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Designing Efficient and Ultralong Pure Organic Room‐Temperature Phosphorescent Materials by Structural Isomerism
Author(s) -
Xiong Yu,
Zhao Zheng,
Zhao Weijun,
Ma Huili,
Peng Qian,
He Zikai,
Zhang Xuepeng,
Chen Yuncong,
He Xuewen,
Lam Jacky W. Y.,
Tang Ben Zhong
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201800834
Subject(s) - phosphorescence , intersystem crossing , carbazole , substituent , singlet state , quantum yield , phosphor , materials science , steric effects , photochemistry , triplet state , chemistry , organic chemistry , optoelectronics , molecule , atomic physics , excited state , fluorescence , physics , quantum mechanics
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 (ΔE ST ) and pure ππ* configuration of the lowest triplet state (T 1 ) 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 ΔE ST and pure ππ* configuration of T 1 .