Edge-functionalized and substitutional doped graphene nanoribbons: electronic and spin properties

TL;DR

This study uses density functional theory to explore how chemical modifications, including edge functionalization and substitutional doping, affect the electronic and spin properties of graphene nanoribbons, revealing potential for spintronic applications.

Contribution

It provides a detailed analysis of how various chemical modifications influence the electronic and spin states of graphene nanoribbons, highlighting new pathways for tuning their properties.

Findings

Chemical modifications can break spin degeneracy in zigzag ribbons.

Edge functionalization minimally affects armchair ribbons' bandgap.

Substitutional doping can induce semiconducting-metal transitions.

Abstract

Graphene nanoribbons are the counterpart of carbon nanotubes in graphene-based nanoelectronics. We investigate the electronic properties of chemically modified ribbons by means of density functional theory. We observe that chemical modifications of zigzag ribbons can break the spin degeneracy. This promotes the onset of a semiconducting-metal transition, or of an half-semiconducting state, with the two spin channels having a different bandgap, or of a spin-polarized half-semiconducting state -where the spins in the valence and conduction bands are oppositely polarized. Edge functionalization of armchair ribbons gives electronic states a few eV away from the Fermi level, and does not significantly affect their bandgap. N and B produce different effects, depending on the position of the substitutional site. In particular, edge substitutions at low density do not significantly alter the bandgap, while bulk substitution promotes the onset of semiconducting-metal transitions. Pyridine-like defects induce a semiconducting-metal transition.