Fullerene-C₆₀ and PCBM as interlayers in regular and inverted lead-free PSCs using CH₃NH₃SnI₃: an analysis of device performance and defect density dependence by SCAPS-1D

One of the challenges hindering the commercialization of perovskite solar cells (PSCs) is the presence of toxic metals such as lead in their composition. Simulation studies using SCAPS-1D have already been conducted on lead-free PSCs to find optimized solar cell parameters, having tin as the primary candidate for replacing lead in perovskites. Here, we used fullerene-C-60 and its derivative PCBM as interlayers in a lead-free tin-based PSC between the ETL (ZnO) and the perovskite MASI in both regular and inverted configurations of PSCs using SCAPS-1D software. To the best of our knowledge, this is the first simulation study reporting the impact of using fullerene-C-60 and PCBM as interlayers in lead-free PSCs. The defect density (N-t) of the perovskite material is varied, allowing us to observe its influence on the power conversion efficiency (PCE). Using an N-t value of 10(17) cm(-3) without the interlayer, the PCE was 6.90% and 3.72% for regular and inverted devices. Using PCBM as an interlayer improves the efficiency of both simulated PSCs, achieving a maximum PCE of 8.11% and 5.26% for the regular and inverted configurations, respectively. Decreasing the N-t from 10(17) cm(-3) to 10(16) cm(-3) caused a significant increase in efficiency, reaching 13.38% (n-i-p) and 10.00% (p-i-n). Finally, using the optimized parameters and an ideal N-t value (10(13) cm(-3)), both PSCs achieved a PCE close to 30%.