▎ 摘　　要

In this paper a comprehensive model to investigate the thermionic emission from few layer graphene (FLG) structures operating at finite temperature (7) and its feasibility towards thermionic energy conversion scheme as cathode, has been proposed. Taking into account the stacking dependent energy dispersion for the evaluation of density of states of Fermionic electrons and Fowler's treatment of the electron emission, the analytical expressions for the thermionic flux from ABA/ABC stacked FLG surfaces have been derived and shown to be an increasing function of number of constituent layers (N). In contrast to the usual RD law (alpha T-2) thermionic flux -temperature scaling, ABA and ABC stacked FLG have been identified to display alpha T-3 and alpha T1+2/N temperature scaling. Utilizing the competence of FLGs to deliver substantial thermionic flux in fabricating the FLG based cathodes, an appropriate operating regime for the constituent parameters of the thermionic convertors (TCs) describing efficient energy conversion, has been specified. As a remarkable feature, FLG based cathodes provide flexibility to operate TC at low cathode (and high anode) temperature, with a sustained optimum efficacy (equal to the monolayer graphene). As an illustrative case, a TC configured with FLG based cathode (N = 10, ABA stacking, similar to 900 K) and low work function (Cesium coated) metallic anode (2.0 V, 400 K) has been identified to display similar to 55% of the conversion efficiency (equivalent to similar to 2% of the Carnot efficiency). On the basis of analytical formulation, appropriately tuned FLG based cathode operating at low temperature, is proposed as a promising contrivance in achieving efficient energy conversion of heat into electrical power. (C) 2017 Elsevier Masson SAS. All rights reserved.