Performance optimization of a CsGeI₃-based solar device by numerical simulation

Germanium-based halide perovskites (CsGeI₃) are good absorbers materials for eco-friendly perovskite solar devices. In this work, a numerical analysis via SCAPS-1D software, is done to enhance the performance of a device already experimentally realized (FTO/TiO₂/CsGeI₃/Spiro-OMeTAD/Ag). After selecting SnO₂ and CuI as best Charge transport materials (CTMs) in front of others, we have optimized their thicknesses, we investigated the impact of: CsGeI₃ thickness, its defect density (N_t), its acceptor concentration, CuI doping density, SnO₂ doping density, SnO₂/CsSnI₃ defect density, CsSnI₃/CuI defect density, also the impact of shunt resistance, series resistance, and temperature. Finally, we have achieved a new solar device based on CsGeI₃, with a fully inorganic FTO/ SnO₂/CsGeI₃/CuI/Ag structure. The final output parameters are PCE = 15.68 %, FF = 73.45 %, J_SC = 22.56 mA/cm² and V_OC = 0.946 V at room temperature. The results are beneficial for the design and manufacture of CsGeI₃-based solar devices.