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

2017-09-11T21:54:12Z (GMT) by Carlo Motta Stefano Sanvito
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, CH<sub>3</sub>NH<sub>3</sub>-containing, lead bromide perovskites. When only phonon scattering is considered we find hole mobilities at room temperature in the 40-180~cm<sup>2</sup>V<sup>-1</sup>s<sup>-1</sup> 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 6<i>p</i> shell. Most importantly, our parameter-free approach, finds a <i>T</i><sup>-3/2</sup> 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.