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  • 1. Abdi-Jalebi, Mojtaba
    et al.
    Andaji-Garmaroudi, Zahra
    Cacovich, Stefania
    Stavrakas, Camille
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Richter, Johannes M.
    Alsari, Mejd
    Booker, Edward P.
    Hutter, Eline M.
    Pearson, Andrew J.
    Lilliu, Samuele
    Savenije, Tom J.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Divitini, Giorgio
    Ducati, Caterina
    Friend, Richard H.
    Stranks, Samuel D.
    Maximizing and stabilizing luminescence from halide perovskites with potassium passivation2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 555, p. 497-501Article in journal (Refereed)
    Abstract [en]

    Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability2 (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield—a quantity that must be maximized to obtain high efficiency—remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can approach the efficiency limits in tandem solar cells, coloured-light-emitting diodes and other optoelectronic applications.

  • 2.
    Abdi-Jalebi, Mojtaba
    et al.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Dar, M. Ibrahim
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Alsari, Mejd
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Sadhanala, Aditya
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Diyitini, Giorgio
    Univ Cambridge, Dept Mat Sci & Met, Charles Babbage Rd, Cambridge, England.
    Imani, Roghayeh
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lilliu, Samuele
    Univ Sheffield, Dept Phys & Astron, Sheffield, S Yorkshire, England; UAE Ctr Crystallog, Dubai, U Arab Emirates.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gratzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Friend, Richard H.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Dedoping of Lead Halide Perovskites Incorporating Monovalent Cations2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 7, p. 7301-7311Article in journal (Refereed)
    Abstract [en]

    We report significant improvements in the optoelectronic properties of lead halide perovskites with the addition of monovalent ions with ionic radii close to Pb2+. We investigate the chemical distribution and electronic structure of solution processed CH3NH3PbI3 perovskite structures containing Na+, Cu+, and Ag+, which are lower valence metal ions than Pb2+ but have similar ionic radii. Synchrotron X-ray diffraction reveals a pronounced shift in the main perovskite peaks for the monovalent cation-based films, suggesting incorporation of these cations into the perovskite lattice as well as a preferential crystal growth in Ag+ containing perovskite structures. Furthermore, the synchrotron X-ray photoelectron measurements show a significant change in the valence band position for Cu- and Ag-doped films, although the perovskite bandgap remains the same, indicating a shift in the Fermi level position toward the middle of the bandgap. Such a shift infers that incorporation of these monovalent cations dedope the n-type perovskite films when formed without added cations. This dedoping effect leads to cleaner bandgaps as reflected by the lower energetic disorder in the monovalent cation-doped perovskite thin films as compared to pristine films. We also find that in contrast to Ag+ and Cu+, Na+ locates mainly at the grain boundaries and surfaces. Our theoretical calculations confirm the observed shifts in X-ray diffraction peaks and Fermi level as well as absence of intrabandgap states upon energetically favorable doping of perovskite lattice by the monovalent cations. We also model a significant change in the local structure, chemical bonding of metal-halide, and the electronic structure in the doped perovskites. In summary, our work highlights the local chemistry and influence of monovalent cation dopants on crystallization and the electronic structure in the doped perovskite thin films.

  • 3. Alarcón, H.
    et al.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Johansson, Erik M. J.
    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.
    Hagfeldt, Anders
    KTH, Fysikalisk kemi / Physical Chemistry.
    Boschloo, Gerrit K.
    KTH, Fysikalisk kemi / Physical Chemistry.
    Modification of nanostructured TiO2 electrodes by electrochemical Al3+ insertion: Effects on dye-sensitized solar cell performance2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 35, p. 13267-13274Article in journal (Refereed)
    Abstract [en]

    Nanostructured TiO2 films were modified by insertion with aluminum ions using an electrochemical process. After heat treatment these films were found suitable as electrodes in dye-sensitized solar cells. By means of a catechol adsorption test, as well as photoelectron spectroscopy (PES), it was demonstrated that the density of Ti atoms at the metal oxide/electrolyte interface is reduced after Al modification. There is, however, not a complete coverage of aluminum oxide onto the TiO2, but the results rather suggest either the formation of a mixed Al−Ti oxide surface layer or formation of a partial aluminum oxide coating. No new phase could, however, be detected. In solar cells incorporating Al-modified TiO2 electrodes, both electron lifetimes and electron transport times were increased. At high concentrations of inserted aluminum ions, the quantum efficiency for electron injection was significantly decreased. Results are discussed at the hand of different models:  A multiple trapping model, which can explain slower kinetics by the creation of additional traps during Al insertion, and a surface layer model, which can explain the reduced recombination rate, as well as the reduced injection efficiency, by the formation of a blocking layer.

  • 4.
    Alfredsson, Y.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Sandell, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Siegbahn, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Electronic structure of TiOPc thin film on conducting glass studied by means of X-ray and photoelectron spectroscopies2009In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 174, no 1-3, p. 50-54Article in journal (Refereed)
    Abstract [en]

    Thin films of TiOPc have been investigated using photoelectron   spectroscopy (PES) and X-ray spectroscopy (XAS). The results are   interpreted in terms of the local geometry around the metal center both   with regard to bonding and crystal field symmetry. Core and valence PES   have been found to be in accordance with the structural characteristics   of the TiOPc molecule. For resonant PES at the N1s and Ti2p edges,   information on the local electronic structure of the occupied molecular   orbitals has been obtained. Ti2p XAS was interpreted in terms of   five-fold coordination around the titanium atom for TiOPc of C-4V   symmetry. Angle-resolved N1s XAS suggests the molecular planes to order   preferentially parallel to the sample surface plane.

