Table 1.

Band-structure parameters for orthorhombic MAPbI₃.

Parameter	Value	Source
Kane energy $E_p$	13.884 eV	This work
Tetragonal CF $\delta$	349.8 meV	This work
Orthorhombic CF $\zeta$	147.7 meV	This work
Luttinger’s magnetic parameter $\kappa$	0.206	This work

Using the expressions in Supplementary Table 1 of Supplementary Note 1, the Kane energy, $E_p$, the crystal field parameters $\delta$ and $\zeta$ and Luttinger’s magnetic parameter $\kappa$ are uniquely determined by measurement of the electron and hole g-factors along two directions. The measured values are taken as $g_Z^h=-\mid g_{\left[001\right]}^h\mid$ =  −0.28; $g_{\left[1\overline{1}0\right]}^h=-0.57$ for the holes, $g_Z^e=g_{\left[001\right]}^e=2.52$ and $g_{\left[1\overline{1}0\right]}^e=2.63$. For these calculations, the bandgap, $E_g$, is taken as 1.65 eV corresponding to the measured exciton energy and the SOC parameter $\mathrm{\Delta }=1.4$ eV from ref. ²⁴. The calculated g-factor values match the experimental values.