Conduction mechanism and stability of organic light-emitting diodes depending on the Al-based cathodes

摘要

We have studied a conduction mechanism and stability of organic light-emitting diodes with a variation of cathode materials; Al, LiAl, and LiF/Al. The organic light-emitting diodes emit a light by an injection and transport of charge carriers such as holes and electrons. Thus, the charge transport is affected by the injection barrier at the interface and hopping process in the bulk. To have an efficient organic light-emitting diodes, understanding of the electrical conduction mechanism is important. By varying the cathode materials, the electron injection at the interface could be controlled because of the work function change at the cathode. We have performed the temperature-dependent electrical properties and stability of the organic light-emitting diodes in the temperature range from 10 K to 300 K. And the devices of LiAl and LiF/AI cathode, in the lifetime and luminous efficiency, are superior to those of pure-Al.