National Library of Energy BETA

Sample records for organic light-emitting diodes

  1. Organic light emitting diodes with structured electrodes

    DOE Patents [OSTI]

    Mao, Samuel S.; Liu, Gao; Johnson, Stephen G.

    2012-12-04

    A cathode that contain nanostructures that extend into the organic layer of an OLED has been described. The cathode can have an array of nanotubes or a layer of nanoclusters extending out from its surface. In another arrangement, the cathode is patterned and etched to form protruding nanostructures using a standard lithographic process. Various methods for fabricating these structures are provided, all of which are compatible with large-scale manufacturing. OLEDs made with these novel electrodes have greatly enhanced electron injection, have good environmental stability.

  2. High-Efficiency and Stable White Organic Light-Emitting Diode...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Efficiency and Stable White Organic Light-Emitting Diode Using a Single Emitter High-Efficiency and Stable White Organic Light-Emitting Diode Using a Single Emitter Lead Performer: ...

  3. Organic light-emitting diodes from homoleptic square planar complexes

    DOE Patents [OSTI]

    Omary, Mohammad A

    2013-11-12

    Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").

  4. light-emitting diode

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  5. Phosphorescent organic light emitting diodes with high efficiency and brightness

    DOE Patents [OSTI]

    Forrest, Stephen R; Zhang, Yifan

    2015-11-12

    An organic light emitting device including a) an anode; b) a cathode; and c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV. The organic light emitting device may further include a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode. In some embodiments, the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 .mu.s. In some embodiments, the concentration of the phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.

  6. Electroluminescence property of organic light emitting diode (OLED)

    SciTech Connect (OSTI)

    zdemir, Orhan; Kavak, Pelin; Saatci, A. Evrim; Gkdemir, F. P?nar; Menda, U. Deneb; Can, Nursel; Kutlu, Kubilay; Tekin, Emine; Pravadal?, Selin

    2013-12-16

    Transport properties of electrons and holes were investigated not only in a anthracene-containing poly(p-phenylene-ethynylene)- alt - poly(p-phenylene-vinylene) (PPE-PPV) polymer (AnE-PVstat) light emitting diodes (OLED) but also in an ITO/Ag/polymer/Ag electron and ITO/PEDOT:PSS/polymer/Au hole only devices. Mobility of injected carriers followed the Poole-Frenkel type conduction mechanism and distinguished in the frequency range due to the difference of transit times in admittance measurement. Beginning of light output took place at the turn-on voltage (or flat band voltage), 1.8 V, which was the difference of energy band gap of polymer and two barrier offsets between metals and polymer.

  7. High-Efficiency and Stable White Organic Light-Emitting Diode Using a

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Single Emitter | Department of Energy and Stable White Organic Light-Emitting Diode Using a Single Emitter High-Efficiency and Stable White Organic Light-Emitting Diode Using a Single Emitter Lead Performer: Arizona State University - Tempe, AZ DOE Total Funding: $664,785 Cost Share: $170,547 Project Term: 10/1/2011 - 9/30/2015 Funding Opportunity: Solid State Lighting Core Technology Funding Opportunity Announcement (DE-FOA- 0000329) Project Objective This project will demonstrate an

  8. SciTech Connect: "light emitting diode"

    Office of Scientific and Technical Information (OSTI)

    light emitting diode" Find + Advanced Search Term Search Semantic Search Advanced Search All Fields: "light emitting diode" Semantic Semantic Term Title: Full Text:...

  9. Color stable white phosphorescent organic light emitting diodes with red emissive electron transport layer

    SciTech Connect (OSTI)

    Wook Kim, Jin; Yoo, Seung Il; Sung Kang, Jin; Eun Lee, Song; Kwan Kim, Young; Hwa Yu, Hyeong; Turak, Ayse; Young Kim, Woo

    2015-06-28

    We analyzed the performance of multi-emissive white phosphorescent organic light-emitting diodes (PHOLEDs) in relation to various red emitting sites of hole and electron transport layers (HTL and ETL). The shift of the recombination zone producing stable white emission in PHOLEDs was utilized as luminance was increased with red emission in its electron transport layer. Multi-emissive white PHOLEDs including the red light emitting electron transport layer yielded maximum external quantum efficiency of 17.4% with CIE color coordinates (−0.030, +0.001) shifting only from 1000 to 10 000 cd/m{sup 2}. Additionally, we observed a reduction of energy loss in the white PHOLED via Ir(piq){sub 3} as phosphorescent red dopant in electron transport layer.

  10. Enhancing the emission directionality of organic light-emitting diodes by using photonic microstructures

    SciTech Connect (OSTI)

    Zhang, Shuyu; Turnbull, Graham A., E-mail: gat@st-andrews.ac.uk, E-mail: idws@st-andrews.ac.uk; Samuel, Ifor D. W., E-mail: gat@st-andrews.ac.uk, E-mail: idws@st-andrews.ac.uk [Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)] [Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)

    2013-11-18

    We report microstructured organic light-emitting diodes (OLEDs) with directional emission based on efficient solution-processable europium-OLEDs patterned by solvent assisted microcontact molding. The angle dependence of the light emission is characterized for OLEDs with square-array photonic crystals with periods between 275?nm and 335?nm. The microstructured devices have emission patterns strongly modified from the Lambertian emission of planar OLEDs and can approximately double the emitted power in a desired angle range in both s- and p-polarizations. The modified emission is attributed to light diffracted out of the waveguide modes of the OLEDs.

  11. High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence

    SciTech Connect (OSTI)

    Nishide, Jun-ichi; Hiraga, Yasuhide; Nakanotani, Hajime; Adachi, Chihaya

    2014-06-09

    White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

  12. Horizontal molecular orientation in solution-processed organic light-emitting diodes

    SciTech Connect (OSTI)

    Zhao, L.; Inoue, M.; Komino, T.; Kim, J.-H.; Ribierre, J. C. E-mail: adachi@cstf.kyushu-u.ac.jp [Center for Organic Photonics and Electronics Research , Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395; Japan Science and Technology Agency , ERATO, Adachi Molecular Exciton Engineering Project, c and others

    2015-02-09

    Horizontal orientation of the emission transition dipole moments achieved in glassy vapor-deposited organic thin films leads to an enhancement of the light out-coupling efficiency in organic light-emitting diodes (OLEDs). Here, our combined study of variable angle spectroscopic ellipsometry and angle dependent photoluminescence demonstrates that such a horizontal orientation can be achieved in glassy spin-coated organic films based on a composite blend of a heptafluorene derivative as a dopant and a 4,4′-bis(N-carbazolyl)-1,1′-biphenyl as a host. Solution-processed fluorescent OLEDs with horizontally oriented heptafluorene emitters were then fabricated and emitted deep blue electroluminescence with an external quantum efficiency as high as 5.3%.

  13. Room-temperature spin-polarized organic light-emitting diodes with a single ferromagnetic electrode

    SciTech Connect (OSTI)

    Ding, Baofu, E-mail: b.ding@ecu.edu.au; Alameh, Kamal, E-mail: k.alameh@ecu.edu.au [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup WA 6027 Australia (Australia); Song, Qunliang [Institute for Clean Energy and Advanced Materials, Southwest University, Chongqing 400715 (China)

    2014-05-19

    In this paper, we demonstrate the concept of a room-temperature spin-polarized organic light-emitting diode (Spin-OLED) structure based on (i) the deposition of an ultra-thin p-type organic buffer layer on the surface of the ferromagnetic electrode of the Spin-OLED and (ii) the use of oxygen plasma treatment to modify the surface of that electrode. Experimental results demonstrate that the brightness of the developed Spin-OLED can be increased by 110% and that a magneto-electroluminescence of 12% can be attained for a 150?mT in-plane magnetic field, at room temperature. This is attributed to enhanced hole and room-temperature spin-polarized injection from the ferromagnetic electrode, respectively.

  14. Efficient Light Extraction from Organic Light-Emitting Diodes Using Plasmonic Scattering Layers

    SciTech Connect (OSTI)

    Rothberg, Lewis

    2012-11-30

    Our project addressed the DOE MYPP 2020 goal to improve light extraction from organic light-emitting diodes (OLEDs) to 75% (Core task 6.3). As noted in the 2010 MYPP, the greatest opportunity for improvement is in the extraction of light from [OLED] panels. There are many approaches to avoiding waveguiding limitations intrinsic to the planar OLED structure including use of textured substrates, microcavity designs and incorporating scattering layers into the device structure. We have chosen to pursue scattering layers since it addresses the largest source of loss which is waveguiding in the OLED itself. Scattering layers also have the potential to be relatively robust to color, polarization and angular distributions. We note that this can be combined with textured or microlens decorated substrates to achieve additional enhancement.

  15. Charge injection and accumulation in organic light-emitting diode with PEDOT:PSS anode

    SciTech Connect (OSTI)

    Weis, Martin; Otsuka, Takako; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2015-04-21

    Organic light-emitting diode (OLED) displays using flexible substrates have many attractive features. Since transparent conductive oxides do not fit the requirements of flexible devices, conductive polymer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) has been proposed as an alternative. The charge injection and accumulation in OLED devices with PEDOT:PSS anodes are investigated and compared with indium tin oxide anode devices. Higher current density and electroluminescence light intensity are achieved for the OLED device with a PEDOT:PSS anode. The electric field induced second-harmonic generation technique is used for direct observation of temporal evolution of electric fields. It is clearly demonstrated that the improvement in the device performance of the OLED device with a PEDOT:PSS anode is associated with the smooth charge injection and accumulation.

  16. Nano-honeycomb structured transparent electrode for enhanced light extraction from organic light-emitting diodes

    SciTech Connect (OSTI)

    Shi, Xiao-Bo; Qian, Min; Wang, Zhao-Kui E-mail: lsliao@suda.edu.cn; Liao, Liang-Sheng E-mail: lsliao@suda.edu.cn

    2015-06-01

    A universal nano-sphere lithography method has been developed to fabricate nano-structured transparent electrode, such as indium tin oxide (ITO), for light extraction from organic light-emitting diodes (OLEDs). Perforated SiO{sub 2} film made from a monolayer colloidal crystal of polystyrene spheres and tetraethyl orthosilicate sol-gel is used as a template. Ordered nano-honeycomb pits on the ITO electrode surface are obtained by chemical etching. The proposed method can be utilized to form large-area nano-structured ITO electrode. More than two folds' enhancement in both current efficiency and power efficiency has been achieved in a red phosphorescent OLED which was fabricated on the nano-structured ITO substrate.

  17. White organic light-emitting diodes with 4 nm metal electrode

    SciTech Connect (OSTI)

    Lenk, Simone; Schwab, Tobias; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl; Reineke, Sebastian; Gather, Malte C.

    2015-10-19

    We investigate metal layers with a thickness of only a few nanometers as anode replacement for indium tin oxide (ITO) in white organic light-emitting diodes (OLEDs). The ultrathin metal electrodes prove to be an excellent alternative that can, with regard to the angular dependence and efficiency of the OLED devices, outperform the ITO reference. Furthermore, unlike ITO, the thin composite metal electrodes are readily compatible with demanding architectures (e.g., top-emission or transparent OLEDs, device unit stacking, etc.) and flexible substrates. Here, we compare the sheet resistance of both types of electrodes on polyethylene terephthalate for different bending radii. The electrical performance of ITO breaks down at a radius of 10 mm, while the metal electrode remains intact even at radii smaller than 1 mm.

  18. Ultrastrong light-matter coupling in electrically doped microcavity organic light emitting diodes

    SciTech Connect (OSTI)

    Mazzeo, M.; Genco, A.; Gambino, S.; Ballarini, D.; Mangione, F.; Sanvitto, D.; Di Stefano, O.; Patanè, S.; Savasta, S.; Gigli, G.

    2014-06-09

    The coupling of the electromagnetic field with an electronic transition gives rise, for strong enough light-matter interactions, to hybrid states called exciton-polaritons. When the energy exchanged between light and matter becomes a significant fraction of the material transition energy an extreme optical regime called ultrastrong coupling (USC) is achieved. We report a microcavity embedded p-i-n monolithic organic light emitting diode working in USC, employing a thin film of squaraine dye as active layer. A normalized coupling ratio of 30% has been achieved at room temperature. These USC devices exhibit a dispersion-less angle-resolved electroluminescence that can be exploited for the realization of innovative optoelectronic devices. Our results may open the way towards electrically pumped polariton lasers.

  19. Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

    SciTech Connect (OSTI)

    Chang, Y. L. Gong, S. White, R.; Lu, Z. H.; Wang, X.; Wang, S.; Yang, C.

    2014-04-28

    We have demonstrated high-efficiency greenish-blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a dimesitylboryl-functionalized C^N chelate Pt(II) phosphor, Pt(m-Bptrz)(t-Bu-pytrz-Me). Using a high triplet energy platform and optimized double emissive zone device architecture results in greenish-blue PHOLEDs that exhibit an external quantum efficiency of 24.0% and a power efficiency of 55.8?lm/W. This record high performance is comparable with that of the state-of-the-art Ir-based sky-blue organic light-emitting diodes.

  20. Broadband light-emitting diode

    DOE Patents [OSTI]

    Fritz, Ian J.; Klem, John F.; Hafich, Michael J.

    1998-01-01

    A broadband light-emitting diode. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3-2 .mu.m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-division-multiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft.

  1. Broadband light-emitting diode

    DOE Patents [OSTI]

    Fritz, I.J.; Klem, J.F.; Hafich, M.J.

    1998-07-14

    A broadband light-emitting diode is disclosed. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3--2 {micro}m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-divisionmultiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft. 10 figs.

  2. High efficiency and brightness fluorescent organic light emitting diode by triplet-triplet fusion

    DOE Patents [OSTI]

    Forrest, Stephen; Zhang, Yifan

    2015-02-10

    A first device is provided. The first device further comprises an organic light emitting device. The organic light emitting device further comprises an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer may include an organic host compound and at least one organic emitting compound capable of fluorescent emission at room temperature. Various configurations are described for providing a range of current densities in which T-T fusion dominates over S-T annihilation, leading to very high efficiency fluorescent OLEDs.

  3. Quantum Dot Light Emitting Diode

    SciTech Connect (OSTI)

    Keith Kahen

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  4. Quantum Dot Light Emitting Diode

    SciTech Connect (OSTI)

    Kahen, Keith

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  5. Soft holographic interference lithography microlens for enhanced organic light emitting diode light extraction

    SciTech Connect (OSTI)

    Park, Joong-Mok; Gan, Zhengqing; Leung, Wai Y.; Liu, Rui; Ye, Zhuo; Constant, Kristen; Shinar, Joseph; Shinar, Ruth; Ho, Kai-Ming

    2011-06-06

    Very uniform 2 {micro}m-pitch square microlens arrays ({micro}LAs), embossed on the blank glass side of an indium-tin-oxide (ITO)-coated 1.1 mm-thick glass, are used to enhance light extraction from organic light-emitting diodes (OLEDs) by {approx}100%, significantly higher than enhancements reported previously. The array design and size relative to the OLED pixel size appear to be responsible for this enhancement. The arrays are fabricated by very economical soft lithography imprinting of a polydimethylsiloxane (PDMS) mold (itself obtained from a Ni master stamp that is generated from holographic interference lithography of a photoresist) on a UV-curable polyurethane drop placed on the glass. Green and blue OLEDs are then fabricated on the ITO to complete the device. When the {mu}LA is {approx}15 x 15 mm{sup 2}, i.e., much larger than the {approx}3 x 3 mm{sup 2} OLED pixel, the electroluminescence (EL) in the forward direction is enhanced by {approx}100%. Similarly, a 19 x 25 mm{sup 2} {mu}LA enhances the EL extracted from a 3 x 3 array of 2 x 2 mm{sup 2} OLED pixels by 96%. Simulations that include the effects of absorption in the organic and ITO layers are in accordance with the experimental results and indicate that a thinner 0.7 mm thick glass would yield a {approx}140% enhancement.

  6. Anomalous hole injection deterioration of organic light-emitting diodes with a manganese phthalocyanine layer

    SciTech Connect (OSTI)

    Lee, Hyunbok; Lee, Jeihyun; Yi, Yeonjin; Cho, Sang Wan; Kim, Jeong Won

    2015-01-21

    Metal phthalocyanines (MPcs) are well known as an efficient hole injection layer (HIL) in organic devices. They possess a low ionization energy, and so the low-lying highest occupied molecular orbital (HOMO) gives a small hole injection barrier from an anode in organic light-emitting diodes. However, in this study, we show that the hole injection characteristics of MPc are not only determined by the HOMO position but also significantly affected by the wave function distribution of the HOMO. We show that even with the HOMO level of a manganese phthalocyanine (MnPc) HIL located between the Fermi level of an indium tin oxide anode and the HOMO level of a N,N?-bis(1-naphthyl)-N,N?-diphenyl-1,1?-biphenyl-4,4?-diamine hole transport layer the device performance with the MnPc HIL is rather deteriorated. This anomalous hole injection deterioration is due to the contracted HOMO wave function, which leads to small intermolecular electronic coupling. The origin of this contraction is the significant contribution of the Mn d-orbital to the MnPc HOMO.

  7. Fabrication and Characterization of New Hybrid Organic Light Emitting Diode (OLED): Europium-picrate-triethylene oxide Complex

    SciTech Connect (OSTI)

    Sarjidan, M. A. Mohd; Abu Zakaria, N. Z. A.; Abd. Majid, W. H. [Solid State Research Laboratory, Department of Physics, University of Malaya, 50603, Kuala Lumpur (Malaysia); Kusrini, Eny; Saleh, M. I. [School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2009-07-07

    Thin-film light emitting devices based on organic materials have attracted vast interest in applications such as light emitting diode (LED) and flat-panel display. The organic material can be attached with inorganic material to enhance the performance of the light emitting device. A hybrid OLED based on a new complex of europium picrate (Eu-pic) with triethylene oxide (EO3) ligand is fabricated. The OLED is fabricated by using spin coating technique with acetone as the solvent and aluminum as the top electrode. The optical, photoluminescence (PL) and electrical properties of the sample are carried out by UV-Vis spectroscopy (Jasco V-750), luminescence spectroscopy (Perkin Elmer LS-500) and source measure unit (SMU)(Keithly), respectively.

  8. Quantum efficiency harmonic analysis of exciton annihilation in organic light emitting diodes

    SciTech Connect (OSTI)

    Price, J. S.; Giebink, N. C.

    2015-06-29

    Various exciton annihilation processes are known to impact the efficiency roll-off of organic light emitting diodes (OLEDs); however, isolating and quantifying their contribution in the presence of other factors such as changing charge balance continue to be a challenge for routine device characterization. Here, we analyze OLED electroluminescence resulting from a sinusoidal dither superimposed on the device bias and show that nonlinearity between recombination current and light output arising from annihilation mixes the quantum efficiency measured at different dither harmonics in a manner that depends uniquely on the type and magnitude of the annihilation process. We derive a series of analytical relations involving the DC and first harmonic external quantum efficiency that enable annihilation rates to be quantified through linear regression independent of changing charge balance and evaluate them for prototypical fluorescent and phosphorescent OLEDs based on the emitters 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran and platinum octaethylporphyrin, respectively. We go on to show that, in most cases, it is sufficient to calculate the needed quantum efficiency harmonics directly from derivatives of the DC light versus current curve, thus enabling this analysis to be conducted solely from standard light-current-voltage measurement data.

  9. Dopant effects on charge transport to enhance performance of phosphorescent white organic light emitting diodes

    SciTech Connect (OSTI)

    Zhu, Liping; Chen, Jiangshan; Ma, Dongge

    2015-11-07

    We compared the performance of phosphorescent white organic light emitting diodes (WOLEDs) with red-blue-green and green-blue-red sequent emissive layers. It was found that the influence of red and green dopants on electron and hole transport in emissive layers leads to the large difference in the efficiency of fabricated WOLEDs. This improvement mechanism is well investigated by the current density-voltage characteristics of single-carrier devices based on dopant doped emissive layers and the comparison of electroluminescent and photoluminescence spectra, and attributed to the different change of charge carrier transport by the dopants. The optimized device achieves a maximum power efficiency, current efficiency, and external quantum efficiency of 37.0 lm/W, 38.7 cd/A, and 17.7%, respectively, which are only reduced to 32.8 lm/W, 38.5 cd/A, and 17.3% at 1000 cd/m{sup 2} luminance. The critical current density is as high as 210 mA/cm{sup 2}. It can be seen that the efficiency roll-off in phosphorescent WOLEDs can be well improved by effectively designing the structure of emissive layers.

  10. Simulations of emission from microcavity tandem organic light-emitting diodes

    SciTech Connect (OSTI)

    Biswas, Rana; Xu, Chun; Zhao, Weijun; Liu, Rui; Shinar, Ruth; Shinar, Joseph

    2011-01-01

    Microcavity tandem organic light-emitting diodes (OLEDs) are simulated and compared to experimental results. The simulations are based on two complementary techniques: rigorous finite element solutions of Maxwell's equations and Fourier space scattering matrix solutions. A narrowing and blue shift of the emission spectrum relative to the noncavity single unit OLED is obtained both theoretically and experimentally. In the simulations, a distribution of emitting sources is placed near the interface of the electron transport layer tris(8-hydroxyquinoline) Al (Alq{sub 3}) and the hole transport layer (N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine) ({alpha}-NPB). Far-field electric field intensities are simulated. The simulated widths of the emission peaks also agree with the experimental results. The simulations of the 2-unit tandem OLEDs shifted the emission to shorter wavelength, in agreement with experimental measurements. The emission spectra's dependence on individual layer thicknesses also agreed well with measurements. Approaches to simulate and improve the light emission intensity from these OLEDs, in particular for white OLEDs, are discussed.

  11. Analyzing degradation effects of organic light-emitting diodes via transient optical and electrical measurements

    SciTech Connect (OSTI)

    Schmidt, Tobias D. Jger, Lars; Brtting, Wolfgang; Noguchi, Yutaka; Ishii, Hisao

    2015-06-07

    Although the long-term stability of organic light-emitting diodes (OLEDs) under electrical operation made significant progress in recent years, the fundamental underlying mechanisms of the efficiency decrease during operation are not well understood. Hence, we present a comprehensive degradation study of an OLED structure comprising the well-known green phosphorescent emitter Ir(ppy){sub 3}. We use transient methods to analyze both electrical and optical changes during an accelerated aging protocol. Combining the results of displacement current measurements with time-resolved investigation of the excited states lifetimes of the emitter allows for a correlation of electrical (e.g., increase of the driving voltage due to trap formation) and optical (e.g., decrease of light-output) changes induced by degradation. Therewith, it is possible to identify two mechanisms resulting in the drop of the luminance: a decrease of the radiative quantum efficiency of the emitting system due to triplet-polaron-quenching at trapped charge carriers and a modified charge carrier injection and transport, as well as trap-assisted non-radiative recombination resulting in a deterioration of the charge carrier balance of the device.

  12. Demonstration Assessment of Light-Emitting Diode (LED) Freezer...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Demonstration Assessment of Light-Emitting Diode (LED) Freezer Case Lighting Demonstration Assessment of Light-Emitting Diode (LED) Freezer Case Lighting This document is a report ...

  13. OLED Fundamentals: Materials, Devices, and Processing of Organic Light-Emitting Diodes

    SciTech Connect (OSTI)

    Blochwitz-Nimoth, Jan; Bhandari, Abhinav; Boesch, Damien; Fincher, Curtis R.; Gaspar, Daniel J.; Gotthold, David W.; Greiner, Mark T.; Kido, Junji; Kondakov, Denis; Korotkov, Roman; Krylova, Valentina A.; Loeser, Falk; Lu, Min-Hao; Lu, Zheng-Hong; Lussem, Bjorn; Moro, Lorenza; Padmaperuma, Asanga B.; Polikarpov, Evgueni; Rostovtsev, Vsevolod V.; Sasabe, Hisahiro; Silverman, Gary; Thompson, Mark E.; Tietze, Max; Tyan, Yuan-Sheng; Weaver, Michael; Xin , Xu; Zeng, Xianghui

    2015-05-26

    What is an organic light emitting diode (OLED)? Why should we care? What are they made of? How are they made? What are the challenges in seeing these devices enter the marketplace in various applications? These are the questions we hope to answer in this book, at a level suitable for knowledgeable non-experts, graduate students and scientists and engineers working in the field who want to understand the broader context of their work. At the most basic level, an OLED is a promising new technology composed of some organic material sandwiched between two electrodes. When current is passed through the device, light is emitted. The stack of layers can be very thin and has many variations, including flexible and/or transparent. The organic material can be polymeric or composed small molecules, and may include inorganic components. The electrodes may consist of metals, metal oxides, carbon nanomaterials, or other species, though of course for light to be emitted, one electrode must be transparent. OLEDs may be fabricated on glass, metal foils, or polymer sheets (though polymeric substrates must be modified to protect the organic material from moisture or oxygen). In any event, the organic material must be protected from moisture during storage and operation. A control circuit, the exact nature of which depends on the application, drives the OLED. Nevertheless, the control circuit should have very stable current control to generate uniform light emission. OLEDs can be designed to emit a single color of light, white light, or even tunable colors. The devices can be switched on and off very rapidly, which makes them suitable for displays or for general lighting. Given the amazing complexity of the technical and design challenges for practical OLED applications, it is not surprising that applications are still somewhat limited. Although organic electroluminescence is more than 50 years old, the modern OLED field is really only about half that age – with the first high

  14. Moisture exposure to different layers in organic light-emitting diodes and the effect on electroluminescence characteristics

    SciTech Connect (OSTI)

    Liao, L. S.; Tang, C. W.

    2008-08-15

    Moisture effect on electroluminescence characteristics, including current density versus voltage, luminance versus voltage, luminous efficiency versus current density, dark spot formation, and operational stability of organic light-emitting diodes, has been systematically investigated by exposing each layer of the devices to moisture at room temperature. Moisture has a different effect on each of the interfaces or surfaces, and the influence increases as exposure time increases. There is a slight effect on the electroluminescence characteristics after the anode surface has been exposed to moisture. However, severe luminance decrease, dark spot formation, and operational stability degradation take place after the light-emitting layer or the electron-transporting layer is exposed to moisture. It is also demonstrated that the effect of moisture can be substantially reduced if the exposure to moisture is in a dark environment.

  15. MoO3 as combined hole injection layer and tapered spacer in combinatorial multicolor microcavity organic light emitting diodes

    SciTech Connect (OSTI)

    Liu, R.; Xu, Chun; Biswas, Rana; Shinar, Joseph; Shinar, Ruth

    2011-09-01

    Multicolor microcavity ({mu}C) organic light-emitting diode (OLED) arrays were fabricated simply by controlling the hole injection and spacer MoO{sub 3} layer thickness. The normal emission was tunable from {approx}490 to 640 nm and can be further expanded. A compact, integrated spectrometer with two-dimensional combinatorial arrays of {mu}C OLEDs was realized. The MoO{sub 3} yields more efficient and stable devices, revealing a new breakdown mechanism. The pixel current density reaches {approx}4 A/cm{sup 2} and a maximal normal brightness {approx}140 000 Cd/m{sup 2}, which improves photoluminescence-based sensing and absorption measurements.

  16. Simulation of mixed-host emitting layer based organic light emitting diodes

    SciTech Connect (OSTI)

    Riku, C.; Kee, Y. Y.; Ong, T. S.; Tou, T. Y.; Yap, S. S.

    2015-04-24

    ‘SimOLED’ simulator is used in this work to investigate the efficiency of the mixed-host organic light emitting devices (MH-OLEDs). Tris-(8-hydroxyquinoline) aluminum(3) (Alq{sub 3}) and N,N-diphenyl-N,N-Bis(3-methylphenyl)-1,1-diphenyl-4,4-diamine (TPD) are used as the electron transport layer (ETL) material and hole transport layer (HTL) material respectively, and the indium-doped tin oxide (ITO) and aluminum (Al) as anode and cathode. Three MH-OLEDs, A, B and C with the same structure of ITO / HTM (15 nm) / Mixed host (70 nm) / ETM (10 nm) /Al, are stimulated with ratios TPD:Alq{sub 3} of 3:5, 5:5, and 5:3 respectively. The Poole-Frenkel model for electron and hole mobilities is employed to compute the current density-applied voltage-luminance characteristics, distribution of the electric field, carrier concentrations and recombination rate.

  17. Low-cost electrochemical treatment of indium tin oxide anodes for high-efficiency organic light-emitting diodes

    SciTech Connect (OSTI)

    Hui Cheng, Chuan, E-mail: chengchuanhui@dlut.edu.cn; Shan Liang, Ze; Gang Wang, Li; Dong Gao, Guo; Zhou, Ting; Ming Bian, Ji; Min Luo, Ying [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Tong Du, Guo, E-mail: dugt@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2014-01-27

    We demonstrate a simple low-cost approach as an alternative to conventional O{sub 2} plasma treatment to modify the surface of indium tin oxide (ITO) anodes for use in organic light-emitting diodes. ITO is functionalized with F{sup ?} ions by electrochemical treatment in dilute hydrofluoric acid. An electrode with a work function of 5.2?eV is achieved following fluorination. Using this electrode, a maximum external quantum efficiency of 26.0% (91?cd/A, 102?lm/W) is obtained, which is 12% higher than that of a device using the O{sub 2} plasma-treated ITO. Fluorination also increases the transparency in the near-infrared region.

  18. Highly efficient inverted top emitting organic light emitting diodes using a transparent top electrode with color stability on viewing angle

    SciTech Connect (OSTI)

    Kim, Jung-Bum; Lee, Jeong-Hwan; Moon, Chang-Ki; Kim, Jang-Joo, E-mail: jjkim@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-02-17

    We report a highly efficient phosphorescent green inverted top emitting organic light emitting diode with excellent color stability by using the 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile/indium zinc oxide top electrode and bis(2-phenylpyridine)iridium(III) acetylacetonate as the emitter in an exciplex forming co-host system. The device shows a high external quantum efficiency of 23.4% at 1000?cd/m{sup 2} corresponding to a current efficiency of 110?cd/A, low efficiency roll-off with 21% at 10?000?cd/m{sup 2} and low turn on voltage of 2.4?V. Especially, the device showed very small color change with the variation of ?x?=?0.02, ?y?=?0.02 in the CIE 1931 coordinates as the viewing angle changes from 0 to 60. The performance of the device is superior to that of the metal/metal cavity structured device.

  19. Tetra-methyl substituted copper (II) phthalocyanine as a hole injection enhancer in organic light-emitting diodes

    SciTech Connect (OSTI)

    Wang, Yu-Long; Xu, Jia-Ju; Lin, Yi-Wei; Chen, Qian; Shan, Hai-Quan; Xu, Zong-Xiang E-mail: val.roy@cityu.edu.hk; Yan, Yan; Roy, V. A. L. E-mail: val.roy@cityu.edu.hk

    2015-10-15

    We have enhanced hole injection and lifetime in organic light-emitting diodes (OLEDs) by incorporating the isomeric metal phthalocyanine, CuMePc, as a hole injection enhancer. The OLED devices containing CuMePc as a hole injection layer (HIL) exhibited higher luminous efficiency and operational lifetime than those using a CuPc layer and without a HIL. The effect of CuMePc thickness on device performance was investigated. Atomic force microscope (AFM) studies revealed that the thin films were smooth and uniform because the mixture of CuMePc isomers depressed crystallization within the layer. This may have caused the observed enhanced hole injection, indicating that CuMePc is a promising HIL material for highly efficient OLEDs.

  20. Spectrally resolved hyperfine interactions between polaron and nuclear spins in organic light emitting diodes: Magneto-electroluminescence studies

    SciTech Connect (OSTI)

    Crooker, S. A.; Kelley, M. R.; Martinez, N. J. D.; Nie, W.; Mohite, A.; Nayyar, I. H.; Tretiak, S.; Smith, D. L.; Liu, F.; Ruden, P. P.

    2014-10-13

    We use spectrally resolved magneto-electroluminescence (EL) measurements to study the energy dependence of hyperfine interactions between polaron and nuclear spins in organic light-emitting diodes. Using layered devices that generate bright exciplex emission, we show that the increase in EL emission intensity I due to small applied magnetic fields of order 100 mT is markedly larger at the high-energy blue end of the EL spectrum (ΔI/I ∼ 11%) than at the low-energy red end (∼4%). Concurrently, the widths of the magneto-EL curves increase monotonically from blue to red, revealing an increasing hyperfine coupling between polarons and nuclei and directly providing insight into the energy-dependent spatial extent and localization of polarons.

  1. Large-scale patterning of indium tin oxide electrodes for guided mode extraction from organic light-emitting diodes

    SciTech Connect (OSTI)

    Geyer, Ulf; Hauss, Julian; Riedel, Boris; Gleiss, Sebastian; Lemmer, Uli; Gerken, Martina

    2008-11-01

    We describe a cost-efficient and large area scalable production process of organic light-emitting diodes (OLEDs) with photonic crystals (PCs) as extraction elements for guided modes. Using laser interference lithography and physical plasma etching, we texture the indium tin oxide (ITO) electrode layer of an OLED with one- and two-dimensional PC gratings. By optical transmission measurements, the resonant mode of the grating is shown to have a drift of only 0.4% over the 5 mm length of the ITO grating. By changing the lattice constant between 300 and 600 nm, the OLED emission angle of enhanced light outcoupling is tailored from -24.25 deg. to 37 deg. At these angles, the TE emission is enhanced up to a factor of 2.14.

  2. Operating organic light-emitting diodes imaged by super-resolution spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    King, John T.; Granick, Steve

    2016-06-21

    Super-resolution stimulated emission depletion microscopy is adapted here for materials characterization that would not otherwise be possible. With the example of organic lightemitting diodes (OLEDs), spectral imaging with pixel-by-pixel wavelength discrimination allows us to resolve local-chain environment encoded in the spectral response of the semiconducting polymer, and correlate chain packing with local electroluminescence by using externally applied current as the excitation source. We observe nanoscopic defects that would be unresolvable by traditional microscopy. They are revealed in electroluminescence maps in operating OLEDs with 50 nm spatial resolution. We find that brightest emission comes from regions with more densely packed chains.more » Conventional microscopy of an operating OLED would lack the resolution needed to discriminate these features, while traditional methods to resolve nanoscale features generally cannot be performed when the device is operating. Furthermore, this points the way towards real-time analysis of materials design principles in devices as they actually operate.« less

  3. Organic Light-Emitting Diodes (OLEDs) and Optically-Detected Magnetic Resonance (ODMR) studies on organic materials

    SciTech Connect (OSTI)

    Cai, Min

    2011-11-30

    Organic semiconductors have evolved rapidly over the last decades and currently are considered as the next-generation technology for many applications, such as organic light-emitting diodes (OLEDs) in flat-panel displays (FPDs) and solid state lighting (SSL), and organic solar cells (OSCs) in clean renewable energy. This dissertation focuses mainly on OLEDs. Although the commercialization of the OLED technology in FPDs is growing and appears to be just around the corner for SSL, there are still several key issues that need to be addressed: (1) the cost of OLEDs is very high, largely due to the costly current manufacturing process; (2) the efficiency of OLEDs needs to be improved. This is vital to the success of OLEDs in the FPD and SSL industries; (3) the lifetime of OLEDs, especially blue OLEDs, is the biggest technical challenge. All these issues raise the demand for new organic materials, new device structures, and continued lower-cost fabrication methods. In an attempt to address these issues, we used solution-processing methods to fabricate highly efficient small molecule OLEDs (SMOLEDs); this approach is costeffective in comparison to the more common thermal vacuum evaporation. We also successfully made efficient indium tin oxide (ITO)-free SMOLEDs to further improve the efficiency of the OLEDs. We employed the spin-dependent optically-detected magnetic resonance (ODMR) technique to study the luminescence quenching processes in OLEDs and organic materials in order to understand the intrinsic degradation mechanisms. We also fabricated polymer LEDs (PLEDs) based on a new electron-accepting blue-emitting polymer and studied the effect of molecular weight on the efficiency of PLEDs. All these studies helped us to better understand the underlying relationship between the organic semiconductor materials and the OLEDs’ performance, and will subsequently assist in further enhancing the efficiency of OLEDs. With strongly improved device performance (in addition to

  4. Low-Cost Light-Emitting Diode Luminaire for General Illumination

    Broader source: Energy.gov [DOE]

    This project is demonstrating an efficient and stable white organic light-emitting diode (WOLED) using a single emitter on a planar glass substrate.

  5. Highly transparent and conductive double-layer oxide thin films as anodes for organic light-emitting diodes

    SciTech Connect (OSTI)

    Yang Yu; Wang Lian; Yan He; Jin Shu; Marks, Tobin J.; Li Shuyou

    2006-07-31

    Double-layer transparent conducting oxide thin film structures containing In-doped CdO (CIO) and Sn-doped In{sub 2}O{sub 3} (ITO) layers were grown on glass by metal-organic chemical vapor deposition and ion-assisted deposition (IAD), respectively, and used as anodes for polymer light-emitting diodes (PLEDs). These films have a very low overall In content of 16 at. %. For 180-nm-thick CIO/ITO films, the sheet resistance is 5.6 {omega}/{open_square}, and the average optical transmittance is 87.1% in the 400-700 nm region. The overall figure of merit ({phi}=T{sup 10}/R{sub sheet}) of the double-layer CIO/ITO films is significantly greater than that of single-layer CIO, IAD-ITO, and commercial ITO films. CIO/ITO-based PLEDs exhibit comparable or superior device performance versus ITO-based control devices. CIO/ITO materials have a much lower sheet resistance than ITO, rendering them promising low In content electrode materials for large-area optoelectronic devices.

  6. Role of chemical reactions of arylamine hole transport materials in operational degradation of organic light-emitting diodes

    SciTech Connect (OSTI)

    Kondakov, Denis Y.

    2008-10-15

    We report that the representative arylamine hole transport materials undergo chemical transformations in operating organic light-emitting diode (OLED) devices. Although the underlying chemical mechanisms are too complex to be completely elucidated, structures of several identified degradation products point at dissociations of relatively weak carbon-nitrogen and carbon-carbon bonds in arylamine molecules as the initiating step. Considering the photochemical reactivities, the bond dissociation reactions of arylamines occur by the homolysis of the lowest singlet excited states formed by recombining charge carriers in the operating OLED device. The subsequent chemical reactions are likely to yield long-lived, stabilized free radicals capable of acting as deep traps--nonradiative recombination centers and fluorescence quenchers. Their presence in the hole transport layer results in irreversible hole trapping and manifests as a positive fixed charge. The extent and localization of chemical transformations in several exemplary devices suggest that the free radical reactions of hole transporting materials, arylamines, can be sufficient to account for the observed luminance efficiency loss and voltage rise in operating OLEDs. The relative bond strengths and excited state energies of OLED materials appear to have a determining effect on the operational stability of OLED devices.

  7. Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities

    SciTech Connect (OSTI)

    Kuwae, Hiroyuki; Kasahara, Takashi; Nitta, Atsushi; Yoshida, Kou; Inoue, Munetomo; Matsushima, Toshinori; Adachi, Chihaya; Shoji, Shuichi; Mizuno, Jun

    2015-10-21

    We developed organic light-emitting diodes (OLEDs) with nanopatterned current flow regions using electron-beam lithography with the aim of suppressing singlet–polaron annihilation (SPA). Nanopatterns composed of lines and circles were used in the current flow regions of nano-line and nano-dot OLEDs, respectively. Excitons partially escape from the current flow regions where SPA takes place. As such, current densities where external quantum efficiencies were half of their initial values (J{sub 0}) increased as line width and circle diameter were decreased to close to the exciton diffusion length. Circles were more efficient at enhancing exciton escape and increasing J{sub 0} than lines. The J{sub 0} increase in the nano-dot OLEDs containing nanopatterned circles with a diameter of 50 nm was approximately 41-fold that of a conventional OLED with a current flow region of 4 mm{sup 2}. The dependence of J{sub 0} on the size and shape of the nanopatterns was well explained by an SPA model that considered exciton diffusion. Nanopatterning of OLEDs is a feasible method of obtaining large J{sub 0}.

  8. White top-emitting organic light-emitting diodes with solution-processed nano-particle scattering layers

    SciTech Connect (OSTI)

    Schaefer, Tim; Schwab, Tobias; Lenk, Simone; Gather, Malte C.

    2015-12-07

    A random scattering approach to enhance light extraction in white top-emitting organic light-emitting diodes (OLEDs) is reported. Through solution processing from fluorinated solvents, a nano-particle scattering layer (NPSL) can be deposited directly on top of small molecule OLEDs without affecting their electrical performance. The scattering length for light inside the NPSL is determined from transmission measurements and found to be in agreement with Mie scattering theory. Furthermore, the dependence of the light outcoupling enhancement on electron transport layer thickness is studied. Depending on the electron transport layer thickness, the NPSL enhances the external quantum efficiency of the investigated white OLEDs by between 1.5 and 2.3-fold. For a device structure that has been optimized prior to application of the NPSL, the maximum external quantum efficiency is improved from 4.7% to 7.4% (1.6-fold improvement). In addition, the scattering layer strongly reduces the undesired shift in emission color with viewing angle.

  9. Highly-selective wettability on organic light-emitting-diodes patterns by sequential low-power plasmas

    SciTech Connect (OSTI)

    Svarnas, P.; Edwards, A. J.; Bradley, J. W.; Yang, L.; Munz, M.; Shard, A. G.

