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

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.