Optimization CIGS/CIGS Tandem Solar Cells by Adjusting Layer Thickness Using Silvaco-Tcad

This research designed and simulated CIGS/CIGS back-to-back solar cells using Silvaco-Atlas software. We considered CIGS absorbing layer thickness and sub-cells as critical parameters to optimize the performance of the CIGS/CIGS tandem solar cell. The research comparatively examined the effect of different electrode metals, such as molybdenum, aluminum, titanium, and silver, on the efficiency. The electrical parameters of the best CIGS/CIGS tandem solar cell configuration were a short-circuit current density (Jsc) of 15.65 mA/cm², an open-circuit voltage (Voc) of 1.86 V, a fill factor (FF) of 86.04%, and a conversion efficiency (η) of 27.12%. The optimal CIGS absorbing layer thickness of the top and bottom cells corresponding to the maximum conversion efficiency obtained were 0.17 and 6.3 μm, respectively. In contrast, the optimal thickness of the Cds layer was 0.04 µm. Silver had the best performance in connecting layers between several metals. The results can be used to develop low-cost and high-efficiency solar cells.