Color-tunable, high-dissymmetry circularly polarized phosphorescence in purely organic chiral nematic phases

Abstract

Purely organic circularly polarized phosphorescence (CPP) materials are promising candidates for chiral optoelectronic and photonic applications but remain limited by challenges in achieving both high quantum efficiency and strong dissymmetry. Here, we report a CPP system based on brominated cholesteric liquid crystalline (CLC) molecules that spontaneously self-assemble into left-handed chiral nematic (N*) phases. The resulting films display efficient CPP at 450 nm, with a phosphorescent quantum yield of 36% and a dissymmetry factor of glum = +0.30. This performance arises from enhanced spin–orbit coupling and suppression of non-radiative decay via long-range helical ordering and optical rotation. Furthermore, doping the N* matrix with an achiral fluorescent dye (8CNS) enabled green circularly polarized fluorescence through triplet-to-singlet Förster resonance energy transfer, accompanied by inversion of emission handedness (glum = –0.32) due to selective reflection within the doped N* phase. These findings demonstrate a modular strategy for tuning chiroptical emission properties in purely organic systems and establish CLC scaffolds as versatile platforms for developing high-performance CPP materials.