Dynamic self-regulating interfaces enable crystallization control and lead sequestration in perovskite photovoltaics

Carbon-electrode, hole-transport-layer-free perovskite solar cells (C-PSCs) offer compelling commercialization potential but suffer from uncontrolled crystallization, leading to defective films and severe non-radiative losses. Current interfacial modifications passively form adducts, failing to kinetically regulate crystallization. This work pioneers a dynamic, self-regulating interface strategy using nickel acetate (NA). NA enables in situ generation of a Pb²⁺ complex reservoir via reversible ion exchange (PbI₂ + Ni(CH₃COO)₂ ⇌ Pb(CH₃COO)₂ + NiI₂). The controlled Pb²⁺ release from the complex reservoir uniquely achieves dual functionality: it kinetically suppresses nucleation for large-grained films while simultaneously passivating interfacial defects. This synergistic action, coupled with optimized energy-level alignment, yields significantly enhanced charge extraction. Consequently, NA-modified C-PSCs achieve a record power conversion efficiency (PCE) of 18.43% (vs. 14.11% for the control) with exceptional operational stability. Crucially, the synergistic action of chemical bonding in the insoluble Pb-Ni complex and the physical barrier formed by the NiO_x layer during annealing drastically reduces lead leakage, establishing a dual-function paradigm for highly efficient, stable, and eco-compatible perovskite photovoltaics.