Light extraction of organic light emitting diodes by defective hexagonal-close-packed array

Won Hoe Koo, Wooram Youn, Peifen Zhu, Xiao Hang Li, Nelson Tansu, Franky So*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

165 Scopus citations


Defective silica sphere arrays having locally hexagonal-closed-packed structure but lack of long range ordering were incorporated into organic light emitting diodes as grating to extract the waveguided light trapped in the indium tin oxide/organic layers and the glass substrate. Using these defective hexagonal-closed-packed gratings for light extraction, broad band lambertian emitters are obtained due to the periodicity broadening and the random orientation in the gratings, resulting in enhancements in current and power efficiencies by a factor of 1.7 and 1.9, respectively. An organic light-emitting diode device with a defective hexagonal-close-packed array can effectively extract the waveguide modes over all emission wavelengths and angles without spectral changes and directionality because of the broadening of the periodicity and the random orientation from the defective array pattern.

Original languageEnglish (US)
Pages (from-to)3454-3459
Number of pages6
JournalAdvanced Functional Materials
Issue number16
StatePublished - Aug 21 2012
Externally publishedYes


  • OLED
  • defective hexagonal-close-packed array
  • extraction
  • waveguide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Chemistry
  • Condensed Matter Physics
  • General Materials Science
  • Electrochemistry
  • Biomaterials


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