Electron Thermionic Emission from Graphene and a Thermionic Energy Converter

Abstract

A simple means to convert waste heat into electrical energy is thermionic emission, in which the thermal energy of a hot cathode exceeds the work function for electrons to evaporate from its surface, for subsequent collection at a cold anode. Here thermionic emission from a monolayer of suspended graphene has been reconsidered, to account for the electrons in this material behaving like massless fermionic quasiparticles. The authors predict a scaling of current density as ${T}^{3}$, as opposed to the ${T}^{2}$ scaling predicted for metals by the traditional Richardson-Dushman equation. The efficiency of the authors' proposed thermionic energy converter is about 45% at relatively low temperatures, with high current capability.