Anomalous electrical characteristics, memory phenomena and microcavity effects in polymeric light-emitting diodes

The electrical and emission properties of poly(p-phenylene vinylene) -based light-emitting devices with different thicknesses of the emitting layer, and especially the influence of the ambient atmosphere, were examined. In vacuum anomalous current-voltage characteristics and a memory switching phenomenon were found in single-layer sandwich structures (ITO/polymer/Al, Au/polymer/Al). In air the anomalous behaviour disappeared. Microcavity effects in the electroluminescence emission of the single-layer devices are further reported.