Abstract

We demonstrate a novel light trapping configuration based on an array of micro lenses in conjunction with a self aligned array of micro apertures located in a highly reflecting mirror. When locating the light trapping element, that displays strong directional asymmetric transmission, in front of thin film organic photovoltaic cells, an increase in cell absorption is obtained. By recycling reflected photons that otherwise would be lost, thinner films with more beneficial electrical properties can effectively be deployed. The light trapping element enhances the absorption rate of the solar cell and increases the photocurrent by as much as 25%.

© 2008 Optical Society of America

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  1. S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
    [CrossRef] [PubMed]
  2. K. M. Coakley and M. D. McGehee, "Conjugated polymer photovoltaic cells," Chem. Mat. 16, 4533-4542 (2004).
    [CrossRef]
  3. J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
    [CrossRef]
  4. J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).
  5. K. Tvingstedt, M. Tormen, L. Businaro, and O. Inganäs, "Light confinement in thin film organic photovoltaic cells," Proc. SPIE 6197 61970C 1-10 (2006).
  6. L. S. Roman et al. "Trapping light in polymer photodiodes with soft embossed gratings," Adv. Materials 12, 189-195 (2000).
    [CrossRef]
  7. M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
    [CrossRef]
  8. P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
    [CrossRef]
  9. M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
    [CrossRef]
  10. K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
    [CrossRef]
  11. S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
    [CrossRef]
  12. R. B. Johnson and G. A. Jacobsen, "Advances in lenticular lens arrays for visual display," Proceedings of SPIE 5874 587406 1-11 (2005).
    [CrossRef]
  13. F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
    [CrossRef]
  14. M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
    [CrossRef]

2008 (1)

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

2007 (4)

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
[CrossRef] [PubMed]

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

2006 (1)

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

2005 (1)

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

2004 (2)

K. M. Coakley and M. D. McGehee, "Conjugated polymer photovoltaic cells," Chem. Mat. 16, 4533-4542 (2004).
[CrossRef]

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

2000 (2)

P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
[CrossRef]

L. S. Roman et al. "Trapping light in polymer photodiodes with soft embossed gratings," Adv. Materials 12, 189-195 (2000).
[CrossRef]

1996 (1)

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Altermatt, P. P.

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Andersson, M. R.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Andersson, V.

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

Barrau, S.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Bijleveld, J.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Bulovic, V.

P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
[CrossRef]

Carpentiero, A.

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Coakley, K. M.

K. M. Coakley and M. D. McGehee, "Conjugated polymer photovoltaic cells," Chem. Mat. 16, 4533-4542 (2004).
[CrossRef]

Cojoc, D.

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Fabrizio, E.

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Ferrari, E.

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Forrest, S. R.

P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
[CrossRef]

Glatthaar, M.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Gombert, A.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Green, M. A.

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Gunes, S.

S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
[CrossRef] [PubMed]

Hinsch, A.

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Inganas, O.

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

Inganäs, O.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Lewer, P.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

McGehee, M. D.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

K. M. Coakley and M. D. McGehee, "Conjugated polymer photovoltaic cells," Chem. Mat. 16, 4533-4542 (2004).
[CrossRef]

Muller, C.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

Muller, J.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Neugebauer, H.

S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
[CrossRef] [PubMed]

Niggemann, M.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Perzon, E.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Peumans, P.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
[CrossRef]

Rech, B.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Reetz, W.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Rim, S. B.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

Roman, L. S.

L. S. Roman et al. "Trapping light in polymer photodiodes with soft embossed gratings," Adv. Materials 12, 189-195 (2000).
[CrossRef]

Sariciftci, N. S.

S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
[CrossRef] [PubMed]

Scully, S. R.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

Springer, J.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Tormen, M.

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Tvingstedt, K.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

Vanecek, M.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Wagner, J.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

Wang, A. H.

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Wenham, S. R.

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Wittwer, V.

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Zhang, F.

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

Zhao, J. H.

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Zhao, S.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

Adv. Materials (1)

L. S. Roman et al. "Trapping light in polymer photodiodes with soft embossed gratings," Adv. Materials 12, 189-195 (2000).
[CrossRef]

Appl. Phys. Lett. (3)

P. Peumans, V. Bulovic, and S. R. Forrest, "Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes," Appl. Phys. Lett. 76, 2650-2652 (2000).
[CrossRef]

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, "Folded reflective tandem polymer solar cell doubles efficiency," Appl. Phys. Lett. 91, 123514-1-123514-3 (2007).
[CrossRef]

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, "An effective light trapping configuration for thin-film solar cells," Appl. Phys. Lett. 91, 243501-1-243501-3 (2007).
[CrossRef]

