Transparent Conductive Single-Walled Carbon Nanotube Networks with Precisely Tunable Ratios of Semiconducting and Metallic Nanotubes

Abstract

We present a comprehensive study of the optical and electrical properties of transparent conductive films made from precisely tuned ratios of metallic and semiconducting single-wall carbon nanotubes. The conductivity and transparency of the SWNT films are controlled by an interplay between localized and delocalized carriers, as determined by the SWNT electronic structure, tube-tube junctions, and intentional and unintentional redox dopants. The results suggest that the main resistance in the SWNT thin films is the resistance associated with tube-tube junctions. Redox dopants are found to increase the delocalized carrier density and transmission probability through intertube junctions more effectively for semiconductor-enriched films than for metal-enriched films. As a result, redox-doped semiconductor-enriched films are more conductive than either intrinsic or redox-doped metal-enriched films.

Highly conductive and transparent carbon nanotube composite thin films deposited on polyethylene terephthalate solution dipping

“…Hence, if we are able to increase the number of the effective electric conductive tube-tube junctions per unit area without increasing the number of the SWCNTs, we will improve the transport of free carriers between the tubes and lower the percolation threshold, thus improving the conductivity of the CNT networks. Recent work by Blackburn et al [14] supports this analysis. Those workers found that the DC conductivity of the SWCNT film is several orders of magnitude lower than expected by considering the total carrier density within the conduction band of individual SWCNTs (approximately 1 electron per carbon atom).…”

“…T h em a i nc h a l l e n g eh e r ei st oa d d r e s st h et r a d e -o f fb e t w e e n transparency and conductivity. Many factors have been studied in order to improve the conductivity of the CNT thin films without sacrificing their transparency [4,[11][12][13][14][15]. For example: processing techniques and parameters [4,11]; length of the CNT [12]; doping [13,14]; and metallic amount of the CNT in the mixture [14].…”

“…The preliminary results are close to those of the commercial available ITO thin films deposited on PET, such as the ones from Sigma-Aldrich (35 Ω/□, N86% transmission at 550 nm). With the optimization of the composition of the SWCNT composite, plus other techniques reported in the literature [11][12][13][14][15], SWCNT/conducting polymer composite thin films might potentially offer better or comparable performances as the conductive oxides.…”

Unique Origin of Colors of Armchair Carbon Nanotubes

“…In a recent report, 10 we provided unambiguous evidence of bulk enrichment of armchair nanotubes through DGU by utilizing wavelength-dependent resonant Raman scattering spectroscopy. We found that the Raman spectra were dominated by (6,6), (7,7), (8,8), (9,9), and (10,10) for samples enriched from carbon nanotubes synthesized by the high-pressure carbon monoxide (HiPco) method.We studied the absorption properties of a series of armchairenriched samples with different diameter distributions, exhibiting distinct colors (see Fig. 1).…”

The 2008 Kavli Prize in Nanoscience: Carbon Nanotubes

“…Compared to the commonly used indium tin oxide electrodes, nanotube films show lower resistance for the same transparency level. 34,35 Another interesting application of carbon nanotubes is in chemical and biological sensors. Since all of the carbon atoms are on the surface, SWNTs are highly sensitive to their environment.…”