期刊
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
卷 58, 期 38, 页码 13522-13531出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/anie.201906371
关键词
energy transfer; intermolecular pi-pi stacking; luminescence; organic crystals; thermally activated delayed fluorescence
资金
- National Key R&D Program of China [2016YFB0401004]
- National Natural Science Foundation of China [91833304, 51625301, U1601651, 51573059]
- 973 Project [2015CB655003]
- Guangdong Provincial Department of Science and Technology [2016B090906003, 2016TX03C175]
Thermally activated delayed fluorescent (TADF) materials generally suffer from severe concentration quenching. Efficient non-doped TADF emitters are generally highly twisted aromatic amine-based compounds with isolated chemical moieties. Herein we demonstrate that co-facial packing and strong pi-pi intermolecular interactions give rise to bright TADF emissions in non-doped film and crystalline states within the compound 2,4-diphenyl-6-(thianthren-1-yl)-1,3,5-triazine (oTE-DRZ). Quantum chemistry simulations indicate that a disperse outer orbital of sulfur atoms, a folded thianthrene plane (for a reduced donor-acceptor distance), and a triazine acceptor with n-pi* character, generate a spatially conjugated transition with a small singlet-triplet splitting energy. In company with a highly emissive non-doped film, the corresponding organic light-emitting diode achieved a 20.6 % external quantum efficiency, verifying its potential for high-performance optoelectronic applications. In a crystalline state, it was verified that intra- and intermolecular dual TADF assisted by a hidden room-temperature phosphorescent state. This state could preserve the long-lived excitons while suppressing non-radiation, and it could serve as a spring-board for cascade up-conversion processes. The oTE-DRZ crystal showed greenish-blue emission with a very high photoluminescent quantum yield of approximately 87 %, which is the highest among all TADF crystals reported to date.
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