Synthesis and Characterization of Silver Indium Diselenide Thin Films Prepared via the Sol-Gel Assisted Process

Single-phased AgInSe2 thin films were successfully prepared via depositing sol-gel derived precursors, followed by a selenization process. The pure-phased AgInSe2 thin films were obtained at a selenization temperature as low as 400 degrees C via adding the excess amount of In3+ ions. Adjusting the In3+/Ag+ molar ratios can effectively prevent the formation of impurities Ag2Se and AgIn5Se8 in thin films. A Raman spectrum indicated that the obtained films belonged to chalcopyrite structure. The optical absorption revealed that the obtained AgInSe2 had the band gap of 1.23 eV. According to the GIXD analysis of the prepared films, the formation mechanism of AgInSe2 thin films is proposed. Se vapor reacts with Ag to produce Ag2Se at first, and then Se vapor subsequently reacts with In2O3 and Ag2Se to form AgInSe2. The sol-gel assisted route with a selenization process was demonstrated to be a potential way for preparing AgInSe2 thin films with densified microstructures.