Optimization of polymer‐stabilized bistable black‐white cholesteric reflective display

Cholesteric liquid crystals at zero field exhibit two optically contrasting stable states: planar texture and focal‐conic texture. When a cholesteric liquid crystal is in the planar texture, the helical axis is perpendicular to the cell surface; the material Bragg‐reflects colored light. When the liquid crystal is in the focal‐conic texture, the helical axis is more or less parallel to the cell surface; the material is forward‐scattering and has a black appearance if the back plate of the cell is painted black. We develop a cholesteric liquid‐crystal/polymer composite in which a small amount of polymer is dispersed in the liquid crystal. The dispersed polymer changes the planar texture to a poly‐domain structure, which has a white appearance but has little effect on the optical properties of the focal‐conic texture. The result is a bistable black‐white reflective display which is a good candidate for electronic‐paper applications.