Designing Efficient and Ultralong Pure Organic Room-Temperature Phosphorescent Materials by Structural Isomerism

Yu Xiong; Zheng Zhao; Weijun Zhao; Huili Ma; Qian Peng; Zikai He; Xuepeng Zhang; Yuncong Chen; Xuewen He; Jacky W Y Lam; Ben Zhong Tang

doi:10.1002/anie.201800834

Designing Efficient and Ultralong Pure Organic Room-Temperature Phosphorescent Materials by Structural Isomerism

Angew Chem Int Ed Engl. 2018 Jul 2;57(27):7997-8001. doi: 10.1002/anie.201800834. Epub 2018 Jun 4.

Authors

Yu Xiong¹, Zheng Zhao¹, Weijun Zhao¹, Huili Ma², Qian Peng², Zikai He³, Xuepeng Zhang¹, Yuncong Chen¹, Xuewen He¹, Jacky W Y Lam¹, Ben Zhong Tang^{1

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Affiliations

¹ HKUST Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park Nanshan, Shenzhen, 518057, China.
² Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
³ School of Science, Harbin Institute of Technology Shenzhen, HIT Campus of University Town of Shenzhen, Shenzhen, 518055, 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, Clear Water Bay, 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, 510640, China.

PMID: 29736955
DOI: 10.1002/anie.201800834

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 (ΔE_ST ) 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 ΔE_ST and pure ππ* configuration of T₁ .

Keywords: carbazoles; charge transfer; fluorescence; phosphorescence; small energy gap.

Publication types

Research Support, Non-U.S. Gov't