Highly anisotropic thermoelectric transport properties responsible for enhanced thermoelectric performance in the hot-deformed tetradymite Bi2Te2S

Joo, Sung‐Jae; Ryu, Byungki; Son, Ji-Hee; Lee, Ji Eun; Min, Bok Ki; Kim, Bong-Seo

doi:10.1016/j.jallcom.2018.12.340

Cited by 17 publications

(13 citation statements)

References 25 publications

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“…From the comparison with experimental data at 300 K, Hinsche et al determined that the in-plane τ = 1.2 × 10 –14 and 1.1 × 10 –14 s for the Sb 2 Te 3 and Bi 2 Te 3 , respectively. Also, fitted values such as 2.2 × 10 –14 , and ≈0.65 × 10 –14 s were suggested for Bi 2 Te 3 at 300 K. Likewise, for Bi 2 Te 2 S, the in-plane relaxation time of 3 × 10 –14 s was used …”

Section: Resultsmentioning

confidence: 99%

Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence

Diznab

Maleki

Allaei

et al. 2019

ACS Appl. Mater. Interfaces

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An efficient approach to improve the thermoelectric performance of materials is to converge their electronic bands, which is known as band engineering. In this regard, lots of effort has been made to further improve the thermoelectric efficiency of bulk and exfoliated monolayers of Bi2Te3 and Sb2Te3. However, ultrahigh band degeneracy and thus significant improvement of the power factor have not yet been realized in these materials. Using first-principles methods, we demonstrate that the valley degeneracy of Bi2Te3 and Sb2Te3 can be largely improved upon substitution of the middle-layer Te atoms with the more electronegative S or Se atoms. Our detailed analysis reveals that in this family of materials, two out of four possible valence band valleys merely depend on the electronegativity of the middle-layer chalcogen atoms, which makes the independent modulation of the valleys’ position feasible. As such, band alignment of Bi2Te3 and Sb2Te3 largely improves upon substitution of the middle-layer Te atoms with more electronegative, yet chemically similar, S and Se ones. A superior valence band alignment is attained in Sb2Te2Se monolayers where three out of four possible valleys are well aligned, resulting in a giant band degeneracy of 18 that holds the record among all thermoelectric materials. As a result, an outstanding power factor for the hole-doped monolayers is achieved, indicating a highly efficient p-type thermoelectric material.

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Section: Resultsmentioning

confidence: 99%

Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence

Diznab

Maleki

Allaei

et al. 2019

ACS Appl. Mater. Interfaces

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“…Thus, better functional properties of the two processes were obtained by our facile process. Further, Figure c shows that the values of thermal conductivity are much lower than those of the samples produced by both the previously reported processes , due to nanostructuring in our process. Resultantly, ZT has an analogous temperature dependence to the reported data , in Figure d, but 2–4 times higher ZT values.…”

Section: Thermoelectric Characterizationsmentioning

confidence: 50%

Anomalous Seebeck Coefficient in Sulfur-Substituted Bismuth Telluride

DS,

Saharan,

Sheoran

et al. 2024

ACS Appl. Eng. Mater.

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Seebeck coefficient is determined by the asymmetry of density of states across Fermi level and their occupancy. These parameters are, in turn, essentially governed by the band structure and carrier concentration of the materials. In the present study, sulfur was substituted in versatile bismuth telluride thermoelectric material in subatomic ratio. The successful substitution in the resulting compounds, viz., Bi 2 Te 2.85 S 0.15 and Bi 2 Te 2.7 S 0.3 , was confirmed using Xray diffraction with Rietveld refinement and X-ray photoelectron spectroscopy. High resolution-transmission electron microscopy showed an ultrathin platy morphology in nanopowder and a randomly oriented high grain density at nanometer scale in the consolidated pellet. The sulfur substitution resulted in polarity reversal and enhanced value of the Seebeck coefficient at subzero temperatures in the bismuth telluride matrix. This anomaly in the sign and value of the Seebeck coefficient was analyzed using temperature-dependent Hall measurement, scanning tunneling spectroscopy, and first-principle computation using density functional theory coupled with Boltzmann transport theory. The analysis showed that the band-structure variations due to the localized polarity induced by the higherelectronegativity sulfur atom at Te I sites and suppression of antisite defects may be the prominent reasons for causing this anomaly. This study may also pave the way for the design of thermoelectric materials for enhanced performance in subzero temperature range for solid-state refrigeration application.

