Low-Cost Enamel Coatings on Stainless Steel Foil for Thin Film Photovoltaics

"High-efficiency photovoltaic cells fabricated from copper-indium-gallium-diselenide (CIGS) technology are important for the generation of low-cost electrical energy. Greater cost benefits could be realized if photovoltaic films could be fabricated onflexible metal foils using a roll-to-roll manufacturing process. A thin insulative layer is required to separate the CIGS film from the metal foil. This insulative coating should exhibit excellent adhesion to the metal substrate and be compatible withthe CIGS and metal substrate layer, both thermophysically and chemically. An inexpensive method of applying this coating over large areas without surface defects is also needed. Sommer Materials Research (SMR) proposes to apply thin pinhole-free enamelcoatings to stainless steel foil for CIGS solar cells. Air spraying and electrophoretic deposition will be used to obtain thin uniform coatings. The enamel coatings will exhibit excellent flexibility and be compatible with CIGS processing conditions.The electrically insulative coating will also show high bond strength, a high use temperature, and a compatible thermal expansion coefficient to the CIGS layer and metal foil. Thin enamel coatings on metals have a proven track record commercially and maybe the key for producing inexpensive high-efficiency solar cells for military, aerospace, and commercial use. The enameled foils will exhibit high flexibility and compatibility, allowing roll-