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Revealing the Nature of Singlet Fission under the Veil of Internal Conversion
Author(s) -
Wang Long,
Bai Shuming,
Wu Yishi,
Liu Yanping,
Yao Jiannian,
Fu Hongbing
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201912202
Subject(s) - singlet fission , internal conversion , intramolecular force , intermolecular force , energy conversion efficiency , chemistry , photochemistry , excited state , yield (engineering) , chemical physics , singlet state , spectroscopy , excitation , materials science , optoelectronics , atomic physics , molecule , organic chemistry , physics , quantum mechanics , astronomy , metallurgy , spectral line , electrical engineering , engineering
Abstract Singlet fission (SF) holds the potential to boost the maximum power conversion efficiency of photovoltaic devices. Internal conversion (IC) has been considered as one of the major competitive deactivation pathways to transform excitation energy into heat. Now, using time‐resolved spectroscopy and theoretical calculation, it is demonstrated that, instead of a conventional IC pathway, an unexpected intramolecular singlet fission (iSF) process is responsible for excited state deactivation in isoindigo derivatives. The 1 TT state could form at ultrafast rate and nearly quantitatively in solution. In solid films, the slipped stacked intermolecular packing of a thiophene‐functionalized derivative leads to efficient triplet pair separation, giving rise to an overall triplet yield of 181 %. This work not only enriches the pool of iSF‐capable materials, but also contributes to a better understanding of the iSF mechanism, which could be relevant for designing new SF sensitizers.