Advances in polymers for PLEDs: from a polymerization mechanism to industrial manufacturing

The recent development of polymer light emitting diodes (PLEDs) has trigger ed a lot of interest for their use in displays, backlights, and for lightin g applications. Their high efficiency and ease of manufacturing make PLEDs especially attractive. Various conjugated polymers have been employed, but especially soluble phenyl-poly-p-phenylene vinylene(s) show excellent prope rties. The chemical as well as the structural purity of the polymers has proven to be essential for high performance, long lifetime PLEDs. Mechanistic invest igations allowed the identification of one major polymerization defect in P PVs, the so called tolane-bisbenzyl moiety. This in turn has enabled us to eliminate the most significant failure mechanism of these PPVs during devic e operation. The newly developed polymers are manufactured on an industrial scale. A com bination of a glass lined 370/560 L vessel cascade allows manufacturing in kilogram scale quantities while still maintaining high purity levels. A sig nificant extension of this facility is now in use and ensures availability of large quantities ready-to-use solution of various light emitting polymer s with photo-resist type purity. (C) 2001 Published by Elsevier Science B.V .