NOVELTY - Method of making a low-index silica based coating, comprises: forming a silica precursor comprising a radiation curable composition having a radiation curable monomer and a photoinitiator, and a silica sol having a silane and/or a colloidal silica; depositing the silica precursor on a glass (1) substrate to form a coating layer; curing the coating layer using at least exposure to electromagnetic radiation; and firing the coating layer in an oven at 550-700 degrees C for 1-10 minutes, to form the low-index silica based coating.    USE - The method is useful for making the low-index silica based coating, which is useful as an antireflective coating (claimed) or film on a front glass substrate of the photovoltaic device (solar cell), storefront windows, display cases, picture frames, greenhouse glass/windows, solariums and fireplace doors.    ADVANTAGE - The method provides low-index silica based coating with improved mechanical properties, where the coating reduces reflection of the incident light or other substrates.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a photovoltaic device comprising a photoelectric transfer film and the low-index coating, where the low-index coating is provided on a light incident side of a front glass substrate of the photovoltaic device; and    (2) a method of making a photovoltaic device including a low-index silica based coating used in an antireflective coating (3), comprising forming the silica precursor, depositing the silica precursor on a glass substrate to form the coating layer, curing the coating layer using at least exposure to electromagnetic radiation, after the curing, firing the coating layer using elevated temperature(s) of 550-700 degrees C to form the low-index silica based coating, and using the glass substrate with the low-index silica based coating as a front glass substrate of the photovoltaic device, where the low-index silica based coating is provided on a light incident side of the glass substrate.    DESCRIPTION OF DRAWING(S) - The figure shows a cross sectional view of photovoltaic device.    Glass (1)    Antireflective coating. (3)