Investigation of the magnetic field effects on electron mobility in tri-(8-hydroxyquinoline)-aluminum based light-emitting devices

We investigated the magnetic field effects (MFEs) on electron mobility in tri-(8-hydroxyquinoline)-aluminum based light-emitting devices by the transient electroluminescence (EL) method upon application of various offset voltages (V_offset). It is found that the rising edges of the EL overlap closely but the falling edges are separated by the magnetic field both when V_offset = 0 V and V_offset > V_turnon. The results suggest the bipolaron model and the triplet-polaron interaction model related to the carriers' mobility are not the dominant mechanisms for explaining the MFEs under our experimental conditions, and the external magnetic field is confirmed to affect the carriers' recombination process.