Unveiling the role of electrode polarization in modulating dielectric and electro-optical properties of SnSe dispersed nematic liquid crystal

Abstract

This study examines the influence of SnSe nanospheres (NSs) on the dielectric and electro-optical properties of liquid crystal (LC) blends. A notable Debye relaxation phenomenon has been observed within a few Hz to near kHz frequency regime. This phenomenon is ascribed to the accumulation of mobile charge carriers near the cell electrodes (electrode polarization). We engage in a comprehensive analysis of the implications of this phenomenon on the electro-optical response, taking into account crucial factors including threshold voltage, response time, and dielectric permittivity. Our findings unveil a significant alteration in the electro-optical behavior resulting from the introduction of NSs, extending well beyond the instance of electrode polarization, although with a detrimental impact on performance within the low-frequency range. Furthermore, the inclusion of SnSe NSs within LC molecules has the potential to capture charged ionic impurities, leading to suppression of the screening effect. This, in turn, gives rise to an intensified electric field and heightened van der Waals dispersion interaction between LC molecules and alignment layers. Through COMSOL Multiphysics software simulation and experimental validation, we establish a consistency between the predicted phenomena and observed experimental results. Notably, LC cells containing 0.5 wt% SnSe NSs demonstrated superior electro-optical properties. These enhancements comprised an elevated dielectric anisotropy (increased from 14.27 to 19.50), a lowered low threshold voltage (decreased from 1.08 to 0.73 V), and a quicker response time (reduced from 11.5 to 4.01 ms), above the onset frequency of electrode polarization.