In recent years, halide perovskite (HaPs) materials have become one of the most promising photovoltaic materials due to their unique crystal structure and their carrier diffusion and migration properties. However, the unusual nature of the carriers in HaPs does not conform to conventional transport models indicating a lack of understanding of the underlying transport mechanism. Our work utilizes a combination of the path-integral molecular dynamics (PIMD) method and the ring polymer molecular dynamics (RPMD) approach to provide an atomic-level picture of the coupled electronic and nuclear motions during charge transport in HaPs. PIMD is a way to obtain exact quantum statistical results from the classical molecular simulation trajectories, while RPMD utilizes the path integral formalism to model the real-time dynamics. Using PIMD, we are able to compare the ensemble of nuclear configurations with and without an excess electron to identify which nuclear modes couple most strongly to a photo-excited charge. Furthermore, we use RPMD to examine the coupled dynamical motion of the excess electron and nuclei. These simulations allow us to directly calculate the charge mobility, which we find to be in good agreement with the experiment in terms of both the magnitude and temperature dependence in contrast to predictions using conventional transport models.

Path-integral molecular dynamics simulation approach for charge transport dynamics in halide perovskites

ACS Spring Meeting 2021

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