Device Simulation of a Thin-Layer CsSnI₃-Based Solar Cell with Enhanced 31.09% Efficiency

In the last decade, perovskite-based solar cells (PSCs) have become the hotspot in photovoltaic (PV) research around the globe because of their excellent photovoltaic performance in terms of their high-power conversion efficiency. However, the stability and existence of lead in the perovskite absorber layer hindered their use in practical applications. In the present study, we evaluated the numerical simulation-based performance of oxide/perovskite/oxide-type PSCs using the one-dimensional solar cell capacitance program (SCAPS-1D). Initially, the effect of various oxide-based electron transport layers (ETLs; TiO2, SnO2, and ZnO) and hole transport layers (HTLs; NiO, Cu2O, and CuO) on PSC performance was evaluated. It was found that a solar cell with TiO2 as an ETL and NiO as an HTL (FTO/n-TiO2/CsSnI3/p-NiO) exhibited the highest PV performance in terms of power conversion efficiency (PCE ∼ 30.57%), and other parameters were open circuit voltage (VOC ∼ 0.98 V), short circuit current density (JSC ∼ 35.17 mA/cm2) and fill factor (FF ∼ 88.43%). Next, we evaluated the effect of the thickness of TiO2, NiO, and CsSnI3 layers of the above-benchmarked device, along with their bulk and interface defects in detail. It is successfully demonstrated that the PCE and FF can further reach values of 31.09 and 88.39%, respectively, at a 1.25 μm thick CsSnI3 absorber with a band gap of Eg ∼ 1.35 eV. The obtained results and detailed analysis will provide an important basis for the selection of CsSnI3 as an absorber with optimized defects.