Transparent conductive coatings and

Another growing apphcation that overlaps the electrically functional area is the use of transparent conductive coatings or tin oxide, indium—tin oxide, and similar materials in photovoltaic solar ceUs and various optic electronic apphcations (see Photovoltaic cells). These coatings are deposited by PVD techniques as weU as by spray pyrolysis, which is a CVD process. 

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. 

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]. 

A review with many references about various sol-gel dye composites, photo-chromic and electrochromic coatings, transparent conducting, antistatic and antireflection coatings as well as hydrophobic and oleophobic fluorinated sol-gel coatings was recently published by Uhlmann et al.[490]. Further examples can be found in the Proceedings of the ls,ICCG-96 [491], several books as e.g. [492,493] and particularly in the Journal of Non-Crystalline Solids (Elsevier). 

In the transport industry, the most important application is the de-icing and de-misting of large extended surface areas by transparent and electrically conductive coatings and there are, in addition, some solar control applications. 

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]. 

Most of the transparent conductive coatings are produced by vacuum evaporation and sputtering. Other techniques are hot spraying and chemical vapour deposition, as manufactured by Corning, Pittsburgh Plate Glass (PPG) and others [162]. 

Another strategy that allows the combination of electronic, electrical and optical properties of ICP with tunable properties of the matrix has also been explored. Nanostructure materials with an ICP core and an insulating polymer shell have also been reported [79-81]. Highly transparent conductive coatings with core-shell nanoparticles have been reported by Jang et al. [82]. Poly(methyl methacrylate)... 

PMMA)-coated PPy nanopartides were prepared by microemulsion polymerization, and the composite particles were incorporated into a PMMA matrix to obtain transparent conductive coatings. The prepared particle showed core-shell morphology (Fig. 6.15). 

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