Wu Kailong, Wang Zian, Zhan Lisi, Zhong Cheng, Gong Shaolong, Xie Guohua, Yang Chuluo
Department of Chemistry and Hubei Key Lab on Organic and Polymeric Optoelectronic Materials , Wuhan University , Wuhan 430072 , People's Republic of China.
J Phys Chem Lett. 2018 Apr 5;9(7):1547-1553. doi: 10.1021/acs.jpclett.8b00344. Epub 2018 Mar 13.
Two new blue emitters, i.e., bis-[2-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( o-ACSO2) and bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( m-ACSO2), with reserved fine thermally activated delayed fluorescent (TADF) nature and simply tuned thermal and optoelectronic properties, were synthesized by isomer engineering. The meta-linking compound, i.e., m-ACSO2, obtains the highest photoluminescence quantum yield with a small singlet-triplet energy gap, a moderate delayed fluorescent lifetime, excellent solubility, and neat film homogeneity. Due to its unique aggregation-induced emission (AIE) character, neat film-based heterojunction-like organic light-emitting diodes (OLEDs) are achievable. By inserting an excitonic inert exciton-blocking layer, the PN heterojunction-like emission accompanied by intefacial exciplex was shifted to a homojunction-like channel mainly from the AIE emitter itself, providing a new tactic to generate efficient blue color from neat films. The solution-processed nondoped sky-blue OLED employing m-ACSO2 as emitter with homojunction-like emission achieved a maximum external quantum efficiency of 17.2%. The design strategies presented herein provide practical methods to construct efficient blue TADF dyes and realize high-performance blue TADF devices.
通过异构体工程合成了两种新型蓝色发光体，即双-[2-(9,9-二甲基-9,10-二氢吖啶)-苯基]-砜（邻-ACSO2）和双-[3-(9,9-二甲基-9,10-二氢吖啶)-苯基]-砜（间-ACSO2），它们保留了良好的热激活延迟荧光（TADF）特性，并且热学和光电性能易于调节。间位连接的化合物，即间-ACSO2，具有最高的光致发光量子产率，其单重态-三重态能隙小，延迟荧光寿命适中，溶解性优异，且薄膜均匀性良好。由于其独特的聚集诱导发光（AIE）特性，可以制备基于纯薄膜的类异质结有机发光二极管（OLED）。通过插入激子惰性的激子阻挡层，伴随界面激基复合物的PN类异质结发射主要转变为源自AIE发光体本身的类同质结通道，这为从纯薄膜产生高效蓝光提供了一种新策略。采用间-ACSO2作为发光体且具有类同质结发射的溶液法加工非掺杂天蓝色OLED实现了17.2%的最大外量子效率。本文提出的设计策略为构建高效蓝色TADF染料和实现高性能蓝色TADF器件提供了实用方法。
