A Study on the Dielectric Polarization of $ITO/Alq_3/Al$ Structure Organic Light-emitting Diodes

$ITO/Alq_3/Al$ 구조 유기 발광 소자의 유전분극 현상의 연구

  • Published : 2008.01.01

Abstract

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric polarization of organic light-emitting diodes using characteristics of impedance and equivalent circuit of $ITO/Alq_3/Al$. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of $1{\times}40Hz\;to\;1{\times}10^8Hz$. We obtained complex electrical conductivity, dielectric constant, and loss tangent(tan${\delta}$) of the device at room temperature. And, we obtained the equivalent circuit of $ITO/Alq_3/Al$ through analyzing dielectric constant and dielectric loss tangent. From these analyses, we could interpret a conduction mechanism and dielectric polarization.

References

  1. C. W. Tang and S. A. VanSlyke, "Organic electroluminescent diodes", Appl. Phys. Lett., Vol. 51, No. 12, p. 913, 1987 https://doi.org/10.1063/1.98799
  2. 電氣學會通信敎育會, "誘電體現象論", 7版, 日本電氣學會, p. 120-130, 1980
  3. P. W. M. Blom, M. J. M. de Jong, and J. J. M. Vleggaar, "Electron and hole transport in poly(p-phenylene vinylene) devices", Appl. Phys. Lett., Vol. 68, No. 23, pp. 3308-3310, 1996 https://doi.org/10.1063/1.116583
  4. Z.-L. Zhang, X.-Y Jiang, X.H. Xu, T. Nagatomo, and O. Omoto, "Stability enhancement of organic electroluminescent diode through buffer layer or rubrene doping in hole- transporting layer", Synth. Met., Vol. 91, pp. 131-132, 1997 https://doi.org/10.1016/S0379-6779(98)80073-8
  5. F. T. Reis, D. Mencaraglia, S. Ould Saad, I. Seguy, M. Oukachmih, P. Jolinat, and P. Destruel, "Electrical characterization of ITO/CuPc/Al diodes using temperature dependent capacitance spectroscopy and I-V measurements", J. Non-Crystalline Solids, Vol. 338-340, p. 599, 2004 https://doi.org/10.1016/j.jnoncrysol.2004.03.050
  6. E. Barsoukov and J. Ross Macdonald, "Impedance Spectroscopy-Theory, Experiment, and Applications", 2nd Eds, Wiley Interscience, p. 8, 2005
  7. C. Jonda and Andrea B. R. Mayer, "Investigation of the electronic properties of organic light-emitting devices by impedance spectroscopy", Chem. Mater., Vol. 11, p. 2429, 1999 https://doi.org/10.1021/cm991024b
  8. D. H. Chung, S. W. Hur, J. U. Lee, M. J. Song, K. U. Jang, S. K. Kim, H. N. Cho, T. W. Kim, "Frequency-dependent response in ITO/Alq3/Al organic light-emitting diodes", Current Applied Physics, Vol. 4, pp. 543-546, April, 2004 https://doi.org/10.1016/j.cap.2004.01.015
  9. 電氣學會通信敎育會, "誘電體現象論", 7版, 日本電氣學會, p. 203-258, 1980