Synergistic Dual‐Passivation of Grain Boundaries and Buried Interface for High‐Efficiency and Stable Perovskite Solar Cells

The interlayer contact issue in perovskite devices is a primary source of defect generation and a major constraint on grain and interface optimization. While promoting high‐quality crystal growth and repairing interface defects are both viable pathways, these processes are often addressed separately. Here, we propose that a synergistic strategy, employing dual additives, can concurrently fulfill both objectives. Here, we report a synergistic dual‐passivation approach combining N, N‐dimethyldipropyltriamine (DMDPTF) treatment of the perovskite with cobalt acetate (Co(OAc) 2 ) modification of the SnO 2 electron transport layer. This dual passivation not only mitigates interfacial recombination but also induces an enhanced crystallization to form an optimized interlayer contact. The resulting devices achieved power conversion efficiencies (PCEs) of 25.41% (0.096 cm 2 n‐i‐p), with p‐i‐n devices reaching 26.41% (0.096 cm 2 ) and 22.18% (10.04 cm 2 module). Unencapsulated devices exhibit exceptional stability, retaining 99% of initial performance for 2448 h under dark storage.