Stabilizing Ni ³⁺ ‐Rich NiO _x /Perovskite Interface via Dual Coordination for Efficient and Durable Perovskite Photovoltaics

ABSTRACT While nickel oxide (NiO _x ) is widely employed as an efficient hole‐transport material, the surface Ni ³⁺ species required for effective transport are unstable and can drive unfavorable interfacial reactions with the perovskite layer. Herein, we introduce a tetraoxopyridine‐functionalized porphyrin molecule to stabilize a Ni ³⁺ ‐rich NiO _x /perovskite interface through dual coordination. Two oxopyridines in porphyrin act as hard Lewis bases that coordinate with hard‐acidic Ni ³⁺ sites on NiO _x , while the other two interact with Pb ²⁺ in the perovskite lattice. Such a situation reduces interface defect formation, slows degradation, and helps maintain film integrity, while the conjugated porphyrin macrocycle promotes efficient hole extraction. Devices with the modified NiO _x reach the champion efficiency of 27.05% (0.062 cm ² ) and 21.8% (21.54 cm ² aperture area), retaining >95% of the initial efficiency after 2000 h of continuous 1‐sun operation at the maximum power point. This work establishes a robust molecular‐engineering route to stabilize surface Ni ³⁺ in NiO _x and support high‐efficiency, long‐lived perovskite solar cells.