Optical, Photoluminescence, and Birefringence Studies on ZnO-Dispersed p-n-Nonyloxy Benzoic Acid Liquid Crystals for Display Device Application

Abstract

This paper presents optical and photoluminescence (PL) properties of liquid crystalline (LC) compound-like p-n-nonyloxy (9OBA) benzoic acid, with the dispersion of zinc oxide (ZnO) nanoparticles (NPs) in different concentrations (0.5–2 wt.%). The optical absorbance reveals an absorption peak for pure 9OBA at 240 nm that is shifted to 238 nm upon dispersion of 1 wt.% ZnO NPs. PL studies show two significant peaks at 362 and 588 nm for pure 9OBA and 389 nm for dispersed ZnO NPs. The peak observed at 389 nm corresponds to the near-band-edge emission of free exactions, while the peak at 588 nm is indicative of deep-level emission, resulting from point defects such as vacancies and interstitials within the bandgap. Refractive indices, birefringence, and dispersive power are measured for the prepared samples. The properties related to refractive index, birefringence, and dispersive powers are enhanced through the dispersion of ZnO NPs in the 9OBA LC compound. The refractive indices measured are fitted with two- and three-coefficient Cauchy models. The outcome of the results suggests an enhancement in material properties that are beneficial for display technologies.