Giant Quasiparticle Bandgap Modulation in Graphene Nanoribbons Supported on Weakly Interacting Surfaces

TL;DR

This study reveals that dielectric screening from substrates significantly reduces the bandgap in graphene nanoribbons, even with weak interactions, highlighting the importance of substrate effects in nanostructure electronic properties.

Contribution

The paper demonstrates through GW calculations that substrate dielectric screening can strongly suppress GNR bandgaps, a factor previously underexplored in theoretical studies.

Findings

Bandgaps in GNRs can be suppressed by up to 1 eV due to substrate effects.

Weak GNR-substrate interactions still lead to significant electronic property modifications.

Dielectric screening plays a crucial role in the electronic behavior of supported nanostructures.

Abstract

In general, there are two major factors affecting bandgaps in nanostructures: (i) the enhanced electron-electron interactions due to confinement and (ii) the modified self-energy of electrons due to the dielectric screening. While recent theoretical studies on graphene nanoribbons (GNRs) report on the first effect, the effect of dielectric screening from the surrounding materials such as substrates has not been thoroughly investigated. Using large-scale electronic structure calculations based on the GW approach, we show that when GNRs are deposited on substrates, bandgaps get strongly suppressed (by as much as 1 eV) even though the GNR-substrate interaction is weak.