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“…However, the σ of the nanocomposite sample with 50 mol% MoS 2 is drastically reduced in consistence with the dominant presence of the tetradymite phase ( Figure 1 ) which reduced the overall carrier concentration of the nanocomposite. Indeed, the tetradymite phase is known to have a wider bandgap ( E g ≈ 0.3 eV) and a lower electrical conductivity than Bi 2 Te 3 [ 43 , 44 ]. In addition, the influence of the fractured microstructure ( Figure 2 c) cannot be ruled out, which could be the major contribution of the large reduction of the σ in the Bi 2 Te 3 /75 mol%MoS 2 composite by reducing the carrier mobility.…”

Section: Resultsmentioning

confidence: 99%

“…Further increase in mol% of MoS 2 dilapidates the value of | S | to around 40% lower in the Bi 2 Te 3 /50 mol% MoS 2 sample. Contrary to the electrical transport tendency moving to a ‘semiconductor-like’ behavior with increasing MoS 2 molar ratio, the decreasing of | S | suggests a more ‘metal-like’ behavior that is not representative of the tetradymite main phase, which will be represented by a higher | S | (≈−190 μV K −1 at 300 K) [ 43 , 44 ]. However, this Seebeck value appears consistent with the report of the MoS 2 /Mo 2 S 3 nanocomposite [ 45 ], which gives us an insight into the non-negligible role of the S-deficient MoS 2 phases observed in the EDS mapping analysis ( Figures S4 and S5 ).…”

Section: Resultsmentioning

confidence: 99%

The Effect of Reactive Electric Field-Assisted Sintering of MoS2/Bi2Te3 Heterostructure on the Phase Integrity of Bi2Te3 Matrix and the Thermoelectric Properties

Wang

Bourgès

Rajamathi³

et al. 2021

Materials

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In this work, a series of Bi2Te3/X mol% MoS2 (X = 0, 25, 50, 75) bulk nanocomposites were prepared by hydrothermal reaction followed by reactive spark plasma sintering (SPS). X-ray diffraction analysis (XRD) indicates that the native nanopowders, comprising of Bi2Te3/MoS2 heterostructure, are highly reactive during the electric field-assisted sintering by SPS. The nano-sized MoS2 particles react with the Bi2Te3 plates matrix forming a mixed-anion compound, Bi2Te2S, at the interface between the nanoplates. The transport properties characterizations revealed a significant influence of the nanocomposite structure formation on the native electrical conductivity, Seebeck coefficient, and thermal conductivity of the initial Bi2Te3 matrix. As a result, enhanced ZT values have been obtained in Bi2Te3/25 mol% MoS2 over the temperature range of 300–475 K induced mainly by a significant increase in the electrical conductivity.

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Highly anisotropic thermoelectric transport properties responsible for enhanced thermoelectric performance in the hot-deformed tetradymite Bi2Te2S

Cited by 17 publications

References 25 publications

Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence

Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence

Anomalous Seebeck Coefficient in Sulfur-Substituted Bismuth Telluride

The Effect of Reactive Electric Field-Assisted Sintering of MoS2/Bi2Te3 Heterostructure on the Phase Integrity of Bi2Te3 Matrix and the Thermoelectric Properties

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Highly anisotropic thermoelectric transport properties responsible for enhanced thermoelectric performance in the hot-deformed tetradymite Bi2Te2S

Cited by 17 publications

References 25 publications

Achieving an Ultrahigh Power Factor in Sb2Te2Se Monolayers via Valence Band Convergence

Achieving an Ultrahigh Power Factor in Sb2Te2Se Monolayers via Valence Band Convergence

Anomalous Seebeck Coefficient in Sulfur-Substituted Bismuth Telluride

The Effect of Reactive Electric Field-Assisted Sintering of MoS2/Bi2Te3 Heterostructure on the Phase Integrity of Bi2Te3 Matrix and the Thermoelectric Properties

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Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence

Achieving an Ultrahigh Power Factor in Sb₂Te₂Se Monolayers via Valence Band Convergence