Publication date: 21st July 2025
State-of-the-art perovskite solar cells often rely on toxic solvents and inert-atmosphere processing, limiting scalability and adding cost. Here, we demonstrate the scalable fabrication of high-quality FAPbI₃ perovskite films by slot-die coating using dimethyl sulfoxide (DMSO) as a green solvent. Controlling crystallization of FAPbI₃ in DMSO remains challenging due to strong solvent–lead halide coordination, which typically results in poor morphology and high defect densities. We address this by incorporating an optimal concentration of Cs to stabilize the cubic phase, together with functional organic ligands that tune the rheological properties of the ink, regulate film growth, passivate grain-boundary defects, and improve interfacial energetics. Remarkably, uniform perovskite layers were deposited on PEDOT:PSS-coated ITO substrates under ambient air (relative humidity ~25%), without the need for a glovebox. Devices with a p–i–n architecture achieved power conversion efficiencies up to 13%. Beyond efficiency gains, the ligand-assisted strategy markedly enhanced stability by suppressing ion migration and moisture-induced degradation. This combined solvent and interface engineering approach provides a scalable and environmentally friendly pathway toward stable, high-performance perovskite photovoltaics.