Transparent conductive coatings and films

Vacuum filtration is another popular method in the fabrication of transparent conductive films, which are morphologically like bucky-papers . For example, Rinzler and co-workers used filtration to 

Lu et al7 applied the vacuum filtration fabrication to the comparison of films of as-purified SWNTs and separated metallic SWNTs (approximately 85% purity in metallicity). In the fabrication, the two nanotube samples were each dispersed into an aqueous solution of SDS. A porous alumina membrane was used as filter in the vacuum filtration of the suspended SWNTs. After filtration, the film on the filter was washed repeatedly with deionized water to remove the surfactant SDS, for which the progress in surfactant removal via 

All these wet-processing methods for nanotube films seem to share some common features, as determined by the properties of SWNTs and their networks in the coated films. It is known in the literature that the resistance at an inter-tube junction is higher when the junction is between nanotube bundles. Therefore, the homogeneous dispersion and individualization of SWNTs are a prerequisite to the formation of more conductive nanotube films in terms of wet-processing methods. Indeed, dispersion strategies in these 

SWNTs was 1 kQ sq Mn sheet resistance, whereas the thicker reference film (130 nm in thickness) by the same fabrication from non-separated SWNTs exhibited a much higher sheet resistance of 20 kQ sq .  

Yang and co-workers used the separated metallic SWNTs in a systematic evaluation on transparent conductive films, which also included nanotubes from different sources coupled with various fabrication conditions. It is worth noting that the films were on a flexible substrate (PET), for which dip coating was used. Again, those films from the separated metallic SWNTs exhibited sheet resistance down to 130 Q sq for 80% optical transmittance at 550 nm (Table 6.1). The comparison of nanotube films with ITO coatings on the 

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Since one common use of oxide films is for transparent, conducting coatings, the resistivities of these films were usually measured. Table 2.2 shows some basic electrical and optical properties of some of these films. 

In a typical spectroelectrochemical measurement, an optically transparent electrode (OTE) is used and the UV/vis absorption spectrum (or absorbance) of the substance participating in the reaction is measured. Various types of OTE exist, for example (i) a plate (glass, quartz or plastic) coated either with an optically transparent vapor-deposited metal (Pt or Au) film or with an optically transparent conductive tin oxide film (Fig. 5.26), and (ii) a fine micromesh (40-800 wires/cm) of electrically conductive material (Pt or Au). The electrochemical cell may be either a thin-layer cell with a solution-layer thickness of less than 0.2 mm (Fig. 9.2(a)) or a cell with a solution layer of conventional thickness ( 1 cm, Fig. 9.2(b)). The advantage of the thin-layer cell is that the electrolysis is complete within a short time ( 30 s). On the other hand, the cell with conventional solution thickness has the advantage that mass transport in the solution near the electrode surface can be treated mathematically by the theory of semi-infinite linear diffusion. 

Chemically deposited non stoichiometric cuprous sulfide films (Cui.gS) have been used as conducting layers as reported by Grozdanov et al. [50]. The films, deposited at 40 °C, present a resistivity of 2.10 Q.cm. In addition they present optical transmission values between 50 and 70% in the visible range for a 0.12 pm thick film. These properties have been used for ohmic contacts to ferroelectric films and transparent conducting coatings on polymers. These films can also be used as chemical sensors for Cu + ions. Note that due to the low deposition temperature polymer substrates can be used [61]. 

Transparent conductive coatings combine high optical transmission with good electrical conductivity. The existence of both properties in the same material is, from the physics point of view, not trivial and is only possible with certain semi-conductors like indium oxide, tin oxide, cadmium oxide, and with thin gold and silver films, e.g. [157]. Particularly antimony or fluorine doped tin oxide (ATO, FTO), tin doped indium oxide (ITO), and aluminium, indium, or boron doped zinc oxide (AZO, IZO, BZO) are of technical importance [157a]. 

Al-Dahoudi N., Bisht H., Gobbert C., Krajewski T., Aegerter M.A. Transparent conducting, antistatic and anti-static-anti-glare coatings on plastic substrates. Thin Solid Films 2001 392 299-304... 

Aegerter M.A., Al-Dahoudi N., Solieman A., Kavak H., Oliveira P. Transparent conducting coatings made by chemical nanotechnology processes. Mol. Cryst. Liquid Cryst. 2004 in print Alam M.J., Cameron D.C. Characterization of transparent conductive LTO thin films deposited on titanium dioxide film by a sol-gel process. Surf. Coat. Technol. 2001 142 776-780 Alam M.J., Cameron D.C. Preparation and characterization 0fTiO2 thin films by sol-gel method. J. Sol-Gel Sci. Technol. 2002 25 137-145... 

T. Kawashima, H. Matsui, and N. Tanabe, New transparent conductive films FTO coated ITO, Thin Solid Films, 445 241-244 (2003). 

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