National Library of Energy BETA

Sample records for light-emitting diodes leds

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

    Energy Savers [EERE]

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

  2. 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 ...

  3. 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.

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

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; LIGHT EMITTING DIODES; OCCUPANTS; ...

  5. 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.

  6. 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

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

    Office of Scientific and Technical Information (OSTI)

    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 ...

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

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ROADS; LIGHTING SYSTEMS; LIGHT EMITTING ...

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

    Office of Scientific and Technical Information (OSTI)

    the Field Museum in Chicago, IL (Technical Report) | SciTech Connect Accent Lighting at the Field Museum in Chicago, IL Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Accent Lighting at the Field Museum in Chicago, IL 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. Authors: Myer, Michael ; Kinzey, Bruce R.

  10. 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 (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 post-top luminaire. This report reviews the energy

  11. 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

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

    Office of Scientific and Technical Information (OSTI)

    monochromatic spectral output and poor color rendering ability; therefore, this LED ... Subject: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLOR; DEMONSTRATION PROGRAMS; ...

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

    Office of Scientific and Technical Information (OSTI)

    In comparison to the 400W PMH system, the LED system would save 44 percent of the energy ... This demonstration met the GATEWAY requirements of saving energy, matching or improving ...

  14. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting

    Office of Scientific and Technical Information (OSTI)

    in Leavenworth, KS (Technical Report) | SciTech Connect in Leavenworth, KS Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting in Leavenworth, KS 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

  15. Demonstration Assessment of Light-Emitting Diode (LED) Street Lighting Host

    Office of Scientific and Technical Information (OSTI)

    Site: Lija Loop, Portland, Oregon (Technical Report) | SciTech Connect Street Lighting Host Site: Lija Loop, Portland, Oregon Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Street Lighting Host Site: Lija Loop, Portland, Oregon 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

  16. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting

    Office of Scientific and Technical Information (OSTI)

    at T.J.Maxx in Manchester, NH Phase I (Technical Report) | SciTech Connect at T.J.Maxx in Manchester, NH Phase I Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting at T.J.Maxx in Manchester, NH Phase I 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

  17. 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.

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

    Office of Scientific and Technical Information (OSTI)

    the I-35W Bridge, Minneapolis, MN (Technical Report) | SciTech Connect Roadway Lighting at the I-35W Bridge, Minneapolis, MN Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, Minneapolis, MN 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

  19. Energy Savings Estimates of Light Emitting Diodes

    Office of Energy Efficiency and Renewable Energy (EERE)

    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

  20. light-emitting diode

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

    light-emitting diode - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced

  1. 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.

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

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting ... Country of Publication: United States Language: English Subject: LEDs; light-emitting diodes; ...

  3. 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.

  4. 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. However, when the life-cycle costs from energy and maintenance were factored into the scenario, the LED system had lower costs at the end of a 10-year analysis period. The LED system had a 6.1 year payback compared to the 1000W PMH system and a 7.5 year payback versus the 400W PMH system. The costs reflect high initial cost for the LED luminaire, plus more luminaires and (subsequently) more poles for the LED system. The other major issue affecting cost effectiveness was that Leavenworth, Kansas has very low electricity costs. The melded rate for this site was $0.056 per kWh for electricity. However, if the national electricity rate of $0.1022/kWh was used the payback would change to between four and five years for the LED system. This demonstration met the GATEWAY requirements of saving energy, matching or improving illumination, and being cost effective. The project also demonstrated that the Commercial Building Energy Alliance (CBEA) specification works in practice. Walmart appreciated having an entire site lighted by LEDs to gain more experience with the technology. Walmart is reviewing the results of the demonstration as they consider their entire real estate portfolio.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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:...

  10. 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.

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

    Office of Scientific and Technical Information (OSTI)

    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) ...

  12. 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.

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

    Broader source: Energy.gov [DOE]

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

  14. 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.

  15. 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 ...

  16. 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.

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

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

    Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate Presenter: Arpan Chakraborty, Soraa Inc. This ...

  18. 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 levels were measured for the HPS and LED Version 1 luminaires and projected for the Version 2 luminaires. Maximum light levels were 23.51 foot candles, 20.54 fc, and 26.7 fc respectively and minimum light levels were 1.49 fc, 1.45 fc, and 1.88 fc. These results indicate very similar or even slightly higher light levels produced by the LED lamps, despite the higher lumen output of the HPS lamp. The LED lamps provide higher luminaire efficacy because all of the light is directed down and out. None of it is “lost” in the fixture. Also the HPS luminaire had poorly designed optics and a plastic covering that tended to get dirty and cracked, further decreasing the realized light output.[is this an accurate way to say this?] Consumer perceptions of the Version 2 LED were collected via a written survey form given to maintenance and security personnel. More than half felt the LED luminaires provided more light than the HPS lamps and a majority expressed a preference for the new lamps when viewing the relamped area through a security camera. Respondents commented that the LED luminaires were less glary, created less shadows, had a positive impact on visibility, and improved the overall appearance of the area. PNNL conducted an economic analysis and found that the Version 1 lamp produced annual energy savings of 955 kWh and energy cost savings of $76.39 per lamp at electricity rates of 6.5 cents per kWh and $105.03 at 11 cents per kWh. PNNL found that the Version 2 lamp produced annual energy savings of 991 kWh and energy cost savings of $79.26 per lamp at electricity rates of 6.5 cents per kWh and $108.98 at 11 cents per kWh. PNNL also calculated simple payback and found that Version 1 showed paybacks of 5.4 yrs at 6.5c/kWh and 4.1 yrs at 11c/kWh while Version 2 showed paybacks of 5.2 yrs at 6.5c/kWh and 3.9 yrs at 11c/kWh.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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%.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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 illuminance measurements taken on the walls, indicating better lateral dispersion of the light. The undercabinet fixture’s light output was midway between the low and high power halogen undercabinet fixture light outputs (35.8 foot candle versus 13.4 fc and 53.4 fc) but it produced a more uniform light (max/min ratio of 7.0 versus 10.8). The color correlated temperature (CCT, the blue or yellowness) of the LED light correlated well with the halogen and incandescent lights (2675 K vs 2700 K). The color rendering of the LED downlight also correlated well at 92 CRI compared to 100 CRI for the halogen and incandescent lamps. The LED undercabinet fixture had measures of 2880 K CCT and 71 CRI compared to the 2700 K and 100 CRI scores for the halogen undercabinet fixture. Builders who toured the homes were surveyed; they gave the LED downlight high marks for brightness, said the undercabinet improved shadows and glare and said both products improved overall visibility, home appearance, and home value. Paybacks on the LED downlight ranged from 7.6 years (assuming electricity cost of 11 c/kWh) to 13.5 years (at 5C/kWh). Paybacks on the LED undercabinet fixture in a new home ranged from 4.4 years (11c/kWh electricity) to 7.6 years (5c/kWh) based on product costs of $95 per LED downlight and $140 per LED undercabinet fixture at 3 hrs per day of usage for the downlight and 2 hrs per day for the undercabinet lighting.

  12. 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.

  13. Laterally injected light-emitting diode and laser diode

    SciTech Connect (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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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").

  19. 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.

  20. 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

  1. 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 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) Headquarters in Washington, DC, in which

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 2014-06-18 Issuance: Test Procedure for Integrated Light-Emitting Diode

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

    Lamps; Supplemental Notice of Proposed Rulemaking | Department of Energy 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 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 Deputy

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

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

    Low-Cost Light-Emitting Diode Luminaire for General Illumination Presenter: Paul Fini, CREE Santa Barbara Technology Center This project is demonstrating an efficient and stable ...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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. %.

  4. 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.

  5. 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.

  6. 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.

  7. Demonstration Assessment of Light-Emitting Diode Roadway Lighting on the

    Office of Scientific and Technical Information (OSTI)

    FDR Drive in New York, New York (Technical Report) | SciTech Connect Roadway Lighting on the FDR Drive in New York, New York Citation Details In-Document Search Title: Demonstration Assessment of Light-Emitting Diode Roadway Lighting on the FDR Drive in New York, New York 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. Authors: Myer, Michael ; Hazra, Oindrila ; Kinzey, Bruce R.

  8. 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.

  9. 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. ...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. High-Efficiency and Stable White Organic Light-Emitting Diode Using a Single Emitter

    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. Current WOLED technology requires the use of multiple emissive materials, which are expensive to manufacture and also generate color instability and color aging issues, affecting WOLED performance and operational lifetime.

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

    Office of Scientific and Technical Information (OSTI)

    Staff at DOL Headquarters reported high satisfaction with the operation of the LED product. Authors: Kinzey, Bruce R. ; Myer, Michael Publication Date: 2013-03-01 OSTI Identifier: ...

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    Broader source: Energy.gov [DOE]

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

  7. 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.

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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?LED were significantly improved, which was attributed to an enhancement in the current spreading property due to densely interconnecting ITO NWs. In addition, light output power and wall-plug efficiency from the Si NC LED were enhanced by 45% and 38%, respectively. This was originated from an enhancement in the escape probability of the photons generated in the Si NCs due to multiple scatterings at the surface of ITO NWs acting as a light waveguide. We show here that the use of the ITO NWs can be very useful for realizing a highly efficient Si NC LED.

  15. 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.

  16. 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.

  17. 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.

  18. 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}.

  19. Layering Mismatched Lattices Creates Long-Sought-After Green Light-Emitting Diode (Fact Sheet), NREL Highlights, Science, NREL (National Renewable Energy Laboratory)

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

    Scientists at the National Renewable Energy Laboratory (NREL) invent a deep green LED that can lead to higher-efficiency white light, lower electric bills. The white light light-emitting diode (LED) that promises to revolutionize indoor lighting while dramatically lowering electricity costs had been confounded by the so-called "green gap:" the inability to develop light in the green spectrum that can be combined with red and blue to produce white light. NREL researchers conceptualized

  20. 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.

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. 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?LEDs.

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

    Office of Scientific and Technical Information (OSTI)

    Authors: Myer, Michael ; Kinzey, Bruce R. Publication Date: 2010-12-10 OSTI Identifier: 1004825 Report Number(s): PNNL-20005 BT0301000; TRN: US201105%%110 DOE Contract Number: ...

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  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. 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.

  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. 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. 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.

  17. 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.

  18. 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.

  19. High-Throughput, High-Precision Hot Testing Tool for High-Brightness Light-Emitting Diode Testing

    Broader source: Energy.gov [DOE]

    This project is determining the requirements of the solid-state lighting industry for high-quality color coordination and flux characterization of high-brightness light-emitting diodes (HBLEDs) as well as demonstrating and testing a cost-effective hot test tool that meets the requirements.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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.

  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. 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.

  8. 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

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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-efficiency OLED demonstrated in 1987. Thus, we expect to see exciting advances in the science, technology and commercialization in the coming years. We hope that this book helps to advance the field in some small way. Contributors to this monograph are experts from top academic institutions, industry and national laboratories who provide comprehensive and up-to-date coverage of the rapidly evolving field of OLEDs. Furthermore, this monograph collects in one place, for the first time, key topics across the field of OLEDs, from fundamental chemistry and physics, to practical materials science and engineering topics, to aspects of design and manufacturing. The monograph synthesizes and puts into context information scattered throughout the literature for easy review in one book. The scope of the monograph reflects the necessity to focus on new technological challenges brought about by the transition to manufacturing. In the Section 1, all materials of construction of the OLED device are covered, from substrate to encapsulation. In Section 2, for the first time, additional challenges in devices and processing are addressed. This book is geared towards a broad audience, including materials scientists, device physicists, synthetic chemists and electrical engineers. Furthermore, this book makes a great introduction to scientists in industry and academia, as well as graduate students interested in applied aspects of photophysics and electrochemistry in organic thin films. This book is a comprehensive source for OLED R&D professionals from all backgrounds and institutions.

  16. 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.

  17. 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.

  18. 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.

  19. 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 other OLEDs' attributes such as mechanical flexibility and potential low cost), the OLED technology is promising to successfully compete with current technologies, such as LCDs and inorganic LEDs.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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 423426?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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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-phosphor converted white light emitting diodes.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 2014-05-16 Issuance: Test Procedures for Integrated Light-Emitting...

