Controlled Introduction of sp3 Quantum Defects in Fluorescent Carbon Nanotubes by Mechanochemistry

Precise control over low‐dimensional materials holds an immense potential for their applications in sensing, imaging and information processing. The controlled introduction of sp3 quantum defects (color centers) can be used to tailor the optoelectronic properties of single‐walled carbon nanotubes (SWCNTs) in the tissue transparency (> 800 nm) and the telecommunication window. However, an uncontrolled functionalization of SWCNTs with defects leads to a loss of the NIR fluorescence. Here, we use mechanochemistry with aryldiazonium salts to create quantum defects in SWCNTs. The reaction proceeds within 5 min without solvents or illumination and can be controlled by a varied mechanochemical energy impact. By working in the solid‐state, this method presents an alternative synthetic route and marks a crucial step for tailoring photophysics of SWCNTs.