Process for the preparation of perovskite-based inks

A process for preparing a perovskite-based ink, said perovskite having general formula (I):

• wherein y is a number comprised between 0 and 0.2;
• the process including the following steps:
• (a) dissolving lead iodide (PbI2) in at least one organic solvent selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), γ-butyrolactone (GBL), or mixtures thereof, obtaining a first solution;
• (b) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula (II):
• wherein R represents a linear or branched C1-C4 alkyl group, in a part of said first solution obtained in step (a), obtaining a second solution;
• (c) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula (III):
• wherein R represents a linear or branched C1-C4 alkyl group, in a part of said first solution obtained in step (a), obtaining a third solution;
• (d) mixing said second solution obtained in step (b) with said third solution obtained in step (c), obtaining a perovskite-based ink;
• wherein in said step (d), the molar ratio between said at least one ammonium salt having general formula (II) and said at least one ammonium salt having general formula (III) is comprised between 0:100 and 50:50.