Dispersion of Single-Walled Carbon Nanotubes by Nafion in Water/Ethanol for Preparing Transparent Conducting Films

Single-wall carbon nanotubes (SWCNTs) dispersed by Nafion in water/ethanol with different ratios (100:0, 75:25, 50:50, 25:75, 0:100) were used to prepare transparent conducting SWCNT films both on glass and on polyethylene terephthalate (PET) substrates by filtration method. SWCNT-SDS films were also made to compare with different SWCNT-Nafion films, and the factors influencing the electrical conductivity of SWCNT films were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It was found that SWCNT-Nafion-water/ethanol (50:50) films exhibited the best performance with the sheet resistance of 500−600 Ω/sq at transmittance of 85% and the best thermal stability at 60 °C with change of sheet resistance less than 2% in 200 h. The best performance of SWCNT-Nafion-water/ethanol (50:50) films was attributed to the following: (1) the bundle size of SWCNTs dispersed by Nafion was small, (2) the residual substance Nafion in the network of SWCNTs was more conductive than insulating SDS, (3) SWCNTs were p-doped by Nafion, and (4) the thermal stability of Nafion was good.