Performance of injection-limited polymer light-emitting diodes

The electro-optical characteristics of a polymer light emitting diode (PLED) with a strongly reduced hole injection have been investigated. The device consists of a poly-p-phenylene vinylene semiconductor with a Ag hole injecting contact, which has an injection barrier of about 1 eV. It is observed that the light and current density of such an injection-limited PLED strongly exceed the expected device characteristics. Numerical calculations of the injection-limited PLED show that the enhanced performance can be explained by a very high electric field at the bole injecting contact, due to trapped electrons.