Cholesteric liquid crystal (ChLC) materials with broadband reflection are witnessing a significant surge in interest due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship. Nowadays, by the virtue of building self-organized nanostructures with pitch gradient or non-uniform pitch distribution, extensive work has already been performed to obtain ChLC films with a broad reflection band. This critical review systematically summarizes the optical background of the ChLCs with broadband reflection characteristics, methods to obtain broadband reflection of ChLCs, as well as the application in this area. Combined with the research status and the advantages in the field, the challenges and opportunities of applied scientific problems in the research direction are also introduced.
Keywords: broadband reflection; cholesteric phase; liquid crystals; non-uniform pitch distribution; pitch gradient; selective reflection.