Journal of the Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회논문지)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Analysis of the Characteristics of a White OLED using the Newly Synthesized Blue Emitting Material nitro-DPVT by Varying the Doping Concentrations of Fluorescent Dye and the Thickness of the NPB Layer

신규 합성한 청색발광재료 nitro-DPVT를 사용한 백색 유기발광다이오드의 형광색소 도핑농도 및 NPB 층의 두께 변화에 따른 특성 분석

  • Published : 2006.04.01
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Abstract

A stacked white organic light-emitting diode (OLED) having a blue/orange emitting layer was fabricated by synthesizing nitro-DPVT, a new derivative of the blue-emitting material DPVBi on the market. The white-emission of the two-wavelength type was successfully obtained by using both nitro-DPVT for blue~emitting material, orange emission as a host material and Rubrene for orange emission as a guest material. The basic structure of the fabricated white OLED is glass/ITO/NPB$(200{\AA})$/nitro-DPVT$(100{\AA})$/nitro-DPVT:$Rubrene(100{\AA})/BCP(70{\AA})/Alq_3(150{\AA})/Al(600{\AA})$. To evaluate the. characteristics of the devices, firstly, we varied the doping concentrations of fluorescent dye Rubrene from 0.5 % to 0.8 % to 1.3 % to 1.5 % to 3.0 % by weight. A nearly pure white-emission was obtained in CIE coordinates of (0.3259, 0.3395) when the doping concentration of Rubrene was 1.3 % at an applied voltage of 18 V. Secondly, we varied the thickness of the NPB layer from $150{\AA}\;to\;200{\AA}\;to\;250{\AA}\;to\;300{\AA}$ by fixing doping with of Rubrene at 1.3 %. A nearly pure white-emission was also obtained in CIE coordinates of (0.3304, 0.3473) when the NPB layer was $250-{\AA}$ thick at an applied voltage of 16 V. The two devices started to operate at 4 V and to emit light at 4.5 V. The external quantum efficiency was above 0.4 % when almost all of the current was injected.

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References

  1. C. W. Tang and S. A. VanSlyke, 'Organic electroluminescent diodes', Appl. Phys. Lett., Vol. 51, No. 12, p. 913, 1987
  2. M. Morimoto and H. Watanabe, 'Flat panel displays', NEC Technical Journal, Vol. 49, No.1, p. 82, 1996
  3. J. Feng, F. Li, W. Gao, and S. Liu, 'White light emission from exciplex using tris-(8-hydroxyquinoline) aluminum as chromaticity-tuning layer', Appl. Phys. Lett., Vol. 78, No. 25, p. 3947, 2001 https://doi.org/10.1063/1.1379788
  4. H. Mattoussi, H. Murata, C. D. Merritt, Y. Lizumi, J. Kido, and Z. H. Kafafi, 'Photo luminescence quantum yield of pure and molecularly doped organic solid films', J. Appl. Phys., Vol. 86, No.5, p. 2642, 1999
  5. C. W. Ko and Y. T. Tao, 'Bright white organic light-emitting diode', Appl. Phys. Lett., Vol. 79, No. 25, p. 4234, 2001 https://doi.org/10.1063/1.1425454
  6. Zhang Z.-L., Jiang X.-Y., Zhu W.-Q., Zhang B.-X., and Xu S.-H., 'A white organic light emitting diode with improved stability', J. Phys. D: Appl. Phys., Vol. 34, p. 3083, 2001
  7. R. S. Deshpande, V. Bulovic, and S. R. Forrest, 'White-light-emitting organic electro-luminescent devices based on interlayer sequential energy tranfer', Appl. Phys. Lett., Vol. 75, No.7, p. 888, 1999 https://doi.org/10.1063/1.124250
  8. J. Y. Cho, S. J. Choi, S. B. Yoon, and H. S. Oh, 'A study on the luminous properties of the white-light-emitting organic LED with two-wavelength using DPVBi/$Alq_3$:Rubrene structure', J. of KIEEME(in Korean), Vol. 16, No.7, p. 616, 2003
  9. H. S. Oh, Y. Cho, S. J. Choi, M. K. Kang, and S. B. Yoon, 'A study on the optical and electrical properties of the whitelight-emitting organic LED with two-wavelength using DPVBi/Rubrene structure', J. of KlEEME(in Korean), Vol. 17, No.2, p. 217, 2004
  10. J. Y. Cho, H. S. Oh, T. G. Kim, and S. B. Yoon, 'Fabrication of a white organic light emitting diode by synthesizing a novel non-conjugated blue emitting material PPPMA-co-DTPM Copolymer', J. of KlEEME(in Korean), Vol. 18, No.7, p. 641, 2005