Figure 2. Densities of states for methylammonium lead iodide (MAPbI₃) and formamidinium tin bromide (FASnBr₃), showing contributions from the organic cation and the inorganic sublattice.

The band edges are spanned by metal and halogen states, with the cation having only minor hybridization. The inset shows the shallow DOS (‘funnel’) near the VBM, characteristic for tin-based compounds, and shallow DOS near the CBM, typical of Pb-based compounds (see text for details).