The INM – Leibniz Institute for New Materials (Saarbrücken, Germany) has developed transparent conducting oxide (TCO) coatings for which technology transfer licenses are available. Due to the combination of high electrical conductivity with a high optical transmission, transparent conducting oxides (TCO) find wide application, for example, as electrodes in displays and thin film solar cells. In addition to the electrical conductivity of these materials, the closely related IR reflectivity is particularly of high interest for heat insulating windows (low-E, solar control). The materials involved are mostly doped n-type semiconducting oxides with a wide band gap (> 3 eV) including materials such as In2O3, SnO2 and ZnO.
Sol-Gel TCO-Coatings
The sol-gel process is a cost-efficient alternative for depositing TCO coatings on temperature-resistant substrates such as glasses and ceramics. Examples of such TCO materials include:
- ATO - SnO2:Sb (alternatively: Ta, Nb, W)
- ITO - In2O3:Sn
- AZO - ZnO:Al
- Ternary oxides - e.g. Zn2SnO4
For their deposition, not only large-area coating techniques such as dip coating can be used but also, for example, spin coating and the more flexible spray coating process. In addition, special coating techniques were developed for a deposition inside glass tubes and on thin display glasses („T 0.7 mm) to take account of the substrate requirements. The achieved sheet resistance values (single coatings) are in the lower kW/sq region (ATO) or 300 W/sq (ITO), respectively, with a transmission of 85-90 % (400 to 750 nm).
TCO nanoparticles
New applications arise from the use of functional TCO nanoparticles such as ITO or ATO. Such materials can be incorporated in polymers and lacquers to obtain electrical conductivity or IR reflective properties. In this way, UV curable ITO coatings could be deposited also on temperature sensitive polymer substrates (e.g. PC, PMMA, PET) with a sheet resistance of 1 kW/sq and a transmission > 85 %. Large-area coatings on flexible polymer films are also possible by using appropriate printing techniques such as gravure, offset and flexo printing.
The additional opportunities of a direct patterning of TCO materials, moreover, are opening new applications especially in the field of printed electronics. A corresponding process for gravure printing of patterned ITO anodes for use in flexible OLED displays was developed within the EU-funded ROLLED project (FP6-IST), which was a four year project completed in 2008.
The project's goal was the development of a cost-effective, volume-scale, roll-to-roll manufacturing technology for the production of flexible OLED devices with arbitrary size and shape pixels and displays on web. These technologies are developed in order to achieve a good understanding of the production process structure. Technologies are tested and demonstrated in the manufacturing process of demonstrator displays.
The INM – Leibniz Institute for New Materials, situated in Saarbrücken (Germany), engages in fundamental and applied materials research – from molecules to pilot production. Their main research fields are “Chemical nanotechnology“, “Interface Materials” and “Materials in Biology” INM develops nanostructured materials from a chemical, physical and biological perspective, investigate material properties and promote their potential applications in industrial collaborations. We develop for companies worldwide and cooperate with national and international institutions. The institute employs some 180 collaborators and has an annual budget of about $24.5 (17 million Euros) (Status: 2008).
Technology Transfer Contacts:
Dr. Peter W. de Oliveira, Head of Optical Materials
Phone: +49 (0)681-9300-148, Fax.: +49 (0)681-9300-223
E-mail: Peter.Oliveira@inm-gmbh.de
Phone: +49 (0)681-9300-148, Fax.: +49 (0)681-9300-223
E-mail: Peter.Oliveira@inm-gmbh.de
Secretary, Sonja Immisch
Phone: +49 (0)681-9300-375, Fax.: +49 (0)681-9300-223
E-mail: Sonja.Immisch@inm-gmbh.de
Phone: +49 (0)681-9300-375, Fax.: +49 (0)681-9300-223
E-mail: Sonja.Immisch@inm-gmbh.de
