Vertical liquid crystal orientation on amorphous tantalum pentoxide surfaces depending on anisotropic dipole-dipole interaction via ion beam irradiation

We achieved vertically aligned (VA) liquid crystals (LCs) on amorphous tantalum pentoxide (Ta₂O₅) alignment films deposited by radio frequency (rf) magnetron sputtering using ion beam (IB) irradiation. By analyzing measurements by X-ray photoelectron spectroscopy (XPS), we confirmed the bond breaking, as detected from the O 1s spectra, which caused an isotropic dipole-dipole interaction between the LC molecules and the Ta2O5 alignment film to uniformly align the vertical LC molecular orientation as a function of IB energy density. Moreover, by examining the electro-optical (EO) characteristics of the Ta₂O₅ surfaces compared with those of the polyimide (PI) alignment layer, we confirmed that Ta₂O₅ has a low threshold voltage and a low power consumption when used as an LC alignment layer.