Abstract

Influence of electric field on the subnanosecond charge photogeneration dynamics in the polymer solar cell based on polyfluorene copolymer BisDMO-PFDTBT blended with PC61BM was examined with transient absorption spectroscopy. The charge dynamics showed no difference under short- or open-circuit conditions and under a forward bias of 0.79 V (1.6 × 105 V/cm), implying negligible field effects on the subnanosecond dynamics of charge photogeneration/recombination. However, under the reverse biases of −2 V (4.0 × 105 V/cm) and −5 V (1.0 × 106 V/cm), significant enhancement of charge photogeneration and apparent suppression of polaron pair recombination were observed, which agrees with the field-assisted enhancement of external quantum efficiency of the solar cell devices.

© 2013 OSA

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    [CrossRef]
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    [CrossRef] [PubMed]
  3. M. Tong, N. E. Coates, D. Moses, A. J. Heeger, “Charge carrier photogeneration and decay dynamics in the poly(2,7-carbazole) copolymer PCDTBT and in bulk heterojunction composites with PC70BM,” Phys. Rev. B 81(12), 125210 (2010).
    [CrossRef]
  4. N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
    [CrossRef] [PubMed]
  5. J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
    [CrossRef] [PubMed]
  6. J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
    [CrossRef] [PubMed]
  7. V. D. Mihailetchi, L. J. A. Koster, J. C. Hummelen, P. W. M. Blom, “Photocurrent generation in polymer-fullerene bulk heterojunctions,” Phys. Rev. Lett. 93(21), 216601 (2004).
    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
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  11. R. A. Marsh, J. M. Hodgkiss, R. H. Friend, “Direct measurement of electric field-assisted charge separation in polymer:fullerene photovoltaic diodes,” Adv. Mater. (Deerfield Beach Fla.) 22(33), 3672–3676 (2010).
    [CrossRef] [PubMed]
  12. F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
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  14. D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
    [CrossRef]
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  16. M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
    [CrossRef]
  17. F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
    [CrossRef] [PubMed]
  18. S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  20. M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
    [CrossRef]
  21. A. Pivrikas, N. S. Sariciftci, G. Juška, R. A. Österbacka, “A review of charge transport and recombination in polymer/fullerene organic solar cells,” Prog. Photovolt. Res. Appl. 15(8), 677–696 (2007).
    [CrossRef]
  22. R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
    [CrossRef] [PubMed]
  23. W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
    [CrossRef]
  24. K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
    [CrossRef] [PubMed]
  25. F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
    [CrossRef] [PubMed]
  26. J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
    [CrossRef] [PubMed]
  27. J. Nelson, “Diffusion-limited recombination in polymer-fullerene blends and its influence on photocurrent collection,” Phys. Rev. B 67(15), 155209 (2003).
    [CrossRef]
  28. J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
    [CrossRef] [PubMed]
  29. A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
    [CrossRef] [PubMed]
  30. F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
    [CrossRef]
  31. B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
    [CrossRef]
  32. R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
    [CrossRef]
  33. L. Onsager, “Deviations from Ohm's Law in weak electrolytes,” J. Chem. Phys. 2(9), 599–615 (1934).
    [CrossRef]
  34. V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
    [CrossRef] [PubMed]
  35. J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
    [CrossRef] [PubMed]
  36. W. J. Potscavage, S. Yoo, B. Kippelen, “Origin of the open-circuit voltage in multilayer heterojunction organic solar cells,” Appl. Phys. Lett. 93(19), 193308 (2008).
    [CrossRef]
  37. K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
    [CrossRef]
  38. E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
    [CrossRef]

2013 (1)

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

2012 (7)

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

2011 (2)

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
[CrossRef] [PubMed]

2010 (11)

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
[CrossRef] [PubMed]

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
[CrossRef] [PubMed]

R. A. Marsh, J. M. Hodgkiss, R. H. Friend, “Direct measurement of electric field-assisted charge separation in polymer:fullerene photovoltaic diodes,” Adv. Mater. (Deerfield Beach Fla.) 22(33), 3672–3676 (2010).
[CrossRef] [PubMed]

F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
[CrossRef]

T. M. Clarke, J. R. Durrant, “Charge photogeneration in organic solar cells,” Chem. Rev. 110(11), 6736–6767 (2010).
[CrossRef] [PubMed]

