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  • 1.
    Almquist, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Mattsson, Ken
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    High-fidelity numerical solution of the time-dependent Dirac equation2014Inngår i: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 262, s. 86-103Artikkel i tidsskrift (Fagfellevurdert)
  • 2.
    Almquist, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Mattsson, Ken
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Numerisk analys.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Stable and accurate simulation of phenomena in relativistic quantum mechanics2013Inngår i: Proc. 11th International Conference on Mathematical and Numerical Aspects of Waves, Tunisia: ENIT , 2013, s. 213-214Konferansepaper (Annet vitenskapelig)
  • 3.
    Amft, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Skorodumova, Natalia V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Thermally Excited Vibrations in Copper, Silver, and Gold Trimers and Enhanced Binding of CO2010Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Artikkel i tidsskrift (Annet vitenskapelig)
  • 4.
    Anaraki, Elham Halvani
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran.
    Kermanpur, Ahmad
    Isfahan Univ Technol, Dept Mat Engn, Esfahan 8415683111, Iran.
    Mayer, Matthew T.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland;Helmholtz Zentrum Berlin, Young Investigator Grp Electrochem Convers CO2, Hahn Meitner Pl 1, D-14109 Berlin, Germany.
    Steier, Ludmilla
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland;Imperial Coll London, Dept Chem, London SW7 2AZ, England.
    Ahmed, Taha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Turren-Cruz, Silver-Hamill
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Seo, Jiyoun
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Luo, Jingshan
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Zakeeruddin, Shaik Mohammad
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Tress, Wolfgang Richard
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland.
    Correa-Baena, Juan-Pablo
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland;MIT, Dept Mech Engn, 77 Massachusetts Ave, Cambridge, MA 02139 USA.
    Low-Temperature Nb-Doped SnO2 Electron-Selective Contact Yields over 20% Efficiency in Planar Perovskite Solar Cells2018Inngår i: ACS Energy Letters, ISSN 2380-8195, Vol. 3, nr 4, s. 773-778Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low-temperature planar organic inorganic lead halide perovskite solar cells have been at the center of attraction as power conversion efficiencies go beyond 20%. Here, we investigate Nb doping of SnO2 deposited by a low-cost, scalable chemical bath deposition (CBD) method. We study the effects of doping on compositional, structural, morphological, and device performance when these layers are employed as electron-selective layers (ESLs) in planar-structured PSCs. We use doping concentrations of 0, 1, 5, and 10 mol % Nb to Sn in solution. The ESLs were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and ultraviolet visible spectroscopy. ESLs with an optimum 5 mol % Nb doping yielded, on average, an improvement of all the device photovoltaic parameters with a champion power conversion efficiency of 20.5% (20.1% stabilized).

  • 5.
    Ardo, Shane
    et al.
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA;Univ Calif Irvine, Dept Chem Engn & Mat Sci, Irvine, CA 92697 USA;US DOE, Off Energy Efficiency & Renewable Energy EERE, Fuel Cell Technol Off, EE-3F,1000 Independence Ave SW, Washington, DC 20585 USA.
    Rivas, David Fernandez
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Modestino, Miguel A.
    NYU, Dept Chem & Biomol Engn, Brooklyn, NY 11201 USA.
    Greiving, Verena Schulze
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Abdi, Fatwa F.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Llado, Esther Alarcon
    Amolf Inst, Ctr Nanophoton, Amsterdam, Netherlands.
    Artero, Vincent
    Univ Grenoble Alpes, CNRS, CEA, Lab Chim & Biol Metaux, Grenoble, France.
    Ayers, Katherine
    Proton OnSite, Wallingford, CT 06492 USA.
    Battaglia, Corsin
    Empa, Swiss Fed Labs Mat Sci & Technol, Dubendorf, Switzerland.
    Becker, Jan-Philipp
    Forschungszentrum Julich, IEK Photovolta 5, Julich, Germany.
    Bederak, Dmytro
    Univ Groningen, Zernike Inst Adv Mat, Nijenborgh 4, NL-9747 AG Groningen, Netherlands.
    Berger, Alan
    Air Prod & Chem Inc, Allentown, PA 18195 USA.
    Buda, Francesco
    Leiden Univ, Leiden Inst Chem, Leiden, Netherlands.
    Chinello, Enrico
    Ecole Polytech Fed Lausanne, LAPD, Lausanne, Switzerland.
    Dam, Bernard
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Di Palma, Valerio
    Eindhoven Univ Technol, Dept Appl Phys, Eindhoven, Netherlands.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fujii, Katsushi
    Univ Kitakyushu, Inst Environm Sci & Technol, Wakamatsu Ku, Kitakyushu, Fukuoka, Japan.
    Gardeniers, Han
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Geerlings, Hans
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Hashemi, S. Mohammad H.
    Ecole Polytech Fed Lausanne, Opt Lab LO, Lausanne, Switzerland.
    Haussener, Sophia
    Ecole Polytech Fed Lausanne, LRESE, Lausanne, Switzerland.
    Houle, Frances
    Lawrence Berkeley Natl Lab, Joint Ctr Artificial Photosynthesis & Chem Sci Di, Berkeley, CA 94720 USA.
    Huskens, Jurriaan
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    James, Brian D.
    Strateg Anal Inc, Arlington, VA 22203 USA.
    Konrad, Kornelia
    Univ Twente, Dept Sci Technol & Policy Studies, Enschede, Netherlands.
    Kudo, Akihiko
    Tokyo Univ Sci, Fac Sci, Dept Appl Chem, Tokyo 1628601, Japan.
    Kunturu, Pramod Patil
    Univ Twente, MESA Inst Nanotechnol, Mol Nanofabricat Grp, Enschede, Netherlands.
    Lohse, Detlef
    Univ Twente, MESA Inst Nanotechnol, Phys Fluids Grp, Enschede, Netherlands.
    Mei, Bastian
    Univ Twente, MESA Inst Nanotechnol, Photocatalyt Synth Grp, Enschede, Netherlands.
    Miller, Eric L.
    Moore, Gary F.
    Arizona State Univ, Sch Mol Sci, Biodesign Ctr Appl Struct Discovery CASD, Tempe, AZ 85287 USA.
    Muller, Jiri
    Inst Energiteknikk, Kjeller, Norway.
    Orchard, Katherine L.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Rosser, Timothy E.
    Univ Cambridge, Dept Chem, Cambridge, England.
    Saadi, Fadl H.
    CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA.
    Schuttauf, Jan-Willem
    Swiss Ctr Elect & Microtechnol CSEM, PV Ctr, Neuchatel, Switzerland.
    Seger, Brian
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Sheehan, Stafford W.
    Catalyt Innovat, Fall River, MA 02723 USA.
    Smith, Wilson A.
    Delft Univ Technol, MECS, Dept Chem Engn, Maasweg 9, NL-2629 HZ Delft, Netherlands.
    Spurgeon, Joshua
    Univ Louisville, Conn Ctr Renewable Energy Res, Louisville, KY 40292 USA.
    Tang, Maureen H.
    Drexel Univ, Chem & Biol Engn, Philadelphia, PA 19104 USA.
    van de Krol, Roel
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Solar Fuels, Berlin, Germany.
    Vesborg, Peter C. K.
    Tech Univ Denmark DTU, Dept Phys, Lyngby, Denmark.
    Westerik, Pieter
    Univ Twente, MESA Inst Nanotechnol, Mesoscale Chem Syst Grp, Enschede, Netherlands.
    Pathways to electrochemical solar-hydrogen technologies2018Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 11, nr 10, s. 2768-2783Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/ or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.

