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  • 1.
    Alfredsson, Ylfi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kjeldgaard, Lisbeth
    O´Shea, J. N.
    Theobald, J.
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Phase and molecular orientation in H2Pc on conducting glass: characterization of two deposition methods2005In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 493, no 1-2, p. 13-19Article in journal (Refereed)
    Abstract [en]

    In this study, metal-free phthalocyanine has been deposited on a conducting glass surface by two methods: by spreading the molecular powder directly on the substrate in air and by vapor sublimation under ultra-high vacuum conditions (evaporation). The films have been characterized by means of core level X-ray Photoemission Spectroscopy, X-ray Absorption Spectroscopy (XAS) and Ultra Violet and Visible absorption spectroscopy (UV-Vis). Our results show that the two deposition methods produce molecular overlayers in different polymorphic phases; the UV-Vis measurements indicate that the film obtained by powder deposition is of x-phase type whereas sublimation leads to an α-polymorph structure. The XAS results show that in the powder deposited film the molecules are mainly oriented parallel to the surface. This is opposite to the case of the vapor deposited film, where the molecules mainly are oriented orthogonal to the surface.

  • 2.
    Alfredsson, Ylvi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Brena, Barbara
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kjeldgaard, Lisbeth
    Nyberg, Mats
    Luo, Yi
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Electronic structure of a vapor-deposited metal-free phthalocyanine thin film2005In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 122, no 21, p. 214723-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a vapor-sublimated thin film of metal-free phthalocyanine(H2Pc) is studied experimentally and theoretically. An atom-specific picture of the occupied and unoccupied electronic states is obtained using x-ray-absorption spectroscopy (XAS), core- and valence-level x-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) calculations. The DFT calculations allow for an identification of the contributions from individual nitrogen atoms to the experimental N1sXAS and valence XPS spectra. This comprehensive study of metal-free phthalocyanine is relevant for the application of such molecules in molecular electronics and provides a solid foundation for identifying modifications in the electronic structure induced by various substituent groups.

  • 3.
    Alfredsson, Ylvi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kjeldgaard, Lisbeth
    O'Shea, James
    Theobald, J
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Phase and molecular orientation in metal-free phthalocyanine films on conducting glass: Characterization of two deposition methods2005In: Thin Solid Films, Vol. 493, no 1-2, p. 13-19Article in journal (Refereed)
  • 4.
    Andersson, Anna M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Henningsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemically lithiated graphite characterised by photoelectron spectroscopy2003In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 119-121, p. 522-527Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) has been used to study the depth profile of the solid–electrolyte interphase (SEI) formed on a graphite powder electrode in a Li-ion battery. The morphology of the SEI-layer, formed in a 1 M LiBF4 EC/DMC 2:1 solution, consists of a 900 Å porous layer of polymers (polyethylene oxide) and a 15–20 Å thin layer of Li2CO3 and LiBF4 reduction–decomposition products. Embedded LiF crystals as large as 0.2 μm were found in the polymer matrix. LiOH and Li2O are not major components on the surface but rather found as a consequence of sputter-related reactions. Monochromatised Al Kα XPS-analysis based on the calibration of Ar+ ion sputtering of model compounds combined with a depth profile analysis based on energy tuning of synchrotron XPS can describe the highly complex composition and morphology of the SEI-layer.

  • 5.
    Augustsson, A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics II. Physics I.
    Henningsson, A
    Butorin, S
    Department of Physics and Materials Science, Physics II. Physics I.
    Siegbahn, H
    Department of Physics and Materials Science, Physics II. Physics I.
    Nordgren, J
    Department of Physics and Materials Science, Physics II. Physics I.
    Guo, J H
    Lithium ion insertion in nanoporous anatase Ti02 studied with RIXS2003In: Journal of Chemical Physics, Vol. 119, no 7, p. 3983-3987Article in journal (Refereed)
  • 6. Brena, Barbara
    et al.
    Luo, Yi
    Nyberg, Mats
    Carniato, Stephane
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Alfredsson, Ylvi
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Equivalent core-hole time-dependent density functional theory calculations of carbon 1s shake-up states of phthalocyanine2004In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 70, no 19, p. 195214-Article in journal (Refereed)
    Abstract [en]

    The shake-up transition energies of the carbon 1s photoelectron spectrum of metal-free phthalocyanine (H2Pc) have been calculated by means of time-dependent density functional theory, for which an equivalent core approximation is adopted. Model calculations for the C 1s shake-up states of benzene are in excellent agreement with the latest experimental results. The complex C 1s shake-up structures associated with the aromatic and pyrrole carbons in the phthalocyanine are computed, as well as their ionization potentials. They allow us to determine the origin of the anomalous intensity ratio between the pyrrole and benzene carbons in a high resolution C 1s photoelectron spectrum measured for a H2Pc film, as due to a benzene-related shake-up contribution, hidden under the pyrrole main intensity feature.

  • 7. Edwards, Marten O. M.
    et al.
    Karlsson, Patrik G.
    Eriksson, Susanna Kaufmann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kahk, Juhan M.
    Villar-Garcia, Ignacio J.
    Payne, David J.
    Ahlund, John
    Increased photoelectron transmission in High-pressure photoelectron spectrometers using "swift acceleration"2015In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 785, p. 191-196Article in journal (Refereed)
    Abstract [en]

    A new operation mode of a HPXPS (high-pressure X-ray photoelectron spectroscopy) analyzer is evaluated on a HPXPS system fitted with an Al K alpha X-ray source. A variety of metal foil samples (gold, silver and copper) were measured in different sample gas environments (N-2 and H2O), and a front aperture diameter of 0.8 mm. The new design concept is based upon "swiftly" accelerating the photoelectrons to kinetic energies of several keV after they pass the analyzer front aperture. Compared to the standard mode, in which the front section between the two first apertures is field-free, this gives a wider angular collection and a lower tendency for electron losses in collisions with gas molecules within the analyzer. With the swift-acceleration mode we attain, depending on the experimental conditions, up to about 3 times higher peak intensities in vacuum and about 10 to 20 times higher peak intensities in the 6-9 mbar regime, depending on kinetic energy. These experimental findings agree well with simulated transmission functions for the analyzer. The new mode of operation enables faster data acquisition than the standard mode of operation, particularly valuable in a home laboratory environment. Further demonstrations of performance are highlighted by measurements of the valence band structure in dye sensitized solar cell photoelectrodes under a 2 mbar H2O atmosphere, a molecularly modified surface of interest in photoelectrochemical devices.

