\captionsetup [figure]justification=raggedright, singlelinecheck=false, font=footnotesize \captionsetup[subfigure]justification=centering [1]¿m#1 The stability of buried interfaces is critical to the long-term performance of perovskite solar cells (PSCs), yet it is often compromised by the light-induced oxidation of iodide ions, followed with structural degradation. To address this issue, we incorporated boric acid (BA) into the SnO2 electron transport layer (ETL). The addition of BA not only enhances the carrier mobility and hydrophilicity of the SnO2 layer but also effectively suppresses the deprotonation of formamidine iodide (FAI) and the oxidation of iodide ions. As a result, the stability of the perovskite film on the BA-SnO2 substrate under intense UV illumination was highly improved. Furthermore, devices with the modified ETL retained 80% of their initial efficiency after 1500 hours of aging at 85 ℃, significantly outperforming the control devices, which retained only 60%. This work demonstrates that ETL modification with BA is a highly effective strategy for stabilizing buried interfaces and enhancing the overall durability of PSCs.