Evolution of electro-chemical and electro-optical properties of nematic liquid crystal doped with graphene oxide

Abstract

Different concentrations of graphene oxide (GO) nanoparticles dispersed in the nematic liquid crystal (NLC) was investigated to monitor the impedance response and electro-optic parameters such as dielectric anisotropy threshold voltage, elastic constant, and response times. The impedance response of colloidal nematic dispersions was studied at the frequency range of 0.1 Hz–100 kHz. By fitting an appropriate equivalent electric circuit model to the experimental data, it can be concluded that although GO doping does not significantly affect the permittivity of the nematic host, it noticeably increases its charge capacitance. The threshold voltage and splay elastic constant are strictly dependent upon the GO concentration and the amount of these parameters rise by increasing the concentration of GO (up to saturation at ≈1%). Although the GO concentration reduces the switching-off time efficiently, the switching-on time is not mainly affected by increasing the GO. Non-collective relaxation was detected by dielectric spectroscopy in GO doped LCs which may be attributed to drastically slow down molecular relaxation associated to the rotation around the short axis of the LC's molecules.