Abstract

Low driving voltage blue, green, yellow, red and white phosphorescent organic light-emitting diodes (OLEDs) with a common simply double emitting layer (D-EML) structure are investigated. Our OLEDs without any out-coupling schemes as well as n-doping strategies show low driving voltage, e.g. < 2.4 V for onset and < 3 V for 1000 cd/m2, and high efficiency of 32.5 lm/W (13.3%), 58.8 lm/W (14.3%), 55.1 lm/W (14.6%), 24.9 lm/W (13.7%) and 45.1 lm/W (13.5%) for blue, green, yellow, red and white OLED, respectively. This work demonstrates that the low driving voltages and high efficiencies can be simultaneously realized with a common simply D-EML structure.

© 2014 Optical Society of America

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    [CrossRef]
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    [CrossRef]
  3. S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
    [CrossRef] [PubMed]
  4. B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
    [CrossRef]
  5. M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
    [CrossRef]
  6. B. W. D'Andrade, S. R. Forrest, “White organic light-emitting devices for solid-state lighting,” Adv. Mater. 16(18), 1585–1595 (2004).
    [CrossRef]
  7. J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
    [CrossRef]
  8. R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
    [CrossRef]
  9. C. W. Seo, J. Y. Lee, “High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material,” Org. Electron. 12(9), 1459–1464 (2011).
    [CrossRef]
  10. J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
    [CrossRef]
  11. Q. Wang, D. Ma, “Management of charges and excitons for high-performance white organic light-emitting diodes,” Chem. Soc. Rev. 39(7), 2387–2398 (2010).
    [CrossRef] [PubMed]
  12. D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
    [CrossRef] [PubMed]
  13. C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
    [CrossRef] [PubMed]
  14. C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
    [CrossRef] [PubMed]
  15. C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
    [CrossRef] [PubMed]
  16. H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
    [CrossRef]
  17. J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
    [CrossRef]
  18. X. Zhou, D. Qin, M. Pfeiffer, J. Blochwitz-Nimoth, A. Werner, J. Drechsel, B. Maennig, K. Leo, M. Bold, P. Erk, H. Hartmann, “High-efficiency electrophosphorescent organic light-emitting diodes with double light-emitting layers,” Appl. Phys. Lett. 81(21), 4070 (2002).
    [CrossRef]
  19. S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
    [CrossRef] [PubMed]
  20. M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
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  21. W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
    [CrossRef]
  22. D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
    [CrossRef]
  23. G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
    [CrossRef]
  24. X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
    [CrossRef]
  25. Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
    [CrossRef]
  26. N. Giebink, S. R. Forrest, “Quantum efficiency roll-off at high brightness in fluorescent and phosphorescent organic light emitting diodes,” Phys. Rev. B 77(23), 235215 (2008).
    [CrossRef]
  27. S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
    [CrossRef]
  28. G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
    [CrossRef]
  29. G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
    [CrossRef]
  30. C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
    [CrossRef]
  31. R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
    [CrossRef] [PubMed]
  32. B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).
  33. C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
    [CrossRef] [PubMed]

2013

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

2012

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

2011

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

C. W. Seo, J. Y. Lee, “High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material,” Org. Electron. 12(9), 1459–1464 (2011).
[CrossRef]

2010

Q. Wang, D. Ma, “Management of charges and excitons for high-performance white organic light-emitting diodes,” Chem. Soc. Rev. 39(7), 2387–2398 (2010).
[CrossRef] [PubMed]

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

2009

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

2008

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

N. Giebink, S. R. Forrest, “Quantum efficiency roll-off at high brightness in fluorescent and phosphorescent organic light emitting diodes,” Phys. Rev. B 77(23), 235215 (2008).
[CrossRef]

2007

S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
[CrossRef]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

2006

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

2004

B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
[CrossRef]

B. W. D'Andrade, S. R. Forrest, “White organic light-emitting devices for solid-state lighting,” Adv. Mater. 16(18), 1585–1595 (2004).
[CrossRef]

2002

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

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

1998

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Adamovich, V.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Araoka, F.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Baldo, M. A.

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Blochwitz-Nimoth, J.

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

Bold, M.

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

Brown, J. J.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Chan, M.-Y.

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

Chao, C. C.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Che, C.

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

Chen, C. H.

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Chen, J.

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

Chen, P.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Chu, H. Y.

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

D’Andrade, B. W.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

D'Andrade, B. W.

