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The influence of non-idealities on the thermoelectric power factor of nanostructured superlattices
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Thesberg, Mischa, Pourfath, Mahdi, Kosina, Hans and Neophytou, Neophytos (2015) The influence of non-idealities on the thermoelectric power factor of nanostructured superlattices. Journal of Applied Physics, 118 (22). 224301. doi:10.1063/1.4936839
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Official URL: http://dx.doi.org/10.1063/1.4936839
Abstract
Cross-plane superlattices composed of nanoscale layers of alternating potential wells and barriers have attracted great attention for their potential to provide thermoelectric power factor improvements and higher ZT figure of merit. Previous theoretical works have shown that the presence of optimized potential barriers could provide improvements to the Seebeck coefficient through carrier energy filtering, which improves the power factor by up to 40%. However, experimental corroboration of this prediction has been extremely scant. In this work, we employ quantum mechanical electronic transport simulations to outline the detrimental effects of random variation, imperfections, and non-optimal barrier shapes in a superlattice geometry on these predicted power factor improvements. Thus, we aim to assess either the robustness or the fragility of these theoretical gains in the face of the types of variation one would find in real material systems. We show that these power factor improvements are relatively robust against: overly thick barriers, diffusion of barriers into the body of the wells, and random fluctuations in barrier spacing and width. However, notably, we discover that extremely thin barriers and random fluctuation in barrier heights by as little as 10% is sufficient to entirely destroy any power factor benefits of the optimized geometry. Our results could provide performance optimization routes for nanostructured thermoelectrics and elucidate the reasons why significant power factor improvements are not commonly realized in superlattices, despite theoretical predictions.
| Item Type: | Journal Article | ||||||||
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| Subjects: | Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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| Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | ||||||||
| Library of Congress Subject Headings (LCSH): | Thermoelectricity , Thermoelectric materials, Superlattices as materials, Nanoscience , Nanotechnology | ||||||||
| Journal or Publication Title: | Journal of Applied Physics | ||||||||
| Publisher: | American Institute of Physics | ||||||||
| ISSN: | 0021-8979 | ||||||||
| Official Date: | 8 December 2015 | ||||||||
| Dates: |
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| Volume: | 118 | ||||||||
| Number: | 22 | ||||||||
| Article Number: | 224301 | ||||||||
| DOI: | 10.1063/1.4936839 | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||
| Funder: | Fonds zur FoĢrderung der Wissenschaftlichen Forschung (Austria) (FWF) | ||||||||
| Grant number: | P25368-N30 |
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