Abstract

Microstructured porous zinc oxide (ZnO) thin film was developed and demonstrated as an electron selective layer for enhancing light scattering and efficiency in inverted organic photovoltaics. High degree of porosity was induced and controlled in the ZnO layer by incorporation of polyethylene glycol (PEG) organic template. Scanning electron microscopy, contact angle and absorption measurements prove that the ZnO:PEG ratio of 4:1 is optimal for the best performance of porous ZnO. Ensuring sufficient pore-filling, the use of porous ZnO leads to a marked improvement in device performance compared to non-porous ZnO, with 35% increase in current density and 30% increase in efficiency. Haze factor studies indicate that the performance improvement can be primarily attributed to the improved light scattering enabled by such a highly porous structure.

© 2014 Optical Society of America

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  23. Y.-M. Chang and C.-Y. Leu, “Solvent extraction induced nano-porous zinc oxide as an electron transport layer for inverted polymer solar cells,” Org. Electron. 13(12), 2991–2996 (2012).
    [CrossRef]
  24. Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
    [CrossRef]

2012 (2)

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Y.-M. Chang and C.-Y. Leu, “Solvent extraction induced nano-porous zinc oxide as an electron transport layer for inverted polymer solar cells,” Org. Electron. 13(12), 2991–2996 (2012).
[CrossRef]

2011 (5)

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

J. D. Servaites, M. A. Ratner, and T. J. Marks, “Organic solar cells: A new look at traditional models,” Energy & Environmental Science 4(11), 4410–4422 (2011).
[CrossRef]

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

2010 (4)

A. J. Heeger, “Semiconducting polymers: the Third Generation,” Chem. Soc. Rev. 39(7), 2354–2371 (2010).
[CrossRef] [PubMed]

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

J. Bouclé, H. J. Snaith, and N. C. Greenham, “Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals,” J. Phys. Chem. C 114(8), 3664–3674 (2010).
[CrossRef]

2009 (2)

Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
[CrossRef]

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

2008 (4)

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

K. Takanezawa, K. Tajima, and K. Hashimoto, “Efficiency enhancement of polymer photovoltaic devices hybridized with ZnO nanorod arrays by the introduction of a vanadium oxide buffer layer,” Appl. Phys. Lett. 93(6), 063308 (2008).
[CrossRef]

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

2007 (2)

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

2006 (1)

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

2005 (2)

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

S. R. Forrest, “The limits to organic photovoltaic cell efficiency,” MRS Bull. 30(01), 28–32 (2005).
[CrossRef]

1986 (1)

C. W. Tang, “Two-layer organic photovoltaic cell,” Appl. Phys. Lett. 48(2), 183–185 (1986).
[CrossRef]

Beaupre, S.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Bejbouji, H.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Berry, J. J.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Bouclé, J.

J. Bouclé, H. J. Snaith, and N. C. Greenham, “Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals,” J. Phys. Chem. C 114(8), 3664–3674 (2010).
[CrossRef]

Brett, M. J.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Buriak, J. M.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Cao, Y.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Chang, Y.-M.

Y.-M. Chang and C.-Y. Leu, “Solvent extraction induced nano-porous zinc oxide as an electron transport layer for inverted polymer solar cells,” Org. Electron. 13(12), 2991–2996 (2012).
[CrossRef]

Chao, C. H.

Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
[CrossRef]

Chen, C. P.

Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
[CrossRef]

Chesin, J. P.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Cho, K.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Cho, S.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Choi, Y. S.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Coates, N.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Dang, M. T.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Dautel, O. J.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Emery, K.

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Feng, W.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Forrest, S. R.

S. R. Forrest, “The limits to organic photovoltaic cell efficiency,” MRS Bull. 30(01), 28–32 (2005).
[CrossRef]

Fujii, A. H.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Gang, L.

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Ginley, D. S.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Greenham, N. C.

J. Bouclé, H. J. Snaith, and N. C. Greenham, “Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals,” J. Phys. Chem. C 114(8), 3664–3674 (2010).
[CrossRef]

Harris, K. D.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Hashimoto, K.