  • 6. Arteca, G A
    et al.
    Edvinsson, T
    Elvingson, C
    Compaction of grafted wormlike chains under variable confinement2001Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 3, nr 17, s. 3737-3741Artikkel i tidsskrift (Fagfellevurdert)
  • 7.
    Arteca, GA
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Edvinsson, T
    Elvingson, C
    Compaction of grafted wormlike chains under variable confinement2001Inngår i: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, ISSN 1463-9076, Vol. 3, nr 17, s. 3737-3741Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the mean molecular shape features for a model of wormlike chains with variable persistence length and nonbonded pair interactions. The chains are modelled as end-grafted and confined within an infinite slab with variable thickness. By using two i

  • 8. Boschloo, G.
    et al.
    Marinado, T.
    Nonomura, K.
    Edvinsson, T.
    Agrios, A. G.
    Hagberg, D. P.
    Sun, L.
    Quintana, M.
    Karthikeyan, C. S.
    Thelakkat, M.
    Hagfeldt, A.
    A comparative study of a polyene-diphenylaniline dye and Ru(dcbpy)(2)(NCS)(2) in electrolyte-based and solid-state dye-sensitized solar cells2008Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 20, s. 7214-7217Artikkel i tidsskrift (Fagfellevurdert)
  • 9. Boschloo, Gerrit
    et al.
    Edvinsson, Tomas
    Hagfeldt, Anders
    Dye-sensitized nanostructured ZnO Electrodes for solar cell applications2007Inngår i: Nanostructured materials for solar energy conversion / [ed] Tetsuo Soga, Amsterdam: Elsevier Science , 2007Kapittel i bok, del av antologi (Fagfellevurdert)
  • 10.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    A concentrated effort2019Inngår i: NATURE ENERGY, ISSN 2058-7546, Vol. 4, nr 5, s. 354-355Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    While recent gains in the efficiency of photoelectrochemical devices for hydrogen production are encouraging, high efficiency is rarely combined with high power output, which is important for large-scale viability. Towards this goal, researchers now demonstrate a promising thermally integrated device driven by concentrated solar irradiation.

  • 11.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    On the Size and Shape of Polymers and Polymer Complexes: A Computational and Light Scattering Study2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Detailed characterization of size and shape of polymers, and development of methods to elucidate the mechanisms behind shape transitions are central issues in this thesis. In particular we characterize grafted polymer chains under confinement in terms of the chain entanglement complexity and mean molecular size. Confinement of polymers into small regions can drastically affect the structural and mechanical properties, and make these systems convenient for a large number of applications, including the design of lubricants, coatings, and various biotechnical applications.

    Using Monte Carlo simulations with a model including both persistence length and intramolecular non-bonded interaction, we find two regimes of polymer behaviour: i) soft mushrooms, where confinement successively flattens the chains with accompanying change in the folding complexity, and ii) hard mushrooms where the compact structures appear to resist confinement and the only way to reorganize the entanglements is by flattening under strong confinement. We also show that a simultaneous use of mean molecular size and chain entanglement complexity renders the possibility to create configurational "phase" diagrams for a wide range of polymers. We have further introduced a new descriptor of folding complexity, the path-space ratio, ζα which captures essential features of molecular shape beyond those conveyed by mean size and asphericity.

    This thesis also contains results of light scattering measurements on supramolecular complexes formed when mixing an adamantane end-capped star polymer with a β-cyclodextrin polymer. The specific interactions result in an interplay between the association of the end-caps and a strong inclusion interaction between adamantane and β-cyclodextrin.

  • 12. Edvinsson, Tomas
    Optical Quantum Confinement and Photocatalysis2014Konferansepaper (Annet vitenskapelig)
  • 13.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical quantum confinement and photocatalytic properties in two-, one- and zero-dimensional nanostructures2018Inngår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 5, nr 9, artikkel-id 180387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low-dimensional nanomaterials have been explored extensively in the last decades, partly fuelled by the new possibilities for tuning and controlling their electronic properties. In a broader perspective within catalysis, two-, one- and zero-dimensional (2D, 1D and 0D) inorganic nanomaterials represent a bridge between the selectivity of molecular catalysts and the high performance and stability of inorganic catalysts. As a consequence of the low dimensions, higher surface areas are obtained but also introduce new physics and increased tuneability of the electronic states in the nanostructured system. Herein, we derive the commonly used equations for optical transitions and carrier confinement in semiconductors and discuss their effect on the optical and photocatalytic properties of direct band and indirect band gap materials. In particular, the physical properties of the optical and photocatalytic properties of Fe2O3 and ZnO will be used to exemplify the effects of the low dimensionality. Carrier confinement effects with changes in the density of states, band gap/shift of band edges will be outlined together with their effects on the tuneability of the material and their wider application as photocatalytic materials.

  • 14.
    Edvinsson, Tomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Arteca, Gustavo A.
    Elvingson, Christer
    Path-Space Ratio as a Molecular Shape Descriptor of Polymer Conformation2003Inngår i: Journal of Chemical Information and Computer Science, Vol. 43, s. 126-133Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Edvinsson, Tomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I.
    Elvingson, Christer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi I.
    Arteca, Gustavo
    Effect of compression on the molecular shape of polymer mushrooms with variable stiffness2002Inngår i: Journal of chemical physics, Vol. 116, s. 9510-Artikkel i tidsskrift (Fagfellevurdert)
  • 16.
    Edvinsson, Tomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Elvingson, Christer
    Gustavo, Arteca
    Variations in molecular compactness and chain entanglement during the compression of grafted polymers2000Inngår i: MACROMOLECULAR THEORY AND SIMULATIONS, ISSN 1022-1344, Vol. 9, nr 7, s. 398-406Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Characterizing the effect of geometrical confinement on mean polymer shape is an important step towards understanding and controlling molecular behaviour at interfaces. In this work, we study the configurational transitions and molecular shape changes tha

