Design and Optimization of Highly Efficient a-Si:H/µc-Si:H Tandem Solar Cell

Silicon material based solar cells are considered as the most rapid developing technology for higher efficiency and cost-effective in the photovoltaic (PV) industry. However, Si-based single junction suffers from transmission and thermalization losses. Therefore, to overcome these losses, tandem solar cells (TSCs) are established. Here, 2-terminal a-Si:H/µc-Si:H based TSC is simulated and examined through Silvaco-TCAD tool. In the proposed work, two absorber materials viz. a-Si:H with bandgap (Eg=1.7 eV) for top cell and µc-Si:H (Eg=1.16 eV) for bottom cell are used through interlayer (ITO). The complete performance of TSC is studied by changing the thickness of both top absorber layer (TopABL) (50-300 nm) and bottom (BottomABL) (500 to 3000 nm) cells, collectively and analyzed through PV parameters, EQE and JV curve. The champion tandem device delivers high values of PV parameters viz. short circuit current density (JSC) of 10.21 mA/cm2, open circuit voltage (VOC) of 1.35 V, fill factor (FF) of 72.3% and power conversion efficiency (PCE) of 10% at optimal values as TopABL of 200 nm and BottomABL of 2500 nm.