Stabilizing Ni³⁺-Rich NiO_x/Perovskite Interface via Dual Coordination for Efficient and Durable Perovskite...

While nickel oxide (NiO_x) is widely employed as an efficient hole-transport material, the surface Ni³⁺ 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 Ni³⁺-rich NiO_x/perovskite interface through dual coordination. Two oxopyridines in porphyrin act as hard Lewis bases that coordinate with hard-acidic Ni³⁺ sites on NiO_x, while the other two interact with Pb²⁺ 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 cm²) and 21.8% (21.54 cm² 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 Ni³⁺ in NiO_x and support high-efficiency, long-lived perovskite solar cells.