Bistable switching between homeotropic and focal-conic states in an ion-doped chiral nematic liquid crystal cell

Abstract

Operation of a light shutter usually requires that an electric addressing field is applied continuously to switch between a transparent and an extinct or opaque scattering state. To achieve low-power operation, a bistable light shutter, which consumes power only when switching between the two stable states, is preferred. Here, switching between the two stable states is induced with a short pulse rather than by applying a continuous field. In this work, we report bistable switching of an ion-doped chiral nematic liquid crystal between the transparent homeotropic and the scattering focal-conic states. Owing to ionic dopants, the use of complicated patterned electrodes or dual-frequency liquid crystals was not required for switching of the device. The light shutter exhibited an opaque state, which has higher scattering than previously reported bistable light shutters. Furthermore, doping of the reported device with a dichroic-dye enabled simultaneous control of light scattering and absorption. A new candidate for both smart window and see-through display applications is presented.