Circularly polarized room-temperature phosphorescence (CPRTP) materials integrate circularly polarized emission with long-lived triplet excitons, offering unique potential for anticounterfeiting and optical information storage. However, existing polymer-based CPRTP systems often suffer from short phosphorescence lifetimes and low luminescence dissymmetry factors (g lum ). Here, we report a rational copolymerization strategy to construct high-performance CPRTP polymers by precisely regulating their liquid crystal phase structures. A nematic cyanobiphenyl monomer (MA4BiCN), a chiral cholesterol-based phosphorescent monomer (M6Chol), and a phosphorescent dibenzofuran monomer (M6DFM) are copolymerized to yield CN(x)-Chol(y)-DFM(z) copolymers with tunable compositions. Increasing M6Chol content drives a mesophase transition from a left-handed cholesteric to a left-handed twist grain boundary A phase, enhancing molecular ordering. This structural evolution significantly extends room-temperature phosphorescence lifetimes from 314.9 ms for CN(0.63)-Chol(0.18)-DFM(0.19) to 685.8 ms for CN(0.14)-Chol(0.65)-DFM(0.21). The well-defined chiral liquid crystal phases also induce strong selective reflection, resulting in pronounced circularly polarized luminescence, with maximum g lum values of −0.52 (fluorescence) and −0.38 (phosphorescence) for CN(0.47)-Chol(0.34)-DFM(0.19). Furthermore, the dual phosphorescent units allow composition-dependent tuning of emission color and afterglow behavior. This work demonstrates that controlling the polymer phase structure is an effective strategy to simultaneously enhance phosphorescence lifetime and achieve high g lum in CPRTP polymers.
Wu et al. (Sun,) studied this question.
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