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  • 101.
    Lögdlund, Michael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Fredriksson, C.
    Service de Chimie des Matériaux, Université de Mons-Hainaut, Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux, Université de Mons-Hainaut, Mons, Belgium.
    Ramsey, M. G.
    nstitut für Experimentalphysik, Karl-Franzens Universität Graz, A-8010 Graz, Austria.
    Spangler, C. W.
    Department of Chemistry, Northern Illinois University, DeKalb, IL 60115, USA.
    A photoelectron spectroscopy study of the charge-induced π-electronic structural changes in α.ω.-diphenyltetradecaheptaene, a model molecule for polyacetylene1993In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 57, no 2, p. 4722-4727Article in journal (Refereed)
    Abstract [en]

    The π€-electronic structural changes in diphenylpolyene, α.ω.-diphenyltetradecaheptaene, or DP7, have been studied upon gradually doping with sodium Xu using X-ray and Ultraviolet Photoelectron Spectroscopy, XPS and UPS. The spectra are interpreted with the help of the results from Austin Model 1 (AM1) and Valence Effective Hamiltonian (VEH) quantum chemical calculations. The results of the doping with sodium can be discussed in terms of two confined solitons on the polyene part of the molecule, which results in two new energy levels in the originally forbidden energy gap.

  • 102.
    Lögdlund, Michael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Ramsey, M. G.
    Institut für Experimentalphysik, Karl-Franzens Universität Graz, Graz, Austria.
    Spangler, C. W.
    Department of Chemistry, Northern Illinois University, DeKalb, Illinois, USA.
    Fredriksson, C.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Mons, Belgium.
    Soliton pair charge storage in doped polyene molecules: Evidence from photoelectron spectroscopy studies1993In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 70, no 7, p. 970-973Article in journal (Refereed)
    Abstract [en]

    The π-electronic structural changes in a polyene molecule containing seven double bonds, α,ω-diphenyltetradecaheptaene (DP7), have been studied upon gradually doping with sodium, using x-ray and ultraviolet photoelectron spectroscopies. The spectra are interpreted with the help of detailed quantum chemical calculations. Analysis of the evolution of the XPS and UPS spectra as a function of doping with sodium indicates that the extra charges are stored in the form of two charged solitons on the polyene part of the molecules, which results in two new energy levels in the originally forbidden energy gap.

  • 103.
    Magnuson, Martin
    et al.
    Uppsala University.
    Yang, L.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Guo, J.-H.
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Agui, A.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Luo, Y.
    University of Stockholm.
    Ågren, H.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Hornsburgh, L. E.
    University of Durham.
    Monkman, A. P.
    University of Durham.
    The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies1998In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 237, no 3, p. 295-304Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the poly-pyridine conjugated polymer has been investigated by resonant and non-resonant inelastic X-ray scattering and X-ray absorption spectroscopies using synchrotron radiation. The measurements were made for both the carbon and nitrogen contents of the polymer. The analysis of the spectra has been carried out in comparison with molecular orbital calculations taking the repeat-unit cell as a model molecule of the polymer chain. The simulations indicate no significant differences in the absorption and in the non-resonant X-ray scattering spectra for the different isomeric geometries, while some isomeric dependence of the resonant spectra is predicted. The resonant emission spectra show depletion of the electron bands in line with symmetry selection and momentum conservation rules. The effect is most visual for the carbon spectra; the nitrogen spectra are dominated by lone pair n orbital emission of symmetry and are less frequency dependent.

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  • 104.
    Marciniak Braun, Slawomir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Trzcinski, M.
    Institute of Mathematics and Physics, Bydgoszcz, Poland.
    Birgerson, J.
    LCD Technology, Dalarna University, Borlänge, Sweden.
    Groenendaal, L.
    Agfa-Gevaert N. V., R&D Materials/Chemistry Department, Mortsel, Belgium.
    Louwet, F.
    Agfa-Gevaert N. V., R&D Materials/Chemistry Department, Mortsel, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Light Induced Damage in Poly(3,4-ethylenedioxythiophene) and its Derivatives Studied by Photoelectron Spectroscopy2004In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 141, no 1-2, p. 67-73Article in journal (Refereed)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene), usually known as PEDOT, and derivatives have attracted significant interest because of their high electrical conductivity. This electric property, however, deteriorates upon exposure to solar radiation. X-ray photoelectron spectroscopy (XPS) has been used to study the UV-light-induced chemical changes in doped PEDOT, as well as in both neutral and doped forms of its alkylated derivative—PEDOT-C14H29. Analysis of the XPS data indicates an oxidation of the sulfur in the thiophene ring. Apparently, photo-oxidation leads to the formation of sulfon groups, SO2, resulting in a disruption of π-conjugation in PEDOT, which there by diminishes the conductivity of the organic layer. This hypothesis is supported by the results of a study of model molecules for pristine and the oxidized PEDOT unit: 3,4 ethylenedioxythiophene (EDOT) and 3,4 ethylenedioxythiophene and S-dioxide (EDOT-SO2), respectively.

  • 105.
    Mason, M.G.
    et al.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Tang, C.W.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Hung, L.-S.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Raychaudhuri, P.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Madathil, J.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Giesen, D.J.
    Research Laboratories, Eastman Kodak Company, Rochester, NY 14650-2132, United States.
    Yan, L.
    Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, United States.
    Le, Q.T.
    Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, United States.
    Gao, Y.
    Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, United States.
    Lee, S.-T.
    Dept. of Phys. and Mat. Research, Center for Super Diamond Research, City University of Hong Kong, Kowloon, Hong Kong.
    Liao, L.S.
    Dept. of Phys. and Mat. Research, Center for Super Diamond Research, City University of Hong Kong, Kowloon, Hong Kong.
    Cheng, L.F.
    Dept. of Phys. and Mat. Research, Center for Super Diamond Research, City University of Hong Kong, Kowloon, Hong Kong.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Dos, Santos D.A.
    Dos Santos, D.A., Ctr. Rech. Electron. Photonique M., Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Bredas, J.L.
    Brédas, J.L., Ctr. Rech. Electron. Photonique M., Université de Mons-Hainaut, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, Tucson, AZ 85721-0041, United States.
    Interfacial chemistry of Alq3 and LiF with reactive metals2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 89, no 5, p. 2756-2765Article in journal (Refereed)
    Abstract [en]

