Bistable Cholesteric Liquid Crystal Films with Excellent Electro-Optical Performance and Spacing Stability for Reflective Displays

A bistable cholesteric liquid crystal display offers the Bragg selective reflection over the incidence of light to address various needs in energy conservation, long image storage time, and no backlight; yet, most of the existing technologies still suffer from unstable cell spacing in the curved state. In this work, a bistable cholesteric liquid crystal film with polymer spacer columns for flexible displays was prepared by stepwise UV light polymerization. By investigating the effects of cross-linking agent concentration and liquid crystal content, a formulation composition with optimal electro-optical performance was determined. Then, the influences of different process conditions for mask polymerization on the morphologies of polymer spacer columns and the electro-optical performance were systematically investigated. The results show that films with polymer spacer columns exhibit better electro-optical performance and spacing stability compared to conventional bistable liquid crystal films. Therefore, the bistable liquid crystal films reported in this paper show broad application prospects, especially in flexible displays.