B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
[CrossRef]

B. W. D'Andrade, S. R. Forrest, “White organic light-emitting devices for solid-state lighting,” Adv. Mater. 16(18), 1585–1595 (2004).
[CrossRef]

Deng, Z.

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

Drechsel, J.

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

Duan, L.

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Erk, P.

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

Esler, J.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Fehse, K.

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

Forrest, S. R.

N. Giebink, S. R. Forrest, “Quantum efficiency roll-off at high brightness in fluorescent and phosphorescent organic light emitting diodes,” Phys. Rev. B 77(23), 235215 (2008).
[CrossRef]

B. W. D'Andrade, S. R. Forrest, “White organic light-emitting devices for solid-state lighting,” Adv. Mater. 16(18), 1585–1595 (2004).
[CrossRef]

B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
[CrossRef]

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Fukagawa, H.

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

Giebink, N.

N. Giebink, S. R. Forrest, “Quantum efficiency roll-off at high brightness in fluorescent and phosphorescent organic light emitting diodes,” Phys. Rev. B 77(23), 235215 (2008).
[CrossRef]

Han, C.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Hartmann, H.

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

Ho, C.-L.

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Holmes, R. J.

B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
[CrossRef]

Hsiao, C. H.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Hu, D.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Huang, C. L.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Huang, W.

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Ishikawa, K.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Jeong, S. M.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Kido, J.

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

Koo, W. H.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Kwong, R.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Lee, J.

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

Lee, J. H.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Lee, J. I.

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

Lee, J. Y.

C. W. Seo, J. Y. Lee, “High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material,” Org. Electron. 12(9), 1459–1464 (2011).
[CrossRef]

Lee, S. J.

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

Leo, K.

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
[CrossRef]

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

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

Leung, M. K.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Li, J.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

Li, J.-Y.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Li, X.

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

Li, Y.

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Lin, C.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Lin, M.-F.

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Lindner, F.

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

Liu, D.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Liu, G.-Y.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Liu, H.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Liu, S.

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Lu, P.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Luo, Y.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Lüssem, B.

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

Lv, Y.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Ma, D.

Q. Wang, D. Ma, “Management of charges and excitons for high-performance white organic light-emitting diodes,” Chem. Soc. Rev. 39(7), 2387–2398 (2010).
[CrossRef] [PubMed]

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

Ma, Y.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

Maennig, B.

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

Meerheim, R.

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

Nakayama, K. I.

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

Nishimura, S.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

O'Brien, D. F.

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Padmaperuma, A. B.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Pfeiffer, M.

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

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

Polikarpov, E.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Pu, Y. J.

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

Qiao, X.

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

Qin, D.

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

Qiu, Y.

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Quan, B.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Reineke, S.

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
[CrossRef]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

Ren, H.-C.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Sapochak, L. S.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Sasabe, H.

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

Schwartz, G.

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

Seidler, N.

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

Seo, C. W.

C. W. Seo, J. Y. Lee, “High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material,” Org. Electron. 12(9), 1459–1464 (2011).
[CrossRef]

Shen, F.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Shen, J.

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

Shoustikov, A.

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Sibley, S.

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Song, K. I.

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

Su, S. J.

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

Swensen, J. S.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Takezoe, H.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Tam, A. Y.-Y.

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

Thompson, M. E.

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Thomschke, M.

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

Tokito, S.

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

Toyooka, T.

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Tsang, D. P.-K.

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

Tsuzuki, T.

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

Von Ruden, A.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Walzer, K.

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
[CrossRef]

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

Wang, L.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Wang, Q.

Q. Wang, D. Ma, “Management of charges and excitons for high-performance white organic light-emitting diodes,” Chem. Soc. Rev. 39(7), 2387–2398 (2010).
[CrossRef] [PubMed]

Wang, R.-J.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Watanabe, K.

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

Weaver, M. S.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Werner, A.

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

Wong, W.-K.

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Wong, W.-Y.

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Wu, Q.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Xia, S.

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Xie, G.

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Xie, L.

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Xu, H.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Xue, Q.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Yam, V. W.-W.

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

Yan, P.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

Yang, C. C.

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

Yin, H.-M.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

You, Y.

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

Yue, S.

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

Zhang, D.

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Zhang, H.

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

Zhang, R.

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

Zhang, S.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Zhang, T.

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

Zhang, Z.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Zhao, L.

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Zhao, Y.

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Zhou, X.

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

Adv. Funct. Mater.

J. S. Swensen, E. Polikarpov, A. Von Ruden, L. Wang, L. S. Sapochak, A. B. Padmaperuma, “Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter,” Adv. Funct. Mater. 21(17), 3250–3258 (2011).
[CrossRef]

Adv. Mater.