    The electronic structure and chemistry of interfaces between tris-(8-hydroxyquinoline) aluminum (Alq3) and representative group IA and IIA metals, Al, and Al/LiF have been studied by x-ray and ultraviolet photoelectron spectroscopies. Quantum-chemical calculations at the density functional theory level predict that the Alq3 radical anion is formed upon reaction with the alkali metals. In this case, up to three metal atoms can react with a given Alq3 molecule to form the trivalent anion. The anion formation results in a splitting of the N 1 s core level and formation of a new feature in the previously forbidden energy gap. Virtually identical spectra are observed in the Al/LiF/Alq3 system, leading to the conclusion that the radical anion is also formed when all three of these constituents are present. This is support by a simple thermodynamic model based on bulk heats of formation. In the absence of LiF or similar material, the reaction of Al with Alq3 appears to be destructive, with the deposited Al reacting directly with the quinolate oxygen. We proposed that in those circumstances where the radical anion is formed, it and not the cathode metal are responsible for the electron injection properties. This is borne out by producing excellent injecting contacts when Ag and Au are used as the metallic component of the cathode structure. © 2001 American Institute of Physics.

  • 106.
    Minkov, I.
    et al.
    Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
    Gel'Mukhanov, F.
    Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Suess, C.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Core excitations of biphenyl2005In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 109, no 7, p. 1330-1336Article in journal (Refereed)
    Abstract [en]

    High-resolution C(1s) near-edge X-ray absorption and X-ray photoionization spectra of the free biphenyl molecule are presented and theoretically analyzed in order to allow an assignment of the observed spectral features. Finite lifetime broadening, a high density of vibrational states, and a strong overlap of contributions from chemically different carbon atom sites only partially allow resolving the vibrational fine structure. However, the shape and width of the spectral profiles are strongly determined by both chemical shifts and vibronic effects. In particular, different from photoionization of valence levels, both types of core level spectra do not contain contributions from dihedral modes which are related to the twisting motion of the two phenyl rings. Contrary to naphthalene, C-H stretching modes are significantly enhanced in the core excitation spectra of biphenyl while the contributions from C-C stretching modes are reduced. © 2005 American Chemical Society.

  • 107.
    Minkov, I.
    et al.
    Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
    Gel'mukhanov, F.
    Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden, Inst. of Automation and Electrometry, 630090 Novosibirsk, Russian Federation.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Suess, C.
    Ohrwall, G.
    Öhrwall, G., Department of Physics, Uppsala University, P.O. Box 530, S-751 21 Uppsala, Sweden.
    Sorensen, S.L.
    Dept. of Synchrt. Radiation Research, Institut of Physics, Lund University, P.O. Box 118, 5-221 00 Lund, Sweden.
    Braun, Slawomir
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Murdey, R.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, Roslagstullsbacken 15, S-106 91 Stockholm, Sweden.
    Core excitations of naphthalene: Vibrational structure versus chemical shifts2004In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 12, p. 5733-5739Article in journal (Refereed)
    Abstract [en]

    The initial state chemical shifts and vibrational fine structure of core excitations of naphthalene were analyzed using high-resolution x-ray photoelectron emission (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectra. The carbon atoms at peripheral sites were found to experience a small chemical shift and exhibit similar charge-vibrational coupling. The C-H stretching modes provide significant contributions to overall shape of spectra in the XPS spectra. The results show that vibrational fine structure dominates by particular C-C stretching modes, and in XPS of C2 and C3 sites also by high-energy C-H stretching modes.

  • 108. Murdey, Richard J.
    et al.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Charge injection barrier heights across multilayer organic thin films2005In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 44, no 6 A, p. 3751-3756Article in journal (Refereed)
    Abstract [en]

    Organic multilayer structures having a tetrathiafulvalene (TTF) or tetracyanoquinodimethane (TCNQ) interlayer were grown by physical vapor deposition on gold, indium tin oxide (ITO) or poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) PEDOT-PSS, substrates chosen to be representative of the anode materials typically used in the manufacture of organic electronic devices. The top layer was either p-quarterphenyl (Qp) or the hole transport material N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD). The valence electronic structure and vacuum level of the compound interface were monitored as a function of film thickness by ultraviolet photoelectron spectroscopy (UPS). Here we report the dependence of the energy level alignment on the substrate work function and discuss how an organic interlayer having a strong electron accepting or donating characteristic might be used to control the charge injection from a conducting electrode to a semiconducting organic hole transport material. © 2005 The Japan Society of Applied Physics.

  • 109. Oehzelt, M.
    et al.
    Resel, R.
    Suess, C.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Crystallographic and morphological characterization of thin pentacene films on polycrystalline copper surfaces2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, no 5, p. 54711-Article in journal (Refereed)
    Abstract [en]

    The degree of crystallinity, the structure and orientation of crystallites, and the morphology of thin pentacene films grown by vapor deposition in an ultrahigh vacuum environment on polycrystalline copper substrates have been investigated by x-ray diffraction and tapping-mode scanning force microscopy (TM-SFM). Depending on the substrate temperature during deposition, very different results are obtained: While at 77 K a long-range order is missing, the films become crystalline at elevated temperatures. From a high-resolution x-ray-diffraction profile analysis, the volume-weighted size of the crystallites perpendicular to the film surface could be determined. This size of the crystallites increases strongly upon changing temperature between room temperature and 333 K, at which point the size of individual crystallites typically exceeds 100 nm. In this temperature region, three different polymorphs are identified. The vast majority of crystallites have a fiber texture with the (001) net planes parallel to the substrate. In this geometry, the molecules are oriented standing up on the substrate (end-on arrangement). This alignment is remarkably different from that on single-crystalline metal surfaces, indicating that the growth is not epitaxial. Additionally, TM-SFM images show needlelike structures which suggest the presence of at least one additional orientation of crystallites (flat-on or edge-on). These results indicate that properties of thin crystalline pentacene films prepared on technologically relevant polycrystalline metal substrates for fast electronic applications may be compromised by the simultaneous presence of different local molecular aggregation states at all temperatures. © 2006 American Institute of Physics.

