Electro-optical Properties of Twisted Nematic Liquid Crystal Doped with SiO2 and Fe3O4 Nanoparticles
Date Issued
2006
Date
2006
Author(s)
Wang, Chien-Sheng
DOI
en-US
Abstract
The main purpose of this thesis is to investigate the optical properties of SiO2-doped or Fe3O4-doped 90o twisted nematic liquid crystal (TN-LC) cells. The doped cells comprise both a nematic host and a minute amount of SiO2 or Fe3O4 nanoparticles. We measured their transmittance, response time, capacitance and ion effect in the presence of ac and dc voltage. Experimental results indicate that doping some impurities in LC cell can reduce the Vth for 1 kHz, 500 Hz, and 100 Hz voltage. It is experimentally proved that SiO2 or Fe3O4 nanoparticles modify the dielectric anisotropy and the viscosity of the doped liquid crystal cells, hence significantly modifying the threshold voltage and the switching behavior of a liquid crystal device. Besides the transmittance and the threshold voltage, the ion effect of the doped TN-LC cells is also reduced. Since the ion effect is decreased, the threshold voltage is of course reduced. The doped SiO2 or Fe3O4 nanoparticles also increase the viscosity of the doped TN-LC cells. Therefore, the rise time and the fall time increase when the doped concentration increases due to the increase in the viscosity of the doped TN-LC cells.
Subjects
摻雜
二氧化矽
四氧化三鐵
扭轉向列型液晶
doped
SiO2
Fe3O4
twisted nematic liquid crystal
Type
thesis
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