Anti‐Solvent‐Free Fabrication of Stable FA0.9Cs0.1PbI3 Perovskite Solar Cells with Efficiency Exceeding 24.0% through a Naphthalene‐Based Passivator

Abstract The anti‐solvent‐free fabrication of high‐efficiency perovskite solar cells (PSCs) holds immense significance for the transition from laboratory‐scale to large‐scale commercial applications. However, the device performance is severely hindered by the increased occurrence of surface defects resulting from the lack of control over nucleation and crystallization of perovskite using anti‐solvent methods. In this study, 2‐(naphthalen‐2‐yl)ethylamine hydriodide (NEAI) is employed as the surface passivator for perovskite films without using any anti‐solvent. Naphthalene demonstrates strong π‐π conjugation, which aids in the efficient extraction of charge carriers. Additionally, the naphthalene‐ring moieties form a tight attachment to the perovskite surface. After NEAI treatment, FA and I vacancies are selectively occupied by NEA + and I − in NEAI respectively, thus effectively passivating the surface defects and isolating the surface from moisture. Ultimately, the optimized NEAI‐treated device achieves a promising power conversion efficiency (PCE) of 24.19% (with a certified efficiency of 23.94%), featuring a high fill factor of 83.53%. It stands out as one of the reported high PCEs achieved for PSCs using the spin‐coating technique without the need for any anti‐solvent so far. Furthermore, the NEAI‐treated device can maintain ≈87% of its initial PCE after 2000 h in ambient air with a relative humidity of 30% ± 5%.