Complexing agent-assisted highly dense CuInSe2 thin films prepared by one-step electrochemical deposition

Highly dense CuInSe2 (CISe) thin films were electrochemically deposited on Mo-coated soda-lime glass substrates in aqueous solution. Three compounds, CuCl2, InCl3, and SeO2, were used as precursors with glycine or oxalic acid as complexing agents. The deposition process was carefully selected through preliminary study of the individual electrochemical properties of the three precursors. To achieve ideal stoichiometry and uniform deposition of CISe thin films, the reaction temperature and acidity of precursor solution were investigated. As the reaction temperature increased, Cu deficiency was observed in the CISe thin film. The density and surface morphology of CISe films prepared by one-step electrodeposition were affected strongly by the acidity of deposition solution. The addition of HCl to solution improved the density and surface roughness of as-deposited CISe films. Denser and larger grain size CISe polycrystalline films were prepared in oxalic acid solution. Two-step heat treatments for the prepared CISe samples were applied to fabrication of CISe photovoltaic devices without an additional Se source.