Transparent UV-blocking photonic film based on reflection of cholesteric liquid crystals

An optically transparent bilayer cholesteric liquid crystal (CLC) solid film capable of almost completely rejecting ultraviolet (UV)-A light was fabricated with a bilayer CLC film comprising double handed CLC layers using UV-curing reactive mesogen mixtures (RMMs) doped with LC756 and S811. The concentrations of S811 and LC756 in RMMs and the film thickness were optimized to achieve more than 98% UV blocking (in the UV-A region) and more than 95% transparency (in the visible region). The proposed approach provides a simple and reliable fabrication process that can be employed in practical applications such as smart windows, eyeglasses, and lenses.