BROWSE

Related Researcher

Author's Photo

Baik, Jeong Min
Nano Energy and Environmental Materials Lab
Research Interests
  • Nanogenerators, antimicrobial material, catalysis, smart sensors

ITEM VIEW & DOWNLOAD

Highly efficient organic light-emitting diodes with hole injection layer of transition metal oxides

Cited 40 times inthomson ciCited 35 times inthomson ci
Title
Highly efficient organic light-emitting diodes with hole injection layer of transition metal oxides
Author
Kim, Soo YoungBaik, Jeong MinYu, Hak KiLee, Jong-Lam
Keywords
Hole injection; Indium tin oxides (ITO) anodes; Organic light-emitting diodes; X-ray reflectivity
Issue Date
2005-11
Publisher
AMER INST PHYSICS
Citation
JOURNAL OF APPLIED PHYSICS, v.98, no.9, pp. -
Abstract
We report on the advantage of interlayers using transition-metal oxides, such as iridium oxide (IrOx) and ruthenium oxide (RuOx), between indium tin oxide (ITO) anodes and 4'-bis[N-(1-naphtyl)-N-phenyl-amino]biphenyl (alpha-NPD) hole transport layers on the electrical and optical properties of organic light-emitting diodes (OLEDs). The operation voltage at a current density of 100 mA/cm(2) decreased from 17 to 11 V for OLEDs with 3-nm-thick IrOx interlayers and from 17 to 14 V for OLEDs with 2-nm-thick RuOx ones. The maximum luminance value increased about 50% in OLED using IrOx and 108% in OLED using RuOx. Synchrotron radiation photoelectron spectroscopy results revealed that core levels of Ru 3d and Ir 4f shifted to high binding energies and that the valence band was splitting from metallic Fermi level as the surface of the transition metal was treated with O-2 plasma. This provides evidence that the transition-metal surface transformed to a transition-metal oxide. The surface of the transition metal became smoother with the O-2 plasma treatment. The thickness was calculated to be 0.4 nm for IrOx and 0.6 nm for RuOx using x-ray reflectivity measurements. Secondary electron emission spectra showed that the work function increased by 0.6 eV for IrOx and by 0.4 eV for RuOx. Thus, the transition-metal oxides lowered the potential barrier for hole injection from ITO to alpha-NPD, reducing the turn-on voltage of OLEDs and increasing the quantum efficiency. (c) 2005 American Institute of Physics
URI
Go to Link
DOI
10.1063/1.2123375
ISSN
0021-8979
Appears in Collections:
MSE_Journal Papers
Files in This Item:
1.2123375.pdf Download

find_unist can give you direct access to the published full text of this article. (UNISTARs only)

Show full item record

qrcode

  • mendeley

    citeulike

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

MENU