Spray-coated Ag Back Contacts for III-V Solar Cells

The continuity of III-V photovoltaics as the dominant technology in space applications and its expansion for terrestrial applications demand the development of cost-effective solutions for the processing of these devices. Here, we assess spray-coated Ag back contacts as a substitute for the expensive e-beam evaporated metals currently used in industry. We find that the spray-coated Ag films are dense, continuous, and meet the ISO 0 adhesion standard on the unpolished back of p-type GaAs substrates. Most importantly, by means of quantum efficiency, dark current-voltage, and illuminated current-voltage characterizations, we show that GaAs upright solar cells with spray-coated Ag back contacts perform equally well as their baseline counterparts with electroplated Au back contacts even under concentrated illumination. This work is part of a coordinated research effort that investigates alternative techniques to reduce the cost of III-V solar cells.