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  • 151.
    Ji, Yu-Xia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, C.-G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Boman, M.
    Thermochromic VO2 Films by Thermal Oxidation of Vanadium in SO22016Inngår i: Solar Energy Materials and Solar Cells Journal, nr 144, s. 713-716Artikkel i tidsskrift (Fagfellevurdert)
  • 152. Johansson, M.
    et al.
    Alves, P.
    Green, S.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Near-infrared electrochromism in crystalline tungsten oxide thin films2010Konferansepaper (Fagfellevurdert)
  • 153.
    Johansson, Malin B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Baldissera, Gustavo
    Kungliga Tekniska Högskolan.
    Valyukh, Iryna
    Linköpings Universitet.
    Persson, Clas
    Kungliga Tekniska Högskolan.
    Arwin, Hans
    Linköpings Universitet.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations2013Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, nr 20, s. 205502-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (Ptot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low Ptot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies Eg ≈ 3.1 eV, which increase with increasing Ptot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic δ-WO3, and monoclinic γ- and ε-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The δ-WO3 and γ-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (>3 eV) and allowed transitions (>3.8 eV). The calculations show that Eg in ε-WO3 is higher than in the δ-WO3 and γ-WO3 phases, which provides an explanation for the Ptot dependence of the optical data.

  • 154.
    Johansson, Malin B
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kristiansen, Paw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Baldissera, G
    Duda, Laurent C
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Persson, C
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Band gap states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy, optical absorption spectroscopy and density functional calculationsManuskript (preprint) (Annet vitenskapelig)
  • 155. Johansson, Malin B
    et al.
    Kristiansen, Paw
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Baldissera, G
    Duda, Laurent C
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Persson, C
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Sub-band gap electronic states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy, optical absorption spectroscopy and density functional calculationsManuskript (preprint) (Annet vitenskapelig)
  • 156.
    Johansson, Malin B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mattsson, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lindquist, Sten-Eric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    The Importance of Oxygen Vacancies in Nanocrystalline WO3−x ThinFilms Prepared by DC Magnetron Sputtering for Achieving High Photoelectrochemical Efficiency2017Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, nr 13, s. 7412-7420Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The photoelectrochemical properties of tungsten oxide thinfilms with different stoichiometry (WO3−x) and thickness were investigated.The films were sputtered in O2/Ar gas (ratio 0.43) on glass substrates coatedwith fluorine-doped tin dioxide at two sputter pressures, Ptot = 10 and 30mTorr, yielding O/W ratios of the films, averaged over three samples, of 2.995and 2.999 (x ∼ 0.005 and x ∼ 0.001), respectively. The films were characterizedby X-ray diffraction, scanning electron microscopy, and spectrophotometry.The 10 mTorr samples showed large absorption in the near-infrared (NIR)range, whereas the 30 mTorr samples had a small absorption in this region. Theconcentration of oxygen vacancy band gap states was estimated from cyclicvoltammetry and was found to correlate with the optical absorption in the NIRregion. The incident photon to current efficiency for illumination from theelectrolyte side (IPCEEE) and substrate electrode side (IPCESE) showed higherefficiency for the more stoichiometric films, indicating that oxygen vacancies in the band gap act as recombination centers.Surprisingly high values of IPCEEE and IPCESE were found, and it was concluded that efficient charge separation and transporttake place almost throughout the entire film even for film electrodes as thick as 2 μm. Analysis of the spectral distribution of thephotoresponse (action spectra) using an extended Gärtner−Butler model to calculate the IPCE for front-side and back-sideillumination was performed and showed that the diffusion length is large, of the order of the depletion layer thickness.

  • 157.
    Johansson, Malin B
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Structural and optical properties of visible active photocatalytic WO3 thin films prepared by reactive dc magnetron sputtering2012Inngår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 27, nr 24, s. 3130-3140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanostructured tungsten trioxide films were prepared by reactive dc magnetron sputteringat different working pressures P-tot = 1-4 Pa. The films were characterized by scanning electron microscopy, x-ray diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, and ultraviolet-visible spectrophotometry. The films were found to exhibit predominantly monoclinic structures and have similar band gap, E-g approximate to 2.8 eV, with a pronounced Urbach tail extending down to 2.5 eV. At low P-tot, strained film structures formed, which were slightly reduced and showed polaron absorption in the near-infrared region. The photodegradation rate of stearic acid was found to correlate with the stoichiometry and polaron absorption. This is explained by a recombination mechanism, whereby photoexcited electron-hole pairs recombine with polaron states in the band gap. The quantum yield decreased by 50% for photon energies close to E-g due to photoexcitations to band gap states lying below the O-2 affinity level.