K. Takanezawa, K. Tajima, and K. Hashimoto, “Efficiency enhancement of polymer photovoltaic devices hybridized with ZnO nanorod arrays by the introduction of a vanadium oxide buffer layer,” Appl. Phys. Lett. 93(6), 063308 (2008).
[CrossRef]

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

He, Z.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Heeger, A. J.

A. J. Heeger, “Semiconducting polymers: the Third Generation,” Chem. Soc. Rev. 39(7), 2354–2371 (2010).
[CrossRef] [PubMed]

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Hirota, K.

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

Hirsch, L.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Hori, T. S.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Hou, J.

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

Hsiao, Y. S.

Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
[CrossRef]

Hsu, J. W. P.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Hu, Z. Y.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Ihn, S.-G.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Jiang, C. Y.

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Jin, Z. G.

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

Jo, S. B.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Ju, X. H.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Ke, L.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

Kim, M.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Kim, Y.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Kopidakis, N.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Krause, K. M.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Kwong, D. L.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Kyaw, A. K. K.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Lalany, A.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Leclerc, M.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Lee, J. H.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Lee, K.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Leu, C.-Y.

Y.-M. Chang and C.-Y. Leu, “Solvent extraction induced nano-porous zinc oxide as an electron transport layer for inverted polymer solar cells,” Org. Electron. 13(12), 2991–2996 (2012).
[CrossRef]

Li, G.

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

Li, W.

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

Li, Y. N.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Liu, Y.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Liu, Z. F.

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

Lo, G. Q.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Marks, T. J.

J. D. Servaites, M. A. Ratner, and T. J. Marks, “Organic solar cells: A new look at traditional models,” Energy & Environmental Science 4(11), 4410–4422 (2011).
[CrossRef]

Miedaner, A.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Moon, J. S.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Moriarty, T.

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Moses, D.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Olson, D. C.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Ozaki, M. N.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Park, J. H.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Park, S. H.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Qiu, J. J.

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

Ratner, M. A.

J. D. Servaites, M. A. Ratner, and T. J. Marks, “Organic solar cells: A new look at traditional models,” Energy & Environmental Science 4(11), 4410–4422 (2011).
[CrossRef]

Rider, D. A.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Roy, A.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Servaites, J. D.

J. D. Servaites, M. A. Ratner, and T. J. Marks, “Organic solar cells: A new look at traditional models,” Energy & Environmental Science 4(11), 4410–4422 (2011).
[CrossRef]

Shaheen, S. E.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Shrotriya, V.

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Sim, M.

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Snaith, H. J.

J. Bouclé, H. J. Snaith, and N. C. Greenham, “Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals,” J. Phys. Chem. C 114(8), 3664–3674 (2010).
[CrossRef]

Steirer, K. X.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Su, S.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Sun, X. W.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Tajima, K.

K. Takanezawa, K. Tajima, and K. Hashimoto, “Efficiency enhancement of polymer photovoltaic devices hybridized with ZnO nanorod arrays by the introduction of a vanadium oxide buffer layer,” Appl. Phys. Lett. 93(6), 063308 (2008).
[CrossRef]

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

Takanezawa, K.

K. Takanezawa, K. Tajima, and K. Hashimoto, “Efficiency enhancement of polymer photovoltaic devices hybridized with ZnO nanorod arrays by the introduction of a vanadium oxide buffer layer,” Appl. Phys. Lett. 93(6), 063308 (2008).
[CrossRef]

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

Tang, C. W.

C. W. Tang, “Two-layer organic photovoltaic cell,” Appl. Phys. Lett. 48(2), 183–185 (1986).
[CrossRef]

Tucker, R. T.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Urien, M.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Varutt, K. C.

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

Vignau, L.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Voigt, J. A.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Wantz, G.

M. T. Dang, G. Wantz, H. Bejbouji, M. Urien, O. J. Dautel, L. Vignau, and L. Hirsch, “Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent,” Sol. Energy Mater. Sol. Cells 95(12), 3408–3418 (2011).
[CrossRef]

Wei, Q. S.

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

Whang, W. T.

Y. S. Hsiao, C. P. Chen, C. H. Chao, and W. T. Whang, “All-solution-processed inverted polymer solar cells on granular surface-nickelized polyimide,” Org. Electron. 10(4), 551–561 (2009).
[CrossRef]

White, M. S.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Widjonarko, N. E.