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

    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 ...

  4. 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 ...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. LedEngin Inc | Open Energy Information

    Open Energy Info (EERE)

    LedEngin Inc Jump to: navigation, search Name: LedEngin, Inc Place: Santa Clara, California Zip: 95054 Product: Developer of Light Emitting Diode (LED) technology for medical and...

  12. 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.

  13. Sandia-Developed LED Pulser Delivers Laser-Like Performance at...

    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. 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.

  15. 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, E-mail: ymchang@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China)] [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China); Chang, Chiao-Yun; Huang, Huei-Min; Lu, Tien-Chang [Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan (China)] [Department of Photonics, National Chiao Tung University, 30010 Hsinchu, Taiwan (China)

    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 ?m 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.

  16. LED ADOPTION REPORT | Department of Energy

    Energy Savers [EERE]

    ADOPTION REPORT LED ADOPTION REPORT PDF icon Report: Adoption of Light-Emitting Diodes in Common Lighting Applications PDF icon Report Summary PDF icon Full Infographic More Documents & Publications Energy Savings Forecast of Solid-State Lighting in General Illumination Applications 2015 SSL TECHNOLOGY DEVELOPMENT WORKSHOP PRESENTATIONS - Day 1 Energy Savings Estimates of Light Emitting Diodes

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. LED Lighting | Department of Energy

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

    focusing light in ways that are useful in homes and commercial settings. The light-emitting diode (LED) is one of today's most energy-efficient and rapidly-developing lighting...

  5. LED Lighting | Department of Energy

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

    are directional, focusing light in ways that are useful in homes and commercial settings. The light-emitting diode (LED) is one of today's most energy-efficient and...

  6. LED ADOPTION REPORT | Department of Energy

    Energy Savers [EERE]

    Publications » Market Studies » LED ADOPTION REPORT LED ADOPTION REPORT LED ADOPTION REPORT The DOE report, Adoption of Light-Emitting Diodes in Common Lighting Applications, is the latest in a series analyzing markets where LEDs compete with traditional lighting sources. Report: Adoption of Light-Emitting Diodes in Common Lighting Applications Report Summary Full Infographic The new report reveals a wealth of insights into promising pathways for SSL technology development, providing estimates

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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 dipoledipole 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.

  13. Save Money with LED Holiday Light Strings

    Broader source: Energy.gov [DOE]

    LED (or light emitting diode) light strings can use 90% less energy than regular incandescent light strings. They also last about ten times longer, are cooler than incandescents (reducing fire hazards), and are more durable.

  14. LEDs Ready for Takeoff at Louisiana Airport

    Broader source: Energy.gov [DOE]

    About 250 lights along the busy taxiway at Hammond Northshore Regional Airport are being replaced with light-emitting diodes (LEDs) with funds from an Energy Efficiency and Conservation Block Grant (EECBG) from the U.S. Department of Energy.

  15. 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.

  16. 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 thin LiF layer serves typically as the electron injection layer in OLEDs and electron collection interlayer in the OSCs. However, several reports showed that it can also assist in holeinjection in OLEDs. Here we first demonstrate that it assists hole-collection in OSCs, which is more obvious after air-plasma treatment, and explore this intriguing dual role. For OLEDs, we focus on solution processing methods to fabricate highly efficient phosphorescent OLEDs. First, we investigated OLEDs with a polymer host matrix, and enhanced charge injection by adding hole- and electron-transport materials into the system. We also applied a hole-blocking and electron-transport material to prevent luminescence quenching by the cathode. Finally, we substituted the polymer host by a small molecule, to achieve more efficient solution processed small molecular OLEDs (SMOLEDs); this approach is cost-effective in comparison to the more common vacuum thermal evaporation. All these studies help us to better understand the underlying relationship between the organic semiconductor materials and the OSCs and OLEDs performance and will subsequently assist in further enhancing the efficiencies of OSCs and OLEDs. With better efficiency and longer lifetime, the OSCs and OLEDs will be competitive with their inorganic counterparts.

  17. EECBG Success Story: LEDs Ready for Takeoff at Louisiana Airport

    Broader source: Energy.gov [DOE]

    About 250 lights along the taxiway at Hammond Northshore Regional Airport in Louisiana are being replaced with light-emitting diodes (LEDs) with funds from an Energy Efficiency and Conservation Block Grant (EECBG). Learn more.

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. LED lamp

    DOE Patents [OSTI]

    Galvez, Miguel; Grossman, Kenneth; Betts, David

    2013-11-12

    There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

  3. 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

  4. 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}).

  5. 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.

  6. 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.

  7. 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.

  8. Prospects for LED lighting.

    SciTech Connect (OSTI)

    Tsao, Jeffrey Yeenien; Gee, James Martin; Simmons, Jerry Alvon

    2003-08-01

    Solid-state lighting using light-emitting diodes (LEDs) has the potential to reduce energy consumption for lighting by 50% while revolutionizing the way we illuminate our homes, work places, and public spaces. Nevertheless, substantial technical challenges remain in order for solid-state lighting to significantly displace the well-developed conventional lighting technologies. We review the potential of LED solid-state lighting to meet the long-term cost goals.

  9. Today LED Holiday Lights, Tomorrow the World?

    SciTech Connect (OSTI)

    Gordon, Kelly L.

    2004-12-20

    This article for The APEM Advantage, the quarterly newsletter of the Association of Professional Energy Managers (APEM) describes the recent increase in the popularity of light emitting diode (LED) lighting and compares LED light output with that of incandescent and compact fluorescent lighting.

  10. 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.

  11. LED Lighting | Department of Energy

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

    Electricity & Fuel » Lighting » LED Lighting LED Lighting LED Lighting The light-emitting diode (LED) is one of today's most energy-efficient and rapidly-developing lighting technologies. Quality LED light bulbs last longer, are more durable, and offer comparable or better light quality than other types of lighting. Check out the top 8 things you didn't know about LEDs to learn more. Energy Savings LED is a highly energy efficient lighting technology, and has the potential to fundamentally

  12. 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.

  13. 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.

  14. 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.

  15. Biomedical devices from ultraviolet LEDs

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

    Biomedical devices from ultraviolet LEDs Light-emitting nanocrystal diodes go ultraviolet Biomedical devices with active components could be made from nanostructured systems. February 24, 2012 Researcher working with nanocrystals A researcher at LANL works with nanocrystals. Get Expertise Researcher Sergio Brovelli Physical Chem & Applied Spectroscopy Email Research Team Leader Alberto Paleari University of Milano-Bicocca in Italy Such devices could, for example, selectively activate

  16. 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.

  17. Purchasing Energy-Efficient Commercial and Industrial LED Luminaires |

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

    Department of Energy Commercial and Industrial LED Luminaires Purchasing Energy-Efficient Commercial and Industrial LED Luminaires The Federal Energy Management Program (FEMP) provides acquisition guidance for commercial and industrial light emitting diode (LED) luminaires, a product category covered by FEMP efficiency requirements. Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified or FEMP-designated products in all product categories covered by these

  18. 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.

  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. LED Update

    SciTech Connect (OSTI)

    Johnson, Mark L.; Gordon, Kelly L.

    2006-09-01

    This article, which will appear in RESIDENTIAL LIGHTING MAGAZINE, interviews PNNL's Kelly Gordon and presents the interview in question and answer format. The topic is a light emitting diode (LED) lighting also known as solid state lighting. Solid state lighting will be a new category in an energy efficient lighting fixture design competition called Lighting for Tomorrow sponsored by the US Department of Energy Emerging Technologies Office, the American Institute for Lighting, and the Consortium for Energy Efficiency. LED technology has been around since the ’60s, but it has been used mostly for indicator lights on electronics equipment. The big breakthrough was the development in the 1990s of blue LEDs which can be combined with the red and green LEDs that already existed to make white light. LEDs produce 25 to 40 lumens of light per watt of energy used, almost as much as a CFL (50 lumens per watt) and much more efficient than incandescent sources, which are around 15 lumens per watt. They are much longer lived and practical in harsh environments unsuitable for incandescent lighting. They are ready for niche applications now, like under-counter lighting and may be practical for additional applications as technological challenges are worked out and the technology is advancing in leaps and bounds.

  1. 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.

  2. 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.

  3. 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.

  4. 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 400410 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.

  5. 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.

  6. 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.

  7. Researchers Say They've Solved the Mystery of LED Lighting "Droop"

    Broader source: Energy.gov [DOE]

    Despite being cool, ultra-efficient and long lasting, the light-emitting diode (LED) faces a problem called “efficiency droop.” New findings from simulations carried out at the National Energy Research Scientific Computer Center (NERSC) have unearthed droop’s elusive cause, researchers say, paving the way for wider LED use. An illustration of nitride-based LEDs.| Courtesy of the National Energy Research Scientific Computing Center.

  8. 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.

  9. To Bridge LEDs' Green Gap, Scientists Think Small

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

    To Bridge LEDs' Green Gap, Scientists Think Small To Bridge LEDs' Green Gap, Scientists Think Small Nanostructures Half a DNA Strand-Wide Show Promise for Efficient LEDs April 4, 2014 Contact: Margie Wylie, mwylie@lbl.gov, +1 510 486 7421 Nanostructures half the breadth of a DNA strand could improve the efficiency of light emitting diodes (LEDs), especially in the "green gap," a portion of the spectrum where LED efficiency plunges, simulations at the U.S. Department of Energy's

  10. 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

  11. 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: ...

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

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

    ... flashlights, machine vision, museum or art gallery display lighting, architectural ... shaped neon-tube channel letter signs, reverse channel letters, and border lighting. ...

  13. 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.

  14. 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.

  15. 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.

  16. MOF Coating a Promising Path to White LEDs

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

    MOF Coating a Promising Path to White LEDs MOF Coating a Promising Path to White LEDs Print Friday, 27 February 2015 17:11 Hu et al. designed a new yellow phosphor with high quantum yield by immobilizing a preslected chromophore into the rigid framework of a metal-organic framework (MOF); the structure was determined at Beamline 11.3.1. Coating a blue light-emitting diode (LED) with this compound readily generates white light with high luminous efficacy. The new yellow phosphor demonstrates

  17. High Performance Green LEDs by Homoepitaxial

    SciTech Connect (OSTI)

    Wetzel, Christian; Schubert, E Fred

    2009-11-22

    This work's objective was the development of processes to double or triple the light output power from green and deep green (525 - 555 nm) AlGaInN light emitting diode (LED) dies within 3 years in reference to the Lumileds Luxeon II. The project paid particular effort to all aspects of the internal generation efficiency of light. LEDs in this spectral region show the highest potential for significant performance boosts and enable the realization of phosphor-free white LEDs comprised by red-green-blue LED modules. Such modules will perform at and outperform the efficacy target projections for white-light LED systems in the Department of Energy's accelerated roadmap of the SSL initiative.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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%.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. LED intense headband light source for fingerprint analysis

    DOE Patents [OSTI]

    Villa-Aleman, Eliel

    2005-03-08

    A portable, lightweight and high-intensity light source for detecting and analyzing fingerprints during field investigation. On-site field analysis requires long hours of mobile analysis. In one embodiment, the present invention comprises a plurality of light emitting diodes; a power source; and a personal attachment means; wherein the light emitting diodes are powered by the power source, and wherein the power source and the light emitting diodes are attached to the personal attachment means to produce a personal light source for on-site analysis of latent fingerprints. The present invention is available for other applications as well.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Multicolor, High Efficiency, Nanotextured LEDs

    SciTech Connect (OSTI)

    Jung Han; Arto Nurmikko

    2011-09-30

    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 green for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) heteroepitaxy of nitrogen-polar LEDs on sapphire, (ii) heteroepitaxy of semipolar (11{bar 2}2) green LEDs on sapphire, (iii) synthesis of quantum-dot loaded nanoporous GaN that emits white light without phosphor conversion, (iv) demonstration of the highest quality semipolar (11{bar 2}2) GaN on sapphire using orientation-controlled epitaxy, (v) synthesis of nanoscale GaN and InGaN medium, and (vi) development of a novel liftoff process for manufacturing GaN thin-film vertical LEDs. 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.

