Passivation properties of OLEDs with aluminum cathodes prepared by ion-beam-assisted deposition process

A long-lived organic light emitting diode (OLED) was fabricated using a dense aluminum cathode prepared by the ion-beamassisted deposition (IBAD) process. We investigated the passivation properties of ion-beam-assisted and thermal evaporationinduced aluminum cathodes mounted on Ph-PPV. The dense and highly packed Al cathode effectively prevents the permeation of H2O and O2 through pinhole defects, which results in retarding dark spot growth. Employing thin Al buffer layer diminished Ar+ ion-induced damages in Ph-PPVand limited permeation against H2O and O2. The interface between Al and Ph-PPV may be modified in IBAD case, even though buffered Al layer was deposited to 30 nm by thermal evaporation prior to Ar+ ion beam irradiation. It is believed that the buffered Al film cannot screen the Ar+ ions or Al atoms wholly due to the existence of pinholes or non-deposited regions among the columnar structures.