Optimization of Mixed Sn and Pb Perovskite Solar Cell in Terms of Transport Layers and Absorber Layer Thickness Variation

The performance of the organic and inorganic halide perovskite solar cells (PSCs) has been improved rapidly in the last few years. In literature maximum PSCs are based on lead (Pb) based perovskite (CH₃NH₃PbI₃) and such PSCs have reflected record conversion efficiency of 25.2% in the year 2020. PSCs own some unique properties like excellent optical absorption, bandgap tunability and low fabrication cost. This makes hybrid PSCs most promising for photovoltaic (PV) industry by means of performance with power conversion efficiency (PCE). We in this work report the simulation study on a low bandgap (1.2eV) mixed Sn (50%) and Pb (50%) halide (MAPb_0.5Sn_0.5I₃) PSC structure. Initially a device with the combination of C₆₀ (Buckminsterfullerene) and IC₆₀BA (Indene-C₆₀ Bisadduct) as electron transport layer (ETL) and PEDOT: PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) as hole transport layer (HTL) respectively is calibrated. Thereafter, the analysis has been performed by using different set of HTLs like PEDOT: PSS, P3HT, Cu₂O and Spiro-OMeTAD in which highest PCE of 13.57% is achieved with C₆₀ & IC₆₀BA (ETL) and PEDOT: PSS (HTL). Followed by ETLs (mp-TiO₂ and CdS) variation which reflected the highest PCE (18.82%) with mp-TiO₂ (ETL) and PEDOT: PSS (HTL). The results are further summarized in terms of absorber layer thickness variation from 50 nm to 300 nm at the optimized ETL (mp-TiO₂) and HTL (PEDOT: PSS) material. The exercise carried out in this work showed optimized conversion efficiency of 19.21%. Work reported in these studies may open up the window for the development of low lead content perovskite based high efficiency PSCs.