Synthesis and characterization of silver indium diselenide thin films prepared via the sol-gel assisted process

Single-phased AgInSe ₂ thin films were successfully prepared via depositing sol-gel derived precursors, followed by a selenization process. The pure-phased AgInSe ₂ thin films were obtained at a selenization temperature as low as 400°C via adding the excess amount of In ³⁺ ions. Adjusting the In ³⁺/Ag ⁺ molar ratios can effectively prevent the formation of impurities Ag ₂Se and AgIn ₅Se ₈ in thin films. A Raman spectrum indicated that the obtained films belonged to chalcopyrite structure. The optical absorption revealed that the obtained AgInSe ₂ had the band gap of 1.23 eV. According to the GIXD analysis of the prepared films, the formation mechanism of AgInSe ₂ thin films is proposed. Se vapor reacts with Ag to produce Ag ₂Se at first, and then Se vapor subsequently reacts with In ₂O ₃ and Ag ₂Se to form AgInSe ₂. The sol-gel assisted route with a selenization process was demonstrated to be a potential way for preparing AgInSe ₂ thin films with densified microstructures.