Dielectric and Electro-Optic Effects in a Nematic Liquid Crystal Doped with h-BN Flakes

Crystals

Rajratan Basu¹  GeorgeW. Sterling¹  LukasJ. Atwood¹ 

[1] Soft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, MD 21402, USA;

关键词: nematic liquid crystals;    h-bn flakes;    dielectric anisotropy;    rotational viscosity;    anchoring energy;    electro-optic effect;   

DOI  :  10.3390/cryst10020123

来源: DOAJ

【 摘 要 】

A small quantity of hexagonal boron nitride (h-BN) flakes is doped into a nematic liquid crystal (LC). The epitaxial interaction between the LC molecules and the h-BN flakes rising from the π−π electron stacking between the LC’s benzene rings and the h-BN’s honeycomb structure stabilizes pseudo-nematic domains surrounding the h-BN flakes. Electric field-dependent dielectric studies reveal that the LC-jacketed h-BN flakes follow the nematic director reorientation upon increasing the applied electric field. These anisotropic pseudo-nematic domains exist in the isotropic phase of the LC+h-BN system as well, and interact with the external electric field, giving rise to a nonzero dielectric anisotropy in the isotropic phase. Further investigations reveal that the presence of the h-BN flakes at a low concentration in the nematic LC enhances the elastic constants, reduces the rotation viscosity, and lowers the pre-tilt angle of the LC. However, the Fréedericksz threshold voltage stays mostly unaffected in the presence of the h-BN flakes. Additional studies show that the presence of the h-BN flakes enhances the effective polar anchoring strength in the cell. The enhanced polar anchoring strength and the reduced rotational viscosity result in faster electro-optic switching in the h-BN-doped LC cell.

【 授权许可】

Unknown