M. Tong, N. E. Coates, D. Moses, A. J. Heeger, “Charge carrier photogeneration and decay dynamics in the poly(2,7-carbazole) copolymer PCDTBT and in bulk heterojunction composites with PC70BM,” Phys. Rev. B 81(12), 125210 (2010).
[CrossRef]

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
[CrossRef] [PubMed]

2009 (3)

J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
[CrossRef] [PubMed]

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
[CrossRef] [PubMed]

2008 (2)

W. J. Potscavage, S. Yoo, B. Kippelen, “Origin of the open-circuit voltage in multilayer heterojunction organic solar cells,” Appl. Phys. Lett. 93(19), 193308 (2008).
[CrossRef]

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

2007 (3)

M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

A. Pivrikas, N. S. Sariciftci, G. Juška, R. A. Österbacka, “A review of charge transport and recombination in polymer/fullerene organic solar cells,” Prog. Photovolt. Res. Appl. 15(8), 677–696 (2007).
[CrossRef]

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

2006 (1)

V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
[CrossRef]

2005 (1)

T. Offermans, P. A. van Hal, S. C. J. Meskers, M. M. Koetse, R. A. J. Janssen, “Exciplex dynamics in a blend of π-conjugated polymers with electron donating and accepting properties: MDMO-PPV and PCNEPV,” Phys. Rev. B 72(4), 045213 (2005).
[CrossRef]

2004 (3)

V. D. Mihailetchi, L. J. A. Koster, J. C. Hummelen, P. W. M. Blom, “Photocurrent generation in polymer-fullerene bulk heterojunctions,” Phys. Rev. Lett. 93(21), 216601 (2004).
[CrossRef] [PubMed]

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
[CrossRef] [PubMed]

2003 (1)

J. Nelson, “Diffusion-limited recombination in polymer-fullerene blends and its influence on photocurrent collection,” Phys. Rev. B 67(15), 155209 (2003).
[CrossRef]

2002 (1)

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

2001 (1)

C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, “Plastic solar cells,” Adv. Funct. Mater. 11(1), 15–26 (2001).
[CrossRef]

1934 (1)

L. Onsager, “Deviations from Ohm's Law in weak electrolytes,” J. Chem. Phys. 2(9), 599–615 (1934).
[CrossRef]

Ade, H.

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

Agostinelli, T.

F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
[CrossRef]

Ai, X.-C.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Albert-Seifried, S.

R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
[CrossRef] [PubMed]

Albrecht, S.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Allard, S.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Andersson, M.

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

Andersson, M. R.

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

Asbury, J. B.

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

Azimi, H.

F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
[CrossRef]

Baek, N. S.

F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
[CrossRef] [PubMed]

Bahlke, M. E.

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Bakulin, A. A.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

Baldo, M. A.

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Banerji, N.

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

Bässler, H.

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Bavel, S. S.

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

Beenken, W. J. D.

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

Beljonne, D.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

Benten, H.

J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
[CrossRef] [PubMed]

Blakesley, J. C.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Blom, P. W. M.

V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
[CrossRef]

V. D. Mihailetchi, L. J. A. Koster, J. C. Hummelen, P. W. M. Blom, “Photocurrent generation in polymer-fullerene bulk heterojunctions,” Phys. Rev. Lett. 93(21), 216601 (2004).
[CrossRef] [PubMed]

Boschloo, G.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Bose, S.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Brabec, C. J.

C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, “Plastic solar cells,” Adv. Funct. Mater. 11(1), 15–26 (2001).
[CrossRef]

Brédas, J.-L.

J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
[CrossRef] [PubMed]

Carr, J. A.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Chaudhary, S.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Chen, L.-M.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Chen, M.-H.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Chen, Y.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Cho, D. M.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

Clarke, T. M.

T. M. Clarke, J. R. Durrant, “Charge photogeneration in organic solar cells,” Chem. Rev. 110(11), 6736–6767 (2010).
[CrossRef] [PubMed]

Coates, N. E.

M. Tong, N. E. Coates, D. Moses, A. J. Heeger, “Charge carrier photogeneration and decay dynamics in the poly(2,7-carbazole) copolymer PCDTBT and in bulk heterojunction composites with PC70BM,” Phys. Rev. B 81(12), 125210 (2010).
[CrossRef]

Collins, B. A.

