Abstract

Long working lifetime and high efficient phosphorescent organic light-emitting diode (PHOLED) in which mixed host composed of wide-band-gap based 4, 7-diphenyl-1, 10-phenanthroline (Bphen) and (4,4’-bis(carbazol-9-yl)-biphenyl) (CBP) was demonstrated. The PHOLED with structure of ITO / MoO3 / CBP:MoO3 (15v%, 30 nm) / CBP(10 nm) / ([50v%:50v% CBP:Bphen]: 6v% Ir(ppy)3)(30 nm) / Bphen (40 nm) / LiF (1 nm) / Al offers a peak power efficiency of 41.6 lm/W (a peak current efficiency of 39.8 cd/A)) at a low driving voltage of 3 V which increases by 55% and 27% compared to that of corresponding single-host (SH) and double emitting layer (DML) devices, respectively. Especially very long work lifetime (3530 hs) at an initial luminance of 500 cd/m2 of the mixed hosted device is exhibited, rising by about 4.1 and 2.46 times relative to that of corresponding SH and DML devices. High efficiency and longer working lifetime was attributed to the absence of heterojunction and balanced charge carrier transport characteristics in the mixed host based OLED structure. The more detail mechanism was also presented.

© 2013 OSA

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  1. M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
    [CrossRef]
  2. S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
    [CrossRef]
  3. X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
    [CrossRef]
  4. Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
    [CrossRef]
  5. Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
    [CrossRef]
  6. K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
    [CrossRef]
  7. D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
    [CrossRef]
  8. D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
    [CrossRef]
  9. D. Y. Kondakov and R. H. Young, “Variable sensitivity of organic light-emitting diodes to operation- induced chemical degradation: Nature of the antagonistic relationship between lifetime and efficiency,” J. Appl. Phys.108(7), 074513 (2010).
    [CrossRef]
  10. J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
    [CrossRef] [PubMed]
  11. J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
    [CrossRef]
  12. B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
    [CrossRef]
  13. C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
    [CrossRef]
  14. N. C. Erickson and R. J. Holmes, “Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer,” Appl. Phys. Lett.97(8), 083308 (2010).
    [CrossRef]
  15. S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
    [CrossRef]
  16. M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
    [CrossRef]
  17. J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
    [CrossRef]
  18. S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
    [CrossRef]
  19. S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
    [CrossRef]
  20. J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
    [CrossRef]
  21. M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
    [CrossRef]
  22. B. D. Chin, “Enhancement of efficiency and stability of phosphorescent OLEDs based on heterostructured light-emitting layers,” J. Phys. D Appl. Phys.44(11), 115103 (2011).
    [CrossRef]
  23. L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
    [CrossRef]
  24. S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
    [CrossRef]
  25. J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
    [CrossRef]
  26. R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
    [CrossRef]

2013 (1)

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

2012 (2)

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
[CrossRef]

2011 (2)

B. D. Chin, “Enhancement of efficiency and stability of phosphorescent OLEDs based on heterostructured light-emitting layers,” J. Phys. D Appl. Phys.44(11), 115103 (2011).
[CrossRef]

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

2010 (5)

N. C. Erickson and R. J. Holmes, “Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer,” Appl. Phys. Lett.97(8), 083308 (2010).
[CrossRef]

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

D. Y. Kondakov and R. H. Young, “Variable sensitivity of organic light-emitting diodes to operation- induced chemical degradation: Nature of the antagonistic relationship between lifetime and efficiency,” J. Appl. Phys.108(7), 074513 (2010).
[CrossRef]

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

2009 (2)

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

2008 (2)

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

2007 (3)

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
[CrossRef]

S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
[CrossRef]

2006 (1)

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

2005 (2)

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

2003 (1)

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

2002 (3)

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
[CrossRef]

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

2000 (1)

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

1998 (1)

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Bai, C. L.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Baldo, M. A.

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Blochwitz-Nimoth, J.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Bold, M.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Brown, C. T.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Brown, J. J.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
[CrossRef]

Chang, G.-K.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

Chang, H. J.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

Chang, Y.

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

Chen, C.-H.

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

Chen, Y.-H.

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

Chin, B. D.

