Dielectric relaxation dynamics in liquid crystal – dye composites

Abstract

Dielectric relaxation spectroscopic studies were undertaken to investigate the role of the resistivity of a host liquid crystal in the relaxation dynamics of dyed systems. Two different types of liquid crystal mixture were used, namely, one that was characterized by high ion contamination and low resistivity and the other which was of high resistivity and virtual ion-free; both types were doped using an azo or anthraquinone dye. Dielectric spectra of both the pristine liquid crystals and their composites at different external fields were measured in homogenously-aligned cells. The use of both dyes on an ion-enriched liquid crystal not only enhanced ion concentration but also slowed down the relaxation process. In contrast, the relaxation process for composites with a high-resistivity liquid crystal host was faster than that of the pristine liquid crystal.