Smart Reflector Using Photoluminescence Cholesteric Liquid Crystal for Electrowetting Displays

We fabricated a smart reflector using stacked double photoluminescence cholesteric liquid crystal (PL-CLC) layers. This smart reflector reflects external incident light and emits light by converting the UV light coming from a backlight. The smart reflector made of two PL-CLC layers of left- and right-handed helixes has a high effective reflectance owing to the photonic crystal structure of the CLCs and the re-emission of light after absorbing the short-wavelength external lights. The smart reflector can be used to devise a reflective-emissive-type display by combining with any reflective display; here we demonstrate an electrowetting display (EWD) device combined with the smart reflector. The EWD with smart reflector has good visibility under all ambient brightness conditions. Hence, the smart reflector can provide a new way to achieve a low-power portable display with excellent visibility in conditions ranging from dark surroundings to under bright sunlight.