Deep-red light-emitting phosphorescent dendrimer encapsulated tris-[2-benzo[b]thiophen-2-yl-pyridyl] iridium (III) core for light-emitting device applications

Kyung Moon Jung, Kyung Hwan Kim, Jung Il Jin, Min Ju Cho, Dong Hoon Choi

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New deep-red light-emitting phosphorescent dendrimers with hole-transporting carbazole dendrons were synthesized by reacting tris(2-benzo[b]thiophen-2-yl-pyridyl) iridium (III) complex with carbazolyl dendrons by DCC-catalyzed esterification. The resulting first-, second-, and third-generation dendrimers were found to be highly efficient as solution-processable emitting materials and for use in host-free electrophosphorescent light-emitting diodes. We fabricated a host-free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/ Alq3 (40 nm)/LiP (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m2 at 383.4 mA/cm2 (12 V) for 15, 1302 cd/m2 at 321.3 mA/cm2 (14 V) for 16, and 422 cd/m2 at 94.4 mA/cm 2 (18 V) for 17. The third-generation dendrimer, 17 (ηext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light-harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep-red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole-transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution-processable materials for dendrimer light-emitting diode (DLED) applications.

Original languageEnglish
Pages (from-to)7517-7533
Number of pages17
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Issue number22
Publication statusPublished - 2008 Nov 15



  • Absorption
  • Carrier mobility
  • Dendrimer
  • Electroluminescence
  • Fluorescence
  • Light-emitting diodes
  • Luminescence
  • Phosphorescence
  • Photoluminescence
  • Triplet energy transfer

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Organic Chemistry

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