  • 17. Edvinsson, Tomas
    et al.
    Li, Chen
    Pschirer, Neil
    Schoeneboom, Jan
    Eickemeyer, Felix
    Sens, Ruediger
    Boschloo, Gerrit
    Herrmann, Andreas
    Muellen, Klaus
    Hagfeldt, Anders
    Intramolecular charge-transfer tuning of perylenes: Spectroscopic features and performance in Dye-sensitized solar cells2007Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, nr 42, s. 15137-15140Artikkel i tidsskrift (Fagfellevurdert)
  • 18.
    Edvinsson, Tomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Pschirer, Niel
    Schöneboom, Jan
    Eickemeyer, Felix
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    Photoinduced electron transfer from a terrylene dye to TiO2: Quantification of band edge shift effects2009Inngår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 357, nr 1-3, s. 124-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A terrylene chromophore exhibiting a high extinction coefficient has been developed as a sensitizer for photovoltaic applications. The photophysical and photochemical properties of the dye were analyzed both experimentally and theoretically. Terrylene-sensitized nanocrystalline TiO2 solar cells yielded good photocurrents providing more than 60% in external quantum efficiency. The photoinduced electron transfer from the dye to TiO2 was found to be very sensitive to conduction band edge shifts in TiO2 induced, either by changes in the composition of the redox electrolyte or by UV-illumination. This sensitivity was observed in quantum efficiencies for photocurrent generation of terrylene-sensitized solar cells and in photoinduced absorption experiments. The conduction band shifts were quantified using charge extraction methods. The observed sensitivity of the injection efficiency suggests that photoinduced electron transfer occurs from the relaxed excited state, possibly due to poor electronic coupling between TMIMA excited states and TiO2 conduction band states.

  • 19.
    Edvinsson, Tomas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Råsmark, Per Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Elvingson, Christer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Cluster identification and percolation analysis using a recursive algorithm1999Inngår i: Molecular Simulation, ISSN 0892-7022, E-ISSN 1029-0435, Vol. 23, nr 3, s. 169-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A recursive algorithm for sampling properties of physical clusters such as size distribution andpercolation is presented. The approach can be applied to any system with periodic boundaryconditions, given a spatial definition of a cluster. We also introduce some modifications in thealgorithm that increases the efficiency considerably if one is only interested in percolationanalysis. The algorithm is implemented in Fortran 90 and is compared with a number ofiterative algorithms. The recursive cluster identification algorithm is somewhat slower than theiterative methods at low volume fraction but is at least as fast at high densities. The percolationanalysis, however, is considerably faster using recursion, for all systems studied. We also notethat the CPU time using recursion is independent on the static allocation of arrays, whereas theiterative method strongly depends on the size of the initially allocated arrays.

  • 20.
    Ferdowsi, Parnian
    et al.
    Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran.;Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Saygili, Yasemin
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Zhang, Weiwei
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kavan, Ladislav
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland.;J Heyrovsky Inst Phys Chem, Prague 1823, Czech Republic..
    Mokhtari, Javad
    Univ Guilan, Fac Engn, Dept Text Engn, Rasht 416353756, Iran..
    Zakeeruddin, Shaik M.
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Grätzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photon & Interfaces, Dept Chem, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci Engn, Lab Photomol Sci, Dept Chem, CH-1015 Lausanne, Switzerland..
    Molecular Design of Efficient Organic D-A-pi-A Dye Featuring Triphenylamine as Donor Fragment for Application in Dye-Sensitized Solar Cells2018Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, nr 2, s. 494-502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A metal-free organic sensitizer, suitable for the application in dye-sensitized solar cells (DSSCs), has been designed, synthesized and characterized both experimentally and theoretically. The structure of the novel donor-acceptor--bridge-acceptor (D-A-pi-A) dye incorporates a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid (BTEBA). The triphenylamine unit is widely used as an electron donor for photosensitizers, owing to its nonplanar molecular configuration and excellent electron-donating capability, whereas 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid is used as an electron acceptor unit. The influences of I-3(-)/I-, [Co(bpy)(3)](3+/2+) and [Cu(tmby)(2)](2+/+) (tmby=4,4,6,6-tetramethyl-2,2-bipyridine) as redox electrolytes on the DSSC device performance were also investigated. The maximal monochromatic incident photon-to-current conversion efficiency (IPCE) reached 81% and the solar light to electrical energy conversion efficiency of devices with [Cu(tmby)(2)](2+/+) reached 7.15%. The devices with [Co(bpy)(3)](3+/2+) and I-3(-)/I- electrolytes gave efficiencies of 5.22% and 6.14%, respectively. The lowest device performance with a [Co(bpy)(3)](3+/2+)-based electrolyte is attributed to increased charge recombination.

  • 21.
    Fondell, Mattis
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Jacobsson, Jesper T.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Boman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Optical quantum confinement in low dimensional hematite2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 10, s. 3352-3363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hematite is considered to be a promising material for various applications, including for example photoelectrochemical cells for solar hydrogen production. Due to limitations in the charge transport properties hematite needs to be in the form of low-dimensional particles or thin films in several of these applications. This may however affect the optical properties, introducing additional complications for efficient design of photo-active devices. In this paper the optical absorption is analyzed in detail as a function of film thickness for 35 thin films of hematite ranging between 2 and 70 nm. Hematite was deposited by atomic layer deposition on FTO-substrates using Fe(CO)(5) and O-2 as precursors. It was found that for film thicknesses below 20 nm the optical properties are severely affected as a consequence of quantum confinement. One of the more marked effects is a blue shift of up to 0.3 eV for thinner films of both the indirect and direct transitions, as well as a 0.2 eV shift of the absorption maximum. The data show a difference in quantum confinement for the indirect and the direct transitions, where the probability for the indirect transition decreases markedly and essentially disappears for the thinnest films. Raman measurements showed no peak shift or change in relative intensity for vibrations for the thinnest films indicating that the decrease in indirect transition probability could not be assigned to depression of any specific phonon but instead seems to be a consequence of isotropic phonon confinement. The onset of the indirect transition is found at 1.75 eV for the thickest films and shifted to 2.0 eV for the thinner films. Two direct transitions are found at 2.15 eV and 2.45 eV, which are blue shifted 0.3 and 0.45 eV respectively, when decreasing the film thickness from 20 to 4 nm. Low dimensional hematite, with dimensions small enough for efficient charge transport, thus has a substantially lower absorption in the visible region than expected from bulk values. This knowledge of the intrinsic optical behavior of low dimensional hematite will be of importance in the design of efficient photo-active devices.

