Flexoelectro-optic properties of liquid crystal dimer CB7CB in the uniform standing helix structure under planar anchoring boundary conditions

Abstract

Based on the theory of liquid crystal elasticity, flexoelectric effect and dielectric effect in uniform standing helix (USH) structure with the liquid crystal dimer CB7CB which has larger flexoelectric effect and smaller dielectric anisotropy under strong and weak planar anchoring boundary conditions are studied. The influence of flexoelectric effect on the distribution of director and the rotation of USH optical axis can be quantitatively analysed through numerical simulation. We find that the dielectric effect has little effect on the director and almost no effect on the rotation angle of the optical axis. The rotation angle of the optical axis under strong anchoring is consistent with the formulas in the literature. Under weak anchoring, the pitch of the cholesteric liquid crystal becomes shorter, and the difference between the flexoelectric coefficients e 1–e 3 and the single flexoelectric coefficient e 3 affect the rotation angle of the optical axis. Remarkably, our method provides a more accurate theory basis for the rotation of the optic axis in USH cholesteric liquid crystals.