  • 158.
    Johansson, Malin B
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Xie, Ling
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thyr, Jakob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Göthelid, Mats
    KTH Royal Institute of Technology.
    Niklasson, Gunnar
    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.
    Porous Fractals of MAPbI3 Perovskite: Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Isopropanol solution based methylammonium lead triiodide (MAPbI3) is studied during the crystallization process. The crystal growth starts in an unstable suspension far from equilibrium by forming different dendritic patterns and terminates with aggregation of stable cubic crystalline grains into fractal clusters. Using transmission electron microscopy (TEM), the time evolution of a newly mixed suspension was studied over a period of two weeks at room temperature and a sequence of the morphological changes was observed. The crystallization process started with single dendritic growth exhibiting branches at 90 degrees angles to one another. After 4 hours, a multi-dendritic growth pattern and a transformation into small crystalline quantum dots were observed. After a week, clusters of crystal grains were formed into a fractal pattern and these patterns appear to be stable also during the second week. Electron and x-ray diffraction revealed the crystallinity of the quantum dots and the clusters of micrometer-sized crystals. Scanning transmission electron microscope (STEM) together with energy dispersive X-ray spectroscopy (EDS) showed that newly formed large grains, from a one hour old solution, displayed a core-shell structure with higher percentage of Pb atoms as compared to iodine at the surface. In the inner core of the grains the percentage of iodine was slightly higher. The electron diffraction (ED) scan over the newly formed grains revealed a polycrystalline surface whereas the inner part had a single crystal pattern. The same solution, now one-week-old, contained grains with only single crystal patterns in the ED scan and showed no core-shell character or polycrystalline surface. The measured percentage of iodine atoms compared to lead was 2:1 throughout the cross section, which is a quantitative value within the measurement. It can be concluded from these measurements that the suspension approaches higher crystallinity of the perovskite grains in an irreversible process, where the perovskite grains are insoluble in isopropanol. The perovskite material has also been characterized with scanning electron microscopy (SEM) and photoluminescence (PL) mapping where both techniques showed a very porous crystalline material. The PL mapping revealed two peaks at 730 and 760 nm for a thin film spin coated from a newly mixed solution, while a film deposited from a one week old solution showed three peaks, the last one at 830 nm. Because of the high crystallinity, it is suggested that all three peaks are due to band-to-band transitions and not due to localized states. These data will be analyzed further; however, the results contain information of the content of quantum dots versus larger crystals, as well as displaying emission intensity variations at different positions of the grains. The purpose with this project is to understand these phenomena of crystal growth. A new mesoporous perovskite material has been designed for optoelectronic purposes.

  • 159.
    Johansson, Malin B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zietz, Burkhard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical properties of nanocrystalline WO3 and WO3-x thin films prepared by DC magnetron sputtering2014Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, nr 21, s. 213510-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical properties of tungsten trioxide thin films prepared by DC magnetron sputtering, withdifferent oxygen vacancy (Vo) concentration, have been studied by spectrophotometry andphotoluminescence (PL) emission spectroscopy. Absorption and PL spectra show that the filmsexhibit similar band gap energies, Eg 2.9 eV. The absorption spectra of the films show twopronounced absorption bands in the near-infrared region. One peak (P1) is located atapproximately 0.7 eV, independent of Vo concentration. A second peak (P2) shifts from 0.96 eV to1.16 eV with decreasing Vo concentration. Peak P1 is assigned to polaron absorption due totransitions between tungsten sites (W5þ!W6þ), or an optical transition from a neutral vacancystate to the conduction band, Vo0!W6þ. The origin of peak P2 is more uncertain but may involveþ1 and þ2 charged vacancy sites. The PL spectra show several emission bands in the range 2.07 to3.10 eV in the more sub-stoichiometric and 2.40 to 3.02 eV in the less sub-stoichiometric films.The low energy emission bands agree well with calculated optical transition energies of oxygenvacancy sites, with dominant contribution from neutral and singly charged vacancies in the lesssub-stoichiometric films, and additional contributions from doubly charged vacancy sites in themore sub-stoichiometric films.

  • 160.
    Johansson, Malin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kristiansen, Paw T.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Duda, Laurent
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Band gap states in nanocrystalline WO3 thin films studied by softx-ray spectroscopy and opticalspectrophotometry2016Inngår i: Journal of Physics: Condensed Matter, ISSN 1361-648X, Vol. 28, artikkel-id 475802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocrystalline tungsten trioxide (WO3) thin films prepared by DC magnetron sputteringhave been studied using soft x-ray spectroscopy and optical spectrophotometry. Resonantinelastic x-ray scattering (RIXS) measurements reveal band gap states in sub-stoichiometric γ-WO3−x with x = 0.001–0.005. The energy positions of these states are in good agreementwith recently reported density functional calculations. The results were compared with opticalabsorption measurements in the near infrared spectral region. An optical absorption peak at 0.74 eV is assigned to intervalence transfer of polarons between W sites. A less prominentpeak at energies between 0.96 and 1.16 eV is assigned to electron excitation of oxygenvacancies. The latter results are supported by RIXS measurements, where an energy loss inthis energy range was observed, and this suggests that electron transfer processes involvingtransitions from oxygen vacancy states can be observed in RIXS. Our results have implicationsfor the interpretation of optical properties of WO3, and the optical transitions close to the bandgap, which are important in photocatalytic and photoelectrochemical applications.

