Thermoelectric properties of gamma-graphyne nanoribbon incorporating diamond-like quantum dots

Abstract

The ballistic thermoelectric properties of γ-graphyne nanoribbons incorporating diamond-like quantum dots are theoretically investigated by means of a nonequilibrium Green's function. The calculation shows that as the diamond-like quantum dot is introduced, the thermoelectric conversion efficiency can be enhanced dramatically. Such enhancement mainly stems from the significant suppression of phononic and electronic thermal conductance and the reserved high Seebeck coefficient. Meanwhile, variation of the geometric size of the quantum dot will result in an obvious oscillatory behavior of thermoelectric performance, which is attributed to the resonant electronic conductance caused by the quasi-bound state in diamond-like quantum dots. When the nanoribbon is embedded with multi-quantum dots, we find that the thermoelectric efficiency can be improved further (the stable figure of merit can achieve 1.55 even at room temperature). These findings demonstrate the incorporation of diamond-like quantum dots is a viable approach to optimize the thermoelectric performance of γ-graphyne, and could provide helpful guidance for designing and fabricating nanoscale thermoelectric devices.