  • 110.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Tengstedt, Carl
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lindell, Linda
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Kugler, Thomas
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Transparent low-work-function indium tin oxide electrode obtained by molecular scale interface engineering2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 9, p. 1616-1618Article in journal (Refereed)
    Abstract [en]

    Transparent low-work-function indium tin oxide (ITO) electrode was obtained by using molecular scale interface engineering. The modified ITO surface may be used as electron injecting electrode in polymer light-emitting devices. ITO surfaces, exposed to TDAE molecules, were found to be stable upon exposure to air, and to mild annealing. Photoelectron spectroscopy measurements show that the low-work-function of the modified electrode remains upon exposure to air in gentle annealing.

  • 111.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Braun, Slawomir
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Tengstedt, Carl
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Energetics at Au top and bottom contacts on conjugated polymers2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 19Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy was employed to examine the energetics, and therefore charge injection barriers, at top and bottom contact configurations of gold and conjugated polymers, i.e., polymer spin coated on gold and vapor-deposited gold on polymer interfaces. Very similar results are obtained for both ex situ (contaminated) and in situ (clean) prepared interfaces: a 0.7-0.8 eV decrease in the vacuum energy levels is consistently observed as compared to bare polycrystalline gold. These observations are explained by changes of the metal work function upon contacting either polymers or contaminants, associated with the reduction of the electron density tail that extends outside the metal surface. © 2006 American Institute of Physics.

  • 112.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Formation of the interfacial dipole at organic-organic interfaces: C 60/polymer interfaces2007In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, no 23, p. 4213-4217Article in journal (Refereed)
    Abstract [en]

    The energetics at organic-organic interfaces comprising a thin film of a p-conjugated polymer and an overlayer of fullerene C60 was investigated. Two different polymers, poly(3-hexylthiophene) or P3HT, a polymer with moderate electron donor character were investigated. P3HT films were spin-coated from 5 mg mL-1 and 20 mg mL solutions in dichlorobenzene on conductive substrates such as native oxide terminated silicon SiO x/Si and aluminum, cleaned in acetone and isopropyl alcohol prior to spin coating and UV ozone treated gold. The thickness of the resulting polymer films obtained from the solutions with high concentrations was about 20 nm and 150 nm, as determined from reflectance ellipsometry. The results suggested that integer charge transfer provides a comprehensive description of energy level alignment at interfaces of organic semiconductors.

  • 113.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Sorensen, S.L.
    Lunds universitet.
    Groenendaal, L.
    AGFA-Gevaert.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Site-specific electronic structure of an oligo-ethylenedioxythiophene derivative probed by resonant photoemission2005In: New Journal of Physics, E-ISSN 1367-2630, Vol. 7Article in journal (Refereed)
    Abstract [en]

    A combination of conventional and resonant photoemission spectroscopy, x-ray absorption spectroscopy and ground-state quantum-chemical calculations has been used to study the valence electronic structure of a phenyl-capped 3,4-ethylenedioxythiophene oligomer, in polycrystalline thin films. The photon energy-dependent intensities of specific resonant decay channels are interpreted in terms of the spatial overlap of the excitation site and the ground-state molecular orbital involved in the decay. By making use of chemical shifts, excitations on different atomic sites are distinguished. It is demonstrated that site-specific information on the electronic structure of relatively large and complex organic systems may be obtained experimentally from non-radiative resonant decay spectra. In addition, these spectra provide relevant insight into the interpretation of near-edge x-ray absorption fine structure spectra. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

  • 114.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Murdey, R.
    Giles, M.
    Merck Chemicals, University Parkway, Southampton SO16 7QD, United Kingdom.
    Heeney, M.
    Merck Chemicals, University Parkway, Southampton SO16 7QD, United Kingdom.
    Tierney, S.
    Merck Chemicals, University Parkway, Southampton SO16 7QD, United Kingdom.
    McCulloch, I.
    Merck Chemicals, University Parkway, Southampton SO16 7QD, United Kingdom.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Electronic structure of a novel alkylidene fluorene polymer in the pristine state2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 385, no 3-4, p. 184-188Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a novel conjugated polymer, polyalkylidene fluorene has been studied using a combined experimental-theoretical approach. The densities of states in the valence band region of the new derivative, poly(9-(1'-decylundecylidene)fluorene), were measured by ultraviolet photoelectron spectroscopy and compared with electronic band-structure calculations performed in the valence effective Hamiltonian framework. The results are compared with those of similar studies on the reference polymer poly(9,9-dioctylfluorene). We report the experimentally determined ionization potential for this new material and discuss the role of substitution in altering the electronic properties of the polymer backbone. © 2003 Elsevier B.V. All rights reserved.

  • 115.
    Osikowicz, Wojciech
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Van, Der Gon A.W.D.
    Van Der Gon, A.W.D., Department of Applied Physics, Eindhoven Univ. of Technology, PO Box 513, 5600 MB Eindhoven, Netherlands.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Groenendaal, L.
    AGFA-Gevaert N.V., R and D Mat. - Chem. Dept., Septestraat 27, B-2640 Mortsel, Belgium.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Beljonne, D.
    Serv. Chim. des Materiaux Nouveaux, CREPM, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Lazzaroni, R.
    Serv. Chim. des Materiaux Nouveaux, CREPM, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    A joint theoretical and experimental study on the electronic properties of phenyl-capped 3,4-ethylenedioxythiophene oligomers2003In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 19, p. 10415-10420Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a series of phenyl-capped EDOT oligomers was studied using ultraviolet photoelectron spectroscopy, in combination with quantum-chemical methods. The bulk IP of the neutral PEDOT polymer was estimated to be 4.2 eV. The frontier band structue was predicted from the evolution of the spectral features in the studied series of oligomers.

