Electron mean-free-path filtering in Dirac material for improved thermoelectric performance
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Author(s)
Liu, Te Huan
Zhou, Jiawei
Li, Mingda
Ding, Zhiwei
Song, Qichen
Fu, Liang
Chen, Gang
Date Issued
January 2018
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Liu, Te-Huan et al. “Electron Mean-Free-Path Filtering in Dirac Material for Improved Thermoelectric Performance.” Proceedings of the National Academy of Sciences 115, 5 (January 2018): 879–884 © 2018 National Academy of Sciences
Version
Final published version
Abstract
Recent advancements in thermoelectric materials have largely benefited from various approaches, including band engineering and defect optimization, among which the nanostructuring technique presents a promising way to improve the thermoelectric figure of merit (zT) by means of reducing the characteristic length of the nanostructure, which relies on the belief that phonons’ mean free paths (MFPs) are typically much longer than electrons’. Pushing the nanostructure sizes down to the length scale dictated by electron MFPs, however, has hitherto been overlooked as it inevitably sacrifices electrical conduction. Here we report through ab initio simulations that Dirac material can overcome this limitation. The monotonically decreasing trend of the electron MFP allows filtering of long-MFP electrons that are detrimental to the Seebeck coefficient, leading to a dramatically enhanced power factor. Using SnTe as a material platform, we uncover this MFP filtering effect as arising from its unique nonparabolic Dirac band dispersion. Room-temperature zT can be enhanced by nearly a factor of 3 if one designs nanostructures with grain sizes of ∼10 nm. Our work broadens the scope of the nanostructuring approach for improving the thermoelectric performance, especially for materials with topologically nontrivial electronic dynamics. Keywords: Dirac material; electrom mean-free-path filtering; thermoelectrics; nanostructuring approach; electron-phonon interactions
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1073/PNAS.1715477115
