Expanding the Solvent Library for Halide Perovskites via Amine Additives

Processing halide perovskites from solution is central to their development in optoelectronic devices, yet their solubility has traditionally been limited to a narrow set of solvents. Here, we demonstrate that primary alkylamine (RNH2) additives can greatly expand the solvent space. By screening 24 unconventional solvent systems, including nitriles, sulfites, carbonates, and others, we identify 13 that dissolve perovskite precursors (MAI and PbI2) in the presence of amine additives. Using acetonitrile (ACN) as a model system, we show that amines promote dissolution through Pb-coordination, while excess amine induces the deprotonation of methylammonium (MA) cations, directing the formation of 2D Ruddlesden–Popper (RP) perovskite phases. Robot-assisted precipitation and thin-film deposition experiments validate our theoretical predictions, revealing a systematic shift toward lower-n RP phases with an increasing amine amount. This work presents alternative solvent systems and provides mechanistic insights into amine-assisted perovskite processing, offering opportunities for sustainable device fabrication.