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  • 1.
    Bantikassegn, W.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Absence of Schottky barrier formation in junctions of Al and polypyrrole-polyelectrolyte polymer complexes1993In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 224, no 2, p. 232-236Article in journal (Refereed)
    Abstract [en]

    Thin films of conducting polypyrrole doped with large polymeric anions of polystyrene-sulphonate are electrochemically prepared to study the metal/polymer junctions. Aluminium and gold contacts are vacuum deposited to form metal/polymer/gold sandwich structures for current-voltage characterization. Photoelectron spectroscopy, using UV and X-ray photons, is carried out to investigate the possible causes of current limitation in the Al/PPy(PSS) junction.

  • 2.
    Bantikassegn, W.
    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.
    Inganäs, Olle
    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.
    Proceedings of the International Conference on Science and Technology of Synthetic Metals Electronic properties of polypyrrole (polystyrene-sulphonate)/metal junctions1993In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 55, no 1, p. 36-42Article in journal (Refereed)
    Abstract [en]

    The nature of polymer/metal interfaces is decisive for the operation of polymer based electronic devices. At such interfaces charge transport may be affected by barrier formation, or by formation of insulating interfaces of various types. We have prepared thin films of conducting polypyrrole doped with large polymeric anions of polystyrenesulphonate for studies in metal/polymer junctions. Aluminium and gold contacts are vacuum deposited to form metal/polymer/gold sandwich structures. The current-voltage characteristics show that the interface between polypyrrole and gold is ohmic with no current limitation. However, the aluminium/polypyrrole interface forms highly resistive and nonohmic contacts. Photoelectron spectroscopy using UV and X-ray photons reveals a decrease of the work function upon Al deposition, reactions between Al and the sulphonate anions, and immediate oxidation of the aluminium upon exposure to oxygen. These observations corroborate the interpretation that the current limitation found at Al/polypyrrole junctions is due to formation of insulating aluminium oxide, not excluding reactions between the metal and dopant. It is also pointed out that interfaces between reactive metals and polymers are prone to such oxide interface formation, considering the high diffusivity of oxygen in many polymers.

  • 3.
    Barta, P.
    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.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Zagórska, M.
    Department of Chemistry, Technical University of Warsaw, PL‐00 664 Warsaw, Poland.
    Pron, A.
    Department of Material Science and Ceramics, Academy of Mining and Metallurgy, PL‐30 059 Kraków, Poland.
    Temperature evolution of the electronic band structure of the undoped and doped regioregular analog of poly(3‐alkylthiophenes): A spectroscopic and theoretical study1994In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 100, no 2, p. 1731-1741Article in journal (Refereed)
    Abstract [en]

    The undoped and ferric chloride p‐doped ‘‘head‐to‐head’’ ‘‘tail‐to‐tail’’ analog of poly(3‐decylthiophene) obtained from substituted bithiophenes, i.e., poly(4,4’didecyl‐2,2’bithiophene)‐PDDBT has been investigated. The samples were studied by means of ultraviolet photoelectron spectroscopy,optical absorption measurements, and polymerbands structure calculations. Experiments were carried out at different temperatures between 100 °C and −180 °C. The results indicate that PDDBT is nonplanar in the undoped state. No temperature effects have been observed in the π‐electron properties. In the doped state, however, lowering of the temperature results in an increase of the system planarity that modifies the electronic band structure. This effect has been shown to be fully reversible with temperature.

  • 4.
    Bröms, P.
    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.
    Xing, K. Z.
    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.
    Dannetun, Per
    Groupe de Physique des Solides, Tour 23-2, place Jussieu, F-752 51 Paris Cedex 05, France.
    Cornil, J.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Santos, D.A. dos
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Moratti, S. C.
    University Chemical Laboratory, University of Cambridge, Cambridge CB2 1EW, UK.
    Holmes, A. B.
    University Chemical Laboratory, University of Cambridge, Cambridge CB2 1EW, UK.
    Friend, R. H.
    Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
    Optical absorption studies of sodium doped poly(cyanoterephthalylidene)1994In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1-3, p. 93-96Article in journal (Refereed)
    Abstract [en]

    The effects of doping poly(cyanoterephthalylidene) with sodium in ultrahighvacuum been studied by optical absorption spectroscopy. Upon doping, new optical transitions are observed within the bandgap; the characteristics of these transitions are consistent with the formation of bipolarons. The optical absorption results are confirmed by direct measurements of the doping-induced gap states using ultraviolet photoelectron spectroscopy.