  • 8. Eriksson, Susanna K.
    et al.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Axnanda, Stephanus
    Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Adv Light Source, One Synchrotron Rd, Berkeley, CA 94720 USA..
    Crumlin, Ethan
    Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Adv Light Source, One Synchrotron Rd, Berkeley, CA 94720 USA..
    Wilks, Regan
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Renewable Energy, Hahn Meitner Pl 1, D-14109 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie GmbH, Energy Mat In Situ Lab EMIL, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Eriksson, Anna I. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Liu, Zhi
    Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Adv Light Source, One Synchrotron Rd, Berkeley, CA 94720 USA..
    Ahlund, John
    VG Scienta AB, Box 15120, S-75015 Uppsala, Sweden..
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Starr, David E.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Hahn Meitner Pl 1, D-14109 Berlin, Germany..
    Baer, Marcus
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Renewable Energy, Hahn Meitner Pl 1, D-14109 Berlin, Germany.;Helmholtz Zentrum Berlin Mat & Energie GmbH, Energy Mat In Situ Lab EMIL, Albert Einstein Str 15, D-12489 Berlin, Germany.;Brandenburg Tech Univ Cottbus Senftenberg, Inst Chem & Phys, Pl Deutsch Einheit 1, D-03046 Cottbus, Germany..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    In-Situ Probing of H2O Effects on a Ru-Complex Adsorbed on TiO2 Using Ambient Pressure Photoelectron Spectroscopy2016In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 59, no 5-7, p. 583-590Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized interfaces in photocatalytic and solar cells systems are significantly affected by the choice of electrolyte solvent. In the present work, the interface between the hydrophobic Ru-complex Z907, a commonly used dye in molecular solar cells, and TiO2 was investigated with ambient pressure photoelectron spectroscopy (AP-PES) to study the effect of water atmosphere on the chemical and electronic structure of the dye/TiO2 interface. Both laboratory-based Al K alpha as well as synchrotron-based ambient pressure measurements using hard X-ray (AP-HAXPES) were used. AP-HAXPES data were collected at pressures of up to 25 mbar (i.e., the vapor pressure of water at room temperature) showing the presence of an adsorbed water overlayer on the sample surface. Adopting a quantitative AP-HAXPES analysis methodology indicates a stable stoichiometry in the presence of the water atmosphere. However, solvation effects due to the presence of water were observed both in the valence band region and for the S 1s core level and the results were compared with DFT calculations of the dye-water complex.

  • 9.
    Eriksson, Susanna K
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Kahk, Juhan Matthias
    Villar-Garcia, Ignacio J
    Webb, Matthew J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Yakimova, Rositza
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Edwards, Mårten O M
    Karlsson, Patrik G
    Backlund, Klas
    Ahlund, John
    Payne, David J
    A versatile photoelectron spectrometer for pressures up to 30 mbar2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 7, p. 075119-Article in journal (Refereed)
    Abstract [en]

    High-pressure photoelectron spectroscopy is a rapidly developing technique with applications in a wide range of fields ranging from fundamental surface science and catalysis to energy materials, environmental science, and biology. At present the majority of the high-pressure photoelectron spectrometers are situated at synchrotron end stations, but recently a small number of laboratory-based setups have also emerged. In this paper we discuss the design and performance of a new laboratory based high pressure photoelectron spectrometer equipped with an Al Kα X-ray anode and a hemispherical electron energy analyzer combined with a differentially pumped electrostatic lens. The instrument is demonstrated to be capable of measuring core level spectra at pressures up to 30 mbar. Moreover, valence band spectra of a silver sample as well as a carbon-coated surface (graphene) recorded under a 2 mbar nitrogen atmosphere are presented, demonstrating the versatility of this laboratory-based spectrometer.

  • 10.
    Guo, J H
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Luo, Yi
    Augustsson, A
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Rubensson, J E
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Såthe, C
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Ågren, H
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Nordgren, J
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    X-ray emission spectroscopy of hydrogen bonding and electronic structure of liquid water2005In: Physical Review Letters, Vol. 89, no 13Article in journal (Refereed)
  • 11.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, M
    Magnuson, Martin
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagberg, D
    Sun, L
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Mapping the frontier electronic structures of triphenylamine basedorganic dyes at TiO2 interfaces2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 8, p. 3534-3546Article in journal (Refereed)
    Abstract [en]

    The frontier electronic structures of a series of organic dye molecules containing a triphenylamine moiety, a thiophene moiety and a cyanoacrylic acid moiety have been investigated by photoelectron spectroscopy (PES), X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES) and resonant photoelectron spectroscopy (RPES). The experimental results were compared to electronic structure calculations on the molecules, which are used to confirm and enrich the assignment of the spectra. The approach allows us to experimentally measure and interpret the basic valence energy level structure in the dye, including the highest occupied energy level and how it depends on the interaction between the different units. Based on N 1s X-ray absorption and emission spectra we also obtain insight into the structure of the excited states, the molecular orbital composition and dynamics. Together the results provide an experimentally determined energy level map useful in the design of these types of materials. Included are also results indicating femtosecond charge redistribution at the dye/TiO(2) interface.

  • 12.
    Hedlund, Maria
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik1.
    Johansson, Erik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Effects of water in the Surface Adsorption of Dye molecules at Nanostructured TiO22006In: 16th International Conference on Photochemical Conversion and Storage of Solar Energy (IPS-16), 2006Conference paper (Other scientific)
    Abstract [en]

    The dye-sensitized solar cell is a promising new alternative to conventional solar cells. However these molecular solar cells may suffer from long term stability problems. Some of these problems are believed to be linked to the presence of water. Recently, dyes possessing long hydrophobic chains have been introduced, as an effort to come to terms with problems related to water [1]. In this study the Ru-dyes N3, N719 and 520DN (an analog containing hydrophobic chains) bound to TiO2, have after being exposed to water, been investigated by photoelectron spectroscopy (PES). PES was used to understand on a molecular level, how the introduction of water influences the molecular and electronic structure of these dye sensitized surfaces.

