Tuning the Electronic Structure of Two-Dimensional Materials through Molecular Assembly*

The areal dipole of organic monolayers assembled on surfaces is known to alter significantly the surface workfunction. In this work, inspired by recent progresses in molecular assembly and in two-dimensional (2D) device synthesis, we examine how organic molecules can be used to tune the electronic structure of 2D materials through higher moments of their charge densities.
Using density functional theory calculations of graphene decorated with self-assembled monolayers (SAMs), we show that this effect can induce significant in-plane modulation of the electrostatic potential (> 0.1V/nm) for typical SAMs.
We develop a classical electrostatic model of the SAM-2D materials interactions, that captures the characteristic length and energy scales of the higher moments effects, and discuss its implications for device functionality.