  • 5.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Boman, Magnus
    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.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Fredriksson, C.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Zamboni, R.
    Istituto di Spettroscopia Molecolare, CNR, Bologna, Italy.
    Taliani, C.
    Istituto di Spettroscopia Molecolare, CNR, Bologna, Italy.
    The chemical and electronic structure of the interface between aluminum and polythiophene semiconductors1993In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 99, no 1, p. 664-672Article in journal (Refereed)
    Abstract [en]

    We have investigated the chemical nature and the electronic structure of the interface between a low work function metal,aluminum, and a conjugated polymersemiconductor, polythiophene. We have studied the initial stages of the interface formation by depositing the metal onto the surface of a polymer film. Charge transfer processes between the metal and the polymer are analyzed using core‐level x‐ray photoelectron spectroscopy (XPS); the evolution upon metallization of the valence electronic levels directly related to the polymerelectronic structure is followed with ultraviolet photoelectron spectroscopy (UPS). With these techniques, we investigate the deposition of aluminum on two polythiophene systems (i) the alkyl‐substituted poly‐3‐octylthiophene and (ii) the α‐sexithiophene oligomer. The experimental data are compared to the results of a recent quantum chemical study on model systems consisting of thiophene oligomers (up to sexithiophene) interacting with a few Al atoms. The interaction of polythiophene with Al atoms is found to modify dramatically the structure of the conjugated backbone, as strong carbon–aluminum bonds are formed in the α positions of the thiophene rings. A large charge transfer takes place from the Al atoms to the polymer chain, and the upper π levels of the polymer are strongly affected. The metallization is contrasted to the doping of conjugated polymers with alkali metals

  • 6.
    Dannetun, Per
    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.
    Fauquet, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kaerijama, K.
    National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305, Japan.
    Sonoda, Y.
    National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305, Japan.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Interface formation between poly(2,5-diheptyl-p-phenylenevinylene) and calcium: implications for light-emitting diodes1994In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1-3, p. 133-136Article in journal (Refereed)
    Abstract [en]

    The early stages of metal/polymer interface formation between calcium and poly(2,5-diheptyl-p-phenylenevinylene) (PDHPV) have been studied using both X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Charge transfer is observed from the metal atoms to the polymer; as a result the calcium atoms at the interface are ionic, and negative bipolarons appear as the charge-carrying species on the polymer chains. This n-type doping of PDHPV by calcium leads to the appearance of new electronic states in the polymer bandgap. The calcium atoms appear to diffuse into the near surface region of the polymer, rather than forming a well-defined overlayer on the organic films.

  • 7.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Boman, Magnus
    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.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Mons Belgium.
    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.
    Graham, S.
    Cavendish Laboratory, University of Cambridge, Cambridge, UK.
    Friend, R. H.
    Cavendish Laboratory, University of Cambridge, Cambridge, UK.
    Holmes, A. B.
    University Chemical Laboratory, Lensfield road, Cambridge, UK.
    Zamboni, R.
    Instituto di Spettroscopia Molecolare, Bologna, Italy.
    Taliani, C.
    Instituto di Spettroscopia Molecolare, Bologna, Italy.
    Proceedings of the International Conference on Science and Technology of Synthetic Metals The chemical and electronic structure of the interface between aluminum and conjugated polymers or molecules1993In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 55, no 1, p. 212-217Article in journal (Refereed)
    Abstract [en]

    The interaction between aluminum and α-ω-diphenyltetradecaheptaenee (DP7), α-sexithienyl (6T), and poly(p-phenylenevinylene) (PPV), respectively have been studied using both X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS). The UPS valence band spectra, are interpreted with the help of quantum chemical calculations based upon Modified Neglect of Diatomic Overlap (MNDO), Valence Effective Hamitonian (VEH) and ab initio Hartree-Fock methods. DP7 is a model molecule for polyacetylene, while 6T is a model molecule (an oligomer) of polythiophene. The results indicate that aluminum reacts strongly with the surfaces of all of the materials studied. The π-electronic structure of each material was strongly modified. Furthermore, aluminum reacts preferentially with the polyene partof DP7, with the vinylene part of PPV, and with the α-carbons of the thiophene nits of 6T.