    In general, the surface sensitized with 520DN does not give signs of any major changes after being subjected to water. The investigation therefore found that the hydrophobic chains in the dye surface with 520DN effectively protect the molecular structure of the surface. However the surfaces of N3 and N719 do show large changes after exposing the surface to water. More specifically, it has been found that the outermost molecular orbitals (HOMO), which are vital for the function of the solar cell, are affected by water by shifting towards higher binding energies.

    Also, changes in the thiocyanate group can be found in the N3 and N719 dyes after being exposed to water. Specifically, the sulphur S2p energy levels have a substantially larger amount of a second spin-orbit split peak after being exposed to water. The nitrogen N1s peak relating to the thiocyanate group also changes shape. Moreover, in the case of N719, the counter ion TBA+ is not present on the dye sensitized surface after being subjected to water.

    Finally, the amount of dye on the TiO2 surfaces is also important for the efficiency of the solar cell. It was found that the coverage of N3 and N719 dye decreases when exposed to water, but the coverage of the 520DN dye remains the same.

  • 13.
    Henningsson, A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry. Physics, Department of Physics and Materials Science, Physics I. Department of Physical and Analytical Chemistry, Physical Chemistry.
    Rensmo, H
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Department of Physical and Analytical Chemistry, Physical Chemistry.
    Sandell, A
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Department of Physical and Analytical Chemistry, Physical Chemistry.
    Siegbahn, H
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Department of Physical and Analytical Chemistry, Physical Chemistry.
    Södergren, S
    Lindström, H
    Hagfeld, A
    Physics, Department of Physics and Materials Science, Physics I. Department of Physical and Analytical Chemistry, Physical Chemistry.
    Electronic structure of electrochemically Li-inserted TiO2 studied with synchrotron radiation electron spectroscopies2003In: Journal of Chemical Physics, Vol. 118, no 12, p. 5607-5612Article in journal (Refereed)
  • 14.
    Henningsson, Anders
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Sandell, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Södergren, Sven
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Insertion of H+, Li+, Na+ and K+ into thin films prepared from silicotungstic acid - a photoelectron spectroscopy study2004In: Thin Solid Films, Vol. 461, no 2, p. 237-242Article in journal (Refereed)
  • 15.
    Henningsson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Stashans, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Södergren, Sven
    Lindström, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Vayssieres, L.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Lunell, Sten
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry I. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semi-empirical calculations2004In: Advances in Quantum Chemistry, ISSN 0065-3276, E-ISSN 2162-8815, Vol. 47, p. 23-36Article in journal (Refereed)
  • 16.
    Herstedt, Marie
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Andersson, A.M
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Rensmo, Håkan
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Siegbahn, Hans
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Characterisation of the SEI formed on natural graphite in PC-based electrolytes2004In: Electrochimica Acta, no 49, p. 4939-4947Article in journal (Refereed)
    Abstract [en]

    The origin of the different Li+ intercalation behavior of raw and jet-milled natural graphite has been investigated. Jet-milled graphite is found to cycle reversibly in equal solvent mixture of propylene carbonate (PC) and etylene carbonate (EC), whereas raw graphite does not. Using both Al Ka and synchrotron radiation (SR) Photoelectron Spectroscopy, new insight is obtained inti the formation of the solid electrolyte interphase (SEI) on the two different graphite materials during electrochemical cycling in 1 M LiPF6 in either PC:EC (1:1) or in PC with 5% vinylene carbonate (VC) as additive. Solvent reduction products are found at the surface of both raw and jat-milled graphite cycled in PC:EC (1:1), but differed in composition. The addition of VC reduces primarily the quantities of salt reaction products (LiF and LixPFy compounds) and produces a mainly organic SEI layer. Electron diffraction from the edges for raw and jet-milled graphite particles shows a physical barrier hindering PC co-intercalation and faciltating the formation of a stable SEI layer.

  • 17.
    Herstedt, Marie
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Rensmo, Håkan
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Siegbahn, Hans
    Department of Physics. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Physics, Department of Physics and Materials Science, Physics I. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Electrolyte additives for enhanced thermal stability of the graphite anode interface in a Li-ion battery2004In: Electrochimica Acta, no 49, p. 2351-2359Article in journal (Refereed)
    Abstract [en]

    The influence of electrolyte additives on the thermal stability of graphite anodes in a Li-ion battery has been investigated. The selected additives are: ethyltriacetoxysilane, 1,3 benzoldioxole, tetra (ethylene glycol) dimethylether and vinylene carbonate. These compounds were added in 4% to an electrolyte consisting of 1 M LiBF4 ethylene carbonate (EC/diethyl carbonate (DEC) solvent mixture. Differential scanning calorimetry (DSC) was used to investigated the thermal stability. The electrochemical performance was investigated by galvanostatic cycling and the formed solid electrolyte interphase (SEI) was characterised by photoelectron spectroscopy (PES) using Al Ka and synchrotron radiation /SR). The onset temperature for the thermally activated reactions was found to increas for all electrodes cycled with additives compared to electordes cycled without additives. The onset temperature in creased in the order: no additive < tetra (ethylene glycole) dimethyl ether < 1,3-benzoldioxole < ethyl-triacetoxysilane < vinylene carbonate. Feature in the PES spectra found to be associated with high onset temeratures for thermally activated reactions are: (i) no discernible graphite peak, (ii) small amount of salt species of the type LiF and LixBFyOz and (iii) larger amounts of organic compounds preferably with a high oxygen content.

