News Article
Electroluminescent Deposition
Researchers from Munich-based universities and from German chemical company Covion have developed a class of electroluminescent (EL) polymers that can be patterned in a way similar to standard lithography photoresists (Nature, February 20, 2003). In other words, the polymer is spin coated onto a substrate and then photographically patterned and processed.
Researchers from Munich-based universities and from German chemical company Covion have developed a class of electroluminescent (EL) polymers that can be patterned in a way similar to standard lithography photoresists (Nature, February 20, 2003). In other words, the polymer is spin coated onto a substrate and then photographically patterned and processed.
The scientists say that the resolution of the process is sufficient for making pixellated matrix displays. The resulting devices had RGB colours with efficiencies comparable to - but, except for the blue polymer, not yet achieving - state-of-the-are organic light emitting diodes with a slightly reduced onset voltage.
The device structure was of the form of a 20nm indium tin oxide/poly(3,4-ethylenedioxy-thiophene) (ITO/PEDOT) layer, an 80nm EL polymer layer, a 20nm calcium layer and finally a 200nm silver layer. The PEDOT material is a polymer commonly used for hole injection.
The paper points out that the alternative deposition methods such as vacuum deposition, screen printing and ink jet printing each have their disadvantages.