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Kaufmann, Susanna
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Publications (10 of 19) Show all publications
Eriksson K., S., Josefsson, I., Ellis, H., Amat, A., Pastore, M., Oscarsson, J., . . . Rensmo, H. (2016). Geometrical and energetical structural changes in organic dyes for dye-sensitized solar cells probed with photoelectron spectroscopy and DFT. Physical Chemistry, Chemical Physics - PCCP, 18(1), 252-260
Open this publication in new window or tab >>Geometrical and energetical structural changes in organic dyes for dye-sensitized solar cells probed with photoelectron spectroscopy and DFT
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2016 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 1, p. 252-260Article in journal (Other academic) Published
Abstract [en]

The effects of alkoxy chain length in triarylamine based donor acceptor organic dyes are investigated with respect to the electronic and molecular surface structures on the performance of solar cells and the electron lifetime. The dyes were investigated when adsorbed on TiO2 in a configuration that can be used for dye sensitized solar cells (DSCs). Specifically, the two dyes D35 and D45 were compared using photoelectron spectroscopy (PES) and density functional theory (DFT) calculations. The differences in solar cell characteristics when longer alkoxy chains are introduced in the dye donor unit are attributed to geometrical changes in dye packing while only minor differences were observed in the electronic structure. A higher dye load was observed for D45 on TiO2. However, D35 based solar cells result in higher photocurrent although the dye load is lower. This is explained by different geometrical structures of the dyes on the surface.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-230853 (URN)10.1039/c5cp04589d (DOI)000368755500027 ()
Funder
Swedish Research CouncilCarl Tryggers foundation Swedish Energy AgencyStandUp
Available from: 2014-08-31 Created: 2014-08-31 Last updated: 2017-12-05Bibliographically approved
Maibach, J., Xu, C., Eriksson, S. K., Ahlund, J., Gustafsson, T., Siegbahn, H., . . . Hahlin, M. (2015). A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system. Review of Scientific Instruments, 86(4), Article ID 044101.
Open this publication in new window or tab >>A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system
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2015 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 4, article id 044101Article in journal (Refereed) Published
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.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-255308 (URN)10.1063/1.4916209 (DOI)000353837700037 ()25933870 (PubMedID)
Funder
Swedish Research Council, 2012-4681EU, FP7, Seventh Framework Programme, 608575
Available from: 2015-06-16 Created: 2015-06-15 Last updated: 2017-12-04Bibliographically approved
Gabrielsson, E., Tian, H., Eriksson, S. K., Gao, J., Chen, H., Li, F., . . . Sun, L. (2015). Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells. Chemical Communications, 51(18), 3858-3861
Open this publication in new window or tab >>Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells
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2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 18, p. 3858-3861Article in journal (Refereed) Published
Abstract [en]

Dipicolinic acidwas investigated as a new anchoring group for DSSCs. A pilot dye (PD2) bearing this new anchoring group was found to adsorb significantly stronger to TiO2 than its cyanoacrylic acid analogue. The electrolyte composition was found to have a strong effect on the photoelectrochemical properties of the adsorbed dye in the device, allowing the dye LUMO energy to be tuned by 0.5 eV. Using a pyridine-free electrolyte, panchromatic absorption of the dye on TiO2 extending to 900 nm has been achieved. Solar cells using PD2 and a Co(bpy)(3) based electrolyte showed unique stability under simulated sunlight and elevated temperatures.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-249034 (URN)10.1039/c4cc06432a (DOI)000349990600035 ()25655483 (PubMedID)
Available from: 2015-04-23 Created: 2015-04-10 Last updated: 2017-12-04Bibliographically approved
Edwards, M. O. M., Karlsson, P. G., Eriksson, S. K., Hahlin, M., Siegbahn, H., Rensmo, H., . . . Ahlund, J. (2015). Increased photoelectron transmission in High-pressure photoelectron spectrometers using "swift acceleration". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 785, 191-196
Open this publication in new window or tab >>Increased photoelectron transmission in High-pressure photoelectron spectrometers using "swift acceleration"
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2015 (English)In: 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) Published
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.

