Low work function reduced metal complexes as cathodes in organic electroluminescent devices

Several electrochemically active polypyridine-metal complexes are isolated in the formally zero-charged state via reductive electrocrystallization, and are thermally evaporated to form conducting thin films with low work functions. Solution-phase cyclic voltammetry of the parent complexes is used to predict the work function of these materials. The reduced films are used as cathode materials in organic light-emitting devices, in place of the commonly used low work function metals such as calcium and aluminum. These reduced complexes represent a new class of materials available for use as electron-injecting contacts in organic electroluminescent devices.