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Thermoelectric power factor of nanocomposite materials from two-dimensional quantum transport simulations
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Foster, Samuel, Thesberg, Mischa and Neophytou, Neophytos (2017) Thermoelectric power factor of nanocomposite materials from two-dimensional quantum transport simulations. Physical Review B (Condensed Matter and Materials Physics), 96 (19). 195425. doi:10.1103/PhysRevB.96.195425 ISSN 1098-0121.
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Official URL: http://dx.doi.org/10.1103/PhysRevB.96.195425
Abstract
Nanocomposites are promising candidates for the next generation of thermoelectric materials since they exhibit extremely low thermal conductivities as a result of phonon scattering on the boundaries of the various material phases. The nanoinclusions, however, should not degrade the thermoelectric power factor, and ideally should increase it, so that benefits to the ZT figure of merit can be achieved. In this work we employ the nonequilibrium Green's function quantum transport method to calculate the electronic and thermoelectric coefficients of materials embedded with nanoinclusions. For computational effectiveness we consider two-dimensional nanoribbon geometries, however, the method includes the details of geometry, electron-phonon interactions, quantization, tunneling, and the ballistic to diffusive nature of transport, all combined in a unified approach. This makes it a convenient and accurate way to understand electronic and thermoelectric transport in nanomaterials, beyond semiclassical approximations, and beyond approximations that deal with the complexities of the geometry. We show that the presence of nanoinclusions within a matrix material offers opportunities for only weak energy filtering, significantly lower in comparison to superlattices, and thus only moderate power factor improvements. However, we describe how such nanocomposites can be optimized to limit degradation in the thermoelectric power factor and elaborate on the conditions that achieve the aforementioned mild improvements. Importantly, we show that under certain conditions, the power factor is independent of the density of nanoinclusions, meaning that materials with large nanoinclusion densities which provide very low thermal conductivities can also retain large power factors and result in large ZT figures of merit.
Item Type: | Journal Article | |||||||||
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Subjects: | T Technology > TA Engineering (General). Civil engineering (General) | |||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | |||||||||
Library of Congress Subject Headings (LCSH): | Nanocomposites (Materials), Thermoelectricity | |||||||||
Journal or Publication Title: | Physical Review B (Condensed Matter and Materials Physics) | |||||||||
Publisher: | American Physical Society | |||||||||
ISSN: | 1098-0121 | |||||||||
Official Date: | 17 November 2017 | |||||||||
Dates: |
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Volume: | 96 | |||||||||
Number: | 19 | |||||||||
Article Number: | 195425 | |||||||||
DOI: | 10.1103/PhysRevB.96.195425 | |||||||||
Status: | Peer Reviewed | |||||||||
Publication Status: | Published | |||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||
Date of first compliant deposit: | 23 November 2017 | |||||||||
Date of first compliant Open Access: | 24 November 2017 | |||||||||
RIOXX Funder/Project Grant: |
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