Jpn. J. Appl. Phys. 43 (2004) pp. L1226-L1228  |Previous Article| |Next Article|  |Table of Contents|
|Full Text PDF (122K)| |Buy This Article|


Improved Performance of Electrophosphorescent Organic Light-emitting Diode by Graded Doped Emissive Layer

Gangtie Lei, Liduo Wang and Yong Qiu

Key Laboratory of Organic-Optoelectronics & Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China

(Received June 28, 2004; accepted July 16, 2004; published September 3, 2004)

We report a blue electrophosphorescent organic light-emitting diode (PHOLED) with performance improved by designing a graded doped emissive layer. The graded doped emissive layer is formed by doping a guest material, bis[(4,6-difluorophenyl)-pyridinato-N, C2'] (picolinato) Ir(III) (FIrpic), in the host material, N, N'-dicarbazolyl-1, 4-dimethene-benzene (DCB), with a gradient increase in concentration. The graded doped emissive layer PHOLED shows a peak power efficiency of 15.4 cd/A and a maximum brightness of 35000 cd/m2, a sharp increase compared to the conventional PHOLED which has a peak power efficiency of 8.7 cd/A and a maximum brightness of 17000 cd/m2. It is also noted that the efficiency of the graded doped device dropped slowly at high current density. We attribute this improvement mainly to the fact that the concentration distribution of guest material is in accord with that of electrons in the devices and the carrier recombination zone is adjusted away from the electrodes.

DOI: 10.1143/JJAP.43.L1226
KEYWORDS:electrophosphorescence, organic light-emitting diode, graded doped emissive layer

|Full Text PDF (122K)| |Buy This Article| Citation:

References | Citing Articles (8)

  1. M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson and S. R. Forrest: Nature 395 (1998) 151[CrossRef].
  2. C. Adachi, R. C. Kwong, P. Djurovich, M. A. Baldo, M. E. Thompson and S. R. Forrest: Appl. Phys. Lett. 79 (2001) 2082[AIP Scitation].
  3. Y. Kawamura, S. Yanagida and S. R. Forrest: J. Appl Phys. 92 (2002) 87[AIP Scitation].
  4. R. J. Holmes, S. R. Forrest, Y. J. Tung, R. C. Kwong, J. J. Brown, S. Garon and M. E. Thompson: Appl. Phys. Lett. 82 (2003) 2422[AIP Scitation].
  5. K. Tai, L. Yang, Y. H. Wang, J. D. Wynn and A. Y. Cho: Appl. Phys. Lett. 56 (1990) 2496[AIP Scitation].
  6. P. K. H. Ho, J. S. Kim, J. H. Burroughes, H. Becker, S. F. Y. Li, T. M. Brown, F. Cacialli and R. H. Friend: Nature 404 (2000) 481[CrossRef].
  7. A. B. Chwang, R. C. Kwong and J. J. Brown: Appl. Phys. Lett. 80 (2002) 725[AIP Scitation].
  8. D. Ma, C. S. Lee, S. T. Lee and L. S. Hung: Appl. Phys. Lett. 80 (2002) 3641[AIP Scitation].
  9. G. T. Lei, L. D. Wang, L. Duan, J. H. Wang and Y. Qiu: Synth. Met. 144 (2004) 249[CrossRef].
  10. C. Adachi, M. A. Baldo, S. R. Forrest and M. E. Thompson: Appl. Phys. Lett. 77 (2000) 904[AIP Scitation].
  11. Y. Qiu, Y. D. Gao, P. Wei and L. D. Wang: Appl. Phys. Lett. 80 (2002) 2628[AIP Scitation].
  12. E. Tutis, D. Berner and L. Zuppiroli: J. Appl. Phys. 93 (2003) 4594[AIP Scitation].
  13. D. F. O Brien, M. A. Baldo, M. E. Thompson and S. R. Forrest: Appl. Phys. Lett. 74 (1999) 442[AIP Scitation].
  14. V. I. Adamovich, S. R. Cordero, P. I. Djurovich, A. Tamayo, M. E. Thompson, B. W. D'Andrade and S. R. Forrest: Organic Electronics 4 (2003) 77.
  15. R. J. Holmes, B. W. D'Andrade, S. R. Forrest, X. Ren, J. Li and M. E. Thompson: Appl. Phys. Lett. 83 (2003) 3818[AIP Scitation].
  16. A. Gasso, D. Ma, I. A. Hummelgen and M. G. E. da Luz: J. Appl. Phys. 95 (2004) 2056[AIP Scitation].
  17. H. Riel, S. Karg, T. Beierlein and W. Rieß: J. Appl. Phys. 94 (2003) 5290[AIP Scitation].

|TOP|  |Previous Article| |Next Article|  |Table of Contents| |JJAP Home|
Copyright © 2013 The Japan Society of Applied Physics
Contact Information