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  • 101.
    Herlogsson, Lars
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Cölle, Michael
    Merck Chemicals Ltd Chilworth Science Park Southampton, SO16 7QD, UK.
    Tierney, Steven
    Merck Chemicals Ltd Chilworth Science Park Southampton, SO16 7QD,l UK.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Low-Voltage Ring Oscillators Based on Polyelectrolyte-Gated Polymer Thin-Film Transistors2010In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 22, no 1, p. 72-76Article in journal (Refereed)
    Abstract [en]

    A polyanionic electrolyte is used as gate insulator in top-gate p-channel polymer thin-film transistors. The high capacitance of the polyelectrolyte film allows the transistors and integrated circuits to operate below 1.5 V. Seven-stage ring oscillators that operate at supply voltages down to 0.9 V and exhibit signal propagation delays as low as 300 µs per stage are reported.

  • 102.
    Crispin, Xavier
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Larsson, Oscar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Said, Elias
    Royal Institute of Technology, Stockholm, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Polyelectrolyte-Gated Organic Field-Effect Transistors2010In: Iontronics: Ionic Carriers in Organic Electronic Materials and Devices / [ed] Janell Leger, Magnus Berggren, Sue Carter, Boca Raton: CRC Press; Taylor & Francis Group , 2010, p. 193-218Chapter in book (Other academic)
    Abstract [en]

    The field of organic electronics promises exciting new technologies based on inexpensive and mechanically flexible electronic devices. It has progressed over the past three decades to the point of commercial viability and is projected to grow to a 30 billion dollar market by the year 2015. Exploring new applications and device architectures, this book sets the tone for that exploration, gathering a community of experts in this area who are focused on the use of ionic functions to define the principle of operation in polymer devices. The contributors detail relevant technologies based on organic electronics, including polymer electrochromic devices and light-emitting electrochemical cells.

  • 103.
    Larsson, Oscar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wang, Xiaodong
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. null.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. null.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. null.
    Proton motion in a polyelectrolyte: A probe for wireless humidity sensors2010In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 143, no 2, p. 482-486Article in journal (Refereed)
    Abstract [en]

    Low-cost passive wireless electronic sensor labels glued onto packages are highly desirable since they enable monitoring of the status of the packages for instance along the logistic chain or while stored at a shelf. Such additional sensing feature would be of great value for many producers and vendors, active in e.g. the food or construction industries. Here, we explore a novel concept for wireless sensing and readout, in which the humidity sensitive ionic motion in a polyelectrolyte membrane is directly translated into a shift of the resonance frequency of a resonance circuit. Thanks to its simplicity, the wireless sensor device itself can be manufactured entirely using common printing techniques and can be integrated into a low-cost passive electronic sensor label.

  • 104.
    Wadeasa, Amal
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tzamalis, G
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sehati, Parisa
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Solution processed ZnO nanowires/polyfluorene heterojunctions for large area lightening2010In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 490, no 4-6, p. 200-204Article in journal (Refereed)
    Abstract [en]

    Hybrid inorganic-organic semiconductor heterojunctions are nowadays scrutinized for optoelectronic devices, such as solar cells and light emitting diodes. Here, ZnO nanowires/polyfluorene heterojunctions have been entirely fabricated from solution by wet chemistry and low temperature processes. The transparent plastic electrode PEDOT injects holes in the polyfluorene, while the electrons are injected via the ZnO-Au contact, thus avoiding the use of air sensitive low work function metals. The hybrid inorganic-organic light emitting diode emits almost white light. Because of its solution processability, stable cathode, low cost and low temperature process, the ZnO/polymer heterojunction devices are promising for large area lightening applications.

  • 105.
    Xuan, Yu
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Desbief, S.
    Service de Chimie des Matériaux Nouveaux, Université de Mons (UMONS), Place du Parc 20, B-7000 Mons, Belgium.
    Leclére, P.
    Service de Chimie des Matériaux Nouveaux, Université de Mons (UMONS), Place du Parc 20, B-7000 Mons, Belgium.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons (UMONS), Place du Parc 20, B-7000 Mons, Belgium.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Cornil, .
    Service de Chimie des Matériaux Nouveaux, Université de Mons (UMONS), Place du Parc 20, B-7000 Mons, Belgium.
    Emin, D.
    Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, USA.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Thermoelectric properties of conducting polymers: The case of poly(3-hexylthiophene)2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 11, p. 115454-115463Article in journal (Refereed)
  • 106.
    Liu, Jiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sawadtee, A
    Acreo AB.
    Favia, P
    IMEC.
    Sandberg, M
    Acreo AB.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Engquist, Isak
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Vertical polyelectrolyte-gated organic field-effect transistors2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, p. 103303-Article in journal (Refereed)
    Abstract [en]

    Short-channel, vertically structured organic transistors with a polyelectrolyte as gate insulator are demonstrated. The devices are fabricated using low-resolution, self-aligned, and mask-free photolithography. Owing to the use of a polyelectrolyte, our vertical electrolyte-gated organic field-effect transistors (VEGOFETs), with channel lengths of 2.2 and 0.7 μm, operate at voltages below one volt. The VEGOFETs show clear saturation and switch on and off in 200 μs. A vertical geometry to achieve short-transistor channels and the use of an electrolyte makes these transistors promising candidates for printed logics and drivers with low operating voltage.

  • 107.
    Said, Elias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, Peter
    ACREO AB, Bredgatan 34, SE-602 21 Norrköping, Sweden.
    Engquist, Isak
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Electrochromic display cells driven by an electrolyte-gated organic field-effect transistor2009In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 10, no 6, p. 1195-1199Article in journal (Refereed)
    Abstract [en]

    Monolithic integration of an electrolyte-gated organic field-effect transistor (OFET) and an organic electrochromic pixel is reported. Thanks to its versatility, the polyanionic proton conductor poly(styrenesulfonic acid) (PSSH) can serve both as the gate “insulator” in OFETs and as the electrolyte in electrochromic display pixels. Employing identical materials in both the display cells and in the driver transistors is a necessary prerequisite to achieve robust displays possible to manufacture on flexible carriers using printing tools. Smart pixels combining depletion mode electrochemical transistors and electrochromic displays have been reported in the past. Here, an enhancement mode OFET as the driver enables relatively shorter updating times and much simpler addressing and updating schemes.

