Calculating polaron mobility in halide perovskites
Calculating polaron mobility in halide perovskites
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DOI：
10.1103/physrevb.96.195202
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发表时间：
2017-11-07
影响因子：
3.7
通讯作者：
Frost, Jarvist Moore
中科院分区：
文献类型：
--
作者：
Frost, Jarvist Moore
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 Osaka. 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 300 K we predict electron and hole mobilities of 133 and 94 cm(2) V-1 s(-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.
