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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 22, Iss. 10 — May. 19, 2014
  • pp: 12392–12397

Enhancement of light extraction efficiency of OLEDs using Si3N4-based optical scattering layer

Sang-Jun Park, Yang Doo Kim, Ho Won Lee, Hyung Jin Yang, Joong-Yeon Cho, Young Kwan Kim, and Heon Lee  »View Author Affiliations

Optics Express, Vol. 22, Issue 10, pp. 12392-12397 (2014)

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An optical scattering layer, consisting of a Si3N4 nano-pillar array and a spin-coated hydrogen silsesquioxane (HSQ) planarization layer, was introduced to an organic light-emitting diode (OLED) substrate to increase the out-coupling efficiency. After plasma enhanced chemical vapor deposition (PECVD) of the Si3N4 layer, the nano-pillar array was created using nanoimprint lithography and reactive ion etching. As the Si3N4 pillar array has a refractive index of 2.0, photons generated in the organic layer are scattered by the Si3N4 structures and thus have a higher chance of being emitted from the device. The spin-coated HSQ planarization layer produces a flat substrate, which is essential for depositing a uniform organic material layer and assuring the electric conductivity of the transparent conducting oxide (TCO) layer. In this study, Si3N4 nano-structures with a height of 100 or 300 nm were used to enhance the out-coupling efficiency of the OLED devices. Although the electrical conductivity of the TCO layer deposited on the light scattering layer was slightly degraded, the OLED devices formed with the light scattering layer exhibited a higher luminous power at given electrical power. Consequently, the use of a planarized 300-nm-thick Si3N4 layer increased the external quantum efficiency of the OLED device by 50% at 10,000 cd/m2 compared to the reference OLED device fabricated on a flat glass substrate.

© 2014 Optical Society of America

OCIS Codes
(230.0230) Optical devices : Optical devices
(230.3670) Optical devices : Light-emitting diodes
(230.4000) Optical devices : Microstructure fabrication

ToC Category:

Original Manuscript: March 18, 2014
Revised Manuscript: May 1, 2014
Manuscript Accepted: May 2, 2014
Published: May 14, 2014

Sang-Jun Park, Yang Doo Kim, Ho Won Lee, Hyung Jin Yang, Joong-Yeon Cho, Young Kwan Kim, and Heon Lee, "Enhancement of light extraction efficiency of OLEDs using Si3N4-based optical scattering layer," Opt. Express 22, 12392-12397 (2014)

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