Process for the preparation of perovskite-based inks

A process for preparing a perovskite-based ink, said comprising a perovskite of 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), a molar ratio between said at least one ammonium salt having the general formula (II) and said at least one ammonium salt having the general formula (III) is comprised between 0:100 and 50:50.