    2010-05-15

    Patterned organic light-emitting-diode substrates were treated by oxygen (O{sub 2}) and tetrafluoromethane (CF{sub 4}) radio-frequency (rf, 13.56 MHz) plasmas of low-power (close to 1 W) that were capacitively-coupled. An unexpected wettability contrast (water contact angle difference up to 90 deg. ) between the indium-tin-oxide anode and the bank resist regions was achieved, providing excellent conditioning prior to the ink-jet printing. This selectivity was found to be adjustable by varying the relative exposure time to the O{sub 2} and CF{sub 4} sequential plasmas. Static contact angle measurements and extensive x-ray photoelectron spectroscopy analyses showed that the wetting properties depend on the carbon and fluorine chemical functional groups formed at the outermost surface layers, whereas atomic force microscopy images did not show a morphological change. Plasma optical emission spectroscopy and ion mass spectroscopy suggested that surface functionalization was initiated by energy transfer from ionic species (O{sup +}, O{sub 2}{sup +}, CF{sup +}, CF{sub 2}{sup +}, and CF{sub 3}{sup +}) and excited neutrals (O{sup *} and F{sup *}). The absolute ion fluxes measured on the substrates were up to 10{sup 14} cm{sup -2} s{sup -1} and the ion energies up to 20 eV, despite the low powers applied during the process.

  10. The effect of the hole injection layer on the performance of single layer organic light-emitting diodes

    SciTech Connect (OSTI)

    Wenjin, Zeng; Ran, Bi; Hongmei, Zhang E-mail: iamwhuang@njupt.edu.cn; Wei, Huang E-mail: iamwhuang@njupt.edu.cn

    2014-12-14

    Efficient single-layer organic light-emitting diodes (OLEDs) were reported based on a green fluorescent dye 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7tetramethyl-1H,5H,11H-(1) benzopyropyrano (6,7-8-I,j)quinolizin-11-one (C545T). Herein, poly(3,4-ethylenedioxy thiophene) poly(styrene sulfonate) were, respectively, applied as the injection layer for comparison. The hole transport properties of the emission layer with different hole injection materials are well investigated via current-voltage measurement. It was clearly found that the hole injection layers (HILs) play an important role in the adjustment of the electron/hole injection to attain transport balance of charge carriers in the single emission layer of OLEDs with electron-transporting host. The layer of tris-(8-hydroxyquinoline) aluminum played a dual role of host and electron-transporting materials within the emission layer. Therefore, appropriate selection of hole injection layer is a key factor to achieve high efficiency OLEDs with single emission layer.

  11. Energy Savings Estimates of Light Emitting Diodes | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Estimates of Light Emitting Diodes Energy Savings Estimates of Light Emitting Diodes This report is an analysis of niche markets and applications for light emitting diodes (LEDs), undertaken on behalf of the U.S. Department of Energy nichefinalreport_january2011.pdf (677.78 KB) More Documents & Publications LED ADOPTION REPORT Energy Savings Potential of Solid-State Lighting in General Illumination Applications - Report 2010 U.S. Lighting Market Characterization

  12. Organic light emitting diodes (OLEDS) and OLED-based structurally integrated optical sensors

    SciTech Connect (OSTI)

    Cai, Yuankun

    2010-05-16

    microheterogeneity. Effect of TiO{sub 2} doping was also discussed. Stretched exponential analysis also generates calibration curves with higher sensitivity, which is preferred from the operational point of view. The work of enhanced integration was shown in chapter 7 with a polymer photodetector, which enables the preferred operation mode, decay time measurement, due to fast reponse (<20 {mu}s). Device thickness was enlarged for maximum absorption of the PL, which was realized by slow spincoating rate and shorter spincoating time. Film prepared this way shows more crystalline order by Raman spectra, probably due to slow evaporation. This also ensures charge transport is not affected even with a thick film as indicated in the response time. Combination of OLEDs and polymer photodetectors present opportunities for solution processed all-organic sensors, which enables cheap processing at large scale. Future development can focus on monolithically integration of OLEDs and organic photodetectors (OPD) on the same substrate at a small scale, which could be enabled by inkjet printing. As OLED and OPD technologies continue to advance, small-sized, flexible and all-organic structurally integrated sensor platforms will become true in the near future.

  13. Studies of solution-processed organic light-emitting diodes and their materials

    SciTech Connect (OSTI)

    Hellerich, Emily

    2013-01-01

    A hitherto unexplored approach is presented in which a small molecule is used as a host to polymer guests in solution-processed OLEDs. We find that the small molecule host results in much more efficient devices than the often-used alternative polymer host when used for the guests presented. It is likely that nano- and microstructural differences between the hosts contribute to the improvements, which highlights some interesting characteristics that can help to better understand the nature of these mixtures. A number of the guests used in this study were newly synthesized benzobisoxazole-based copolymers. New organic copolymers are presented that are based on the chemical structure of benzobisoxazoles, which have been shown in the past to have good electron transporting properties. The novel concept in this publication pertains to a change in the direction of polymerization, also known as the conjugation pathway, which we show increases the emission efficiency. This work highlights a unique and useful property of organic semiconducting materials in that they can be synthesized to create the desired characteristics. Earlier work is described that kick-started in our research group the use of small molecules in solution-processed OLEDs. Originally these devices were to be used in magnetoresistance studies, but the project took a different path when the devices were more efficient than expected. The efficient use of small molecules in solution-processed OLEDs is highlighted, which at the time was not often the case. Also, the important observation of the effect of solvent choice on the resultant film is emphasized, with discussion of the likely cause of these effects. Microcavity OLEDs are introduced in which the transparent anode ITO is replaced with semi-transparent thin silver, which creates an optical cavity within the devices. The goal was to expand a previous work that created an on-chip spectrometer covering wavelengths 493 to 639 nm. In this case, a spin

  14. Test Procedures for Integrated Light-Emitting Diode Lamps; Final...

    Broader source: Energy.gov (indexed) [DOE]

    Test Procedures for Integrated Light-Emitting Diode Lamps - Final Rule (532.58 KB) More Documents & Publications ISSUANCE 2015-06-25: Energy Conservation Program: Test Procedures ...

  15. Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate

    Broader source: Energy.gov [DOE]

    This project is producing high-efficiency semipolar light-emitting diodes (LEDs) on low-defect bulk gallium nitride (GaN) substrates.

  16. Energy Savings Estimates of Light Emitting Diodes in Niche Lighting...

    Broader source: Energy.gov (indexed) [DOE]

    Estimates of Light Emitting Diodes in Niche Lighting Applications Prepared for: Building Technologies Program Office of Energy Efficiency and Renewable Energy U.S. Department of ...

  17. Evaluation and prediction of color-tunable organic light-emitting diodes based on carrier/exciton adjusting interlayer

    SciTech Connect (OSTI)

    Liu, Shengqiang; Li, Jie; Yu, Junsheng; Du, Chunlei

    2015-07-27

    A color tuning index (I{sub CT}) parameter for evaluating the color change capability of color-tunable organic light-emitting diodes (CT-OLEDs) was proposed and formulated. And a series of CT-OLEDs, consisting of five different carrier/exciton adjusting interlayers (C/EALs) inserted between two complementary emitting layers, were fabricated and applied to disclose the relationship between I{sub CT} and C/EALs. The result showed that the trend of electroluminescence spectra behavior in CT-OLEDs has good accordance with I{sub CT} values, indicating that the I{sub CT} parameter is feasible for the evaluation of color variation. Meanwhile, by changing energy level and C/EAL thickness, the optimized device with the widest color tuning range was based on N,N′-dicarbazolyl-3,5-benzene C/EAL, exhibiting the highest I{sub CT} value of 41.2%. Based on carrier quadratic hopping theory and exciton transfer model, two fitting I{sub CT} formulas derived from the highest occupied molecular orbital (HOMO) energy level and triplet energy level were simulated. Finally, a color tuning prediction (CTP) model was developed to deduce the I{sub CT} via C/EAL HOMO and triplet energy levels, and verified by the fabricated OLEDs with five different C/EALs. We believe that the CTP model assisted with I{sub CT} parameter will be helpful for fabricating high performance CT-OLEDs with a broad range of color tuning.

  18. Laterally injected light-emitting diode and laser diode

    DOE Patents [OSTI]

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  19. Poly (p-phenyleneneacetylene) light-emitting diodes

    DOE Patents [OSTI]

    Shinar, Joseph; Swanson, Leland S.; Lu, Feng; Ding, Yiwei; Barton, Thomas J.; Vardeny, Zeev V.

    1994-10-04

    Acetylene containing poly(p-phenyleneacetylene) (PPA) - based light-emitting diodes (LEDs) are provided. The LEDs are fabricated by coating a hole-injecting electrode, preferably an indium tin oxide (ITO) coated glass substrate, with a PPA polymer, such as a 2,5-dibutoxy or a 2,5-dihexoxy derivative of PPA, dissolved in an organic solvent. This is then followed by evaporating a layer of material capable of injecting electrons, such as Al or Al/Ca, onto the polymer to form a base electrode. This composition is then annealed to form efficient EL diodes.

  20. Poly (p-phenyleneacetylene) light-emitting diodes

    DOE Patents [OSTI]

    Shinar, J.; Swanson, L.S.; Lu, F.; Ding, Y.; Barton, T.J.; Vardeny, Z.V.

    1994-10-04

    Acetylene containing poly(p-phenyleneacetylene) (PPA) - based light-emitting diodes (LEDs) are provided. The LEDs are fabricated by coating a hole-injecting electrode, preferably an indium tin oxide (ITO) coated glass substrate, with a PPA polymer, such as a 2,5-dibutoxy or a 2,5-dihexoxy derivative of PPA, dissolved in an organic solvent. This is then followed by evaporating a layer of material capable of injecting electrons, such as Al or Al/Ca, onto the polymer to form a base electrode. This composition is then annealed to form efficient EL diodes. 8 figs.

  1. Fabrication of poly(p-phenyleneacetylene) light-emitting diodes

    DOE Patents [OSTI]

    Shinar, Joseph; Swanson, Leland S.; Lu, Feng; Ding, Yiwei

    1994-08-02

    Acetylene containing poly(p-phenyleneacetylene) (PPA) - based light-emitting diodes (LEDs) are provided. The LEDs are fabricated by coating a hole-injecting electrode, preferably an indium tin oxide (ITO) coated glass substrate, with a PPA polymer, such as a 2,5-dibutoxy or a 2,5-dihexoxy derivative of PPA, dissolved in an organic solvent. This is then followed by evaporating a layer of material capable of injecting electrons, such as A1 or A1/Ca, onto the polymer to form a base electrode. This composition is then annealed to form efficient EL diodes.

  2. Fabrication of poly(p-phenyleneacetylene) light-emitting diodes

    DOE Patents [OSTI]

    Shinar, J.; Swanson, L.S.; Lu, F.; Ding, Y.

    1994-08-02

    Acetylene-containing poly(p-phenyleneacetylene) (PPA)-based light-emitting diodes (LEDs) are provided. The LEDs are fabricated by coating a hole-injecting electrode, preferably an indium tin oxide (ITO) coated glass substrate, with a PPA polymer, such as a 2,5-dibutoxy or a 2,5-dihexoxy derivative of PPA, dissolved in an organic solvent. This is then followed by evaporating a layer of material capable of injecting electrons, such as Al or Al/Ca, onto the polymer to form a base electrode. This composition is then annealed to form efficient EL diodes. 8 figs.

  3. A micrometer-size movable light emitting area in a resonant tunneling light emitting diode

    SciTech Connect (OSTI)

    Pettinari, G., E-mail: giorgio.pettinari@cnr.it [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); National Research Council (CNR), Institute for Photonics and Nanotechnologies (IFN-CNR), Via Cineto Romano 42, 00156 Roma (Italy); Balakrishnan, N.; Makarovsky, O.; Campion, R. P.; Patan, A. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Polimeni, A.; Capizzi, M. [CNISM-Dipartimento di Fisica, Sapienza Universit di Roma, P.le A. Moro 2, 00185 Roma (Italy)] [CNISM-Dipartimento di Fisica, Sapienza Universit di Roma, P.le A. Moro 2, 00185 Roma (Italy)

    2013-12-09

    We report on the fabrication of a micrometer-size movable light emitting area in a GaAs/AlAs quantum well resonant tunneling p-i-n diode. The spatial position of the micrometer-size light emitting area shifts linearly with increasing applied bias, up to 30??m for a bias increment of 0.2?V. Also, the simultaneous resonant tunneling injection of both electrons and holes into the quantum well states is achieved at specific positions of the diode, thus resulting in a tenfold increase of the electroluminescence intensity.

  4. Stable blue phosphorescent organic light emitting devices

    DOE Patents [OSTI]

    Forrest, Stephen R.; Thompson, Mark; Giebink, Noel

    2014-08-26

    Novel combination of materials and device architectures for organic light emitting devices is provided. An organic light emitting device, is provided, having an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer includes a host and a phosphorescent emissive dopant having a peak emissive wavelength less than 500 nm, and a radiative phosphorescent lifetime less than 1 microsecond. Preferably, the phosphorescent emissive dopant includes a ligand having a carbazole group.

  5. Suppression of roll-off characteristics of organic light-emitting diodes by narrowing current injection/transport area to 50?nm

    SciTech Connect (OSTI)

    Hayashi, Kyohei Inoue, Munetomo; Yoshida, Kou; Nakanotani, Hajime; Mikhnenko, Oleksandr; Nguyen, Thuc-Quyen E-mail: adachi@cstf.kyushu-u.ac.jp; Adachi, Chihaya E-mail: adachi@cstf.kyushu-u.ac.jp

    2015-03-02

    Using e-beam nanolithography, the current injection/transport area in organic light-emitting diodes (OLEDs) was confined into a narrow linear structure with a minimum width of 50?nm. This caused suppression of Joule heating and partial separation of polarons and excitons, so the charge density where the electroluminescent efficiency decays to the half of the initial value (J{sub 0}) was significantly improved. A device with a narrow current injection width of 50?nm exhibited a J{sub 0} that was almost two orders of magnitude higher compared with that of the unpatterned OLED.

  6. Demonstration Assessment of Light Emitting Diode (LED) Street...

    Energy Savers [EERE]

    Demonstration Assessment of Light Emitting Diode (LED) Street Lighting Host Site: City of Oakland, California Final Report prepared in support of the U.S. DOE Solid-State Lighting ...

  7. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting

    SciTech Connect (OSTI)

    Kinzey, B. R.; Myer, M. A.

    2009-11-01

    A U.S. Department of Energy Solid-State Lighting Gateway Report on a Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting in Lija Loop, Portland, Oregon.

  8. White light-emitting organic electroluminescent devices

    DOE Patents [OSTI]

    Shiang, Joseph John; Duggal, Anil Raj; Parthasarathy, Gautam

    2006-06-20

    A light-emitting device comprises a light-emitting member, which comprises two electrodes, at least two organic electroluminescent ("EL") materials disposed between the electrodes, a charge blocking material disposed between the electrodes, and at least one photoluminescent ("PL") material. The light-emitting member emits electromagnetic ("EM") radiation having a first spectrum in response to a voltage applied across the two electrodes. The PL material absorbs a portion of the EM radiation emitted by the light-emitting member and emits EM radiation having second spectrum different than the first spectrum. Each of the organic EL materials emits EM radiation having a wavelength range selected from the group consisting of blue and red wavelength ranges.

  9. Demonstration Assessment of Light-Emitting Diode Parking Structure Lighting

    Office of Scientific and Technical Information (OSTI)

    at U.S. Department of Labor Headquarters (Technical Report) | SciTech Connect Demonstration Assessment of Light-Emitting Diode Parking Structure Lighting at U.S. Department of Labor Headquarters Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode Parking Structure Lighting at U.S. Department of Labor Headquarters This report documents a solid-state lighting (SSL) technology demonstration at the parking structure of the U.S. Department of Labor (DOL)

  10. Influences of wide-angle and multi-beam interference on the chromaticity and efficiency of top-emitting white organic light-emitting diodes

    SciTech Connect (OSTI)

    Deng, Lingling; Zhou, Hongwei; Chen, Shufen Liu, Bin; Wang, Lianhui; Shi, Hongying

    2015-02-28

    Wide-angle interference (WI) and multi-beam interference (MI) in microcavity are analyzed separately to improve chromaticity and efficiency of the top-emitting white organic light-emitting diodes (TWOLEDs). A classic electromagnetic theory is used to calculate the resonance intensities of WI and MI in top-emitting organic light-emitting diodes (TOLEDs) with influence factors (e.g., electrodes and exciton locations) being considered. The role of WI on the performances of TOLEDs is revealed through using ?-doping technology and comparing blue and red EML positions in top-emitting and bottom-emitting devices. The blue light intensity significantly increases and the chromaticity of TWOLEDs is further improved with the use of enhanced WI (the blue emitting layer moving towards the reflective electrode) in the case of a weak MI. In addition, the effect of the thicknesses of light output layer and carrier transport layers on WI and MI are also investigated. Apart from the microcavity effect, other factors, e.g., carrier balance and carrier recombination regions are considered to obtain TWOLEDs with high efficiency and improved chromaticity near white light equal-energy point.

  11. Low-Cost Light-Emitting Diode Luminaire for General Illumination...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    organic light-emitting diode (WOLED) using a single emitter on a planar glass substrate. ... A single-doped WOLED that addresses manufacturing and performance issues can help meet the ...

  12. Enhancement of hole injection and electroluminescence by ordered Ag nanodot array on indium tin oxide anode in organic light emitting diode

    SciTech Connect (OSTI)

    Jung, Mi E-mail: Dockha@kist.re.kr; Mo Yoon, Dang; Kim, Miyoung; Kim, Chulki; Lee, Taikjin; Hun Kim, Jae; Lee, Seok; Woo, Deokha E-mail: Dockha@kist.re.kr; Lim, Si-Hyung

    2014-07-07

    We report the enhancement of hole injection and electroluminescence (EL) in an organic light emitting diode (OLED) with an ordered Ag nanodot array on indium-tin-oxide (ITO) anode. Until now, most researches have focused on the improved performance of OLEDs by plasmonic effects of metal nanoparticles due to the difficulty in fabricating metal nanodot arrays. A well-ordered Ag nanodot array is fabricated on the ITO anode of OLED using the nanoporous alumina as an evaporation mask. The OLED device with Ag nanodot arrays on the ITO anode shows higher current density and EL enhancement than the one without any nano-structure. These results suggest that the Ag nanodot array with the plasmonic effect has potential as one of attractive approaches to enhance the hole injection and EL in the application of the OLEDs.

  13. Using interlayer step-wise triplet transfer to achieve an efficient white organic light-emitting diode with high color-stability

    SciTech Connect (OSTI)

    Wang, Qi; Ma, Dongge Ding, Junqiao; Wang, Lixiang; Leo, Karl; Qiao, Qiquan; Jia, Huiping; Gnade, Bruce E.

    2014-05-12

    An efficient phosphorescent white organic light emitting-diode with a red-green-blue tri-emitting-layer structure is reported. The host of the red dopant possesses a lower triplet-energy than the green dye. An interlayer step-wise triplet transfer via blue dye ? green dye ? red host ? red dye is achieved. This mechanism allows an efficient triplet harvesting by the three dopants, thus maintaining a balanced white light and reducing energy loss. Moreover, the color stability of the device is improved significantly. The white device not only achieves a peak external quantum efficiency of 21.1??0.8% and power efficiency of 37.5??1.4?lm/W but shows no color shift over a wide range of voltages.

  14. Top-emission Si-based phosphor organic light emitting diode with Au doped ultrathin n-Si film anode and bottom Al mirror

    SciTech Connect (OSTI)

    Li, Y. Z.; Xu, W. J.; Ran, G. Z. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Qin, G. G. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Key Lab of Semiconductor Materials, CAS, Beijing 100083 (China)

    2009-07-20

    We report a highly efficient top-emission Si-based phosphor organic light emitting diode (PhOLED) with an ultrathin polycrystalline n-Si:Au film anode and a bottom Al mirror. This anode is formed by magnetron sputtering followed by Ni induced crystallization and then Au diffusion. By optimizing the thickness of the n-Si:Au film anode, the Au diffusion temperature, and the other parameters of the PhOLED, the highest current and power efficiencies of the n-Si:Au film anode PhOLED reached 85{+-}9 cd/A and 80{+-}8 lm/W, respectively, corresponding to an external quantum efficiency of 21{+-}2% and a power conversion efficiency of 15{+-}2%, respectively, which are about 60% and 110% higher than those of the indium tin oxide anode counterpart and 70% and 50% higher than those of the bulk n{sup +}-Si:Au anode counterpart, respectively.

  15. Thermally activated delayed fluorescence from {sup 3}n?* to {sup 1}n?* up-conversion and its application to organic light-emitting diodes

    SciTech Connect (OSTI)

    Li, Jie; Zhang, Qisheng; Nomura, Hiroko [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Miyazaki, Hiroshi [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Functional Materials Laboratory, Nippon Steel and Sumikin Chemical Co., Ltd, 4680 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 8048503 (Japan); Adachi, Chihaya, E-mail: adachi@cstf.kyushu-u.ac.jp [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

    2014-07-07

    Intense n?* fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the n?* transition and the higher energy of the {sup 3}??* state than the {sup 3}n?* one lead to a small energy difference between the lowest singlet (S{sub 1}) and triplet (T{sub 1}) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T{sub 1} ? S{sub 1} pathway in the electroluminescent process.

  16. Method of making organic light emitting devices

    DOE Patents [OSTI]

    Shiang, Joseph John; Janora, Kevin Henry; Parthasarathy, Gautam; Cella, James Anthony; Chichak, Kelly Scott

    2011-03-22

    The present invention provides a method for the preparation of organic light-emitting devices comprising a bilayer structure made by forming a first film layer comprising an electroactive material and an INP precursor material, and exposing the first film layer to a radiation source under an inert atmosphere to generate an interpenetrating network polymer composition comprising the electroactive material. At least one additional layer is disposed on the reacted first film layer to complete the bilayer structure. The bilayer structure is comprised within an organic light-emitting device comprising standard features such as electrodes and optionally one or more additional layers serving as a bipolar emission layer, a hole injection layer, an electron injection layer, an electron transport layer, a hole transport layer, exciton-hole transporting layer, exciton-electron transporting layer, a hole transporting emission layer, or an electron transporting emission layer.

  17. Modifying the organic/electrode interface in Organic Solar Cells (OSCs) and improving the efficiency of solution-processed phosphorescent Organic Light-Emitting Diodes (OLEDs)

    SciTech Connect (OSTI)

    Xiao, Teng

    2012-04-27

    Organic semiconductors devices, such as, organic solar cells (OSCs), organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs) have drawn increasing interest in recent decades. As organic materials are flexible, light weight, and potentially low-cost, organic semiconductor devices are considered to be an alternative to their inorganic counterparts. This dissertation will focus mainly on OSCs and OLEDs. As a clean and renewable energy source, the development of OSCs is very promising. Cells with 9.2% power conversion efficiency (PCE) were reported this year, compared to < 8% two years ago. OSCs belong to the so-called third generation solar cells and are still under development. While OLEDs are a more mature and better studied field, with commercial products already launched in the market, there are still several key issues: (1) the cost of OSCs/OLEDs is still high, largely due to the costly manufacturing processes; (2) the efficiency of OSCs/OLEDs needs to be improved; (3) the lifetime of OSCs/OLEDs is not sufficient compared to their inorganic counterparts; (4) the physics models of the behavior of the devices are not satisfactory. All these limitations invoke the demand for new organic materials, improved device architectures, low-cost fabrication methods, and better understanding of device physics. For OSCs, we attempted to improve the PCE by modifying the interlayer between active layer/metal. We found that ethylene glycol (EG) treated poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT: PSS) improves hole collection at the metal/polymer interface, furthermore it also affects the growth of the poly(3- hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) blends, making the phase segregation more favorable for charge collection. We then studied organic/inorganic tandem cells. We also investigated the effect of a thin LiF layer on the hole-collection of copper phthalocyanine (CuPc)/C70-based small molecular OSCs. A

  18. Low Voltage, Low Power Organic Light Emitting Transistors for AMOLED Displays

    SciTech Connect (OSTI)

    McCarthy, M. A. [University of Florida, Gainesville; Liu, B. [University of Florida, Gainesville; Donoghue, E. P. [University of Florida, Gainesville; Kravchenko, Ivan I [ORNL; Kim, D. Y. [University of Florida, Gainesville; Reynolds, J. R. [University of Florida, Gainesville; So, Franky [University of Florida, Gainesville; Rinzler, A. G. [University of Florida, Gainesville

    2011-01-01

    Low voltage, low power dissipation, high aperture ratio organic light emitting transistors are demonstrated. The high level of performance is enabled by a carbon nanotube source electrode that permits integration of the drive transistor and the organic light emitting diode into an efficient single stacked device. Given the demonstrated performance, this technology could break the technical logjam holding back widespread deployment of active matrix organic light emitting displays at flat panel screen sizes.

  19. Organic light emitting devices for illumination

    DOE Patents [OSTI]

    Hack, Michael; Lu, Min-Hao Michael; Weaver, Michael S.

    2012-01-24

    An organic light emitting device an a method of obtaining illumination from such a device is provided. The device has a plurality of regions, each region having an organic emissive layer adapted to emit a different spectrum of light. The regions in combination emit light suitable for illumination purposes. The area of each region may be selected such that the device is more efficient than an otherwise equivalent device having regions of equal size. The regions may have an aspect ratio of at least about four. All parts of any given region may be driven at the same current.

  20. Organic light emitting devices for illumination

    DOE Patents [OSTI]

    Hack, Michael; Lu, Min-Hao Michael; Weaver, Michael S.

    2010-02-16

    An organic light emitting device is provided. The device has a plurality of regions, each region having an organic emissive layer adapted to emit a different spectrum of light. The regions in combination emit light suitable for illumination purposes. The area of each region may be selected such that the device is more efficient that an otherwise equivalent device having regions of equal size. The regions may have an aspect ratio of at least about four. All parts of any given region may be driven at the same current.

  1. High extraction efficiency ultraviolet light-emitting diode

    DOE Patents [OSTI]

    Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

    2015-11-24

    Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

  2. Flip-chip light emitting diode with resonant optical microcavity

    DOE Patents [OSTI]

    Gee, James M.; Bogart, Katherine H.A.; Fischer, Arthur J.

    2005-11-29

    A flip-chip light emitting diode with enhanced efficiency. The device structure employs a microcavity structure in a flip-chip configuration. The microcavity enhances the light emission in vertical modes, which are readily extracted from the device. Most of the rest of the light is emitted into waveguided lateral modes. Flip-chip configuration is advantageous for light emitting diodes (LEDs) grown on dielectric substrates (e.g., gallium nitride LEDs grown on sapphire substrates) in general due to better thermal dissipation and lower series resistance. Flip-chip configuration is advantageous for microcavity LEDs in particular because (a) one of the reflectors is a high-reflectivity metal ohmic contact that is already part of the flip-chip configuration, and (b) current conduction is only required through a single distributed Bragg reflector. Some of the waveguided lateral modes can also be extracted with angled sidewalls used for the interdigitated contacts in the flip-chip configuration.

  3. Permanent polarization and charge distribution in organic light-emitting diodes (OLEDs): Insights from near-infrared charge-modulation spectroscopy of an operating OLED

    SciTech Connect (OSTI)

    Marchetti, Alfred P.; Haskins, Terri L.; Young, Ralph H.; Rothberg, Lewis J.

    2014-03-21

    Vapor-deposited Alq{sub 3} layers typically possess a strong permanent electrical polarization, whereas NPB layers do not. (Alq{sub 3} is tris(8-quinolinolato)aluminum(III); NPB is 4,4?-bis[N-(1-naphthyl)-N-phenylamino]biphenyl.) The cause is a net orientation of the Alq{sub 3} molecules with their large dipole moments. Here we report on consequences for an organic light-emitting diode (OLED) with an NPB hole-transport layer and Alq{sub 3} electron-transport layer. The discontinuous polarization at the NPB|Alq{sub 3} interface has the same effect as a sheet of immobile negative charge there. It is more than compensated by a large concentration of injected holes (NPB{sup +}) when the OLED is running. We discuss the implications and consequences for the quantum efficiency and the drive voltage of this OLED and others. We also speculate on possible consequences of permanent polarization in organic photovoltaic devices. The concentration of NPB{sup +} was measured by charge-modulation spectroscopy (CMS) in the near infrared, where the NPB{sup +} has a strong absorption band, supplemented by differential-capacitance and current-voltage measurements. Unlike CMS in the visible, this method avoids complications from modulation of the electroluminescence and electroabsorption.

  4. Influence of PEDOT:PSS on the effectiveness of barrier layers prepared by atomic layer deposition in organic light emitting diodes

    SciTech Connect (OSTI)

    Wegler, Barbara; Schmidt, Oliver; Hensel, Bernhard

    2015-01-15

    Organic light emitting diodes (OLEDs) are well suited for energy saving lighting applications, especially when thinking about highly flexible and large area devices. In order to avoid the degradation of the organic components by water and oxygen, OLEDs need to be encapsulated, e.g., by a thin sheet of glass. As the device is then no longer flexible, alternative coatings are required. Atomic layer deposition (ALD) is a very promising approach in this respect. The authors studied OLEDs that were encapsulated by 100 nm Al{sub 2}O{sub 3} deposited by ALD. The authors show that this coating effectively protects the active surface area of the OLEDs from humidity. However, secondary degradation processes still occur at sharp edges of the OLED stack where the extremely thin encapsulation layer does not provide perfect coverage. Particularly, the swelling of poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate), which is a popular choice for the planarization of the bottom electrode and at the same time acts as a hole injection layer, affects the effectiveness of the encapsulation layer.

  5. Adoption of Light-Emitting Diodes in Common Lighting Applications

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Adoption of Light-Emitting Diodes in Common Lighting Applications Prepared for the U.S. Department of Energy Solid-State Lighting Program July 2015 Prepared by Navigant This page intentionally left blank i | P a g e Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government, nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any

  6. Interfacial chemical reaction and multiple gap state formation on three layer cathode in organic light-emitting diode: Ca/BaF{sub 2}/Alq{sub 3}

    SciTech Connect (OSTI)

    Kim, Tae Gun; Kim, Jeong Won; Lee, Hyunbok; Yi, Yeonjin; Lee, Seung Mi

    2015-07-14

    A three layer cathode is a promising stack structure for long lifetime and high efficiency in organic light-emitting diodes. The interfacial chemical reactions and their effects on electronic structures for alkaline-earth metal (Ca, Ba)/Alq{sub 3} [tris(8-hydroxyquinolinato)aluminum] and Ca/BaF{sub 2}/Alq{sub 3} are investigated using in-situ X-ray and ultraviolet photoelectron spectroscopy, as well as molecular model calculation. The BaF{sub 2} interlayer initially prevents direct contact between Alq{sub 3} and the reactive Ca metal, but it is dissociated into Ba and CaF{sub 2} by the addition of Ca. As the Ca thickness increases, the Ca penetrates the interlayer to directly participate in the reaction with the underlying Alq{sub 3}. This series of chemical reactions takes place irrespective of the BaF{sub 2} buffer layer thickness as long as the Ca overlayer thickness is sufficient. The interface reaction between the alkaline-earth metal and Alq{sub 3} generates two energetically separated gap states in a sequential manner. This phenomenon is explained by step-by-step charge transfer from the alkaline-earth metal to the lowest unoccupied molecular orbital states of Alq{sub 3}, forming new occupied states below the Fermi level.

  7. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    SciTech Connect (OSTI)

    Hua, Wang, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Du, Xiaogang [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China) [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Su, Wenming, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Zhang, Dongyu [Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China)] [Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China); Lin, Wenjing [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China) [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China)

    2014-02-15

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4{sup ?}-N,N{sup ?}-dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N{sup ?})iridium(III) (Ir(2-phq){sub 3}) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2{sup ?}]picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m{sup 2}. More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  8. Monte Carlo study of efficiency roll-off of phosphorescent organic light-emitting diodes: Evidence for dominant role of triplet-polaron quenching

    SciTech Connect (OSTI)

    Eersel, H. van, E-mail: h.v.eersel@tue.nl; Coehoorn, R. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven (Netherlands); Bobbert, P. A.; Janssen, R. A. J. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-10-06

    We present an advanced molecular-scale organic light-emitting diode (OLED) model, integrating both electronic and excitonic processes. Using this model, we can reproduce the measured efficiency roll-off for prototypical phosphorescent OLED stacks based on the green dye tris[2-phenylpyridine]iridium (Ir(ppy){sub 3}) and the red dye octaethylporphine platinum (PtOEP) and study the cause of the roll-off as function of the current density. Both the voltage versus current density characteristics and roll-off agree well with experimental data. Surprisingly, the results of the simulations lead us to conclude that, contrary to what is often assumed, not triplet-triplet annihilation but triplet-polaron quenching is the dominant mechanism causing the roll-off under realistic operating conditions. Simulations for devices with an optimized recombination profile, achieved by carefully tuning the dye trap depth, show that it will be possible to fabricate OLEDs with a drastically reduced roll-off. It is envisaged that J{sub 90}, the current density at which the efficiency is reduced to 90%, can be increased by almost one order of magnitude as compared to the experimental state-of-the-art.

  9. Distinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer

    SciTech Connect (OSTI)

    Xue, Qin, E-mail: xueqin19851202@163.com; Liu, Shouyin [Department of Physical Science and Technology, Central China Normal University, Wuhan 430079 (China); Xie, Guohua; Chen, Ping; Zhao, Yi; Liu, Shiyong [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2014-03-21

    An ultrathin layer of deep-red phosphorescent emitter tris(1-phenylisoquinoline) iridium (III) (Ir(piq){sub 3}) is inserted within different positions of the electron blocking layer fac-tris (1-phenylpyrazolato-N,C{sup 2?})-iridium(III) (Ir(ppz){sub 3}) to distinguish the contribution of the emission from the triplet exciton energy transfer/diffusion from the adjacent blue phosphorescent emitter and the trap-assisted recombination from the narrow band-gap emitter itself. The charge trapping effect of the narrow band-gap deep-red emitter which forms a quantum-well-like structure also plays a role in shaping the electroluminescent characteristics of multi-color organic light-emitting diodes. By accurately controlling the position of the ultrathin sensing layer, it is considerably easy to balance the white emission which is quite challenging for full-color devices with multiple emission zones. There is nearly no energy transfer detectable if 7 nm thick Ir(ppz){sub 3} is inserted between the blue phosphorescent emitter and the ultrathin red emitter.

  10. Simulated evolution of fluorophores for light emitting diodes

    SciTech Connect (OSTI)

    Shu, Yinan; Levine, Benjamin G.

    2015-03-14

    Organic light emitting diodes based on fluorophores with a propensity for thermally activated delayed fluorescence (TADF) are able to circumvent limitations imposed on device efficiency by spin statistics. Molecules with a propensity for TADF necessarily have two properties: a small gap between the lowest lying singlet and triplet excited states and a large transition dipole moment for fluorescence. In this work, we demonstrate the use of a genetic algorithm to search a region of chemical space for molecules with these properties. This algorithm is based on a flexible and intuitive representation of the molecule as a tree data structure, in which the nodes correspond to molecular fragments. Our implementation takes advantage of hybrid parallel graphics processing unit accelerated computer clusters to allow efficient sampling while retaining a reasonably accurate description of the electronic structure (in this case, CAM-B3LYP/6-31G{sup ??}). In total, we have identified 3792 promising candidate fluorophores from a chemical space containing 1.26 10{sup 6} molecules. This required performing electronic structure calculations on only 7518 molecules, a small fraction of the full space. Several novel classes of molecules which show promise as fluorophores are presented.

  11. High efficiency III-nitride light-emitting diodes

    DOE Patents [OSTI]

    Crawford, Mary; Koleske, Daniel; Cho, Jaehee; Zhu, Di; Noemaun, Ahmed; Schubert, Martin F; Schubert, E. Fred

    2013-05-28

    Tailored doping of barrier layers enables balancing of the radiative recombination among the multiple-quantum-wells in III-Nitride light-emitting diodes. This tailored doping enables more symmetric carrier transport and uniform carrier distribution which help to reduce electron leakage and thus reduce the efficiency droop in high-power III-Nitride LEDs. Mitigation of the efficiency droop in III-Nitride LEDs may enable the pervasive market penetration of solid-state-lighting technologies in high-power lighting and illumination.

  12. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    SciTech Connect (OSTI)

    Chang, Yung-Ting; Liu, Shun-Wei; Yuan, Chih-Hsien; Lee, Chih-Chien; Ho, Yu-Hsuan; Wei, Pei-Kuen; Chen, Kuan-Yu; Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti E-mail: chihiwu@cc.ee.ntu.edu.tw; Wu, Chih-I E-mail: chihiwu@cc.ee.ntu.edu.tw

    2013-11-07

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7?cd/A and maximum power efficiency of 8.39?lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7?cd/A and 8.39?lm/W to 23?cd/A and 13.2?lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.

  13. 2014-05-16 Issuance: Test Procedures for Integrated Light-Emitting Diode

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Lamps; Supplemental Notice of Proposed Rulemaking | Department of Energy 16 Issuance: Test Procedures for Integrated Light-Emitting Diode Lamps; Supplemental Notice of Proposed Rulemaking 2014-05-16 Issuance: Test Procedures for Integrated Light-Emitting Diode Lamps; Supplemental Notice of Proposed Rulemaking This document is a pre-publication Federal Register supplemental notice of proposed rulemaking regarding test procedures for integrated light-emitting diode lamps, as issued by the

  14. Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications

    SciTech Connect (OSTI)

    none,

    2011-01-01

    This report is an analysis of niche markets and applications for light-emitting diodes (LEDs), undertaken on behalf of the U.S. Department of Energy.

  15. Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications

    SciTech Connect (OSTI)

    None, None

    2008-09-01

    This report is an analysis of niche markets and applications for light-emitting diodes (LEDs), undertaken on behalf of the U.S. Department of Energy.

  16. Demonstration Assessment of Light-Emitting Diode (LED) Area Lights for a Commercial Garage

    SciTech Connect (OSTI)

    2008-11-01

    This U.S. Department of Energy GATEWAY Demonstration project studied the applicability of light-emitting diode (LED) luminaires for commercial parking garage applications.

  17. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    SciTech Connect (OSTI)

    Sarwar, A. T. M. Golam; May, Brelon J.; Deitz, Julia I.; Grassman, Tyler J.; McComb, David W.; Myers, Roberto C.

    2015-09-07

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon.

  18. Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at

    Office of Scientific and Technical Information (OSTI)

    Central Park in New York City (Technical Report) | SciTech Connect Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at Central Park in New York City Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at Central Park in New York City A review of five post-top light-emitting diode (LED) pedestrian luminaires installed in New York City's Central Park for possible replacement to the existing metal halide

  19. Demonstration Assessment of Light-Emitting Diode (LED) Post-Top...

    Office of Scientific and Technical Information (OSTI)

    at Central Park in New York City Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at Central Park in New York ...

  20. Understanding Drooping Light Emitting Diodes CEEM | U.S. DOE Office of

    Office of Science (SC) Website

    Science (SC) Understanding Drooping Light Emitting Diodes CEEM Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights Highlight Archives News & Events Publications History Contact BES Home 04.27.12 Understanding Drooping Light Emitting Diodes CEEM Print Text Size: A A A FeedbackShare Page Scientific Achievement New calculations demonstrate that LED "droop" is dominated by multi-particle interactions. Droop occurs when increasing energy input

  1. Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Estimates of Light Emitting Diodes in Niche Lighting Applications Prepared for: Building Technologies Program Office of Energy Efficiency and Renewable Energy U.S. Department of Energy Prepared by: Navigant Consulting Inc. 1801 K Street, NW Suite 500 Washington DC, 20006 September 2008 * Department of Energy Washington, DC 20585 Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications Released: September 2008 Revised: October 2008 This DOE report presents research

  2. DOE Science Showcase - Light-emitting Diode (LED) Lighting Research | OSTI,

    Office of Scientific and Technical Information (OSTI)

    US Dept of Energy Office of Scientific and Technical Information Light-emitting Diode (LED) Lighting Research Light-emitting diode (LED) lighting is a type of solid-state lighting that uses a semiconductor to convert electricity to light. LED lighting products are beginning to appear in a wide variety of home, business, and industrial products such as holiday lighting, replacement bulbs for incandescent lamps, street lighting, outdoor area lighting and indoor ambient lighting. Over the past

  3. White-blue electroluminescence from a Si quantum dot hybrid light-emitting diode

    SciTech Connect (OSTI)

    Xin, Yunzi; Nishio, Kazuyuki; Saitow, Ken-ichi

    2015-05-18

    A silicon (Si) quantum dot (QD)-based hybrid inorganic/organic light-emitting diode (LED) was fabricated via solution processing. This device exhibited white-blue electroluminescence at a low applied voltage of 6?V, with 78% of the effective emission obtained from the Si QDs. This hybrid LED produced current and optical power densities 280 and 350 times greater than those previously reported for such device. The superior performance of this hybrid device was obtained by both the prepared Si QDs and the optimized layer structure and thereby improving carrier migration through the hybrid LED and carrier recombination in the homogeneous Si QD layer.

  4. Method and apparatus for improving the performance of light emitting diodes

    DOE Patents [OSTI]

    Lowery, Christopher H.; McElfresh, David K.; Burchet, Steve; Adolf, Douglas B.; Martin, James

    1996-01-01

    A method for increasing the resistance of a light emitting diode and other semiconductor devices to extremes of temperature is disclosed. During the manufacture of the light emitting diode, a liquid coating is applied to the light emitting die after the die has been placed in its lead frame. After the liquid coating has been placed on the die and its lead frames, a thermosetting encapsulant material is placed over the coating. The operation that cures the thermosetting material leaves the coating liquid intact. As the die and the encapsulant expand and contract at different rates with respect to changes in temperature, and as in known light emitting diodes the encapsulating material adheres to the die and lead frames, this liquid coating reduces the stresses that these different rates of expansion and contraction normally cause by eliminating the adherence of the encapsulating material to the die and frame.

  5. Diffusion injected multi-quantum well light-emitting diode structure

    SciTech Connect (OSTI)

    Riuttanen, L. Nyknen, H.; Svensk, O.; Suihkonen, S.; Sopanen, M.; Kivisaari, P.; Oksanen, J.; Tulkki, J.