B. D. Chin, “Enhancement of efficiency and stability of phosphorescent OLEDs based on heterostructured light-emitting layers,” J. Phys. D Appl. Phys.44(11), 115103 (2011).
[CrossRef]

Chou, Y.-C.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Chu, B.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Chu, H. Y.

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

Chu, M.-T.

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

Chwang, B.

B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
[CrossRef]

Deaton, J. C.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Demir, H. V.

S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
[CrossRef]

Drechsel, J.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Duan, L.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Erickson, N. C.

N. C. Erickson and R. J. Holmes, “Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer,” Appl. Phys. Lett.97(8), 083308 (2010).
[CrossRef]

Erk, P.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Forrest, S. R.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Giesen, D. J.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Gong, J.-R.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Gong, M. S.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

Hack, M.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Han, L. L.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Hao, Y. Y.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Hartmann, H.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Holmes, R. J.

N. C. Erickson and R. J. Holmes, “Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer,” Appl. Phys. Lett.97(8), 083308 (2010).
[CrossRef]

Hsiao, C.-C.

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

Hsiao, C.-H.

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

Huang, C.-A.

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

Huang, X.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Jang, J.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
[CrossRef]

Jeon, S. O.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Jeong, W.-I.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Jou, J.-H.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Kang, J.-W.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Kang, S.-K.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Kim, J.-J.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Kim, S. H.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
[CrossRef]

Klubek, K. P.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Kondakov, D. Y.

D. Y. Kondakov and R. H. Young, “Variable sensitivity of organic light-emitting diodes to operation- induced chemical degradation: Nature of the antagonistic relationship between lifetime and efficiency,” J. Appl. Phys.108(7), 074513 (2010).
[CrossRef]

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

Kondakova, M. E.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Kwong, R. C.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
[CrossRef]

Lee, J.

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

Lee, J. Y.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
[CrossRef]

Lee, J.-H.

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

Lee, J.-I.

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

Lee, M.-T.

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

Lee, S. T.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Lee, S.-H.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Lee, T.-W.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Lei, S.-B.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Lenhard, J. R.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Leo, K.

S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
[CrossRef]

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Li, T. L.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Li, W. L.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Li, Y. F.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Lin, C.-H.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Lin, T.-C.

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

Liu, H. H.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Liu, S. W.

S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
[CrossRef]

Liu, S.-W.

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

Maennig, B.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Michalski, L.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Min, S.-Y.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Naka, S.

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

Ngo, T.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Noh, T.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Nugent, M. R.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

O’Brien, D. F.

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Okada, H.

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

Onnagawa, H.

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

Park, H.-D.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Park, Y.-S.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Pawlik, T. D.

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

Pfeiffer, M.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Qin, D. S.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Qiu, Y.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Rajan, K.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Reineke, S.

S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
[CrossRef]

Ryu, S.

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

Sandifer, J. R.

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

Shen, S.-M.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Shoustikov, A.

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Sibley, S.

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Su, Z. S.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Sun, X. W.

S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
[CrossRef]

Tang, C. W.

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

Thompson, M. E.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Tseng, M.-R.

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

Tsutsui, T.

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

Tung, Y.-J.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Walzer, K.

S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
[CrossRef]

Wan, L.-J.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Wang, H.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Wang, H.-C.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Wang, L.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Wang, Z. G.

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Weaver, M. S.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Werner, A.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Wu, C.-I.

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

Wu, K.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Wu, M.-H.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Wu, P.-H.

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

Xu, B. S.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Yan, Z. F.

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

Yang, D. F.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Yang, H.-J.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

Yang, Q.

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Yoo, K.-M.

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

Yook, K. S.

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

You, Y.

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Young, R. H.

D. Y. Kondakov and R. H. Young, “Variable sensitivity of organic light-emitting diodes to operation- induced chemical degradation: Nature of the antagonistic relationship between lifetime and efficiency,” J. Appl. Phys.108(7), 074513 (2010).
[CrossRef]

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

Zhang, D.

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

Zhang, D. Y.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Zhang, G.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Zhang, X. H.

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

Zhou, T. X.

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

Zhou, X.

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

Zhu, J. Z.