  • 108.
    Hamedi, Mahiar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Marcilla, Rebeca
    CIDETEC, Spain.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Fiber-Embedded Electrolyte-Gated Field-Effect Transistors for e-Textiles2009In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 21, no 5, p. 573-577Article in journal (Refereed)
    Abstract [en]

    Electrolyte-gate organic field-effect transistors embedded at the junction of textile microfibers are demonstrated. The fiber transistor operates below I V and delivers large current densities. The transience of the organic thin-film transistors current and the impedance spectroscopy measurements reveal that the channel is formed in two steps.

  • 109.
    Larsson, Oscar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Said, Elias
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. null.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. null.
    Insulator Polarization Mechanisms in Polyelectrolyte-Gated Organic Field-Effect Transistors2009In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 19, no 20, p. 3334-3341Article in journal (Refereed)
    Abstract [en]

    Electrolyte-gated organic field-effect transistors (OFETs) hold promise for robust printed electronics operating at low voltages. The polarization mechanism of thin solid electrolyte films, the gate insulator in such OFETs, is still unclear and appears to limit the transient current characteristics of the transistors. Here, the polarization response of a thin proton membrane, a poly(styrenesulfonic acid) film, is controlled by varying the relative humidity. The formation of the conducting transistor channel follows the polarization of the polyelectrolyte, such that the drain transient current characteristics versus the time are rationalized by three different polarization mechanisms: the dipolar relaxation at high frequencies, the ionic relaxation (migration) at intermediate frequencies, and the electric double-layer formation at the polyelectrolyte interfaces at low frequencies. The electric double layers of polyelectrolyte capacitors are formed in 1 µs at humid conditions and an effective capacitance per area of 10 µF cm-2 is obtained at 1 MHz, thus suggesting that this class of OFETs might operate at up to 1 MHz at 1 V.

  • 110.
    Jakobsson, Fredrik L. E.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Prediction of the current versus voltage behavior of devices based on organic semiconductor host-guest systems2009In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 10, no 1, p. 95-106Article in journal (Refereed)
    Abstract [en]

    Organic semiconductor blends are commonly used in organic based (opto-)electronic devices. They are composed of two types of (macro-) molecules, referredto as the guest and host. To achieve optimum device operation, the chemicalnature, electronic structure, molecular order and the relative concentration of theguests and host are crucial. Here, we present simulation results of the currentdensity versus the voltage (J-V) behavior of a two-terminal device based on avariable-range hopping model in which the electronic states of the guest and hostare represented by two Gaussian distributions. The J-V behavior is investigatedfor various energetic mismatches between guest and host states, widths of thedistribution as well as the guest concentration. Finally, a simple tool enablingeasy prediction of the J-V behavior of organic host-guest diodes is derived.

  • 111.
    Jakobsson, Fredrik
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Marsal, Philippe
    University Mons Hainaut.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Cornil, Jerome
    University Mons Hainaut.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tuning the Energy Levels of Photochromic Diarylethene Compounds for Opto-electronic Switch Devices2009In: JOURNAL OF PHYSICAL CHEMISTRY C, ISSN 1932-7447, Vol. 113, no 42, p. 18396-18405Article in journal (Refereed)
    Abstract [en]

    Diarylethene molecules are photochromics (PCs) currently investigated for use in optical write/electrical read memory applications. The impact of the photoisomerization of PCs on the device behavior is analyzed with charge transport models. These results indicate that good electrical current switching can be achieved in a device when the PCs are combined with an organic semiconductor (in multilayered structures or blends). The frontier energy levels and dipole moment of a series of diarylethene compounds have been calculated using density functional theory. A good agreement is found between the calculated electronic structure and the measured ultraviolet photoelectron spectra. Shirts in the frontier energy levels and dipole moment are generated through two different approaches for chemical modification: (i) by changing the chemical nature of the aryl rings or (ii) by adding substituents on the ethylene, bridge. The frontier energy levels can be tuned by more than 2 eV via such chemical modifications. We find that, for this family of photochromic compounds, the photoinduced current switch effect in diodes is mainly due to the modulation in the frontier energy levels rather than the changes in the amplitude of the dipole moment.

  • 112.
    Herlogsson, Lars
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Noh, Yong-Young
    Cavendish Laboratory University of Cambridge, UK.
    Zhao, Ni
    Cavendish Laboratory University of Cambridge, UK.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sirringhaus, Henning
    Cavendish Laboratory University of Cambridge, UK.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Downscaling of Organic Field-Effect Transistors with a Polyelectrolyte Gate Insulator2008In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 20, no 24, p. 4708-4713Article in journal (Refereed)
    Abstract [en]

    A polyelectrolyte is used as gate insulator material in organic field-effect transistors with self-aligned inkjet printed sub–micrometer channels. The small separation of the charges in the electric double layer at the electrolyte-semiconductor interface, which builds up in tens of microseconds, provides a very high transverse electric field in the channel that effectively suppresses short-channel effects at low applied gate voltages.

  • 113.
    Said, Elias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Larsson, Oscar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Effects of the Ioinc Currents in Electrolyte-gated Organic Field-Effect Transistors2008In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 21, p. 3529-3536Article in journal (Refereed)
    Abstract [en]

    Polyelectrolytes are promising materials as gate dielectrics in organic field-effect transistors (OFETs). Upon gate bias, their polarization induces an ionic charging current, which generates a large double layer capacitor (10-500 µF cm-2) at the semiconductor/electrolyte interface. The resulting transistor operates at low voltages (<1 V) and its conducting channel is formed in 50 µs. The effect of ionic currents on the performance of the OFETs is investigated by varying the relative humidity of the device ambience. Within defined humidity levels and potential values, the water electrolysis is negligible and the OFETs performances are optimum.

