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

An inexpensive method to insulate the CIGS thin-film from the stainless steel substrate is needed to make monolithic production of lightweight CIGS-based photovoltaics feasible. This coating must allow good foil flexibility and exhibit high breakdownvoltages. The coating must also be compatible with the CIGS and metal substrate layers, both thermophysically and chemically. An inexpensive method of reliably depositing this thin coating over large areas of foil without pinholes is also desirable.To meet these requirements, Sommer Materials Research (SMR) has developed an ambient-air approach to deposit a layer of soda-lime glass on the surface of stainless steel foil sufficiently thin to allow the metal foil to be flexed to a small radius.Pinhole-free coatings with breakdown voltages as high as 350V were demonstrated on glass coatings less than 2 mils thick. In Phase II, a roll-to-roll deposition process will be developed to coat foil up to 5