Activated Corrosion and Recovery in Lead Mixed-Halide Perovskites Revealed by Dynamic Near-Ambient Pressure X-ray Photoelectron Spectroscopy

作者：Michel De Keersmaecker, Paul Dietrich, Mounib Bahri, Nigel D. Browning, Neal R. Armstrong, Erin L. Ratcliff · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c00668 · 被引用次数：19 · 研究领域：Perovskite Materials and Applications、Electronic and Structural Properties of Oxides、Catalytic Processes in Materials Science

High Resolution Image Download MS PowerPoint Slide Herein, we quantify rates of O 2 -photoactivated corrosion and recovery processes within triple cation CsFAMAPb(IBr) 3 perovskite active layers using dynamic near-ambient pressure X-ray photoemission spectroscopy (NAP-XPS). Activated corrosion is described as iodide oxidation and lead reduction, which occurs only in the presence of both O 2 and light through photoinduced electron transfer. We observe electron density reorganization from the Pb–I bonds consistent with ligand exchange, evident from the nonstoichiometric redox change (i.e., <1 e – ). Approximately half of the Pb centers are reduced to weakly coordinated Pb–higher oxidation number than metallic Pb–with a rate coefficient of ∼3 (±0.3) × 10 –4 atomic percent/s. Hole capture by I – yields I 3 – and is accompanied by increased concentrations of near-surface bromides, hypothesized to be due to anion vacancies and/or oxidation of mobile iodide resulting from ion demixing. Activated corrosion is found to be quasi-reversible; initial perovskite stoichiometry slowly recovers when the O 2 /light catalyst is removed, postulated to be due to mobile halide species present within the film below XPS sampling depth. Small deviations in near-surface composition (<2%) of the perovskite are used to connect reaction rates to quantified, near-band edge donor and acceptor defect concentrations, demonstrating two energetically distinct sites are responsible for the redox process. Colle...