Dependence of hole and electron current density of mixed host devices on mixed host composition

The hole and electron current densities of mixed host emitting layer were studied according to the composition of the mixed host to investigate the origin of high quantum efficiency of the mixed host devices. Hole only and electron only devices of mixed host emitting layer were fabricated and the current density of single charge devices was studied. The hole current density was greatly affected by the mixed host composition, while the electron current density was not greatly changed by the mixed host composition. Therefore, the change of hole current density by mixed host composition was critical to the device performances of the mixed host devices.