ZnO/CdS/CuGaSe2 solar cells – absorber and device properties

Abstract

For solar cells based on CuGaSe2 (CGSe) polycrystalline thin films, a novel chemical close-spaced vapor transport technique is used to deposit CGSe absorber. Film characterisation including X-ray diffraction measurements, scanning electron microscopy observations, X-ray fluorescence and elastic recoil detection analysis has been carried out. Optical measurements were performed to monitor the changes in the CGSe band gap as a function of composition. These results are used for a discussion of the behaviour of the ZnO/CdS/CuGaSe2 solar cell photovoltaic parameters as well as of the current transport. For the first time, a thermally activated Shockley-Read-Hall recombination mechanism is observed for the CGSe- based solar cells in a large temperature region.