Color-tunable, high-dissymmetry circularly polarized phosphorescence in chiral nematic phases: self-assembly, energy transfer, and handedness inversion

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 high-performance CPP system based on brominated cholesteric liquid-crystalline (CLC) molecules that spontaneously self-assemble into left-handed chiral nematic (N*) phases. Among the series, Br10Ch exhibits bright blue CPP at 450 nm with a phosphorescent quantum yield of 36% and a dissymmetry factor of g_lum = +0.30, enabled by enhanced spin–orbit coupling and long-range helical ordering that suppress non-radiative decay. Furthermore, doping the N* matrix with an achiral fluorescent dye (8CNS) enables triplet-to-singlet Förster resonance energy transfer, yielding green circularly polarized fluorescence at 502 nm with inverted handedness (g_lum = −0.32) via selective reflection within the cholesteric host. This combined color tunability and handedness switching in a purely organic system provides a modular approach for tailoring chiroptical emission without heavy metals. Our findings establish CLCs as versatile supramolecular scaffolds for high-performance CPP, offering new opportunities for dynamic optical control in displays, data encryption, and advanced photonic devices.