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Citation
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HERO ID
6936947
Reference Type
Journal Article
Title
A Red Thermally Activated Delayed Fluorescence Emitter Simultaneously Having High Photoluminescence Quantum Efficiency and Preferentially Horizontal Emitting Dipole Orientation
Author(s)
Gong, Xu; Wu, CC; Gong, S; Yang, C; Li, Pan; Huang, YuH; Wang, CYu; Lu, CHan; Lee, WeiKai; Zhong, C; Chen, Z; Ning, W; ,
Year
2020
Is Peer Reviewed?
Yes
Journal
Advanced Functional Materials
ISSN:
1616-301X
EISSN:
1616-3028
Publisher
WILEY-V C H VERLAG GMBH
Location
WEINHEIM
DOI
10.1002/adfm.201908839
Web of Science Id
WOS:000515672300001
Abstract
The development of red thermally activated delayed fluorescence (TADF) emitters having excellent optoelectronic properties and satisfactory electroluminescence efficiency is full of challenges due to strict molecular design principles. Two red TADF molecules, 3-(9,9-dimethylacridin-10(9H)-yl)acenaphtho[1,2-b]quinoxaline-9,10-dicarbonitrile and 3-(2,7-dimethyl-10H-spiro[acridine-9,9 '-fluoren]-10-yl)acenaphtho[1,2-b]quinoxaline-9,10-dicarbonitrile, are developed by adopting a donor-acceptor molecular architecture bearing an electron-accepting acenaphtho[1,2-b]quinoxaline-9,10-dicarbonitrile (ANQDC) moiety and a 9,9-dimethyl-9,10-dihydroacridine or 2,7-dimethyl-10H-spiro[acridine-9,9 '-fluorene] electron donor. The combined effects of rigid and planar D/A moieties and highly steric hindrance between D and A groups endow both molecules with high rigidity to suppress nonradiative decay processes, resulting in high photoluminescence quantum efficiencies (phi(PL)s) of up to 95%. Attributed to the linear and planar acceptor motif and rod-like molecular configuration, both emitters achieve high horizontal ratios of emitting dipole orientation of approximate to 80%. The organic light-emitting diodes (OLEDs) based on both emitters exhibit red emissions peaking at approximate to 615 nm and successfully afford ultrahigh electroluminescence performance with an external quantum efficiency of nearly 28% and a power efficiency of above 50 lm W-1, on par with the state-of-the-art device efficiency for red TADF OLEDs. This presents a feasible design strategy for excellent TADF emitters simultaneously possessing high phi(PL)s and horizontally aligned emitting dipoles.
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