Thermoelectric transport properties of rock-salt SnSe: first-principles investigation

Wang, Dongyang; He, Wei; Chang, Cheng; Wang, Guangtao; Wang, Jinfeng; Zhao, Li‐Dong

doi:10.1039/c8tc01314d

Cited by 56 publications

(34 citation statements)

References 60 publications

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“…The trend of the values firstly increases and then decreases with a maximum value at ≈464 K due to the bipolar effect of minority carrier excitation. [17] All the Seebeck coefficients of single-crystal SnSe are lower than those of polycrystalline SnSe at the same measured temperature, which is due to the increased carrier concentration derived from a small energy gap around 0.20 eV and a large electronic density of states in the cubic rock-salt phase. [18] The electrical conductivities of polycrystalline and single-crystal rock-salt SnSe show different temperature-dependent trends (Figure 3b).…”

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confidence: 89%

“…The thermoelectric property of single-crystal SnSe fiber with rock-salt Fm3 m phase has not been reported so far, even though the theoretical studies on polycrystalline SnSe bulk materials with rock-salt phase have indicated that rock-salt SnSe is a very promising material for high-performance thermoelectrics. [17,18] Here, we experimentally measure the thermoelectric properties along the axial direction as a function of temperature for SnSe fibers with both polycrystalline and single-crystal rock-salt structures. As shown in Figure 3a, both the Seebeck coefficients of polycrystalline and single-crystal SnSe fiber are positive, which means they are p-type semiconductors.…”

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confidence: 99%

“…There are two band valleys above the conduction band minimum and three band valleys below the valence band maximum. The deviation of band valleys from high symmetry points results in a larger valley degeneracy number [17] and enhances the thermoelectric power factor. The electronic transport properties are calculated by employing BoltzTraP package [26] based on the semiclassical Boltzmann transport theory with the constant relaxation time approximation.…”

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confidence: 99%

“…The experimental Seebeck coefficient of the 1D fiber is significantly higher than the calculated value of bulk rock-salt SnSe. [17] Therefore, we used a 1 × 2 × 2 supercell of rock-salt SnSe having 32 atoms (8 × 1 × 2 × 2) with a 20 Å vacuum added in the two transverse directions to confine the electrons and simulate the 1D electronic transport. The simulations provide a general guideline to understanding experimental results and the calculated Seebeck coefficient is comparable to the experiments.…”

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confidence: 99%

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Single‐Crystal SnSe Thermoelectric Fibers via Laser‐Induced Directional Crystallization: From 1D Fibers to Multidimensional Fabrics

Zhang

et al. 2020

Advanced Materials

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Single‐crystal tin selenide (SnSe), a record holder of high‐performance thermoelectric materials, enables high‐efficient interconversion between heat and electricity for power generation or refrigeration. However, the rigid bulky SnSe cannot satisfy the applications for flexible and wearable devices. Here, a method is demonstrated to achieve ultralong single‐crystal SnSe wire with rock‐salt structure and high thermoelectric performance with diameters from micro‐ to nanoscale. This method starts from thermally drawing SnSe into a flexible fiber‐like substrate, which is polycrystalline, highly flexible, ultralong, and mechanically stable. Then a CO2 laser is employed to recrystallize the SnSe core to single‐crystal over the entire fiber. Both theoretical and experimental studies demonstrate that the single‐crystal rock‐salt SnSe fibers possess high thermoelectric properties, significantly enhancing the ZT value to 2 at 862 K. This simple and low‐cost approach offers a promising path to engage the fiber‐shaped single‐crystal materials in applications from 1D fiber devices to multidimensional wearable fabrics.

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confidence: 89%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Single‐Crystal SnSe Thermoelectric Fibers via Laser‐Induced Directional Crystallization: From 1D Fibers to Multidimensional Fabrics

Zhang

et al. 2020

Advanced Materials

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“…18,21 Rocksalt SnS can be stabilised under certain conditions such as epitaxial growth, 20,22 whereas rocksalt SnSe is a dynamically stable phase under ambient conditions. 23 We therefore focus on the Pnma, Cmcm, rocksalt and π-cubic phases, the structures of which are illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Phase Stability of the Tin Monochalcogenides SnS and SnSe: A Quasi-Harmonic Lattice-Dynamics Study

Pallikara¹,

Skelton²

2021

Preprint

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The tin monochalcogenides SnS and SnSe adopt four different crystal structures, viz. orthorhombic Pnma and Cmcm and cubic rocksalt and π-cubic (P213) phases, each of which has optimal properties for a range of potential applications. This rich phase space makes it challenging to identify the conditions under which the different phases are obtained. We have performed first-principles quasi-harmonic lattice-dynamics calculations to assess the relative stabilities of the four phases of SnS and SnSe. We investigate dynamical stability through the presence or absence of imaginary modes in the phonon dispersion curves, and we compute Helmholtz and Gibbs free energies to evaluate the thermodynamic stability. We also consider applied pressures from 0-15 GPa to obtain temperature-pressure phase diagrams. Finally, the relationships between the different crystal phases are investigated by explicitly mapping the potential-energy surfaces along the imaginary phonon modes and by using the climbing-image nudged elastic-band method.

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Metavalent Bonding in Cubic SnSe Alloys Improves Thermoelectric Properties over a Broad Temperature Range

Lin,

Han,

Ghosh

et al. 2024

Adv Funct Materials

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Monocrystalline SnSe is one of the most promising thermoelectric materials with outstanding performance and a high abundance of constituting elements. However, polycrystalline SnSe, which is more robust for applications, only shows large figure‐of‐merit (zT) values in its high‐symmetry phase. Stabilizing the high‐symmetry phase at low temperatures can thus enhance the average zT value over a broad temperature range. In this work, the high‐symmetry rock‐salt SnSe phase is successfully obtained by alloying SnSe with AgVVI2 compounds (V = Sb, Bi; VI = Se, Te). These cubic SnSe phases show a unique portfolio of properties including a high optical dielectric constant, a large maximum of optical absorption, a large Born effective charge, and abnormal bond‐breaking behavior in laser‐assisted atom probe tomography. All of these characteristics are indicative of metavalent bonding. In contrast, the Pnma phase of SnSe employs covalent bonding. The enhanced symmetry at low temperatures is realized by tailoring chemical bonding. Concomitantly, zT near room temperature is increased by a factor of more than 10 from the pristine Pnma SnSe to Fmm SnSe alloys. This provides insights into the enhancement of the thermoelectric performance of SnSe and other chalcogenides over a broad temperature range by manipulating the chemical bonds.

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Thermoelectric transport properties of rock-salt SnSe: first-principles investigation

Abstract: Rock-salt SnSe is a new promising thermoelectric material.

Cited by 56 publications

References 60 publications

Single‐Crystal SnSe Thermoelectric Fibers via Laser‐Induced Directional Crystallization: From 1D Fibers to Multidimensional Fabrics

Single‐Crystal SnSe Thermoelectric Fibers via Laser‐Induced Directional Crystallization: From 1D Fibers to Multidimensional Fabrics

Phase Stability of the Tin Monochalcogenides SnS and SnSe: A Quasi-Harmonic Lattice-Dynamics Study

Metavalent Bonding in Cubic SnSe Alloys Improves Thermoelectric Properties over a Broad Temperature Range

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