Aggregation‐Dependent Thermally Activated Delayed Fluorescence Emitters: AIE or ACQ?

The understanding of the excited state dynamics of thermally activated delayed fluorescence (TADF) materials is crucial. In this study, two donor–acceptor‐type TADF emitters with highly twisted conformation are synthesized. The emitters with subtle chemical modification of donor unit exhibit opposit...

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Bibliographic Details
Published in:Advanced optical materials 2023-06, Vol.11 (12), p.n/a
Main Authors: Wu, Yaxun, Ni, Fan, Chen, Zhanxiang, Yang, Wei, Xiang, Yepeng, Gong, Shaolong, Cao, Xiaosong, Yang, Chuluo
Format: Article
Language:English
Subjects:
aggregation‐caused quenching
aggregation‐induced emission
aggregation‐induced phosphorescence
Atomic energy levels
Chemical synthesis
Crystallography
Emission analysis
Emitters
Fluorescence
Materials science
Optics
Phosphorescence
room‐temperature phosphorescence
thermally activated delayed fluorescence
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Summary:The understanding of the excited state dynamics of thermally activated delayed fluorescence (TADF) materials is crucial. In this study, two donor–acceptor‐type TADF emitters with highly twisted conformation are synthesized. The emitters with subtle chemical modification of donor unit exhibit opposite aggregation luminescent behaviors: aggregation‐induced emission (AIE) and aggregation‐caused quenching (ACQ). Through the photophysical properties study, crystallographic analysis, and theory simulations, it is discovered that X‐aggregation supports AIE behavior by restricting the intramolecular motions and preserving TADF emission via an efficient reverse intersystem crossing (RISC) process, but on the other hand, H‐aggregation leads to ACQ behavior due to inhibited RISC, disabled TADF channel, and weak phosphorescence from radiative low‐lying triplet state. The findings shed light on the excited‐state dynamic behaviors of TADF emitters, which are dependent on aggregation. Two thermally actived delayed fluorescence (TADF) materials with subtle chemical modification exhibit different luminescent behavior in aggregation state. Rigid X‐aggregation maintains TADF emission with aggregation‐induced emission (AIE) feature and efficient intramolecular intersystem crossing (ISC) and reverse ISC(RISC) process, whereas compact H‐aggregation disables TADF emission channel with active intermolecular ISC, enhanced phosphorescence, and inhibited RISC process, which leads to aggregation‐caused quenching (ACQ) character.
ISSN:2195-1071
2195-1071
DOI:10.1002/adom.202300186