Photo-induced handedness inversion with opposite-handed cholesteric liquid crystal.

Cholesteric liquid crystals (CLCs) are self-organized helical nano-structures that selectively reflect certain wavelength of a circularly polarized light. For most CLCs, the handedness is fixed once a chiral dopant is employed. Here, we report a handedness-invertible CLC through opposite-handed doping of a photo-sensitive chiral azobenzene dopant and a photo-stable chiral dopant. With high solubility of the photo-sensitive chiral dopant, the Bragg reflection can be tailored from right-handed to left-handed upon UV exposure. The reversed process can be easily carried out through heating.