Charge Transport in Hybrid Halide Perovskites

TL;DR

This paper presents a theoretical model based on large polarons to explain charge transport in hybrid halide perovskites, highlighting the roles of acoustic phonons and temperature-dependent dielectric properties, thereby resolving existing controversies.

Contribution

It introduces a novel polaron-based model that incorporates acoustic phonon scattering and dielectric effects to better understand charge mobility in perovskites.

Findings

Acoustic phonons, not optical phonons, dominate polaron scattering.

Temperature dependence of mobility is explained by dielectric function.

Model resolves key controversies in charge transport literature.

Abstract

Charge transport is crucial to the performance of hybrid halide perovskite solar cells. A theoretical model based on large polarons is proposed to elucidate charge transport properties in the perovskites. Critical new physical insights are incorporated into the model, including the recognitions that acoustic phonons as opposed to optical phonons are responsible for the scattering of the polarons; these acoustic phonons are fully excited due to the "softness" of the perovskites, and the temperature-dependent dielectric function underlies the temperature dependence of charge carrier mobility. This work resolves key controversies in literature and forms a starting point for more rigorous first-principles predictions of charge transport.