A Bipolar Transporter as an Efficient Green Fluorescent Emitter and Host for Red Phosphors in Multi‐ and Single‐Layer Organic Light‐Emitting Diodes |
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| Authors: | Dr. Jun Ye Zhan Chen Kai Wang Dr. Feifei An Yi Yuan Wencheng Chen Qingdan Yang Prof. Xiaohong Zhang Prof. Chun‐Sing Lee |
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| Affiliation: | 1. Center of Super‐Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR (P. R. China);2. Nano‐organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 29 Zhongguancun East Road, Haidian District, Beijing, 100190 (P. R. China), Fax: (+86)?10‐64879375 |
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| Abstract: | Multifunctional donor–acceptor compound 4,4′‐bis(dibenzothiophene‐S,S‐dioxide‐2‐yl)triphenylamine ( DSTPA ) was obtained by linking a strongly electron‐withdrawing core and a strongly electron‐donating core with a biphenyl bridge in linear spatial alignment. DSTPA not only has suitable HOMO and LUMO levels for easily accepting both holes and electrons, it was also demonstrated to have a high fluorescence quantum yield of 0.98 and a high triplet energy level of 2.39 eV. Versatile applications of DSTPA for bipolar transport, green fluorescent emission, and sensitizing a red phosphor were systematically investigated in a series of multi‐ and single‐layer organic light‐emitting devices. In traditional multilayer devices, it shows excellent performance both in an undoped fluorescent device (used as a green emitter and achieving maximum current and power efficiencies (CE and PE) of 12.6 cd A?1 and 9.4 Lm W?1, respectively) and in a red phosphorescent device (used as a host and achieving maximum CE and PE of 26.4 cd A?1 and 26.3 Lm W?1, respectively). Furthermore, DSTPA was also simultaneously used as an emitter, a hole transporter, and an electron transporter in a single‐layer device showing CE and PE of 5.1 cd A?1 and 4.7 Lm W?1, respectively. A single‐layer red phosphorescent device with efficiencies of 11.7 cd A?1 and 12.6 Lm W?1 was obtained by doping DSTPA with a red phosphor. The performances of all of the devices in this work are comparable to the best of their corresponding classes in the literature. |
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| Keywords: | bipolar charge transport charge carrier injection donor– acceptor systems fluorescence semiconductors |
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