Electronic Structure and Optical Absorption of Fluorographene

TL;DR

This study uses advanced first-principles calculations to analyze fluorographene's electronic and optical properties, revealing significant excitonic effects and a large band gap increase, with implications for optoelectronic applications.

Contribution

It provides a detailed first-principles analysis of fluorographene's quasiparticle energies and optical absorption, highlighting excitonic effects and explaining experimental photoluminescence.

Findings

Band gap increased from 3.0 eV to 7.3 eV by GW approximation.

Optical spectrum dominated by bright excitons around 9.0 eV.

Lowest exciton at 3.8 eV with 3.5 eV binding energy.

Abstract

A first-principles study on the quasiparticles energy and optical absorption spectrum of fluorographene is presented by employing the GW + Bethe-Salpeter Equation (BSE) method with many-electron effects included. The calculated band gap is increased from 3.0 eV to 7.3 eV by the GW approximation. Moreover, the optical absorption spectrum of fluorographene is dominated by enhanced excitonic effects. The prominent absorption peak is dictated by bright resonant excitons around 9.0 eV that exhibit a strong charge transfer character, shedding light on the exciton condensation and relevant optoelectronic applications. At the same time, the lowest-lying exciton at 3.8 eV with a binding energy of 3.5 eV is identified, which gives rise to explanation of the recent ultraviolet photoluminescence experiment.