Excitonic Effects in the Optical Spectra of Graphene Nanoribbons

TL;DR

This paper provides first-principles calculations revealing strong excitonic effects in graphene nanoribbons, significantly impacting their optical spectra and potential optoelectronic applications.

Contribution

It introduces a detailed first-principles analysis of excitonic effects in armchair-edged graphene nanoribbons, highlighting their impact on optical properties.

Findings

Enhanced electron-hole binding energies (0.8-1.4 eV) in AGNRs.

Significant transfer of oscillator strength to exciton states.

Distinct excitonic characteristics across different AGNR families.

Abstract

We present a first-principles calculation of the optical properties of armchair-edged graphene nanoribbons (AGNRs) with many-electron effects included. The reduced dimensionality of the AGNRs gives rise to an enhanced electron-hole binding energy for both bright and dark exciton states (0.8-1.4 eV for GNRs with width w ~ 1.2 nm) and dramatically changes the optical spectra owing to a near complete transfer of oscillator strength to the exciton states from the continuum transitions. The characteristics of the excitons of the three distinct families of AGNRs are compared and discussed. The enhanced excitonic effects found here are expected to be of importance in optoelectronic applications of graphene-based nanostructures.