A general route to Earth abundant element absorber layers for thin film photovoltaics with high yield using molecular precursors and non-toxic solvents

Earth abundant absorber materials are the most promising candidates for terawatt-scale thin film photovoltaics due to the robust supply chains for the elements involved. The strongest initial candidate appears to be Cu2ZnSnS4 (CZTS), but there are other potential material systems such as FeS2, CuO, and PbS that are just beginning to be re-examined with solution phase processing. Here we report a new, facile, and scalable chemical route to Earth abundant element thin film solar cells by coating a solution of highly soluble, inexpensive, and commercially available precursors in an environmentally friendly non-toxic solvent to form device quality films. Air-stable CZTS photovoltaic devices with 4.1% total area power conversion efficiency are obtained. We have generalized the chemical route and have used it to also fabricate PbS devices that are 1.5% efficient.