  • 5.
    Andaji-Garmaroudi, Zahra
    et al.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Abdi-Jalebi, Mojtaba
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;UCL, Inst Mat Discovery, Torrington Pl, London WC1E 7JE, England..
    Kosasih, Felix U.
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Doherty, Tiarnan
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Macpherson, Stuart
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Bowman, Alan R.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ducati, Caterina
    Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England..
    Friend, Richard H.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England..
    Stranks, Samuel D.
    Univ Cambridge, Cavendish Lab, Dept Phys, JJ Thomson Ave, Cambridge CB3 0HE, England.;Univ Cambridge, Dept Chem Engn & Biotechnol, Philippa Fawcett Dr, Cambridge CB3 0AS, England..
    Elucidating and Mitigating Degradation Processes in Perovskite Light-Emitting Diodes2020In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 10, no 48, article id 2002676Article in journal (Refereed)
    Abstract [en]

    Halide perovskites have attracted substantial interest for their potential as disruptive display and lighting technologies. However, perovskite light-emitting diodes (PeLEDs) are still hindered by poor operational stability. A fundamental understanding of the degradation processes is lacking but will be key to mitigating these pathways. Here, a combination of in operando and ex situ measurements to monitor the performance degradation of (Cs(0.06)FA(0.79)MA(0.15))Pb(I0.85Br0.15)(3) PeLEDs over time is used. Through device, nanoscale cross-sectional chemical mapping, and optical spectroscopy measurements, it is revealed that the degraded performance arises from an irreversible accumulation of bromide content at one interface, which leads to barriers to injection of charge carriers and thus increased nonradiative recombination. This ionic segregation is impeded by passivating the perovskite films with potassium halides, which immobilizes the excess halide species. The passivated PeLEDs show enhanced external quantum efficiency (EQE) from 0.5% to 4.5% and, importantly, show significantly enhanced stability, with minimal performance roll-off even at high current densities (>200 mA cm(-2)). The decay half-life for the devices under continuous operation at peak EQE increases from <1 to approximate to 15 h through passivation, and approximate to 200 h under pulsed operation. The results provide generalized insight into degradation pathways in PeLEDs and highlight routes to overcome these challenges.

  • 6.
    Cappel, Ute B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, Stockholm, Sweden.
    Liu, Peng
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Kloo, Lars
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden.
    Gardner, James M.
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic Structure Characterization of Cross-Linked Sulfur Polymers2018In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 9, p. 1041-1047Article in journal (Refereed)
    Abstract [en]

    Cross-linked polymers of elemental sulfur are of potential interest for electronic applications as they enable facile thin-film processing of an abundant and inexpensive starting material. Here, we characterize the electronic structure of a cross-linked sulfur/diisopropenyl benzene (DIB) polymer by a combination of soft and hard X-ray photoelectron spectroscopy (SOXPES and HAXPES). Two different approaches for enhancing the conductivity of the polymer are compared: the addition of selenium in the polymer synthesis and the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) during film preparation. For the former, we observe the incorporation of Se into the polymer structure resulting in a changed valence-band structure. For the latter, a Fermi level shift in agreement with p-type doping of the polymer is observed and also the formation of a surface layer consisting mostly of TFSI anions.

  • 7.
    Cappel, Ute B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Terschlüsen, Joachim Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Leitner, Thorsten
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johansson, Erik J. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    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.
    Svensson, Svante
    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.
    Rensmo, Håkan
    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.
    Direct measurement of excited electrons in a low bandgap polymer using XUV based time-resolved photoelectron spectroscopyIn: Article in journal (Refereed)
  • 8.
    Cappel, Ute B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Smeigh, Amanda L.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Johansson, Erik M. J.
    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.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Characterization of the Interface Properties and Processes in Solid State Dye-Sensitized Solar Cells Employing a Perylene Sensitizer2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 10, p. 4345-4358Article in journal (Refereed)
    Abstract [en]

    We recently reported on a perylene sensitizer, ID176, which performs much better in solid state dye-sensitized solar cells than in those using liquid electrolytes with iodide/tri-iodide as the redox couple (J. Phys. Chem. C2009, 113, 14595-14597). Here, we present a characterization of the sensitizer and of the TiO2/dye interface by UV-visible absorption and fluorescence spectroscopy, spectroelectrochemistry, photoelectron spectroscopy, electroabsorption spectroscopy, photoinduced absorption spectroscopy, and femtosecond transient absorption measurements. We report that the absorption spectrum of the sensitizer is red-shifted by addition of lithium ions to the surface due to a downward shift of the excited state level of the sensitizer, which is of the same order of magnitude as the downward shift of the titanium dioxide conduction band edge. Results from photoelectron spectroscopy and electrochemistry suggest that the excited state is largely located below the conduction band edge of TiO2 but that there are states in the band gap of TiO2 which might be available for photoinduced electron injection. The sensitizer was able to efficiently inject into TiO2, when a lithium salt was present on the surface, while injection was much less effective in the absence of lithium ions or in the presence of solvent. In the presence of the hole conductor 2,2-,7,7-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9-spirobifluorene (spiro-MeOTAD) and LiTFSI, charge separation was monitored by the emergence of a Stark shift of the dye in transient absorption spectra, and both injection and regeneration appear to be completed within 1 ps. Regeneration by spiro-MeOTAD is therefore several orders of magnitude faster than regeneration by iodide, and ID176 can even be photoreduced by spiro-MeOTAD.

  • 9.
    Cappel, Ute B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Johansson, Fredrik O. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Aitola, Kerttu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Leitner, Torsten
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Foehlisch, Alexander
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.;Univ Potsdam, Inst Phys & Astron, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany..
    Svensson, Svante
    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. Uppsala Berlin Joint Lab Next Generat Photoelectr, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Boschloo, Gerrit
    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, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 34970-34978Article in journal (Refereed)
    Abstract [en]

    Metal halide perovskites have emerged as materials of high interest for solar energy-to-electricity conversion, and in particular, the use of mixed-ion structures has led to high power conversion efficiencies and improved stability. For this reason, it is important to develop means to obtain atomic level understanding of the photoinduced behavior of these materials including processes such as photoinduced phase separation and ion migration. In this paper, we implement a new methodology combining visible laser illumination of a mixed-ion perovskite ((FAP-bI(3))(0.85)(MAPbBr(3))(0.15)) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.

