Abstract: The present disclosure relates to methods for making formamidinium lead iodide (FAPbI3). The methods comprise preparing a reaction mixture in various ways, including: (i) preparing a lead(ii) iodide suspension, wherein at least 90% of lead(ii) iodide is not dissolved and remains in solid state, followed by introducing formamidinium iodide to the suspension; (ii) mixing lead(ii) iodide and formamidinium iodide, followed by heating and cooling the solid mixture, which is then used to form a suspension with a liquid; or (iii) mixing a first precursor, which contains lead(ii) ions; a second precursor, which contains formamidinium ions; a third precursor, which contains iodide ions; and a liquid. The methods further comprise of heating the reaction mixture to a temperature greater than or equal to 40° C. and less than or equal to 190° C., followed by isolating formamidinium lead iodide product from the supernatant, and washing the product with a liquid.

Abstract: The present disclosure relates to a method for making formamidinium iodide compound. The method comprises mixing a first precursor, which contains formamidinium ions, with a first liquid (step (a)); mixing a second precursor, which contains iodide ions, and a second liquid (step (b)); preparing a reaction mixture (step (c)) by mixing the resulting mixture in step (a) with the resulting mixture in step (b); introducing a third liquid (step (d)) to the reaction mixture in step (c); mixing the reaction mixture (step (e)); collecting the solution which contains formamidinium iodide product (step (f)); and isolating formamidinium iodide product by removing solvents in the product solution (step (g)).