    2014-02-24

    The attention towards light-emitting diode (LED) structures based on nanowires, surface plasmon coupled LEDs, and large-area high-power LEDs has been increasing for their potential in increasing the optical output power and efficiency of LEDs. In this work we demonstrate an alternative way to inject charge carriers into the active region of an LED, which is based on completely different current transport mechanism compared to conventional current injection approaches. The demonstrated structure is expected to help overcoming some of the challenges related to current injection with conventional structures. A functioning III-nitride diffusion injected light-emitting diode structure, in which the light-emitting active region is located outside the pn-junction, is realized and characterized. In this device design, the charge carriers are injected into the active region by bipolar diffusion, which could also be utilized to excite otherwise challenging to realize light-emitting structures.

  6. Concave-hemisphere-patterned organic top-light emitting device

    DOE Patents [OSTI]

    Forrest, Stephen R; Slootsky, Michael; Lunt, Richard

    2014-01-21

    A first device is provided. The first device includes an organic light emitting device, which further comprises a first electrode, a second electrode, and an organic emissive layer disposed between the first and second electrode. Preferably, the second electrode is more transparent than the first electrode. The organic emissive layer has a first portion shaped to form an indentation in the direction of the first electrode, and a second portion shaped to form a protrusion in the direction of the second electrode. The first device may include a plurality of organic light emitting devices. The indentation may have a shape that is formed from a partial sphere, a partial cylinder, a pyramid, or a pyramid with a mesa, among others. The protrusions may be formed between adjoining indentations or between an indentation and a surface parallel to the substrate.

  7. Concave-hemisphere-patterned organic top-light emitting device

    DOE Patents [OSTI]

    Forrest, Stephen R.; Slootsky, Michael; Lunt, Richard

    2015-06-09

    A first device is provided. The first device includes an organic light emitting device, which further comprises a first electrode, a second electrode, and an organic emissive layer disposed between the first and second electrode. Preferably, the second electrode is more transparent than the first electrode. The organic emissive layer has a first portion shaped to form an indentation in the direction of the first electrode, and a second portion shaped to form a protrusion in the direction of the second electrode. The first device may include a plurality of organic light emitting devices. The indentation may have a shape that is formed from a partial sphere, a partial cylinder, a pyramid, or a pyramid with a mesa, among others. The protrusions may be formed between adjoining indentations or between an indentation and a surface parallel to the substrate.

  8. Organic light emitting device having multiple separate emissive layers

    DOE Patents [OSTI]

    Forrest, Stephen R. (Ann Arbor, MI)

    2012-03-27

    An organic light emitting device having multiple separate emissive layers is provided. Each emissive layer may define an exciton formation region, allowing exciton formation to occur across the entire emissive region. By aligning the energy levels of each emissive layer with the adjacent emissive layers, exciton formation in each layer may be improved. Devices incorporating multiple emissive layers with multiple exciton formation regions may exhibit improved performance, including internal quantum efficiencies of up to 100%.

  9. Organic light emitting device structure for obtaining chromaticity stability

    DOE Patents [OSTI]

    Tung, Yeh-Jiun; Ngo, Tan

    2007-05-01

    The present invention relates to organic light emitting devices (OLEDs). The devices of the present invention are efficient white or multicolored phosphorescent OLEDs which have a high color stability over a wide range of luminances. The devices of the present invention comprise an emissive region having at least two emissive layers, with each emissive layer comprising a different host and emissive dopant, wherein at least one of the emissive dopants emits by phosphorescence.

  10. Organic light emitting device structures for obtaining chromaticity stability

    DOE Patents [OSTI]

    Tung, Yeh-Jiun; Lu, Michael; Kwong, Raymond C.

    2005-04-26

    The present invention relates to organic light emitting devices (OLEDs). The devices of the present invention are efficient white or multicolored phosphorescent OLEDs which have a high color stability over a wide range of luminances. The devices of the present invention comprise an emissive region having at least two emissive layers, with each emissive layer comprising a different host and emissive dopant, wherein at least one of the emissive dopants emits by phosphorescence.

  11. Green Light-Emitting Diode Makes Highly Efficient White Light; The Spectrum of Clean Energy Innovation (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2010-06-01

    Fact sheet describing NREL's green light emitting diode that can lead to higher efficiency white light used in indoor lighting applications.

  12. Demonstration Assessment of Light-Emitting Diode Roadway Lighting on the FDR Drive in New York, New York

    SciTech Connect (OSTI)

    Myer, Michael; Hazra, Oindrila; Kinzey, Bruce R.

    2011-12-01

    This a report about a field study of light-emitting diodes street lights by four different manufacturers installed on the FDR Drive in New York City, NY.

  13. Printed assemblies of ultrathin, microscale inorganic light emitting diodes for deformable and semitransparent displays

    DOE Patents [OSTI]

    Rogers, John A; Nuzzo, Ralph; Kim, Hoon-sik; Brueckner, Eric; Park, Sang Il; Kim, Rak Hwan

    2014-10-21

    Described herein are printable structures and methods for making, assembling and arranging electronic devices. A number of the methods described herein are useful for assembling electronic devices where one or more device components are embedded in a polymer which is patterned during the embedding process with trenches for electrical interconnects between device components. Some methods described herein are useful for assembling electronic devices by printing methods, such as by dry transfer contact printing methods. Also described herein are GaN light emitting diodes and methods for making and arranging GaN light emitting diodes, for example for display or lighting systems.

  14. New red phosphor for near-ultraviolet light-emitting diodes with high color-purity

    SciTech Connect (OSTI)

    Wang, Zhengliang; He, Pei; Wang, Rui; Zhao, Jishou; Gong, Menglian

    2010-02-15

    New red phosphors, Na{sub 5}Eu(MoO{sub 4}){sub 4} doped with boron oxide were prepared by the solid-state reaction. Their structure and photo-luminescent properties were investigated. With the introduction of boron oxide, the red emission intensity of the phosphors under 395 nm excitation is strengthened, with high color-purity (x = 0.673, y = 0.327). The single red light-emitting diode was obtained by combining InGaN chip with the red phosphor, bright red light can be observed by naked eyes from the red light-emitting diodes under a forward bias of 20 mA.

  15. Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)

    SciTech Connect (OSTI)

    Stark, Christoph J. M.; Detchprohm, Theeradetch; Wetzel, Christian, E-mail: wetzel@ieee.org [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Future Chips Constellation, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Lee, S. C.; Brueck, S. R. J. [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)] [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States); Jiang, Y.-B. [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2013-12-02

    GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting (111) planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100??A is found fixed at 487?nm (peak), 516?nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.

  16. Tunnel junction multiple wavelength light-emitting diodes

    DOE Patents [OSTI]

    Olson, Jerry M.; Kurtz, Sarah R.

    1992-01-01

    A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect.

  17. Tunnel junction multiple wavelength light-emitting diodes

    DOE Patents [OSTI]

    Olson, J.M.; Kurtz, S.R.

    1992-11-24

    A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect. 5 figs.

  18. Cathode encapsulation of organic light emitting diodes by atomic layer deposited Al{sub 2}O{sub 3} films and Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks

    SciTech Connect (OSTI)

    Keuning, W.; Weijer, P. van de; Lifka, H.; Kessels, W. M. M.; Creatore, M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Philips Research Laboratories, High Tech Campus 4, P.O. Box WAG12, 5656 AE Eindhoven (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2012-01-15

    Al{sub 2}O{sub 3} thin films synthesized by plasma-enhanced atomic layer deposition (ALD) at room temperature (25 deg. C) have been tested as water vapor permeation barriers for organic light emitting diode devices. Silicon nitride films (a-SiN{sub x}:H) deposited by plasma-enhanced chemical vapor deposition served as reference and were used to develop Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks. On the basis of Ca test measurements, a very low intrinsic water vapor transmission rate of {<=} 2 x 10{sup -6} g m{sup -2} day{sup -1} and 4 x 10{sup -6} g m{sup -2} day{sup -1} (20 deg. C/50% relative humidity) were found for 20-40 nm Al{sub 2}O{sub 3} and 300 nm a-SiN{sub x}:H films, respectively. The cathode particle coverage was a factor of 4 better for the Al{sub 2}O{sub 3} films compared to the a-SiN{sub x}:H films and an average of 0.12 defects per cm{sup 2} was obtained for a stack consisting of three barrier layers (Al{sub 2}O{sub 3}/a-SiN{sub x}:H/Al{sub 2}O{sub 3}).

  19. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    SciTech Connect (OSTI)

    Xu, Xianmei; Wang, Yilin; Gule, Teri; Luo, Qiang [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Zhou, Liya, E-mail: zhouliyatf@163.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Gong, Fuzhong [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China)

    2013-03-15

    Highlights: ? Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ? The fabricated white LEDs show good white balance. ? CdSe QDs present well green to yellow band luminescence. ? CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de lclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors.

  20. Light-emitting device with organic electroluminescent material and photoluminescent materials

    DOE Patents [OSTI]

    McNulty, Thomas Francis; Duggal, Anil Raj; Turner, Larry Gene; Shiang, Joseph John

    2005-06-07

    A light-emitting device comprises a light-emitting member, which comprises two electrodes and an organic electroluminescent material disposed between the electrodes, and at least one organic photoluminescent ("PL") material. The light-emitting member emits light having a first spectrum in response to a voltage applied across the two electrodes. The organic PL material absorbs a portion of the light emitted by the light-emitting member and emits light having second spectrum different than the first spectrum. The light-emitting device can include an inorganic PL material that absorbs another portion of the light emitted from the light-emitting member and emits light having a third spectrum different than both the first and the second spectra.

  1. Enhanced performance of organic light-emitting diodes (OLEDs) and OLED-based photoluminescent sensing platforms by novel microstructures and device architectures

    SciTech Connect (OSTI)

    Liu, Rui

    2012-08-01

    After a general introduction to OLEDs and OLED-based PL sensors, the transient emission mechanism of guest-host OLEDs is described both experimentally and theoretically. A monolithic and easy-to-apply process is demonstrated for fabricating multicolor microcavity OLEDs (that improve the sensor platform). The outcoupling issues of OLEDs at the substrate/air interface are addressed by using a microstructured polymer film resulting from a PS and polyethylene glycol (PEG) mixture. Based on the understanding of OLEDs and their improvement, research was done in order to realize integrated all organic-based O{sub 2} and pH sensors with improved signal intensity and sensitivity. The sensor design modification and optimization are summarized

  2. Organic light-emitting devices using spin-dependent processes

    DOE Patents [OSTI]

    Vardeny, Z. Valy; Wohlgenannt, Markus

    2010-03-23

    The maximum luminous efficiency of organic light-emitting materials is increased through spin-dependent processing. The technique is applicable to all electro-luminescent processes in which light is produced by singlet exciton decay, and all devices which use such effects, including LEDs, super-radiant devices, amplified stimulated emission devices, lasers, other optical microcavity devices, electrically pumped optical amplifiers, and phosphorescence (Ph) based light emitting devices. In preferred embodiments, the emissive material is doped with an impurity, or otherwise modified, to increase the spin-lattice relaxation rate (i.e., decrease the spin-lattice time), and hence raise the efficiency of the device. The material may be a polymer, oligomer, small molecule, single crystal, molecular crystal, or fullerene. The impurity is preferably a magnetic or paramagnetic substance. The invention is applicable to IR, UV, and other electromagnetic radiation generation and is thus not limited to the visible region of the spectrum. The methods of the invention may also be combined with other techniques used to improve device performance.

  3. Red light-emitting diodes based on InP/GaP quantum dots

    SciTech Connect (OSTI)

    Hatami, F.; Lordi, V.; Harris, J.S.; Kostial, H.; Masselink, W.T.

    2005-05-01

    The growth, fabrication, and device characterization of InP quantum-dot light-emitting diodes based on GaP are described and discussed. The diode structures are grown on gallium phosphide substrates using gas-source molecular-beam epitaxy and the active region of the diode consists of self-assembled InP quantum dots embedded in a GaP matrix. Red electroluminescence originating from direct band-gap emission from the InP quantum dots is observed at low temperatures.With increasing temperature, however, the emission line shifts to the longer wavelength. The emission light is measured to above room temperature.

  4. ISSUANCE 2015-06-25: Energy Conservation Program: Test Procedures for Integrated Light-Emitting Diode Lamps, Supplemental Notice of Proposed Rulemaking

    Office of Energy Efficiency and Renewable Energy (EERE)

    Energy Conservation Program: Test Procedures for Integrated Light-Emitting Diode Lamps, Supplemental Notice of Proposed Rulemaking

  5. Broadband visible light source based on AllnGaN light emitting diodes

    DOE Patents [OSTI]

    Crawford, Mary H.; Nelson, Jeffrey S.

    2003-12-16

    A visible light source device is described based on a light emitting diode and a nanocluster-based film. The light emitting diode utilizes a semiconductor quantum well structure between n-type and p-type semiconductor materials on the top surface a substrate such as sapphire. The nanocluster-based film is deposited on the bottom surface of the substrate and can be derived from a solution of MoS.sub.2, MoSe.sub.2, WS.sub.2, and WSe.sub.2 particles of size greater than approximately 2 nm in diameter and less than approximately 15 nm in diameter, having an absorption wavelength greater than approximately 300 nm and less than approximately 650 nm.

  6. Amber light-emitting diode comprising a group III-nitride nanowire active region

    DOE Patents [OSTI]

    Wang, George T.; Li, Qiming; Wierer, Jr., Jonathan J.; Koleske, Daniel

    2014-07-22

    A temperature stable (color and efficiency) III-nitride based amber (585 nm) light-emitting diode is based on a novel hybrid nanowire-planar structure. The arrays of GaN nanowires enable radial InGaN/GaN quantum well LED structures with high indium content and high material quality. The high efficiency and temperature stable direct yellow and red phosphor-free emitters enable high efficiency white LEDs based on the RGYB color-mixing approach.

  7. Photoionization of optically trapped ultracold atoms with a high-power light-emitting diode

    SciTech Connect (OSTI)

    Goetz, Simone; Hoeltkemeier, Bastian; Amthor, Thomas; Weidemueller, Matthias [Physikalisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany)

    2013-04-15

    Photoionization of laser-cooled atoms using short pulses of a high-power light-emitting diode (LED) is demonstrated. Light pulses as short as 30 ns have been realized with the simple LED driver circuit. We measure the ionization cross section of {sup 85}Rb atoms in the first excited state, and show how this technique can be used for calibrating efficiencies of ion detector assemblies.

  8. Low Power, Red, Green and Blue Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for Active Matrix OLED Displays

    SciTech Connect (OSTI)

    McCarthy, M. A. [University of Florida, Gainesville; Liu, B. [University of Florida, Gainesville; Donoghue, E. P. [University of Florida, Gainesville; Kravchenko, Ivan I [ORNL; Kim, D. Y. [University of Florida, Gainesville; So, Franky [University of Florida, Gainesville; Rinzler, A. G. [University of Florida, Gainesville

    2011-01-01

    Organic semiconductors are potential alternatives to polycrystalline silicon as the semiconductor used in the backplane of active matrix organic light emitting diode displays. Demonstrated here is a light-emitting transistor with an organic channel, operating with low power dissipation at low voltage, and high aperture ratio, in three colors: red, green and blue. The single-wall carbon nanotube network source electrode is responsible for the high level of performance demonstrated. A major benefit enabled by this architecture is the integration of the drive transistor, storage capacitor and light emitter into a single device. Performance comparable to commercialized polycrystalline-silicon TFT driven OLEDs is demonstrated.

  9. Adhesion in flexible organic and hybrid organic/inorganic light emitting device and solar cells

    SciTech Connect (OSTI)

    Yu, D.; Kwabi, D.; Akogwu, O.; Du, J.; Oyewole, O. K.; Tong, T.; Anye, V. C.; Rwenyagila, E.; Asare, J.; Fashina, A.; Soboyejo, W. O.

    2014-08-21

    This paper presents the results of an experimental study of the adhesion between bi-material pairs that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, organic bulk heterojunction solar cells, and hybrid organic/inorganic solar cells on flexible substrates. Adhesion between the possible bi-material pairs is measured using force microscopy (AFM) techniques. These include: interfaces that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, bulk heterojunction solar cells, and hybrid combinations of titanium dioxide (TiO{sub 2}) and poly(3-hexylthiophene). The results of AFM measurements are incorporated into the Derjaguin-Muller-Toporov model for the determination of adhesion energies. The implications of the results are then discussed for the design of robust organic and hybrid organic/inorganic electronic devices.

  10. Development of substrate-removal-free vertical ultraviolet light-emitting diode (RefV-LED)

    SciTech Connect (OSTI)

    Kurose, N. Aoyagi, Y.; Shibano, K.; Araki, T.

    2014-02-15

    A vertical ultraviolet (UV) light-emitting diode (LED) that does not require substrate removal is developed. Spontaneous via holes are formed in n-AlN layer epitaxially grown on a high conductive n+Si substrate and the injected current flows directly from the p-electrode to high doped n{sup +} Si substrate through p-AlGaN, multi-quantum wells, n-AlGaN and spontaneous via holes in n-AlN. The spontaneous via holes were formed by controlling feeding-sequence of metal-organic gas sources and NH{sub 3} and growth temperature in MOCVD. The via holes make insulating n-AlN to be conductive. We measured the current-voltage, current-light intensity and emission characteristics of this device. It exhibited a built-in voltage of 3.8 V and emission was stated at 350 nm from quantum wells with successive emission centered at 400 nm. This UV LED can be produced, including formation of n and p electrodes, without any resist process.

  11. Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2015-04-13

    The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, andmore » the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.« less

  12. Demonstration Assessment of Light-Emitting Diode (LED) Accent Lighting at the Field Museum in Chicago, IL

    SciTech Connect (OSTI)

    Myer, Michael; Kinzey, Bruce R.

    2010-12-10

    This report reviews a demonstration of light-emitting diode (LED) accent lighting compared to halogen (typical) accent lighting in a gallery of the Field Museum in Chicago, IL.

  13. Environmental barrier material for organic light emitting device and method of making

    DOE Patents [OSTI]

    Graff, Gordon L [West Richland, WA; Gross, Mark E [Pasco, WA; Affinito, John D [Kennewick, WA; Shi, Ming-Kun [Richland, WA; Hall, Michael [West Richland, WA; Mast, Eric [Richland, WA

    2003-02-18

    An encapsulated organic light emitting device. The device includes a first barrier stack comprising at least one first barrier layer and at least one first polymer layer. There is an organic light emitting layer stack adjacent to the first barrier stack. A second barrier stack is adjacent to the organic light emitting layer stack. The second barrier stack has at least one second barrier layer and at least one second polymer layer. A method of making the encapsulated organic light emitting device is also provided.

  14. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    SciTech Connect (OSTI)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Nicolai, H. T.

    2014-12-14

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

  15. P-doping-free III-nitride high electron mobility light-emitting diodes and transistors

    SciTech Connect (OSTI)

    Li, Baikui; Tang, Xi; Chen, Kevin J.; Wang, Jiannong

    2014-07-21

    We report that a simple metal-AlGaN/GaN Schottky diode is capable of producing GaN band-edge ultraviolet emission at 3.4?eV at a small forward bias larger than ?2?V at room temperature. Based on the surface states distribution of AlGaN, a mature impact-ionization-induced Fermi-level de-pinning model is proposed to explain the underlying mechanism of the electroluminescence (EL) process. By experimenting with different Schottky metals, Ni/Au and Pt/Au, we demonstrated that this EL phenomenon is a universal property of metal-AlGaN/GaN Schottky diodes. Since this light-emitting Schottky diode shares the same active structure and fabrication processes as the AlGaN/GaN high electron mobility transistors, straight-forward and seamless integration of photonic and electronic functional devices has been demonstrated on doping-free III-nitride heterostructures. Using a semitransparent Schottky drain electrode, an AlGaN/GaN high electron mobility light-emitting transistor is demonstrated.

  16. OSTIblog Articles in the Light-emitting diode Topic | OSTI, US Dept of

    Office of Scientific and Technical Information (OSTI)

    Energy Office of Scientific and Technical Information Light-emitting diode Topic Enjoy the benefits of LED lighting by Kathy Chambers 30 Dec, 2013 in Products and Content 13966 Photographic%20credit%E2%80%9CArchitect%20of%20the%20Capitol.%E2%80%9D%202010%20LED%20Tree.jpg Enjoy the benefits of LED lighting Read more about 13966 Every day we are bombarded with advertisements in every form and format telling us that our lives will be improved if we buy a particular product because it will save

  17. Light-emitting diode technology status and directions: Opportunities for horticultural lighting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tsao, Jeffrey Y.; Pattison, P. Morgan; Krames, Michael R.

    2016-01-01

    Here, light-emitting diode (LED) technology has advanced rapidly over the last decade, primarily driven by display and general illumination applications ("solid-state lighting (SSL) for humans"). These advancements have made LED lighting technically and economically advantageous not only for these applications, but also, as an indirect benefit, for adjacent applications such as horticultural lighting ("SSL for plants"). Moreover, LED technology has much room for continued improvement. In the near-term, these improvements will continue to be driven by SSL for humans (with indirect benefit to SSL for plants), the most important of which can be anticipated.

  18. Temperature-dependent efficiency droop of blue InGaN micro-light emitting diodes

    SciTech Connect (OSTI)

    Tian, Pengfei; McKendry, Jonathan J. D.; Herrnsdorf, Johannes; Ferreira, Ricardo; Watson, Ian M.; Gu, Erdan Dawson, Martin D.; Watson, Scott; Kelly, Anthony E.

    2014-10-27

    Temperature-dependent trends in radiative and Auger recombination coefficients have been determined at different injection carrier concentrations using InGaN micro-light emitting diodes 40 ?m in diameter. The differential lifetime was obtained first from the measured modulation bandwidth and was then employed to calculate the carrier concentration in the quantum well active region. When the temperature increases, the carrier concentration increases, but both the radiative and Auger recombination coefficients decrease. In addition, the temperature dependence of radiative and Auger recombination coefficients is weaker at a higher injection carrier concentration, which is strongly related to phase space filling.

  19. Integrated porous-silicon light-emitting diodes: A fabrication process using graded doping profiles

    SciTech Connect (OSTI)

    Barillaro, G.; Diligenti, A.; Pieri, F.; Fuso, F.; Allegrini, M.

    2001-06-25

    A fabrication process, compatible with an industrial bipolar+complementary metal{endash}oxide{endash}semiconductor (MOS)+diffusion MOS technology, has been developed for the fabrication of efficient porous-silicon-based light-emitting diodes. The electrical contact is fabricated with a double n{sup +}/p doping, achieving a high current injection efficiency and thus lower biasing voltages. The anodization is performed as the last step of the process, thus reducing potential incompatibilities with industrial processes. The fabricated devices show yellow-orange electroluminescence, visible with the naked eye in room lighting. A spectral characterization of light emission is presented and briefly discussed. {copyright} 2001 American Institute of Physics.

  20. Light emitting diode package element with internal meniscus for bubble free lens placement

    DOE Patents [OSTI]

    Tarsa, Eric; Yuan, Thomas C.; Becerra, Maryanne; Yadev, Praveen

    2010-09-28

    A method for fabricating a light emitting diode (LED) package comprising providing an LED chip and covering at least part of the LED chip with a liquid encapsulant having a radius of curvature. An optical element is provided having a bottom surface with at least a portion having a radius of curvature larger than the liquid encapsulant. The larger radius of curvature portion of the optical element is brought into contact with the liquid encapsulant. The optical element is then moved closer to the LED chip, growing the contact area between said optical element and said liquid encapsulant. The liquid encapsulant is then cured. A light emitting diode comprising a substrate with an LED chip mounted to it. A meniscus ring is on the substrate around the LED chip with the meniscus ring having a meniscus holding feature. An inner encapsulant is provided over the LED chip with the inner encapsulant having a contacting surface on the substrate, with the meniscus holding feature which defines the edge of the contacting surface. An optical element is included having a bottom surface with at least a portion that is concave. The optical element is arranged on the substrate with the concave portion over the LED chip. A contacting encapsulant is included between the inner encapsulant and optical element.

  1. InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

    SciTech Connect (OSTI)

    Krishnamoorthy, Sriram E-mail: rajan@ece.osu.edu; Akyol, Fatih; Rajan, Siddharth E-mail: rajan@ece.osu.edu

    2014-10-06

    InGaN/GaN tunnel junction contacts were grown using plasma assisted molecular beam epitaxy (MBE) on top of a metal-organic chemical vapor deposition (MOCVD)-grown InGaN/GaN blue (450?nm) light emitting diode. A voltage drop of 5.3?V at 100?mA, forward resistance of 2 10{sup ?2} ? cm{sup 2}, and a higher light output power compared to the reference light emitting diodes (LED) with semi-transparent p-contacts were measured in the tunnel junction LED (TJLED). A forward resistance of 5??10{sup ?4} ? cm{sup 2} was measured in a GaN PN junction with the identical tunnel junction contact as the TJLED, grown completely by MBE. The depletion region due to the impurities at the regrowth interface between the MBE tunnel junction and the MOCVD-grown LED was hence found to limit the forward resistance measured in the TJLED.

  2. Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes

    SciTech Connect (OSTI)

    Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep

    2013-01-28

    We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

  3. Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

    SciTech Connect (OSTI)

    Pozina, Galia; Ciechonski, Rafal; Bi, Zhaoxia; Samuelson, Lars; Monemar, Bo

    2015-12-21

    Today's energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates.

  4. A spin light emitting diode incorporating ability of electrical helicity switching

    SciTech Connect (OSTI)

    Nishizawa, N., E-mail: nishizawa@isl.titech.ac.jp; Nishibayashi, K.; Munekata, H. [Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259-J3-15 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2014-03-17

    Fabrication and optical characteristics of a spin light-emitting-diode (spin-LED) having dual spin-injection electrodes with anti-parallel magnetization configuration are reported. Alternating a current between the two electrodes using a computer-driven current source has led us to the observation of helicity switching of circular polarization at the frequency of 1 kHz. Neither external magnetic fields nor optical delay modulators were used. Sending dc-currents to both electrodes with appropriate ratio has resulted in continuous variation of circular polarization between the two opposite helicity, including the null polarization. These results suggest that the tested spin-LED has the feasibility of a monolithic light source whose circular polarization can be switched or continuously tuned all electrically.

  5. Sidewall passivation for InGaN/GaN nanopillar light emitting diodes

    SciTech Connect (OSTI)

    Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); You, Guanjun; Liu, Jie; Wang, Li; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-07-07

    We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage current and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.

  6. Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at Central Park in New York City

    SciTech Connect (OSTI)

    Myer, Michael; Goettel, Russell T.; Kinzey, Bruce R.

    2012-09-30

    A review of five post-top light-emitting diode (LED) pedestrian luminaires installed in New York City's Central Park for possible replacement to the existing metal halide post-top luminaire. This report reviews the energy savings potential and lighting delivered by the LED post-top luminaires.

  7. Color tuning of light-emitting-diodes by modulating the concentration of red-emitting silicon nanocrystal phosphors

    SciTech Connect (OSTI)

    Barillaro, G. Strambini, L. M.

    2014-03-03

    Luminescent forms of nanostructured silicon have received significant attention in the context of quantum-confined light-emitting devices thanks to size-tunable emission wavelength and high-intensity photoluminescence, as well as natural abundance, low cost, and non-toxicity. Here, we show that red-emitting silicon nanocrystal (SiN) phosphors, obtained by electrochemical erosion of silicon, allow for effectively tuning the color of commercial light-emitting-diodes (LEDs) from blue to violet, magenta, and red, by coating the LED with polydimethylsiloxane encapsulating different SiN concentrations. High reliability of the tuning process, with respect to SiN fabrication and concentration, and excellent stability of the tuning color, with respect to LED bias current, is demonstrated through simultaneous electrical/optical characterization of SiN-modified commercial LEDs, thus envisaging exciting perspectives for silicon nanocrystals in the field of light-emitting applications.

  8. Stress-induced piezoelectric field in GaN-based 450-nm light-emitting diodes

    SciTech Connect (OSTI)

    Tawfik, Wael Z.; Hyeon, Gil Yong; Lee, June Key

    2014-10-28

    We investigated the influence of the built-in piezoelectric field induced by compressive stress on the characteristics of GaN-based 450-nm light-emitting diodes (LEDs) prepared on sapphire substrates of different thicknesses. As the sapphire substrate thickness was reduced, the compressive stress in the GaN layer was released, resulting in wafer bowing. The wafer bowing-induced mechanical stress altered the piezoelectric field, which in turn reduced the quantum confined Stark effect in the InGaN/GaN active region of the LED. The flat-band voltage was estimated by measuring the applied bias voltage that induced a 180° phase shift in the electro-reflectance (ER) spectrum. The piezoelectric field estimated by the ER spectra changed by ∼110 kV/cm. The electroluminescence spectral peak wavelength was blue-shifted, and the internal quantum efficiency was improved by about 22% at a high injection current of 100 mA. The LED on the 60-μm-thick sapphire substrate exhibited the highest light output power of ∼59 mW at an injection current of 100 mA, with the operating voltage unchanged.

  9. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    SciTech Connect (OSTI)

    Arto V. Nurmikko; Jung Han

    2005-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the second 12 month contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  10. NANOSTRUCTURED HIGH PERFORMANCE ULTRAVIOLET AND BLUE LIGHT EMITTING DIODES FOR SOLID STATE LIGHTING

    SciTech Connect (OSTI)

    Arto V. Nurmikko; Jung Han

    2004-10-01

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the first 12 month contract period include (1) new means of synthesizing zero- and one-dimensional GaN nanostructures, (2) establishment of the building blocks for making GaN-based microcavity devices, and (3) demonstration of top-down approach to nano-scale photonic devices for enhanced spontaneous emission and light extraction. These include a demonstration of eight-fold enhancement of the external emission efficiency in new InGaN QW photonic crystal structures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  11. Dislocation-related trap levels in nitride-based light emitting diodes

    SciTech Connect (OSTI)

    Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna

    2014-05-26

    Deep level transient spectroscopy was performed on InGaN/GaN multiple quantum well light emitting diodes (LEDs) in order to determine the effect of the dislocation density on the deep intragap electronic levels. The LEDs were grown by metalorganic vapor phase epitaxy on GaN templates with a high dislocation density of 8 10{sup 9} cm{sup ?2} and a low dislocation density of 3 10{sup 8} cm{sup ?2}. Three trapping levels for electrons were revealed, named A, A1, and B, with energies E{sub A}???0.04?eV, E{sub A1}???0.13?eV, and E{sub B}???0.54?eV, respectively. The trapping level A has a much higher concentration in the LEDs grown on the template with a high density of dislocations. The logarithmic dependence of the peak amplitude on the bias pulse width for traps A and A1 identifies the defects responsible for these traps as associated with linearly arranged defects. We conclude that traps A and A1 are dislocation-related intragap energy levels.

  12. Effect of heterostructure design on carrier injection and emission characteristics of 295?nm light emitting diodes

    SciTech Connect (OSTI)

    Mehnke, Frank Kuhn, Christian; Stellmach, Joachim; Rothe, Mark-Antonius; Reich, Christoph; Ledentsov, Nikolay; Pristovsek, Markus; Wernicke, Tim; Kolbe, Tim; Lobo-Ploch, Neysha; Rass, Jens; Kneissl, Michael

    2015-05-21

    The effects of the heterostructure design on the injection efficiency and external quantum efficiency of ultraviolet (UV)-B light emitting diodes (LEDs) have been investigated. It was found that the functionality of the Al{sub x}Ga{sub 1?x}N:Mg electron blocking layer is strongly influenced by its aluminum mole fraction x and its magnesium doping profile. By comparing LED electroluminescence, quantum well photoluminescence, and simulations of LED heterostructure, we were able to differentiate the contributions of injection efficiency and internal quantum efficiency to the external quantum efficiency of UV LEDs. For the optimized heterostructure using an Al{sub 0.7}Ga{sub 0.3}N:Mg electron blocking layer with a Mg to group III ratio of 4% in the gas phase the electron leakage currents are suppressed without blocking the injection of holes into the multiple quantum well active region. Flip chip mounted LED chips have been processed achieving a maximum output power of 3.5 mW at 290?mA and a peak external quantum efficiency of 0.54% at 30?mA.

  13. A hole modulator for InGaN/GaN light-emitting diodes

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Kyaw, Zabu; Liu, Wei; Ji, Yun; Wang, Liancheng; Tan, Swee Tiam; Sun, Xiao Wei E-mail: VOLKAN@stanfordalumni.org; Demir, Hilmi Volkan E-mail: VOLKAN@stanfordalumni.org

    2015-02-09

    The low p-type doping efficiency of the p-GaN layer has severely limited the performance of InGaN/GaN light-emitting diodes (LEDs) due to the ineffective hole injection into the InGaN/GaN multiple quantum well (MQW) active region. The essence of improving the hole injection efficiency is to increase the hole concentration in the p-GaN layer. Therefore, in this work, we have proposed a hole modulator and studied it both theoretically and experimentally. In the hole modulator, the holes in a remote p-type doped layer are depleted by the built-in electric field and stored in the p-GaN layer. By this means, the overall hole concentration in the p-GaN layer can be enhanced. Furthermore, the hole modulator is adopted in the InGaN/GaN LEDs, which reduces the effective valance band barrier height for the p-type electron blocking layer from ?332?meV to ?294?meV at 80?A/cm{sup 2} and demonstrates an improved optical performance, thanks to the increased hole concentration in the p-GaN layer and thus the improved hole injection into the MQWs.

  14. Note: A portable, light-emitting diode-based ruby fluorescence spectrometer for high-pressure calibration

    SciTech Connect (OSTI)

    Feng Yejun [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2011-04-15

    Ruby (Al{sub 2}O{sub 3}, with {approx}0.5 wt. % Cr doping) is one of the most widely used manometers at the giga-Pascal scale. Traditionally, its fluorescence is excited with intense laser sources. Here, I present a simple, robust, and portable design that employs light-emitting diodes (LEDs) instead. This LED-based system is safer in comparison with laser-based ones.

  15. Scalable Light Module for Low-Cost, High-Efficiency Light- Emitting Diode Luminaires

    SciTech Connect (OSTI)

    Tarsa, Eric

    2015-08-31

    During this two-year program Cree developed a scalable, modular optical architecture for low-cost, high-efficacy light emitting diode (LED) luminaires. Stated simply, the goal of this architecture was to efficiently and cost-effectively convey light from LEDs (point sources) to broad luminaire surfaces (area sources). By simultaneously developing warm-white LED components and low-cost, scalable optical elements, a high system optical efficiency resulted. To meet program goals, Cree evaluated novel approaches to improve LED component efficacy at high color quality while not sacrificing LED optical efficiency relative to conventional packages. Meanwhile, efficiently coupling light from LEDs into modular optical elements, followed by optimally distributing and extracting this light, were challenges that were addressed via novel optical design coupled with frequent experimental evaluations. Minimizing luminaire bill of materials and assembly costs were two guiding principles for all design work, in the effort to achieve luminaires with significantly lower normalized cost ($/klm) than existing LED fixtures. Chief project accomplishments included the achievement of >150 lm/W warm-white LEDs having primary optics compatible with low-cost modular optical elements. In addition, a prototype Light Module optical efficiency of over 90% was measured, demonstrating the potential of this scalable architecture for ultra-high-efficacy LED luminaires. Since the project ended, Cree has continued to evaluate optical element fabrication and assembly methods in an effort to rapidly transfer this scalable, cost-effective technology to Cree production development groups. The Light Module concept is likely to make a strong contribution to the development of new cost-effective, high-efficacy luminaries, thereby accelerating widespread adoption of energy-saving SSL in the U.S.

  16. Intermediate connector for stacked organic light emitting devices

    DOE Patents [OSTI]

    D'Andrade, Brian

    2013-02-12

    A device is provided, having an anode, a cathode, and an intermediate connector disposed between the anode and the cathode. A first organic layer including an emissive sublayer is disposed between the anode and the intermediate connector, and a second including an emissive sublayer is disposed between the intermediate connector and the cathode. The intermediate connector includes a first metal having a work function lower than 4.0 eV and a second metal having a work function lower than 5.0 eV. The work function of the first metal is at least 0.5 eV less than the work function of the second metal. The first metal is in contact with a sublayer of the second organic layer that includes a material well adapted to receive holes from a low work function metal.

  17. Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

    DOE Patents [OSTI]

    Li, Ting

    2013-08-13

    The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

  18. Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

    DOE Patents [OSTI]

    Li, Ting

    2011-04-26

    The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

  19. Electrical spin injection using GaCrN in a GaN based spin light emitting diode

    SciTech Connect (OSTI)

    Banerjee, D.; Ganguly, S.; Saha, D.; Adari, R.; Sankaranarayan, S.; Kumar, A.; Aldhaheri, R. W.; Hussain, M. A.; Balamesh, A. S.

    2013-12-09

    We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ?2.5% is obtained at 200?K.

  20. Ultraviolet light-emitting diodes grown by plasma-assisted molecular beam epitaxy on semipolar GaN (2021) substrates

    SciTech Connect (OSTI)

    Sawicka, M.; Grzanka, S.; Skierbiszewski, C.; Turski, H.; Muziol, G.; Krysko, M.; Grzanka, E.; Sochacki, T.; Siekacz, M.; Kucharski, R.

    2013-03-18

    Multi-quantum well (MQW) structures and light emitting diodes (LEDs) were grown on semipolar (2021) and polar (0001) GaN substrates by plasma-assisted molecular beam epitaxy. The In incorporation efficiency was found to be significantly lower for the semipolar plane as compared to the polar one. The semipolar MQWs exhibit a smooth surface morphology, abrupt interfaces, and a high photoluminescence intensity. The electroluminescence of semipolar (2021) and polar (0001) LEDs fabricated in the same growth run peaks at 387 and 462 nm, respectively. Semipolar LEDs with additional (Al,Ga)N cladding layers exhibit a higher optical output power but simultaneously a higher turn-on voltage.

  1. 2014-06-18 Issuance: Test Procedure for Integrated Light-Emitting Diode Lamps; Supplemental Notice of Proposed Rulemaking

    Broader source: Energy.gov [DOE]

    This document is a pre-publication Federal Register Supplemental Notice of Proposed Rulemaking regarding Test Procedures for Integrated Light-Emitting Diode Lamps, as issued by the Deputy Assistant Secretary for Energy Efficiency on June 18, 2014. Though it is not intended or expected, should any discrepancy occur between the document posted here and the document published in the Federal Register, the Federal Register publication controls. This document is being made available through the Internet solely as a means to facilitate the public's access to this document.

  2. Device Optimization and Transient Electroluminescence Studies of Organic light Emitting Devices

    SciTech Connect (OSTI)

    Lijuan Zou

    2003-08-05

    Organic light emitting devices (OLEDs) are among the most promising for flat panel display technologies. They are light, bright, flexible, and cost effective. And while they are emerging in commercial product, their low power efficiency and long-term degradation are still challenging. The aim of this work was to investigate their device physics and improve their performance. Violet and blue OLEDs were studied. The devices were prepared by thermal vapor deposition in high vacuum. The combinatorial method was employed in device preparation. Both continuous wave and transient electroluminescence (EL) were studied. A new efficient and intense UV-violet light emitting device was developed. At a current density of 10 mA/cm{sup 2}, the optimal radiance R could reach 0.38 mW/cm{sup 2}, and the quantum efficiency was 1.25%. using the delayed EL technique, electron mobilities in DPVBi and CBP were determined to be {approx} 10{sup -5} cm{sup 2}/Vs and {approx} 10{sup -4} cm{sup 2}/Vs, respectively. Overshoot effects in the transient El of blue light emitting devices were also observed and studied. This effect was attributed to the charge accumulation at the organic/organic and organic/cathode interfaces.

  3. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting in Leavenworth, KS

    SciTech Connect (OSTI)

    Myer, Michael; Kinzey, Bruce R.; Curry, Ku'uipo

    2011-05-06

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in a commercial parking lot lighting application, under the U.S. Department of Energy (DOE) Solid-State Lighting Technology GATEWAY Demonstration Program. The parking lot is for customers and employees of a Walmart Supercenter in Leavenworth, Kansas and this installation represents the first use of the LED Parking Lot Performance Specification developed by the DOE’s Commercial Building Energy Alliance. The application is a parking lot covering more than a half million square feet, lighted primarily by light-emitting diodes (LEDs). Metal halide wall packs were installed along the building facade. This site is new construction, so the installed baseline(s) were hypothetical designs. It was acknowledged early on that deviating from Walmart’s typical design would reduce the illuminance on the site. Walmart primarily uses 1000W pulse-start metal halide (PMH) lamps. In order to provide a comparison between both typical design and a design using conventional luminaires providing a lower illuminance, a 400W PMH design was also considered. As mentioned already, the illuminance would be reduced by shifting from the PMH system to the LED system. The Illuminating Engineering Society of North America (IES) provides recommended minimum illuminance values for parking lots. All designs exceeded the recommended illuminance values in IES RP-20, some by a wider margin than others. Energy savings from installing the LED system compared to the different PMH systems varied. Compared to the 1000W PMH system, the LED system would save 63 percent of the energy. However, this corresponds to a 68 percent reduction in illuminance as well. In comparison to the 400W PMH system, the LED system would save 44 percent of the energy and provide similar minimum illuminance values at the time of relamping. The LED system cost more than either of the PMH systems when comparing initial costs

  4. Organic light-emitting device with a phosphor-sensitized fluorescent emission layer

    DOE Patents [OSTI]

    Forrest, Stephen; Kanno, Hiroshi

    2009-08-25

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters. The emissive region of the devices of the present invention comprise at least one phosphor-sensitized layer which has a combined emission from a phosphorescent emitter and a fluorescent emitter. In preferred embodiments, the invention relates to white-emitting OLEDS (WOLEDs).

