Electro-optical properties of liquid crystal displays based on the transparent zinc oxide films treated by using a rubbing method

Liquid crystal (LC) alignment on inorganic films has been found to be affected by surface modification via ion-beam irradiation. In this study, ZnO films treated by rubbing with a velvet cloth were shown to be capable of aligning LC molecules in the direction of the rubbing. Uniform and homogeneous LC alignment was achieved on the rubbed ZnO films. By analysing the optical axes before and after the rubbing treatment, we confirmed an increase in the anisotropy of the ZnO films; this optical anisotropy contributed to the uniform orientation of LC molecules. Further, the electro-optical characteristics of the twisted nematic cells based on ZnO films were superior to those based on conventional polyimide layers. Our results indicate that the rubbing approach could be applied in the fabrication of high-performance LC displays.