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  • 1.
    Aasmundtveit, K.E.
    et al.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Samuelsen, E.J.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Guldstein, M.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Steinsland, C.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Flornes, O.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Fagermo, C.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Seeberg, T.M.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., N-7491 Trondheim, Norway.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Feidenhans'l, R.
    Forskningscenter Risø, DK-4000 Roskilde, Denmark.
    Ferrer, S.
    Europ. Synchrt. Radiation Facility, BP 220, F-38043 Grenoble Cedex, France.
    Structural anisotropy of poly(alkylthiophene) films2000In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 33, no 8, p. 3120-3127Article in journal (Refereed)
    Abstract [en]

    The structural anisotropy of various poly(alkylthiophene) films have been studied by X-ray diffraction, using both conventional methods and synchrotron radiation at grazing incidence. Solution-cast films orient with the side chains preferably normal to the film surface, whereas spin-cast films of nonstereoregular material orient with both the main and the side chains in the film plane. For thick (10-50 µm) solution-cast films, the degree of orientation depends strongly on the solvent used for casting, and on the stereoregularity of the polymer, films of stereoregular materials being more oriented than those of nonregular materials. The most oriented nonregular films are those cast from mixtures of chloroform and tetrahydrofuran. Thin (50-500 nm) solution-cast films are more oriented than the thicker ones, and the effects of different stereoregularity or different casting solvents are small. For spin-cast films, the degree of orientation is independent of substrate and solvent. Spin-cast films of stereoregular material have two different phases: One with the side chains normal to the substrate, and another where they are parallel to the substrate. The diffraction peaks of spin-cast poly(octylthiophene) narrow considerably upon heating.

  • 2.
    Aasmundtveit, K.E.
    et al.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., Trondheim, Norway.
    Samuelsen, E.J.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskapelige U., Trondheim, Norway.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Johansson, Tomas
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Ferrer, S.
    Europ. Synchrt. Radiat. Facil. (E., F-38043, Grenoble, France.
    Structural aspects of electrochemical doping and dedoping of poly(3,4-ethylenedioxythiophene)2000In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 113, no 1, p. 93-97Article in journal (Refereed)
    Abstract [en]

    Electrochemical dedoping and redoping of p-toluene sulfonate doped poly(3,4-ethylenedioxythiophene) (PEDOT) has been studied with in situ grazing incidence diffraction with water used as an electrolyte. The diffraction peak positions and integrated intensities do not change significantly during doping and dedoping, while the peak widths increase upon dedoping and decrease upon doping. This implies that the lattice parameters and the relative positions of the polymer chains and the p-toluene sulfonate ions remain unchanged, the redox processes being carried out by the motion of smaller ions between the polymer and the electrolyte, and that the structural order decreases upon dedoping and increases upon doping in a reversible manner.

  • 3.
    Aasmundtveit, K.E.
    et al.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskaplige U., N-7491 Trondheim, Norway.
    Samuelsen, E.J.
    Institutt for Fysikk, Norges Tekn.-Naturvitenskaplige U., N-7491 Trondheim, Norway.
    Mammo, W.
    Institutionen för Organisk Kemi, Chalmers Tekniska Hôgskola, S-412 96 Göteborg, Sweden.
    Svensson, M.
    Institutionen för Organisk Kemi, Chalmers Tekniska Hôgskola, S-412 96 Göteborg, Sweden.
    Andersson, M.R.
    Institutionen för Polymerteknik, Chalmers Tekniska Hôgskola, S-412 96 Göteborg, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Structural ordering in phenyl-substituted polythiophenes2000In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 33, no 15, p. 5481-5489Article in journal (Refereed)
    Abstract [en]

    Various substituted poly(phenylthiophene)s have been studied by X-ray diffraction. They are semicrystalline, with very different degrees of crystallinity. Those with para-substituted phenyl groups have a low degree of crystallinity, whereas those with ortho-substituted phenyl groups are more crystalline. The most crystalline materials in this study have two equally long substituents on the phenyl ring, one at the ortho position and the other at the ortho or meta position on the opposite side of the phenyl ring. Poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) was most thoroughly studied, and a structural model is proposed. The structure of PDOPT is quite different from previously studied substituted polythiophenes in that the octyl side chains are directed normal to the thiophene planes. In this way, the conjugated polymer chains are kept separated from each other. Solution-cast and spin-cast PDOPT films are anisotropic, with the octyl side chains oriented normal to the film surface in both cases. This is contrary to the situation for poly(3-alkylthiophene)s, where solution-cast and spin-cast films orient in different ways.

