A gap opening in graphene covered by a conducting polymer: The role of many-body effects

Abstract

We study the adsorption of the conducting polymer poly-para-phenylene (PPP) on graphene using first-principles electronic structure calculations. In this article, we decided to investigate the role of polarization of the polymer on the band gap renormalization of the graphene sheet. For this purpose, we supposed that the polymer is lying flat on the sheet of graphene. The polymer adsorption has caused the polarization of graphene and vice versa. We demonstrate the anisotropic polarization of the polymer significantly affects the energy band structure of graphene by opening a gap at the Dirac point. Upon polymer adsorption, the conical shape of the graphene at the Dirac point is partially transformed and leads to opening the band gap about 260 meV at this point. This finding can change the metallic property of the graphene and created semiconducting property inside the compound. This result can only be explained by many-body effects which are treated within the G0W0 quasi-particle approximation while the Kohn-Sham single-particle band structure of graphene is hardly modified by the presence of the polymer. Our findings can be understood as a renormalization due to image charge effects on the anisotropic polymer chain.