  • 18.
    Herstedt, Marie
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Stjerndahl, Mårten
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Nytén, Anton
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Gustafsson, Torbjörn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Rensmo, Håkan
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I.
    Siegbahn, Hans
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I.
    Ravet, N
    Armand, M
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. Physics, Department of Physics and Materials Science, Physics I. strukturkemi.
    Surface Chemistry of Carbon-Treated LiFePO4 Particles for Li-Ion Battery Cathodes Studied by PES2003In: Electrochemical and Solid-State Letters, Vol. 6, no 9, p. A202-A206Article in journal (Refereed)
  • 19. Jena, Naresh K.
    et al.
    Josefsson, Ida
    Eriksson, Susanna Kaufmann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, Michael
    Solvent-Dependent Structure of the I-3(-) Ion Derived from Photoelectron Spectroscopy and Ab Initio Molecular Dynamics Simulations2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 10, p. 4049-4055Article in journal (Refereed)
    Abstract [en]

    Ab initio molecular dynamics (MD) simulations of the solvation of LiI3 in four different solvents (water, methanol, ethanol, and acetonitrile) are employed to investigate the molecular and electronic structure of the I-3(-) ion in relation to X-ray photoelectron spectroscopy (XPS). Simulations show that hydrogen-bond rearrangement in the solvation shell is coupled to intramolecular bond-length asymmetry in the I-3(-) ion. By a combination of charge analysis and I 4d core-level XPS measurements, the mechanism of the solvent-induced distortions has been studied, and it has been concluded that charge localization mediates intermolecular interactions and intramolecular distortion. The approach involving a synergistic combination of theory and experiment probes the solvent-dependent structure of the I-3(-) ion, and the geometric structure has been correlated with the electronic structure.

  • 20.
    Johansson, E
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Platzer-Björkman, C
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rensmo, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Sandell, A
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gorgoi, M
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Schäfers, F
    Braun, W
    Eberhardt, W
    HIKE experiments at KMC-1: Studies of Solar Cell Materials2007In: Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m.b.H. (BESSY) Annual Report (2006), no 508-509Article in journal (Refereed)
  • 21.
    Johansson, Erik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Hedlund, Maria
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Electronic and molecular surface structure of Ru(tcterpy)(NCS)3 and Ru(dcbpy)2(NCS)2 adsorbed from solution onto nanostructured TiO2 – A Photoelectron spectroscopy study2005In: Journal of Physical Chemistry B, Vol. 149, no 47, p. 22256-22263Article in journal (Refereed)
  • 22.
    Johansson, Erik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik 1.
    Karlsson, Patrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik1.
    Hedlund, Maria
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik 1.
    Ryan, Declan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik 1.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik 1.
    PHOTOVOLTAIC AND INTERFACIAL PROPERTIES OF HETEROJUNCTIONS COMPRISING DYE-SENSITIZED DENSE TiO2 AND TRIARYLAMINE DERIVATIVES IN SOLID AND LIQUID STATE.1996Conference paper (Other scientific)
    Abstract [en]

    Different triarylamine derivatives have successfully been used as solid hole-conductor materials in dye-sensitized solar cells with efficiencies up to 4% [1-3]. In the present work TiO2/dye/ hole-conductor heterojunctions is assembled to form model systems for solid state DSSC and the interfacial structure at the molecular level. A series of triarylamine molecules is used to investigate the influence of small differences in the hole-conductor material structure on the photovoltaic and molecular surface properties. Both solid state and liquid state junctions with the triarylamine molecules were investigated. In the solid state heterojunctions the hole-conductor molecules were evaporated on the substrate and in the liquid state heterojunctions the hole-conductor molecules were solvated in an organic solvent. The photovoltaic properties of the heterojunction largely depend on the electron transfer rates at the interfaces between the different materials (semiconductor, dye and hole-conductor). Photoelectron Spectroscopy (PES) measurements was used to investigate the molecular and electronic interface structure. In the figure below the valence electronic structure of interfaces with the different hole-conductors are shown.

    From the valence PES the interaction and the energy level matching between the dyes and the hole-conductors is studied. The results show large differences in the energy matching of the different holconducting materials with respect to the dye molecules partly explaining the differences in efficiency. The valence structure also shows that when combining different materials their individual properties adjust slightly to their new environment. From the core level PES we observe differences molecular surface structure. Specifically it was found that the smaller holecondctors are able to penetrate the dye layer and contact the TiO2 surface.

  • 23.
    Johansson, Erik M. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Karlsson, Patrik G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Ryan, Declan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Photovoltaic and Interfacial Properties of Heterojunctions Containing Dye-sensitized Dense TiO2 and Triarylamine derivatives2007In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 19, no 8, p. 2071-2078Article in journal (Refereed)
    Abstract [en]

    A series of solid-state heterojunctions comprising a dense TiO2 film electrode as an electron conductor, a ruthenium polypyridine complex (Ru(dcbpy)2(NCS)2) as a light-absorbing dye, and different triarylamine derivatives as hole conductors were prepared, and their photovoltaic properties as well as the molecular and electronic interfacial structures were investigated. The photovoltaic properties were compared to systems containing the hole conductors dissolved in an organic solvent as well as to a system containing a liquid electrolyte containing the iodide/tri-iodide redox couple. Two of the solid-state heterojunctions showed conversion efficiencies close to those of the system containing the iodide/tri-iodide redox couple, while one system was clearly less efficient. To explain the differences in photovoltaic properties the electronic and molecular interfacial structures of the solid-state heterojunctions were investigated by photoelectron spectroscopy (PES). By valence level PES the electronic energy levels highest in energy for the dye and the hole conductors were mapped, and the differences in energy matching partly explain the trends in photovoltaic properties. Differences in the molecular surface structure of the heterojunctions were also observed from the N Is core level measurements. Specifically it was found that the smaller hole conductor, showing low photocurrent yield, is inserted into the dye layer.

  • 24.
    Johansson, Erik M. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Atomic and Electronic Structures of Interfaces in Dye-Sensitized, Nanostructured Solar Cells2014In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 15, no 6, p. 1006-1017Article, review/survey (Refereed)
    Abstract [en]

    Key processes in nanostructured dye-sensitized solar cells occur at material interfaces containing, for example, oxides, dye molecules, and hole conductors. A detailed understanding of interfacial properties is therefore important for new developments and device optimization. The implementation of X-ray-based spectroscopic methods for atomic-level understanding of such properties is reviewed. Specifically, the use of the chemical and element sensitivity of photoelectron spectroscopy, hard X-ray photoelectron spectroscopy, and resonant photoelectron spectroscopy for investigating interfacial molecular and electronic properties are described; examples include energy matching, binding configurations, and molecular orbital composition. Finally, results from the complete oxide/dye/hole-conductor systems are shown and demonstrate how the assembly itself can affect the molecular and electronic structure of the materials.