  • 114.
    Lindell, Linda
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Unge, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Osikowicz, Wojciech
    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.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    de Jong, Michael P
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Integer charge transfer at the tetrakis(dimethylamino)ethylene/Au interface2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 16, p. 163302-1-163302-3Article in journal (Refereed)
    Abstract [en]

    In organic-based electronics, interfacial properties have a profound impact on device performance. The lineup of energy levels is usually dependent on interface dipoles, which may arise from charge transfer reactions. In many applications, metal-organic junctions are prepared under ambient conditions, where direct overlap of the organic system from the metal bands is prevented due to presence of oxides and/or hydrocarbons. We present direct experimental and theoretical evidence showing that the interface energetic for such systems is governed by exchange of an integer amount of electrons.

  • 115.
    Fahlman, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Crispin, Annica
    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.
    Henze, S.K.M.
    de Jong, Michel P
    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 .
    Tengstedt, Carl
    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 .
    Electronic structure of hybrid interfaces for polymer-based electronics2007In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 19, no 18Article, review/survey (Refereed)
    Abstract [en]

    The fundamentals of the energy level alignment at anode and cathode electrodes in organic electronics are described. We focus on two different models that treat weakly interacting organic/metal (and organic/organic) interfaces: the induced density of interfacial states model and the so-called integer charge transfer model. The two models are compared and evaluated, mainly using photoelectron spectroscopy data of the energy level alignment of conjugated polymers and molecules at various organic/metal and organic/organic interfaces. We show that two different alignment regimes are generally observed: (i) vacuum level alignment, which corresponds to the lack of vacuum level offsets (Schottky-Mott limit) and hence the lack of charge transfer across the interface, and (ii) Fermi level pinning where the resulting work function of an organic/metal and organic/organic bilayer is independent of the substrate work function and an interface dipole is formed due to charge transfer across the interface. We argue that the experimental results are best described by the integer charge transfer model which predicts the vacuum level alignment when the substrate work function is above the positive charge transfer level and below the negative charge transfer level of the conjugated material. The model further predicts Fermi level pinning to the positive (negative) charge transfer level when the substrate work function is below (above) the positive (negative) charge transfer level. The nature of the integer charge transfer levels depend on the materials system: for conjugated large molecules and polymers, the integer charge transfer states are polarons or bipolarons, for small molecules' highest occupied and lowest unoccupied molecular orbitals and for crystalline systems, the relevant levels are the valence and conduction band edges. Finally, limits and further improvements to the integer charge transfer model are discussed as well as the impact on device design. © IOP Publishing Ltd.

  • 116.
    Herlogsson, Lars
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Robinson, Nathaniel D
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sandberg, M.
    Thin Film Electronics AB.
    Hagel, O.-J.
    Thin Film Electronics AB.
    Gustafsson, G.
    Acreo AB.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Low-Voltage Polymer Field-Effect Transistors Gated via a Proton Conductor2007In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 19, no 1, p. 97-101Article in journal (Refereed)
    Abstract [en]

    Low operating voltages for p-channel organic field-effect transistors (OFETs) can be achieved by using an electrolyte as the gate insulator. However, mobile anions in the electrolyte can lead to undesired electrochemistry in the channel. In order to avoid this, a polyanionic electrolyte is used as the gate insulator. The resulting OFET has operating voltages of less than 1 V (see figure) and shows fast switching (less than 0.3 ms) in ambient atmosphere.

  • 117.
    Tehrani, Payman
    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.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Robinson, Nathaniel D.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    The effect of pH on the elechtrochemical over-oxidation of PEDOT:PSS films2007In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 177, no 39-40, p. 3521-3527Article in journal (Refereed)
    Abstract [en]

    Chemical degradation of conjugated polymers is one cause of material failures in polymer-based (opto)electronic devices, but can also be used as a technique for subtractive patterning of polymer films. When a large anodic potential is applied to the conducting polymer blend poly(3,4-ethylenedioxythiophene)-poly(4styrenesulfonate), PEDOT:PSS, an over-oxidation reaction occurs, altering its electrical conductivity. Here, we have studied the effect of pH on the electrochemical over-oxidation process of PEDOT in PEDOT:PSS. High pH is associated with a decrease of over-oxidation potential and an increase of resistivity in the resulting film. Vibrational spectroscopy and photoelectron spectroscopy measurements on over-oxidized PEDOT:PSS films indicate that the decrease in conductivity results from cleavage of the conjugation pathway accompanied by the formation of sulfone, carbonyl and carboxylic groups in the polymer chain.

  • 118.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Andersson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Robinson, Nathaniel D
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Olivier, Yoann
    Laboratory for Chemistry of Novel Materials, Université de Mons. Mons, Belgium.
    Cornil, Jerome
    Belgian National Fund for Scientific Research (FNRS), Université de Mons. Mons, Belgium.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Photochromic Diodes2006In: Semiconducting Polymers: chemistry, physics and engineering. Vol. 2 / [ed] Georges Hadziioannou, George Malliaras, Weinheim, Tyskland: WileyVCH Verlag GmbH & Co , 2006, 2, p. 579-611Chapter in book (Other academic)
    Abstract [en]

      The field of semiconducting polymers has attracted many researchers from a diversity of disciplines. Printed circuitry, flexible electronics and displays are already migrating from laboratory successes to commercial applications, but even now fundamental knowledge is deficient concerning some of the basic phenomena that so markedly influence a device's usefulness and competitiveness. This two-volume handbook describes the various approaches to doped and undoped semiconducting polymers taken with the aim to provide vital understanding of how to control the properties of these fascinating organic materials. Prominent researchers from the fields of synthetic chemistry, physical chemistry, engineering, computational chemistry, theoretical physics, and applied physics cover all aspects from compounds to devices.Since the first edition was published in 2000, significant findings and successes have been achieved in the field, and especially handheld electronic gadgets have become billion-dollar markets that promise a fertile application ground for flexible, lighter and disposable alternatives to classic silicon circuitry. The second edition brings readers up-to-date on cutting edge research in this field.

