Enhancing Circularly Polarized Luminescence in Chiral Fluorescent Dyes via Cholesteric Liquid Crystal Polymer Networks

Abstract

Materials with circularly polarized luminescence have garnered significant attention due to their applications in anticounterfeiting and displays. In this work, we synthesized a pair of AIEgens, designated as D- and L-TA-TPE, as dopants by utilizing tartaric acid and tetraphenylethylene. These AIEgens were incorporated as dopants into nematic liquid crystal polymer network films. The resulting films exhibited |g_lum| values of about 7.0 × 10^–3, which can be attributed to the chiral conformations of these two AIEgens. For the AIEgen-doped cholesteric liquid crystal polymer network (CLCN) films, due to the selective Bragg reflection of the CLCN films, the |g_lum| values reached about 0.7. When composite films incorporating both fluorescent and CLCN layers were examined, the |g_lum| values reached about 1.6. The |g_lum| value increased with increasing CLCN film thickness. AIEgen-doped CLCN patterns were prepared by using a photomask or through screen printing. Based on the selective Bragg reflection and the handedness of the CPL, distinct images were observed through the left- and right-handed circular polarizers. Therefore, these patterns are potentially applied for decoration and anticounterfeiting.