Abstract

Organic light-emitting devices (OLEDs) have posed as promising candidates for the next-generation display and lighting technologies with their various merits. Internal quantum efficiency η_IQE of OLEDs can now approach nearly 100% due to development of electrophosphorescence^[1]. However, the external quantum efficiency η_EQE of OLEDs is still limited by the optical confinement caused by higher refractive indices of substrate, organic materials and transparent conducting oxide (TCO), which result in total internal reflection and lower light extraction. Here, we report ITO nanomesh OLED with nanostructured composite electrode consisting of the ITO nanomesh and high-conductivity conducting polymer PEDOT:PSS for enhancing light extraction of OLEDs. Their very different refractive indices and incomplete planarization of the ITO nanomesh electrode give combined characteristics of photonic crystals and surface corrugation. This composite electrode enhances coupling of OLED internal radiation into the substrate, in addition to functioning as current conductor/injector. When combining this internal extraction structure and the external extraction scheme (e.g., by attaching extraction lens), a very high EQE of nearly 62% was achieved with a green phosphorescent OLED.

© 2015 Optical Society of America