Low-Dimensional Thermoelectricity

Heremans, Joseph P.

doi:10.12693/aphyspola.108.609

Cited by 146 publications

(91 citation statements)

References 50 publications

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“…This variation can be explained by the jump in electrical conductivity, due to the fact that electrical conductivity and Seebeck coefficient are inversely proportional to each other [33,34]. Since the GNP samples are less electrical conductive than the solid counterpart, only the most excited electron is able to move between the conductive pathways, which result in a higher Seebeck coefficient.…”

Section: Seebeck Coefficient Measurementmentioning

confidence: 99%

Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Sun

Terakita

Tseng

et al. 2015

Smart Mater. Struct.

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Always cite the published version, so the author(s) will receive recognition through services that track citation counts, e.g. Scopus. If you need to cite the page number of the author manuscript from TSpace because you cannot access the published version, then cite the TSpace version in addition to the published version using the permanent URI (handle) found on the record page. Abstract. Thermoelectric effect is defined as the revisable translation between thermal and electrical energy. In this paper, we investigate the properties of p-type poly(vinylidene fluoride) (PVDF) based polymer composite foams that can be used in next generation energy harvesting applications. The composites were created via continuous melt blending method. Multi-walled carbon nanotubes (MWCNTs) and graphene nano-platelets (GNPs) were used as secondary phases to strengthen the electrical conductivity of the composites. Foam structures were later generated via super-critical carbon dioxide saturation method. We study the material properties between solid and foam samples; the results indicate a dramatic increase in overall thermoelectric properties for GNP foamed samples. We also report at least an order decreased in thermal conductivity which is in favor of thermoelectric effect. An unexpected drop in electrical conductivity was observed after the foaming process and can be explained by large volumetric expansion of the foam. Finally we report the Seebeck coefficient for both types of composite foams: 11 μV/K for 5 wt% MWCNT/PVDF foam and 58 μV/K for 15 wt% GNP/PVDF foam. IntroductionThermoelectric (TE) effect is known as the direct conversion between electrical and thermal energy and such effect can be explained by three different phenomena: Seebeck effect, Peliter effect, and Thomson effect. When a temperature gradient is applied to a circuit that consists of two different electric conductors, a small current can be observed which is called the Seebeck effect. The opposite phenomenon is called the Peliter effect, of which the junctions of the two conductors may either absorb or release heat when a voltage is supplied to the circuit. Lastly, the Thomson Effect states that when an electric current is passing through a conductor, certain amount of heat (Thomson heat) would be released or absorbed by the material and such heat is does not include the non-reversible Joule heating which is generated from the electric resistance nature of the material [1]. Seebeck effect is currently being implemented in verity types of temperature sensors or thermocouples [2] while the Peliter effect can be applied in different types of heat engines and coolers [3]. Other than temperature sensors, Seebeck effect also being widely researched for energy harvesting

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Section: Seebeck Coefficient Measurementmentioning

confidence: 99%

Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Sun

Terakita

Tseng

et al. 2015

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…11 These papers gave rise to a great drive towards the synthesis of materials exhbiting a reduction of dimensionality, [12][13][14] by trapping electrons either in superlattices, for instance PbTe/Pb 1−x Eu x Te 15 and Bi 2 Te 3 /Sb 2 Te 3 , 16 or in the interface between two compounds, such as TiO 2 and SrTiO 3 . 17 The basic idea is to increase the density of state (DOS) near the band edge in order to boost the power factor.…”

Section: Introductionmentioning

confidence: 99%

Boosting the power factor with resonant states: A model study

et al. 2017

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A particularly promising pathway to enhance the efficiency of thermoelectric materials lies in the use of resonant states, as suggested by experimentalists and theorists alike. In this paper, we go over the mechanisms used in the literature to explain how resonant levels affect the thermoelectric properties, and we suggest that the effects of hybridization are crucial yet ill-understood. In order to get a good grasp of the physical picture and to draw guidelines for thermoelectric enhancement, we use a tight-binding model containing a conduction band hybridized with a flat band. We find that the conductivity is suppressed in a wide energy range near the resonance, but that the Seebeck coefficient can be boosted for strong enough hybridization, thus allowing for a significant increase of the power factor. The Seebeck coefficient can also display a sign change as the Fermi level crosses the resonance. Our results suggest that in order to boost the power factor, the hybridization strength must not be too low, the resonant level must not be too close to the conduction (or valence) band edge, and the Fermi level must be located around, but not inside, the resonant peak.

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“…A quasisuppression of the thermal conductivity has been found in bismuth nanowires, but its origin is still debated [2]. Measurements made on thin films [18][19][20] and nanowires [2,[21][22][23][24][25], most of which are semiconducting, have yielded widely scattered values, preventing a deep understanding of the mechanisms at play in nanostructures [2]. A theoretical determination of the nanostructuring effect on the lattice thermal conductivity (LTC) of bismuth has thus become mandatory.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale mechanisms for the reduction of heat transport in bismuth

et al. 2016

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Hand-on routes to reduce lattice thermal conductivity (LTC) in bismuth have been explored by employing a combination of Boltzmann's transport equation and ab initio calculations of phonon-phonon interaction within the density functional perturbation theory. We have first obtained the temperature dependence of the bulk LTC in excellent agreement with available experiments. A very accurate microscopic description of heat transport has been achieved and the electronic contribution to thermal conductivity has been determined. By controlling the interplay between phonon-phonon interaction and phonon scattering by sample boundaries, we predict the effect of size reduction for various temperatures and nanostructure shapes. The largest heat transport reduction is obtained in polycrystals with grain sizes smaller than 100 nm.

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Low-Dimensional Thermoelectricity

Cited by 146 publications

References 50 publications

Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Boosting the power factor with resonant states: A model study

Nanoscale mechanisms for the reduction of heat transport in bismuth

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