Enhanced Thermoelectric Power in Graphene: Violation of the Mott Relation by Inelastic Scattering

Abstract

We report the enhancement of the thermoelectric power (TEP) in graphene with extremely low disorder. At high temperature we observe that the TEP is substantially larger than the prediction of the Mott relation, approaching to the hydrodynamic limit due to strong inelastic scattering among the charge carriers. However, closer to room temperature the inelastic carrier-optical-phonon scattering becomes more significant and limits the TEP below the hydrodynamic prediction. We support our observation by employing a Boltzmann theory incorporating disorder, electron interactions, and optical phonons.

First-principles study of the electrical and lattice thermal transport in monolayer and bilayer graphene

“…Enhancement of S by inelastic scattering has been reported recently by Ghahari et al [18]. Experimental electrical conductivity studies of graphene doped with potassium as a function of charge carrier has been reported by Chen et al [11].…”

“…A further motivation to study the effects of impurity scattering on graphene sheets was provided by a recent paper by Ghahari et al [18], which reported an enhanced Seebeck coefficient in graphene due to scattering. We have used a tight-binding model (TBM) for graphene with impurities and solved the Boltzmann transport equations for electrons to study the effect of impurities on electrical conductance.…”

“…We have used a tight-binding model (TBM) for graphene with impurities and solved the Boltzmann transport equations for electrons to study the effect of impurities on electrical conductance. Our study used a large k mesh to capture correctly the enhancement of the Seebeck coefficient and a constant decrease in electrical conductivity due to doping and decrease in mobility by an order of magnitude as observed experimentally [10,11,18].…”

Strained-graphene-based highly efficient quantum heat engine operating at maximum power

“…Recent works show that graphene is a good thermoelectric material with a moderate Seebeck coefficient 10,11 . Though, due to its high thermal conductance, it possesses a very small thermoelectric figure of merit ZT around 0.1-0.001, much smaller than the most efficient 3D thermoelectric material Bi 2 Te 3 .…”

High thermoelectricpower factor in graphene/hBN devices

“…In the calculation, inelastic electronphonon interaction is not included because the screened Coulomb scattering is dominant in this temperature range as indicated by the energy scale of the RPF. However, electron-phonon scattering could become important when the temperature yields a k B T that is much higher than the energy of RPF as in the case for hBN-encapsulated graphene devices (43).…”