Electrical Properties of TiO2-Doped Nematic Liquid Crystals under UV Exposure
|關鍵字:||二氧化鈦;液晶;奈米粒子;紫外光;anatase nanoparticles;liquid crystals;nano particles;ultraviolet|
The effect of ultraviolet (UV) exposure on electrical and ionic characteristics of nematic liquid crystals (NLCs) doped with anatase nanoparticles (TiO2 NPs) was investigated by means of dielectric spectroscopy as well as the voltage holding ratio (VHR) measurement. In this study, experimental samples were prepared by mixing NLCs and TiO2 NPs at appropriate concentrations. For cell samples with UV exposure, the exposure time and the intensity of UV light were set as variables. The irradiation of UV light to a LC cell leads to the increase in ionic concentration and the reduction in VHR, presumably due to the dissociation of the LC material and photoinduced desorption and injection of impurity ions. Increasing either the intensity of light or exposure time results in the promotion of the ionic effect in the cell. Specifically, experimental results demonstrate that the influence of UV light on ion density and VHR of a NLC cell can be suppressed by doping a proper amount of TiO2 NPs because of the ion-trapping ability of doped TiO2 associated with the photochemical reaction of TiO2 with irradiated UV light. As a result, our proposed TiO2/NLC system is a potential approach to enhancing the electro-optical performance and extend the lifetime of a LC display under sunlight.