Abstract

We replace Indium Tin Oxide (ITO) with an MgO nano-facet Embedded WO3/Ag/WO3(WAW) multilayer for electrodes of high efficiency OLEDs. WAW shows higher values for transmittance (93%) and conductivity (1.3×105 S/cm) than those of ITO. Moreover, WAW shows higher transmittance (92.5%) than that of ITO (86.4%) in the blue region (<500 nm). However, due to the large difference in refractive indices (n) of glass (n=1.55) and WO3 (n=1.95), the incident light has a small critical angle (52°). Thus, the generated light is confined by the glass/WAW interface, resulting in low light outcoupling efficiency (~20%). This can be enhanced by using a nano-facet structured MgO (n=1.73) layer and a ZrO2 (n=1.84) layer as a graded index layer. Using these optimized electrodes, ITO-free, OLEDs with various emission wavelengths have been produced. The luminance of OLEDs using MgO/ZrO2/WAW layers is enhanced by 24% compared to that of devices with ITO.

© 2012 OSA

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  1. S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, and K. Leo, “White organic light-emitting diodes with fluorescent tube efficiency,” Nature 459(7244), 234–238 (2009).
    [CrossRef] [PubMed]
  2. S. Choi, S.-J. Kim, C. Fuentes-Hernandez, and B. Kippelen, “ITO-free large-area organic light-emitting diodes with an integrated metal grid,” Opt. Express 19(S4Suppl 4), A793–A803 (2011).
    [CrossRef] [PubMed]
  3. S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
    [CrossRef]
  4. J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
    [CrossRef] [PubMed]
  5. R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
    [CrossRef] [PubMed]
  6. Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
    [CrossRef]
  7. A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
    [CrossRef]
  8. H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
    [CrossRef]
  9. H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
    [CrossRef]
  10. K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
    [CrossRef]
  11. K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
    [CrossRef]
  12. H. Cho, C. Yun, and S. Yoo, “Multilayer transparent electrode for organic light-emitting diodes: tuning its optical characteristics,” Opt. Express 18(4), 3404–3414 (2010).
    [CrossRef] [PubMed]
  13. H. A. Macleod, Thin Film Optical Filters (Taylor & Francis, 2001).
  14. Y. Sun and S. R. Forrest, “Enhanced light outcoupling of organic light-emitting devices using embedded low-index grids,” Nat. Photonics 2(8), 483–487 (2008).
    [CrossRef]
  15. M. Cui, H. P. Urbach, and D. K. G. de Boer, “Optimization of light extraction from OLEDs,” Opt. Express 15(8), 4398–4409 (2007).
    [CrossRef] [PubMed]
  16. T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
    [CrossRef]
  17. Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
    [CrossRef]
  18. W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
    [CrossRef] [PubMed]
  19. T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
    [CrossRef]
  20. T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
    [CrossRef] [PubMed]
  21. T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
    [CrossRef]
  22. J. Feng, T. Okamoto, and S. Kawata, “Enhancement of electroluminescence through a two-dimensional corrugated metal film by grating-induced surface-plasmon cross coupling,” Opt. Lett. 30(17), 2302–2304 (2005).
    [CrossRef] [PubMed]
  23. M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
    [CrossRef]
  24. K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
    [CrossRef]
  25. J. H. Son, H. K. Yu, and J.-L. Lee, “MgO nano-pyramids structure for enhancement of light extraction efficiency in vertical light-emitting diodes,” Opt. Express 18(S3Suppl 3), A403–A410 (2010).
    [CrossRef] [PubMed]
  26. A. Subrahmanyam and A. Karuppasamy, “Optical and electrochromic properties of oxygen sputtered tungsten oxide (WO3) thin films,” Sol. Energy Mater. Sol. Cells 91(4), 266–274 (2007).
    [CrossRef]
  27. J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
    [CrossRef]
  28. Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
    [CrossRef]
  29. K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
    [CrossRef]