  • 22.
    Grånäs, Oscar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Timneanu, Nicusor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Eliah Dawod, Ibrahim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Ragazzon, Davide
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Trygg, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Souvatzis, Petros
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Caleman, C
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Femtosecond bond breaking and charge dynamics in ultracharged amino acids2019Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 151, nr 14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Historically, structure determination of nanocrystals, proteins, and macromolecules required the growth of high-quality crystals sufficiently large to diffract X-rays efficiently while withstanding radiation damage. The development of the X-ray free-electron laser has opened the path toward high resolution single particle imaging, and the extreme intensity of the X-rays ensures that enough diffraction statistics are collected before the sample is destroyed by radiation damage. Still, recovery of the structure is a challenge, in part due to the partial fragmentation of the sample during the diffraction event. In this study, we use first-principles based methods to study the impact of radiation induced ionization of six amino acids on the reconstruction process. In particular, we study the fragmentation and charge rearrangement to elucidate the time scales involved and the characteristic fragments occurring.

  • 23. Hagberg, Daniel P.
    et al.
    Edvinsson, Tomas
    Marinado, Tannia
    Boschloo, Gerrit
    Hagfeldt, Anders
    Sun, Licheng
    A novel organic chromophore for dye-sensitized nanostructured solar cells2006Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 21, s. 2245-2247Artikkel i tidsskrift (Fagfellevurdert)
  • 24.
    Imani, Roghayeh
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;Univ Ljubljana, Fac Elect Engn, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Dillert, Ralf
    Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;Leibniz Univ Hannover, Lab Nano & Quantum Engn, Schneiderberg 39, D-30167 Hannover, Germany..
    Bahnemann, Detlef W.
    Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;St Petersburg State Univ, Lab Photoact Nanocomposite Mat, St Petersburg 198504, Russia..
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Apih, Tomaz
    Jozef Stefan Inst, Jamova 39, SI-1000 Ljubljana, Slovenia..
    Kononenko, Veno
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Repar, Neza
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Kralj-Iglic, Veronika
    Univ Ljubljana, Fac Hlth Sci, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Drobne, Damjana
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Iglic, Ales
    Univ Ljubljana, Fac Elect Engn, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Multifunctional Gadolinium-Doped Mesoporous TiO2 Nanobeads: Photoluminescence, Enhanced Spin Relaxation, and Reactive Oxygen Species Photogeneration, Beneficial for Cancer Diagnosis and Treatment2017Inngår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 13, nr 20, artikkel-id 1700349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Materials with controllable multifunctional abilities for optical imaging (OI) and magnetic resonant imaging (MRI) that also can be used in photodynamic therapy are very interesting for future applications. Mesoporous TiO2 sub-micrometer particles are doped with gadolinium to improve photoluminescence functionality and spin relaxation for MRI, with the added benefit of enhanced generation of reactive oxygen species (ROS). The Gd-doped TiO2 exhibits red emission at 637 nm that is beneficial for OI and significantly improves MRI relaxation times, with a beneficial decrease in spin-lattice and spin-spin relaxation times. Density functional theory calculations show that Gd3+ ions introduce impurity energy levels inside the bandgap of anatase TiO2, and also create dipoles that are beneficial for charge separation and decreased electron-hole recombination in the doped lattice. The Gd-doped TiO2 nanobeads (NBs) show enhanced ability for ROS monitored via center dot OH radical photogeneration, in comparison with undoped TiO2 nanobeads and TiO2 P25, for Gd-doping up to 10%. Cellular internalization and biocompatibility of TiO2@xGd NBs are tested in vitro on MG-63 human osteosarcoma cells, showing full biocompatibility. After photoactivation of the particles, anticancer trace by means of ROS photogeneration is observed just after 3 min irradiation.

  • 25.
    Imani, Roghayeh
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Qiu, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fernandes, Daniel L. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Mitev, Pavlin D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Unravelling in-situ formation of highly active mixed metal oxide CuInO2 nanoparticles during CO2 electroreduction2018Inngår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 49, s. 40-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Technologies and catalysts for converting carbon dioxide (CO2) to immobile products are of high interest to minimize greenhouse effects. Copper(I) is a promising catalytic active state of copper but hampered by the inherent instability in comparison to copper(II) or copper(0). Here, we report a stabilization of the catalytic active state of copper(I) by the formation of a mixed metal oxide CuInO2 nanoparticle during the CO2 electroreduction. Our result shows the incorporation of nanoporous Sn:In2O3 interlayer to Cu2O pre-catalyst system lead to the formation of CuInO2 nanoparticles with remarkably higher activity for CO2 electroreduction at lower overpotential in comparison to the conventional Cu nanoparticles derived from sole Cu2O. Operando Raman spectroelectrochemistry is employed to in-situ monitor the process of nanoparticles formation during the electrocatalytic process. The experimental data are collaborated with DFT calculations to provide insight into the electro-formation of the type of Cu-based mixed metal oxide catalyst during the CO2 electroreduction, where a formation mechanism via copper ion diffusion across the substrate is suggested.

  • 26.
    Jacobsson, Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Antireflective coatings of ZnO quantum dots and their photocatalytic activity2012Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 2, nr 27, s. 10298-10305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films of ZnO quantum dots of different sizes have been deposited on conducting glass substrates. The films are transparent and work as antireflective coatings in the visible region. The negative absorption reaches down to -0.25 which represent a 77% increase in the transmitted light. Over a large part of the visible spectrum the increased transmittance is over 25%, and we demonstrate this to be a thin film effect. Under simulated solar illumination these films show a relatively high photocatalytic activity towards decomposition of methylene blue. The rate of photodecomposition depends on particle size and the smallest particles, which are less than 4 nm in diameter, show the highest quantum efficiency. We find the overall efficiency to be in the same order of magnitude to what's reported for commercial photocatalytic products like Degussa P25 and Pilkinton Active™, and maybe even somewhat better. We also demonstrate an increased hydrophilicity for the films under UV radiation. The photocatalytic oxidation of water into oxygen as a function of applied bias was measured in a three electrode system. The overall efficiency is small due to the high band gap but the internal quantum efficiency reaches over 10%.

