Synthesis and characterization of CIS nanoparticle ink for low-cost thin film solar cells

CuSe and CuInSe₂ nanoparticles were synthesized through the aqueous solution process using NaBH₄ solution as a solvent and subsequent heat-treatment. Not only the synthesized nanoparticles, CuSe and CuInSe₂, but also spray-coated thin films prepared by using CuSe and CuInSe₂ were characterized by XRD, SEM-EDS, TGA and UV-Vis spectroscopy. CuSe nanoparticles with a plate-like shape, which were confirmed by XRD and SEM, were directly prepared by a reaction of a mixture of CuCl₂ and Se in the aqueous solution of NaBH₄ at room temperature. Cu-In-Se compounds were obtained through the reaction of CuCl₂, InCl₃, and Se in the aqueous solution of NaBH₄, were consisted of the mixture of CuSe_x and In hydroxides, and were transformed into CuInSe₂ with a chalcopyrite structure by a heat-treatment at 300 °C.