Band Degeneracy and Anisotropy Enhances Thermoelectric Performance from Sb2Si2Te6 to Sc2Si2Te6

Wenzhen Dou; Kieran B Spooner; Seán R Kavanagh; Miao Zhou; David O Scanlon

doi:10.1021/jacs.4c01838

Band Degeneracy and Anisotropy Enhances Thermoelectric Performance from Sb2Si2Te6 to Sc2Si2Te6

Wenzhen Dou, Kieran B Spooner, Seán R Kavanagh^*, Miao Zhou^*, David O Scanlon^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

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Abstract

The complex interrelationships among thermoelectric parameters mean that a priori design of high-performing materials is difficult. However, band engineering can allow the power factor to be optimized through enhancement of the Seebeck coefficient. Herein, using layered Sb2Si2Te6 and Sc2Si2Te6 as model systems, we comprehensively investigate and compare their thermoelectric properties by employing density functional theory combined with semiclassical Boltzmann transport theory. Our simulations reveal that Sb2Si2Te6 exhibits superior electrical conductivity compared to Sc2Si2Te6 due to lower scattering rates and more pronounced band dispersion. Remarkably, despite Sb2Si2Te6 exhibiting a lower lattice thermal conductivity and superior electrical conductivity, Sc2Si2Te6 is predicted to achieve an extraordinary dimensionless figure of merit (ZT) of 3.51 at 1000 K, which significantly surpasses the predicted maximum ZT of 2.76 for Sb2Si2Te6 at 900 K. We find the origin of this behavior to be a combined increase in band (valley) degeneracy and anisotropy upon switching the conduction band orbital character from Sb p to Sc d, yielding a significantly improved Seebeck coefficient. This work suggests that enhancing band degeneracy and anisotropy (complexity) through compositional variation is an effective strategy for improving the thermoelectric performance of layered materials.

Original language	English
Pages (from-to)	17679-17690
Number of pages	12
Journal	Journal of the American Chemical Society
Volume	146
Issue number	26
Early online date	18 Jun 2024
DOIs	https://doi.org/10.1021/jacs.4c01838
Publication status	Published - 3 Jul 2024

Bibliographical note

Acknowledgments
We thank Alex M. Ganose for insightful discussions regarding the electronic band structures of these compounds. We also thank Adair Nicolson for thoughtful discussions regarding the highest ZT of different materials in theory. Lastly, we extend our thanks to Wenjin Gao for his careful review of the manuscript and the Supporting Information. W.D, K.B.S., and D.O.S. acknowledge support from the European Research Council (grant 758345). S.R.K. acknowledges the EPSRC Centre for Doctoral Training in the Advanced Characterization of Materials (EP/S023259/1) for a PhD studentship. W.D and M.Z. acknowledge the support of the National Key R&D Program of China (2022YFF0708800), the Natural Science Foundation of Zhejiang Province (LZ22A040004), and the National Natural Science Foundation of China (11674042). W.D acknowledges the support of the international joint doctoral education fund of Beihang University. W.D, K.B.S., S.R.K., and D.O.S. acknowledge the support of the UCL Myriad and Kathleen High-Performance Computing Facilities (Myriad@UCL, Kathleen@UCL). W.D and M.Z. acknowledge the support of the High-Performance Supercomputing Center of Hangzhou International Innovation Institute of Beihang University and the Center for High-Performance Computing of Beihang University (BHHPC).

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title = "Band Degeneracy and Anisotropy Enhances Thermoelectric Performance from Sb2Si2Te6 to Sc2Si2Te6",

abstract = "The complex interrelationships among thermoelectric parameters mean that a priori design of high-performing materials is difficult. However, band engineering can allow the power factor to be optimized through enhancement of the Seebeck coefficient. Herein, using layered Sb2Si2Te6 and Sc2Si2Te6 as model systems, we comprehensively investigate and compare their thermoelectric properties by employing density functional theory combined with semiclassical Boltzmann transport theory. Our simulations reveal that Sb2Si2Te6 exhibits superior electrical conductivity compared to Sc2Si2Te6 due to lower scattering rates and more pronounced band dispersion. Remarkably, despite Sb2Si2Te6 exhibiting a lower lattice thermal conductivity and superior electrical conductivity, Sc2Si2Te6 is predicted to achieve an extraordinary dimensionless figure of merit (ZT) of 3.51 at 1000 K, which significantly surpasses the predicted maximum ZT of 2.76 for Sb2Si2Te6 at 900 K. We find the origin of this behavior to be a combined increase in band (valley) degeneracy and anisotropy upon switching the conduction band orbital character from Sb p to Sc d, yielding a significantly improved Seebeck coefficient. This work suggests that enhancing band degeneracy and anisotropy (complexity) through compositional variation is an effective strategy for improving the thermoelectric performance of layered materials.",

author = "Wenzhen Dou and Spooner, {Kieran B} and Kavanagh, {Se{\'a}n R} and Miao Zhou and Scanlon, {David O}",

note = "Acknowledgments We thank Alex M. Ganose for insightful discussions regarding the electronic band structures of these compounds. We also thank Adair Nicolson for thoughtful discussions regarding the highest ZT of different materials in theory. Lastly, we extend our thanks to Wenjin Gao for his careful review of the manuscript and the Supporting Information. W.D, K.B.S., and D.O.S. acknowledge support from the European Research Council (grant 758345). S.R.K. acknowledges the EPSRC Centre for Doctoral Training in the Advanced Characterization of Materials (EP/S023259/1) for a PhD studentship. W.D and M.Z. acknowledge the support of the National Key R&D Program of China (2022YFF0708800), the Natural Science Foundation of Zhejiang Province (LZ22A040004), and the National Natural Science Foundation of China (11674042). W.D acknowledges the support of the international joint doctoral education fund of Beihang University. W.D, K.B.S., S.R.K., and D.O.S. acknowledge the support of the UCL Myriad and Kathleen High-Performance Computing Facilities (Myriad@UCL, Kathleen@UCL). W.D and M.Z. acknowledge the support of the High-Performance Supercomputing Center of Hangzhou International Innovation Institute of Beihang University and the Center for High-Performance Computing of Beihang University (BHHPC).",

