Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-31T23:27:44.708Z Has data issue: false hasContentIssue false
  • English
  • Français

Nanomorphology of P3HT:PCBM-Based Absorber Layers of Organic Solar Cells after Different Processing Conditions Analyzed by Low-Energy Scanning Transmission Electron Microscopy

Published online by Cambridge University Press:  20 November 2012

Marina Pfaff ,
Michael F.G. Klein ,
Erich Müller ,
Philipp Müller ,
Alexander Colsmann ,
Uli Lemmer  and
Dagmar Gerthsen
Marina Pfaff*
Affiliation:
Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT), Engesserstraße 7, 76131 Karlsruhe, Germany Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, 76131 Karlsruhe, Germany
Michael F.G. Klein
Affiliation:
Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstraße 13, 76131 Karlsruhe, Germany
Erich Müller
Affiliation:
Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT), Engesserstraße 7, 76131 Karlsruhe, Germany Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, 76131 Karlsruhe, Germany
Philipp Müller
Affiliation:
Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT), Engesserstraße 7, 76131 Karlsruhe, Germany Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, 76131 Karlsruhe, Germany
Alexander Colsmann
Affiliation:
Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstraße 13, 76131 Karlsruhe, Germany
Uli Lemmer
Affiliation:
Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, 76131 Karlsruhe, Germany Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstraße 13, 76131 Karlsruhe, Germany
Dagmar Gerthsen
Affiliation:
Laboratory for Electron Microscopy (LEM), Karlsruhe Institute of Technology (KIT), Engesserstraße 7, 76131 Karlsruhe, Germany Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, 76131 Karlsruhe, Germany
*
*Corresponding author. E-mail: [email protected]
Get access

Abstract

In this study the nanomorphology of P3HT:PC61BM absorber layers of organic solar cells was studied as a function of the processing parameters and for P3HT with different molecular weight. For this purpose we apply scanning transmission electron microscopy (STEM) at low electron energies in a scanning electron microscope. This method exhibits sensitive material contrast in the high-angle annular dark-field (HAADF) mode, which is well suited to distinguish materials with similar densities and mean atomic numbers. The images taken with low-energy HAADF STEM are compared with conventional transmission electron microscopy and atomic force microscopy images to illustrate the capabilities of the different techniques. For the interpretation of the low-energy HAADF STEM images, a semiempirical equation is used to calculate the image intensities. The experiments show that the nanomorphology of the P3HT:PC61BM blends depends strongly on the molecular weight of the P3HT. Low-molecular-weight P3HT forms rod-like domains during annealing. In contrast, only small globular features are visible in samples containing high-molecular-weight P3HT, which do not change significantly after annealing at 150°C up to 30 min.

Keywords

scanning transmission electron microscopylow electron energyHAADForganic solar cellP3HTPCBMnanomorphology
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 18 , Issue 6 , December 2012 , pp. 1380 - 1388
Copyright
Copyright © Microscopy Society of America 2012

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.)

