Abstract

In this work, we conducted studies of tandem organic light-emitting devices (OLEDs) based on the connecting structure consisting of n-doped electron-transport layer (n-ETL)/1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN)/hole-transport layer. We investigated effects of different n-ETL materials and different HATCN thicknesses on characteristics of tandem OLEDs. Results show that the tandem OLEDs with n-BPhen and a 20 nm layer of HATCN in the connecting structure exhibited the best performance. With these, highly efficient and bright green phosphorescent two-emitting-unit tandem OLEDs, with drive voltages significantly lower than twice that of the single-unit benchmark device and current efficiencies higher than twice that of the single-unit benchmark device, were demonstrated.

© 2014 Optical Society of America

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2012 (3)

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

S. Lee, J. H. Lee, and J. J. Kim, “The mechanism of charge generation in charge-generation units composed of p-doped hole-transporting layer/HATCN/n-doped electron-transporting layers,” Adv. Funct. Mater. 22, 855–860 (2012).
[CrossRef]

2011 (5)

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

2010 (4)

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

2009 (2)

Y.-K. Kim, J. W. Kim, and Y. Park, “Energy level alignment at a charge generation interface between 4,4(′)-bis(N-phenyl-1-naphthylamino)biphenyl and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile,” Appl. Phys. Lett. 94, 063305 (2009).
[CrossRef]

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

2008 (4)

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (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, 054502 (2008).
[CrossRef]

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

L. S. Liao and K. P. Klubek, “Power efficiency improvement in a tandem organic light-emitting diode,” Appl. Phys. Lett. 92, 223311 (2008).
[CrossRef]

2007 (1)

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

2006 (4)

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

T. Y. Cho, C. L. Lin, and C. C. Wu, “Microcavity two-unit tandem organic light-emitting devices having a high efficiency,” Appl. Phys. Lett. 88, 111106 (2006).
[CrossRef]

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

2005 (4)

F. W. Guo and D. G. Ma, “White organic light-emitting diodes based on tandem structures,” Appl. Phys. Lett. 87, 173510 (2005).
[CrossRef]

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

2004 (3)

T. Tsutsui and M. Terai, “Electric field-assisted bipolar charge spouting in organic thin-film diodes,” Appl. Phys. Lett. 84, 440–442 (2004).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[CrossRef]

L. S. Liao, K. P. Klubek, and C. W. Tang, “High-efficiency tandem organic light-emitting diodes,” Appl. Phys. Lett. 84, 167169 (2004).
[CrossRef]

2003 (3)

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

S. R. Forrest, “The road to high efficiency organic light emitting devices,” Org. Electron. 4, 45–48 (2003).
[CrossRef]

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

1996 (1)

S. A. VanSlyke, C. H. Chen, and C. W. Tang, “Organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 69, 2160–2162 (1996).
[CrossRef]

1987 (1)

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

Bao, Q. Y.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Blochwitz-Nimoth, J.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Blum, R.-P.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Broeker, B.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Brown, J. J.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Chang, C. C.

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[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, 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, 054502 (2008).
[CrossRef]

Chen, C. H.

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[CrossRef]

S. A. VanSlyke, C. H. Chen, and C. W. Tang, “Organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 69, 2160–2162 (1996).
[CrossRef]

Chen, C. W.

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Chen, J.

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Chen, J. F.

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[CrossRef]

Chen, J. S.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

Chen, M. H.

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

Chen, Y.

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Chen, Y. H.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

Chiba, T.

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

Cho, T. Y.

T. Y. Cho, C. L. Lin, and C. C. Wu, “Microcavity two-unit tandem organic light-emitting devices having a high efficiency,” Appl. Phys. Lett. 88, 111106 (2006).
[CrossRef]

Chopra, N.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Chu, C. W.

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Chu, X.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Chwang, A. B.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Comfort, D. L.

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

Deng, Y. H.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Eom, S. H.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Forrest, S. R.

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

S. R. Forrest, “The road to high efficiency organic light emitting devices,” Org. Electron. 4, 45–48 (2003).
[CrossRef]

Giebink, N. C.

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

Glowatzki, H.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Gnam, F.

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

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, 054502 (2008).
[CrossRef]

Greiner, M. T.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Guo, F. W.

