Dual‐SAM/Al ₂ O ₃ ‐Nanoparticles Hole‐Selective Stack With BCP/PEAI Passivation Enabling High Performance Inverted Perovskite Solar Cells

While hole‐selective self‐assembled monolayers (SAMs) serve as pivotal components for high‐performance inverted perovskite solar cells (PSCs), conventional single‐layer SAM architectures struggle to reconcile efficient carrier extraction and superior device stability simultaneously. Herein, we rationally design a dual‐interface architecture featuring alumina nanoparticles (Al 2 O 3 ‐NPs) between two phosphonic acid‐based SAMs. The embedded Al 2 O 3 ‐NPs not only effectively seal pinholes within the bottom SAM but also construct robust Al‐O‐P bridging linkages with the upper SAM, enabling a higher effective work function, balanced charge transport, and significantly suppressed non‐radiative recombination. In parallel, a BCP/PEAI bilayer overlayer passivates surface defects at the perovskite interface and reinforces electron extraction through favorable π‐π stacking interactions. In parallel, a BCP/PEAI bilayer overlayer passivates surface defects at the perovskite interface and reinforces electron extraction through favorable π–π stacking interactions. Consequently, the optimized inverted PSCs yield a champion PCE of 25.13% with a fill factor of 82.6%, accompanied by negligible hysteresis and 73.8% PCE retention after 2700 h of ambient storage. This work provides a dual‐interface molecular engineering strategy toward highly efficient and stable perovskite solar cells.