Copper-phthalocyanine (CuPc) and O, Li and Mn adatoms on graphene substrate: First-principles study of stability, magnetism and electronic properties

Abstract

The effects of adatoms of Oxygen (O), Lithium (Li) and Manganese (Mn) on the adsorption properties of copper-phthalocyanine molecule on a graphene substrate have been investigated using the spin-polarized density functional theory (DFT) calculations. The effects of van der Waals dispersion correction of the type vdW-DF2 is also investigated. This work extends our earlier work (J.F. Matoko-Ngouma et. al., J. Mol. Struct., 1211 (2020) 128034) on molecular CuPc adsorption on a graphene substrate. Here, our structural models consist of CuPc having an adatom of X = Li, Mn and O at a stable site, i.e., X-CuPc, with the latter deposited on a graphene substrate in a configuration we have named X-CuPc/graphene. Also, we have considered structural models wherein CuPc is deposited on a X-decorated graphene, i.e., CuPc/X-graphene. Our results show that X-CuPc/graphene and CuPc/X-graphene structures are stable. In fact, we have found that the Li and Mn adatoms increase the binding of CuPc to the graphene substrate as evidenced by the increase in the adsorption energy of CuPc to graphene (CuPc/graphene) upon the aforementioned adatom adsorption. However, the Oxygen atom does not have significant effect on the relative stability of CuPc adsorption on graphene. Regarding the magnetization, incorporating O and Mn as an adatom in CuPc/graphene system enhance its magnetization while Li quenches the magnetization of CuPc when it is adsorbed with or without the graphene substrate. Our findings underline the possibility to improve molecular adsorption of phthalocyanine molecules on graphene and to manipulate its magnetization through the incorporation of external atoms such as Li, Mn and O. This may be consequential in the development of molecular electronics, spintronics and nanosensors.