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

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, methylammonium lead tribromide (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>MAPbBr</a:mi><a:mn>3</a:mn></a:msub></a:math>) and methylammonium lead triiodide (<b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>MAPbI</b:mi><b:mn>3</b:mn></b:msub></b:math>), 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 <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mi>p</c:mi><c:mi>p</c:mi><c:mi>π</c:mi></c:mrow></c:math> channel as a critical bottleneck for charge transport and to provide insights into the differences between electron and hole transport across the two materials.