  • 27. Jacobsson, Jesper
    et al.
    Edvinsson, Tomas
    Photoelectrochemical determination of the band edge positions as a function of particle size for ZnO quantum dots2012Konferansepaper (Annet vitenskapelig)
  • 28. Jacobsson, Jesper
    et al.
    Edvinsson, Tomas
    Potential dependent absorption in ZnO quantum dots and determination of band edges as a function of particle size2011Konferansepaper (Annet vitenskapelig)
  • 29.
    Jacobsson, Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Quantum Confined Stark Effects in ZnO Quantum Dots Investigated with Photoelectrochemical Methods2014Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, nr 22, s. 12061-12072Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical absorption behavior of ZnO quantum dots has been investigated as a function of particle size in the quantum confined regime, between 4 and 9 nm in diameter, by using photoelectrochemical methods. Thin films of quantum dots, with 18 different sizes, were prepared on conducting substrates where the Fermi level could be controlled potentiostatically simultaneously as absorption measurements were performed. While raising the Fermi level into the conduction band, the dominant effect is a decrease in absorption as a consequence of increased electron population in the conduction band. This is a potentiostatic analogue to the Burstein-Moss shift for degenerate semiconductors. For applied potentials in an interval of 0.2 eV below the conduction band edge, the absorption does, however, increases instead of decreases. This absorption increase was found to be caused by a transition into states located within the band gap, which are introduced as a consequence of the applied potential. The magnitude of this effect is for the smallest particles (4 nm) approximately 9% compared to the magnitude of the Burstein-Moss bleaching. The effect decreases with increased particle size and essentially disappears for particles approaching 9 nm. The phenomenon is analyzed in terms of the Stark effect where the consequence of the applied potential is a buildup of an electric field within the particles, breaking the symmetry and splitting the energy levels in the conduction band. The gradual disappearance of the effect for the growing particles gives the extent of the quantum confinement effects of this phenomenon. The size-dependent absorption probability is analyzed and gives important information concerning the nature of both the perturbed states above the conduction band edge and the formation of the subband edge states.

  • 30. Jacobsson, Jesper
    et al.
    Edvinsson, Tomas
    Time resolved in situ UV-vis absorption spectroscopy on growing ZnO quantum dots: Correlation to steady state fluorescence and x-ray diffraction measurements2011Konferansepaper (Annet vitenskapelig)
  • 31. Jacobsson, Jesper
    et al.
    Edvinsson, Tomas
    Time resolved in situ UV-vis absorption spectroscopy on growing ZnO quantum dots in correlation to steady state fluorescence and x-ray diffraction measurements2011Konferansepaper (Annet vitenskapelig)
  • 32. Jacobsson, Jesper
    et al.
    Fjällström, Viktor
    Edoff, Marika
    Edvinsson, Tomas
    An efficient approach to solar water splitting based on CuInxGa1-xSe2 reaching 10% overall solar-to-hydrogen conversion efficiency2013Konferansepaper (Annet vitenskapelig)
  • 33. Jacobsson, Jesper
    et al.
    Fjällström, Viktor
    Sahlberg, Martin
    Edoff, Marika
    Edvinsson, Tomas
    A Monolithic Device for Solar Water Splitting Based on Series Interconnected CIGS-Cells Reaching Over 10 % Solar-to-Hydrogen Efficiency2013Konferansepaper (Annet vitenskapelig)
  • 34. Jacobsson, Jesper
    et al.
    Fjällström, Viktor
    Sahlberg, Martin
    Edoff, Marika
    Edvinsson, Tomas
    A Monolithic Device for Solar Water Splitting Based on Series Interconnected CIGS-Cells Reaching Over 10 % Solar-to-Hydrogen Efficiency2013Konferansepaper (Annet vitenskapelig)
  • 35. Jacobsson, Jesper
    et al.
    Fjällström, Viktor
    Sahlberg, Martin
    Edvinsson, Tomas
    A Monolithic Device for Solar Water Splitting Based on Series Interconnected CIGS-Cells Reaching Over 10 % Solar-to-Hydrogen Efficiency2013Konferansepaper (Annet vitenskapelig)
  • 36.
    Jacobsson, Jesper T.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Fjällström, Viktor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Sahlberg, Martin Häggblad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    A monolithic device for solar water splitting based on series interconnected thin film absorbers reaching over 10% solar-to-hydrogen efficiency2013Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 6, nr 12, s. 3676-3683Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Efficient production of hydrogen from solar energy is anticipated to be an important component in a future sustainable post-carbon energy system. Here we demonstrate that series interconnected absorbers in a PV-electrolysis configuration based on the compound semiconductor CIGS, CuInxGa1-xSe2, are a highly interesting concept for solar water splitting applications. The band gap energy of CIGS can be adjusted to a value close to optimum for efficient absorption of the solar spectrum, but is too low to drive overall water splitting. Therefore we connect three cells in series, into a monolithic device, which provides sufficient driving force for the full reaction. Integrated with a catalyst this forms a stable PV/photo-electrochemical device, which when immersed in water reaches over 10% solar-to-hydrogen efficiency for unassisted water splitting. The results show that series interconnected device concepts, which enable use of a substantial part of the solar spectrum, provide a simple route towards highly efficient water splitting and could be used also for other solar absorbers with similar electro-optical properties. We discuss how the efficiency could be increased for this particular device, as well as the general applicability of the concepts used in this work. We also briefly discuss advantages and disadvantages of photo-electrochemical cells in relation to PV-electrolysis with respect to our results.

  • 37.
    Jacobsson, Jesper T.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Platzer-Björkman, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    CuInxGa1-xSe2 as an efficient photocathode for solar hydrogen generation2013Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, nr 35, s. 15027-15035Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilizing the energy in the sun to efficiently split water into hydrogen and oxygen can have a huge beneficial impact on a future post-carbon energy system. There is still, however, some way to go before this concept will be fully competitive. At the heart of the problem is finding and designing materials that can drive the photoreaction in an efficient and stable way. In this work we demonstrate how CIGS (CuInxGa1-xSe2), can be used for photo reduction of water into hydrogen. CIGS, which is a proven good solar cell material, does not in itself have the appropriate energetics to drive the reaction to any larger extent. Here we show that by utilizing a solid state pn-junction for charge separation and a catalyst deposited on the surface, the efficiency is significantly improved and photocurrents of 6 mA/cm(2) are demonstrated for the reduction reaction in the configuration of a photo-electrochemical cell. The stability of CIGS in water under illumination turns out to be a problem. In our present set-up, we demonstrate that separation between the charge carrier generation, which takes place in the solar cell, from the catalysis, which takes place in the electrolyte leads to improved stability, while keeping the essential functions of the processes. By incorporating appropriate charge separation layers and optimizing the catalytic conditions at the surface of the electrodes, photocurrents in excess of 20 mA/cm2 are reached for the reduction half reaction, demonstrating how essentially the full potential of GIGS as an efficient absorber material can be utilized in photocatalytic reduction of water into hydrogen.

