Role of the dielectric capping layer in enhancement of light outcoupling for semitransparent metal-cathode organic light-emitting devices

We study theoretically the effects of the dielectric capping layer on the light outcoupling efficiency for semitransparent metal-cathode organic light-emitting devices. The outcoupling enhancement is co-determined by the improved transmission, the reduced (or improved) reflection, and the reduced absorption, as well as the suppressed surface plasmon polaritons. For some metals such as aluminium, the outcoupling efficiency can be enhanced largely by capping, but it can hardly be enhanced for some metals such as ytterbium. As a practical cathode, the Ag(15 nm)/TeO2(24 nm) combination achieves an outcoupling efficiency of 21.5%, competitive with bottom-emission devices.OpticsSCI(E)EI0ARTICLE9733-736