Functionalized carbon nanotubes and dispersions containing functionalized carbon nanotubes are provided. Exemplary functionalized carbon nanotubes include optionally substituted indene-based moieties. Methods of making functionalized carbon nanotubes and dispersions containing functionalized carbon nanotubes are provided. Methods of making conductive carbon nanotube dispersions, including films, are provided. Such methods include heating carbon nanotubes in a solvent in the absence of externally applied energy, to obtain an adduct that includes the solvent moiety bound to the carbon nanotube. Where the solvent includes an indene-based compound, the carbon nanotube thus prepared includes optionally indene-based moieties bound to the carbon nanotubes.