Hostname: page-component-6587cd75c8-gglxz Total loading time: 0.001 Render date: 2025-04-23T11:27:26.449Z Has data issue: false hasContentIssue false
  • English
  • Français

Organic solar cells: An overview

Published online by Cambridge University Press:  03 March 2011

Harald Hoppe  and
Niyazi Serdar Sariciftci
Harald Hoppe*
Affiliation:
Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, 4040 Linz, Austria
Niyazi Serdar Sariciftci
Affiliation:
Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, 4040 Linz, Austria
*
a) Address all correspondence to this author. e-mail: [email protected]
Get access

Abstract

Organic solar cell research has developed during the past 30 years, but especially in the last decade it has attracted scientific and economic interest triggered by a rapid increase in power conversion efficiencies. This was achieved by the introduction of new materials, improved materials engineering, and more sophisticated device structures. Today, solar power conversion efficiencies in excess of 3% have been accomplished with several device concepts. Though efficiencies of these thin-film organicdevices have not yet reached those of their inorganic counterparts (η ≈ 10–20%); the perspective of cheap production (employing, e.g., roll-to-roll processes) drives the development of organic photovoltaic devices further in a dynamic way. The two competitive production techniques used today are either wet solution processing or dry thermal evaporation of the organic constituents. The field of organic solar cells profited well from the development of light-emitting diodes based on similar technologies, which have entered the market recently. We review here the current status of the field of organic solar cells and discuss different production technologies as well as study the important parameters to improve their performance.

Keywords

OrganicPhotovoltaicNanoscale
Type
Reviews—Organic Electronics Special Section
Information
Journal of Materials Research , Volume 19 , Issue 7 , July 2004 , pp. 1924 - 1945
Copyright
Copyright © Materials Research Society 2004

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

REFERENCES

1.Goetzberger, A., Hebling, C. and Schock, H-W.: Photovoltaic materials, history, status and outlook. Mater. Sci. Eng. R 40, 1 (2003).CrossRefGoogle Scholar
2.Chamberlain, G.A.: Organic solar cells: A review. Solar Cells 8, 47 (1983).CrossRefGoogle Scholar
3.Wöhrle, D. and Meissner, D.: Organic solar cells. Adv. Mater. 3, 129 (1991).CrossRefGoogle Scholar
4.Brabec, C.J., Sariciftci, N.S. and Hummelen, J.C.: Plastic solar cells. Adv. Funct. Mater. 11, 15 (2001).3.0.CO;2-A>CrossRefGoogle Scholar
5.Halls, J.J.M. and Friend, R.H. in Clean Electricity from Photovoltaics, edited by Archer, M.D. and Hill, R. (Imperial College Press, London, U.K., 2001)Google Scholar
6.Nelson, J.: Organic photovoltaic films. Curr. Opin. Solid State Mater. Sci. 6, 87 (2002).CrossRefGoogle Scholar
7.Nunzi, J-M.: Organic photovoltaic materials and devices. C. R. Physique 3, 523 (2002).CrossRefGoogle Scholar
8.Photovoltaics Organic: Concepts and Realization; Vol. 60, edited by Brabec, C.J., Dyakonov, V., Parisi, J., and Sariciftci, N.S. (Springer, Berlin, Germany, 2003)CrossRefGoogle Scholar
9.Peumans, P., Yakimov, A. and Forrest, S.R.: Small molecular weight organic thin-film photodetectors and solar cells. J. Appl. Phys. 93, 3693 (2003).CrossRefGoogle Scholar
10.Handbook of Conducting Polymers, Vol. 1-2, edited by Skotheim, T.A. (Marcel Dekker, Inc., New York, 1986)Google Scholar
11.Handbook of Organic Conductive Molecules and Polymers, Vol. 1–4, edited by Nalwa, H.S. (John Wiley & Sons Ltd., Chichester, U.K., 1997)Google Scholar
12.Handbook of Conducting Polymers, edited by Skotheim, T.A., Elsenbaumer, R.L., and Reynolds, J.R. (Marcel Dekker, Inc., New York, 1998)Google Scholar
13.Semiconducting Polymers, edited by Hadziioannou, G. and van Hutten, P.F. (Wiley-VCH, Weinheim, 2000)Google Scholar
14.Winder, C. and Sariciftci, N.S.: Low Bandgap polymers for photon harvesting in bulk heterojunction solar cells. J. Mater. Chem. 14, 1077 (2004).CrossRefGoogle Scholar
15.Dimitrakopoulos, C.D. and Mascaro, D.J.: Organic thin-film transistors: A review of recent advances. IBM J. Res. Dev. 45, 11 (2001).CrossRefGoogle Scholar
16.Halls, J.J.M., Pichler, K., Friend, R.H., Moratti, S.C. and Holmes, A.B.: Exciton diffusion and dissociation in a poly(p-phenylenevinylene)/C60 heterojunction photovoltaic cell. Appl. Phys. Lett. 68, 3120 (1996).CrossRefGoogle Scholar
17.Halls, J.J.M. and Friend, R.H.: The photovoltaic effect in a poly(p-phenylenevinylene)/perylene heterojunction. Synth. Met. 85, 1307 (1997).CrossRefGoogle Scholar
18.Kerp, H.R., Donker, H., Koehorst, R.B.M., Schaafsma, T.J. and van Faassen, E.E.: Exciton transport in organic dye layers for photovoltaic applications. Chem. Phys. Lett. 298, 302 (1998).CrossRefGoogle Scholar
19.Savanije, T.J., Warman, J.M. and Goossens, A.: Visible light sensitisation of titanium dioxide using a phenylene vinylene polymer. Chem. Phys. Lett. 287, 148 (1998).CrossRefGoogle Scholar
20.Haugeneder, A., Neges, M., Kallinger, C., Spirkl, W., Lemmer, U., Feldmann, J., Scherf, U., Harth, E., Gügel, A. and Müllen, K.: Exciton diffusion and dissociation in conjugated polymer/fullerene blends and heterostructures. Phys. Rev. B 59, 15346 (1999).CrossRefGoogle Scholar
21.Pettersson, L.A.A., Roman, L.S. and Inganäs, O.: Modeling photocurrent action spectra of photovoltaic devices based on organic thin films. J. Appl. Phys. 86, 487 (1999).CrossRefGoogle Scholar
22.Stoessel, M., Wittmann, G., Staudigel, J., Steuber, F., Blässing, J., Roth, W., Klausmann, H., Rogler, W., Simmerer, J., Winnacker, A., Inbasekaran, M. and Woo, E.P.: Cathode-induced luminescence quenching in polyfluorenes. J. Appl. Phys. 87, 4467 (2000).CrossRefGoogle Scholar
23.Stübinger, T. and Brütting, W.: Exciton diffusion and optical interference in organic donor–acceptor photovoltaic cells. J. Appl. Phys. 90, 3632 (2001).CrossRefGoogle Scholar
24.Primary Photoexcitations in Conjugated Molecular Exciton versus Semiconductor Band Model; edited by Sariciftci, N.S. (World Scientific, Singapore, 1997)Google Scholar