2011

S. Choi, S.-J. Kim, C. Fuentes-Hernandez, and B. Kippelen, “ITO-free large-area organic light-emitting diodes with an integrated metal grid,” Opt. Express 19(S4Suppl 4), A793–A803 (2011).
[CrossRef] [PubMed]

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

2010

H. Cho, C. Yun, and S. Yoo, “Multilayer transparent electrode for organic light-emitting diodes: tuning its optical characteristics,” Opt. Express 18(4), 3404–3414 (2010).
[CrossRef] [PubMed]

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

J. H. Son, H. K. Yu, and J.-L. Lee, “MgO nano-pyramids structure for enhancement of light extraction efficiency in vertical light-emitting diodes,” Opt. Express 18(S3Suppl 3), A403–A410 (2010).
[CrossRef] [PubMed]

2009

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

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

2008

Y. Sun and S. R. Forrest, “Enhanced light outcoupling of organic light-emitting devices using embedded low-index grids,” Nat. Photonics 2(8), 483–487 (2008).
[CrossRef]

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
[CrossRef]

2007

A. Subrahmanyam and A. Karuppasamy, “Optical and electrochromic properties of oxygen sputtered tungsten oxide (WO3) thin films,” Sol. Energy Mater. Sol. Cells 91(4), 266–274 (2007).
[CrossRef]

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

M. Cui, H. P. Urbach, and D. K. G. de Boer, “Optimization of light extraction from OLEDs,” Opt. Express 15(8), 4398–4409 (2007).
[CrossRef] [PubMed]

2005

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

J. Feng, T. Okamoto, and S. Kawata, “Enhancement of electroluminescence through a two-dimensional corrugated metal film by grating-induced surface-plasmon cross coupling,” Opt. Lett. 30(17), 2302–2304 (2005).
[CrossRef] [PubMed]

2004

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

2003

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

2002

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

2001

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

2000

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Agrawal, M.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

Araoka, F.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Baik, K.-H.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Bao, Z.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Becerril, H. A.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Capelli, R.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Chen, Y.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Cho, H.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

H. Cho, C. Yun, and S. Yoo, “Multilayer transparent electrode for organic light-emitting diodes: tuning its optical characteristics,” Opt. Express 18(4), 3404–3414 (2010).
[CrossRef] [PubMed]

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

Choi, H. W.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

Choi, J.-M.

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

Choi, S.

Chrisey, D. B.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Cui, M.

de Boer, D. K. G.

Do, Y. R.

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

Facchetti, A.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Feng, J.

Finocchi, F.

J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
[CrossRef]

Forrest, S. R.

Y. Sun and S. R. Forrest, “Enhanced light outcoupling of organic light-emitting devices using embedded low-index grids,” Nat. Photonics 2(8), 483–487 (2008).
[CrossRef]

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

Fuentes-Hernandez, C.

Fujii, H.

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

Furukawa, K.

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

Generali, G.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Gilmore, C. M.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Goniakowski, J.

J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
[CrossRef]

Han, Y.-S.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Hiyama, K.

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

Hong, K.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Horwitz, J. S.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Ishikawa, K.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Jeon, S. O.

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

Jeong, S. M.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Joo, C. W.

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

Juni, N.

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

Kafafi, Z. H.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Karuppasamy, A.

A. Subrahmanyam and A. Karuppasamy, “Optical and electrochromic properties of oxygen sputtered tungsten oxide (WO3) thin films,” Sol. Energy Mater. Sol. Cells 91(4), 266–274 (2007).
[CrossRef]

Kawano, K.

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

Kawata, S.

Kim, H.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Kim, K.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Kim, K.-B.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Kim, S.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Kim, S. H.

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

Kim, S.-J.

Kim, Y. C.

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

Kippelen, B.

Koh, T.-W.

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

Koo, W. H.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Kushto, G.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Kwon, J. E.

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

Lee, H. Y.

