Spontaneous exciton dissociation in carbon nanotubes

TL;DR

This study demonstrates that excitons in single-walled carbon nanotubes can spontaneously dissociate into free carriers during relaxation, providing insights into their photoconductivity despite high exciton binding energies.

Contribution

It reveals spontaneous exciton dissociation in carbon nanotubes and introduces a method to correlate optical and electrical signals for detailed exciton analysis.

Findings

Spontaneous exciton dissociation observed during relaxation.

Correlation of luminescence and photocurrent elucidates exciton behavior.

Extraction of absorption cross section and oscillator strength.

Abstract

Simultaneous photoluminescence and photocurrent measurements on individual single-walled carbon nanotubes reveal spontaneous dissociation of excitons into free electron-hole pairs. Correlation of luminescence intensity and photocurrent shows that a significant fraction of excitons are dissociating during their relaxation into the lowest exciton state. Furthermore, the combination of optical and electrical signals also allows for extraction of the absorption cross section and the oscillator strength. Our observations explain the reasons for photoconductivity measurements in single-walled carbon nanotubes being straightforward despite the large exciton binding energies.