▎ 摘　　要

We have investigated the energetics and work function (WF) of graphene (GR) with depositing pentacene (C22H14, PEN) and perfluorinated pentacene (C22F14, PFP) using the electronic structure calculations based on the density functional theory with van der Waals (vdW) corrections. Both molecules are adsorbed on GR in flat-laying form with the height of 3.2 angstrom through vdW interaction, and no explicit exchange of electrons was found between GR and adsorbed molecules. However, we found charge redistribution in the surface to interface region and this brings about the vacuum level shifts, Delta = -0.06 eV for PEN and Delta = +0.10 eV for PFP, demonstrating that the work function of GR can be tuned by the physisorption of organic molecules.