Transparent conducting oxide TCO films which are characterized by a
The majority of the present production of flat panel displays and solar cells is based on glass substrates which provide a rigid support and can withstand the high temperatures required for successive manufacturing steps. In order to meet the expectations for growing electronic markets with lower prices, it is necessary to substitute flexible plastics for rigid glass as the NU 7026 substrate. Polymer foils are lighter and thus allow low-cost mass production by roll-to-roll (R2R) based continuous fabrication processes . However, thermoplastic polymers cannot withstand the necessary temperature for achieving a low electrical resistivity for widely used production steps. Considerable efforts are being made on the development of low-temperature processes compatible with plastic substrates , ,  and . Sputter technology is extensively utilized for wide web R2R deposition of TCO films on plastics. Wet-chemical processing for TCO preparation is a low cost alternative, which allows coating small, large flat substrates or complex shaped substrates and cavities. A route proposed by Burgard et al.  was to develop hybrid organic–inorganic sols containing the highest possible amount of already conducting crystalline oxide TCO nanoparticles for further processing, like by sol–gel spin/dip coating on plastics. The major advantages of this technique are the separation of the crystallization step of the TCO material from the process of film formation on the one hand and the redispersability of the obtained nanoparticles in a variety of lacquer composition on the other hand. This offers the possibility of curing layers either by a low temperature thermal treatment (<130 °C) or by UV light irradiation. Also a high nanoparticles filling of the sol containing an adequate organic binder should assure a reasonable conductivity. The use of nanoparticles will lead to a low light scattering and to high transparency of the coatings . Recently, Kim et al.  and  proposed a novel and general strategy for fabricating solution-processed metal oxide thin-film transistors (TFTs) at much lower annealing temperatures, Tanneal as low as 200 °C, using self-energy generating combustion chemistry. It could be seen that the generation of high local temperatures without a furnace enabled low-cost large-scale bulk syntheses, and the high self-generated energies could convert precursors into the corresponding oxides at low process temperatures. Essentially, to achieve a flexible deposition methodology and better property control over the metal oxide nanocomposite film formation, the properties of nanoparticles for hybrid organic–inorganic sols and/or other further processing should be investigated firstly.