  • 161. Johansson, Malin
    et al.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Determination of structures and properties of WO3 thin films deposited by DC magnetron sputtering2009Konferansepaper (Fagfellevurdert)
  • 162.
    Johnson, William B.
    et al.
    W. L. Gore & Associates.
    Worrell, Wayne L.
    University of Pennsylvania.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Malmgren, Sara
    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.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Sundaram, S K
    Alfred University.
    Solid-State Devices: Impedance Response of Electrochromic Materials and Devices2018Inngår i: IMPEDANCE SPECTROSCOPY: Theory, Experiment, and Applications / [ed] Evgenij Barsoukov and J. Ross Macdonald, Hoboken,: John Wiley & Sons, 2018, 3rd, s. 247-291Kapittel i bok, del av antologi (Fagfellevurdert)
  • 163.
    Jonsson, A K
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Fasta tillståndets fysik.
    Larsson, A-L
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Fasta tillståndets fysik.
    Niklasson, G A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Fasta tillståndets fysik.
    Strömme, M
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Nanoteknologi och funktionella material.
    H+ Conduction Parameters in Solid-State Electrochromic Devices Obtained by the Isothermal2005Inngår i: J. Electrochem. Soc., Vol. 152, s. A377-A379Artikkel i tidsskrift (Fagfellevurdert)
  • 164.
    Jonsson, AnnaKarin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Frenning, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Nilsson, M
    Strømme Mattsson, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap.
    Dielectric study of thin films of Ta2O5 and ZrO22001Inngår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 8, nr 4, s. 648-651Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electronic conduction in sputtered Ta2O5 and ZrO2 thin films have been studied using impedance spectroscopy, isothermal transient ionic current, and current-voltage measurements. The dielectric properties of Ta2O5 were shown to be sensitively dependent on deposition parameters with two different frequency responses: a flat loss behavior with very low DC conductivity, or a relaxation peak together with a somewhat higher DC conductivity. ZrO2 has different dielectric properties when fresh, i.e. newly deposited, or aged. A fresh sample arbitrarily can show two different behaviors, consisting of a DC conductivity with a relaxation peak superimposed on it. The DC conductivity shows either of two different values. The aged sample has a lower permittivity and DC conductivity, and the relaxation peak is found at much lower frequencies. Fresh samples of ZrO2 also show switching behavior

  • 165.
    Jonsson, Jacob
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Materialvetenskap.
    Karlsson, Linus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Materialvetenskap.
    Nostell, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Materialvetenskap.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Materialvetenskap.
    Smith, Geoffrey
    Angle-dependent light scattering in materials with controlled diffuse solar optical properties2004Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 84, nr 1-4, s. 427-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Light scattering plays a prominent role in a wide range of energy-efficient materials and solar applications. Some examples are materials for daylighting, diffusely reflecting sunscreens, foils for radiative cooling and nanocrystalline solar cells. Measurements of the angular profile of light scattering are very useful for obtaining a detailed characterization of the light scattering mechanisms. We review recent theoretical results on the forward and backward light scattering profiles. Forward scattering is of major importance for novel pigmented polymeric daylighting materials. Measurements of scattering profiles are in good agreement with Mie theory. Backscattering profiles from highly diffusely reflecting paints containing titanium oxide-based pigments have also been measured. It seems that scattering from the paint surface dominates at low pigment volume fractions. Results for paints with high pigment volume fractions are interpreted in terms of coherent backscattering effects from the pigment particles.

  • 166.
    Kaden, Heike
    et al.
    Karlsruhe Institute of Technology.
    Königer, F
    Karlsruhe Institute of Technology.
    Schuhmann, R
    Karlsruhe Institute of Technology.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Emmerich, Katja
    Karlsruhe Institute of Technology.
    Detection of moisture differences of a swellable and a non-swellable clay in the low and mid frequency range2011Inngår i: 6th Conference on Innovative Moisture Measurement in Research and Practise, Karlsruhe, Oct. 2011, 2011, s. 10pp-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The sensitivity of dielectric spectroscopy to display changes in moisture content was studied for one swellable (bentonite) and one non-swellable clay (illite) in the low (1.0E-04…1.0E+06 Hz) and mid (2.0E+08…1.1E+09 Hz) frequency range. Therefore, both air dry materials were stored until equilibration at 11% and 93% relative humidity (r.h.) and their volumetric water content (Wvol) was measured with static and dynamic heating as well as with dielectric spectroscopy. Transformation of complex permittivity to Wvol was accomplished using the calibration functions after Topp and Roth. Moisture distinction could be displayed for both materials in the lower frequency range, whereas the changes in water content could only be described for the illite within the mid frequency range. Estimation of volumetric water content by transformation of real relative permittivity with Topp-function, resulted in underestimation of Wvol, especially for samples stored at high relative humidity (93% r.h.). Determination of Wvol with the calibration function after Roth was successful for illite at 11% r.h., but failed at higher relative humidity and for the bentonite in both hydration states. Additionally, complex dielectric data were clearly influenced by other processes beside bound water polarization.