B. W. D'Andrade, R. J. Holmes, S. R. Forrest, “Efficient organic electrophosphorescent white-light-emitting device with a triple doped emissive layer,” Adv. Mater. 16(7), 624–628 (2004).
[CrossRef]

M. Pfeiffer, S. R. Forrest, K. Leo, M. E. Thompson, “Electrophosphorescent pin organic light-emitting devices for very-high-efficiency flat-panel displays,” Adv. Mater. 14(22), 1633–1636 (2002).
[CrossRef]

B. W. D'Andrade, S. R. Forrest, “White organic light-emitting devices for solid-state lighting,” Adv. Mater. 16(18), 1585–1595 (2004).
[CrossRef]

S. J. Su, H. Sasabe, Y. J. Pu, K. I. Nakayama, J. Kido, “Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘ideal’ operating voltage,” Adv. Mater. 22(30), 3311–3316 (2010).
[CrossRef] [PubMed]

G. Schwartz, M. Pfeiffer, S. Reineke, K. Walzer, K. Leo, “Harvesting triplet excitons from fluorescent blue emitters in white organic light emitting diodes,” Adv. Mater. 19(21), 3672–3676 (2007).
[CrossRef]

R.-J. Wang, D. Liu, H.-C. Ren, T. Zhang, H.-M. Yin, G.-Y. Liu, J.-Y. Li, “Highly efficient orange and white organic light-emitting diodes based on new orange iridium complexes,” Adv. Mater. 23(25), 2823–2827 (2011).
[CrossRef] [PubMed]

C. Han, G. Xie, H. Xu, Z. Zhang, L. Xie, Y. Zhao, S. Liu, W. Huang, “A single phosphine oxide host for high-efficiency white organic light-emitting diodes with extremely low operating voltages and reduced efficiency roll-off,” Adv. Mater. 23(21), 2491–2496 (2011).
[CrossRef] [PubMed]

Appl. Phys. Lett.

G. Schwartz, K. Fehse, M. Pfeiffer, K. Walzer, K. Leo, “Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions,” Appl. Phys. Lett. 89(8), 083509 (2006).
[CrossRef]

C.-L. Ho, M.-F. Lin, W.-Y. Wong, W.-K. Wong, C. H. Chen, “High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence,” Appl. Phys. Lett. 92(8), 083301 (2008).
[CrossRef]

Y. Li, D. Zhang, L. Duan, R. Zhang, L. Wang, Y. Qiu, “Elucidation of the electron injection mechanism of evaporated cesium carbonate cathode interlayer for organic light-emitting diodes,” Appl. Phys. Lett. 90(1), 012119 (2007).
[CrossRef]

H. Fukagawa, K. Watanabe, T. Tsuzuki, S. Tokito, “Highly efficient, deep-blue phosphorescent organic light emitting diodes with a double-emitting layer structure,” Appl. Phys. Lett. 93(13), 133312 (2008).
[CrossRef]

J. H. Lee, C. L. Huang, C. H. Hsiao, M. K. Leung, C. C. Yang, C. C. Chao, “Blue phosphorescent organic light-emitting device with double emitting layer,” Appl. Phys. Lett. 94(22), 223301 (2009).
[CrossRef]

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

R. Meerheim, K. Walzer, M. Pfeiffer, K. Leo, “Ultrastable and efficient red organic light emitting diodes with doped transport layers,” Appl. Phys. Lett. 89(6), 061111 (2006).
[CrossRef]

J. Lee, J. I. Lee, K. I. Song, S. J. Lee, H. Y. Chu, “Effects of interlayers on phosphorescent blue organic light-emitting diodes,” Appl. Phys. Lett. 92(20), 203305 (2008).
[CrossRef]

Chem. Commun.

D. Hu, F. Shen, H. Liu, P. Lu, Y. Lv, D. Liu, Y. Ma, “Separation of electrical and optical energy gaps for constructing bipolar organic wide bandgap materials,” Chem. Commun. 48(24), 3015–3017 (2012).
[CrossRef] [PubMed]

Chem. Soc. Rev.