  • 116.
    Salaneck, W R
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Classical ultraviolet photoelectron spectroscopy of polymers2009In: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA, ISSN 0368-2048, Vol. 174, no 1-3, p. 3-9Article in journal (Refereed)
    Abstract [en]

    Although X-ray photoelectron spectroscopy of polymers was well established by Clark and coworkers in the 1970s, ultraviolet photoelectron spectroscopy of polymer films, was developed later. Previous to the 1970s, the first attempts to use ultraviolet light on polymer films took the form of appearance potential (valence band edge) measurements. Only some years later could the full valence band region of thin polymer films, including insulating polymers, semiconducting polymers and electrically conducting polymers. The development of what might be termed "classical ultraviolet photoelectron spectroscopy" of polymer films may be loosely based upon a variety of issues, including adapting thin polymer film technology to ultra high vacuum studies, the widespread use of helium resonance lamps for studies of solid surfaces, the combined advent of practical and sufficient theoretical-computational methods. The advent of, and the use of, easily available synchrotron radiation for multi-photon spectroscopies, nominally in the area of the near UV, is not included in the term "classical". At the same time, electrically conducting polymers were discovered, leading to applications of the corresponding semiconducting polymers, which added technologically driven emphasis to this development of ultraviolet photoelectron spectroscopy for polymer materials. This paper traces a limited number of highlights in the evolution of ultraviolet photoelectron spectroscopy of polymers, from the 1970s through to 2008. Also, since this issue is dedicated to Prof. Kazuhiko Seki, who has been a friend and competitor for over two decades, the author relies on some of Prof. Sekis earlier research, unpublished, on who-did-what-first. Prof. Sekis own contributions to the field, however, are discussed in other articles in this issue. (C) 2009 Elsevier B.V. All rights reserved.

  • 117.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Photoelectron spectroscopy of interfaces in polymer-based electronic devices.2001In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 221, p. 467-COLL-Conference paper (Other academic)
  • 118.
    Salaneck, William R.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Photoelectron Spectroscopy: A Basic Tool for the Study of Molecular Materials1992In: Nanostructures Based on Molecular Materials / [ed] W. Gopel and Ch Ziegler, Weinhem: Vch Pub , 1992, p. 329-348Chapter in book (Refereed)
  • 119.
    Salaneck, William R
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Hybrid interfaces of conjugate polymers: Band edge alignment studied by ultraviolet photoelectron spectroscopy2004In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 19, no 7, p. 1917-1923Article in journal (Refereed)
    Abstract [en]

    The control of hybrid interfaces in polymer-based electronic devices may be enabling in many applications. The engineering of hybrid interface involves (requires) an understanding of the electronic structure of materials - one organic and one inorganic - that form the two halves of hybrid interfaces, as well as the electronic and chemical consequences of the coupling of the two. Although much literature exists describing the interfaces between vapor-deposited organic molecules and model molecules for polymers on the surfaces of clean metals in ultrahigh vacuum, few studies have been reported on spin-coated, semiconducting polymer films on realistic substrates. Spin coating in an inert atmosphere (or even air) is a central part of the process of the fabrication of polymer-based light-emitting devices and other modern polymer-based electronic components. Here, work on the electronic structure of semiconducting (conjugated) polymer films spin-coated onto selected inorganic substrates, carried out using ultraviolet photoelectron spectroscopy, is reviewed and summarized to generate a generalized picture of the hybrid interfaces formed under realistic device fabrication conditions. © 2004 Materials Research Society.

  • 120.
    Salaneck, William R
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Friend, RH
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium.
    Bredas, JL
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium.
    Electronic structure of conjugated polymers: consequences of electron-lattice coupling1999In: Physics reports, ISSN 0370-1573, E-ISSN 1873-6270, Vol. 319, no 6, p. 232-251Article, review/survey (Refereed)
    Abstract [en]

    Conjugated organic polymers can be doped, via oxidation or reduction chemistry or via acid-base chemistry, to induce very high electrical conductivity. Conjugated polymers are beginning to find uses, in both the neutral and the doped states, in prototype molecular-based electronics applications and in electronic and opto-electronic devices. The physical basis for the many of the unusual properties of these new materials is discussed, at a sufficient level of approximation to enable an understanding of the important issues by the general condensed matter physicist. In particular, emphasis is placed on the interconnections of the electronic. geometric and chemical structures, Lu the ground stale and especially in the excited states. The important role of electron-electron and electron-lattice interactions are pointed out, and justified through a combined experimental-theoretical approach. (C) 1999 Elsevier Science B.V. All rights reserved.

  • 121.
    Salaneck, William R
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Logdlund, M
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Acreo AB, S-60221 Norrkoping, Sweden Linkoping Univ, ITN, Dept Nat Sci & Technol, S-60174 Norrkoping, Sweden.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Greczynski, G
    Linkoping Univ, IFM, Dept Phys, S-58183 Linkoping, Sweden Acreo AB, S-60221 Norrkoping, Sweden Linkoping Univ, ITN, Dept Nat Sci & Technol, S-60174 Norrkoping, Sweden.
    Kugler, Thomas
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    The electronic structure of polymer-metal interfaces studied by ultraviolet photoelectron spectroscopy2001In: Materials science & engineering. R, Reports, ISSN 0927-796X, E-ISSN 1879-212X, Vol. 34, no 3, p. 121-146Article, review/survey (Refereed)
    Abstract [en]

    Ultraviolet photoelectron spectroscopy has come of age. UPS can take its place beside its older, better-known sister, ESCA (or XPS) as a surface sensitive method which has become more useful in learning certain specific things about interfaces at distances significantly larger than the typical electron elastic mean-free-paths dictated by the photon energies employed, In particular, the emergence of UPS as a real tool for interfacial studies has been applications driven, evolving after needs within polymer-based electronics applications. The situation is clarified through the use of several examples, drawn from the applications-spectroscopy literature. (C) 2001 Published by Elsevier Science B.V.

