NOVELTY - Making (M1) photovoltaic device including antireflective coating (3), involves forming coating solution by mixing mono-metal oxide, bi-metal oxide, silane and/or siloxane with solvent, such that the coating solution can be used as barrier between the antireflective coating and glass substrate (1); forming the barrier layer (2); curing the barrier layer; providing antireflective film on the glass substrate over at least the barrier layer; and using the coated glass substrate including the cured barrier layer in photovoltaic device.    USE - For making photovoltaic device (claimed) such as solar cell, storefront windows, display cases, picture frames, other types of windows.    ADVANTAGE - The method can reduce reflection of light from the glass substrate, thus allowing more light within the solar spectrum to pass through the incident glass substrate and reach the photovoltaic semiconductor film so that the device can be more efficient; reduces sodium ion migration from the glass substrate; and reduces loss of transmission of radiation through the substrate after exposure to environmental factors including humidity and temperature.    DETAILED DESCRIPTION - Making (M1) photovoltaic device including antireflective coating (3), involves forming coating solution by mixing mono-metal oxide, bi-metal oxide, silane and/or siloxane with solvent, such that the coating solution can be used as barrier between the antireflective coating and glass substrate (1) that reduces sodium ion migration from the glass substrate; providing the coating solution on the glass substrate to form barrier layer (2); curing the barrier layer; providing antireflective film on the glass substrate over at least the barrier layer; and using the coated glass substrate including the cured barrier layer in photovoltaic device, where the barrier layer is located under the antireflective film provided on the glass substrate in the photovoltaic device, and the barrier layer and antireflective film are provided on light incident side of the glass substrate. INDEPENDENT CLAIMS are included for the following:    (1) making (M2) an environmentally durable coating for substrate, involving forming coating solution by mixing at least one mono-metal oxide, bi-metal oxide, silane and/or siloxane with at least one solvent, such that the coating solution is used in forming a barrier layer that reduces loss of transmission of radiation through the substrate after exposure to environmental factors including humidity and temperature; casting the coating solution to form barrier layer on the substrate; and curing the barrier layer using at least heat treatment;    (2) a photovoltaic device comprising photovoltaic film and at least a glass substrate located on light incident side of the photovoltaic film; barrier layer provided on the glass substrate; an anti-reflection coating provided on the glass substrate over at least the barrier layer; where the barrier layer comprises at least one mono-metal oxide, bi-metal oxide, silane and/or siloxane; and    (3) coated article comprising glass substrate; barrier layer provided on the glass substrate; anti-reflection coating provided on the barrier layer; where the barrier layer is formed using a solution that comprises at least one mono-metal oxide, a bi-metal oxide, a silane and/or a siloxane.    DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of a photovoltaic device.    Glass substrate; (1)    Barrier layer; (2)    Antireflective coating; (3)    Transparent conductive electrode; (4)    Photovoltaic semiconductor (active film) of solar cell; (5)    Reflection enhancement oxide and/or ethylene vinyl acetate (EVA) film; (6)    Back metallic or conductive contact. (7)