Synergistic Interface Engineering via a Dual-A-Site 1D Perovskite Bridge for Efficient All-Perovskite Tandems

The severe halide segregation and interfacial recombination in wide-bandgap perovskites fundamentally limit all-perovskite tandem solar cells. We address this by synthesizing a novel dual A-site 1D perovskite, i.e., (PDA)0.6(GUA)1.4Pb6I16, enabling to achieve simultaneous suppression of ion migration and interfacial recombination. First-principles calculations uncover the significant dual A-site cation orbital hybridization in the conduction band and I-dominated states at the valence band maximum, which facilitates efficient charge transfer. The engineered interface creates a hydrophobic surface with 56.3% reduced polarity while enhancing the built-in potential from 1.02 to 1.15 V, facilitating efficient charge extraction. These synergistic effects yield unprecedented device performance: WBG single-junction cells achieve 20.46% efficiency with 1.328 V VOC, while all-perovskite tandem cells deliver a efficiency of 28.43% with 2.079 V VOC. Most notably, the tandem devices maintain 80% initial efficiency after 1000 h of continuous operation, representing a breakthrough in stability that addresses the most critical barrier for practical applications.