Formation of Antireflection Thin-Film Glasses Using Organopolysiloxane by Low-Temperature Process and Surface Modification

Abstract

Porous SiO_x thin films were prepared using a commercial liquid glass (LG) based on organopolysiloxane to improve the conversion efficiency of photovoltaic modules as antireflection films. Optimization of the preparation of porous SiO_x films such as the ink manufacturing process was carried out by adding isopropyl alcohol (IPA) to the LG, spin coating, and annealing. Adding an ultrapure water (UW) to the ink with subsequent annealing at 300℃ resulted in the formation of a porous SiO_x thin film with 4.6% reflectance at 600 nm wavelength, whose refractive index was estimated to be 1.33, which is lower than that of conventional antireflection coating films such as MgF₂. In addition, the antireflection effect of the antireflection film fabricated at room temperature without dilution with UW was improved by surface modification by performing excimer vacuum ultraviolet (VUV) irradiation at room temperature and atmospheric pressure. This treatment modified the reflectance of the film from 8.1% to 7.7% at 600 nm and the refractive index from 1.44 to 1.42, which is lower than that of normal glass.