Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Electrical and Luminescent Properties of OLEDs by Nickel Oxide Buffer Layer with Controlled Thickness

NiO 완충층 두께 조절에 의한 OLEDs 전기-광학적 특성

  • Choi, Gyu-Chae (Nano Functional Powder Research Group, Korea Institute of Materials Science) ;
  • Chung, Kook-Chae (Nano Functional Powder Research Group, Korea Institute of Materials Science) ;
  • Kim, Young-Kuk (Nano Functional Powder Research Group, Korea Institute of Materials Science) ;
  • Cho, Young-Sang (Nano Functional Powder Research Group, Korea Institute of Materials Science) ;
  • Choi, Chul-Jin (Nano Functional Powder Research Group, Korea Institute of Materials Science) ;
  • Kim, Yang-Do (Department of Materials Science and Engineering, Pusan National University)
  • 최규채 (재료연구소 나노기능분말연구그룹) ;
  • 정국채 (재료연구소 나노기능분말연구그룹) ;
  • 김영국 (재료연구소 나노기능분말연구그룹) ;
  • 조영상 (재료연구소 나노기능분말연구그룹) ;
  • 최철진 (재료연구소 나노기능분말연구그룹) ;
  • 김양도 (부산대학교 재료공학과)
  • Received : 2011.03.14
  • Published : 2011.10.25
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Abstract

In this study, we have investigated the role of a metal oxide hole injection layer (HIL) between an Indium Tin Oxide (ITO) electrode and an organic hole transporting layer (HTL) in organic light emitting diodes (OLEDs). Nickel Oxide films were deposited at different deposition times of 0 to 60 seconds, thus leading to a thickness from 0 to 15 nm on ITO/glass substrates. To study the influence of NiO film thickness on the properties of OLEDs, the relationships between NiO/ITO morphology and surface properties have been studied by UV-visible spectroscopy measurements and AFM microscopy. The dependences of the I-V-L properties on the thickness of the NiO layers were examined. Comparing these with devices without an NiO buffer layer, turn-on voltage and luminance have been obviously improved by using the NiO buffer layer with a thickness smaller than 10 nm in OLEDs. Moreover, the efficiency of the device ITO/NiO (< 5 nm)/NPB/$Alq_3$/ LiF/Al has increased two times at the same operation voltage (8V). Insertion of a thin NiO layer between the ITO and HTL enhances the hole injection, which can increase the device efficiency and decrease the turn-on voltage, while also decreasing the interface roughness.

Keywords

Acknowledgement

Supported by : 재료연구소

References

  1. C. Adachi, K. Nagai, and N. Tamoto, Appl. Phys. Lett. 66, 2679 (1995). https://doi.org/10.1063/1.113123
  2. S. Schols, S. VERLAAK, C. Rolin, D. Cheyns, J. Genoe, P. Heremans, Adv. Funct. Mater. 18, 136 (2008). https://doi.org/10.1002/adfm.200700769
  3. J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friedn, P. L. Burn, and A. B. Holmes, Nature 347, 539 (1990). https://doi.org/10.1038/347539a0
  4. J. Kido, K. Nagai, and Y. Okamoto, IEEE Trans. Electron Devices 40, 1342 (1993). https://doi.org/10.1109/16.216443
  5. S. L. Lai, M. Y. CHan, M. K. Fung, C. S. Lee, L. S. Hung, and S. T. Lee, Chem. Phys. Lett. 366, 128 (2002). https://doi.org/10.1016/S0009-2614(02)01553-1
  6. M. Pope, H. kallmane, and P. Magnate, J. Chem. Phys. 38, 2042 (1963). https://doi.org/10.1063/1.1733929
  7. C. W. Tang and S. A. Van Slyke, Appl. Phys. Lett. 51, 913 (1987). https://doi.org/10.1063/1.98799
  8. S. Y. Kim, K. Y. Hong, K. S. Kim, H. K. Yu, W. K. Kim, and J. L. Lee, J. Appl. Phys. Lett. 103, 076101 (2008).
  9. S. Y. Kim, K. B. Kim, Y. H. Tak, and J. L. Lee, J. Appl. Phys. Lett. 95, 2560 (2004).
  10. D. Guo, S. Entani, S. Ikeda, and K. Saiki, Chem. Phys. Lett. 429, 124 (2004).
  11. S. Y. Kim, K. Hong, and J. L. Lee, Appl. Phys. Lett. 90, 183508 (2007). https://doi.org/10.1063/1.2734916
  12. J. Ma, X. Y. Jiang, Z, Liang, J. Cao, X. Zhang, and Z. L. Zhang, Semicond. Sci, Technol. 24, 6 (2009).
  13. Z. Z. You and J. Y. Dong, Appl, Surf. Sci. 249, 271 (2005). https://doi.org/10.1016/j.apsusc.2004.12.006
  14. B. S. Kim, D. E. Kim, Y. K. Jang, N. S. Lee, O. K. Kwon, and Y. S. Kwon, Korean Phys. Soc. 50, 1858 (2007). https://doi.org/10.3938/jkps.50.1858
  15. J. M. Caruge, J. E. Halpert, V. Bulovic, and M. G. Bawendi, Nano, Lett. 6, 2991 (2006). https://doi.org/10.1021/nl0623208
  16. K. C. Chung, Y. K. Kim, and C. J. Choi, Kor. J. Met. Mater. 48, 320 (2010). https://doi.org/10.3365/KJMM.2010.48.04.320
  17. J. Y. Lee, Appl. Phys. Lett. 88, 73512 (2002).
  18. K. kato et al., Current Appl. Phys. 5, 321 (2005). https://doi.org/10.1016/j.cap.2004.01.047
  19. J. A. Thornton, An. Rev. Mater. Sci. 7, 239 (1977) https://doi.org/10.1146/annurev.ms.07.080177.001323
  20. I. M. Chan, T. Y. Hong, and F. C. Hong, Appl. Phys. Lett. 81, 1899 (2002). https://doi.org/10.1063/1.1505112