Tween-80-Assisted Surface Recrystallization Strategy for Blade-Coated Perovskite Solar Cells with Enhanced Device Performance

Blade-coated FAPbI3 films enable scalable PSCs but suffer from uncontrolled crystallization, impairing performance. We introduce a viscous nonionic surfactant, Tween-80 (polyoxyethylene 20 sorbitan monooleate, Mw = 428.6), to induce vertical recrystallization on the upper surface of FAPbI3 films. We find that the abundant hydroxyl (–OH) groups in Tween-80 can coordinate with Pb2+ and FA+ in the perovskite lattice, facilitating secondary nucleation and oriented crystal growth. Notably, surfactants with long alkyl chains and hydroxyl groups are known to strongly tune the perovskite crystallinity. This treatment yields FAPbI3 films with vertically aligned grains and a more oriented microstructure. As a result, small-area PSCs achieve a champion power conversion efficiency (PCE) of 23.29%. Furthermore, these devices exhibit operational stability, retaining 97.82% and 91.48% of their initial PCE after 1800 h of aging under N2 conditions (O2, H2O <0.1 ppm) and atmospheric conditions (30 ± 5% RH, 25 °C), respectively. Notably, large-area devices with a total area of 7 × 7 cm2 (aperture area of 21 cm2) deliver a high PCE of 19.71%, demonstrating excellent compatibility with scalable fabrication. This work provides a simple and effective surface recrystallization strategy for producing high-quality, vertically oriented FAPbI3 films for industrial-scale PSC applications.