25.Gregg, B.A. and Hanna, M.C.: Comparing organic to inorganic photovoltaic cells: Theory, experiment, and simulation. J. Appl. Phys. 93, 3605 (2003).CrossRefGoogle Scholar
26.Parker, I.D.: Carrier tunneling and device characteristics in polymer light-emitting diodes. J. Appl. Phys. 75, 1656 (1994).CrossRefGoogle Scholar
27.Gosh, A.K., Morel, D.L., Feng, T., Shaw, R.F., Rowe, C.A. and Jr., : Photovoltaic and rectification properties of Al/Mg phthalocyanine/Ag Schottky-barrier cells. J. Appl. Phys. 45, 230 (1974).CrossRefGoogle Scholar
28.Meissner, D., Siebentritt, S., and S. Günster: Charge carrier photogeneration in organic solar cells, presented at the International Symposium on Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XI: Photovoltaics, Photochemistry and Photoelectrochemistry, Toulouse, France, 1992.CrossRefGoogle Scholar
29.Karg, S., Riess, W., Dyakonov, V. and Schwoerer, M.: Electrical and optical characterization of poly(phenylene-vinylene) light emitting diodes. Synth. Met. 54, 427 (1993).CrossRefGoogle Scholar
30.Morel, D.L., Gosh, A.K., Feng, T., Stogryn, E.L., Purwin, P.E., Shaw, R.F. and Fishman, C.: High-efficiency organic solar cells. Appl. Phys. Lett. 32, 495 (1978).CrossRefGoogle Scholar
31.Gosh, A.K. and Feng, T.: Merocyanine organic solar cells. J. Appl. Phys. 49, 5982 (1978).CrossRefGoogle Scholar
32.Sze, S.M.: Physics of Semiconductor Devices (John Wiley & Sons, New York, 1981)Google Scholar
33.Tang, C.W.: Two-layer organic photovoltaic cell. Appl. Phys. Lett. 48, 183 (1986).CrossRefGoogle Scholar
34.Rostalski, J. and Meissner, D.: Monochromatic versus solar efficiencies of organic solar cells. Sol. Energy Mater. Sol. Cells 61, 87 (2000).CrossRefGoogle Scholar
35.Peumanns, P., Bulovic, V. and Forrest, S.R.: Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes. Appl. Phys. Lett. 76, 2650 (2000).CrossRefGoogle Scholar
36.Hiramoto, M., Suezaki, M. and Yokoyama, M.: Effect of thin gold interstitial-layer on the photovoltaic properties of tandem organic solar cells. Chem. Lett. 19, 327 (1990).CrossRefGoogle Scholar
37.Hiramoto, M., Fujiwara, H. and Yokoyama, M.: Three-layered organic solar cell with a photoactive interlayer of codeposited pigments. Appl. Phys. Lett. 58, 1062 (1991).CrossRefGoogle Scholar
38.Hiramoto, M., Fujiwara, H. and Yokoyama, M.: p-i-n like behavior in three-layered organic solar cells having a co-deposited interlayer of pigments. J. Appl. Phys. 72, 3781 (1992).CrossRefGoogle Scholar
39.Marks, R.N., Halls, J.J.M., Bradley, D.D.C., Friend, R.H. and Holmes, A.B.: The photovoltaic response in poly(p-phenylene vinylene) thin-film devices. J. Phys.: Condens. Matter. 6, 1379 (1994).Google Scholar
40.Yu, G., Zhang, C. and Heeger, A.J.: Dual-function semiconducting polymer devices: Light-emitting and photodetecting diodes. Appl. Phys. Lett. 64, 1540 (1994).CrossRefGoogle Scholar
41.Antoniadis, H., Hsieh, B.R., Abkowitz, M.A., Jenekhe, S.A. and Stolka, M.: Photovoltaic and photoconductive properties of aluminum/poly(p-phenylene vinylene) interfaces. Synth. Met. 62, 265 (1994).CrossRefGoogle Scholar
42.Sariciftci, N.S., Smilowitz, L., Heeger, A.J. and Wudl, F.: Photoinduced electron transfer from a conducting polymer to buckminsterfullerene. Science 258, 1474 (1992).CrossRefGoogle ScholarPubMed
43.Smilowitz, L., Sariciftci, N.S., Wu, R., Gettinger, C., Heeger, A.J. and Wudl, F.: Photoexcitation spectroscopy of conducting-polymer-C60 composites: Photoinduced electron transfer. Phys. Rev. B 47, 13835 (1993).CrossRefGoogle ScholarPubMed
44.Lee, C.H., Yu, G., Moses, D., Pakbaz, K., Zhang, C., Sariciftci, N.S., Heeger, A.J. and Wudl, F.: Sensitization of the photoconductivity of conducting polymers by C60: Photoinduced electron transfer. Phys. Rev. B 48, 15425 (1993).CrossRefGoogle ScholarPubMed
45.Morita, S., Zakhidov, A.A. and Yoshino, K.: Doping effect of buckminsterfullerene in conducting polymer: Change of absorption spectrum and quenching of luminescene. Solid State Commun. 82, 249 (1992).CrossRefGoogle Scholar
46.Morita, S., Kiyomatsu, S., Yin, X.H., Zakhidov, A.A., Noguchi, T., Ohnishi, T. and Yoshino, K.: Doping effect of buckminsterfullerene in poly(2,5-dialkoxy-p-phenylene vinylene). J. Appl. Phys. 74, 2860 (1993).CrossRefGoogle Scholar
47.Sariciftci, N.S., Braun, D., Zhang, C., Srdanov, V.I., Heeger, A.J., Stucky, G. and Wudl, F.: Semiconducting polymer-buckminsterfullerene heterojunctions: Diodes, photodiodes, and photovoltaic cells. Appl. Phys. Lett. 62, 585 (1993).CrossRefGoogle Scholar
48.Roman, L.S., Mammo, W., Petterson, L.A.A., Andersson, M.R. and Inganäs, O.: High quantum efficiency polythiophene/C60 photodiodes. Adv. Mater. 10, 774 (1998).3.0.CO;2-J>CrossRefGoogle Scholar
49.Yu, G., Gao, J., Hummelen, J.C., Wudl, F. and Heeger, A.J.: Polymer photovoltaic cells: Enhanced efficiencies via a network of internal donor-acceptor heterojunctions. Science 270, 1789 (1995).CrossRefGoogle Scholar
50.Yang, C.Y. and Heeger, A.J.: Morphology of composites of semiconducting polymers mixed with C60. Synth. Met. 83, 85 (1996).CrossRefGoogle Scholar
51.Hummelen, J.C., Knight, B.W., LePeq, F., Wudl, F., Yao, J. and Wilkins, C.L.: Preparation and characterization of fulleroid and methanofullerene derivatives. J. Org. Chem. 60, 532 (1995).CrossRefGoogle Scholar
52.Yu, G. and Heeger, A.J.: Charge separation and photovoltaic conversion in polymer composites with internal donor/acceptor heterojunctions. J. Appl. Phys. 78, 4510 (1995).CrossRefGoogle Scholar
53.Halls, J.J.M., Walsh, C.A., Greenham, N.C., Marseglia, E.A., Friend, R.H., Moratti, S.C. and Holmes, A.B.: Efficient photodiodes from interpenetrating polymer networks. Nature 376, 498 (1995).CrossRefGoogle Scholar
54.Tada, K., Hosada, K., Hirohata, M., Hidayat, R., Kawai, T., Onoda, M., Teraguchi, M., Masuda, T., Zakhidov, A.A. and Yoshino, K.: Donor polymer (PAT6) - acceptor polymer (CNPPV) fractal network photocells. Synth. Met. 85, 1305 (1997).CrossRefGoogle Scholar
55.Granström, M., Petritsch, K., Arias, A.C., Lux, A., Andersson, M.R. and Friend, R.H.: Laminated fabrication of polymeric photovoltaic diodes. Nature 395, 257 (1998).CrossRefGoogle Scholar
56.Peumanns, P. and Forrest, S.R.: Very-high-efficiency double-heterostructure copper phthalocyanine/C60 photovoltaic cells. Appl. Phys. Lett. 79, 126 (2001).CrossRefGoogle Scholar
