Simultaneous Enhancement of Electrical Conductivity and Thermopower of Bi<sub>2</sub>Te<sub>3</sub> by Multifunctionality of Native Defects

Suh, Joonki; Yu, Kin Man; Fu, Deyi; Liu, Xinyu; Yang, Fan; Fan, Jinchen; Smith, David J.; Zhang, Yong-Hang; Furdyna, J. K.; Dames, Chris; Walukiewicz, W.; Wu, Junqiao

doi:10.1002/adma.201501350

Cited by 106 publications

(83 citation statements)

References 36 publications

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“…Undoped materials show a decrease in n‐type carrier concentration, suggesting SiC somehow alters intrinsic defect concentrations possibly at the interfaces of the grains ( Figure 3 a). The carrier concentration of polycrystalline Bi 2 Te 3− x Se x is usually affected by the concentration of anion vacancies, antisite defects, and their interaction (donor‐like effect), which is shown in the following equation28, 29, 30

2 V_{normalBi}^{‴} + 3 V_{Te}^{¨} (V_{Se}^{¨}) + B i_{normalTe}^{'} (B i_{normalSe}^{'}) = V_{normalBi}^{‴} + B i_{Bi}^{normal*} + 4 V_{Te}^{¨} (V_{Se}^{¨}) + 6 e^{'}

…”

Section: Resultsmentioning

confidence: 99%

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

et al. 2017

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Bi2Te3 thermoelectric materials are utilized for refrigeration for decades, while their application of energy harvesting requires stable thermoelectric and mechanical performances at elevated temperatures. This work reveals that a steady zT of ≈0.85 at 200 to 300 °C can be achieved by doping small amounts of copper iodide (CuI) in Bi2Te2.2Se0.8–silicon carbide (SiC) composites, where SiC nanodispersion enhances the flexural strength. It is found that CuI plays two important roles with atomic Cu/I dopants and CuI precipitates. The Cu/I dopants show a self‐tuning behavior due to increasing solubility with increasing temperatures. The increased doping concentration increases electrical conductivity at high temperatures and effectively suppresses the intrinsic excitation. In addition, a large reduction of lattice thermal conductivity is achieved due to the “in situ” CuI nanoprecipitates acting as phonon‐scattering centers. Over 60% reduction of bipolar thermal conductivity is achieved, raising the maximum useful temperature of Bi2Te3 for substantially higher efficiency. For module applications, the reported materials are suitable for segmentation with a conventional ingot. This leads to high device ZT values of ≈0.9–1.0 and high efficiency up to 9.2% from 300 to 573 K, which can be of great significance for power generation from waste heat.

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2 V_{normalBi}^{‴} + 3 V_{Te}^{¨} (V_{Se}^{¨}) + B i_{normalTe}^{'} (B i_{normalSe}^{'}) = V_{normalBi}^{‴} + B i_{Bi}^{normal*} + 4 V_{Te}^{¨} (V_{Se}^{¨}) + 6 e^{'}

…”

Section: Resultsmentioning

confidence: 99%

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

et al. 2017

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“…Several experimental works have supported this idea, among them the research with doped skutterudites, [50][51][52][53] Ni cross-substituted type-I clathrates, 54 and Bi 2 Te 3 with native defects. 55 This change of r brings about additional scattering, which inevitably reduces the mobility. Finding a proper ratio between the acoustic phonon scattering and the impurity scattering is essential to maximise the benefits.…”

Section: Manipulation Of Carrier Scatteringmentioning

confidence: 99%

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

et al. 2016

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During the last two decades, we have witnessed great progress in research on thermoelectrics. There are two primary focuses. One is the fundamental understanding of electrical and thermal transport, enabled by the interplay of theory and experiment; the other is the substantial enhancement of the performance of various thermoelectric materials, through synergistic optimisation of those intercorrelated transport parameters. Here we review some of the successful strategies for tuning electrical and thermal transport. For electrical transport, we start from the classical but still very active strategy of tuning band degeneracy (or band convergence), then discuss the engineering of carrier scattering, and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials. For thermal transport, we summarise the approaches for studying thermal transport based on phonon-phonon interactions valid for conventional solids, as well as some quantitative efforts for nanostructures. We also discuss the thermal transport in complex materials with chemical-bond hierarchy, in which a portion of the atoms (or subunits) are weakly bonded to the rest of the structure, leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures. In this review, we provide a summary of achievements made in recent studies of thermoelectric transport properties, and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment, and point out some challenges and possible directions. INTRODUCTION Thermoelectric (TE) materials are materials that can generate useful electric potentials when subjected to a temperature gradient (known as the Seebeck effect). Conversely, they also transfer heat against the temperature gradient when a current is driven against this potential (known as the Peltier effect). They are promising energy materials with many applications, such as waste heat harvesting, radioisotope TE power generation, and solid state Peltier refrigeration, all of which are driving growing research interest. A key challenge is to improve the TE properties in order to obtain more efficient energy conversion and in turn enable new practical applications. Good TE materials must have excellent electrical transport properties, measured by the TE power factor ( = S 2 σ, where S is the Seebeck coefficient and σ is the electrical conductivity), and also a very low thermal conductivity κ (composed of the electronic contribution κ e , the lattice contribution κ L , and the bipolar contribution κ bi ). Combining the two aspects gives us the dimensionless figure of merit ZT,

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“…Point defects can catalyze chemical reactions 1 , control the efficiency of light emission 2–4 , and tune the electrical 5, 6 and thermal 7–9 properties of materials. Defects in crystalline materials require energy to be generated, and as such they can be regarded as excited states of the crystal.…”

Section: Introductionmentioning

confidence: 99%

Using defects to store energy in materials – a computational study

Bernardi

2017

Sci Rep

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Energy storage occurs in a variety of physical and chemical processes. In particular, defects in materials can be regarded as energy storage units since they are long-lived and require energy to be formed. Here, we investigate energy storage in non-equilibrium populations of materials defects, such as those generated by bombardment or irradiation. We first estimate upper limits and trends for energy storage using defects. First-principles calculations are then employed to compute the stored energy in the most promising elemental materials, including tungsten, silicon, graphite, diamond and graphene, for point defects such as vacancies, interstitials and Frenkel pairs. We find that defect concentrations achievable experimentally (~0.1–1 at.%) can store large energies per volume and weight, up to ~5 MJ/L and 1.5 MJ/kg for covalent materials. Engineering challenges and proof-of-concept devices for storing and releasing energy with defects are discussed. Our work demonstrates the potential of storing energy using defects in materials.

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Simultaneous Enhancement of Electrical Conductivity and Thermopower of Bi₂Te₃ by Multifunctionality of Native Defects

Cited by 106 publications

References 36 publications

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Using defects to store energy in materials – a computational study

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Simultaneous Enhancement of Electrical Conductivity and Thermopower of Bi2Te3 by Multifunctionality of Native Defects

Cited by 106 publications

References 36 publications

Self‐Tuning n‐Type Bi2(Te,Se)3/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

Self‐Tuning n‐Type Bi2(Te,Se)3/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Using defects to store energy in materials – a computational study

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Product

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Simultaneous Enhancement of Electrical Conductivity and Thermopower of Bi₂Te₃ by Multifunctionality of Native Defects

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

Self‐Tuning n‐Type Bi₂(Te,Se)₃/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C