Thermoelectric effect enhanced by the resonant states in graphene

TL;DR

This paper theoretically investigates how impurity-induced resonant states in graphene can significantly enhance thermoelectric properties, especially the Seebeck coefficient and figure of merit, by analyzing impurity scattering and relaxation times.

Contribution

It introduces a detailed theoretical model showing how resonant impurity states near the Fermi level boost thermoelectric efficiency in graphene.

Findings

Resonant impurity states near the Fermi level enhance the Seebeck coefficient.

The figure of merit ZT is increased due to impurity resonances.

Deviations from the Wiedemann-Franz law occur near resonant states and small chemical potentials.

Abstract

Thermoelectric effects in graphene are considered theoretically with particular attention paid to the role of impurities. Using the T -matrix method we calculate the impurity resonant states and the momentum relaxation time due to scattering on impurities. The Boltzmann kinetic equation is used to determine the thermoelectric coefficients. It is shown that the resonant impurity states near the Fermi level give rise to a resonant enhancement of the Seebeck coefficient and of the figure of merit $ZT$ . The Wiedemann-Franz ratio deviates from that known for ordinary metals, where this ratio is constant and equal to the Lorentz number. This deviation appears for small chemical potentials and in the vicinity of the resonant states. In the limit of a constant relaxation time, this ratio has been calculated analytically for $\mu=0$.