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

Cordella, F.

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

Cornil, J.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
[CrossRef] [PubMed]

Coropceanu, V.

J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
[CrossRef] [PubMed]

Cowan, S.

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

De, S.

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

De Boer, B.

V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
[CrossRef]

Domingo, E. B.

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

Dumsch, I.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Durrant, J. R.

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
[CrossRef]

T. M. Clarke, J. R. Durrant, “Charge photogeneration in organic solar cells,” Chem. Rev. 110(11), 6736–6767 (2010).
[CrossRef] [PubMed]

Edvinsson, T.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Egelhaaf, H. J.

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

Etzold, F.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
[CrossRef] [PubMed]

Forler, N.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

Forster, M.

M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

Fostiropoulos, K.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Friend, R. H.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

R. A. Marsh, J. M. Hodgkiss, R. H. Friend, “Direct measurement of electric field-assisted charge separation in polymer:fullerene photovoltaic diodes,” Adv. Mater. (Deerfield Beach Fla.) 22(33), 3672–3676 (2010).
[CrossRef] [PubMed]

R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
[CrossRef] [PubMed]

A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
[CrossRef] [PubMed]

Fu, L.-M.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Ganapathysubramanian, B.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Gann, E.

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

Gao, J.

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

Gomez, E. D.

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

Goris, L.

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Guignard, L.

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

Gulbinas, V.

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Guo, C.

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

Guo, J.

J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
[CrossRef] [PubMed]

Hagfeldt, A.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Hansen, M. R.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

He, X.

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
[CrossRef]

Heeger, A. J.

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

M. Tong, N. E. Coates, D. Moses, A. J. Heeger, “Charge carrier photogeneration and decay dynamics in the poly(2,7-carbazole) copolymer PCDTBT and in bulk heterojunction composites with PC70BM,” Phys. Rev. B 81(12), 125210 (2010).
[CrossRef]

Heeney, M.

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

Hellström, S.

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

Hertel, D.

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Herz, L. M.

A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
[CrossRef] [PubMed]

Hodgkiss, J. M.

R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
[CrossRef] [PubMed]

R. A. Marsh, J. M. Hodgkiss, R. H. Friend, “Direct measurement of electric field-assisted charge separation in polymer:fullerene photovoltaic diodes,” Adv. Mater. (Deerfield Beach Fla.) 22(33), 3672–3676 (2010).
[CrossRef] [PubMed]

Hong, Z.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Hou, J.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Hou, J.-H.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Howard, I. A.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
[CrossRef] [PubMed]

Hu, R.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Hummelen, J. C.

V. D. Mihailetchi, L. J. A. Koster, J. C. Hummelen, P. W. M. Blom, “Photocurrent generation in polymer-fullerene bulk heterojunctions,” Phys. Rev. Lett. 93(21), 216601 (2004).
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S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
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J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
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J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
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F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
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F. C. Jamieson, T. Agostinelli, H. Azimi, J. Nelson, J. R. Durrant, “Field-independent charge photogeneration in PCPDTBT/PC70BM solar cells,” J. Phys. Chem. Lett. 1(23), 3306–3310 (2010).
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S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
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S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
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S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
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F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
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F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
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S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
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F. Etzold, I. A. Howard, R. Mauer, M. Meister, T.-D. Kim, K.-S. Lee, N. S. Baek, F. Laquai, “Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 133(24), 9469–9479 (2011).
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D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
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V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
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F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
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S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
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J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
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J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
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S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
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R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

Petrich, J. W.

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

Pivrikas, A.

A. Pivrikas, N. S. Sariciftci, G. Juška, R. A. Österbacka, “A review of charge transport and recombination in polymer/fullerene organic solar cells,” Prog. Photovolt. Res. Appl. 15(8), 677–696 (2007).
[CrossRef]

Potscavage, W. J.

W. J. Potscavage, S. Yoo, B. Kippelen, “Origin of the open-circuit voltage in multilayer heterojunction organic solar cells,” Appl. Phys. Lett. 93(19), 193308 (2008).
[CrossRef]

Pshenichnikov, M. S.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

Pullerits, T.

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

Rao, A.

A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

Rensmo, H.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Roy-Mayhew, J. D.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Sariciftci, N. S.