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doi = "10.1021/jacs.4c01838",

language = "English",

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T1 - Band Degeneracy and Anisotropy Enhances Thermoelectric Performance from Sb2Si2Te6 to Sc2Si2Te6

AU - Dou, Wenzhen

AU - Spooner, Kieran B

AU - Kavanagh, Seán R

AU - Zhou, Miao

AU - Scanlon, David O

N1 - Acknowledgments We thank Alex M. Ganose for insightful discussions regarding the electronic band structures of these compounds. We also thank Adair Nicolson for thoughtful discussions regarding the highest ZT of different materials in theory. Lastly, we extend our thanks to Wenjin Gao for his careful review of the manuscript and the Supporting Information. W.D, K.B.S., and D.O.S. acknowledge support from the European Research Council (grant 758345). S.R.K. acknowledges the EPSRC Centre for Doctoral Training in the Advanced Characterization of Materials (EP/S023259/1) for a PhD studentship. W.D and M.Z. acknowledge the support of the National Key R&D Program of China (2022YFF0708800), the Natural Science Foundation of Zhejiang Province (LZ22A040004), and the National Natural Science Foundation of China (11674042). W.D acknowledges the support of the international joint doctoral education fund of Beihang University. W.D, K.B.S., S.R.K., and D.O.S. acknowledge the support of the UCL Myriad and Kathleen High-Performance Computing Facilities (Myriad@UCL, Kathleen@UCL). W.D and M.Z. acknowledge the support of the High-Performance Supercomputing Center of Hangzhou International Innovation Institute of Beihang University and the Center for High-Performance Computing of Beihang University (BHHPC).

PY - 2024/7/3

Y1 - 2024/7/3

N2 - The complex interrelationships among thermoelectric parameters mean that a priori design of high-performing materials is difficult. However, band engineering can allow the power factor to be optimized through enhancement of the Seebeck coefficient. Herein, using layered Sb2Si2Te6 and Sc2Si2Te6 as model systems, we comprehensively investigate and compare their thermoelectric properties by employing density functional theory combined with semiclassical Boltzmann transport theory. Our simulations reveal that Sb2Si2Te6 exhibits superior electrical conductivity compared to Sc2Si2Te6 due to lower scattering rates and more pronounced band dispersion. Remarkably, despite Sb2Si2Te6 exhibiting a lower lattice thermal conductivity and superior electrical conductivity, Sc2Si2Te6 is predicted to achieve an extraordinary dimensionless figure of merit (ZT) of 3.51 at 1000 K, which significantly surpasses the predicted maximum ZT of 2.76 for Sb2Si2Te6 at 900 K. We find the origin of this behavior to be a combined increase in band (valley) degeneracy and anisotropy upon switching the conduction band orbital character from Sb p to Sc d, yielding a significantly improved Seebeck coefficient. This work suggests that enhancing band degeneracy and anisotropy (complexity) through compositional variation is an effective strategy for improving the thermoelectric performance of layered materials.

AB - The complex interrelationships among thermoelectric parameters mean that a priori design of high-performing materials is difficult. However, band engineering can allow the power factor to be optimized through enhancement of the Seebeck coefficient. Herein, using layered Sb2Si2Te6 and Sc2Si2Te6 as model systems, we comprehensively investigate and compare their thermoelectric properties by employing density functional theory combined with semiclassical Boltzmann transport theory. Our simulations reveal that Sb2Si2Te6 exhibits superior electrical conductivity compared to Sc2Si2Te6 due to lower scattering rates and more pronounced band dispersion. Remarkably, despite Sb2Si2Te6 exhibiting a lower lattice thermal conductivity and superior electrical conductivity, Sc2Si2Te6 is predicted to achieve an extraordinary dimensionless figure of merit (ZT) of 3.51 at 1000 K, which significantly surpasses the predicted maximum ZT of 2.76 for Sb2Si2Te6 at 900 K. We find the origin of this behavior to be a combined increase in band (valley) degeneracy and anisotropy upon switching the conduction band orbital character from Sb p to Sc d, yielding a significantly improved Seebeck coefficient. This work suggests that enhancing band degeneracy and anisotropy (complexity) through compositional variation is an effective strategy for improving the thermoelectric performance of layered materials.

U2 - 10.1021/jacs.4c01838

DO - 10.1021/jacs.4c01838

M3 - Article

C2 - 38889404

SN - 0002-7863

VL - 146

SP - 17679

EP - 17690

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 26

ER -

Band Degeneracy and Anisotropy Enhances Thermoelectric Performance from Sb2Si2Te6 to Sc2Si2Te6

Abstract

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