High thermoelectric and mechanical performance in the n-type polycrystalline SnSe incorporated with multi-walled carbon nanotubes

In this study, we introduce multi-walled carbon nanotubes (MWCNTs) in Pb/I co-doped n-type polycrystal SnSe to simultaneously improve its thermoelectric and mechanical properties for the first time. The introduced MWCNTs act as the bridges to accelerate the electron carrier transport between SnSe grains, leading to significantly increased electrical conductivity from 32.6 to 45.7 S cm(-1) at 773 K, which contributes to an enhanced power factor of similar to 5.0 mu W cm(-1) K-2 at this temperature. Although MWCNTs possess high intrinsic thermal conductivities, these MWCNTs, acting as nanoinclusions in the SnSe matrix to form the dense interfaces between SnSe and MWCNTs, provide extra heat-carrying phonon scattering centers, leading to a slightly reduced lattice thermal conductivity of only 0.34 W( )m(-1) K-2 at 773 K and in turn, a high ZT of similar to 1.0 at this temperature. Furthermore, the introduced MWCNTs can simultaneously act as the binders to bond adjacent grains, significantly improving the mechanical properties of SnSe by boosting its Vickers hardness from 39.5 to 50.5. This work indicates that our facile approach can achieve high thermoelectric and mechanical properties in n-type SnSe polycrystals with a considerable potential for applying to thermoelectric devices as n-type elements. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, multi-walled carbon nanotubes (MWCNTs) were introduced into Pb/I co-doped n-type polycrystal SnSe to improve its thermoelectric and mechanical properties. The MWCNTs acted as bridges to enhance electron carrier transport between SnSe grains, resulting in increased electrical conductivity and power factor. As nanoinclusions in the SnSe matrix, the MWCNTs formed dense interfaces and provided extra heat-carrying phonon scattering centers, leading to reduced lattice thermal conductivity and high ZT. Additionally, the MWCNTs served as binders to improve the mechanical properties of SnSe.