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

Adv. Funct. Mater. (2)

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant,” Adv. Funct. Mater.20(11), 1797–1802 (2010).
[CrossRef]

L. Duan, D. Zhang, K. Wu, X. Huang, L. Wang, and Y. Qiu, “Controlling the recombination zone of white organic light-emitting diodes with extremely long lifetimes,” Adv. Funct. Mater.21(18), 3540–3545 (2011).
[CrossRef]

AIP Advances (1)

S. W. Liu, X. W. Sun, and H. V. Demir, “Graded-host phosphorescent light-emitting diodes with high efficiency and reduced roll-off,” AIP Advances2(1), 012192 (2012).
[CrossRef]

Appl. Phys. Lett. (10)

S. Naka, H. Okada, H. Onnagawa, and T. Tsutsui, “High electron mobility in bathophenanthroline,” Appl. Phys. Lett.76(2), 197–199 (2000).
[CrossRef]

J.-W. Kang, S.-H. Lee, H.-D. Park, W.-I. Jeong, K.-M. Yoo, Y.-S. Park, and J.-J. Kim, “Low roll-off of efficiency at high current density in phosphorescent organic light emitting diodes,” Appl. Phys. Lett.90(22), 223508 (2007).
[CrossRef]

R. C. Kwong, M. R. Nugent, L. Michalski, T. Ngo, K. Rajan, Y.-J. Tung, M. S. Weaver, T. X. Zhou, M. Hack, M. E. Thompson, S. R. Forrest, and J. J. Brown, “High operational stability of electrophosphorescent devices,” Appl. Phys. Lett.81(1), 162–164 (2002).
[CrossRef]

X. Zhou, D. S. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, and H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett.81(21), 4070–4072 (2002).
[CrossRef]

J.-H. Lee, C.-I. Wu, S.-W. Liu, C.-A. Huang, and Y. Chang, “Mixed host organic light-emitting devices with low driving voltage and long lifetime,” Appl. Phys. Lett.86(10), 103506 (2005).
[CrossRef]

B. Chwang, R. C. Kwong, and J. J. Brown, “Graded mixed-layer organic light-emitting devices,” Appl. Phys. Lett.80(5), 725–727 (2002).
[CrossRef]

C.-H. Hsiao, Y.-H. Chen, T.-C. Lin, C.-C. Hsiao, and J.-H. Lee, “Recombination zone in mixed-host organic light-emitting devices,” Appl. Phys. Lett.89(16), 163511 (2006).
[CrossRef]

N. C. Erickson and R. J. Holmes, “Highly efficient, single-layer organic light-emitting devices based on a graded-composition emissive layer,” Appl. Phys. Lett.97(8), 083308 (2010).
[CrossRef]

J. Lee, J.-I. Lee, J. Y. Lee, and H. Y. Chu, “Enhanced efficiency and reduced roll-off in blue and white phosphorescent organic light-emitting diodes with a mixed host structure,” Appl. Phys. Lett.94(19), 193305 (2009).
[CrossRef]

S. H. Kim, J. Jang, and J. Y. Lee, “Relationship between host energy levels and device performances of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure,” Appl. Phys. Lett.91(8), 083511 (2007).
[CrossRef]

J. Appl. Phys. (4)

S. H. Kim, J. Jang, K. S. Yook, J. Y. Lee, M. S. Gong, S. Ryu, G.-K. Chang, and H. J. Chang, “Triplet host engineering for triplet exciton management in phosphorescent organic light-emitting diodes,” J. Appl. Phys.103(5), 054502 (2008).
[CrossRef]

D. Y. Kondakov, J. R. Sandifer, C. W. Tang, and R. H. Young, “Nonradiative recombination centers and electrical aging of organic light-emitting diodes: Direct connection between accumulation of trapped charge and luminance loss,” J. Appl. Phys.93(2), 1108–1119 (2003).
[CrossRef]

D. Y. Kondakov and R. H. Young, “Variable sensitivity of organic light-emitting diodes to operation- induced chemical degradation: Nature of the antagonistic relationship between lifetime and efficiency,” J. Appl. Phys.108(7), 074513 (2010).
[CrossRef]

