Enhancement of the thermoelectric performance of bulk SnTe alloys: Via the synergistic effect of band structure modification and chemical bond softening

Hongchao Wang, Junphil Hwang, Chao Zhang, Teng Wang, Wenbin Su, Hoon Kim, Jungwon Kim, Jinze Zhai, Xue Wang, Hwanjoo Park, Woochul Kim, Chunlei Wang

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

SnTe alloys, which have the same crystal structure as PbTe, have attracted increasing attention. Here, we demonstrate that the synergistic effect of band structure modification and chemical bond softening can be realized simultaneously in In & Mn doped SnTe bulk alloys. The Seebeck coefficient and power factor are synergistically improved by co-doping of In and Mn. In doping is known to introduce a resonance level. Mn doping reduces the separation of light- and heavy-valence bands. The combination of these effects significantly enhances the Seebeck coefficient at room temperature owing to around a factor of five times increase in the band effective mass. The reduction of thermal conductivity is from the decrease of both the electronic and phononic parts. The electronic thermal conductivity is decreased by the increase in defect scattering, as can be confirmed by the carrier mobility. The force constant of the bonds around the Te site is decreased due to the co-doping of In & Mn, which indicates that the chemical bonds are softened, which leads to low sound velocity and lower lattice thermal conductivity. As a result, the peak thermoelectric figure of merit, zT = 1.03 has been achieved for Sn0.89In0.01Mn0.1Te at 923 K. This strategy of using the synergistic effect of band structure modification and chemical bond softening could be applicable to other thermoelectric materials.

Original languageEnglish
Pages (from-to)14165-14173
Number of pages9
JournalJournal of Materials Chemistry A
Volume5
Issue number27
DOIs
Publication statusPublished - 2017 Jan 1

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Chemical bonds
Band structure
Doping (additives)
Thermal conductivity
Seebeck coefficient
Carrier mobility
Acoustic wave velocity
Valence bands
Crystal structure
Scattering
Defects
Temperature

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Wang, Hongchao ; Hwang, Junphil ; Zhang, Chao ; Wang, Teng ; Su, Wenbin ; Kim, Hoon ; Kim, Jungwon ; Zhai, Jinze ; Wang, Xue ; Park, Hwanjoo ; Kim, Woochul ; Wang, Chunlei. / Enhancement of the thermoelectric performance of bulk SnTe alloys : Via the synergistic effect of band structure modification and chemical bond softening. In: Journal of Materials Chemistry A. 2017 ; Vol. 5, No. 27. pp. 14165-14173.
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Enhancement of the thermoelectric performance of bulk SnTe alloys : Via the synergistic effect of band structure modification and chemical bond softening. / Wang, Hongchao; Hwang, Junphil; Zhang, Chao; Wang, Teng; Su, Wenbin; Kim, Hoon; Kim, Jungwon; Zhai, Jinze; Wang, Xue; Park, Hwanjoo; Kim, Woochul; Wang, Chunlei.

In: Journal of Materials Chemistry A, Vol. 5, No. 27, 01.01.2017, p. 14165-14173.

Research output: Contribution to journalArticle

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T1 - Enhancement of the thermoelectric performance of bulk SnTe alloys

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AU - Wang, Hongchao

AU - Hwang, Junphil

AU - Zhang, Chao

AU - Wang, Teng

AU - Su, Wenbin

AU - Kim, Hoon

AU - Kim, Jungwon

AU - Zhai, Jinze

AU - Wang, Xue

AU - Park, Hwanjoo

AU - Kim, Woochul

AU - Wang, Chunlei

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N2 - SnTe alloys, which have the same crystal structure as PbTe, have attracted increasing attention. Here, we demonstrate that the synergistic effect of band structure modification and chemical bond softening can be realized simultaneously in In & Mn doped SnTe bulk alloys. The Seebeck coefficient and power factor are synergistically improved by co-doping of In and Mn. In doping is known to introduce a resonance level. Mn doping reduces the separation of light- and heavy-valence bands. The combination of these effects significantly enhances the Seebeck coefficient at room temperature owing to around a factor of five times increase in the band effective mass. The reduction of thermal conductivity is from the decrease of both the electronic and phononic parts. The electronic thermal conductivity is decreased by the increase in defect scattering, as can be confirmed by the carrier mobility. The force constant of the bonds around the Te site is decreased due to the co-doping of In & Mn, which indicates that the chemical bonds are softened, which leads to low sound velocity and lower lattice thermal conductivity. As a result, the peak thermoelectric figure of merit, zT = 1.03 has been achieved for Sn0.89In0.01Mn0.1Te at 923 K. This strategy of using the synergistic effect of band structure modification and chemical bond softening could be applicable to other thermoelectric materials.

AB - SnTe alloys, which have the same crystal structure as PbTe, have attracted increasing attention. Here, we demonstrate that the synergistic effect of band structure modification and chemical bond softening can be realized simultaneously in In & Mn doped SnTe bulk alloys. The Seebeck coefficient and power factor are synergistically improved by co-doping of In and Mn. In doping is known to introduce a resonance level. Mn doping reduces the separation of light- and heavy-valence bands. The combination of these effects significantly enhances the Seebeck coefficient at room temperature owing to around a factor of five times increase in the band effective mass. The reduction of thermal conductivity is from the decrease of both the electronic and phononic parts. The electronic thermal conductivity is decreased by the increase in defect scattering, as can be confirmed by the carrier mobility. The force constant of the bonds around the Te site is decreased due to the co-doping of In & Mn, which indicates that the chemical bonds are softened, which leads to low sound velocity and lower lattice thermal conductivity. As a result, the peak thermoelectric figure of merit, zT = 1.03 has been achieved for Sn0.89In0.01Mn0.1Te at 923 K. This strategy of using the synergistic effect of band structure modification and chemical bond softening could be applicable to other thermoelectric materials.

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