Design Strategy of Blue and Yellow Thermally Activated Delayed Fluorescence Emitters and Their All-Fluorescence White OLEDs with External Quantum Efficiency beyond 20%
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- 作者：Yunchuan Li ; Xiang-Long Li ; Dongjun Chen ; Xinyi Cai ; Gaozhan Xie ; Zuozheng He ; Yuan-Chun Wu ; Alan Lien ; Yong Cao and Shi-Jian Su
- 刊名：Advanced Functional Materials
- 出版年：2016
- 出版时间：October 11, 2016
- 年：2016
- 卷：26
- 期：38
- 页码：6904-6912
- 全文大小：1363K
- ISSN：1616-3028
文摘
Two thioxanthone-derived isomeric series of thermally activated delayed fluorescence (TADF) emitters 1,6-2TPA-TX/3,6-2TPA-TX and 1,6-2TPA-TXO/3,6-2TPA-TXO are developed for organic light-emitting diodes (OLEDs). Blue emission devices based on symmetrical 3,6-2TPA-TX with common vertical transition route realize an extremely high external quantum efficiency (EQE) of 23.7%, and an ever highest EQE of 24.3% is achieved for yellow emission devices based on 3,6-2TPA-TXO by solely changing the sulfur atom valence state of the thioxanthone core. In contrast, their corresponding asymmetric isomers are affected by intramolecular energy transfer and more severely by a nonradiative deactivation pathway, to give much low EQE values (<5%). By utilizing 3,6-2TPA-TX as a blue emitter and 3,6-2TPA-TXO as a yellow emitter, an ever highest EQE of 20.4% is achieved for all-fluorescence white OLEDs.