M. E. Kondakova, T. D. Pawlik, R. H. Young, D. J. Giesen, D. Y. Kondakov, C. T. Brown, J. C. Deaton, J. R. Lenhard, and K. P. Klubek, “High-efficiency, low-voltage phosphorescent organic light-emitting diode devices with mixed host,” J. Appl. Phys.104(9), 094501 (2008).
[CrossRef]

J. Mater. Chem. (1)

J.-H. Jou, P.-H. Wu, C.-H. Lin, M.-H. Wu, Y.-C. Chou, H.-C. Wang, and S.-M. Shen, “Highly efficient orange-red organic light-emitting diode using double emissive layers with stepwise energy-level architecture,” J. Mater. Chem.20(39), 8464–8466 (2010).
[CrossRef]

J. Phys. Chem. B (1)

J.-R. Gong, L.-J. Wan, S.-B. Lei, C. L. Bai, X. H. Zhang, and S. T. Lee, “Direct evidence of molecular aggregation and degradation mechanism of organic light-emitting diodes under Joule heating: an STM and photoluminescence study,” J. Phys. Chem. B109(5), 1675–1682 (2005).
[CrossRef] [PubMed]

J. Phys. D Appl. Phys. (2)

D. F. Yang, L. L. Han, W. L. Li, B. Chu, Z. S. Su, D. Y. Zhang, T. L. Li, G. Zhang, and J. Z. Zhu, “A very high efficiency electrophosphorescent device doped with short triplet lifetime phosphor using multi-recombination zones,” J. Phys. D Appl. Phys.43(10), 105101 (2010).
[CrossRef]

B. D. Chin, “Enhancement of efficiency and stability of phosphorescent OLEDs based on heterostructured light-emitting layers,” J. Phys. D Appl. Phys.44(11), 115103 (2011).
[CrossRef]

Nature (1)

M. A. Baldo, D. F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, and S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature395(6698), 151–154 (1998).
[CrossRef]

Org. Electron. (1)

M.-T. Chu, M.-T. Lee, C.-H. Chen, and M.-R. Tseng, “Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter,” Org. Electron.10(6), 1158–1162 (2009).
[CrossRef]

Phys. Rev. B (1)

S. Reineke, K. Walzer, and K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B75(12), 125328 (2007).
[CrossRef]

Synth. Met. (2)

Q. Yang, Y. Y. Hao, Z. G. Wang, Y. F. Li, H. Wang, and B. S. Xu, “Double-emission-layer green phosphorescent OLED based on LiF-doped TPBi as electron transport layer for improving efficiency and operational lifetime,” Synth. Met.162(3-4), 398–401 (2012).
[CrossRef]

Y. F. Li, Y. Y. Hao, Z. F. Yan, H. H. Liu, H. Wang, and B. S. Xu, “A single-heterojunction electrophosphorescence device with high efficiency, long lifetime and suppressive roll-off,” Synth. Met.164, 12–16 (2013).
[CrossRef]

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Figures (6)

Fig. 1
Fig. 1

J-V curves of single carrier devices with changed ratio CBP:Bphen mixed host.

Fig. 2
Fig. 2

The schematic structure diagrams for new structure Device-A and references Device-B and C.

Fig. 3
Fig. 3

Normalized EL spectra of Devices-A, B and C at 100 mA/cm2. The peak emission at 512 nm and shoulder peak emission at 542 nm for Ir(ppy)3 are indicated.

Fig. 4
Fig. 4

Current density-luminance-voltage (J-L-V) characteristics of Devices-A, B and C, the maximum luminance is indicated for Device-A: 89561 cd/m2 at 7.6 V; Device-B: 68738 cd/m2 at 7.8 V; Device-C: 43520 cd/m2 at 8.2 V.

Fig. 5
Fig. 5

(a) Current efficiency and power efficiency as well as (b) EQE of Devices-A, B and C.

Fig. 6
Fig. 6

The working lifetime of Devices-A, B and C under constant current density with an initial brightness of 500 cd/m2 at room temperature.

Tables (1)

Tables Icon

Table 1 Performance and working lifetime of Devices-A, B and C.

Metrics