skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1351661
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Organic Electronics
Additional Journal Information:
Journal Volume: 36; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 16:35:15; Journal ID: ISSN 1566-1199
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Ren, Bao-Yi, Zhong, Dao-Kun, Sun, Ya-Guang, Zhao, Xiang-Hua, Zhang, Qi-Jian, Liu, Yi, Jurow, Matthew, Sun, Ming-Li, Zhang, Zhen-Song, and Zhao, Yi. Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes. Netherlands: N. p., 2016. Web. doi:10.1016/j.orgel.2016.06.006.
Ren, Bao-Yi, Zhong, Dao-Kun, Sun, Ya-Guang, Zhao, Xiang-Hua, Zhang, Qi-Jian, Liu, Yi, Jurow, Matthew, Sun, Ming-Li, Zhang, Zhen-Song, & Zhao, Yi. Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes. Netherlands. doi:10.1016/j.orgel.2016.06.006.
Ren, Bao-Yi, Zhong, Dao-Kun, Sun, Ya-Guang, Zhao, Xiang-Hua, Zhang, Qi-Jian, Liu, Yi, Jurow, Matthew, Sun, Ming-Li, Zhang, Zhen-Song, and Zhao, Yi. 2016. "Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes". Netherlands. doi:10.1016/j.orgel.2016.06.006.
@article{osti_1351661,
title = {Quinolyl functionalized spiro[fluorene-9,9′-xanthene] host materials with bipolar characteristics for green and red phosphorescent organic light-emitting diodes},
author = {Ren, Bao-Yi and Zhong, Dao-Kun and Sun, Ya-Guang and Zhao, Xiang-Hua and Zhang, Qi-Jian and Liu, Yi and Jurow, Matthew and Sun, Ming-Li and Zhang, Zhen-Song and Zhao, Yi},
abstractNote = {},
doi = {10.1016/j.orgel.2016.06.006},
journal = {Organic Electronics},
number = C,
volume = 36,
place = {Netherlands},
year = 2016,
month = 9
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.orgel.2016.06.006

Save / Share:
  • Comprising hole- and electron-transporting moieties with flexible linkages, representative non-conjugated bipolar hybrids have been synthesized and characterized for a demonstration of their potential use as host materials for the fabrication of phosphorescent organic light-emitting diodes. The advantages of this material class include solution processing into amorphous films with elevated glass transition temperatures, stability against phase separation and crystallization, and provision of LUMO/HOMO levels and triplet energies contributed by the two independent moieties without constraint by the electrochemical energy gap. While exciplex formation between the hole- and electron-transporting moieties is inevitable, its adverse effects on spectral purity and device efficiency canmore » be avoided by trapping charges on triplet emitters, as demonstrated for Ir(mppy)3 in TRZ-3Cz(MP)2, and TRZ-1Cz(MP)2. With these two bipolar hybrids and hole-transporting Cz(MP)2 as the host, the maximum current efficiency of the bilayer PhOLED is achieved with TRZ-3Cz(MP)2, but the driving voltage decreases monotonically with an increasing TRZ content.« less
  • Data from a series of phosphorescent blue organic light emitting devices OLEDs with emissive layers consisting of either CBP:6% Firpic or mCP:6% FIrpic show that the triplet energy of the hole and electron transport layers can have a larger influence on the external quantum efficiency of an operating OLED than the triplet energy of the host material. These results are important and insightful given the commonly held view that host materials for phosphorescent OLEDs must have a triplet energy higher than that of the emitter in order to obtain high external quantum efficiency (EQE). A new host material, 4-(di-ptolylaminophenyl)diphenylphosphine oxidemore » (DHM-A2), which has a triplet energy less than that of FIrpic is also reported. OLEDs fabricated using DHM-A2 show improved performance (lower drive voltage and higher external quantum efficiency) over OLEDs using 4- (diphenylphosphoryl)-N,N-diphenylaniline (HMA1), a high performance ambipolar DHM-A2 analogue with a triplet energy greater than FIrpic. Our results suggest modified design rules for the development of new, high performance host materials., ames, more focus can be placed on molecular structures that provide good charge transport (i.e., ambipolarity for charge balance) and good molecular stability (for long lifetimes). This improved understanding provides additional flexibility in order to generate OLEDs with lower operating voltage and longer lifetime, while still providing high EQE.« less
  • This paper demonstrates extremely efficient (ηP,max = 118 lm W−1) ITO-free green phosphorescent OLEDs (PHOLEDs) with multilayered, highly conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films as the anode. The efficiency is obtained without any outcoupling-enhancing structures and is 44% higher than the 82 lm W−1 of similar optimized ITO-anode PHOLEDs. Detailed simulations show that this improvement is due largely to the intrinsically enhanced outcoupling that results from a weak microcavity effect.
  • Our project was primarily focused on the MYPP 2015 goal for white phosphorescent organic devices (PhOLEDs or phosphorescent organic light-emitting diodes) for solid-state lighting with long lifetimes and high efficiencies. Our central activity was to synthesize and evaluate a new class of host materials for blue phosphors in the PhOLEDs, known to be a weak link in the device operating lifetime. The work was a collaborative effort between three groups, one primarily responsible for chemical design and characterization (Chen), one primarily responsible for device development (Tang) and one primarily responsible for mechanistic studies and degradation analysis (Rothberg). The host materialsmore » were designed with a novel architecture that chemically links groups with good ability to move electrons with those having good ability to move “holes” (positive charges), the main premise being that we could suppress the instability associated with physical separation and crystallization of the electron conducting and hole conducting materials that might cause the devices to fail. We found that these materials do prevent crystallization and that this will increase device lifetimes but that efficiencies were reduced substantially due to interactions between the materials creating new low energy “charge transfer” states that are non-luminescent. Therefore, while our proposed strategy could in principle improve device lifetimes, we were unable to find a materials combination where the efficiency was not substantially compromised. In the course of our project, we made several important contributions that are peripherally related to the main project goal. First, we were able to prepare the proposed new family of materials and develop synthetic routes to make them efficiently. These types of materials that can transport both electrons and holes may yet have important roles to play in organic device technology. Second we developed an important new method for controlling the deposition profile of material so that arbitrary concentration gradients can be implemented in layers with mixed composition. These concentration profiles are known to increase device efficiency and longevity and we confirmed that experimentally. Third, we investigated a new method for analyzing degradation in devices using mass spectrometry to look for degradation products. We showed that these methods are not simple to interpret unambiguously and need to be used with caution.« less
  • 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)more » 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.« less