Green synthesized TiO2 nanoparticles dispersed cholesteric liquid crystal systems for enhanced optical and dielectric properties

Abstract

Green synthesis of nanoparticles (NPs) is a simple, low-toxic, and cost-effective way to make NPs. The decreased optical band gap attributable to oxygen vacancies in green synthesized TiO2 NPs is responsible for the unique features for photocatalytic applications as well as increased optical properties. To explore optical and dielectric characteristics, green synthesized TiO2 NPs were dispersed in the cholesteric liquid crystal (CLC). By adding 27 wt% R-811 chiral dopant to E7 pure nematic liquid crystal, CLC was formed. The reflection color in the red region was observed in the polarizing optical microscope (POM) at ambient temperature, and the alignment was improved as the dispersion concentration was increased. Pure and TiO2 NPs dispersed CLC samples were subjected to UV–Visible absorbance, FE-SEM, EDAX, XRD, TEM, photoluminescence (PL), and FTIR analysis. As compared to pure CLC, the PL intensity increased for the NPs dispersed CLC samples without any substantial change in the emission peak position and the UV absorbance decreased as the NPs concentration increased. Furthermore, when compared to pure CLC, reduction in the optical band gap for TiO2 NPs dispersed CLC was observed. FTIR analysis revealed the impact of nanoparticle dispersion on CLC molecular dynamics. Dielectric spectroscopy results show a decrease in the relaxation frequency for TiO2 dispersed CLC system which is a positive outcome of this investigation. The findings reveal that TiO2 NPs when dispersed in CLC had significantly improved optical and dielectric properties. As a result, the optimal TiO2 NPs concentration in CLCs may have a variety of credential applications.