Cation Role in Structural and Electronic Properties of 3D Organic-Inorganic Halide Perovskites: A DFT Analysis

Moving from a general revise of the structural and electronic properties of the 3D methylammoniumtrihalogenoplumbates (MAPbX(3), X = Cl, Br, I) class of halide organic-inorganic perovskites, we have focused our attention on the organic cation and studied the role it plays in the electronic/optical features of this class of compounds, paying attention mainly to the iodide compound. We found good agreement with previous experimental works, but at the same time we observed that the bare inorganic network [PbX3](-) does not fully take into account the electronic properties of 3D systems. A comparison is performed between the electronic properties of MAPbI(3) organic-inorganic perovsldte and those of the purely inorganic CsPbI3. Furthermore, we show that hybrid methods applied on top of the spin-orbit calculated structures are not able to open the bandgap sufficiently to reproduce the experimental value, revealing the need of further and more computationally demanding procedures to get improved agreement.