Electron-phonon coupling and polaron mobility in hybrid perovskites from first-principles

Density functional theory electronic structures, maximally localized Wannier funcitons and linear response theory are used to compute the electron and hole mobility of both inorganic, Cs-containing, and hybrid, CH₃NH₃-containing, lead bromide perovskites. When only phonon scattering is considered we find hole mobilities at room temperature in the 40-180~cm²V^-1s^-1 range, in good agreement with experimental data for highly-ordered crystals. The electron mobility is about an order of magnitude larger, because low-energy phonons are ineffective over the Pb 6p shell. Most importantly, our parameter-free approach, finds a T^-3/2 power-law temperature dependence of the mobility, which is a strong indication of polaronic transport. Our work then offers an independent theoretical validation of the many hypotheses about the polaronic nature of the charge carriers in lead halide perovskites.