  5. Organic light emitting device architecture for reducing the number of organic materials

    DOE Patents [OSTI]

    D'Andrade, Brian; Esler, James

    2011-10-18

    An organic light emitting device is provided. The device includes an anode and a cathode. A first emissive layer is disposed between the anode and the cathode. The first emissive layer includes a first non-emitting organic material, which is an organometallic material present in the first emissive layer in a concentration of at least 50 wt %. The first emissive layer also includes a first emitting organic material. A second emissive layer is disposed between the first emissive layer and the cathode, preferably, in direct contact with the first emissive layer. The second emissive material includes a second non-emitting organic material and a second emitting organic material. The first and second non-emitting materials, and the first and second emitting materials, are all different materials. A first non-emissive layer is disposed between the first emissive layer and the anode, and in direct contact with the first emissive layer. The first non- emissive layer comprises the first non-emissive organic material.

  6. Photonic crystal light emitting diode based on Er and Si nanoclusters co-doped slot waveguide

    SciTech Connect (OSTI)

    Lo Savio, R.; Galli, M.; Liscidini, M.; Andreani, L. C.; Franz, G.; Iacona, F.; Miritello, M.; Irrera, A.; Sanfilippo, D.; Piana, A.; Priolo, F.

    2014-03-24

    We report on the design, fabrication, and electro-optical characterization of a light emitting device operating at 1.54??m, whose active layer consists of silicon oxide containing Er-doped Si nanoclusters. A photonic crystal (PhC) is fabricated on the top-electrode to enhance the light extraction in the vertical direction, and thus the external efficiency of the device. This occurs if a photonic mode of the PhC slab is resonant with the Er emission energy, as confirmed by theoretical calculations and experimental analyses. We measure an increase of the extraction efficiency by a factor of 3 with a high directionality of light emission in a narrow vertical cone. External quantum efficiency and power efficiency are among the highest reported for this kind of material. These results are important for the realization of CMOS-compatible efficient light emitters at telecom wavelengths.

  7. The use of short-period InGaN/GaN superlattices in blue-region light-emitting diodes

    SciTech Connect (OSTI)

    Sizov, V. S., E-mail: vsizov@mail.ioffe.ru; Tsatsulnikov, A. F.; Sakharov, A. V.; Lundin, W. V.; Zavarin, E. E.; Cherkashin, N. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Hytch, M. J. [National Center for Scientific Research (CNRS), Center for Material Elaboration and Structural Studies (CEMES) (France); Nikolaev, A. E. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Mintairov, A. M.; He Yan; Merz, J. L. [University of Notre Dame, EE Department (United States)

    2010-07-15

    Optical and light-emitting diode structures with an active InGaN region containing short-period InGaN/GaN superlattices are studied. It is shown that short-period superlattices are thin two-dimensional layers with a relatively low In content that contain inclusions with a high In content 1-3 nm thick. Inclusions manifest themselves from the point of view of optical properties as a nonuniform array of quantum dots involved in a residual quantum well. The use of short-period superlattices in light-emitting diode structures allows one to decrease the concentration of nonradiative centers, as well as to increase the injection of carriers in the active region due to an increase in the effective height of the AlGaN barrier, which in general leads to an increase in the quantum efficiency of light-emitting diodes.

  8. Analysis of dominant carrier recombination mechanisms depending on injection current in InGaN green light emitting diodes

    SciTech Connect (OSTI)

    Kim, Kyu-Sang; Han, Dong-Pyo; Kim, Hyun-Sung; Shim, Jong-In

    2014-03-03

    Two kinds of green InGaN light emitting diodes (LEDs) have been investigated in order to understand the different slopes in logarithmic light output power-current (L-I) curves. Through the analysis of the carrier rate equation and by considering the carrier density-dependent the injection efficiency into quantum wells, the slopes of the logarithmic L-I curves can be more rigorously understood. The low current level, two as the tunneling current is initially dominant. The high current level beyond the peak of the external quantum efficiency (EQE) diminishes below one as the carrier overflow becomes dominant. In addition, the normalized carrier injection efficiency can be obtained by analyzing the slopes of the logarithmic L-I curves. The carrier injection efficiency decreases after the EQE peak of the InGaN LEDs, determined from the analysis of the slopes of the logarithmic L-I curves.

  9. Recoverable degradation of blue InGaN-based light emitting diodes submitted to 3?MeV proton irradiation

    SciTech Connect (OSTI)

    De Santi, C.; Meneghini, M. Trivellin, N.; Gerardin, S.; Bagatin, M.; Paccagnella, A.; Meneghesso, G.; Zanoni, E.

    2014-11-24

    This paper reports on the degradation and recovery of two different series of commercially available InGaN-based blue light emitting diodes submitted to proton irradiation at 3?MeV and various fluences (10{sup 11}, 10{sup 13}, and 10{sup 14}?p{sup +}/cm{sup 2}). After irradiation, we detected (i) an increase in the series resistance, in the sub-turn-on current and in the ideality factor, (ii) a spatially uniform drop of the output optical power, proportional to fluence, and (iii) a reduction of the capacitance of the devices. These results suggest that irradiation induced the generation of non-radiative recombination centers near the active region. This hypothesis is further confirmed by the results of the recovery tests carried out at low temperature (150?C)

  10. Demonstration Assessment of Light-Emitting Diode Parking Structure Lighting at U.S. Department of Labor Headquarters

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael

    2013-03-01

    This report documents a solid-state lighting (SSL) technology demonstration at the parking structure of the U.S. Department of Labor (DOL) Headquarters in Washington, DC, in which light-emitting diode (LED) luminaires were substituted for the incumbent high-pressure sodium (HPS) luminaires and evaluated for relative light quantity and performance. The demonstration results show energy savings of 52% from the initial conversion of HPS to the LED product. These savings were increased to 88% by using occupancy sensor controls that were ultimately set to reduce power to 10% of high state operation after a time delay of 2.5 minutes. Because of the relatively high cost of the LED luminaires at their time of purchase for this project (2010), the simple payback periods were 6.5 years and 4.9 years for retrofit and new construction scenarios, respectively. Staff at DOL Headquarters reported high satisfaction with the operation of the LED product.

  11. Direct periodic patterning of GaN-based light-emitting diodes by three-beam interference laser ablation

    SciTech Connect (OSTI)

    Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch; Yuan, Dajun; Guo, Rui; Liu, Jianping; Asadirad, Mojtaba; Kwon, Min-Ki; Dupuis, Russell D.; Das, Suman; Ryou, Jae-Hyun

    2014-04-07

    We report on the direct patterning of two-dimensional periodic structures in GaN-based light-emitting diodes (LEDs) through laser interference ablation for the fast and reliable fabrication of periodic micro- and nano-structures aimed at enhancing light output. Holes arranged in a two-dimensional hexagonal lattice array having an opening size of 500?nm, depth of 50?nm, and a periodicity of 1??m were directly formed by three-beam laser interference without photolithography or electron-beam lithography processes. The laser-patterned LEDs exhibit an enhancement in light output power of 20% compared to conventional LEDs having a flat top surface without degradation of electrical and optical properties of the top p-GaN layer and the active region, respectively.

  12. Ultraviolet emission from a multi-layer graphene/MgZnO/ZnO light-emitting diode

    SciTech Connect (OSTI)

    Kang, Jang-Won; Choi, Yong-Seok; Goo Kang, Chang; Hun Lee, Byoung [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Byeong-Hyeok [Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407 (United States); Park, Seong-Ju, E-mail: sjpark@gist.ac.kr [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2014-02-03

    We report on ultraviolet emission from a multi-layer graphene (MLG)/MgZnO/ZnO light-emitting diodes (LED). The p-type MLG and MgZnO in the MLG/MgZnO/ZnO LED are used as transparent hole injection and electron blocking layers, respectively. The current-voltage characteristics of the MLG/MgZnO/ZnO LED show that current transport is dominated by tunneling processes in the MgZnO barrier layer under forward bias conditions. The holes injected from p-type MLG recombine efficiently with the electrons accumulated in ZnO, and the MLG/MgZnO/ZnO LED shows strong ultraviolet emission from the band edge of ZnO and weak red-orange emission from the deep levels of ZnO.

  13. Enhancement in light emission and electrical efficiencies of a silicon nanocrystal light-emitting diode by indium tin oxide nanowires

    SciTech Connect (OSTI)

    Huh, Chul, E-mail: chuh@etri.re.kr; Kim, Bong Kyu; Ahn, Chang-Geun; Kim, Sang-Hyeob [IT Convergence Technology Research Laboratory, Electronics and Telecommunications Research Institute, Daejeon 305-350 (Korea, Republic of); Choi, Chel-Jong [Department of BIN Fusion Technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2014-07-21

    We report an enhancement in light emission and electrical efficiencies of a Si nanocrystal (NC) light-emitting diode (LED) by employing indium tin oxide (ITO) nanowires (NWs). The formed ITO NWs (diameter?

  14. Differential spectral responsivity measurement of photovoltaic detectors with a light-emitting-diode-based integrating sphere source

    SciTech Connect (OSTI)

    Zaid, Ghufron; Park, Seung-Nam; Park, Seongchong; Lee, Dong-Hoon

    2010-12-10

    We present an experimental realization of differential spectral responsivity measurement by using a light-emitting diode (LED)-based integrating sphere source. The spectral irradiance responsivity is measured by a Lambertian-like radiation field with a diameter of 40mm at the peak wavelengths of the 35 selectable LEDs covering a range from 280 to 1550nm. The systematic errors and uncertainties due to lock-in detection, spatial irradiance distribution, and reflection from the test detector are experimentally corrected or considered. In addition, we implemented a numerical procedure to correct the error due to the broad spectral bandwidth of the LEDs. The overall uncertainty of the DSR measurement is evaluated to be 2.2% (k=2) for Si detectors. To demonstrate its application, we present the measurement results of two Si photovoltaic detectors at different bias irradiance levels up to 120mW/cm{sup 2}.

  15. High efficiency single Ag nanowire/p-GaN substrate Schottky junction-based ultraviolet light emitting diodes

    SciTech Connect (OSTI)

    Wu, Y.; Li, X.; Xu, P.; Wang, Y.; Shen, X.; Liu, X.; Yang, Q.; Hasan, T.

    2015-02-02

    We report a high efficiency single Ag nanowire (NW)/p-GaN substrate Schottky junction-based ultraviolet light emitting diode (UV-LED). The device demonstrates deep UV free exciton electroluminescence at 362.5?nm. The dominant emission, detectable at ultralow (<1??A) forward current, does not exhibit any shifts when the forward current is increased. External quantum efficiency (EQE) as high as 0.9% is achieved at 25??A current at room temperature. Experiments and simulation analysis show that devices fabricated with thinner Ag NWs have higher EQE. However, for very thin Ag NWs (diameter?

  16. Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps at the Lobby of the Bonneville Power Administration, Portland, OR

    SciTech Connect (OSTI)

    Miller, Naomi

    2011-07-01

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in the lobby of the Bonneville Power Administration (BPA) headquarters building in Portland, Oregon. The project involved a simple retrofit of 32 track lights used to illuminate historical black-and-white photos and printed color posters from the 1930s and 1940s. BPA is a federal power marketing agency in the Northwestern United States, and selected this prominent location to demonstrate energy efficient light-emitting diode (LED) retrofit options that not only can reduce the electric bill for their customers but also provide attractive alternatives to conventional products, in this case accent lighting for BPA's historical artwork.

  17. Enhanced Light Extraction from Organic Light Emitting Diodes - Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Systems » Enhanced Geothermal Systems Demonstration Projects Enhanced Geothermal Systems Demonstration Projects A significant long-term opportunity for widespread power production from new geothermal sources lies in Enhanced Geothermal Systems (EGS), where innovative technology development and deployment could facilitate access to 100+ GW of energy, exponentially more than today's current geothermal capacity. With EGS, we can tap otherwise inaccessible resources in areas that lack traditional

  18. p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Tiam Tan, Swee; Kyaw, Zabu; Liu, Wei; Ji, Yun; Ju, Zhengang; Zhang, Xueliang [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore) [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wei Sun, Xiao, E-mail: EXWSUN@ntu.edu.sg [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electronics and Electrical Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Volkan Demir, Hilmi, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electrical and Electronics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey); Department of Physics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey)

    2013-12-23

    Here, GaN/Al{sub x}Ga{sub 1-x}N heterostructures with a graded AlN composition, completely lacking external p-doping, are designed and grown using metal-organic-chemical-vapour deposition (MOCVD) system to realize three-dimensional hole gas (3DHG). The existence of the 3DHG is confirmed by capacitance-voltage measurements. Based on this design, a p-doping-free InGaN/GaN light-emitting diode (LED) driven by the 3DHG is proposed and grown using MOCVD. The electroluminescence, which is attributed to the radiative recombination of injected electrons and holes in InGaN/GaN quantum wells, is observed from the fabricated p-doping-free devices. These results suggest that the 3DHG can be an alternative hole source for InGaN/GaN LEDs besides common Mg dopants.

  19. Characterization of electrically-active defects in ultraviolet light-emitting diodes with laser-based failure analysis techniques

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Miller, Mary A.; Tangyunyong, Paiboon; Edward I. Cole, Jr.

    2016-01-12

    In this study, laser-based failure analysis techniques demonstrate the ability to quickly and non-intrusively screen deep ultraviolet light-emitting diodes(LEDs) for electrically-active defects. In particular, two laser-based techniques, light-induced voltage alteration and thermally-induced voltage alteration, generate applied voltage maps (AVMs) that provide information on electrically-active defect behavior including turn-on bias, density, and spatial location. Here, multiple commercial LEDs were examined and found to have dark defect signals in the AVM indicating a site of reduced resistance or leakage through the diode. The existence of the dark defect signals in the AVM correlates strongly with an increased forward-bias leakage current. This increasedmore » leakage is not present in devices without AVM signals. Transmission electron microscopyanalysis of a dark defect signal site revealed a dislocation cluster through the pn junction. The cluster included an open core dislocation. Even though LEDs with few dark AVM defect signals did not correlate strongly with power loss, direct association between increased open core dislocation densities and reduced LED device performance has been presented elsewhere [M. W. Moseley et al., J. Appl. Phys. 117, 095301 (2015)].« less

  20. Enhancement of efficiencies for tandem green phosphorescent organic light-emitting devices with a p-type charge generation layer

    SciTech Connect (OSTI)

    Yoo, Byung Soo; Jeon, Young Pyo; Lee, Dae Uk; Kim, Tae Whan

    2014-10-15

    The operating voltage of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was improved by 3% over that of the organic light-emitting device with a molybdenum trioxide layer. The maximum brightness of the tandem green phosphorescent organic light-emitting device at 21.9 V was 26,540 cd/m{sup 2}. The dominant peak of the electroluminescence spectra for the devices was related to the fac-tris(2-phenylpyridine) iridium emission. - Highlights: Tandem OLEDs with CGL were fabricated to enhance their efficiency. The operating voltage of the tandem OLED with a HAT-CN layer was improved by 3%. The efficiency and brightness of the tandem OLED were 13.9 cd/A and 26,540 cd/m{sup 2}. Efficiency of the OLED with a HAT-CN layer was lower than that with a MoO{sub 3} layer. - Abstract: Tandem green phosphorescent organic light-emitting devices with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile or a molybdenum trioxide charge generation layer were fabricated to enhance their efficiency. Current densityvoltage curves showed that the operating voltage of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was improved by 3% over that of the corresponding organic light-emitting device with a molybdenum trioxide layer. The efficiency and the brightness of the tandem green phosphorescent organic light-emitting device were 13.9 cd/A and 26,540 cd/m{sup 2}, respectively. The current efficiency of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was lower by 1.1 times compared to that of the corresponding organic light-emitting device with molybdenum trioxide layer due to the decreased charge generation and transport in the 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer resulting from triplettriplet exciton annihilation.

  1. An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode

    SciTech Connect (OSTI)

    Mehta, M.; Michaelis de Vasconcellos, S.; Zrenner, A.; Meier, C. [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Street 100, 33098 Paderborn (Germany); Reuter, D.; Wieck, A. D. [Applied Solid State Physics, Ruhr-University of Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

    2010-10-04

    We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski-Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.

  2. Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

    SciTech Connect (OSTI)

    Glaab, Johannes Ploch, Christian; Kelz, Rico; Stölmacker, Christoph; Lapeyrade, Mickael; Ploch, Neysha Lobo; Rass, Jens; Kolbe, Tim; Einfeldt, Sven; Weyers, Markus; Mehnke, Frank; Kuhn, Christian; Wernicke, Tim; Kneissl, Michael

    2015-09-07

    The degradation of the electrical and optical properties of (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm{sup 2}, 150 A/cm{sup 2}, and 225 A/cm{sup 2}. In addition, the heat sink temperature was varied between 15 °C and 80 °C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the current-voltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current.

  3. Efficient carrier relaxation and fast carrier recombination of N-polar InGaN/GaN light emitting diodes

    SciTech Connect (OSTI)

    Feng, Shih-Wei Liao, Po-Hsun; Leung, Benjamin; Han, Jung; Yang, Fann-Wei; Wang, Hsiang-Chen

    2015-07-28

    Based on quantum efficiency and time-resolved electroluminescence measurements, the effects of carrier localization and quantum-confined Stark effect (QCSE) on carrier transport and recombination dynamics of Ga- and N-polar InGaN/GaN light-emitting diodes (LEDs) are reported. The N-polar LED exhibits shorter ns-scale response, rising, delay, and recombination times than the Ga-polar one does. Stronger carrier localization and the combined effects of suppressed QCSE and electric field and lower potential barrier acting upon the forward bias in an N-polar LED provide the advantages of more efficient carrier relaxation and faster carrier recombination. By optimizing growth conditions to enhance the radiative recombination, the advantages of more efficient carrier relaxation and faster carrier recombination in a competitive performance N-polar LED can be realized for applications of high-speed flash LEDs. The research results provide important information for carrier transport and recombination dynamics of an N-polar InGaN/GaN LED.

  4. Strong geometrical effects in submillimeter selective area growth and light extraction of GaN light emitting diodes on sapphire

    SciTech Connect (OSTI)

    Tanaka, Atsunori; Chen, Renjie; Jungjohann, Katherine L.; Dayeh, Shadi A.

    2015-11-27

    Advanced semiconductor devices often utilize structural and geometrical effects to tailor their characteristics and improve their performance. Our detailed understanding of such geometrical effects in the epitaxial selective area growth of GaN on sapphire substrates is reported here, and we utilize them to enhance light extraction from GaN light emitting diodes. Systematic size and spacing effects were performed side-by-side on a single 2” sapphire substrate to minimize experimental sampling errors for a set of 144 pattern arrays with circular mask opening windows in SiO2. We show that the mask opening diameter leads to as much as 4 times increase in the thickness of the grown layers for 20 μm spacings and that spacing effects can lead to as much as 3 times increase in thickness for a 350 μm dot diameter. We also observed that the facet evolution in comparison with extracted Ga adatom diffusion lengths directly influences the vertical and lateral overgrowth rates and can be controlled with pattern geometry. Lastly, such control over the facet development led to 2.5 times stronger electroluminescence characteristics from well-faceted GaN/InGaN multiple quantum well LEDs compared to non-faceted structures.

  5. Strong geometrical effects in submillimeter selective area growth and light extraction of GaN light emitting diodes on sapphire

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tanaka, Atsunori; Chen, Renjie; Jungjohann, Katherine L.; Dayeh, Shadi A.

    2015-11-27

    Advanced semiconductor devices often utilize structural and geometrical effects to tailor their characteristics and improve their performance. Our detailed understanding of such geometrical effects in the epitaxial selective area growth of GaN on sapphire substrates is reported here, and we utilize them to enhance light extraction from GaN light emitting diodes. Systematic size and spacing effects were performed side-by-side on a single 2” sapphire substrate to minimize experimental sampling errors for a set of 144 pattern arrays with circular mask opening windows in SiO2. We show that the mask opening diameter leads to as much as 4 times increase inmore » the thickness of the grown layers for 20 μm spacings and that spacing effects can lead to as much as 3 times increase in thickness for a 350 μm dot diameter. We also observed that the facet evolution in comparison with extracted Ga adatom diffusion lengths directly influences the vertical and lateral overgrowth rates and can be controlled with pattern geometry. Lastly, such control over the facet development led to 2.5 times stronger electroluminescence characteristics from well-faceted GaN/InGaN multiple quantum well LEDs compared to non-faceted structures.« less

  6. Failure Mechanisms and Color Stability in Light-Emitting Diodes during Operation in High- Temperature Environments in Presence of Contamination

    SciTech Connect (OSTI)

    Lall, Pradeep; Zhang, Hao; Davis, J Lynn

    2015-05-26

    The energy efficiency of light-emitting diode (LED) technology compared to incandescent light bulbs has triggered an increased focus on solid state luminaries for a variety of lighting applications. Solid-state lighting (SSL) utilizes LEDs, for illumination through the process of electroluminescence instead of heating a wire filament as seen with traditional lighting. The fundamental differences in the construction of LED and the incandescent lamp results in different failure modes including lumen degradation, chromaticity shift and drift in the correlated color temperature. The use of LED-based products for safety-critical and harsh environment applications necessitates the characterization of the failure mechanisms and modes. In this paper, failure mechanisms and color stability has been studied for commercially available vertical structured thin film LED (VLED) under harsh environment conditions with and without the presence of contaminants. The VLED used for the study was mounted on a ceramic starboard in order to connect it to the current source. Contamination sources studied include operation in the vicinity of vulcanized rubber and adhesive epoxies in the presence of temperature and humidity. Performance of the VLEDs has been quantified using the measured luminous flux and color shift of the VLEDs subjected to both thermal and humidity stresses under a forward current bias of 350 mA. Results indicate that contamination can result in pre-mature luminous flux degradation and color shift in LEDs.

  7. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes

    SciTech Connect (OSTI)

    Reich, Christoph Guttmann, Martin; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian; Feneberg, Martin; Goldhahn, Rüdiger; Rass, Jens; Kneissl, Michael; Lapeyrade, Mickael; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Weyers, Markus

    2015-10-05

    The optical polarization of emission from ultraviolet (UV) light emitting diodes (LEDs) based on (0001)-oriented Al{sub x}Ga{sub 1−x}N multiple quantum wells (MQWs) has been studied by simulations and electroluminescence measurements. With increasing aluminum mole fraction in the quantum well x, the in-plane intensity of transverse-electric (TE) polarized light decreases relative to that of the transverse-magnetic polarized light, attributed to a reordering of the valence bands in Al{sub x}Ga{sub 1−x}N. Using k ⋅ p theoretical model calculations, the AlGaN MQW active region design has been optimized, yielding increased TE polarization and thus higher extraction efficiency for bottom-emitting LEDs in the deep UV spectral range. Using (i) narrow quantum wells, (ii) barriers with high aluminum mole fractions, and (iii) compressive growth on patterned aluminum nitride sapphire templates, strongly TE-polarized emission was observed at wavelengths as short as 239 nm.

  8. A novel theoretical model for broadband blue InGaN/GaN superluminescent light emitting diodes

    SciTech Connect (OSTI)

    Moslehi Milani, N.; Mohadesi, V.; Asgari, A.

    2015-02-07

    A broadband superluminescent light emitting diode with In{sub 0.2}Ga{sub 0.8}N/GaN multiple quantum wells (MQWs) active region is investigated. The investigation is based on a theoretical model which includes the calculation of electronic states of the structure, rate equations, and the spectral radiation power. Two rate equations corresponding to MQW active region and separate confinement heterostructures layer are solved self-consistently with no-k selection wavelength dependent gain and quasi-Fermi level functions. Our results show that the superluminescence started in a current of ∼120 mA (∼7.5 kA/Cm{sup 2}) at 300 K. The range of peak emission wavelengths for different currents is 423–426 nm and the emission bandwidth is ∼5 nm in the superluminescence regime. A maximum light output power of 7.59 mW is obtained at 600 mA and the peak modal gain as a function of current indicates logarithmic behavior. Also, the comparison of our calculated results with published experimental data is shown to be in good agreement.

  9. Organic Light-Emitting Devices (OLEDS) and Their Optically Detected Magnetic Resonance (ODMR)

    SciTech Connect (OSTI)

    Gang Li

    2003-12-12

    Organic Light-Emitting Devices (OLEDs), both small molecular and polymeric have been studied extensively since the first efficient small molecule OLED was reported by Tang and VanSlyke in 1987. Burroughes' report on conjugated polymer-based OLEDs led to another track in OLED development. These developments have resulted in full color, highly efficient (up to {approx} 20% external efficiency 60 lm/W power efficiency for green emitters), and highly bright (> 140,000 Cd/m{sup 2} DC, {approx}2,000,000 Cd/m{sup 2} AC), stable (>40,000 hr at 5 mA/cm{sup 2}) devices. OLEDs are Lambertian emitters, which intrinsically eliminates the view angle problem of liquid crystal displays (LCDs). Thus OLEDs are beginning to compete with the current dominant LCDs in information display. Numerous companies are now active in this field, including large companies such as Pioneer, Toyota, Estman Kodak, Philipps, DuPont, Samsung, Sony, Toshiba, and Osram, and small companies like Cambridge Display Technology (CDT), Universal Display Corporation (UDC), and eMagin. The first small molecular display for vehicular stereos was introduced in 1998, and polymer OLED displays have begun to appear in commercial products. Although displays are the major application for OLEDs at present, they are also candidates for nest generation solid-state lighting. In this case the light source needs to be white in most cases. Organic transistors, organic solar cells, etc. are also being developed vigorously.

  10. Edge electroluminescence of the effective silicon point-junction light-emitting diode in the temperature range 80-300 K

    SciTech Connect (OSTI)

    Emel'yanov, A. M. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: Emelyanov@mail.ioffe.ru

    2008-11-15

    The edge electroluminescence spectra of silicon point-junction light-emitting diodes with a p-n junction area of 0.008 mm{sup 2} are studied at temperatures ranging from 80 to 300 K. Unprecedentedly high stability of the position of the spectral peak is observed at temperatures in the range between 130 and 300 K. The spectral characteristics of the light emitting diodes are studied at 80 K at different current densities up to 25 kA/cm{sup 2}. In contrast to the earlier reported data obtained at 300 K, the data obtained at 80 K do not show any noticeable Augerrecombination-related decrease in the quantum efficiency. From an analysis of the electroluminescence spectra at 80 K in a wide range of currents, it follows that radiative annihilation of free excitons is not a governing mechanism of electroluminescence in the entire emitting region in the base of the point-junction light-emitting diode at all currents used in the experiment.

  11. Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO{sub 2} thin film

    SciTech Connect (OSTI)

    Kang, Seung-Hee; Kumar, Ch. Kiran; Kim, Eui-Tae; Lee, Zonghoon; Kim, Kyung-Hyun; Huh, Chul

    2008-11-10

    Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO{sub 2} thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO{sub 2}/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO{sub 2}/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

  12. Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes

    SciTech Connect (OSTI)

    Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun, E-mail: tongjun@pku.edu.cn; Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

    2014-03-07

    Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on kp approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

  13. Roles of V-shaped pits on the improvement of quantum efficiency in InGaN/GaN multiple quantum well light-emitting diodes

    SciTech Connect (OSTI)

    Quan, Zhijue Wang, Li Zheng, Changda; Liu, Junlin; Jiang, Fengyi

    2014-11-14

    The roles of V-shaped pits on the improvement of quantum efficiency in InGaN/GaN multiple quantum well (MQW) light-emitting diodes are investigated by numerical simulation. The simulation results show that V-shaped pits cannot only screen dislocations, but also play an important role on promoting hole injection into the MQWs. It is revealed that the injection of holes into the MQW via the sidewalls of the V-shaped pits is easier than via the flat region, due to the lower polarization charge densities in the sidewall structure with lower In concentration and (1011)-oriented semi-polar facets.

  14. Origin of InGaN/GaN light-emitting diode efficiency improvements using tunnel-junction-cascaded active regions

    SciTech Connect (OSTI)

    Piprek, Joachim

    2014-02-03

    This Letter investigates the efficiency enhancement achieved by tunnel junction insertion into the InGaN/GaN multi-quantum well (MQW) active region of blue light emitting diodes (LEDs). The peak quantum efficiency of such LED exceeds 100%, but the maximum wall-plug efficiency (WPE) hardly changes. However, due to the increased bias, the WPE peaks at much higher input power, i.e., the WPE droop is significantly delayed, and the output power is strongly enhanced. The main physical reason for this improvement lies in the non-uniform vertical carrier distribution typically observed within InGaN MQWs.

  15. Tunnel-injection quantum dot deep-ultraviolet light-emitting diodes with polarization-induced doping in III-nitride heterostructures

    SciTech Connect (OSTI)

    Verma, Jai Islam, S. M.; Protasenko, Vladimir; Kumar Kandaswamy, Prem; Xing, Huili; Jena, Debdeep

    2014-01-13

    Efficient semiconductor optical emitters in the deep-ultraviolet spectral window are encountering some of the most deep rooted problems of semiconductor physics. In III-Nitride heterostructures, obtaining short-wavelength photon emission requires the use of wide bandgap high Al composition AlGaN active regions. High conductivity electron (n-) and hole (p-) injection layers of even higher bandgaps are necessary for electrical carrier injection. This approach requires the activation of very deep dopants in very wide bandgap semiconductors, which is a difficult task. In this work, an approach is proposed and experimentally demonstrated to counter the challenges. The active region of the heterostructure light emitting diode uses ultrasmall epitaxially grown GaN quantum dots. Remarkably, the optical emission energy from GaN is pushed from 365?nm (3.4?eV, the bulk bandgap) to below 240?nm (>5.2?eV) because of extreme quantum confinement in the dots. This is possible because of the peculiar bandstructure and band alignments in the GaN/AlN system. This active region design crucially enables two further innovations for efficient carrier injection: Tunnel injection of carriers and polarization-induced p-type doping. The combination of these three advances results in major boosts in electroluminescence in deep-ultraviolet light emitting diodes and lays the groundwork for electrically pumped short-wavelength lasers.

  16. Bicolor Mn-doped CuInS{sub 2}/ZnS core/shell nanocrystals for white light-emitting diode with high color rendering index

    SciTech Connect (OSTI)

    Huang, Bo; Dai, Qian; Zhang, Huichao; Liao, Chen; Cui, Yiping; Zhang, Jiayu; Zhuo, Ningze; Jiang, Qingsong; Shi, Fenghua; Wang, Haibo

    2014-09-07

    We synthesized bicolor Mn-doped CuInS{sub 2} (CIS)/ZnS core/shell nanocrystals (NCs), in which Mn{sup 2+} ions and the CIS core were separated with a ZnS layer, and both Mn{sup 2+} ions and CIS cores could emit simultaneously. Transmission electron microscopy and powder X-ray diffraction measurements indicated the epitaxial growth of ZnS shell on the CuInS{sub 2} core, and electron paramagnetic resonance spectrum indicated that Mn{sup 2+} ions were on the lattice points of ZnS shell. By integrating these bicolor NCs with commercial InGaN-based blue-emitting diodes, tricolor white light-emitting diodes with color rendering index of 83 were obtained.

  17. Demonstration Assessment of Light Emitting Diode (LED) Commercial Garage Lights In the Providence Portland Medical Center, Portland, Oregon

    SciTech Connect (OSTI)

    Ton, My K.; Richman, Eric E.; Gilbride, Theresa L.

    2008-11-11

    This U.S. Department of Energy GATEWAY Demonstration project studied the applicability of light-emitting diode (LED) luminaires for commercial parking garage applications. High-pressure sodium (HPS) area luminaires were replaced with new LED area luminaires. The project was supported under the U.S. Department of Energy (DOE) Solid State Lighting Program. Other participants in the demonstration project included Providence Portland Medical Center in Portland, Oregon, the Energy Trust of Oregon, and Lighting Sciences Group (LSG) Inc. Pacific Northwest National Laboratory (PNNL) conducted the measurements and analysis of the results. PNNL manages GATEWAY demonstrations for DOE and represents their perspective in the conduct of the work. Quantitative and qualitative measurements of light and electrical power were taken at the site for both HPS and LED light sources. Economic costs were estimated and garage users’ responses to the new light sources were gauged with a survey. Six LED luminaires were installed in the below-ground parking level A, replacing six existing 150W HPS lamps spread out over two rows of parking spaces. Illuminance measurements were taken at floor level approximately every 4 ft on a 60-ft x 40-ft grid to measure light output of these LED luminaires which were termed the “Version 1” luminaires. PNNL conducted power measurements of the circuit in the garage to which the 6 luminaires were connected and determined that they drew an average of 82 W per lamp. An improved LED luminaire, Version 2, was installed in Level B of the parking garage. Illuminance measurements were not made of this second luminaire on site due to higher traffic conditions, but photometric measurements of this lamp and Version 1 were made in an independent testing laboratory and power usage for Version 2 was also measured. Version 1 was found to produce 3600 lumens and Version 2 was found to produce 4700 lumens of light and to consume 78 Watts. Maximum and minimum light

  18. 2014-06-18 Issuance: Test Procedure for Integrated Light-Emitting...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    18 Issuance: Test Procedure for Integrated Light-Emitting Diode Lamps; Supplemental Notice of Proposed Rulemaking 2014-06-18 Issuance: Test Procedure for Integrated Light-Emitting ...

  19. Investigating the origin of efficiency droop by profiling the temperature across the multi-quantum well of an operating light-emitting diode

    SciTech Connect (OSTI)

    Jung, Euihan; Hwang, Gwangseok; Chung, Jaehun; Kwon, Ohmyoung; Han, Jaecheon; Moon, Yong-Tae; Seong, Tae-Yeon

    2015-01-26

    Performance degradation resulting from efficiency droop during high-power operation is a critical problem in the development of high-efficiency light-emitting diodes (LEDs). In order to resolve the efficiency droop and increase the external quantum efficiency of LEDs, the droop's origin should be identified first. To experimentally investigate the cause of efficiency droop, we used null-point scanning thermal microscopy to quantitatively profile the temperature distribution on the cross section of the epi-layers of an operating GaN-based vertical LED with nanoscale spatial resolution at four different current densities. The movement of temperature peak towards the p-GaN side as the current density increases suggests that more heat is generated by leakage current than by Auger recombination. We therefore suspect that at higher current densities, current leakage becomes the dominant cause of the droop problem.

  20. Strong carrier localization effect in carrier dynamics of 585 nm InGaN amber light-emitting diodes

    SciTech Connect (OSTI)

    Li, Panpan; Li, Hongjian; Li, Zhi; Kang, Junjie; Yi, Xiaoyan; Li, Jinmin; Wang, Guohong

    2015-02-21

    Temperature dependence and time-resolved photoluminescence (TRPL) have been carried out to study carrier dynamics for 585 nm InGaN amber light-emitting diodes (LEDs). It is found that in InGaN amber LEDs, peak emission energy only shows a slight blueshift from 588 to 575 nm, as temperature increased from 10 K to 300 K. Moreover, radiative recombination lifetime has demonstrated independent of temperature based TRPL results. These two features indicate that a strong carrier localization effect plays a dominant role in carrier dynamics for InGaN amber LEDs. Also, activation energy of 40.3 meV is obtained through Arrhenius plot of PL intensity versus temperature.

  1. Characterization of the deep levels responsible for non-radiative recombination in InGaN/GaN light-emitting diodes

    SciTech Connect (OSTI)

    Meneghini, M. La Grassa, M.; Vaccari, S.; Meneghesso, G.; Zanoni, E.

    2014-03-17

    This paper presents an extensive investigation of the deep levels related to non-radiative recombination in InGaN/GaN light-emitting diodes (LEDs). The study is based on combined optical and deep-level transient spectroscopy measurements, carried out on LEDs with identical structure and with different values of the non-radiative recombination coefficient. Experimental data lead to the following, relevant, results: (i) LEDs with a high non-radiative recombination coefficient have a higher concentration of a trap (labeled as e{sub 2}) with an activation energy of 0.7 eV, which is supposed to be located close to/within the active region; (ii) measurements carried out with varying filling pulse duration suggest that this deep level behaves as a point-defect/dislocation complex. The Arrhenius plot of this deep level is critically compared with the previous literature reports, to identify its physical origin.

  2. Further reduction of efficiency droop effect by adding a lower-index dielectric interlayer in a surface plasmon coupled blue light-emitting diode with surface metal nanoparticles

    SciTech Connect (OSTI)

    Lin, Chun-Han; Su, Chia-Ying; Chen, Chung-Hui; Yao, Yu-Feng; Shih, Pei-Ying; Chen, Horng-Shyang; Hsieh, Chieh; Kiang, Yean-Woei Yang, C. C.; Kuo, Yang

    2014-09-08

    Further reduction of the efficiency droop effect and further enhancements of internal quantum efficiency (IQE) and output intensity of a surface plasmon coupled, blue-emitting light-emitting diode (LED) by inserting a dielectric interlayer (DI) of a lower refractive index between p-GaN and surface Ag nanoparticles are demonstrated. The insertion of a DI leads to a blue shift of the localized surface plasmon (LSP) resonance spectrum and increases the LSP coupling strength at the quantum well emitting wavelength in the blue range. With SiO{sub 2} as the DI, a thinner DI leads to a stronger LSP coupling effect, when compared with the case of a thicker DI. By using GaZnO, which is a dielectric in the optical range and a good conductor under direct-current operation, as the DI, the LSP coupling results in the highest IQE, highest LED output intensity, and weakest droop effect.

  3. Inversion by metalorganic chemical vapor deposition from N- to Ga-polar gallium nitride and its application to multiple quantum well light-emitting diodes

    SciTech Connect (OSTI)

    Hosalli, A. M.; Van Den Broeck, D. M.; Bedair, S. M. [Department of Electrical and Computer Engineering, NCSU, Raleigh, North Carolina 27695 (United States)] [Department of Electrical and Computer Engineering, NCSU, Raleigh, North Carolina 27695 (United States); Bharrat, D.; El-Masry, N. A. [Department of Material Science and Engineering, NCSU, Raleigh, North Carolina 27695 (United States)] [Department of Material Science and Engineering, NCSU, Raleigh, North Carolina 27695 (United States)

    2013-12-02

    We demonstrate a metalorganic chemical vapor deposition growth approach for inverting N-polar to Ga-polar GaN by using a thin inversion layer grown with high Mg flux. The introduction of this inversion layer allowed us to grow p-GaN films on N-polar GaN thin film. We have studied the dependence of hole concentration, surface morphology, and degree of polarity inversion for the inverted Ga-polar surface on the thickness of the inversion layer. We then use this approach to grow a light emitting diode structure which has the MQW active region grown on the advantageous N-polar surface and the p-layer grown on the inverted Ga-polar surface.

  4. A quantitative method for determination of carrier escape efficiency in GaN-based light-emitting diodes: A comparison of open- and short-circuit photoluminescence

    SciTech Connect (OSTI)

    Lim, Seung-Hyuk; Ko, Young-Ho; Cho, Yong-Hoon

    2014-03-03

    We propose a method to quantitatively analyze the internal quantum efficiency (IQE) as well as the efficiencies of non-radiative recombination in the active region (NRA) and carrier escape out of the active region (ESC) by comparing open-circuit (OC) to short-circuit (SC) conditions of InGaN-based light-emitting diodes (LEDs). First, the IQE was extracted from excitation-power dependent photoluminescence at low temperature, and the electron-hole wavefunction overlaps were calculated under OC and SC conditions. Then, the NRA and ESC efficiencies were quantitatively deduced and also compared with photocurrent data. The proposed method would be useful for assessing and designing quantum barriers and analyzing leakage current in LEDs.

  5. Highly efficient blue organic light emitting device using indium-free transparent anode Ga:ZnO with scalability for large area coating

    SciTech Connect (OSTI)

    Wang, Liang; Matson, Dean W.; Polikarpov, Evgueni; Swensen, James S.; Bonham, Charles C.; Cosimbescu, Lelia; Berry, J. J.; Ginley, D. S.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2010-02-15

    The availability of economically-produced and environmentally-stable transparent conductive oxide (TCO) coatings is critical for the development of a variety of electronic devices requiring transparent electrodes. Such devices include liquid crystal display pixels and organic light emitting diodes (OLEDs),[1, 2] solar cell applications,[3, 4] and electrically heated windows.[5, 6] The materials fulfilling these requirements are usually wide band gap inorganic transparent conductive oxides (TCOs). Tin-doped indium oxide, or ITO, has traditionally been used for electronic TCO applications because of its low resistivity, high work function and transparency. Due to the increasing cost and limited supply of indium and its tendency to migrate in to the device, there has been increasing research interest to substitute ITO with an indium-free material. A number of alternative metal oxides and doped oxides have been evaluated as TCO materials with varying degrees of success.[7, 8] Among these alternatives to ITO, gallium-doped zinc oxide (GZO) [2, 9] and aluminium-doped zinc oxide (AZO) [10, 11] have drawn particular attention. These materials have been demonstrated to have resistivities and transparencies approaching those of the best ITO, low toxicity, and much lower materials cost. Although AZO is attractive as a TCO electrode material, GZO features a greater resistance to oxidation as a result of gallium’s greater electronegativity compared to Submitted to 2 aluminum.[12, 13

  6. Defect-Reduction Mechanism for Improving Radiative Efficiency in InGaN/GaN Light-Emitting Diodes using InGaN Underlayers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Armstrong, Andrew M.; Bryant, Benjamin N.; Crawford, Mary H.; Koleske, Daniel D.; Lee, Stephen R.; Wierer, Jr., Jonathan J.

    2015-04-01

    The influence of a dilute InxGa1-xN (x~0.03) underlayer (UL) grown below a single In0.16Ga0.84N quantum well (SQW), within a light-emitting diode(LED), on the radiative efficiency and deep level defect properties was studied using differential carrier lifetime (DCL) measurements and deep level optical spectroscopy (DLOS). DCL measurements found that inclusion of the UL significantly improved LED radiative efficiency. At low current densities, the non-radiative recombination rate of the LED with an UL was found to be 3.9 times lower than theLED without an UL, while the radiative recombination rates were nearly identical. This, then, suggests that the improved radiative efficiency resultedmore » from reduced non-radiative defect concentration within the SQW. DLOS measurement found the same type of defects in the InGaN SQWs with and without ULs. However, lighted capacitance-voltage measurements of the LEDs revealed a 3.4 times reduction in a SQW-related near-mid-gap defect state for the LED with an UL. Furthermore, quantitative agreement in the reduction of both the non-radiative recombination rate (3.9×) and deep level density (3.4×) upon insertion of an UL corroborates deep level defect reduction as the mechanism for improved LED efficiency.« less

  7. Luminescent properties of Eu{sup 2+}-doped BaGdF{sub 5} glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

    SciTech Connect (OSTI)

    Zhang, Weihuan; Zhang, Yuepin Ouyang, Shaoye; Zhang, Zhixiong; Wang, Qian; Xia, Haiping

    2015-01-14

    Eu{sup 2+} doped transparent oxyfluoride glass ceramics containing BaGdF{sub 5} nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd{sup 3+} ions at 312?nm excited with 275?nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu{sup 2+} doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions, the energy transfer efficiency from Gd{sup 3+} to Eu{sup 2+} ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu{sup 2+} doped BaGdF{sub 5} glass ceramics may be used as a potential blue-emitting phosphor for UV-LED.

  8. Nanoscale determinant to brighten up GaN:Eu red light-emitting diode: Local potential of Eu-defect complexes

    SciTech Connect (OSTI)

    Ishii, Masashi; Koizumi, Atsushi; Fujiwara, Yasufumi

    2015-04-21

    Emission sites in GaN:Eu red light-emitting diodes (LEDs) were investigated using a new spectroscopy technique, namely, site-selective pulse-driven emission spectroscopy (PDES). The PDES, in which the emission intensity of a pulse-driven LED is recorded with respect to the pulse frequency, revealed the charge-trapping dynamics of the Eu emission sites. We found that a determinant of the emission intensity of the sites was not their relative abundance, but rather the spatial extent of the local potential, which determines the effectiveness of the capture of injection charges. Minor sites with wider potentials enhanced the emission intensity of the LED, resulting in emission spectra that differ from those obtained using the photoluminescence of a GaN:Eu thin film. The potential curve is determined by the atomic structure of the complexes, which consist of a Eu dopant and nearby defects in the GaN host. The extent was characterized by a parameter, namely, cutoff frequency, and the emission sites with the wider and narrower potentials in the GaN:Eu LED were found to have cutoff frequencies of 400 kHz and 3 MHz, respectively. The cutoff frequency of 3 MHz was found to be the upper limit for emission sites in the LED. The emission site with the wider potential is useful for slower devices such as light fixtures, while the site with the narrower potential is useful for faster devices such as opto-isolators.

  9. Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes

    SciTech Connect (OSTI)

    Ishii, Masashi; Koizumi, Atsushi; Fujiwara, Yasufumi

    2015-08-24

    A pulse-driven emission-spectroscopy mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode, and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emission spectral data yields a three-dimensional mapping that allows the origin of emission lines to be identified by visual inspection. The identification was achieved even for a weak {sup 5}D{sub 0} → {sup 7}F{sub 3} transition in conventional photoluminescence measurements. A peculiar split is observed in the {sup 5}D{sub 0} → {sup 7}F{sub 3} transition for the bright emission center referred to as OMVPE 8. Despite the unique transition at this emission center, the emission efficiencies for the {sup 5}D{sub 0} → {sup 7}F{sub 3} and {sup 5}D{sub 0} → {sup 7}F{sub 2} transitions were identical. This finding indicates that the excitation of the emission centers, rather than the radiative transitions, is the limiting process that determines the GaN:Eu red LED brightness.

  10. ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Wenyan; Zhang, Yu; Ruan, Cheng; Wang, Dan; Zhang, Tieqiang; Feng, Yi; Gao, Wenzhu; Yin, Jingzhi; Wang, Yiding; Riley, Alexis P.; et al

    2015-01-01

    The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0 lm/W for red, 47.1 lm/W for yellow, and 62.4 lm/W for green LEDs at 2.6 V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to themore » low emission temperature coefficients of 0.022, 0.050, and 0.068 nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs.« less

  11. Enhanced optical power of GaN-based light-emitting diode with compound photonic crystals by multiple-exposure nanosphere-lens lithography

    SciTech Connect (OSTI)

    Zhang, Yonghui; Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Xiong, Zhuo; Shang, Liang; Tian, Yingdong; Zhao, Yun; Zhou, Pengyu; Wang, Junxi; Li, Jinmin [Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2014-07-07

    The light-emitting diodes (LEDs) with single, twin, triple, and quadruple photonic crystals (PCs) on p-GaN are fabricated by multiple-exposure nanosphere-lens lithography (MENLL) process utilizing the focusing behavior of polystyrene spheres. Such a technique is easy and economical for use in fabricating compound nano-patterns. The optimized tilted angle is decided to be 26.6 through mathematic calculation to try to avoid the overlay of patterns. The results of scanning electron microscopy and simulations reveal that the pattern produced by MENLL is a combination of multiple ovals. Compared to planar-LED, the light output power of LEDs with single, twin, triple, and quadruple PCs is increased by 14.78%, 36.03%, 53.68%, and 44.85% under a drive current 350?mA, respectively. Furthermore, all PC-structures result in no degradation of the electrical properties. The stimulated results indicate that the highest light extraction efficiency of LED with the clover-shape triple PC is due to the largest scattering effect on propagation of light from GaN into air.

  12. Comparison of the properties of AlGaInN light-emitting diode chips of vertical and flip-chip design using silicon as the a submount

    SciTech Connect (OSTI)

    Markov, L. K., E-mail: l.markov@mail.ioffe.ru; Smirnova, I. P.; Pavlyuchenko, A. S. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kukushkin, M. V.; Vasil'eva, E. D. [ZAO Innovation 'Tetis' (Russian Federation); Chernyakov, A. E. [Russian Academy of Sciences, Science-and-Technology Microelectronics Center (Russian Federation); Usikov, A. S. [De Core Nanosemiconductors Ltd. (India)

    2013-03-15

    Vertical and flip-chip light-emitting diode (LED) chips are compared from the viewpoint of the behavior of current spreading in the active region and the distribution of local temperatures and thermal resistances of chips. AlGaInN LED chips of vertical design are fabricated using Si as a submount and LED flipchips were fabricated with the removal of a sapphire substrate. The latter are also mounted on a Si submount. The active regions of both chips are identical and are about 1 mm{sup 2} in size. It is shown that both the emittance of the crystal surface in the visible range and the distribution of local temperatures estimated from radiation in the infrared region are more uniform in crystals of vertical design. Heat removal from flip-chips is insufficient in regions of the n contact, which do not possess good thermal contact with the submount. As a result, the total thermal resistances between the p-n junction and the submount both for the vertical chips and for flip-chips are approximately 1 K/W. The total area of the flip-chips exceeds that of the vertical design chips by a factor of 1.4.

  13. High color rendering index white light emitting diodes fabricated from a combination of carbon dots and zinc copper indium sulfide quantum dots

    SciTech Connect (OSTI)

    Sun, Chun; Liu, Wenyan; Zhang, Xiaoyu; Zhang, Yu E-mail: wyu6000@gmail.com; Wang, Yu; Kalytchuk, Sergii; Kershaw, Stephen V.; Rogach, Andrey L.; Zhang, Tieqiang; Zhao, Jun; Yu, William W. E-mail: wyu6000@gmail.com

    2014-06-30

    In a line with most recent trends in developing non-toxic fluorescent nanomaterials, we combined blue emissive carbon dots with green and red emissive zinc copper indium sulfide (ZCIS) core/shell quantum dots (QDs) to achieve white light-emitting diodes (WLEDs) with a high color rendering index of 93. This indicates that ZCIS QDs, with their broad emission bands, can be employed to effectively make up the emission of carbon dots in the yellow and red regions to produce WLEDs in the wide region of color temperature by tuning the volume ratio of these constituting luminophores. Their electroluminescence characteristics including color rendering index, Commission Internationale de l'Eclairage (CIE) color coordinates, and color temperatures were evaluated as a function of forward current. The CIE-1931 chromaticity coordinates of the as-prepared WLEDs, exhibiting good stability, were slightly shifted from (0.321, 0.312) at 10?mA to (0.351, 0.322) at 30?mA, which was mainly caused by the different thermal quenching coefficients of carbon dots and ZCIS QDs.

  14. InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing the Auger recombination

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Liu, Wei; Ju, Zhengang; Tan, Swee Tiam; Ji, Yun; Kyaw, Zabu; Zhang, Xueliang; Wang, Liancheng; Sun, Xiao Wei E-mail: VOLKAN@stanfordalumni.org; Demir, Hilmi Volkan E-mail: VOLKAN@stanfordalumni.org

    2014-07-21

    In conventional InGaN/GaN light-emitting diodes (LEDs), thin InGaN quantum wells are usually adopted to mitigate the quantum confined Stark effect (QCSE), caused due to strong polarization induced electric field, through spatially confining electrons and holes in small recombination volumes. However, this inevitably increases the carrier density in quantum wells, which in turn aggravates the Auger recombination, since the Auger recombination scales with the third power of the carrier density. As a result, the efficiency droop of the Auger recombination severely limits the LED performance. Here, we proposed and showed wide InGaN quantum wells with the InN composition linearly grading along the growth orientation in LED structures suppressing the Auger recombination and the QCSE simultaneously. Theoretically, the physical mechanisms behind the Auger recombination suppression are also revealed. The proposed LED structure has experimentally demonstrated significant improvement in optical output power and efficiency droop, proving to be an effective solution to this important problem of Auger recombination.

  15. Nanospherical-lens lithographical Ag nanodisk arrays embedded in p-GaN for localized surface plasmon-enhanced blue light emitting diodes

    SciTech Connect (OSTI)

    Wei, Tongbo Wu, Kui; Sun, Bo; Zhang, Yonghui; Chen, Yu; Huo, Ziqiang; Hu, Qiang; Wang, Junxi; Zeng, Yiping; Li, Jinmin; Lan, Ding

    2014-06-15

    Large-scale Ag nanodisks (NDs) arrays fabricated using nanospherical-lens lithography (NLL) are embedded in p-GaN layer of an InGaN/GaN light-emitting diode (LED) for generating localized surface plasmon (LSP) coupling with the radiating dipoles in the quantum-well (QWs). Based on the Ag NDs with the controlled surface coverage, LSP leads to the improved crystalline quality of regrowth p-GaN, increased photoluminescence (PL) intensity, reduced PL decay time, and enhanced output power of LED. Compared with the LED without Ag NDs, the optical output power at a current of 350 mA of the LSP-enhanced LEDs with Ag NDs having a distance of 20 and 35 nm to QWs is increased by 26.7% and 31.1%, respectively. The electrical characteristics and optical properties of LEDs with embedded Ag NPs are dependent on the distance of between Ag NPs and QWs region. The LED with Ag NDs array structure is also found to exhibit reduced emission divergence, compared to that without Ag NDs.

  16. Mechanisms of lighting enhancement of Al nanoclusters-embedded Al-doped ZnO film in GaN-based light-emitting diodes

    SciTech Connect (OSTI)

    Lee, Hsin-Ying; Chou, Ying-Hung; Lee, Ching-Ting

    2010-01-15

    Aluminum (Al)-doped ZnO (AZO) films with embedded Al nanoclusters were proposed and utilized to enhance the light output power and maximum operation current of GaN-based light-emitting diodes (LEDs). The AZO films were sputtered using ZnO and Al targets in a magnetron cosputtering system. With Al dc power of 7 W and ZnO 100 W ac power, the electron concentration of 4.1x10{sup 20} cm{sup -3}, electron mobility of 16.2 cm{sup 2}/V s, and resistivity of 7.2x10{sup -4} {Omega} cm were obtained for the deposited AZO film annealed at 600 deg. C for 1 min in a N{sub 2} ambient. As verified by a high resolution transmission electron microscopy, the deposited AZO films with embedded Al nanoclusters were clearly observed. A 35% increase in light output power of the GaN-based LEDs with Al nanoclusters-embedded AZO films was realized compared with the conventional LEDs operated at 500 mA. It was verified experimentally that the various characteristics of GaN-based LEDs including the antireflection, light scattering, current spreading, and the light extraction efficiency in light emission could be significantly enhanced with the use of Al nanoclusters-embedded AZO films.

  17. Metal-interconnection-free integration of InGaN/GaN light emitting diodes with AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Liu, Chao; Cai, Yuefei; Liu, Zhaojun; Ma, Jun; Lau, Kei May

    2015-05-04

    We report a metal-interconnection-free integration scheme for InGaN/GaN light emitting diodes (LEDs) and AlGaN/GaN high electron mobility transistors (HEMTs) by combining selective epi removal (SER) and selective epitaxial growth (SEG) techniques. SER of HEMT epi was carried out first to expose the bottom unintentionally doped GaN buffer and the sidewall GaN channel. A LED structure was regrown in the SER region with the bottom n-type GaN layer (n-electrode of the LED) connected to the HEMTs laterally, enabling monolithic integration of the HEMTs and LEDs (HEMT-LED) without metal-interconnection. In addition to saving substrate real estate, minimal interface resistance between the regrown n-type GaN and the HEMT channel is a significant improvement over metal-interconnection. Furthermore, excellent off-state leakage characteristics of the driving transistor can also be guaranteed in such an integration scheme.

  18. Demonstration Assessment of Light Emitting Diode (LED) Walkway Lighting at the Federal Aviation Administration William J. Hughes Technical Center, in Atlantic City, New Jersey

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael

    2008-03-18

    This report documents the results of a collaborative project to demonstrate a solid state lighting (SSL) general illumination product in an outdoor area walkway application. In the project, six light-emitting diode (LED) luminaires were installed to replace six existing high pressure sodium (HPS) luminaires mounted on 14-foot poles on a set of exterior walkways and stairs at the Federal Aviation Administration (FAA) William J. Hughes Technical Center in Atlantic City, New Jersey, during December, 2007. The effort was a U.S. Department of Energy (DOE) SSL Technology Gateway Demonstration that involved a collaborative teaming agreement between DOE, FAA and Ruud Lighting (and their wholly owned division, Beta LED). Pre- and post-installation power and illumination measurements were taken and used in calculations of energy savings and related economic payback, while personnel impacted by the new lights were provided questionnaires to gauge their perceptions and feedback. The SSL product demonstrated energy savings of over 25% while maintaining illuminance levels and improving illuminance uniformity. PNNL's economic analysis yielded a variety of potential payback results depending on the assumptions used. In the best case, replacing HPS with the LED luminaire can yield a payback as low as 3 years. The new lamps were quite popular with the affected personnel, who gave the lighting an average score of 4.46 out of 5 for improvement.

  19. Electrical current leakage and open-core threading dislocations in AlGaN-based deep ultraviolet light-emitting diodes

    SciTech Connect (OSTI)

    Moseley, Michael Allerman, Andrew; Crawford, Mary; Wierer, Jonathan J.; Smith, Michael; Biedermann, Laura

    2014-08-07

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al{sub 0.7}Ga{sub 0.3}N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these open-core threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al{sub 0.7}Ga{sub 0.3}N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.

  20. Structurally Integrated Photoluminescence-Based Lactate Sensor Using Organic Light Emitting Devices (OLEDs) as the Light Source

    SciTech Connect (OSTI)

    Chengliang Qian

    2006-08-09

    Multianalyte bio(chemical) sensors are extensively researched for monitoring analytes in complex systems, such as blood serum. As a step towards developing such multianalyte sensors, we studied a novel, structurally integrated, organic light emitting device (OLED)-based sensing platform for detection of lactate. Lactate biosensors have attracted numerous research efforts, due to their wide applications in clinical diagnosis, athletic training and food industry. The OLED-based sensor is based on monitoring the oxidation reaction of lactate, which is catalyzed by the lactate oxidase (LOX) enzyme. The sensing component is based on an oxygen-sensitive dye, Platinum octaethyl porphyrin (PtOEP), whose photoluminescence (PL) lifetime {tau} decreases as the oxygen level increases. The PtOEP dye was embedded in a thin film polystyrene (PS) matrix; the LOX was dissolved in solution or immobilized in a sol-gel matrix. {tau} was measured as a function of the lactate concentration; as the lactate concentration increases, {tau} increases due to increased oxygen consumption. The sensors performance is discussed in terms of the detection sensitivity, dynamic range, and response time. A response time of {approx}32 sec was achieved when the LOX was dissolved in solution and kept in a closed cell. Steps towards development of a multianalyte sensor array using an array of individually addressable OLED pixels were also presented.

  1. High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism

    SciTech Connect (OSTI)

    Shi, Hongying; Deng, Lingling; Chen, Shufen E-mail: wei-huang@njupt.edu.cn; Xu, Ying; Zhao, Xiaofei; Cheng, Fan; Huang, Wei E-mail: wei-huang@njupt.edu.cn; Jiangsu-Singapore Joint Research Center for Organic/Bio- Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816

    2014-04-15

    Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m{sup 2}. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

  2. Measurement of the absorption coefficient for light laterally propagating in light-emitting diode structures with In{sub 0.2}Ga{sub 0.8}N/GaN quantum wells

    SciTech Connect (OSTI)

    Lelikov, Yu. S.; Bochkareva, N. I.; Gorbunov, R. I.; Martynov, I. A.; Rebane, Yu. T.; Tarkin, D. V.; Shreter, Yu. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: YShreter@mail.ioffe.ru

    2008-11-15

    A procedure for measuring the absorption coefficient for light propagating parallel to the surface of a GaN-based light emitting diode chip on a sapphire substrate is suggested. The procedure implies the study of emission from one end face of the chip as the opposite end face is illuminated with a light emitting diode. The absorption coefficient is calculated from the ratio between the intensities of emission emerging from the end faces of the sapphire substrate and the epitaxial layer. From the measurements for chips based on p-GaN/In{sub 0.2}Ga{sub 0.8}N/n-GaN structures, the lateral absorption coefficient is determined at a level of (23 {+-} 3)cm{sup -1} at a wavelength of 465 nm. Possible causes for the discrepancy between the absorption coefficients determined in the study and those reported previously are analyzed.

  3. Light emitting ceramic device

    DOE Patents [OSTI]

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  4. Luminescent properties of Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} and its potential application in white light emitting diodes

    SciTech Connect (OSTI)

    Wang, Zhijun; Li, Panlai; Li, Ting; Zhang, Xing; Li, Qingxuan; Yang, Zhiping; Guo, Qinglin

    2013-06-01

    Graphical abstract: Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} phosphor can be effectively excited by an ultraviolet and near-ultraviolet light, and produce a bright blue emission centered at 436 nm. The CIE chromaticity coordinations (x, y) of Na{sub 2}CaSiO{sub 4}:Eu{sup 2+}(NSCE)/Li{sub 2}SrSiO{sub 4}:Eu{sup 2+}(LSSE) vary with the molar ratio of the two constituents. When NSCE/LSSE is 1:3, the CIE chromaticity coordination is (0.332, 0.346), which is close to that of the natural sunlight (0.33, 0.33). The results indicate that Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} may be a promising blue phosphor for UV chip-based multi-phosphor converted white light emitting diodes. Highlights: ? Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} shows the blue emission with a peak at 436 nm and broad excitation band in the UV/n-UV range. ? White light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor with the Li{sub 2}SrSiO{sub 4}:Eu{sup 2+} yellow phosphor. ? Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} would be a promising blue phosphor candidate for UV chip-based multi-phosphor converted white LEDs. - Abstract: A novel blue phosphor Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} is synthesized by a high temperature solid-state reaction, and its luminescent properties are systematically studied. Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} can be effectively excited by the 354 nm radiation, and create blue emission (436 nm). The emission intensity of Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} is influenced by the Eu{sup 2+} doping content, and the optimal doping content is 1.5%, and the concentration quenching mechanism of Eu{sup 2+} in Na{sub 2}CaSiO{sub 4} can be attributed to the multipolar interaction. The white light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} with the yellow phosphor Li{sub 2}SrSiO{sub 4}:Eu{sup 2+}. The results indicate that Na{sub 2}CaSiO{sub 4}:Eu{sup 2+} may be a potential blue emitting phosphor for UV chip-based multi

  5. Modulating dual-wavelength multiple quantum wells in white light emitting diodes to suppress efficiency droop and improve color rendering index

    SciTech Connect (OSTI)

    Zhao, Yukun; Wang, Shuai; Zheng, Min; Ding, Wen; Yun, Feng; Su, Xilin; Yang, Xiangrong; Liu, Shuo; Guo, Maofeng; Zhang, Ye

    2015-10-14

    In this paper, gallium nitride (GaN) based white light-emitting diodes (WLEDs) with modulated quantities of blue (In{sub 0.15}Ga{sub 0.85}N) quantum wells (QWs) and cyan QWs (In{sub 0.18}Ga{sub 0.82}N) in multiple QW (MQW) structures have been investigated numerically and experimentally. It is demonstrated that the optical performance of LEDs is sensitive to the quantities of cyan QWs in dual-wavelength MQW structures. Compared to the LEDs with respective 0, 4, and 8 cyan QWs (12 QWs in total), the optical performance of the sample with 6 cyan QWs is the best. The deterioration of the optical performance in the sample with less (4 pairs) cyan QWs or more (8 pairs) cyan QWs than 6 cyan QWs may be ascribed to weakened reservoir effect or more defects induced. Compared to conventional blue LEDs (12 blue QWs), the sample with 6 cyan QWs could effectively suppress the efficiency droop (the experimental droop ratio decreases from 50.3% to 39.5% at 80 A/cm{sup 2}) and significantly improve the color rendering index (CRI, increases from 66.4 to 77.0) simultaneously. We attribute the droop suppression to the strengthened reservoir effect and carrier confinement of deeper QWs (higher indium composition) incorporated in the dual-wavelength MQW structures, which lead to the better hole spreading and enhanced radiative recombination. Meanwhile, the remarkable experimental CRI improvement may result from the wider full-width at half-maximum of electroluminescence spectra and higher cyan intensity in WLED chips with dual-wavelength MQW structures.

  6. Injection current dependences of electroluminescence transition energy in InGaN/GaN multiple quantum wells light emitting diodes under pulsed current conditions

    SciTech Connect (OSTI)

    Zhang, Feng; Ikeda, Masao Liu, Jianping; Zhang, Shuming; Zhou, Kun; Yang, Hui; Liu, Zongshun

    2015-07-21

    Injection current dependences of electroluminescence transition energy in blue InGaN/GaN multiple quantum wells light emitting diodes (LEDs) with different quantum barrier thicknesses under pulsed current conditions have been analyzed taking into account the related effects including deformation caused by lattice strain, quantum confined Stark effects due to polarization field partly screened by carriers, band gap renormalization, Stokes-like shift due to compositional fluctuations which are supposed to be random alloy fluctuations in the sub-nanometer scale, band filling effect (Burstein-Moss shift), and quantum levels in finite triangular wells. The bandgap renormalization and band filling effect occurring at high concentrations oppose one another, however, the renormalization effect dominates in the concentration range studied, since the band filling effect arising from the filling in the tail states in the valence band of quantum wells is much smaller than the case in the bulk materials. In order to correlate the carrier densities with current densities, the nonradiative recombination rates were deduced experimentally by curve-fitting to the external quantum efficiencies. The transition energies in LEDs both with 15 nm quantum barriers and 5 nm quantum barriers, calculated using full strengths of theoretical macroscopic polarization given by Barnardini and Fiorentini [Phys. Status Solidi B 216, 391 (1999)] are in excellent accordance with experimental results. The LED with 5 nm barriers has been shown to exhibit a higher transition energy and a smaller blue shift than those of LED with 15 nm barriers, which is mainly caused by the smaller internal polarization field in the quantum wells.

  7. Luminescence properties of ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors for white light emitting diodes

    SciTech Connect (OSTI)

    Liao, Jinsheng Liu, Shaohua; Wen, He-Rui; Nie, Liling; Zhong, Laifu

    2015-10-15

    Highlights: • Eu{sup 3+} ions occupy C{sub 1} point group of the Zr{sup 4+} site in ZrW{sub 2}O{sub 8} crystals. • The optimum doping concentration of Eu{sup 3+} was determined for the red emission. • ZrW{sub 2}O{sub 8}:Eu possess high quantum efficiency and suitable chromaticity coordinates. - Abstract: ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors (ca. 60 nm) with different Eu{sup 3+} doping concentrations were obtained using hydrothermal syntheses. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence excitation and emission spectra as well as decay curve measurements were used for the characterization. Under 466 nm excitation, strong red emission at 616 nm corresponding to {sup 5}D{sub 0}–{sup 7}F{sub 2} transition of Eu{sup 3+} was observed for ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) phosphors. The values of intensity parameter Ω{sub 2} and Ω{sub 4} are 17.82 × 10{sup −20} cm{sup 2} and 1.092 × 10{sup −20} cm{sup 2}, respectively. The high quantum efficiency of 83.5% of the ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) suggests this material could be promising red phosphor for generating white light in phosphor-converted white light-emitting diodes (LED)

  8. Luminescence properties of light-emitting diodes based on GaAs with the up-conversion Y{sub 2}O{sub 2}S:Er,Yb luminophor

    SciTech Connect (OSTI)

    Gruzintsev, A. N. [Russian Academy of Sciences, Institute of Problems of Microelectronics Technology (Russian Federation)], E-mail: gran@ipmt-hpm.ac.ru; Barthou, C.; Benalloul, P. [Institute des NanoSciences (France)

    2008-03-15

    Y{sub 2}O{sub 2}S luminophors doped with Er{sup 3+} and Yb{sup 3+} ions are produced by means of solid-phase synthesis and deposited onto standard AL123A infrared light-emitting diodes. When excited with 940 nm radiation from a light-emitting diode, the structures exhibit intense visible up-conversion luminescence. A maximal brightness of 2340 cd/m{sup 2} of green and red up-conversion luminescence at corresponding wavelengths around 550 and 600 nm is observed for the Y{sub 2}O{sub 2}S compound doped with 2 at % Er{sup 3+} ions and 6 at % Yb{sup 3+} ions. The ratio of the intensity of green (or red) up-conversion luminescence to the intensity of infrared Stokes luminescence increases with increasing applied voltage. The efficiency of visible emission of the light-emitting diode structures is {eta} = 1.2 lm/W at an applied voltage of 1.5 V.

  9. Nanoscale engineering boosts performance of quantum dot light emitting

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    diodes Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission color can be tuned by simply changing their dimensions. October 25, 2013 Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos National Laboratory optical laboratory. Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos

  10. Voltage-induced electroluminescence characteristics of hybrid light-emitting diodes with CdSe/Cd/ZnS core-shell nanoparticles embedded in a conducting polymer on plastic substrates

    SciTech Connect (OSTI)

    Kwak, Kiyeol; Cho, Kyoungah, E-mail: chochem@korea.ac.kr, E-mail: sangsig@korea.ac.kr; Kim, Sangsig, E-mail: chochem@korea.ac.kr, E-mail: sangsig@korea.ac.kr [Department of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)] [Department of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2014-03-10

    We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5?V. We examine and discuss the mechanism of this color tunability.

  11. Ge{sub 1−x−y}Si{sub x}Sn{sub y} light emitting diodes on silicon for mid-infrared photonic applications

    SciTech Connect (OSTI)

    Gallagher, J. D.; Xu, C.; Menéndez, J.; Senaratne, C. L.; Wallace, P. M.; Kouvetakis, J.; Aoki, T.

    2015-10-07

    This paper reports initial the demonstration of prototype Ge{sub 1−x−y}Si{sub x}Sn{sub y} light emitting diodes with distinct direct and indirect edges and high quality I-V characteristics. The devices are fabricated on Si (100) wafers in heterostructure pin geometry [n-Ge/i-Ge{sub 1−x−y}Si{sub x}Sn{sub y}/p-Ge(Sn/Si)] using ultra low-temperature (T < 300 °C) depositions of the highly reactive chemical sources Si{sub 4}H{sub 10}, Ge{sub 4}H{sub 10}, Ge{sub 3}H{sub 8}, and SnD{sub 4}. The Sn content in the i-Ge{sub 1−x−y}Si{sub x}Sn{sub y} layer was varied from ∼3.5% to 11%, while the Si content was kept constant near 3%. The Si/Sn amounts in the p-layer were selected to mitigate the lattice mismatch so that the top interface grows defect-free, thereby reducing the deleterious effects of mismatch-induced dislocations on the optical/electrical properties. The spectral responsivity plots of the devices reveal sharp and well-defined absorption edges that systematically red-shift in the mid-IR from 1750 to 2100 nm with increasing Sn content from 3.5% to 11%. The electroluminescence spectra reveal strong direct-gap emission peaks and weak lower energy shoulders attributed to indirect gaps. Both peaks in a given spectrum red-shift with increasing Sn content and their separation decreases as the material approaches direct gap conditions in analogy with binary Ge{sub 1−y}Sn{sub y} counterparts. These findings-combined with the enhanced thermal stability of Ge{sub 1−x−y}Si{sub x}Sn{sub y} relative to Ge{sub 1−y}Sn{sub y} and the observation that ternary alloy disorder does not adversely affect the emission properties—indicate that Ge{sub 1−x−y}Si{sub x}Sn{sub y} may represent a practical target system for future generations of group-IV light sources on Si.

  12. Organic electrophosphorescence device having interfacial layers

    DOE Patents [OSTI]

    Choulis, Stelios A.; Mathai, Mathew; Choong, Vi-En; So, Franky

    2010-08-10

    Techniques are described for forming an organic light emitting diode device with improved device efficiency. Materials having at least one energy level that is similar to those of a phosphorescent light emitting material in the diode are incorporated into the device to directly inject holes or electrons to the light emitting material.

  13. Demonstration Assessment of Light Emitting Diode (LED) Residential Downlights and Undercabinet Lights in the Lane County Tour of Homes, Eugene, Oregon

    SciTech Connect (OSTI)

    Ton, My K.; Richman, Eric E.; Gilbride, Theresa L.

    2008-11-10

    In August 2008 the Pacific Northwest National Laboratory (PNNL) conducted a light emitting diode (LED) residential lighting demonstration project for the U.S. Department of Energy (DOE), Office of Building Technologies, as part of DOE’s Solid State Lighting (SSL) Technology Demonstration Gateway Program. Two lighting technologies, an LED replacement for downlight lamps (bulbs) and an LED undercabinet lighting fixture, were tested in the demonstration which was conducted in two homes built for the 2008 Tour of Homes in Eugene, Oregon. The homes were built by the Lane County Home Builders Association (HBA), and Future B Homes. The Energy Trust of Oregon (ETO) also participated in the demonstration project. The LED downlight product, the LR6, made by Cree LED Lighting Solutions acts as a screw-in replacement for incandescent and halogen bulbs in recessed can downlights. The second product tested is Phillips/Color Kinetics’ eW® Profile Powercore undercabinet fixture designed to mount under kitchen cabinets to illuminate the countertop and backsplash surfaces. Quantitative and qualitative measurements of light performance and electrical power usage were taken at each site before and after initially installed halogen and incandescent lamps were replaced with the LED products. Energy savings and simple paybacks were also calculated and builders who toured the homes were surveyed for their responses to the LED products. The LED downlight product drew 12 Watts of power, cutting energy use by 82% compared to the 65W incandescent lamp and by 84% compared to the 75W halogen lamp. The LED undercabinet fixture drew 10 watts, cutting energy use by 83% to 90% compared to the halogen product, which was tested at two power settings: a low power 60W setting and a high power 105W setting. The LED downlight consistently provided more light than the halogen and incandescent lamps in horizontal measurements at counter height and floor level. It also outperformed in vertical

  14. Low-voltage polariton electroluminescence from an ultrastrongly coupled organic light-emitting diode

    SciTech Connect (OSTI)

    Gubbin, Christopher R.; Maier, Stefan A.; Kna-Cohen, Stphane

    2014-06-09

    We demonstrate electroluminescence from Frenkel molecular excitons ultrastrongly coupled to photons of a metal-clad microcavity containing a 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl)fluorene emissive layer. Thin layers of molybdenum oxide and 4,7-diphenyl-1,10-phenanthroline are used as hole and electron injection layers, respectively. The fabricated devices exhibit an electroluminescence threshold of 3.1?V, a value that is below the bare exciton energy. This result is found to be independent of detuning and consistent with a two-step process for polariton formation. Moreover, we investigate the quantum efficiency of carrier to polariton to photon conversion and obtain an external quantum efficiency of 0.1% for the fabricated structures, an improvement of 5 orders of magnitude over previous reports.

  15. Highly stable and efficient tandem organic light-emitting devices with intermediate connectors using lithium amide as n-type dopant

    SciTech Connect (OSTI)

    Zhou, Dong-Ying; Zu, Feng-Shuo; Shi, Xiao-Bo; Liao, Liang-Sheng E-mail: lsliao@suda.edu.cn; Zhang, Ying-Jie; Aziz, Hany E-mail: lsliao@suda.edu.cn

    2014-08-25

    In this work, we report thermally decomposable lithium amide (LiNH{sub 2}) feasible to function as an effective n-type dopant for intermediate connectors in tandem organic light-emitting devices (OLEDs). Metallic lithium, which is released from the decomposition process of LiNH{sub 2}, is proved by X-ray photoelectron spectroscopy and responsible for n-type electrical doping of electron transporting materials. We demonstrate that tandem OLEDs using LiNH{sub 2} and Cs{sub 2}CO{sub 3} as n-type dopants, respectively, give a comparable electroluminescence efficiency and, moreover, the device with LiNH{sub 2} has far longer operational lifetime. The results therefore highlight the significance of selecting suitable n-type dopant in intermediate connectors to fabricate high-stability tandem OLEDs.

  16. Comparative study of field-dependent carrier dynamics and emission kinetics of InGaN/GaN light-emitting diodes grown on (112{sup }2) semipolar versus (0001) polar planes

    SciTech Connect (OSTI)

    Ji, Yun; Liu, Wei; Chen, Rui; Tiam Tan, Swee; Zhang, Zi-Hui; Ju, Zhengang; Zhang, Xueliang; Sun, Handong; Wei Sun, Xiao; Erdem, Talha; Zhao, Yuji; DenBaars, Steven P. E-mail: volkan@stanfordalumni.org; Nakamura, Shuji; Volkan Demir, Hilmi E-mail: volkan@stanfordalumni.org

    2014-04-07

    The characteristics of electroluminescence (EL) and photoluminescence (PL) emission from GaN light-emitting diodes (LEDs) grown on (112{sup }2) semipolar plane and (0001) polar plane have been comparatively investigated. Through different bias-dependent shifting trends observed from the PL and time-resolved PL spectra (TRPL) for the two types of LEDs, the carrier dynamics within the multiple quantum wells (MQWs) region is systematically analyzed and the distinct field-dependent emission kinetics are revealed. Moreover, the polarization induced internal electric field has been deduced for each of the LEDs. The relatively stable emission behavior observed in the semipolar LED is attributed to the smaller polarization induced internal electric field. The study provides meaningful insight for the design of quantum well (QW) structures with high radiative recombination rates.

  17. KOH based selective wet chemical etching of AlN, AlxGa1-xN, and GaN crystals: A way towards substrate removal in deep ultraviolet-light emitting diode

    SciTech Connect (OSTI)

    Guo, W; Kirste, R; Bryan, I; Bryan, Z; Hussey, L; Reddy, P; Tweedie, J; Collazo, R; Sitar, Z

    2015-02-23

    A controllable and smooth potassium hydroxide-based wet etching technique was developed for the AlGaN system. High selectivity between AlN and AlxGa1-xN (up to 12 x) was found to be critical in achieving effective substrate thinning or removal for AlGaN-based deep ultraviolet light emitting diodes, thus increasing light extraction efficiency. The mechanism of high selectivity of AlGaN as a function of Al composition can be explained as related to the formation and dissolution of oxide/hydroxide on top of N-polar surface. Cross-sectional transmission electron microscopic analysis served as ultimate proof that these hillocks were not related to underlying threading dislocations. (C) 2015 AIP Publishing LLC.

  18. Direct transparent electrode patterning on layered GaN substrate by screen printing of indium tin oxide nanoparticle ink for Eu-doped GaN red light-emitting diode

    SciTech Connect (OSTI)

    Kashiwagi, Y. Yamamoto, M.; Saitoh, M.; Takahashi, M.; Ohno, T.; Nakamoto, M.; Koizumi, A.; Fujiwara, Y.; Takemura, Y.; Murahashi, K.; Ohtsuka, K.; Furuta, S.

    2014-12-01

    Transparent electrodes were formed on Eu-doped GaN-based red-light-emitting diode (GaN:Eu LED) substrates by the screen printing of indium tin oxide nanoparticle (ITO np) inks as a wet process. The ITO nps with a mean diameter of 25?nm were synthesized by the controlled thermolysis of a mixture of indium complexes and tin complexes. After the direct screen printing of ITO np inks on GaN:Eu LED substrates and sintering at 850?C for 10?min under atmospheric conditions, the resistivity of the ITO film was 5.2?m??cm. The fabricated LED up to 3?mm square surface emitted red light when the on-voltage was exceeded.

  19. Effects of Mg-doped AlN/AlGaN superlattices on properties of p-GaN contact layer and performance of deep ultraviolet light emitting diodes

    SciTech Connect (OSTI)

    Al tahtamouni, T. M.; Lin, J. Y.; Jiang, H. X.

    2014-04-15

    Mg-doped AlN/AlGaN superlattice (Mg-SL) and Mg-doped AlGaN epilayers have been investigated in the 284 nm deep ultraviolet (DUV) light emitting diodes (LEDs) as electron blocking layers. It was found that the use of Mg-SL improved the material quality of the p-GaN contact layer, as evidenced in the decreased density of surface pits and improved surface morphology and crystalline quality. The performance of the DUV LEDs fabricated using Mg-SL was significantly improved, as manifested by enhanced light intensity and output power, and reduced turn-on voltage. The improved performance is attributed to the enhanced blocking of electron overflow, and enhanced hole injection.

  20. GaInN light-emitting diodes using separate epitaxial growth for the p-type region to attain polarization-inverted electron-blocking layer, reduced electron leakage, and improved hole injection

    SciTech Connect (OSTI)

    Meyaard, David S., E-mail: meyaad@rpi.edu; Lin, Guan-Bo; Ma, Ming; Fred Schubert, E. [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)] [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Cho, Jaehee [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Semiconductor Physics Research Center, School of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Han, Sang-Heon; Kim, Min-Ho; Shim, HyunWook; Sun Kim, Young [LED Business, Samsung Electronics, Yongin 446-920 (Korea, Republic of)] [LED Business, Samsung Electronics, Yongin 446-920 (Korea, Republic of)

    2013-11-11

    A GaInN light-emitting diode (LED) structure is analyzed that employs a separate epitaxial growth for the p-type region, i.e., the AlGaN electron-blocking layer (EBL) and p-type GaN cladding layer, followed by wafer or chip bonding. Such LED structure has a polarization-inverted EBL and allows for uncompromised epitaxial-growth optimization of the p-type region, i.e., without the need to consider degradation of the quantum-well active region during p-type region growth. Simulations show that such an LED structure reduces electron leakage, reduces the efficiency droop, improves hole injection, and has the potential to extend high efficiencies into the green spectral region.

  1. Green route synthesis of high quality CdSe quantum dots for applications in light emitting devices

    SciTech Connect (OSTI)

    Bera, Susnata, E-mail: susnata.bera@gmail.com [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Singh, Shashi B. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Ray, S.K., E-mail: physkr@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2012-05-15

    Investigation was made on light emitting diodes fabricated using CdSe quantum dots. CdSe quantum dots were synthesized chemically using olive oil as the capping agent, instead of toxic phosphine. Room temperature photoluminescence investigation showed sharp 1st excitonic emission peak at 568 nm. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting devices were fabricated by solution process. The electroluminescence study showed low turn on voltage ({approx}2.2 V) .The EL peak intensity was found to increase by increasing the operating current. - Graphical abstract: Light emitting diode was fabricated using CdSe quantum dots using olive oil as the capping agent, instead of toxic phosphine. Bi-layer organic/inorganic (P3HT/CdSe) hybrid light emitting device shows strong electroluminescence in the range 630-661 nm. Highlights: Black-Right-Pointing-Pointer CdSe Quantum dots were synthesized using olive oil as the capping agent. Black-Right-Pointing-Pointer Light emitting device was fabricated using CdSe QDs/P3HT polymer heterojunction. Black-Right-Pointing-Pointer The I-V characteristics study showed low turn on voltage at {approx}2.2 V. Black-Right-Pointing-Pointer The EL peak intensity increases with increasing the operating current.

  2. Study on copper phthalocyanine and perylene-based ambipolar organic light-emitting field-effect transistors produced using neutral beam deposition method

    SciTech Connect (OSTI)

    Kim, Dae-Kyu; Oh, Jeong-Do; Shin, Eun-Sol; Seo, Hoon-Seok; Choi, Jong-Ho

    2014-04-28

    The neutral cluster beam deposition (NCBD) method has been applied to the production and characterization of ambipolar, heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, multi-digitated, long-channel geometry. Organic thin films of n-type N,N?-ditridecylperylene-3,4,9,10-tetracarboxylic diimide and p-type copper phthalocyanine were successively deposited on the hydroxyl-free polymethyl-methacrylate (PMMA)-coated SiO{sub 2} dielectrics using the NCBD method. Characterization of the morphological and structural properties of the organic active layers was performed using atomic force microscopy and X-ray diffraction. Various device parameters such as hole- and electron-carrier mobilities, threshold voltages, and electroluminescence (EL) were derived from the fits of the observed current-voltage and current-voltage-light emission characteristics of OLEFETs. The OLEFETs demonstrated good field-effect characteristics, well-balanced ambipolarity, and substantial EL under ambient conditions. The device performance, which is strongly correlated with the surface morphology and the structural properties of the organic active layers, is discussed along with the operating conduction mechanism.

  3. Close-packed array of light emitting devices

    DOE Patents [OSTI]

    Ivanov, Ilia N.; Simpson, John T.

    2013-04-09

    A close-packed array of light emitting diodes includes a nonconductive substrate having a plurality of elongate channels extending therethrough from a first side to a second side, where each of the elongate channels in at least a portion of the substrate includes a conductive rod therein. The conductive rods have a density over the substrate of at least about 1,000 rods per square centimeter and include first conductive rods and second conductive rods. The close-packed array further includes a plurality of light emitting diodes on the first side of the substrate, where each light emitting diode is in physical contact with at least one first conductive rod and in electrical contact with at least one second conductive rod.

  4. Efficient semiconductor light-emitting device and method

    DOE Patents [OSTI]

    Choquette, Kent D.; Lear, Kevin L.; Schneider, Jr., Richard P.

    1996-01-01

    A semiconductor light-emitting device and method. The semiconductor light-emitting device is provided with at least one control layer or control region which includes an annular oxidized portion thereof to channel an injection current into the active region, and to provide a lateral refractive index profile for index guiding the light generated within the device. A periodic composition grading of at least one of the mirror stacks in the device provides a reduced operating voltage of the device. The semiconductor light-emitting device has a high efficiency for light generation, and may be formed either as a resonant-cavity light-emitting diode (RCLED) or as a vertical-cavity surface-emitting laser (VCSEL).

  5. Efficient semiconductor light-emitting device and method

    DOE Patents [OSTI]

    Choquette, K.D.; Lear, K.L.; Schneider, R.P. Jr.

    1996-02-20

    A semiconductor light-emitting device and method are disclosed. The semiconductor light-emitting device is provided with at least one control layer or control region which includes an annular oxidized portion thereof to channel an injection current into the active region, and to provide a lateral refractive index profile for index guiding the light generated within the device. A periodic composition grading of at least one of the mirror stacks in the device provides a reduced operating voltage of the device. The semiconductor light-emitting device has a high efficiency for light generation, and may be formed either as a resonant-cavity light-emitting diode (RCLED) or as a vertical-cavity surface-emitting laser (VCSEL). 12 figs.

  6. Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2014-08-04

    Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templatesmore » are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.« less

  7. Liquid-phase exfoliation of chemical vapor deposition-grown single layer graphene and its application in solution-processed transparent electrodes for flexible organic light-emitting devices

    SciTech Connect (OSTI)

    Wu, Chaoxing; Li, Fushan E-mail: gtl-fzu@hotmail.com; Wu, Wei; Chen, Wei; Guo, Tailiang E-mail: gtl-fzu@hotmail.com

    2014-12-15

    Efficient and low-cost methods for obtaining high performance flexible transparent electrodes based on chemical vapor deposition (CVD)-grown graphene are highly desirable. In this work, the graphene grown on copper foil was exfoliated into micron-size sheets through controllable ultrasonication. We developed a clean technique by blending the exfoliated single layer graphene sheets with conducting polymer to form graphene-based composite solution, which can be spin-coated on flexible substrate, forming flexible transparent conducting film with high conductivity (?8 ?/?), high transmittance (?81% at 550?nm), and excellent mechanical robustness. In addition, CVD-grown-graphene-based polymer light emitting diodes with excellent bendable performances were demonstrated.

  8. A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} for near UV white light-emitting diodes

    SciTech Connect (OSTI)

    Yang, Zhigang; Zhao, Zhengyan; Shi, Yurong; Wang, Yuhua

    2013-10-15

    Graphical abstract: - Highlights: Novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was prepared by solid-state reaction. Excitation spectra suggested an obvious absorption in near-ultraviolet region. Under 392 nm excitation, the phosphors exhibited a red emission at 614 nm. Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white LEDs. - Abstract: A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was synthesized using a solid-state reaction method, and its luminescence characteristics and charge compensators effect (Li{sup +}, Na{sup +}, K{sup +}) were investigated. The excitation spectra showed a obvious absorption in near-ultraviolet region. Under 392 nm excitation, the phosphors exhibited an intense red emission at 614 nm. The Commission Internationale de lEclairage (CIE) chromaticity coordinates and quantum efficiency (QE) were (0.65, 0.35) and 62.3%, respectively. The good color saturation, high quantum efficiency and small thermal-quenching properties indicate that Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white light-emitting diodes.

  9. Porous light-emitting compositions

    DOE Patents [OSTI]

    Burrell, Anthony K.; McCleskey, Thomas Mark; Jia, Quanxi; Bauer, Eve; Mueller, Alexander H.

    2012-04-17

    Light-emitting devices are prepared by coating a porous substrate using a polymer-assisted deposition process. Solutions of metal precursor and soluble polymers having binding properties for metal precursor were coated onto porous substrates. The coated substrates were heated at high temperatures under a suitable atmosphere. The result was a substrate with a conformal coating that did not substantially block the pores of the substrate.

  10. Controlling potential barrier height by changing V-shaped pit size and the effect on optical and electrical properties for InGaN/GaN based light-emitting diodes

    SciTech Connect (OSTI)

    Okada, Narihito Kashihara, Hiroyuki; Sugimoto, Kohei; Yamada, Yoichi; Tadatomo, Kazuyuki

    2015-01-14

    The internal quantum efficiency (IQE) of InGaN/GaN multiple quantum wells (MQWs) with blue light emission was improved by inserting an InGaN/GaN superlattice (SL) beneath the MQWs. While the SL technique is useful for improving the light-emitting diode (LED) performance, its effectiveness from a multilateral point of view requires investigation. V-shaped pits (V-pits), which generate a potential barrier and screen the effect of the threading dislocation, are one of the candidates for increasing the light emission efficiency of LEDs exceptionally. In this research, we investigated the relationship between the V-pit and SL and revealed that the V-pit diameter is strongly correlated with the IQE by changing the number of SL periods. Using scanning near-field optical microscopy and photoluminescence measurements, we demonstrated the distinct presence of the potential barrier formed by the V-pits around the dislocations. The relationship between the V-pit and the number of SL periods resulted in changing the potential barrier height, which is related to the V-pit diameter determined by the number of SL periods. In addition, we made an attempt to insert pit expansion layers (PELs) composed of combination of SL and middle temperature grown GaN layer instead of only SL structure. As a result of the evaluation of LEDs using SL or PEL, the EL intensity was strongly related to pit diameter regardless of the structures to form the V-pits. In addition, it was clear that larger V-pits reduce the efficiency droop, which is considered to be suppression of the carrier loss at high injection current.

  11. The site occupation and valence of Mn ions in the crystal lattice of Sr{sub 4}Al{sub 14}O{sub 25} and its deep red emission for high color-rendering white light-emitting diodes

    SciTech Connect (OSTI)

    Chen, Lei; Xue, Shaochan; Chen, Xiuling; Bahader, Ali; Deng, Xiaorong; Zhao, Erlong; Jiang, Yang; Chen, Shifu; Chan, Ting-Shan; Zhao, Zhi; Zhang, Wenhua

    2014-12-15

    Highlights: • Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were identified using XANES and EPR. • Red luminescence was attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. • The Mn{sup 3+} incorporated in the center of AlO{sub 4} tetrahedron was non-luminescent. • The bond-valence theory was used to analyze the effective valences of cations. • A white LED device with CRI up to Ra 93.23 was packaged by using the red phosphor. - Abstract: The synthesis and component of red phosphor, Sr{sub 4}Al{sub 14}O{sub 25}: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr{sup 2+} and Al{sup 3+} in Sr{sub 4}Al{sub 14}O{sub 25}. As a result, the strong covalence of Al{sup 3+} in the AlO{sub 4} tetrahedron other than in the AlO{sub 6} octahedron is disclosed. The deep red emission is attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The mechanism of energy transfer is mainly through dipole–dipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.

  12. Optical manifold for light-emitting diodes

    DOE Patents [OSTI]

    Chaves, Julio C.; Falicoff, Waqidi; Minano, Juan C.; Benitez, Pablo; Parkyn, Jr., William A.; Alvarez, Roberto; Dross, Oliver

    2008-06-03

    An optical manifold for efficiently combining a plurality of blue LED outputs to illuminate a phosphor for a single, substantially homogeneous output, in a small, cost-effective package. Embodiments are disclosed that use a single or multiple LEDs and a remote phosphor, and an intermediate wavelength-selective filter arranged so that backscattered photoluminescence is recycled to boost the luminance and flux of the output aperture. A further aperture mask is used to boost phosphor luminance with only modest loss of luminosity. Alternative non-recycling embodiments provide blue and yellow light in collimated beams, either separately or combined into white.

  13. Megahertz organic/polymer diodes

    SciTech Connect (OSTI)

    Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

    2012-12-11

    Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

  14. Recipient luminophoric mediums having narrow spectrum luminescent materials and related semiconductor light emitting devices and methods

    DOE Patents [OSTI]

    LeToquin, Ronan P; Tong, Tao; Glass, Robert C

    2014-12-30

    Light emitting devices include a light emitting diode ("LED") and a recipient luminophoric medium that is configured to down-convert at least some of the light emitted by the LED. In some embodiments, the recipient luminophoric medium includes a first broad-spectrum luminescent material and a narrow-spectrum luminescent material. The broad-spectrum luminescent material may down-convert radiation emitted by the LED to radiation having a peak wavelength in the red color range. The narrow-spectrum luminescent material may also down-convert radiation emitted by the LED into the cyan, green or red color range.

  15. Bright three-band white light generated from CdSe/ZnSe quantum dot-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode with high color rendering index

    SciTech Connect (OSTI)

    Jang, Ho Seong; Kwon, Byoung-Hwa; Jeon, Duk Young; Yang, Heesun

    2009-10-19

    In this study, bright three-band white light was generated from the CdSe/ZnSe quantum dot (QD)-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode (WLED). The CdSe/ZnSe core/shell structure was confirmed by energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The CdSe/ZnSe QDs showed high quantum efficiency (79%) and contributed to the high luminous efficiency ({eta}{sub L}) of the fabricated WLED. The WLED showed bright natural white with excellent color rendering property ({eta}{sub L}=26.8 lm/W, color temperature=6140 K, and color rendering index=85) and high stability against the increase in forward bias currents from 20 to 70 mA.

  16. The dynamic behavior of thin-film ionic transition metal complex-based light-emitting electrochemical cells

    SciTech Connect (OSTI)

    Meier, Sebastian B. E-mail: wiebke.sarfert@siemens.com; Hartmann, David; Sarfert, Wiebke E-mail: wiebke.sarfert@siemens.com; Winnacker, Albrecht

    2014-09-14

    Light-emitting electrochemical cells (LECs) have received increasing attention during recent years due to their simple architecture, based on solely air-stabile materials, and ease of manufacture in ambient atmosphere, using solution-based technologies. The LEC's active layer offers semiconducting, luminescent as well as ionic functionality resulting in device physical processes fundamentally different as compared with organic light-emitting diodes. During operation, electrical double layers (EDLs) form at the electrode interfaces as a consequence of ion accumulation and electrochemical doping sets in leading to the in situ development of a light-emitting p-i-n junction. In this paper, we comment on the use of impedance spectroscopy in combination with complex nonlinear squares fitting to derive key information about the latter events in thin-film ionic transition metal complex-based light-emitting electrochemical cells based on the model compound bis-2-phenylpyridine 6-phenyl-2,2´-bipyridine iridium(III) hexafluoridophosphate ([Ir(ppy)₂(pbpy)][PF₆]). At operating voltages below the bandgap potential of the ionic complex used, we obtain the dielectric constant of the active layer, the conductivity of mobile ions, the transference numbers of electrons and ions, and the thickness of the EDLs, whereas the transient thickness of the p-i-n junction is determined at voltages above the bandgap potential. Most importantly, we find that charge transport is dominated by the ions when carrier injection from the electrodes is prohibited, that ion movement is limited by the presence of transverse internal interfaces and that the width of the intrinsic region constitutes almost 60% of the total active layer thickness in steady state at a low operating voltage.

  17. Materials and architectures for efficient harvesting of singlet and triplet excitons for white light emitting OLEDs

    DOE Patents [OSTI]

    Thompson, Mark E; Forrest, Stephen

    2015-02-03

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

  18. Organic light emitting device with conducting cover

    DOE Patents [OSTI]

    Silvernail, Jeffrey; Paynter, Jason; Rajan, Kamala

    2014-07-01

    The claimed invention was made by, on behalf of, and/or in connection with one or more of the following parties to a joint university corporation research agreement: Princeton University, The University of Southern California, The University of Michigan and Universal Display Corporation. The agreement was in effect on and before the date the claimed invention was made, and the claimed invention was made as a result of activities undertaken within the scope of the agreement.

  19. Oxycarbonitride phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Romanelli, Michael D.; Tian, Yongchi

    2015-12-22

    A family of oxycarbonitride phosphor compositions is provided. Also provided are light emitting devices incorporating the oxycarbonitride phosphor compositions.

  20. An all-organic UV on-chip spectrometer created | The Ames Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    at Ames Laboratory have developed a near ultra-violet and all-organic light emitting diode (OLED) that can be used as an on-chip photosensor. It's a first in a rather...

  1. Ames Laboratory scientists create an all-organic UV on-chip spectromet...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of Energy's Ames Laboratory has developed a near ultra-violet and all-organic light emitting diode (OLED) that can be used as an on-chip photosensor. It's a first in a rather...

  2. Organimetallic Fluorescent Complex Polymers For Light Emitting Applications

    DOE Patents [OSTI]

    Shi, Song Q.; So, Franky

    1997-10-28

    A fluorescent complex polymer with fluorescent organometallic complexes connected by organic chain spacers is utilized in the fabrication of light emitting devices on a substantially transparent planar substrate by depositing a first conductive layer having p-type conductivity on the planar surface of the substrate, depositing a layer of a hole transporting and electron blocking material on the first conductive layer, depositing a layer of the fluorescent complex polymer on the layer of hole transporting and electron blocking material as an electron transporting emissive layer and depositing a second conductive layer having n-type conductivity on the layer of fluorescent complex polymer.

  3. Light emitting device having peripheral emissive region

    DOE Patents [OSTI]

    Forrest, Stephen R

    2013-05-28

    Light emitting devices are provided that include one or more OLEDs disposed only on a peripheral region of the substrate. An OLED may be disposed only on a peripheral region of a substantially transparent substrate and configured to emit light into the substrate. Another surface of the substrate may be roughened or include other features to outcouple light from the substrate. The edges of the substrate may be beveled and/or reflective. The area of the OLED(s) may be relatively small compared to the substrate surface area through which light is emitted from the device. One or more OLEDs also or alternatively may be disposed on an edge of the substrate about perpendicular to the surface of the substrate through which light is emitted, such that they emit light into the substrate. A mode expanding region may be included between each such OLED and the substrate.

  4. Photoluminescent and thermal properties of (Sr{sub 0.995?x?y?z}Ca{sub x}Ba{sub y}Mg{sub z}){sub 2}SiO{sub 4}:0.01Eu{sup 2+} phosphors for warm white light-emitting diodes

    SciTech Connect (OSTI)

    Li, Yao; Ci, Zhipeng; Peng, Yingquan; Wang, Yuhua; Liu, Chunjuan

    2015-01-15

    Highlights: The photoluminescent property of Sr{sub 2}SiO{sub 4}:Eu{sup 2+} is improved by doping Ca{sup 2+} and Ba{sup 2+}. The emission spectra red-shift obviously by doping Ca{sup 2+} into Sr{sub 2}SiO{sub 4}:Eu{sup 2+}. The thermal stability is enhanced by doping Ba{sup 2+} into (Sr,Ca){sub 2}SiO{sub 4}:Eu{sup 2+}. The improved phosphors can combine blue-LED chips to generate warm white light. - Abstract: A series of phosphors (Sr{sub 0.995?x?y?z}Ca{sub x}Ba{sub y}Mg{sub z}){sub 2}SiO{sub 4}:0.01Eu{sup 2+} (0 ? x ? 0.45, 0 ? y ? 0.015, 0 ? z ? 0.35) were synthesized by solid state reaction. Their phase compositions and photoluminescent properties were investigated in detail. The X-ray diffraction analysis indicates the impurity phase of SrSiO{sub 3} is formed only when z ? 0.25. A photoluminescence investigation shows, with x increasing the emission spectra of the phosphors (0 ? x ? 0.45, 0 ? y ? 0.015, z = 0) obviously red-shift, the corresponding color tones shift from yellow to orangeyellow and their CCTs reduce from 2875 to 2237 K. All the results are beneficial for the phosphors to combining blue light-emitting diode chips to generate warm white light. Besides, the thermal stability of the phosphor (x = 0.36, y = z = 0) is enhanced by doping Ba{sup 2+}, due to the greater activation energy for the compounds containing barium.

  5. Demonstration Assessment of Light-Emitting Diode (LED) Roadway...

    Office of Scientific and Technical Information (OSTI)

    The LEDs had an average illuminance level of 0.91 foot candles compared to 1.29 fc for the HPS lamps. The LED luminairesmore cost 38,000 more than HPS lamps, yielding a lengthy ...

  6. Demonstration Assessment of Light-Emitting Diode Parking Structure...

    Office of Scientific and Technical Information (OSTI)

    Because of the relatively high cost of the LED luminaires at their time of purchase for this project (2010), the simple payback periods were 6.5 years and 4.9 years for retrofit ...

  7. Demonstration Assessment of Light-Emitting Diode Parking Structure...

    Office of Scientific and Technical Information (OSTI)

    LED luminaires at their time of purchase for this project (2010), the simple payback periods were 6.5 years and 4.9 years for retrofit and new construction scenarios, respectively. ...

  8. DOE Science Showcase - Light-emitting Diode (LED) Lighting Research...

    Office of Scientific and Technical Information (OSTI)

    LED Research Information in DOE Databases SciTech Connect National Library of EnergyBeta Science.gov Ciencia.Science.gov WorldWideScience.org Visit the Science Showcase homepage. ...

  9. Demonstration Assessment of Light-Emitting Diode (LED) Accent...

    Office of Scientific and Technical Information (OSTI)

    Subject: 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; AIR CONDITIONING; CONTROL SYSTEMS; DEMONSTRATION PROGRAMS; DESIGN; EDUCATIONAL FACILITIES; FEEDBACK; HALOGENS; ...

  10. Advanced Epi Tools for Gallium Nitride Light Emitting Diode Devices

    SciTech Connect (OSTI)

    Patibandla, Nag; Agrawal, Vivek

    2012-12-01

    Over the course of this program, Applied Materials, Inc., with generous support from the United States Department of Energy, developed a world-class three chamber III-Nitride epi cluster tool for low-cost, high volume GaN growth for the solid state lighting industry. One of the major achievements of the program was to design, build, and demonstrate the world’s largest wafer capacity HVPE chamber suitable for repeatable high volume III-Nitride template and device manufacturing. Applied Materials’ experience in developing deposition chambers for the silicon chip industry over many decades resulted in many orders of magnitude reductions in the price of transistors. That experience and understanding was used in developing this GaN epi deposition tool. The multi-chamber approach, which continues to be unique in the ability of the each chamber to deposit a section of the full device structure, unlike other cluster tools, allows for extreme flexibility in the manufacturing process. This robust architecture is suitable for not just the LED industry, but GaN power devices as well, both horizontal and vertical designs. The new HVPE technology developed allows GaN to be grown at a rate unheard of with MOCVD, up to 20x the typical MOCVD rates of 3{micro}m per hour, with bulk crystal quality better than the highest-quality commercial GaN films grown by MOCVD at a much cheaper overall cost. This is a unique development as the HVPE process has been known for decades, but never successfully commercially developed for high volume manufacturing. This research shows the potential of the first commercial-grade HVPE chamber, an elusive goal for III-V researchers and those wanting to capitalize on the promise of HVPE. Additionally, in the course of this program, Applied Materials built two MOCVD chambers, in addition to the HVPE chamber, and a robot that moves wafers between them. The MOCVD chambers demonstrated industry-leading wavelength yield for GaN based LED wafers and industry-leading uptime enabled in part by a novel in-situ cleaning process developed in this program.

  11. Adoption of Light-Emitting Diodes in Common Lighting Applications

    SciTech Connect (OSTI)

    Yamada, Mary; Chwastyk, Dan

    2013-05-01

    Report estimating LED energy savings in nine applications where LEDs compete with traditional lighting sources such as incandescent, halogen, high-pressure sodium, and certain types of fluorescent. The analysis includes indoor lamp, indoor luminaire, and outdoor luminaire applications.

  12. Demonstration Assessment of Light-Emitting Diode Parking Structure...

    Office of Scientific and Technical Information (OSTI)

    Parking Structure Lighting at U.S. Department of Labor Headquarters Kinzey, Bruce R.; Myer, Michael solid-state lighting; LEDs; occupancy sensor controls; parking facility lighting...

  13. Demonstration Assessment of Light-Emitting Diode (LED) Parking...

    Office of Scientific and Technical Information (OSTI)

    Criteria include payback, light levels, occupant satisfaction. This report is Phase I of II. Phase I deals with initial installation. Authors: Myer, Michael ; Goettel, Russell T. ...

  14. Demonstration Assessment of Light Emitting Diode (LED) Street...

    Broader source: Energy.gov (indexed) [DOE]

    This report summarizes an LED street lighting assessment project conducted to study the applicability of LED luminaires in a street lighting application. emergingtechreportleds...

  15. Demonstration Assessment of Light-Emitting Diode (LED) Parking...

    Office of Scientific and Technical Information (OSTI)

    Lot Performance Specification developed by the DOE's Commercial Building Energy Alliance. ... This demonstration met the GATEWAY requirements of saving energy, matching or ...

  16. Demonstration Assessment of Light-Emitting Diode Roadway Lighting...

    Office of Scientific and Technical Information (OSTI)

    Authors: Myer, Michael ; Hazra, Oindrila ; Kinzey, Bruce R. Publication Date: 2011-12-01 OSTI Identifier: 1074332 Report Number(s): PNNL-21022 BT0301000 DOE Contract Number: ...

  17. Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fabrication of initial 405 nm semipolar LEDs is based on high-IQE structures identified by the experimental data. View the Presentation 2014 BTO Peer Review Presentation - ...

  18. Solid-State Lighting — Using Light-Emitting Diodes

    SciTech Connect (OSTI)

    2011-12-16

    This section includes general guidelines for buying LED products and addresses how these products perform in specific applications.

  19. Demonstration of Light-Emitting Diode (LED) Retrofit Lamps

    SciTech Connect (OSTI)

    Miller, N.

    2011-09-01

    GATEWAY program report on a demonstration of LED retrofit lamps at the Jordan Schnitzer Museum of art in Eugene, OR

  20. Demonstration Assessment of Light-Emitting Diode (LED) Street...

    Office of Scientific and Technical Information (OSTI)

    product is performing at an efficiency level comparable to its primary competition ... Language: English Subject: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLOR; ...

  1. Promising Technology: Parking Lot Light-Emitting Diodes with Controls

    Broader source: Energy.gov [DOE]

    LEDs offer several advantages over conventional high intensity discharge (HID) luminaires. LEDs have longer life times, reduced maintenance and operating costs, superior color rendition, and lower energy consumption.

  2. Promising Technology: Parabolic Aluminized Reflector Light-Emitting Diodes

    Broader source: Energy.gov [DOE]

    Parabolic aluminized reflectors, or PARs, are directional lamps typically used in recessed lighting. In contrast to CFLs, LEDs offer additional advantages including no warm up time, improved dimming and control capabilities, and for some products much greater efficacy ratings.

  3. Promising Technology: High Bay Light-Emitting Diodes

    Broader source: Energy.gov [DOE]

    High bay LEDs offer several advantages over conventional high intensity discharge (HID) luminaires including longer lifetimes, reduced maintenance costs, and lower energy consumption.

  4. Understanding Drooping Light Emitting Diodes CEEM | U.S. DOE...

    Office of Science (SC) Website

    Understanding "droop" may result in cheaper, more efficient LEDs; LEDs are more energy ... indium in Indium Gallium Nitride (InGaN) green LEDs caused a decrease in light intensity. ...

  5. Light emitting elastomer compositions and method of use

    DOE Patents [OSTI]

    McElhanon, James R.; Zifer, Thomas; Whinnery, LeRoy L.

    2004-11-23

    There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout an elastomeric body and activated by deforming the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

  6. 2014-05-16 Issuance: Test Procedures for Integrated Light-Emitting...

    Broader source: Energy.gov (indexed) [DOE]

    notice of proposed rulemaking regarding test procedures for integrated light-emitting ... to this document. 2014-05-16 Issuance: Test Procedures for Integrated Light-Emitting ...

  7. Light-emitting block copolymers composition, process and use

    DOE Patents [OSTI]

    Ferraris, John P.; Gutierrez, Jose J.

    2006-11-14

    Generally, and in one form, the present invention is a composition of light-emitting block copolymer. In another form, the present invention is a process producing a light-emitting block copolymers that intends polymerizing a first di(halo-methyl) aromatic monomer compound in the presence of an anionic initiator and a base to form a polymer and contacting a second di(halo-methyl) aromatic monomer compound with the polymer to form a homopolymer or block copolymer wherein the block copolymer is a diblock, triblock, or star polymer. In yet another form, the present invention is an electroluminescent device comprising a light-emitting block copolymer, wherein the electroluminescent device is to be used in the manufacturing of optical and electrical devices.

  8. Light emitting ceramic device and method for fabricating the same

    DOE Patents [OSTI]

    Valentine, Paul; Edwards, Doreen D.; Walker Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2004-11-30

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, and alternative methods of fabrication for the same are claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  9. Photon extraction from nitride ultraviolet light-emitting devices

    DOE Patents [OSTI]

    Schowalter, Leo J; Chen, Jianfeng; Grandusky, James R

    2015-02-24

    In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.

  10. Fabrication of Organic-inorganic Perovskites for Highly Efficient Solar

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cells and Light Emitting Diodes | MIT-Harvard Center for Excitonics Fabrication of Organic-inorganic Perovskites for Highly Efficient Solar Cells and Light Emitting Diodes January 19, 2016 at 4:30pm/36-428 Sandeep Pathak Oxford University Pathak The unprecedented worldwide interest in organic-inorganic lead halide-based perovskite (HC(NH2)2PbX3 or CH3NH3PbX3) solar cells is rooted in its solution process-ability at low temperature as well as its extraordinary device performance. Perovskite

  11. Wide Area Thermal Processing of Light Emitting Materials

    SciTech Connect (OSTI)

    Duty, Chad E; Joshi, Pooran C; Jellison Jr, Gerald Earle; Angelini, Joseph Attilio; Sabau, Adrian S

    2011-10-01

    Laboratory laser materials synthesis of wide bandgap materials has been successfully used to create white light emitting materials (LEMs). This technology development has progressed to the exploration on design and construction of apparatus for wide area doping and phase transformation of wide bandgap material substrates. The objective of this proposal is to develop concepts for wide area doping and phase transformation based on AppliCote Associates, LLC laser technology and ORNL high density pulsed plasma arc technology.

  12. Light collection optics for measuring flux and spectrum from light-emitting devices

    DOE Patents [OSTI]

    McCord, Mark A.; DiRegolo, Joseph A.; Gluszczak, Michael R.

    2016-05-24

    Systems and methods for accurately measuring the luminous flux and color (spectra) from light-emitting devices are disclosed. An integrating sphere may be utilized to directly receive a first portion of light emitted by a light-emitting device through an opening defined on the integrating sphere. A light collector may be utilized to collect a second portion of light emitted by the light-emitting device and direct the second portion of light into the integrating sphere through the opening defined on the integrating sphere. A spectrometer may be utilized to measure at least one property of the first portion and the second portion of light received by the integrating sphere.

  13. High Efficiency Organic Light Emitting Devices for Lighting

    SciTech Connect (OSTI)

    So, Franky; Tansu, Nelson; Gilchrist, James

    2013-06-30

    Incorporate internal scattering layers and microlens arrays in high efficiency OLED to achieve up to 70% EQE.

  14. Stable, High-Efficiency White Electrophosphorescent Organic Light Emitting

    Broader source: Energy.gov (indexed) [DOE]

    Devices by Reduced Molecular Dissociation | Department of Energy University of Michigan - Ann Arbor - Ann Arbor, MI Partners: -- University of California - City, CA -- Universal Display Corporation - Ewing, NJ DOE Total Funding: $1,314,240 Cost Share: $433,398 Project Term: September 1, 2015 - August 31, 2017 Funding Opportunity: SSL R&D Funding Opportunity Announcement (FOA) (DE-FOA-0001171) Project Objective This project will focus on new strategies for increasing the lifetime of blue

  15. White light emitting Ho{sup 3+}-doped CdS nanocrystal ingrained glass nanocomposites

    SciTech Connect (OSTI)

    Dey, Chirantan; Karmakar, Basudeb; Goswami, Madhumita

    2015-02-23

    We report the generation of white light from Ho{sup 3+} ion doped CdS nanocrystal ingrained borosilicate glass nanocomposites prepared by the conventional melt-quench method. Near visible 405?nm diode laser excited white light emission is produced by tuning the blue emission from the Ho{sup 3+} ions, green band edge, and orange-red surface-state emissions of the nanocrystalline CdS, which are further controlled by the size of the nanocrystals. The absorption and emission spectra evidenced the excitation of Ho{sup 3+} ions by absorption of photons emitted by the CdS nanocrystals. The high color rendering index (CRI?=?8489) and befitting chromaticity coordinates (x?=?0.3080.309, y?=?0.3260.338) of white light emission, near visible harmless excitation wavelength (405?nm), and high absorbance values at excitation wavelength point out that these glass nanocomposites may serve as a prominent candidate for resin free high power white light emitting diodes.

  16. Oxycarbonitride phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

    2014-07-08

    Disclosed herein is a novel family of oxycarbonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

  17. Oxycarbonitride phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

    2013-10-08

    Disclosed herein is a novel family of oxycarbidonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbidonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

  18. High brightness diode-pumped organic solid-state laser

    SciTech Connect (OSTI)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien

    2015-02-02

    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  19. Carbonitride based phosphors and light emitting devices using the same

    DOE Patents [OSTI]

    Li, Yuanqiang; Tian, Yongchi; Romanelli, Michael Dennis

    2013-08-20

    Disclosed herein is a novel group of carbidonitride phosphors and light emitting devices which utilize these phosphors. In certain embodiments, the present invention is directed to a novel family of carbidonitride-based phosphors expressed as follows: Ca.sub.1-xAl.sub.x-xySi.sub.1-x+xyN.sub.2-x-xyC.sub.xy:A; (1) Ca.sub.1-x-zNa.sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.sub.xy:- A; (2) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x- -xyC.sub.xy:A; (3) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3C.sub.xyO.sub.w-v/2H.sub.v:A; and (4) M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w/- 3-v/3C.sub.xyO.sub.wH.sub.v:A, (4a) wherein 0xy+z, and 0

  20. Excitons in Highly Efficient Organic Devices | MIT-Harvard Center for

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Excitonics Excitons in Highly Efficient Organic Devices November 29, 2012 at 3pm/36-428 Karl Leo Department of Mathematics and Natural Sciences, Department of Physics, Technical University of Dresden bio_Karl_leo_d_e Abstract: Organic semiconductors with conjugated electron system are currently intensively investigated for optoelectronic applications. This interest is spurred by novel devices such as organic light-emitting diodes (OLED), and organic solar cells. For both devices, high

  1. Hybrid Organic-Inorganic Halide Perovskite Solar Cells | Department...

    Energy Savers [EERE]

    remain before perovskite solar cells can become a competitive commercial technology. ... semiconductor applications, including thin-film transistors and light-emitting diodes, ...

  2. Megahertz organic/polymer diodes (Patent) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Patent: Megahertz organicpolymer diodes Citation Details In-Document Search Title: ... of a material whose characteristics and properties are such that when formed on the first ...

  3. Promising Technology: Retrofit Lights to Light-Emitting Diodes in Refrigerators

    Broader source: Energy.gov [DOE]

    LEDs increase in efficacy at lower temperatures, in contrast with conventional fluorescents. The low temperatures in display cases, therefore, make this an attractive application of LEDs to reduce energy consumption. In addition to saving lighting energy, an LED retrofit can potentially reduce the cooling load in a display case because LEDs emit less heat than do fluorescent bulbs.

  4. Demonstration Assessment of Light-Emitting Diode (LED) Freezer Case Lighting

    Broader source: Energy.gov [DOE]

    This document is a report of observations and results obtained from a lighting demonstration project conducted under a U.S. Department of Energy program. The program supports demonstrations of high-performance solid-state lighting (SSL) products in order to develop empirical data and experience with in-the-field applications of this advanced lighting technology for plant-wide improvement.

  5. Light emitting diode with porous SiC substrate and method for fabricating

    DOE Patents [OSTI]

    Li, Ting; Ibbetson, James; Keller, Bernd

    2005-12-06

    A method and apparatus for forming a porous layer on the surface of a semiconductor material wherein an electrolyte is provided and is placed in contact with one or more surfaces of a layer of semiconductor material. The electrolyte is heated and a bias is introduced across said electrolyte and the semiconductor material causing a current to flow between the electrolyte and the semiconductor material. The current forms a porous layer on the one or more surfaces of the semiconductor material in contact with the electrolyte. The semiconductor material with its porous layer can serve as a substrate for a light emitter. A semiconductor emission region can be formed on the substrate. The emission region is capable of emitting light omnidirectionally in response to a bias, with the porous layer enhancing extraction of the emitting region light passing through the substrate.

  6. Layering Mismatched Lattices Creates Long-Sought-After Green Light-Emitting Diode (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2011-02-01

    Scientists at the National Renewable Energy Laboratory (NREL) invent a deep green LED that can lead to higher-efficiency white light, lower electric bills.

  7. Demonstration Assessment of Light-Emitting Diode (LED) Freezer Case Lighting

    SciTech Connect (OSTI)

    Rishman, E. E.; Tuenge, J. R.

    2009-10-01

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology combined with occupancy sensors in a set of upright grocery store freezer cases.

  8. Demonstration Assessment of Light-Emitting Diode (LED) Post-Top...

    Office of Scientific and Technical Information (OSTI)

    This report reviews the energy savings potential and lighting delivered by the LED post-top luminaires. Authors: Myer, Michael ; Goettel, Russell T. ; Kinzey, Bruce R. Publication ...

  9. Demonstration Assessment of Light Emitting Diode (LED) Street Lighting, Final Report

    Office of Energy Efficiency and Renewable Energy (EERE)

    This report summarizes an LED street lighting assessment project conducted to study the applicability of LED luminaires in a street lighting application.

  10. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting, Phase I

    SciTech Connect (OSTI)

    Myer, M. A.; Goettel, R. T.

    2010-06-22

    U.S. DOE Solid-State Lighting Technology Demonstration GATEWAY Program Report on the TJMaxx Demonstration.

  11. Demonstration Assessment of Light-Emitting Diode (LED) Street Lighting Host Site: Lija Loop, Portland, Oregon

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael

    2009-11-01

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in a residential street lighting application, under the U.S. Department of Energy GATEWAY Solid-State Lighting Technology Demonstration Program. In this project, eight 100W (nominal) high-pressure sodium cobra head fixtures were replaced with a like number of LED street light luminaires manufactured by Leotek, Inc. The Leotek product achieved an estimated payback in the Lija Loop installation of about 20 years for replacement scenarios and a much shorter 7.6 years for new installations. Much of the associated energy savings (55%) supporting these payback periods, however, were achieved by reducing average horizontal photopic illuminance a similar amount (53%). Examined from a different perspective, the measured performance suggests that the Leotek product is at approximate parity with the HPS cobra head in terms of average delivered photopic illumination for a given power consumption. HPS comprises the second most efficacious street lighting technology available, exceeded only by low pressure sodium (LPS). LPS technology is not considered suitable for most street lighting applications due to its monochromatic spectral output and poor color rendering ability; therefore, this LED product is performing at an efficiency level comparable to its primary competition in this application.

  12. Demonstration Assessment of Light-Emitting Diode (LED) Residential Downlights and Undercabinet Lights

    SciTech Connect (OSTI)

    Ton, M. K.; Richman, E. E.; Gilbride, T. L.

    2008-10-01

    This document is a report of observations and results obtained from a lighting demonstration project conducted under the U.S. Department of Energy (DOE) Solid-State Lighting (SSL) GATEWAY Demonstration Program.

  13. Demonstration Assessment of Light Emitting Diode (LED) Street Lighting, Phase III Continuation

    SciTech Connect (OSTI)

    Cook, Tyson; Shackelford, Jordan; Johnson, Megan; Pang, Terrance

    2008-11-01

    This report summarizes the third phase of an LED street lighting assessment project in Oakland, California, conducted to study the applicability of LED luminaires in a street lighting application.

  14. Metal-halide perovskites for photovoltaic and light-emitting...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    systems. *This talk is the first of the Perovskites Seminar Series organized by Sam Stranks and sponsored by the Center for Excitonics. For more info contact Sam: stranks@mit.edu

  15. Electrical conduction of LiF interlayers in organic diodes

    SciTech Connect (OSTI)

    Bory, Benjamin F.; Janssen, Ren A. J.; Meskers, Stefan C. J.; Gomes, Henrique L.; Leeuw, Dago M. de

    2015-04-21

    An interlayer of LiF in between a metal and an organic semiconductor is commonly used to improve the electron injection. Here, we investigate the effect of moderate bias voltages on the electrical properties of Al/LiF/poly(spirofluorene)/Ba/Al diodes by systematically varying the thickness of the LiF layer (2-50?nm). Application of forward bias V below the bandgap of LiF (V?

  16. Concepts for Phosphorescent Organic LEDs at High Brightness | MIT-Harvard

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Center for Excitonics Concepts for Phosphorescent Organic LEDs at High Brightness May 24, 2010 at 3pm/36-428 Sebastian Reineke Institut für Angewandte Photophysik, Dresden reineke_001 abstract: Organic light-emitting diodes (OLEDs) are next generation light sources which are especially attractive because they promise very high conversion efficiencies. The introduction of phosphorescent emitter materials was the key to enable internal quantum efficiencies approaching unity. However, due to

  17. Structure of Molecular Thin Films for Organic Electronics | Stanford

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Synchrotron Radiation Lightsource Structure of Molecular Thin Films for Organic Electronics Friday, April 6, 2012 - 1:00pm SSRL Conference Room 137-322 Bert Nickel, Physics Faculty and CeNS, Ludwig-Maximilians-University, München Thin films made out of conjugated small molecules and polymers exhibit very interesting semiconducting properties. While some applications such as light emitting diodes (OLED) are already on the market, other application such as solar cells, integrated circuits,

  18. Ultra-thin ohmic contacts for p-type nitride light emitting devices

    DOE Patents [OSTI]

    Raffetto, Mark; Bharathan, Jayesh; Haberern, Kevin; Bergmann, Michael; Emerson, David; Ibbetson, James; Li, Ting

    2012-01-03

    A semiconductor based Light Emitting Device (LED) can include a p-type nitride layer and a metal ohmic contact, on the p-type nitride layer. The metal ohmic contact can have an average thickness of less than about 25 .ANG. and a specific contact resistivity less than about 10.sup.-3 ohm-cm.sup.2.

  19. Metal-halide perovskites for photovoltaic and light-emitting devices* |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MIT-Harvard Center for Excitonics Metal-halide perovskites for photovoltaic and light-emitting devices* September 15, 2015 at 4:30 pm/36-428 Sam Stranks Massachusetts Institute of Technology stranks.02 Metal halide perovskites are exotic hybrid crystalline materials developed out of curiosity. Unexpectedly, solar cells incorporating these perovskites are rapidly emerging as serious contenders to rival the leading photovoltaic technologies. Power conversion efficiencies have jumped from 3% to

  20. Entangled Light Emission From a Diode

    SciTech Connect (OSTI)

    Stevenson, R. M.; Shields, A. J. [Toshiba Research Europe Limited, 208 Cambridge Science Park, Cambridge CB4 0GZ (United Kingdom); Salter, C. L. [Toshiba Research Europe Limited, 208 Cambridge Science Park, Cambridge CB4 0GZ (United Kingdom); Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Farrer, I.; Nicoll, C. A.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2011-12-23

    Electrically-driven entangled photon generation is demonstrated for the first time using a single semiconductor quantum dot embedded in a light emitting diode structure. The entanglement fidelity is shown to be of sufficient quality for applications such as quantum key distribution.

  1. Ultra-thin ohmic contacts for p-type nitride light emitting devices

    DOE Patents [OSTI]

    Raffetto, Mark; Bharathan, Jayesh; Haberern, Kevin; Bergmann, Michael; Emerson, David; Ibbetson, James; Li, Ting

    2014-06-24

    A flip-chip semiconductor based Light Emitting Device (LED) can include an n-type semiconductor substrate and an n-type GaN epi-layer on the substrate. A p-type GaN epi-layer can be on the n-type GaN epi-layer and a metal ohmic contact p-electrode can be on the p-type GaN epi-layer, where the metal ohmic contact p-electrode can have an average thickness less than about 25 .ANG.. A reflector can be on the metal ohmic contact p-electrode and a metal stack can be on the reflector. An n-electrode can be on the substrate opposite the n-type GaN epi-layer and a bonding pad can be on the n-electrode.

  2. Depth-resolved confocal micro-Raman spectroscopy for characterizing GaN-based light emitting diode structures

    SciTech Connect (OSTI)

    Chen, Wei-Liang; Lee, Yu-Yang; Chang, Yu-Ming; Chang, Chiao-Yun; Huang, Huei-Min; Lu, Tien-Chang

    2013-11-15

    In this work, we demonstrate that depth-resolved confocal micro-Raman spectroscopy can be used to characterize the active layer of GaN-based LEDs. By taking the depth compression effect due to refraction index mismatch into account, the axial profiles of Raman peak intensities from the GaN capping layer toward the sapphire substrate can correctly match the LED structural dimension and allow the identification of unique Raman feature originated from the 0.3 μm thick active layer of the studied LED. The strain variation in different sample depths can also be quantified by measuring the Raman shift of GaN A{sub 1}(LO) and E{sub 2}(high) phonon peaks. The capability of identifying the phonon structure of buried LED active layer and depth-resolving the strain distribution of LED structure makes this technique a potential optical and remote tool for in operando investigation of the electronic and structural properties of nitride-based LEDs.

  3. InxGa1-xN Multiple-Quantum-Well Light-Emitting Diodes Grown on...

    Office of Scientific and Technical Information (OSTI)

    Christopher ; Mueller, Jason ; Parra, Eduardo ; Gilgen, Joseph ; Boley, Allison ; Smith, David J. ; Tsong, Ignatius S. T. ; Roberts, John C. ; Piner, Edwin ; Linthicum, Kevin ...

  4. Modulating emission intensity of GaN-based green light emitting diodes on c-plane sapphire

    SciTech Connect (OSTI)

    Du, Chunhua; Ma, Ziguang; Zhou, Junming; Lu, Taiping; Jiang, Yang; Jia, Haiqiang; Liu, Wuming; Chen, Hong

    2014-04-14

    The asymmetric dual-wavelength (green/blue) coupled InGaN/GaN multiple quantum wells were proposed to modulate the green emission intensity. Electroluminescent measurements demonstrate the conspicuous increment of the green light intensity by decreasing the coupled barrier thickness. This was partly attributed to capture of more carriers when holes tunnel across the thinner barrier from the blue quantum wells, as a hole reservoir, to the green quantum wells. While lower effective barrier height of the blue quantum wells benefits improved hole transportation from p-GaN to the active region. Efficiency droop of the green quantum wells was partially alleviated due to the enhanced injection efficiency of holes.

  5. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting, I-35W Bridge, Minneapolis, Minnesota, Phase II Report

    SciTech Connect (OSTI)

    Kinzey, B. R.; Davis, R. G.

    2014-09-30

    On the I-35W Bridge in Minneapolis, Minnesota, the GATEWAY program conducted a two-phase demonstration of LED roadway lighting on the main span, which is one of the country's oldest continuously operated exterior LED lighting installations. The Phase II report documents longer-term performance of the LED lighting system that was installed in 2008, and is the first report on the longer-term performance of LED lighting in the field.

  6. Demonstration Assessment of Light-Emitting Diode Post-Top Lighting at Central Park in New York City

    SciTech Connect (OSTI)

    Myer, M. A.; Goettel, R. T.

    2012-09-01

    GATEWAY program report on a demonstration of LED post-top lighting in Central Park in New York City.

  7. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting on Residential and Commercial Streets in Palo Alto, CA

    SciTech Connect (OSTI)

    Myer, Michael; Kinzey, Bruce R.; Tam, Christine

    2010-06-24

    This report is part of a GATEWAY demonstration that replaced existing HPS streetlights with two different types of LED products and one induction product. Energy savings ranged from 6% to 44%.

  8. Surface plasmon dispersion engineering via double-metallic AU/AG layers for nitride light-emitting diodes

    DOE Patents [OSTI]

    Tansu, Nelson; Zhao, Hongping; Zhang, Jing; Liu, Guangyu

    2014-04-01

    A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.

  9. Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps at Intercontinental Hotel in San Francisco, CA

    SciTech Connect (OSTI)

    Miller, Naomi J.; Curry, Ku'Uipo J.

    2010-11-01

    This document is a report of observations and results obtained from a lighting demonstration project conducted under the U.S. Department of Energy (DOE) GATEWAY Demonstration Program. The program supports demonstrations of high-performance solid-state lighting (SSL) products in order to develop empirical data and experience with in-the-field applications of this advanced lighting technology. The DOE GATEWAY Demonstration Program focuses on providing a source of independent, third-party data for use in decision-making by lighting users and professionals; this data should be considered in combination with other information relevant to the particular site and application under examination. Each GATEWAY Demonstration compares SSL products against the incumbent technologies used in that location. Depending on available information and circumstances, the SSL product may also be compared to alternate lighting technologies. Though products demonstrated in the GATEWAY program have been prescreened and tested to verify their actual performance, DOE does not endorse any commercial product or in any way guarantee that users will achieve the same results through use of these products.

  10. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, Minneapolis, MN

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael

    2009-08-31

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology conducted in 2009 at the recently reconstructed I-35W bridge in Minneapolis, MN. The project was supported under the U.S. Department of Energy (DOE) Solid-State Lighting GATEWAY Technology Demonstration Program. Other participants in the demonstration project included the Minnesota Department of Transportation (Mn/DOT), Federal Highways Administration (FHWA), and BetaLED™ (a division of Ruud Lighting). Pacific Northwest National Laboratory (PNNL) conducted the measurements and analysis of the results. DOE has implemented a three-year evaluation of the LED luminaires in this installation in order to develop new longitudinal field data on LED performance in a challenging, real-world environment. This document provides information through the initial phase of the I-35W bridge project, up to and including the opening of the bridge to the public and the initial feedback received on the LED lighting installation from bridge users. Initial findings of the evaluation are favorable, with minimum energy savings level of 13% for the LED installation relative to the simulated base case using 250W high-pressure sodium (HPS) fixtures. The LEDs had an average illuminance level of 0.91 foot candles compared to 1.29 fc for the HPS lamps. The LED luminaires cost $38,000 more than HPS lamps, yielding a lengthy payback period, however the bridge contractor had offered to include the LED luminaires as part of the construction package at no additional cost. One potentially significant benefit of the LEDs in this installation is avoiding rolling lane closures on the heavily-traveled interstate bridge for the purpose of relamping the HPS fixtures. Rolling lane closures involve multiple crew members and various maintenance and safety vehicles, diversion of traffic, as well as related administrative tasks (e.g., approvals, scheduling, etc.). Mn/DOT records show an average cost of relamping fixtures along interstate roadways of between $130-150 per pole. The previous bridge saw a lamp mortality rate of approximately 50% every two years, though the new bridge was designed to minimize many of the vibration issues. A voluntary Web-based feedback survey of nearly 500 self-described bridge users showed strong preference for the LED lighting - positive comments outnumbered negative ones by about five-to-one.

  11. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting, I-35W Bridge, Minneapolis, Minnesota, Phase I Report

    SciTech Connect (OSTI)

    Kinzey, B. R.; Myer, M. A.

    2009-08-01

    On the I-35W Bridge in Minneapolis, Minnesota, the GATEWAY program conducted a two-phase demonstration of LED roadway lighting on the main span, which is one of the country's oldest continuously operated exterior LED lighting installations. The Phase I report provides an overview of initial project results including lighting performance, economic performance, and potential energy savings.

  12. Electronic structure of the polymer-cathode interface of an organic electroluminescent device investigated using operando hard x-ray photoelectron spectroscopy

    SciTech Connect (OSTI)

    Ikeuchi, J.; Hamamatsu, H.; Miyamoto, T.; Tanaka, S.; Yamashita, Y.; Yoshikawa, H.; Ueda, S.

    2015-08-28

    The electronic structure of a polymer-cathode interface of an operating organic light-emitting diode (OLED) was directly investigated using hard X-ray photoelectron spectroscopy (HAXPES). The potential distribution profile of the light-emitting copolymer layer as a function of the depth under the Al/Ba cathode layer in the OLED depended on the bias voltage. We found that band bending occurred in the copolymer of 9,9-dioctylfluorene (50%) and N-(4-(2-butyl)-phenyl)diphenylamine (F8-PFB) layer near the cathode at 0 V bias, while a linear potential distribution formed in the F8-PFB when a bias voltage was applied to the OLED. Direct observation of the built-in potential and that band bending formed in the F8-PFB layer in the operating OLED suggested that charges moved in the F8-PFB layer before electron injection from the cathode.

  13. Ultra-thin titanium nanolayers for plasmon-assisted enhancement of bioluminescence of chloroplast in biological light emitting devices

    SciTech Connect (OSTI)

    Hsun Su, Yen; Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan ; Hsu, Chia-Yun; Chang, Chung-Chien; Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan ; Tu, Sheng-Lung; Shen, Yun-Hwei

    2013-08-05

    Ultra-thin titanium films were deposited via ultra-high vacuum ion beam sputter deposition. Since the asymmetric electric field of the metal foil plane matches the B-band absorption of chlorophyll a, the ultra-thin titanium nanolayers were able to generate surface plasmon resonance, thus enhancing the photoluminescence of chlorophyll a. Because the density of the states of plasmon resonance increases, the enhancement of photoluminescence also rises. Due to the biocompatibility and inexpensiveness of titanium, it can be utilized to enhance the bioluminescence of chloroplast in biological light emitting devices, bio-laser, and biophotonics.

  14. Confocal Microscopy on Light-emitting Nanostructures and X-ray Imaging Detectors Based on Color Centers in Lithium Fluoride

    SciTech Connect (OSTI)

    Bonfigli, F.; Almaviva, S.; Montereali, R. M.

    2010-10-06

    Confocal Laser Scanning Microscope (CLSM) is a versatile and powerful optical instrument which is gaining a strong increase of interest for biological investigations and also for the characterization of materials, microstructures and devices. We exploit its capability for the characterization of light-emitting micro and nano-structures based on color centers in lithium fluoride. CLSM was successfully used as an advanced optical reading system to detect X-ray micro-radiographies of biological specimens stored in LiF imaging detectors.

  15. Data Diode

    Energy Science and Technology Software Center (OSTI)

    2014-11-07

    The Data Diode is a data security technology that can be deployed within an organization's defense-in-depth computer network strategy for information assurance. For internal security, the software creates an environment within the network where an organization's approved users can work freely inside an enclave of protected data, but file transfers out of the enclave is restricted. For external security, once a network intruder has penetrated the network, the intruder is able to "see" the protectedmore » data, but is unable to download the actual data. During the time it takes for the intruder to search for a way around the obstacle created by the Data Diode, the network's intrusion detection technologies can locate and thwart the malicious intent of the intruder. Development of the Data Diode technology was made possible by funding from the Intelligence Advanced Research Projects Activity (IARPA).« less

  16. Modulation of hole-injection in GaInN-light emitting triodes and its effect on carrier recombination behavior

    SciTech Connect (OSTI)

    Hwang, Sunyong; Kim, Dong Yeong; Park, Jun Hyuk; Kim, Jong Kyu; Ryu, Han-Youl

    2015-10-15

    The effects of the hole injection modulated by using a three-terminal GaInN-based light emitter, light-emitting triode (LET), on carrier recombination behavior and efficiency droop are investigated. It was found that the lateral electric field created by applying voltage bias between the two anodes effectively reduces efficiency droop as well as dynamic conductance of LETs. Detailed analyses of LETs under various operation conditions by APSYS simulations reveal that the asymmetry in carrier transport between electrons and holes is alleviated by promoted injection of hot holes over the potential barrier, increasing the hole concentration as well as the radiative recombination rate in the multiple quantum well active region.

  17. Semiconductor light-emitting devices having concave microstructures providing improved light extraction efficiency and method for producing same

    DOE Patents [OSTI]

    Tansu, Nelson; Gilchrist, James F; Ee, Yik-Khoon; Kumnorkaew, Pisist

    2013-11-19

    A conventional semiconductor LED is modified to include a microlens layer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.

  18. Carrier-induced transient defect mechanism for non-radiative recombination in InGaN light-emitting devices

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bang, Junhyeok; Sun, Y. Y.; Song, Jung -Hoon; Zhang, S. B.

    2016-04-14

    Non-radiative recombination (NRR) of excited carriers poses a serious challenge to optoelectronic device efficiency. Understanding the mechanism is thus crucial to defect physics and technological applications. Here, by using first-principles calculations, we propose a new NRR mechanism, where excited carriers recombine via a Frenkel-pair (FP) defect formation. While in the ground state the FP is high in energy and is unlikely to form, in the electronic excited states its formation is enabled by a strong electron-phonon coupling of the excited carriers. As a result, this NRR mechanism is expected to be general for wide-gap semiconductors, rather than being limited tomore » InGaN-based light emitting devices.« less

  19. Calcium chloride electron injection/extraction layers in organic electronic devices

    SciTech Connect (OSTI)

    Qu, Bo, E-mail: bqu@pku.edu.cn, E-mail: qhgong@pku.edu.cn; Gao, Zhi; Yang, Hongsheng; Xiao, Lixin; Chen, Zhijian; Gong, Qihuang, E-mail: bqu@pku.edu.cn, E-mail: qhgong@pku.edu.cn [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)

    2014-01-27

    Nontoxic calcium chloride (CaCl{sub 2}) was introduced into organic electronic devices as cathode buffer layer (CBL). The turn-on voltage and maximum luminance of organic light-emitting diode (OLED) with 1.5?nm CaCl{sub 2} was 3.5?V and 21960?cd/m{sup 2}, respectively. OLED with 1.5?nm CaCl{sub 2} possessed comparable electroluminescent characteristics to that of the commonly used LiF. Moreover, the performance of the organic photovoltaic device with 0.5?nm CaCl{sub 2} was comparable to that of the control device with LiF. Therefore, CaCl{sub 2} has the potential to be used as the CBL for organic electronic devices.

  20. Dual function conducting polymer diodes

    DOE Patents [OSTI]

    Heeger, Alan J.; Yu, Gang

    1996-01-01

    Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

  1. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    SciTech Connect (OSTI)

    Romero, V.H.; De la Rosa, E.; Salas, P.; Velazquez-Salazar, J.J.

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  2. A novel broadband emission phosphor Ca{sub 2}KMg{sub 2}V{sub 3}O{sub 12} for white light emitting diodes

    SciTech Connect (OSTI)

    Li, Junfu; Qiu, Kehui; Li, Junfeng; Li, Wei; Yang, Qian; Li, Junhan

    2010-05-15

    A novel broadband emission phosphor Ca{sub 2}KMg{sub 2}V{sub 3}O{sub 12} was first synthesized by solution combustion method. The X-ray diffraction showed that Ca{sub 2}KMg{sub 2}V{sub 3}O{sub 12} phase can be obtained at 600-900 {sup o}C through combustion route. The crystal structure of this material was refined by Rietveld method using powder X-ray diffraction. It crystallizes in cubic system and belongs to space group Ia3d with z = 8, a = 0.12500 nm. The excitation band of Ca{sub 2}KMg{sub 2}V{sub 3}O{sub 12} peaks at 320 nm in a region between 260 nm and 425 nm, and the emission spectrum exhibits an intense band centered at about 528 nm covering from 400 nm to 800 nm. The colour coordinates of samples prepared at different ignition temperatures are in a range of x = 0.323-0.339, y = 0.430-0.447.

  3. Emission color-tuned light-emitting diode microarrays of nonpolar InxGa1–xN/GaN multishell nanotube heterostructures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hong, Young Joon; Lee, Chul -Ho; Yoo, Jinkyoung; Kim, Yong -Jin; Jeong, Junseok; Kim, Miyoung; Yi, Gyu -Chul

    2015-12-09

    Integration of nanostructure lighting source arrays with well-defined emission wavelengths is of great importance for optoelectronic integrated monolithic circuitry. We report on the fabrication and optical properties of GaN-based p–n junction multishell nanotube microarrays with composition-modulated nonpolar m-plane InxGa1–xN/GaN multiple quantum wells (MQWs) integrated on c-sapphire or Si substrates. The emission wavelengths were controlled in the visible spectral range of green to violet by varying the indium mole fraction of the InxGa1–xN MQWs in the range 0.13 ≤ x ≤ 0.36. Homogeneous emission from the entire area of the nanotube LED arrays was achieved via the formation of MQWs withmore » uniform QW widths and composition by heteroepitaxy on the well-ordered nanotube arrays. Importantly, the wavelength-invariant electroluminescence emission was observed above a turn-on of 3.0 V because both the quantum-confinement Stark effect and band filling were suppressed due to the lack of spontaneous inherent electric field in the m-plane nanotube nonpolar MQWs. Lastly, the method of fabricating the multishell nanotube LED microarrays with controlled emission colors has potential applications in monolithic nonpolar photonic and optoelectronic devices on commonly used c-sapphire and Si substrates.« less

  4. Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode

    SciTech Connect (OSTI)

    Wallace, M. J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Kappers, M. J.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Hopkins, M. A.; Sivaraya, S.; Allsopp, D. W. E. [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-07-21

    Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 210??m in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 3040?meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (?100??m) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.

  5. Effect of the band structure of InGaN/GaN quantum well on the surface plasmon enhanced light-emitting diodes

    SciTech Connect (OSTI)

    Li, Yi; Zhang, Rong E-mail: bliu@nju.edu.cn; Liu, Bin E-mail: bliu@nju.edu.cn; Xie, Zili; Zhang, Guogang; Tao, Tao; Zhuang, Zhe; Zhi, Ting; Zheng, Youdou

    2014-07-07

    The spontaneous emission (SE) of InGaN/GaN quantum well (QW) structure with silver(Ag) coated on the n-GaN layer has been investigated by using six-by-six K-P method taking into account the electron-hole band structures, the photon density of states of surface plasmon polariton (SPP), and the evanescent fields of SPP. The SE into SPP mode can be remarkably enhanced due to the increase of electron-hole pairs near the Ag by modulating the InGaN/GaN QW structure or increasing the carrier injection. However, the ratio between the total SE rates into SPP mode and free space will approach to saturation or slightly decrease for the optimized structures with various distances between Ag film and QW layer at a high injection carrier density. Furthermore, the Ga-face QW structure has a higher SE rate than the N-face QW structure due to the overlap region of electron-hole pairs nearer to the Ag film.

  6. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting at T.J.Maxx in Manchester, NH Phase I

    SciTech Connect (OSTI)

    Myer, Michael; Goettel, Russell T.

    2010-06-29

    A report describing the process and results of replacing existing parking lot lighting, looking at a LED option with occupancy sensors, and conventional alternates. Criteria include payback, light levels, occupant satisfaction. This report is Phase I of II. Phase I deals with initial installation.

  7. Demonstration Assessment of Light-Emitting Diode (LED) Retrofit Lamps at an Exhibit of 19th Century Photography at the Getty Museum

    SciTech Connect (OSTI)

    Miller, N. J.; Druzik, J. R.

    2012-03-01

    GATEWAY program report on a demonstration of LED retrofit lamps at the J. Paul Getty Museum in Malibu, CA.

  8. Multifunctional oxides for integrated manufacturing of efficient graphene electrodes for organic electronics

    SciTech Connect (OSTI)

    Kidambi, Piran R.; Robertson, John; Hofmann, Stephan; Weijtens, Christ; Meyer, Jens

    2015-02-09

    Using multi-functional oxide films, we report on the development of an integration strategy for scalable manufacturing of graphene-based transparent conducting electrodes (TCEs) for organic electronics. A number of fundamental and process challenges exists for efficient graphene-based TCEs, in particular, environmentally and thermally stable doping, interfacial band engineering for efficient charge injection/extraction, effective wetting, and process compatibility including masking and patterning. Here, we show that all of these challenges can be effectively addressed at once by coating graphene with a thin (>10 nm) metal oxide (MoO{sub 3} or WO{sub 3}) layer. We demonstrate graphene electrode patterning without the need for conventional lithography and thereby achieve organic light emitting diodes with efficiencies exceeding those of standard indium tin oxide reference devices.

  9. High-temperature luminescence in an n-GaSb/n-InGaAsSb/p-AlGaAsSb light-emitting heterostructure with a high potential barrier

    SciTech Connect (OSTI)

    Petukhov, A. A., E-mail: andrey-rus29@rambler.ru; Zhurtanov, B. E.; Kalinina, K. V.; Stoyanov, N. D.; Salikhov, H. M.; Mikhailova, M. P.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-09-15

    The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface ({Delta}E{sub c} = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence (EL) spectrum. In the entire temperature range under study, T = 290-480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated as a result of the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the EL intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290-345 K, and a linear increase is observed at T > 345 K. This work for the first time reports an increase in the emission power of a light-emitting diode structure with increasing temperature. It is shown that this rise is caused by a decrease in the threshold energy of the impact ionization due to narrowing of the band gap of the active region.

  10. Understanding the role of electron and hole trions on current transport in aluminium tris(8-hydroxyquinoline) using organic magnetoresistance

    SciTech Connect (OSTI)

    Zhang, Sijie; Gillin, W. P.; Willis, M.; Gotto, R.; Roy, K. A.; Kreouzis, T.; Rolfe, N. J.

    2014-01-27

    The change in current through an organic light emitting diode (OLED) when it is placed in a magnetic field has been dubbed organic magnetoresistance and provides a means to understand the spin interactions that are occurring in working devices. Whilst there are a wide range of interactions that have been proposed to be the cause of the measured effects, there is still a need to identify their individual roles and in particular how they respond to an applied magnetic field. In this work, we investigate the effect of changing the balance of electron and hole injection in a simple aluminium tris(8-hydroxyqinoline) based OLED and demonstrate that the triplet polaron interaction appears to be much stronger for electrons than for holes in this material.

  11. Visionox Inc | Open Energy Information

    Open Energy Info (EERE)

    China Zip: 100085 Product: Visionox is engaged in the development, manufacturing and marketing of display products, typically OLED (Organic Light Emitting Diode Display)....

  12. Energy Department Announces Winners of Next Generation Luminaires...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Solid-state lighting (SSL), which includes LED and organic light emitting diode (OLED) ... evaluated the entries based on characteristics such as color, illuminance, glare ...

  13. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    structure (1) fermi level (1) fluorescence (1) gallium alloys (1) hole mobility ... a device, has an important function in fluorescence-based organic light-emitting diodes ...

  14. Hot-Wire Chemical Vapor Deposition (HWCVD) technologies - Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Applications and Industries Solar cells Thin-film transistors Light emitting diodes Gas sensors Electrochromic windows Organic devices Micromechanical structures Patents and Patent ...

  15. Company Name Company Name Address Place Zip Sector Product Website

    Open Energy Info (EERE)

    manufacturing and marketing of display products typically OLED Organic Light Emitting Diode Display Vista International Inc Vista International Inc Englewood Colorado...

  16. Analysis of different tunneling mechanisms of In{sub x}Ga{sub 1?x}As/AlGaAs tunnel junction light-emitting transistors

    SciTech Connect (OSTI)

    Wu, Cheng-Han; Wu, Chao-Hsin

    2014-10-27

    The electrical and optical characteristics of tunnel junction light-emitting transistors (TJLETs) with different indium mole fractions (x?=?5% and 2.5%) of the In{sub x}Ga{sub 1?x}As base-collector tunnel junctions have been investigated. Two electron tunneling mechanisms (photon-assisted or direct tunneling) provide additional currents to electrical output and resupply holes back to the base region, resulting in the upward slope of I-V curves and enhanced optical output under forward-active operation. The larger direct tunneling probability and stronger Franz-Keldysh absorption for 5% TJLET lead to higher collector current slope and less optical intensity enhancement when base-collector junction is under reverse-biased.

  17. Development of White-Light Emitting Active Layers in Nitride Based Heterostructures for Phosphorless Solid State Lighting

    SciTech Connect (OSTI)

    Jan Talbot; Kailash Mishra

    2007-12-31

    This report provides a summary of research activities carried out at the University of California, San Diego and Central Research of OSRAM SYLVANIA in Beverly, MA partially supported by a research contract from US Department of Energy, DE-FC26-04NT422274. The main objective of this project was to develop III-V nitrides activated by rare earth ions, RE{sup 3+}, which could eliminate the need for phosphors in nitride-based solid state light sources. The main idea was to convert electron-hole pairs injected into the active layer in a LED die to white light directly through transitions within the energy levels of the 4f{sup n}-manifold of RE{sup 3+}. We focused on the following materials: Eu{sup 3+}(red), Tb{sup 3+}(green), Er{sup 3+}(green), Dy{sup 3+}(yellow) and Tm{sup 3+}(blue) in AlN, GaN and alloys of AlN and GaN. Our strategy was to explore candidate materials in powder form first, and then study their behavior in thin films. Thin films of these materials were to be deposited on sapphire substrates using pulsed laser deposition (PLD) and metal organic vapor phase epitaxy (MOVPE). The photo- and cathode-luminescence measurements of these materials were used to investigate their suitability for white light generation. The project proceeded along this route with minor modifications needed to produce better materials and to expedite our progress towards the final goal. The project made the following accomplishments: (1) red emission from Eu{sup 3+}, green from Tb{sup 3+}, yellow from Dy{sup 3+} and blue from Tm{sup 3+} in AlN powders; (2) red emission from Eu{sup 3+} and green emission from Tb{sup 3+} in GaN powder; (3) red emission from Eu{sup 3+} in alloys of GaN and AlN; (4) green emission from Tb{sup 3+} in GaN thin films by PLD; (5) red emission from Eu{sup 3+} and Tb{sup 3+} in GaN thin films deposited by MOVPE; (6) energy transfer from host to RE{sup 3+}; (7) energy transfer from Tb{sup 3+} to Eu{sup 3+} in AlN powders; (8) emission from AlN powder samples

  18. Investigation of surface-plasmon coupled red light emitting InGaN/GaN multi-quantum well with Ag nanostructures coated on GaN surface

    SciTech Connect (OSTI)

    Li, Yi; Liu, Bin E-mail: rzhang@nju.edu.cn; Zhang, Rong E-mail: rzhang@nju.edu.cn; Xie, Zili; Zhuang, Zhe; Dai, JiangPing; Tao, Tao; Zhi, Ting; Zhang, Guogang; Chen, Peng; Ren, Fangfang; Zhao, Hong; Zheng, Youdou

    2015-04-21

    Surface-plasmon (SP) coupled red light emitting InGaN/GaN multiple quantum well (MQW) structure is fabricated and investigated. The centre wavelength of 5-period InGaN/GaN MQW structure is about 620?nm. The intensity of photoluminescence (PL) for InGaN QW with naked Ag nano-structures (NS) is only slightly increased due to the oxidation of Ag NS as compared to that for the InGaN QW. However, InGaN QW with Ag NS/SiO{sub 2} structure can evidently enhance the emission efficiency due to the elimination of surface oxide layer of Ag NS. With increasing the laser excitation power, the PL intensity is enhanced by 25%53% as compared to that for the SiO{sub 2} coating InGaN QW. The steady-state electric field distribution obtained by the three-dimensional finite-difference time-domain method is different for both structures. The proportion of the field distributed in the Ag NS for the GaN/Ag NS/SiO{sub 2} structure is smaller as compared to that for the GaN/naked Ag NS structure. As a result, the energy loss of localized SP modes for the GaN/naked Ag NS structure will be larger due to the absorption of Ag layer.

  19. Blue light emitting thiogallate phosphor

    DOE Patents [OSTI]

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  20. Broadband superluminescent diodes with bell-shaped spectra emitting in the range from 800 to 900 nm

    SciTech Connect (OSTI)

    Andreeva, E V; Il'ichenko, S N; Kostin, Yu O; Lapin, P I; Ladugin, M A; Marmalyuk, A A; Yakubovich, S D

    2013-08-31

    Quantum-well superluminescent diodes (SLD) with extremely thin active (AlGa)As and (InGa)As layers and centre wavelengths about 810, 840, 860 and 880 nm are experimentally studied. Their emission spectrum possesses the shape close to Gaussian, its FWHM being 30 – 60 nm depending on the length of the active channel and the level of pumping. Under cw injection, the output power of light-emitting modules based on such SLDs can amount to 1.0 – 25 mW at the output of a single-mode fibre. It is demonstrated that the operation lifetime of these devices exceeds 30000 hours. Based on the light-emitting modules the prototypes of combined BroadLighter series light sources are implemented having a bell-shaped spectrum with the width up to 100 nm. (optical radiation sources)

  1. U. S. Department of Energy to Invest up to $20.6 Million for...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    diodes (LEDs) and organic light-emitting diodes (OLEDs). Once used only for indicator lights (to illuminate the numbers on digital clocks and light up watches), LEDs are now found...

  2. New N-Type Polymers for Organic Photovoltaics: Cooperative Research and Development Final Report, CRADA Number CRD-06-177

    SciTech Connect (OSTI)

    Olson, D.

    2014-08-01

    This CRADA will develop improved thin film organic solar cells using a new n-type semiconducting polymer. High efficiency photovoltaics (PVs) based on inorganic semiconductors have good efficiencies (up to 30%) but are extremely expensive to manufacture. Organic PV technology has the potential to overcome this problem through the use of high-throughput production methods like reel-to-reel printing on flexible substrates. Unfortunately, today's best organic PVs have only a few percent efficiency, a number that is insufficient for virtually all commercial applications. The limited choice of stable n-type (acceptor) organic semiconductor materials is one of the key factors that prevent the further improvement of organic PVs. TDA Research, Inc. (TDA) previously developed a new class of electron-deficient (n-type) conjugated polymers for use in organic light emitting diodes (OLEDs). During this project TDA in collaboration with the National Renewable Energy Laboratory (NREL) will incorporate these electron-deficient polymers into organic photovoltaics and investigate their performance. TDA Research, Inc. (TDA) is developing new materials and polymers to improve the performance of organic solar cells. Materials being developed at TDA include spin coated transparent conductors, charge injection layers, fullerene derivatives, electron-deficient polymers, and three-phase (fullerene/polythiophene/dye) active layer inks.

  3. The potential of ill-nitride laser diodes for solid-state lighting [Advantages of III-Nitride Laser Diodes in Solid-State Lighting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wierer, Jonathan; Tsao, Jeffrey Y.

    2014-09-01

    III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from direct emitters is equally challenging for bothmore » LEDs and LDs, with neither source having a direct advantage. Lastly, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. These advantages make LDs a compelling source for future SSL.« less

  4. Red phosphor Ca{sub 2}Ge{sub 7}O{sub 16}:Eu{sup 3+} for potential application in field emission displays and white light-emitting diodes

    SciTech Connect (OSTI)

    Wang, Ting; Xu, Xuhui; Zhou, Dacheng; Qiu, Jianbei; Yu, Xue

    2014-12-15

    Abstract: A novel red emitting phosphor of Eu{sup 3+} doped Ca{sub 2}Ge{sub 7}O{sub 16} was prepared through the solid state reaction. The luminescence properties were studied in detail by photoluminescence excitation (PLE), emission (PL) spectra and cathodoluminescence (CL). Under the excitation of ultraviolet light, Ca{sub 2}Ge{sub 7}O{sub 16}:Eu{sup 3+} phosphor shows the characteristic {sup 5}D{sub 0}-{sup 7}F{sub J}(J = 1, 2, 3, 4) transition of Eu{sup 3+} with two different emissions due to the two kinds of Eu{sup 3+} ions. The luminescent intensity could be improved by co-doping with the charge compensators R{sup +} (Li, Na, K) which partially substitute for Ca{sup 2+} crystal sites. CL spectra show that Eu{sup 3+} ions were excited by the plasma produced by the incident electrons and the CL properties of Ca{sub 2}Ge{sub 7}O{sub 16}:Eu{sup 3+}, Li{sup +} as a function of accelerating voltage and probe current were investigated. Ca{sub 2}Ge{sub 7}O{sub 16}:Eu{sup 3+} phosphor offers higher thermal stability compared with the commercial red phosphor Y{sub 2}O{sub 3}:Eu{sup 3+}. The results indicate that Ca{sub 2}Ge{sub 7}O{sub 16}:Eu{sup 3+} can be a suitable red-emitting phosphor candidate for FEDs and w-LEDs.

  5. Synthesis and photoluminescence properties of Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14}:Sm{sup 3+} red phosphor for white light emitting diodes

    SciTech Connect (OSTI)

    Zhu, Ge; Ci, Zhipeng; Shi, Yurong; Wang, Yuhua

    2014-07-01

    Highlights: • A novel red phosphor Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14}:Sm{sup 3+} was synthesized and investigated firstly. • The structure and characteristic luminescence properties are discussed. • The excellent thermal stability was found and investigated. • It has good color saturation, the CIE is close to that of commercial Y{sub 2}O{sub 3}:Eu{sup 3+}. - Abstract: A series of Sm{sup 3+} doped Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14} red phosphors were successfully synthesized. X-ray diffraction analysis indicates that all the samples are single phased. The luminescence property is investigated in detail by measuring their photoluminescence excitation and emission spectra. Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14}:Sm{sup 3+} phosphors show strong absorption in 400–410 nm region, which is suitable for application in LEDs. When excited at 403 nm, Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14}:Sm{sup 3+} phosphor can emit red emission with CIE chromaticity coordinates (0.615, 0.384). The optimal doping concentration of Sm{sup 3+} doped Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14} is measured to be 0.02. The thermal quenching property is also measured and compared with the commercial red phosphor Y{sub 2}O{sub 3}:Eu{sup 3+} (Topstar, TXC-RIA). The results indicate Ca{sub 19}Mg{sub 2}(PO{sub 4}){sub 14}:Sm{sup 3+} phosphors have potential to serve as a red phosphor for white LEDs.

  6. Emission color-tuned light-emitting diode microarrays of nonpolar InxGa1–xN/GaN multishell nanotube heterostructures

    SciTech Connect (OSTI)

    Hong, Young Joon; Lee, Chul -Ho; Yoo, Jinkyoung; Kim, Yong -Jin; Jeong, Junseok; Kim, Miyoung; Yi, Gyu -Chul

    2015-12-09

    Integration of nanostructure lighting source arrays with well-defined emission wavelengths is of great importance for optoelectronic integrated monolithic circuitry. We report on the fabrication and optical properties of GaN-based p–n junction multishell nanotube microarrays with composition-modulated nonpolar m-plane InxGa1–xN/GaN multiple quantum wells (MQWs) integrated on c-sapphire or Si substrates. The emission wavelengths were controlled in the visible spectral range of green to violet by varying the indium mole fraction of the InxGa1–xN MQWs in the range 0.13 ≤ x ≤ 0.36. Homogeneous emission from the entire area of the nanotube LED arrays was achieved via the formation of MQWs with uniform QW widths and composition by heteroepitaxy on the well-ordered nanotube arrays. Importantly, the wavelength-invariant electroluminescence emission was observed above a turn-on of 3.0 V because both the quantum-confinement Stark effect and band filling were suppressed due to the lack of spontaneous inherent electric field in the m-plane nanotube nonpolar MQWs. Lastly, the method of fabricating the multishell nanotube LED microarrays with controlled emission colors has potential applications in monolithic nonpolar photonic and optoelectronic devices on commonly used c-sapphire and Si substrates.

  7. Text-Alternative Version: Challenges in OLED Research and Development

    Broader source: Energy.gov [DOE]

    Narrator: Organic light-emitting diodes, OLEDs, are made using organic carbon-based materials. Unlike LEDs, which are small point light sources, OLEDs are made in sheets that create diffuse area...

  8. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Applications Royer Michael P Tuttle Ralph Rosenfeld Scott M Miller Naomi J Light emitting diode LED color shift color stability color maintenance warranty Light emitting diode...

  9. Spectroscopy of Charge Carriers and Traps in Field-Doped Single Crystal Organic Semiconductors

    SciTech Connect (OSTI)

    Zhu, Xiaoyang

    2014-12-10

    The proposed research aims to achieve quantitative, molecular level understanding of charge carriers and traps in field-doped crystalline organic semiconductors via in situ linear and nonlinear optical spectroscopy, in conjunction with transport measurements and molecular/crystal engineering. Organic semiconductors are emerging as viable materials for low-cost electronics and optoelectronics, such as organic photovoltaics (OPV), organic field effect transistors (OFETs), and organic light emitting diodes (OLEDs). Despite extensive studies spanning many decades, a clear understanding of the nature of charge carriers in organic semiconductors is still lacking. It is generally appreciated that polaron formation and charge carrier trapping are two hallmarks associated with electrical transport in organic semiconductors; the former results from the low dielectric constants and weak intermolecular electronic overlap while the latter can be attributed to the prevalence of structural disorder. These properties have lead to the common observation of low charge carrier mobilities, e.g., in the range of 10-5 - 10-3 cm2/Vs, particularly at low carrier concentrations. However, there is also growing evidence that charge carrier mobility approaching those of inorganic semiconductors and metals can exist in some crystalline organic semiconductors, such as pentacene, tetracene and rubrene. A particularly striking example is single crystal rubrene (Figure 1), in which hole mobilities well above 10 cm2/Vs have been observed in OFETs operating at room temperature. Temperature dependent transport and spectroscopic measurements both revealed evidence of free carriers in rubrene. Outstanding questions are: what are the structural features and physical properties that make rubrene so unique? How do we establish fundamental design principles for the development of other organic semiconductors of high mobility? These questions are critically important but not comprehensive, as the nature of

  10. In the OSTI Collections: LEDs | OSTI, US Dept of Energy Office of

    Office of Scientific and Technical Information (OSTI)

    Scientific and Technical Information LEDs User experiences Light-emitting diodes and phosphors Electronics to drive light-emitting diodes Getting the light out of the diode and onto where it's wanted Environmental effects References Research Organizations Patent Assignees Reports Available through OSTI's SciTech Connect Reports Available through OSTI's DOepatents Additional References As "efficiency" is often defined for technology, the efficiency of anything that changes energy

  11. Blue light emitting SrSn(OH){sub 6} nano-rods doped with lanthanide ions (Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+})

    SciTech Connect (OSTI)

    Patel, D.K.; Nuwad, J.; Rajeswari, B.; Vishwanadh, B.; Sudarsan, V.; Vatsa, R.K.; Kadam, R.M.; Pillai, C.G.S.; Kulshreshtha, S.K.

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ? Room temperature synthesis of blue light emitting SrSn(OH){sub 6} nano-rods. ? Blue light emission originates from the recombination of self trapped excitons. ? There exists energy transfer from host to lanthanide ions in SrSn(OH){sub 6}:Ln nano-rods. ? Solubility of Eu{sup 3+} ions in SrSn(OH){sub 6} nano-rods is around 1.5 at%. -- Abstract: Blue light emitting SrSn(OH){sub 6} nano-rods were prepared in aqueous medium at room temperature. Presence of lanthanide ions in reaction medium during synthesis of nano-rods, leads to significant changes in the morphology of the nano-rods. Based on luminescence studies emission in the blue region from SrSn(OH){sub 6} nano-rods has been attributed to radiative recombination of self trapped excitons in the lattice. SrSn(OH){sub 6} nano-rods were doped with lanthanide ions like Eu{sup 3+}, Tb{sup 3+} and Dy{sup 3+} and their luminescence studies revealed that there exists energy transfer from host to lanthanide ions. From the luminescence studies on Eu{sup 3+} doped samples, it is confirmed that up to 1.5 at%, Eu{sup 3+} ions get incorporated at Sr{sup 2+} site in SrSn(OH){sub 6} lattice and beyond which a separate Eu{sup 3+} containing phase is formed. Part of the europium ions also exists as Eu{sup 2+} species in the lattice as confirmed by electron paramagnetic resonance (EPR) studies.

  12. Webinar: OLED Lighting Products—Capabilities, Challenges, Potential

    Broader source: Energy.gov [DOE]

    Organic light-emitting diodes are a solid-state technology that is entering the architectural lighting marketplace and experiencing some of the same issues that LEDs encountered a few years ago....

  13. CX-010823: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Manufacturing Process for Organic Light-Emitting Diode (OLED) Integrated Substrate CX(s) Applied: B3.6 Date: 07/30/2013 Location(s): Pennsylvania Offices(s): National Energy Technology Laboratory

  14. CX-010822: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Manufacturing Process for Organic Light-Emitting Diode (OLED) Integrated Substrate CX(s) Applied: B3.6 Date: 07/30/2013 Location(s): Illinois Offices(s): National Energy Technology Laboratory

  15. CX-010821: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Manufacturing Process for Organic Light-Emitting Diode (OLED) Integrated Substrate CX(s) Applied: B3.6 Date: 07/30/2013 Location(s): Pennsylvania Offices(s): National Energy Technology Laboratory

  16. CX-010824: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Manufacturing Process for Organic Light-Emitting Diode (OLED) Integrated Substrate CX(s) Applied: B3.6 Date: 07/30/2013 Location(s): New Jersey Offices(s): National Energy Technology Laboratory

  17. CX-001153: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Roll-to-Roll Solution-Processable Small-Molecule Organic Light-Emitting Diodes (Wilmington) Date: 03/11/2010Location(s): Wilmington, DelawareOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  18. CX-004127: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Energy Saving Phosphorescent Organic Light Emitting Diode (OLED) LuminairesCX(s) Applied: B3.6, B5.1Date: 09/14/2010Location(s): Ewing, New JerseyOffice(s): Energy Efficiency and Renewable Energy

  19. Phosphor suspended in silicone, molded/formed and used in a remote phosphor configuration

    DOE Patents [OSTI]

    Kolodin, Boris; Deshpande, Anirudha R

    2014-09-16

    A light emitting package comprising a support hosting at least one light emitting diode. A light transmissive dome comprised of a silicone including a phosphor material positioned to receive light emitted by the diode. A glass cap overlies said dome.

  20. Organic Solid State Lighting | MIT-Harvard Center for Excitonics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Solid State Lighting March 15, 2011 at 3pm/36-428 Paul E. Burrows Reata Research burrows.p abstract: Many scientific papers and presentations in the field of organic electronic materials have kicked off with bold statements implying a route to low cost, large area manufacturing. Organic solid state lighting has recently become feasible due to dramatic improvements in the efficiency and operating lifetime of organic light emitting devices (OLEDs) and, again, dramatic visions of efficient, large

  1. Photonic Systems | The Ames Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Photonic Systems Research Personnel Updates Publications Dramatic Efficiency Improvements for Organic Light Emitting Diodes Read More Standing Ribbons on Edge Leads to Transparent Triumph Read More Illuminating the Deep-Blue UV Read More Previous Pause Next Synthesis Since ~1990, the Ames Laboratory has conducted pioneering development and studies of 3D photonic crystals (PCs), developed forefront organic light-emitting diodes (OLEDs) and procedures for characterizing them, and conducted

  2. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  3. Hybrid electroluminescent devices

    DOE Patents [OSTI]

    Shiang, Joseph John; Duggal, Anil Raj; Michael, Joseph Darryl

    2010-08-03

    A hybrid electroluminescent (EL) device comprises at least one inorganic diode element and at least one organic EL element that are electrically connected in series. The absolute value of the breakdown voltage of the inorganic diode element is greater than the absolute value of the maximum reverse bias voltage across the series. The inorganic diode element can be a power diode, a Schottky barrier diode, or a light-emitting diode.

  4. Secretary Chu Announces More than $37 Million for Next Generation Lighting

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    | Department of Energy 37 Million for Next Generation Lighting Secretary Chu Announces More than $37 Million for Next Generation Lighting January 15, 2010 - 12:00am Addthis WASHINGTON, DC - Energy Secretary Steven Chu today announced more than $37 million in funding from the American Recovery and Reinvestment Act to support high-efficiency solid-state lighting projects. Solid-state lighting, which uses light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) instead of

  5. Color Maintenance of LEDs in Laboratory and Field Applications...

    Office of Scientific and Technical Information (OSTI)

    Royer, Michael P.; Tuttle, Ralph; Rosenfeld, Scott M.; Miller, Naomi J. Light-emitting diode (LED), color shift, color stability, color maintenance, warranty Light-emitting...

  6. Ultra-high Charge Carrier Mobility in an Organic Semiconductor by Vertical

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Chain Alignment | Stanford Synchrotron Radiation Lightsource Ultra-high Charge Carrier Mobility in an Organic Semiconductor by Vertical Chain Alignment Thursday, March 31, 2016 The control of the electronic and optical properties of conjugated polymer thin films is of great interest for building more efficient solution processed organic electronic devices, e.g. photovoltaic (OPV) and light emitting (OLED) devices. The crystallinity and the chain orientation in the polymer film has been shown

  7. Electronic and chemical structure of an organic light emitter embedded in an inorganic wide-bandgap semiconductor: Photoelectron spectroscopy of layered and composite structures of Ir(BPA) and ZnSe

    SciTech Connect (OSTI)

    Dimamay, Mariel; Mayer, Thomas; Jaegermann, Wolfram; Hadziioannou, Georges

    2015-05-07

    Luminescent organic phases embedded in conductive inorganic matrices are proposed for hybrid organic-inorganic light-emitting diodes. In this configuration, the organic dye acts as the radiative recombination site for charge carriers injected into the inorganic matrix. Our investigation is aimed at finding a material combination where the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the organic dye are situated in between the valence and conduction bands of the inorganic matrix in order to promote electron and hole transfer from the matrix to the dye. Bilayer and composite thin films of zinc selenide (ZnSe) and a red iridium complex (Ir(BPA)) organic light emitter were prepared in situ via UHV thermal evaporation technique. The electronic and atomic structures were studied applying X-ray and ultraviolet photoelectron spectroscopies. The measured energy band alignments for the ZnSe/Ir(BPA) bilayer and ZnSe+Ir(BPA) composite reveal that the HOMO and LUMO of the organic dye are positioned in the ZnSe bandgap. For the initial steps of ZnSe deposition on a dye film to form Ir(BPA)/ZnSe bilayers, zinc atoms intercalate into the dye film leaving behind an excess of selenium at the interface that partly reacts with dye molecules. Photoelectron spectroscopy of the composites shows the same species suggesting a similar mechanism. This mechanism leads to composite films with increased content of amorphous phases in the inorganic matrix, thereby affecting its conductivity, as well as to the presence of nonradiative recombination sites provided by the intercalated Zn atoms.

  8. Mechanistic Studies of Charge Injection from Metallic Electrodes into Organic Semiconductors Mediated by Ionic Functionalities: Final Report

    SciTech Connect (OSTI)

    Nguyen, Thuc-Quyen; Bazan, Guillermo; Mikhailovsky, Alexander

    2014-04-15

    Metal-organic semiconductor interfaces are important because of their ubiquitous role in determining the performance of modern electronics such as organic light emitting diodes (OLEDs), fuel cells, batteries, field effect transistors (FETs), and organic solar cells. Interfaces between metal electrodes required for external wiring to the device and underlying organic structures directly affect the charge carrier injection/collection efficiency in organic-based electronic devices primarily due to the mismatch between energy levels in the metal and organic semiconductor. Environmentally stable and cost-effective electrode materials, such as aluminum and gold typically exhibit high potential barriers for charge carriers injection into organic devices leading to increased operational voltages in OLEDs and FETs and reduced charge extraction in photovoltaic devices. This leads to increased power consumption by the device, reduced overall efficiency, and decreased operational lifetime. These factors represent a significant obstacle for development of next generation of cheap and energy-efficient components based on organic semiconductors. It has been noticed that introduction of organic materials with conjugated backbone and ionic pendant groups known as conjugated poly- and oligoelectrolytes (CPEs and COEs), enables one to reduce the potential barriers at the metal-organic interface and achieve more efficient operation of a device, however exact mechanisms of the phenomenon have not been understood. The goal of this project was to delineate the function of organic semiconductors with ionic groups as electron injection layers. The research incorporated a multidisciplinary approach that encompassed the creation of new materials, novel processing techniques, examination of fundamental electronic properties and the incorporation of the resulting knowledgebase into development of novel organic electronic devices with increased efficiency, environmental stability, and reduced

  9. Quaternary InGaAsSb Thermophotovoltaic Diodes

    SciTech Connect (OSTI)

    MW Dashiell; JF Beausang; H Ehsani; GJ Nichols; DM Depoy; LR Danielson; P Talamo; KD Rahner; EJ Brown; SR Burger; PM Foruspring; WF Topper; PF Baldasaro; CA Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; J Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryi

    2006-03-09

    In{sub x}Ga{sub 1-x}As{sub y}Sb{sub 1-y} thermophotovoltaic (TPV) diodes were grown lattice-matched to GaSb substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) in the bandgap range of E{sub G} = 0.5 to 0.6eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density of {eta}{sub TPV} = 19.7% and PD =0.58 W/cm{sup 2} respectively for a radiator temperature of T{sub radiator} = 950 C, diode temperature of T{sub diode} = 27 C, and diode bandgap of E{sub G} = 0.53eV. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters, which for 0.53eV InGaAsSb TPV energy conversion is {eta}{sub TPV} = 28% and PD = 0.85W/cm{sup 2} at the above operating temperatures. The most severe performance limits are imposed by (1) diode open-circuit voltage (VOC) limits due to intrinsic Auger recombination and (2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode V{sub OC} is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance vs. diode architecture indicate that the V{sub OC} and thus efficiency is limited by extrinsic recombination processes such as through bulk defects.

  10. Analysis of carrier transport and carrier trapping in organic diodes with polyimide-6,13-Bis(triisopropylsilylethynyl)pentacene double-layer by charge modulation spectroscopy and optical second harmonic generation measurement

    SciTech Connect (OSTI)

    Lim, Eunju E-mail: taguchi.d.aa@m.titech.ac.jp; Taguchi, Dai E-mail: taguchi.d.aa@m.titech.ac.jp Iwamoto, Mitsumasa E-mail: taguchi.d.aa@m.titech.ac.jp

    2014-08-18

    We studied the carrier transport and carrier trapping in indium tin oxide/polyimide (PI)/6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene)/Au diodes by using charge modulation spectroscopy (CMS) and time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurements. TR-EFISHG directly probes the spatial carrier behaviors in the diodes, and CMS is useful in explaining the carrier motion with respect to energy. The results clearly indicate that the injected carriers move across TIPS-pentacene thorough the molecular energy states of TIPS-pentacene and accumulate at the PI/TIPS-pentacene interface. However, some carriers are trapped in the PI layers. These findings take into account the capacitance-voltage and current-voltage characteristics of the diodes.

  11. Energy Department Offers $10 Million for Energy-Saving Lighting

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Technologies | Department of Energy Offers $10 Million for Energy-Saving Lighting Technologies Energy Department Offers $10 Million for Energy-Saving Lighting Technologies December 11, 2013 - 12:00am Addthis The Energy Department on December 6 announced nearly $10 million to support U.S. research, development, and manufacturing of solid-state lighting (SSL) technologies. This funding will help accelerate the development of high-quality light-emitting diode (LED) and organic light-emitting

  12. Emitron: microwave diode

    DOE Patents [OSTI]

    Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

    1982-05-06

    The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

  13. Enhanced vbasis laser diode package

    DOE Patents [OSTI]

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  14. The FY 2008 Budget Request - Twenty in Ten: Strengthening America...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... processing of lightweight structural ... hydrogen storage materials research and engineering science; demonstrate ... and inorganic light emitting diodes ...

  15. CALiPER Benchmark Report: Performance of Halogen Incandescent MR16 Lamps and LED Replacement

    SciTech Connect (OSTI)

    Paget, M. L.; Lingard, R. D.; Myer, M. A.

    2008-11-01

    This benchmark report addresses the halogen MR16 lamp and its commercially available light-emitting diode (LED) replacements.

  16. diod - distributed I/O daemon

    Energy Science and Technology Software Center (OSTI)

    2010-01-29

    diod is an I/O forwarding daemon used to improve scalability of file systems on large Linux clusters.

  17. Method of making diode structures

    DOE Patents [OSTI]

    Compaan, Alvin D.; Gupta, Akhlesh

    2006-11-28

    A method of making a diode structure includes the step of depositing a transparent electrode layer of any one or more of the group ZnO, ZnS and CdO onto a substrate layer, and depositing an active semiconductor junction having an n-type layer and a p-type layer onto the transparent electrode layer under process conditions that avoid substantial degradation of the electrode layer. A back electrode coating layer is applied to form a diode structure.

  18. Apply: Solid-State Lighting Advanced Technology R&D - 2014

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (DE-FOA-0000973) | Department of Energy Apply: Solid-State Lighting Advanced Technology R&D - 2014 (DE-FOA-0000973) Apply: Solid-State Lighting Advanced Technology R&D - 2014 (DE-FOA-0000973) December 6, 2013 - 4:27pm Addthis This funding opportunity is closed. Through research and development of solid-state lighting (SSL),including both light-emitting diode (LED) and organic light emitting diode (OLED) technologies, the objectives of this opportunity are to: Maximize the

  19. Light emitting device comprising phosphorescent materials for white light generation

    DOE Patents [OSTI]

    Thompson, Mark E.; Dapkus, P. Daniel

    2014-07-22

    The present invention relates to phosphors for energy downconversion of high energy light to generate a broadband light spectrum, which emit light of different emission wavelengths.

  20. Visible light emitting vertical cavity surface emitting lasers

    DOE Patents [OSTI]

    Bryan, Robert P. (Boulder, CO); Olbright, Gregory R. (Boulder, CO); Lott, James A. (Albuquerque, NM); Schneider, Jr., Richard P. (Albuquerque, NM)

    1995-01-01

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of .lambda./2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In.sub.z (Al.sub.y Ga.sub.1-y).sub.1-z P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m .lambda./2n.sub.eff where m is an integer and n.sub.eff is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of .lambda./n, typically within the green to red portion of the visible spectrum.

  1. Visible light emitting vertical cavity surface emitting lasers

    DOE Patents [OSTI]

    Bryan, R.P.; Olbright, G.R.; Lott, J.A.; Schneider, R.P. Jr.

    1995-06-27

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of {lambda}/2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In{sub z}(Al{sub y}Ga{sub 1{minus}y}){sub 1{minus}z}P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m {lambda}/2n{sub eff} where m is an integer and n{sub eff} is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of {lambda}/n, typically within the green to red portion of the visible spectrum. 10 figs.

  2. Quaternary InGaAsSb Thermophotovoltaic Diode Technology

    SciTech Connect (OSTI)

    M Dashiell; J Beausang; H Ehsani; G Nichols; D DePoy; L Danielson; P Talamo; K Rahner; E Brown; S Burger; P Fourspring; W Topper; P Baldasaro; C Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; Jizhong Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryl

    2005-01-26

    Thermophotovoltaic (TPV) diodes fabricated from InGaAsSb alloys lattice-matched to GaSb substrates are grown by Metal Organic Vapor Phase Epitaxy (MOVPE). 0.53eV InGaAsSb TPV diodes utilizing front-surface spectral control filters have been tested in a vacuum cavity and a TPV thermal-to-electric conversion efficiency ({eta}{sub TPV}) and a power density (PD) of {eta}{sub TPV} = 19% and PD=0.58 W/cm{sup 2} were measured for T{sub radiator} = 950 C and T{sub diode} = 27 C. Recombination coefficients deduced from minority carrier measurements and the theory reviewed in this article predict a practical limit to the maximum achievable conversion efficiency and power density for 0.53eV InGaAsSb TPV. The limits for the above operating temperatures are projected to be {eta}{sub TPV} = 26% and PD = 0.75 W/cm{sup 2}. These limits are extended to {eta}{sub TPV} = 30% and PD = 0.85W/cm{sup 2} if the diode active region is bounded by a reflective back surface to enable photon recycling and a two-pass optical path length. The internal quantum efficiency of the InGaAsSb TPV diode is close to the theoretically predicted limits, with the exception of short wavelength absorption in GaSb contact layers. Experiments show that the open circuit voltage of the 0.53eV InGaAsSb TPV diodes is not strongly dependent on the device architectures studied in this work where both N/P and P/N double heterostructure diodes have been grown with various acceptor and donor doping levels, having GaSb and AlGaAsSb confinement, and also partial back surface reflectors. Lattice matched InGaAsSb TPV diodes were fabricated with bandgaps ranging from 0.6 to 0.5eV without significant degradation of the open circuit voltage factor, quantum efficiency, or fill factor as the composition approached the miscibility gap. The key diode performance parameter which is limiting efficiency and power density below the theoretical limits in InGaAsSb TPV devices is the open circuit voltage. The open circuit voltages of

  3. Light source comprising a common substrate, a first led device and a second led device

    DOE Patents [OSTI]

    Choong, Vi-En

    2010-02-23

    At least one stacked organic or polymeric light emitting diode (PLEDs) devices to comprise a light source is disclosed. At least one of the PLEDs includes a patterned cathode which has regions which transmit light. The patterned cathodes enable light emission from the PLEDs to combine together. The light source may be top or bottom emitting or both.

  4. CX-001310: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Low-Cost Integrated Substrate for Organic Light-Emitting Diode (OLED) Lighting (Ewing)CX(s) Applied: B3.6Date: 03/19/2010Location(s): Ewing, New JerseyOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  5. Research Highlights 2007-2008

    Office of Energy Efficiency and Renewable Energy (EERE)

    Universal Display Corporation has successfully demonstrated an all phosphorescent white organic light emitting diode (WOLED™) with a record power efficacy of 45 lm/W at 1,000 cd/m2. This high-efficacy device was enabled by lowering the device operating voltage, increasing the outcoupling efficiency, and incorporating highly efficient phosphorescent emitters. (June 2007) Learn more.

  6. CX-001308: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Low-Cost Integrated Substrate for Organic Light-Emitting Diode (OLED) Lighting (Allison Park)CX(s) Applied: A2, A9Date: 03/19/2010Location(s): Allison Park, PennsylvaniaOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  7. CX-001309: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Low-Cost Integrated Substrate for Organic Light-Emitting Diode (OLED) Lighting (Monroeville)CX(s) Applied: B3.6Date: 03/19/2010Location(s): Monroeville, PennsylvaniaOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  8. CX-001035: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Solution Processable Transparent Conductive Hole Injection Electrode for Organic Light Emitting Diode (OLED) Solid State LightingCX(s) Applied: B3.6Date: 03/02/2010Location(s): Sunnyvale, CaliforniaOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  9. CX-001307: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Low-Cost Integrated Substrate for Organic Light-Emitting Diode (OLED) Lighting (Harmar)CX(s) Applied: B3.6Date: 03/19/2010Location(s): Harmar, PennsylvaniaOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  10. CX-001152: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Roll-to-Roll Solution-Processable Small-Molecule Organic Light-Emitting Diodes (Niskayuna)CX(s) Applied: B3.6Date: 03/11/2010Location(s): Niskayuna, New YorkOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  11. CX-001036: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Solution Processable Transparent Conductive Hole Injection Electrode for Organic Light Emitting Diode (OLED) Solid State Lighting (Pennsylvania)CX(s) Applied: B3.6Date: 03/02/2010Location(s): Pittsburgh, PennsylvaniaOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  12. Progress in semiconductor laser diodes: SPIE volume 723

    SciTech Connect (OSTI)

    Eichen, E.

    1987-01-01

    This book contains proceedings arranged under the following session headings: High power diode lasers; single emitters and arrays; Ultrahigh speed modulation of semiconductor diode lasers; Coherence and linewidth stabilized semiconductor lasers; and Growth, fabrication, and evaluation of laser diodes.

  13. Photovoltaic power generation system free of bypass diodes (Patent...

    Office of Scientific and Technical Information (OSTI)

    Photovoltaic power generation system free of bypass diodes Title: Photovoltaic power generation system free of bypass diodes A photovoltaic power generation system that includes a ...

  14. Semiconductor diode with external field modulation

    DOE Patents [OSTI]

    Nasby, Robert D.

    2000-01-01

    A non-destructive-readout nonvolatile semiconductor diode switching device that may be used as a memory element is disclosed. The diode switching device is formed with a ferroelectric material disposed above a rectifying junction to control the conduction characteristics therein by means of a remanent polarization. The invention may be used for the formation of integrated circuit memories for the storage of information.

  15. Photochemical deterioration of the organic/metal contacts in organic optoelectronic devices

    SciTech Connect (OSTI)

    Wang Qi; Williams, Graeme; Aziz, Hany; Tsui Ting

    2012-09-15

    We study the effect of exposure to light on a wide range of organic/metal contacts that are commonly used in organic optoelectronic devices and found that irradiation by light in the visible and UV range results in a gradual deterioration in their electrical properties. This photo-induced contact degradation reduces both charge injection (i.e., from the metal to the organic layer) and charge extraction (i.e., from the organic layer to the metal). X-ray photoelectron spectroscopy (XPS) measurements reveal detectable changes in the interface characteristics after irradiation, indicating that the photo-degradation is chemical in nature. Changes in XPS characteristics after irradiation suggests a possible reduction in bonds associated with organic-metal complexes. Measurements of interfacial adhesion strength using the four-point flexure technique reveal a decrease in organic/metal adhesion in irradiated samples, consistent with a decrease in metal-organic bond density. The results shed the light on a new material degradation mechanism that appears to have a wide presence in organic/metal interfaces in general, and which likely plays a key role in limiting the stability of various organic optoelectronic devices such as organic light emitting devices, organic solar cells, and organic photo-detectors.

  16. Laser diode package with enhanced cooling

    DOE Patents [OSTI]

    Deri, Robert J.; Kotovsky, Jack; Spadaccini, Christopher M.

    2012-06-12

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  17. Laser diode package with enhanced cooling

    DOE Patents [OSTI]

    Deri, Robert J.; Kotovsky, Jack; Spadaccini, Christopher M.

    2011-09-13

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  18. Laser diode package with enhanced cooling

    DOE Patents [OSTI]

    Deri, Robert J.; Kotovsky, Jack; Spadaccini, Christopher M.

    2012-06-26

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  19. Fused thiophene-based conjugated polymers and their use in optoelectronic devices

    SciTech Connect (OSTI)

    Facchetti, Antonio; Marks, Tobin J; Takai, Atsuro; Seger, Mark; Chen, Zhihua

    2015-11-03

    The present teachings relate to certain polymeric compounds and their use as organic semiconductors in organic and hybrid optical, optoelectronic, and/or electronic devices such as photovoltaic cells, light emitting diodes, light emitting transistors, and field effect transistors. The disclosed compounds can provide improved device performance, for example, as measured by power conversion efficiency, fill factor, open circuit voltage, field-effect mobility, on/off current ratios, and/or air stability when used in photovoltaic cells or transistors. The disclosed compounds can have good solubility in common solvents enabling device fabrication via solution processes.

  20. Bilayer avalanche spin-diode logic

    SciTech Connect (OSTI)

    Friedman, Joseph S. Querlioz, Damien; Fadel, Eric R.; Wessels, Bruce W.; Sahakian, Alan V.

    2015-11-15

    A novel spintronic computing paradigm is proposed and analyzed in which InSb p-n bilayer avalanche spin-diodes are cascaded to efficiently perform complex logic operations. This spin-diode logic family uses control wires to generate magnetic fields that modulate the resistance of the spin-diodes, and currents through these devices control the resistance of cascaded devices. Electromagnetic simulations are performed to demonstrate the cascading mechanism, and guidelines are provided for the development of this innovative computing technology. This cascading scheme permits compact logic circuits with switching speeds determined by electromagnetic wave propagation rather than electron motion, enabling high-performance spintronic computing.

  1. Arbitrary waveform generator to improve laser diode driver performance

    DOE Patents [OSTI]

    Fulkerson, Jr, Edward Steven

    2015-11-03

    An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.

  2. Bypass diode for a solar cell

    DOE Patents [OSTI]

    Rim, Seung Bum; Kim, Taeseok; Smith, David D.; Cousins, Peter J.

    2012-03-13

    Bypass diodes for solar cells are described. In one embodiment, a bypass diode for a solar cell includes a substrate of the solar cell. A first conductive region is disposed above the substrate, the first conductive region of a first conductivity type. A second conductive region is disposed on the first conductive region, the second conductive region of a second conductivity type opposite the first conductivity type.

  3. Stacked Switchable Element and Diode Combination

    DOE Patents [OSTI]

    Branz, H. M.; Wang, Q.

    2006-06-27

    A device (10) comprises a semiconductor diode (12) and a switchable element (14) positioned in stacked adjacent relationship so that the semiconductor diode (12) and the switchable element (14) are electrically connected in series with one another. The switchable element (14) is switchable from a low-conductance state to a high-conductance state in response to the application of a forming voltage to the switchable element (14).

  4. Stacked switchable element and diode combination

    DOE Patents [OSTI]

    Branz, Howard M.; Wang, Qi

    2006-06-27

    A device (10) comprises a semiconductor diode (12) and a switchable element (14) positioned in stacked adjacent relationship so that the semiconductor diode (12) and the switchable element (14) are electrically connected in series with one another. The switchable element (14) is switchable from a low-conductance state to a high-conductance state in response to the application of a forming voltage to the switchable element (14).

  5. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  6. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  7. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  8. The Role of Intermolecular Coupling in the Photophysics of Disordered

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Organic Semiconductors | MIT-Harvard Center for Excitonics Role of Intermolecular Coupling in the Photophysics of Disordered Organic Semiconductors October 6, 2009 at 3pm/36-428 Frank Spano Department of Chemistry, Temple University spano abstract: Electronic excitations in aggregates, thin films and crystals of conjugated organic molecules play a fundamental role in the operation of a wide array of organic-based devices including solar cells, transistors and light-emitting diodes. Optical

  9. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  10. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  11. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  12. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  13. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  14. Electrodes mitigating effects of defects in organic electronic devices

    DOE Patents [OSTI]

    Heller, Christian Maria Anton

    2008-05-06

    A compound electrode for organic electronic devices comprises a thin first layer of a first electrically conducting material and a second electrically conducting material disposed on the first layer. In one embodiment, the second electrically conducting material is formed into a plurality of elongated members. In another embodiment, the second material is formed into a second layer. The elongated members or the second layer has a thickness greater than that of the first layer. The second layer is separated from the first layer by a conducting material having conductivity less than at least the material of the first layer. The compound electrode is capable of mitigating adverse effects of defects, such as short circuits, in the construction of the organic electronic devices, and can be included in light-emitting or photovoltaic devices.

  15. Energy Department Invests More Than $10 Million in Efficient Lighting R&D |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy More Than $10 Million in Efficient Lighting R&D Energy Department Invests More Than $10 Million in Efficient Lighting R&D June 13, 2014 - 8:29am Addthis The Energy Department today announced nine research and development projects that will receive funding to support solid-state lighting (SSL) core technology research and product development. The projects will help accelerate the development of high-quality light-emitting diode (LED) and organic light-emitting

  16. Series connected OLED structure and fabrication method

    DOE Patents [OSTI]

    Foust, Donald Franklin; Balch, Ernest Wayne; Duggal, Anil Raj; Heller, Christian Maria; Guida, Renato; Nealon, William Francis; Faircloth, Tami Janene

    2006-05-23

    A light emitting device comprises a plurality of organic light emitting diode (OLED) modules. The OLED modules are arranged into a series group where the individual OLED modules are electrically connected in series. The device is configured to be coupled to a power supply. A display is also provided. The display includes a plurality of OLED modules arranged to depict a shape selected from the group consisting of at least one letter, at least one number, at least one image, and a combination thereof.

  17. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    SciTech Connect (OSTI)

    Chang-Hwan Kim

    2003-12-12

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

  18. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print Wednesday, 31 October 2012 00:00 The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film

  19. Integrated injection-locked semiconductor diode laser

    DOE Patents [OSTI]

    Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1991-01-01

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

  20. Integrated injection-locked semiconductor diode laser

    DOE Patents [OSTI]

    Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

    1991-02-19

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

  1. Tunable, diode side-pumped Er: YAG laser

    DOE Patents [OSTI]

    Hamilton, Charles E.; Furu, Laurence H.

    1997-01-01

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 .mu.m, and is tunable over a 6 nm range near about 2.936 .mu.m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 .mu.m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 .mu.m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems.

  2. Tunable, diode side-pumped Er:YAG laser

    DOE Patents [OSTI]

    Hamilton, C.E.; Furu, L.H.

    1997-04-22

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.

  3. CX-002915: Categorical Exclusion Determination | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    LED (light-emitting diode) lights, 4) install fuel cellengine hybrid power and microgrid for city E911emergency cooling center, and 5) technical consultant to enhance...

  4. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Energy Technology Engineering Center (ETEC), Canoga ... in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes. ... Mechanical properties of water-assembled graphene oxide ...

  5. News | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    to operate. Business owners have long recognized the potential of light-emitting diode (LED) technology in parking lot lighting-to save energy, reduce maintenance costs, and...

  6. Fabrication of Emissible Metallic Layer-by-Layer Photonic Crystals...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    lighting technologies, such as compact fluorescent bulbs or light-emitting diodes (LEDs) have gained increasing interest with energy security becoming an important national...

  7. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Idaho National Laboratory Specific Manufacturing Plant Idaho National Laboratory, Idaho ... important in energy devices such as solar cells and light-emitting diodes, but the ...

  8. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    gateway, caliper, report, color, shift, maintenance (1) light-emitting diode (led), color shift, color stability, color maintenance, warranty (1) Filter by Author Tuttle, Ralph ...

  9. Solid-State Lighting Consortia | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Solid-State Lighting Consortia Solid-State Lighting Consortia Presenter: Marc Ledbetter, Pacific Northwest National Laboratory Most potential users of light-emitting diode (LED) ...

  10. DOE Solid-State Lighting Program: Modest Investments, Extraordinary...

    Energy Savers [EERE]

    Modest Investments, Extraordinary Impacts DOE Solid-State Lighting Program Shaping the Future of Solid-State Lighting Today, LED (light-emitting diode) technologies illuminate ...

  11. Wireless Environment LLC | Open Energy Information

    Open Energy Info (EERE)

    Wireless Environment LLC Jump to: navigation, search Name: Wireless Environment LLC Place: Elyria, Ohio Product: Wireless Environment designs light-emitting diode lighting products...

  12. CALiPER Benchmark Report: Performance of Incandescent A Type and Decorative Lamps and LED Replacements

    SciTech Connect (OSTI)

    Lingard, R. D.; Myer, M. A.; Paget, M. L.

    2008-11-01

    This benchmark report addresses common omnidirectional incandescent lamps - A-type and small decorative, candelabra-type lamps - and their commercially available light-emitting diode (LED) replacements.

  13. SANDIA NATIONAL LABORATORIES

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    light- emitting diode (LED), a cell membrane, a NISAC model, synthetic aperture radar ... For cells utilize protein water- channels (aquaporins) that can likely teach membrane ...

  14. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Demonstration Assessment of Light Emitting Diode Parking Structure Lighting at U S Department of Labor Headquarters Kinzey Bruce R Myer Michael solid state lighting LEDs occupancy...

  15. DOE Announces Winners of Lighting for Tomorrow 2010 Competition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    2004. This year, the SSL competition was expanded beyond fixtures to include light-emitting diode (LED) replacement bulbs as well as lighting control devices that are compatible...

  16. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    Northwest National Laboratory (PNNL), Richland, WA (US)","USDOE","Light-emitting diode (LED), color shift, color stability, color maintenance, warranty",,"Synopsis:...

  17. Types of Lighting | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    selection. Types of lighting include: Fluorescent Incandescent Outdoor solar Light-emitting diode (LED) Also learn how energy-efficient lightbulbs compare to traditional...

  18. Lighting Controls | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    fluorescent lighting fixtures rather than replace them. Dimmers and LEDs Some light-emitting diode (LED) lightbulbs can be used with dimmers. LED bulbs and fixtures must be...

  19. UCSB researchers uncover fundamental limits on optical transparency...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a wide range of optoelectronic devices, such as solar cells, light-emitting diodes, and LCD touch screens. These materials can conduct electricity while being transparent to...

  20. Fulham Company Inc | Open Energy Information

    Open Energy Info (EERE)

    California-based manufacturer and seller of electronic ballasts for fluorescent, high intensity, and light emitting diode lights. Coordinates: 41.097398, -73.794711 Show Map...

  1. Life-Cycle Assessment of Energy and Environmental Impacts of...

    Office of Scientific and Technical Information (OSTI)

    Hollomon, Brad; Dillon, Heather E.; Snowden-Swan, Lesley J. LED; light-emitting diode; CFL; incandescent; halogen; lamp; bulb; TCLP; STLC; TTLC; WET; hazardous waste; electronic...

  2. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    National Laboratory (PNNL), Richland, WA (US)","USDOE","LED; light-emitting diode; CFL; incandescent; halogen; lamp; bulb; TCLP; STLC; TTLC; WET; hazardous waste; electronic...

  3. Center for Energy Nanoscience at USC

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Areas: The Center for Energy Nanoscience performs research to create low cost, high efficiency solar cells and light emitting diodes (LEDs) by using semiconductor...

  4. News Item

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... photovoltage multiplication in carbon nanotubes, by L.J. Yang et al., Nature Photonics 5 (2011) 672 6 High performance two-terminal carbon nanotube light emitting diodes, ...

  5. Top Science of 2013

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of quantum dot light emitting diodes Unraveling the mystery of quantum-dot blinking Smartphone data safety with quantum cryptography Los Alamos researchers unravel the mystery of...

  6. Exciting White Lighting

    Broader source: Energy.gov [DOE]

    Windows that emit light and are more energy efficient? Universal Display’s PHOLED technology enables windows that have transparent light-emitting diodes in them.

  7. Application Assessment of Bi-Level LED Parking Lot Lighting

    SciTech Connect (OSTI)

    Johnson, Megan; Cook, Tyson; Shackelford, Jordan; Pang, Terrance

    2009-02-01

    This report summarizes an assessment project conducted to evaluate light-emitting diode (LED) luminaires with bi-level operation in an outdoor parking lot application.

  8. GATEWAY Demonstrations: LED Street Lighting

    SciTech Connect (OSTI)

    Cook, Tyson; Shackelford, Jordan; Pang, Terrance Pang

    2008-12-01

    This report summarizes an assessment project conducted to study the performance of light emitting diode (LED) luminaires in a street lighting application in San Francisco, CA.

  9. ISSUANCE 2015-06-25: Energy Conservation Program: Test Procedures...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Test Procedures for Integrated Light-Emitting Diode Lamps, Supplemental Notice of Proposed Rulemaking ISSUANCE 2015-06-25: Energy Conservation Program: Test Procedures for ...

  10. 50-nanosecond pulses at 200 kilohertz

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  11. allows researchers to capture high-resolution images

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  12. LED Pulser

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  13. combines high intensity and short pulse duration

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  14. custom electronic circuitry

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  15. high-power LEDs

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  16. SAND2015-9467M

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  17. LED

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Cost The high-brightness, rapidly pulsed, multicolor light-emitting diode (LED) driver delivers lighting performance that exceeds that of conventional (laserarc-light) sources ...

  18. Center for Energy Nanoscience at USC

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    LED Nanowire LEDs GaN based light emitting diodes (LEDs) are a key technology for high brightness LEDs. Although already successful commercially, fundamental physical and device...

  19. Microsoft Word - Blue Cover

    Energy Savers [EERE]

    are now commercially viable. For example, cost- effective solid state light-emitting diode (LED) products that offer lighting uniformity and longer operating life are now...

  20. Biomass Cookstoves Technical Meeting: Summary Report

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Renewable Energy EPA Environmental Protection Agency GHG Greenhouse gas IAP Indoor air pollution IAQ Indoor air quality KPT Kitchen Performance Test LED Light-emitting diode NIH ...

  1. Uniform insulation applied-B ion diode

    DOE Patents [OSTI]

    Seidel, David B.; Slutz, Stephen A.

    1988-01-01

    An applied-B field extraction ion diode has uniform insulation over an anode surface for increased efficiency. When the uniform insulation is accomplished with anode coils, and a charge-exchange foil is properly placed, the ions may be focused at a point on the z axis.

  2. Spin-current diode with a ferromagnetic semiconductor

    SciTech Connect (OSTI)

    Sun, Qing-Feng Xie, X. C.

    2015-05-04

    Diode is a key device in electronics: the charge current can flow through the device under a forward bias, while almost no current flows under a reverse bias. Here, we propose a corresponding device in spintronics: the spin-current diode, in which the forward spin current is large but the reversed one is negligible. We show that the lead/ferromagnetic quantum dot/lead system and the lead/ferromagnetic semiconductor/lead junction can work as spin-current diodes. The spin-current diode, a low dissipation device, may have important applications in spintronics, as the conventional charge-current diode does in electronics.

  3. Azido Functionalized Poly(3-hexylthiophene) and Method of Forming Same -

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Innovation Portal Advanced Materials Advanced Materials Find More Like This Return to Search Azido Functionalized Poly(3-hexylthiophene) and Method of Forming Same Brookhaven National Laboratory Contact BNL About This Technology <p> Imprinted and cross-linked P3HT-N5</p> Imprinted and cross-linked P3HT-N5 Technology Marketing Summary Conductive polymers are finding mainstream applications in organic light-emitting diodes, capacitors, batteries, organic transistors,

  4. Organization | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Organization Organization Organization

  5. Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

    SciTech Connect (OSTI)

    Ding, Baofu Alameh, Kamal

    2014-07-07

    The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.

  6. Advancements in ion diode and triode design

    SciTech Connect (OSTI)

    Cavenago, M., E-mail: cavenago@lnl.infn.it [INFN-LNL, viale dell'Universit n.2, 35020 Legnaro (PD) (Italy)

    2014-02-15

    Selfconsistent laminar flow models, which enable to predict the optimal cathode and anode geometry in simple diodes, must be modified to account for the anode aperture and the effect of other electrodes. An equation for charge coupled to arbitrary laminar flows is here first presented and its numerical solutions are obtained with a new method, based on mesh transformations. It is found that a close match to theoretical flows requires an increase of the simple diode voltage v{sub 0} by an amount v{sub ?}, which, for a typical case designed for zero exit angle condition, are v{sub 0} = 0.7465 and v{sub ?} = 0.0294 in adimensional units. States in and out for the anode lens are also shown, where out is a new and nonlinear solution for the beam expansion in a drift tube.

  7. DIODE STEERED MANGETIC-CORE MEMORY

    DOE Patents [OSTI]

    Melmed, A.S.; Shevlin, R.T.; Laupheimer, R.

    1962-09-18

    A word-arranged magnetic-core memory is designed for use in a digital computer utilizing the reverse or back current property of the semi-conductor diodes to restore the information in the memory after read-out. In order to ob tain a read-out signal from a magnetic core storage unit, it is necessary to change the states of some of the magnetic cores. In order to retain the information in the memory after read-out it is then necessary to provide a means to return the switched cores to their states before read-out. A rewrite driver passes a pulse back through each row of cores in which some switching has taken place. This pulse combines with the reverse current pulses of diodes for each column in which a core is switched during read-out to cause the particular cores to be switched back into their states prior to read-out. (AEC)

  8. Infrared photoemitting diode having reduced work function

    DOE Patents [OSTI]

    Hirschfeld, T.B.

    1982-05-06

    In electro-optical detectors which include as elements a photoemitting photocathode and anode, a photoemitting diode is fabricated which lowers the diode's work function, thus reducing the cooling requirement typically needed for this type of device. The work function is reduced by sandwiching between the photocathode and anode a liquid meidum of the formula NR/sub 3/ and having an electron affinity for the electrons of the photocathode, which liquid medium permits free electrons leaving the photocathode to remain as stable solvated species in the liquid medium. Thus, highly light-absorbent, and therefore thin, metallic layers can be used for detection, thereby reducing dark current at a given temperature, with a consequent reduction in cooling requirements at constant detector performance.

  9. Infrared photoemitting diode having reduced work function

    DOE Patents [OSTI]

    Hirschfeld, Tomas B.

    1984-01-01

    In electro-optical detectors which include as elements a photoemitting photocathode and anode, a photoemitting diode is fabricated which lowers the diode's work function, thus reducing the cooling requirement typically needed for this type of device. The work function is reduced by sandwiching between the photocathode and anode a liquid medium of the formula NR.sub.3 and having an electron affinity for the electrons of the photocathode, which liquid medium permits free electrons leaving the photocathode to remain as stable solvated species in the liquid medium. Thus, highly light-absorbent, and therefore thin, metallic layers can be used for detection, thereby reducing dark current at a given temperature, with a consequent reduction in cooling requirements at constant detector performance.

  10. Stability theory of Knudsen plasma diodes

    SciTech Connect (OSTI)

    Kuznetsov, V. I. Ender, A. Ya.

    2015-11-15

    A stability theory is developed for a plasma diode in which an electron beam supplied from the emitter propagates without collisions in the self-consistent electric field against the immobile ion background. An integral equation for the amplitude of the perturbed field is deduced using the Q,G method for the regime without electron reflection from a potential barrier. Analytic solutions to this equation are obtained for a number of important particular cases, and the plasma dispersion properties are examined.

  11. Diode having trenches in a semiconductor region

    DOE Patents [OSTI]

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2016-03-22

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  12. Thermal Reliability Study of Bypass Diodes in Photovoltaic Modules |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Thermal Reliability Study of Bypass Diodes in Photovoltaic Modules Thermal Reliability Study of Bypass Diodes in Photovoltaic Modules Presented at the PV Module Reliability Workshop, February 26 - 27 2013, Golden, Colorado pvmrw13_ps3_nrel_zhang.pdf (530.07 KB) More Documents & Publications US TG 4 Activities of QA Forum US & Japan TG 4 Activities of QA Forum High Temperature Reverse By-Pass Diodes Bias and Failures

  13. Plasma-filled diode based on the coaxial gun

    SciTech Connect (OSTI)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-10-15

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of {>=}1 MeV at the current of Almost-Equal-To 100 kA was obtained in the experiments with a plasma-filled diode. The energy of Almost-Equal-To 5 kJ with the peak power of {>=}100 GW dissipated in the diode.

  14. Diode-Pumped Alkali Laser: A New Combination

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser-Compton Light Source Technology Short-Pulse Lasers High-Powered Lasers Journal Articles home science photon science directed energy Diode-Pumped Alkali Laser: A ...

  15. Apparatus for mounting a diode in a microwave circuit

    DOE Patents [OSTI]

    Liu, Shing-gong

    1976-07-27

    Apparatus for mounting a diode in a microwave circuit for making electrical contact between the circuit and ground and for dissipation of heat between the diode and a heat sink. The diode, supported on a thermally and electrically conductive member, is resiliently pressed in electrical contact with the microwave circuit. A tapered collar on the member is elastically deformably wedged into a tapered aperture formed in a heat sink. The wedged collar tightens firmly around the member establishing good thermal and electrical conduction from the diode to the heat sink and ground. Disassembly is facilitated because of the elastically deformed collar.

  16. Research & Development | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Research & Development Research & Development R&amp;DPlan2016_Cover.jpg DOE leadership and support spur advances in the efficacy and performance of light-emitting diode (LED) and organic LED (OLED) technologies-advances that might not otherwise be achieved without DOE funding. Despite rapid advances, SSL technology is actually still in its early years, and continued innovation and breakthroughs are needed to achieve the full potential of the technology. Unlike conventional lighting

  17. New Efficiency Record Achieved for White OLED Device

    Broader source: Energy.gov [DOE]

    Osram Opto-Semiconductors, Inc. has successfully demonstrated a white organic light emitting diode (OLED) with a record efficiency of 25 lumens per watt, the highest known efficiency achieved to date for a polymer-based white OLED. The 25 LPW cool-white-emitting device was produced by applying a standard external inorganic phosphor to Osram's record-breaking blue-emitting phosphorescent polymer device with a peak luminous efficacy of 14 LPW.

  18. Achieving Record Efficiency for Blue OLEDs by Controlling the Charge Balance

    Broader source: Energy.gov [DOE]

    Researchers at the University of Florida (UF) have demonstrated a blue phosphorescent organic light-emitting diode (OLED) with a peak power efficiency of 50 lm/W and an external quantum efficiency exceeding 20 percent at a luminance of 1,000 cd/m2, using no external light extraction techniques. This accomplishment is believed to be the world record in blue OLED efficiency.

  19. Research & Development | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Research & Development Research & Development R&amp;DPlan2016_Cover.jpg DOE leadership and support spur advances in the efficacy and performance of light-emitting diode (LED) and organic LED (OLED) technologies-advances that might not otherwise be achieved without DOE funding. Despite rapid advances, SSL technology is actually still in its early years, and continued innovation and breakthroughs are needed to achieve the full potential of the technology. Unlike conventional lighting

  20. SSL Basics | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    SSL Basics SSL Basics Solid-state lighting (SSL) differs from other kinds of lighting in that it's based on light-emitting diodes (LEDs) or organic LEDs (OLEDs) instead of filaments, plasma, or gases. In addition to having the potential to be more energy efficient than any other existing lighting technology, it also has a number of other advantages-including directionality, controllability, vibration resistance, long life, color tunability, and aesthetic appeal. But SSL is still at a relatively