  • 122.
    Salaneck, William R.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Brédas, Jean-Luc
    Universíté de Mons-Hainault, Belgium.
    Conjugated polymer surfaces and interfaces: electronic and chemical structure of interfaces for polymer light emitting devices1996Book (Other academic)
    Abstract [en]

    In this book, we attempt to bring together in one place the results of a relatively large number of basic studies of conjugated polymer surfaces, as well as the 'early stages of metal-polymer interface formation', in an attempt to produce a simple and coherent picture of some of the unique features of these surfaces and interfaces; features which are important in understanding and controling the performance of polymer-based LEDs.

  • 123. Samori, P.
    et al.
    Keil, M.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Birgerson, J.
    Watson, M.
    Mullen, K.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Rabe, J.P.
    Growth of ordered hexakis-dodecyl-hexabenzocoronene layers from solution: A SFM and ARUPS study2001In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 105, no 45, p. 11114-11119Article in journal (Refereed)
    Abstract [en]

    The layer growth of a polycyclic aromatic hydrocarbon moiety, hexakis-dodecyl-hexabenzocoronene (HBC-C12), from solution onto a conductive flat solid substrate has been studied. Scanning Force Microscopy (SFM), together with the analysis of the intensities of p-structures in spectra of Angle-Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS) measurements, revealed that the HBC-C12 molecules can self-assemble as dry layers with the conjugated disklike molecules lying flat on the (0001) plane of highly oriented pyrolitic graphite (HOPG). By varying the rate of the molecular physisorption it was possible to orient these molecular architectures along preferential directions according to the symmetry of the substrate. Additionally, the film morphology is affected by the concentration of the solution. This indicates that the growth of these organic layers on HOPG is a kinetically governed process which, if carried out sufficiently slowly, leads to the growth of hetero-epitaxial crystallites.

  • 124.
    Sanchez-Carrera, R.S.
    et al.
    Sánchez-Carrera, R.S., School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
    Coropceanu, V.
    School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
    Da, Silva Filho D.A.
    Da Silva Filho, D.A., School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Murdey, R.
    Suess, C.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Bredas, J.-L.
    Brédas, J.-L., School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
    Vibronic coupling in the ground and excited states of oligoacene cations2006In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, no 38, p. 18904-18911Article in journal (Refereed)
    Abstract [en]

    The vibrational coupling in the ground and excited states of positively charged naphthalene, anthracene, tetracene, and pentacene molecules is studied on the basis of a joint experimental and theoretical study of ionization spectra using high-resolution gas-phase photoelectron spectroscopy and first-principles correlated quantum-mechanical calculations. Our theoretical and experimental results reveal that, while the main contribution to relaxation energy in the ground state of oligoacene systems comes from high-energy vibrations, the excited-state relaxation energies show a significant redistribution toward lower-frequency vibrations. A direct correlation is found between the nature of the vibronic interaction and the pattern of the electronic state structure. © 2006 American Chemical Society.

  • 125. Sancho-Garcia, JC
    et al.
    Foden, CL
    Grizzi, I
    Greczynski, G
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Bredas, JL
    Cornil, J
    Joint theoretical and experimental characterization of the structural and electronic properties of poly(dioctylfluorene-alt-N-butylphenyl diphenylamine)2004In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 18, p. 5594-5599Article in journal (Refereed)
    Abstract [en]

    Fluorene-based copolymers are currently attracting considerable interest for use in a wide range of optoelectronic devices. Here, we present the results of a joint quantum-chemical and experimental characterization of the structural, electronic, and optical properties of an alternating fluorene-triphenylamine copolymer. We compare the results from this study with those from similar studies of polyfluorene. Although calculations are performed for the gas phase and experiments are performed on the solid state, the results from the two methodologies are in good agreement: the relevant electronic levels, HOMO and LUMO, of polyfluorene are found to be destabilized by incorporation of triphenylamine units in the conjugated backbone, whereas the optical properties of polyfluorene chains are largely unperturbed by the presence of triphenylamine.

  • 126.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Poly(3.4-ethylene dioxythiophene)- and polyaniliane-Poly(perfluoroethylenesulfonic acid) as hole injecting layers in polymer light emitting devicesManuscript (preprint) (Other academic)
    Abstract [en]

    We present a study of poly(3,4-ethylene dioxythiophene), PEDOT, and polyaniline, where poly(perfluoroethylenesulfonic acid), PFESA has been used as counter ion and dopant respectively. The study was done in order to establish how the material petfonns as hole injecting layers in polymer light emitting devices. A total of 19 different PEDOT-PFESA samples and three different PAni-PFESA systems were studied, each with a different acidity, ranging between pH 1.6 to pH 7.7. The highest work function obtained was 6.0 eV and work function and acidity correlate such that significantly higher work functions are obtained for higher acidities. Photoelectron spectroscopy and Atomic Force Microscopy data suggest that the resulting fihns have grain structured morphology where the PAni-PFESA and PEDOT-PFESA systems form inverse micelles, i.e. PEDOT or PAni together with counter ions as an inner core surrounded by mainly the PFESA backbone.

