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

ABSTRACT

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 Pb ²⁺ via sulfonate and N–H groups, while forming hydrogen bonds with organic cations. Notably, partial release of Cu ²⁺ triggers a reversible Cu ²⁺ /Cu ⁺ redox shuttle, which mitigates deep‐level Pb ⁰ /I ⁰ 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.