The scientific duo of TiO2 nanoparticles and nematic liquid crystal E204: Increased absorbance, photoluminescence quenching and improving response time for electro-optical devices

The present investigation on the dielectric and electro-optical properties of nematic liquid crystal (NLC) E204 and TiO2 nanocomposites has been carried out with a wide range of frequencies. The low-frequency spectra of these composites with a concentration of 0.1 wt/wt%, 0.5 wt/wt%, and 1.0 wt/wt% are recorded in the frequency range of 50-1000 Hz, and the content of impurity ions in these samples has been analyzed. The ion trapping by adsorbing sites of TiO2 and that effect on DC conductivity and diffusion constant have also been investigated. TiO2-doped LC cell results in a two-fold faster response time of the pure LC cell, as a consequence of a remarkable reduction in the rotational viscosity of the LCs. The change in the intensity of the photoluminescence (PL) spectra of NLC composites as a function of the concentration of TiO2 nanoparticles (NPs) has also been investigated. PL spectra reveal that the PL-quenching increases in nano-nematic composites with increasing the concentration of TiO2 NPs following to the Stern-Volmer quenching equation. The pure NLC exhibits a strong absorption band nearly at 314 nm, attributing to pi-pi* transitions in the phenyl rings which has been slightly blue-shifted after the addition of TiO2 NPs. This blue shift was to be attributed to the n ->pi* electronic transitions in the systems. The doping of TiO2 NPs has a promising application to the field of LC devices and displays. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The research investigated the dielectric and electro-optical properties of nematic liquid crystal (NLC) E204 and TiO2 nanocomposites over a wide range of frequencies. It was found that doping TiO2 can significantly improve the response time and photoluminescence properties of the liquid crystal.