| abstract |
An organic light emitting diode (OLED) device comprises a cathode, a light emitting layer and an anode, in that order, and, has located between the cathode and the light emitting layer, a layer containing (a) more than 10 vol % of a carbocyclic fused ring aromatic compound and (b) at least one salt or complex of an alkali or alkaline earth metal. The device provides reduced drive voltage and good luminance. |