Magnetic field dependent triplet-triplet annihilation in Alq(3)-based organic light emitting diodes at different temperatures

The magnetic field dependent current and electroluminescence (EL) of aluminum tris-(8-hydroxyquinoline) (Alq(3))-based organic light emitting diodes (OLEDs) have been measured at different temperatures. At low temperatures, the magnetic field effects consist of a rapid rising in EL in low field regime followed by a slow falling at high fields and a continuous increase in current for all applied magnetic fields. The high field decrease in the EL is weakened and even vanishes at higher temperatures, which is attributed to the field affected triplet-triplet annihilation process. Other possible mechanisms about the magnetic field effects on electronic processes in OLEDs are also discussed. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3125507]