numerical modeling and simulation of a monolithic CZTGS/CZTS tandem structure has been carried out using SCAPS-1D. This is aimed at enhancing the performance of copper zinc tin sulfide (CZTS) solar cell using a double junction CZTGS/CZTS tandem structure. The top cell consists of a non-toxic element (germanium) used in tuning the band gap of copper zinc tin germanium sulfide (CZTGS) while the bottom cell is CZTS based. The best J–V characteristics of the top cell was obtained at a composition ratio of Cu2ZnSn0.8Ge0.2S4 with an efficiency of 9.39%. The bottom cell condition is simulated based on the state-of-art records with an efficiency of 8.4% which is in good agreement with experimental results. At an absorber thickness of 0.65 μm and 3.00 μm of the top and bottom sub-cell of the tandem structure under current matching condition of 18.53 mA/cm² gave an efficiency of 17.51%. This is a significant improvement in efficiency over that of the CZTS thin film solar cell with a single junction.
i have made a lecture series on SCAPS usage, and provided publication oriented demos/tutorials, you can access it in youtube , serach with key word as "atul kumar scaps"