  • 25.
    Johansson, Erik M. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Schölin, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Energy level alignment in TiO(2)/dipole-molecule/P3HT interfaces2011In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 515, no 1-3, p. 146-150Article in journal (Refereed)
    Abstract [en]

    Controlling the energy levels at the interface between an inorganic and an organic material is of importance to improve the properties in devices based on such hybrid interfaces, and can be obtained by the incorporation of dipole molecules between the materials. In this report interfaces containing TiO(2), a dipole molecule (benzoic acid or 4-nitrobenzoic acid) and a polymer, poly(3-hexylthiophene) (P3HT) were investigated using high kinetic energy photoelectron spectroscopy. We could successfully measure through all materials in the fully assembled systems, and thereby experimentally quantify the dipole induced change in the energy level alignment of the polymer and the TiO(2).

  • 26.
    Johansson, Erik M.J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Odelius, M.
    Hagberg, Daniel P.
    KTH, Organisk kemi / Organic chemistry.
    Sun, Licheng
    KTH, Organisk kemi / Organic chemistry.
    Hagfeldt, Anders
    KTH, Fysikalisk kemi / Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Electronic and Molecular Surface Structure of a Polyene-diphenylaniline Dye Adsorbed from Solution onto Nanoporous TiO22007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 24, p. 8580-8586Article in journal (Refereed)
    Abstract [en]

    The surface electronic and molecular structure of a new organic chromophore useful for dye-sensitized nanostructured solar cells has been investigated by means of electron spectroscopy. Initially the use of a simple molecular system containing the polyene-diphenylaniline chromophore in a solar cell device was verified. The electronic and molecular surface structure of the functional dye-sensitized interface was then investigated in detail by a combination of core level spectroscopy, valence level spectroscopy, X-ray absorption spectroscopy, and resonant photoemission spectroscopy. The results indicate a dominating orientation of the molecule at the surface, having the diphenylaniline moiety pointing out from the surface. Valence level spectroscopy, X-ray absorption spectroscopy, and resonant photoemission spectroscopy were used to experimentally delineate the frontier electronic structure of the molecule, and the experimental spectra were analyzed against theoretical spectra, based on density functional theory. Together the investigation gives insight into energy matching of the molecular electronic states with respect to the TiO2 substrate as well as the localization of the frontier electronic states and the direction of the charge-transfer absorption process with regards to the TiO2 surface.

  • 27. Josefsson, Ida
    et al.
    Eriksson, Susanna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ottosson, Niklas
    Ohrwall, Gunnar
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, Michael
    Collective hydrogen-bond dynamics dictates the electronic structure of aqueous I-3(-)2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 46, p. 20189-20196Article in journal (Refereed)
    Abstract [en]

    The molecular and electronic structures of aqueous I-3 and I ions have been investigated through ab initio molecular dynamics (MD) simulations and photoelectron (PE) spectroscopy of the iodine 4d core levels. Against the background of the theoretical simulations, data from our I4d PE measurements are shown to contain evidence of coupled solute-solvent dynamics. The MD simulations reveal large amplitude fluctuations in the I-I distances, which couple to the collective rearrangement of the hydrogen bonding network around the I-3(-) ion. Due to the high polarizability of the I-3(-) ion, the asymmetric I-I vibration reaches partially dissociated configurations, for which the electronic structure resembles that of I-2 + I-. The charge localization in the I-3(-) ion is found to be moderated by hydrogen-bonding. As seen in the PE spectrum, these soft molecular vibrations are important for the electronic properties of the I-3(-) ion in solution and may play an important role in its electrochemical function.

  • 28.
    Karlsson, Patrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Bolik, Sara
    Richter, Jan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Mahrov, Boriss
    Department of Physical Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Johansson, E M J
    Blomquist, J
    Uvdal, P
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Sandell, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Interfacial properties of the nanostructured dye-sensitized solid heterojunction TiO2/RuL2(NCS)(2)/CuI2004In: Journal of Chemical Physics, Vol. 120, no 23, p. 11224-11232Article in journal (Refereed)
  • 29.
    Karlsson, Patrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Fysik 1.
    Richter, Jan Hinnerk
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Andersson, M P
    Blomquist, J
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Uvdal, P
    Sandell, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    UHV-MOCVD growth of TiO2 on SiOx/Si(111): Interfacial properties reflected in the Si 2p photoemission spectra2005In: Surface Science, Vol. 580, no 1-3, p. 207-217Article in journal (Refereed)
  • 30. Kashtanov, S
    et al.
    Augustsson, Andreas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Physics II.
    Luo, Yi
    Guo, J H
    Såthe, Conny
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Physics II.
    Rubensson, Jan-Erik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Physics II.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Physics II.
    Nordgren, Joseph
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Physics II.
    Ågren, Hans
    Local structures of liquid water studied by x-ray emission spectroscopy2004In: Physical Review B, Vol. 69, no 2Article in journal (Refereed)
  • 31.
    Keis, K
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Bauer, C
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Westermark, K
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nanostructured ZnO electrodes for dye-sensitized solar cell applications2002In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 148, no 1-3, p. 57-64Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized photoelectrochemical solar cells constitute a promising candidate in the search for cost-effective and environment-friendly solar cells. The most extensively studied, and to date the most efficient systems are based on titanium dioxide. In this paper, the possibilities to use nanostructured ZnO electrodes in photoelectrochemical solar cells are investigated. Various experimental techniques (e.g. infrared, photoelectron, femtosecond and nanosecond laser spectroscopies, laser flash induced photocurrent transient measurements, two and three-electrode photoelectrochemical measurements) show that the thermodynamics, kinetics and charge transport properties are comparable for ZnO and TiO2. The preparation techniques of ZnO provide more possibilities of varying the particle size and shape compared to TiO2. However, the dye-sensitization process is more complex in case of ZnO and care needs to be taken to achieve an optimal performance of the solar cell.

