Elimination of Plasmon Losses and Enhanced Light Extraction of Top-Emitting Organic Light-Emitting Devices Using a Reflective Subelectrode Grid

Abstract

We demonstrate high-efficiency light extraction for top-emitting organic light-emitting devices (OLEDs) comprising a transparent conductive oxide on the surface of a nondiffractive, reflecting metal-coated scattering grid located beneath the organic active region. The grid scatters light trapped in waveguide modes without changing the device electrical properties or causing significant plasmonic losses. This results in an increase in external quantum efficiency for green phosphorescent organic light-emitting devices from 20 ± 1% to 30 ± 2%, for structures without and with the reflecting grid. Adding a low refractive index capping layer reduces the spectral angular dependence characteristic of top-emitting OLEDs. The improvement in light extraction by substrate modification allows for optimization of the optical design without necessitating changes in the design or structure of the OLEDs themselves.