Abstract

We have developed a high efficiency and deep blue organic light-emitting diodes (OLEDs) incorporating a 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (AlmND<sub>3</sub>) as the emitter and electron transporting layer (ETL). The blue AlmND<sub>3</sub> emitter, with an electron withdrawing group added to the well-known green fluorophore tris(8-hydroxyquinolinato)aluminum (Alq<sub>3</sub>), exhibited ambipolar charge transport as well as high electron and hole mobilities on the order of 10<sup>-5</sup> cm<sup>2</sup>/V·s, as deduced time-of-flight measurements. The magnitude of the electron mobility was 10 times greater than that of the widely used Alq<sub>3</sub> ETL, resulting in efficient charge balance in the AlmND<sub>3</sub> device. Based on a simple configuration of double heterojunction device, a blue device with the maximum external quantum efficiency of 1.58% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.08) was achieved at a brightness of 200 cd/m<sup>2</sup>. This study has revealed the fundamental nature of charge transport in hydroxynaphthyridine metal chelate and shed a new light on the design of high performance blue OLEDs.

© 2011 IEEE

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  4. C.-C. Lee, M.-Y. Chang, P.-T. Huang, Y. C. Chen, Y. Chang, S.-W. Liu, "Electrical and optical simulation of organic light-emitting devices with fluorescent dopant in the emitting layer," J. Appl. Phys. 101, 114501-114511 (2007).
  5. L. S. Hung, C. H. Chen, "Recent progress of molecular organic electroluminescent materials and devices," Mater. Sci. Eng. R 39, 143-222 (2002).
  6. S.-W. Liu, J.-H. Lee, C.-C. Lee, C.-T. Chen, J.-K. Wang, "Charge carrier mobility of mixed-layer organic light-emitting diodes," Appl. Phys. Lett. 91, 142106 (2007).
  7. H. Aziz, Z. D. Popovic, "Study of organic light emitting devices with a 5,6,11,12-tetraphenylnaphthacene (rubrene)-doped hole transport layer," Appl. Phys. Lett. 80, 2180-2182 (2002).
  8. S.-H. Liao, J.-R. Shiu, S.-W. Liu, S.-J. Yeh, Y.-H. Chen, C.-T. Chen, T. J. Chow, C.-I. Wu, "Hydroxynaphthyridine-derived group iii metal chelates: Wide band gap and deep blue analogues of green Alq3 (Tris(8-hydroxyquinolate)aluminum) and their versatile applications for organic light-emitting diodes," J. Amer. Chem. Soc. 131, 763-777 (2008).
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  16. C.-H. Hsiao, S.-W. Liu, C.-T. Chen, J.-H. Lee, "Emitting layer thickness dependence of color stability in phosphorescent organic light-emitting devices," Org. Electron. 11, 1500-1506 (2010).
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  19. H. Doi, M. Kinoshita, K. Okumoto, Y. Shirota, "A novel class of emitting amorphous molecular materials with bipolar character for electroluminescence," Chem. Mater. 15, 1080-1089 (2003).
  20. C.-C. Wu, T.-L. Liu, W.-Y. Hung, Y.-T. Lin, K.-T. Wong, R.-T. Chen, Y.-M. Chen, Y.-Y. Chien, "Unusual nondispersive ambipolar carrier transport and high electron mobility in amorphous Ter(9,9-diarylfluorene)s," J. Amer. Chem. Soc. 125, 3710-3711 (2003).

2010 (1)

C.-H. Hsiao, S.-W. Liu, C.-T. Chen, J.-H. Lee, "Emitting layer thickness dependence of color stability in phosphorescent organic light-emitting devices," Org. Electron. 11, 1500-1506 (2010).

2008 (2)

N. Matsumoto, M. Nishiyama, C. Adachi, "Exciplex formations between Tris(8-hydoxyquinolate)aluminum and hole transport materials and their photoluminescence and electroluminescence characteristics," J. Phys. Chem. C 112, 7735-7741 (2008).

S.-H. Liao, J.-R. Shiu, S.-W. Liu, S.-J. Yeh, Y.-H. Chen, C.-T. Chen, T. J. Chow, C.-I. Wu, "Hydroxynaphthyridine-derived group iii metal chelates: Wide band gap and deep blue analogues of green Alq3 (Tris(8-hydroxyquinolate)aluminum) and their versatile applications for organic light-emitting diodes," J. Amer. Chem. Soc. 131, 763-777 (2008).

2007 (4)

M.-F. Wu, S.-J. Yeh, C.-T. Chen, H. Murayama, T. Tsuboi, W.-S. Li, I. Chao, S.-W. Liu, J.-K. Wang, "The quest for high-performance host materials for electrophosphorescent blue dopants," Adv. Funct. Mater. 17, 1887-1895 (2007).

