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Energy Express

Energy Express

  • Editor: Bernard Kippelen
  • Vol. 19, Iss. S4 — Jul. 4, 2011
  • pp: A786–A792

Soft holographic interference lithography microlens for enhanced organic light emitting diode light extraction

Joong-Mok Park, Zhengqing Gan, Wai Y. Leung, Rui Liu, Zhuo Ye, Kristen Constant, Joseph Shinar, Ruth Shinar, and Kai-Ming Ho  »View Author Affiliations


Optics Express, Vol. 19, Issue S4, pp. A786-A792 (2011)
http://dx.doi.org/10.1364/OE.19.00A786


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Abstract

Very uniform 2 μm-pitch square microlens arrays (μLAs), embossed on the blank glass side of an indium-tin-oxide (ITO)-coated 1.1 mm-thick glass, are used to enhance light extraction from organic light-emitting diodes (OLEDs) by ~100%, significantly higher than enhancements reported previously. The array design and size relative to the OLED pixel size appear to be responsible for this enhancement. The arrays are fabricated by very economical soft lithography imprinting of a polydimethylsiloxane (PDMS) mold (itself obtained from a Ni master stamp that is generated from holographic interference lithography of a photoresist) on a UV-curable polyurethane drop placed on the glass. Green and blue OLEDs are then fabricated on the ITO to complete the device. When the μLA is ~15 × 15 mm2, i.e., much larger than the ~3 × 3 mm2 OLED pixel, the electroluminescence (EL) in the forward direction is enhanced by ~100%. Similarly, a 19 × 25 mm2 μLA enhances the EL extracted from a 3 × 3 array of 2 × 2 mm2 OLED pixels by 96%. Simulations that include the effects of absorption in the organic and ITO layers are in accordance with the experimental results and indicate that a thinner 0.7 mm thick glass would yield a ~140% enhancement.

© 2011 OSA

OCIS Codes
(080.3630) Geometric optics : Lenses
(230.3990) Optical devices : Micro-optical devices

ToC Category:
Light-Emitting Diodes

History
Original Manuscript: March 16, 2011
Revised Manuscript: April 22, 2011
Manuscript Accepted: April 23, 2011
Published: June 6, 2011

Citation
Joong-Mok Park, Zhengqing Gan, Wai Y. Leung, Rui Liu, Zhuo Ye, Kristen Constant, Joseph Shinar, Ruth Shinar, and Kai-Ming Ho, "Soft holographic interference lithography microlens for enhanced organic light emitting diode light extraction," Opt. Express 19, A786-A792 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-S4-A786


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