Organic electroluminescent devices fabricated using a diamine doped MgF2 thin film as a hole-transporting layer

Abstract

Organic electroluminescent (EL) devices have been fabricated which have a MgF2 layer doped with N, N′-diphenyl-N, N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4, 4′-diamine (TPD) as the hole- transporting layer, and the emitting layer of tris-(8-hydroxyquinoline) aluminum (Alq). For the organic EL devices, bright green emission with 2600 cd/m2 is observed at a voltage of 15 V. The luminous efficiency is about 0.3 lm/W at a current density of 100 mA/cm2. This high efficiency indicates that the diamine doped MgF2 layer plays the role of hole transport and confinement of electrons in the emitting layer. It is also found that the thermal stability of the organic EL device is higher than that of the conventional organic EL device.