  18. 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.

  19. Switched-capacitor isolated LED driver

    DOE Patents [OSTI]

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  20. Tests gauge LED sensors for fuel-dye measurements

    SciTech Connect (OSTI)

    Ozanich, Richard M.; Lucke, Richard B.; Melville, Angela M.; Wright, Bob W.

    2009-10-19

    The goal of this work was to develop a low cost, robust sensor to allow direct measurement of Solvent Red 164 dye concentration in off-road fuel at refineries and fuel terminals. Optical absorption sensors based on light emitting diodes (LEDs) are rugged, low-cost, have low power consumption, and can be designed to be intrinsically safe.LED-based systems have been used in a variety of chemical detection applications including heavy metals, pH, CO2, and O2. The approach for this work was to develop a sensor that could be mounted on a pipeline sight glass, precluding the need for direct contact of the sensor with the fuel. Below is described the design and testing of three different LED/photodiode sensors utilizing reflectance spectrometry for the measurement of dye concentration.

  1. 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.

  2. 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

  3. Magical Mystery Devices or Not: How do LED Lamps and Luminaires Really Measure-Up?

    SciTech Connect (OSTI)

    Paget, Maria L.; McCullough, Jeffrey J.; Steward, Heidi E.

    2008-08-15

    Solid-state lighting products for general lighting applications are now gaining a market presence, and more and more people are asking, “Which of these are ‘good’ products? Do they perform as claimed? How do they compare? Light Emitting Diodes (LEDs) differ from other light sources enough to require new procedures for measuring their performance and comparing to other lighting options, so both manufacturers and buyers are facing a learning curve. The energy-efficiency community has traditionally compared light sources based on system efficacy: rated lamp lumens divided by power into the system. This doesn’t work for LEDs because there are no standard LED “lamp” packages and no lamp ratings, and because LED performance depends heavily on thermal, electrical, and optical design of complete lighting unit or ‘luminaire’. Luminaire efficacy is the preferred metric for LEDs because it measures the net light output from the luminaire divided by power into the system.

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

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

    Current WOLED technology requires the use of multiple emissive materials, which are expensive to manufacture and also generate color instability and color aging issues, affecting ...

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

    SciTech Connect (OSTI)

    Hellerich, Emily

    2013-05-15

    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-coated mixed emitting layer (EML) is used, consisting of a polymer and a small molecule that both emit in the near UV and blue. The resulting combined spectra gives a wide band that can be used to create narrow microcavity emission peaks of 373 to 469 nm, depending on the device thickness (i.e. the cavity’s optical length). In the process of this effort, the mixed EML presented interesting complexities that we attempt to explain via simulation and morphology study.

  11. 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.

  12. LED system performance in a trial installation - one year later: Yuma border patrol, Yuma, Arizona

    SciTech Connect (OSTI)

    Wilkerson, Andrea M.; Davis, Robert G.

    2015-04-01

    The Yuma Sector Border Patrol Area is a high temperature and high solar radiation environment, providing an opportunity for the U.S. Department of Energy (DOE) to study thermal effects on outdoor light-emitting diode (LED) luminaires outside of the testing laboratory. Six LED luminaires were installed on three poles on the U.S.- Mexico border in February 2014 as part of a trial installation, which was detailed in a prior GATEWAY report.1 The initial trial installation was intended as a short - term test of six luminaires installed on three poles before proceeding with the complete installation of over 400 luminaires. Unexpected delays in the full installation have prevented the detailed evaluations initially planned, but the six installed LED luminaires continue to be monitored, and over the past year illuminance measurements were recorded initially in February 2014 and again in September 2014 at about 2500 hours of operation and in March 2015 at about 5000 hours of operation.

  13. Characterization of failure modes in deep UV and deep green LEDs utilizing advanced semiconductor localization techniques.

    SciTech Connect (OSTI)

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

    2012-03-01

    We present the results of a two-year early career LDRD that focused on defect localization in deep green and deep ultraviolet (UV) light-emitting diodes (LEDs). We describe the laser-based techniques (TIVA/LIVA) used to localize the defects and interpret data acquired. We also describe a defect screening method based on a quick electrical measurement to determine whether defects should be present in the LEDs. We then describe the stress conditions that caused the devices to fail and how the TIVA/LIVA techniques were used to monitor the defect signals as the devices degraded and failed. We also describe the correlation between the initial defects and final degraded or failed state of the devices. Finally we show characterization results of the devices in the failed conditions and present preliminary theories as to why the devices failed for both the InGaN (green) and AlGaN (UV) LEDs.

  14. New DOE Report Estimates LED Savings in Common Lighting Applications

    Broader source: Energy.gov [DOE]

    The U.S. Department of Energy (DOE) has released its latest report in a series analyzing markets where LEDs compete with traditional lighting sources. The new report, Adoption of Light-Emitting...

  15. Long-term Testing Results for the 2008 Installation of LED Luminaires at the I-35 West Bridge in Minneapolis

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Davis, Robert G.

    2014-09-30

    This document reports the long-term testing results from an extended GATEWAY project that was first reported in “Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, in Minneapolis, MN,” August 2009. That original report presented the results of lighting the newly reconstructed I 35W Bridge using LEDs in place of conventional high-pressure sodium (HPS) roadway luminaires, comparing energy use and illuminance levels with a simulated baseline condition. That installation was an early stage implementation of LED lighting and remains one of the oldest installations in continued operation today. This document provides an update of the LED system’s performance since its installation in September 2008.

  16. 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.

  17. Assessing the Performance of 5mm White LED Light Sources forDeveloping-Country Applications

    SciTech Connect (OSTI)

    Mills, Evan

    2007-05-03

    Some white light-emitting diode (LED) light sources haverecently attained levels of efficiency and cost that allow them tocompete with fluorescent lighting for off-grid applications in thedeveloping world. Additional attributes (optics, size, ruggedness, andservice life) make them potentially superior products. Enormousreductions in energy use and greenhouse-gas emissions are thus possible,and system costs can be much lower given the ability to downsize thecharging and energy storage components compared to a fluorescentstrategy. However, there is a high risk of "market-spoiling" if inferiorproducts are introduced and result in user dissatisfaction. Completesystems involve the integration of light sources and optics, energysupply, and energy storage. A natural starting point for evaluatingproduct quality is to focus on the individual light sources. This reportdescribes testing results for batches of 10 5mm white LEDs from 26manufacturers. Efficacies and color properties are presented.

  18. Advanced method for increasing the efficiency of white light quantum dot LEDs

    SciTech Connect (OSTI)

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which, respectively, diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal processing (PTP), reduces the number of point defects while maintaining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of theQD nanoparticles. The current research uses a thermal model to predict annealing temperatures during PTP and demonstrates up to a 300% increase in photoluminescence for QDs on passive substrates.

  19. Advanced Power Electronics for LED Drivers: Advanced Technologies for integrated Power Electronics

    SciTech Connect (OSTI)

    2010-09-01

    ADEPT Project: MIT is teaming with Georgia Institute of Technology, Dartmouth College, and the University of Pennsylvania (UPenn) to create more efficient power circuits for energy-efficient light-emitting diodes (LEDs) through advances in 3 related areas. First, the team is using semiconductors made of high-performing gallium nitride grown on a low-cost silicon base (GaN-on-Si). These GaN-on-Si semiconductors conduct electricity more efficiently than traditional silicon semiconductors. Second, the team is developing new magnetic materials and structures to reduce the size and increase the efficiency of an important LED power component, the inductor. This advancement is important because magnetics are the largest and most expensive part of a circuit. Finally, the team is creating an entirely new circuit design to optimize the performance of the new semiconductors and magnetic devices it is using.

  20. LED Lighting: Applying Lessons Learned from the CFL Experience

    SciTech Connect (OSTI)

    McCullough, Jeffrey J.; Gilbride, Theresa L.; Gordon, Kelly L.; Ledbetter, Marc R.; Sandahl, Linda J.; Ton, My K.

    2008-08-20

    Light emitting diode (LED) technology has emerged as an exciting new lighting alternative with the potential for significant energy savings. There is concern, however, that white light LEDs for general illumination could take a long, bumpy course similar to another energy-efficient lighting technology – compact fluorescent lights (CFLs). Recognizing the significant potential energy-efficient lighting has to reduce U.S. energy consumption, Congress mandated in the Energy Policy Act of 2005 that the U.S. Department of Energy (DOE) develop Solid State Lighting (SSL) through a Next Generation Lighting Initiative. DOE’s first step was to analyze the market introduction of compact fluorescent lighting to determine what lessons could be learned to smooth the introduction of SSL in the United States (Sandahl et al. 2006). This paper summarizes applicable lessons learned from the market introduction of CFLs and describe how DOE and others are applying those lessons to speed the development and market introduction of energy-efficient LED lighting for general illumination applications. A description of the current state of LED technology and compares LEDs to incandescent, fluorescent, and halogen lights is also provided.

  1. LED Chips and Packaging for 120 LPW SSL Component

    SciTech Connect (OSTI)

    Ibbetson, James

    2009-12-28

    Cree has developed a new, high-efficiency, low-cost, light emitting diode (LED) lamp module that should be capable of replacing standard, halogen, fluorescent and metal halide lamps based on the total cost of ownership. White LEDs are produced by combining one or more saturated color LEDs with a phosphor or other light down-converting media to achieve white broad-band illumination. This two year project addressed LED chip and package efficiency improvements to establish a technology platform suitable for low-cost, high-efficiency commercial luminaires. Novel photonic-crystal LEDs were developed to improve the light extraction efficiency of blue GaN-based LEDs compared to the baseline technology. Improved packaging designs that reduced down-conversion and absorption related light losses, led to a higher overall LED efficiency. Specifically, blue LEDs were demonstrated with light output nearing 600 mW and an external quantum efficiency greater than 60 percent (using 1 mm2 chips at an operating current of 350 mA). The results were achieved using a novel, production capable photonic-crystal LED fabrication process. These LEDs formed the basis for a multi-chip white lamp module prototype, which provided 510 lumens light output at a correlated color temperature (CCT) of 3875 K and an operating current of 350 mA per 1mm2 chip. The overall conversion efficiency at 4100 K improved to ~ 65%. The resulting efficacy is 112 lumens per watt (LPW) a 33% improvement over the start of the project. In addition, a proof-of-concept luminaire was demonstrated that provided a flux of 1700 lumens at a 3842 K CCT.

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

    DOE Patents [OSTI]

    Forrest, Stephen (Ann Arbor, MI); Kanno, Hiroshi (Osaka, JP)

    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).

  3. 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

  4. 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.

  5. LOW-COST LED LUMINAIRE FOR GENERAL ILLUMINATION

    SciTech Connect (OSTI)

    Lowes, Ted

    2014-07-31

    During this two-year Solid-State Lighting (SSL) Manufacturing R&D project Cree developed novel light emitting diode (LED) technologies contributing to a cost-optimized, efficient LED troffer luminaire platform emitting at ~3500K correlated color temperature (CCT) at a color rendering index (CRI) of >90. To successfully achieve program goals, Cree used a comprehensive approach to address cost reduction of the various optical, thermal and electrical subsystems in the luminaire without impacting performance. These developments built on Cree’s high- brightness, low-cost LED platforms to design a novel LED component architecture that will enable low-cost troffer luminaire designs with high total system efficacy. The project scope included cost reductions to nearly all major troffer subsystems as well as assembly costs. For example, no thermal management components were included in the troffer, owing to the optimized distribution of compact low- to mid-power LEDs. It is estimated that a significant manufacturing cost savings will result relative to Cree’s conventional troffers at the start of the project. A chief project accomplishment was the successful development of a new compact, high-efficacy LED component geometry with a broad far-field intensity distribution and even color point vs. emission angle. After further optimization and testing for production, the Cree XQ series of LEDs resulted. XQ LEDs are currently utilized in Cree’s AR series troffers, and they are being considered for use in other platforms. The XQ lens geometry influenced the independent development of Cree’s XB-E and XB-G high-voltage LEDs, which also have a broad intensity distribution at high efficacy, and are finding wide implementation in Cree’s omnidirectional A-lamps.

