Programmable Coloration and Patterning on Reconfigurable Chiral Photonic Paper

Abstract Responsive photonic crystals are widely employed to construct rewritable paper, where patterns are written and erased repeatedly via color switching. The working principle mainly lies in the changes on the lattice constant of periodic structures, which, however, restricts the localized color tuning of the recorded patterns and thus limits multicolor information transfer. Herein, a novel strategy is reported to write, erase, and importantly to tune the colors by developing unique light‐driven cholesteric liquid crystals (CLCs) that possess self‐organized helical superstructures with two structural elements of pitch lengths (lattice constant) and helical axes (reconfiguration). Reconfiguration of the helical axes provides two high‐contrast optical states for writing and erasing by pressure and electricity, whereas precise photocontrol of the pitch lengths contributes to localized color tuning. These features primarily capitalize on the light‐driven CLC with diverse photostationary colors, which is induced by a newly designed binary chiral system and confined in the polymer dispersed liquid crystal layer. Distinct multicolor patterns are mechanically written, optically tuned, and electrically erased on the rewritable photonic paper in a programmable manner. Such photonic paper has potential to record, program, and remember optically addressed images in visualized color information and user‐interactive display technologies.