Chem. Mat. (1)

K. M. Coakley and M. D. McGehee, "Conjugated polymer photovoltaic cells," Chem. Mat. 16, 4533-4542 (2004).
[CrossRef]

Chem. Rev. (1)

S. Gunes, H. Neugebauer, and N. S. Sariciftci, "Conjugated polymer-based organic solar cells," Chem. Rev. 107, 1324-1338 (2007).
[CrossRef] [PubMed]

J. Mat. Chem. (1)

F. Zhang, J. Bijleveld, E. Perzon, K. Tvingstedt, S. Barrau, O. Inganäs, and M. R. Andersson, "High photovoltage achieved in low band gap polymer solar cells by aligning energy levels of polymer with the LUMOs of fullerene derivatives," J. Mat. Chem. 185468-5474 (2008).
[CrossRef]

Nanotech. (1)

M. Tormen, A. Carpentiero, E. Ferrari, D. Cojoc, and E. Fabrizio, "Novel fabrication method for three-dimensional nanostructuring: an application to micro-optics," Nanotech. 18, 385301 1-4 (2007).
[CrossRef]

Sol Energy Mat Sol Cells (1)

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, "Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates," Sol Energy Mat Sol Cells 85, 1-11 (2005).

Sol. Energy Mat. Sol. Cells (1)

J. H. Zhao, A. H. Wang, P. P. Altermatt, S. R. Wenham, and M. A. Green, "24% efficient PERL silicon solar cell: Recent improvements in high efficiency silicon cell research," Sol. Energy Mat. Sol. Cells 41-2, 87-99 (1996).
[CrossRef]

Thin Solid Films (2)

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, "Functional microprism substrate for organic solar cells," Thin Solid Films 511, 628-633 (2006).
[CrossRef]

M. Niggemann, M. Glatthaar, A. Gombert, A. Hinsch, and V. Wittwer, "Diffraction gratings and buried nano-electrodes - architectures for organic solar cells," Thin Solid Films 451-52, 619-623 (2004).
[CrossRef]

Other (2)

K. Tvingstedt, M. Tormen, L. Businaro, and O. Inganäs, "Light confinement in thin film organic photovoltaic cells," Proc. SPIE 6197 61970C 1-10 (2006).

R. B. Johnson and G. A. Jacobsen, "Advances in lenticular lens arrays for visual display," Proceedings of SPIE 5874 587406 1-11 (2005).
[CrossRef]

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Figures (6)

Fig. 1.
Fig. 1.

Principle of the light trap. a) Operational principle of the light trap and its constituents. b) Ray tracing light with a 100% absorbing solar cell. c) Ray tracing light with a 100% reflecting solar cell.

Fig. 2.
Fig. 2.

Manufacturing route of the light trapping element. 1. Imprinting, 2. Resist deposition, 3. UV exposure through the lenses, 4–5. Resist development, 6. Metallization through evaporation, 7. Residual resist removal. 8. The light trap in operation with a solar cell.

Fig. 3.
Fig. 3.

Pictures of the obtained structures. SEM scans of the spherical (a) and cylindrical (b) polymer lenses. The periodicity is 200 and 400 µm respectively. Optical transmission microscope picture of the backside of the samples, comprising the perforated mirrors, is displayed in (c) and (d).

Fig. 4.
Fig. 4.

Optical characteristics of the trap and the cell. a) Trap element transmission in forward and backward direction. b) Device absorptance as measured from reflectance and blend material absorption as measured from transmission. Inset: chemical structures of the utilized donor (APFO Green 9) and acceptor (PCBM[70]) materials in the blend.

Fig. 5.
Fig. 5.

Photovoltaic characteristics with the light trap. a) Photoresponsivity with and without the light trapping element in front of the cell, together with the solar irradiance spectra. b. JV characteristics from simulated AM 1.5 solar illuminated APFO Green 9/PCBM[70] solar cell with and without the trap. An increase in short circuit current of 25% can be confirmed upon the addition of the light trap.

Fig. 6.
Fig. 6.

Effect of multiple absorption events. a) Schematic of the multiple bounces and the according Fresnel intensity coefficients. b) Calculated total cell absorptance for the APFO Green 9/PCBM[70] system with and without the trap system. For different number of absorption events included, a noticeable improvement above 400 nm can be found.

Equations (4)

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f = R [ n 2 ( n 2 n 1 ) ]
( 1 R s ) T T ( 1 R s ) + T T R S R T ( 1 R s ) + T T R S 2 R T 2 ( 1 R s ) +
T T ( 1 R S ) 1 ( 1 R S R T )
R S ( λ ) > 1 T T ( λ ) R T ( λ )

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