  6. High Efficiency LED Lamp for Solid-State Lighting

    SciTech Connect (OSTI)

    James Ibbetson

    2006-12-31

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency, solid-state lamps based on gallium nitride/silicon carbide light-emitting diodes. Novel chip designs and fabrication processes are described for a new type of nitride light-emitting diode with the potential for very high efficiency. This work resulted in the demonstration of blue light-emitting diodes in the one watt class that achieved up to 495 mW of light output at 350 mA drive current, corresponding to quantum and wall plug efficiencies of 51% and 45%, respectively. When combined with a phosphor in Cree's 7090 XLamp package, these advanced blue-emitting devices resulted in white light-emitting diodes whose efficacy exceeded 85 lumens per watt. In addition, up to 1040 lumens at greater than 85 lumens per watt was achieved by combining multiple devices to make a compact white lamp module with high optical efficiency.

  7. 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.

  8. Use of Occupancy Sensors in LED Parking Lot and Garage Applications: Early Experiences

    SciTech Connect (OSTI)

    Kinzey, Bruce R.; Myer, Michael; Royer, Michael P.; Sullivan, Greg P.

    2012-11-07

    Occupancy sensor systems are gaining traction as an effective technological approach to reducing energy use in exterior commercial lighting applications. Done correctly, occupancy sensors can substantially enhance the savings from an already efficient lighting system. However, this technology is confronted by several potential challenges and pitfalls that can leave a significant amount of the prospective savings on the table. This report describes anecdotal experiences from field installations of occupancy sensor controlled light-emitting diode (LED) lighting at two parking structures and two parking lots. The relative levels of success at these installations reflect a marked range of potential outcomes: from an additional 76% in energy savings to virtually no additional savings. Several issues that influenced savings were encountered in these early stage installations and are detailed in the report. Ultimately, care must be taken in the design, selection, and commissioning of a sensor-controlled lighting installation, else the only guaranteed result may be its cost.

  9. LED Surgical Task Lighting Scoping Study: A Hospital Energy Alliance Project

    SciTech Connect (OSTI)

    Tuenge, Jason R.

    2011-01-17

    Tungsten-halogen (halogen) lamps have traditionally been used to light surgical tasks in hospitals, even though they are in many respects ill-suited to the application due to the large percentage of radiant energy outside the visible spectrum and issues with color rendering/quality. Light-emitting diode (LED) technology offers potential for adjustable color and improved color rendition/quality, while simultaneously reducing side-effects from non-visible radiant energy. It also has the potential for significant energy savings, although this is a fairly narrow application in the larger commercial building energy use sector. Based on analysis of available products and Hospital Energy Alliance member interest, it is recommended that a product specification and field measurement procedure be developed for implementation in demonstration projects.

  10. 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.

  11. 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.

  12. LED exit signs: Improved technology leads the way to energy savings

    SciTech Connect (OSTI)

    Sardinsky, R.; Hawthorne, S.

    1994-12-31

    Recent innovations in light-emitting diode (LED) exit signs may make LED signs the best choice among the energy efficient options available. In the past, LED signs have offered low power consumption, projected long lamp life, and low maintenance requirements. Now, the best of the LED signs also offer improved optical designs that reduce their already low power consumption while improving visibility and appearance, and even reduce their cost. LED exit signs are gaining market share, and E Source expects this technology to eventually dominate over incandescent, compact fluorescent, and electroluminescent signs. More research is needed, however, to confirm manufacturers` claims of 20-year operating lives for LED signs. Conservative estimates place the number of exit signs in US buildings at about 40 million. Although each sign represents a very small part of a building`s load, exit signs are ready targets for energy efficiency upgrades -- they operate continuously and most use inefficient incandescent sources. With an LED sign, annual energy and maintenance costs can be reduced by more than 90 percent compared to a typical incandescent sign. Low annual costs help to offset the LED sign`s relatively high first cost. More than 25 utilities offer DSM incentives for energy efficient exit signs, and efficient alternatives are becoming more readily available. Recent improvements in optical designs enable many LED signs to visually out perform other sources. In addition to these benefits, LED exit signs have lower life cycle cost than most other options. The biggest barrier to their success, however, is that their first cost has been considerably higher than competing technologies. LED sign prices are falling rapidly, though, because manufacturers are continually improving optical designs of the fixtures to use fewer LEDs and thus even less energy while providing better performance.

  13. 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...

  14. 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.

  15. 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.

  16. Energy Department Announces $10 Million to Advance Innovative...

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

    This funding will help accelerate the development of high-quality light-emitting diode (LED) and organic light-emitting diode (OLED) products with the potential to reduce lighting ...

  17. Development and Industrialization of InGaN/GaN LEDs on Patterned Sapphire Substrates for Low Cost Emitter Architecture

    SciTech Connect (OSTI)

    Flemish, Joseph; Soer, Wouter

    2015-11-30

    Patterned sapphire substrate (PSS) technology has proven to be an effective approach to improve efficacy and reduce cost of light-emitting diodes (LEDs). The volume emission from the transparent substrate leads to high package efficiency, while the simple and robust architecture of PSS-based LEDs enables low cost. PSS substrates have gained wide use in mid-power LEDs over the past years. In this project, Lumileds has developed and industrialized PSS and epitaxy technology for high- power flip-chip LEDs to bring these benefits to a broader range of applications and accelerate the adoption of energy-efficient solid-state lighting (SSL). PSS geometries were designed for highly efficient light extraction in a flip-chip architecture and high-volume manufacturability, and corresponding sapphire patterning and epitaxy manufacturing processes were integrally developed. Concurrently, device and package architectures were developed to take advantage of the PSS flip-chip die in different types of products that meet application needs. The developed PSS and epitaxy technology has been fully implemented in manufacturing at Lumileds’ San Jose, CA location, and incorporated in illumination-grade LED products that have been successfully introduced to the market, including LUXEON Q and LUXEON FlipChip White.

  18. Evaluation of Metal Halide, Plasma, and LED Lighting Technologies for a Hydrogen Fuel Cell Mobile Light (H 2 LT)

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

    Miller, L. B.; Donohoe, S. P.; Jones, M. H.; White, W. A.; Klebanoff, L. E.; Velinsky, S. A.

    2015-04-22

    This article reports on the testing and comparison of a prototype hydrogen fuel cell light tower (H2LT) and a conventional diesel-powered metal halide light trailer for use in road maintenance and construction activities. The prototype was originally outfitted with plasma lights and then with light-emitting diode (LED) luminaires. Light output and distribution, lighting energy efficiency (i.e., efficacy), power source thermal efficiency, and fuel costs are compared. The metal halide luminaires have 2.2 and 3.1 times more light output than the plasma and LED luminaires, respectively, but they require more power/lumen to provide that output. The LED luminaires have 1.6 timesmore » better light efficacy than either the metal halide or plasma luminaires. The light uniformity ratios produced by the plasma and LED towers are acceptable. The fuel cell thermal efficiency at the power required to operate the plasma lights is 48%, significantly higher than the diesel generator efficiency of 23% when operating the metal halide lights. Due to the increased efficiency of the fuel cell and the LED lighting, the fuel cost per lumen-hour of the H2LT is 62% of the metal halide diesel light tower assuming a kilogram of hydrogen is twice the cost of a gallon of diesel fuel.« less

  19. 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...

  20. Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers

    DOE Patents [OSTI]

    Tansu, Nelson; Chan, Helen M; Vinci, Richard P; Ee, Yik-Khoon; Biser, Jeffrey

    2013-09-24

    The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

  1. Feedback-Controlled LED Photobioreactor for Photophysiological Studies of Cyanobacteria

    SciTech Connect (OSTI)

    Melnicki, Matthew R.; Pinchuk, Grigoriy E.; Hill, Eric A.; Kucek, Leo A.; Stolyar, Sergey; Fredrickson, Jim K.; Konopka, Allan; Beliaev, Alex S.

    2013-04-09

    A custom photobioreactor (PBR) was designed to enable automatic light adjustments using computerized feedback control. A black anodized aluminum enclosure, constructed to surround the borosilicate reactor vessel, prevents the transmission of ambient light and serves as a mount for arrays of light-emitting diodes (LEDs). The high-output LEDs provide narrow-band light of either 630 or 680 nm for preferential excitation of the cyanobacterial light-harvesting pigments, phycobilin or chlorophyll a, respectively. Custom developed software BioLume provides automatic control of optical properties and a computer feedback loop can automatically adjust the incident irradiance as necessary to maintain a fixed transmitted light through the culture, based on user-determined set points. This feedback control serves to compensate for culture dynamics which have optical effects, (e.g., changing cell density, pigment adaptations) and thus can determine the appropriate light conditions for physiological comparisons or to cultivate light-sensitive strains, without prior analyses. The LED PBR may also be controlled as a turbidostat, using a feedback loop to continuously adjust the rate of media-dilution based on the transmitted light measurements, with a fast and precise response. This cultivation system gains further merit as a high-performance analytical device, using non-invasive tools (e.g., dissolved gas sensors, online mass spectrometry) to automate real-time measurements, thus permitting unsupervised experiments to search for optimal growth conditions, to monitor physiological responses to perturbations, as well as to quantitate photophysiological parameters using an in situ light-saturation response routine.

  2. A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements

    SciTech Connect (OSTI)

    Wang, Hongtao; Salthouse, Christopher D.; Qi, Ying; Mountziaris, T. J.; Chemical Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003

    2014-05-15

    Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve the peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.

  3. Impact of photonic crystals on LED light extraction efficiency: approaches and limits to vertical structure designs

    SciTech Connect (OSTI)

    Matioli, Elison; Weisbuch, Claude

    2010-08-19

    The enhancement of the extraction efficiency in light emitting diodes (LEDs) through the use of photonic crystals (PhCs) requires a structure design that optimizes the interaction of the guided modes with the PhCs. The main optimization parameters are related to the vertical structure of the LED, such as the thickness of layers, depth of the PhCs, position of the quantum wells as well as the PhC period and fill factor. We review the impact of the vertical design of different approaches of PhC LEDs through a theoretical and experimental standpoint, assessing quantitatively the competing mechanisms that act over each guided mode. Three approaches are described to overcome the main limitation of LEDs with surface PhCs, i.e. the insufficient interaction of low order guided modes with the PhCs. The introduction of an AlGaN confining layer in such structure is shown to be effective in extracting a fraction of the optical energy of low order modes; however, this approach is limited by the growth of the lattice mismatched AlGaN layer on GaN. The second approach, based on thin-film LEDs with PhCs, is limited by the presence of an absorbing reflective metal layer close to the guided modes that plays a major role in the competition between PhC extraction and metal dissipation. Finally, we demonstrate both experimentally and theoretically the superior extraction of the guided light in embedded PhC LEDs due to the higher interaction between all optical modes and the PhCs, which resulted in a close to unity extraction efficiency for this device. The use of high-resolution angle-resolved measurements to experimentally determine the PhC extraction parameters was an essential tool for corroborating the theoretical models and quantifying the competing absorption and extraction mechanisms in LEDs.

  4. Performance of T12 and T8 Fluorescent Lamps and Troffers and LED Linear Replacement Lamps CALiPER Benchmark Report

    SciTech Connect (OSTI)

    Myer, Michael; Paget, Maria L.; Lingard, Robert D.

    2009-01-16

    The Department of Energy (DOE) Commercially Available LED Product Evaluation and Reporting (CALiPER) Program was established in 2006 to investigate the performance of light-emitting diode (LED) based luminaires and replacement lamps. To help users better compare LED products with conventional lighting technologies, CALiPER has also performed benchmark research and testing of traditional (i.e., non-LED) lamps and fixtures. This benchmark report addresses standard 4-foot fluorescent lamps (i.e., T12 and T8) and the 2-foot by 4-foot recessed troffers in which they are commonly used. This report also examines available LED replacements for T12 and T8 fluorescent lamps, and their application in fluorescent troffers. The construction and operation of linear fluorescent lamps and troffers are discussed, as well as fluorescent lamp and fixture performance, based on manufacturer data and CALiPER benchmark testing. In addition, the report describes LED replacements for linear fluorescent lamps, and compares their bare lamp and in situ performance with fluorescent benchmarks on a range of standard lighting measures, including power usage, light output and distribution, efficacy, correlated color temperature, and the color rendering index. Potential performance and application issues indicated by CALiPER testing results are also examined.

  5. Demonstration of LED Retrofit Lamps at the Jordan Schnitzer Museum of Art

    SciTech Connect (OSTI)

    Miller, Naomi J.

    2011-09-01

    The Jordan Schnitzer Museum of Art in Eugene, Oregon, houses a remarkable permanent collection of Asian art and antiquities, modern art, and sculpture, and also hosts traveling exhibitions. In the winter and spring of 2011, a series of digital photographs by artist Chris Jordan, titled "Running the Numbers," was exhibited in the Coeta and Donald Barker Special Exhibitions Gallery. These works graphically illustrate waste (energy, money, health, consumer objects, etc.) in contemporary culture. The Bonneville Power Administration and the Eugene Water and Electricity Board provided a set of Cree 12W light-emitting diode (LED) PAR38 replacement lamps (Cree LRP38) for the museum to test for accent lighting in lieu of their standard Sylvania 90W PAR38 130V Narrow Flood lamps (which draw 78.9W at 120V). At the same time, the museum tested LED replacement lamps from three other manufacturers, and chose the Cree lamp as the most versatile and most appropriate color product for this exhibit. The lamps were installed for the opening of the show in January 2011. This report describes the process for the demonstration, the energy and economic results, and results of a survey of the museum staff and gallery visitors on four similar clusters of art lighted separately by four PAR38 lamps.

  6. Revolutionary Method for Increasing the Efficiency of White Light Quantum Dot LEDs

    SciTech Connect (OSTI)

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which respec-tively diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal proc-essing (PTP), reduces the number of point defects while main-taining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of the quantum dot nanoparticles. The cur-rent research uses a thermal model to predict annealing tempera-tures during PTP and demonstrates up to a 300% increase in pho-toluminescence for QDs on passive substrates

  7. 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.

  8. 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.

  9. Evaluation of Metal Halide, Plasma, and LED Lighting Technologies for a Hydrogen Fuel Cell Mobile Light (H 2 LT)

    SciTech Connect (OSTI)

    Miller, L. B.; Donohoe, S. P.; Jones, M. H.; White, W. A.; Klebanoff, L. E.; Velinsky, S. A.

    2015-04-22

    This article reports on the testing and comparison of a prototype hydrogen fuel cell light tower (H2LT) and a conventional diesel-powered metal halide light trailer for use in road maintenance and construction activities. The prototype was originally outfitted with plasma lights and then with light-emitting diode (LED) luminaires. Light output and distribution, lighting energy efficiency (i.e., efficacy), power source thermal efficiency, and fuel costs are compared. The metal halide luminaires have 2.2 and 3.1 times more light output than the plasma and LED luminaires, respectively, but they require more power/lumen to provide that output. The LED luminaires have 1.6 times better light efficacy than either the metal halide or plasma luminaires. The light uniformity ratios produced by the plasma and LED towers are acceptable. The fuel cell thermal efficiency at the power required to operate the plasma lights is 48%, significantly higher than the diesel generator efficiency of 23% when operating the metal halide lights. Due to the increased efficiency of the fuel cell and the LED lighting, the fuel cost per lumen-hour of the H2LT is 62% of the metal halide diesel light tower assuming a kilogram of hydrogen is twice the cost of a gallon of diesel fuel.

  10. GaN-Ready Aluminum Nitride Substrates for Cost-Effective, Very Low Dislocation Density III-Nitride LED's

    SciTech Connect (OSTI)

    Sandra Schujman; Leo Schowalter

    2010-10-15

    The objective of this project was to develop and then demonstrate the efficacy of a costeffective approach for a low defect density substrate on which AlInGaN LEDs can be fabricated. The efficacy of this GaN-ready substrate would then be tested by growing high efficiency, long lifetime InxGa1-xN blue LEDs. The approach used to meet the project objectives was to start with low dislocation density AlN single-crystal substrates and grow graded AlxGa1-xN layers on top. Pseudomorphic AlxGa1-xN epitaxial layers grown on bulk AlN substrates were used to fabricate light emitting diodes and demonstrate better device performance as a result of the low defect density in these layers when benched marked against state-of-the-art LEDs fabricated on sapphire substrates. The pseudomorphic LEDs showed excellent output powers compared to similar wavelength devices grown on sapphire substrates, with lifetimes exceeding 10,000 hours (which was the longest time that could reliably be estimated). In addition, high internal quantum efficiencies were demonstrated at high driving current densities even though the external quantum efficiencies were low due to poor photon extraction. Unfortunately, these pseudomorphic LEDs require high Al content so they emit in the ultraviolet. Sapphire based LEDs typically have threading dislocation densities (TDD) > 108 cm-2 while the pseudomorphic LEDs have TDD ? 105 cm-2. The resulting TDD, when grading the AlxGa1-xN layer all the way to pure GaN to produce a GaN-ready substrate, has varied between the mid 108 down to the 106 cm-2. These inconsistencies are not well understood. Finally, an approach to improve the LED structures on AlN substrates for light extraction efficiency was developed by thinning and roughening the substrate.

  11. The photocatalysis of Bi{sub 2}MoO{sub 6} under the irradiation of blue LED

    SciTech Connect (OSTI)

    Sun, Yuanyuan; Wang, Wenzhong Zhang, Ling; Sun, Songmei

    2013-10-15

    Graphical abstract: - Highlights: • ·OH trap and hole sink were involved to investigate the active radicals. • Holes play a more important role in the degradation of RhB. • The ·OH were related to the decomposition of phenol. • The ·O{sub 2}-played a leading role in the photodegradation of phenol. • Blue LED is competitive and promising alternative for the future application. - Abstract: Bi{sub 2}MoO{sub 6} has been reported as a promising photocatalyst in wastewater treatment. The active radicals generated over the Bi{sub 2}MoO{sub 6} during the photocatalytic process were thought to be hydroxyl radical (·OH) but have not been proved. Herein, Bi{sub 2}MoO{sub 6} with nanoplate like morphology was synthesized and its photocatalytic performances in the degradation of rhodamine B (RhB) and phenol as colored and colorless model pollutants respectively were evaluated under the irradiation of blue light emitting diode (LED). The tert-butyl alcohol (TBA) as a ·OH trap and ethylene diamine tetraacetic acid (EDTA) as a hole sink were involved to investigate the main active groups that are generated on Bi{sub 2}MoO{sub 6} and function during the photodegradation of RhB and phenol. In addition, it is a competitive and promising alternative plan to use blue LED as light source for the future practical application in environmental remediation.

  12. Detroit Street Lighting Report | Department of Energy

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

    2015restoring-detroit.pdf More Documents & Publications LED Roadway Lighting OCTOBER 2015 POSTINGS Demonstration Assessment of Light Emitting Diode (LED) Street Lighting, Final ...

  13. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject led, ssl, solid-state, lighting, gateway, caliper, report, color, shift, maintenance (1) light-emitting diode (led), color shift, color stability, ...

  14. Energy Department Offers $10 Million for Energy-Saving Lighting...

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

    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 ...

  15. 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.

  16. 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.

  17. LED Lightbulbs

    Broader source: Energy.gov [DOE]

    All of these lightbulbs meet the new energy standards that take effect from 2012–2014. These LED bulbs use about 75%–80% less energy than traditional bulbs.

  18. High-Efficiency Non-Polar GaN-Based LEDs

    SciTech Connect (OSTI)

    Paul Fini

    2010-11-30

    Inlustra Technologies with subcontractor U.C. Santa Barbara conducted a project with the principle goal of demonstrating high internal quantum efficiency blue (430 nm) and green (540nm) light emitting diodes (LEDs) on low-defect density non-polar GaN wafers. Inlustra pursued the fabrication of smooth thick a-plane and m-plane GaN films, as well as defect reduction techniques such as lateral epitaxial overgrowth (LEO) to uniformly lower dislocation density in these films. Limited free-standing wafers were produced as well. By the end of the reporting period, Inlustra had met its milestone of dislocation reduction to < 5 x 10{sup 6} cm{sup -2}. Stacking faults were still present in appreciable density ({approx} 1 x 10{sup 5} cm{sup -1}), but were not the primary focus of defect reduction since there have been no published studies establishing their detrimental effects on LED performance. Inlustra's LEO progress built a solid foundation upon which further commercial development of GaN substrates will occur. UCSB encountered multiple delays in its LED growth and fabrication efforts due to unavoidable facilities outages imposed by ongoing construction in an area adjacent to the metalorganic chemical vapor deposition (MOCVD) laboratory. This, combined with the large amount of ab initio optimization required for the MOCVD system used during the project, resulted in unsatisfactory LED progress. Although numerous blue-green photoluminescence results were obtained, only a few LED structures exhibited electroluminescence at appreciable levels. UCSB also conducting extensive modeling (led by Prof. Van de Walle) on the problem of non-radiative Auger recombination in GaN-based LED structures, which has been posited to contribute to LED efficiency 'droop' at elevated current density. Unlike previous modeling efforts, UCSB's approach was truly a first-principles ab initio methodology. Building on solid numerical foundations, the Auger recombination rates of In{sub x}Ga{sub 1-x}N alloys were calculated from first-principles density-functional and many-body-perturbation theory. The differing mechanisms of inter- and intra-band recombination were found to affect different parts of the emission spectrum. In the blue to green spectral region and at room temperature the Auger coefficient was calculated to be as large as 2 x 10{sup -30} cm{sup 6} s{sup -1}; in the infrared it is even larger. These results indicated that Auger recombination may be responsible for the loss of quantum efficiency that affects InGaN-based light emitters, whether on non-polar or polar crystal planes.

  19. OSTI, US Dept of Energy, Office of Scientific and Technical Informatio...

    Office of Scientific and Technical Information (OSTI)

    ... a wide variety of home, business, and industrial products such as holiday lighting, ... Related Topics: cumulative energy, energy star, LED, Light-emitting diode, lighting, ...

  20. 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...

  1. Mapping the Nanoscale Landscape

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

    helps explain the efficient performance of polymer-based light-emitting diodes (LEDs) and will lead to a new avenue of research on organic electronic devices, supporting...

  2. 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...

  3. 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 ...

  4. ADEPS Vitae Vitae Experimental Physical Sciences

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

    One of Bauer's most enjoyable projects involves fabricating and coating photonic crystals for developing new lighting materials, for light-emitting diode (LED) applications, as ...

  5. Sensors & Optical Diagnostics

    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 ...

  6. 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 ...

  7. Energy Department Announces Winners of Next Generation Luminaires...

    Energy Savers [EERE]

    was launched in 2008 to promote technological innovation and excellence in the design of energy efficient light-emitting diode (LED) commercial lighting fixtures, or "luminaires." ...

  8. Portland Street Lighting Report (August 2015) | Department of...

    Energy Savers [EERE]

    More Documents & Publications OCTOBER 2015 POSTINGS Detroit Street Lighting Report Demonstration Assessment of Light Emitting Diode (LED) Street Lighting, Final Report

  9. 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 ...

  10. CRF

    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. lighting in the library

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

    lighting will be examined here: * replacing incandescent bulbs with compact fluorescent lamps * replacing incandescent exit signs with those lit by light emitting diodes (LED) * ...

  12. 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...

  13. "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:...

  14. 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...

  15. Energy 101: Lighting Choices | Department of Energy

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

    Upgrading 15 of the inefficient incandescent light bulbs in your home to energy-saving incandescent, compact fluorescent lamp (CFL), or light emitting diode (LED) bulbs could save ...

  16. 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...

  17. 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...

  18. 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...

  19. "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...

  20. 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...

