Theoretical Description of the Electron-Lattice Interaction in Molecular and Magnetic Crystals

Mozafari, Elham

doi:10.3384/diss.diva-130517

Cited by 3 publications

(3 citation statements)

References 130 publications

(207 reference statements)

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“…The susceptibility is determined by a phonon dispersion relationship only in the limit of zero temperature, and generally reflects the correlations within the effective polar displacement field . Consistent with the Coulombic pseudopotentials used in the MD simulations, we take the coupling between the charges and the lattice to be linear and described by a Fröhlich-like interaction, where λ is a Fröhlich coupling constant. The lattice variables can be integrated out, leaving a Gaussian approximation to the partition function, , where is the partition function for a displacement field without couplings to the charges.…”

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Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

2022

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We use path integral molecular dynamics simulations and theory to elucidate the interactions between charge carriers, as mediated by a lead halide perovskite lattice. We find that the charge− lattice coupling of MAPbI 3 results in a repulsive interaction between electrons and holes at intermediate distances. The effective interaction is understood using a Gaussian field theory, whereby the underlying soft, polar lattice contributes a nonlocal screening between quasiparticles. Path integral calculations of this nonlocal screening model are used to rationalize the small exciton binding energy and low radiative recombination rate observed experimentally and are compared to traditional Wannier−Mott and Froḧlich models, which fail to do so. These results clarify the origin of the high power conversion efficiencies in lead halide perovskites. Emergent repulsive electron−hole interactions provide a design principle for optimizing soft, polar semiconductors.

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“…and described by a Froḧlich-like interaction, 47 where λ is a Froḧlich coupling constant. The lattice variables can be integrated out, leaving a Gaussian approximation to the partition function, G ,…”

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confidence: 99%

Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

2022

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“…and described by a Fröhlich-like interaction, 46 where λ is a Fröhlich coupling constant. The lattice variables can be integrated out, leaving a Gaussian approximation to the partition function, Z G ,…”

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Nonlocal screening dictates the radiative lifetimes of excitations in lead halide perovskites

Park¹,

Obliger²,

Limmer³

2021

Preprint

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We use path integral molecular dynamics simulations and theory to elucidate the interactions between charge carriers, as mediated by a lead halide perovskite lattice. We find that the charge-lattice coupling of MAPbI3 results in a repulsive interaction between electrons and holes at intermediate distances. The effective interaction is understood using a Gaussian field theory, whereby the underlying soft, polar lattice contributes a nonlocal screening between quasiparticles. Path integral calculations of this nonlocal screening model are used to rationalize the small exciton binding energy and low radiative recombination rate observed experimentally and are compared to traditional Wannier-Mott and Fröhlich models, which fail to do so. These results clarify the origin of the high power conversion efficiencies in lead halide perovskites. Emergent repulsive electron-hole interactions provide a design principle for optimizing soft, polar semiconductors.

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Renormalization of excitonic properties by polar phonons

Park

Limmer

2022

The Journal of Chemical Physics

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We employ quasiparticle path integral molecular dynamics to study how theexcitonic properties of model semiconductors are altered by electron-phononcoupling. We describe ways within a path integral representation of the systemto evaluate the renormalized mass, binding energy, and radiative recombinationrate of excitons in the presence of a fluctuating lattice. To illustrate thisapproach, we consider Fr\"ohlich-type electron-phonon interactions and employan imaginary time influence functional to incorporate phonon-induced effectswithout approximation. The effective mass and binding energies are comparedwith perturbative and variational approaches, which provide qualitativelyconsistent trends. We evaluate electron-hole recombination rates as mediatedthrough both trap-assisted and bimolecular processes, developing a consistentstatistical mechanical approach valid in the reaction limited regime. Thesecalculations demonstrate how phonons screen electron-hole interactions,generically reducing exciton binding energies and increasing their radiativelifetimes.

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Theoretical Description of the Electron-Lattice Interaction in Molecular and Magnetic Crystals

Cited by 3 publications

References 130 publications

Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

Nonlocal screening dictates the radiative lifetimes of excitations in lead halide perovskites

Renormalization of excitonic properties by polar phonons

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