Fabrication of double- and multi-walled carbon nanotube transparent conductive films by filtration-transfer process and their property improvement by acid treatment

Double-walled carbon nanotubes (DWCNTs) and two kinds of vertically aligned multi-walled carbon nanotubes were employed as raw materials to fabricate transparent conductive films (TCFs). DWCNTs constructed the densest conductive network at the same transmittance, and the corresponding TCFs showed the best performance (320 Omega/a- at 75.0% T). The ratio of dc conductivity to optical conductivity (sigma (dc)/sigma (op)) of the as-dispersed DWCNTs was 3.88. The as-obtained TCFs were dipped in HNO3 solution to improve their performances. Attributed to the removal of sodium dodecyl sulfate molecules, reduction of film thickness, and doping with electron acceptors (such as oxygen), the surface resistance after HNO3 treatment decreased. The sigma (dc)/sigma (op) ratio of the DWCNTs was further increased to 5.24.