Dedoping of Carbon\nNanotube Networks Containing Metallic\nClusters and Chloride

Doping\ncarbon nanotube films improves their electrical\nconductivity\nand chemical stability. One conventional doping method is the in situ\nreduction of AuCl<sub>3</sub> and yet its beneficial properties on\nthe electrical conductivity lessen once the films are thermally annealed.\nHere, density functional theory and semiclassical Boltzmann transport\ntheory calculations show a deterioration of the electrical conductivity\nof a doped network of (8,0) carbon nanotubes as the Au<sub><i>n</i></sub> clusters (<i>n</i> ≤ 10) become\nlarger or the Cl impurity concentration decreases. Between the smallest\nand largest cluster sizes, the conductivity along the nanotubes and\nacross the junction dropped by 47 and 90% in metallic networks. The\ndeclines in semiconducting networks were 50 and 13%, respectively.\nThe maximum electrical conductivity across the junction was for networks\ncontaining Au<sub>5</sub> clusters (193 times larger than the pristine\nnetwork). Additionally, the electrical transport was reduced when\nCl impurities were removed. Networks with excess Cl impurities had\n9.6 and 36.7 times larger electrical conductivity along the nanotubes\nand across the junction than networks without impurities. Controlling\nthe cluster size and Cl content would mitigate the dedoping of carbon\nnanotube films after thermal annealing.