  • 127.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Annica
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hsu, C.
    Dupont Displays, The Experimental Station, Wilmington, USA.
    Zhang, C.
    Dupont Displays, Santa Barbara, USA.
    Parker, I.D.
    Dupont Displays, Santa Barbara, USA.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Study and comparison of conducting polymer hole injection layers in light emitting devices2005In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 6, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A set of polyaniline- and poly(3,4-ethylene dioxythiophene)-based materials were studied as hole injection layers in polymer light emitting devices. The choice of polymeric counterion/dopant poly(styrenesulfonic acid), and poly(acrylamido-2-methyl-1-propanesulfonic acid), and poly(acrylamide) blended with polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) was found to influence both work function and film morphology, which in turn affects device performance. The work functions of the polymer films spanned the range of over 1 eV and the surface region of the films were found to be low in conducting polymer content compared to the bulk. This was particularly the case of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) blended with poly(acrylamide) which showed device efficiency equal to that of the poly(3,4-ethylene dioxythiophene)–poly(styrenesulfonic acid) reference. The turn on voltage, however, was significantly larger, likely due to the insulating poly(acrylamide)-rich surface region of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid)/poly(acrylamide) film. The polymer blend of polyaniline/poly(styrenesulfonic acid) yielded the highest work function (5.5 ± 0.1 eV).

  • 128.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    de Jong, M. P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kanciurzewska, Anna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Carlegrim, Elin
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    V(TCNE)x: the electronic structure of an enigmatic, organic-based room temperature magnet revealedManuscript (preprint) (Other academic)
    Abstract [en]

    We have prepared and characterized thin films of V(TCNE)x in ultra-high vacuum using a novel film growth technique based on in-situ chemical vapor deposition of tetracyanoethylene, TCNE, and bis-benzene vanadium, V(C6H6)2. The in-situ preparation method enabled, for the first time, experimental analysis of the electronic structure. X-ray magnetic circular dichroism (XMCD) measurements recorded at the V L2,3-edge confirmed room temperature magnetic ordering. A combination of conventional photoelectron spectroscopy (PES) and resonant photoemission (RPE) measured at the x-ray absorption edges (V L3-edge, C K-edge, N K-edge) shows that the highest occupied electronic state is V(3d)-derived. Nearly complete quenching of the V(3d) orbital angular momentum is observed from the low value of the integrated XMCD signal, indicating a strong ligand field. The rearrangements of the TCNE" related valance electronic states observed in PED and near edge x-ray absorption fine structure (NEXAFS) spectra, in combination with the evidence of V(3d) and TCNE" π (π*) orbital overlap contained in RPE spectra, also point to strong, covalent type bonding.

  • 129.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kanciurzewska, Anna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    de Jong, M. P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    UV-ozone treatment of PEDOT-based materials resulting in increased work functionsManuscript (preprint) (Other academic)
    Abstract [en]

    We describe a simple method to increase the work function of PEDOT-PFESA and PEDOT-PSS by short exposure to UV and ozone in a "UVO-Cleaner®". The creation of carbonyl gmups in the surface region fotms a dipole layer shifting the vacuum level with a followed increase in work function. It has been shown that the work function of PEDOT-PFESA can be increased by as much as -0.4 eV to the absolute value of 6.3 eV and by at least -0.2 eV for PEDOT-PSS to the absolute value of 5.4 e V. The increase in work function has also proven to be time dependent with the largest increasing rate occuning for short exposure times. Upon ozone treatment, both PEDOT and PSS are oxidized whereas PFESA seems to be unaffected.

  • 130.
    Tengstedt, Carl
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Kanciurzewska, Anna
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Braun, Slawomir
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Ultraviolet light-ozone treatment of poly(3,4-ethylenedioxy-thiophene)-based materials resulting in increased work functions2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 4, p. 2085-2090Article in journal (Refereed)
    Abstract [en]

    We describe a simple method to increase the work function of poly(3,4-ethylenedioxy-thiophene)-poly(perfluoroethylene sulfonic acid), PEDOT-PFESA, and poly(3,4-ethylenedioxy-thiophene)-poly(styrene sulfonic acid), PEDOT-PSS, by short exposure to ultraviolet light and ozone. The creation of carbonyl groups in the surface region forms a dipole layer shifting the vacuum level with a followed increase in work function. It has been shown that the work function of PEDOT-PFESA can be increased by as much as ∼ 0.4 eV to the absolute value of 6.3 eV and by at least ∼ 0.2 eV for PEDOT-PSS to the absolute value of 5.4 eV. The increase in work function has also proven to be time dependent with the largest increasing rate occurring for short exposure times. Upon ozone treatment, both PEDOT and PSS are oxidized whereas PFESA seems to be unaffected.

  • 131.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Osikowicz, Wojciech
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Parker, I.D.
    Dupont Displays, Santa Barbara, California.
    Hsu, C-H.
    Dupont Displays, E.I. DuPont de Nemours and Company, Wilmington, Delaware.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fermi-level pinning at conjugated polymer interfaces2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 5, p. 53502-Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy has been used to map out energy level alignment of conjugated polymers at various organic-organic and hybrid interfaces. Specifically, we have investigated the hole-injection interface between the substrate and light-emitting polymer. Two different alignment regimes have been observed: (i) Vacuum-level alignment, which corresponds to the lack of vacuum-level offsets (Schottky–Mott limit) and (ii) Fermi-level pinning, where the substrate Fermi level and the positive polaronic level of the polymer align. The observation is rationalized in terms of spontaneous charge transfer whenever the substrate Fermi level exceeds the positive polaron/bipolaron formation energy per particle. The charge transfer leads to the formation of an interfacial dipole, as large as 2.1 eV.

  • 132.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Unge, Mikael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    de Jong, Michel P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Coulomb interactions in rubidium-doped tetracyanoethylene: a model system for organometallic magnets2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 16, p. 165208-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of tetracyanoethylene (TCNE) has been studied both in its pristine state and upon stepwise rubidium intercalation, by UV and x-ray photoelectron spectroscopy as well as with theoretical calculations. The intercalated system may serve as a model for TCNE-based organometallic magnets, of which the electronic structure remains largely unknown. Rubidium is found to n-dope the TCNE molecules forming Rb+TCNE- with almost complete charge transfer. Calculations show a spin splitting of the former highest occupied molecular orbital level upon Rb doping. We see no evidence for the formation of doubly charged TCNE molecules. A gap opens up at the Fermi energy for Rb+TCNE- due to on-site Coulomb interactions. We estimate the on-site Coulomb interaction of amorphous TCNE doped with Rb to be ∼2 eV.

