Physicochemically Constructed Unidirectional Aluminum Bismuth Gallium Zinc Oxide Film for Enhanced Nematic Liquid Crystal System Using a Brush-Coating Method

We propose a convenient brush coating method for liquid crystal (LC) alignment. This method enables film deposition and an alignment layer treatment process simultaneously. Aluminum bismuth gallium zinc oxide (AlBiGaZnO) is used as the alignment layer. After the curing process, a unidirectional AlBiGaZnO film is formed; its surface morphology and chemical composition were verified using scanning electron microscopy and X-ray photoelectron spectroscopy. This oriented structure of the surface was produced by shear-stress which originated from brush movement. That structure induced a surface anisotropic characteristic and resulted in a uniform LC alignment. The uniform and homogeneous LC alignment state on the film was confirmed using polarized optical microscopy and pre-tilt angle analysis. The brush coated AlBiGaZnO film exhibited excellent thermal budget for advanced LC system. The film exhibited enhanced electro-optical performance with a low operating voltage. These results demonstrate the potential of LC alignment technology via the brush coating method.