Abstract

A high-contrast organic light-emitting diode (OLED) structure is presented. Because of poor contrast of conventional OLED resulting from high reflective metal cathode, the hybrid cathode structure was developed for low reflectivity. It consists the semitransparent cathode layers, passivation layers and a thick light-absorbing film. By optical reflectivity measurement and OLED electrical characterization tests for both OLED with the hybrid cathode and conventional OLED, it was found that the spectrum reflectance of OLED with hybrid cathode is among 8%–12%, about eight times lower than the conventional one when the two types of devices have similar turn-on voltages and current-voltage characteristics. The hybrid cathode for the high-contrast OLED is easily fabricated and its optical reflectance is slightly dependent on wavelength.

© 2005 Optical Society of America

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  1. C. W. Tang and S.A. Van Slyke, “Organic electroluminescent diodes,” Appl. Phys. Lett.,  51, 913–915 (1987)
    [CrossRef]
  2. 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,” Nature1990,  347, 539.
    [CrossRef]
  3. J. Pucilowski, R. Schuman, and J. Velasquez, “contrast enhancement of light emitting diodes,” Appl. Opt. 13, 2248–2252 (1974)
    [CrossRef] [PubMed]
  4. P.G. Hofstra and A.N. Krasnov, US Patent IPN No. WO 01/08240
  5. A.N. Krasnov, “High-contrast organic light-emitting diodes on flexible subtrate,” Appl. Phys. Lett. 80, 3853 (2002)
    [CrossRef]
  6. L.S. Hung and J. Madathil, “Reduction of Ambient light reflection in organic light-emitting diodes,” Adv. Mater. 23, 1787–1790 (2001)
    [CrossRef]
  7. Z.Y. Xie and L.S. Hung, “High-contrast organic light-emitting diodes,” Appl. Phys. Lett. 84, 1207–1209 (2004)
    [CrossRef]
  8. X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
    [CrossRef]
  9. F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
    [CrossRef]
  10. J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
    [CrossRef]
  11. G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
    [CrossRef]
  12. L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
    [CrossRef]
  13. S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
    [CrossRef]
  14. Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
    [CrossRef]

2004 (4)

Z.Y. Xie and L.S. Hung, “High-contrast organic light-emitting diodes,” Appl. Phys. Lett. 84, 1207–1209 (2004)
[CrossRef]

X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
[CrossRef]

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

2003 (1)

Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
[CrossRef]

2002 (2)

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

A.N. Krasnov, “High-contrast organic light-emitting diodes on flexible subtrate,” Appl. Phys. Lett. 80, 3853 (2002)
[CrossRef]

2001 (2)

L.S. Hung and J. Madathil, “Reduction of Ambient light reflection in organic light-emitting diodes,” Adv. Mater. 23, 1787–1790 (2001)
[CrossRef]

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

1996 (1)

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

1990 (1)

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,” Nature1990,  347, 539.
[CrossRef]

1987 (1)

C. W. Tang and S.A. Van Slyke, “Organic electroluminescent diodes,” Appl. Phys. Lett.,  51, 913–915 (1987)
[CrossRef]

1974 (1)

Bradley, D. D. C.

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,” Nature1990,  347, 539.
[CrossRef]

Brown, A. R.

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,” Nature1990,  347, 539.
[CrossRef]

Bulovic, V.

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

Burns, P. L.

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,” Nature1990,  347, 539.
[CrossRef]

Burroughes, J. H.

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,” Nature1990,  347, 539.
[CrossRef]

Burrows, P.E.

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

Chan, M.Y.

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Chang, Y.

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

Feng, X.D.

X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
[CrossRef]

Forrest, S.R.

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

Friend, R. H.

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,” Nature1990,  347, 539.
[CrossRef]

Fung, M.K.

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Gu, G.

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

Hofstra, P.G.

P.G. Hofstra and A.N. Krasnov, US Patent IPN No. WO 01/08240

Holmes, A. B.

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,” Nature1990,  347, 539.
[CrossRef]

Hu, P.J.

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

Hung, L.S.

Z.Y. Xie and L.S. Hung, “High-contrast organic light-emitting diodes,” Appl. Phys. Lett. 84, 1207–1209 (2004)
[CrossRef]

Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
[CrossRef]

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

L.S. Hung and J. Madathil, “Reduction of Ambient light reflection in organic light-emitting diodes,” Adv. Mater. 23, 1787–1790 (2001)
[CrossRef]

Jiang, X.

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

Khangura, RE.

X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
[CrossRef]

Krasnov, A.N.

A.N. Krasnov, “High-contrast organic light-emitting diodes on flexible subtrate,” Appl. Phys. Lett. 80, 3853 (2002)
[CrossRef]

P.G. Hofstra and A.N. Krasnov, US Patent IPN No. WO 01/08240

Lai, S.L.

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Lee, C.S.

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Lee, J.H.

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

Lee, S.T.

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Li, Y.Q.

Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
[CrossRef]

Liao, C.C.

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

Lu, Z.H.

X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
[CrossRef]

Mackey, K.

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,” Nature1990,  347, 539.
[CrossRef]

Madathil, J.

L.S. Hung and J. Madathil, “Reduction of Ambient light reflection in organic light-emitting diodes,” Adv. Mater. 23, 1787–1790 (2001)
[CrossRef]

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

Marks, R. N.

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,” Nature1990,  347, 539.
[CrossRef]

Mason, M.G.

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

Pucilowski, J.

Raychaudhuri, P.

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

Schuman, R.

Tang, C. W.

C. W. Tang and S.A. Van Slyke, “Organic electroluminescent diodes,” Appl. Phys. Lett.,  51, 913–915 (1987)
[CrossRef]

Tang, C.W.

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

Tang, J.X.

Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
[CrossRef]

Thompson, M.E.

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

Van Slyke, S.A.

C. W. Tang and S.A. Van Slyke, “Organic electroluminescent diodes,” Appl. Phys. Lett.,  51, 913–915 (1987)
[CrossRef]

Velasquez, J.

Wong, F.L.

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

Xie, Z.Y.

Z.Y. Xie and L.S. Hung, “High-contrast organic light-emitting diodes,” Appl. Phys. Lett. 84, 1207–1209 (2004)
[CrossRef]

Adv. Mater. (1)

L.S. Hung and J. Madathil, “Reduction of Ambient light reflection in organic light-emitting diodes,” Adv. Mater. 23, 1787–1790 (2001)
[CrossRef]

Appl. Opt. (1)

Appl. Phys. Lett. (6)

C. W. Tang and S.A. Van Slyke, “Organic electroluminescent diodes,” Appl. Phys. Lett.,  51, 913–915 (1987)
[CrossRef]

Z.Y. Xie and L.S. Hung, “High-contrast organic light-emitting diodes,” Appl. Phys. Lett. 84, 1207–1209 (2004)
[CrossRef]

X.D. Feng, RE. Khangura, and Z.H. Lu, “Metal-organic-metal cathode for high-contrast organic light-emitting diodes,” Appl. Phys. Lett. 85, 497–499 (2004,)
[CrossRef]

G. Gu, V. Bulovic, P.E. Burrows, S.R. Forrest, and M.E. Thompson, “Transparent organic light emitting diodes,” Appl. Phys. Lett. 68, 2606–2608(1996)
[CrossRef]

L.S. Hung, C.W. Tang, M.G. Mason, P. Raychaudhuri, and J. Madathil “Application of an ultrathin LiF/Al bilayer in organic surface-emitting diodes,” Appl. Phys. Lett. 78, 544–546(2001)
[CrossRef]

A.N. Krasnov, “High-contrast organic light-emitting diodes on flexible subtrate,” Appl. Phys. Lett. 80, 3853 (2002)
[CrossRef]

Chem. Phys. Lett. (2)

S.L. Lai, M.Y. Chan, M.K. Fung, C.S. Lee, L.S. Hung, and S.T. Lee, “Applications of Ytterbium in organic light-emitting devices as high performance and transparent electrodes,” Chem. Phys. Lett. 366, 128–133 (2002)
[CrossRef]

Y.Q. Li, J.X. Tang, and L.S. Hung, “Interfacial chemistry of Sm with Alq3 and its implication to organic light-emitting devices,” Chem. Phys. Lett. 376, 90–95 (2003)
[CrossRef]

Nature (1)

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,” Nature1990,  347, 539.
[CrossRef]

Synthetic Metals (1)

J.H. Lee, C.C. Liao, P.J. Hu, and Y. Chang, “High contrast ratio organic light-emitting devices based on CuPc as electron transport material,” Synthetic Metals,  144, 279–283, (2004)
[CrossRef]

Thin Solid Film (1)

F.L. Wong, M.K. Fung, X. Jiang, C.S. Lee, and S.T. Lee, “Non-reflective black cathode in organic light-emitting diode,” Thin Solid Film,  446, 143–146, (2004)
[CrossRef]

Other (1)

P.G. Hofstra and A.N. Krasnov, US Patent IPN No. WO 01/08240

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Figures (5)

Fig. 1.
Fig. 1.

Schematic diagram of the OLED with conventional metallic cathode (Device 1) and hybrid cathode (Device 2)

Fig. 2.
Fig. 2.

I-V and L-V characteristics of Device 1 and Device 2

Fig. 3.
Fig. 3.

The measured spectrum reflectance of Device 1 and Device 2

Fig. 4.
Fig. 4.

Contrast-ratio of Device 1 and Device 2

Fig. 5.
Fig. 5.

Photographs of Device 1 and Device2 at 3, 4 and 5 operational voltages.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

R L = λ 1 λ 2 V ( λ ) S ( λ ) R ( λ ) d λ λ 1 λ 2 V ( λ ) S ( λ ) d λ
CR = L max + L ambient L min + L ambient

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