  • 133.
    Tsao, H.N.
    et al.
    Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    Pisula, W.
    Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany, Evonik Degussa GmbH, Process Technology and Engineering, Process Technology New Processes, Rodenbacher Chaussee 4, 63457 Hanau, Germany.
    Liu, Z.
    Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Mullen, K.
    Müllen, K., Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    From ambi- To unipolar behavior in discotic dye field-effect transistors2008In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 20, no 14, p. 2715-2719Article in journal (Refereed)
    Abstract [en]

    A study was conducted to demonstrate solution-processable ambipolar organic field-effect transistors based on a discotic dye. Such single component devices allow the study of the influence of supramolecular ordering on FET charge transport properties. These transistors exhibited ambipolarity even without any structural order. The absence of p-type behavior could not be explained by the increase of hole injection barrier or by interface trapping. It was rather observed that the change in morphology most probably lead to such a phenomenon. These findings further suggest that besides charge injection barriers and interface trapping, structural composition, that is, microscopic domain boundaries together with local defects in one-dimensional columnar systems, also trigger the loss of ambipolarity owing to lowering of the minority charge carrier mobility.

  • 134.
    Uvdal, Kajsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bertilsson, L.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    MacDiarmid, A. G.
    Department of Chemistry, University of Pennsylvania, Philadelphia, USA.
    Ray, A.
    Chemistry, University of Pennsylvania, Philadelphia, USA.
    Scherr, E. M.
    Chemistry, University of Pennsylvania, Philadelphia, USA.
    Hjertberg, T.
    Department of Polymer Technology, Chalmers University, Göteborg, Sweden.
    Epstein, A. J.
    Department of Physics, The Ohio State University, Columbus, OH, USA.
    Vapor deposited polyaniline1989In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 29, no 1, p. 451-456Article in journal (Refereed)
    Abstract [en]

    We have prepared thin films of polyaniline (emeraldine base) by an open boat evaporation process. These vapor-deposited films have a higher molecular weight than expected from a vapor deposition process, indicating a post deposition chemical process. The films have optical properties very similar to, but not identical to, these of “conventional” emeraldine. After treatment with protonic acid, the films exhibit an electrical conductivity of up to about 10% of that of conventional emeraldine salt.

  • 135. Van, Der Gon A.W.D.
    et al.
    Birgerson, J.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Modification of PEDOT-PSS by low-energy electrons2002In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 3, no 3-4, p. 111-118Article in journal (Refereed)
    Abstract [en]

    The stability of conjugated organic materials under electron transport is of great importance for the lifetime of devices such as polymer light-emitting diodes (PLEDs). Here, the modification of thin films of poly(3,4- ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) (known as PEDOT-PSS, often used in the fabrication of PLEDs) by low-energy electrons has been studied using X-ray photo-electron spectroscopy. Thin films of PSSH and molecular solid films of EDOT molecules also have been studied. We find that electrons with kinetic energies as low as 3 eV result in significant modification of the chemical structure of the materials. For thin films of PSSH, the electron bombardment leads to a strong loss of oxygen and a smaller loss of sulfur. In addition, a large amount of the sulfur atoms that remain in the films exhibits a different binding energy because of scissions of the bonds to oxygen atoms. For condensed molecular solid films of EDOT molecules, we find that the carbon atoms bonded to oxygen react and form additional bonds, as evidenced by a new component in the C(1s) peak at a higher binding energy. In the PEDOT-PSS blend, we find both effects. The importance of these observations for light-emitting diodes incorporating PEDOT-PSS films is discussed. This work demonstrates that the combination of in situ low-energy electron bombardment in combination with photo-electron spectroscopy is a powerful method to simulate and study certain processes, associated with low-energy electrons, occurring in organic based devices, which cannot be studied directly otherwise. © 2002 Elsevier Science B.V. All rights reserved.

  • 136. Wang, Ying
    et al.
    Gao, Weiying
    Braun, Slawomir
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Fabrice, Amy
    Calvin, Chan
    Kahn, Antoine
    Enhancement of iridium-based organic light-emitting diodes by spatial doping of the hole transport layer2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 19, p. 193501-Article in journal (Refereed)
    Abstract [en]

    The electroluminescence efficiency of Ir-based green emitter devices is very sensitive to the nature of the hole transport layer used. We show that by inserting a 1 nm layer of bis[4-(N,N-diethylamino)-2-methylphenyl](4- methylphenyl)methane (MPMP) in a 4, 4′ - bis- (carbazol-9-yl) biphenyl (CBP) hole transport layer, a device that combines the positive attributes of both MPMP (high efficiency) and CBP (low injection voltage) is obtained. These results can be understood based on a combined ultraviolet photoemission spectroscopy/inverse photoemission spectroscopy study, which reveals the very low electron affinity and superior electron blocking capability of MPMP. © 2005 American Institute of Physics.

  • 137.
    Xing, K. Z.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Iucci, G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bröms, P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 76, no 1-3, p. 263-267Article in journal (Refereed)
    Abstract [en]

    The electronic and geometric structures of poly [3-(4-octylphenyl)thiophene] have been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Thermochromic effects, and new charge induced states generated by potassium doping, have been observed by direct UPS measurements. The experimental results are in very good agreement with the results of theoretical quantum chemical calculations performed with the Austin Model 1 semi-empirical model and the valence-effective Hamiltonian pseudo-potential model.

  • 138.
    Xing, K. Z.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Iucci, G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bröms, P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy1996In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 80, no 1, p. 59-66Article in journal (Refereed)
    Abstract [en]

    The electronic structure of poly [3-(4-octylphenyl)thiophene] (POPT) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS), as well as by quantum chemical calculations. Both temperature-dependent effects on the electronic structure of the neutral system, as well as the generation of new electronic states induced by doping with alkaline metals, have been observed. The experimental results are in good agreement with the results of the quantum chemical calculations.

