Theory of near-field electrostatic effects in supported and decorated 2D materials

Far-field electrostatic effecfs at interfaces are known to strongly modulate surface workfunctions through the areal dipole of the interface electronic density. However, for thin-films and integrated two-dimensional materials, the near-field effects resulting from higher moments of the interface electronic density may also impact optoelectronic properties. 

In this work, we derive a theory of such effects, and validate it through first-principles calculations. We develop a classical electrostatic model of the 2D materials / substrate interactions beyond the multipole expansion of the potential. Our theory captures the magnitude, modulations, and decay lengths of near-field effects using simple materials descriptors (i.e. atomic structures and charge density multipoles) [1].  and energy scales of the higher moments effects.

We discuss the implications of our theory for device functionality  showing how such effects allow to tune the momentum-dependent polarizability of a 2D metal as a function of its proximity to a metallic substrate [2], and can lead to bandgap opening for graphene  decorated by a phthalocyanine monolayer [1].