  • 4.
    Godovsky, D
    et al.
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Chalmers Univ Technol, Gothenburg, Sweden Univ Groningen, Stratingh Inst & Mat Sci Ctr, NL-9747 AG Groningen, Netherlands.
    Chen, LC
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Andersson, MR
    Hummelen, JC
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Chalmers Univ Technol, Gothenburg, Sweden Univ Groningen, Stratingh Inst & Mat Sci Ctr, NL-9747 AG Groningen, Netherlands.
    The use of combinatorial materials development for polymer solar cells2000In: Advanced Materials for Optics and Electronics, ISSN 1057-9257, E-ISSN 1099-0712, Vol. 10, no 2, p. 47-54Article in journal (Refereed)
    Abstract [en]

    Vile use a combinatorial approach to develop molecular plastic solar cells based on soluble fullerene derivatives blended with conjugated polymers. A combinatorial way of sample preparation is well suited to deal with the multitude of possible combinations of the components of such blends. We use high mobility poly(thiophene) and poly(phenylenevinylene) derivatives to be combined with accepters, Gradients of methanofullerene/polymer concentration were formed by diusion of the low molecular weight component in the spin-cast polymer matrix, Likewise the gradients of zinc phthalocyanine/C-60 were prepared by co-evaporation of the two materials from two sources to make a linear array of photodiode devices, Photo- and electrophysical properties, such as absorption, luminescence, short circuit photocurrent and open circuit photovoltage, were measured using a specially designed installation with a resolution of 70-100 mu. Clear evidence was obtained that the photoconversion efficiency increased with the amount of methanofullerene up to very high levels, in the case of methanofullerene/polymer blends, verifying the important role of the acceptor in the photoconversion. By choosing the optimal ratio between C-60 and ZnPc in the evaporated layer it Is possible to obtain high photocurrent in the 600-700 nm range, due to the added contribution from photoinduced electron transfer between the two molecules, Copyright (C) 2000 John Wiley & Sons, Ltd.

  • 5.
    Granlund, T
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden Chalmers Univ Technol, Dept Organ Chem & Polymer Technol, S-41296 Gothenburg, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Andersson, MR
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Luminescence probing of crystallization in a polymer film2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 12, p. 8549-8556Article in journal (Refereed)
    Abstract [en]

    We report studies of a thin film multilayer stack including a highly emissive substituted polythiophene, poly[3-(2,5-dioctylphenyl)thiophene]. Analysis of the photoluminescence spectra revealed an inhomogeneous polymer film. X-ray diffraction studies attribute the existence of an inhomogeneous film as originating from crystallization of the polymer. We used the interference effect of light to detect the region of crystallization in the film. Photoluminescence and absorption were redshifted upon crystallization and displayed an enhanced vibronic structure. Comparison between calculated and measured photoluminescence shows that the crystallization starts from the top of the film and not from the supporting substrate. (C) 2000 American Institute of Physics. [S0021- 8979(00)08112-3].

  • 6.
    Granlund, T
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, S-58183 Linkoping, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Determination of the emission zone in a single-layer polymer light-emitting diode through optical measurements2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, no 11, p. 5897-5902Article in journal (Refereed)
    Abstract [en]

    We study the emission zone in a single-layer polymer light-emitting diode. The emission zone is found by studying the angular distribution of the electroluminescence. The emission is modeled by accounting for optical interference. We account for birefringence of the anode layer in our model. The active polymer was, however, found to be isotropic. The anode consists of a single-layer of the conducting polymer complex poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) (PEDOT-PSS), with enhanced conductivity. As a cathode we use plain aluminum. By using only PEDOT-PSS we avoid having a thin metal layer or indium-tin-oxide as the anode in the path of the escaping light. The active material is a substituted polythiophene with excellent film forming properties. A comparison between the experimental and calculated angular distribution of light emission from a single-layered polymer light-emitting diode was shown to be in good agreement for the spectral region studied. By assuming a distribution of the emission zone, we deduce the position as well as the width of the zone. (C) 2001 American Institute of Physics.

  • 7. Greczynski, G.
    et al.
    Johansson, N.
    Logdlund, M.
    Lögdlund, M., ACREO AB, S-602 21 Norrköping, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Horsburgh, L.E.
    Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
    Monkman, A.P.
    Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
    Dos, Santos D.A.
    Dos Santos, D.A., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721-0041, United States.
    Electronic structure of pristine and sodium doped poly(p-pyridine)2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 114, no 9, p. 4243-4252Article in journal (Refereed)
    Abstract [en]

    Ultraviolet spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS) were used to study the valence electronic structures of pristine and sodium doped poly (p-pyridine) (PPY). The UPS spectra were analyzed by studying the density-of-valence-states (DOVS) derived from quantum chemical calculations. The electronic band structure of the PPY chains was also theoretically investigated using the valence effective Hamiltonian (VEH) method. The theoretical approach was found to be more accurate in describing the electronic structure of PPY.

  • 8.
    Johansson, Tomas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Conductivity of de-doped poly(3,4-ethylenedioxythiophene)2002In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 129, no 3, p. 269-274Article in journal (Refereed)
    Abstract [en]

    The conductivity of chemically and electrochemically de-doped poly(3,4-ethylenedioxythiophene) (PEDOT) has been investigated in situ. We observe a decrease in the conductivity by 4-5 orders of magnitude. The change of conductivity is correlated to the change of electronic structure. We obtain the dielectric function of the polymer by spectroscopic ellipsometry and note that anisotropy is observed in both doped and neutral states. © 2002 Elsevier Science B.V. All rights reserved.