  • 119.
    Said, Elias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Elhag, Sami
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Robinson, Nathaniel D.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Polymer field-effect transistor gated via a poly(styrenesulfonic acid) thin film2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 14, p. 143507-Article in journal (Refereed)
    Abstract [en]

    A polyanionic proton conductor, named poly(styrenesulfonic acid) (PSSH), is used to gate an organic field-effect transistor (OFET) based on poly(3-hexylthiophene) (P3HT). Upon applying a gate bias, large electric double layer capacitors (EDLCs) are formed quickly at the gate-PSSH and P3HT-PSSH interfaces due to proton migration in the polyelectrolyte. This type of robust transistor, called an EDLC-OFET, displays fast response (<1  ms) and operates at low voltages (<1  V). The results presented are relevant for low-cost printed polymer electronics.

  • 120.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Jakobsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Crispin, Annica
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Grim, P.C.M.
    KUL, Belgien.
    Andersson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Volodin, A.
    KUL, Belgien.
    van Haesendonch, C.
    KUL, Belgien.
    van der Auweraer, M.
    KUL, Belgien.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    The origin of the high conductivity of poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT-PSS) plastic electrodes2006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, no 18, p. 4354-4360Article in journal (Refereed)
    Abstract [en]

    The development of printed and flexible (opto)electronics requires specific materials for the device's electrodes. Those materials must satisfy a combination of properties. They must be electrically conducting, transparent, printable, and flexible. The conducting polymer poly(3,4-ethylenedioxythiophene) - poly-(styrenesulfonate) (PEDOT-PSS) is known as a promising candidate. Its conductivity can be increased by 3 orders of magnitude by the secondary dopant diethylene glycol (DEG). This "secondary doping" phenomenon is clarified in a combined photoelectron spectroscopy and scanning probe microscopy investigation. PEDOT-PSS appears to form a three-dimensional conducting network explaining the improvement of its electrical property upon addition of DEG. Polymer light emitting diodes are successfully fabricated using the transparent plastic PEDOT-PSS electrodes instead of the traditionally used indium tin oxide. © 2006 American Chemical Society.

  • 121.
    Jakobsson, Fredrik L. E.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lindell, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Kanciurzewska, Anna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. 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.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Towards all-plastic flexible light emitting diodes2006In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 433, no 1-3, p. 110-114Article in journal (Refereed)
    Abstract [en]

    All-plastic light emitting diodes require the design and fabrication of low work function plastic electrodes. Here, we show that the work function of poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT-PSS) can be decreased from 4.8 eV to 3.9 eV by surface reaction with the strong electron-donor tetrakis(dimethylamino)ethylene (TDAE). The surface modification was characterized by photoelectron spectroscopy and optical spectroscopy. The low work function plastic electrode was used in a first prototype for all-plastic light emitting diodes.

  • 122.
    Crispin, Annica
    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.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Berggren, Magnus
    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.
    Transition between energy level alignment regimes at a low band gap polymer-electrode interfaces2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, no 21Article in journal (Refereed)
    Abstract [en]

    The energy level alignment at interfaces between a low band gap conjugated polymer and various electrodes is investigated using ultraviolet photoemission spectroscopy. When the electrode work function is lower (higher) than the negative (positive) polaronic level of the polymer, the Fermi level is pinned to the negative (positive) polaronic level. These Fermi level pinning regimes suggest a spontaneous electron transfer from or towards the electrode resulting in an interfacial dipole of different orientation. On the contrary, when the substrate work function is intermediate, there is no charge transfer and the energy level alignment across the interface follows the Schottky-Mott limit. © 2006 American Institute of Physics.

  • 123.
    Lindell, Linda
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Burquel, A.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, 5-7000 Mons, Belgium.
    Jakobsson, Fredrik
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lemaur, V.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, 5-7000 Mons, Belgium.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, 5-7000 Mons, Belgium.
    Cornil, J.
    Service de Chimie des Matériaux Nouveaux, Université de Mons-Hainaut, Place du Parc 20, 5-7000 Mons, Belgium.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Transparent, plastic, low-work-function poly(3,4-ethylenedioxythiophene) electrodes2006In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, no 18, p. 4246-4252Article in journal (Refereed)
    Abstract [en]

    Novel applications for flexible electronics, e.g., displays and solar cells, require fully flexible, transparent, stable, and low-work-function electrodes that can be manufactured via a low-cost process. Here, we demonstrate that surface chemistry constitutes a route to producing transparent low-work-function plastic electrodes. The work function of the conducting polymer poly(3,4-ethylenedioxythiophene)-tosylate, or PEDOT-Tos, is decreased by submonolayer surface redox reaction with a strong electron donor, tetrakis-(dimethylamino)ethylene (TDAE), allowing it to reach a work function of 3.8 eV. The interface formed between TDAE and PEDOT is investigated in a joint experimental and theoretical study using photoelectron spectroscopy and quantum chemical calculations. © 2006 American Chemical Society.

  • 124.
    Gadisa, Abay
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Admassie, Shimelis
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindell, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Department of Organic Chemistry and Polymer Technology, Chalmers University of Technology, Göteborg, Sweden.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Transparent polymer cathode for organic photovoltaic devices2006In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 156, no 16-17, p. 1102-1107Article in journal (Refereed)
    Abstract [en]

    We demonstrate a prototype solar cell with a transparent polymer cathode, and indium-tin-oxide (ITO)/poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) (PEDOT:PSS) anode. As an active layer, thin film of a bulk heterojunction of polyfluorene copolymer poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2thienyl-2′,1′3′-benzothiadiazole)] (APFO-3) and an electron acceptor molecule [6] and [6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:4 wt.) was sandwiched between the two transparent polymer electrodes. The cathode is another form of PEDOT formed by vapor phase polymerised PEDOT (VPP PEDOT) of conductivity 102–103 S/cm. The cathode is supported on an elastomeric substrate, and forms a conformal contact to the APFO-3/PCBM blend. Transparent solar cells are useful for building multilayer and tandem solar cells.

