Controllable CPL response driven by achiral UV-photosensitive dichroic dye through cholesteric liquid crystals

Versatile stimuli-responsive circularly polarized luminescent (CPL) materials have potential applications in information storage, security encryption, and intelligent displays. In this study, the Z/E isomerization of ultraviolet (UV)-photosensitive achiral alpha-cyanostilbene derivative was used as an achiral dichroic dye (Switch) to drive the controllable CPL-active response in cholesteric liquid crystals (CLCs). Under irradiation by 365 nm UV light, the resulting CLCs-Z-Switch underwent a Z-to-E configuration isomerization as CLCs-E-Switch, accompanied by a decrease in its dichroic order parameter (SF value) from 0.15 to 0.07. Although the quantum yield (QY) of CLCs-E-Switch increased from 8.1% (CLCs-Z-Switch) to 16.8%, the corresponding glum values of CPL emission decreased from +0.55/-0.57 to +0.37/-0.39 due to a decrease in the order of helical arrangement of E-Switch in E7 media. This study enables photosensitive CLCs-Switch to be applied for optical information storage devices.