Q. Wang, D. Ma, “Management of charges and excitons for high-performance white organic light-emitting diodes,” Chem. Soc. Rev. 39(7), 2387–2398 (2010).
[CrossRef] [PubMed]

Chemistry

C. Han, Z. Zhang, H. Xu, G. Xie, J. Li, Y. Zhao, Z. Deng, S. Liu, P. Yan, “Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence,” Chemistry 19(1), 141–154 (2013).
[CrossRef] [PubMed]

C. Han, Z. Zhang, H. Xu, J. Li, Y. Zhao, P. Yan, S. Liu, “Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-π-A systems,” Chemistry 19(4), 1385–1396 (2013).
[CrossRef] [PubMed]

J. Am. Chem. Soc.

C. Han, Z. Zhang, H. Xu, S. Yue, J. Li, P. Yan, Z. Deng, Y. Zhao, P. Yan, S. Liu, “Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts,” J. Am. Chem. Soc. 134(46), 19179–19188 (2012).
[CrossRef] [PubMed]

J. Appl. Phys.

X. Qiao, J. Chen, X. Li, D. Ma, “Observation of hole hopping via dopant in MoOx-doped organic semiconductors: Mechanism analysis and application for high performance organic light-emitting devices,” J. Appl. Phys. 107(10), 104505 (2010).
[CrossRef]

J. Phys. Chem. C

G. Xie, Z. Zhang, Q. Xue, S. Zhang, Y. Luo, L. Zhao, Q. Wu, P. Chen, B. Quan, Y. Zhao, S. Liu, “Tailoring the efficiencies and spectra of white organic light-emitting diodes with the interlayers,” J. Phys. Chem. C 115(1), 264–269 (2011).
[CrossRef]

Nano Lett.

M. Thomschke, S. Reineke, B. Lüssem, K. Leo, “Highly efficient white top-emitting organic light-emitting diodes comprising laminated microlens films,” Nano Lett. 12(1), 424–428 (2012).
[CrossRef] [PubMed]

Nat. Photonics

W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, H. Takezoe, “Light extraction from organic light-emitting diodes enhanced by spontaneously formed buckles,” Nat. Photonics 4(4), 222–226 (2010).
[CrossRef]

Nature

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, “Highly efficient phosphorescent emission from organic electroluminescent devices,” Nature 395(6698), 151–154 (1998).
[CrossRef]

S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
[CrossRef] [PubMed]

Org. Electron.

C. W. Seo, J. Y. Lee, “High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material,” Org. Electron. 12(9), 1459–1464 (2011).
[CrossRef]

D. P.-K. Tsang, M.-Y. Chan, A. Y.-Y. Tam, V. W.-W. Yam, “Host engineering for improving the performance of blue phosphorescent organic light-emitting devices,” Org. Electron. 12(7), 1114–1119 (2011).
[CrossRef]

Phys. Rev. B

N. Giebink, S. R. Forrest, “Quantum efficiency roll-off at high brightness in fluorescent and phosphorescent organic light emitting diodes,” Phys. Rev. B 77(23), 235215 (2008).
[CrossRef]

S. Reineke, K. Walzer, K. Leo, “Triplet-exciton quenching in organic phosphorescent light-emitting diodes with Ir-based emitters,” Phys. Rev. B 75(12), 125328 (2007).
[CrossRef]

Proc. SPIE

B. W. D’Andrade, J. Esler, C. Lin, V. Adamovich, S. Xia, M. S. Weaver, R. Kwong, J. J. Brown, “Realizing white phosphorescent 100 lm/W OLED efficacy,” Proc. SPIE 7051, 70510Q (2008).

Synth. Met.

Y. Ma, H. Zhang, J. Shen, C. Che, “Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes,” Synth. Met. 94(3), 245–248 (1998).
[CrossRef]

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Figures (7)

Fig. 1
Fig. 1

Schematic diagram of HOMO-LUMO values of some materials used in this paper.

Fig. 2
Fig. 2

Luminance-Voltage-Current density characteristics ofthe fabricated blue (B), green (G), yellow (Y) and Red (R) OLED. Inset: normalized EL spectrum of these OLEDs.

Fig. 3
Fig. 3

Schematic energy diagrams of our monochromatic OLED with D-EML.

Fig. 4
Fig. 4

The current efficiency (CE), power efficiency (PE)and external quantum efficiency (EQE) versus luminancecharacteristics of the blue, green, yellow and red OLED.

Fig. 5
Fig. 5

Luminance-Voltage-Current density characteristics of the white PhOLEDs. Inset: the spectra of the white PhOLEDs.

Fig. 6
Fig. 6

Efficiencies-Luminance characteristics of the white PhOLEDs.

Fig. 7
Fig. 7

Schematic energy diagrams of our WOLED with TcTa:TmPPPyTz interlayer.

Tables (1)

Tables Icon

Table 1 EL performance of WOLEDs.

Metrics