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Aggregation-Induced Radical of Donor-Acceptor Organic Semiconductors

preprint
submitted on 03.05.2021, 16:08 and posted on 05.05.2021, 11:09 by Zhongxin Chen, Yuan Li, Weiya Zhu, zejun wang, Wenqiang Li, Miao Zeng, fei huang

Narrow bandgap donor-acceptor organic semiconductors are generally considered to show closed-shell singlet ground state and their radicals are reported as impurities, polarons, charge transfer state monoradical or defects. Herein, we reported the open-shell singlet diradical electronic ground state of two diketopyrrolopyrrole-based compounds Flu-TDPP and DTP-TDPP via the combination of variable temperature NMR, variable temperature electron spin spectroscopy (ESR), superconducting quantum interference device magnetometry, and theoretical calculations. It is observed that the quinoid-diradical character is significantly enhanced in aggregation state because of the limitation of intramolecular rotation. Consequently, we propose a mechanism of aggregation-induced radical to understand the driving force of the open-shell diradical formation of DTP-TDPP based on the ESR spectroscopy test in different proportions of mixed solvents. Our results demonstrate the thermally-excited triplet state for donor-acceptor organic semiconductors, providing a novel view to comprehend the intrinsic chemical structure of donor-acceptor organic semiconductors, as well as the potential electronic transition process between ground state and excited state.


History

Email Address of Submitting Author

celiy@scut.edu.cn

Institution

State Key Laboratory of Luminescent Materials and Devices, South China University of Technology

Country

China

ORCID For Submitting Author

0000-0002-7931-9879

Declaration of Conflict of Interest

No conflict of interest