Fabrication of high-transmittance and fast-response bistable dual-frequency CLC cells

Abstract

Liquid crystal devices are popularly used in the design of smart windows. However, the continuous electric field required for their operation may cause unnecessary energy loss and there is a risk of state transition when the electric field disappears. To overcome these problems, bistable devices were developed that exhibit electro-optic memory. In this study, we demonstrate the synthesis of a novel liquid crystalline acrylic chiral dopant. The polymerizable chiral dopant is expected to disperse and be fixed in liquid crystals, homogeneously revealing higher chiral efficiency. Incorporation of the synthesized chiral dopant into the dual frequency cholesteric liquid crystal results in a bistable display performance with a high transmittance of 97.6% and a fast response time of 1.5 ms. Each of the transparent “ON” and opaque “OFF” states was maintained without the bias of a continuous electric field. The achieved results show the possible application of the synthesized acrylic chiral dopant on a bistable dual frequency cholesteric liquid crystal display (BDFCLC) for smart windows and other devices. BackgroundThe continuous electric field required for their operation may cause unnecessary energy loss and there is a risk of state transition when the electric field disappears. MethodsTo fabricate a smart optical device with fast transition between “ON” and “OFF” states, and with continuously electric field addition, a new acrylic chiral dopant was synthesized and mixed with commercially available dual frequency nematic liquid crystal as a new cholesteric liquid crystal material possessing both perpendicular and planer arrangements with and without one-time electric field addition. Significant findingsIn this study, we demonstrate the synthesis of a novel liquid crystalline acrylic chiral dopant. The polymerizable chiral dopant is expected to disperse and be fixed in liquid crystals, homogeneously revealing higher chiral efficiency. Incorporation of the synthesized chiral dopant into the dual frequency cholesteric liquid crystal results in a bistable display performance with a high transmittance of 97.6% and a fast response time of 1.5 ms. Each of the transparent “ON” and opaque “OFF” states was maintained without the bias of a continuous electric field.