Optical transmission characteristics of epsilon negative tri-metal layer electrode for OLED

In this work, the optical characteristics of various epsilon negative tri-metal layer electrodes on organic light-emitting diodes (OLEDs) are investigated by full wave simulation and experiments to establish a transmittance database based on the kind and thickness of the metals. The established database shows that the optical transmittance of tri-metal layer electrode heavily depends on the absolute value of negative epsilon and the thickness of each metal layer. Tri-metal layer electrode structures were fabricated by sandwiching Ag, Cu, and Al between two Ni layers for red phosphorescent OLEDs. The electrical and optical characteristics of indium-tin-oxide (ITO) based and tri-metal layer electrodes-based devices are compared and the results indicate that the proposed tri-metal layer could replace ITO in optical applications.