57.Peumans, P. and Forrest, S.R.: Erratum: Very-high-efficiency double-heterostructure copper phthalocyanine/C60 photovoltaic cells. Appl. Phys. Lett. 79, 126 (2001).CrossRefGoogle Scholar
58.Xue, J., Uchida, S., Rand, B.P., Forrest, S.R.: 4.2% efficient organic photovoltaic cells with low series resistances. Appl Phys. Lett. 84, 3013 (2004).CrossRefGoogle Scholar
59.Shaheen, S.E., Brabec, C.J., Sariciftci, N.S., Padinger, F., Fromherz, T. and Hummelen, J.C.: 2.5% efficient organic plastic solar cells. Appl. Phys. Lett. 78, 841 (2001).CrossRefGoogle Scholar
60.Kroon, J.M., Wienk, M.M., Verhees, W.J.H. and Hummelen, J.C.: Accurate efficiency determination and stability studies of conjugated polymer/fullerene solar cells. Thin Solid Films 403–404, 223 (2002).CrossRefGoogle Scholar
61.Munters, T., Martens, T., Goris, L., Vrindts, V., Manca, J., Lutsen, L., Ceunick, W.D., Vanderzande, D., Schepper, L.D., Gelan, J., Sariciftci, N.S. and Brabec, C.J.: A comparison between state-of-the-art ‘gilch’ and ‘sulphinyl’ synthesised MDMO-PPV/PCBM bulk heterojunction solar cells. Thin Solid Films 403–404, 247 (2002).CrossRefGoogle Scholar
62.Aernouts, T., Geens, W., Portmans, J., Heremans, P., Borghs, S. and Mertens, R.: Extraction of bulk and contact components of the series resistance in organic bulk donor-acceptor-heterojunctions. Thin Solid Films 403, 297 (2002).CrossRefGoogle Scholar
63.Schilinsky, P., Waldauf, C. and Brabec, C.J.: Recombination and loss analysis in polythiophene based bulk heterojunction photodetectors. Appl. Phys. Lett. 81, 3885 (2002).CrossRefGoogle Scholar
64.Padinger, F., Rittberger, R.S. and Sariciftci, N.S.: Effects of postproduction treatment on plastic solar cells. Adv. Funct. Mater. 13, 1 (2003).CrossRefGoogle Scholar
65.Svensson, M., Zhang, F., Veenstra, S.C., Verhees, W.J.H., Hummelen, J.C., Kroon, J.M., Inganäs, O. and Andersson, M.R.: High-performance polymer solar cells of an alternating polyfluorene copolymer and a fullerene derivative. Adv. Mater. 15, 988 (2003).CrossRefGoogle Scholar
66.Wienk, M.M., Kroon, J.M., Verhees, W.J.H., Knol, J., Hummelen, J.C., van Hall, P.A. and Janssen, R.A.J. Efficient methano[70]fullerene/MDMO-PPV bulk heterojunction photovoltaic cells. Angew. Chem. Int. Ed. 42, 3371 (2003)CrossRefGoogle Scholar
67.Geens, W., Aernouts, T., Poortmans, J. and Hadziioannou, G.: Organic co-evaporated films of a PPV-pentamer and C60: Model systems for donor/acceptor polymer blends. Thin Solid Films 403, 438 (2002).CrossRefGoogle Scholar
68.Peumans, P., Uchida, S. and Forrest, S.R.: Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films. Nature 425, 158 (2003).CrossRefGoogle ScholarPubMed
69.Maennig, B., Drechsel, J., Gebeyehu, D., Simon, P., Kozlowski, F., Werner, A., Li, F., Grundmann, S., Sonntag, S., Koch, M., Leo, K., Pfeiffer, M., Hoppe, H., Meissner, D., Sariciftci, S., Riedel, I., Dyakonov, V. and Parisi, J.: Organic p-i-n solar cells. Appl. Phys. A 79,1 (2004).CrossRefGoogle Scholar
70.Gebeyehu, D., Pfeiffer, M., Maennig, B., Drechsel, J., Werner, A. and Leo, K.: Highly efficient p-i-n type organic photovoltaic devices. Thin Solid Films 451–452, 29 (2004).CrossRefGoogle Scholar
71.Krüger, J., Plass, R., Cevey, L., Piccirelli, M., Grätzel, M. and Bach, U.: High efficiency solid-state photovoltaic device due to inhibition of interface charge recombination. Appl. Phys. Lett. 79, 2085 (2001).CrossRefGoogle Scholar
72.Krüger, J., Plass, R., Grätzel, M. and Matthieu, H-J.: Improvement of the photovoltaic performance of solid-state dye-sensitized device by silver complexation of the sensitizer cis-bis(4,4-dicarboxy-2,2bipyridine)-bis(isothiocyanato) ruthenium(II). Appl. Phys. Lett. 81, 367 (2002).CrossRefGoogle Scholar
73.Huynh, W.U., Dittmer, J.J. and Alivisatos, A.P.: Hybrid Nanorod-Polymer Solar Cells. Science 295, 2425 (2002).CrossRefGoogle ScholarPubMed
74.Tributsch, H. and Calvin, M.: Electrochemistry of excited molecules. Photoelectrochemical reactions of chlorophylls. Photochem. Photobiol. 14, 95 (1971).CrossRefGoogle Scholar
75.Tributsch, H.: Reaction of excited chlorophyll molecules at electrodes and in photosynthesis. Photochem. Photobiol. 16, 261 (1972).CrossRefGoogle Scholar
76.Osa, T. and Fujihira, M.: Photocell using covalently-bound dyes on semiconductor surfaces. Nature 264, 349 (1976).CrossRefGoogle Scholar
77.Fujihira, M., Ohishi, N. and Osa, T.: Photocell using covalently-bound dyes on semiconductor surfaces. Nature 268, 226 (1977).CrossRefGoogle Scholar
78.Tsubomura, H., Matsumura, M., Nakatani, K., Yamamoto, K. and Maeda, K.: ‘Wet-type’ solar cells with semiconductor electrodes. Sol. Energy 21, 93 (1978).CrossRefGoogle Scholar
79.Matsumura, M., Matsudaira, S., Tsubomura, H., Takata, M. and Yanagida, H.: Sintered ZnO electrode for dye-sensitized photocell. Yogyo Kyokai Shi 87, 167 (1979).CrossRefGoogle Scholar
80.O’Regan, B. and Grätzel, M.: A low cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature 353, 737 (1991).CrossRefGoogle Scholar
81.Kalyanasundaram, K. and Grätzel, M.: Applications of functionalized transition metal complexes in photonic and optoelectronic devices. Coordin. Chem. Rev. 77, 347 (1998).CrossRefGoogle Scholar
82.Grätzel, M.: Photoelectrochemical cells. Nature 414, 338 (2001).CrossRefGoogle ScholarPubMed
83.Grätzel, M.: Dye-sensitized solar cells. J. Photochem. Photobiol. C 4, 145 (2003).CrossRefGoogle Scholar
84.Bach, U., Lupo, D., Comte, P., Moser, J.E., Weissörtel, F., Salbeck, J., Spreitzer, H. and Grätzel, M.: Solid-state dye-sensitized mesoporous TiO2 solar cells with high photon-to-electron conversion efficiencies. Nature 395, 583 (1998).CrossRefGoogle Scholar
85.Salafsky, J.S.: Exciton dissociation, charge transport, and recombination in ultrathin, conjugated polymer-TiO2 nanocrystal intermixed composites. Phys. Rev. B 59, 10885 (1999).CrossRefGoogle Scholar
86.Arango, A.C., Johnson, L.R., Bliznyuk, V.N., Schlesinger, Z., Carter, S.A. and Hörhold, H-H.: Efficient titanium oxide/conjugated polymer photovoltaics for solar energy conversion. Adv. Mater. 89, 1689 (2000).3.0.CO;2-9>CrossRefGoogle Scholar
87.Fan, Q., McQuillin, B., Bradley, D.D.C., Whitelegg, S. and Seddon, A.B.: A solid state solar cell using sol–gel processed material and a polymer. Chem. Phys. Lett. 347, 325 (2001).CrossRefGoogle Scholar
