Reducing series resistance in Cu 2 ZnSn(S,Se) 4 nanoparticle ink solar cells on flexible molybdenum foil substrates.

Earth abundant Cu 2 ZnSnS 4 nanoparticle inks were deposited on molybdenum foil substrates and subsequently converted to high quality thin film Cu 2 ZnSn(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.