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Y. Zhu, J. Carrete, Q. Meng, N. Mingo, P. Jiang, B. Xinhe:
"Independently tuning the power factor and thermal conductivity of SnSe via Ag₂S addition and nanostructuring";
Journal of Materials Chemistry A, 6 (2018), 7959 - 7966.

Single-crystal SnSe has been reported to exhibit ultralow thermal conductivity and high thermoelectric
performance. For future large-scale thermoelectric applications, however, polycrystalline SnSe would
offer more advantages. Unfortunately, its thermoelectric figure of merit (ZT) is much poorer than that of
single crystal. Improvements are challenging because the reduction in thermal conductivity is usually
accompanied by a degradation in the power factor. Here we report how the thermal conductivity of
polycrystalline SnSe can be reduced by Ag₂S addition and nanostructuring while avoiding this downside.
We investigated the thermoelectric properties of Ag₂S-added SnSe polycrystals in the range from 300 to
773 K. We obtained a peak ZT of 0.88 in SnSe with 1% Ag₂S addition (SS1), twice as high as pristine SnSe
(SS). The thermal conductivity is depressed even further in a nanostructured SnSe + 0.01Ag₂S sample
(SS1-Nano). More importantly, at high temperature the power factor remains as high as that of the SS1
sample. Due to a minimum thermal conductivity of 0.30 W m ^-1 K^-1, we obtained a maximum ZT of 1.13
in the SS1-Nano sample at 773 K.

http://dx.doi.org/10.1039/c8ta00608c