Strong Circularly Polarized Luminescence Promoted by AIE‐active Chiral Co‐assemblies in Liquid Crystal Polymer Films

Abstract

Recently, extensive works have focused on increasing the dissymmetry factors (glum) of various circularly polarized luminescence (CPL) materials, which is one of the most important factors for future applications of CPL. Herein, we designed a chiral co‐assembled liquid crystal polymer (LCP) PTZ@R/S‐PB2, which was prepared by chiral binary co‐polymer (R/S‐PB2) doped with achiral phenothiazine derivation dye (PTZ). For comparison, ternary co‐polymerized LCP (R/S‐PT) was synthesized by co‐polymerizing with mesogenic monomer, chiral monomer and emissive monomer. Both PTZ@R/S‐PB2 and R/S‐PT showed aggregation‐induced emission (AIE) properties. Interestingly, the CPL signals of both PTZ@R/S‐PB2 and R/S‐PT were reversed and amplified after thermal annealing treatment. The |glum| values of the co‐assembled PTZ@R/S‐PB2 were up to 0.13 at a 32 nm thickness, which was 5.4 times that of R/S‐PT (|glum| = 0.024). This is due to PTZ@R/S‐PB2 could form more orderly chiral co‐assembly structures. Noticeably, increasing the LCP film thickness could further improve the glum value, and the maximum glum of PTZ@R/S‐PB2 could be enhanced to 0.91 at a 220 nm thickness.

Ultrastrong Circularly Polarized Luminescence Triggered by the Synergistic Effect of Chiral Coassembly and Selective Reflective Cholesteric Liquid Crystal Film

“…This factor is determined by the equation g lum = 2­( I L – I R )/( I L + I R ), where I L and I R represent the intensities of left- and right-handed CPL emission, respectively. However, the practical application of CPL materials is hindered by the inability of existing CPL materials to achieve sufficiently high dissymmetry factor ( g lum ) values. − To date, several strategies have been developed for high-performance CPL materials, including chiral supramolecular assemblies such as liquid crystals (LCs), , Förster resonance energy transfer (FRET), − triplet–triplet annihilation-based photon upconversion, , and helical polymers. − Notably, cholesteric liquid crystals (CLCs) have received particular attention due to their unique optical capability to generate CPL with significantly high g lum values through selective reflection or chiral supramolecular coassembly. , …”