Plasmon loss improved top emission organic light-emitting diode with multi capping layer

Abstract

Here, we report surface plasmon (SP) loss improved top-emitting organic light emitting diodes (TEOLEDs) by applying our unique cathode unit structure. Generally, the TEOLED has high optical loss portion of SP mode compared to the bottom emitting OLED and it causes low out-coupling efficiency in the TEOLED. Commonly used TEOLED structure uses Ag:Mg (10:1, 22 nm) cathode with high refractive index single capping layer, which has high optical loss portion of SP mode. To reduce SP mode loss in the TEOLED, we applied thin Ag:Mg (10:1, 12 nm) cathode with multi-capping layer. Our cathode unit reduces 55% of SP loss and enhances about 20% efficiency. Our approach to enhance out-coupling efficiency will be useful to make high efficiency TEOLEDs.