Novel alignment materials for use in liquid crystal displays.

摘要

Obtaining stable and uniform alignment of liquid crystals on a macroscopic scale is essential for the fabrication and operation of high-quality liquid crystal displays. The alignment layer imposes the proper orientation of the liquid crystals in the initial state. Currently, the preferred modification technique is rather primitive: the conductive substrate is coated with a polyimide layer that after thermal curing is mechanically rubbed. This technique generates dust particles that interfere with display operation and often results in irreversible electrostatic damage to the electronic components of the display. Also, the details of the alignment mechanisms associated with unidirectional rubbing are not well understood. Thus, there is a demand for non-contact alignment techniques that are easily reproduced and quanitifed.; The work presented in this dissertation focuses on the development of novel alignment layers for use in liquid crystal displays, alignment layers that eliminate the need for a mechanical rubbing step in the fabrication process. The goal of this research was to find a material that could induce spontaneous, uniform alignment by means of easily quantified mechanisms. Several types of alignment layers, including surfactant monolayers, carbon nanotube and metal-oxide nanorod films and polymer films were examined for possible use in liquid crystal displays. Perfluoropolyether films embossed by soft lithography methods with a pattern of parallel grooves induced uniform homeotropic alignment of nematic liquid crystals on a macroscopic scale, offering the most promising alternative to traditional polyimide alignment layers.