Nanopatterning of Polymer/Gallium Oxide Thin Films by UV-Curing Nanoimprint Lithography for Liquid Crystal Alignment

A liquid crystal (LC) alignment layer was created using the nanoimprint lithography method and ultraviolet (UV) curing. A hybrid film of a solution of gallium oxide (GaO) and a UV-curing polymer was coated on a substrate and cured by UV irradiation. After that, an LC cell was manufactured by assembling two films by an antiparallel method. The LC orientation characteristics and the surface were analyzed by varying the curing time. The molecular composition of the coated film surface was confirmed via X-ray photoelectron spectroscopy, and nanopattern formation was observed through atomic force microscopy. The LC alignment characteristics were analyzed by polarized optical microscopy and pretilt angle measurements, and thermal stability tests were performed. It was confirmed that the refractive index anisotropy and van der Waals forces based on the nanopattern formation enabled a homogeneous and uniform alignment of the LC molecules; further, it was found that the GaO hybrid film was suitable for use as an LC alignment layer.