  • 8.
    Dannetun, Per
    et al.
    Groupe de Physique des Solides, Tour 23-2, place Jussieu, 752 51 Paris Cedex 05, France.
    Lögdlund, Michael
    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.
    Fauquet, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Beljonne, D.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, place du Parc 20, B-7000 Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, place du Parc 20, B-7000 Mons, Belgium.
    Bässler, H.
    Fachbereich Physikalische Chemie und Zentrum für Materialwissenschaften der Phillips-Universität, Hans-Meerwein-Strasse, W-3550 Marburg, Germany.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The evolution of charge-induced gap states in degenerate and non-degenerate conjugated molecules and polymers as studied by photoelectron spectroscopy1994In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1, p. 81-86Article in journal (Refereed)
    Abstract [en]

    We report the results of ultraviolet photoelectron spectroscopy (UPS) studies of the interaction between sodium and conjugated systems for a series of diphenylpolyees and diffrent oligomers of poly(p-phenylenevinylene) (PPV). The diphenylpolyenes include molecules containing two (i.e., stilbene) to 14 carbon atoms in the polyene part; stilbene itself can also be considered as a phenyl-capped monomer of PPV. Furthermore, a PPV oligomer with three phenylene units, as well as PPV itself, has been studied. The experimental results are interpreted with the help of quantum-chemical calculations using the Hartree-Fock semi-empirical Austin Model 1 (AM1) and valence-effective Hamiltonian (VEH) methods. An important result is that all the systems react strongly with sodium; at high doping levels two new doping-induced states are detected above the valence band edge of the pristine material. In the case of saturation-doped diphenylpolyenes (i.e., two sodiums per molecule), the new states can be discussed in terms of soliton-antisoliton pairs confined within the polyene part of the molecules; in contrast, the self-localized states induced in PPV and its oligomers have to be referred to as bipolarons.

  • 9.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Fredriksson, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Fauquet, C.
    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.
    Spangler, C. W.
    Department of Chemistry, Northern Illinois University, Dekalb, Illinois 60115, USA.
    Bredás, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Reactions of low work function metals Na, Al, and Ca on α,ω-€diphenyltetradecaheptaene. Implications for metal/polymer interfaces1994In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 100, no 9, p. 6765-6771Article in journal (Refereed)
    Abstract [en]

    The interactions between different low work function metals aluminium,calcium and sodium, and α,ω‐diphenyltetradecaheptaene, a model molecule for certain conjugated polymers, have been investigated using both x‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The spectra are interpreted with the help of the results of quantum chemical calculations performed within the local spin density (LSD) approximation methodology. The metals are found to interact with the conjugated system in very different ways. Aluminium forms a covalent bond, which strongly modifies the π‐electronic structure of the conjugated molecule, while both the sodium and the calcium atoms act as doping agents, inducing new states in the otherwise forbidden bandgap. These new gap states can be viewed as a soliton–antisoliton pair for the Na/DP7 and a bipolaronic‐like defect for Ca/DP7.

  • 10.
    Dannetun, Per
    et al.
    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.
    Fredriksson, C.
    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.
    Holmes, A. B.
    Cavendish Laboratory , University of Cambridge Cambridge , CB3 OHE, England.
    Brown, A.
    Cavendish Laboratory , University of Cambridge Cambridge , CB3 OHE, England.
    Graham, S.
    Cavendish Laboratory , University of Cambridge Cambridge , CB3 OHE, England.
    Friend, R. H.
    Cavendish Laboratory , University of Cambridge Cambridge , CB3 OHE, England.
    Lhost, O.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    New Results on Metal-Polymer Interfaces1993In: Molecular Crystals and Liquid Crystals, ISSN 1542-1406, E-ISSN 1563-5287, Vol. 228, no 1, p. 43-48Article in journal (Refereed)
    Abstract [en]

    New results on studies of the early stages of formation of the aluminum-poly(p-phenylenevinylene) interface are presented.

