dc.description.abstract | In recent decades, liquid crystal (LC) is one of the famous materials for the applications of many types of electronics, such as LC displays, LC smart windows, and others. Therefore, LC technology is an indispensable technology in human’s daily life. Nowadays, non-renewable energy comes from sources, such as oil and coal, that will eventually run out, so the development of technologies moves towards energy conservation and sustainable development. In LC fields, it is definitely true that the development of bistable and multi-stable devices, as well as the transflective LC display devices, is an important key direction now.
The thesis includes two parts, the first part is the study of polarization-selective light scattering by polymer-network liquid crystals (PNLC). The famous LC polymer, RM257, cured by UV light, is adopted to form the PNLC structures. The mismatch of the refractive indexes of LCs and polymers in a PNLC cell applied with suitable electric fields results in light scattering. Regarding the scattering of the incident light, one component of the incident light will be scattered by the PNLC cell, while the other component will smoothly penetrate the PNLC cell. Such a phenomenon is called polarization-selective light scattering. Moreover, using various UV light having different polarization directions to polymerize the polymers will obtain the PNLC cells having different threshold voltages, voltage hysteresis widths, and the uniformity and completion of polymerization. The second part of this thesis is the study of electro-optic characteristics of the azo dye (MR)- and polymer-doped nematic LCs. Experimentally, the doped MR molecules illuminated by green light will be adsorbed onto the substrate facing the incident light. Here, Williams domains can be initiated by applying a suitable voltage, and the doped MR molecules are simultaneously illuminated with green light to generate the specific structures of MR adsorption. Thereafter, the observation of the generated structures of LCs, resulting from the adsorbed MR, under a polarized optical microscope is similar to that of Williams domain. It indicates that the dynamic structures cannot be stabilized by the adsorbed MR, but the bright and dark stripes, resulting from the orientation of LCs based on the guest-host effect, can be recorded onto the LC cell. | en_US |