Strong Light-Matter Coupling in Carbon Nanotubes as a Route to Exciton Brightening

TL;DR

This paper demonstrates that strong light-matter coupling in optical microcavities can enhance the luminescence of carbon nanotubes by altering exciton energy states, enabling more efficient optical emission.

Contribution

It introduces a theoretical method to use exciton-polariton states in microcavities to prevent dark exciton quenching in carbon nanotubes, improving their optical emission.

Findings

Strong coupling creates hybrid exciton-polariton states.

Lower polariton energy can be tuned below dark exciton energy.

This approach can enhance nanotube luminescence efficiency.

Abstract

We show that strong light-matter coupling can be used to overcome a long standing problem that has prevented efficient optical emission from carbon nanotubes. The luminescence from the nominally bright exciton states of carbon nanotubes is quenched due to the fast nonradiative scattering to the dark exciton state having a lower energy. We present a theoretical analysis to show that by placing carbon nanotubes in an optical microcavity the bright exctonic state may be split into two hybrid exciton-polariton states, while the dark state remains unaltered. For sufficiently strong coupling between the bright exciton and the cavity, we show that the energy of the lower polariton may be pushed below that of the dark exciton. This overturning of the relative energies of the bright and dark excitons prevents the dark exciton from quenching the emission. Our resutls pave the way for a new approach to band-engineering the properties of the nanoscale optoelectronic devices.