  • 11.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    Université de Mons-Hainaut, Belgium.
    Spangler, C. W.
    Northen Illinois University, USA.
    Bredas, J. L.
    Université de Mons-Hainaut, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. william.r.salaneck@liu.se.
    Evolution of Charge-Induced Gap States in Short Diphenylpolyenes as Studied by Photoelectron Spectroscopy1994In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, The Journal of Physical Chemistry, Vol. 98, no 11, p. 2853-2858Article in journal (Refereed)
    Abstract [en]

    The evolution of doping-induced electronic states within the otherwise forbidden energy gap has been studied as a function of the polyene length in a series of diphenylpolyenes. The chemical and electronic structures ha ve been studied using both X-ray and ultraviolet photoelectron spectroscopies. The results are interpreted with the help of quantum chemical calculations, performed using the semiempirical Austin Model 1 and valence effective Hamiltonian methods. The molecules studied area series of diphenylpolyenes, DPx, with x = 1-7 C=C double bonds in the pol yene part of the molecule. Since the frontier or bitals of the diphenylpolyenes are localized on the polyene chain portion of the molecule, there is a high degree of separation of the phenyl and polyene parts of the 11"-systems. Hence, many chemical and electronic properties of diphenylpolyenes are expected to be similar to those of short-chain trans-polyacetylene. For the longer molecules, n = 6 or 7, the present results indicate the presence of doubly charged, interacting soliton-antisoliton pairs, which appear as two new energy levels in the otherwise forbidden energy gap. In diphenyldecaheptaene to stilbene, i.e. 1 ≤ x ≤ 5, however, a singly charged state is formed at intermediate doping levels, after which the soliton-antisoliton pairs appear for the fully doubly charged systems. These results show that, remarkably, even for very short polyene  segments, charges transferred are stored in the form of ( confined) solitons.

  • 12.
    Dannetun, Per
    et al.
    Groupe de Physique des Solides, Unité associée au CNRS 040017, Universités Paris 7 et Paris 6, Tour 23, 2 Place Jussieu, France.
    Schott, M
    Groupe de Physique des Solides, Unité associée au CNRS 040017, Universités Paris 7 et Paris 6, Tour 23, 2 Place Jussieu, France.
    Vilar, M.Rei
    Laboratoire de Spectrochimie Infrarouge et Raman (CNRS), Thiais, France.
    High-resolution electron energy loss spectroscopy of thin crystalline highly oriented films of poly(tetrafluoroethylene)1996In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 286, no 1-2, p. 321-329Article in journal (Refereed)
    Abstract [en]

    High-resolution electron energy loss spectroscopy (HREELS) spectra of highly oriented films of poly(tetrafluoroethylene) (PTFE) are reported. With one exception, all peaks in the spectra correspond to IR active vibrations. They are well resolved, and with a remarkably high intensity, more than two orders of magnitude greater than we have observed on any other polymer in HREELS. The angular distributions of the elastic peak, and of the vibrational peaks are very narrow, which indicates both a well ordered system and a dipolar scattering behaviour. No evidence of amorphous regions in these films is found. A Raman active mode can be observed in off-specular geometry, using an incident electron beam coplanar with the PTFE fibers direction. This corresponds to resonance excitation of a transient negative ion state, with a maximum cross-section at an incident electron kinetic energy of about 4 eV.

  • 13.
    Fauquet, C.
    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.
    Fredriksson, C.
    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.
    Bourée, J. E.
    CNRS, Laboratoire de Meudon, Meudon, France.
    Brillaud, P.
    SMI Organometallics Division, 13 000 Marseille, France.
    Bouanah, N.
    SMI Organometallics Division, 13 000 Marseille, France.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Electronic structure of trimethylamine alane in the solid state1995In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 235, no 5-6, p. 528-534Article in journal (Refereed)
    Abstract [en]

    The chemical and electronic structure of ultrathin molecular films of trimethylamine alane (TMAA), condensed in UHV at − 100°C, have been studied in the solid state, using both X-ray and ultraviolet photoelectron spectroscopy. The results are analyzed with the help of quantum chemical calculations at the ab initio Hartree-Fock 6-31G∗ level. Based upon the good agreement between theory and experimental, it is determined that clean, oxygen-free, condensed molecular solid films consist of the 2:1 adduct of TMAA, which was previously uncertain. In addition, based upon the electronic structure results, it is clear that the mechanism of the photodecomposition of TMAA can be explained in terms of the wavefunction of electrons photoexcited into the first unoccupied molecular orbital.

