Role of SiO2 optically active mediators to tailor optical and electro-optical properties of ferroelectric liquid crystalline nanocomposites

Abstract

We have investigated the effects of silica nanoparticles doping on the optical parameters and physical properties of ferroelectric liquid crystal. Nanocomposites comprise with different concentration of silica nanoparticles are characterized with Fourier Transform Infrared Spectroscopy, Polarizing optical microscopy, and optical techniques. Chemical interactions, textural behaviour, transmittance, contrast behaviour, threshold, dynamic response, anchoring energy, conductivity and optical bandgap for nanocomposites are presented. A significant improvement in optical transmittance, contrast and birefringence has been achieved with silica nanoparticles doping. For instance, 75% increment in optical transmittance and about 77% in contrast ratio has been observed. Such an increase in the optical parameters could attribute to the coupling between the dopant/host, their higher transparency and optical anisotropies. Doping of silica nanoparticles strongly reduces the threshold voltage as well. Fastening of the switching response has also been noted. Such change in parameters may correspond to the higher electrical torque experienced by the ferroelectric liquid crystal molecules in the presence of silica nanoparticles on the application of the applied field. Anchoring energy, dc conductivity and optical energy band gap of pure and doped systems have been calculated and correlated with observed behaviour. The nanocomposites with such an enhanced optical parameter can be used for optical device applications.