Striped Phase Formations of Alkanethiols in Au(111)/Graphene/SAM and Au(111)/SAM/Graphene Heterolayered Structures: Insights from vdW-DFT Calculations

The heterolayered Au(111)/Graphene/Alkanethiol and Au(111)/Alkanethiol/Graphene structures have been investigated using van der Waals supplemented density functional theory (vdW-DFT) calculations considering striped phases of decanethiol and octanethiol self-assembled monolayers (SAMs) with (6 x root 3) and (12 x root 3) superlattices of graphene and Au(111). For the thiol-based SAMs on gold, graphene not only acts as a protective top layer but also enhances the adsorption energy of alkanes and modifies surface electronic properties. Deposition of alkanethiol molecules on Au(111)-supported graphene is likely to show distinctive flexibility and adsorption characteristics. Electronically, graphene preserves its Dirac conicals and becomes a p-type material in the combined systems. The work functions of the resulting geometries mainly depend on the ordering and the number of the heterolayers as well as on the molecular arrangements.