Many-Electron Effects on Optical Absorption Spectra of Strained Graphene

TL;DR

This study uses first-principles calculations to explore how uniaxial strain affects the electronic structure and optical absorption spectra of graphene, revealing anisotropic effects, peak splitting, and enhanced excitonic phenomena across a broad energy range.

Contribution

It introduces a comprehensive first-principles analysis of many-electron effects on strained graphene's optical properties, highlighting strain-induced anisotropy and excitonic enhancements.

Findings

Optical absorption becomes anisotropic under strain.

Single absorption peak splits into two with enhanced excitonic effects.

Strain causes a red shift in visible-light absorption, altering color and transparency.

Abstract

We employ the first-principles GW+Bethe Salpeter equation approach to study the electronic structure and optical absorption spectra of uniaxial strained graphene with many-electron effects included. Applied strain not only induces an anisotropic Fermi velocity but also tilts the axis of the Dirac cone. As a result, the optical response of strained graphene is dramatically changed; the optical absorption is anisotropic, strongly depending on the polarization direction of the incident light and the strain orientation; the characteristic single optical absorption peak from {\pi}-{\pi}* transitions of pristine graphene is split into two peaks and both display enhanced excitonic effects. Within the infrared regime, the optical absorbance of uniaxial strained graphene is no longer a constant because of the broken symmetry and associated anisotropic excitonic effects. Within the visible-light regime, we observe a prominent optical absorption peak due to a significant red shift by electron-hole interactions, enabling us to change the visible color and transparency of stretched graphene. Finally, we also reveal enhanced excitonic effects within the ultraviolet regime (8 to 15 eV), where a few nearly bound excitons are identified.