Interplay between metavalent bonds and dopant orbitals enables the design of SnTe thermoelectrics

Engineering the electronic band structures upon doping is crucial to improve the thermoelectric performance of materials. Understanding how dopants influence the electronic states near the Fermi level is thus a prerequisite to precisely tune band structures. Here, we demonstrate that the Sn-s states in SnTe contribute to the density of states at the top of the valence band. This is a consequence of the half-filled p-p σ-bond (metavalent bonding) and its resulting symmetry of the orbital phases at the valence band maximum (L point of the Brillouin zone). This insight provides a recipe for identifying superior dopants. The overlap between the dopant s- and the Te p-state is maximized, if the spatial overlap of both orbitals is maximized and their energetic difference is minimized. This simple design rule has enabled us to screen out Al as a very efficient dopant to enhance the local density of states for SnTe. In conjunction with doping Sb to tune the carrier concentration and alloying with AgBiTe<sub>2</sub> to promote band convergence, as well as introducing dislocations to impede phonon propagation, a record-high average ZT of 1.15 between 300 and 873 K and a large ZT of 0.36 at 300 K is achieved in Sn<sub>0.8</sub>Al<sub>0.08</sub>Sb<sub>0.15</sub>Te-4%AgBiTe<sub>2</sub>.

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Publication Details

Journal
Nature Communications
Published
2024-10-23
DOI
https://doi.org/10.1038/s41467-024-53599-2
Citations
39
Primary Topic
Advanced Thermoelectric Materials and Devices
Type
article
Field-Weighted Citation Impact
4.57

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article

Interplay between metavalent bonds and dopant orbitals enables the design of SnTe thermoelectrics

Carl‐Friedrich Schön, Nan Lin, Matteo Cagnoni, Binghui Ge et al.
39 citations
Nature Communications
Advanced Thermoelectric Materials and Devices
4.57
article

Interplay between metavalent bonds and dopant orbitals enables the design of SnTe thermoelectrics

Carl‐Friedrich Schön, Nan Lin, Matteo Cagnoni, Binghui Ge, Pan Ying, Guodong Tang, Matthias Wuttig, Xuefei Miao, Xuemei Zhang, Yongsheng Zhang, Yuqi Liu, Yu Zhen Yuan, Dasol Kim, Kun Song, Pengfei Nan, Yaru Gong, Xiaoyu Yang
article en
39 citations

Abstract

Engineering the electronic band structures upon doping is crucial to improve the thermoelectric performance of materials. Understanding how dopants influence the electronic states near the Fermi level is thus a prerequisite to precisely tune band structures. Here, we demonstrate that the Sn-s states in SnTe contribute to the density of states at the top of the valence band. This is a consequence of the half-filled p-p σ-bond (metavalent bonding) and its resulting symmetry of the orbital phases at the valence band maximum (L point of the Brillouin zone). This insight provides a recipe for identifying superior dopants. The overlap between the dopant s- and the Te p-state is maximized, if the spatial overlap of both orbitals is maximized and their energetic difference is minimized. This simple design rule has enabled us to screen out Al as a very efficient dopant to enhance the local density of states for SnTe. In conjunction with doping Sb to tune the carrier concentration and alloying with AgBiTe<sub>2</sub> to promote band convergence, as well as introducing dislocations to impede phonon propagation, a record-high average ZT of 1.15 between 300 and 873 K and a large ZT of 0.36 at 300 K is achieved in Sn<sub>0.8</sub>Al<sub>0.08</sub>Sb<sub>0.15</sub>Te-4%AgBiTe<sub>2</sub>.

Nature CommunicationsVol. 15(1)
University of Science and Technology of China (CN), Nanjing Tech University (CN), Anhui University (CN), Forschungszentrum Jülich (DE), Politecnico di Torino (IT), Qufu Normal University (CN), Nanjing University of Science and Technology (CN), Ningxia Normal University (CN), Jülich Aachen Research Alliance (DE), Ministry of Education and Child Care (CA), RWTH Aachen University (DE), Ministry of Industry and Information Technology (CN)
National Natural Science Foundation of China, Natural Science Foundation of Ningxia Province, RWTH Aachen University
Openalex Percentile: Top 2%
Advanced Thermoelectric Materials and Devices
4.57
DOIOpen Access PDFOpenAlex
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