| Summary: | 碩士 === 國立中山大學 === 光電工程學系研究所 === 101 === Blue phase(BP) is a mesophase existed at temperature range between cholesteric phase and isotropic phase. BP can be classified into BP I and BP II according to their crystal structures. BP I is body-center cubic(BCC) and BP II is simple cubic(SC). Since BP is a self-assembled 3D photonic crystal, it has periodic structure and Bragg reflection properties. Due to the different structures of BP I and BP II, it provide with various photonic bandgap and wavelength of Bragg reflection. In this thesis, our purpose is to control the reflection wavelength of azo-dye doped BP using photo-addressing to achieve color reflective display.
First, we doped azo-dye to the blue phase liquid crystal. The trans-cis photoisomeration of azo-dye could be induced by irradiated 404nm laser. It can change the phase transition temperature of BPLC. The cholesteric phase would be changed to BP and then to isotropic phase at the same temperature under suitable excitation. Then irradiation of 532nm laser can induce back photoisomeration which can induce isotropic phase back into BP then to cholesteric phase. So we could obtain the desired reflection colors through the photoisomeration cycle. There are three colors(red, green, blue) in our BP as bright state. The isotropic phase with black background can be used as dark state. This study achieves a Light-driven, multistable and full-color reflective blue phase liquid crystal display.
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