Influence of composition ratio on the performances of kesterite solar cell with double CZTS layers-A numerical approach

Effects of double CZTS layers with different composition ratio Cu/Zn in which a high copper concentration at the bottom and a low copper concentration at the top on the physical parameters and cell performance of CZTS solar cells by using the one-dimensional SCAPS-1D numerical model have been analyzed and discussed. In this study, it is demonstrated that a numerical analysis can provide informative predictions of the CZTS solar cell's performance proposed. The agreement between simulated and observed data was sufficient to indicate that the general response of the cell performance is reasonably represented. The high Cu/Zn ratio of the bottom layer was shown as very influential on the parameters of solar cells, where: (i) this bottom layer becomes an electrical mirror for the minority carriers, (ii) effective surface recombination velocity reduce, (iii) Auger recombination mechanism become more important, (iv) high efficiency depends strongly on the larger thickness of top layer, and finally (v) bandgap energy of bottom layer decreases and achieved best cell performance.