Mitigation of interface recombination by careful selection of ETL for efficiency enhancement of MASnI3 solar cell

Lead halide perovskite solar cells (LHPSC) are of great potential for commercial application with conversion efficiency exceeding 20%. But the toxic nature of lead, fabrication of perovskite solar cell is still not considered for commercial applications. Methylammonium tin halide perovskite (MASnI3) is being used as an alternate absorber layer for replacement of LHPSC but the power conversion efficiency (PCE) achieved from MASnI3 solar cell is still far less from LHPSC. To investigate the limitation of MASnI3 solar cell performance numerical analysis was performed. For device modeling different electron transport layer (ETL) and methylammonium tin halide (MASnBr3) as hole transport layer (HTL) was used. From analysis it was revealed that open circuit voltage (V0c), short cicuit current (Jsc), fill factor (FF) and PCE are highly depended on ETL conduction band offset (CBO) between ETL/Absorber (MASnI3) interface, thickness of ETL and donor doping concentration of ETL. With +CBO at junction a “cliff” is formed at the interface, this leads to high interface recombination because of built in potential to separate charge carriers. In contrast to -CBO a “spike” suppress interface recombination but a larger value of spike will lead to degradation of device performance. For selection of ETL, a moderate value of -CBO is required and this is achieved by changing elemental composition of ETL alloy materials (Cd1-xZnxS,ZnS1-xOx). These materials are expected to provide higher conversion efficiency for MASnI3 solar cell. A novel concept in numerical modeling is presented which will categorically offer new direction for the fabrication of high efficiency photovoltaic devices.