Keywords
High-pressure X-ray photoelectron spectroscopy, Photoelectron spectroscopy, Scientific instrumentation, Spectrometer, Charge particle analyser
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-252668 (URN)10.1016/j.nima.2015.02.047 (DOI)000352815400029 ()
Funder
VINNOVASwedish Research Council, 2012-4721Swedish Research Council, 2012-4681
Available from: 2015-05-26 Created: 2015-05-11 Last updated: 2017-12-04Bibliographically approved
Jena, N. K., Josefsson, I., Eriksson, S. K., Hagfeldt, A., Siegbahn, H., Björneholm, O., . . . Odelius, M. (2015). Solvent-Dependent Structure of the I-3(-) Ion Derived from Photoelectron Spectroscopy and Ab Initio Molecular Dynamics Simulations. Chemistry - A European Journal, 21(10), 4049-4055
Open this publication in new window or tab >>Solvent-Dependent Structure of the I-3(-) Ion Derived from Photoelectron Spectroscopy and Ab Initio Molecular Dynamics Simulations
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2015 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 10, p. 4049-4055Article in journal (Refereed) Published
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.

Keywords
ab initio calculations, hydrogen bonds, molecular dynamics, photoelectron spectroscopy, solvent effects
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-251438 (URN)10.1002/chem.201405549 (DOI)000350762400027 ()25631177 (PubMedID)
Available from: 2015-04-23 Created: 2015-04-17 Last updated: 2017-12-04Bibliographically approved
Eriksson, S. K., Hahlin, M., Kahk, J. M., Villar-Garcia, I. J., Webb, M. J., Grennberg, H., . . . Payne, D. J. (2014). A versatile photoelectron spectrometer for pressures up to 30 mbar. Review of Scientific Instruments, 85(7), 075119
Open this publication in new window or tab >>A versatile photoelectron spectrometer for pressures up to 30 mbar
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2014 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 7, p. 075119-Article in journal (Refereed) Published
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.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-230851 (URN)10.1063/1.4890665 (DOI)000341176600066 ()25085185 (PubMedID)
Available from: 2014-08-31 Created: 2014-08-31 Last updated: 2017-12-30
Tian, H., Oscarsson, J., Gabrielsson, E., Eriksson, S. K., Lindblad, R., Xu, B., . . . Sun, L. (2014). Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor. Scientific Reports, 4, 4282
Open this publication in new window or tab >>Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor
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2014 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, p. 4282-Article in journal (Refereed) Published
Abstract [en]

Supramolecular interactions based on porphyrin and fullerene derivatives were successfully adopted to improve the photovoltaic performance of p-type dye-sensitized solar cells (DSCs). Photoelectron spectroscopy (PES) measurements suggest a change in binding configuration of ZnTCPP after co-sensitization with C60PPy, which could be ascribed to supramolecular interaction between ZnTCPP and C60PPy. The performance of the ZnTCPP/C60PPy-based p-type DSC has been increased by a factor of 4 in comparison with the DSC with the ZnTCPP alone. At 560 nm, the IPCE value of DSCs based on ZnTCPP/C60PPy was a factor of 10 greater than that generated by ZnTCPP-based DSCs. The influence of different electrolytes on charge extraction and electron lifetime was investigated and showed that the enhanced V-oc from the Co2+/(3+)(dtbp)(3)-based device is due to the positive E-F shift of NiO.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-222728 (URN)10.1038/srep04282 (DOI)000332374500002 ()
Available from: 2014-04-17 Created: 2014-04-14 Last updated: 2017-12-05
Kaufmann Eriksson, S. (2014). Interfaces in Dye-Sensitized Solar Cells Studied with Photoelectron Spectroscopy at Elevated Pressures. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Interfaces in Dye-Sensitized Solar Cells Studied with Photoelectron Spectroscopy at Elevated Pressures
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With an increasing demand for renewable energy sources, research efforts on different solar cell technologies are increasing rapidly. The dye-sensitized solar cell (DSC) is one such technology, taking advantage of light absorption in dye molecules. The liquid based DSC contains several interesting and important interfaces, crucial for the understanding and development of the solar cell performance. Examples of such interfaces include dye-semiconductor, electrode-electrolyte and solute-solvent interfaces. Ultimately, complete interfaces with all these components included are of particular interest. One major challenge is to understand the key functions of these systems at an atomic level and one way to achieve this is to use an element specific and surface sensitive tool, such as photoelectron spectroscopy (PES). This thesis describes the use and development of PES for studying interfaces in the DSC.

