Phototuning structural color and optical switching cholesteric textures in azobenzene-doped cholesteric liquid crystals

Abstract

Photoresponsive cholesteric liquid crystals (CLCs) can selectively reflect colors upon exposure. However, achieving simultaneous erasure rewriting and color tuning in CLCs through light exposure remains a formidable challenge. Interestingly, CLCs doped with azobenzene show rapid RGB color shifts when exposed to 365 nm wavelength light within a few seconds. This fully reversible process is also easily attainable under 405 nm wavelength irradiation. Furthermore, intense light induces isomerization in the azobenzene molecules, disrupting the molecular arrangement of the liquid crystals and facilitating the transition from a planar state (P-state) to a focal conic state (FC-state). This transition leads to the complete elimination of reflected colors in CLCs. Alongside mechanical stress and electrical responsiveness, these properties make CLCs doped with azobenzene highly attractive and applicable in diverse areas such as color displays, information encryption, and anti-counterfeiting.