A thermal route to synthesize photovoltaic grade CuInSe₂ films from printed CuO/In₂O₃ nanoparticle-based inks under Se atmosphere Available to Purchase

In this work we present an alternative thermal route for the synthesis of CuInSe₂ light absorber films for photovoltaic applications from printed CuO/In₂O₃ nanoparticle-based inks. We demonstrate the possibility of substituting highly toxic (H₂Se) and explosive (H₂) gases for the processing of this type of precursors, using more environmental friendly gases (elemental Se and Ar/H₂ mixtures). We show that by using Ar/H₂ mixtures with low H₂ concentration, it is possible to reduce the oxide nanoparticles to their metallic form, thus priming the film for subsequent selenization. This reactive thermal process seems to be the critical step to obtain large CuInSe₂ grains with photovoltaic activity. Optimizing the proposed thermal route, based on less toxic, safer, and more eco-friendly gases, we obtain a very promising 2.4% efficiency solar cell based on CuInSe₂ films as the absorber layer.