  • 125.
    Lindell, Linda
    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.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Lazzaroni, R
    Berggren, Magnus
    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.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Characterization of the interface dipole at the paraphenylenediamine-nickel interface: A joint theoretical and experimental study2005In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 122, no 8, p. 84712-Article in journal (Refereed)
    Abstract [en]

    In organic-based (opto)electronic devices, charge injection into conjugated materials is governed to a large extent by the metal-organic interface dipole. Controlling the injection of charges requires a better understanding of the fundamental origin of the interface dipole. In this context, photoelectron spectroscopies and density functional theory calculations are used to investigate the interaction between para-phenylenediamine (PPDA), an electron donor, and a polycrystalline nickel surface. The interface dipole formed upon chemisorption of one PPDA monolayer strongly modifies the work function of the nickel surface from 5.10 to 3.55 eV. The work function decrease of 1.55 eV is explained by the electron-donor character of PPDA and the modification of the electronic density at the metal surface. PPDA monolayers are composed of tilted molecules interacting via the nitrogen lone-pair and PPDA molecules chemisorbed parallel to the surface via their π-electron density. Annealing the monolayer leads to dehydrogenation of PPDA activated by the nickel surface, as found for other amines.

  • 126.
    Chen, Miaoxiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Perzon, Erik
    Department of Materials and Surface Chemistry, Polymer Technology, Chalmers University of Technology, Göteborg, Sweden .
    Andersson, Mats R
    Department of Materials and Surface Chemistry, Polymer Technology, Chalmers University of Technology, Göteborg, Sweden .
    Pullerits, Tönu
    Department of Chemical Physics, Lund University, Lund, Sweden .
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    High carrier mobility in low band gap polymer-based field-effect transistors2005In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 87, no 25, p. 252105-1-252105-3Article in journal (Refereed)
    Abstract [en]

    A conjugated polymer with a low band gap of 1.21 eV, i.e., absorbing infrared light, is demonstrated as active material in field-effect transistors (FETs). The material consists of alternating fluorene units and low band gap segments with electron donor-acceptor-donor units composed of two electron-donating thiophene rings attached on both sides of a thiadiazolo-quinoxaline electron-acceptor group. The polymer is solution-processable and air-stable; the resulting FETs exhibit typical p-channel characteristics and field-effect mobility of 0.03 cm2 V−1 s−1.

  • 127.
    Lindell, Linda
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Jakobsson, Fredrik
    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.
    Andersson, Peter
    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.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Cornil, Jerome
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Towards Transparent Inorganic and Plastic Low-Workfunction Electrodes2005In: MRS Fall Meeting,2005, 2005Conference paper (Refereed)
  • 128.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Cornil, J.
    Université de Mons-Hainaut.
    Friedlein, Rainer
    Linköping University, Department of Physics, Chemistry and Biology.
    Okudaira, K. K.
    Chiba University.
    Lemaur, V
    Université de Mons-Hainaut.
    Crispin, Annica
    Linköping University, Department of Physics, Chemistry and Biology.
    Kestemont, G.
    Université Libre de Bruxelles.
    Lehmann, M.
    Université Libre de Bruxelles.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lazzaroni, R.
    Université de Mons-Hainaut.
    Geerts, Y
    Université Libre de Bruxelles.
    Wendin, G.
    Chalmers University of Technology.
    Ueno, N.
    Chiba University.
    Brédas, J.-L.
    Université de Mons-Hainaut.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology.
    Electronic delocalization in discotic liquid crystals: A joint experimental and theoretical study2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 38, p. 11889-11899Article in journal (Refereed)
    Abstract [en]

    Discotic liquid crystals emerge as very attractive materials for organic-based (opto)electronics as they allow efficient charge and energy transport along self-organized molecular columns. Here, angle-resolved photoelectron spectroscopy (ARUPS) is used to investigate the electronic structure and supramolecular organization of the discotic molecule, hexakis(hexylthio)diquinoxalino[2,3-a:2′,3′-c]phenazine, deposited on graphite. The ARUPS data reveal significant changes in the electronic properties when going from disordered to columnar phases, the main feature being a decrease in ionization potential by 1.8 eV following the appearance of new electronic states at low binding energy. This evolution is rationalized by quantum-chemical calculations performed on model stacks containing from two to six molecules, which illustrate the formation of a quasi-band structure with Bloch-like orbitals delocalized over several molecules in the column. The ARUPS data also point to an energy dispersion of the upper π-bands in the columns by some 1.1 eV, therefore highlighting the strongly delocalized nature of the π-electrons along the discotic stacks.

  • 129.
    Karazazi, Y.
    et al.
    Université de Mons-Hainaut.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Kwon, O.
    Université de Mons-Hainaut.
    Bredas, J. L.
    Université de Mons-Hainaut.
    Cornil, J.
    Université de Mons-Hainaut.
    Influence of contact geometry and molecular derivatization on the interfacial interactions between gold and conjugated wires2004In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 387, no 4-6, p. 502-508Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayers made of thiolated conjugated wires attached on gold surfaces currently attract a considerable interest in the field of nanoelectronics. The interactions taking place at the metal/molecule interface govern the electronic structure of the complex, and hence the barriers for charge injection from the electrodes to the molecules. Considering benzenethiol as a prototype molecule, we investigate here the way the electronic structure is affected by the nature of the anchoring site of the sulfur atom on the gold surface and by the relative orientation of the molecule with respect to the surface. We also assess whether the changes in the molecular electronic properties upon substitution are similar for the isolated molecule and for the molecule attached on the gold surface. Our results provide strong evidences that, in order to introduce functionalities and/or improve charge injection in molecular devices, the electronic properties of conjugated molecular wires can be tailored by derivatization independently of the metal electrodes. copy,

  • 130.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Interface dipole at organic/metal interfaces and organic solar cells2004In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 83, no 2-3, p. 147-168Article in journal (Refereed)
    Abstract [en]

    In organic-based solar cells, the interface dipole present at the organic/metal interface participates to the collection and injection of charges between the electrode and the active organic material. The origins of the interface dipole is illustrated for a model system of the organic/metal interface composed of the electron-donor molecule p-phenylenediamine (PPDA) interacting with a nickel surface. The interface dipole created at the PPDA/Ni interface is characterized in a joint experimental and theoretical study using photoelectron spectroscopy and density functional theory calculations. The formation of strong interface dipoles upon chemisorption of a PPDA mono-layer is accompanied by a significant decrease (1.5eV) of the metal work function reaching 3.6eV.