    Download full text (pdf)
    fulltext
  • 10.
    Cappel, Ute
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Boschloo, Gerrit
    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.
    Energy Alignment and Surface Dipoles of Rylene Dyes adsorbed to TiO2 nanoparticles2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 32, p. 14767-14774Article in journal (Refereed)
    Abstract [en]

    The energy loss in dye-sensitized solar cells calculated from the energy difference between the lowest electronic transition of the dye and the obtained open-circuit voltage is often 1 eV or even more. To minimize this loss, it is important to accurately determine the energy alignment at the TiO2/dye/redox-mediator interface. In this study, we compared the results from electrochemistry and photoelectron spectroscopy for determining the energy alignment of three rylene dyes, two of which absorb relatively far in the red. The trends observed with the methods were different, as in the former, the energy alignment is measured relative to an external reference and includes contributions from solvent reorganization energies, while in the latter, it is measured relative to the energetics of the TiO2 and is lacking such contributions. The influence of the dyes' dipole moments on the energetics of the TiO2 was also measured and explained some of the differences in trends. Finally, we compared the injection efficiencies of the two red-absorbing dyes and found that the differences in injection efficiencies can be better explained using the energy alignment determined from photoelectron spectroscopy. This shows that the method for measuring the energetics of a DSC should be chosen according to what process one intends to study.

    Download full text (pdf)
    Cappel_10.1039/c1cp20911f
  • 11.
    Chareev, Dmitriy A.
    et al.
    Ural Fed Univ, Ekaterinburg 620002, Russia; Inst Expt Mineral, Chernogolovka 142432, Russia; Kazan Fed Univ, Kazan 420008, Russia.
    Evstigneeva, Polina
    Inst Geol Ore Deposits Petrog Mineral & Geochem, Moscow 119017, Russia.
    Phuyal, Dibya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Man, Gabriel J.
    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.
    Vasiliev, Alexander N.
    Ural Fed Univ, Ekaterinburg 620002, Russia; Lomonosov Moscow State Univ, Moscow 119991, Russia; Natl Res South Ural State Univ, Chelyabinsk 454080, Russia.
    Abdel-Hafiez, Mahmoud
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Heidelberg Univ, Kirchhoff Inst Phys, D-69120 Heidelberg, Germany.
    Growth of Transition-Metal Dichalcogenides by Solvent Evaporation Technique2020In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 20, no 10, p. 6930-6938Article in journal (Refereed)
    Abstract [en]

    Due to their physical properties and potential applications in energy conversion and storage, transition-metal dichalcogenides (TMDs) have garnered substantial interest in recent years. Among this class of materials, TMDs based on molybdenum, tungsten, sulfur, and selenium are particularly attractive due to their semiconducting properties and the availability of bottom-up synthesis techniques. Here we report a method which yields high-quality crystals of transition-metal diselenide and ditelluride compounds (PtTe2, PdTe2, NiTe2, TaTe2, TiTe2, RuTe2, PtSe2, PdSe2, NbSe2, TiSe2, VSe2, ReSe2) from their solid solutions, via vapor deposition from a metal-saturated chalcogen melt. Additionally, we show the synthesis of rare-earth-metal polychalcogenides and NbS2 crystals using the aforementioned process. Most of the crystals obtained have a layered CdI2 structure. We have investigated the physical properties of selected crystals and compared them to state of the art findings reported in the literature. Remarkably, the charge density wave transition in 1T-TiSe2 and 2H-NbSe2 crystals is well-defined at TCDW ≈ 200 and 33 K, respectively. Angle-resolved photoelectron spectroscopy and electron diffraction are used to directly access the electronic and crystal structures of PtTe2 single crystals and yield state of the art measurements.

  • 12.
    Chernysheva, Ekaterina
    et al.
    UMR 125 CNRS St Gobain Rech, SVI, 39 Quai Lucien Lefranc, F-93303 Aubervilliers, France;Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Srour, Waked
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Baris, Bulent
    Sorbonne Univ, CNRS, Ecole Super Phys & Chim Ind, Lab Phys & Etud Mat,UMR 8213, 10 Rue Vauquelin, F-75005 Paris, France.
    Chenot, Stephane
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Felix Duarte, Roberto
    Helmholtz Zentrum Berlin Mat & Energie GmbH, D-12489 Berlin, Germany.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Mat & Energie GmbH, D-12489 Berlin, Germany.
    Cruguel, Herve
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Montigaud, Herve
    UMR 125 CNRS St Gobain Rech, SVI, 39 Quai Lucien Lefranc, F-93303 Aubervilliers, France.
    Jupille, Jacques
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Cabailh, Gregory
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Grachev, Sergey
    UMR 125 CNRS St Gobain Rech, SVI, 39 Quai Lucien Lefranc, F-93303 Aubervilliers, France.
    Lazzari, Remi
    Sorbonne Univ, CNRS, Inst NanoSci Paris, UMR 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Band alignment at Ag/ZnO(0001) interfaces: A combined soft and hard x-ray photoemission study2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 23, article id 235430Article in journal (Refereed)
    Abstract [en]

