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

We report a chemical method to prepare Cu/In inks or Cu-In inks, from which CuInS2 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 CuInS2 films are compact with large grains and pure phases. The band gap of the CuInS2 film is determined to be similar to 1.45 eV, which is near the optimal band gap of the solar cell materials. Tentative CuInS2 solar cell with an efficiency of 0.7% is fabricated. (C) 2010 Elsevier B.V. All rights reserved.