  • 131.
    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.

  • 132.
    Friedlein, Rainer
    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.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Molecular parameters controlling the energy storage capability of lithium polyaromatic hydrocarbon intercalation compounds2004In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 129, no 1, p. 29-33Article in journal (Refereed)
    Abstract [en]

    One route for improving the performance of Li-based batteries is to optimize the carbon-based electrode. In order to find the best carbon-based materials, the specific roles of the molecular and solid-state contributions have to be understood. Here, the molecular contributions are analyzed. A semi-quantitative method is proposed to compare the charge storage capability of polyaromatic hydrocarbon molecules (PAHs). For planar PAHs, the ability to store electrical energy is found to be to a large extend determined by a single parameter, that is the electronic hardness (half the electronic gap) Multiplied the number of carbon atom in the molecule. A compilation of results for oligophenyls, oligoacenes and medium-size planar systems suggests trends in the dependence of the energy storage capability on the size and shape of the molecules. (C) 2003 Elsevier B.V. All rights reserved.

  • 133.
    Friedlein, Rainer
    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.
    Osikowicz, Wojciech
    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 .
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Simpson, CD
    Watson, MD
    von Kieseritzky, F
    Samori, P
    Jonsson, SKM
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Jackel, F
    Rabe, JP
    Hellberg, J
    Mullen, K
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Surface-induced vertical alignment of self-assembled supramolecular columns of large polycyclic aromatic hydrocarbons and porphyrins2004In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 147, no 01-Mar, p. 79-83Article in journal (Refereed)
    Abstract [en]

    Ordered films of polycyclic aromatic hydrocarbons (PAHs) and porphyrins with functional (e.g. thiophene) side-groups are good candidates for (opto-)electronic applications where fast charge separation and transport are required. Such highly ordered thin films of PAHs, including discotic hexa-peri-hexabenzocoronene (HBC) and C-132-C-16,C-4, as well as brominated functionalized porphyrin molecules have been grown from solutions on semi-metallic molybdenum disulfide substrates and characterized by angle-resolved valence band photoelectron spectroscopy. A vertical growth of self-assembled supramolecular columns perpendicular to the basal plane of the substrate along with their lateral ordering on the surface has been achieved. Annealing made it possible to increase the structural order in the HBC columns, with molecules positioned at a regular offset from the columnar axis. This permitted the formation of extended pi-electronic states with a bandwidth of at least 0.1-0.2 eV at room temperature. (C) 2004 Elsevier B.V. All rights reserved.

  • 134.
    Friedlein, Rainer
    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.
    Suess, C.
    Pickholz, M.
    Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    The role of intermolecular polarization for the stability of lithium intercalation compounds of a- and ß-perylene2004In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 5, p. 2239-2245Article in journal (Refereed)
    Abstract [en]

    The charge transfer in Li-intercalation compounds of the polyaromatic hydrocarbon perylene was examined. It was found that the valence and core-level photoelectron spectroscopies characterized the bonding configuration of the alkali metal atoms. The effect of intermolecular polarization on the ionization potential of Li atoms was compensated by a screening of the Madelung energy. The data collected illustrated that the large charge transfer in the a-perylene was due to the lower ionization potential of lithium atoms.

  • 135.
    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.

  • 136.
    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.

  • 137.
    Crispin, Xavier
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Marciniak, S.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Osikowicz, Wojciech
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Zotti, G.
    Instituto Consiglio Nazionale delle Ricerche per l' Energetica e le Interfasi, Padova, Italy.
    Denier Van Der Gon, A. W.
    Faculty of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands.
    Louwet, F.
    Chemistry Department, R&D Materials Research, Agfa Gevaert N.V., Mortsel, Belgium.
    Fahlman, Mats
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Groenendaal, L.
    Chemistry Department, R&D Materials Research, Agfa Gevaert N.V., Mortsel, Belgium.
    De Schryver, F.
    Afdeling Fotochemie en Spectroscopie, Katholieke Universiteit Leuven, Heverlee, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Conductivity, Morphology, Interfacial Chemistry, and Stability of Poly(3,4- ethylene dioxythiophene)–Poly(styrene sulfonate): A Photoelectron Spectroscopy Study2003In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 41, no 21, p. 2561-2583Article, review/survey (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDT/PSS), one of the most common electrically conducting organic polymers. A correlation has been established between the composition, morphology, and polymerization mechanism, on the one hand, and the electric conductivity of PEDT/PSS, on the other hand. XPS has been used to identify interfacial reactions occurring at the polymer-on-ITO and polymer-on-glass interfaces, as well as chemical changes within the polymer blend induced by electrical stress and exposure to ultraviolet light.

  • 138.
    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.

  • 139.
    Friedlein, Rainer
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Sorensen, S.L.
    Sörensen, S.L., Department of Synchrotron Radiation Research, Institute of Physics, Lund University, S-221 00 Lund, Sweden.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Rosenqvist, L.
    Department of Synchrotron Radiation Research, Institute of Physics, Lund University, S-221 00 Lund, Sweden.
    Crispin, Annica
    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.
    de Jong, Michel P
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Murphy, C.
    CDT Ltd., Cambridge CB3 0KJ, United Kingdom.
    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 .
    Electronic structure of conjugated polymers and interfaces in polymer-based electronics2003Conference paper (Refereed)
    Abstract [en]

    The electronic structure of conjugated polymers and interfaces in polymer-based electronics were analyzed. Fine structure were observed in the region of the first resonance with pi-final state symmetry, between 284.1 eV and 285.8 eV. The electronic transitions from the non-dispersed C(1s) level to specific parts of the unoccupied band structure were generated. It was found that for a dispersing valence band, in the presence of a core-hole, a given photon energy corresponded to an excitation into a state with a distinct wave vectors.

