Xiang Yepeng, Li Pan, Gong Shaolong, Huang Yu-Hsin, Wang Chun-Yu, Zhong Cheng, Zeng Weixuan, Chen Zhanxiang, Lee Wei-Kai, Yin Xiaojun, Wu Chung-Chih, Yang Chuluo
Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China.
Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China.
Sci Adv. 2020 Oct 9;6(41). doi: 10.1126/sciadv.aba7855. Print 2020 Oct.
Manipulating orientation of organic emitters remains a formidable challenge in organic light-emitting diodes (OLEDs). Here, expansion of the acceptor plane of thermally activated delayed fluorescence (TADF) emitters was demonstrated to selectively modulate emitting dipole orientation. Two proof-of-the-concept molecules, PXZPyPM and PXZTAZPM, were prepared by introducing a planar 2-phenylpyridine or 2,4,6-triphenyl-1,3,5-triazine substituent into a prototypical molecule (PXZPM) bearing a pyrimidine core and two phenoxazine donors. This design approach suppressed the influence of substituents on electronic structures and associated optoelectronic properties. Accordingly, PXZPyPM and PXZTAZPM preserved almost the same excited states and similar emission characteristics as PXZPM. The expanded acceptor plane of PXZPyPM and PXZTAZPM resulted in a 15 to 18% increase in horizontal ratios of emitting dipole orientation. PXZPyPM supported its green device exhibiting an external quantum efficiency of 33.9% and a power efficiency of 118.9 lumen per watt, competitive with the most efficient green TADF OLEDs reported so far.
在有机发光二极管（OLED）中，控制有机发光体的取向仍然是一项艰巨的挑战。在此，热激活延迟荧光（TADF）发光体的受体平面扩展被证明可选择性地调节发射偶极子取向。通过将平面的2-苯基吡啶或2,4,6-三苯基-1,3,5-三嗪取代基引入具有嘧啶核心和两个吩恶嗪供体的原型分子（PXZPM）中，制备了两个概念验证分子PXZPyPM和PXZTAZPM。这种设计方法抑制了取代基对电子结构和相关光电性质的影响。因此，PXZPyPM和PXZTAZPM与PXZPM保持几乎相同的激发态和相似的发射特性。PXZPyPM和PXZTAZPM扩展的受体平面导致发射偶极子取向的水平比率增加了15%至18%。PXZPyPM的绿色器件表现出33.9%的外量子效率和118.9流明每瓦的功率效率，与迄今为止报道的最高效绿色TADF OLED具有竞争力。
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