Damp-heat induced sulfate formation in Cu(In,Ga)(S,Se)2-based thin film solar cells

To investigate the impact of damp heat treatments on the electronic and chemical structure of Cu(In,Ga)(S,Se)(2)-based thin film solar cells, we have performed a detailed soft x-ray emission study of the ZnO/CuIn(S,Se)(2) and ZnO/CdS/CuIn(S,Se)(2) interfaces. By comparing the sulfur L-2,L-3 emission spectra of pristine and damp-heat treated samples, we find a sulfate formation at the ZnO/CuIn(S,Se)(2) and the ZnO/CdS interface. The intensity behavior as a function of ZnO film thickness further reveals a diffusion of sulfur atoms into the ZnO film, leading to the formation of zinc sulfate in the ZnO window layer of damp-heat-treated Cu(In,Ga)(S,Se)(2)-based solar cells. (C) 2002 American Institute of Physics.