Highly Efficient Circularly Polarized Luminescence Based on Center-Chiral Frustrated Lewis Pairs

Abstract

Achieving high-efficiency circularly polarized luminescence (CPL) in organic light-emitting diodes (OLEDs) presents a significant challenge, particularly for center-chiral systems, due to the inherent trade-off between high luminescence efficiency and large luminescence dissymmetry factors. In this work, we introduce a center-chiral frustrated Lewis pair (FLP) design to overcome this limitation. By integrating a stereogenic carbon center into a fluorene scaffold, we create a unique interaction between a boron-based multi-resonance (MR) thermally activated delayed fluorescence (TADF) Lewis acid and an arylamine Lewis base. This sterically hindered design prevents strong charge transfer while optimizing the alignment between electric and magnetic dipole moments for amplified CPL signals. Our OLEDs achieve impressive electroluminescence (EL) dissymmetry factors (|g_EL|) of 6.64 × 10⁻³, external quantum efficiencies (EQEs) of up to 30.4%, and sub-30 nm spectral linewidths. These improvements yield a Figure of Merit (FoM = EQE × |g_EL|) of 1.91 × 10⁻³, the highest reported for center-chiral CPL devices. These findings demonstrate the effectiveness of the center-chiral FLP design in overcoming the long-standing trade-off between polarization and efficiency in CPL devices.