Reversible Photoswitchable Axially Chiral Dopants with High Helical Twisting Power

Abstract

A new class of photoswitchable axially chiral dopants with high helical twisting power was synthesized. Their reversible photoresponsive properties were well demonstrated. These materials are found suitable for dopants in chiral nematic materials for applications in novel optically addressed displays, i.e., photodisplay. Optically addressed images were demonstrated. The dopants were sufficiently responsive to an addressing light source such that a high-resolution image with gray scale could be imaged in a few seconds of irradiation time. It was further found that an image could be retained on the screen at room temperature for 24 h before being thermally erased. The high solubility of these materials in a nematic host is also of commercial interest for stability in display applications. It is worth noting here that the photodisplay device can display a high-resolution image without the need of attached drive and control electronics, substantially reducing the cost of the display unit for use in applications where paper is currently used. Their high twisting power and large solubility in common nematic liquid crystal host can facilitate small amounts of doping to induce mesophase chirality and magnify the photocontrol effect.