How to recognize clustering of luminescent defects in single-wall carbon nanotubes - UTU Research Portal

A1 Refereed original research article in a scientific journal

How to recognize clustering of luminescent defects in single-wall carbon nanotubes

Authors: Sebastian, Finn L.; Settele, Simon; Li, Han; Flavel, Benjamin S.; Zaumseil, Jana

Publisher: ROYAL SOC CHEMISTRY

Publishing place: CAMBRIDGE

Publication year: 2024

Journal: Nanoscale Horizons

Journal name in source: NANOSCALE HORIZONS

Journal acronym: NANOSCALE HORIZ

Volume: 9

Issue: 12

First page : 2286

Last page: 2294

Number of pages: 9

ISSN: 2055-6756

eISSN: 2055-6764

DOI: https://doi.org/10.1039/d4nh00383g

Web address : https://doi.org/10.1039/D4NH00383G

Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/458590284

Abstract

Semiconducting single-wall carbon nanotubes (SWCNTs) are a promising material platform for near-infrared in vivo imaging, optical sensing, and single-photon emission at telecommunication wavelengths. The functionalization of SWCNTs with luminescent defects can lead to significantly enhanced photoluminescence (PL) properties due to efficient trapping of highly mobile excitons and red-shifted emission from these trap states. Among the most studied luminescent defect types are oxygen and aryl defects that have largely similar optical properties. So far, no direct comparison between SWCNTs functionalized with oxygen and aryl defects under identical conditions has been performed. Here, we employ a combination of spectroscopic techniques to quantify the number of defects, their distribution along the nanotubes and thus their exciton trapping efficiencies. The different slopes of Raman D/G+ ratios versus calculated defect densities from PL quantum yield measurements indicate substantial dissimilarities between oxygen and aryl defects. Supported by statistical analysis of single-nanotube PL spectra at cryogenic temperatures they reveal clustering of oxygen defects. The clustering of 2-3 oxygen defects, which act as a single exciton trap, occurs irrespective of the functionalization method and thus enables the use of simple equations to determine the density of oxygen defects and defect clusters in SWCNTs based on standard Raman spectroscopy. The presented analytical approach is a versatile and sensitive tool to study defect distribution and clustering in SWCNTs and can be applied to any new functionalization method.Defect clustering in carbon nanotubes can be recognized by a new analytical approach combining quantum yield measurements and Raman spectroscopy.

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Funding information in the publication:
This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 817494 “TRIFECTS”). B. S. F. and H. L. gratefully acknowledge support by the DFG under grant numbers FL 834/5-1, FL 834/9-1 and FL 834/12-1. H. L. acknowledges financial support from the Turku Collegium for Science, Medicine and Technology (TCSMT). The authors thank Kerstin Brödner and Marcus Dodds for their technical support during initial tests of the ozone functionalization reaction.