Broadband Circular Polarizing Film Based on Chiral Nematic Liquid Crystals

Films capable of broadband circular polarization of light are important for many optical applications. Owing to their intrinsic chiral nematic mesostructure, freestanding films of cellulose nanocrystals can reflect circularly polarized light, but this is typically restricted to a narrow part of the spectrum. A new micelle-assisted self-assembly strategy is discovered to prepare freestanding films of cellulose nanocrystals that display circularly polarized reflection across the visible spectrum. The inexpensive and simple approach distorts the chiral nematic domains with variations of helical pitches and helical axis orientations, leading to broadband polarization. This novel method may be applicable to modifying the optical properties of other chiral nematic liquid crystals, which are widely used in display technologies.