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Worfolk, B. J.

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Wu, H.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Xu, M.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Xu, Z.

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

Yan, Y.

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Yang, Y.

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Yao, Y.

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

Yun-Ju, L.

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

Zhang, J. J.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Zhang, X. D.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Zhao, D. W.

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

Zhao, Y.

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Zhong, C.

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Adv. Funct. Mater. (2)

V. Shrotriya, L. Gang, Y. Yan, T. Moriarty, K. Emery, and Y. Yang, “Accurate measurement and characterization of organic solar cells,” Adv. Funct. Mater. 16(15), 2016–2023 (2006).
[CrossRef]

Y. Yao, J. Hou, Z. Xu, G. Li, and Y. Yang, “Effects of solvent mixtures on the nanoscale phase separation in polymer solar cells,” Adv. Funct. Mater. 18(12), 1783–1789 (2008).
[CrossRef]

Advanced Energy Materials (1)

S. B. Jo, J. H. Lee, M. Sim, M. Kim, J. H. Park, Y. S. Choi, Y. Kim, S.-G. Ihn, and K. Cho, “High performance organic photovoltaic cells using polymer-hybridized ZnO nanocrystals as a cathode interlayer,” Advanced Energy Materials 1(4), 690–698 (2011).
[CrossRef]

Appl. Phys. Lett. (4)

X. W. Sun, D. W. Zhao, L. Ke, A. K. K. Kyaw, G. Q. Lo, and D. L. Kwong, “Inverted tandem organic solar cells with a MoO3/Ag/Al/Ca intermediate layer,” Appl. Phys. Lett. 97(5), 053303 (2010).
[CrossRef]

C. W. Tang, “Two-layer organic photovoltaic cell,” Appl. Phys. Lett. 48(2), 183–185 (1986).
[CrossRef]

A. K. K. Kyaw, X. W. Sun, C. Y. Jiang, G. Q. Lo, D. W. Zhao, and D. L. Kwong, “An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer,” Appl. Phys. Lett. 93(22), 221107 (2008).
[CrossRef]

K. Takanezawa, K. Tajima, and K. Hashimoto, “Efficiency enhancement of polymer photovoltaic devices hybridized with ZnO nanorod arrays by the introduction of a vanadium oxide buffer layer,” Appl. Phys. Lett. 93(6), 063308 (2008).
[CrossRef]

Chem. Soc. Rev. (1)

A. J. Heeger, “Semiconducting polymers: the Third Generation,” Chem. Soc. Rev. 39(7), 2354–2371 (2010).
[CrossRef] [PubMed]

Energy & Environmental Science (1)

J. D. Servaites, M. A. Ratner, and T. J. Marks, “Organic solar cells: A new look at traditional models,” Energy & Environmental Science 4(11), 4410–4422 (2011).
[CrossRef]

J. Phys. Chem. C (3)

D. C. Olson, L. Yun-Ju, M. S. White, N. Kopidakis, S. E. Shaheen, D. S. Ginley, J. A. Voigt, and J. W. P. Hsu, “Effect of polymer processing on the performance of poly(3-hexylthiophene)/ZnO nanorod photovoltaic devices,” J. Phys. Chem. C 111(44), 16640–16645 (2007).
[CrossRef]

K. Takanezawa, K. Hirota, Q. S. Wei, K. Tajima, and K. Hashimoto, “Efficient charge collection with ZnO nanorod array in hybrid photovoltaic devices,” J. Phys. Chem. C 111(19), 7218–7223 (2007).
[CrossRef]

J. Bouclé, H. J. Snaith, and N. C. Greenham, “Simple Approach to Hybrid Polymer/Porous Metal Oxide Solar Cells from Solution-Processed ZnO Nanocrystals,” J. Phys. Chem. C 114(8), 3664–3674 (2010).
[CrossRef]

Mater. Lett. (1)

Z. F. Liu, Z. G. Jin, W. Li, and J. J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Mater. Lett. 59(28), 3620–3625 (2005).
[CrossRef]

MRS Bull. (1)

