Ag-doped SnSe₂ as a promising mid-temperature thermoelectric material

This study has investigated the thermoelectric property of a layered metal dichalcogenide SnSe₂, which is also non-toxic and earth abundant, especially with a similar composition of SnSe whose single crystals are recently revealed to possess high thermoelectricity. By investigating the electrical and thermal transport properties of Sn_1−x Ag _x Se₂ (x = 0.00, 0.01, 0.03 and 0.05) in this work, it is revealed that the Ag-doped SnSe₂ has the potential as a good thermoelectric material used at mid-temperature, benefiting from its relatively low thermal conductivity below 1.0 Wm⁻¹ K⁻¹ and moderate power factor over 350 μWm⁻¹ K⁻² at 773 K. A ZT value of ~0.4 can be finally achieved for the composition of Sn_0.99Ag_0.01Se₂ at 773 K, which is an order of magnitude higher than the undoped ones and also larger than the reported metal dichalcogenides compounds of TiS₂ and WS₂. The present work also reveals that Ag-doped sample shows much better thermal stability over 700 K compared with the undoped one whose measured temperature is only limited to 573 K, even with a few mole doping content of 1%.