Sol-gel assisted preparation and characterization of silver indium diselenide powders

AgInSe₂ powders were successfully prepared via mixing sol-gel derived precursors, followed by a selenization process. To obtain the pure AgInSe₂ compound, excess amounts of In³⁺ ions were added into the starting solution to compensate the loss of In₂O₃ during the selenization process. A figure that depicts the relationship between the resultant compounds and different selenization temperatures was constructed according to the formed phases. The Raman spectrum and Rietveld refinement confirmed that the prepared AgInSe₂ belonged to the chalcopyrite structure. With increasing selenization temperatures, the AgInSe₂ powder particle sizes as well as the crystallinity increased significantly. The AgInSe₂ formation mechanism during the selenization process is proposed as a two-step process. Ag₂Se is formed in the first step and then induces the second-step reaction to produce AgInSe₂. The sol-gel route with a selenization process is introduced as a new approach to fabricate pure AgInSe₂ powders for use in thin-film solar cells.