Numerical study on the field-emission properties of a graphene–C60 composite

A new model of a graphene–C60 composite is constructed to explore its electronic structure and field-emission characteristics. We investigate the structural stability, energy levels, local electron density distribution, work function, ionization potential, and Mulliken, Hirshfeld, and electrostatic potential fitting (ESP) charges of this composite by using first-principles methods. The results indicate that the electronic structure of the composite can be modulated obviously by applying an external electric field. The energy gap decreases as the electric field is increased, and the change in the local electron density distribution plays the role of a tip emission point. We find that the binding energy increases as the electric field is increased, which confirms that the assembly of graphene and C60 directly improves the stability of the compound and results in excellent semiconducting properties. With the increasing electric field, we also find that the work functions and ionization potentials of this composite decrease linearly, and the Mulliken, Hirshfeld and ESP charge move efficiently. All of those and the change of energy gap and the local electron density distribution show the improvement of graphene–C60 composite’s field emission properties. We conclude that the graphene–C60 composite may be a promising candidate for use in field-emission devices.