Fabrication and effect of post treatment on flexible single-walled carbon nanotube films

We report, an effective method of purification by dry oxidation and acid treatments of commercial arc discharged single-walled carbon nanotubes (SWNTs) without affecting their pristine structure. Stable dispersion of the purified SWNTs in 1,2-dichlorobenzene is accomplished in the absence of surfactants/polymers at a concentration of 0.1 mg/ml using the ultrasonic process. Fabrication of transparent conducting films from the nanotube dispersed solution on UV/ozone treated flexible substrates, polyethylene naphthalate (PEN) and polyether sulphone (PES) is reported. We produced SWNT films on PEN/PES for sheet resistances 110/100 and 200/193 a"broken vertical bar/sq with 80 and 90% transmittances, respectively, at 550 nm after a post treatment in a mixture of isopropyl alcohol-nitric acid solution. Effective wetting of nanotubes during post treatment enhanced the film conductivity without sacrificing its stability and optical transparency.