Effect of orientation of the cation CH3NH3on exciton’s mobility in CH3NH3PbI3

We investigated the effect of the orientation of the cation MA (i.e., CH3NH3) on exciton’s mobility in the hybrid material MAPbI3using the density functional theory. We calculated the effect of such an orientation on the lattice parameters, band structure, density of states, and electric conductivity. The latter was calculated using the Boltzmann transport equation in the relaxation time approximation as a function of the chemical potential. It is compared with the conductivity of the centrosymmetric material CsPbI3to highlight the role played by MA in MAPbI3. Particularly, the conductivity in the latter is anisotropic, showing a pronounced enhancement along the direction of the dipolar moment of MA. Applications could take advantage of this result if they are made in a polarized phase. Our findings agree with experimental data for MAPbI3under the effect of an external electric field.