  • 32.
    Kristensen, E
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Rensmo, H
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Larsson, R
    Medicinska vetenskapsområdet, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology. Department of Physics and Materials Science, Physics I.
    Siegbahn, H
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Characterization of heparin surfaces using photoelectron spectroscopy and quartz crystal microbalance2003In: Biomaterials, Vol. 24, p. 4153-4159Article in journal (Refereed)
  • 33.
    Kristensen, Emma
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I.
    Nederberg, Fredrik
    Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I. polymerkemi.
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I.
    Bowden, Tim
    Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I. polymerkemi.
    Hilborn, Jöns
    Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I. polymerkemi.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Materials Chemistry, Polymer Chemistry. Department of Physics and Materials Science, Physics I.
    Photoelectron Spectroscopy Studies of the Functionalization of a Silicon Surface with a Phosphorylcholine-Terminated Polymer Grafted onto (3-Aminopropyl)trimethoxysilane2006In: Langmuir, Vol. 22, no 23, p. 9651-9657Article in journal (Refereed)
    Abstract [en]

    The structure of a biomimetic phosphorylcholine (PC)-functionalized poly(trimethylene carbonate) (PC-PTMC-PC), linked to a silicon substrate through an aminolysis reaction at 120 C with (3-aminopropyl)trimethoxysilane (APTMS), was studied using photoelectron spectroscopy. Two chemical states were found for the unreacted APTMS amine, a neutral state and a protonated state, where the protonated amine on average was situated closer to the silicon substrate than the neutral amine. The experiments also indicated the presence of a third chemical state, where amines interact with unreacted silanol groups. The PTMC chains of the grafted films were found to consist of only 2-3 repeat units, with the grafted chains enriched in the zwitterionic end group, suggesting that these groups are attracted to the surface. This was further supported by the experiments showing that the PC groups were situated deeper within the film.

  • 34.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Johansson, E
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Sandell, A
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Gorgoi, M
    Schäfers, F
    Braun, W
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Stüber, M
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Eberhardt, W
    HIKE experiments at KMC-1: Recent Analysis of Thin Film Nanocomposites2007In: Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m.b.H. (BESSY) Annual Report (2006), p. 503-504Article in journal (Other academic)
  • 35.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Persson, P.O.Å
    Lattermann, M
    Stüber, M
    Gorgoi, M
    Sandell, A
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Ziebert, C
    Schäfers, F
    Braun, W
    Halbritter, J
    Ulrich, S
    Eberhard, W
    Hultman, L
    Siegbahn, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    On the origin of a third spectral component of C1s XPS-spectra for nc-TiC/a-C nanocomposite thin films2008In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 202, no 15, p. 3563-3570Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) spectra of sputter-etched nc-TiC/a-C nanocomposite thin films published in literature show an extra feature of unknown origin in the C1s region. This feature is situated between the contributions of carbide and the carbon matrix. We have used high kinetic energy XPS (HIKE-XPS) on magnetron-sputtered nc-TiC/a-C thin films to show that this feature represents a third chemical environment in the nanocomposites, besides the carbide and the amorphous carbon. Our results show that component is present in as-deposited samples, and that the intensity is strongly enhanced by Ar+-ion etching. This third chemical environment may be due to interface or disorder effects. The implications of these observations on the XPS analysis of nanocomposites are discussed in the light of overlap problems for ternary carbon based systems.

  • 36.
    Lindblad, Rebecka
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Bi, Dongqin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Park, Byung-wook
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Oscarsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Gorgoi, Mihaela
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, Michael
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Electronic Structure of TiO2/CH3NH3PbI3 Perovskite Solar Cell Interfaces2014In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, no 4, p. 648-653Article in journal (Refereed)
    Abstract [en]

    The electronic structure and chemical composition of efficient CH3NH3PbI3 perovskite solar cell materials deposited onto mesoporous TiO2 were studied using photoelectron spectroscopy with hard X-rays. With this technique, it is possible to directly measure the occupied energy levels of the perovskite as well as the TiO2 buried beneath and thereby determine the energy level matching of the interface. The measurements of the valence levels were in good agreement with simulated density of states, and the investigation gives information on the character of the valence levels. We also show that two different deposition techniques give results indicating similar electronic structures.

  • 37.
    Lindblad, Rebecka
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Cappel, Ute
    O'Mahony, Flannan
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Haque, Saif A.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Energy level alignment in TiO2/metal sulfide/polymer interfaces for solar cell applications2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 32, p. 17099-17107Article in journal (Refereed)
    Abstract [en]

    Semiconductor sensitized solar cell interfaces have been studied with photoelectron spectroscopy to understand the interfacial electronic structures. In particular, the experimental energy level alignment has been determined for complete TiO2/metal sulfide/polymer interfaces. For the metal sulfides CdS, Sb2S3 and Bi2S3 deposited from single source metal xanthate precursors, it was shown that both driving forces for electron injection into TiO2 and hole transfer to the polymer decrease for narrower bandgaps. The energy level alignment results were used in the discussion of the function of solar cells with the same metal sulfides as light absorbers. For example Sb2S3 showed the most favourable energy level alignment with 0.3 eV driving force for electron injection and 0.4 eV driving force for hole transfer and also the most efficient solar cells due to high photocurrent generation. The energy level alignment of the TiO2/Bi2S3 interface on the other hand showed no driving force for electron injection to TiO2, and the performance of the corresponding solar cell was very low.

  • 38.
    Lindblad, Rebecka
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Jena, Naresh K
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Oscarsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Bi, Dongqin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mandal, Suman
    Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India.
    Pal, Banabir
    Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India.
    Sarma, Dipankar Das
    Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johansson, Erik M.J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Odelius, Michael
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Electronic Structure of CH3NH3PbX3 Perovskites: Dependence on the Halide Moiety2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 4, p. 1818-1825Article in journal (Refereed)
    Abstract [en]

    A combination of measurements using photoelectron spectroscopy and calculations using density functional theory (DFT) was applied to compare the detailed electronic structure of the organolead halide perovskites CH3NH3PbI3 and CH3NH3PbBr3. These perovskite materials are used to absorb light in mesoscopic and planar heterojunction solar cells. The Pb 4f core level is investigated to get insight into the chemistry of the two materials. Valence level measurments are also included showing a shift of the valence band edges where there is a higher binding energy of the edge for the CH3NH3PbBr3 perovskite. These changes are supported by the theoretical calculations which indicate that the differences in electronic structure are mainly caused by the nature of the halide ion rather than structural differences. The combination of photoelectron spectroscopy measurements and electronic structure calculations is essential to disentangle how the valence band edge in organolead halide perovskites is governed by the intrinsic difference in energy levels of the halide ions from the influence of chemical bonding.

