Dielectric Screening by 2D Substrates

While electronic screening within 2D materials has been studied extensively, the question of how 2D substrates screen charge perturbations or electronic excitations adjacent to them still remains.

In this work, we use first principles calculations to study the fully non-local dielectric screening properties of 2D material substrates. Our calculations give results in good qualitative agreement with those from electrostatic force microscopy (EFM) and Kelvin probe force miscroscopy (KPFM) experiments, indicating that the experimentally observed thickness-dependent screening effects and reduced charge potential fluctuations are intrinsic to 2D materials.

2D material substrates can also dramatically change the HOMO-LUMO gaps of small molecule adsorbates. We suggest an easy and reliable method to predict the HOMO- LUMO gaps of small physisorbed molecules on 2D and 3D substrates, using only the band gap of the substrate and the gas phase gap of the molecule.