A. Pivrikas, N. S. Sariciftci, G. Juška, R. A. Österbacka, “A review of charge transport and recombination in polymer/fullerene organic solar cells,” Prog. Photovolt. Res. Appl. 15(8), 677–696 (2007).
[CrossRef]

C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, “Plastic solar cells,” Adv. Funct. Mater. 11(1), 15–26 (2001).
[CrossRef]

Scharber, M.

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

Scherf, U.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
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M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

Schindler, W.

S. Albrecht, W. Schindler, J. Kurpiers, J. Kniepert, J. C. Blakesley, I. Dumsch, S. Allard, K. Fostiropoulos, U. Scherf, D. Neher, “On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives,” J. Phys. Chem. Lett. 3(5), 640–645 (2012).
[CrossRef]

Shu, J.

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
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A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
[CrossRef] [PubMed]

Sista, S.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Sreearunothai, P.

A. C. Morteani, P. Sreearunothai, L. M. Herz, R. H. Friend, C. Silva, “Exciton regeneration at polymeric semiconductor heterojunctions,” Phys. Rev. Lett. 92(24), 247402 (2004).
[CrossRef] [PubMed]

Stingelin, N.

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

Sundström, V.

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Sweelssen, J.

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

Toffanin, S.

M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

Tong, M.

M. Tong, N. E. Coates, D. Moses, A. J. Heeger, “Charge carrier photogeneration and decay dynamics in the poly(2,7-carbazole) copolymer PCDTBT and in bulk heterojunction composites with PC70BM,” Phys. Rev. B 81(12), 125210 (2010).
[CrossRef]

Unger, E. L.

E. L. Unger, T. Edvinsson, J. D. Roy-Mayhew, H. Rensmo, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, “Excitation energy dependent charge separation at hole-transporting dye/TiO2 hetero interface,” J. Phys. Chem. C 116(40), 21148–21156 (2012).
[CrossRef]

Vakhshouri, K.

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

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T. Offermans, P. A. van Hal, S. C. J. Meskers, M. M. Koetse, R. A. J. Janssen, “Exciplex dynamics in a blend of π-conjugated polymers with electron donating and accepting properties: MDMO-PPV and PCNEPV,” Phys. Rev. B 72(4), 045213 (2005).
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A. A. Bakulin, A. Rao, V. G. Pavelyev, P. H. M. van Loosdrecht, M. S. Pshenichnikov, D. Niedzialek, J. Cornil, D. Beljonne, R. H. Friend, “The role of driving energy and delocalized States for charge separation in organic semiconductors,” Science 335(6074), 1340–1344 (2012).
[CrossRef] [PubMed]

Vandewal, K.

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Vauthey, E.

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

Veenstra, S. C.

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

Veldman, D.

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

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J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Wang, Y.-W.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Xie, H. X.

V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
[CrossRef]

Yang, G.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Yang, Y.

M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Yartsev, A.

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Yokoya, S.

J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
[CrossRef] [PubMed]

Yoo, S.

W. J. Potscavage, S. Yoo, B. Kippelen, “Origin of the open-circuit voltage in multilayer heterojunction organic solar cells,” Appl. Phys. Lett. 93(19), 193308 (2008).
[CrossRef]

Yost, S. R.

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

Zaushitsyn, Y.

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

V. Gulbinas, Y. Zaushitsyn, V. Sundström, D. Hertel, H. Bässler, A. Yartsev, “Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity,” Phys. Rev. Lett. 89(10), 107401 (2002).
[CrossRef] [PubMed]

Zhang, F.

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

Zhang, J.-P.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

Zhang, W.

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
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Acc. Chem. Res. (1)

J.-L. Brédas, J. E. Norton, J. Cornil, V. Coropceanu, “Molecular understanding of organic solar cells: the challenges,” Acc. Chem. Res. 42(11), 1691–1699 (2009).
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Adv. Energy Mater. (1)

D. Jarzab, F. Cordella, J. Gao, M. Scharber, H. J. Egelhaaf, M. A. Loi, “Low-temperature behaviour of charge transfer excitons in narrow-bandgap polymer-based bulk heterojunctions,” Adv. Energy Mater. 1(4), 604–609 (2011).
[CrossRef]

Adv. Funct. Mater. (3)

M. A. Loi, S. Toffanin, M. Muccini, M. Forster, U. Scherf, M. Scharber, “Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative,” Adv. Funct. Mater. 17(13), 2111–2116 (2007).
[CrossRef]