  • 39.
    Mahrov, Boriss
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Photoelectron spectroscopy studies of Ru(dcbpyH(2))(2)(NCS)(2)/CuI and Ru(dcbpyH(2))(2)(NCS)(2)/CuSCN interfaces for solar cell applications2004In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 31, p. 11604-11610Article in journal (Refereed)
    Abstract [en]

    In this work, the electronic structure of the wide band gap hole conductors Cut and CuSCN in contact with an organic dye (Ru(dcbpyH(2))(2)(NCS)(2), cis-bis(4,4'-dicarboxy-2,2-bipyridine)bis(isothiocyanato)ruthenium(II)) were investigated by means of photoelectron spectroscopy. The experiments show specific interaction between the NCS groups of the dye molecules and the Cut and CuSCN surfaces. For Cut there are strong indications that the dye molecules interact with Cut through both NCS ligands. Also, one of the carboxylic groups is affected by the surface adsorption on the CuI substrate. For the CuSCN surface the results indicate that about half of the molecules interact with the surface through both NCS ligands, that about half of the molecules interact with the surface through one NCS ligand, and that there is no specific interaction with the carboxylic groups. The measurements also reveal changes in the electronic structure of the dye molecule when adsorbed onto the substrates. In particular, changes in the upper valence electronic structure, important for the function of this material combination in a solar cell device, are discussed.

  • 40.
    Maibach, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eriksson, Susanna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ahlund, John
    Gustafsson, Torbjron
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Hakan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 4, article id 044101Article in journal (Refereed)
    Abstract [en]

    We report a methodology for a direct investigation of the solid/liquid interface using high pressure x-ray photoelectron spectroscopy (HPXPS). The technique was demonstrated with an electrochemical system represented by a Li-ion battery using a silicon electrode and a liquid electrolyte of LiClO4 in propylene carbonate (PC) cycled versus metallic lithium. For the first time the presence of a liquid electrolyte was realized using a transfer procedure where the sample was introduced into a 2 mbar N-2 environment in the analysis chamber without an intermediate ultrahigh vacuum (UHV) step in the load lock. The procedure was characterized in detail concerning lateral drop gradients as well as stability of measurement conditions over time. The X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the solid substrate and the liquid electrolyte can be observed simultaneously. The results show that the solid electrolyte interphase (SEI) composition for the wet electrode is stable within the probing time and generally agrees well with traditional UHV studies. Since the methodology can easily be adjusted to various high pressure photoelectron spectroscopy systems, extending the approach towards operando solid/liquid interface studies using liquid electrolytes seems now feasible. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

  • 41.
    Nytén, Anton
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Stjerndahl, Mårten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Armand, Michel
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Thomas, John O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Surface characterization and stability phenomena in Li2FeSiO4 studied by PES/XPS2006In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 16, no 34, p. 3483-3488Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy (PES) has been used to characterise the surface of Li2FeSiO4 cathodes extracted from lithium-ion batteries. Pristine, uncycled, air-exposed electrodes were first analysed and found to carry significantly greater amounts of Li2CO3 on their surfaces than electrodes stored under inert atmosphere. The surface film formed on electrochemical cycling of Li2FeSiO4 electrodes at 60 degrees C using a LiN(SO2CF3)(2) salt based electrolyte revealed high salt stability and only small amounts of solvent reaction products. These were mainly of Li-carboxylate type; neither carbonates nor LiF were found. The excellent capacity retention (<3% over 120 cycles) and minimal irreversible capacity during the first cycle are probably a direct result of this very thin surface film. Li2FeSiO4 must therefore be seen as a most promising ( and potentially cheap) positive electrode material for future large-scale Li-ion battery applications.

  • 42.
    Oscarsson, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Eriksson K., Susanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Eriksson, Anna I. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Interface Structure Effects upon Co-Adsorption of Black Dye and D35 on TiO2Manuscript (preprint) (Other academic)
  • 43.
    Oscarsson, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Eriksson, Susanna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Eriksson, Anna I. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Zia, Azhar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Coadsorption of Dye Molecules at TiO2 Surfaces: A Photoelectron Spectroscopy Study2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 23, p. 12484-12494Article in journal (Refereed)
    Abstract [en]

    The effects of coadsorbing the amphiphilic ruthenium-based dye Z907 (cis-bis(isothiocyanato)(2,20-bipyridy1-4,40-dicarboxylato)(4,40-dinony1-20-bipyridy1)-ruthenium(II)) with the coadsorbent DPA (n-decylphosphonic acid) and with the organic dye D35 ((E)-3-(5-(4-(bis(2',4'-dibutoxybiphenyl-4-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid) on mesoporous TiO2 were investigated using photoelectron spectroscopy (PES). Z907 is expected to adsorb to the TiO2 surface via the carboxylic acid groups. However, Z907 also shows signs of interacting with the TiO2 via the sulfur of the thiocyanate groups, and this interaction is affected by both the addition of DPA and D35. DPA, when added, exchanges with Z907 at the TiO2 surface, and each Z907 is replaced by six DPA molecules, but it does not affect the energy level alignment between Z907 and TiO2 substantially. Adding D35 to Z907 induces changes in the adsorption configuration of Z907 by the means of suppressing the interaction of the thiocyanate ligands and the TiO2 surface. The HOMO level of Z907 is shifted by the addition of D35. Coadsorbing Z907 with D35 thus gives changes at a molecular level, meaning that this is an example of collaborative sensitization.

