Improved conductivity of transparent single-wall carbon nanotube thin films via stable postdeposition functionalization

A simple postdeposition method for improving the conductivity of transparent and conducting single-wall carbon nanotube (SWNT) thin films via exposure to nitric acid and thionyl chloride is reported. A systematic study on a range of films of variable density and from different commercial sources of SWNTs is performed. The functionalized films possess sheet resistances as low as that of indium tin oxide (ITO) (∼30Ω∕◻) albeit at lower transmittance (∼50%). At 80±5% transmittance, the functionalized films have resistance values ranging from 150to300Ω∕◻. The SWNT films, however, are more flexible than ITO. The stability of the functionalized films upon annealing and processing in solvents (water, methanol, and chloroform) is also reported.