Transactions on Electrical and Electronic Materials

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Optical Effect due to Thickness Variation of Electron Injection Layer in Organic Light-emitting Diodes

  • Lee, Young-Hwan (Department of Electrical Engineering, Kwangwoon University) ;
  • Lee, Kang-Won (Department of Electrical Engineering, Kwangwoon University) ;
  • Yi, Keon-Young (Department of Electrical Engineering, Kwangwoon University) ;
  • Hong, Jin-Woong (Department of Electrical Engineering, Kwangwoon University) ;
  • Kim, Tae-Wan (Department of Physics, Hongik University)
  • Published : 2008.02.29
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Abstract

Organic light-emitting diodes (OLEDs) are attractive because of possible application in display with low-operating voltage, low-power consumption, self-emission and capability of multicolor emission by the selection of emissive materials. To investigated the optical effects, we studied the electrical and optical characteristics due to thickness variation of electron injection materials LiF on organic light-emitting diodes in the ITO (indium-tin-oxide)/N,N'-diphenyl-N, N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline) aluminum $(Alq_3)/LiF$ layer/Al device. We maintained the thicknesses of TPD and $Alq_3$ layers at 40 nm and 60 nm, respectively. The deposition rates of TPD and $Alq_3$ were in the $1.5{\AA}/s$ under a base pressure of $5{\times}10^{-6}$ Torr. It was found that luminance and luminous efficiency of the device with 0.7 nm LiF layer improve 25 times and 7 times than the device without the LiF layer, respectively.

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References

  1. G. B. Blanchet, Y. L. Loo, J. A. Rogers, F. Gao, and C. R. Fincher, "Large area, high resolution, dry printing of conducting polymers for organic electronics", Appl. Phys. Lett., Vol. 82, p. 463, 2003 https://doi.org/10.1063/1.1533110
  2. H. E. A. Huitema, G. H. Gelinck, J. B. P. H. Putten, K. E. Kuijk, K. M. Hart, E. Cantatore, and D. M. Leeuw, "Active-matrix displays driven by solution processed polymeric transistors", Adv. Mater., Vol. 14, p. 1201, 2002 https://doi.org/10.1002/1521-4095(20020903)14:17<1201::AID-ADMA1201>3.0.CO;2-5
  3. L. S. Hung and C. H. Chen, "Recent progress of molecular organic electroluminescent materials and devices", Materials Science and Engineering, R., Vol. 39, p. 143, 2002 https://doi.org/10.1016/S0927-796X(02)00093-1
  4. M. Pope, H. P. Kallmann, and P. Magnante, "Electroluminescence in organic crystals", J. Chem. Phys., Vol. 38, p. 2042, 1963 https://doi.org/10.1063/1.1733929
  5. C. W. Tang and S. A. VanSlyke, "Organic electroluminescent diodes", Appl. Phys. Lett., Vol. 51, p. 913, 1987 https://doi.org/10.1063/1.98799
  6. J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackey, R. H. Friend, P. L. Burns, and A. B. Holmes, "Light-emitting diodes based on conjugated polymers", Nature, Vol. 347, p. 539, 1990 https://doi.org/10.1038/347539a0
  7. C. Jiang W. Yang, J. Peng, S. Xiao, and Y. Cao, "High-efficiency, saturated red-phosphorescent polymer light-emitting diodes based on conjugated and non-conjugated polymers doped with an Ir complex", Adv. Mater., Vol. 16, p. 537, 2004 https://doi.org/10.1002/adma.200306331
  8. W. J. Kim, J. H. Yang, T. Y. Kim, J. Jeong, Y. H. Lee, J. W. Hong, H. Y. Park, and T. W. Kim, "Efficiency improvement of organic light-emitting diodes depending on thickness of hole injection materials", Trans. EEM, Vol. 6, No. 5, p. 233, 2005 https://doi.org/10.4313/TEEM.2005.6.5.233
  9. Y. H. Lee, W. J. Kim, T. Y. Kim, J. H. Yang, K. S. Cho, J. W. Hong, J. Y. Shin, and T. W. Kim, "Effect of deposition rate of organic layer on electrical and optical characteristics of OLEDs", Mol. Crys. Liq. Crys., Vol. 462, p. 143, 2007 https://doi.org/10.1080/07370650601013088
  10. Y. H. Lee, W. J. Kim, T. Y. Kim, J. Jung, J. Y. Lee, H. D. Park, T. W. Kim, and J. W. Hong, "Electrical characteristics and efficiency of OLEDs depending on hole-injection layer", Curr. Appl. Phys., Vol. 7, p. 409, 2007 https://doi.org/10.1016/j.cap.2006.09.021
  11. J. Kido, M. Kohda, K. Okuyama, and K. Nagai, "Organic electroluminescent devices based on molecularly doped polymers", Appl. Phys. Lett., Vol. 61, p. 761, 1992 https://doi.org/10.1063/1.107790