The electrooptical characteristics of carbon nanotube-doped liquid crystal (LC) devices were investigated. Two complementary operation modes of the liquid crystal cells were fabricated. The measured results reveal that anisotropic carbon nanosolids modify the dielectric anisotropy and the viscosity of the liquid crystal carbon nanotube mixture, hence significantly modifying the threshold voltage and the switching behavior of a liquid crystal device. Doping a small amount of carbon nanotubes into the liquid crystal mixture is effective in improving the electrooptical characteristics of an LC device when the employed LC mixture is viscous.

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We investigated the electrooptical properties of a carbon nanotube (CNT)-doped twisted nematic (TN) liquid crystal (LC) cell. Experimental results reveal that the doped CNTs influence the elastic constant of LC–CNT dispersion. Using a small amount of CNT dopant, the field-on response time of the LC cell is nearly invariant; the threshold voltage of the cell increases due to the increase in the elastic constant of LC–CNT dispersion. At a higher CNT concentration, the marked increase in the dielectric anisotropy of LC–CNT dispersion markedly decreases the field-on response time and threshold voltage of the LC cell. The field-off response time of this cell decreases with increasing CNT concentration due to the increase in elastic constant and the slight increase in viscosity of LC–CNT dispersion. The field-on and field-off response times of the LC cell are reduced simultaneously when the LC host is doped with a moderate amount of CNT dopant.

The effects of ultraviolet (UV) irradiation on the work function of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) have been investigated in this study. Spectroscopic methods [x-ray photoelectron spectroscopy and Raman spectroscopy (532nm excitation)] and electrical conductivity measurements were used to characterize the electrical conducting polymer PEDOT:PSS prepared by UV irradiation. The authors found that UV irradiation could lead to an increase in the work function and the enhancement of electrical conductivity of PEDOT:PSS, resulting from a decrease in the number of the charge-trapping-related defects and the formation of linear or expanded-coil conformation.

The dynamic pattern formation and the beam-steering characteristics of cholesteric gratings were studied. Films with a planar cholesteric texture and various thickness to pitch length ratios (d/p) were fabricated. An optical microscope was used to observe the stripe patterns of the cholesteric gratings formed by applying a voltage to the planar films. The micrographs showed that the cholesteric gratings were formed in two different ways, depending on the sample's d/p ratio. For samples with 1/2≤d/p≤1.0, the grating stripes simultaneously appeared across the whole sample, and the contrast of the stripes increased with time during formation. For films with d/p≥1.5, the stripes were initiated near the edges, and near the defects on the substrates, and then slowly extended to the whole sample along the rubbing direction. The diffraction measurements showed that the diffracted beams could be steered either electrically or optically only for the latter type of film. These results can be well explained theoretically.

We design a dual-view liquid crystal display (DVLCD) which display two different images in the left and right viewing directions simultaneously. The main-pixel of the DVLCD comprises the right sub-pixels (RSPs) and the left sub-pixels (LSPs). The LCs in the RSPs and the LSPs have the opposite rotation directions, which are controlled by the inclined electric fields provided by the patterned electrodes. Addressing the RSPs and LSPs with the voltages having different polarities effectively decreases the maximum operation voltage of the DVLCD. The proposed DVLCD is free of the complicate multiple-step rubbing and shadow mask treatments, and hence has the advantages of low cost and easy fabrication.

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This work investigates the switching characteristics of the polymer-stabilized vertical alignment (VA) liquid crystal (LC) cell. The experimental results reveal that the fall time of the cell declines as the monomer concentration increases because the vertically-aligned polymer networks accelerate the relaxation of the LC molecules. Furthermore, the formed polymer networks impede the growth and annihilation of LC defects, suppressing the optical bounce in the time dependent transmittance curve of the cell when the voltage is applied to the cell, substantially reducing the rise time of the cell. A step-voltage driving scheme is demonstrated to eliminate completely the optical bounce and hence improve further the rise time of the VA LC cell. The rise times of the pristine and the polymer-stabilized VA LC cells under the step-voltage driving scheme are less than 50% of those under the conventional driving scheme.