  • 139.
    Yim, Keng-Hoong
    et al.
    University of Cambridge.
    Doherty, Walter J
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Murphy, Craig E
    National Physics Lab, Teddington .
    Friend, Richard H
    University of Cambridge.
    Kim, Ji-Seon
    University London Imperial College of Science and Technology and Medicine.
    Phase-Separated Thin Film Structures for Efficient Polymer Blend Light-Emitting Diodes2010In: NANO LETTERS, ISSN 1530-6984, Vol. 10, no 2, p. 385-392Article in journal (Refereed)
    Abstract [en]

    We report laterally and vertically phase-separated thin film structures in conjugated polymer blends created by polymer molecular weight variation. We find that micrometer-scale lateral phase separation is critical in achieving high initial device efficiency of light-emitting diodes, whereas improved balance of charge carrier mobilities and film thickness uniformity are important in maintaining high efficiency at high voltages. The optoelectronic properties of these blend thin films and devices are strongly influenced by the polymer chain order/disorder and the interface state formed at polymer/polymer heterojunctions.

  • 140.
    Zhan, Yiqiang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    de Jong, M.P.
    Li, Fenghong
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Dediu, A.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Energy level alignment and chemical interaction at Alq3/Co interfaces for organic spintronic devices2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 4, article id 045208Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the interface between tris(8-hydroxyquinoline) aluminum (Alq3) and cobalt was investigated by means of photoelectron spectroscopy. As demonstrated recently, this interface is characterized by efficient spin injection in organic spintronic devices. A strong interface dipole that reduces the effective work function of cobalt by about 1.5 eV was observed. This leads to a large barrier for hole injection into the highest occupied molecular-orbital (HOMO) level of 2.1 eV, in agreement with a previously proposed model based on electron transport in Co-Alq3 -La0.7 Sr0.3 MnO3 spin valves. Further experimental results indicate that chemical interaction occurs between the Alq3 molecules and the cobalt atoms, while the latter penetrate the Alq3 layer upon vapor deposition of Co atoms. The data presented lead to significant progress in understanding the electronic structure of the Co-on- Alq3 interface and represent a significant step toward the definition of the interface parameters for the efficient spin injection in Alq3 based spin valves. © 2008 The American Physical Society.

  • 141.
    Zhi, L.
    et al.
    Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    Gorelik, T.
    Institute of Physical Chemistry, Johannes Gutenberg Universität, 55128 Mainz, Germany.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Wu, J.
    Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    Kolb, U.
    Institute of Physical Chemistry, Johannes Gutenberg Universität, 55128 Mainz, Germany.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Mullen, K.
    Müllen, K., Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
    Solid-state pyrolyses of metal phthalocyanines: A simple approach towards nitrogen-doped CNTs and metal/carbon nanocables2005In: Small, ISSN 1613-6810, Vol. 1, no 8-9, p. 798-801Article in journal (Refereed)
    Abstract [en]

    Solid-state pyrolysis of organometallic precursors has emerged as an alternative method for preparing carbon nanostructures such as carbon nanotubes (CNT) and carbon anions. The morphology of the tubes can be controlled by the nature of the precursors and the pyrolysis procedures, and micrometer long nanotubes, composed of metal carbide wires encased in a graphitic sheath. Cobalt phthalocyanine (CoPc) as well as iron phthalocyanine were pyrolyzed at different temperatures to obtain CNTs. HRTEM and energy-dispersion X-Ray analysis disclosed that the core consisted of long, iron-containing single crystals and that the core was fully surrounded by crystallized graphic carbon. Iron-filled carbon nanotubes were also obtained from the pyrolysis of ferrocene by CVD method. Encapsulated iron carbide were also observed inside the carbon nanotubes formed after pyrolysis of FePc. These nanotubes and nanocables were considered useful for assembling miniaturized electronic device and sensors.

  • 142.
    Zotti, G.
    et al.
    Istituto CNR l'Energetica Interfasi, C.o Stati Uniti 4, 35127 Padova, Italy.
    Zecchin, S.
    Istituto CNR l'Energetica Interfasi, C.o Stati Uniti 4, 35127 Padova, Italy.
    Schiavon, G.
    Istituto CNR l'Energetica Interfasi, C.o Stati Uniti 4, 35127 Padova, Italy.
    Louwet, F.
    R and D Materials Research, Chemistry Department, Agfa Gevaert N.V., Septelaan 27, B-2640 Mortsel, Belgium.
    Groenendaal, L.
    R and D Materials Research, Chemistry Department, Agfa Gevaert N.V., Septelaan 27, B-2640 Mortsel, Belgium.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Electrochemical and XPS studies toward the role of monomeric and polymeric sulfonate counterions in the synthesis, composition, and properties of poly(3,4-ethylenedioxythiophene)2003In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 36, no 9, p. 3337-3344Article in journal (Refereed)
    Abstract [en]

    Electrochemically prepared poly(3,4-ethylenedioxythiophene) (PEDT) poly(styrenesulfonate) (PSS), produced from acidic (PSSH) and basic (PSSNa) PSS, was characterized by cyclic voltammetry CV, UV-vis spectroscopy, in situ conductivity, and XPS spectroscopy and was compared with electrochemically prepared PEDT/tosylate and chemically prepared PEDT/PSS. CV analysis shows that the polymer synthesis is strongly affected by the nucleophilic character of the counteranion. Although CV and UV-vis spectroscopy show that the structure and degree of polymerization (oligomeric, ca. 10 EDT units) of the PEDT backbone is the same for all polymers, XPS is able to explain the different conductivity values for these materials (ranging from 1 S cm-1 for PEDT/PSSNa to 400-450 S cm-1 for PEDT/tosylate) based on doping level and composition. In particular, critical results are observed to be the ratios between sulfonate and thiophene units in the polymers: the higher the PEDT concentration, the higher the conductivity. XPS also explains by solvent-induced nanometer-scale segregation between PEDT/PSS and excess PSS particles the often reported conductivity enhancement of chemically prepared PEDT/PSS upon treatment with polar solvents.

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