Hot Carrier Filtering in Solution Processed Heterostructures: A Paradigm for Improving Thermoelectric Efficiency

Zhang, Yichi; Bahk, Je‐Hyeong; Lee, Joun; Birkel, Christina S.; Snedaker, Matthew L.; Liu, Deyu; Zeng, Hongmei; Moskovits, Martin; Shakouri, Ali; Stucky, Galen D.

doi:10.1002/adma.201304419

Cited by 64 publications

(56 citation statements)

References 29 publications

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“…Even if nanoinclusions may yield more predictable filtering barriers than grain boundaries, 75 a system featuring only grain boundaries might give a more pure signal of filtering which is easier to interpret.…”

Section: à3mentioning

confidence: 99%

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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Section: à3mentioning

confidence: 99%

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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“…[28,29] The exclusive increase of E def for CB in Te-MS can be interpreted as the consequence of the significant band bending of CB, whereas no remarkable change in VB is expected. [13][14][15][16][17] Indeed, in spite of the enhanced S and μ H characters, the temperature dependences of σ, μ H , and n C does not change considerably in Te-MS compared to those of MS. [13][14][15][16][17] Indeed, in spite of the enhanced S and μ H characters, the temperature dependences of σ, μ H , and n C does not change considerably in Te-MS compared to those of MS.…”

Section: Doi: 101002/aenm201800065mentioning

confidence: 99%

Effect of Dislocation Arrays at Grain Boundaries on Electronic Transport Properties of Bismuth Antimony Telluride: Unified Strategy for High Thermoelectric Performance

Hwang

Kim

et al. 2018

Advanced Energy Materials

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Harnessing individual electronic and thermal transport properties selectively has long been a fundamental goal of achieving high thermoelectric (TE) performance in many materials. TE energy conversion efficiency of materials is directly proportional to the material-dependent parameter as known as a dimensionless figure of merit, zT. In principle, twofold intercorrelated relations of physical parameters i) between electrical conductivity (σ) and Seebeck coefficient (S) and ii) between σ and total thermal conductivity (κ total ) in TE semiconductors are strongly correlated each other and the trade-offs have been major obstacles for improving zT, which is determined by zT = S 2 σ T/κ total where T is temperature and κ total consists of the sum of electronic (κ elec ) and lattice (κ latt ) contributions to thermal conductivity.Many efforts have been demonstrated to overcome these long historic cliché issues on thermoelectrics. Concerning about electronic transports, several distinct strategies have been proposed for exclusively enhancing power factor (PF: S 2 σ) by utilizing resonance state in Tl-doped p-type PbTe, [1,2] the convergence of electronic bands, [3] and the doping modulation in nanocomposites. [4] However, these approaches are not widely applicable to all TE materials since the enhancement of PF through such strategies utterly depends on the unique electronic band structure of the individual material. Apart from the optimization of PF, remarkable enhancements of the zT have been achieved mostly due to the reduction of the κ latt via increased phonon scattering utilizing structural defects in nanostructured materials, such as grain boundaries, interfaces, dislocations, and precipitates. [4][5][6][7] Further, efforts to find a new material with intrinsically low thermal conductivity have been devoted. [8][9][10] In fact, little room remains for further reducing κ latt in nanostructured single-phase materials because κ latt cannot be reduced below the amorphous limit, which has been already achieved in the state-of-the-art nanostructured TE materials. Moreover, it has been widely recognized that κ elec cannot be decoupled from σ. However, there is a possibility to reduce the κ elec value by decreasing Lorenz number (L) since L is a band structure-dependent parameter of material but relatively Taming electronic and thermal transport properties is the ultimate goal in the quest to achieve unprecedentedly high performance in thermoelectric (TE) materials. Most state-of-the-art TE materials are inherently narrow bandgap semiconductors, which have an inevitable contribution from minority carriers, concurrently decreasing Seebeck coefficient and increasing thermal conductivity. Nevertheless, the restraint control of minority carrier transport is seldom considered as a key element to enhance the TE figure of merit (zT). Herein, it is verified that the localized dislocation arrays at grain boundaries enable the suppression of minority carrier contribution to electronic transport properties, resulting in an increase ...

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“…Both models agree only when this ratio is low. More specifically, interface effects such as electron filtering (able to increase the thermopower in specific cases 21,26,27 ), or the influence of thermoelectric effects on both the electrical resistivity and thermal conductivity (that may trigger peculiar phenomena close to the percolation threshold 25 ) are not taken into account. 5, the WJC model reproduces well the steep decrease followed by a plateau.…”

Section: Webman-jortner-cohen (Wjc) Model For the Thermopowermentioning

confidence: 99%

Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass–crystal composite system Si₁₀As₁₅Te₇₅–Bi_0.4Sb_1.6Te₃

et al. 2015

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Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass-crystal composite system Si 10 As 15 Te 75 -Bi 0.4 Sb 1.6 Te 3 † We report on the theoretical predictions of the effective medium theory (EMT) and its generalized version taking into account percolation theory (GEMT) on the thermoelectric properties of composites based on Landauer and Sonntag's equations. The results were tested experimentally on composites composed of the glassy phase Si 10 As 15 Te 75 and the crystalline phase Bi 0.4 Sb 1.7 Te 3 . The evolution of the electrical resistivity and thermal conductivity with the fraction of crystalline phase matches very well the experimental data, although the GEMT model fails to predict the thermopower. A better agreement between theory and experiment could be obtained by combining the principles of the GEMT and the Webman-Jortner-Cohen models. Despite the fact that the GEMT model originally predicts the possibility to optimize the dimensionless figure of merit ZT of composites by adjusting the fraction and the values of the transport properties of each phase, the new model developed rules out any beneficial influence on the ZT values. These results confirm within a different framework the early conclusions of Bergman regarding the impossibility of improving the ZT values using multi-phased materials.

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Hot Carrier Filtering in Solution Processed Heterostructures: A Paradigm for Improving Thermoelectric Efficiency

Cited by 64 publications

References 29 publications

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

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

Effect of Dislocation Arrays at Grain Boundaries on Electronic Transport Properties of Bismuth Antimony Telluride: Unified Strategy for High Thermoelectric Performance

Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass–crystal composite system Si₁₀As₁₅Te₇₅–Bi_0.4Sb_1.6Te₃

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Hot Carrier Filtering in Solution Processed Heterostructures: A Paradigm for Improving Thermoelectric Efficiency

Cited by 64 publications

References 29 publications

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

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

Effect of Dislocation Arrays at Grain Boundaries on Electronic Transport Properties of Bismuth Antimony Telluride: Unified Strategy for High Thermoelectric Performance

Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass–crystal composite system Si10As15Te75–Bi0.4Sb1.6Te3

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Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass–crystal composite system Si₁₀As₁₅Te₇₅–Bi_0.4Sb_1.6Te₃