  • 140.
    Friedlein, Rainer
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Simpson, C. D.
    Max Planck Institute for Polymer Research, Germany.
    Watson, M. D.
    Max Planck Institute for Polymer Research, Germany.
    Jackel, F.
    Department of Physics, Humboldt University Berlin, Berlin, Germany.
    Osikowicz, Wojciech
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Marciniak, S.
    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.
    Samori, P.
    Department of Physics, Humboldt University Berlin, Berlin, Germany.
    Jönsson, Stina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Müllen, K.
    Max Planck Institute for Polymer Research, Germany.
    Rabe, J. P.
    Department of Physics, Humboldt University Berlin, Berlin, Germany.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Electronic structure of highly ordered films of self-assembled graphitic nanocolumns2003In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 19, p. 195414-Article in journal (Refereed)
    Abstract [en]

    Highly ordered, several nanometers thick films of alkylated large planar, polycyclic aromatic hydrocarbon (PAH) molecules have been grown on semi-metallic molybdenum disulfide substrates. The films are characterized by a two-dimensional lateral arrangement of columns standing at the surface on a macroscopic scale. The self-assembly of such insulated columns of face-to-face disks with surface-induced vertical alignment has been achieved directly from solution processing. Angle-resolved photoelectron spectra revealed a highly anisotropic quasi-one-dimensional electronic structure with an extended π-electronic wave function. An intermolecular dispersion of the highest occupied band of at least 0.15 eV along the stacking direction has been measured. A partial breakdown of the concept of quasimomentum due to the finite size of the nano-objects perpendicular to the stacks is observed.

  • 141.
    Fahlman, Mats
    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.
    Smallfield, JAO
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Lazzaroni, R
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Bredas, JL
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Li, S
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Wei, Y
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Epstein, AJ
    Linkoping Univ, Dept Sci & Technol, SE-60174 Norrkoping, Sweden Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Univ Mons, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA.
    Iron-polyaniline interfaces: Implications for corrosion protection2003In: American Chemical Society Symposium Series (ACS), ISSN 0097-6156, E-ISSN 1947-5918, Vol. 843, p. 76-89Article in journal (Refereed)
    Abstract [en]

    The early stages of interface formation between iron and a three-ring model molecule (trimer) of emeraldine base form of polyaniline (EB) were investigated using theoretical (DFT) and experimental (XPS) methods: Iron atoms were sputter-deposited in ultra high vacuum onto thin oligomer films, with X-ray photoelectron spectroscopy (XPS) core level spectra taken after each deposition. Similar studies were carried out for Fe sputter-deposited on EB polymer films as well. Based on the chemical shifts of the core level peaks and the theoretical results, iron was determined to donate charge (e(-)) into the trimer and EB films. The reverse case where thin films of trimer and EB were deposited on iron also was studied. The C(1s) core level shake up spectra show that the pi-electronic structure is modified for trimer and EB coatings on iron as compared to coatings on gold. (C) 2003 American Chemical Society.

  • 142.
    Jönsson, Stina
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Birgerson, J.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Osikowicz, Wojciech
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Denier van der Gon, A.W.
    Denier van der Gon, A.W., Faculty of Applied Physics, Eindhoven University of Technology, Eindhoven, Netherlands.
    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.
    The effects of solvents on the morphology and sheet resistance in poly(3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT–PSS) films2003In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 139, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Films of poly(3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT–PSS), prepared by coating the aqueous PEDOT–PSS dispersion and by coating a mixture of the PEDOT–PSS dispersion and different solvents, have been studied using four-point probe conductivity measurements, atomic force microscopy and photoelectron spectroscopy. The electrical conductivity of thin films of the second type (further on called PEDOT–PSS–solvents) was increased by a factor of about 600 as compared to films of the first type (further on called PEDOT–PSS–pristine). Morphological and physical changes occur in the polymer film due to the presence of the solvent mixture, the most striking being that the ratio of PEDOT-to-PSS in the surface region of the films is increased by a factor of ∼2–3. This increase of PEDOT at the surface indicates that the thickness of the insulating PSS ‘shell’ that surrounds the conducting PEDOT–PSS grains is reduced. The (partial) reduction of the excess PSS layer that surrounds the conducting PEDOT–PSS grains is proposed to lead to an increased and improved connectivity between such grains in the film and hence a higher conductivity. When PEDOT–PSS–solvents receives a post-coating heat treatment, the increased PEDOT-to-PSS ratio at the surface is maintained or even slightly improved, as is the increase in electrical conductivity, even though spectroscopy show that the solvent molecules are removed. This suggests that screening or doping by the solvents throughout the film are not likely to be the key mechanisms for the improved conductivity and supports our proposed mechanism of improved conductivity through improved connectivity between the conducting grains.

  • 143.
    de Jong, Michel P
    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.
    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 .
    Groenendaal, L.
    Agfa-Gevaert N.V., R and D Materials - Chemistry Dept., Septestraat 27, B-2640 Mortsel, Belgium.
    The electronic structure of n- and p-doped phenyl-capped 3,4-ethylenedioxythiophene trimer2003In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 118, no 14, p. 6495-6502Article in journal (Refereed)
    Abstract [en]

    A study was conducted on the effects of chemical doping on the chemical and electronic structure of condensed molecular solid films of the ethylenedioxythiophene (EDOT) trimer using ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). Phenyl-capped EDOT oligomers were potential candidates for molecular electronics applications and serve as model molecules for PEDOT. By combining UPS, XPS, and NEXAFS, a clear picture of the doping induced changes in the electronic structure of phenyl-capped EDOT-trimer was obtained.

  • 144.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Geskin, V.
    Crispin, Annica
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Cornil, J.
    Lazzaroni, R.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Bredas, J.-L.
    Characterization of the interface dipole at organic/metal interfaces2002In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 124, no 27, p. 8131-8141Article in journal (Refereed)
    Abstract [en]

    In organics-based (opto)electronic devices, the interface dipoles formed at the organic/metal interfaces play a key role in determining the barrier for charge (hole or electron) injection between the metal electrodes and the active organic layers. The origin of this dipole is rationalized here from the results of a joint experimental and theoretical study based on the interaction between acrylonitrile, a p-conjugated molecule, and transition metal surfaces (Cu, Ni, and Fe). The adsorption of acrylonitrile on these surfaces is investigated experimentally by photoelectron spectroscopies, while quantum mechanical methods based on density functional theory are used to study the systems theoretically. It appears that the interface dipole formed at an organic/metal interface can be divided into two contributions: (i) the first corresponds to the "chemical" dipole induced by a partial charge transfer between the organic layers and the metal upon chemisorption of the organic molecules on the metal surface, and (ii) the second relates to the change in metal surface dipole because of the modification of the metal electron density tail that is induced by the presence of the adsorbed organic molecules. Our analysis shows that the charge injection barrier in devices can be tuned by modulating various parameters: the chemical potential of the bare metal (given by its work function), the metal surface dipole, and the ionization potential and electron affinity of the organic layer.

