The Effects of Ge Doping on the Thermoelectric Performance of Polycrystalline SnSe.
Tessera Alemneh Wubieneh1,2,3*, Yang-Yuan Chen2
1Department of Physics, National central University, Taoyuan, Taiwan
2Academia Sinica, IOP, Taipei, Taiwan
3MSTP, IAMS, Taipei, Taiwan
* presenting author:Tessera Alemneh Wubieneh,
Recently single crsystal SnSe has attracted much attention due to its unprecedented high zT (~2.6) value, which has stimulated curiosity to study its polycrystalline counterparts by effective doping. The polycrystalline (Sn1-xGex)Se specimens were prepared by melting and spark plasma sintering (SPS) to improve the thermoelectric performance and mechanical property of pristine SnSe. This study systematically investigated the Ge doping effects and discussed the anisotropic behavior on the thermoelectric (TE) properties of SPS-sintered (Sn1-xGex)Se samples. We found that Ge doping not only results in a remarkable enhancement of Seebeck coefficient but also reduces the thermal conductivity of (Sn1-xGex)Se series. All Ge-doped compounds show a low thermal conductivity, which is mainly attributed to phonon scattering from disordered dopant atoms and high anharmonicity bonding nature of SnSe. This led to a maximum zT of 0.77 was obtained at 800 K for (Sn0.99Ge0.01)Se, which shows an approximately 40 % enhancement over the pristine polycrystalline SnSe (zT =0.56). consequently, (Sn1-xGex)Se is a promising candidate for highly effiecent thermoeletric materials.

Keywords: Thermoelectric , Seebeck Coefficient , thermal conductivity