88.Gebeyehu, D., Brabec, C.J., Padinger, F., Fromherz, T., Spiekermann, S., Vlachopoulos, N., Kienberger, F., Schindler, H. and Sariciftci, N.S.: Solid state dye-sensitized TiO2 solar cells with poly(3-octylthiophene) as hole transport layer. Synth. Met. 121, 1549 (2001).CrossRefGoogle Scholar
89.Saito, Y., Kitamura, T., Wada, Y. and Yanagida, S.: Poly(3,4-ethylenedioxythiophene) as a hole conductor in solid state dye sensitized solar cells. Synth. Met. 131, 185 (2002).CrossRefGoogle Scholar
90.Greenham, N.C., Peng, X. and Alivisatos, A.P.: Charge separation and transport in conjugated-polymer/semiconductor-nanocrystal composites studied by photoluminescence quenching and photoconductivity. Phys. Rev. B 54, 17628 (1996).CrossRefGoogle ScholarPubMed
91.Arici, E., Sariciftci, N.S. and Meissner, D.: Hybrid solar cells based on nanoperticles of CuInS2 in organic matrices. Adv. Funct. Mater. 13, 165 (2003).CrossRefGoogle Scholar
92.van Hal, P.A., Wienk, M.M., Kroon, J.M., Verhees, W.J.H., Slooff, L.H., van Gennip, W.J.H., Jonkheijm, P. and Janssen, R.A.J.: Photoinduced electron transfer and photovoltaic response of a MDMO-PPV:TiO2 bulk-heterojunction. Adv. Mater. 15, 118 (2003).CrossRefGoogle Scholar
93.Pientka, M., Dyakonov, V., Meissner, D., Rogach, A., Talapin, D., Weller, H., Lutsen, L. and Vanderzande, D.: Photoinduced charge transfer in composites of conjugated polymers and semiconductor nanocrystals. Nanotechnology 15, 163 (2004).CrossRefGoogle Scholar
94.Arici, E., Hoppe, H., Schäffler, F., Meissner, D., Malik, M.A. and Sariciftci, N.S.: Hybrid solar cells based on inorganic nanoclusters and semiconductive polymers. Thin Solid Films 451–452,612 (2004).CrossRefGoogle Scholar
95.Arici, E., Sariciftci, N.S. and Meissner, D. in Encyclopedia of Nanoscience and Nanotechnology, edited by Nalwa, H.S. (American Scientific Publishers, Stevenson Ranch, CA, 2004)Google Scholar
96.Neugebauer, H., Brabec, C., Hummelen, J.C. and Sariciftci, N.S.: Stability and photodegradation mechanisms of conjugated polymer/fullerene plastic solar cells. Sol. Energy Mater. Sol. Cells 61,35 (2000).CrossRefGoogle Scholar
97.Padinger, F., Fromherz, T., Denk, P., Brabec, C.J., Zettner, J., Hierl, T. and Sariciftci, N.S.: Degradation of bulk heterojunction solar cells operated in an inert gas atmosphere: A systematic study. Synth. Met. 121, 1605 (2001).CrossRefGoogle Scholar
98.Tang, C.W. and Albrecht, A.C.: Photovoltaic effects of metal-chlorophyll-a-metal sandwich cells. J. Chem. Phys. 62, 2139 (1975).CrossRefGoogle Scholar
99.Hiramoto, M., Kishigami, Y. and Yokoyama, M.: Doping effect on the two-layer organic solar cell. Chem. Lett. 19, 119 (1990).CrossRefGoogle Scholar
100.Lane, P.A., Rostalski, J., Giebeler, C., Martin, S.J., Bradley, D.D.C. and Meissner, D.: Electroabsorption studies of phthalocyanine/perylene solar cells. Sol. Energy Mater. Sol. Cells 63,3 (2000).CrossRefGoogle Scholar
101.Rostalski, J. and Meissner, D.: Photocurrent spectroscopy for the investigation of charge carrier generation and transport mechanisms in organic p/n-junction solar cells. Sol. Energy Mater. Sol. Cells 63,37 (2000).CrossRefGoogle Scholar
102.Pfeiffer, M., Beyer, A., Plönnigs, B., Nollau, A., Fritz, T., Leo, K., Schlettwein, D., Hiller, S. and Wöhrle, D.: Controlled p-doping of pigment layers by cosublimation: Basic mechanisms and implication for their use in organic photovoltaic cells. Sol. Energy Mater. Sol. Cells 63,83 (2000).CrossRefGoogle Scholar
103.Gebeyehu, D., Maennig, B., Drechsel, J., Leo, K. and Pfeiffer, M.: Bulk-heterojunction photovoltaic devices based on donor-acceptor organic small molecule blends. Sol. Energy Mater. Sol. Cells 79, 81 (2003).CrossRefGoogle Scholar
104.Drechsel, J., Männig, B., Kozlowski, F., Gebeyehu, D., Werner, A., Koch, M., Leo, K. and Pfeiffer, M.: High efficiency organic solar cells based on single or multiple PIN structures. Thin Solid Films 451–452, 515 (2004).CrossRefGoogle Scholar
105.Dresselhaus, M.S., Dresselhaus, G. and Eklund, P.C.: Science of Fullerenes and Carbon Nanotubes (Academic Press, San Diego, CA, 1996)Google Scholar
106.Sariciftci, N.S. and Heeger, A.J. in Handbook of Organic Conductive Molecules and Polymers; Vol. 1, edited by Nalwa, H.S. (John Wiley & Sons Ltd., Chichester, U.K., 1997), p. 413Google Scholar
107.Burroughes, J.H., Bradley, D.D.C., Brown, A.R., Marks, R.N., Mackay, K., Friend, R.H., Burns, P.L. and Holmes, A.B.: Light- emitting diodes based on conjugated polymers. Nature 347, 539 (1990).CrossRefGoogle Scholar
108.Braun, D. and Heeger, A.J.: Visible light emission from semiconducting polymer diodes. Appl. Phys. Lett. 58, 1982 (1991).CrossRefGoogle Scholar
109.Organic Light-Emitting Devices Survey; edited by Shinar, J. (Springer, New York, 2004)CrossRefGoogle Scholar
110.Adam, D., Schuhmacher, P., Simmerer, J., Häussling, L., Siemensmeyer, K., Etzbachi, K.H., Ringsdorf, H. and Haarer, D.: Fast photoconduction in the highly ordered columnar phase of a discotic liquid crystal. Nature 371, 141 (1994).CrossRefGoogle Scholar
111.Funahashi, M. and Hanna, J.-I.: Fast hole transport in a new calamitic liquid crystal of 2-(4’-heptyloxyphenyl)-6dodecylthiobenzothiazole. Phys. Rev. Lett. 78, 2184 (1997).CrossRefGoogle Scholar
112.Sirringhaus, H., Brown, P.J., Friend, R.H., Nielsen, M.M., Bechgaard, K., Langeveld-Voss, B.M.W., Spiering, A.J.H., Janssen, R.A.J., Meijer, E.W., Herwig, P. and de Leeuw, D.M.: Two-dimensional charge transport in self-organized, high-mobility conjugated polymers. Nature 401, 685 (1999).CrossRefGoogle Scholar
113.Sirringhaus, H., Wilson, R.J., Friend, R.H., Inbasekaran, M., Wu, W., Woo, E.P., Grell, M. and Bradley, D.D.C.: Mobility enhancement in conjugated polymer field-effect transistors through chain alignment in a liquid-crystalline phase. Appl. Phys. Lett. 77, 406 (2000).CrossRefGoogle Scholar
114.Aasmundtveit, K.E., Samuelsen, E.J., Guldstein, M., Steinsland, C., Flornes, O., Fagermo, C., Seeberg, T.M., Pettersson, L.A.A., Inganäs, O., Feidenhans, R. and Ferrer, S.: Structural anisotropy of poly(alkylthiophene) films. Macromolecules 33, 3120 (2000).CrossRefGoogle Scholar
