Synergistic dual-layer passivation boosts efficiency and stability in perovskite solar cells using naphthol sulfonate

The performance and stability of perovskite solar cells (PSCs) are critically influenced by the interfacial properties between the perovskite absorption layer and the electron transport layer (ETL). This study introduces a novel interfacial engineering approach using dipotassium 7-hydroxynaphthalene-1,3-disulfonate (K-NDS) as a multifunctional passivator to enhance both the SnO₂ ETL and the perovskite absorber layer. The sulfonic acid groups (-SO₃^-) in K-NDS effectively fill oxygen vacancies on the SnO₂ surface, while the hydroxyl groups (-OH) passivate dangling bonds, improving the crystallinity of the perovskite film. Additionally, the diffusion of K⁺ from the SnO₂ ETL into the perovskite layer optimizes energy level alignment, thereby enhancing charge carrier extraction and transport. This bifacial passivation strategy has significantly improved both the power conversion efficiency (PCE) and long-term stability of PSCs. The modified devices achieved a champion PCE of 23.00% and an open-circuit voltage (<i>V</i>_OC) of 1.172 V. Furthermore, these devices maintained 75% of their initial PCE even after 1000 hours of storage under indoor environmental conditions. This work demonstrates the effectiveness of synergistic interfacial passivation in advancing the performance and durability of PSCs.