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

Lee, I.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Lee, J.-L.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

J. H. Son, H. K. Yu, and J.-L. Lee, “MgO nano-pyramids structure for enhancement of light extraction efficiency in vertical light-emitting diodes,” Opt. Express 18(S3Suppl 3), A403–A410 (2010).
[CrossRef] [PubMed]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Lee, K.-H.

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Lee, M.-H.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Lee, N.-Y.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

Lee, S.

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

Lee, Y. H.

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

Leo, K.

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

Lindner, F.

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

Liu, Z.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Lüssem, B.

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

Lyer, S. S. K.

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

Mallajosyula, A. T.

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

Mazhari, B.

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

Muccini, M.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Nakamura, T.

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

Nakayama, T.

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

Nishi, Y.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Nishimura, S.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Noguera, C.

J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
[CrossRef]

Oh, J. H.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Ohtani, H.

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

Okajima, M.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Okamoto, T.

Park, H.-G.

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Park, J.-W.

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

Park, S.

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

Park, S. Y.

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

Paul, B. C.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Peumans, P.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

Piqué, A.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Reineke, S.

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

Roberts, M. E.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Schwartz, G.

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

Seidler, N.

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

Son, J. H.

Song, Y. W.

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

Srivastava, N.

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

Subrahmanyam, A.

A. Subrahmanyam and A. Karuppasamy, “Optical and electrochromic properties of oxygen sputtered tungsten oxide (WO3) thin films,” Sol. Energy Mater. Sol. Cells 91(4), 266–274 (2007).
[CrossRef]

Sun, Y.

Y. Sun and S. R. Forrest, “Enhanced light outcoupling of organic light-emitting devices using embedded low-index grids,” Nat. Photonics 2(8), 483–487 (2008).
[CrossRef]

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

Tak, Y.-H.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Takezoe, H.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Toffanin, S.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Toyooka, T.

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

Tsutsui, T.

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

Tsutsumi, N.

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

Urbach, H. P.

Usta, H.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Walzer, K.

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

Wei, P.

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

Wu, J.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Yahiro, M.

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

Yokogawa, H.

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

Yokoyama, M.

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

Yoo, S.

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

H. Cho, C. Yun, and S. Yoo, “Multilayer transparent electrode for organic light-emitting diodes: tuning its optical characteristics,” Opt. Express 18(4), 3404–3414 (2010).
[CrossRef] [PubMed]

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

Yook, K. S.

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

Yoon, M.-H.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Yu, H. K.

J. H. Son, H. K. Yu, and J.-L. Lee, “MgO nano-pyramids structure for enhancement of light extraction efficiency in vertical light-emitting diodes,” Opt. Express 18(S3Suppl 3), A403–A410 (2010).
[CrossRef] [PubMed]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Yun, C.

H. Cho, C. Yun, and S. Yoo, “Multilayer transparent electrode for organic light-emitting diodes: tuning its optical characteristics,” Opt. Express 18(4), 3404–3414 (2010).
[CrossRef] [PubMed]

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

ACS Nano

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano 4(1), 43–48 (2010).
[CrossRef] [PubMed]

Adv. Funct. Mater.

S. H. Kim, S. Park, J. E. Kwon, and S. Y. Park, “Organic light-emitting diodes with a white-emitting molecule: emission mechanism and device characteristics,” Adv. Funct. Mater. 21(4), 644–651 (2011).
[CrossRef]

Adv. Mater. (Deerfield Beach Fla.)

