The Characteristic Analysis of White Organic Light Emitting Diodes with Two-wavelength Materials at Emitting Layer

발광층에 2파장 재료를 갖는 백색 유기발광소자의 특성분석

  • Published : 2008.03.25

Abstract

In this paper, the white organic LED with two-wavelength was fabricated using the NPB of blue emitting material and a series of orange color fluorescent dye(Rubrene) by vacuum evaporation processes. The structure of white OLED was ITO/NPB$(200{\AA})$NPB:Rubrene$(300{\AA})$/BCP$(100{\AA})/Alq_3(100{\AA})/Al(1000{\AA})$ and the doping concentration of Rubrene was 0.75 wt%. We obtained the white OLED with CIE color coordinates were x=0.3327 and y=0.3387, and the maximum EL wavelength of the fabricated white organic light-emitting device was 560 nm at applied voltage of 11 V, which was similar to NTSC white color with CIE color coordinates of x=0.3333 and y=0.3333. The turn-on voltage is 1 V, the light-emitting him-on voltage is 4 V. We were able to obtain an excellent maximum external quantum efficiency of 0.457 % at an applied voltage of 18.5 V and current density of $369mA/cm^2$.

본 연구에서는 발광층에 2 파장 재료를 갖는 백색 유기발광소자를 진공증착법을 사용하여 청색 발광재료인 NPB와 황색 발광재료인 Rubrene을 사용하여 제작하였다. 제작된 소자는 ITO/NPB$(200{\AA})$NPB:Rubrene$(300{\AA})$/BCP$(100{\AA})/Alq_3(100{\AA})/Al(1000{\AA})$ 구조로 하였고 Rubrene의 도핑농도는 0.75 wt%이었다. 소자의 색좌표값은 인가전압 11 V에서 x = 0.3327, y = 0.3387 로 NTSC 색좌표 순수한 백색영역(x = 0.3333, y = 0.3333)에 근접한 순수한 백색에 가까운 값을 얻었고, 이 때 최대발광파장은 560 nm이었다. 소자의 동작 개시전압은 1 V이하이고 발광 개시전압은 4 V이다. 최대 외부양자효율은 인가전압 18.5 V, 전류밑도 $369mA/cm^2$ 일 때 0.457 %를 얻었다.

Keywords

References

  1. 김환규, 정태형, '유기 전계발광 재료 및 소자의 기술현황 및 전망', 화학세계, 37권, 8호, pp. 33-47, 1997
  2. M. Morimoto, and H. Watanabe, 'Flat Panel Displays', NEC Technical Journal, Vol. 49, No. 1, pp. 82-86, 1996
  3. C.Charton, N. Schiller, M. Fahland, A. Hollander, A. Wedel, and K. Noller, 'Development of high barrier films on flexible polymer substrates', Thin Solid Films, In Press, Corrected Proof, 2005
  4. M.Pope, H.P.Kallmann and P.Magnate, J. Chem. Phys., No. 38, p.2042, 1963
  5. P. S. Vincett, W.A. Barlow, R.A. Hanu, and G.G. Robats, Thin Solid Films, No.94, p.171, 1982
  6. C. W. Tang and S.A. VanSlyke, 'Organic electroluminescent diodes', Appl. Phys. Lett., Vol. 51, No. 12, pp. 913-915, 1987 https://doi.org/10.1063/1.98799
  7. C. W. Tang, S.A. VanSlyke, and C.H. Chen, 'Electroluminescece of doped organic thin films', J.Appl. Phys., Vol.65, No.9, pp. 3610-3616, 1989 https://doi.org/10.1063/1.343409
  8. Zhang Zhi-lin, Jiang Xue-yin, and Xu Shao-hong, 'Energy tranfer and white emitting organic thin film electroluminescence', Thin Solid Films, Vol. 363, p. 61. 2000 https://doi.org/10.1016/S0040-6090(99)00984-0
  9. Zhang Zhi-lin, Jiang Xue-yin, Zhu Wen-quing Zhang Bu-xin, and Xu Shao-hong, 'A white organic light emitting diode with improved stability', J. Phys. D: Appl. Phys., Vol. 34, p. 3083, 2001 https://doi.org/10.1088/0022-3727/34/20/313
  10. C. W. Ko and Y. T. Tao, 'Bright white organic light-emitting diode', Appl. Phys. Lett., Vol. 79, No. 25, pp.4234-4236, 2001 https://doi.org/10.1063/1.1425454
  11. Jea-Young Cho, Sung-Jin Choi, Seok-Bum Yoon, Hwan-Sool Oh, A Study on the Luminous Properties of the White-light-emitting Organic LED with Two-wavelength using DPVBi/ Alq3:Rubrene Structure, Journal of the KIEEME, Vol. 16, No. 7, pp.616-621, July 1. 2003 https://doi.org/10.4313/JKEM.2003.16.7.616
  12. S. Tokito, T. Tsuzuki, F. Sato, and T. Iijuma, 'High-efficiency blue and white phosphorescent organic light-emitting devices', Current Applied Physics, Vol. 5, pp. 331-336, 2005 https://doi.org/10.1016/j.cap.2003.11.094