Photoswitching of ferroelectric liquid crystals using photochromic dopants

Abstract

This review focuses on the development of photochromic dopants designed to trigger the switching of ferroelectric liquid crystals via photomodulation of the spontaneous polarization (P_S). The photomodulation of P_S has been achieved by reducing the polar order of a FLC host via the change in shape of azobenzene dopants upon trans–cis photoisomerization, and via the loss of conformational flexibility of dithienylethene dopants upon photocyclization. It has also been achieved by increasing the polarization power of chiral thioindigo dopants in achiral SmC hosts via a photoinduced change in transverse dipole moment. A photoinversion of the sign of P_S has been achieved using an “ambidextrous” thioindigo dopant with two competing chiral side-chains that induce polarizations of opposite handedness.