We propose a light shutter device using dichroic-dye-doped liquid crystals (LCs) whose Bragg reflection wavelength is set to be infrared by controlling the pitch of cholesteric liquid crystals (ChLCs). A dye-doped long-pitch ChLC cell is switchable between the dark planar state and the transparent homeotropic state. It has the advantages of high transmittance, low operation voltage, and an easy fabrication process relative to previous LC light shutter devices. The proposed light shutter device is expected to achieve high visibility for transparent organic light-emitting diode displays and emerging smart windows, which can be used in airplanes, cars, and other similar applications.

We propose an initially transparent light shutter using polymer-networked liquid crystals with crossed patterned electrodes. The proposed light shutter is switchable between the transparent and opaque states, and it exhibits a fast response time and a low operating voltage. In the transparent state, the light shutter has high transmittance; in the opaque state, it can block the background image and provides black color. We expect that the proposed light shutter can be applied to see-through displays and smart windows.

We propose a double-layered light shutter device using two cholesteric liquid crystal (ChLC) cells. The proposed light shutter consists of a light-scattering layer using long-pitch cholesteric LCs and a light-absorption layer using dye-doped ChLCs. The light shutter has four switchable states: light scattering, light absorption, absorption and scattering, and transparent. The light shutter in the absorption and scattering state can block the background image and provide a black color. By switching of the proposed light shutter positioned at the rear side of a transparent display, we can operate a transparent display in various modes, not just showing the images produced by a transparent display along with the background.

We reported electrical circuit modeling to analyze the optical performance degradation in an ion-doped liquid-crystal (LC) cell, which exhibited advantages, such as excellent optical performance and simple switching process, but suffered from long-term reliability issues. When an electric field was applied to the cell for an extended period of time, the optical performance became nonuniform, and the haze in the opaque state decreased. By measuring the impedance and fitting the measured data by using an equivalent circuit model, we confirmed the changes of the parameters in the electrochemical impedance spectroscopy and electrophysical properties of the ion-doped LC cell with time. According to the measurement of the optical and physical characteristics, the optical performance degradation was caused mainly by the ionic materials.

Although the fringe-field-switching (FFS) mode based on a two-domain (2D) electrode structure has been widely used for wide viewing angle in a liquid crystal display (LCD), it still suffers from color shift and asymmetric luminance distribution at off-axis. We propose a four-domain (4D) electrode structure for wide viewing angle characteristics in an FFS LCD. We demonstrate that the use of the 4D electrode structure instead of the 2D-chevron structure can reduce the off-axis color difference from 0.038 to 0.010 at a low gray level and from 0.019 to 0.002 at a mid-gray level. Moreover, the off-axis gamma distortion is reduced from 0.159 to 0.007.