No abstract

Indium tin oxide (ITO) is a widely applied optoelectronic material. However, conventionally, it is deposited via cost‐ and energy‐intensive physical vapor deposition processes (PVD) like sputtering, resulting in rather brittle layers. In this report, the tape casting process is presented as an alternative processing route for the manufacture of transparent, conductive ITO layers. Tape casting is a particle‐based technique, thus ITO nano‐particles are first dispersed and stabilized in organic solvents. Subsequently, slurries are prepared using polyvinyl butyral binder and benzyl phthalate plasticizer. The rheological behavior of the slurries is analyzed and adapted to the tape casting process. After tape casting, the ITO green tapes are characterized concerning their electrical and optical behavior. Optical transmission up to 75% and electrical resistances down to 2 Ω·cm are reached without any further treatment. The ITO layers which exhibit such values are already suitable for applications in certain electronic devices. In this study, the applicability of the ITO green tapes is demonstrated by the assembly of functional, fully flexible electroluminescent lamps, which are laminated using the ITO green tapes as well as other functional green tapes in the as‐deposited state.

This presentation introduces a new technique to manufacture continuously submicron thick ceramic green tapes and coatings from nano particulate suspensions. A profiled steel rod is used to coat large areas with a very low film thickness of down to 250 nm. This technique can easily be scaled up and is therefore suitable for mass production at high throughput and low cost. The profile rod technique could be a method to overcome the limit of the tape casting process and therefore this technique exhibits an enormous economical potential. The technique is demonstrated at the example of nano particulate indium tin oxide (ITO) and zinc oxide (ZnO) particles, which are both transparent conductive oxides (TCOs) and therefore interesting materials for printed displays etc. Nano particles from Evonik Degussa GmbH were first dispersed and stabilized in organic solvents. Subsequently, dispersions as well as slurries were prepared. Their rheological and wetting behavior were studied and the effect on the microstructure of the resulting layer was evaluated. Furthermore, the influence of the processing parameters during coating on the layer quality was analyzed. Finally, the functionality of the printed layers was proven by electrical measurements as well as the assembly of electron devices.

There is a fast‐growing market for printable electronics, which requires new techniques for micro‐ and nanofabrication suitable for mass production of functional electronic products. This makes the evaluation and comparison of different printing techniques highly important. In this work, a coating process, referred to as “profile rod technique,” is presented as an alternative to the spin‐coating process for the production of nanoparticulate zinc oxide (ZnO) layers with thicknesses of several hundred nanometers. Such layers could be used, e.g., as semiconducting layers for printed thin film transistors. The profile rod technique, in contrast to spin‐coating, is a continuous process, which allows for easier mass production and reduction in manufacturing costs. To compare the spin‐coating and the profile rod process, submicrometer‐thick layers of ZnO nanoparticle dispersions in ethanol were prepared. Different dispersion techniques were studied concerning their applicability for the manufacture of nanosized particle dispersions because well‐dispersed suspensions are the basic requirement for the manufacture of submicrometer‐thick layers with high morphological quality. The quality of the deposited layers was evaluated concerning their microstructure. Moreover, the profile rod technique could be successfully used for the manufacture of submicrometer ceramic green tapes.