Fast-relaxation, dye-doped cholesteric liquid-crystal smart window with a perfect planar state

A fast-relaxation dye-doped cholesteric liquid crystal (DDCLC) smart window without any defects is prepared by the doping of a low bend elastic constants liquid crystal dimer 1'',7''-bis-(4-cyanobiphenyl-4'-yl)heptane (CB7CB). The ratio of the bend elastic constant to the twist elastic constant of the liquid crystals (LCs) is adjusted so that it equates to unity. The transient planar (TP) state and the planar (P) state are combined, so the relaxation time from the homeotropic (H) state to the P state is greatly. Moreover, the oily streaks of the P state are removed and the light scattering is lessened. The polarisation-independent DDCLC smart window switches between three states: the haze-free dark state, the high-haze dark state and the transparent state. The smart window can be used in situations where absorbed sunlight reduces room temperature and protects privacy.

Automated summary

A fast-relaxation dye-doped cholesteric liquid crystal (DDCLC) smart window without any defects is prepared by doping CB7CB, a liquid crystal dimer with low bend elastic constants. By adjusting the ratio of bend elastic constant to twist elastic constant to unity, the relaxation time from the homeotropic state to the planar state is greatly reduced. The oily streaks of the planar state are removed and light scattering is lessened.