C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, “Plastic solar cells,” Adv. Funct. Mater. 11(1), 15–26 (2001).
[CrossRef]

V. D. Mihailetchi, H. X. Xie, B. De Boer, L. J. A. Koster, P. W. M. Blom, “Charge transport and photocurrent generation in poly(3-hexylthiophene): methanofullerene bulk-heterojunction solar cells,” Adv. Funct. Mater. 16(5), 699–708 (2006).
[CrossRef]

Adv. Mater. (Deerfield Beach Fla.) (2)

R. A. Marsh, J. M. Hodgkiss, R. H. Friend, “Direct measurement of electric field-assisted charge separation in polymer:fullerene photovoltaic diodes,” Adv. Mater. (Deerfield Beach Fla.) 22(33), 3672–3676 (2010).
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M.-H. Chen, J. Hou, Z. Hong, G. Yang, S. Sista, L.-M. Chen, Y. Yang, “Efficient polymer solar cells with thin active layers based on alternating polyfluorene copolymer/fullerene bulk heterojunctions,” Adv. Mater. (Deerfield Beach Fla.) 21(42), 4238–4242 (2009).
[CrossRef]

Appl. Phys. Lett. (1)

W. J. Potscavage, S. Yoo, B. Kippelen, “Origin of the open-circuit voltage in multilayer heterojunction organic solar cells,” Appl. Phys. Lett. 93(19), 193308 (2008).
[CrossRef]

Chem. Rev. (1)

T. M. Clarke, J. R. Durrant, “Charge photogeneration in organic solar cells,” Chem. Rev. 110(11), 6736–6767 (2010).
[CrossRef] [PubMed]

Chem. Sci. (1)

F. C. Jamieson, E. B. Domingo, T. McCarthy-Ward, M. Heeney, N. Stingelin, J. R. Durrant, “Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells,” Chem. Sci. 3(2), 485–492 (2012).
[CrossRef]

Energy Environ. Sci. (1)

K. S. Nalwa, J. A. Carr, R. C. Mahadevapuram, H. K. Kodali, S. Bose, Y. Chen, J. W. Petrich, B. Ganapathysubramanian, S. Chaudhary, “Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles,” Energy Environ. Sci. 5(5), 7042–7049 (2012).
[CrossRef]

J. Am. Chem. Soc. (10)

J. Guo, H. Ohkita, S. Yokoya, H. Benten, S. Ito, “Bimodal polarons and hole transport in poly(3-hexylthiophene):fullerene blend films,” J. Am. Chem. Soc. 132(28), 9631–9637 (2010).
[CrossRef] [PubMed]

D. Veldman, Ö. İpek, S. C. J. Meskers, J. Sweelssen, M. M. Koetse, S. C. Veenstra, J. M. Kroon, S. S. Bavel, J. Loos, R. A. J. Janssen, “Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 130(24), 7721–7735 (2008).
[CrossRef] [PubMed]

F. Etzold, I. A. Howard, N. Forler, D. M. Cho, M. Meister, H. Mangold, J. Shu, M. R. Hansen, K. Müllen, F. Laquai, “The effect of solvent additives on morphology and excited-state dynamics in PCPDTBT:PCBM photovoltaic blends,” J. Am. Chem. Soc. 134(25), 10569–10583 (2012).
[CrossRef] [PubMed]

J. Lee, K. Vandewal, S. R. Yost, M. E. Bahlke, L. Goris, M. A. Baldo, J. V. Manca, T. V. Voorhis, “Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells,” J. Am. Chem. Soc. 132(34), 11878–11880 (2010).
[CrossRef] [PubMed]

N. Banerji, S. Cowan, M. Leclerc, E. Vauthey, A. J. Heeger, “Exciton formation, relaxation, and decay in PCDTBT,” J. Am. Chem. Soc. 132(49), 17459–17470 (2010).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Near-IR femtosecond transient absorption spectroscopy of ultrafast polaron and triplet exciton formation in polythiophene films with different regioregularities,” J. Am. Chem. Soc. 131(46), 16869–16880 (2009).
[CrossRef] [PubMed]

J. Guo, H. Ohkita, H. Benten, S. Ito, “Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies,” J. Am. Chem. Soc. 132(17), 6154–6164 (2010).
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[CrossRef] [PubMed]

