Abstract: | Thiols are prone to react with a multitude of various functional groups in high yields, which has been widely used for surface‐ and particle‐patterning, bioorganic synthesis, polymer modification, imprint nanolithography, the fabrication of optical components, hydrogel synthesis, and the curing of hard protective coatings. In this work, a chiral thiol with a high helical twisting power was synthesized through a novel synthetic route with high selectivity, yield, and cost‐effectiveness. It was then used to fabricate a liquid‐crystal composite film with ultra‐wide broadband reflection via thiol click chemistry. Cholesteric liquid‐crystal materials with broadband reflection have many potential applications for broadband polarizers, polarizer‐free displays, organic optical data storage media, smart switchable reflective windows, and continuous waveband laser protection. |