ABSTRACT
The conversion efficiency of thin film solar cells based on Cu-rich grown CuInS2 is limited due to the electrically active absorber/buffer interface as well as due to the grain boundaries. The investigations carried out show that low admixtures of Zn to CuInS2 result in an enhanced Zn-concentration at the surface compared to the bulk of the film. This Zn-incorporation leads to an improved open circuit voltage exceeding 800 mV. Moreover, thermally activated recombination processes become dominant over a wider temperature range and the influence of the photosensitivity of the CdS buffer layer decreases. The conversion efficiency (η =10.4%) is limited by inferior transport properties till now.