  • 167.
    Kaden, Heike
    et al.
    Karlsruhe Institute of Technology.
    Königer, Franz
    Karlsruhe Institute of Technology.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Emmerich, Katja
    Karlsruhe Institute of Technology.
    Low-frequency dielectric properties of three bentonites at different adsorbed water states2013Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 411, s. 16-26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three bentonites of varying smectite content were investigated by dielectric spectroscopy in the frequency range 10(-4) to 10(6)Hz after storage at well-defined humidities. The identification of relaxation processes from complex permittivity measurements was difficult, since conductivity effects were superimposed on the underlying relaxations. Relaxation peaks revealed by the dissipation factor indicated the occurrence of interfacial processes between 10(2) and 10(6) Hz. The intensity of the polarization of the electrochemical double-layer at the clay-water interface was promoted by increasing water content and was shifted to higher frequencies the higher the water content in the bentonites. Below ∼1Hz, electrode polarization (EP) was shown to be a participating process with capacitance values ranging from 0.6(*)10(-3) to 7.3(*)10(-3)F due to the accumulated charges. An equivalent circuit model was introduced that successfully described the low-frequency dielectric behavior of bentonites at low moisture levels. An included series R-CPE connection was used to describe the double-layer relaxation. At water contents up to 17%, the bulk resistivity was mainly influenced by smectite content and cation exchange capacity, whereas at water contents of ⩾19%, interlayer occupation and hydration state became more important.

  • 168.
    Kaden, Heike
    et al.
    Karlsruhe Institute of Technology.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Königer, F
    Karlsruhe Institute of Technology.
    Schuhmann, R
    Karlsruhe Institute of Technology.
    Emmerich, K
    Karlsruhe Institute of Technology.
    Dielectric spectroscopy of swellable clays at low moisture levels2012Inngår i: BDS 2012. Broadband Dielectric Spectroscopy and its Applications, Leipzig, September 3-7, 2012., 2012, s. 142-Konferansepaper (Fagfellevurdert)
  • 169.
    Karlsson, Stefan
    et al.
    RISE Research Institutes of Sweden.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Järn, M
    RISE.
    Eriksson, J
    RISE.
    Welinder, J
    RISE.
    Försth, M
    RISE.
    Ludvigsson, Mikael
    RISE.
    "Transparent intelligence" for sustainable development2018Inngår i: Abstracts: 15th Internatinal Conference on the Physics of Non-Crystalline Solids och 14th European Society of Glass Conference (PNCS-ESG 2018), Saint Malo, Frankrike, 2018, s. 208-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Transparent materials are essential in everyone’s life. They enable daylight to reach the interior of buildings, thereby contributing to both our physical and mental well-being; they are the primary component for communication via optical fibers and a key component in electronic devices such as protective cover and/or dielectric material; and they enable clean energy production through solar panels or algae reactors by acting as protective and light transmitting barriers. Adding functions to transparent materials in an intelligent way creates further opportunities to use and enhance the beneficial impacts of transparency. The concept Transparent Intelligence covers transparent materials and products with integral intelligent functions – passive, active or interactive. By using Transparent Intelligence it is possible to embrace many of the societal challenges that we are facing today. The concept can be divided into five broad industrial sectors: Built Environment, Information and Communication Technologies (ICT), Solar Energy, Mobility, and Materials. A perspective on how Transparent Intelligence can improve the sustainable development of our world will be presented, using examples of electrochromic windows for energy-efficient buildings, photocatalytic coatings for improved indoor air quality, transparent conductive coatings for antennas, bandpass filters for mobile phone indoor coverage, UV down-converting components for efficient solar energy, hygienic surfaces for infection mitigation on electronic devices, printed electronics for sustainable glass packaging, and IR-reflecting coatings for fire safety.

  • 170.
    Kish, L. B.
    et al.
    Texas A&M Univ, Dept Elect & Comp Engn, College Stn, TX USA.
    Ferry, D. K.
    Arizona State Univ, Sch Elect Comp & Energy Engn, Tempe, AZ USA.
    Niklasson, G. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Smulko, J. M.
    Gdansk Univ Technol, Fac Elect Telecommun Informat, Dept Metrol & Optoelect, Gdansk, Poland.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Facts and myths about zero-point thermal noise, and information entropy versus thermal entropy2017Inngår i: 2017 INTERNATIONAL CONFERENCE ON NOISE AND FLUCTUATIONS (ICNF), IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this talk, we are briefly surveying our recent results [1-3] about two very popular yet often misunderstood concepts in physical informatics: (i) The existence of Johnson noise at near to absolute zero temperature has been debated many times yet it is generally accepted [1]. We point out the fundamental problems [2] with the particular approach the related quantum theories [4] of Fluctuation-Dissipation Theorem are using. Then we prove that the existence of zero-point noise would allow the construction of a perpetual motion machine [1]. Finally, we cite early works pointing out that the observed “zeropoint” noise in experiments [7] with phase-sensitive linear amplifiers is an amplifier-noise [5,6] due to the uncertainty principle, and it does not exist in the resistor in an objective way, independently from the measurement [1,2]. Thus a correct derivation of the Fluctuation-Dissipation Theorem must include [1] the type of experimental setup used for the measurement. (ii) The general opinion is that information entropy and thermal entropy are interchangeable. This belief triggered Brillouin's negentropy principle of information [8], and Landauer's claimed principle [9] about energy dissipation during information erasure that has been debated on many occasions [10-19]. Here we show the newest and perhaps the simplest arguments [3] proving that the two types of entropies are apples and oranges and are not interchangeable.

