Patent ID: 8852989

Claim:
A method for forming a back contact layer for a thin film photovoltaic device comprising: providing a substrate, wherein the substrate comprises glass; applying a sol-gel or nanoparticle material directly on a glass surface of the substrate; curing the sol-gel or nanoparticle material; and forming a back contact layer on the cured sol-gel or nanoparticle material such that the cured sol-gel or nanoparticle material is between the substrate and the back contact layer, wherein the back contact layer forms a primary electrical current conductor layer disposed between the substrate and an absorber layer in the thin film photovoltaic device; further comprising removing a portion of the sol gel or nanoparticle material after the curing but before the forming of the back contact layer, wherein the sol gel or nanoparticle material contains particles, and wherein the particles remain on the surface of the substrate after the removing step, wherein the back contact layer comprises molybdenum, copper, or a combination thereof; and wherein the size of the particles is greater than the thickness of the sol-gel or nanoparticle material after the curing step and the particles comprise at least one of silicon oxide and titanium oxide; wherein particles have a size greater than 1 nm and less than 100 nm.