Light Control over Chirality Selective Functionalization of Substrate Supported Carbon Nanotubes

Diazonium reactions with carbon nanotubes form optical sp3 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 E22 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 E11 compared to the emission from the pristine tubes.