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Energy Express

Energy Express

  • Editor: Bernard Kippelen
  • Vol. 18, Iss. S4 — Nov. 8, 2010
  • pp: A631–A639

Improving the outcoupling efficiency of indium-tin-oxide-free organic light-emitting diodes via rough internal interfaces

Boris Riedel, Inga Kaiser, Julian Hauss, Uli Lemmer, and Martina Gerken  »View Author Affiliations


Optics Express, Vol. 18, Issue S4, pp. A631-A639 (2010)
http://dx.doi.org/10.1364/OE.18.00A631


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Abstract

We present low-cost texturing methods to produce different surface roughnesses on glass substrates. Using sand blasting, abrasion and wet etching we achieve roughnesses of about 50 nm to 250 nm (root mean squared roughness Rq). These textured substrates are used as extraction elements for guided modes and substrate modes in organic light-emitting diodes (OLEDs). We evaporate 50 nm of the high index material Ta2O5 on the textured substrate, which acts as waveguide layer, and flatten it with the transparent photoresist SU-8. On top of that, we fabricate indium tin oxide (ITO)-free OLEDs, which are characterized by electroluminescence and photoluminescence measurements. The devices with rough interfaces obtain an up to 37.4% and 15.5% (at 20 mA/cm2) enhanced emission and it is shown that the enhancement is due to an increased outcoupling efficiency.

© 2010 OSA

OCIS Codes
(240.5770) Optics at surfaces : Roughness
(250.3680) Optoelectronics : Light-emitting polymers
(260.3800) Physical optics : Luminescence
(290.5880) Scattering : Scattering, rough surfaces
(310.1860) Thin films : Deposition and fabrication
(310.6845) Thin films : Thin film devices and applications

ToC Category:
Light-Emitting Diodes

History
Original Manuscript: September 20, 2010
Manuscript Accepted: October 19, 2010
Published: October 28, 2010

Citation
Boris Riedel, Inga Kaiser, Julian Hauss, Uli Lemmer, and Martina Gerken, "Improving the outcoupling efficiency of indium-tin-oxide-free organic light-emitting diodes via rough internal interfaces," Opt. Express 18, A631-A639 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-S4-A631


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