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

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.