F. W. Guo and D. G. Ma, “White organic light-emitting diodes based on tandem structures,” Appl. Phys. Lett. 87, 173510 (2005).
[CrossRef]

Hack, M.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Hamada, Y.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

Hamwi, S.

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

Hatwar, T. K.

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

Helander, M. G.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Hewitt, R. H.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Hirasawa, M.

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

Hofmann, M.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Hofmann, O. T.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Huang, J. S.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Hwang, S. W.

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[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, 054502 (2008).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Kahn, A.

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

Kang, H.

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Kanno, H.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

Kido, J.

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

Kim, J. H.

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Kim, J. J.

S. Lee, J. H. Lee, and J. J. Kim, “The mechanism of charge generation in charge-generation units composed of p-doped hole-transporting layer/HATCN/n-doped electron-transporting layers,” Adv. Funct. Mater. 22, 855–860 (2012).
[CrossRef]

Kim, J. K.

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Kim, J. W.

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

Y.-K. Kim, J. W. Kim, and Y. Park, “Energy level alignment at a charge generation interface between 4,4(′)-bis(N-phenyl-1-naphthylamino)biphenyl and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile,” Appl. Phys. Lett. 94, 063305 (2009).
[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, 054502 (2008).
[CrossRef]

Kim, Y. H.

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

Kim, Y.-K.

Y.-K. Kim, J. W. Kim, and Y. Park, “Energy level alignment at a charge generation interface between 4,4(′)-bis(N-phenyl-1-naphthylamino)biphenyl and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile,” Appl. Phys. Lett. 94, 063305 (2009).
[CrossRef]

Klubek, K. P.

L. S. Liao and K. P. Klubek, “Power efficiency improvement in a tandem organic light-emitting diode,” Appl. Phys. Lett. 92, 223311 (2008).
[CrossRef]

L. S. Liao, K. P. Klubek, and C. W. Tang, “High-efficiency tandem organic light-emitting diodes,” Appl. Phys. Lett. 84, 167169 (2004).
[CrossRef]

Koch, N.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Kowalsky, W.

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

Krajewski, T.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Kroeger, M.

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

Kwok, H. S.

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

Lee, J.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Lee, J. H.

S. Lee, J. H. Lee, and J. J. Kim, “The mechanism of charge generation in charge-generation units composed of p-doped hole-transporting layer/HATCN/n-doped electron-transporting layers,” Adv. Funct. Mater. 22, 855–860 (2012).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 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, 054502 (2008).
[CrossRef]

Lee, S.

S. Lee, J. H. Lee, and J. J. Kim, “The mechanism of charge generation in charge-generation units composed of p-doped hole-transporting layer/HATCN/n-doped electron-transporting layers,” Adv. Funct. Mater. 22, 855–860 (2012).
[CrossRef]

Lee, S. T.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Leo, K.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Li, Y. Q.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Liao, L. S.

L. S. Liao and K. P. Klubek, “Power efficiency improvement in a tandem organic light-emitting diode,” Appl. Phys. Lett. 92, 223311 (2008).
[CrossRef]

L. S. Liao, K. P. Klubek, and C. W. Tang, “High-efficiency tandem organic light-emitting diodes,” Appl. Phys. Lett. 84, 167169 (2004).
[CrossRef]

Liao, L.-S.

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

Lin, C. L.

T. Y. Cho, C. L. Lin, and C. C. Wu, “Microcavity two-unit tandem organic light-emitting devices having a high efficiency,” Appl. Phys. Lett. 88, 111106 (2006).
[CrossRef]

Lin, C. T.

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

Liu, Z. W.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Lu, Y. J.

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Lu, Z. H.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Ma, D.

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Ma, D. G.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

F. W. Guo and D. G. Ma, “White organic light-emitting diodes based on tandem structures,” Appl. Phys. Lett. 87, 173510 (2005).
[CrossRef]

Mameno, K.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

Mao, S. Y.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Meyer, J.

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Minamoto, K.

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

Miyazaki, R.

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

Moro, L.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Muellen, K.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Nakayama, K.-i.

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

Nishimura, K.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Oh, H. Y.

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

Okumoto, K.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

Park, S. M.

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

Park, Y.

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Y.-K. Kim, J. W. Kim, and Y. Park, “Energy level alignment at a charge generation interface between 4,4(′)-bis(N-phenyl-1-naphthylamino)biphenyl and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile,” Appl. Phys. Lett. 94, 063305 (2009).
[CrossRef]

Peng, H. J.

