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

Abstract

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-C₆₀ 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-C₆₀ 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 10¹⁷ 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 10¹⁷ cm⁻³ to 10¹⁶ 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 (10¹³ cm⁻³), both PSCs achieved a PCE close to 30%.