Surface-emitting polymer light-emitting diodes

We report the fabrication of polymer electroluminescent devices on doped silicon substrates. An electron-injecting aluminium electrode is thermally evaporated onto the silicon substrate, and a layer of a high electron affinity conjugated polymer, poly(cyanoterephthalylidene), CN-PPV, is then spin-coated onto this. A hole-transporting layer of poly(p-phenylene vinylene), PPV, is formed on top of the CN-PPV layer by thermal conversion of a spin-coated layer of the sulphonium precursor polymer. Finally, a transparent hole-injecting top electrode of indium-tin oxide is formed by RF sputtering. These devices show efficient red electroluminescence, with emission from the CN-PPV layer.