Controllable Iodoplumbate-Coordination of Hybrid Lead Iodide Perovskites via Additive Engineering for High-Performance Solar Cells

The crystallization and growth of perovskite crystals are two crucial factors influencing the performance of perovskite solar cells (PSCs). Moreover, iodoplumbate complexes such as PbI₂, PbI₃^–, and PbI₄^2– in perovskite precursor solution dictate both the quality of perovskite crystals and the optoelectrical performance of PSCs. Here, we propose an iodoplumbate-coordination strategy that employs pentafluorophenylsulfonyl chloride (PTFC) as an additive to tailor the crystal quality. This strategy directly affects the thermodynamics and kinetics of perovskite crystal formation by regulating hydrogen bonds or coordination bonds with Pb²⁺ or I^– ions. Subsequently, the synergistic effect of the PTFC and FA⁺ complex was beneficial for intermediate-to-perovskite phase transition, improving the crystalline quality and reducing the defect density in the perovskite film to suppress nonradiative recombination loss. Consequently, the treated PSCs achieved a power conversion efficiency (PCE) of 24.61%, demonstrating enhanced long-term stability under both light and thermal stress. The developed device retained 92.53% of its initial PCE after 1200 h of continuous illumination and 88.6% of its initial PCE after 600 h of 85 °C thermal stability tests, respectively, both conducted in N₂ atmospheres.