115.Zhokhavets, U., Gobsch, G., Hoppe, H. and Sariciftci, N.S.: Anisotropic optical properties of thin poly(3-octylthiophene)-films as a function of preparation conditions. Synth. Met. 143, 113 (2004).CrossRefGoogle Scholar
116.Geens, W., Shaheen, S.E., Brabec, C.J., Poortmans, J., and Sariciftci, N.S.: Field-effect mobility measurements of conjugated polymer/fullerene photovoltaic blends, presented at the 14th International Winterschool/Euroconference, Kirchberg, Austria, 2000 (AIP).CrossRefGoogle Scholar
117.Aernouts, T., Vanlaeke, P., Geens, W., Poortmans, J., Heremans, P., Borghs, S., and Mertens, R.: The influence of the donor/acceptor ratio on the performance of organic bulk heterojunction solar cells, presented at the E-MRS Spring Meeting, Strasbourg, France, 2003.Google Scholar
118.Choulis, S.A., Nelson, J., Kim, Y., Poplavskyy, D., Kreouzis, T., Durrant, J.R. and Bradley, D.D.C.: Investigation of transport properties in polymer/fullerene blends using time-of-flight photocurrent measurements. Appl. Phys. Lett. 83, 3812 (2003).CrossRefGoogle Scholar
119.Pacios, R., Nelson, J., Bradley, D.D.C. and Brabec, C.J.: Composition dependence of electron and hole transport in polyfluorene:[6,6]-phenyl C61-butyric acid methyl ester blend films. Appl. Phys. Lett. 83, 4764 (2003).CrossRefGoogle Scholar
120.Veenstra, S.C., Malliaras, G.G., Brouwer, H.J., Esselink, F.J., Krasnikov, V.V., van Hutten, P.F., Wildeman, J., Jonkman, H.T., Sawatzky, G.A. and Hadziioannou, G.: Sexithiophene-C60 blends as model systems for photovoltaic devices. Synth. Met. 84, 971 (1997).CrossRefGoogle Scholar
121.Tsuzuki, T., Shirota, Y., Rostalski, J. and Meissner, D.: The effect of fullerene doping on photoelectric conversion using titanyl phthalocyanine and a perylene pigment. Sol. Energy Mater. Sol. Cells 61, 1 (2000).CrossRefGoogle Scholar
122.Shaheen, S.E., Radspinner, R., Peyghambarian, N. and Jabbour, G.E.: Fabrication of bulk heterojunction plastic solar cells by screen printing. Appl. Phys. Lett. 79, 2996 (2001).CrossRefGoogle Scholar
123.Gregg, B.A.: Excitonic Solar Cells. J. Phys. Chem. B 107, 4688 (2003).CrossRefGoogle Scholar
124.Pope, M. and Swenberg, C.E.: Electronic Processes in Organic Crystals and Polymers, 2nd ed. (Oxford University Press, New York, 1999)CrossRefGoogle Scholar
125.Murgia, M., Biscarini, F., Cavallini, M., Taliani, C. and Ruani, G.: Intedigitated p-n junction: A route to improve the efficiency in organic photovoltaic cells. Synth. Met. 121, 1533 (2001).CrossRefGoogle Scholar
126.Ruani, G., Fontanini, C., Murgia, M. and Taliani, C.: Weak intrinsic charge-transfer complexes: A new route for developing wide spectrum organic photovoltaic cells. J. Chem. Phys. 116, 1713 (2002).CrossRefGoogle Scholar
127.Toccoli, T., Boschetti, A., Corradi, C., Guerini, L., Mazzola, M. and Iannotta, S.: Co-deposition of phthalocyanines and fullerene by SuMBE; Characterization and prototype devices. Synth. Met. 138, 3 (2003).CrossRefGoogle Scholar
128.Arkhipov, V.I., Heremans, P. and Bässler, H.: Why is exciton dissociation so efficient at the interface between a conjugated polymer and an electron acceptor? Appl. Phys. Lett. 82, 4605 (2003).CrossRefGoogle Scholar
129.Zerza, G., Brabec, C.J., Cerullo, G., Silvestri, S.D. and Sariciftci, N.S.: Ultrafast charge transfer in conjugated polymer-fullerene composites. Synth. Met. 119, 637 (2001).CrossRefGoogle Scholar
130.Nogueira, A.F., Montari, I., Nelson, J., Durrant, J.R., Winder, C., Sariciftci, N.S. and Brabec, C.: Charge recombination in conjugated polymer/fullerene blended films studied by transient absorption spectroscopy. J. Phys. Chem. B 107, 1567 (2003).CrossRefGoogle Scholar
131.Breeze, A.J., Salomon, A., Ginley, D.S., Gregg, B.A., Tillmann, H. and Hörhold, H-H.: Polymer-perylene diimide heterojunction solar cells. Appl. Phys. Lett. 81, 3085 (2002).CrossRefGoogle Scholar
132.Jenekhe, S.A. and Yi, S.: Efficient photovoltaic cells from semiconducting polymer heterojunctions. Appl. Phys. Lett. 77, 2635 (2000).CrossRefGoogle Scholar
133.Yohannes, T., Zhang, F., Svensson, M., Hummelen, J.C., Andersson, M.R. and Inganäs, O.: Polyfluorene copolymer based bulk heterojunction solar cells. Thin Solid Films 449, 152 (2004).CrossRefGoogle Scholar
134.Katz, E.A., Faiman, D., Tuladhar, S.M., Kroon, J.M., Wienk, M.M., Fromherz, T., Padinger, F., Brabec, C.J. and Sariciftci, N.S.: Temperature dependence for the photovoltaic device parameters of polymer-fullerene solar cells under operating conditions. J. Appl. Phys. 90, 5343 (2001).CrossRefGoogle Scholar
135.Dyakonov, V.: The polymer-fullerene interpenetrating network: One route to a solar cell approach. Physica E 14, 53 (2002).CrossRefGoogle Scholar
136.Dittmer, J.J., Lazzaroni, R., Leclere, P., Moretti, P., Granström, M., Petritsch, K., Marseglia, E.A., Friend, R.H., Bredas, J.L., Rost, H. and Holmes, A.B.: Crystal network formation in organic solar cells. Sol. Energy Mater. Sol. Cells 61, 53 (2000).CrossRefGoogle Scholar
137.Dittmer, J.J., Marseglia, E.A. and Friend, R.H.: Electron trapping in dye/polymer blend photovoltaic cells. Adv. Mater. 12, 1270 (2000).3.0.CO;2-8>CrossRefGoogle Scholar
138.Petritsch, K., Dittmer, J.J., Marseglia, E.A., Friend, R.H., Lux, A., Rozenberg, G.G., Moratti, S.C. and Holmes, A.B.: Dye-based donor/acceptor solar cells. Sol. Energy Mater. Sol. Cells 61, 63 (2000).CrossRefGoogle Scholar
139.Schmidt-Mende, L., Fechtenkötter, A., Müllen, K., Moons, E., Friend, R.H. and MacKenzie, J.D.: Self-organized discotic liquid crystals for high-efficiency organic photovoltaics. Science 293, 1119 (2001).CrossRefGoogle ScholarPubMed
140.Chen, L., Godovsky, D., Inganäs, O., Hummelen, J.C., Janssens, R.A.J., Svensson, M. and Andersson, M.R.: Polymer photovoltaic devices from stratified multilayers of donor-acceptor blends. Adv. Mater. 12, 1367 (2000).3.0.CO;2-Z>CrossRefGoogle Scholar
141.Brabec, C.J., Cravino, A., Meissner, D., Sariciftci, N.S., Rispens, M.T., Sanchez, L., Hummelen, J.C. and Fromherz, T.: The influence of materials work function on the open circuit voltage of plastic solar cells. Thin Solid Films 403–404,368 (2002).CrossRefGoogle Scholar
142.Drees, M., Premaratne, K., Graupner, W., Heflin, J.R., Davis, R.M., Marciu, D. and Miller, M.: Creation of a gradient polymer-fullerene interface in photovoltaic devices by thermally controlled interdiffusion. Appl. Phys. Lett. 81, 1 (2002).CrossRefGoogle Scholar
