Acoustic phonon lifetimes limit thermal transport in methylammonium lead iodide
[1];
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[7]
- Department of Chemistry, Stanford University, Stanford, CA 94305,, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025,
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899,
- Department of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom,
- Department of Chemistry, Stanford University, Stanford, CA 94305,
- Department of Physics, King’s College London, London WC2R 2LS, United Kingdom,
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom,, Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025,
Hybrid organic-inorganic perovskites (HOIPs) have become an important class of semiconductors for solar cells and other optoelectronic applications. Electron-phonon coupling plays a critical role in all optoelectronic devices, and although the lattice dynamics and phonon frequencies of HOIPs have been well studied, little attention has been given to phonon lifetimes. We report high-precision momentum - resolved measurements of acoustic phonon lifetimes in the hybrid perovskite methylammonium lead iodide ( MAPI ), using inelastic neutron spectroscopy to provide high energy resolution and fully deuterated single crystals to reduce incoherent scattering from hydrogen. Our measurements reveal extremely short lifetimes on the order of picoseconds, corresponding to nanometer mean free paths and demonstrating that acoustic phonons are unable to dissipate heat efficiently. Lattice-dynamics calculations using ab-initio third-order perturbation theory indicate that the short lifetimes stem from strong three-phonon interactions and a high density of low-energy optical phonon modes related to the degrees of freedom of the organic cation. Such short lifetimes have significant implications for electron-phonon coupling in MAPI and other HOIPs, with direct impacts on optoelectronic devices both in the cooling of hot carriers and in the transport and recombination of band edge carriers. These findings illustrate a fundamental difference between HOIPs and conventional photovoltaic semiconductors and demonstrate the importance of understanding lattice dynamics in the effort to develop metal halide perovskite optoelectronic devices.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1481042
- Alternate ID(s):
- OSTI ID: 1480457
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 115 Journal Issue: 47; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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