  1. Crystal Chemistry and Luminescence of Ce3+ -Doped Lu2CaMg2(Si,Ge)3O12 and Its Use in LED Based Lighting

    SciTech Connect (OSTI)

    Setlur,A.; Heward, W.; Gao, Y.; Srivastava, A.; Chandron, R.; Shankar, M.

    2006-01-01

    In this paper, we describe the formation and luminescence of a new garnet phosphor for light emitting diode (LED) based lighting, Lu{sub 2}CaMg{sub 2}(Si,Ge){sub 3}O{sub 12}:Ce{sup 3+}.The regions for garnet phase formation are initially described with respect to larger rare earth substitution and show reasonable correlation to previous crystal chemistry studies for the garnet parent structure. While the pure silicate phosphor also has apatite second phases, a significant amount of Ce{sup 3+} enters the garnet phase, giving Ce{sup 3+} luminescence that is significantly redder when compared to typical Al{sup 3+} garnet phosphors with quantum efficiencies comparable to commercial Ce{sup 3+} garnet phosphors. Potential reasons for the emission red shift and the high quantum efficiency are discussed. Finally, the performance of these new phosphors is tested within LED based lamps. Lamps using these phosphors can reach color temperatures required for general illumination lighting and also have comparable phosphor conversion efficiencies when compared to lamps using typical garnet phosphors.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Expandable LED array interconnect

    SciTech Connect (OSTI)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  7. 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...

  8. Prediction of Lumen Output and Chromaticity Shift in LEDs Using Kalman Filter and Extended Kalman Filter Based Models

    SciTech Connect (OSTI)

    Lall, Pradeep; Wei, Junchao; Davis, J Lynn

    2014-06-24

    Abstract Solid-state lighting (SSL) luminaires containing light emitting diodes (LEDs) have the potential of seeing excessive temperatures when being transported across country or being stored in non-climate controlled warehouses. They are also being used in outdoor applications in desert environments that see little or no humidity but will experience extremely high temperatures during the day. This makes it important to increase our understanding of what effects high temperature exposure for a prolonged period of time will have on the usability and survivability of these devices. Traditional light sources burn out at end-of-life. For an incandescent bulb, the lamp life is defined by B50 life. However, the LEDs have no filament to burn. The LEDs continually degrade and the light output decreases eventually below useful levels causing failure. Presently, the TM-21 test standard is used to predict the L70 life of LEDs from LM-80 test data. Several failure mechanisms may be active in a LED at a single time causing lumen depreciation. The underlying TM-21 Model may not capture the failure physics in presence of multiple failure mechanisms. Correlation of lumen maintenance with underlying physics of degradation at system-level is needed. In this paper, Kalman Filter (KF) and Extended Kalman Filters (EKF) have been used to develop a 70-percent Lumen Maintenance Life Prediction Model for LEDs used in SSL luminaires. Ten-thousand hour LM-80 test data for various LEDs have been used for model development. System state at each future time has been computed based on the state space at preceding time step, system dynamics matrix, control vector, control matrix, measurement matrix, measured vector, process noise and measurement noise. The future state of the lumen depreciation has been estimated based on a second order Kalman Filter model and a Bayesian Framework. Life prediction of L70 life for the LEDs used in SSL luminaires from KF and EKF based models have been compared with the TM-21 model predictions and experimental data.

  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. Biomedical device potential for robust, implantable product

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

    Light-emitting nanocrystal diodes go ultraViolet Light-emitting nanocrystal diodes go ultraviolet A team of scientists has developed a process for creating glass-based, inorganic light-emitting diodes (LEDs) that produce light in the ultraviolet range. February 24, 2012 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to

  11. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    SciTech Connect (OSTI)

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped phosphor particles are used. This spherical morphology will result in better light extraction and so an improvement of efficiency in the overall device. Cabot is a 2.5 billion dollar company that makes specialized materials using propriety spray based technologies. It is a core competency of Cabot's to exploit the spray based technology and resulting material/morphology advantages. Once a business opportunity is clearly identified, Cabot is positioned to increase the scale of the production to meet opportunity's need. Cabot has demonstrated the capability to make spherical morphology micron-sized phosphor powders by spray based routes for PDP and CRT applications, but the value proposition is still unproven for LED applications. Cabot believes that the improvements in phosphor powders yielded by their process will result in a commercial advantage over existing technologies. Through the SSL project, Cabot has produced a number of different compositions in a spherical morphology that may be useful for solid state lights, as well as demonstrated processes that are able to produce particles from 10 nanometers to 3 micrometers. Towards the end of the project we demonstrated that our process produces YAG:Ce powder that has both higher internal quantum efficiency (0.6 compared to 0.45) and external quantum efficiency (0.85 compared to 0.6) than the commercial standard (see section 3.4.4.3). We, however, only produced these highly bright materials in research and development quantities, and were never able to produce high quantum efficiency materials in a reproducible manner at a commercial scale.

  12. 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.

  13. 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.

  14. Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

    SciTech Connect (OSTI)

    Calciati, Marco; Vallone, Marco; Zhou, Xiangyu; Ghione, Giovanni; Goano, Michele Bertazzi, Francesco; Meneghini, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico; Verzellesi, Giovanni; Zhu, Dandan; Humphreys, Colin

    2014-06-15

    Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10{sup −30} cm{sup 6}/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary attempt at uncertainty quantification confirms, beyond the present case, the need for an improved description of carrier transport and microscopic radiative and nonradiative recombination mechanisms in device-level LED numerical models.

  15. LED Lightbulbs | Department of Energy

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

    Image icon LED lightbulbs

  16. 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

  17. Blog | Department of Energy

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

    About LEDs Counting down the top facts about light-emitting diodes. Read on to test your LED knowledge. May 29, 2013 Home solar systems can save you energy and money. | Photo...

  18. When to Turn Off Your Lights | Department of Energy

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

    are not already factored into the rate. LED Lighting The operating life of a light emitting diode (LED) is unaffected by turning it on and off. While lifetime is reduced for...

  19. Solid-State Lighting Patents Resulting from DOE-Funded Projects

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

    of Efficient Optical Devices * Nitride LEDs Based on Flat and Wrinkled Quantum Wells Cree, Inc. * Light Emitting Diode with Porous SiC Substrate and Method for Fabricating * LED ...

  20. Central Park in New York City Myer, Michael; Goettel, Russell...

    Office of Scientific and Technical Information (OSTI)

    (LED) Post-Top Lighting at Central Park in New York City Myer, Michael; Goettel, Russell T.; Kinzey, Bruce R. GATEWAY; Central Park; lighting; LED; light-emitting diode; post-top...

  1. 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.

  2. 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.

  3. 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.

  4. LED Color Characteristics

    SciTech Connect (OSTI)

    2012-01-01

    Color quality is an important consideration when evaluating LED-based products for general illumination. This fact sheet reviews the basics regarding light and color and summarizes the most important color issues related to white-light LED systems.

  5. Energy Efficiency of LEDs

    Broader source: Energy.gov [DOE]

    This fact sheet discusses the current state of the LED market and discusses package efficacy, luminaire efficacy, and application efficacy.

  6. Cree LED Lighting Solutions Formerly LED Lighting Fixtures LLF...

    Open Energy Info (EERE)

    LED Lighting Solutions Formerly LED Lighting Fixtures LLF Jump to: navigation, search Name: Cree LED Lighting Solutions (Formerly LED Lighting Fixtures (LLF)) Place: Morrisville,...

  7. LED MR16 Lamps

    SciTech Connect (OSTI)

    2012-07-01

    Solid-state lighting program technology fact sheet that describes the performance of LED MR16 lamps and discusses electronic compatibility concerns.

  8. LED Color Stability

    SciTech Connect (OSTI)

    2014-03-01

    DOE Solid-State Lighting program technology fact sheet that addresses key questions about color stability and color shift in LED lighting applications.

  9. LED Color Characteristics

    Broader source: Energy.gov [DOE]

    Reviews the fundamentals regarding light and color, summarizing the most important color issues related to white-light LED systems. (6 pages, April 2016)

  10. General Service LED Lamps

    Broader source: Energy.gov [DOE]

    A U.S. DOE SSL technology fact sheet that compares general service LED light bulbs with incandescent and CFL bulbs.

  11. Recessed LED Downlights

    SciTech Connect (OSTI)

    2012-05-01

    Solid-state lighting program technology fact sheet that briefly discusses different LED product types and their performance relative to downlights utilizing traditional lamps.

  12. General Service LED Lamps

    SciTech Connect (OSTI)

    2012-04-01

    Solid-state lighting program technology fact sheet that compares general service incandescent lamps—i.e., light bulbs—to LED and CFL alternatives.

  13. Establishing LED Equivalency

    SciTech Connect (OSTI)

    2011-10-01

    Solid-state lighting program technology fact sheet that provides guidance for comparing products based on LED or other light source technologies.

  14. CALiPER Summary of Results. Round 13 of Product Testing

    SciTech Connect (OSTI)

    none,

    2011-10-01

    The Department of Energy (DOE) Commercially Available Light-Emitting Diode (LED) Product Evaluation and Reporting (CALiPER) Program has been purchasing and testing general illumination solid-state lighting (SSL) products since 2006.

  15. CX-002420: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Traffic Signal Light Emitting Diode (LED) RetrofitCX(s) Applied: B1.32, B5.1Date: 05/17/2010Location(s): Attleboro, MassachusettsOffice(s): Energy Efficiency and Renewable Energy

  16. CX-003723: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    LED (Light-Emitting Diode) Traffic Signal UpgradeCX(s) Applied: B5.1Date: 09/15/2010Location(s): Nassau County, New YorkOffice(s): Energy Efficiency and Renewable Energy, Golden Field Office

  17. Final_Testimony(20).pdf

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

    of four Americans say they have replaced inefficient bulbs with compact fluorescent lights (CFLs) or light-emitting diodes (LEDs) over the last few years, and 84 percent of...

  18. News | Department of Energy

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

    their invention of the blue light emitting diode, a game-changer in the history of LED lights. | Photo courtesy of Soraa. Energy-Department Supported Scientist Receives Nobel Prize...

  19. Energy Department Announces $10 Million for Innovative, Energy...

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

    an estimated energy savings of 1.8 billion in 2013. Solid-state lighting technologies, which include both LED and organic light emitting diode technologies, have the potential to ...

  20. (Lighting and) Solid-State Lighting: Science, Technology, Economic...

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

    ... Topics cover the basics of light-emitting diode (LED) operation; a 200-year history of lighting technology; the importance of white light and color vision to the evolutionary ...

  1. Microsoft Word - DOE-ID-INL-16-002.docx

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

    The upper lift station would be removed entirely. Finally, for convenience and proper lighting, a new Light-emitting diode (LED) light fixture would be added to the maintenance ...

  2. School Energy Survey Student Guide

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

    of 40 new power plants. INCANDESCENT BULB HALOGEN COMPACT FLUORESCENT (CFL) LIGHT EMITTING DIODE (LED) Brightness 850 lumens 850 lumens 850 lumens 850 lumens Life of Bulb 1,000...

  3. Say Hello to Stricter TV Standards | Department of Energy

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

    past couple of years to reduce the power consumption of TVs. For example, LED (light emitting diode) technology is expected to be the leading backlight technology for LCD TV sets...

  4. School Energy Survey Teacher Guide

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

    Key Student Guide Page 20 INCANDESCENT BULB HALOGEN COMPACT FLUORESCENT (CFL) LIGHT EMITTING DIODE (LED) Number of bulbs to get 25,000 hours 25 8.3 2.5 1 Cost of bulbs for 25,000...

  5. OSTI, US Dept of Energy, Office of Scientific and Technical Informatio...

    Office of Scientific and Technical Information (OSTI)

    Light-emitting diode Topic Enjoy the benefits of LED lighting by Kathy Chambers 30 Dec, 2013 in Products and Content Source: http:www.flickr.comphotosuscapitol6309229615in...

  6. Sandia Energy - III-Nitride core-shell nanowire arrayed solar...

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

    for other III-nitride devices such as light-emitting diodes (LEDs). Abstract: A solar cell based on a hybrid nanowire-film architecture consisting of a vertically aligned...

