Thermally activated and aggregation-regulated excitonic coupling enable emissive high-lying triplet excitons
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Room-temperature phosphorescence (RTP) originating from higher-lying triplet excitons remains a rather rarely documented occurrence for purely organic molecular systems. Here, we report two naphthalene-based RTP luminophores whose phosphorescence emission is enabled by radiative decay of high-lying triplet excitons. In contrast, upon cooling the dominant phosphorescence originates from the lowest-lying triplet excited state, which is manifested by a red-shifted emission. Photophysical and theoretical studies reveal that the unusual RTP results from thermally activated excitonic coupling between different conformations of the compounds. Aggregation-regulated excitonic coupling is observed when increasing the doping concentration of the emitters in poly(methylmethacrylate) (PMMA). Further, the RTP quantum efficiency improves more than 80-fold in 1,3-bis(N-carbazolyl)benzene (mCP) compared to that in PMMA. This design principle offers important insight into triplet excited state dynamics and has been exploited in afterglow-indicating temperature sensing.
Wang , T , De , J , Wu , S , Gupta , A K & Zysman-Colman , E 2022 , ' Thermally activated and aggregation-regulated excitonic coupling enable emissive high-lying triplet excitons ' , Angewandte Chemie International Edition , vol. 61 , no. 33 , e202206681 . https://doi.org/10.1002/anie.202206681
Angewandte Chemie International Edition
Copyright © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
DescriptionFunding: Horizon 2020 Framework Programme (Grant Number(s): 897098; Grant recipient(s): Tao Wang, Eli Zysman-Colman); Horizon 2020 Framework Programme (Grant Number(s): 101025143; Grant recipient(s): Eli Zysman-Colman, Joydip De); Engineering and Physical Sciences Research Council (Grant Number(s): EP/P010482/1; Grant recipient(s): Eli Zysman-Colman); Royal Society (Grant Number(s): SRF\R1\201089; Grant recipient(s): Abhishek Kumar Gupta, Eli Zysman-Colman); China Scholarship Council (GrantNumber(s): 201906250199; Grant recipient(s): Sen Wu)
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