Cu_2ZnSnSe_4 thin film solar cells produced via co-evaporation and annealing including a SnSe_2 capping layer

摘要

(CZTSe) thin film solar cells have been produced via co-evaporation followed by a high-temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe_2 capping layer has been evaporated onto the absorber prior to the high-temperature treatment. This eliminates the Sn losses due to SnSe evaporation. A solar cell efficiency of 5.1% could be achieved with this method. Moreover, the device does not suffer from high series resistance, and the dominant recombination pathway is situated in the absorber bulk. Finally, different illumination conditions (white light, red light, and yellow light) reveal a strong loss in fill factor if no carriers are generated in the CdS buffer layer. This effect, known as red-kink effect, has also been observed in the closely related Cu(In,Ga)Se_2 thin film solar cells.