Analysis of real-space transport channels for electrons and holes in halide perovskites

TL;DR

This paper investigates how real-space transport channels influence charge carrier mobility in halide perovskites, highlighting the roles of on-site energies and spin-orbit coupling in electron and hole transport mechanisms.

Contribution

It introduces a dynamic disorder model analyzing orbital occupations to understand charge transport, emphasizing the impact of material-specific parameters on mobility.

Findings

On-site energies and SOC significantly affect orbital occupation dynamics.

Energy gaps and halide SOC strength govern transport channel filling.

The $pp\pi$ channel is identified as a key bottleneck for charge transport.

Abstract

Predicting and explaining charge carrier transport in halide perovskites is a formidable challenge because of the unusual vibrational and electron-phonon coupling properties of these materials. This study explores charge carrier transport in two prototypical halide perovskite materials, MAPbBr$_3$ and MAPbI$_3$, using a dynamic disorder model. Focusing on the role of real-space transport channels, we analyze temporal orbital occupations to assess the impact of material-specific on-site energy levels and spin-orbit coupling (SOC) strengths. Our findings reveal that both on-site energies and SOC magnitude significantly influence the orbital occupation dynamics, thereby affecting charge dispersal and carrier mobility. In particular, energy gaps across on-site levels and the halide SOC strength govern the filling of transport channels over time. This leads us to identify the $pp\pi$ channel as a critical bottleneck for charge transport and to provide insights into the differences between electron and hole transport across the two materials.