Interfaces in thin film solar cells

Interfaces are important for the efficiencies of thin film solar cells. In particular, for polycrystalline chalcogenide semiconductors as CdTe and Cu(In,Ga)(S,Se)₂ (CIGS) the existing physical concepts, which describe the electronic properties of elemental or III-V compound semiconductor interfaces quite well, are not sufficient. The increased complexity is mostly due to the non-abruptness of the interfaces and the strong tendency for the formation of defects in the more polar bonded II-VI compounds. Photoelectron spectroscopy has significantly contributed to the understanding of the mechanisms governing the properties of semiconductor interfaces in thin film solar cells. The experimental approach using integrated surface analysis and thin film deposition systems and selected results will be presented.