    Band alignment at the interface between evaporated silver films and Zn- or O-terminated polar orientations of ZnO is explored by combining soft and hard x-ray photoemissions on native and hydrogenated surfaces. Ultraviolet photoemission spectroscopy (UPS) is used to track variations of work function, band bending, ionization energy, and Schottky barrier during silver deposition. The absolute values of band bending and the bulk position of the Fermi level are determined on continuous silver films by hard x-ray photoemission spectroscopy (HAXPES) through a dedicated modeling of core levels. Hydrogenation leads to the formation of similar to 0.3 monolayer of donorlike hydroxyl groups on both ZnO-O and ZnO-Zn surfaces and to the release of metallic zinc on ZnO-Zn. However, no transition to an accumulation layer is observed. On bare surfaces, silver adsorption is cationic on ZnO(000 (1) over bar)-O [anionic on ZnO(0001)-Zn] at the earliest stages of growth as expected from polarity healing before adsorbing as a neutral species. UPS and HAXPES data appear quite consistent. The two surfaces undergo rather similar band bendings for all types of preparation. The downward band bending of V-bb,(ZnO-O) = -0.4 eV and V-bb,(ZnO-Zn) = -0.6 eV found for the bare surfaces is reinforced upon hydrogenation (V-bb,(ZnO-O+H) = -1.1 eV, V-bb,(ZnO-Zn+H) = -1.2 eV). At the interface with Ag, a unique value of band bending of -0.75 eV is observed. While exposure to atomic hydrogen modulates strongly the energetic positions of the surface levels, a similar Schottky barrier of 0.5-0.7 eV is found for thick silver films on the two surfaces.

  • 13.
    Ciosek Högström, Katarzyna
    et al.
    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, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    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.
    Aging of electrode/electrolyte interfaces in LiFePO4/graphite cells cycled with and without PMS additive2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 24, p. 12649-12660Article in journal (Refereed)
  • 14.
    Ciosek Högström, Katarzyna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    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, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    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.
    The Buried Carbon/Solid Electrolyte Interphase in Li-ion Batteries Studied by Hard X-ray Photoelectron Spectroscopy2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 138, p. 430-436Article in journal (Refereed)
  • 15.
    Ciosek Högström, Katarzyna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    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, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Thébault, Frédéric
    Chalmers university of technology.
    Johansson, Patrik
    Chalmers university of technology.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The influence of PMS-additive on the electrode/electrolyte interfaces in LiFePO4/graphite Li-ion batteries2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 45, p. 23476-23486Article in journal (Refereed)
    Abstract [en]

    The influence of a film-forming additive, propargyl methanesulfonate (PMS), on electrochemical performance and electrode/electrolyte interface composition of LiFePO4/graphite Li-ion batteries has been studied. Combined use of in-house X-ray photoelectron spectroscopy (XPS) and soft and hard X-ray photoelectron spectroscopy (PES) enabled nondestructive depth profiling at four different probing depths in the 2-50 nm range. Cells cycled with PMS and LiPF6 in ethylene carbonate/diethyl carbonate (EC/DEC) were compared to a reference sample cycled without PMS. In the first cycle, PMS cells showed a higher irreversible capacity, which is explained by formation of a thicker solid electrolyte interphase (SEI). After three cycles, the SET thicknesses were determined to be 19 and 25 nm for the reference and PMS samples, respectively. After the initial cycling, irreversible losses shown by the PMS cells were lower than those of the reference cell. This could be attributed to a different SET composition and lower differences in the amount of lithium between lithiated and delithiated electrodes for the PMS sample. It was suggested that PMS forms a triple-bonded radical on reduction, which further reacts with the electrolyte. The PMS additive was shown to influence the chemical composition at the positive electrode/electrolyte interface. Thicker interface layers with higher C-O and smaller LiF contributions were formed on LiFePO4 cycled with PMS.

  • 16.
    D'Amario, Luca
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Jiang, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gibson, Elizabeth A.
    Newcastle Univ, Sch Chem, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Sun, Licheng
    Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.; Organ Chem Royal Inst Technol KTH, Dept Chem, S-10044 Stockholm, Sweden..
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Royal Inst Technol KTH, Ctr Mol Devices, Dept Chem, S-10044 Stockholm, Sweden.
    Chemical and Physical Reduction of High Valence Ni States in Mesoporous NiO Film for Solar Cell Application.2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 39, p. 33470-33477Article in journal (Refereed)
    Abstract [en]

    The most common material for dye-sensitized photocathodes is mesoporous NiO. We transformed the usual brownish NiO to be more transparent by reducing high valence Ni impurities. Two pretreatment methods have been used: chemical reduction by NaBH4 and thermal reduction by heating. The power conversion efficiency of the cell was increased by 33% through chemical treatment, and an increase in open-circuit voltage from 105 to 225 mV was obtained upon heat treatment. By optical spectroelectrochemistry, we could identify two species with characteristically different spectra assigned to Ni3+ and Ni4+. We suggest that the reduction of surface Ni3+ and Ni4+ to Ni2+ decreases the recombination reaction between holes on the NiO surface with the electrolyte. It also keeps the dye firmly on the surface, building a barrier for electrolyte recombination. This causes an increase in open-circuit photovoltage for the treated film.

  • 17.
    Daniel, Quentin
    et al.
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Anabre, Ram B.
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Zhang, Biaobiao
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Chen, Hong
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Li, Fusheng
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Fan, Ke
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden..
    Ahmadi, Sareh
    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.
    Sun, Licheng
    KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Chem, S-10044 Stockholm, Sweden.;Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species2017In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 2, p. 1143-1149Article in journal (Refereed)
    Abstract [en]

    The use of cobalt porphyrin complexes as efficient and cost-effective molecular catalysts for water oxidation has been investigated previously. However, by combining a set of analytical techniques (electrochemistry, ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and synchrotron-based photoelectron spectroscopy (SOXPES and HAXPES)), we have demonstrated that three different cobalt porphyrins, deposited on FTO glasses, decompose promptly into a thin film of CoOx on the surface of the electrode during water oxidation under certain conditions (borate buffer pH 9.2). It is presumed that the film is composed of CoO, only detectable by SOXPES, as conventional techniques are ineffective. This newly formed film has a high turnover frequency (TOF), while the high transparency of the CoOx-based electrode is very promising for future application in photoelectrochemical cells.

