The long-standing popularity of thermoelectric materials has contributed to the creation of various thermoelectric devices and stimulated the development of strategies to improve their thermoelectric ...performance. In this review, we aim to comprehensively summarize the state-of-the-art strategies for the realization of high-performance thermoelectric materials and devices by establishing the links between synthesis, structural characteristics, properties, underlying chemistry and physics, including structural design (point defects, dislocations, interfaces, inclusions, and pores), multidimensional design (quantum dots/wires, nanoparticles, nanowires, nano- or microbelts, few-layered nanosheets, nano- or microplates, thin films, single crystals, and polycrystalline bulks), and advanced device design (thermoelectric modules, miniature generators and coolers, and flexible thermoelectric generators). The outline of each strategy starts with a concise presentation of their fundamentals and carefully selected examples. In the end, we point out the controversies, challenges, and outlooks toward the future development of thermoelectric materials and devices. Overall, this review will serve to help materials scientists, chemists, and physicists, particularly students and young researchers, in selecting suitable strategies for the improvement of thermoelectrics and potentially other relevant energy conversion technologies.
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IJS, KILJ, NUK, PNG, UL, UM
GeTe with rhombohedral‐to‐cubic phase transition is a promising lead‐free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is ...linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon–phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally, based on Ge1−xSbxTe with optimized carrier concentration, a record‐high figure‐of‐merit of 2.3 is achieved via further doping with In, which induces the distortion of the density of states near the Fermi level. Moreover, Sb and In codoping reduces the phase‐transition temperature to extend the better thermoelectric behavior of cubic GeTe to low temperature. Additionally, electronic microscopy characterization demonstrates grain boundaries, a high‐density of stacking faults, and nanoscale precipitates, which together with the inevitable point defects result in a dramatically decreased thermal conductivity. The fundamental investigation and experimental demonstration provide an important direction for the development of high‐performance Pb‐free thermoelectric materials.
An ultrahigh figure‐of‐merit of 2.3 is achieved in Ge0.89Sb0.1In0.01Te through enhancing the power‐factor and decreasing the thermal conductivity. The enhanced power‐factor is caused by the optimized carrier concentration, reduced phase‐transition temperature, and introduced resonant‐energy doping. The decreased thermal conductivity is due to the enhanced phonon scattering by the intrinsically deformed phonon transport and the externally induced phonon scattering sources.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Thermoelectric materials offer an alternative opportunity to tackle the energy crisis and environmental problems by enabling the direct solid-state energy conversion. As a promising candidate with ...full potentials for the next generation thermoelectrics, tin selenide (SnSe) and its associated thermoelectric materials have been attracted extensive attentions due to their ultralow thermal conductivity and high electrical transport performance (power factor). To provide a thorough overview of recent advances in SnSe-based thermoelectric materials that have been revealed as promising thermoelectric materials since 2014, here, we first focus on the inherent relationship between the structural characteristics and the supreme thermoelectric performance of SnSe, including the thermodynamics, crystal structures, and electronic structures. The effects of phonon scattering, pressure or strain, and oxidation behavior on the thermoelectric performance of SnSe are discussed in detail. Besides, we summarize the current theoretical calculations to predict and understand the thermoelectric performance of SnSe, and provide a comprehensive summary on the current synthesis, characterization, and thermoelectric performance of both SnSe crystals and polycrystals, and their associated materials. In the end, we point out the controversies, challenges and strategies toward future enhancements of the SnSe thermoelectric materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
As a key type of emerging thermoelectric material, tin telluride (SnTe) has received extensive attention because of its low toxicity and eco‐friendly nature. The recent trend shows that band ...engineering and nanostructuring can enhance thermoelectric performance of SnTe as intermediate temperature (400–800 K) thermoelectrics, which provides an alternative for toxic PbTe with the same operational temperature. This review highlights the key strategies to enhance the thermoelectric performance of SnTe materials through band engineering, carrier concentration optimization, synergistic engineering, and structure design. A fundamental analysis elucidates the underpinnings for the property improvement. This comprehensive review will boost the relevant research with a view to work on further performance enhancement of SnTe materials.
SnTe qualifies as an eco‐friendly alternative to medium‐temperature thermoelectric PbTe by showing robust potential as high‐performance thermoelectrics via effective strategies through band engineering, carrier concentration optimization, synergistic engineering, and structure design.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Asymmetric hydroxycarbonylation is one of the most fundamental yet challenging methods for the synthesis of carboxylic acids. Herein, we reported the development of a palladium‐catalyzed highly ...enantioselective Markovnikov hydroxycarbonylation of vinyl arenes with CO and water. A monodentate phosphoramidite ligand L6 plays vital role in the reaction. The reaction tolerates a range of functional groups, and provides a facile and atom‐economical approach to an array of 2‐arylpropanoic acids including several commonly used non‐steroidal anti‐inflammatory drugs. The catalytic system has also enabled an asymmetric Markovnikov hydroalkoxycarbonylation of vinyl arenes with alcohols to afford 2‐arylpropanates. Mechanistic investigations suggested that the hydropalladation is irreversible and is the regio‐ and enantiodetermining step, while hydrolysis/alcoholysis is probably the rate‐limiting step.
