Al₂O₃/Ag/Al₂O₃ multilayer thin film passivation prepared by plasma damage-free linear facing target sputtering for organic light emitting diodes

Al₂O₃/Ag/Al₂O₃ multilayer passivation prepared by plasma damage-free linear facing target sputtering (LFTS) was investigated as a function of inserted Ag thickness. Using antireflection effect of the Ag layer that is sandwiched between dielectric Al₂O₃ layers, we can obtain a transparent Al ₂O₃/Ag/Al₂O₃ multilayer passivation for organic light emitting diodes (OLEDs). It was found that insertion of the Ag layer with optimized thickness between Al₂O₃ layers lead to improvement of the optical transparency and water vapor transmission rate of the Al₂O₃/Ag/Al₂O₃ multilayer. In addition, current density-voltage-luminescence of an OLED passivated with Al₂O₃/Ag (10 nm)/Al₂O₃ multilayer was similar to that of an OLED with nonpassivated sample, indicating that the performance of an OLED is not affected by high-density plasma during the LFTS process. Moreover, the lifetime to half initial luminance of an OLED passivated with Al₂O₃/Ag (10 nm)/Al₂O₃ multilayer was longer than that of a nonpassivated sample.