Exciton Energy Spectra in Two-Dimensional Graphene Derivatives

TL;DR

This paper investigates how quantum confinement affects exciton spectra in 2D graphene derivatives like graphyne and graphane, providing a simplified model to predict their optical properties and potential applications.

Contribution

It introduces a modified hydrogenic model to accurately describe exciton spectra in 2D graphene derivatives, enabling easier estimation of binding energies from optical data.

Findings

Quantum confinement significantly alters exciton spectra in 2D graphene derivatives.

A modified hydrogenic model effectively explains ab initio exciton spectra.

Graphyne shows promise for energy and biomedical applications due to its optical properties.

Abstract

The energy spectra and wavefunctions of bound excitons in important two-dimensional (2D) graphene derivatives, i.e., graphyne and graphane, are found to be strongly modified by quantum confinement, making them qualitatively different from the usual Rydberg series. However, their parity and optical selection rules are preserved. Thus a one-parameter modified hydrogenic model is applied to quantitatively explain the ab initio exciton spectra, and allows one to extrapolate the electron-hole binding energy from optical spectroscopies of 2D semiconductors without costly simulations. Meanwhile, our calculated optical absorption spectrum and enhanced spin singlet-triplet splitting project graphyne, an allotrope of graphene, as a candidate for intriguing energy and biomedical applications.