Sharply directed emission in organic electroluminescent diodes with an optical-microcavity structure

Abstract

An optical microcavity structure was introduced into organic three-layer electroluminescent (EL) diodes with a 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. Both angular dependences of intensity of emitted light and emission spectra of the EL diodes with the microcavity were compared with those of conventional EL diodes without microcavity.