Performance improvement approach of all inorganic perovskite solar cell with numerical simulation

Lead-halide perovskites (PVKs) based solar cells have seen remarkable consideration due to improved efficiency, ease of fabrication, versatility and flexibility. However, the existence of lead, a toxic material, raises several concerns about the environment and the health of living beings and hinders their future commercialization. Therefore, a considerable surge in searching for an alternate lead-free PVK has started in the past few years. Several lead-free PVK solar cells have been proposed; nonetheless, achievable conversion efficiency from these devices is not up to the mark due to some inherent losses. Therefore, a comprehensive theoretical analysis is needed to understand the root of these losses for uplifting efficiency. Thus, the results of a specific modelling technique for all-inorganic lead-free PVK-based solar cells, namely cesium tin germanium halide (CsSnGeI₃), to achieve the highest feasible efficiencies. The current simulation uses an electron transport material (ETM) of TiO₂ and a hole transport material (HTM) of Spiro-OMeTAD to sandwich PVK layers of CsSnGeI₃ (Eg=1.5 eV) for the PSCs. The device is subjected to further analysis and optimization of active layer thickness, defect density, operating temperature, defect density, capacitance-voltage (C-V) and impedance analysis to investigate the different performance parameters. The optimized conversion efficiency of 28.4% has been achieved with CsSnGeI₃-based PSC. Results reported in this study may pave the way to developing lead-free PVK solar cells through higher conversion efficiencies.