Core–shell nanostructures introduce multiple potential barriers to enhance energy filtering for the improvement of the thermoelectric properties of SnTe

Ma, Zheng; Wang, Chao; Lei, Jingdan; De, Zhang; Chen, Yanqun; Wang, Yuanxu; Wang, Jianli; Cheng, Zhenxiang

doi:10.1039/c9nr09331a

Cited by 47 publications

(53 citation statements)

References 65 publications

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“…lowered the energy separation between heavy and light hole valence bands,which eventually resulted in increased S. In addition to that, carrier energy filtering effect can also enhance S substantially in SnTe. [33,34] To inhibit the phonon propagation, nanoprecipitates of CdS, [35] HgTe, [32] Cu 1.75 Se, [36] MnTe, [21] Cu 2 Te [37] etc.a nd layered intergrowth Sn m Sb 2n Te 3n+m nanostructure [38] have been embedded in the SnTem atrix. A significantly suppressed k lat has been demonstrated by inducing ferroelectric instability in SnTevia Ge alloying.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Band Convergence and Ultra‐Low Thermal Conductivity Lead to High Thermoelectric Performance in SnTe

2021

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SnTe, as tructural analogue of champion thermoelectric (TE) material PbTe, has recently attracted wide attention for TE energy conversion. Herein, we demonstrate ac o-doping strategy to improve the TE performance of SnTe via simultaneous modulation of electronic structure and phonon transport. The electrical transport is optimizedb y 3mol %A gd oping in self-compensated SnTe( i.e., Sn 1.03 Te). Further,Mgdoping in SnAg 0.03 Te resulted in highly converged valence bands,w hich enhanced the Seebeck coefficient markedly.T he energy gap between two uppermost valence bands (DE v )decreases to 0.10 eV in Sn 0.92 Ag 0.03 Mg 0.08 Te compared to 0.35 eV in pristine SnTe. The optimizedp-type carrier concentration and highly converged valence bands gave ahigh power factor of ca. 27 mWcm À1 K À2 at 865 Ki nS n 0.92 Ag 0.03 Mg 0.08 Te. The lattice thermal conductivity of Sn 0.92 Ag 0.03 Mg 0.08 Te reached to an ultra-low value of % 0.23 Wm À1 K À1 at 865 Kd ue to the formation of MgTen anoprecipitates in SnTem atrix. These combined effects resulted in ah igh TE figure of merit, zT % 1.55 at 865 Ki nSn 0.92 Ag 0.03 Mg 0.08 Te.

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Section: Introductionmentioning

confidence: 99%

Enhanced Band Convergence and Ultra‐Low Thermal Conductivity Lead to High Thermoelectric Performance in SnTe

2021

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“…In general, avoiding band edge discontinuities between the matrix material and the grain boundaries or the different inclusions, allows the reduction of the thermal conductivity with minimal penalty in the electrical conductivity. Potential barriers, however, is the norm in nanostructured TE materials rather than the exception and cannot be easily avoided [170,171]. This creates a compromise in the design of nanostructures, where the density of defects needs to be large enough to stop phonons of various MFPs, but small enough to allow high electrical conductivity and PF.…”

Section: Introductionmentioning

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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“…Similarly, the Seebeck coefficient and the electrical conductivity can be tuned by impurity doping, resonant level doping, and nanostructured materials. 93,94,[97][98][99] The Seebeck coefficient can be expressed as: 95,100 S ¼…”

Section: Core-shell Structuresmentioning

confidence: 99%

“…The terms, n(E) and m(E) are the energy-dependent carrier density and mobility, respectively. 100 Therefore, the Seebeck coefficient can be enhanced by two mechanisms: (i) increasing the density of states (DOS) near the Fermi level and (ii) increasing the energy dependence of m(E) using energy filtering effects. Increasing DOS can be effectively achieved from resonant level doping or band engineering.…”

Section: Core-shell Structuresmentioning

confidence: 99%

Core–shell nanostructures for better thermoelectrics

Mulla

Dunnill

2022

Mater. Adv.

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Core–shell nanostructures introduce multiple potential barriers to enhance energy filtering for the improvement of the thermoelectric properties of SnTe

Abstract: BiCuSeO@SnO2 core-shell nanostructures can introduce multiple potential barriers in SnTe to enhance energy filtering effect.

Cited by 47 publications

References 65 publications

Enhanced Band Convergence and Ultra‐Low Thermal Conductivity Lead to High Thermoelectric Performance in SnTe

Enhanced Band Convergence and Ultra‐Low Thermal Conductivity Lead to High Thermoelectric Performance in SnTe

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

Core–shell nanostructures for better thermoelectrics

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