Y. Shirota, H. Kageyama, "Charge carrier transporting molecular materials and their applications in devices," Chem. Rev. 107, 953-1010 (2007).

C.-C. Lee, M.-Y. Chang, P.-T. Huang, Y. C. Chen, Y. Chang, S.-W. Liu, "Electrical and optical simulation of organic light-emitting devices with fluorescent dopant in the emitting layer," J. Appl. Phys. 101, 114501-114511 (2007).

S.-W. Liu, J.-H. Lee, C.-C. Lee, C.-T. Chen, J.-K. Wang, "Charge carrier mobility of mixed-layer organic light-emitting diodes," Appl. Phys. Lett. 91, 142106 (2007).

2005 (2)

H. H. Fong, S. K. So, "Effects of nitrogen, oxygen, and moisture on the electron transport in tris(8-hydroxyquinoline) aluminum," J. Appl. Phys. 98, 023711-023714 (2005).

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, Y. Chang, "Mixed host organic light-emitting devices with low driving voltage and long lifetime," Appl. Phys. Lett. 86, 103506-103503 (2005).

2003 (2)

H. Doi, M. Kinoshita, K. Okumoto, Y. Shirota, "A novel class of emitting amorphous molecular materials with bipolar character for electroluminescence," Chem. Mater. 15, 1080-1089 (2003).

C.-C. Wu, T.-L. Liu, W.-Y. Hung, Y.-T. Lin, K.-T. Wong, R.-T. Chen, Y.-M. Chen, Y.-Y. Chien, "Unusual nondispersive ambipolar carrier transport and high electron mobility in amorphous Ter(9,9-diarylfluorene)s," J. Amer. Chem. Soc. 125, 3710-3711 (2003).

2002 (2)

H. Aziz, Z. D. Popovic, "Study of organic light emitting devices with a 5,6,11,12-tetraphenylnaphthacene (rubrene)-doped hole transport layer," Appl. Phys. Lett. 80, 2180-2182 (2002).

L. S. Hung, C. H. Chen, "Recent progress of molecular organic electroluminescent materials and devices," Mater. Sci. Eng. R 39, 143-222 (2002).

2001 (1)

G. G. Malliaras, Y. Shen, D. H. Dunlap, H. Murata, Z. H. Kafafi, "Nondispersive electron transport in Alq3," Appl. Phys. Lett. 79, 2582-2584 (2001).

2000 (2)

S. Naka, H. Okada, H. Onnagawa, T. Tsutsui, "High electron mobility in bathophenanthroline," Appl. Phys. Lett. 76, 197-199 (2000).

Y. Shirota, M. Kinoshita, T. Noda, K. Okumoto, T. Ohara, "A novel class of emitting amorphous molecular materials as bipolar radical formants: 2-{4-[Bis(4-methylphenyl)amino]phenyl}-5-(dimesitylboryl)thiophene and 2-{4-[Bis(9,9-dimethylfluorenyl)amino]phenyl}-5-(dimesitylboryl)thiophene," J. Amer. Chem. Soc. 122, 11021-11022 (2000).

1999 (1)

V.-E. Choong, S. Shi, J. Curless, C.-L. Shieh, H. C. Lee, F. So, J. Shen, J. Yang, "Organic light-emitting diodes with a bipolar transport layer," Appl. Phys. Lett. 75, 172-174 (1999).

1995 (1)

R. G. Kepler, P. M. Beeson, S. J. Jacobs, R. A. Anderson, M. B. Sinclair, V. S. Valencia, P. A. Cahill, "Electron and hole mobility in tris(8-hydroxyquinolinolato-N1,O8) aluminum," Appl. Phys. Lett. 66, 3618-3620 (1995).

1987 (1)

C. W. Tang, S. A. Vanslyke, "Organic electroluminescent diodes," Appl. Phys. Lett. 51, 913-915 (1987).

Adv. Funct. Mater. (1)

M.-F. Wu, S.-J. Yeh, C.-T. Chen, H. Murayama, T. Tsuboi, W.-S. Li, I. Chao, S.-W. Liu, J.-K. Wang, "The quest for high-performance host materials for electrophosphorescent blue dopants," Adv. Funct. Mater. 17, 1887-1895 (2007).

Appl. Phys. Lett. (8)

S.-W. Liu, J.-H. Lee, C.-C. Lee, C.-T. Chen, J.-K. Wang, "Charge carrier mobility of mixed-layer organic light-emitting diodes," Appl. Phys. Lett. 91, 142106 (2007).

H. Aziz, Z. D. Popovic, "Study of organic light emitting devices with a 5,6,11,12-tetraphenylnaphthacene (rubrene)-doped hole transport layer," Appl. Phys. Lett. 80, 2180-2182 (2002).

