An efficient mechanism for enhancing the thermoelectricity of nanoribbons by blocking phonon transport in 2D materials

Inspired by the novel mechanism of reducing thermal conductivity by local phonon resonance instead of by inducing structural defects, we investigate the effect of side branching on the thermoelectric properties of MoS2 nanoribbons, and prove that side branching is a highly efficient mechanism for enhancing the thermoelectricity of different kinds of nanoribbons. For both armchair and zigzag MoS2 nanoribbons, the side branches result in not only significant blocking of phonon transport but also notable increase of the Seebeck coefficient. Consequently, the thermoelectric figure of merit of the armchair MoS2 nanoribbon is boosted from 0.72 to as high as 1.93, and the originally non-thermoelectric metallic zigzag MoS2 nanoribbon is turned into a thermoelectric material due to the appearance of the band gap induced by the side branches. These results mean that the mechanism of branching is not only very efficient, but also takes effect regardless of the original properties of the nanoribbons, and thus will hold great promise for its application in the thermoelectric field.