Multiple-resonance thermally activated delayed fluorescence materials based on phosphorus central chirality for efficient circularly polarized electroluminescence

• Published in: Materials horizons 2024-09, Vol.11 (19), p.4722-4729
• Main Authors: Wang, Yu, Lv, Zi-Yi, Chen, Zi-Xuan, Xing, Shuai, Huo, Zhong-Zhong, Hong, Xian-Fang, Yuan, Li, Li, Wei, Zheng, You-Xuan
• Format: Article
• Language: English
• Subjects: Chirality; Circular polarization; Doped films; Electroluminescence; Enantiomers; Fluorescence; Organic light emitting diodes; Phosphorus; Photoluminescence; Quantum efficiency; Resonance; Toluene
• ISSN: 2051-6347; 2051-6355; 2051-6355
• DOI: 10.1039/d4mh00605d

Circularly polarized organic light-emitting diodes (CP-OLEDs) hold great potential for naked-eye 3D displays, necessitating efficient chiral luminescent materials with an optimal CP luminescence (CPL) dissymmetry factor ( g ). Herein, we present the first chiral multiple resonance thermally activated delayed fluorescence (MR-TADF) materials containing a phosphorus chiral center by incorporating 5-phenylbenzo[ b ]phosphindole-5-oxide into the para -position of two MR-TADF cores. The compounds, NBOPO and NBNPO, exhibit photoluminescence peaks at 462 and 498 nm with narrow full-width at half-maximum values of 25 and 24 nm in toluene, respectively. Notably, ( R / S )-NBOPO and ( R / S )-NBNPO enantiomers display high quantum yields of 87% and 93% and symmetric CPL with | g PL | factors of 1.18 × 10 −3 and 4.30 × 10 −3 , respectively, in doped films. Moreover, the corresponding CP-OLEDs show impressive external quantum efficiencies of 16.4% and 28.3%, along with symmetric CP electroluminescence spectra with | g EL | values of 7.0 × 10 −4 and 1.4 × 10 −3 , respectively. This work presents the first chiral multiple resonance thermally activated delayed fluorescence materials based on a phosphorus chiral center. The circularly polarized devices exhibit high performances with dissymmetry factors of up to 1.46 × 10 −3 .