Photoinduced isotropic state of cholesteric liquid crystals: Novel dynamic photonic materials

The photoinduced isotropic (PHI) state of cholesteric liquid crystals (CLCs) induced by the UV irradiation of a highly doped (azobenzene liquid crystal) CLC can be stable for tens of hours dominated by the lifetime of the cis isomers. Low-power laser light can be used to write complex 2D images (a car is shown), where the contrast arises from restoration of the reflective cholesteric phase.