Cao Hong-Tao, Hou Peng-Fei, Yu Wen-Jing, Gao Ying, Li Bo, Feng Quan-You, Zhang He, Wang Sha-Sha, Su Zhong-Min, Xie Ling-Hai
Center for Molecular Systems and Organic Devices (CMSOD), State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, P.R. China.
Institute of Biomass Functional Materials Interdisciplinary Studies, Jilin Engineering Normal University, 3050 Kaixuan Road, Changchun 130052, P.R. China.
ACS Appl Mater Interfaces. 2023 Feb 8;15(5):7236-7246. doi: 10.1021/acsami.2c22266. Epub 2023 Jan 26.
The exciplex-thermally activated delayed fluorescence (exciplex-TADF) system is an excellent candidate for the fabrication of high-efficiency organic light-emitting diodes (OLEDs) because of its more easily achieved small singlet-triplet energy splitting (Δ) and doping control. However, exciplex-TADF is still faced with the problems of low external quantum efficiency (η) and unclear effect of structure modification in electron acceptors. Herein, we provide a steric hindrance increase strategy to obtain high-efficiency exciplex emissions. Through introducing a 9-phenylfluorene group into -ethylcarbazole of the dicyano-substituted 9-phenylfluorene, an electron acceptor material with increased steric hindrance is obtained, which helps the exciplex harvest a larger driving force and higher emission efficiencies. Encouragingly, the obtained OLED displays a maximum η of 25.8%, which is one of the best efficiency values among reported exciplex-OLEDs, simultaneously possessing excellent current efficiency of 83.6 cd A and power efficiency of 93.7 lm W. It is expected that this work will offer a new avenue for designing electron acceptors for highly efficient exciplex emissions.
激基复合物热激活延迟荧光（exciplex-TADF）体系因其更易于实现较小的单重态-三重态能量分裂（Δ）和掺杂控制，是制造高效有机发光二极管（OLED）的极佳候选材料。然而，exciplex-TADF仍面临外部量子效率（η）低以及电子受体结构修饰效果不明确的问题。在此，我们提供一种增加空间位阻的策略来获得高效的激基复合物发射。通过将9-苯基芴基引入二氰基取代的9-苯基芴的-乙基咔唑中，得到一种空间位阻增加的电子受体材料，这有助于激基复合物获得更大的驱动力和更高的发射效率。令人鼓舞的是，所制备的OLED的最大η为25.8%，这是已报道的激基复合物OLED中最佳效率值之一，同时具有83.6 cd/A的优异电流效率和93.7 lm/W的功率效率。预计这项工作将为设计用于高效激基复合物发射的电子受体提供一条新途径。
