Cu(InGa)Se₂ photovoltaic absorber formation by spray-deposition of aqueous precursors followed by selenization

Aqueous precursor solutions prepared by water-soluble molecular precursors, CuCl₂, InCl₃, GaCl₃, and SeC(NH₂)₂, have been successfully employed to deposit Cu(InGa)Se₂ thin-film solar cell absorbers by spray-deposition followed by selenization. The spray-deposition process was optimized by adjusting the spray operation parameters (e.g., spray flow rate, time, and spray distance from substrate) and the substrate conditions (e.g., rotational speed and substrate temperature). The selenization process was then adjusted by changing the selenization temperature and Se flux. Here we report a cell efficiency of 4.7% obtained from spray-deposition of an aqueous precursor followed by selenization in a vacuum thermal evaporator.