Multiple Types of Defect Passivation Using a Pyridine Derivative Modifier for Efficient and Stable Perovskite Solar Cells

The defect formation energy of perovskites is low, and ions can easily migrate and evaporate during annealing and usage. Here, we introduce 5-aminopyridine-2-carboxylic acid (5-APA) for modifying the perovskite layer to enhance the device efficiency and stability. The pyridine N and carbonyl (C═O) can form strong anchoring effects with uncoordinated Pb²⁺, effectively suppressing nonradiative recombination. Simultaneously, the amino group (−NH₂) forms hydrogen bonds with the organic cations in the perovskite film and can bind with V_MA and V_FA vacancies, thereby significantly enhancing the stability of the device. After surface modification, the crystallinity of the perovskite film was significantly improved, and the energy level alignment with C₆₀ is optimized. Specifically, the V_OC of the modified device increases from 1.09 to 1.17 V, and the PCE reaches 24.19%. After aging for 1000 h at 85 °C in a nitrogen atmosphere, the stability of the modified device remains at 81%, while the unmodified device retains only 51%. Additionally, sunlight aging in the air was simulated for 30 days. The stability of the modified device is 82%, compared to only 52% for the unmodified device. Our findings fully demonstrate the significant effect of multifunctional pyridine derivative surface modification in enhancing the efficiency and stability of perovskite solar cells.