Intrinsic Limits of Charge Carrier Mobilities in Layered Halide Perovskites
arxiv(2024)
摘要
Layered halide perovskites have emerged as potential alternatives to
three-dimensional halide perovskites due to their improved stability and larger
material phase space, allowing fine-tuning of structural, electronic, and
optical properties. However, their charge carrier mobilities are significantly
smaller than that of three-dimensional halide perovskites, which has a
considerable impact on their application in optoelectronic devices. Here, we
employ state-of-the-art ab initio approaches to unveil the electron-phonon
mechanisms responsible for the diminished transport properties of layered
halide perovskites. Starting from a prototypical ABX_3 halide perovskite,
we model the case of n=1 and n=2 layered structures and compare their
electronic and transport properties to the three-dimensional reference. The
electronic and phononic properties are investigated within density functional
theory (DFT) and density functional perturbation theory (DFPT), while transport
properties are obtained via the ab initio Boltzmann transport equation. The
vibrational modes contributing to charge carrier scattering are investigated
and associated with polar-phonon scattering mechanisms arising from the
long-range Fröhlich coupling and deformation potential scattering processes.
Our investigation reveals that the lower mobilities in layered systems
primarily originates from the increased electronic density of states at the
vicinity of the band edges, while the electron-phonon coupling strength remains
similar. Such increase is caused by the dimensionality reduction and the break
in octahedra connectivity along the stacking direction. Our findings provide a
fundamental understanding of the electron-phonon coupling mechanisms in layered
perovskites and highlight the intrinsic limitations of the charge carrier
transport in these materials.
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