Computational insights into wide bandgap lead free perovskite solar cells for silicon based tandem configurations.

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(IBr) 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(IBr) 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 (V) of 2.04 V, a short-circuit current density (J) of 21.14 mA/cm, and a fill factor (FF) of 77.26%. For comparison, the perovskite top cell alone achieved a V of 1.36 V, J of 20.44 mA/cm, FF of 75.51%, and PCE of 21.07%. The bottom cell under AM 1.5G illumination exhibited a V of 0.68 V, J of 40.36 mA/cm, FF of 80.18%, and PCE of 22.05%. Under a filtered spectrum, the bottom cell produced a V of 0.67 V, J of 30.46 mA/cm, 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.