The enhancement of passivation effect on aluminum cathode deposited by ion beam assisted deposition method in organic display

Highly stable organic electroluminescent devices based on spin-coated MEH-PPV thin films have been achieved. The improvement of lifetime is derived from Aluminum cathode deposited by Ion Beam Assisted Deposition (IBAD) method. In thermal evaporated Al, pinholes were formed due to the low surface mobility and less reactivity with MEH-PPV. But in Ion Beam Assisted Al there are much less pinhole defects because of fine grain size caused by high surface mobility. And the energetic particles of At assisted by Ar+ ion enhance the adhesion between Al and MEH-PPV. Also Ta-CeO2 film was deposited by IBAD to protect Al cathode and MEH-PPV from the H2O and O2. The passivation effect of ion beam assisted Al is superior to that of thermal evaporated Al. It is believed that Ta-CeO2 film have much less pinhole on the ion beam assisted Al than the thermal evaporated Al.