S. R. Forrest, “The limits to organic photovoltaic cell efficiency,” MRS Bull. 30(01), 28–32 (2005).
[CrossRef]

Nanotechnology (2)

X. H. Ju, W. Feng, K. C. Varutt, T. S. Hori, A. H. Fujii, and M. N. Ozaki, “Fabrication of oriented ZnO nanopillar self-assemblies and their application for photovoltaic devices,” Nanotechnology 19(43), 435706 (2008).
[CrossRef] [PubMed]

D. A. Rider, R. T. Tucker, B. J. Worfolk, K. M. Krause, A. Lalany, M. J. Brett, J. M. Buriak, and K. D. Harris, “Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells,” Nanotechnology 22(8), 085706 (2011).
[CrossRef] [PubMed]

Nat. Photonics (2)

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009).
[CrossRef]

Z. He, C. Zhong, S. Su, M. Xu, H. Wu, and Y. Cao, “Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure,” Nat. Photonics 6(9), 593–595 (2012).
[CrossRef]

Org. Electron. (3)

K. X. Steirer, J. P. Chesin, N. E. Widjonarko, J. J. Berry, A. Miedaner, D. S. Ginley, and D. C. Olson, “Solution deposited NiO thin-films as hole transport layers in organic photovoltaics,” Org. Electron. 11(8), 1414–1418 (2010).
[CrossRef]

Y.-M. Chang and C.-Y. Leu, “Solvent extraction induced nano-porous zinc oxide as an electron transport layer for inverted polymer solar cells,” Org. Electron. 13(12), 2991–2996 (2012).
[CrossRef]

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[CrossRef]

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[CrossRef]

Synth. Met. (1)

Z. Y. Hu, J. J. Zhang, Y. Liu, Y. N. Li, X. D. Zhang, and Y. Zhao, “Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates,” Synth. Met. 161(19-20), 2174–2178 (2011).
[CrossRef]

Other (1)

“ http://www.heliatek.com/ ”, retrieved.

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Figures (7)

Fig. 1
Fig. 1

Schematic representation of OPV devices with (a) a non-porous ZnO layer and (b) a highly porous ZnO layer, along with respective SEM images showing the porous and non-porous ZnO layer in the respective devices (scale bars: 20µm).

Fig. 2
Fig. 2

Current density-voltage (J-V) characteristics of OPVs with (a) porous ZnO layer and (b)non-porous ZnO layer, with the active layer coated at different spinning speeds (reference spin-coating speed: 2000 rpm; slow spin-coating speed: 800-1000 rpm).

Fig. 3
Fig. 3

SEM images of porous ZnO layer with the ZnO:PEG ratio of (a) 3:1 (b) 4:1 and (c) 5:1.

Fig. 4
Fig. 4

(a) Current density-voltage (J-V) characteristics of OPVs employing porous ZnO layer with different ZnO:PEG ratios and non-porous reference cell (b) efficiency trend for the cells with different PEG ratios and non-porous reference cell extracted from 24 devices. The horizontal lines in the box denote the 25th, 50th and 75th percentile values while the error bars denote the 5th and 95th percentile values.

Fig. 5
Fig. 5

IPCE spectra of OPVs employing ZnO layer with different ZnO:PEG ratios and non-porous reference cell.

Fig. 6
Fig. 6

Absorption spectra of the active layer deposited on porous ZnO layer with different ZnO:PEG ratios and on non-porous ZnO layer. A slow spin speed of 800-1000 rpm is used for porous ZnO whereas spin speed of 2000 rpm is used for non-porous ZnO.

Fig. 7
Fig. 7

(a) Total transmission (inset: diffused transmission) spectra and (b) the haze factor of the porous ZnO layer using different ZnO:PEG ratios and non-porous ZnO (reference).

Tables (3)

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Table 1 Device parameters of porous and non-porous ZnO OPV with the active layer spin-coated at different spinning speeds (reference spin-coating speed: 2000 rpm; slow spin-coating speed: 800-1000 rpm)

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Table 2 Device parameters of the best porous ZnO OPV with different ZnO:PEG ratios and their non-porous reference device fabricated

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Table 3 Contact angle measurements of the ZnO layer in different ZnO:PEG ratios

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