Interfacial chemistry control in thin film solar cells based on electrodeposited CuIn(S,Se)2

In this work, we present a study on CuIn(S,Se)2 absorbers prepared by electrodeposition followed by rapid thermal annealing promising to lower manufacturing cost. However the annealed material contains copper sulpho-selenide of Cu(Sy,Se1 − y) type which is harmful for the electrical properties of photovoltaic devices. These phases are removed by a cyanide etching. Because of an intrinsic variability of absorber fabrication process, the presented survey is based on statistic approach. We highlighted the influence of a cyanide treatment on surface and bulk compositions. The surface composition follows a distribution according to a Cu(S,Se)–CuIn(S,Se)2 system and the bulk composition agrees with Cu(S,Se)2–CuIn3(S,Se)5 system. Moreover, surface composition can be modified by adjusting the cyanide concentrations of etching solution without any changes in the bulk one. It ensues that Cu(S,Se) is not only present on the surface but also in the bulk of samples.