  • 171.
    Kish, Laszlo B
    et al.
    Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Khatri, Sunil P
    Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Peper, Ferdinand
    CiNet, NICT, Osaka University, Osaka, Japan.
    Information, Noise, and Energy Dissipation:: Laws, Limits, and Applications2017Inngår i: Molecular Architectonics: Advances in Atom and Single Molecule Machines / [ed] T. Ogawa, Springer, 2017, s. 27-44Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This chapter addresses various subjects, including some open questions related to energy dissipation, information, and noise, that are relevant for nano- and molecular electronics. The object is to give a brief and coherent presentation of the results of a number of recent studies of ours

  • 172.
    Kish, Laszlo B.
    et al.
    Department of Electrical Engineering, Texas A&M University, Texas USA.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Zero Thermal Noise in Resistors at Zero Temperature2016Inngår i: Fluctuation and Noise Letters, ISSN 0219-4775, E-ISSN 1793-6780, Vol. 15, nr 3, artikkel-id 1640001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The bandwidth of transistors in logic devices approaches the quantum limit, where Johnsonnoise and associated error rates are supposed to be strongly enhanced. However, the related theory — asserting a temperature-independent quantum zero-point (ZP) contribution to Johnson noise, which dominates the quantum regime — is controversial and resolution of the controversy is essential to determine the real error rate and fundamental energy dissipation limits of logic gates in the quantum limit. The Callen–Welton formula (fluctuation–dissipation theorem) of voltage and current noise for a resistance is the sum of Nyquist’s classical Johnson noise equation and a quantum ZP term with a power density spectrum proportional to frequency and independent of temperature. The classical Johnson–Nyquist formula vanishes at the approach of zero temperature, but the quantum ZP term still predicts non-zero noise voltage and current. Here, we show that this noise cannot be reconciled with the Fermi–Dirac distribution, which defines the thermodynamics of electrons according to quantum-statistical physics. Consequently,Johnson noise must be nil at zero temperature, and non-zero noise found for certain experimental arrangements may be a measurement artifact, such as the one mentioned in Kleen’s uncertainty relation argument.

  • 173.
    Kish, Laszlo B.
    et al.
    Texas A&M Univ, Dept Elect & Comp Engn, TAMUS 3128, College Stn, TX 77843 USA..
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Zero-point term and quantum effects in the Johnson noise of resistors: a critical appraisal2016Inngår i: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, artikkel-id 054006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a longstanding debate about the zero-point term in the Johnson noise voltage of a resistor. This term originates from a quantum-theoretical treatment of the fluctuation-dissipation theorem (FDT). Is the zero-point term really there, or is it only an experimental artifact, due to the uncertainty principle, for phase-sensitive amplifiers? Could it be removed by renormalization of theories? We discuss some historical measurement schemes that do not lead to the effect predicted by the FDT, and we analyse new features that emerge when the consequences of the zero-point term are measured via the mean energy and force in a capacitor shunting the resistor. If these measurements verify the existence of a zero-point term in the noise, then two types of perpetual motion machines can be constructed. Further investigation with the same approach shows that, in the quantum limit, the Johnson-Nyquist formula is also invalid under general conditions even though it is valid for a resistor-antenna system. Therefore we conclude that in a satisfactory quantum theory of the Johnson noise, the FDT must, as a minimum, include also the measurement system used to evaluate the observed quantities. Issues concerning the zero-point term may also have implications for phenomena in advanced nanotechnology.

  • 174.
    Kish, Laszlo B
    et al.
    Department of Electrical and Computer Engineering, Texas A&M University, College Station,.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ferry, D K
    School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe.
    Smulko, Janusz M
    Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications, Informatics, Gdansk University of Technology.
    Facts and myths about zero-point thermal noise, and information entropy versus thermal entropy2017Inngår i: 2017 International Conference on Noise and Fluctuations, IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this talk, we are briefly surveying our recent results [1-3] about two very popular yet often misunderstood concepts in physical informatics: (i) The existence of Johnson noise at near to absolute zero temperature has been debated many times yet it is generally accepted [1]. We point out the fundamental problems [2] with the particular approach the related quantum theories [4] of Fluctuation-Dissipation Theorem are using. Then we prove that the existence of zero-point noise would allow the construction of a perpetual motion machine [1]. Finally, we cite early works pointing out that the observed "zeropoint" noise in experiments [7] with phase-sensitive linear amplifiers is an amplifier-noise [5,6] due to the uncertainty principle, and it does not exist in the resistor in an objective way, independently from the measurement [1,2]. Thus a correct derivation of the Fluctuation-Dissipation Theorem must include[1] the type of experimental setup used for the measurement. (ii) The general opinion is that information entropy and thermal entropy are interchangeable. This belief triggered Brillouin's negentropy principle of information [8], and Landauer's claimed principle [9] about energy dissipation during information erasure that has been debated on many occasions [10-19]. Here we show the newest and perhaps the simplest arguments [3] proving that the two types of entropies are apples and oranges and are not interchangeable.

