Transient electroluminescence measurements on organic heterolayer light emitting diodes

We have investigated the field dependence of the electron and hole drift mobility in tris-(8-hydroxyquinoline) aluminium (Alq3) in organic multi layer light emitting diodes (LEDs) using transient electroluminescence measurements. The electron transport in thin films of Alq3 can be understood in terms of hopping processes. We obtain a full set of parameters for a modified Poole–Frenkel equation describing the temperature and field dependence of the electron drift mobility. For the measurement of the hole drift mobility, a special device structure was designed. We were able to determine the hole drift mobility in Alq3 and found good agreement with the data obtained from previous time-of-flight (TOF) measurements.