  • 9.
    Marcus, Carina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    UTD analysis of faceted conformal antenna arrays of dipoles2005In: European Workshop on Conformal Antennas,2005, Stockholm: Universitetsservice US AB , 2005, p. 23-Conference paper (Refereed)
  • 10.
    Martin, T
    et al.
    Linkoping Inst Technol, Dept Microwave Technol, FOA Def Res Estab, S-58111 Linkoping, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Dispersion compensation for Huygens' sources and far-zone transformation in FDTD2000In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 48, no 4, p. 494-501Article in journal (Refereed)
    Abstract [en]

    The equivalence principle is utilized for generation of both incident plane waves and for near- to far-zone transformation in the finite-difference time-domain (FDTD) method. Small errors will appear due to numerical dispersion when a plane wave is generated by Huygens' sources using an analytical expression fur the incident field. These errors can be derived from the numerical dispersion relation in the frequency domain. By using a second-order approximation of the numerical wavenumber it is shown that a simple approximative time-domain compensation procedure for the dispersion can be derived. This has been implemented in a Huygens' source routine and in a time-domain near- to far-zone transformation routine. It is shown that this compensation significantly reduces the errors produced when calculating far-zone scattered fields of low amplitude. It is also shown that it is sufficient to compensate either the Huygens' sources or the time-domain near- to Far-zone transformation with respect to dispersion. For validation, plane wave propagation through empty space and scattering of a dipole have been studied.

  • 11.
    Pettersson, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Ghosh, S.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Optical anisotropy in thin films of poly(3,4-ethylenedioxythiophene)- poly(4-styrenesulfonate)2002In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 3, no 3-4, p. 143-148Article in journal (Refereed)
    Abstract [en]

    Anisotropic optical constants spectrum of spin-coated thin films of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate) (PEDOT-PSS) from 200 to 1700 nm were determined using variable-angle spectroscopic ellipsometry and polarized intensity transmission data together with absorption spectroscopy. PEDOT-PSS was found to be very anisotropic, uniaxial with the optic axis parallel to the surface normal. The result is in good agreement with results obtained of chemically polymerized PEDOT layers doped with toluenesulfonate. By adding sorbitol to the PEDOT-PSS dispersion before spin-coating, layers with a higher conductivity were obtained. A detailed study was made of the optical response of these layers in comparison to the PEDOT-PSS prepared from dispersions without sorbitol. The optical anisotropy is important to consider when using PEDOT-PSS in optoelectronic devices, such as polymer light-emitting diodes and photovoltaic devices. © 2002 Elsevier Science B.V. All rights reserved.

  • 12.
    Pettersson, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Roman, L.S.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Quantum efficiency of exciton-to-charge generation in organic photovoltaic devices2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, no 10, p. 5564-5569Article in journal (Refereed)
    Abstract [en]

    We present an analysis of the internal monochromatic quantum efficiency of photovoltaic devices based on polymer and polymer/fullerene thin films. A quantum efficiency of exciton-to-charge generation is defined as the external monochromatic quantum efficiency normalized to the absorption in the active materials of the device. An upper limit of the efficiency can be determined, and results show that much of the light is absorbed in photoactive layers of the device, whereas only a fraction of the generated excitons is converted to charge carriers and can be collected as photocurrent. © 2001 American Institute of Physics.

  • 13.
    Samuelsen, E.J.
    et al.
    Department of Physics, Norwegian University for Science and Technology (NTNU), N-7491 Trondheim, Norway.
    Monkman, A.P.
    OEM Group, Department of Physics, University of Durham, Durham DH1 2UE, United Kingdom.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Horsburgh, L.E.
    OEM Group, Department of Physics, University of Durham, Durham DH1 2UE, United Kingdom.
    Aasmundtveit, K.E.
    Department of Physics, Norwegian University for Science and Technology (NTNU), N-7491 Trondheim, Norway.
    Ferrer, S.
    Experimental Division, ESRF, F-38043 Grenoble, France.
    The structure of polypyridine2001In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 124, no 2-3, p. 393-398Article in journal (Refereed)
    Abstract [en]

    X-ray diffraction on samples in the form of a deposited thin layer, a crushed powder and a flake were used to deduce models for the crystalline structure of polypyridine (-(C5H3N)n-), a conjugated polymer of great interest for applications. A monoclinic unit cell with lattice parameters a = 7.47 Å, b = 5.83 Å, c = 4.25 Å, ? = 108.7° containing two chains running along the c-axis and with the molecular plane normal to the a-axis gives a good fit with the observations. The interchain packing distance is about 3.6 Å, i.e. in the same range as intermolecular distances found in conductive charge transfer salts. The deposited layer is highly anisotropic, with the a-c-plane parallel to the substrate. © 2001 Elsevier Science B.V. All rights reserved.

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