  • 175. Kish, LB
    et al.
    Niklasson, G A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ferry, DK
    Smulko, JM
    Facts and myths about zero-point thermal noise, and information entropy versus thermal entropy2017Inngår i: IEEE Digital Library, 2017Konferansepaper (Fagfellevurdert)
  • 176.
    Laaksonen, Katri
    et al.
    Aalto University.
    Li, Shu-Yi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Puisto, S. R.
    MatOx Oy.
    Rostedt, N. K. J.
    MatOx Oy.
    Ala-Nissila, T.
    Aalto University.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nieminen, R. M.
    Aalto University.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nanoparticles of TiO2 and VO2 in dielectric media: Conditions for low optical scattering, and comparison between effective medium and four-flux theories2014Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 130, nr SI, s. 132-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spectral transmittance and reflectance in the 300 to 2500 nm solar-optical wavelength range were calculated for nanoparticles of titanium dioxide and vanadium dioxide with radii between 5 and 100 nm embedded in transparent dielectric media. Both of the materials are of large importance in green nanotechnologies: thus TiO2 is a photocatalyst that can be applied as a porous film or a nanoparticle composite on indoor or outdoor surfaces for environmental remediation, and VO2 is a thermochromic material with applications to energy-efficient fenestration. The optical properties, including scattering, of the nanoparticle composites were computed from the Maxwell–Garnett effective-medium theory as well as from a four-flux radiative transfer model. Predictions from these theories approach one another in the limit of small particles and in the absence of optical interference. Effects of light scattering can be modeled only by the four-flux theory, though. We found that nanoparticle radii should be less than ~20 nm in order to avoid pronounced light scattering.

  • 177.
    Lansåker, P. C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Johansson, M.
    Granqvist, C.-G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Temperature Dependent Coalescence in Au Films and Nanopartickles: Applications to Smart Windows and Photocatalysis2011Konferansepaper (Fagfellevurdert)
  • 178.
    Lansåker, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Backholm, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    TiO2/Au/TiO2 Multilayer Thin Films: Novel Metal-Based Transparent Conductors for Electrochromic Devises2009Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, nr 4, s. 1225-1229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transparent conductors based on Au films, with thicknesses in the 2.6<d<9.8 nm range, were made by DC magnetron sputtering onto glass. The films went from an "island" structure at low thicknesses to a uniform structure at d>8 nm, as seen from electron microscopy, electrical resistance, and spectrophotometric transmittance and reflectance. Optical data for uniform films were given a consistent interpretation within the Drude model. Optimized TiO2/Au/TiO2 films, with a luminous transmittance of 80%, were found to have good electrochemical durability and may be useful for applications in electrochromic devices.

  • 179.
    Lansåker, Pia C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gunnarsson, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Au-Based Transparent Conductors for Window Applications: Effect of Substrate Material2010Inngår i: Advances in Science and Technology, ISSN 1662-0356, Vol. 75, s. 25-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films of Au were made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films were up to ~11 nm in thickness and covered the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less “holey” film. Scanning electron microscopy and atomic force microscopy showed that the SnO2:In films were considerably rougher than the glass itself. This roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and electrical resistance could be reconciled with impeded Au film formation on the SnO2:In layer, leading to pronounced “plateaus” in the near infrared optical properties for Au films on SnO2:In and an accompanying change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses.

  • 180.
    Lansåker, Pia C
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gunnarsson, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Au thin films deposited on SnO2:In and glass: Substrate effects on the optical and electrical properties2011Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, nr 6, s. 1930-1933Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on a detailed study on the optical and electrical properties of Au films made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films had thicknesses up to 10.7 nm and hence spanned the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less "holey" film. Scanning electron microscopy and atomic force microscopy demonstrated that the SnO2:In films were considerably rougher than the glass itself, and this roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and reflectance and of electrical resistance gave a fully consistent picture that could be reconciled with impeded Au film formation on the SnO2:In layer; this led to pronounced "plateaus" in the near infrared optical spectra for Au films on SnO2:In and a concomitant change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses. Our work highlights the importance of the substrate roughness for transparent conductors comprising coinage metal films backed by wide band gap transparent conducting oxides.

