Enhanced light extraction from organic light-emitting devices using a sub-anode grid

We demonstrate the highly effective extraction of waveguided light from the active region of organic light-emitting devices using a non-diffractive dielectric grid layer placed between the transparent anode and the substrate. The sub-anode grid couples out all waveguide mode power into the substrate without changing the device electrical properties, resulting in an increase in both the external quantum efficiency and luminous efficacy for green phosphorescent organic light-emitting devices from 15 ± 1% and 36 ± 2 lm W –1 to 18 ± 1% and 43 ± 2 lm W –1 . These characteristics are further increased to 40 ± 2% and 95 ± 4 lm W –1 when all glass modes are also extracted. The use of a thick electron transport layer further reduces surface plasmon modes, resulting in an increase in the substrate and air modes by 50 ± 8% compared with devices lacking the grids. The sub-anode grid has minimal impact on organic light-emitting device emission wavelength and viewing angle, and is likely to prove beneficial for a broad range of display and lighting applications. A diffractive dielectric grid placed between the anode and substrate of an organic light-emitting device is found to significantly enhance the extraction of light.