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Abstract: Organic light-emitting diodes (OLEDs) with aluminum cathodes prepared by the ion beam-assisted deposition (IBAD) have a longer lifetime than thermally evaporated one. The electroluminescent features were examined to compare the rate of degradation in the devices with thermally evaporated Al cathodes and ion beam-assisted Al cathodes. 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 phenyl-substituted poly-p-phenylene-vinylene (Ph-PPVs) and 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 30nm 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. [Copyright &y& Elsevier]

Abstract: Highly stable organic electroluminescent devices based on spin-coated poly-p-phenylene-vynylene (PPV) thin films have been achieved. We investigated the electrical properties of ion beam assisted aluminum cathode contacting PPV compared that of thermal evaporation. Energetic particles of Al assisted by Ar+ ion increase the contact area between Al and PPV minimizing contact resistance. In addition, dense Al cathode inhibits the permeation of H2O and O2 through pinhole defects, which results in retarding dark spot growth. It is believed that the lifetime of organic light-emitting diode (OLED) device was enhanced effectively by ion beam assisted deposition process resulting from dense Al structure. [Copyright &y& Elsevier]

Abstract: A long-lived organic light emitting diode (OLED) was fabricated using a dense aluminum cathode prepared by the ion-beam-assisted deposition (IBAD) process. We investigated the passivation properties of ion-beam-assisted and thermal evaporation-induced 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-PPV and 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 30nm 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. [Copyright &y& Elsevier]

Abstract: We have fabricated highly stable organic electroluminescent devices based on spin-coated poly-p-phenylene-vynylene (PPV) thin films. The electrical properties of aluminum cathode, prepared by ion beam assisted deposition, on PPV have been investigated and compared to those by thermal evaporation. Although energetic particles of Al assisted by Ar+ ion may damage the organic material, I–V–L characteristics are improved by applying thin Al buffer layer. In addition, a dense Al cathode inhibits the permeation of H2O and O2 into PPV film through pinhole defects, and thus retards dark spot growth. It may be deduced from highly packed structure of Al cathode with smaller junction resistance between Al and PPV. In conclusion, the lifetime of organic light-emitting device (OLED) has been extended effectively by dense Al film through ion beam assisted deposition process. [Copyright &y& Elsevier]

Abstract: We have fabricated highly stable organic electroluminescent devices based on spin-coated poly-p-phenylene-vynylene (PPV) thin films. The electrical properties of aluminum cathode, prepared by ion beam assisted deposition, on PPV have been investigated and compared to those by thermal evaporation. Although energetic particles of Al assisted by Ar+ ion may damage the organic material, I–V–L characteristics are improved by applying thin Al buffer layer. In addition, a dense Al cathode inhibits the permeation of H2O and O2 into PPV film through pinhole defects, and thus retards dark spot growth. It may be deduced from highly packed structure of Al cathode with an increase in the contact area between Al and PPV that reduce the contact resistance. In conclusion, the lifetime of organic light-emitting device (OLED) has been extended effectively by dense Al film through ion beam assisted deposition process. [Copyright &y& Elsevier]

Highly stable organic electroluminescent devices based on spin-coated soluble phenyl-substituted poly-p-phenylene-vinylene (Ph-PPVs) thin films have been achieved. We investigated the electrical properties of ion beam assisted aluminum cathode contacting Ph-PPV and compared them to those of thermal evaporation. Although energetic particles of Al assisted by Ar+ ion generate the damages in organic materials, I–V–L characteristics can be improved by using thin Al buffer layer to avoid damages. In addition, dense Al cathode inhibits the permeation of H2O and O2 through pinhole defects, which results in retarding gas bubble formation. This may be explained by highly packed structure of Al cathode and decrease of the contact resistance between Al and Ph-PPV. It is believed that the larger contact area and increase of density of state in Ph-PPV minimize the contact resistance and that results in the longevity of organic light-emitting devices (OLEDs). [Copyright &y& Elsevier]