Molecular Bridge Regulation of Buried Interface in Perovskite Solar Cells

ABSTRACT Defects at the buried interface represent a critical challenge that impedes further improvements in both the performance and scalable manufacturing of perovskite solar cells (PSCs). Defect formation, lattice mismatch, and energy‐level misalignment at this interface aggravate nonradiative recombination and accelerate photothermal degradation, thereby limiting both efficiency and operational stability. Here, we employ interface engineering using multifunctional molecules to suppress defect formation. To minimize redundant material screening, we combine theoretical calculations with experimental validation to identify 4‐aminobutylphosphonic acid (4‐ABPA) for modifying the interface between the perovskite layer and the electrode. Both simulation and experimental results demonstrate 4‐ABPA as a multifunctional molecular bridge that simultaneously anchors to the charge transport layer and interacts with the perovskite lattice. And its role in dynamically regulating perovskite crystallization and enhancing interfacial performance is uncovered. The dual‐site chemical binding regulates crystallization, alleviates residual stress, suppresses interfacial defects, and optimizes energy‐level alignment at the buried interface. As a result, voltage loss is reduced to 31 mV, enabling power conversion efficiencies of 25.56% in n–i–p and 26.45% in p–i–n architectures with negligible hysteresis. The modified devices also exhibit outstanding durability, retaining 83.91% of their initial performance under 1440 h of continuous operation and 91.59% after 2600 h of ambient storage. Our work establishes a systematic and universal buried‐interface engineering strategy to further enhance efficiency and stability, thereby advancing the mass production of perovskite devices.