Transparent conducting oxides (TCOs) are already in wide use today as nearly invisible electrodes or reflectors for infrared light. Until now, they have been applied to the necessary support material using a special process known as vacuum sputtering. To maintain the TCOs' conductive properties, however, this procedure can only be used with rigid substrates. The Leibniz Institute for New Materials (INM) has now developed a special TCO ink that enables direct printing of transparent conductor structures on films. The Saarbrücken researchers are presenting this and other developments at HANNOVER MESSE at Research & Technology, the flagship trade fair for research, development and technology transfer.
The procedure developed by INM enables wet chemical application of TCO inks onto a wide range of substrates, employing a UV curing process that enables even thin plastic films to be coated. The inks employed contain modified TCO nanoparticles and a special binder that not only enables application on plastics and films, but also supports direct printing of transparent conductor structures for the first time. This process offers several advantages: gravure printing using a printing plate enables cost-effective production of structured TCO coatings in a single step. In addition to providing good bonding of the TCO nanoparticles to the substrate, the binders ensure that the coating remains conductive even when the films are bent.