  • 18.
    Doubaji, Siham
    et al.
    Univ Cadi Ayyad, FST Marrakesh, LCME, Marrakech 40000, Morocco..
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Saadoune, Ismael
    Univ Cadi Ayyad, FST Marrakesh, LCME, Marrakech 40000, Morocco.;Univ Mohammed VI Polytech, Ctr Adv Mat, Ben Guerir, Morocco..
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Mat & Energie, D-12489 Berlin, Germany..
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Solhy, Abderrahim
    Univ Mohammed VI Polytech, Ctr Adv Mat, Ben Guerir, Morocco..
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Passivation Layer and Cathodic Redox Reactions in Sodium-Ion Batteries Probed by HAXPES2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 1, p. 97-108Article in journal (Refereed)
    Abstract [en]

    The cathode material P2-NaxCo2/3Mn2/9Ni1/9O2, which could be used in Na-ion batteries, was investigated through synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES). Nondestructive analysis was made through the electrode/electrolyte interface of the first electrochemical cycle to ensure access to information not only on the active material, but also on the passivation layer formed at the electrode surface and referred to as the solid permeable interface (SPI). This investigation clearly shows the role of the SPI and the complexity of the redox reactions. Cobalt, nickel, and manganese are all electrochemically active upon cycling between 4.5 and 2.0V; all are in the 4+ state at the end of charging. Reduction to Co3+, Ni3+, and Mn3+ occurs upon discharging and, at low potential, there is partial reversible reduction to Co2+ and Ni2+. A thin layer of Na2CO3 and NaF covers the pristine electrode and reversible dissolution/reformation of these compounds is observed during the first cycle. The salt degradation products in the SPI show a dependence on potential. Phosphates mainly form at the end of the charging cycle (4.5V), whereas fluorophosphates are produced at the end of discharging (2.0V).

  • 19.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    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.
    Åhlund, John
    Scienta.
    Gustafsson, Torbjörn
    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, Håkan
    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.
    Recent progress in high pressure analyser and experimental method development applied to liquid/solid interface studies2015Conference paper (Refereed)
  • 20. 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.

  • 21.
    Ellis, Hanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Kaufmann Eriksson, Susanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Feldt, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Gabrielsson, Erik
    KTH, Organisk kemi.
    Lohse, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sun, Licheng
    KTH, Organisk kemi.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Linker Unit Modification of Triphenylamine-based Organic Dyes for Efficient Cobalt Mediated Dye-Sensitized Solar Cells2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 41, p. 21029-21036Article in journal (Refereed)
    Abstract [en]

    Linker unit modification of donor-linker-acceptor-based organic dyes was investigated with respect to the spectral and physicochemical properties of the dyes. The spectral response for a series of triphenylamine (TPA)-based organic dyes, called LEG1-4, was shifted into the red wavelength region, and the extinction coefficient of the dyes was increased by introducing different substituted dithiophene units on the pi-conjugated linker. The photovoltaic performance of dye-sensitized solar cells (DSCs) incorporating the different dyes in combination with cobalt-based electrolytes was found to be dependent on dye binding. The binding morphology of the dyes on the TiO2 was studied using photoelectron spectroscopy, which demonstrated that the introduction of alkyl chains and different substituents on the dithiophene linker unit resulted in a larger tilt angle of the dyes with respect to the normal of the TiO2-surface, and thereby a lower surface coverage. The good photovoltaic performance for cobalt electrolyte-based DSCs found here and by other groups using TPA-based organic dyes with a cyclopentadithiophene linker unit substituted with alkyl chains was mainly attributed to the extended spectral response of the dye, whereas the larger tilt angle of the dye with respect to the TiO2-surface resulted in less efficient packing of the dye molecules and enhanced recombination between electrons in TiO2 and Co(III) species in the electrolyte.

  • 22.
    Erbing, Axel
    et al.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Park, Byung-wook
    Ulsan Natl Inst Sci & Technol, Dept Energy & Chem Engn, 50 UNIST Gil, Ulsan 44919, South Korea..
    Cappel, Ute B.
    KTH Royal Inst Technol, Div Appl Phys Chem, Dept Chem, SE-10044 Stockholm, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Spatial microheterogeneity in the valence band of mixed halide hybrid perovskite materials2022In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 13, no 32, p. 9285-9294Article in journal (Refereed)
    Abstract [en]

    The valence band of lead halide hybrid perovskites with a mixed I/Br composition is investigated using electronic structure calculations and complementarily probed with hard X-ray photoelectron spectroscopy. In the latter, we used high photon energies giving element sensitivity to the heavy lead and halide ions and we observe distinct trends in the valence band as a function of the I : Br ratio. Through electronic structure calculations, we show that the spectral trends with overall composition can be understood in terms of variations in the local environment of neighboring halide ions. From the computational model supported by the experimental evidence, a picture of the microheterogeneity in the valence band maximum emerges. The microheterogeneity in the valence band suggests that additional charge transport mechanisms might be active in lead mixed halide hybrid perovskites, which could be described in terms of percolation pathways.

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  • 23.
    Eriksson K., Susanna
    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.
    Axnanda, Stephanus
    Crumlin, Ethan
    Wilks, Regan
    Eriksson, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Liu, Zhi
    Åhlund, John
    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.
    Starr, David
    Bär, Marcus
    Rensmo, Håkan
    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 high pressure XPSManuscript (preprint) (Other academic)
  • 24.
    Eriksson K., Susanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Josefsson, Ida
    Ellis, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Amat, Anna
    Pastore, Mariachiara
    Oscarsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. 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 - Ångström, Physical Chemistry.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Fantacci, Simona
    Odelius, Michael
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Geometrical and energetical structural changes in organic dyes for dye-sensitized solar cells probed with photoelectron spectroscopy and DFT2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 1, p. 252-260Article in journal (Other academic)
    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.

  • 25. 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.

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  • 26.
    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.

  • 27.
    Eriksson, Susanna K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Josefsson, Ida
    Ottosson, Niklas
    Ohrwall, Gunnar
    Bjorneholm, Olle
    Siegbahn, Hans
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Odelius, Michael
    Rensmo, Hakan
    Solvent Dependence of the Electronic Structure of I- and I-3(-)2014In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, no 11, p. 3164-3174Article in journal (Refereed)
    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.