S. De, T. Pascher, M. Maiti, K. G. Jespersen, T. Kesti, F. Zhang, O. Inganäs, A. Yartsev, V. Sundström, “Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends,” J. Am. Chem. Soc. 129(27), 8466–8472 (2007).
[CrossRef] [PubMed]

S. K. Pal, T. Kesti, M. Maiti, F. Zhang, O. Inganäs, S. Hellström, M. R. Andersson, F. Oswald, F. Langa, T. Österman, T. Pascher, A. Yartsev, V. Sundström, “Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function,” J. Am. Chem. Soc. 132(35), 12440–12451 (2010).
[CrossRef] [PubMed]

J. Chem. Phys. (2)

K. G. Jespersen, W. J. D. Beenken, Y. Zaushitsyn, A. Yartsev, M. Andersson, T. Pullerits, V. Sundström, “The electronic states of polyfluorene copolymers with alternating donor-acceptor units,” J. Chem. Phys. 121(24), 12613–12617 (2004).
[CrossRef] [PubMed]

L. Onsager, “Deviations from Ohm's Law in weak electrolytes,” J. Chem. Phys. 2(9), 599–615 (1934).
[CrossRef]

J. Phys. Chem. C (3)

R. D. Pensack, C. Guo, K. Vakhshouri, E. D. Gomez, J. B. Asbury, “Influence of acceptor structure on barriers to charge separation in organic photovoltaic materials,” J. Phys. Chem. C 116(7), 4824–4831 (2012).
[CrossRef]

W. Zhang, Y.-W. Wang, R. Hu, L.-M. Fu, X.-C. Ai, J.-P. Zhang, J.-H. Hou, “Mechanism of primary charge photogeneration in polyfluorene copolymer/fullerene blends and influence of the donor/acceptor lowest unoccupied molecular orbital level offset,” J. Phys. Chem. C 117(2), 735–749 (2013).
[CrossRef]

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J. Phys. Chem. Lett. (3)

B. A. Collins, E. Gann, L. Guignard, X. He, C. R. McNeill, H. Ade, “Molecular miscibility of polymer−fullerene blends,” J. Phys. Chem. Lett. 1(21), 3160–3166 (2010).
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[CrossRef]

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Nano Lett. (1)

R. A. Marsh, J. M. Hodgkiss, S. Albert-Seifried, R. H. Friend, “Effect of annealing on P3HT:PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy,” Nano Lett. 10(3), 923–930 (2010).
[CrossRef] [PubMed]

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Science (1)

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[CrossRef] [PubMed]

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Figures (4)

Fig. 1
Fig. 1

(a) UV-visible absorption spectra of the BisDMO-PFDTBT/PC61BM (1:3) photoactive layer in real solar cell device (thicker solid), the neat films of BisDMO-PFDTBT (thinner solid) and PC61BM (dashed). Insets are the molecular structures. Arrow points to the excitation wavelength for time-resolved measurements (610 nm). (b) Typical current-voltage (I-V) curve of the solar cells determined under AM 1.5 G illumination (▾) and in dark (◼).

Fig. 2
Fig. 2

Representative time-resolved spectra for the BisDMO-PFDTBT/PC61BM solar cell at indicated bias potentials and delay times. Excitation wavelength was 610 nm (~1.0 × 1013 photons·cm−2·pulse−1). The depleted sections around 1200 nm are due to the interference from the second order diffraction of the excitation pulses.

Fig. 3
Fig. 3

Time-evolution profiles probed at (a) 970 nm and (b) 1050 nm for the BisDMO-PFDTBT/PC61BM solar cell at indicated bias potentials (cf Fig. 2. Normalized to the amplitudes maxima at 0.13 ps). Solid lines were obtained by global fitting of the kinetics to the model function ΔOD= A 1 t α 1 + A 2 t α 2 , see text for details).

Fig. 4
Fig. 4

The EQE curves of the BisDMO-PFDTBT/PC61BM device (1:3, w/w) determined under short circuit (0 V) and at the forwards (Vf) and the reverse (Vr) biases.

Tables (1)

Tables Icon

Table 1 Power-law exponents (α) obtained by global fitting of the 970 nm and the 1050 nm kinetics under individual bias voltages (cf Fig. 3).

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