Mathematical models for thermionic emission current density of graphene emitter

Olukunle C Olawole,Sunday O Oyedepo,Dilip K De,Fabian I Ezema

doi:10.1038/s41598-021-01546-2

Abstract

In this study, five mathematical models were fitted in the absence of space charge with experimental data to find a more appropriate model and predict the emission current density of the graphene-based thermionic energy converter accurately. Modified Richardson Dushman model (MRDE) shows that TEC's electron emission depends on temperature, Fermi energy, work function, and coefficient of thermal expansion. Lowest Least square value of S=sum {left({J}_{th}-{J}_{exp}right)}^{2}=0.0002 ,text{A}^{2}/text{m}^{4} makes MRDE most suitable in modelling the emission current density of the graphene-based TEC over the other four tested models. The developed MRDE can be adopted in predicting the current emission density of two-dimensional materials and also future graphene-based TEC response.

Highlights

In this study, five mathematical models were fitted in the absence of space charge with experimental data to find a more appropriate model and predict the emission current density of the graphene-based thermionic energy converter accurately
The developed MRDE can be adopted in predicting the current emission density of twodimensional materials and future graphene-based TEC response
Because of its unmatched prospects in electronics, thermal expansion, optical and mechanical properties, ease of tune-ability of its work function that is seen to operate in the 2D w orld[9,10,11,12,13,14,15] and graphene’s tolerance of high temperature[16]

Summary

Introduction

Five mathematical models were fitted in the absence of space charge with experimental data to find a more appropriate model and predict the emission current density of the graphene-based thermionic energy converter accurately. As soon as the external load is attached to the setup in the presence of continuous supply of thermal energy from sunlight as depicted, the electrons at the cathode would have sufficient energy to overcome a surface barrier, migrate to the anode and drive electricity through the TEC. Despite enormous research in TEC, the TEC technology’s potential in generating electricity is still being hindered due to high material work function and space charge related p roblems[7,28,29,30]. This has led to the unnatural death of technology in the 90 s. The technologies that are primarily of interest for applying graphene-based TEC are graphene’s growth on solid tungsten and silicon carbide s ubstrates[16,31,32,33] and ease of work function engineering of graphene s urface[13,15,34,35,36]

Methods

Results

Conclusion