Thermoelectric Properties of Transition Metal Dichalcogenides: From Monolayers to Nanotubes

Thermoelectric material has the unique ability to directly convert waste heat into electricity, and theoretical guidance is an efficient method for exploring high-performance nanostructured thermoelectric materials. By using first-principles method, we systematically present the ballistic thermoelectric properties of four representative series of transition metal dichalcogenides (WSe2, MoSe2, WS2, and MoS2), each including monolayer, zigzag (10, 0), and armchair (6, 6) nanotubes. Consistent regularity can be seen for each considered series. From monolayer to small nanotubes, degeneration of thermoelectric figure of merit is observed, which indicates that transition metal dichalcogenide monolayers exhibit better thermoelectric performance than the small nanotubes. In addition, it is interesting to find out the divergence pattern with regard to the phononic thermal conductance, which points out that the room-temperature phononic thermal conductance of monolayers is bigger than that of zigzag (10, 0) nanotube but lower than that of armchair (6, 6) nanotube.