Defect-Immune Perovskite Photovoltaics via Molecular Vise Engineering: A Pathway to Scalable, Encapsulation-Free Production under Mild Conditions

The interfacial defects induced by halide ion migration critically limit the performance scalability of solution-processed perovskite solar cells (PSCs). Here, we demonstrate an engineering strategy using zwitterionic potassium hydrogen phthalate (KHP). This approach synergistically regulates crystallization dynamics and passivates multidimensional defects via atomic-scale interface anchoring. Time-resolved AFM characterization reveals that the amphiphilic KHP, with C═O/Pb²⁺ coordination capability, induces self-assembled boundary confinement during perovskite crystallization, generating ultrasmooth films with 68% reduced surface roughness (average roughness (R_a) = 62 nm vs control 112 nm). Multinuclear (¹H/²⁰⁷Pb) NMR analyses decipher the dual-anchoring mechanism, where KHP coordinates Pb²⁺ via carboxyl oxygen (²⁰⁷Pb upfield shift Δδ = 1020 ppm, [PbI₆]^4- → [PbI₅(OOCR)]^3-) while forming NH₃···HOOC^- hydrogen bonds with the hydrogen phthalate anion (HP^-) (2D COSY J-coupling at 7.95 ppm), synergistically immobilizing halides through this molecular vise effect as corroborated by XPS-derived Pb²⁺ reduction (Pb 4f_7/2 peak shift of 1.25 eV). The dual passivation mechanism involving both Pb defects and halide vacancies enables a record PCE of 6.17% for air-processed low-cost PSCs, achieving absolute efficiency enhancement over the baseline. Herein, ambient-air fabricated perovskite solar cells via zwitterion-mediated interface anchoring achieve 6.17% efficiency and 71.12% stability (360 h), with enhanced moisture resistance (contact angle: 31° → 59°), enabling scalable low-cost production under noninert conditions.