  • 44.
    Philippe, Bertrand
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, SE-75121 Uppsala, Sweden..
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Photoelectron Spectroscopy for Lithium Battery Interface Studies2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 2, p. A178-A191Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy (PES) has become an important tool for investigating Li-ion battery materials, in particular for analyzing interfacial structures and reactions. Since the methodology was introduced in the battery research area, PES has undergone a dramatic development regarding photon sources, sample handling and electron energy analyzers. This includes the possibility to use synchrotron radiation with increased intensity and the possibility to vary the photon energy. The aim of the present paper is to describe how PES can be used to investigate battery interfaces and specifically highlight how synchrotron based PES has been implemented to address different questions useful for the development of the Li-ion batteries. We also present some recent developments of the techniques, which have the potential to further push the limits for the use of photoelectron spectroscopy in battery research.

  • 45.
    Plogmaker, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Linusson, Per
    Eland, John H D
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Baker, Neville
    Johansson, Erik M J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Feifel, Raimund
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Versatile high-repetition-rate phase-locked chopper system for fast timing experiments in the vacuum ultraviolet and x-ray spectral region2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 1, p. 013115-Article in journal (Refereed)
    Abstract [en]

    A novel light chopper system for fast timing experiments in the vacuum-ultraviolet (VUV) and x-ray spectral region has been developed. It can be phase-locked and synchronized with a synchrotron radiation storage ring, accommodating repetition rates in the range of ∼8 to ∼120 kHz by choosing different sets of apertures and subharmonics of the ring frequency (MHz range). Also the opening time of the system can be varied from some nanoseconds to several microseconds to meet the needs of a broad range of applications. Adjusting these parameters, the device can be used either for the generation of single light pulses or pulse packages from a microwave driven, continuous He gas discharge lamp or from storage rings which are otherwise often considered as quasi-continuous light sources. This chopper can be utilized for many different kinds of experiments enabling, for example, unambiguous time-of-flight (TOF) multi-electron coincidence studies of atoms and molecules excited by a single light pulse as well as time-resolved visible laser pump x-ray probe electron spectroscopy of condensed matter in the valence and core level region.

  • 46.
    Plogmaker, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Terschlüsen, Joachim A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kerbs, N.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Svanqvist, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Forsberg, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Söderström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    HELIOS-A laboratory based on high-order harmonic generation of extreme ultraviolet photons for time-resolved spectroscopy2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 12, article id 123107Article in journal (Refereed)
    Abstract [en]

    In this paper, we present the HELIOS (High Energy Laser Induced Overtone Source) laboratory, an in-house high-order harmonic generation facility which generates extreme ultraviolet (XUV) photon pulses in the range of 15-70 eV with monochromatized XUV pulse lengths below 35 fs. HELIOS is a source for time-resolved pump-probe/two-color spectroscopy in the sub-50 fs range, which can be operated at 5 kHz or 10 kHz. An optical parametric amplifier is available for pump-probe experiments with wavelengths ranging from 240 nm to 20 000 nm. The produced XUV radiation is monochromatized by a grating in the so-called off-plane mount. Together with overall design parameters, first monochromatized spectra are shown with an intensity of 2 . 10(10) photons/s (at 5 kHz) in the 29th harmonic, after the monochromator. The XUV pulse duration is measured to be <25 fs after monochromatization.

  • 47.
    Rensmo, H
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Westermark, K
    Fitzmaurice, D
    Siegbahn, H
    Department of Physics and Materials Science, Physics I.
    Studies of dodecanethiol capped Ag and Au nanoparticles using synchrotron radiation based photoelectron spectroscopy2002In: Langmuir, Vol. 18, no 26, p. 10372-10378Article in journal (Refereed)
  • 48.
    Rensmo, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Photoelectron Spectroscopy for Chemical Analysis2015In: Chimia (Basel), ISSN 0009-4293, Vol. 69, no 1-2, p. 22-29Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy started its modern development in the fifties based on techniques for studies of nuclear decay. Since then, photoelectron spectroscopy has undergone a dramatic expansion of application and is now a prime research tool in basic and applied science. This progress has been largely due to the concomitant development of photon sources, sample handling and electron energy analyzers. The present article describes some of the salient features of modern photoelectron spectroscopy and its applications with particular emphasis on energy relevant issues.

  • 49.
    Richter, Jan Hinnerk
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Henningsson, Anders
    Karlsson, Patrik
    Department of Physics and Materials Science, Physics I.
    Andersson, M P
    Uvdal, P
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Sandell, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Electronic structure of lithium-doped anatase TiO2 prepared in ultrahigh vacuum2005In: Physical Review B, Vol. 71, no 23Article in journal (Refereed)
  • 50.
    Richter, Jan Hinnerk
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Fysik 1.
    Henningsson, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism.
    Sanyal, Biplab
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Theoretical Magnetism.
    Karlsson, Patrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Fysik 1.
    Andersson, M. P.
    Uvdal, P
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Fysik 1.
    Eriksson, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Theoretical Magnetism.
    Sandell, Anders
    Department of Physics and Materials Science, Physics I. Theoretical Magnetism. Fysik 1.
    Phase separation and charge localization in UHV-lithiated anatase TiO2 nanoparticles2005In: Physical Review B, ISSN 1098-0121, Vol. 71, no 23, p. 235419-Article in journal (Refereed)
    Abstract [en]

    The insertion of lithium in anatase TiO2 nanoparticles under ultrahigh vacuum (UHV) conditions is studied using x-ray absorption spectroscopy (XAS) and resonant photoelectron spectroscopy (RPES) at the Ti L2,3 edge. It is demonstrated that XAS can be used to monitor the separation into an anatase phase and a lithium titanate phase of formal stoichiometry Li0.5TiO2. The initial state properties of the Ti 3d states of the lithium titanate phase are investigated using ab initio electronic structure calculations. The calculations show a correlation driven separation of Ti 3d states from the conduction band in agreement with previous studies. It is shown that Ti in different oxidation states (Ti3+ and Ti4+) is formed as a direct consequence of the electron-electron interaction. RPES and XAS spectra confirm the presence of electronically inequivalent Ti sites. The site-sensitivity of the RPES spectra at selected electron binding energies is found to be consistent with the calculations.

12 1 - 50 of 62
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