Off-centering effect and crystal symmetry modification lead to high thermoelectric performance in diamondoid Cu<sub>2</sub>SnSe<sub>3</sub>
Recently, dimensionless figure of merit (ZT) beyond 1.0 has been demonstrated in diamondoid Cu<sub>2</sub>SnSe<sub>3</sub>, positioning it as a low-cost and ecofriendly thermoelectric alternative, and sparking intense interest in further optimizing its thermoelectric properti...
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Science Press
2025-03-01
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| Series: | National Science Open |
| Subjects: | |
| Online Access: | https://www.sciengine.com/doi/10.1360/nso/20250004 |
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| Summary: | Recently, dimensionless figure of merit (ZT) beyond 1.0 has been demonstrated in diamondoid Cu<sub>2</sub>SnSe<sub>3</sub>, positioning it as a low-cost and ecofriendly thermoelectric alternative, and sparking intense interest in further optimizing its thermoelectric properties. However, its intrinsic monoclinic structure and the compact packing of tetrahedral coordination lead to a light valence band and high thermal conductivity, which impede further performance improvement in Cu<sub>2</sub>SnSe<sub>3</sub>. Thus, developing effective approaches to altering the local structure of Cu<sub>2</sub>SnSe<sub>3</sub> is important for further optimizing its thermoelectric performance. Herein, we identified and thoroughly investigated the atomic off-centering behavior in Cu<sub>2</sub>SnSe<sub>3</sub>, and demonstrated the electronic and phonon transport properties of Cu<sub>2</sub>SnSe<sub>3</sub> can be significantly enhanced by carefully modifying its monoclinic lattice into a distorted zinc-blende cubic structure via introducing Cd and off-centering Ag elements. This structure transition leads to band convergence and a reduction in the deformation potential of the material, resulting in a 7-fold enhancement in the density-of-state effective mass and an 85% increase in carrier mobility. Additionally, the off-centering effect results in strong acoustic-optical phonon scattering and an ultra-low lattice thermal conductivity of <sc>0.3 W m<sup>−1</sup> K<sup>−1</sup>.</sc> Consequently, a maximum ZT of 1.3 was obtained at <sc>800 K</sc> for the Cu<sub>1.85</sub>Ag<sub>0.15</sub>Sn<sub>0.9</sub>Cd<sub>0.1</sub>Se<sub>3</sub>. |
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| ISSN: | 2097-1168 |