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

Pfeiffer, M.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Pu, Y. J.

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

Pu, Y.-J.

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

Puzzo, D. P.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Qiu, J.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Rabe, J. P.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Rajan, K.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Ricks, M. L.

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

Riedl, T.

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

Rieger, R.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Rothman, M. A.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Rutherford, N.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[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, 054502 (2008).
[CrossRef]

Saito, N.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

Sasabe, H.

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

Seo, J.

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Shibata, K.

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

Silvernail, J. A.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Slusarek, W. K.

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

So, F.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Sun, J. X.

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

Sun, Y.

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

Takeda, T.

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

Tanaka, D.

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

Tang, C. W.

L. S. Liao, K. P. Klubek, and C. W. Tang, “High-efficiency tandem organic light-emitting diodes,” Appl. Phys. Lett. 84, 167169 (2004).
[CrossRef]

S. A. VanSlyke, C. H. Chen, and C. W. Tang, “Organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 69, 2160–2162 (1996).
[CrossRef]

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

Tang, J. X.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Terai, M.

T. Tsutsui and M. Terai, “Electric field-assisted bipolar charge spouting in organic thin-film diodes,” Appl. Phys. Lett. 84, 440–442 (2004).
[CrossRef]

Tsutsui, T.

T. Tsutsui and M. Terai, “Electric field-assisted bipolar charge spouting in organic thin-film diodes,” Appl. Phys. Lett. 84, 440–442 (2004).
[CrossRef]

VanSlyke, S. A.

S. A. VanSlyke, C. H. Chen, and C. W. Tang, “Organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 69, 2160–2162 (1996).
[CrossRef]

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

Vollmer, A.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Wang, L.

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Wang, L. X.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

Wang, Z. B.

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
[CrossRef]

Watanabe, S.

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

Weaver, M. S.

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

Werner, A.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Winkler, T.

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

Witte, M.

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

Wong, M.

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

Wrzesniewski, E.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Wu, C. C.

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

T. Y. Cho, C. L. Lin, and C. C. Wu, “Microcavity two-unit tandem organic light-emitting devices having a high efficiency,” Appl. Phys. Lett. 88, 111106 (2006).
[CrossRef]

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Wu, C. I.

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

Wu, E. H. E.

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Xiao, Y.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Xue, J. G.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Yan, D.

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Yan, D. H.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

Yang, J. P.

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

Yang, Y.

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

Yi, Y.

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[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, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 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, 054502 (2008).
[CrossRef]

Zheng, Y.

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

Zhou, X.

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

Zhu, F. R.

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

Zhu, X. L.

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

Zojer, E.

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Adv. Funct. Mater. (3)

K. S. Yook, S. O. Jeon, S.-Y. Min, J. Y. Lee, H.-J. Yang, T. Noh, S.-K. Kang, and T.-W. Lee, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Adv. Funct. Mater. 20, 1797–1802 (2010).
[CrossRef]

S. Hamwi, J. Meyer, M. Kroeger, T. Winkler, M. Witte, T. Riedl, A. Kahn, and W. Kowalsky, “The role of transition metal oxides in charge-generation layers for stacked organic light-emitting diodes,” Adv. Funct. Mater. 20, 1762–1766 (2010).
[CrossRef]

S. Lee, J. H. Lee, and J. J. Kim, “The mechanism of charge generation in charge-generation units composed of p-doped hole-transporting layer/HATCN/n-doped electron-transporting layers,” Adv. Funct. Mater. 22, 855–860 (2012).
[CrossRef]

Adv. Mater. (1)

L.-S. Liao, W. K. Slusarek, T. K. Hatwar, M. L. Ricks, and D. L. Comfort, “Tandem organic light-emitting mode using hexaazatriphenylene hexacarbonitrile in the intermediate connector,” Adv. Mater. 20, 324–329 (2008).
[CrossRef]

Appl. Phys. Lett. (18)

L. S. Liao and K. P. Klubek, “Power efficiency improvement in a tandem organic light-emitting diode,” Appl. Phys. Lett. 92, 223311 (2008).
[CrossRef]

Y. Chen, J. Chen, D. Ma, D. Yan, and L. Wang, “Tandem white phosphorescent organic light-emitting diodes based on interface-modified C-60/pentacene organic heterojunction as charge generation layer,” Appl. Phys. Lett. 99, 103304 (2011).
[CrossRef]

