Abstract

Background: Transparent and conductive films (TCF) are the principal core for fabricating electronic devices. The traditional TCFs, indium tin oxide (ITO) thin films have been used for such devices which have their own drawbacks. In the present study, multi-walled carbon nanotubes (MWCNTs) thin films were fabricated and their electrical conductivity was improved by adding Ag nanowires to the CNTs for the first time in literature.

Methods: The initial multi-walled carbon nanotubes with the diameters less than 10 nm and 5-15 m length were oxidized in a mixture of sulfuric and nitric acids. Silver nanowires were synthesized by solvothermal method through reducing silver nitrate with ethylene glycol (EG) in the presence of polyvinylpyrrolidone (PVP). Different solutions including 1.8, 3.5, 5.1, and 10.5 wt.% of Ag/MWCNTs were prepared and coated on a cleaned and functionalized glass substrate by spin coating technique.

Results: For low thicknesses, dc conductivity of the films was thickness-dependent but appeared to become bulk-like for film thicknesses of about 300 nm. A sheet resistance of 1006 ohm/sq with 82% transmittance at 550 nm in wavelength was attained for 5.1wt.% Ag nanowires in MWCNTs. Using the deduced data, the DC conductivity to optical conductivity ratio for a percolated network 92.4 was calculated for 5.1wt.% of Ag nanowires in MWCNTs which was much higher than 37 for the films without using Ag nanowires.

Conclusions: It was observed that the conductivity and figure of merit of different films of MWCNTs-Ag nanowires composite were improved by increasing Ag nanowires concentration. The electrical conductivity and optical transmittance were affected by different Ag wt.% and different film thicknesses. The low sheet resistance of thin conductive films was due to the increased contact areas between MWNTs and Ag nanowires on the MWNTs surfaces.

Keywords: Ag nanowires, carbon nanotube, sheet resistance, transparent conductive film.