| In this thesis, photo-aligned ferroelectric liquid crystal displays based on azo-dye layer are investigated. A remarkable property of such azo-dye is pure reorientation of the molecular absorption oscillator perpendicular to the UV light polarization, without any photochemical transformations. This property makes it suitable to provide a high photo-alignment quality of FLC using the azo-dye layer.; The mechanism of azo-dye photo-alignment process is explained with a specific potential, which characterizes the interactions of the dye molecules and the activated UV light. Both the approximations of negligible and strong molecular interaction are considered during the process of reorientation under the action of a polarized light. The reorientation ordering of azo-dye increases with the exposure time and comes to a saturation level; such saturation value increases with the intensity of the activated light. A non-zero order parameter relaxation is observed when the activating light swtched off, which is caused by dye molecular interaction.; The properties of photo-aligned azo-dyes would be presented. The azo-dyes shows remarkable properties, including high order parameter, good thermostability, high anchoring energy, pretilt angle generation and high voltage holding ratio.; A photo-aligned FLC with a bistable switching are discussed in static and multiplex operations. Optimization of photo-aligned FLC display is investigated, including the effects of UV exposure energy, photo-aligned/planar layer quality and boundary conditions. The Photo-aligned FLC displays with large cell gap of 5∼7 mum is developed instead of the traditional 1.5mum cells. It shows the excellent electrooptical performance, including high contrast ratio, good bistable switching, fast response time and memorized gray scale generation. A prototype of passively addressed 64 x 64 FLC display based on the photo-alignment technique has been developed with perfect bistable switching in the multiplex driving regime. |
