题目： | Avoiding Energy Loss on TADF Emitters: Controlling the Dual Conformations of D–A Structure Molecules Based on the Pseudoplanar Segments |
作者： | Kai Wang,1,2,3 Cai-Jun Zheng,2,3* Wei Liu,1,3 Ke Liang,1 Yi-Zhong Shi,1 Si-Lu Tao,2 Chun-Sing Lee,4* Xue-Mei Ou,1 and Xiao-Hong Zhang1,3* |
单位： | 1Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu, Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China 2School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, P. R. China 3Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China 4Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China |
摘要： | The recent introduction of thermally activated delayed fluorescence (TADF) emitters is regarded as an important breakthrough for the development of high efficiency organic light-emitting devices (OLEDs). The planar D and A groups are generally used to construct TADF emitters for their rigid structure and large steric hindrance. In this work, it is shown that many frequently used nonaromatic (noncontinuous conjugation or without satisfying Hückel’s rule) planar segments, such as 9,9-dimethyl-9,10-dihydroacridine, are actually pseudoplanar segments and have two possible conformations–a planar form and a crooked form. Molecules constructed from pseudoplanar segments can thus have two corresponding conformations. Their existence can have significant impact on the performance of many TADF emitters. Two design strategies are presented for addressing the problem by either (1) increasing the rigidity of these groups to suppress its crooked form or (2) increasing the steric hindrance of the linked group to minimize energy of the emitters with the highly twisted form. Following these strategies, two new emitters are synthesized accordingly and successfully applied in OLEDs demonstrating high external quantum efficiencies (20.2% and 18.3%). |
影响因子： | 19.791 |
分区情况： | 一区 |
链接： | http://onlinelibrary.wiley.com/doi/10.1002/adma.201701476/epdf |
责任编辑： 向丹婷