Figure 1. Fast band picture of excitons in MAPbX₃.

Left: GW₀ band structure of MAPbX₃ in the pseudo-cubic phase, with X = I (red), Br (blue) and Cl (green) determined by Wannier interpolation⁶⁴ from a calculation using 4 × 4 × 4 k-points. The band gaps at R are indicated in eV. The dashed lines in the background are the corresponding DFT+scissor band structures. Right: Zoom-in of the band structure (marked by the dotted lines) close to the R point. The radii of the circles represent the contribution of the e-h pair at that k-point () to the first exciton wave function.