  • 38.
    Jacobsson, Jesper T
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Viarbitskaya, Sviatlana
    Mukhtar, Emad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    A size dependent discontinuous decay rate for the exciton emission in ZnO quantum dots2014Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 27, s. 13849-13857Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The time resolved UV-fluorescence in ZnO quantum dots has been investigated using femtosecond laser spectroscopy. The measurements were performed as a function of particle size for particles between 3 and 7 nm in diameter, which are in the quantum confined regime. A red shift in the fluorescence maximum is seen while increasing the particle size, which correlates with the shift in band gap due to quantum confinement. The energy difference between the UV-fluorescence and the band gap does, however, increase for the smaller particles. For 3.7 nm particles the fluorescence energy is 100 meV smaller than the band gap energy, whereas it is only 20 meV smaller for the largest particles. This indicates a stabilization of the excitons in the smallest particles. The lifetime of the UV fluorescence is in the picosecond time scale and interestingly, it is discontinuous with respect to particle size. For the smallest particles, the exciton emission life time reaches 30 ps, which is three times longer than that for the largest particles. This demonstrates a transition between two different mechanisms for the UV-fluorescence. We suggest that this is an effect of surface trapping and stabilization of the excitons occurring in the smallest particles but not in the larger ones. We also discuss the time scale limit for slowed hot carrier dynamics in ensembles of quantum confined ZnO particles.

  • 39.
    Jacobsson, Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Viktor, Fjällström
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Marika, Edoff
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Tomas, Edvinsson
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Sustainable Solar Hydrogen Production: From Photo-Electrochemical Cells to PV-Electrolysis and Back Again2014Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sustainable hydrogen production could, in principle, be accomplished along several different routes, where some of the most promising approaches involve utilization of solar energy. Photoelectrochemical cells (PEC-cells) and PV-electrolyzers for solar hydrogen production are here analyzed and compared. The analysis is performed by theoretically designing a number of intermediate devices, successively going from PEC-cells to PV-electrolyzers. The main physical processes: absorption, charge carrier separation, charge carrier transport, and catalysis are analyzed in the different devices. This demonstrates how the two concepts are related, and how one could easily be transformed and converted into the other. The awareness of the close relationship between PEC-cells and PV-electrolyzers is not as widely recognized as it should be. Traditionally, these two approaches have often been considered as fundamentally different, and are far too seldom analyzed in the same context. We argue that the different device designs for solar hydrogen production are best seen as essentially equivalent approaches, and as topological variations of the same basic theme, and can in many cases be unified under the acronym photo driven catalytic (PDC) devices. We further argue that much is to gain by acknowledging the similarities between PEC water splitting and PV-electrolysis, and that one concept alone should not be considered without also considering the other. The analysis and discussion presented could potentially lead to an increased fruitful crossbreeding of the accumulated knowledge in the respective sub-discipline, and aid in realizing solar hydrogen production as a sustainable and economically compatible energy alternative.

  • 40.
    Jacobsson, T. Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    A Spectroelectrochemical Method for Locating Fluorescence Trap States in Nanoparticles and Quantum Dots2013Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, nr 10, s. 5497-5504Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We here devise an electrochemical method for determining the absolute energetic position of trap levels involved in fluorescence. The method utilizes potentiostatic control of the Fermi level in the material, and thereby also the electronic population of the energy states involved in the fluorescence. The method is especially useful for nanoparticle semiconductor electrodes. Here we exemplify the method by determining the position of the trap levels involved in the green fluorescence in thin films of ZnO quantum dots. The exact mechanism and the absolute positions of these states have been debated in the literature. Here we show that the visible fluorescence is caused by a transition from energy levels slightly below the conduction band edge to a deep trap within the band gap. We further pinpoint the location of the upper trap level to be at 0.35 +/- 0.03 eV below the conduction band edge. Particles between 5 and 8 nm in diameter have been analyzed, which is in the quantum confined region of ZnO. We also show that the position of the upper trap level shifts with the size of the quantum dots in the same way as the conduction band.

  • 41.
    Jacobsson, T. Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Absorption and Fluorescence Spectroscopy of Growing ZnO Quantum Dots: Size and Band Gap Correlation and Evidence of Mobile Trap States2011Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, nr 19, s. 9578-9586Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ZnO nanoparticles constitute a convenient model system for fundamental studies with many possible technical applications in, for example, sensors and the field of catalysis and optoelectronics. A large set of ZnO quantum dots in the size range 2.5-7 nm have been synthesized and analyzed in detail. Time resolved in situ UV-vis absorption measurements were used to monitor the growth of these particles in solution by correlating the optical band gap to particle size given from X-ray diffraction (XRD) measurements. The particles formed were isotropic in shape, but small initial deviations gave indications of a transition from thermodynamic to kinetically controlled growth for particles around 4 nm in diameter. On the basis of this, the behavior and mechanisms for the particle growth are discussed. The fluorescence dependence on particle size was investigated by combining fluorescence and UV-vis measurements on growing particles. This revealed that the positions of the fluorescence trap states are mobile toward the conduction- and valence band. A broadening of the trap states was also found, and a surface dependent mechanism of the trap state shift and broadening is proposed.

  • 42.
    Jacobsson, T. Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Photoelectrochemical Determination of the Absolute Band Edge Positions as a Function of Particle Size for ZnO Quantum Dots2012Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, nr 29, s. 15692-15701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The absolute position of the conduction and the valence band edges of ZnO quantum dots (Qdots) has been determined as a function of particle size with potential dependent absorption spectroscopy. The absolute position of the band edges are vital for which catalytic reactions that can occur at the surface. They are also crucial parameters for charge injection and extraction in nanoparticular solar cells and other optoelectronic devices based on nanoparticles. The position of the conduction band edge was determined by potentiostatic population of the conduction band states and monitoring the resulting increase in the optical band gap. This was performed for ZnO particles in the quantum confined region with diameters ranging between 4 and 9 nm. The particles were deposited into thin films giving an ensemble of particles for which the analysis could be performed. The relevant equations were derived and their validity in terms of applied potential and kinetic considerations was quantified. We find that essentially all of the quantum size effect of increased band gap is occurring by a shift of the conduction band edge. The extent of the validity of the parabolic approximation, which is one of the assumptions in the analysis, is investigated, both experimentally and with density functional theory calculations of bulk ZnO Here, we find that the parabolic approximation only is valid in an energy range of slightly less than 0.1 eV from the conduction band edge but in that regime constitutes an excellent approximation. We also demonstrate that the validity of the parabolic approximation follows a rising Fermi level into the conduction band energy levels.

