Electrohydrodynamically Driven Broadband and Color‐Shifting in Cholesteric Liquid Crystals

ABSTRACT

Rapid, multimode photonic bandgap tuning of cholesteric liquid crystals (CLCs) is achieved by harnessing ion‐driven electrohydrodynamic (EHD) effects. By utilizing CLCs with negative dielectric anisotropy doped with ions and applying low‐frequency AC voltage, two distinct optical phenomena are observed: a rapid color‐shifting mode and a broadening mode. This method achieves dynamic tunability and enhanced optical performance with significantly reduced response times. The color‐shifting mode enables the reflection band to traverse the entire visible spectrum within milliseconds while maintaining a reflection of approximately 37% when shifting from red to blue. In the broadening mode, the reflection band expands to cover the entire visible spectrum with an average reflection exceeding 30%. These results, driven by electrohydrodynamic effects and ion concentration, highlight unique advantages, including fast response, simplicity, and durability. This study not only introduces a fundamentally different mechanism for reflection band tuning but also demonstrates significant potential for material applications in dynamic optics, advanced coatings, and adaptive photonic devices.