Liquid CO2-based coating for dense CuInxGa1−xS2 film fabrication

•A liquid CO2 (l-CO2)-based coating technique was used for the pore-filling of a porous CIGS film.•The use of an indium-rich solution in l-CO2 improves the pore-filling behavior.•The pore-filled CIGS had a highly dense film structure.

A liquid CO2 (l-CO2)-based coating technique is used for the pore-filling of a porous copper indium gallium sulfide (CuInxGa1−xS2, CIGS) film synthesized by a solution-based method. In the l-CO2-based coating, copper and indium precursors dissolved in l-CO2 are deposited on the porous copper indium gallium oxide film, followed by low-temperature sulfurization. After the high-temperature sulfurization of the deposited film with the l-CO2-based coating, a highly dense CIGS film with almost complete pore-filling is obtained. The use of an indium rich solution in l-CO2 leads to the formation of near stoichiometric ratio of Cu:(In + Ga) that improves the pore filling behavior.

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