TECHNOLOGY FOCUS - POLYMERS - Preferred Method: In the method (I), post heat treatment: the AR coating provides a visible transmission gain of at least 2.5% relative to the glass substrate alone; and the AR coating has a basterisk value of greater than or equal to 0.9, preferably greater than or equal to 1. The curing step comprises exposing the substrate together with the sol spin coated on it to first and second elevated temperatures, where the second elevated temperature is higher than the first elevated temperature. The substrate together with the sol spin coated on it is exposed to 150 degrees C for 2 minutes, followed by 220 degrees C for 2.5 minutes. The step of preparing of the silica sol comprises: preparing a polymeric component, where the polymeric component comprises n-propanol, glycidoxypropyltrimethoxysilane, water, and hydrochloric acid; mixing the polymeric component; forming a coating solution by combining the polymeric solution with the colloidal silica in methyl ethyl ketone; and stirring the coating solution to form the silica sol. The method (I) further comprises building the glass substrate together with the AR coating into a photovoltaic device. In the method (II), the heat treatment comprises thermally tempering in a tempering furnace at, at least 580 degrees C. Preferred Components: The particle size is 20-100 nm. EXAMPLE - n-Propanol (64 wt.%), glycidoxypropyltrimethoxysilane (24 wt.%), water (7 wt.%) and hydrochloric acid (5 wt.%) were mixed for 24 hours to give a polymeric component of silica. The coating solution was prepared by using polymeric solution (21 wt.%), colloidal silica (7 wt.%) in methyl ethyl ketone and n-propanol (72 wt.%). The solution was stirred for 2 hours to give a silica sol. The silica coating was fabricated using a spin coater operating at 1200 rpm for 30 seconds. The coating was heated on a hot plate at 150 degrees C for 2 minutes, then in an oven at 220 degrees C for 2.5 minutes, and tempered in a furnace at 625 degrees C for 3.5 minutes, to give a coating with thickness of approximately 128.9 nm, and the transmission of 86.7%.