  • 14.
    Fredriksson, C.
    et al.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Bredas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    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.
    Theoretical studies of the aluminum/poly(p-phenylene vinylene) interface1993In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 57, no 2, p. 4632-4637Article in journal (Refereed)
    Abstract [en]

    A molecular quantum chemical approach is used to study the aluminum on PPV (Poly(p-Phenylene Vinylene)) interface. We focus on modifications to the chemical and electronic structure of the polymer upon interaction with a submonolayer of aluminum. A model system, trans-stilbene, is taken to investigate the nature of the Al-PPV bonding. Energetically favorable conformations are then used as prototypes to study the evolution of the electronic structure as modified by the reaction with aluminum. Results at the ab initio Hartree-Fock level indicates that Al atoms react with the vinylene linkage rather than the phenyl groups at early stages of interface formation.

  • 15.
    Fredriksson, C.
    et al.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Bredas, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    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.
    Theoretical studies of the aluminum/trans-polyacetylene interface: Calculations of model systems and comparison to experiment1993In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 57, no 2-3, p. 4590-4595Article in journal (Refereed)
    Abstract [en]

    The interaction between Al atoms and trans-polyacetylene has been studied quantum chemically at the ab initio Hartree-Fock level using oligomeric model systems. Investigations of the Al-polyacetylene bonding and modifications to the chemical and electronic structure of model systems for polyacetylene upon interaction with Al atoms are reported. The density-of-states is calculated for a polyene chain interacting with a pair of Al atoms. The results are discussed in relation to photoelectron spectra taken during Al deposition on an oligomeric model for polyacetylene (a diphenylpolyene with 7 C=C bonds in the polyene segment).

  • 16.
    Lazzaroni, R.
    et al.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Belgium.
    Chtaïb, M.
    Laboratoire Interdépartemental de Spectroscopie Electronique, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
    Snauwaert, P.
    Laboratoire Interdépartemental de Spectroscopie Electronique, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium .
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Uvdal, Kajsa
    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.
    Electronic Structure of Metal/Polymer Interfaces: Aluminum on Conjugated Polymers1991In: Metallized Plastics 2: Fundamental and Applied Aspects / [ed] Kashmiri Lal Mittal, Springer, 1991, p. 199-212Chapter in book (Other academic)
    Abstract [en]

    Aluminum has been deposited on two types of conjugated polymers, polyalkylthiophene and polyaniline. The polymers were in the undoped, neutral form which possesses semiconducting properties. The chemical structure of the metal/polymer interface has been investigated by X-ray and UV photoelectron spectroscopy. Core level spectra indicate that aluminum reacts with the sulfur atom of the polythiophene chain, strongly perturbing the π-electron system. In the case of polyaniline, the interaction with the metal depends on the oxidation state of the polymer. UPS data, combined with the results of band structure calculations, are interpreted in terms of the Al-induced modifications of the π-electron system.

  • 17.
    Lazzaroni, R.
    et al.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Mons, Belgium.
    Dannetun, Per
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Mons, Belgium.
    Fredriksson, C.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Mons, Belgium.
    Stafström, Sven
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Mons, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The chemical and electronic structure of the interface between aluminum and conjugated polymers1994In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 39, no 2, p. 235-244Article in journal (Refereed)
    Abstract [en]

    The chemical and electronic structure of the interface between aluminum and several proto-typical conjugated systems is investigated with a combined experimental and theoretical approach. The experiments consists of following the evolution of the polymer surface during the early stages of aluminum deposition, with X-ray and Ultraviolet Photoelectron Spectroscopies (XPS, UPS). In parallel, quantum chemical calculations are performed on model oligomer systems interacting with isolated Al atoms. Aluminum is found to interact strongly with the polymer chain. New covalent Al-carbon bonds are formed along the polymer backbone; the chain geometry is deeply modified and the π electron conjugation can be dramatically reduced.

  • 18.
    Lazzaroni, R.
    et al.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons-Hainaut, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lögdlund, Michael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Uvdal, Kajsa
    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.
    Electronic structure of the aluminum/polythiophene interface: A joint experimental and theoretical study1991In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 43, no 1-2, p. 3323-3328Article in journal (Refereed)
    Abstract [en]

    Not Available.