References

Ballantyne, A.M., Ferenczi, T.A.M., Campoy-Quiles, M., Clarke, T.M., Maurano, A., Wong, K.H., Zhang, W.M., Stingelin-Stutzmann, N., Kim, J.S., Bradley, D.D.C., Durrant, J.R., McCulloch, I., Heeney, M., Nelson, J., Tierney, S., Duffy, W., Mueller, C. & Smith, P. (2010). Understanding the influence of morphology on Poly(3-hexylselenothiophene):PCBM solar cells. Macromolecules 43, 1169–1174.CrossRefGoogle Scholar
Banhart, F. (1999). Irradiation effects in carbon nanostructures. Rep Prog Phys 62, 1181–1221.CrossRefGoogle Scholar
Bertho, S., Oosterbaan, W.D., Vrindts, V., D'Haen, J., Cleij, T.J., Lutsen, L., Manca, J. & Vanderzande, D. (2009). Controlling the morphology of nanofiber-P3HT:PCBM blends for organic bulk heterojunction solar cells. Org Electron 10, 1248–1251.Google Scholar
Bothe, W. (1933). Durchgang von Elektronen durch Materie. In Handbuch der Physik 22,2: Negative und positive Strahlen, Geiger, H. & Bothe, W. (Eds.), pp. 1–74. Berlin: Springer.CrossRefGoogle Scholar
Delong, A., Hladil, K., Kolařík, V. & Pavelka, P. (2000). Low voltage electron microscope I.—Design. In Conference Proceedings of the 12th European Congress on Electron Microscopy, pp. 197–198.Google Scholar
Drummy, L.F., Davis, R.J., Moore, D.L., Durstock, M., Vaia, R.A. & Hsu, J.W.P. (2010). Molecular-scale and nanoscale morphology of P3HT:PCBM bulk heterojunctions: Energy-filtered TEM and low-dose HREM. Chem Mater 23, 907–912.Google Scholar
Drummy, L.F. & Kübel, C. (2010). Polymer microscopy: Current challenges. Polym Rev 50, 231–234.Google Scholar
Haugeneder, A., Neges, M., Kallinger, C., Spirkl, W., Lemmer, U., Feldmann, J., Scherf, U., Harth, E., Gugel, A. & Mullen, K. (1999). Exciton diffusion and dissociation in conjugated polymer fullerene blends and heterostructures. Phys Rev B 59, 15346–15351.Google Scholar
Herzing, A.A., Richter, L.J. & Anderson, I.M. (2010). 3D Nanoscale characterization of thin-film organic photovoltaic device structures via spectroscopic contrast in the TEM. J Phys Chem C 114, 17501–17508.Google Scholar
Hoppe, H., Niggemann, M., Winder, C., Kraut, J., Hiesgen, R., Hinsch, A., Meissner, D. & Sariciftci, N.S. (2004). Nanoscale morphology of conjugated polymer/fullerene-based bulk-heterojunction solar cells. Adv Func Mater 14, 1005–1011.Google Scholar
Kalita, G., Masahiro, M., Koichi, W. & Umeno, M. (2010). Nanostructured morphology of P3HT:PCBM bulk heterojunction solar cells. Solid-State Electron 54, 447–451.Google Scholar
Klein, M.F.G., Pfaff, M., Müller, E., Czolk, J., Reinhard, M., Valouch, S., Lemmer, U., Colsmann, A. & Gerthsen, D. (2012). Poly(3-hexylselenophene) solar cells: Correlating the optoelectronic device performance and nanomorphology imaged by low-energy scanning transmission electron microscopy. J Polym Sci Poly Phys 50, 198–206.CrossRefGoogle Scholar
Li, G., Yao, Y., Yang, H., Shrotriya, V., Yang, G. & Yang, Y. (2007). “Solvent annealing” effect in polymer solar cells based on poly(3-hexylthiophene) and methanofullerenes. Adv Func Mater 17, 1636–1644.Google Scholar
Li, G., Zhu, R. & Yang, Y. (2012). Polymer solar cells. Nat Photonics 6, 153–161.Google Scholar
Lin, C., Lin, E.-Y. & Tsai, F.-Y. (2010). Enhanced thermal stability and efficiency of polymer bulk-heterojunction solar cells by low-temperature drying of the active layer. Adv Func Mater 20, 834–839.Google Scholar
Ma, W.L., Yang, C.Y., Gong, X., Lee, K. & Heeger, A.J. (2005). Thermally stable, efficient polymer solar cells with nanoscale control of the interpenetrating network morphology. Adv Func Mater 15, 1617–1622.Google Scholar
Mårdalen, J., Samuelsen, E.J., Gautun, O.R. & Carlsen, P.H. (1991). Chain configuration of poly(3-hexylthiophene) as revealed by detailed X-ray diffraction studies. Solid State Commun 77, 337–339.CrossRefGoogle Scholar