A Pd‐catalyzed highly enantioselective Markovnikov hydroxycarbonylation of vinyl arenes with CO and water for the synthesis of 2‐arylpropanoic acids has been developed. Several non‐steroidal anti‐inflammatory drugs including ibuprofen, naproxen, flurbiprofen, fenoprofen, and ketoprofen were synthesized in high yields and ees in gram scale.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The coupling nature of thermoelectric properties determines that optimizing the Fermi level is the priority to achieve a net increase in thermoelectric performance. Conventionally, the carrier ...concentration is used as the reflection of the Fermi level in the band structure. However, carrier concentration strongly depends upon the material’s effective mass, leading to that the optimal carrier concentration varies over a large scale for different materials. Herein, inspired by the big data survey, we develop a golden Seebeck coefficient range of 202–230 μV K–1 for thermoelectric semiconductors with lattice thermal conductivity of 0.4–1.5 W m–1 K–1. When the measured Seebeck coefficient reaches this range, the corresponding figure of merit is maximized. Using this approach, we exemplarily analyze the characteristics of n-type Pb1–x Bi x Se thermoelectric materials. With detailed electron microscopy and property characterizations, the high densities of dislocations and pores are found to be responsible for a low lattice thermal conductivity. Moreover, Bi substitution significantly tunes the Seebeck coefficient in a wide range. As a result, the Seebeck coefficient of ∼ –230 μV K–1 in Pb0.98Bi0.02Se is close to the golden range, leading to a figure of merit beyond 1.5. This finding provides an intuitive metric to determine the optimization extent of thermoelectric performance.
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Due to the nature of their liquid‐like behavior and high dimensionless figure of merit, Cu2X (X = Te, Se, and S)‐based thermoelectric materials have attracted extensive attention. The superionicity ...and Cu disorder at the high temperature can dramatically affect the electronic structure of Cu2X and in turn result in temperature‐dependent carrier‐transport properties. Here, the effective strategies in enhancing the thermoelectric performance of Cu2X‐based thermoelectric materials are summarized, in which the proper optimization of carrier concentration and minimization of the lattice thermal conductivity are the main focus. Then, the stabilities, mechanical properties, and module assembly of Cu2X‐based thermoelectric materials are investigated. Finally, the future directions for further improving the energy conversion efficiency of Cu2X‐based thermoelectric materials are highlighted.
Deriving from their high performance and eco‐friendliness, superionic Cu2X‐based thermoelectric materials are attracting ever‐increasing attention. A comprehensive summary of the understanding of the superionicity, performance enhancement strategies, and material stability design can set up a solid foundation for future development. Pointing out the development challenges can better guide future studies.
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Conducting polymers have drawn considerable attention in the field of wearable and implantable thermoelectric devices due to their unique advantages, including availability, ...flexibility, lightweight, and non-toxicity. To date, researchers have made dramatic breakthroughs in achieving high-performance thermoelectrics; however, the figure of merit ZT of conducting polymers is still far below that of the high-performance thermoelectric Bi2Te3-based alloys at room temperature. This challenge lies in the complex interrelation between electrical conductivity, Seebeck coefficient, and thermal conductivity. In this review, we overview the state-of-the-art on conducting polymers and their thermoelectric devices, starting with the summary of the fundamentals as well as several well-accepted theoretical models. Furthermore, this review examines the key factors determining the charge transport mechanisms in this family of materials and previously reported optimization strategies are discussed and classified. Finally, this review further introduces several favourable device fabrication techniques including illustrating and demonstrating the performance of several typical thermoelectric prototypes, which highlights the bright future of polymer-based flexible thermoelectric devices in wearable and implantable electronics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The spreading of misfolded alpha-synuclein (α-syn) protein has been observed in animal models of Parkinson's disease (PD) and other α-synucleinopathies that mimic human PD pathologies. In animal ...models, the spreading of α-syn has been associated with motor dysfunction and neuronal death. However, variability in both susceptible brain regions and cellular populations limits our understanding of the consequences of α-syn spreading and the development of associated therapies. Here, we have reviewed the physiological and pathological functions of α-syn and summarized the susceptible brain regions and cell types identified from human postmortem studies and exogenous α-syn injection-based animal models. We have reviewed the methods for inducing α-syn aggregation, the specific hosts, the inoculation sites, the routes of propagation, and other experimental settings that may affect the spreading pattern of α-syn, as reported in current studies. Understanding the spread of α-syn to produce a consistent PD animal model is vital for future drug discovery.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
<正>The field of thermoelectrics has long been recognized as a potentially transformative power generation technology and the field is now growing steadily due to their ability to convert heat ...directly into electricity and to develop cost-effective,pollution-free forms of energy conversion.Of various types of thermoelectric materials,nanostructured materials have shown the most promise for commercial use because of their extraordinary thermoelectric performances. This article aims to summarize the present progress of nanostructured thermoelectrics and intends to understand and explain the underpinnings of the innovative breakthroughs in the last decade or so.We believed that recent achievements will augur the possibility for thermoelectric power generation and cooling,and discuss several future directions which could lead to new exciting next generation of nanostructured thermoelectrics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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