  • 43.
    Jacobsson, T. Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Fjällstrom, Viktor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    A theoretical analysis of optical absorption limits and performance of tandem devices and series interconnected architectures for solar hydrogen production2015Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 138, s. 86-95Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photo-driven catalytic (PDC) water splitting, using either photoelectrochemical cells (PEC-cells), PV-electrolyzers, or some hybrid system in-between, has attracted a lot of attention. In single-cell device architectures for solar hydrogen production, based on single band gap photoabsorbers, there is a fundamental efficiency problem originating from the energy distribution of the solar spectrum and the thermodynamic and kinetic requirements for splitting water. The minimum band gap for a single-junction device in order to withhold unbiased overall water splitting is considered to be at least 2.0 eV. This is far from the 1.35 eV which is the optimal band gap of a semiconductor for maximum power conversion of light in the solar spectrum. This discrepancy has been termed as the solar spectrum mismatch problem (the SSM-problem). The standard solution to this problem is to construct tandem devices, whereas an alternative is to interconnect several one band gap cells in series, side by side. Both approaches enable the use of low energy photons in the solar spectrum while still providing a sufficiently high photopotential for driving the full reaction, without seriously compromising with the area efficiency. In this paper, the tandem and serial architectures for handling the SSM-problem are analyzed and compared. The analysis is focused towards differences in the limits of optical absorption, the optimal number of optical. absorbers, and their corresponding band gaps. Taking losses due to charge carrier separation and catalysis into account, the maximum STH-efficiency for a series interconnected solar splitting device was found to be 24.6%, compared to 32.0% for an optimum tandem device at 1 Sun (air mass 1.5, 1000 W m(-2)). This can be compared with the maximum efficiency of 18.0% for an ideal single band gap photoabsorber in single junction device. The analysis shows that the maximum STH efficiency limits for series interconnected architectures for unassisted solar water splitting are not particularly far behind the more commonly studied tandem devices. They could then be an interesting alternative given the simplicity and versatility of series interconnected device architectures. The analysis also compares how tandem devices and series interconnected devices can differ in terms of charge carrier separation, charge carrier transport, catalysis, overall efficiency, device architecture, and expected cost.

  • 44.
    Jacobsson, T. Jesper
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Fjällstrom, Viktor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    CIGS based devices for solar hydrogen production spanning from PEC-cells to PV-electrolyzers: a comparison of efficiency, stability and device topology2015Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 134, s. 185-93Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Jacobsson, T. Jesper
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Goldschmidt's Rules and Strontium Replacement in Lead Halogen Perovskite Solar Cells: Theory and Preliminary Experiments on CH3NH3SrI32015Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, nr 46, s. 25673-25683Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the past few years, organic lead halogen perovskites have emerged as a class of highly promising solar cell materials, with certified solar cell efficiencies now surpassing 20%. Concerns have, however, been raised about the possible environmental and legalization problems associated with a new solar cell technology based on a water-soluble lead compound. Replacing lead in the perovskite structure: with a less toxic element, without degrading the favorable photo physical properties, would therefore be of interest. In this paper, the possibility of replacing lead with other metal ions is explored by following the replacement rules of Goldschmidt together with additional quantum mechanical considerations. This analysis provides a conceptual toolbox toward replacing lead, as well as additional insights into the photo physics of the metal halogen perovskites. This approach is exemplified by focusing on strontium in particular, which is nontoxic and relatively inexpensive. The ionic radius of Sr2+ and Pb2+ are almost identical, suggesting an exchange could be made without affecting the crystal structure. Couple cluster calculations on the metal ions and their halogen salts give the bonding patterns to be sufficiently similar and density functional theory (DFT) revealed the strontium perovskite, CH3NH3SrI3, to be a stable phase, despite the difference in electronegativity between lead and strontium. This is further supported by the existence of binary PM, and SrI2 compounds and the beneficial formation energy of the strontium perovskite. The electronic properties of both CH3NH3SrI3 and CH3NH3PbI3 were simulated and compared, revealing a higher degree of ionic interaction in the metal halogen bound in the strontium perovskite. This is a consequence of the lower electronegativity of strontium, which, together with the lack of d-orbitals in the Valence of Sr2+, results, in a higher band gap. The band gap for the strontium perovskite was estimated to 3.6 eV, which unfortunately is too high for an efficient photo absorber. Initial investigations on experimental synthesis of the strontium perovskite, using wet chemical methods, revealed it to be harder to produce than the lead perovskite This is explained as a:consequence of different bonding patterns in the metal iodine salts, which obstruct the methylammonium intercalation pathway utilized for forming the perovskite. Vapor phase methods are instead suggested as more promising synthesis routes.

  • 46.
    Jacobsson, T. Jesper
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Schwan, L. Josef
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ottosson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Determination of Thermal Expansion Coefficients and Locating the Temperature-Induced Phase Transition in Methylammonium Lead Perovskites Using X-ray Diffraction2015Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, nr 22, s. 10678-10685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lead halogen perovskites, and particularly methylammonium lead iodine, CH3NH3PbI3, have recently attracted considerable interest as alternative solar cell materials, and record solar cell efficiencies have now surpassed 20%. Concerns have, however, been raised about the thermal stability of methylammonium lead iodine, and a phase transformation from a tetragonal to a cubic phase has been reported at elevated temperature. Here, this phase transition has been investigated in detail using temperature-dependent X-ray diffraction measurements. The phase transformation is pinpointed to 54 degrees C, which is well within the normal operating range of a typical solar cell. The cell parameters were extracted as a function of the temperature, from which the thermal expansion coefficient was calculated. The latter was found to be rather high (alpha(v) = 1.57 X 10(-4) K-1) for both the tetragonal and cubic phases. This is 6 times higher than the thermal expansion coefficient for soda lime glass and CIGS and 11 times larger than that of CdTe. This could potentially be of importance for the mechanical stability of perovskite solar cells in the temperature cycling experienced under normal day night operation. The experimental knowledge of the thermal expansion coefficients and precise determination of the cell parameters can potentially also be valuable while conducting density functional theory simulations on these systems in order to deliver more accurate band structure calculations.

  • 47.
    Jacobsson, T. Jesper
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Tress, Wolfgang
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Correa-Baena, Juan-Pablo
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Room Temperature as a Goldilocks Environment for CH3NH3PbI3 Perovskite Solar Cells: The Importance of Temperature on Device Performance2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 21, s. 11382-11393Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Terrestrial applications of solar cells during day-night cycling as well as operation in winter and summer involve substantial temperature variations, which influence the photophysics as well as the charge separation and transport properties in the various materials employed in a device. In this study, the optical absorption of methylammonium lead iodide (MAPbI(3)) and the device performance of MAPbI(3) solar cells have been investigated in an extended temperature range between -190 and 80 degrees C. The optical properties were found to change by only a small amount in that temperature range. The device performance did, however, show more dramatic changes and decreased in a reversible manner for temperatures both higher and lower than room temperature. For temperatures up to 80 degrees C and down to -80 degrees C, the drop in performance was up to 25% compared to the room temperature value. Given thermal stability and reversible device performance, this is probably not a showstopper for terrestrial applications of perovskite solar cells but should be considered when evaluating the total energy yield under outdoor operations. At temperatures of 100 degrees C and below, which are relevant for outer atmosphere and space applications, the performance decreases rather dramatically and approaches zero at even lower temperature. Irreversible changes set in for temperatures above 50 degrees C. In addition, the hysteresis decreases at reduced temperatures. As the effects for the absorption properties are minor, the decrease in performance can be attributed to a temperature induced limitation in the transport and extraction of the photogenerated charge carriers which is seen as a strong increase of the series resistance at reduced temperature. The drop of the photovoltage for temperatures below -100 degrees C might be related to reduced charge carrier separation in the perovskite due to excitonic effects and a lower dielectric constant.

