A transparent laptop screen? A window as a video display? It’s long been a dream and occasionally an expensive prototype, but Fraunhofer researchers say their light-permeable conductive coatings could soon make transparent displays commonplace and relatively inexpensive.
While some of these display already exist (usually made by a lithographic method) the costs are enormous, but scientists from several Fraunhofer Institutes are working to drive the production costs for conductive transparent coatings via two separate methods.
One method is to directly print the coatings using a sol-gel process, by which the coatings can be simply applied by printing. Direct printing is desirable compared to lithography because it would be relatively simple and far faster. In a Fraunhofer release, project manager Peer Löbmann says, “We have already been able to improve the conductivity of the printed coatings fivefold, which makes them suitable for displays, and we believe we can improve them even further. At present their conductivity is a tenth of that achieved by conventional coatings.”
The second method being tested is to use a p-type of conductive coating instead of the typical n-type. “[With n-type] semiconductors, electrons carry the current flow,” said Löbmann. “We are developing transparent coatings made of p-conducting materials, in which moving gaps between the electrons conduct the current.” P-type coatings, however, are turning out to have some problems with transparency and conductivity, but are likely good enough to be used to manufacture (combined with n-type materials, too) transparent diodes, transistors and solar cells.