Effect of quantum interference and doping on thermoelectric performance in GYNR and GYCNNR molecular junctions with PBCF-graphene nanoribbon electrodes

Abstract

In carbon-based molecule rings, quantum interference and doping can be employed to enhance the thermoelectric properties by controlling charge transport. Towards this goal, we investigate the thermoelectric performance of GYNR and GYCNNR molecular junctions with PBCF-graphene nanoribbon electrodes by applying the nonequilibrium Green’s function technique and Landauer transport theory. The results reveal that the thermoelectric properties can be greatly enhanced in both GYNR and GYCNNR molecular junctions at positive energies where manifests a constructive quantum interference. While in negative energy region, their thermoelectric performances are very low due to destructive quantum interference. Especially, the nitrogen-atom doped L-GYCNNR-M-PBCFs can obviously suppress phonon transport, resulting in a lower phonon thermal conductance, and effectively tune the electronic properties and seebeck coefficient. Furthermore, the length of carbon chain between GYNR (or GYCNNR) and BCF-graphene nanoribbon electrodes can also significantly regulate the electronic transport properties and thermoelectric performance. As a result, the figure-of-merit will be over 2 in L-GYNR-M-PBCF, and over 5.5 in L-GYCNNR-M-PBCF at room temperature.