  • 48.
    Jain, Sagar M.
    et al.
    Swansea Univ, Coll Engn, SPECIFIC, Bay Campus,Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala Univ, Dept Engn Sci, Solid State Phys, Box 534, SE-75121 Uppsala, Sweden.
    Durrant, James R.
    Swansea Univ, Coll Engn, SPECIFIC, Bay Campus,Fabian Way, Swansea SA1 8EN, W Glam, Wales;Imperial Coll London, Dept Chem, Exhibit Rd, London SW7 2AZ, England;Imperial Coll London, Ctr Plast Elect, Exhibit Rd, London SW7 2AZ, England.
    Green fabrication of stable lead-free bismuth based perovskite solar cells using a non-toxic solvent2019Inngår i: COMMUNICATIONS CHEMISTRY, ISSN 2399-3669, Vol. 2, artikkel-id 91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The very fast evolution in certified efficiency of lead-halide organic-inorganic perovskite solar cells to 24.2%, on par and even surpassing the record for polycrystalline silicon solar cells (22.3%), bears the promise of a new era in photovoltaics and revitalisation of thin film solar cell technologies. However, the presence of toxic lead and particularly toxic solvents during the fabrication process makes large-scale manufacturing of perovskite solar cells challenging due to legislation and environment issues. For lead-free alternatives, non-toxic tin, antimony and bismuth based solar cells still rely on up-scalable fabrication processes that employ toxic solvents. Here we employ non-toxic methyl-acetate solution processed (CH3NH3)(3)Bi2I9 films to fabricate lead-free, bismuth based (CH3NH3)(3)Bi2I9 perovskites on mesoporous TiO2 architecture using a sustainable route. Optoelectronic characterization, X-ray diffraction and electron microscopy show that the route can provide homogeneous and good quality (CH3NH3)(3)Bi2I9 films. Fine-tuning the perovskite/hole transport layer interface by the use of conventional 2,2',7,7'-tetrakis (N,N'-di-p-methoxyphenylamino)-9,9'-spirbiuorene, known as Spiro-OMeTAD, and poly(3-hexylthiophene-2,5-diyl - P3HT as hole transporting materials, yields power conversion efficiencies of 1.12% and 1.62% under 1 sun illumination. Devices prepared using poly(3-hexylthiophene-2,5-diyl hole transport layer shown 300 h of stability under continuous 1 sun illumination, without the use of an ultra violet-filter.

  • 49.
    Jain, Sagar M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Phuyal, Dibya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Davies, Matthew L.
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Li, Meng
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales;Soochow Univ, Inst Funct Nano & Soft Mat, Suzhou 215000, Peoples R China.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    De Castro, Catherine
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Qiu, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kim, Jinhyun
    Imperial Coll London, Dept Chem, Exhibit Rd, London SW7 2AZ, England;Imperial Coll London, Ctr Plast Elect, Exhibit Rd, London SW7 2AZ, England.
    Watson, Trystan
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Tsoi, Wing Chung
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Karis, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Durrant, James R.
    Swansea Univ Bay Campus, Coll Engn, SPECIFIC, Fabian Way, Swansea SA1 8EN, W Glam, Wales;Imperial Coll London, Dept Chem, Exhibit Rd, London SW7 2AZ, England;Imperial Coll London, Ctr Plast Elect, Exhibit Rd, London SW7 2AZ, England.
    An effective approach of vapour assisted morphological tailoring for reducing metal defect sites in lead-free, (CH3NH3)(3)Bi2I9 bismuth-based perovskite solar cells for improved performance and long-term stability2018Inngår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 49, s. 614-624Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a controlled, stepwise formation of methylammonium bismuth iodide (CH3NH3)(3)Bi2I9 perovskite films prepared via the vapour assisted solution process (VASP) by exposing BiI3 films to CH3NH3I (MAI) vapours for different reaction times, (CH3NH3)(3)Bi2I9 semiconductor films with tunable optoelectronic properties are obtained. Solar cells prepared on mesoporous TiO2 substrates yielded hysteresis-free efficiencies upto 3.17% with good reproducibility. The good performance is attributed mainly to the homogeneous surface coverage, improved stoichiometry, reduced metallic content in the bulk, and desired optoelectronic properties of the absorbing material. In addition, solar cells prepared using pure BiI3 films without MAI exposure achieved a power conversion efficiency of 0.34%. The non-encapsulated (CH3NH3)(3)Bi2I9 devices were found to be stable for as long as 60 days with only 0.1% drop in efficiency. This controlled formation of (CH3NH3)(3)Bi2I9 perovskite films highlights the benefit of the VASP technique to optimize material stoichiometry, morphology, solar cell performance, and long-term durability.

  • 50.
    Jain, Sagar Motilal
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Park, Byung-Wook
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vapor phase conversion of PbI2 to CH3NH3PbI3: spectroscopic evidence for formation of an intermediate phase2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 7, s. 2630-2642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation of CH3NH3PbI3 (MAPbI(3)) from its precursors is probably the most significant step in the control of the quality of this semiconductor perovskite material, which is highly promising for photovoltaic applications. Here we investigated the transformation of spin coated PbI2 films to MAPbI(3) using a reaction with MAI in vapor phase, referred to as vapor assisted solution process (VASP). The presence of a mesoporous TiO2 scaffold on the substrate was found to speed up reaction and led to complete conversion of PbI2, while reaction on glass substrates was slower, with some PbI2 remaining even after prolonged reaction time. Based on data from UV-visible spectroscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, the formation of an X-ray amorphous intermediate phase is proposed, which is identified by an increasing absorption from 650 to 500 nm in the absorption spectrum. This feature disappears upon long reaction times for films on planar substrates, but persists for films on mesoporous TiO2. Poor solar cell performance of planar VASP prepared devices was ascribed to PbI2 remaining in the film, forming a barrier between the perovskite layer and the compact TiO2/FTO contact. Good performance, with efficiencies up to 13.3%, was obtained for VASP prepared devices on mesoporous TiO2.

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