  • 181.
    Lansåker, Pia C
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Hallén, Anders
    Royal Institute of Technology, Stockholm.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Characterization of gold nanoparticle films: Rutherford backscatteringspectroscopy, scanning electron microscopy with image analysis, and atomic forcemicroscopy2014Inngår i: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 4, nr 10, s. 107101-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gold nanoparticle films are of interest in several branches of science and technology,and accurate sample characterization is needed but technically demanding. We preparedsuch films by DC magnetron sputtering and recorded their mass thicknessby Rutherford backscattering spectroscopy. The geometric thickness dg—from thesubstrate to the tops of the nanoparticles—was obtained by scanning electron microscopy(SEM) combined with image analysis as well as by atomic force microscopy(AFM). The various techniques yielded an internally consistent characterization ofthe films. In particular, very similar results for dg were obtained by SEM with imageanalysis and by AFM.

  • 182.
    Lansåker, Pia C
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thin gold films on SnO2:In: Temperature-dependent effects on the optical properties2012Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 9, s. 3688-3691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gold films with thicknesses of 5 +/- 0.5 nm were sputter deposited onto SnO2:In-coated glass kept at different temperatures up to 140 degrees C, and similar films, deposited onto substrates at 25 degrees C, were annealing post treated at the same temperatures. Nanostructures and optical properties were recorded by scanning electron microscopy and spectrophotometry in the 0.3 to 2.5 mu m wavelength range, respectively. Annealing had a minor influence on the optical transmittance despite significant changes in the scale of the nanostructure, whereas deposition onto substrates heated to 140 degrees C yielded granular films with strong plasmon absorption of luminous radiation. These results are of considerable interest for optical devices with gold films prepared at elevated temperature or operating at such temperature.

  • 183.
    Lansåker, Pia C.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Petersson, P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thin sputter deposited gold films on In2O3:Sn, SnO2:In, TiO2 and glass: Optical, electrical and structural effects2013Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 117, nr SI, s. 462-470Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin gold films are promising transparent conductors with many actual and potential uses in "green" technologies, transparent electronics, etc. These applications require different substrate materials, and hence it is important to understand the role of the substrate on Au thin film growth. Such effects have been studied in this work wherein Au films ranging from island structures, via large scale coalescence into meandering metal networks, to thin homogenous layers were deposited by DC magnetron sputtering onto glass substrates and In2O3:Sn (ITO), SnO2:In and TiO2 base layers backed by glass. Optical, electrical and structural properties were recorded for films deposited onto unheated substrates. We found distinct and characteristic differences in Au growth on the various backings. Thus ITO and SnO2:In base layers yielded gold films with island features remaining to larger thicknesses than for deposition directly onto glass, and the sheet resistance was lower for gold deposition onto SnO2:In and ITO only when the gold films were less than similar to 5 nm in thickness. Our results highlight the complexity of substrates' influence on thin film formation. 

  • 184.
    Lansåker, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Cindemir, Umut
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Indium Tin Oxide Thin Films for Formaldehyde and Acetaldehyde Sensing2014Inngår i: Micronano System Workshop, Uppsala, Sweden, 15-16 May, 2014Konferansepaper (Fagfellevurdert)
  • 185.
    Lansåker, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gunnarsson, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, C.-G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Au-based transparent conductors for windows applications: Effect of substrate material2010Inngår i: International Journal of Advances in Science and Technology, ISSN 2229-5216, Vol. 75, s. 25-30Artikkel i tidsskrift (Fagfellevurdert)
  • 186.
    Lansåker, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ribbing, Carl-Gustaf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Temperature effect on gold nanoparticle growth and plasmonic properties.2013Inngår i: Optics and Photonics in Sweden, Uppsala Oct. 22-23, 2013: Poster abstracts, PhotonicSweden , 2013, s. 1 p-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The plasmonic properties of gold nanoparticles (NPs) have very promising prospects to enhance theefficiency in several branches of science and technology, such as in environmental, energy, biomedicaland information technology. The plasmonic properties are strongly related to the shape, size anddistribution of the NPs and to their surrounding media. Therefore, suitable techniques for optimizedNP manufacturing, as well as improved understanding of the optical characteristics of the NPs, arenecessary for progress.In this work, gold was deposited on heated substrates using DC magnetron sputtering, which is amethod with great reproducibility and suitability for large area coatings. The method is also simple touse and gives NPs at considerably lower temperatures than other heat treating manufacturingtechniques. The depositions were performed at three different substrate temperatures, and a series ofgold NP samples were manufactured at each temperature. The localized surface plasmon resonance ofthe NPs was investigated by optical measurements, and the results were related to the shape, size anddistribution of the NPs, as observed from scanning electron microscopy and image analysis. Basic physics regarding plasmonics and metal NP growth processes are also presented.The optical results show effects of particle-particle interaction, aspect ratio and size of the NPs,which are in full agreement with results on NP structure and distribution.

