Single‐Layer Cholesteric Liquid Crystal Films With Extended High‐Reflectivity Bandwidth via Washing Out/Refilling and Secondary Polymerization

ABSTRACT The selective reflection mechanism fundamentally limits the ability of cholesteric liquid crystals (CLCs) to achieve broadband high‐reflectivity properties. This study proposes an innovative high‐reflectivity CLC film based on the washing out/refilling strategy, where the polymerizable chiral dopant HCM006 is covalently anchored within the polymer network to stabilize its structure. Initially, a right‐handed polymer network (RH‐CLC) was engineered through UV polymerization, followed by the washing out of non‐crosslinked components and the subsequent infiltration of a left‐handed cholesteric system (LH‐CLC) doped with S5011. Secondary polymerization facilitated spectral overlap between the reproduced reflective band of the polymer network and the broadband reflection of the refilled system, forming an extended high‐reflectivity band. By optimizing the component ratios and polymerization conditions of the RH‐CLC/LH‐CLC systems, the reflection bandwidth was significantly broadened. Polarized light microscopy and ultraviolet–visible‐near‐infrared spectrophotometry confirmed that the film maintained a well‐aligned planar texture throughout the fabrication process while achieving high reflectivity. Furthermore, the regulation of the chiral dopant concentration gradient achieved broadband high‐reflectivity properties in the infrared region, enabling effective infrared shielding. The enhanced near‐infrared reflection effectively mitigates solar‐induced internal heat accumulation, rendering this film advantageous for thermal management applications, such as energy‐saving architectural coatings or adaptive smart windows.