Multifunctional SnO 2 /Perovskite Interface Engineering for Efficient Perovskite Solar Cells

Abstract Perovskite solar cells (PSCs) have shown significant advancements and commercial potential; however, their efficiency is often limited by defects in the bulk material and surface. Stability issues, such as ion migration and degradation of perovskite materials, further exacerbate this challenge. In this study, a strategy using aluminum chloride is introduced to eliminate hydroxyl groups and potassium ions from the tin dioxide (SnO 2 ) surface, effectively reducing deprotonation of perovskite. This process also forms an ultra‐thin aluminum oxide layer at the SnO 2 /perovskite interface, functioning as a passivation layer. This modification decreases leakage current and charge carrier recombination, lowering the energy barrier for electron transport, resulting in enhanced open‐circuit voltage and overall efficiency. The approach achieved a certified efficiency of 26.29% in single‐junction n‐i‐p PSCs, marking the highest reported efficiency for the n‐i‐p PSCs utilizing SnO 2 electron transport material. The devices retained 94% of their initial efficiency after 10 044 h in dry air (5% relative humidity) and demonstrated a T 80 lifetime of over 500 h under continuous illumination, demonstrating superior stability compared to control cells. This research provides critical insights into engineering the chemical and physical interface properties and enhancing the photovoltaic performance of PSCs.