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.