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Designing Efficient and Ultralong Pure Organic Room‐Temperature Phosphorescent Materials by Structural Isomerism |
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| Authors: | Dr Yu Xiong Dr Zheng Zhao Dr Weijun Zhao Dr Huili Ma Prof Qian Peng Prof Zikai He Dr Xuepeng Zhang Dr Yuncong Chen Xuewen He Prof Jacky W Y Lam Prof Ben Zhong Tang |
| Institution: | 1. HKUST Shenzhen Research Institute, Shenzhen, China;2. Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;3. School of Science, Harbin Institute of Technology Shenzhen, HIT Campus of University Town of Shenzhen, Shenzhen, China;4. Department of Chemistry, Division of Life Science, Division of Biomedical Engineering, Institute for Advanced Study and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China;5. NSFC Center for Luminescence from Molecular Aggregates, SCUT-HKUST, Joint Research Institute, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, China |
| Abstract: | Pure organic materials with ultralong room‐temperature phosphorescence (RTP) are attractive alternatives to inorganic phosphors. However, they generally show inefficient intersystem crossing (ISC) owing to weak spin–orbit coupling (SOC). A design principle based on the realization of small energy gap between the lowest singlet and triplet states (ΔEST) and pure ππ* configuration of the lowest triplet state (T1) via structural isomerism was used to obtain efficient and ultralong RTP materials. The meta isomer of carbazole‐substituted methyl benzoate exhibits an ultralong lifetime of 795.0 ms with a quantum yield of 2.1 %. Study of the structure–property relationship shows that the varied steric and conjugation effects imposed by ester substituent at different positions are responsible for the small ΔEST and pure ππ* configuration of T1. |
| Keywords: | carbazoles charge transfer fluorescence phosphorescence small energy gap |