Light Control over Chirality Selective Functionalization of Substrate Supported Carbon Nanotubes

TL;DR

This paper presents a laser-based technique for chirality-selective functionalization of substrate-supported carbon nanotubes, enabling targeted optical modifications by matching laser frequency with nanotube transition energies.

Contribution

It introduces a novel on-device, light-controlled functionalization method that achieves chirality selectivity in carbon nanotubes using resonant laser irradiation.

Findings

Successful selective functionalization of (9,7) nanotubes confirmed by Raman spectroscopy.

Demonstrated red-shift in emission from electroluminescent device by 25 meV.

Method enables targeted optical property modification of individual nanotubes.

Abstract

Diazonium reactions with carbon nanotubes form optical $sp^3$ defects that can be used in optical and electrical circuits. We investigate a direct on-device reaction supported by confined laser irradiation and present a technique where an arbitrary carbon nanotube can be preferentially functionalized within a device by matching the light frequency with its transition energy. An exemplary reaction was carried out between (9,7) nanotube and 4-bromobenzenediazonium tetrafluoroborate. The substrate supported nanotubes of multiple semiconducting chiralities were locally exposed to laser light while monitoring the reaction kinetics in-situ via Raman spectroscopy. The chiral selectivity of the reaction was confirmed by resonant Raman spectroscopy, reporting a 10 meV $E_{22}$ transition energy red-shift only of the targeted species. We further demonstrated this method on a single tube (9,7) electroluminescent device and show a 25 meV red-shifted emission of the ground state $E_{11}$ compared to the emission from the pristine tubes.