Al_2O_3/Ag/Al_2O_3 multilayer thin film passivation prepared by plasma damage-free linear facing target sputtering for organic light emitting diodes

摘要

Al_2O_3/Ag/Al_2O_3 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 Al_2O_3 layers, we can obtain a transparent Al_2O_3/Ag/Al_2O_3 multilayer passivation for organic light emitting diodes (OLEDs). It was found that insertion of the Ag layer with optimized thickness between Al_2O_3 layers lead to improvement of the optical transparency and water vapor transmission rate of the Al_2O_3/Ag/Al_2O_3 multilayer. In addition, current density-voltage-luminescence of an OLED passivated with Al_2O_3/Ag (10 nm)/Al_2O_3 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 Al_2O_3/Ag (10 nm)/Al_2O_3 multilayer was longer than that of a nonpassivated sample.