In Situ Copper Ions Redox Engineering Elevates Hole Transport for Efficient Perovskite Solar Cells

Interfacial non-radiative recombination and energy-level mismatch remain critical bottlenecks for perovskite solar cells (PSCs). Here, we reported an in situ redox engineering strategy using a cobweb-like quadrangular macrocyclic copper-organic complex, Cu(II) meso-tetra(4-sulfonatophenyl) porphine [Cu(TSPPa)₂], to simultaneously achieve defect passivation and enhanced hole transport at the perovskite/hole transport layer interface. Benefiting from its lattice-matching macrocyclic structure, Cu(TSPPa)₂ infiltrates grain boundaries and anchors undercoordinated Pb²⁺ via sulfonate and N-H groups, while forming hydrogen bonds with organic cations. Notably, partial release of Cu²⁺ triggers a reversible Cu²⁺/Cu⁺ redox shuttle, which mitigates deep-level Pb⁰/I⁰ defects and generates p-type CuI in situ, smoothing the interfacial energy barrier and boosting hole extraction. This multifunctional modification yields a champion power conversion efficiency of 26.32% with negligible hysteresis, along with significantly enhanced operational, thermal, and ambient stability. Our work demonstrates a paradigm of leveraging metal-ion redox chemistry in metal-organic complexes for synergistic interfacial engineering in high-performance PSCs.