C. W. Tang, S. A. Vanslyke, "Organic electroluminescent diodes," Appl. Phys. Lett. 51, 913-915 (1987).

V.-E. Choong, S. Shi, J. Curless, C.-L. Shieh, H. C. Lee, F. So, J. Shen, J. Yang, "Organic light-emitting diodes with a bipolar transport layer," Appl. Phys. Lett. 75, 172-174 (1999).

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, Y. Chang, "Mixed host organic light-emitting devices with low driving voltage and long lifetime," Appl. Phys. Lett. 86, 103506-103503 (2005).

G. G. Malliaras, Y. Shen, D. H. Dunlap, H. Murata, Z. H. Kafafi, "Nondispersive electron transport in Alq3," Appl. Phys. Lett. 79, 2582-2584 (2001).

R. G. Kepler, P. M. Beeson, S. J. Jacobs, R. A. Anderson, M. B. Sinclair, V. S. Valencia, P. A. Cahill, "Electron and hole mobility in tris(8-hydroxyquinolinolato-N1,O8) aluminum," Appl. Phys. Lett. 66, 3618-3620 (1995).

S. Naka, H. Okada, H. Onnagawa, T. Tsutsui, "High electron mobility in bathophenanthroline," Appl. Phys. Lett. 76, 197-199 (2000).

Chem. Mater. (1)

H. Doi, M. Kinoshita, K. Okumoto, Y. Shirota, "A novel class of emitting amorphous molecular materials with bipolar character for electroluminescence," Chem. Mater. 15, 1080-1089 (2003).

Chem. Rev. (1)

Y. Shirota, H. Kageyama, "Charge carrier transporting molecular materials and their applications in devices," Chem. Rev. 107, 953-1010 (2007).

J. Amer. Chem. Soc. (3)

S.-H. Liao, J.-R. Shiu, S.-W. Liu, S.-J. Yeh, Y.-H. Chen, C.-T. Chen, T. J. Chow, C.-I. Wu, "Hydroxynaphthyridine-derived group iii metal chelates: Wide band gap and deep blue analogues of green Alq3 (Tris(8-hydroxyquinolate)aluminum) and their versatile applications for organic light-emitting diodes," J. Amer. Chem. Soc. 131, 763-777 (2008).

Y. Shirota, M. Kinoshita, T. Noda, K. Okumoto, T. Ohara, "A novel class of emitting amorphous molecular materials as bipolar radical formants: 2-{4-[Bis(4-methylphenyl)amino]phenyl}-5-(dimesitylboryl)thiophene and 2-{4-[Bis(9,9-dimethylfluorenyl)amino]phenyl}-5-(dimesitylboryl)thiophene," J. Amer. Chem. Soc. 122, 11021-11022 (2000).

C.-C. Wu, T.-L. Liu, W.-Y. Hung, Y.-T. Lin, K.-T. Wong, R.-T. Chen, Y.-M. Chen, Y.-Y. Chien, "Unusual nondispersive ambipolar carrier transport and high electron mobility in amorphous Ter(9,9-diarylfluorene)s," J. Amer. Chem. Soc. 125, 3710-3711 (2003).

J. Appl. Phys. (2)

H. H. Fong, S. K. So, "Effects of nitrogen, oxygen, and moisture on the electron transport in tris(8-hydroxyquinoline) aluminum," J. Appl. Phys. 98, 023711-023714 (2005).

C.-C. Lee, M.-Y. Chang, P.-T. Huang, Y. C. Chen, Y. Chang, S.-W. Liu, "Electrical and optical simulation of organic light-emitting devices with fluorescent dopant in the emitting layer," J. Appl. Phys. 101, 114501-114511 (2007).

J. Phys. Chem. C (1)

N. Matsumoto, M. Nishiyama, C. Adachi, "Exciplex formations between Tris(8-hydoxyquinolate)aluminum and hole transport materials and their photoluminescence and electroluminescence characteristics," J. Phys. Chem. C 112, 7735-7741 (2008).

Mater. Sci. Eng. R (1)

L. S. Hung, C. H. Chen, "Recent progress of molecular organic electroluminescent materials and devices," Mater. Sci. Eng. R 39, 143-222 (2002).

Org. Electron. (1)

C.-H. Hsiao, S.-W. Liu, C.-T. Chen, J.-H. Lee, "Emitting layer thickness dependence of color stability in phosphorescent organic light-emitting devices," Org. Electron. 11, 1500-1506 (2010).

Other (1)

P. M. Borsenberger, D. S. Weiss, Organic Photoreceptors for Imaging Systems (Marcel Dekker, 1993).

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