143.Malliaras, G.G., Salem, J.R., Brock, P.J. and Scott, J.C.: Photovoltaic measurement of the built-in potential in organic light emitting diodes and photodiodes. J. Appl. Phys. 84, 1583 (1998).CrossRefGoogle Scholar
144.Brabec, C.J., Cravino, A., Meissner, D., Sariciftci, N.S., Fromherz, T., Rispens, M.T., Sanchez, L. and Hummelen, J.C.: Origin of the open circuit voltage of plastic solar cells. Adv. Funct. Mater. 11, 374 (2001).3.0.CO;2-W>CrossRefGoogle Scholar
145.Mihailetchi, V.D., Blom, P.W.M., Hummelen, J.C. and Rispens, M.T.: Cathode dependence of the open-circuit voltage of polymer:fullerene bulk heterojunction solar cells. J. Appl. Phys. 94, 6849 (2003).CrossRefGoogle Scholar
146.Campbell, I.H., Rubin, S., Zawodzinski, T.A., Kress, J.D., Martin, R.L., Smith, D.L., Barashkov, N.N. and Ferraris, J.P.: Controlling Schottky energy barriers in organic electronic devices using self-assembled monolayers. Phys. Rev. B 54, 14321 (1996).CrossRefGoogle ScholarPubMed
147.Heller, C.M., Campbell, I.H., Smith, D.L., Barashkov, N.N. and Ferraris, J.P.: Chemical potential pinning due to equilibrium electron transfer at metal/C 60-doped polymer interfaces. J. Appl. Phys. 81, 3227 (1996).CrossRefGoogle Scholar
148.Hirose, Y., Kahn, A., Aristov, V., Soukiassian, P., Bulovic, V. and Forrest, S.R.: Chemistry and electronic properties of metal-organic semiconductor interfaces: Al, Ti, In, Sn, Ag, and Au on PTCDA. Phys. Rev. B 54, 13748 (1996).CrossRefGoogle ScholarPubMed
149.Ishii, H., Sugiyama, K., Ito, E. and Seki, K.: Energy level alignment and interfacial electronic structures at organic/metal and organic/organic interfaces. Adv. Mater. 11, 605 (1999).3.0.CO;2-Q>CrossRefGoogle Scholar
150.Yan, L. and Gao, Y.: Interfaces in organic semiconductor devices. Thin Solid Films 417, 101 (2002).CrossRefGoogle Scholar
151.Koch, N., Kahn, A., Ghijsen, J., Pireaux, J-J., Schwartz, J., Johnson, R.L. and Elschner, A.: Conjugated organic molecules on metal versus polymer electrodes: Demonstration of a key energy level alignment mechanism. Appl. Phys. Lett. 82, 70 (2003).CrossRefGoogle Scholar
152.Cahen, D. and Kahn, A.: Electron energetics at surfaces and interfaces: Concepts and experiments. Adv. Mater. 15, 271 (2003).CrossRefGoogle Scholar
153.Veenstra, S.C. and Jonkman, H.T.: Energy-level alignment at metal-organic and organic-organic interfaces. J. Polym. Sci Polym. Phys. 41, 2549 (2003).CrossRefGoogle Scholar
154.Veenstra, S.C., Heeres, A., Hadziioannou, G., Sawatzky, G.A. and Jonkman, H.T.: On interface dipole layers between C60 and Ag or Au. Appl. Phys. A 75, 661 (2002).CrossRefGoogle Scholar
155.Melzer, C., Krasnikov, V.V. and Hadziioannou, G.: Organic donor/acceptor photovoltaics: The role of C60/metal interfaces. Appl. Phys. Lett. 82, 3101 (2003).CrossRefGoogle Scholar
156.Wu, C.C., Wu, C.I., Sturm, J.C. and Kahn, A.: Surface modification of indium tin oxide by plasma treatment: An effective method to improve the efficiency, brightness, and reliability of organic light-emitting devices. Appl. Phys. Lett. 70, 1348 (1997).CrossRefGoogle Scholar
157.Sugiyama, K., Ishii, H., Ouchi, Y. and Seki, K.: Dependence of indium–tin–oxide work function on surface cleaning method as studied by ultraviolet and x-ray photoemission spectroscopies. J. Appl. Phys. 87, 295 (2000).CrossRefGoogle Scholar
158.Scott, J.C., Carter, S.A., Karg, S. and Angelopoulos, M.: Polymeric anodes for organic light-emitting diodes. Synth. Met. 85, 1197 (1997).CrossRefGoogle Scholar
159.Cao, Y., Yu, G., Zhang, C., Menon, R. and Heeger, A.J.: Polymer light-emitting diodes with polyethylene dioxythiophene–polystyrene sulfonate as the transparent anode. Synth. Met. 87, 171 (1997).CrossRefGoogle Scholar
160.Brown, T.M., Kim, J.S., Friend, R.H., Cacialli, F., Daik, R. and Feast, W.J.: Built-in field electroabsorption spectroscopy of polymer light-emitting diodes incorporating a doped poly(3,4-ethylene dioxythiophene) hole-injection layer. Appl. Phys. Lett. 75, 1679 (1999).CrossRefGoogle Scholar
161.Ganzorig, C. and Fujihira, M.: Chemical modification of indium-tin-oxide electrodes by surface molecular design in Organic Optoelectronic Materials, Processing and Devices, edited by Moss, S.C.. (Mater. Res. Soc. Symp. Proc. 708, Warrendale, PA, 2002), p. 83.Google Scholar
162.Hung, L.S., Tang, C.W. and Mason, M.G.: Enhanced electron injection in organic electroluminescence devices using an Al/LiF electrode. Appl. Phys. Lett. 70, 152 (1997).CrossRefGoogle Scholar
163.Jabbour, G.E., Kawabe, Y., Shaheen, S.E., Wang, J.F., Morrell, M.M., Kippelen, B. and Peyghambarian, N.: Highly efficient and bright organic electroluminescent devices with an aluminum cathode. Appl. Phys. Lett. 71, 1762 (1997).CrossRefGoogle Scholar
164.Brabec, C.J., Shaheen, S.E., Winder, C., Sariciftci, N.S. and Denk, P.: Effect of LiF/metal electrodes on the performance of plastic solar cells. Appl. Phys. Lett. 80, 1288 (2002).CrossRefGoogle Scholar
165.Zhang, F.L., Johansson, M., Anderson, M.R., Hummelen, J.C. and Inganäs, O.: Polymer solar cells based on MEH-PPV and PCBM. Synth. Met. 137, 1401 (2003).CrossRefGoogle Scholar
166.van Duren, J.K.J., Loos, J., Morrissey, F., Leewis, C.M., Kivits, K.P.H., van IJzendoorn, L.J., Rispens, M.T., Hummelen, J.C. and Janssen, R.A.J.: In-situ compositional and structural analysis of plastic solar cells. Adv. Funct. Mater. 12, 665 (2002).3.0.CO;2-J>CrossRefGoogle Scholar
167.Bulle-Lieuwma, C.W.T., van Gennip, W.J.H., van Duren, J.K.J., Jonkheijm, P., Janssen, R.A.J. and Niemantsverdriet, J.W.: Characterization of polymer solar cells by TOF-SIMS depth profiling. Appl. Surf. Sci. 203, 547 (2003).CrossRefGoogle Scholar
168.Kim, H., Jin, S-H., Suh, H. and Lee, K. Origin of the open circuit voltage in conjugated polymer-fullerene photovoltaic cells. In Organic Photovoltaics IV, edited by Kafafi, Z.H., and Lane, P.A., Proceedings of the SPIE, Vol. 5215, (SPIE, Bellingham, WA, 2004), p. 111,Google Scholar
169.Gao, J., Hide, F. and Wang, H.: Efficient photodetectors and photovoltaic cells from composites of fullerenes and conjugated polymers: Photoinduced electron transfer. Synth. Met. 84, 979 (1997).Google Scholar
