Just now the most intensive development is aimed at conjugated polymers in their un-doped, semiconductive state. This is because it was discovered ten years ago that some conjugated polymers exhibit electro-luminescence, they glow when a voltages passes through them. Many applications are predicted for luminescent plastic. We shall soon be seeing the first practical use in light displays in mobile telephones and on information boards. In a few years flat TV screens in luminescent plastic may have become a reality.