Enhancement of thermoelectric figure of merit in zigzag graphene nanoribbons with periodic edge vacancies

TL;DR

This study demonstrates that periodic edge vacancies and antidot arrays significantly enhance the thermoelectric figure of merit in zigzag graphene nanoribbons by inducing a band gap and increasing the Seebeck coefficient.

Contribution

It introduces a novel approach of combining periodic edge vacancies and antidot arrays to improve thermoelectric performance in graphene nanoribbons.

Findings

Periodic edge vacancies open a band gap and create degenerate energy levels.

Seebeck coefficient increases markedly with specific vacancy arrangements.

Combining edge defects with antidot arrays further enhances thermoelectric efficiency.

Abstract

The influence of periodic edge vacancies and antidot arrays on the thermoelectric properties of zigzag graphene nanoribbons is investigated. Using the Green's function method, the tight-binding approximation for the electron Hamiltonian and the 4th nearest neighbor approximation for the phonon dynamical matrix, we calculate the Seebeck coefficient and the thermoelectric figure of merit. It is found that, at a certain periodic arrangement of vacancies on both edges of zigzag nanoribbon, a finite band gap opens and almost twofold degenerate energy levels appear. As a result, a marked increase in the Seebeck coefficient takes place. It is shown that an additional enhancement of the thermoelectric figure of merit can be achieved by a combination of periodic edge defects with an antidot array.