  • 28.
    Fan, Ke
    et al.
    KTH Royal Inst Technol, Dept Chem, Organ Chem, S-10044 Stockholm, Sweden.;Wuhan Univ Technol, State Key Lab Adv Technol Mat Synth & Proc, Wuhan 430070, Peoples R China..
    Chen, Hong
    KTH Royal Inst Technol, Dept Chem, Organ Chem, S-10044 Stockholm, Sweden..
    Ji, Yongfei
    KTH Royal Inst Technol, Sch Biotechnol, Div Theoret Chem & Biol, SE-10691 Stockholm, Sweden..
    Huang, Hui
    KTH Royal Inst Technol, Dept Chem Surface & Corros Sci, SE-10044 Stockholm, Sweden..
    Claesson, Per Martin
    KTH Royal Inst Technol, Dept Chem Surface & Corros Sci, SE-10044 Stockholm, Sweden..
    Daniel, Quentin
    KTH Royal Inst Technol, Dept Chem, Organ Chem, S-10044 Stockholm, Sweden..
    Philippe, Bertrand
    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.
    Li, Fusheng
    KTH Royal Inst Technol, Dept Chem, Organ Chem, S-10044 Stockholm, Sweden..
    Luo, Yi
    KTH Royal Inst Technol, Sch Biotechnol, Div Theoret Chem & Biol, SE-10691 Stockholm, Sweden..
    Sun, Licheng
    KTH Royal Inst Technol, Dept Chem, Organ Chem, S-10044 Stockholm, Sweden.;Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation2016In: Nature Communications, E-ISSN 2041-1723, Vol. 7, article id 11981Article in journal (Refereed)
    Abstract [en]

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.

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  • 29.
    Fredin, Kristofer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Johansson, Erik M. J.
    Blom, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Using a molten organic conducting material to infiltrate a nanoporous semiconductor film and its use in solid-state dye-sensitized solar cells2009In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 159, no 1-2, p. 166-170Article in journal (Other academic)
    Abstract [en]

    We describe a method to fill thin films of nanoporous TiO2 with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 mu m below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO2/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process.

  • 30.
    Fredin, Kristofer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Schölin, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Gabrielsson, Erik
    Sun, Licheng
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Solid state dye-sensitized solar cells prepared by infiltrating a molten hole conductor into a mesoporous film at a temperature below 150 degrees C2011In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 161, no 21-22, p. 2280-2283Article in journal (Refereed)
    Abstract [en]

    Infiltration of a molten hole conductor in a mesoporous film at an elevated temperature exhibits good wetting performance and the procedure is therefore suitable as part of the preparation method for solid state dye-sensitized solar cells. Herein, we present a system prepared by infiltrating 4-(diethylamino)benzaldehyde-1,1)-diphenyl-hydrazone in its molten form at a temperature below 150 degrees C. The system displays a maximum photon-to-current conversion efficiency of about 35%, a value corresponding to an increase of about 5 times in comparison with a previously published system prepared by infiltrating a molten hole-conductor at a temperature exceeding 250 degrees C. By means of comparing charge transport and recombination with the results measured for a liquid analogue, we conclude that whereas the transport rates are similar, recombination is significantly more rapid in the solid-state device.

  • 31. Fullham, S
    et al.
    Rensmo, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics I.
    Noncovalent Self-Assembly of Silver and Gold Nanocrystal Aggregates in Solution2002In: Chemistry of Materials, Vol. 14, no 3643Article in journal (Other (popular scientific, debate etc.))
  • 32. Fullham, S
    et al.
    Rensmo, Håkan
    Fitzmaurice, D
    Carbon Nanotube Templated Self-Assembly and Thermal Processing of Gold Nanowires2000In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 12, no 19, p. 1430-1432Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Gold nanowires have been produced by the self-assembly of gold nanoparticles onto multi-walled carbon nanotubes. The nanotubes were mixed with a suspension of gold nanoparticles, resulting in a decrease in color intensity of the suspension, and indicating binding between the nanotubes and the gold (see Figure). Subsequent heating in air for 2 min gave rise to continuous nanowires up to 10 μm in length (see also cover).

  • 33. Gabrielsson, Erik
    et al.
    Tian, Haining
    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.
    Gao, Jiajia
    Chen, Hong
    Li, Fusheng
    Oscarsson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sun, Junliang
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kloo, Lars
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sun, Licheng
    Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 18, p. 3858-3861Article in journal (Refereed)
    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.

  • 34.
    Ganegoda, Hasitha
    et al.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Mukherjee, Soham
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Ma, Beihai
    Argonne Natl Lab, Appl Mat Div, 9700 S Cass Ave, Argonne, IL 60439 USA..
    Olive, Daniel T.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    McNeely, James H.
    IIT, Dept Chem, Chicago, IL 60616 USA..
    Kaduk, James A.
    IIT, Dept Chem, Chicago, IL 60616 USA.;Poly Crystallog Inc, Naperville, IL 60540 USA..
    Terry, Jeff
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Segre, Carlo U.
    IIT, Dept Phys, Chicago, IL 60616 USA.;IIT, Ctr Synchrotron Radiat Res & Instrumentat, Chicago, IL 60616 USA..
    Role of Fe Doping on Local Structure and Electrical and Magnetic Properties of PbTiO32021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 22, p. 12342-12354Article in journal (Refereed)
    Abstract [en]

    The local structure and multiferroic properties of iron-doped lead titanate (PbTi1-xFexO3-delta) samples was investigated over the entire composition range (x = 0-1). Inherent polarization in PbTiO3 decreases due to Fe3+ incorporation up to the solubility limit (x similar to 0.3), although homogeneous doping persists only up to x = 0.1. Ti prefers highly distorted oxygen octahedra for any x value, while Fe prefers more symmetric O-deficient polyhedra (Fe-O-n). The charge compensating oxygen vacancies induce local tilting of the Fe-O-n polyhedra beyond a critical x value (x >= 0.2), promoting magnetic interaction between two adjacent Fe atoms. The strain induced by local heterogeneity could act as a coupling force between magnetic and ferroelectric properties. Fe-rich clusters evolve into ferromagnetic PbFe12O19 with increased Fe doping. PbTi1-xFexO3-delta ( x >= 0.3) samples therefore have separate origins for the ferroelectric (PbTi1-xFexO3-delta) and magnetic (PbFe12O19) phases.

