Flexible transparent conducting single-wall carbon nanotube film with network bridging method

We fabricated random network films of highly pure single-wall carbon nanotubes (SWCNTs) on flexible polyethylene terephthalate substrate by dip- and spray-coatings and their combination method for application to flexible transparent conducting films (TCFs). The dip-coating treatment was a more efficient method for fabricating the SWCNT-TCFs of high electrical conductivity without drastic drop in the optical transmittance, compared to the spray-coating one. This should be primarily due to more loose contact in intertube and interbundle junctions of the spray-coated SWCNT networks. Although the electrical conductivity of the SWCNT-TCFs was dramatically enhanced as increasing the number of dipping times, the dip-coating treatment with a large number of dipping times considerably reduced the transmittance without corresponding improvement in the electrical conductivity, indicating the patch-wise coating of the SWCNTs. On the other hand, the combination of the spray- and dip-coatings gave a supplementary effect for formation of a highly transparent film of better electrical conductivity. For SWCNT-TCF coated with 100 dipping times, an additional spray-coating dramatically decreased the sheet resistance from 1300 to 340 Ω/square, which is accompanied by slight reduction of the transmittance from 88 to 80%. Therefore, the post spray-coating can efficiently bridge the patch-wise SWCNT networks produced by the successive dip-coating.

Graphical abstractAdditional spray-coating treatment on dip-coated single-wall carbon nanotube-based transparent conducting film can efficiently bridge the quasi one-dimensional conducting pathways, resulting in enhancement of electrical conductivity without drastic drop of optical transmittance.Figure optionsDownload full-size imageDownload as PowerPoint slide