  7. OptoElectronix Inc | Open Energy Information

    Open Energy Info (EERE)

    is a San Jose-headquartered developer and manufacturer of Light Emitting Diode (LED) products. References: OptoElectronix, Inc.1 This article is a stub. You can help...

  8. Solid-State Lighting Patents Resulting from DOE-Funded Projects

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

    Cree, Inc. * Light Emitting Diode with Porous SiC Substrate and Method for Fabricating * LED Package Element with Internal Meniscus for Bubble-Free Hallow Floating Lens Placement * ...

  9. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Demonstration Assessment of Light Emitting Diode LED Post Top Lighting at Central Park in New York City Myer Michael Goettel Russell T Kinzey Bruce R GATEWAY Central Park lighting...

  10. "Title","Creator/Author","Publication Date","OSTI Identifier...

    Office of Scientific and Technical Information (OSTI)

    Demonstration Assessment of Light-Emitting Diode (LED) Post-Top Lighting at Central Park in New York City","Myer, Michael; Goettel, Russell T.; Kinzey, Bruce R.","2012-09-30T04:00:...

  11. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    Jason R 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 waste e...

  12. Revolution Now: The Future Arrives for Four Clean Energy Technologies-- 2014 Update

    Broader source: Energy.gov [DOE]

    This report provides an update and finds that cost reductions and deployment have continued to advance in the past year for onshore wind power, polysilicon photovoltaic (PV) modules, light-emitting diodes (LEDs), and electric vehicles (EVs).

  13. Optical Safety of LEDs

    SciTech Connect (OSTI)

    none,

    2013-06-01

    Solid-state lighting program technology fact sheet that clarifies the issue of LED lighting safety for the human eye and takes a look at current standards for photobiological safety.

  14. LED Frequently Asked Questions

    SciTech Connect (OSTI)

    2011-05-01

    Solid-state lighting program technology fact sheet that provides an overview of what retailers, energy efficiency advocates, and consumers need to know to make informed LED buying decisions.

  15. LED Frequently Asked Questions

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

    ... including 10% post consumer waste. EERE Information Center 1-877-EERE-INFO (1-877-337-3463) www.eere.energy.govinformationcenter Courtesy of CREE. LED downlight showing heat sink.

  16. LED Directional Lamps

    SciTech Connect (OSTI)

    2012-11-01

    Solid-state lighting program technology fact sheet that provides an overview of the current performance of LED PAR-, BR-, R-, and AR-shaped lamps, which were all investigated by CALiPER in 2012.

  17. Energy Efficiency of LEDs

    SciTech Connect (OSTI)

    2013-03-01

    Solid-state lighting program technology fact sheet on energy efficiency of LEDs, characterizing the current state of the market and discussing package efficacy, luminaire efficacy, and application efficacy.

  18. LEd:JCD

    Office of Legacy Management (LM)

    LEd:JCD TO- 54 k-sour R3scsrck Fouadatlon 0f..&+0istlstituta of TecGJlow Tecmolocy Csilter 10 Zest 35th Stmet ', cxk3go lo, I3.Umie Atteqtion: MC. R. c. Barrall Gentlemen: ...

  19. Nanoscale engineering boosts performance of quantum dot light...

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

    Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission...

  20. high-power LEDs

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

    high-power LEDs - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced Nuclear

  1. LEDS | OpenEI Community

    Open Energy Info (EERE)

    LEDS Home Graham7781's picture Submitted by Graham7781(2017) Super contributor 16 November, 2012 - 11:23 LEDS the focus of Monday's 10 a.m. Town Hall Meeting LEDS Town Hall meeting...

  2. 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.

  3. 1

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

    Nanoscale engineering boosts performance of quantum dot light emitting diodes October 25, 2013 Making the light at the end of the tunnel more efficient LOS ALAMOS, N.M., Oct. 25, 2013-Dramatic advances in the field of quantum dot light emitting diodes (QD-LEDs) could come from recent work by the Nanotechnology and Advanced Spectroscopy team at Los Alamos National Laboratory. Quantum dots are nano-sized semiconductor particles whose emission color can be tuned by simply changing their dimensions.

  4. Why SSL | Department of Energy

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

    SSL Basics » Why SSL Why SSL Since 2003, the U.S. Department of Energy has invested with industry partners in research and development of solid-state lighting (SSL)-including both light-emitting diode (LED) and organic light emitting diode (OLED) technologies. Why such concentrated attention on SSL? The answer is simple: because of SSL's rapid ongoing improvements and superior energy-saving potential. It is estimated that switching to SSL could reduce national lighting electricity use by nearly

  5. Doing Business with DOE's Solid-State Lighting Program

    Energy Savers [EERE]

    Doing Business with DOE's Solid-State Lighting Program Solid-state lighting (SSL) is an emerging technology that promises to make a significant impact on solving our nation's energy and environmental challenges. With the promise of being more than ten times as effcient as incandescent lighting and twice as effcient as fuorescent light- ing, SSL products using light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) will mean "greener" homes and businesses that use

  6. Advanced Leds | Open Energy Information

    Open Energy Info (EERE)

    Place: Coventry, England, United Kingdom Zip: CV5 6SP Product: Advanced Leds develops LED technology for outdoor lighting, including street lighting applications. Coordinates:...

  7. Eu{sup 2+}, Mn{sup 2+} co-doped Ba{sub 9}Y{sub 2}Si{sub 6}O{sub 24} phosphors based on near-UV-excitable LED lights

    SciTech Connect (OSTI)

    Kim, Yoejin; Park, Sangmoon

    2014-01-01

    Graphical abstract: - Highlights: • New near-ultraviolet (NUV)-excitable materials composed of Ba{sub 9}Eu{sub m}Mn{sub n}Y{sub 2}Si{sub 6}O{sub 24} (m = 0.01–0.5, n = 0–0.7) were prepared. • High energy-transfer from Eu{sup 2+} to Mn{sup 2+} and their energy-transfer mechanism were discussed. • The co-doping of Eu{sup 2+} and Mn{sup 2+} in the orthosilicate structure resulted in the emission of white light under NUV LED light. - Abstract: New single-phase and near-ultraviolet (NUV)-excitable materials composed of Ba{sub 9}Eu{sub m}Mn{sub n}Y{sub 2}Si{sub 6}O{sub 24} (m = 0.01–0.5, n = 0–0.7) were prepared via a solid-state reaction in reducing atmosphere. X-ray diffraction patterns of the obtained phosphors were examined to index the peak positions. After doping the host structure with Eu{sup 2+} and Mn{sup 2+} emitters, the intense green, white, and orange emission lights that were observed in the photoluminescence spectra under NUV excitation were monitored. The dependence of the luminescent intensity of the Mn{sup 2+} co-doped (n = 0.1–0.7) host lattices on the fixed Eu{sup 2+} content (m = 0.1, 0.3, 0.5) is also investigated. Co-doping Mn{sup 2+} into the Eu{sup 2+}-doped host structure enabled a high energy-transfer from Eu{sup 2+} to Mn{sup 2+} and their energy-transfer mechanism were discussed. Using these phosphors, the desired CIE values including emissions throughout the green to orange regions of the spectra were achieved. Efficient white-light light-emitting diodes (LEDs) were fabricated using Eu{sup 2+} and Mn{sup 2+} co-doped phosphors based on NUV-excitable LED lights.

  8. Using LEDs | Department of Energy

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

    Using LEDs Using LEDs With their unique design and performance characteristics-such as directional light emission, compact profile, superior optical control, energy efficiency, breakage resistance, reduced maintenance, and long life-LEDs are well suited to a variety of lighting applications. LED products are most competitive in applications where these performance characteristics outweigh their first-cost disadvantages. Although LED products are finding success in a growing number of

  9. 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.

  10. 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.

  11. LED Watch: How Safe Is the Light from LEDs?

    Energy Savers [EERE]

    LED WATCH James Brodrick HOW SAFE IS THE LIGHT FROM LEDs? A new report separates fact from fiction regarding the potential for damage caused by LEDs T he spectral emission of LEDs is a frequent topic of conversation among lighting professionals and others. There's no shortage of published material-some of it based on myth, some of it factual, and some of it a combination of the two-addressing the spectral power distribu- tion (SPD) of LED products used for general illumination. So the question

  12. LED Lighting | Department of Energy

    Office of Environmental Management (EM)

    comparable or better light quality than other types of lighting. Check out the top 8 things you didn't know about LEDs to learn more. Energy Savings LED is a highly energy...

  13. LED Roundtable Reports | Department of Energy

    Energy Savers [EERE]

    LED Roundtable Reports LED Roundtable Reports PDF icon 2015 LED Core Technology Roundtable Report.pdf PDF icon 2015 LED Product Development and Manufacturing Roundtable Report.pdf...

  14. LED Green Power Inc | Open Energy Information

    Open Energy Info (EERE)

    LED Green Power Inc Jump to: navigation, search Name: LED Green Power Inc Place: Santa Cruz, California Zip: 95060 Product: LED fixture and cartridge manufacturer. References: LED...

  15. LED Roundtable Reports | Department of Energy

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

    LED Roundtable Reports LED Roundtable Reports PDF icon 2015 LED Core Technology Roundtable Report.pdf PDF icon 2015 LED Product Development and Manufacturing Roundtable Report.pdf ...

  16. 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.

  17. LED Record Efficacy and Brightness

    Broader source: Energy.gov [DOE]

    Designed for general lighting applications such as street, industrial, and parking garage lighting, the Cree XLamp® power LED sets new records for LED brightness and efficacy, up to 85 lm/W at 350 mA. The XLamp utilizes Cree's performance breakthrough EZBright™ LED chip; both products include technology that was developed in part with R&D funding support from DOE.

  18. Reporting LED Luminaire Product Performance

    SciTech Connect (OSTI)

    2008-12-01

    This brochure on LED product performance is an outcome of a joint DOE-NGLIA effort to assure and improve the quality of SSL products.

  19. Demonstration of LED Street Lighting

    SciTech Connect (OSTI)

    Kinzey, B. R.; Royer, M. P.; Hadjian, M.; Kauffman, R.

    2013-06-01

    GATEWAY program and Municipal Solid-State Street Lighting Consortium report on a demonstration of LED street lighting in Kansas City, MO.

  20. Upgrading Troffer Luminaires to LED

    SciTech Connect (OSTI)

    none,

    2014-01-31

    Solid-state lighting technology fact sheet providing guidance on the various factors to consider when deciding on an LED upgrade for a fluorescent troffer system.

  1. LED

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

    - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs Advanced Nuclear Energy Nuclear

  2. Metacapacitors for LED Lighting: Metacapacitors

    SciTech Connect (OSTI)

    2010-09-02

    ADEPT Project: The CUNY Energy Institute is developing less expensive, more efficient, smaller, and longer-lasting power converters for energy-efficient LED lights. LEDs produce light more efficiently than incandescent lights and last significantly longer than compact fluorescent bulbs, but they require more sophisticated power converter technology, which increases their cost. LEDs need more sophisticated converters because they require a different type of power (low voltage direct current, or DC) than what's generally supplied by power outlets. The CUNY Energy Institute is developing sophisticated power converters for LEDs that contain capacitors made from new, nanoscale materials. Capacitors are electrical components that are used to store energy. CUNY's unique capacitors are configured with advanced power circuits to more efficiently control and convert power to the LED lighting source. They also eliminate the need for large magnetic components, instead relying on networks of capacitors that can be easily printed on plastic substrate. CUNY's prototype LED power converter already meets DOE's 2020 projections for the energy efficiency of LED power converters.

  3. LED Frequently Asked Questions | Department of Energy

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

    Frequently Asked Questions LED Frequently Asked Questions EERE Solid-State Lighting LED Factsheet PDF icon ledbasics.pdf More Documents & Publications LED Frequently Asked ...

  4. Recessed LED Downlights | Department of Energy

    Energy Savers [EERE]

    Recessed LED Downlights Recessed LED Downlights A Dept of Energy Solid-State Lighting Program technology fact sheet on recessed LED downlights. PDF icon recesseddownlight.pdf More ...