Y. H. Chen, J. S. Chen, D. G. Ma, D. H. Yan, L. X. Wang, and F. R. Zhu, “High power efficiency tandem organic light-emitting diodes based on bulk heterojunction organic bipolar charge generation layer,” Appl. Phys. Lett. 98, 243309 (2011).
[CrossRef]

Y.-K. Kim, J. W. Kim, and Y. Park, “Energy level alignment at a charge generation interface between 4,4(′)-bis(N-phenyl-1-naphthylamino)biphenyl and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile,” Appl. Phys. Lett. 94, 063305 (2009).
[CrossRef]

S. M. Park, Y. H. Kim, Y. Yi, H. Y. Oh, and J. W. Kim, “Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices,” Appl. Phys. Lett. 97, 063308 (2010).
[CrossRef]

C. I. Wu, C. T. Lin, Y. H. Chen, M. H. Chen, Y. J. Lu, and C. C. Wu, “Electronic structures and electron-injection mechanisms of cesium-carbonate-incorporated cathode structures for organic light-emitting devices,” Appl. Phys. Lett. 88, 152104 (2006).
[CrossRef]

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

A. B. Chwang, M. A. Rothman, S. Y. Mao, R. H. Hewitt, M. S. Weaver, J. A. Silvernail, K. Rajan, M. Hack, J. J. Brown, X. Chu, L. Moro, T. Krajewski, and N. Rutherford, “Thin film encapsulated flexible organic electroluminescent displays,” Appl. Phys. Lett. 83, 413–415 (2003).
[CrossRef]

H. Kanno, N. C. Giebink, Y. Sun, and S. R. Forrest, “Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters,” Appl. Phys. Lett. 89, 023503 (2006).
[CrossRef]

L. S. Liao, K. P. Klubek, and C. W. Tang, “High-efficiency tandem organic light-emitting diodes,” Appl. Phys. Lett. 84, 167169 (2004).
[CrossRef]

T. Y. Cho, C. L. Lin, and C. C. Wu, “Microcavity two-unit tandem organic light-emitting devices having a high efficiency,” Appl. Phys. Lett. 88, 111106 (2006).
[CrossRef]

J. Meyer, M. Kroeger, S. Hamwi, F. Gnam, T. Riedl, W. Kowalsky, and A. Kahn, “Charge generation layers comprising transition metal-oxide/organic interfaces: electronic structure and charge generation mechanism,” Appl. Phys. Lett. 96, 193302 (2010).
[CrossRef]

S. A. VanSlyke, C. H. Chen, and C. W. Tang, “Organic electroluminescent devices with improved stability,” Appl. Phys. Lett. 69, 2160–2162 (1996).
[CrossRef]

J. X. Sun, X. L. Zhu, H. J. Peng, M. Wong, and H. S. Kwok, “Effective intermediate layers for highly efficient stacked organic light-emitting devices,” Appl. Phys. Lett. 87, 093504 (2005).
[CrossRef]

T. Tsutsui and M. Terai, “Electric field-assisted bipolar charge spouting in organic thin-film diodes,” Appl. Phys. Lett. 84, 440–442 (2004).
[CrossRef]

F. W. Guo and D. G. Ma, “White organic light-emitting diodes based on tandem structures,” Appl. Phys. Lett. 87, 173510 (2005).
[CrossRef]

C. W. Chen, Y. J. Lu, C. C. Wu, E. H. E. Wu, C. W. Chu, and Y. Yang, “Effective connecting architecture for tandem organic light-emitting devices,” Appl. Phys. Lett. 87, 241121 (2005).
[CrossRef]

C. C. Chang, J. F. Chen, S. W. Hwang, and C. H. Chen, “Highly efficient white organic electroluminescent devices based on tandem architecture,” Appl. Phys. Lett. 87, 253501 (2005).
[CrossRef]

Chem. Lett. (1)

D. Tanaka, T. Takeda, T. Chiba, S. Watanabe, and J. Kido, “Novel electron-transport material containing boron atom with a high triplet excited energy level,” Chem. Lett. 36, 262–263 (2007).
[CrossRef]

J. Appl. Phys. (1)

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, 054502 (2008).
[CrossRef]

