Tunable Circularly Polarized Afterglow from Cholesteric Liquid Crystalline Polymer Networks

Abstract

Circularly polarized afterglow (CPA) materials have demonstrated significant potential in diverse applications. Nevertheless, the development of organic CPA materials simultaneously possessing large luminescence dissymmetry factors (g_lum) and ultralong lifetimes remains a formidable challenge. Herein, a series of liquid crystalline polymer network films with tunable CPA properties were fabricated via photopolymerization of liquid crystalline mixtures doped with varying amounts of binaphthyl derivatives. The resulting polymer films exhibit structural colors, room-temperature phosphorescence (RTP), and circularly polarized RTP properties, with phosphorescence dissymmetry factors reaching up to 0.70 and tunable lifetimes extending to 730 ms. Through further photopolymerization of cholesteric liquid crystalline mixtures doped with rhodamine 6G (Rh6G), a commercially available fluorescent dye, lifetime- and color-tunable CPA with enhanced g_lum values and quantum yields as high as 8.6% was achieved via phosphorescence energy transfer. Furthermore, the fabricated film patterns display distinct colors in reflection, fluorescence, and phosphorescence modes. This work presents a facile strategy for preparing CPA films with large g_lum values as well as tunable lifetimes and colors, which hold promise for applications in image encryption and anticounterfeiting technology.