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Chiral Spiro‐Axis Induced Blue Thermally Activated Delayed Fluorescence Material for Efficient Circularly Polarized OLEDs with Low Efficiency Roll‐Off
Author(s) -
Zhang YiPin,
Liang Xiao,
Luo XuFeng,
Song ShiQuan,
Li Si,
Wang Yi,
Mao ZhiPing,
Xu WenYe,
Zheng YouXuan,
Zuo JingLin,
Pan Yi
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202015411
Subject(s) - oled , quantum efficiency , electroluminescence , quantum yield , photoluminescence , fluorescence , materials science , singlet state , circular polarization , intramolecular force , photochemistry , luminescence , optoelectronics , chemistry , optics , atomic physics , physics , stereochemistry , nanotechnology , layer (electronics) , excited state , microstrip
A spiro‐axis skeleton not only introduces circularly polarized luminescence (CPL) into thermally activated delayed fluorescence (TADF) molecules but also enhances the intramolecular through space charge transfer (TSCT) process. Spiral distributed phenoxazine and 2‐(trifluoromethyl)‐9 H ‐thioxanthen‐9‐one‐10,10‐dioxide act as donor and acceptor units, respectively. The resulting TADF enantiomers, ( rac )‐OSFSO, display emission maxima at 470 nm, small singlet‐triplet energy gap (Δ E ST ) of 0.022 eV and high photoluminescence quantum yield (PLQY) of 81.2 % in co‐doped film. The circularly polarized OLEDs (CP‐OLEDs) based on ( R )‐OSFSO and ( S )‐OSFSO display obvious circularly polarized electroluminescence (CPEL) signals with dissymmetry factor up to 3.0×10 −3 and maximum external quantum efficiency (EQE max ) of 20.0 %. Moreover, the devices show remarkably low efficiency roll‐off with an EQE of 19.3 % at 1000 cd m −2 (roll‐off ca. 3.5 %), which are among the top results of CP‐OLEDs.