J. Korean Phys. Soc. (1)

H. Kang, J. H. Kim, J. K. Kim, J. Seo, and Y. Park, “Interface electronic structure of a strongly electron withdrawing molecule on an indium-tin-oxide surface,” J. Korean Phys. Soc. 59, 3060–3063 (2011).
[CrossRef]

Jpn. J. Appl. Phys. (2)

H. Kanno, Y. Hamada, K. Nishimura, K. Okumoto, N. Saito, K. Mameno, and K. Shibata, “Reduction in power consumption for full-color active matrix organic light-emitting device,” Jpn. J. Appl. Phys. 45, L947–L950 (2006).
[CrossRef]

C. C. Chang, S. W. Hwang, C. H. Chen, and J. F. Chen, “High-efficiency organic electroluminescent device with multiple emitting units,” Jpn. J. Appl. Phys. 43, 6418–6422 (2004).
[CrossRef]

Nano Lett. (1)

H. Glowatzki, B. Broeker, R.-P. Blum, O. T. Hofmann, A. Vollmer, R. Rieger, K. Muellen, E. Zojer, J. P. Rabe, and N. Koch, “‘Soft’ metallic contact to isolated C-60 molecules,” Nano Lett. 8, 3825–3829 (2008).
[CrossRef]

Org. Electron. (6)

S. H. Eom, Y. Zheng, E. Wrzesniewski, J. Lee, N. Chopra, F. So, and J. G. Xue, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 10, 686–691 (2009).
[CrossRef]

M. Pfeiffer, K. Leo, X. Zhou, J. S. Huang, M. Hofmann, A. Werner, and J. Blochwitz-Nimoth, “Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices,” Org. Electron. 4, 89–103 (2003).
[CrossRef]

H. Sasabe, K. Minamoto, Y. J. Pu, M. Hirasawa, and J. Kido, “Ultra high-efficiency multi-photon emission blue phosphorescent OLEDs with external quantum efficiency exceeding 40%,” Org. Electron. 13, 2615–2619 (2012).
[CrossRef]

J. P. Yang, Q. Y. Bao, Y. Xiao, Y. H. Deng, Y. Q. Li, S. T. Lee, and J. X. Tang, “Hybrid intermediate connector for tandem OLEDs with the combination of MoO3-based interlayer and p-type doping,” Org. Electron. 13, 2243–2249 (2012).
[CrossRef]

S. R. Forrest, “The road to high efficiency organic light emitting devices,” Org. Electron. 4, 45–48 (2003).
[CrossRef]

T. Chiba, Y.-J. Pu, R. Miyazaki, K.-i. Nakayama, H. Sasabe, and J. Kido, “Ultra-high efficiency by multiple emission from stacked organic light-emitting devices,” Org. Electron. 12, 710–715 (2011).
[CrossRef]

Science (1)

M. G. Helander, Z. B. Wang, J. Qiu, M. T. Greiner, D. P. Puzzo, Z. W. Liu, and Z. H. Lu, “Chlorinated indium tin oxide electrodes with high work function for organic device compatibility,” Science 332, 944–947 (2011).
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Figures (6)

Fig. 1.
Fig. 1.

Chemical structures of organic materials utilized in this study.

Fig. 2.
Fig. 2.

Structures of the OLEDs in this study. (a) The structure of Device A. (b) The structures of Device B1, B2, and B3. The ETMs utilized in Device B1, B2, and B3 were TPBi, BPhen, and 3TPYMB, respectively. (c) The structures of Device C1, C2, C3, C4, and C5. The thickness of HATCN (x  nm) in Device C1, C2, C3, C4, and C5 were 5, 10, 20, 30, and 40 nm, respectively.

Fig. 3.
Fig. 3.

Characteristics of device A: (a) current–voltage–luminance characteristics and (b) current and power efficiencies versus luminance.

Fig. 4.
Fig. 4.

Characteristics of devices B1, B2, and B3: (a) current–voltage–luminance characteristics and (b) current and power efficiencies versus luminance.

Fig. 5.
Fig. 5.

Schematic energy band diagram of the connecting structure of the tandem OLEDs in this study.

Fig. 6.
Fig. 6.

Characteristics of devices C1, C2, C3, C4, and C5: (a) current–voltage–luminance characteristics and (b) current and power efficiencies versus luminance.

Tables (1)

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Table 1. Characteristics of OLEDs in this Study

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