Thermoelectric properties of SnSe nanoribbons: a theoretical aspect

Bulk SnSe is reported to be an excellent thermoelectric material at high temperatures. We now present the results on thermoelectric properties of nanoribbons of SnSe of variable widths obtained using density functional theory coupled with semi-classical Boltzmann theory. The calculated results find armchair nanoribbons of width <= 47 angstrom to be semiconducting and zigzag nanoribbons of width <= 52 angstrom to be metallic. A relatively high Seebeck coefficient (approximate to 1720 mu V K-1) and low thermal conductivity was calculated for the armchair nanoribbon of 6 angstrom width, while a large relaxation time and small effective mass was obtained for the armchair nanoribbon of 47 angstrom width. The calculated results suggest that patterning SnSe into nanoribbons may provide thermoelectric performance that is similar to the monolayer and low-temperature bulk phases of SnSe.