  • 35.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Kammlander, Birgit
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Riva, Stefania
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kuehn, Danilo
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, D-12489 Berlin, Germany..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, S-75120 Uppsala, Sweden..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    Interface Energy Alignment between Lead Halide Perovskite Single Crystals and TIPS-Pentacene2023In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 38, p. 15412-15420Article in journal (Refereed)
    Abstract [en]

    At present, there is a huge development in optoelectronic applications using lead halide perovskites. Considering that device performance is largely governed by the transport of charges across interfaces and, therefore, the interfacial electronic structure, fundamental investigations of perovskite interfaces are highly necessary. In this study, we use high-resolution soft X-ray photoelectron spectroscopy based on synchrotron radiation to explore the interfacial energetics for the molecular layer of TIPS-pentacene and lead halide perovskite single crystals. We perform ultrahigh vacuum studies on multiple thicknesses of an in situ formed interface of TIPS-pentacene with four different in situ cleaved perovskite single crystals (MAPbI(3), MAPbBr(3), FAPbBr(3), and Cs(x)FA(1-x)PbBr(y)I(3-y)). Our findings reveal a substantial shift of the TIPS-pentacene energy levels toward higher binding energies with increasing thickness, while the perovskite energy levels remain largely unaffected regardless of their composition. These shifts can be interpreted as band bending in the TIPS-pentacene, and such effects should be considered when assessing the energy alignment at perovskite/organic transport material interfaces. Furthermore, we were able to follow a reorganization on the MAPbI3 surface with the transformation of the surface C 1s into bulk C 1s.

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  • 36.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Kammlander, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden..
    Riva, Stefania
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cappel, Ute B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden.;Uppsala Univ, Dept Phys & Astron, Wallenberg Initiat Mat Sci Sustainabil, S-75120 Uppsala, Sweden..
    Composition dependence of X-ray stability and degradation mechanisms at lead halide perovskite single crystal surfaces2024In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 2, p. 1000-1010Article in journal (Refereed)
    Abstract [en]

    The multiple applications of lead halide perovskite materials and the extensive use of X-ray based techniques to characterize them highlight a need to understand their stability under X-ray irradiation. Here, we present a study where the X-ray stability of five different lead halide perovskite compositions (MAPbI3, MAPbCl3, MAPbBr3, FAPbBr3, CsPbBr3) was investigated using photoelectron spectroscopy. To exclude effects of thin film formation on the observed degradation behaviors, we studied clean surfaces of single crystals. Different X-ray resistance and degradation mechanisms were observed depending on the crystal composition. Overall, perovskites based on the MA+ cation were found to be less stable than those based on FA+ or Cs+. Metallic lead formed most easily in the chloride perovskite, followed by bromide, and only very little metallic lead formation was observed for MAPbI3. MAPbI3 showed one main degradation process, which was the radiolysis of MAI. Multiple simultaneous degradation processes were identified for the bromide compositions. These processes include ion migration towards the perovskite surface and the formation of volatile and solid products in addition to metallic lead. Lastly, CsBr formed as a solid degradation product on the surface of CsPbBr3.

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  • 37.
    Garcia-Fernandez, Alberto
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Sterling, Cody M.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Gangan, Abhijeet
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Erbing, Axel
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Kamal, Chinnathambi
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden.;Raja Ramanna Ctr Adv Technol, Theory & Simulat Lab, HRDS, Indore 452013, Madhya Pradesh, India.;Homi Bhabha Natl Inst, Training Sch Complex, Mumbai 400094, Maharashtra, India..
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Kammlander, Birgit
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, S-10691 Stockholm, Sweden..
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces2022In: Small : nano micro, Vol. 18, no 13, article id 2106450Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI(3) and Cs(x)FA(1-x)PbI(3)) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI(3) and assign these to MA(+) ions in an MAI-terminated surface and to MA(+) ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2-terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.

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  • 38.
    García Fernández, Alberto
    et al.
    Kungliga Tekniska Högskolan.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Cody, M Sterling
    Stockholms Universitet.
    Gangan, Abhijeet
    Stockholm University.
    Erbing, Axel
    Stockholm University.
    Kamal, Chinnathambi
    Stockholms Universitet.
    Sloboda, Tamara
    Kungliga Tekniska Högskolan.
    Kammlander, Birgit
    Kungliga Tekniska Högskolan.
    Man, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Odelius, Michael
    Stockholms Universitet.
    Cappel, Ute B
    Kungliga Tekniska Högskolan.
    Experimental and theoretical core level and valence band analysis of clean perovskite single crystal surfaceIn: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095Article in journal (Other academic)
  • 39. Gorgoi, M
    et al.
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Schaefers, F
    Öhrwall, G
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Mertin, M
    Bressler, P
    Karis, O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Siegbahn, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Sandell, A
    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.
    Doherty, W
    Jung, C
    Braun, W
    Eberhardt, W
    The high kinetic energy photoelectron spectroscopy facility at BESSY progress and first results2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 601, no 1-2, p. 48-53Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectroscopy at high kinetic energy is a research field that receives an increasing interest due to the possibility of studying bulk properties of materials and deeply buried interfaces. Recently the high kinetic energy electron (HIKE) spectroscopy facility at BESSY in Berlin has become operative at the bending magnet beamline KMC-1. The first results show very good performance. Electron spectra have been recorded using X-ray energies from 2 keV up to 12 keV. Using back-scattering conditions in the crystal monochromator, very high-resolution has been achieved for photon energies around 2, 6 and 8 keV. In the latter case, spectra with a resolving power from the monochromator of >= 80 000 have been achieved and it has been possible to perform electron spectroscopy with resolving power of >= 60 000, yielding a total instrument resolution of about 150 meV as determined directly from spectra. This paper describes the facility and reports some of the first results. (C) 2009 Elsevier B.V. All rights reserved.

