Buried‑Interface Seeded Bottom‑Up Growth for Universal High‑Efficiency p–i–n Perovskites

Oriented crystallization is critical for high performance and stability in inverted (p–i–n) perovskite solar cells, yet practical routes to precisely regulate this process remain limited. We introduce a co‐assembled monolayer (Co‐SAM) of MeO‐2PACz and pyrophosphoric acid (PA) that densifies packing on ITO and converts the buried contact into an active nucleation scaffold. Strong PA‐PbI 2 coordination enables the formation of interfacial seeds for α‐phase nuclei, directing interface‐initiated nucleation and bottom‐up phase conversion. The resulting films exhibit continuous, void‐free coverage, large high‐crystallinity grains, fewer residual intermediates and grain boundaries. Furthermore, the Co‐SAM optimizes energy‐level alignment and chemical passivation at the hole‐extract interface. This versatile strategy is successfully demonstrated across diverse inverted perovskite formulations, delivering high power conversion efficiencies (PCEs) with a champion value of 26.37%, and 25.07% for a 1 cm 2 device. Additionally, the Co‐SAM‐based devices demonstrate exceptional operational durability, retaining over 95% of their initial efficiency after 1500 h of continuous maximum power point tracking.