SHARPLY DIRECTED EMISSION IN ORGANIC ELECTROLUMINESCENT DIODES WITH AN OPTICAL-MICROCAVITY STRUCTURE

An optical microcavity structure was introduced into organic three-lay er electroluminescent (EL) diodes with a europium complex as an emissi on layer. The device structure consisted of a dielectric reflector com posed of SiO2/TiO2 bilayers, an indium-tin-oxide electrode, a hole tra nsport layer, a europium complex as an emission layer, an electron tra nsport layer, and a MgAg electrode. The dielectric reflector and the M gAg metal electrode constituted a planer microcavity. Sharply directed emission from the europium complex was observed when operated under d c drive voltage. Both angular dependences of intensity of emitted ligh t and emission spectra of the EL diodes with the microcavity were comp ared with those of conventional EL diodes without microcavity. (C) 199 4 American Institute of Physics.