Single-walled carbon nanotube networks growth optimization

In recent years there have been many improvements in quality and yield of single-walled carbon nanotubes (SWCNTs) obtained by chemical vapour deposition (CVD). Mainstream in research is focused on growing thick vertically aligned forests of SWCNTs. At the same time SWCNT films - usually obtained by spraying and filtration - are one of the most promising candidates to replace indium tin oxide (ITO) as transparent electrodes in solar cells and flat displays. The main limit of those techniques is that usually carbon nanotubes (CNTs) are deposited in the form of thick bundles and are mixed with insulating molecules, such as surfactants, used to try to unbundle the CNTs in solution. Moreover, ultrasonication is in general used to help dispersion, inducing defects in the tubes; the overall effect is to considerably reduce the conductivity of such CNT films. It is our firm belief that a considerable improvement in film quality can come by directly synthesizing the networks onto the substrate via CVD, but this requires achieving a control of the density and quality of the SWCNT networks without losing the planar arrangement. We show here our latest results in enhancing the quality of SWCNT percolating network synthesis by alcohol CVD on silicon oxide substrates using cobalt and nickel acetates as precursors. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim