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Organohalide lead perovskites have revolutionized the scenario of emerging photovoltaic technologies. The prototype MAPbI₃ perovskite (MA = CH₃NH₃⁺) has dominated the field, despite only harvesting photons above 750 nm (∼1.6 eV). Intensive research efforts are being devoted to find new perovskites with red-shifted absorption onset, along with good charge transport properties. Recently, a new perovskite based on the formamidinium cation ((NH₂)₂CH⁺ = FA) has shown potentially superior properties in terms of band gap and charge transport compared to MAPbI₃. The results have been interpreted in terms of the cation size, with the larger FA cation expectedly delivering reduced band-gaps in Pb-based perovskites. To provide a full understanding of the interplay among size, structure, and organic/inorganic interactions in determining the properties of APbI₃ perovskites, in view of designing new materials …