High‐Nuclear Metal–Oxide Cluster Porous Interlayers Enabling Tailored Carrier Transport and Ion‐Exchange Lead Leakage Prevention in Perovskite Solar Cells

Although interface engineering has become a key strategy for enhancing the efficiency and stability of perovskite solar cells (PSCs), existing interface materials still struggle to achieve a balance between defect passivation, charge transport, and suppression of lead leakage. In this study, the barium‐zinc‐antimony oxide cluster‐based material H 1.03 Ba 2.485 (H 2 O) 15 [Zn 2 Sb 12 (μ 3 ‐O) 8 (μ 4 ‐O) 5 (tta) 6 ]·8H 2 O ( FJSM‐BZA ) is introduced as a multifunctional porous layer at the SnO 2 /perovskite interface. By providing charge transport pathways and in situ suppression of lead leakage, this material simultaneously enhances device performance, stability, and environmental safety. Experimental results show that FJSM‐BZA suppresses the intrinsic defects of SnO 2 , optimizes the interface energy level alignment, enhances the built‐in electric field, and promotes charge extraction. At the same time, it significantly passivates defects in the perovskite layer and improves film quality. The introduction of FJSM‐BZA‐modified n‐i‐p devices ultimately achieved a power conversion efficiency (PCE) of 25.72% (0.09 cm 2 ). Unsealed modified devices maintained over 90% of their initial efficiency after 2000 h of aging in air or 600 h of continuous heating at 85 °C. Moreover, the unique lead adsorption mechanism exhibited by FJSM‐BZA effectively suppresses lead leakage, thereby enhancing the environmental safety of PSCs. This study provides a new strategy for the development of efficient, stable, and environmentally friendly PSCs.