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The quest for high-efficiency solar cells has led to significant research into lead-free perovskite materials, particularly tin-based perovskites. This study investigates the photovoltaic properties of various compositions of FASn(I1 − xBrx)3 perovskites for potential application in solar cells. Computational simulations explore the influence of absorber layer thickness and bulk defect density on the performance of lead-free single-junction perovskite solar cells. Additionally, a two-terminal monolithic tandem solar cell configuration comprising FASn(I0.75Br0.25)3 for the top cell and silicon for the bottom cell is proposed and analyzed. The proposed tandem device, with a 1.66 eV perovskite top cell and a 1.12 eV c-Si-based heterojunction, achieved a maximum power conversion efficiency (PCE) of 33.39%, an open circuit voltage (VOC) of 2.04 V, a short-circuit current density (JSC) of 21.14 mA/cm2, and a fill factor (FF) of 77.26%. For comparison, the perovskite top cell alone achieved a VOC of 1.36 V, JSC of 20.44 mA/cm2, FF of 75.51%, and PCE of 21.07%. The bottom cell under AM 1.5G illumination exhibited a VOC of 0.68 V, JSC of 40.36 mA/cm2, FF of 80.18%, and PCE of 22.05%. Under a filtered spectrum, the bottom cell produced a VOC of 0.67 V, JSC of 30.46 mA/cm2, FF of 79.13%, and PCE of 16.33%. This performance comparison highlights the enhanced efficiency, voltage, and overall stability provided by the tandem structure over individual cells. This examination encompassed the variation of absorber layer thickness, J-V curves under illumination, quantum efficiency, energy band diagrams, filtered spectra, and tandem photovoltaic parameters governing the conversion efficiency. The study demonstrates the potential of lead-free perovskite/silicon tandem devices, showcasing their promise for the future development of high-efficiency and stable solar cells.
Tahir et al. (Fri,) studied this question.