Xiaoyi Lai
(, ), Junqing Wang
(, ), Xiaolong Liu
(, ), Lei Hua
(, ), Bin Li
(, ), Weiguo Zhu
(, ), Jun Yeob Lee, Yafei Wang
(, )
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引用次数: 0
Abstract
Exciplex system is a charming candidate for thermally activated delayed fluorescence (TADF) due to its intrinsic small energy difference between the lowest singlet state and triplet excited state (ΔEST). However, high emission efficiency and fast radiative decay rate are still a formidable task for the exciplex emission. Herein two novel tri(triazolo) triazine-based TADF emitters, named TTT-HPh-Ac and TTT-MePh-Ac, are synthesized and characterized. Using such TADF emitters as the donor molecule and (1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-dial)tris(diphenylphosphine oxide) (PO-T2T) as the acceptor molecule, the exciplex system of TTT-HPh-Ac:PO-T2T and TTT-MePh-Ac:PO-T2T are prepared, which show a tiny ΔEST of 40 ± 20 meV and fast reverse intersystem crossing rate. As a result, very high emission efficiency (97%) and a small non-radiative decay rate are detected for the exciplex TADF system. The solution processable organic light-emitting diode using the exciplex system as the emitter achieves a maximum external quantum efficiency (EQEmax) of 17.0%. When using the exciplex as the host matrix, the TTT-MePh-Ac:PO-T2T based solution processable device shows a better performance with an EQEmax of 20% with a very small efficiency roll-off of 6% at 1000 cd m−2. This work proves that the molecule with both intramolecular hydrogen bonding and proper twisted molecular geometry in exciplex is more favorable to enhance its emission efficiency and suppress the non-radiative transition, which provides a new way to develop efficient and stable exciplex emitters.
期刊介绍：
Science China Materials (SCM) is a globally peer-reviewed journal that covers all facets of materials science. It is supervised by the Chinese Academy of Sciences and co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China. The journal is jointly published monthly in both printed and electronic forms by Science China Press and Springer. The aim of SCM is to encourage communication of high-quality, innovative research results at the cutting-edge interface of materials science with chemistry, physics, biology, and engineering. It focuses on breakthroughs from around the world and aims to become a world-leading academic journal for materials science.
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