Enhancement of frequency modulation response time for polymer-dispersed liquid crystal

Through the ferroelectric nanoparticles of BaTiO₃ (BTO) doping, the response time for the frequency modulation of the polymer-dispersed liquid crystal (PDLC) was improved. The BTO-doped PDLC cells were prepared by polymerisation induced phase separation (PIPS) process using UV light. The capacitance of the PDLC composites was measured with an impedance analyzer in the frequency range of 100 Hz–1 MHz at 1 V. The dynamic signal for the response time of the PDLC devices was monitored through a digital oscilloscope. The electro-optical properties of the PDLC were found to strongly depend on the doped BTO concentration. The BTO doping caused a large increase in the capacitance. The dielectric constants were drastically decreased in the samples with rather low BTO doping ratio at a high frequency. No outstanding difference in the rising time of the LC was observed in the BTO-doped PDLC device, but the falling time was significantly decreased from 0.334 to 0.094 s. The present results imply that the nanoparticle-doping technology could improve the electro-optical performance of the PDLC requiring fast response and frequency modulation, such as optical modulators and PDLC-hybrid electroluminescence device for flexible electronic devices.     

Fabrication and characterization of ordered microsized tubular TiO2 films by using various anodizing conditions

In this study, we investigated the oxidation process of titanium in two different electrolytic solutions in order to understand the effect of the electrolyte on the microsized tubular TiO₂ formation and their structure. In the first set of experiments, we used 0.5% HF electrolyte by applying 23?V for 50?min. The second set of experiments was performed using glycerol electrolyte with 0.27?M NH₄F and 1.5% H₂O under 40?V for 19?h. Both experiments were performed at room temperature. After the anodizing process, the samples were annealed at 550?°C in O₂ atmosphere. In both electrolytic conditions well-ordered microsized tubular TiO₂ were obtained. The morphologies, structures, and microsized tubular TiO₂ array films were characterized by FE-SEM, EDS, and XRD.