Percolation in Transparent and Conducting Carbon Nanotube Networks

Ultrathin, uniform single-walled carbon nanotube networks of varying densities have been fabricated at room temperature by a vacuum filtration method. Measurements of the sheet conductance as a function of nanotube network density show 2D percolation behavior. In addition, the network transparency in the visible spectral range was examined and the results are in agreement with a standard thin-film model: fits to the standard theory indicate óac) ódc for transmission measurements at 550 nm. Transmission measurements also indicate the usefulness of nanotube network films as a transparent, conductive coating. Avenues for improvement of the network conductance are discussed. Since their discovery in the early 1990s, single-walled carbon nanotubes (SWNTs) have been exhaustively researched, and still only the surface of their potential has been scratched. Their usefulness in applications stems from their amazing physical properties: single tube devices have mobilities as high as 100,000 cm2/Vs,1 current carrying capacities of 109 A/cm2 (ref 2), and ON/OFF current ratios as large as 105.3 However, applications using single nanotube devices, though superior in some aspects, have the major flaw of irrepro