Long-Term Degradation Mechanism of Organic Light Emitting Devices Based on Small Molecules


The intrinsic degradation of tris(8-hydroxyquinoline) aluminum (AlQ3)-based organic light emitting devices, that leads to the long-term decrease in the electroluminescence efficiency of the devices operated under constant current conditions, is studied. The injection of holes in A1Q3 is found to be the main factor responsible for device degradation. OLEDs with dual HTLs in different arrangements are also presented to demonstrate the proposed degradation mechanism. The role of various approaches to increase OLED lifetime, such as, doping the hole transport layer, introducing a buffer layer at the hole-injecting contact, or using a mixed emitting layer of hole and electron transporting molecules, is explained.

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  1. 1.

    C. W. Tang, S. A. Van Slyke, C. H. Chen, Appl. Phys. Lett. 65, 3610 (1989).

    CAS  Google Scholar 

  2. 2.

    J. Kido and Y. Iizumi, Appl. Phys. Lett. 73, 2721 (1998).

    CAS  Article  Google Scholar 

  3. 3.

    Z. Shen, P. B. Burrows, V. Bulovic, S. R. Forrest, M. E. Thompson, Science 276, 2009 (1997).

    CAS  Article  Google Scholar 

  4. 4.

    J.R. Sheats, H. Antoniadis, M. Hueschen, W. Leonard, J. Miller, R. Moon, D. Roitman and A. Stocking, Science 273, 884 (1996).

    CAS  Article  Google Scholar 

  5. 5.

    J. McElvain, H. Antoniadis, M. R. Hueschen, J. N. Miller, D. M. Roitman, J. R. Sheets and R. L. Moon, J. Appl. Phys. 80, 6002 (1996).

    Article  Google Scholar 

  6. 6.

    H. Aziz, Z. Popovic, S. Xie, A. Hor, N. Hu, C. Tripp and G. Xu, Appl. Phys. Lett. 72, 756 (1998), H. Aziz, Z. Popovic, C. P. Tripp, N. Hu, A. Hor and G. Xu, ibid., p. 2642.

    CAS  Article  Google Scholar 

  7. 7.

    P. E. Burrows, V. Bulovic, S. R. Forrest, L. S. Sapochak, D. M. McCarty and M. E. Thompson., Appl. Phys. Lett. 65, 2922 (1994).

    CAS  Article  Google Scholar 

  8. 8.

    Hamada, T. Sano, K. Shibata, K. Kuroki, Jpn. J. Appl. Phys. 34, L824, (1995).

    CAS  Article  Google Scholar 

  9. 9.

    S. A. Van Slyke, C. H. Chen, C. W. Tang, Appl. Phys. Lett. 69, 2160 (1996).

    Article  Google Scholar 

  10. 10.

    J. Shi and C. W. Tang, Appl. Phys. Lett. 70, 1665 (1997).

    CAS  Article  Google Scholar 

  11. 11.

    C. Adachi, K. Nagai, N. Tamoto, Appl. Phys. Lett. 66, 2679 (1995).

    CAS  Article  Google Scholar 

  12. 12.

    Z. D. Popovic, H. Aziz, C. P. Tripp, N. X. Hu, A. M. Hor and G. Xu., in roceedings of the SPIE, Volume3476, Organic Light-Emitting Materials and Devices II, San Diego, CA, July1998, pp68–73.

    CAS  Article  Google Scholar 

  13. 13.

    H. Vestweber and W. Rieb, Synth. Met. 91, 181 (1997).

    CAS  Article  Google Scholar 

  14. 14.

    J. Yang and J. Shen, J. Appl. Phys. 84, 2105 (1998).

    CAS  Article  Google Scholar 

  15. 15.

    G. G. Malliaras and J. C. Scott, J. Appl. Phys. 83, 5399 (1998).

    CAS  Article  Google Scholar 

  16. 16.

    F. Papadimitrakopoulos, X.-M. Zhang, D. L. Thomsen III, K. A. Higginson, Chem. Mater. 8, 1363 (1996).

    CAS  Article  Google Scholar 

  17. 17.

    H. Aziz, Z. D. Popovic, N. X. Hu, A. M. Hor and G. Xu, Science 283, 1900 (1999).

    CAS  Article  Google Scholar 

  18. 18.

    L. B. Bin, S. A. Jenekhe, R. H. Young, P. M. Borsenberger, Appl. Phys. Lett. 70, 2052 (1997).

    Article  Google Scholar 

  19. 19.

    J. D. Anderson et al., J. Am. Chem. Soc. 120, 9646 (1998).

    CAS  Article  Google Scholar 

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Aziz, H., Popovic, Z.D., Hu, NX. et al. Long-Term Degradation Mechanism of Organic Light Emitting Devices Based on Small Molecules. MRS Online Proceedings Library 558, 507–512 (1999). https://doi.org/10.1557/PROC-558-507

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