  • 40.
    Hagfeldt, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Didriksson, B
    Lindström, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Södergren, Sven
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Rensmo, Håkan
    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.
    Lindquist, Sten-Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Verification of High Efficiencies for the Grätzel Cell: A 7% Efficient Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films.1994In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 31, no 481Article in journal (Other (popular science, discussion, etc.))
  • 41.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Johansson, Erik M J
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Odelius, Michael
    Hagberg, P
    Sun, Licheng
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Electronic and molecular structures of organic dye/TiO2 interfaces for solar cell applications: a core level photoelectron spectroscopy study2010In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 12, no 7, p. 1507-1517Article in journal (Refereed)
    Abstract [en]

    The electronic and molecular properties of three organic dye molecules with the general structure donor-linker-anchor have been investigated using core level photoelectron spectroscopy (PES). The molecules contain a diphenylaniline donor unit, a thiophene linker unit, and cyanoacrylic acid or rhodanine-3-acetic acid anchor units. They have been investigated both in the form of a multilayer and adsorbed onto nanoporous TiO2 and the experimental results were also compared with DFT calculations. The changes at the dye-sensitized TiO2 surface due to the modification of either the donor unit or the anchor unit was investigated and the results showed important differences in coverage as well as in electronic and molecular surface properties. By measuring the core level binding energies, the sub-molecular properties were characterized and the result showed that the adsorption to the TiO2 influences the energy levels of the sub-molecular units differently.

  • 42.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Johansson, Erik M. J.
    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.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Influence of Water on the Electronic: and Molecular Surface Structures of Ru-Dyes at Nanostructured TiO22011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 24, p. 11996-12004Article in journal (Refereed)
    Abstract [en]

    The influence of water on the surface electronic and molecular properties of three Ru-dyes adsorbed at nanostructured TiO2 was investigated using photoelectron spectroscopy (PES). The dyes investigated were the Ru(dcbpy)(2)(NCS)(2) in its acid (N3) and in its 2-fold deprotonated form (N719) as well as a similar dye (Z-907) containing the hydrophobic ligand 4,4'-dinonyl-2,2'-bipyridine. Trends in surface structures depending on water exposure were followed for the three dyes. The results showed that the hydrophobic chains of the Z-907 dye effectively inhibit surface reorganization while large changes in surface electronic and molecular structure were observed for the N3 and N719 molecular layers. Specifically, large effects involving the thiocyanate ligands were detected, and the S2p and N Is core level spectra indicate that the changes involve mixing of only two dominating surface configurations. Moreover, the PES results also showed water-induced changes in the energy level matching between the dye and the TiO2, and water induced desorption of the TBA(+) counterion. Basic photoelectrochemical trends depending on water exposure to dye-sensitized solar cell systems were also verified.

  • 43.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Johansson, Erik M J
    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.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    The Influence of Water on the Electronic and Molecular Surface Structures of Ru-dyes at Nanostructured TiO2In: Article in journal (Other academic)
    Abstract [en]

    The influence of water on the surface electronic and molecular properties of three Ru-dyes adsorbed at nanostructured TiO2 was investigated using photoelectron spectroscopy (PES). The dyes investigated were the Ru(dcbpy)2 (NCS)2 in its acid (N3) and in its 2-fold deprotonated form (N719) as well as a similar dye (Z-907) containing the hydrophobic ligand 4,4-dinonyl-2,2-bipyridine. Trends in surface structures depending on water exposure were followed for the three dyes. The results showed that the hydrophobic chains of the Z-907 dye effectively inhibit surface reorganization while large changes in surface electronic and molecular structure was observed for the N3 and N719 molecular layers. Specifically, large effects involving the thiocyanate ligands were detected and the S2p and N1s core level spectra indicate that the changes involve mixing of only two dominating surface configurations. Moreover, the PES results also showed water induced changes in the energy level matching between the dye and the TiO2, and water induced desorption of the TBA+ counter ion. Basic photoelectrochemical trends depending on water exposure to dye sensitized solar cell systems were also verified.

  • 44.
    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.

  • 45.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Odelius, Michael
    Magnuson, Martin
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Hagberg, Daniel
    Sun, Licheng
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Mapping the frontier electronic structures of triphenylamine based organic 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 structure 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 N1s 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 is also results indicating femtosecond charge redistribution at the dye/TiO2 interface.

  • 46.
    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.

  • 47.
    Henningsson, A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rensmo, H
    Sandell, A
    Siegbahn, H
    Södergren, S
    Insertion of H+, Li+, Na+ and K+ into thin films of silicotungstic acid studied by means of photoelectron spectroscopyManuscript (Other academic)
  • 48.
    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)
  • 49.
    Henningsson, A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rensmo, Håkan
    Sandell, A
    Siegbahn, H
    Södergren, S
    Lindström, H
    Hagfeldt, Anders
    TiO2 (anatase) and electrochemically Li-inserted TiO2 studied with photoelectron (PES, RPES)- and x-ray absorption (XAS) spectroscopyIn: Article in journal (Refereed)
  • 50.
    Henningsson, A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sandell, A
    Rensmo, Håkan
    Siegbahn, H
    Södergren, S
    Stashans, A
    Lunell, S
    Vayssieres, L
    Lindström, H
    Hagfeldt, Anders
    Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semiempirical calculationsIn: Article in journal (Refereed)
12345 1 - 50 of 220
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