Remarkably high thermoelectric performance of Cu<sub>2−x</sub>Li<sub>x</sub>Se bulks with nanopores

Hu, Qiujun; Zhu, Zheng; Zhang, Yuewen; Li, Xinjian; Song, Hang; Zhang, Yingjiu

doi:10.1039/c8ta06912c

Cited by 78 publications

(31 citation statements)

References 35 publications

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“…However, calculations indicate that the pores can contribute to the κ l reduction only when the size of pores is reduced to a certain value. To determine the effective size of pores, a “gray medium” approximation under the assumption of complete phonon‐scattering on the interfaces of these interspaces can be described as154

κ_{l} = \frac{1 - ϕ_{n}}{1 + {normalΛ}_{b} \cdot ([], \frac{3 α_{n} ϕ_{n}}{2 (α_{n} + 2) \cdot d_{n}})} \cdot κ_{lb}

where α n is the “shape” parameter of the gamma distribution,256 d n is the average diameter of interspaces, and κ lb is the lattice thermal conductivity of bulk with 100% relative mass density, respectively. The parameter ϕ n can be described as154

ϕ_{n} = \frac{1}{6} π c_{n} d_{n}^{3} ([], \frac{(α_{n} + 1) (α_{n} + 2)}{α_{n}^{2}})

where c n is the number density of interspaces and Λ b is the phonon mean free path calculated by154

{normalΛ}_{b} = \frac{3 \cdot κ_{lb}}{C_{v} v_{a}}

where C v is the volume heat capacity and v a is the average sound velocity, taken as 1410 m s −1 for SnSe 24.…”

Section: Fundamentalmentioning

confidence: 99%

“…Thermodynamics of SnSe. a) The phase diagram of Sn–Se 154,195–197. b) Sn‐rich region of the Sn–Se phase diagram 196.…”

Section: Fundamentalmentioning

confidence: 99%

“…Figure a shows the development timeline for all SnSe‐based bulk thermoelectric materials,11–124 from which a record high ZT of ≈2.8 at 773 K was found in the n‐type SnSe single crystal,11 derived from its ultralow κ l of ≈0.18 W m −1 K −1 and high S 2 σ of ≈9.0 µW cm −1 K −2 at this temperature 125. Such a high ZT is also very competitive to other state‐of‐the‐art thermoelectric systems which possess ZTs > 2, such as PbTe,126–134 GeTe,135–147 Cu 2 Se/Cu 2 S,148–157 and AgSbTe 2 158. Inspired by the full potentials for further improving ZT via reducing κ l and tuning carrier concentration n (for electrons) and/or p (for holes), SnSe‐based thermoelectric materials have attracted much attentions in recent years 159,160…”

Section: Introductionmentioning

confidence: 97%

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High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

2020

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Tin selenide (SnSe) is one of the most promising candidates to realize environmentally friendly, cost‐effective, and high‐performance thermoelectrics, derived from its outstanding electrical transport properties by appropriate bandgaps and intrinsic low lattice thermal conductivity from its anharmonic layered structure. Advanced aqueous synthesis possesses various unique advantages including convenient morphology control, exceptional high doping solubility, and distinctive vacancy engineering. Considering that there is an urgent demand for a comprehensive survey on the aqueous synthesis technique applied to thermoelectric SnSe, herein, a thorough overview of aqueous synthesis, characterization, and thermoelectric performance in SnSe is provided. New insights into the aqueous synthesis‐based strategies for improving the performance are provided, including vacancy synergy, crystallization design, solubility breakthrough, and local lattice imperfection engineering, and an attempt to build the inherent links between the aqueous synthesis‐induced structural characteristics and the excellent thermoelectric performance is presented. Furthermore, the significant advantages and potentials of an aqueous synthesis route for fabricating SnSe‐based 2D thermoelectric generators, including nanorods, nanobelts, and nanosheets, are also discussed. Finally, the controversy, strategy, and outlook toward future enhancement of SnSe‐based thermoelectric materials are also provided. This Review guides the design of thermoelectric SnSe with high performance and provides new perspectives as a reference for other thermoelectric systems.

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κ_{l} = \frac{1 - ϕ_{n}}{1 + {normalΛ}_{b} \cdot ([], \frac{3 α_{n} ϕ_{n}}{2 (α_{n} + 2) \cdot d_{n}})} \cdot κ_{lb}

ϕ_{n} = \frac{1}{6} π c_{n} d_{n}^{3} ([], \frac{(α_{n} + 1) (α_{n} + 2)}{α_{n}^{2}})

where c n is the number density of interspaces and Λ b is the phonon mean free path calculated by154

{normalΛ}_{b} = \frac{3 \cdot κ_{lb}}{C_{v} v_{a}}

where C v is the volume heat capacity and v a is the average sound velocity, taken as 1410 m s −1 for SnSe 24.…”

Section: Fundamentalmentioning

confidence: 99%

“…Thermodynamics of SnSe. a) The phase diagram of Sn–Se 154,195–197. b) Sn‐rich region of the Sn–Se phase diagram 196.…”

Section: Fundamentalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

2020

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“…other cases, doping is achieved by incorporation of larger species. For example, carbon/graphene doped Cu2Se materials have recently demonstrated a high ZT of ~ 2.4 at 850-1000 K[24,159,160,161,162].…”

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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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“…For instance, Liu et al used iodine dopant to tune the phase transition temperature of Cu 2 Se, as a result, high ZT value of 2.3 at 400 K obtained, while, Hu et al doped Cu 2 Se with alkaline metal Li to enhance S . They reported ZT of 2.14 at 973 K for Cu 1.98 Li 0.02 Se . In addition, Yang et al used nanostructuring technique that reduced κ lat up to ~0.2 Wm −1 K −1 , as a result obtained high ZT value of 1.82 at 850 K .…”

Section: High Performance Inorganic Te Materialsmentioning

confidence: 99%

Inorganic thermoelectric materials: A review

et al. 2020

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Summary Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near‐room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article.

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Remarkably high thermoelectric performance of Cu_2−xLi_xSe bulks with nanopores

Abstract: Cu2Se is a p-type semiconducting compound that possesses excellent thermoelectric properties which exhibit great potential for practical applications.

Cited by 78 publications

References 35 publications

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

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

Inorganic thermoelectric materials: A review

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Remarkably high thermoelectric performance of Cu2−xLixSe bulks with nanopores

Abstract: Cu2Se is a p-type semiconducting compound that possesses excellent thermoelectric properties which exhibit great potential for practical applications.

Cited by 78 publications

References 35 publications

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

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

Inorganic thermoelectric materials: A review

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Remarkably high thermoelectric performance of Cu_2−xLi_xSe bulks with nanopores