Calculating polaron mobility in halide perovskites
By Jarvist Moore Frost. 2017
158 citations recorded by the source corpus.
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 parametrise the model fully from electronic-structure calculations. In methylammonium lead iodide at 300 K we predict electron and hole mobilities of 133 and 94 cm^2/V/s 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 photo-excited 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-renormalisation, and scattering time constants. These could be used as parameters for larger-scale device models and band-structure dependent mobility simulations.
Subfields: Electrical and Electronic Engineering, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/11f79af6bdec4394f3eaeee49a8ab476e51e5e68
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Citations in the corpus
- Large polarons in lead halide perovskites (2017, background): “Our results also agree with similar treatments by Sendner et al. (47), who estimated an average electron/hole polaron mobility in CH3NH3PbBr3 of me-h ~ 158 cm 2V−1 s−1 for a polaron radius of 4.3 nm and by Frost (48) who calculated electron and hole polaron mobilities in CH3NH3PbI3 of 136 and 94 cm ”