A chiral spirofluorene‐embedded multiple‐resonance thermally activated delayed fluorescence emitter for efficient pure‐green circularly polarized electroluminescence
Xu‐Feng Luo,
Shi‐Quan Song,
Xueying Wu,
Ching‐Fai Yip,
Songliang Cai,
You‐Xuan Zheng
Affiliations
Xu‐Feng Luo
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering Nanjing University Nanjing P. R. China
Shi‐Quan Song
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering Nanjing University Nanjing P. R. China
Xueying Wu
GDMPA Key Laboratory for Process Control and Quality Evaluation of Chiral Pharmaceuticals, Guangzhou Key Laboratory of Analytical Chemistry for Biomedicine, School of Chemistry South China Normal University Guangzhou P. R. China
Ching‐Fai Yip
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering Nanjing University Nanjing P. R. China
Songliang Cai
GDMPA Key Laboratory for Process Control and Quality Evaluation of Chiral Pharmaceuticals, Guangzhou Key Laboratory of Analytical Chemistry for Biomedicine, School of Chemistry South China Normal University Guangzhou P. R. China
You‐Xuan Zheng
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering Nanjing University Nanjing P. R. China
Abstract The simultaneous achievement of chiral multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters with narrowband and circularly polarized electroluminescence (CPEL) poses a challenge. Herein, a MR‐TADF emitter, Spiro‐BNCz, embedding spirofluorene structure was developed and chiral separated, whose emission peaks at 528 nm in toluene with Commission Internationale de L'Eclairage coordinates of (0.26, 0.69). The conjugation extension caused by embedding sulfur substituted spirofluorene on B/N framework shortens the singlet‐triplet energy gap and increases spin‐orbital coupling matrix element. Therefore, a fast reverse intersystem crossing rate constant of 2.8 × 106 s−1 and a high photoluminescence efficiency of 92% in film were achieved. The organic light‐emitting diode (OLED) exhibits a maximum external quantum efficiency of 32.3%. Particularly, the circularly polarized OLEDs based on Spiro‐BNCz enantiomers show symmetric CPEL with dissymmetry factors (|gEL|) ≈ 10−3.
