A tin-based perovskite solar cell with an inverted hole-free transport layer to achieve high energy conversion efficiency by SCAPS device simulation

Organic–inorganic halide perovskite solar cells (PSCs) have received extensive research in the field of optoelectronic materials. The absorption layer widely used in PSCs is methylammonium lead trihalide (MAPbX3, X = Cl, Br, I), still, the toxicity of lead (Pb) restricts its development, tin-based perovskite MASnI3 has attracted much attention due to its sound absorption characteristics. In this work, the perovskite solar cell adopts an inverted HTL-free structure, and the one-dimensional solar cell capacitor simulator SCAPS-1D (Solar Cell Capacitance Simulator) was adopted for numerical simulation and found that FTO/CH3NH3SnI3/C60/Au structure PSCs also showed excellent photovoltaic performance. We studied the influence of the thickness of the absorber layer, the defect density, the doping concentration of different layers, and we also studied PSCs with two structures, upright (p-i-n) and inverted (n-i-p) under the same lighting conditions. The simulation results show that the optimized inverted HTL-free tin-based PSCs based on C60 is with inspiring performance: a short-circuit current density (JSC) of 32.4566 mA/cm2, Open circuit voltage VOC (V) of 0.8585 V, fill factor (FF) of 73.72% and power conversion efficiency (PCE) of 20.54%. Based on HTL-free, the inverted structure can realize the PSCs to the maximum extent to ensure the light intensity of the incident perovskite layer, and the light-induced carriers could be effectively collected, directly increase the number of excitable electron–hole pairs, showing better performance. Based on the inverted HTL-free tin-based PSCs, we also listed the PSCs performance parameters of different material ETL. This work provides new ideas for PSCs development in the future.