Control of spontaneous emission using microcavity structures in organic electroluminescent devices

The method for controlling of spontaneous emission in organic thin-film electroluminescent devices by introducing optical microcavity structures is described. An optical microcavity structure was introduced into organic three-layer electroluminescent (EL) devices with an europium complex as an emission layer. The device structure consisted of a dielectric reflector composed of SiO2/TiO2 bilayers, an indium-tin-oxide electrode, a hole transport layer, a europium complex as an emission layer, an electron transport layer and a MgAg electrode. The dielectric reflector and the MgAg metal electrode constituted a planer microcavity. Sharply directed emission from the europium complex was observed when operated under dc drive voltage.