Infrared shutter using cholesteric liquid crystal.

Abstract

In this paper, we propose an infrared light shutter device using cholesteric liquid crystals. The pitch of the device corresponds to the wavelengths of the infrared region with a strong thermal effect. This device is intended for use as a smart window to maintain an optimal indoor temperature by controlling the infrared radiation coming from the sun. The proposed cholesteric device switches between the planar state and the isotropic state by controlling the temperature using an electrically heated transparent electrode made of indium tin oxide. A window with a planar state that reflects infrared radiation would be used mainly in the summer, while the isotropic state that transmits infrared would be applied in the winter. The proposed device produced a variety of gray levels of transmittance based on the temperature, and thus it can provide the proper temperature for each user. The easy fabrication process gives it appeal as a functional device in the smart window market, and it compares favorably with previous light shutter devices. The infrared shutter is expected to be useful for next-generation window applications.