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Journal of Photonics for Energy • Open Access

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils
Author(s): Harmen Rooms; Dorothee Hermes; Stephan Harkema; Cristina Tanase; Ton van Mol; Paul W. M. Blom; Joanne Wilson

Paper Abstract

We have investigated how to optimize the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes (OLEDs) based on metal foil substrates with the aim of creating efficient flexible devices for lighting and signage applications. By systematically varying the device architecture we were able to tune the optical microcavity which exists within the device structure and observe the change in performance. We paid particular attention to the effects of the metal foil roughness. We have seen that by changing the layer thickness of the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) [PEDOT:PSS] in the device, and the substrate reflectivity and roughness we can obtain efficacies not too far from those achieved for standard bottom-emissive devices on glass substrates made with the same emitter. The angle dependence of luminance can be tuned from pointing in the forward direction via Lambertian to having a maximum at around 65°, and we have used optical modeling to help us find the optimum device structure. We conclude that (rough) metal foils are a realistic possibility for making flexible OLEDs and have demonstrated large area (up to 12 cm × 12 cm), thin film encapsulated, flexible devices.

Paper Details

Date Published: 1 January 2011
PDF: 17 pages
J. Photon. Energy 1(1) 011024 doi: 10.1117/1.3590937
Published in: Journal of Photonics for Energy Volume 1, Issue 1
Show Author Affiliations
Harmen Rooms, TNO Science and Industry (Netherlands)
Dorothee Hermes, TNO Science and Industry (Netherlands)
Stephan Harkema, TNO Science and Industry (Netherlands)
Cristina Tanase, Philips Research Nederland B.V. (Netherlands)
Ton van Mol, TNO Science and Industry (Netherlands)
Paul W. M. Blom, TNO Science and Industry (Netherlands)
Joanne Wilson, TNO Science and Industry (Netherlands)

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