Publication Date

2-19-2018

Department

Ames Laboratory; Physics and Astronomy; Microelectronics Research Center (MRC); Electrical and Computer Engineering;

Campus Units

Electrical and Computer Engineering, Physics and Astronomy, Ames Laboratory, Microelectronics Research Center (MRC)

Report Number

IS-J 9585

DOI

10.1002/adom.201701244

Journal Title

Advanced Optical Materials

Volume Number

6

Issue Number

4

First Page

1701244

Abstract

A key scientific and technological challenge in organic light-emitting diodes (OLEDs) is enhancing the light outcoupling factor ηout, which is typically <20%. This paper reports experimental and modeling results of a promising approach to strongly increase ηout by fabricating OLEDs on novel flexible nanopatterned substrates that result in a >2× enhancement in green phosphorescent OLEDs (PhOLEDs) fabricated on corrugated polycarbonate (PC). The external quantum efficiency (EQE) reaches 50% (meaning ηout ≥50%); it increases 2.6x relative to a glass/ITO device and 2× relative to devices on glass/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) or flat PC/PEDOT:PSS. A significant enhancement is also observed for blue PhOLEDs with EQE 1.7× relative to flat PC. The corrugated PC substrates are fabricated efficiently and cost-effectively by direct room-temperature molding. These substrates successfully reduce photon losses due to trapping/waveguiding in the organic+anode layers and possibly substrate, and losses to plasmons at the metal cathode. Focused ion beam gauged the conformality of the OLEDs. Dome-shaped convex nanopatterns with height of ∼280–400 nm and pitch ∼750–800 nm were found to be optimal. Substrate design and layer thickness simulations, reported first for patterned devices, agree with the experimental results that present a promising method to mitigate photon loss paths in OLEDs.

Language

en

Department of Energy Subject Categories

29 ENERGY PLANNING, POLICY, AND ECONOMY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Available for download on Tuesday, February 19, 2019

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