Reducing series resistance in Cu2ZnSn(S,Se)4 nanoparticle ink solar cells on flexible molybdenum foil substrates

Earth abundant Cu2ZnSnS4 nanoparticle inks were depostied on molybdenum foil substrates and subsequently converted to high quality thin film Cu2ZnSn(S,Se)4 photovoltaic absorbers. Integration of these absorbers within a thin film solar cell device structure yields a solar energy conversion efficiency which is comparable to identical devices processed on rigid glass substrates. Importantly, this is only achieved when a thin layer of molybdenum is first applied directly to the foil. The layer limits the formation of a thick Mo(S,Se)x layer resulting in a substantially reduced series resistance.