Changes in electronic structure of graphene by adsorption of low melamine coverages

Abstract

Using first-principles simulations at Density Functional Theory (DFT) level, we concluded a comprehensive study of the molecular doping of graphene by melamine adsorption. We characterized the different possible positions achieved by the molecule on a pristine graphene or a Stone-Wales defect (5-7-7-5) were characterized. We also analyzed adsorption energies, deformations experienced by melamine and charge separation involved in the process. The defective graphene sheet turned out to be more flexible than the pristine one, exhibiting greater deformations. Melamine adsorption on Stone-Wales defect is preferred and it can be used as a useful strategy to carry out the molecular doping of graphene. Due to adsorption, a charge separation is generated between melamine and graphene, giving rise to an organic/organic interface with a net interfacial dipole. This change in the electronic structure of graphene favors the dynamics of the excited electronic state, tuning it an interesting material used in optoelectronic devices.