Light‐Driven Sign Inversion of Circularly Polarized Luminescence Enabled by Dichroism Modulation in Cholesteric Liquid Crystals

Stimuli‐responsive circularly polarized luminescence (CPL) materials show great promise in applying information encryption and anticounterfeiting. Herein, light‐driven CPL sign inversion is achieved by combining a photoresponsive achiral negative dichroic dye (KG) and a static achiral positive dichroic dye (NR) as dopants at the 0.5:0.5 weight ratio into the cholesteric liquid crystal (CLC) host. The side chains of KG undergo trans/cis isomerization after 365 nm UV light irradiation, leading to the dichroism (SF) decrease. The |glum| value of CLC doping with KG (CLC‐KG) weakens from 0.67 to 0.28 in response to the order degree change. Taking advantage of its unique CPL response property, the light‐driven CPL sign inversion is achieved (from −0.20/0.14 to 0.02/−0.04) by incorporating NR (0.5:0.5) into the CLC‐KG with helical superstructure static. Based on the synergistic use of circular polarization and responsiveness state as cryptographic primitives, the multidimensional information encryption CLC system can be realized. Light‐driven circularly polarized luminescence (CPL) material with the sign inversion character is constructed by incorporating photosensitive negative dichroic dye and an appropriate ratio of the opposite dichroic achiral dye into the cholesteric liquid crystals. The CPL signals invert without helical superstructure change. These results provide valuable avenues for developing stimuli‐responsive CPL tools for information security and anticounterfeiting applications.