  • 19.
    Lazzaroni, R.
    et al.
    Service de Chimie des Maririaux Nouveaux Département des Matériaux et Procédés Universitt de Mons-Hainaw, Mons, Belgium.
    Fredriksson, C.
    Service de Chimie des Maririaux Nouveaux Département des Matériaux et Procédés Universitt de Mons-Hainaw, Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Maririaux Nouveaux Département des Matériaux et Procédés Universitt de Mons-Hainaw, Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Boman, Magnus
    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.
    The Chemical and Electronic Structure of Metal/Conjugated Polymer Interfaces: A Joint Theoretical and Experimental Study1993In: Intrinsically Conducting Polymers: An Emerging Technology / [ed] M. Aldissi, Springer Netherlands, 1993, p. 135-146Chapter in book (Refereed)
    Abstract [en]

    We investigate the interface between aluminum and several prototypical conjugaced systems wich a combined experimental and theoretical approach. The experiments consist of following the evolution of the polymer surface during the early stages of aluminum deposition, with X-ray and Ultraviolet Photoe!ectron Spectroscopies (XPS, UPS). In parallel, we perform quantum chemical calculacions on mode! oligomer systems interacting with one to four Al atoms. Aluminum is found to internet strongly with the polymer chain. Al·carbon covalenc boods an: formed along the polymer backbone; the chain geomeuy is deeply modified and the π electron conjugation can be dramatically reduced.

  • 20.
    Lazzaroni, R.
    et al.
    Service de Chimie des Matériaux Nouveaux Centre de Recherche en Electronique et Photonique Moléculaires Université de Mons-Hainaut, Mons, Belgium.
    Lögdlund, Michael
    Service de Chimie des Matériaux Nouveaux Centre de Recherche en Electronique et Photonique Moléculaires Université de Mons-Hainaut, Mons, Belgium.
    Calderone, A.
    Service de Chimie des Matériaux Nouveaux Centre de Recherche en Electronique et Photonique Moléculaires Université de Mons-Hainaut, Mons, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux Centre de Recherche en Electronique et Photonique Moléculaires Université de Mons-Hainaut, Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fauquet, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fredriksson, C.
    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.
    Chemical and electronic aspects of metal/conjugated polymer interfaces: Implications for electronic devices1995In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 71, no 1-3, p. 2159-2162Article in journal (Refereed)
    Abstract [en]

    The chemical nature and the electronic structure of metal/conjugated polymer interfaces are investigated in the context of polymer-based light-emitting diodes. We consider the interaction of low-workfunction metals (Al, Ca) with the surface of conjugated polymers or model oligomer molecules with a combined experimental and theoretical approach. The early stages of the interface formation are followed with X-ray and ultraviolet photoelectron spectroscopies and the experimental data are compared to the results of quantum chemical calculations. The reactions of Al and Ca with the organic surface are found to be fundamentally different: while the former forms new covalent bonds onto the polymer backbone, the latter tends to dope the conjugated system. Both types of reaction are expected to modify drastically the electronic properties of the polymer semiconductor.

  • 21.
    Lögdlund, Michael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fredriksson, C.
    Ecole Polytechnique de Montréal, Centre de Recherche Appliquée Sur les Polymères (CRASP), Département de Génie Chimique, Case Postale 6079, Succursale A, Montréal, Québec, H3C 3A7 Canada.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Mons, Belgium.
    Theoretical and experimental studies of the interaction between sodium and oligothiophenes1996In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 53, no 24, p. 16327-16333Article in journal (Refereed)
    Abstract [en]

    Quantum-chemical calculations and ultraviolet photoelectron spectroscopy (UPS) measurements have been performed in order to study the interaction between sodium and oligothiophenes, with a focus on the origin of experimentally observed relaxation energy effects in alkali-metal-doped conjugated molecules. Upon doping of a -sexithienylene (α-6T) with sodium atoms, (1) a broad feature appears in the valence band, in an energy region corresponding to the band gap in pristine α-6T, and (2) certain structural features in the valence band shift towards lower binding energies in the doped material. In particular, upon doping, a structural peak related to electronic levels mainly localized to the sulfur and b-carbon atoms destabilizes to an energy corresponding to that of the valence-band edge in pristine α-6T. The results of ab initio Hartree-Fock and local-spin-density calculations on α-trithienylene and bithiophene are consistent with the experimental data, and allow for an assignment of these destabilization effects in terms of initial-state relaxations. We stress that similar destabi-lization effects, reported for other alkali-metal-doped conjugated systems, had previously been proposed to be associated with final-state electronic screening, i.e., a dynamic artifact within the UPS measurements; this is in contradiction to the results of our ab initio theoretical studies. Our present results show that all structural features in the UPS data are contained in the results of sufficiently complete quantum chemical calculations.

