Electron–Phonon Coupling and Polaron Mobility in Hybrid Perovskites from First Principles

Abstract

Density functional theory electronic structures, maximally localized Wannier funcitons and linear response theory are used to compute the electron and hole mobility, μ, 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 cm2 V–1 s–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 μ, which is a strong indication of polaronic transport in these compounds. Our work then offers an independent theoretical validation of the many hypotheses about the polaronic nature of the charge carriers in lead halide perovskites.