LAUSR

In this work, new Cu 2 ZnSn(S 1−x , Se x ) 4 (CZTSSe) solar cells consisting of two absorber layers with constant and graded bandgaps are proposed. CZTS and CZTSe are used as the constant bandgap absorbing layers of the first and second proposed cells, respectively. To validate the simulations, first, a graded bandgap CZTSSe-based cell containing AZO/ZnO/CdS/CZTSSe/MoSe 2 /Mo layers as the basic structure is investigated, revealing that the results are in good agreement with previous experimental data. The impact of varying acceptor doping concentration and temperature on the performance of proposed cells is investigated. The optimum thicknesses of the absorber layers are obtained in all cases. After optimization, maximum efficiencies of 20.99% and 21.37% are obtained for the first and second cells respectively which are significantly greater than the basic structure. The proposed structures provide higher open circuit voltage and short circuit current, compared to the basic structure.