Coevaporated KInSe2: A Fast Alternative to KF Postdeposition Treatment in High-Efficiency Cu(In,Ga)Se2Thin Film Solar Cells

Cu(In,Ga)Se2-based thin film solar cells have reached 22.3% energy conversion efficiency. This outstanding level of performance has been made possible by the use of a so-called potassium fluoride postdeposition treatment (KF-PDT) after the absorber synthesis. Such a treatment, consisting of evaporating KF under Se atmosphere, has been suggested to enhance the formation of a KInSe2surface layer. In this paper, we propose an alternative to the standard KF-PDT, in which we simultaneously evaporate KF and In under Se atmosphere. We compare by X-ray photoemission spectroscopy the modified absorber surfaces in both cases and discuss the advantages of this alternative in terms of robustness and rapidity of the process.