DFT and SCAPS-1D calculations of FASnI3-based perovskite solar cell using ZnO as an electron transport layer

In this work, we used both DFT and TDDFT to investigate the structural, electronic and optical properties of the hybrid organic-inorganic FASnI3 perovskite. Indeed, we apply the DFT approach implemented under Quantum Espresso code to investigate and discuss the solar perovskite FASnI3 applying the calculation approximations: GGA-PBE and GGA-PBESol. When applying the PBE approximation, the band structure demonstrates that this perovskite has a direct band gap of (1.36eV), which agrees well with the results of the existing experiments. The DOS and PDOS have been illustrated and discussed for the two cases. We have also examined of including the spin-orbit coupling effect on the band gap of this material, in addition, the optical properties of the this FASnI3 have been computing and discussed. The band gap and optical properties allowed us to assume that this material could potentially be the best match for photovoltaic use. Further, applying SCAPS software, an n-i-p planar FASnI3 solar perovskite device was modeled and simulated. The device performances have simulated with (ZnO, ZnS, ZnSe, TiO2 and CdS) materials as an Electron Transport Layers. It is found that various factors influencing the device performance such as the thickness of the FASnI3, different ETLs, the impact of the temperature, are also investigated and discussed. In addition, the impact of the active layer defect level and doping level were examined. The simulation results demonstrates that high efficiency of 28.13% can be produced with an absorber thickness of around 600nm, and a total defect density of 1014cm-3 with (ZnO) as an ETL at a temperature of 300k. Finally, these theoretical simulation results could pave the path to design and fabricate, efficient lead-free PSCs.