  • 22.
    Lögdlund, Michael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Mons, Belgium.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Groupe de Physique des Solides, place Jussieu, 75251 Paris Cedex 05, France.
    Fredriksson, C.
    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.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Mons, Belgium.
    Theoretical study of the interaction between sodium and oligomers of poly(p-phenylenevinylene) and poly(p-phenylene)1994In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 67, no 1-3, p. 141-145Article in journal (Refereed)
    Abstract [en]

    The semi-empirical Austin Model 1 and the non-empirical pseudo-potential valence effective Hamiltonian (VEH) methods as well as the local spin density (LSD) approximation technique have been applied to the investigation of the doping-induced electronic and geometrical changes in some conjugated molecules related to poly(p-phenylene) and poly(p-phenylenevinylene) (PPV): biphenyl, stilbene and a phenyl-capped dimer of PPV. The theoretical results are compared with experimental valence band spectra, as recorded by ultraviolet photoelectron spectroscopy (UPS). The experimental UPS studies show that two ingap states are detected upon doping with alkali metals. The energy splitting between the two in-gap states increases as the molecule size decreases. The results of the LSD calculations agree very well with the experimental results, while the VEH method overestimates the energy splitting for the small molecules. The LSD modelling also indicates a destabilization of several high binding energy valence levels, due to the presence of counter-ions, in agreement with experiment.

  • 23.
    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.
    Fredriksson, C.
    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, Faculty of Science & Engineering.
    Sprangler, C. W.
    Deartment of Chemistry, Nothern lllinois University, USA.
    Brédas, J. L.
    lService de Chimie des Materiaux Nouveaux, Université de Mons-Hainaut, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Experimental and Theoretical Studies of the Interaction of Metals with Polymer Surfaces: A Case Study of the Use of a Model Molecular System to Study the Nature of Charge Storage in Short Polyenes1994In: Frontiers of Polymers and Advanced Materials / [ed] Paras N Prasad, Springer-Verlag New York, 1994, p. 369-382Chapter in book (Refereed)
    Abstract [en]

    The electronic and geometric changes in polyenes induced by doping with sodium have been studied using X-ray and Ultraviolet Photoeclectron Spectroscopy, and quantum chemical calculations. The molecular geometry changes induced by doping have been studied using the semiempirical Austin Model 1 method, the results of which has served as input parameters for Valence Effective Hamiltonian band structure calculations, which are compared with the experimental density-of-states data. The molecules studied are members of a series of diphenylpolyenes with 4, 5, 6 ir 7 C=C double bonds in the polyene part of the molecule, i.e., the series DPx, with x = 4, 5, 6 or 7. Since the frontier orbitals of the diphenylpolyenes are localized mostly on the polyene chain portion of the molecule, there is a high degree of separations in energy of the phenyl and polyene parts of the π-system. Hence, many chemical and electronic properties of diphenylpolyenes are similar to those of (at least short chain) trans-polyacerylene. The present doping results indicate the charge is stored in short polyenes in the form of two confined solitons per molecule.

  • 24.
    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.
    Sjögren, B.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Fredriksson, C.
    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.
    The electronic structure of α,ω-diphenyltetradecaheptaene, a model molecule for polyacetylene, as studied by photoelectron spectroscopy1992In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 51, no 1, p. 187-195Article in journal (Refereed)
    Abstract [en]

    The advantages of using model systems for spectroscopic studies of conjugated polymers and interface formation, as well as for charge-induced electronic and geometric structural changes, are discussed. The electronic structure of a diphenylpolyene, α,ω-diphenyltetradecaheptaene, or DP7, is an example of a model molecular system studied using X-ray and Ultraviolet Photoelectron Spectroscopy, XPS, and UPS. The spectra are interpreted with the help of the results from MNDO, VEH and INDO/S-CI quantum chemical calculations. The frontier orbitals of DP7 are localized mostly on the polyene chain portion of the molecule, resulting in a high degree of separation of the phenyl and polyene parts of the π-system. The INDO calculations show two regions of shake-up features corresponding to a benzene-like part and a polyene-like part. The most important individual shake-up transitions, which contribute to the two observed shake-up spectral features, involve one-electron redistributions separable into contributions from the polyene chain and from the phenyl groups. The analysis indicates the extent to which many chemical and electronic properties of DP7 are expected to be similar to those of (at least short chain) trans-polyacetylene.

  • 25.
    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.

  • 26.
    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.

  • 27.
    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)
  • 28.
    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.

1 - 28 of 28
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