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 Sn1−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 Sn0.99Ag0.01Se2 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%.