| Summary: | 碩士 === 國立交通大學 === 光電工程學系 === 99 === Liquid crystal alignment layer plays an important role to the image quality and liquid crystal display’s reliability. The rubbing method on polyimide (PI) film has dominated the alignment films’ preparation. However, high baking temperature over 2000C that is required for the film preparation is a major limitation for its applications into flexible substrates. New alignment materials for low temperature process are the emerging needs of energy conservation. Various alignment materials containing distinct chemical functional groups, such as polyvinyl alcohol (PVA), polystyrene (PS), polystyrene sulfonic acid (PSSA), poly- (4-vinylphenol) (PVP) and polyvinylpyrrolidone (PVPD) are studied. The process temperature for these materials can be as low as 1100C.
Optical properties and surface orientation of a variety of polymer surfaces were investigated as new liquid crystal alignment materials in liquid crystal displays (LCDs). The performances of these new liquid crystal alignment materials induced by mechanical rubbing treatment were examined by their electro-optical properties, order parameter and polar anchoring energy. The bonding orientation of these new alignment materials were characterized through surface sensitive technique, near edge X-ray absorption fine structure (NEXAFS). The NEXAFS measurements clearly indicated the in plane and out of plane asymmetries at the surface of rubbed polymers. These new liquid crystal alignment layers are suitable for flexible substrates of low temperature process in flat panel liquid crystal displays.
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