Liquid CO₂-based coating for dense CuIn_xGa_1−xS₂ film fabrication

A liquid CO₂ (l-CO₂)–based coating technique is used for the pore-filling of a porous copper indium gallium sulfide (CuIn_xGa_1−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.