Numerical Simulation and Design Optimization of Highly Efficient Lead-free Perovskite/c-Si Tandem Solar Cell

With the unprecedented development of Perovskite-Si tandem solar cells technology in the last five years, it has become essential to eliminate the toxicity content by using lead-free perovskite materials. For this purpose, a numerical study using the SCAPS-1D simulation tool was demonstrated to investigate lead-free perovskite on the crystalline silicon-based tandem cell structure. The tandem cell combination of (CH
3
NH
3
SnIBr
2
), a Pb-free perovskite, as upper absorber layer, and (c-Si) as the lower cell is used for the first time. The suggested tandem structure demonstrates an optimal device efficiency of 30.55%. Our numerical Simulation was done in two steps. First, the top cell CH
3
NH
3
SnIBr
2
and bottom cell (c-Si) are simulated as standalone cells to optimize the performance of these single-junction solar cells. Then, 2-T perovskite/c-Si tandem configuration was performed by utilizing the optimized upper and lower cells. To achieve the current matching point for the two-terminal tandem structure, the upper absorber layer thickness of (CH
3
NH
3
SnIBr
2
) should be adjusted to 0.3545 μm. At this thickness, a JSC of 16.08 (mA/cm
²
) is obtained for the two subcells with efficiencies of 20.58% and 19.22% for the upper and lower cells, respectively. Overall, the CH
3
NH
3
SnIBr
2
/c-Si tandem cell yields an impressive PCE of 30.55% with VOC of 2.185 V.