Al 2 O 3 ‐Based Bilateral Anchoring Strategy Enables Efficient and Stable Inverted Perovskite Solar Cells

NiO x is widely used as a hole transport layer (HTL) in inverted perovskite solar cells (PSCs) owing to its low cost, high transparency, and excellent chemical stability. However, high surface trap‐state densities and poor interfacial contact limit further power conversion efficiency (PCE) improvements. Although Al 2 O 3 passivation partially fills surface defects and suppresses ion diffusion, energy‐level misalignment and nonradiative recombination at the buried interface still restrict carrier dynamics. Self‐assembled monolayers (SAMs) show promise for mitigating these losses through favorable energy‐level alignment and efficient charge transport. Nevertheless, forming thermodynamically stable, continuous SAMs on rough NiO x remains challenging because hydrophobic groups create physical voids that aggravate charge recombination. To address this, we develop a multilayer interfacial engineering strategy based on Al 2 O 3 ‐bilaterally‐anchored SAMs. The bottom Al 2 O 3 layer physically fills microscopic grooves on NiO x , creating a flat nanoscale platform that improves SAM density and molecular order. Meanwhile, the top Al 2 O 3 layer modulates surface free energy, enhances wettability, and blocks defect diffusion and detrimental side reactions. This bilateral anchoring strategy simultaneously boosts the open‐circuit voltage ( V oc ) and PCE, providing a viable route to efficient and stable inverted PSCs.