Performance analysis of all-inorganic Cs3Sb2I9 perovskite solar cells with micro-offset energy level structure by SCAPS-1D simulation and First-principles calculation

With the swift progress of metal halide perovskite solar cells (PSCs), new Pb-free perovskites represented by Cs3Sb2I9 have demonstrated broader application prospects. However, compared with Pb-based PSCs, their photovoltaic properties still need to be further improved. In this work, an all-inorganic Cs3Sb2I9 perovskite solar cell with micro-offset energy level structure is proposed. In order to explore the influences of energy level matching and internal factors on the device, we use SCAPS-1D (Solar Cells Capacitor Simulator) to simulate the device numerically. It is shown that the micro-offset energy level structure constituted by ZnOS/Cs3Sb2I9/Cu2O significantly improves the built-in electric field and carrier transport path of PSCs, promotes the motion of photogenerated electron-hole pairs between layers, and makes the device exhibit outstanding performance. Further, the PSCs are optimized in terms of transport layer doping concentration, absorber layer thickness, defect density, metal back electrode, and so on. Through comprehensive analysis of the built-in electric field, energy band structure, and recombination rate, the optimal value of doping concentration in the transport layer is determined to be 1019cm−3. In addition, the optical and electrical properties of the absorber layer are investigated by first-principles. Finally, we achieved the optimal parameters in the proposed device structure (FTO/ZnOS/Cs3Sb2I9/Cu2O/C), and the power conversion efficiency reached up to 18.29% with a fill factor of 90.59%. This work demonstrates that micro-offset energy level structure has enormous potential for future inorganic PSCs with antimony as the metal cation.