| dc.description.abstract | Liquid crystal (LC) optoelectronic technologies, including the panel display technology, the applications of smart windows, and others, have made huge progress over the past decades. The convenience brought by such technologies has become an indispensable part of human daily life. Moreover, with the spread of environmental awareness over the world, the development of multi-stable LC devices having the performance of low power consumption attract great attention among the industrial and academic communities.
The contents of the thesis are divided into two main topics, they are smart windows and dynamic structures of LCs. The first topic is the study of optically and electrically controllable electro-optical characteristics of LC devices based on dichroic dyes-doped cholesteric LCs. The LC device, functioning as a light shutter, has electrical switching performance which can adjust its gray scales from the initial transparent state to light scattering state by the application of an electric field over the threshold voltage (VW). In addition, when a high electric field is applied, the LCs generate dynamic structures, called Williams Domains, before the appearance of dynamic scattering phenomenon. The rotating diffraction pattern can be observed on the screen with the increase of the applied electric voltage and can also be observed by utilizing the photo-isomerization of the doped azobenzenes between trans- and cis-isomers. Such dynamic processes will generate the Williams Domains of cholesteric textures. The second topic is the studies of the electro-optical characteristics of electrohydrodynamic instability and the optically controllable chirality of dichroic dyes-doped cholesteric LCs. The same materials adopted in the first topic are injected into different LC cells treated with different alignment layers, and then the differences of dynamic structures and optical properties of the LC cells applied with a fixed external voltage observed under a polarized optical microscope by adjusting the polarizer and the analyzer are elucidated. Finally, we discuss the properties of the cholesteric textures having Williams Domains treated with photo-isomerization of the doped azobenzenes between trans- and cis-isomers.
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