### Abstract

Lead halide perovskite semiconductors are soft, polar materials. The strong driving force for polaron formation (the dielectric electron-phonon coupling) is balanced by the light band effective masses, leading to a strongly-interacting large polaron. A first-principles prediction of mobility would help understand the fundamental mobility limits. Theories of mobility need to consider the polaron (rather than free-carrier) state due to the strong interactions. In this material we expect that at room temperature polar-optical phonon mode scattering will dominate and so limit mobility. We calculate the temperature-dependent polaron mobility of hybrid halide perovskites by variationally solving the Feynman polaron model with the finite-temperature free energies of Ōsaka. This model considers a simplified effective-mass band structure interacting with a continuum dielectric of characteristic response frequency. We parametrize the model fully from electronic-structure calculations. In methylammonium lead iodide at 300K we predict electron and hole mobilities of 133 and 94cm2V-1s-1, respectively. These are in acceptable agreement with single-crystal measurements, suggesting that the intrinsic limit of the polaron charge carrier state has been reached. Repercussions for hot-electron photoexcited states are discussed. As well as mobility, the model also exposes the dynamic structure of the polaron. This can be used to interpret impedance measurements of the charge-carrier state. We provide the phonon-drag mass renormalization and scattering time constants. These could be used as parameters for larger-scale device models and band-structure dependent mobility simulations.

Language | English |
---|---|

Article number | 195202 |

Journal | Physical Review B |

Volume | 96 |

Issue number | 19 |

DOIs | |

Status | Published - 7 Nov 2017 |

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### ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics

### Cite this

*Physical Review B*,

*96*(19), [195202]. https://doi.org/10.1103/PhysRevB.96.195202

**Calculating polaron mobility in halide perovskites.** / Frost, Jarvist Moore.

Research output: Contribution to journal › Article

*Physical Review B*, vol. 96, no. 19, 195202. https://doi.org/10.1103/PhysRevB.96.195202

}

TY - JOUR

T1 - Calculating polaron mobility in halide perovskites

AU - Frost, Jarvist Moore

PY - 2017/11/7

Y1 - 2017/11/7

N2 - Lead halide perovskite semiconductors are soft, polar materials. The strong driving force for polaron formation (the dielectric electron-phonon coupling) is balanced by the light band effective masses, leading to a strongly-interacting large polaron. A first-principles prediction of mobility would help understand the fundamental mobility limits. Theories of mobility need to consider the polaron (rather than free-carrier) state due to the strong interactions. In this material we expect that at room temperature polar-optical phonon mode scattering will dominate and so limit mobility. We calculate the temperature-dependent polaron mobility of hybrid halide perovskites by variationally solving the Feynman polaron model with the finite-temperature free energies of Ōsaka. This model considers a simplified effective-mass band structure interacting with a continuum dielectric of characteristic response frequency. We parametrize the model fully from electronic-structure calculations. In methylammonium lead iodide at 300K we predict electron and hole mobilities of 133 and 94cm2V-1s-1, respectively. These are in acceptable agreement with single-crystal measurements, suggesting that the intrinsic limit of the polaron charge carrier state has been reached. Repercussions for hot-electron photoexcited states are discussed. As well as mobility, the model also exposes the dynamic structure of the polaron. This can be used to interpret impedance measurements of the charge-carrier state. We provide the phonon-drag mass renormalization and scattering time constants. These could be used as parameters for larger-scale device models and band-structure dependent mobility simulations.

AB - Lead halide perovskite semiconductors are soft, polar materials. The strong driving force for polaron formation (the dielectric electron-phonon coupling) is balanced by the light band effective masses, leading to a strongly-interacting large polaron. A first-principles prediction of mobility would help understand the fundamental mobility limits. Theories of mobility need to consider the polaron (rather than free-carrier) state due to the strong interactions. In this material we expect that at room temperature polar-optical phonon mode scattering will dominate and so limit mobility. We calculate the temperature-dependent polaron mobility of hybrid halide perovskites by variationally solving the Feynman polaron model with the finite-temperature free energies of Ōsaka. This model considers a simplified effective-mass band structure interacting with a continuum dielectric of characteristic response frequency. We parametrize the model fully from electronic-structure calculations. In methylammonium lead iodide at 300K we predict electron and hole mobilities of 133 and 94cm2V-1s-1, respectively. These are in acceptable agreement with single-crystal measurements, suggesting that the intrinsic limit of the polaron charge carrier state has been reached. Repercussions for hot-electron photoexcited states are discussed. As well as mobility, the model also exposes the dynamic structure of the polaron. This can be used to interpret impedance measurements of the charge-carrier state. We provide the phonon-drag mass renormalization and scattering time constants. These could be used as parameters for larger-scale device models and band-structure dependent mobility simulations.

UR - http://www.scopus.com/inward/record.url?scp=85038831299&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.96.195202

DO - 10.1103/PhysRevB.96.195202

M3 - Article

VL - 96

JO - Physical Review B : Condensed Matter and Materials Physics

T2 - Physical Review B : Condensed Matter and Materials Physics

JF - Physical Review B : Condensed Matter and Materials Physics

SN - 1098-0121

IS - 19

M1 - 195202

ER -