Enhancing perovskite solar cell performance through PbI₂ in situ passivation using a one-step process: experimental...

The in situ passivation of a methylammonium lead triiodide (MAPbI₃) phase spin-coated via a one-step process was experimentally investigated to elucidate their fundamental properties. Structural analysis revealed that MAPbI₃ adopts a tetragonal crystal structure with a small excess of PbI₂ (0.03 M) segregating at grain boundaries. Optical characterization indicated a band gap of 1.53 eV, highlighting the material's potential as an effective visible light absorber. To facilitate the fabrication of efficient perovskite solar cells (PSCs), we employed a primary n-i-p planar structure (ITO/SnO₂/MAPbI₃/spiro-OMeTAD/Au) in drift-diffusion SCAPS-1D simulations using experimental data from MAPbI₃ layers containing excess PbI₂. The simulations predicted a high power conversion efficiency (PCE) of approximately 24%. We further analyzed the impact of series resistance, shunt resistance, MAPbI₃ thickness, defect density, as well as radiative and Auger recombination on photovoltaic performance, aiming to identify optimal parameters for enhanced device efficiency. Additionally, the use of ohmic contacts with AZO and IZO as the front and rear contacts, respectively, in the optimized device structure (AZO/SnO₂/MAPbI₃/spiro-OMeTAD/IZO) resulted in a PCE of 26.03%. These findings provide valuable insights for future research aimed at achieving high-efficiency bifacial MAPbI₃ perovskite solar cells.