  • 145.
    Friedlein, Rainer
    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.
    Pickholz, M.
    Keil, M.
    Stafström, Sven
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    High intercalation levels in lithium perylene stoichiometric compounds2002In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 354, no 5-6, p. 389-394Article in journal (Refereed)
    Abstract [en]

    Both amorphous and polycrystalline films of the aromatic hydrocarbon perylene are found to accept as high as one lithium per 3.3±0.1 carbon atoms. Phases composed of stoichiometric compounds with two, four and six lithium atoms per molecule are observed. The intercalation involves a substantial charge transfer from the lithium atoms to the molecules. Moreover, a high binding energy of the dopant-induced valence band electronic states is observed by photoelectron spectroscopy. Those observations suggest a high energy storage capacity for small- and medium-size aromatic hydrocarbons and their potential use in batteries. © 2002 Elsevier Science B.V. All rights reserved.

  • 146.
    Crispin, Annica
    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.
    Fahlman, Mats
    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., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Cornil, J.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Johansson, N.
    Bauer, J.
    Covion Organic Semiconductors GmbH, Industrial Park Hoechst, D-65926 Frankfurt, Germany.
    Weissortel, F.
    Weissörtel, F., Electrochemistry and Optoelectronic Materials, FB 6, University Duisburg, D-47048 Duisburg, Germany.
    Salbeck, J.
    Electrochemistry and Optoelectronic Materials, FB 6, University Duisburg, D-47048 Duisburg, Germany, Macromolecular Chemistry and Molecular Materials, FB 18, University Kassel, D-34132 Kassel, Germany.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, Tucson, AZ 85721-0041, United States.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Influence of dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors2002In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 116, no 18, p. 8159-8167Article in journal (Refereed)
    Abstract [en]

    The influence of the dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors was studied by means of photoelectron spectroscopy. With lithium atoms as dopants, two charges were stored on the same spiro branch in the form of bipolarons, for spiro-quarterphenyl and spiro-sexiphenyl. For doping with the sodium atoms, the size of the counter ions made it less energetically desirable to store two charges onto a single branch, and the charged species were polarons independent of the level of doping which was confirmed by optical absorption data.

  • 147.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Crispin, Annica
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Geskin, V.M.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, Tucson, AZ 85721-0041, United States.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, 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 .
    Understanding the initial stages of polymer grafting on metals: A photoelectron spectroscopy study of acrylonitrile adsorption on transition metal surfaces2001In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 121, no 1-3, p. 57-74Article in journal (Refereed)
    Abstract [en]

    X-ray and UV photoelectron spectroscopies show that acrylonitrile is chemisorbed on iron, nickel and copper polycrystalline surfaces via the carbon and nitrogen atoms. Depending on the conditions used, different adsorption geometries are found. The molecules can either be adsorbed flat on the surface and chemically bound by a (2pp)-(3d/4s) overlap via both the C=C double bond and the C=N nitrile group or they can be adsorbed perpendicular to the surface via a covalent interaction between the nitrogen lone pair and the 3d-4s levels of the metals. Analysis of the XPS data obtained on molecular mono-layers chemisorbed on metal surfaces emphasizes the importance of initial-state effects (charge transfer upon chemisorption, contribution of the metal surface dipole) and final-state effects (metal screening and polarization effect within the mono-layer). The correlation between the XPS and UPS data illustrates the importance of the metal surface dipole in understanding the workfunction changes upon molecular adsorption on metal surfaces. © 2001 Elsevier Science B.V. All rights reserved.

  • 148.
    Bureau, C.
    et al.
    CEA Saclay, France.
    Kranias, S.
    CEA Saclay, France.
    Crispin, Xavier
    University of Mons, Belgium.
    Bredas, J. L.
    University of Mons, Belgium.
    DPT modeling of Stark-Tuning effect: CO on polarized Pd(100) as a probe for double-layer electrostatic effects in electrochemistry2000In: QUANTUM SYSTEMS IN CHEMISTRY AND PHYSICS, VOL 2: AVANCED PROBLEMS AND COMPLEX SYSTEMS / [ed] HernandezLaguna, A; Maruani, J; McWeeny, R; Wilson, S, Springer, 2000, Vol. 3, p. 169-192Conference paper (Refereed)
    Abstract [en]

    The lifetime of chemisorbed radical anions produced in the electroreduction of vinylic molecules is thought to play a decisive part in the mechanism accounting for the production of grafted films in electropolymerization reactions. With the ultimate purpose of evaluating these lifetimes, we propose a one-dimensional model taking into account the interface bond, the anion/metallic surface image charge potential, and the anion/polarized-surface electrostatic repulsion. Orders of magnitude are known for the parameters entering in these terms, except for the latter. In the present work, this term is described using the Gouy-Chapmann model for the electrochemical double layer. Comparing our theoretical DFT predictions on Stark-Tuning effect of CO on Pd(100) with experiment, we can discuss on the legitimacy of a phenomenological linear relationship between the (microscopic) surface electric field and the (macroscopic) electrode potential. The slope of this relationship, termed the electric field rate, in (V.cm(-1)).V-1, turns out to be numerically equivalent to the characteristic length of the double layer, whatever the underlying model. Our calculated rates, carried out within the Gouy-Chapmann approximation, are in acceptable agreement with previous experimental estimates. First insights into our electropolymerization reactions suggest that the presumed intermediate chemisorbed radical-anions may have a borderline stability, i.e. a largely non negligible lifetime on the surface.

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