Exciton resonances quench the photoluminescence of zigzag carbon nanotubes

TL;DR

This paper demonstrates that exciton resonances suppress the photoluminescence of zigzag carbon nanotubes, making armchair tubes appear brighter, and provides a method to normalize luminescence for analyzing nanotube chirality distributions.

Contribution

It reveals the role of exciton resonances in quenching zigzag nanotube luminescence and introduces a normalization technique for chirality abundance analysis.

Findings

Exciton resonances weaken zigzag nanotube photoluminescence.

Armchair nanotubes exhibit stronger luminescence due to electronic structure.

Normalization method enables accurate chirality abundance estimation.

Abstract

We show that the photoluminescence intensity of single-walled carbon nanotubes is much stronger in tubes with large chiral angles - armchair tubes - because exciton resonances make the luminescence of zigzag tubes intrinsically weak. This exciton-exciton resonance depends on the electronic structure of the tubes and is found more often in nanotubes of the +1 family. Armchair tubes do not necessarily grow preferentially with present growth techniques; they just have stronger luminescence. Our analysis allows to normalize photoluminescence intensities and find the abundance of nanotube chiralities in macroscopic samples.