Optimization of CsPb0.75Sn0.25IBr2-based perovskite solar cells using different hole transport materials by SCAPS-1D

In recent years, there has been a significant increase in the literature on all-inorganic perovskite solar cells (PSCs), which are potential candidates for resolving the impasse linked to the high volatility of the organic part of hybrid perovskites. Among the light absorbers in CsPb_1-xSn_xIBr₂ type, CsPb_0.75Sn_0.25IBr₂ exhibits better film quality, good phase stability under illumination and no phase segregation due to its low hysteresis. This makes the CsPb_0.75Sn_0.25IBr₂ light absorber is a viable alternative that combines efficiency and stability in photovoltaic solar cells. In this paper, we used the SCAPS-1D simulation software to model the FTO/TiO₂/CsPb_0.75Sn_0.25IBr₂/Spiro-OMeTAD/Au photovoltaic solar cell, with an initial power conversion efficiency (PCE) of 14.13 %. A study was carried out to optimize the performance of the cell by varying the parameters of several layers. We studied the effect of the absorber layer thickness, defect density, doping concentration and Auger recombination rate; the effect of the TiO₂ layer doping concentration and the TiO₂/CsPb_0.75Sn_0.25IBr₂ interface defect density. We also considered the influence of changing the hole transport layer (HTL) and the back contact on the cell performance. Thus, we have modeled and optimized two solar cells, one using Spiro-OMeTAD, an organic HTL, and the other NiO, an inorganic HTL, with efficiencies of up to 17,41 %. These efficiencies are significantly higher than those obtained in a theoretical study (PCE = 13.82 %) and in an experimental study (PCE = 11.53 %). This study suggests a way forward for the development of all-inorganic PSCs, offering improved efficiency and phase stability.