Effect of NiTe Nanoinclusions on Thermoelectric Properties of Bi2Te3

Sumithra, S.; Takas, Nathan J.; Nolting, Westly; Sapkota, Sanshrut; Poudeu, Pierre F. P.; Stokes, Kevin L.

doi:10.1007/s11664-012-2003-z

Cited by 15 publications

(15 citation statements)

References 15 publications

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“…Nanoinclusions essentially introduce mostly potential barriers (or wells sometimes) or regular or irregular shapes and sizes, of scattered centers in the material matrix. In most experimental observations, a small improvement in the Seebeck coefficient is observed, along with a larger reduction in the electrical conductivity, such that the power factor is slightly reduced [186][187][188][189][190][191][192]. The effect on the PF, however, is typically smaller compared to the reduction of the thermal conductivity, such that ZT typically increases [186,187,190,193].…”

Section: Nanoinclusions Voids and The Power Factormentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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The field of thermoelectric materials has undergone a revolutionary transformation over the last couple of decades as a result of the ability to nanostructure and synthesize myriads of materials and their alloys. The ZT figure of merit, which quantifies the performance of a thermoelectric material has more than doubled after decades of inactivity, reaching values larger than two, consistently across materials and temperatures. Central to this ZT improvement is the drastic reduction in the material thermal conductivity due to the scattering of phonons on the numerous interfaces, boundaries, dislocations, point defects, phases, etc., which are purposely included. In these new generation of nanostructured materials, phonon scattering centers of different sizes and geometrical configurations (atomic, nano- and macro-scale) are formed, which are able to scatter phonons of mean-free-paths across the spectrum. Beyond thermal conductivity reductions, ideas are beginning to emerge on how to use similar hierarchical nanostructuring to achieve power factor improvements. Ways that relax the adverse interdependence of the electrical conductivity and Seebeck coefficient are targeted, which allows power factor improvements. For this, elegant designs are required, that utilize for instance non-uniformities in the underlying nanostructured geometry, non-uniformities in the dopant distribution, or potential barriers that form at boundaries between materials. A few recent reports, both theoretical and experimental, indicate that extremely high power factor values can be achieved, even for the same geometries that also provide ultra-low thermal conductivities. Despite the experimental complications that can arise in having the required control in nanostructure realization, in this colloquium, we aim to demonstrate, mostly theoretically, that it is a very promising path worth exploring. We review the most promising recent developments for nanostructures that target power factor improvements and present a series of design ‘ingredients’ necessary to reach high power factors. Finally, we emphasize the importance of theory and transport simulations for materialoptimization, and elaborate on the insight one can obtain from computational tools routinely used in the electronic device communities. Graphical abstract

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Section: Nanoinclusions Voids and The Power Factormentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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“…In this system, B atoms act as 0-D defects, i.e., dopants, to contribute charge carriers; grain boundaries act as 2-D defects; and Si grains are 3-D defects. The synergy of defects with different dimensionality greatly enhances the TE performance: charge carriers that donated from dopants flow irreversibly into the host matrix, the mobility is largely retained because the host matrix contains fewer point defects, Electron microscope images of defects observed in Bi2Te3: (e) 0-D Cu dopants [9], (f) 1-D dislocations [10], (g) 2-D grain boundaries [11], (h) 3-D NiTe nanoinclusions [12]. and the final electrical conductivity could be higher than the conductivity of both of the components separately.…”

Section: Cross-dimensional Defect Engineeringmentioning

confidence: 99%

Towards higher thermoelectric performance of Bi2Te3 via defect engineering

2016

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“…An important direction in the context of electronic engineering to enhance the performance of nanostructured thermoelectric generators [1][2][3][4][5][6][7][8][9][10] , is to utilize the physics of electronic energy filtering through nanoscale barriers and nanoinclusions [11][12][13][14][15][16][17][18][19][20][21][22][23][24] . To put it simply, energy filtering aims to provide a unidirectional flow of electrons from the hot contact to the cold contact while prohibiting the reverse flow of electrons, which occurs typically when lower energy electrons are scattered off due to the interface potentials 9,[20][21][22]25 .…”

Section: Introductionmentioning

confidence: 99%

Incoherent scattering can favorably influence energy filtering in nanostructured thermoelectrics

Singha

Muralidharan

2017

Sci Rep

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Investigating in detail the physics of energy filtering through a single planar energy barrier in nanostructured thermoelectric generators, we reinforce the non-trivial result that the anticipated enhancement in generated power at a given efficiency via energy filtering is a characteristic of systems dominated by incoherent scattering and is absent in ballistic devices. In such cases, assuming an energy dependent relaxation time τ(E) = kE r, we show that there exists a minimum value r min beyond which generation can be enhanced by embedding nanobarriers. For bulk generators with embedded nanobarriers, we delve into the details of inter sub-band scattering and show that it has finite contribution to the enhancement in generation. We subsequently discuss the realistic aspects, such as the effect of smooth transmission cut-off and show that for r > r min, the optimized energy barrier is just sufficiently wide enough to scatter off low energy electrons, a very wide barrier being detrimental to the performance. Analysis of the obtained results should provide general design guidelines for enhancement in thermoelectric generation via energy filtering. Our non-equilibrium approach is typically valid in the absence of local quasi-equilibrium and hence sets the stage for future advancements in thermoelectric device analysis, for example, Peltier cooling near a barrier interface.

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Effect of NiTe Nanoinclusions on Thermoelectric Properties of Bi2Te3

Cited by 15 publications

References 15 publications

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Towards higher thermoelectric performance of Bi2Te3 via defect engineering

Incoherent scattering can favorably influence energy filtering in nanostructured thermoelectrics

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