The materials part of the thesis focuses on interfaces in DSCs studied with PES and the methodology development parts focus on methods to use PES for investigations of solvated heterogeneous interfaces of interest for photoelectrochemical systems such as the DSC. More specifically, beginning with standard vacuum techniques, dye molecules bound to a semiconductor surface have been studied in terms of energy level alignment, surface coverage and binding configuration. To increase the understanding of solvation phenomena present in the liquid DSC, liquid jet experiments have been performed in close combination with theoretical quantum calculations. As a step towards an in-situ method to measure a complete, functioning (in operando) solar cell, methodology development and measurements performed with higher sample pressures are described using new high pressure X-ray photoelectron spectroscopy techniques (HPXPS).

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. p. 75
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1173
Keywords
Dye-sensitized solar cells, interfaces, solvation, photoelectron spectroscopy, HPXPS, HP-HAXPES, liquid jet
National Category
Physical Chemistry
Research subject
Chemistry with specialization in Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-230855 (URN)978-91-554-9022-5 (ISBN)
Public defence
2014-10-17, Häggsalen, Ångström laboratory, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2014-09-25 Created: 2014-08-31 Last updated: 2015-01-23
Eriksson, S. K., Josefsson, I., Ottosson, N., Ohrwall, G., Bjorneholm, O., Siegbahn, H., . . . Rensmo, H. (2014). Solvent Dependence of the Electronic Structure of I- and I-3(-). Journal of Physical Chemistry B, 118(11), 3164-3174
Open this publication in new window or tab >>Solvent Dependence of the Electronic Structure of I- and I-3(-)
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2014 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, no 11, p. 3164-3174Article in journal (Refereed) Published
Abstract [en]

We present synchrotron-based I4d photoelectron spectroscopy experiments of solutions from LiI and LiI3 in water, ethanol, and acetonitrile. The experimentally determined solvent-induced binding energy shifts (SIBES) for the monatomic I- anion are compared to predictions from simple Born theory, PCM calculations, as well as multiconfigurational quantum chemical spectral calculations from geometries obtained through molecular dynamics of solvated clusters. We show that the SIBES for I- explicitly depend on the details of the hydrogen bonding configurations of the solvent to the I- and that static continuum models such as the Born model cannot capture the trends in the SIBES observed both in experiments and in higher-level calculations. To extend the discussion to more complex polyatomic anions, we also performed experiments on I-3(-) and I-/I-3(-) mixtures in different solvents and the results are analyzed in the perspective of SIBES. The experimental SIBES values indicate that the solvation effects even for such similar anions as I- and I-3(-) can be rather different in nature.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-223887 (URN)10.1021/jp500533n (DOI)000333381800039 ()
Available from: 2014-05-05 Created: 2014-04-28 Last updated: 2017-12-05Bibliographically approved
Josefsson, I., Eriksson, S. K., Ottosson, N., Ohrwall, G., Siegbahn, H., Hagfeldt, A., . . . Odelius, M. (2013). Collective hydrogen-bond dynamics dictates the electronic structure of aqueous I-3(-). Physical Chemistry, Chemical Physics - PCCP, 15(46), 20189-20196
Open this publication in new window or tab >>Collective hydrogen-bond dynamics dictates the electronic structure of aqueous I-3(-)
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2013 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 46, p. 20189-20196Article in journal (Refereed) Published
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.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-212437 (URN)10.1039/c3cp52866a (DOI)000326747200028 ()
Available from: 2013-12-10 Created: 2013-12-10 Last updated: 2017-12-06Bibliographically approved
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