170.Liu, J., Shi, Y. and Yang, Y.: Solvation-induced morphology effects on the performance of polymer-based photovoltaic devices. Adv. Funct. Mater. 11, 420 (2001).3.0.CO;2-K>CrossRefGoogle Scholar
171.Scharber, M.C., Schulz, N.A., Sariciftci, N.S. and Brabec, C.J.: Optical- and photocurrent-detected magnetic resonance studies on conjugated polymer/fullerene composites. Phys. Rev. B 67, 085202 (2003).CrossRefGoogle Scholar
172.Hoppe, H., Niggemann, M., Winder, C., Kraut, J., Hiesgen, R., Hinsch, A., Meissner, D. and Sariciftci, N.S. Nanoscale morphology of conjugated polymer/fullerene based bulk-heterojunction solar cells. Adv. Funct. Mater. (2004)Google Scholar
173.Frohne, H., Shaheen, S.E., Brabec, C.J., Müller, D.C., Sariciftci, N.S. and Meerholz, K.: Influence of the anodic work function on the performance of organic solar cells. Chem Phys Chem. 9, 795 (2002).3.0.CO;2-A>CrossRefGoogle Scholar
174.Ramsdale, C.M., Barker, J.A., Arias, A.C., MacKenzie, J.D., Friend, R.H. and Greenham, N.C.: The origin of the open circuit voltage in polyfluorene-based photovoltaic devices. J. Appl. Phys. 92, 4266 (2002).CrossRefGoogle Scholar
175.Barker, J.A., Ramsdale, C.M. and Greenham, N.C.: Modeling the current-voltage characteristics of bilayer polymer photovoltaic devices. Phys. Rev. B 67, 075205 (2003).CrossRefGoogle Scholar
176.Riedel, I., Parisi, J., Dyakonov, V., Lutsen, L., Vanderzande, D. and Hummelen, J.C.: Effect of temperature and illumination on the electrical characteristics of polymer-fullerene bulk-heterojunction solar cells. Adv. Funct. Mater. 14, 38 (2004).CrossRefGoogle Scholar
177.Schilinsky, P., Waldauf, C., Hauch, J. and Brabec, C.J.: Simulation of light intensity dependent current characteristics of polymer solar cells. J. Appl. Phys. 95, 2816 (2004).CrossRefGoogle Scholar
178.Hoppe, H., Arnold, N., Meissner, D. and Sariciftci, N.S.: Modelling the optical absorption within conjugated polymer/fullerene-based bulk-heterojunction organic solar cells. Sol. Energy Mater. Sol. Cells 80,105 (2003).CrossRefGoogle Scholar
179.Drechsel, J., Maennig, B., Gebeyehu, D., Pfeiffer, M., Leo, K. and Hoppe, H.: MIP-type organic solar cells incorporating phthalocyanine/fullerene mixed layers and doped wide-gap transport layers. Org. Electron. 5, 175 (2004).CrossRefGoogle Scholar
180.Hoppe, H., Arnold, N., Meissner, D. and Sariciftci, N.S.: Modeling of optical absorption in conjugated polymer/fullerene bulk-heterojunction plastic solar cells. Thin Solid Films 451, 589 (2004).CrossRefGoogle Scholar
181.Riedel, I. and Dyakonov, V. Influence of electronic transport properties of polymer-fullerene blends on the performance of bulk heterojunction photovoltaic devices. Phys. Status Solidi A 201, 1332 (2004)Google Scholar
182.Shaheen, S.E., Jabbour, G.E., Morrell, M.M., Kawabe, Y., Kippelen, B., Peyghambarian, N., Nabor, M-F., Schlaf, R., Mash, E.A. and Armstrong, N.R.: Bright blue organic light-emitting diode with improved color purity using a LiF/Al cathode. J. Appl. Phys. 84, 2324 (1998).CrossRefGoogle Scholar
183.Brown, T.M., Friend, R.H., Millard, I.S., Lacey, D.J., Burroughes, J.H. and Cacialli, F.: LiF/Al cathodes and the effect of LiF thickness on the device characteristics and built-in potential of polymer light-emitting diodes. Appl. Phys. Lett. 77, 3096 (2000).CrossRefGoogle Scholar
184.Kugler, T., Salaneck, W.R., Rost, H. and Holmes, A.B.: Polymer band alignment at the interface with indium tin oxide: Consequences for light emitting devices. Chem. Phys. Lett. 310, 391 (1999).CrossRefGoogle Scholar
185.Greczynski, G., Kugler, T. and Salaneck, W.R.: Energy level alignment in organic-based three-layer structures studied by photoelectron spectroscopy. J. Appl. Phys. 88,7187 (2000).CrossRefGoogle Scholar
186.Kim, J.Y., Jung, J.H., Lee, D.E. and Joo, J.: Enhancement of electrical conductivity of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) by a change of solvents. Synth. Met. 126, 311 (2002).CrossRefGoogle Scholar
187.Jönssona, S.K.M., Birgerson, J., Crispin, X., Greczynski, G., Osikowicz, W., van der Gonc, A.W.D., Salaneck, W.R. and Fahlman, M.: The effects of solvents on the morphology and sheet resistance in poly(3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT–PSS) films. Synth. Met. 139, 1 (2003).CrossRefGoogle Scholar
188.Kuhnke, K., Becker, R., Epple, M. and Kern, K.: C60 exciton quenching near metal surfaces. Phys. Rev. Lett. 79, 3246 (1997).CrossRefGoogle Scholar
189.Würfel, P.: Thermodynamic limitations to solar energy conversion. Physica E 14, 18 (2002).CrossRefGoogle Scholar
190.Yakimov, A. and Forrest, S.R.: High photovoltage multiple-heterojunction organic solar cells incorporating interfacial metallic nanoclusters. Appl. Phys. Lett. 80, 1667 (2002).CrossRefGoogle Scholar
191.Roman, L.S., Inganäs, O., Granlund, T., Nyberg, T., Svensson, M., Andersson, M.R. and Hummelen, J.C.: Trapping light in polymer photodiodes with soft embossed gratings. Adv. Mater. 12, 189 (2000).3.0.CO;2-2>CrossRefGoogle Scholar
192.Niggemann, M., B. Bläsi, Gombert, A., Hinsch, A., Hoppe, H., Lalanne, P., Meissner, D., and Wittwer, V.: Trapping light in organic plastic solar cells with integrated diffraction gratings, presented at the 17th European Photovoltaic Solar Energy Conference, Munich, Germany, 2001.Google Scholar
193.Dhanabalan, A., van Duren, J.K.J., van Hal, P.A., van Dongen, J.L.J. and Janssen, R.A.J.: Synthesis and characterization of a low bandgap conjugated polymer for bulk heterojunction photovoltaic cells. Adv. Funct. Mater. 11, 255 (2001).3.0.CO;2-I>CrossRefGoogle Scholar
194.van Duren, J.K.J., Dhanabalan, A., van Hal, P.A. and Janssen, R.A.J.: Low-bandgap polymer photovoltaic cells. Synth. Met. 121, 1587 (2001).CrossRefGoogle Scholar
195.Brabec, C.J., Winder, C., Sariciftci, N.S., Hummelen, J.C., Dhanabalan, A., van Hal, P.A. and Janssen, R.A.J.: A low-bandgap semiconducting polymer for photovoltaic devices and infrared emitting diodes. Adv. Funct. Mater. 12, 709 (2002).3.0.CO;2-N>CrossRefGoogle Scholar
196.Colladet, K., Nicolas, M., Goris, L., Lutsen, L. and Vanderzande, D.: Low-band gap polymers for photovoltaic applications. Thin Solid Films 451–452, 7 (2004).CrossRefGoogle Scholar
