Chemical synthesis of Cu(In) metal inks to prepare CuInS2 thin films and solar cells

Abstract We report a chemical method to prepare Cu/In inks or Cu–In inks, from which CuInS 2 films are formed. Cu, In and Cu–In nanoparticles are initially synthesized by a polyol method, and then dispersed in solvents to form inks. Metal films are subsequently obtained by drop-casting the Cu inks and In inks in sequence or Cu–In inks directly. The sulfurization of the metal films is carried out in a tube with high sulfur vapors. The obtained CuInS 2 films are compact with large grains and pure phases. The band gap of the CuInS 2 film is determined to be ∼1.45 eV, which is near the optimal band gap of the solar cell materials. Tentative CuInS 2 solar cell with an efficiency of 0.7% is fabricated.