Circularly polarized luminescence with large dissymmetry factors based on perovskite and cholesteric liquid crystal polymer network films†

The modulation of colour, handedness, and g_lum values of circularly polarized luminescence (CPL) is of great significance for flexible displays and anti-counterfeiting. Perovskites CsPbX₃ (X = Cl, Br, I) with narrow emission bands were successfully prepared and doped into polymer matrices (PMMA or PAN) to create fluorescent layers. Subsequent integration with highly reflective cholesteric liquid crystal polymer network (CLCN) films yielded a series of CPL-active composite films. When the emission band of the perovskite layer matches the intense Bragg reflection of CLCN film, high |g_lum| values (up to 1.73) were obtained. The correlation between the selective Bragg reflection of CLCN and the tuning of g_lum values was demonstrated. An excellent CPL anti-counterfeiting property was observed for the PMMA–CsPbBr₃/CLCN composite film. This work not only tuned the CPL handedness and achieved large |g_lum| values, but also provided a practical method for decorative, display, and anti-counterfeiting applications.