197.Camaioni, N., Catellani, M., Luzzati, S. and Migliori, A.: Morphological characterization of poly(3-octylthiophene):plasticizer:C60 blends. Thin Solid Films 403–404, 489 (2002).CrossRefGoogle Scholar
198.Rispens, M.T., Meetsma, A., Rittberger, R., Brabec, C.J., Sariciftci, N.S. and Hummelen, J.C.: Influence of the solvent on the crystal structure of PCBM and the efficiency of MDMO-PPV:PCBM ‘plastic’ solar cells. Chem. Commun. 17, 2116 (2003).CrossRefGoogle Scholar
199.Halls, J.J.M., Arias, A.C., MacKenzie, J.D., Wu, W., Inbasekaran, M., Woo, E.P. and Friend, R.H.: Photodiodes based on polyfluorene composites: Influence of morphology. Adv. Mater. 12, 498 (2000).3.0.CO;2-H>CrossRefGoogle Scholar
200.Martens, T., Beelen, Z., D’Haen, J., Munters, T., Goris, L., Manca, J., D’Olieslaeger, M., Vanderzande, D., Schepper, L.D. and Andriessen, R. Morphology of MDMO-PPV:PCBM bulk hetero-junction organic solar cells studied by AFM, KFM and TEM. In Organic Photovoltaics III, edited by Kafafi, Z.H. and Fichou, D., Proceedings of SPIE Vol. 4801 (SPIE, Bellingham, WA, 2003), p. 40CrossRefGoogle Scholar
201.Arias, A.C., Corcoran, N., Banach, M., Friend, R.H., MacKenzie, J.D. and Huck, W.T.S.: Vertically segregated polymer-blend photovoltaic thin-film structures through surface-mediated solution processing. Appl. Phys. Lett. 80, 1695 (2002).CrossRefGoogle Scholar
202.Camaioni, N., Ridolfi, G., Casalbore-Miceli, G., Possamai, G. and Maggini, M.: The effect of a mild thermal treatment on the performance of poly(3-alkylthiophene)/fullerene solar cells. Adv. Mater. 14, 1735 (2002).3.0.CO;2-O>CrossRefGoogle Scholar
203.Hiramoto, M., Suemori, K. and Yokoyama, M.: Photovoltaic properties of ultramicrostructure controlled organic co-deposited films. Jpn. J. Appl. Phys. 41, 2763 (2002).CrossRefGoogle Scholar
204.Martens, T., D’Haen, J., Munters, T., Beelen, Z., Goris, L., Manca, J., D’Olieslaeger, M., Vanderzande, D., Schepper, L.D. and Andriessen, R.: Disclosure of the nanostructure of MDMO-PPV:PCBM bulk heterojunction organic solar cells by a combination of SPM and TEM. Synth. Met. 138, 243 (2003).CrossRefGoogle Scholar
205.Snaith, H.J., Arias, A.C., Morteani, A.C., Silva, C. and Friend, R.H.: Charge generation kinetics and transport mechanisms in blended polyfluorene photovoltaic devices. Nano Lett. 2, 1353 (2003).CrossRefGoogle Scholar
206.Eckert, J-F., Nicoud, J-F., Nierengarten, J-F., Liu, S-G., Echegoyen, L., Barigelletti, F., Armaroli, N., Ouali, L., Krasnikov, V. and Hadziioannou, G.: Fullerene-oligophenylenevinylene hybrids: Synthesis, electronic properties, and incorporation in photovoltaic devices. J. Am. Chem. Soc. 122, 7467 (2000).CrossRefGoogle Scholar
207.Dhanabalan, A., Knol, J., Hummelen, J.C. and Janssen, R.A.J.: Design and synthesis of new processible donor-acceptor dyad and triads. Synth. Met. 119, 519 (2001).CrossRefGoogle Scholar
208.Otsubo, T., Aso, Y. and Takimiya, K.: Functional oligothiophenes as advanced molecular electronic materials. J. Mater. Chem. 12, 2565 (2002).CrossRefGoogle Scholar
209.Possamai, G., Camaioni, N., Ridolfi, G., Franco, L., Ruzzi, M., Menna, E., Casalbore-Miceli, G., Fichera, A.M., Scorrano, G., Corvaja, C. and Maggini, M.: A fullerene-azothiophene dyad for photovoltaics. Synth. Met. 139, 585 (2003).CrossRefGoogle Scholar
210.Loi, M.A., Denk, P., Hoppe, H., Neugebauer, H., Winder, C., Meissner, D., Brabec, C., Sariciftci, N.S., Gouloumis, A., Vazquez, P. and Torres, T.: Long-lived photoinduced charge separation for solar cell applications in phthalocyanine-fulleropyrrolidine dyad thin films. J. Mater. Chem. 13, 700 (2003).Google Scholar
211.Zhang, F., Svensson, M., Andersson, M.R., Maggini, M., Bucella, S., Menna, E. and Inganäs, O.: Soluble polythiophenes with pendant fullerene groups as double cable materials for photodiodes. Adv. Mater. 13, 1871 (2001).3.0.CO;2-3>CrossRefGoogle Scholar
212.Cravino, A., Zerza, G., Maggini, M., Bucella, S., Svensson, M., Andersson, M.R., Neugebauer, H., Brabec, C.J. and Sariciftci, N.S.: A soluble donor-acceptor double-cable polymer: Polythiophene with pendant fullerenes. Monatsh. Chem. 134, 519 (2003).CrossRefGoogle Scholar
213.Park, C., Yoon, J. and Thomas, E.L.: Enabling nanotechnology with self assembled block copolymer patterns. Polymer 44, 6725 (2003).CrossRefGoogle Scholar
214.Stalmach, U., de Boer, B., Videlot, C., van Hutten, P.F. and Hadziioannou, G.: Semiconducting diblock copolymers synthesized by means of controlled radical polymerization techniques. J. Am. Chem. Soc. 122, 5464 (2000).CrossRefGoogle Scholar
215.Hadziioannou, G.: Semiconducting block copolymers for self-assembled photovoltaic devices. MRS Bull. 27, 456 (2002).CrossRefGoogle Scholar
216.Sun, S.S., Fan, Z., Wang, Y., Taft, C., Haliburton, J. and Maaref, S. Synthesis and characterization of a novel -D-B-A-B- block copolymer system for potential light harvesting applications. In Organic Photovoltaics III, edited by Kafafi, Z.H. and Fichou, D., Proceedings of SPIE Vol. 4801 (SPIE, Bellingham, WA, 2003), p. 114.CrossRefGoogle Scholar
217.Kietzke, T., Neher, D., Landfester, K., Montenegro, R., Güntner, R. and Scherf, U.: Novel approaches to polymer blends based on polymer nanoparticles. Nature Mater. 2, 408 (2003).CrossRefGoogle ScholarPubMed
218.Coakley, K.M., Liu, Y., McGehee, M.D., Frindell, K. and Stucky, G.D.: Infiltrating semiconducting polymers into self-assembled mesoporous titania films for photovoltaic applications. Adv. Funct. Mater. 13, 301 (2003).CrossRefGoogle Scholar
219.Coakley, K.M. and McGehee, M.D.: Photovoltaic cells made from conjugated polymers infiltrated into mesoporous titania. Appl. Phys. Lett. 83, 1 (2003).CrossRefGoogle Scholar
220.Peng, X., Manna, L., Yang, W., Wickham, J., Scher, E., Kadavanich, A. and Alivisatos, A.P.: Shape control of CdSe nanocrystals. Nature 404, 59 (2000).CrossRefGoogle ScholarPubMed
221.Milliron, D.J., Pitois, C., Edder, C., Frechet, J.M.J. and Alivisatos, A.P. Designed for charge transfer: complexes of CdSe nanocrystals and oligothiophenes, in Organic and Polymeric Materials and Devices—Optical, Electrical, and Optoelectric Properties, edited by Jabbour, G.E., Carter, S.A., Kido, J., Lee, S-T., and Sariciftci, N.S.. (Mater. Res. Soc. Symp. Proc. 725, Warrendale, PA, 2002), p. 177.Google Scholar