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Low temperature thermoelectric properties of single crystal SnSe

Improving the thermoelectric efficiency, given by the dimensionless figure of merit ZT, is one of the greatest challenges in materials science. A large value of ZT means a higher thermoelectric conversion efficiency, which requires a low thermal conductivity. Recently, ultra-low thermal conductivity and high thermoelectric figure of merit (2.6 at 973 K) have been experimentally found in threedimensional bulk SnSe by Zhao et al.[1]. Although physical properties of SnSe above room temperature are well investigated, there are very few studies of low temperature single- crystalline phase. In order to gain better comprehension of the intrinsic SnSe properties and to be able to improve its performance, we measured thermoelectric properties of SnSe at low temperatures. Here we present investigation of anisotropic thermal conductivity complemented with transport properties of SnSe at low temperatures. We find that the thermal conductivity features a pronounced umklapp maximum near 12K. Our results indicate that the lattice thermal conductivity of single- crystalline SnSe at room temperature is higher than those reported in the literature [1]. We further discuss possible reasons for the differences observed between our results and those previously obtained by Zhao et al. [1]. [1] Zhao, L. D., Lo, S. H., Zhang, Y., Sun, H., Tan, G., Uher, C., Wolverton, C., Dravid, V. P., Kanatzidis, M. G. Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals. Nature 508, 373 (2014).

single crystals, SnSe, termoelectric properties, Figure of merit

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