Optimizing photovoltaic performance: Strategic enhancement of Ag-doped graded CAZTS solar cells achieving 27.3% efficiency

The Ag-doped Cu2ZnSnS4 (CAZTS) based solar cell has been explored, with varying Ag concentrations (x = 0, 0.1, 0.2, 0.3, 0.4) in the composition (Cu1−xAgx)2ZnSnS4. In order to mitigate back surface recombination in CAZTS-based solar cells, a Sn2S3 layer has been incorporated as a back surface field (BSF). Further, the efficiency enhancement employs a bandgap grading approach, elevating efficiency from 15.8 % to 24.7 % compared to devices without the graded structure. Additionally, the thickness and total defect density of the CAZTS layer are optimized. The result demonstrates that the optimized value of the CAZTS layer’s thickness is 1.1 µm, and the defects are 1 × 1012 cm−3. To further enhance the performance, the doping variation of the CAZTS layer has also been investigated. The findings indicate that the maximum efficiency of 27.32 % is attained with a doping value of 1 × 1016 cm−3.