Investigation On Field Emission Properties Of Graphene-C70 Nano-composite Structures

The field emission properties of cathode materials become more and more important,owing to the development and application of field emission display.And the research on cathode materials becomes the core work of developing field emission displays.Graphene becomes the field emission material of a new generation that can substitute for the metallic tip materials and has the enormous potentiality to be a cathode material of filed mission display.In order to develop the application potential and commercial value in the field of field emission,graphene was compounded with other existing field mission cathode materials to create a new cathode material.Therefore,following the tendency of research,we compound graphene with other carbon material and study if the composite has the more excellent field emission properties.The work that we have done is following.(1)A graphene-C70 composite has been built by using Material Studio based on firstprinciple theory.And DMOL3 has been used to conduct the wiener scale simulated calculation under different electric filed.In this paper,we calculated the binding energy,work function(WF),ionization potential(IP)and electron affinity(EA)of the composite with the different electric field,and analyzed the molecular orbital energy levels and electron density distribution.The results suggests that the binding energy of the composite decreases with the increasing electric field.It indicates that the stability of the composite is enhanced with the increasing electric field.What is more,the WF and IP of the composite are reduced as well with the enhancing electric field.It makes the emission of electrons become easier.Under the effect of the electric field,the molecular orbital energy levels and their energy gap also have a trend of decrease.It is a good trend for field emission.All above shows that the composite has the good properties of filed mission and has the potential for cathode material of field emission.(2)Based on the pristine graphene-C70 composite,A B atom is used to replace a C atom from the C70 to modify the properties of pristine composite.We built 7 different Bdoped graphene-C70 composites and calculated their binding energy,WF,IP and EA and so on and analyzed the change of molecular orbital energy levels to survey the improvement for B atom doping to the different place of the pristine composite.The results show that the trend of the binding energy,WF,IP,EA and molecular orbital energy levels have little change after the B atom replacing the C atom.And the index have the great improvement to improve the properties of the pristine composite.(3)In the same doping way,we doped 7 N atoms to the different places of the pristine composite respectively and hence built the 7 different N-doped graphene-C70 composites.In order to have an obvious contrast,the binding energy,WF,IP,EA had been calculated and the molecular orbital energy levels had been analyzed in the different electric field.The results indicate that all N-doped composites have better field emission properties than the pristine composite but the B-doped composites.