Electron energy filtering by a nonplanar potential to enhance the thermoelectric power factor in bulk materials

Bahk, Je‐Hyeong; Bian, Zhixi; Shakouri, Ali

doi:10.1103/physrevb.87.075204

Cited by 178 publications

(150 citation statements)

References 29 publications

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“…(3) at 300∼700K, increasing with the increase temperature. Moreover, based on the Boltzmann transport equations under the relaxation time approximation, the optimal cut-off (barrier height difference) energy level that maximizes the power factor is calculated to be a few k B T above the Fermi level of the matrix, 17 a range that our calculated ∆E B coincidentally falls in, which also supports the proposed energy filtration mechanism.…”

Section: Resultssupporting

confidence: 55%

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

et al. 2015

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We report on a greatly enhanced power factor for 1%PbS-nanoparticle-embedded TiS2 bulk ceramic, about 1 mW/(mK2) at 300 K and 1.23 mW/(mK2) in a wide temperature range of 573 ∼ 673 K, of which the latter is among the highest so far for TiS2-based thermoelectric materials. Compared to TiS2, the power factor is increased by ∼110% at 300 K and (50 ∼ 35)% at 573 ∼ 673 K. This enhancement is derived from a large increase in Seebeck coefficient which overwhelmed the modest degradation of electrical conductivity, which should be attributed to energy filtering induced by the band gap offset between TiS2 and PbS.

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Section: Resultssupporting

confidence: 55%

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

et al. 2015

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“…According to theoretical considerations, energy filtering can arise from extended barriers such as heterostructures, nanocomposites, nanoinclusions, or grain boundaries. [9][10][11][12][13][15][16][17] A. Electronic structure calculations…”

Section: Theorymentioning

confidence: 99%

“…13 Whereas filtering may be appropriate as a crude model of the scattering or trapping caused by extended energy barriers such as grain boundaries, 7,12,70 energy-dependent expressions are better suited to account for scattering by charged impurities such as acceptors or even charged nanoinclusions. 13 In Figure 3, we compare the Seebeck coefficient as a function of temperature for different Hall carrier concentrations and different scattering/filtering accounts. In the upper panel, we compare the Seebeck coefficient for constant scattering time with energy-dependent scattering following Equation (2) with s ¼ 1/2 and 3/2.…”

Section: Potential Of Energy Filtering For Znsbmentioning

confidence: 99%

“…By introducing potential barriers or strongly energy-dependent scattering mechanisms, low-energetic carriers can be blocked, greatly enhancing the Seebeck coefficient. 7,[9][10][11][12][13][14][15][16][17][18] ZnSb has been known as a thermoelectric material for a long time. 19 When Caillat reported a figure of merit of 1.4 for Zn 4 Sb 3 in 1997, that composition got the most attention due to the remarkably low thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%

“…32 Our hypothesis was that such processing could introduce energy filtering from grain boundaries or nanoinclusions associated with grain boundaries. 13,15,17 The transport properties of these samples were then compared to the theoretical predictions with and without energy filtering. This paper is organized as follows: First, a brief description of the sample preparation and experimental methods are provided.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of thermoelectric properties by energy filtering: Theoretical potential and experimental reality in nanostructured ZnSb

Berland

Song

Carvalho

et al. 2016

Journal of Applied Physics

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Energy filtering has been suggested by many authors as a means to improve thermoelectric properties. The idea is to filter away low-energy charge carriers in order to increase Seebeck coefficient without compromising electronic conductivity. This concept was investigated in the present paper for a specific material (ZnSb) by a combination of first-principles atomic-scale calculations, Boltzmann transport theory, and experimental studies of the same system. The potential of filtering in this material was first quantified, and it was as an example found that the power factor could be enhanced by an order of magnitude when the filter barrier height was 0.5 eV. Measured values of the Hall carrier concentration in bulk ZnSb were then used to calibrate the transport calculations, and nanostructured ZnSb with average grain size around 70 nm was processed to achieve filtering as suggested previously in the literature. Various scattering mechanisms were employed in the transport calculations and compared with the measured transport properties in nanostructured ZnSb as a function of temperature. Reasonable correspondence between theory and experiment could be achieved when a combination of constant lifetime scattering and energy filtering with a 0.25 eV barrier was employed. However, the difference between bulk and nanostructured samples was not sufficient to justify the introduction of an energy filtering mechanism. The reasons for this and possibilities to achieve filtering were discussed in the paper.

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Recent Advances on Mg ₂ X ^IV Based Thermoelectric Materials: A Theoretical Approach

Yelgel

2019

Advanced Thermoelectric Materials

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Electron energy filtering by a nonplanar potential to enhance the thermoelectric power factor in bulk materials

Cited by 178 publications

References 29 publications

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

Enhancement of thermoelectric properties by energy filtering: Theoretical potential and experimental reality in nanostructured ZnSb

Recent Advances on Mg ₂ X ^IV Based Thermoelectric Materials: A Theoretical Approach

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Electron energy filtering by a nonplanar potential to enhance the thermoelectric power factor in bulk materials

Cited by 178 publications

References 29 publications

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS2

Enhancement of thermoelectric properties by energy filtering: Theoretical potential and experimental reality in nanostructured ZnSb

Recent Advances on Mg 2 X IV Based Thermoelectric Materials: A Theoretical Approach

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Recent Advances on Mg ₂ X ^IV Based Thermoelectric Materials: A Theoretical Approach