How to Recognize Clustering of Luminescent Defects in Single-Wall Carbon Nanotubes

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 it reveals 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 oxygen 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.

References in corpus (9)

• Luminescent Defects in Single-Walled Carbon Nanotubes for Applications
• Absolute Quantification of sp${}^3$ Defects in Semiconducting Single-Wall Carbon Nanotubes by Raman Spectroscopy
• Ratiometric fluorescent sensing of pyrophosphate with sp${}^3$-functionalized single-walled carbon nanotubes
• Charge Transport in and Electroluminescence from sp${}^3$-Functionalized Carbon Nanotube Networks
• Unified Quantification of Quantum Defects in Small-Diameter Single-Walled Carbon Nanotubes by Raman Spectroscopy
• Easy Access to Bright Oxygen Defects in Biocompatible Single-Walled Carbon Nanotubes via a Fenton-Like Reaction
• Near-Intrinsic Photo- and Electroluminescence from Single-Walled Carbon Nanotube Thin Films on BCB-Passivated Surfaces
• Luminescence properties of closely packed organic color centers grafted on a carbon nanotube
• Tuning Electroluminescence from Functionalized SWCNT Networks further into the Near-Infrared