All-optical trion generation in single walled carbon nanotubes

TL;DR

This study demonstrates all-optical generation and emission of trions in undoped single-walled carbon nanotubes, revealing chirality-dependent properties and underlying mechanisms involving exciton-exciton interactions.

Contribution

It provides the first evidence of all-optical trion generation in undoped SWCNTs and elucidates the chirality dependence and physical processes involved.

Findings

Trion emission peaks are red-shifted relative to excitons.

Chirality dependence observed across 22 SWCNT species.

Exciton-exciton annihilation facilitates trion formation.

Abstract

We present evidence of all optical trion generation and emission in undoped single walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large CW excitation intensity range, show trion emission peaks red-shifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump probe experiments on chirality sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event.