Tuning the van der Waals Interaction of Graphene with Molecules via Doping

TL;DR

This study demonstrates that doping graphene can modulate van der Waals interactions with molecules, with n-doping strengthening and p-doping weakening binding, supported by experimental measurements and theoretical calculations.

Contribution

It provides a quantitative understanding of how doping alters vdW interactions on graphene, combining experimental visualization and ab initio calculations.

Findings

N-doping strengthens molecule-graphene vdW binding.

P-doping weakens molecule-graphene vdW binding.

Theoretical models accurately reproduce experimental trends.

Abstract

We use scanning tunneling microscopy to visualize and thermal desorption spectroscopy to quantitatively measure that the binding of naphthalene molecules to graphene (Gr), a case of pure van der Waals (vdW) interaction, strengthens with $n$- and weakens with $p$-doping of Gr. Density functional theory calculations that include the vdW interaction in a seamless, ab initio way accurately reproduce the observed trend in binding energies. Based on a model calculation, we propose that the vdW interaction is modified by changing the spatial extent of Gr's $\pi$ orbitals via doping.