  5. LED Frequently Asked Questions | Department of Energy

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

    This document provides answers to LED frequently asked questions for plant-wide improvements, such as "Are LEDs ready for general lighting?" PDF icon LED Frequently Asked Questions ...

  6. Demonstration Assessment of LED Roadway Lighting: Philadelphia...

    Office of Scientific and Technical Information (OSTI)

    LED Roadway Lighting: Philadelphia, PA Royer, Michael P.; Tuenge, Jason R.; Poplawski, Michael E. Roadway Lighting; Solid-state lighting; LED lighting; SSL; LED; GATEWAY Roadway...

  7. LED Performance Under Tough Conditions

    Energy Savers [EERE]

    GATEWAY ROUNDUP www.ies.org December 2015 LD+A 53 Three DOE Gateway applications show how LED luminaires respond to rigorous outdoor environments By JAmes BroDrick A lthough LED lighting has already made impressive inroads in outdoor applica- tions, there's still a lot we don't know about how the technology will fare when faced with especially challenging conditions. Three recent U.S. Department of Energy Gateway stud- ies (http://energy.gov/eere/ssl/gateway-demon- strations) add to our

  8. LED lamp power management system and method

    DOE Patents [OSTI]

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A. M.

    2013-03-19

    An LED lamp power management system and method including an LED lamp having an LED controller 58; a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 reduces power loss in one of the channel switch 62 and the shunt switch 68 when LED lamp electronics power loss (P.sub.loss) exceeds an LED lamp electronics power loss limit (P.sub.lim); and each of the channel switches 62 receives a channel switch control signal 63 from the LED controller 58 and each of the shunt switches 68 receives a shunt switch control signal 69 from the LED controller 58.

  9. LED lamp color control system and method

    DOE Patents [OSTI]

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A.M.

    2013-02-05

    An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

  10. Small Area Array-Based LED Luminaire Design

    SciTech Connect (OSTI)

    Thomas Yuan

    2008-01-09

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency LED luminaire designs based on small area array-based gallium nitride diodes. Novel GaN-based LED array designs are described, specifically addressing the thermal, optical, electrical and mechanical requirements for the incorporation of such arrays into viable solid-state LED luminaires. This work resulted in the demonstration of an integrated luminaire prototype of 1000 lumens cool white light output with reflector shaped beams and efficacy of 89.4 lm/W at CCT of 6000oK and CRI of 73; and performance of 903 lumens warm white light output with reflector shaped beams and efficacy of 63.0 lm/W at CCT of 2800oK and CRI of 82. In addition, up to 1275 lumens cool white light output at 114.2 lm/W and 1156 lumens warm white light output at 76.5 lm/W were achieved if the reflector was not used. The success to integrate small area array-based LED designs and address thermal, optical, electrical and mechanical requirements was clearly achieved in these luminaire prototypes with outstanding performance and high efficiency.

  11. Use of double-layer ITO films in reflective contacts for blue and near-UV LEDs

    SciTech Connect (OSTI)

    Markov, L. K., E-mail: l.markov@mail.ioffe.ru; Smirnova, I. P.; Pavluchenko, A. S. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kukushkin, M. V. [ZAO Innovation Company TETIS (Russian Federation); Zakheim, D. A.; Pavlov, S. I. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2014-12-15

    The structural and optical properties of multilayer ITO/SiO{sub 2}/Ag composites are studied. In these composites, the ITO (indium-tin oxide) layer is produced by two different methods: electron-beam evaporation and a combined method including electron-beam evaporation and subsequent magnetron sputtering. It is shown that the reflectance of the composite based on the ITO film produced by electron-beam evaporation is substantially lower. This can be attributed to the strong absorption of light at both boundaries of the SiO{sub 2} layer, which results from the complex surface profile of ITO films deposited by electron-beam evaporation. Samples with a film deposited by the combined method have a reflectance of about 90% at normal light incidence, which, combined with their higher electrical conductivity, makes these samples advantageous for use as reflective contacts to the p-type region of AlInGaN light-emitting diodes of the flip-chip design.

  12. LED MR16 Lamps | Department of Energy

    Energy Savers [EERE]

    LED MR16 Lamps LED MR16 Lamps A U.S. DOE Solid-State Lighting Program technology fact sheet on LED MR16 lamps. PDF icon ledmr16-lamps.pdf More Documents & Publications Report ...

  13. LED North America - Energy Innovation Portal

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

    Image icon LED lightbulbs

    File LED lightbulbs - EPS file.

    LED North America Oak Ridge National Laboratory Success Story Details Partner Location Agreement Type Publication Date LED North America Oak Ridge, TN License July 2, 2013 Summary LED North America (LEDNA), founded in 2008, is a company located in Oak Ridge, Tennessee that produces LED alternatives for commercial lighting for applications such as roadways, parking lots, parking garages, and indoor high bay applications. The

  14. Philadelphia International Airport Apron Lighting: LED System...

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

    Philadelphia International Airport Apron Lighting: LED System Performance in a Trial Installation Philadelphia International Airport Apron Lighting: LED System Performance in a ...

  15. Federally Led Accident Investigation Reports | Department of...

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

    Federally Led Accident Investigation Reports Federally Led Accident Investigation Reports Includes Pre-March 2011 Type A Reports June 1, 1999 Type A Accident Investigation Board...

  16. Demonstration Assessment of LED Roadway Lighting: Philadelphia...

    Office of Scientific and Technical Information (OSTI)

    of LED Roadway Lighting: Philadelphia, PA Citation Details In-Document Search Title: Demonstration Assessment of LED Roadway Lighting: Philadelphia, PA For this demonstration ...

  17. LED Lighting Facts | Department of Energy

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

    Research & Development » Technology Application R&D » LED Lighting Facts LED Lighting Facts LED lighting facts - A Program of the U.S. DOE DOE's LED Lighting Facts® program showcases LED products for general illumination from manufacturers who commit to testing products and reporting performance results according to industry standards. For lighting buyers, designers, and energy efficiency programs, the program provides information essential to evaluating SSL products. Central to the

  18. 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.

  19. 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

  20. Enhanced vbasis laser diode package

    SciTech Connect (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.

  1. Updating the LED Life Cycle Assessment

    Energy Savers [EERE]

    Part 2: LED Manufacturing and Performance 7 Goal of the New Study Review new literature on the life- cycle assessment of LED products. Determine if newer A-19 products...

  2. LEDs for Street Lighting—Here Today

    SciTech Connect (OSTI)

    2013-11-29

    Fact sheet that provides a brief overview of the viability of LED street lighting in municipalities and highlights case studies of two cities—Los Angeles and Seattle—that have invested in LED street lighting.

  3. LED Solutions for the Dark Hours

    Energy Savers [EERE]

    technologies 5 LEDs for Street and Roadway Lighting Portland, OR Philadelphia, PA New York, NY Kansas City, MO 6 Boston Las Vegas Seattle Number of LED Replacements to Date (4...

  4. UNDERSTANDING LED COLOR-TUNABLE PRODUCTS

    Broader source: Energy.gov [DOE]

    LED luminaires with the ability to deliver varying light color have been on the architectural lighting market since the early days of LED lighting, but improved efficacy, colors, controls, and...

  5. SemiLEDs | Open Energy Information

    Open Energy Info (EERE)

    SemiLEDs Place: Boise, Idaho Zip: 83702 Product: US-based LED chip maker with Asia manufacturing operations. Coordinates: 43.60698, -116.193409 Show Map Loading map......

  6. Decisions that led to Y-12

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

    Decisions that led to Y-12 Last week we saw the political and organizational changes that led up to the Manhattan Project being created on August 13, 1942. The S-1 Executive ...

  7. Final decisions that led to Y-12

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

    decisions that led to Y-12 As we have seen earlier in this series, Ernest O. Lawrence and ... By late 1942, progress on the reactor technology being led by Enrico Fermi at the ...

  8. Have You Used LED Light Strings?

    Broader source: Energy.gov [DOE]

    This week, you read about LED holiday light strings, which can use 90% less energy than regular incandescent light strings.

  9. LED Lighting in a Performing Arts Center

    SciTech Connect (OSTI)

    Wilkerson, A. M.; Abell, T. C.; T., E. Perrin

    2015-07-31

    GATEWAY demonstration report of LED wall washer retrofit lighting at the University of Maryland Clarice Smith Performing Arts Center.

  10. LED Lighting: Just the Facts, Please!

    Broader source: Energy.gov [DOE]

    Now there's another arsenal in the toolbox to help consumers find LED lights they can trust: the Lighting Facts™ label.

  11. LED Essentials - Technology, Applications, Advantages, Disadvantages |

    Energy Savers [EERE]

    Department of Energy Essentials - Technology, Applications, Advantages, Disadvantages LED Essentials - Technology, Applications, Advantages, Disadvantages On October 11, 2007, Kevin Dowling, VP of Innovation for Philips Solid-State Lighting Solutions, presented a broad introduction to LED technology, and discussed the technology status, advantages and disadvantages, current applications, future potential, and evolving path of LED technology from indicator lights to general illumination. View

  12. LED Market Adoption: Status and Trends

    Energy Savers [EERE]

    (lmW) 67 60 CCT (K) 3000 3500 L 70 (hours) 28,000 36,000 Price (unit) 23 30 18 LED Linear Fixtures 19 T12 26% T8 67% T5 7% LED Lamp <1% LED Luminaire <1% 2012 T12 17% T8 72%...

  13. CX-001270: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    Conduct Greenhouse Emissions Inventory, Energy Audits, Energy Efficiency Grants, Energy Efficiency Upgrades, Light-Emitting Diode (LED) Lighting, and DehumidificationCX(s) Applied: A1, A9, A11, B2.5, B5.1Date: 01/05/2010Location(s): Burnsville, MinnesotaOffice(s): Energy Efficiency and Renewable Energy

  14. CX-000777: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Low-Cost, Highly Lambertian Reflector Composite for Improved LED (Light-Emitting Diode) Efficiency and LifetimeCX(s) Applied: B3.6Date: 02/10/2010Location(s): Newark, DelawareOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  15. CX-010895: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Development and Industrialization of Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) Light Emitting Diodes LEDs on Patterned Sapphire Substrate (PSS) for Low Cost Emitter Architecture CX(s) Applied: B3.6 Date: 06/27/2013 Location(s): California Offices(s): National Energy Technology Laboratory

  16. CX-001143: Categorical Exclusion Determination

    Office of Energy Efficiency and Renewable Energy (EERE)

    Development of Advanced Manufacturing Methods for Warm-White LEDs (Light-Emitting Diodes) for General LightingCX(s) Applied: B3.6, B5.1Date: 03/09/2010Location(s): Valley View, OhioOffice(s): Energy Efficiency and Renewable Energy, National Energy Technology Laboratory

  17. CX-003524: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Energy Efficient Street Lighting Changeover - Light-Emitting Diode (LED)/High Intensity Discharge (HID)CX(s) Applied: A1, A9, B1.3, B5.1Date: 08/26/2010Location(s): Oak Harbor, OhioOffice(s): Electricity Delivery and Energy Reliability, National Energy Technology Laboratory

  18. CX-003526: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    LED (Light-Emitting Diode) Street Light RetrofitCX(s) Applied: A1, A9, B1.3, B3.6, B5.1Date: 08/26/2010Location(s): Lorain County, OhioOffice(s): Electricity Delivery and Energy Reliability, National Energy Technology Laboratory

  19. Solid-State Lighting Consortia

    Broader source: Energy.gov [DOE]

    Most potential users of light-emitting diode (LED) lighting do not have large training budgets to independently educate themselves; participation in the Solid-State Lighting (SSL) Consortia is a low-cost–low-risk way to benefit from the knowledge and experience of others.

  20. CX-000089: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Milford's Replacement of?Existing Street Lighting with LED (Light-Emitting Diode) LightsCX(s) Applied: B5.1, B1.3Date: 11/19/2009Location(s): Milford, DelawareOffice(s): Energy Efficiency and Renewable Energy