Density functional theory of graphene/Cu phthalocyanine composite material

The molecular structure of graphene-copper phthalocyanine was predicted using the density functional theory with three different optimization methods, including local density approximation (LDA), generalized gradient approximation (GGA), and a conventional hybrid, B3LYP, functionals. Based on the molecular structure of graphene-copper phthalocyanine, some properties can be obtained. It was found that the distance between graphene sheet and the copper phthalocyanine molecule was about 3.155-3.734 Å. The adsorption of copper phthalocyanine molecule on the graphene layer was found to be a spontaneous process with the shortest distance between the two layers. In addition, the presence of the copper phthalocyanine molecule on the graphene layer resulted in a decrease of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap, and therefore, increased reactivity compared to isolated copper phthalocyanine and graphene. Thus, the presence of copper phthalocyanine can enhance charge transport in graphene, which leads to a high-quality transparent conductive material.