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Proceedings Paper

Enhanced light extraction from organic light-emitting devices using a sub-anode grid (Presentation Recording)
Author(s): Yue Qu; Michael Slootsky; Stephen Forrest
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Paper Abstract

We demonstrate a method for extracting waveguided light trapped in the organic and indium tin oxide layers of bottom emission organic light emitting devices (OLEDs) using a patterned planar grid layer (sub-anode grid) between the anode and the substrate. The scattering layer consists of two transparent materials with different refractive indices on a period sufficiently large to avoid diffraction and other unwanted wavelength-dependent effects. The position of the sub-anode grid outside of the OLED active region allows complete freedom in varying its dimensions and materials from which it is made without impacting the electrical characteristics of the device itself. Full wave electromagnetic simulation is used to study the efficiency dependence on refractive indices and geometric parameters of the grid. We show the fabrication process and characterization of OLEDs with two different grids: a buried sub-anode grid consisting of two dielectric materials, and an air sub-anode grid consisting of a dielectric material and gridline voids. Using a sub-anode grid, substrate plus air modes quantum efficiency of an OLED is enhanced from (33±2)% to (40±2)%, resulting in an increase in external quantum efficiency from (14±1)% to (18±1)%, with identical electrical characteristics to that of a conventional device. By varying the thickness of the electron transport layer (ETL) of sub-anode grid OLEDs, we find that all power launched into the waveguide modes is scattered into substrate. We also demonstrate a sub-anode grid combined with a thick ETL significantly reduces surface plasmon polaritons, and results in an increase in substrate plus air modes by a >50% compared with a conventional OLED. The wavelength, viewing angle and molecular orientational independence provided by this approach make this an attractive and general solution to the problem of extracting waveguided light and reducing plasmon losses in OLEDs.

Paper Details

Date Published:
PDF: 1 pages
Proc. SPIE 9566, Organic Light Emitting Materials and Devices XIX, 95661C; doi: 10.1117/12.2187295
Show Author Affiliations
Yue Qu, Univ. of Michigan (United States)
Michael Slootsky, Univ. of Michigan (United States)
Stephen Forrest, Univ. of Michigan (United States)


Published in SPIE Proceedings Vol. 9566:
Organic Light Emitting Materials and Devices XIX
Franky So; Chihaya Adachi; Jang-Joo Kim, Editor(s)

Video Presentation

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