Electron mobility in tris(8-hydroxyquinoline)aluminum (Alq3) films by transient electroluminescence from single layer organic light emitting diodes

Single layer devices of indium tin oxide/Alq(3)/Al were constructed with varying the active areas from 1 to 8 mm(2) and the thicknesses from 30 to 50 nm. Average electric field across the Alq(3) layer during the transient state was estimated from the accumulated charges at the interfaces of the devices. The electron mobility could thus be calculated by assuming that the injected charge carriers moved under the average electric field rather than the instantaneous field. The resulting mobility could be determined uniquely in a device thickness. The electron drift mobility was shown to behave similarly to the time-of-flight results. (C) 2007 American Institute of Physics.