Role of ionic contribution in dielectric behaviour of a nematic liquid crystal with variable cell thickness

Abstract

In this research article, we have investigated the dielectric properties of a nematic liquid crystal (NLC), namely 4 cyano-4′- pentylbiphenyl (which is commonly known as 5CB), in sample cells of variable thickness. The dielectric behaviour has been studied through a LCR meter in the frequency ranging from 20 Hz to 1 MHz. It was observed that the real part of complex dielectric permittivity (ε') decreases and the peak value of the energy dissipated per unit cycle (ε′′) increases on increasing the cell thickness. It has also been noticed that the relaxation frequency of LC material under investigation shifts towards the lower side with the increment in the sample cell thickness. The observed dielectric behaviour has been attributed to the contribution of the ionic species available in the NLC used. The mobilized ions have a significant contribution in influencing the dielectric studies of 5CB in thin cells. Further, all the above mentioned physical attributes of 5CB will play an important role in fabricating a device which is not only cost effective but also has higher transmittance and negligible power consumption.