Extensive numerical elucidation of trifluoromethanesulfonyl anion stabilization effects in air-fabricated FAPbI₃ perovskite solar cells for industrial applications

Despite the high power conversion efficiencies of perovskite (PVT) solar cells (PSCs) fabricated via low-temperature, solution-based processes, persistent challenges such as precursor ink aging and environmental sensitivity hinder large-scale manufacturing. To overcome these issues, this study supports a recently proposed anion-stabilization strategy using trifluoromethanesulfonyl (TFSI), a pseudo-halide bisimide ion, on the well-established formamidinium lead iodide (FAPbI₃) absorber, implemented through a scalable two-step air-fabrication method. For the first time, an extensive and systematic numerical investigation is carried out to evaluate the optoelectronic implications of TFSI treatment on device performance. Using SCAPS-1D, critical parameters including absorber thickness, acceptor density, effective density of states, interfacial defect density, and series/shunt resistances were precisely varied in a FTO/SnO₂/FAPbI₃/Spiro-OMeTAD/Au structure. The simulated results were benchmarked against experimentally reported current density–voltage characteristics of TFSI-treated and untreated devices, validating the model and capturing the essential benefits of the treatment. The optimized TFSI-treated PSC achieved an impressive efficiency of 25.72 % at a valence band effective density of 1 × 10¹⁸ cm⁻³, and up to 25.96 % under ideal series resistance conditions. This work not only affirms the performance-enhancing potential of the recently introduced TFSI treatment but also delivers the first detailed parametric insight into its influence, demonstrating a promising pathway toward stable, high-yield, and air-processable PSCs that are immune to precursor aging.