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) (similar to 30 Omega/square) albeit at lower transmittance (similar to 50%). At 80 +/- 5% transmittance, the functionalized films have resistance values ranging from 150 to 300 Omega/square. 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. (c) 2007 American Institute of Physics.