W. H. Koo, S. M. Jeong, S. Nishimura, F. Araoka, K. Ishikawa, T. Toyooka, and H. Takezoe, “Polarization conversion in surface-plasmon-coupled emission from organic light-emitting diodes using spontaneously formed buckles,” Adv. Mater. (Deerfield Beach Fla.) 23(8), 1003–1007 (2011).
[CrossRef] [PubMed]

T.-W. Koh, J.-M. Choi, S. Lee, and S. Yoo, “Optical outcoupling enhancement in organic light-emitting diodes: highly conductive polymer as a low-index layer on microstructured ITO electrodes,” Adv. Mater. (Deerfield Beach Fla.) 22(16), 1849–1853 (2010).
[CrossRef] [PubMed]

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, and M. Yokoyama, “Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer,” Adv. Mater. (Deerfield Beach Fla.) 13(15), 1149–1152 (2001).
[CrossRef]

K. Hong, H. K. Yu, I. Lee, K. Kim, S. Kim, and J.-L. Lee, “Enhanced light outcoupling of organic light-emitting diodes: Spontaneously formed nanofacet-structured MgO as a refractive index modulation layer,” Adv. Mater. (Deerfield Beach Fla.) 22(43), 4890–4894 (2010).
[CrossRef]

Appl. Phys. Lett.

M. Agrawal, Y. Sun, S. R. Forrest, and P. Peumans, “Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors,” Appl. Phys. Lett. 90(24), 241112 (2007).
[CrossRef]

K. S. Yook, S. O. Jeon, C. W. Joo, and H. Y. Lee, “Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode,” Appl. Phys. Lett. 93(1), 013301 (2008).
[CrossRef]

Z. Liu, J. H. Oh, M. E. Roberts, P. Wei, B. C. Paul, M. Okajima, Y. Nishi, and Z. Bao, “Solution-processed flexible organic transistors showing very-low subthreshold slope with a bilayer polymeric dielectric on plastic,” Appl. Phys. Lett. 94(20), 203301 (2009).
[CrossRef]

J. Appl. Phys.

H. Kim, J. S. Horwitz, G. Kushto, A. Piqué, Z. H. Kafafi, C. M. Gilmore, and D. B. Chrisey, “Effect of film thickness on the properties of indium tin oxide thin films,” J. Appl. Phys. 88(10), 6021–6025 (2000).
[CrossRef]

Y. R. Do, Y. C. Kim, Y. W. Song, and Y. H. Lee, “Enhanced light extraction efficiency from organic light emitting diodes by insertion of a two-dimensional photonic crystal structure,” J. Appl. Phys. 96(12), 7629–7636 (2004).
[CrossRef]

T. Nakamura, N. Tsutsumi, N. Juni, and H. Fujii, “Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate,” J. Appl. Phys. 97(5), 054505 (2005).
[CrossRef]

J. Phys. Chem. C

K. Hong, K. Kim, S. Kim, I. Lee, H. Cho, S. Yoo, H. W. Choi, N.-Y. Lee, Y.-H. Tak, and J.-L. Lee, “Optical properties of WO3/Ag/WO3 multilayer as transparent cathode in top-emitting organic light emitting diodes,” J. Phys. Chem. C 115(8), 3453–3459 (2011).
[CrossRef]

J. Soc. Inf. Disp.

T. Nakayama, K. Hiyama, K. Furukawa, and H. Ohtani, “Development of phosphorescent white OLED with extremely high power efficiency and long lifetime,” J. Soc. Inf. Disp. 16(2), 231–236 (2008).
[CrossRef]

Jpn. J. Appl. Phys.

K.-B. Kim, Y.-H. Tak, Y.-S. Han, K.-H. Baik, M.-H. Yoon, and M.-H. Lee, “Relationship between surface roughness of indium tin oxide and leakage current of organic light-emitting diode,” Jpn. J. Appl. Phys. 42(Part 2, No. 4B), L438–L440 (2003).
[CrossRef]

Nat. Mater.

R. Capelli, S. Toffanin, G. Generali, H. Usta, A. Facchetti, and M. Muccini, “Organic light-emitting transistors with an efficiency that outperforms the equivalent light-emitting diodes,” Nat. Mater. 9(6), 496–503 (2010).
[CrossRef] [PubMed]

Nat. Photonics

Y. Sun and S. R. Forrest, “Enhanced light outcoupling of organic light-emitting devices using embedded low-index grids,” Nat. Photonics 2(8), 483–487 (2008).
[CrossRef]

Nature

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

Opt. Express

Opt. Lett.

