Enhancement of the Seebeck effect in bilayer armchair graphene nanoribbons by tuning the electric fields

Abstract

The Seebeck coefficient in single and bilayer graphene sheets has been observed to be modest due to the gapless characteristic of these structures. In this work, we demonstrate that this coefficient is significantly high in quasi-1D structures of bilayer armchair graphene nanoribbons (BL-AGNRs) thanks to the open gaps induced by the quantum confinement effect. We show that the Seebeck coefficient of BL-AGNRs is also classified into three groups 3p, 3p + 1, 3p + 2 as the energy gap. And for the semiconducting BL-AGNR of width of 12 dimer lines, the Seebeck coefficient is found as high as 707 μV/K and it increases up to 857 μV/K under the impact of the vertical electric field. While in the semimetallic structure of width of 14 dimer lines, the Seebeck coefficient remarkably enhances 14 times from 40 μV/K to 555 μV/K. Moreover, it unveils an appealing result as the Seebeck coefficient always increases with the increase of the applied potential. Such BL-AGNRs appear to be very promising for the applications of the next generation of both electronic and thermoelectric devices applying electric gates.