Two-dimensional (2D) materials, such as graphene, hexagonal boron nitride, and transition metal dichalcogenides (TMDs) have desirable optoelectronic properties. Key to their deployment into next generation devices is the ability to modulate their local carrier density (i.e., doping). In this work, we propose a new strategy to dope 2D materials by surface adsorption of organic molecules, with large electronic multipoles tunable by functional groups and orientation. Using density functional theory for prototypical self-assembled monolayers (SAM) on graphene, we show how SAM can tune the in-plane electronic energies of 2D materials and extract the characteristic length and energy scales of the electrostatic tuning. Our findings suggest that SAM can induce in-plane electric fields on the scale of 0.5V/nm allowing for a large and highly local doping of the 2D materials. We propose an electrostatic theory of the effects for arbitrary multipoles of the density.

Molecular doping of two-dimensional materials through self-assembled monolayers

ACS Spring Meeting 2021

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