| Download | - View final version: From soft harmonic phonons to fast relaxational dynamics in CH₃NH₃PbBr₃ (PDF, 1.5 MiB)
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| DOI | Resolve DOI: https://doi.org/10.1103/PhysRevB.92.100303 |
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| Author | Search for: Swainson, I. P.1; Search for: Stock, C.; Search for: Parker, S. F.; Search for: Van eijck, L.; Search for: Russina, M.; Search for: Taylor, J. W. |
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| Affiliation | - National Research Council of Canada. Security and Disruptive Technologies
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| Format | Text, Article |
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| Abstract | The lead-halide perovskites, including CH₃NH₃PbBr₃, are components in cost effective, highly efficient photovoltaics, where the interactions of the molecular cations with the inorganic framework are suggested to influence the electronic and ferroelectric properties. CH₃NH₃PbBr₃ undergoes a series of structural transitions associated with orientational order of the CH₃NH₃ (methylammonium) molecular cation and tilting of the PbBr₃ host framework. We apply high-resolution neutron scattering to study the soft harmonic phonons associated with these transitions, and find a strong coupling between the PbBr₃ framework and the quasistatic CH₃NH₃ dynamics at low energy transfers. At higher energy transfers, we observe a PbBr₆ octahedra soft mode driving a transition at 150 K from bound molecular excitations at low temperatures to relatively fast relaxational excitations that extend up to ∼50–100 meV. We suggest that these temporally overdamped dynamics enables possible indirect band gap processes in these materials that are related to the enhanced photovoltaic properties. |
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| Publication date | 2015-09-08 |
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| Publisher | APS (American Physical Society) |
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| In | |
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| Language | English |
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| Peer reviewed | Yes |
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| NPARC number | 23001091 |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | 61d159a0-142f-4034-84f5-a57067be0b89 |
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| Record created | 2016-12-12 |
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| Record modified | 2020-06-02 |
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