Org. Electron.

H. Cho, C. Yun, J.-W. Park, and S. Yoo, “Highly flexible organic light-emitting diodes based on ZnS/Ag/WO3 multilayer transparent electrodes,” Org. Electron. 10(6), 1163–1169 (2009).
[CrossRef]

Rep. Prog. Phys.

J. Goniakowski, F. Finocchi, and C. Noguera, “Polarity of oxide surfaces and nanostructures,” Rep. Prog. Phys. 71(1), 016501 (2008).
[CrossRef]

Sol. Energy Mater. Sol. Cells

A. Subrahmanyam and A. Karuppasamy, “Optical and electrochromic properties of oxygen sputtered tungsten oxide (WO3) thin films,” Sol. Energy Mater. Sol. Cells 91(4), 266–274 (2007).
[CrossRef]

A. T. Mallajosyula, N. Srivastava, S. S. K. Lyer, and B. Mazhari, “Characterization of matrix and isolated organic solar cells,” Sol. Energy Mater. Sol. Cells 94(8), 1319–1323 (2010).
[CrossRef]

Thin Solid Films

Y.-H. Tak, K.-B. Kim, H.-G. Park, K.-H. Lee, and J.-L. Lee, “Criteria for ITO (indium-tin-oxide) thin film as the bottom electrode of an organic light emitting diode,” Thin Solid Films 411(1), 12–16 (2002).
[CrossRef]

Other

H. A. Macleod, Thin Film Optical Filters (Taylor & Francis, 2001).

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Figures (8)

Fig. 1
Fig. 1

Schematic illustrations of OLEDs with (a) WAW, and (b) MgO/ZrO2/WAW structure and the schematic representations of the mechanism used for improving device outcoupling efficiency. Inset: The cross section transmission electron microscope (TEM) image of MgO nano-facet structure.

Fig. 2
Fig. 2

(a) Experimental values of refractive indices for Glass, MgO, ZrO2, and WO3. (b) Calculated transmittance values of ZrO2 and MgO as a function of thickness.

Fig. 3
Fig. 3

(a) Simulated contour plots of transmittance for WO3/Ag/WO3, and MgO/ZrO2/WO3/Ag/WO3 multilayers with respect to thickness variation of the upper WO3 and Ag layers.

Fig. 4
Fig. 4

(a) Transmittance of ITO, WAW, MgO/WAW, and MgO/ZrO2/WAW layers as a function of wavelength (b) Current density-voltage characteristics of blue OLEDs with ITO, WAW, MgO/WAW, and MgO/ZrO2/WAW. Inset: Schematic diagram of the blue OLEDs with the embedded graded index layer at the glass/WAW interface.

Fig. 5
Fig. 5

(a) Top-view SEM images of 400 nm thick MgO film on glass substrate. Inset: Schematic crystal structure of MgO (b) RMS and peak-to-valley roughness (RPV) values of MgO nano-facet structure as a function of thickness. Inset: AFM images of MgO nano facet structure (Scale bar: 500 nm).

Fig. 6
Fig. 6

(a) Current density-voltage and (b) luminance-current density characteristics of green OLEDs with MgO/ZrO2/WAW as a function of thickness of MgO.

Fig. 7
Fig. 7

(a) Normalized EL emission spectra and (b) relative luminance-current density characteristics of devices with Alq3:C545T, TCTA:Firpic, and TCTA:Fir6 using MgO/ZrO2/WAW(GIL/WAW) layers compared with devices using ITO layers. Inset: Photograph of operating OLEDs with MgO/ZrO2/WAW(top) and ITO (bottom) layers.

Fig. 8
Fig. 8

Luminance enhancement factors of devices using WAW, MgO/WAW, and MgO/ZrO2/WAW layers.

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