Amplifying Circularly Polarized Luminescence with High Dissymmetry Factor over 10−2 Based on Robust Point Chirality Triptycene Derivatives

A pair of triptycene-bridged enantiomers with a robust point chirality and a donor–acceptor architecture were developed as direct emitters, donors of exciplex emitters, and exciplex hosts for circularly polarized organic light-emitting diodes (CP-OLEDs), respectively. The corresponding dissymmetry factor was sequentially amplified. Remarkably, the CP-OLED achieved a high external quantum efficiency of 31.8% and a dissymmetry factor of 2.2 × 10⁻².

Abstract

Chiral organic luminescent materials are promising candidates as direct emitting layers (EMLs) in circularly polarized organic light-emitting diodes (CP-OLEDs). However, most conventional systems suffered poor thermal stability of chiral configurations and low luminescent dissymmetry factors. Herein, we reported a pair of triptycene-bridged enantiomers with a point chirality and a donor–acceptor architecture. Robust point chirality, originating from quaternary bridgehead-carbons, prevented the common racemization during thermal sublimation. Thanks to the reduced electric transition dipole moment (µ_e) in donor–acceptor architecture, tuned parallel alignment between the further reduced µ_e and magnetic transition dipole moment (µ_m) in the exciplex emitter, and the utilized chiral exciplex host for energy transfer to phosphor, the corresponding dissymmetry factors of emitters were sequentially amplified from 3.3 × 10⁻⁴ to 4.5 × 10⁻³, and to 8.1 × 10⁻³. Remarkably, the CP-OLED device simultaneously achieved outstanding electroluminescence performance with a high external quantum efficiency of 31.8% and a large dissymmetry factor of 2.2 × 10⁻². This work provided a viable pathway for developing high-performance CP-OLED materials through synergistic structural, material, and device engineering.

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