Pristine and quantum dots dispersed nematic liquid crystal: Impact of dispersion and applied voltage on dielectric and electro-optical properties

Abstract

In this work, we have dispersed Cd1-xZnxS/ZnS quantum dots (QDs) in nematic liquid crystal (LC) BBHA which shows negative dielectric anisotropy (Δε = −2.90) [1]. The impact of QDs dispersion, applied bias and concentration of QDs on the dielectric permittivity, dielectric loss, response time, transmittance and birefringence as a function of frequency and temperature for planar alignment has been studied. We have observed that dispersion of QDs in pure nematic LC influences these properties. Due to QDs dispersion the birefringence increases and this helps in the alignment and ordering of nematic molecules. Under applied bias the ionic contributions to the dielectric loss as observed in low frequency region are suppressed and the relaxation frequency is shifted towards higher frequency side. We have made an effort to explain the observed behaviour of pristine and dispersed systems on the basis of interactions between QDs and nematic molecules. © 2017