Michler, G.H. (2008). Phase contrast at large defocus values. In Electron Microscopy of Polymers, Pasch, H. (Ed.), p. 60. Berlin, Heidelberg, Germany: Springer.Google Scholar
Nicolet, C., Deribew, D., Renaud, C., Fleury, G., Brochon, C., Cloutet, E., Vignau, L., Wantz, G., Cramail, H., Geoghegan, M. & Hadziioannou, G. (2011). Optimization of the bulk heterojunction composition for enhanced photovoltaic properties: Correlation between the molecular weight of the semiconducting polymer and device performance. J Phys Chem B 115, 12717–12727.CrossRefGoogle ScholarPubMed
Pennycook, S.J. & Boatner, L.A. (1988). Chemically sensitive structure-imaging with a scanning-transmission electron-microscope. Nature 336, 565–567.Google Scholar
Pfaff, M., Müller, E., Klein, M.F.G., Colsmann, A., Lemmer, U., Krzyzanek, V., Reichelt, R. & Gerthsen, D. (2011). Low-energy electron scattering in carbon-based materials analyzed by scanning transmission electron microscopy and its application to sample thickness determination. J Microsc 243, 31–39.Google Scholar
Pfannmöller, M., Flügge, H., Benner, G., Wacker, I., Sommer, C., Hanselmann, M., Schmale, S., Schmidt, H., Hamprecht, F.A., Rabe, T., Kowalsky, W. & Schröder, R.R. (2011). Visualizing a homogeneous blend in bulk heterojunction polymer solar cells by analytical electron microscopy. Nano Lett 11, 3099–3107.CrossRefGoogle ScholarPubMed
Ritchie, N.W.M. (2005). A new Monte Carlo application for complex sample geometries. Surf Interf Anal 37, 1006–1011.CrossRefGoogle Scholar
Sanyal, M., Schmidt-Hansberg, B., Klein, M.F.G., Colsmann, A., Munuera, C., Vorobiev, A., Lemmer, U., Schabel, W., Dosch, H. & Barrena, E. (2011a). In situ X-ray study of drying-temperature influence on the structural evolution of bulk-heterojunction polymer–fullerene solar cells processed by doctor-blading. Adv Energy Mater 1, 363–367.Google Scholar
Sanyal, M., Schmidt-Hansberg, B., Klein, M.F.G., Munuera, C., Vorobiev, A., Colsmann, A., Scharfer, P., Lemmer, U., Schabel, W., Dosch, H. & Barrena, E. (2011b). Effect of photovoltaic polymer/fullerene blend composition ratio on microstructure evolution during film solidification investigated in real time by X-ray diffraction. Macromolecules 44, 3795–3800.CrossRefGoogle Scholar
Savenije, T.J., Kroeze, J.E., Yang, X. & Loos, J. (2006). The formation of crystalline P3HT fibrils upon annealing of a PCBM:P3HT bulk heterojunction. Thin Solid Films 511–512, 2–6.CrossRefGoogle Scholar
Schmidt-Hansberg, B., Sanyal, M., Klein, M.F.G., Pfaff, M., Schnabel, N., Jaiser, S., Vorobiev, A., Müller, E., Colsmann, A., Scharfer, P., Gerthsen, D., Lemmer, U., Barrena, E. & Schabel, W. (2011). Moving through the phase diagram: Morphology formation in solution cast polymer–fullerene blend films for organic solar cells. ACS Nano 5, 8579–8590.CrossRefGoogle ScholarPubMed
Sourty, E., van Bavel, S., Lu, K.B., Guerra, R., Bar, G. & Loos, J. (2009). High-angle annular dark field scanning transmission electron microscopy on carbon-based functional polymer systems. Microsc Microanal 15, 251–258.CrossRefGoogle ScholarPubMed
van Bavel, S.S., Bärenklau, M., de With, G., Hoppe, H. & Loos, J. (2010). P3HT/PCBM bulk heterojunction solar cells: Impact of blend composition and 3D morphology on device performance. Adv Func Mater 20, 1458–1463.Google Scholar
van Bavel, S.S., Sourty, E., de With, G. & Loos, J. (2009). Three-dimensional nanoscale organization of bulk heterojunction polymer solar cells. Nano Lett 9, 507–513.Google Scholar
Vanlaeke, P., Swinnen, A., Haeldermans, I., Vanhoyland, G., Aernouts, T., Cheyns, D., Deibel, C., D'Haen, J., Heremans, P., Poortmans, J. & Manca, J.V. (2006). P3HT/PCBM bulk heterojunction solar cells: Relation between morphology and electro-optical characteristics. Sol Energy Mat Sol Cells 90, 2150–2158.Google Scholar