Strong charge-transfer excitonic effects and Bose-Einstein exciton-condensate in graphane

TL;DR

This paper uses first-principles calculations to show that graphane exhibits strong charge-transfer excitons with potential for Bose-Einstein condensation, driven by enhanced electron correlations in a 2D dielectric.

Contribution

It reveals the dominance of localized charge-transfer excitations and predicts the possibility of excitonic Bose-Einstein condensate in graphane, a novel 2D material.

Findings

Presence of small radius bound excitons with separated electron and hole

Strong electron-hole interactions dominate optical properties

Potential for observing excitonic Bose-Einstein condensate

Abstract

Using first principles many-body theory methods (GW+BSE) we demonstrate that optical properties of graphane are dominated by localized charge-transfer excitations governed by enhanced electron correlations in a two-dimensional dielectric medium. Strong electron-hole interaction leads to the appearance of small radius bound excitons with spatially separated electron and hole, which are localized out-of-plane and in-plane, respectively. The presence of such bound excitons opens the path on excitonic Bose-Einstein condensate in graphane that can be observed experimentally.