Photosensitization of carbon nanotubes using dye aggregates

Ordered assemblies of dye molecules, dye aggregates, possess significantly larger molar optical absorptivity than dye monomers. Yet, aggregates have not been utilized for photosensitizing nanoscale electronic devices. We find that single-walled carbon nanotubes, which are cleaned down to the atomic scale, template the growth of squaraine dye aggregates and these aggregates effectively photosensitize nanotubes. Templating of aggregates by nanotubes and functionalization of nanotubes with ordered molecular films are reported for the first time. The sensitivity achieved by aggregate-functionalized nanotube network devices is approximately an order of magnitude better than those of similar nanotube devices functionalized with dye monomers and photoactive polymers.