Dual-functional Interface Engineering with Picolinamide for Improved MAPbI _{3– <i>x</i>} Cl _<i>x</i> Perovskite Solar Cells

This study investigates the impact of picolinamide (PA) as an interfacial modifier on the properties of MAPbI_3-<i>x</i>Cl_<i>x</i> perovskite films and their photovoltaic applications. Inverted perovskite solar cells (PSCs) based on MAPbI_3-<i>x</i>Cl_<i>x</i> often suffer from high defect density and energy-level misalignment, leading to nonradiative recombination and inefficient charge extraction. We introduced PA as an ultrathin interlayer, where its pyridine nitrogen and amide groups interact with Pb²⁺ and I^- to passivate defects and optimize energy-level alignment. The PA-modified devices achieved a champion power conversion efficiency (PCE) of 19.35%, representing a 23.01% enhancement over the control. Additionally, PA improved the film's hydrophobicity, effectively inhibiting ion migration and moisture penetration. Consequently, unencapsulated devices maintained over 80% of their initial PCE after 180 days in a nitrogen atmosphere and 360 h under ambient conditions, demonstrating excellent long-term stability. This work provides a promising strategy for optimizing perovskite solar cells.