Enhanced Hole Injections in Organic Light Emitting Diode using Rhodium Oxide Coated Anode

  • Kim, Soo-Young (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Choi, Ho-Won (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Kim, Kwang-Young (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Tak, Yoon-Heung (LG Electronics Inc.) ;
  • Lee, Jong-Lam (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
  • 발행 : 2005.06.30

초록

We compare electrical and optical properties of organic light emitting diodes (OLEDs) using rhodium-oxide-coated indium-tin-oxide ($O_2$-Rh/ITO) to that using $O_2$-plasma-treated ITO (ITO) anodes. The turn-on voltage decreased from 7 V to 5 V and luminance value increased when the $O_2$ plasma treated Rh layer was deposited on ITO. Synchrotron radiation photoelectron spectroscopy results showed the dipole energies of both ITO and $O_2$-Rh/ITO were same with each other, - 0.3 eV, meaning the formation of same amount of interface dipole. The secondary electron emission spectra revealed that the work function of $O_2$-Rh/ITO is higher hy 0.2 eV than that of ITO, resulting in the decrease of the tum-on voltage via reduction ofhole injection barrier.

키워드

참고문헌

  1. K. H. Lee, H. W. Jang, K.-B. Kim, Y.-H. Tak, and J.-L. Lee, J. Appl. Phys. 95, 586 (2004) https://doi.org/10.1063/1.1633351
  2. I.-M. Chan and F. C. Hong, Thin Solid Films. 450, 304 (2004) https://doi.org/10.1016/j.tsf.2003.10.022
  3. C.-M. Hsu and W.-T. Wu, Appl. Phys. Lett. 85, 840 (2004) https://doi.org/10.1063/1.1777416
  4. N. Koch, A. Kahn, J. Ghijsen, J.-J. Pireaux, J. Schwartz, R. L. Johnson, and A. Elschner, Appl. Phys. Lett. 82, 70 (2003) https://doi.org/10.1063/1.1532102
  5. L. Yan, N. J. Watkins, S. Zorba, Y. Gao, and C. W. Tang, Appl. Phys. Lett. 81, 2752 (2002) https://doi.org/10.1063/1.1512826
  6. J. F. Moulder, W. F. Strickle, P. E. Sobol, and K. D. Bomben, Handbook of X-ray Photoelectron Spectroscopy (Perkin-Elmer, Eden Prairie, MN, 1992)
  7. J. M. Baik and J.-L. Lee, Met. Mater. Int. 10, 555 (2004) https://doi.org/10.1007/BF03027418
  8. I. G. Hill, A. Rajagopal, A. Kahn, and Y. Hu, Appl. Phys. Lett., 73, 662 (1998) https://doi.org/10.1063/1.121940
  9. X. Crispin, V. Geskin, A. Crispin, J. Cornil, R. Lazzaroni, W. R. Salaneck, and J.-L. Bredas, J. Am. Chem. Soc., 124, 8131 (2002) https://doi.org/10.1021/ja025673rS0002-7863(02)05673-1
  10. Z. Qiao, R. Latz, and D. Mergel, Thin Solid Films, 466, 250 (2004) https://doi.org/10.1016/j.tsf.2004.02.094