| One alternative way to high thermoelectric performance: the intrinsically low thermal conductivity |
| Li-Dong Zhao |
| Beihang University |
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Thermoelectric materials, capable of converting waste heat into electrical power and vice versa, are currently receiving a significant scientific attention. The efficiency of a thermoelectric device is determined by ZT, ZT = (S2¥ò/¥ê)T, where S, ¥ò, ¥ê and T are the Seebeck coefficient, the electrical conductivity, the thermal conductivity, and the temperature, respectively. S and ¥ò must both be large, while ¥ê must be minimized. However, the high ZT is challenged by the interdependent relationships for these parameters. Several approaches to enhance ZT have emerged in the last decades,1 including band structure engineering to enhance Seebeck coefficients, nanostructuring and all-scale hierarchical architecturing to reduce thermal conductivity, and band alignment to maintain hole mobility. Alternatively, one can also seek high thermoelectric performance in pristine materials with intrinsically low thermal conductivity.2 In this talk, some typical compounds, SnSe,3 BiCuSeO,2 BiAgSeS,4 are presented as promising thermoelectric materials. Their high performances are mainly due to their intrinsically low thermal conductivity, which may arise from a large anharmonicity, lone pair electrons, a large molecular weight, a complex crystal structure, charge density wave distortions, etc.
References:
[1] L.-D. Zhao, et al. Energy Environ. Sci. 7 (2014) 251-268.
[2] L.-D. Zhao, et al. Energy Environ. Sci. 7 (2014) 2900-2924.
[3] L.-D. Zhao, et al. Nature 508 (2014) 373-377.
[4] Y. L. Pei, et al. Energy Environ. Sci. 6 (2013) 1750-1755.
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| Acknowledgements : This contribution was partly supported by the ¡°zhuoyue¡± program of Beihang University. I am grateful to Professor Mercouri G. Kanatzidis for fruitful collaborations. Of course most of all, I am grateful to the numerous dedicated collaborators who have contributed to our thermoelectric research efforts, their names appear in this talk. |
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