Oxygen Doping Modifies Near-Infrared Band Gaps in Fluorescent Single-Walled Carbon Nanotubes

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Science  25 Nov 2010:
DOI: 10.1126/science.1196382


Controlled chemical modifications of single-walled carbon nanotubes (SWCNTs) that tune their useful properties have been sought for multiple applications. We report that beneficial optical changes in SWCNTs result from introducing low concentrations of oxygen atoms. Stable covalently oxygen-doped nanotubes are prepared by exposure to ozone and then light. Treated samples show distinct, structure-specific near-infrared fluorescence at wavelengths 10 to 15% longer than the pristine semiconducting SWCNTs. Dopant sites harvest light energy absorbed in undoped nanotube regions by trapping mobile excitons. The oxygen-doped SWCNTs are much easier to detect and image than pristine SWCNTs because they give stronger near-IR emission and do not absorb at the shifted emission wavelength.