  • 187.
    Lansåker, Pia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Tuncer, Enis
    3M Austin Center, EEBG/CRML, Austin, Texas, USA.
    Valyukh, Irina
    Dept. Physics, Chemistry and Biology, Linköping University.
    Arwin, Hans
    Dept. Physics, Chemistry and Biology, Linköping University.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Spectral Density Analysis of Thin Gold Films: Thickness and Structure Dependence of the Optical Properties2013Inngår i: PIERS 2013 Stockholm: Progress in Electromagnetics Research Symposium Proceedings,, Cambridge, MA: The Electromagnetics Academy , 2013, s. 443-447Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Abstract| In this paper we study the feasibility of representing the optical properties ofultrathin gold films by effective medium theories. Gold films with mass thicknesses in the range of 1.4 to 9.2 nm were deposited by DC magnetron sputtering onto non-heated glass substrates.Optical measurements in the range 0.25 to 2 μm were carried out by spectroscopic ellipsometry, and the effective complex dielectric function of each film was determined. The gold films were modelled as a mixture of gold and air, and a general effective medium description using the spectral density function (SDF) was used to describe their optical properties. Numerical inversion of the experimental dielectric function gave a broad and rather featureless SDF, with a few superimposed peaks, both for island structures and percolating films. The broad background is qualitatively similar to predictions of the Bruggeman model [14].

  • 188.
    Larsson, A.-L
    et al.
    Fasta tillståndets fysik/ ÅSTC.
    Niklasson, G A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Fasta tillståndets fysik.
    Infrared absorption of Li-intercalated tungsten oxide2003Inngår i: IME-4 (International Meeting on Electrochromism)Artikkel i tidsskrift (Fagfellevurdert)
  • 189.
    Larsson, Anna-Lena
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Solis, Jose
    Instituto Peruano de Energía Nuclear.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Infrared absorption in Li-intercalated tungsten oxide2007Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 91, nr 13, s. 1248-1252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin films of amorphous and polycrystalline tungsten oxide were produced by reactive dc magnetron sputtering and nanocrystalline films were deposited by advanced gas evaporation. The films were submitted to electrochemical intercalation of Li ions before infrared reflectance measurements were carried out. For crystalline films, the reflectance in the wavelength region 10–30 μm increases upon intercalation, indicating an increasing free-electron contribution. On the other hand, all the films display an increased absorption at wavelengths less than 10 μm when intercalated. The thermal emittance could be varied from about 0.5 to 0.7–0.75 by intercalation in films with thicknesses in excess of 1 μm. Both absorption and interference contribute to the emittance contrast.

  • 190.
    Lebrun, Delphine
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fabrication of photonic opal structures on different support materials by convective evaporation2014Inngår i: INERA Workshop: Transition Metal Oxides as Functional Layers in Smart windows and Water Splitting Devices / Parallel session of the 18th International School on Condensed Matter Physics, Institute of Physics Publishing (IOPP), 2014, s. 012007-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Photonic polystyrene (PS) opals with face-centered cubic structure werefabricated by convective evaporation. The influences of substrate and its physicalproperties, as well as deposition conditions were investigated. It is shown that thesurface roughness must be less than about 30% of the bead diameter to form wellorderedopals, rendering substrates such as glass, ITO and quartz superior to thickKapton, ordinary tape, thermal release semiconductor tape, plastic and hydrophilicplastic HHNW W (Kemafoil). Periodic stripe-like structures were found to formperpendicular to the growth direction defined by the receding meniscus of the solutionfront when the PS concentration is lower than 1.0 w/v%. Finally, we present theprinciples and results of using soft sacrificial layer deposited on quartz substrates tofabricate free standing inverse opal structures.1.

  • 191.
    Lebrun, Delphine
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Metal Oxides photonic band gap inverse opals2014Inngår i: Workshop on Magnetoplasmonics 2014, Uppsala (Sweden)., 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Poster on metal oxide inverse opal fabrication and gold nanoparticles impregnations for the Workshop on Magnetoplasmonics 2014, Uppsala (Sweden).

  • 192.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bayrak Pehlivan, Ilknur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Progress in Electrochromics and Thermochromics: Two New Applications Involving ITO Nanoparticles.2012Inngår i: Society of Vacuum Coaters 55th Annual Technical Conference Proceedings, Albuquerque, USA: Soiety of Vacuum Coaters , 2012, s. 41-46Konferansepaper (Fagfellevurdert)
  • 193.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Mlyuka, Nuru R
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. University of Dar es Salaam.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Hallén, Anders
    Royal Institute of Technology (KTH).
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes G
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bandgap widening in thermochromic Mg-doped VO2 thin films: Quantitative data based on optical absorption2013Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, nr 16, s. 161907-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermochromic Mg-doped VO2 films were deposited by reactive direct current magnetronsputtering onto heated glass and carbon substrates. Elemental compositions were inferred fromRutherford backscattering. Optical bandgaps were obtained from spectral transmittance and reflectance measurements—from both the film side and the back side of the samples—and ensuing determination of absorption coefficients. The bandgap of Mg-doped films was found to increase by 3.9 ± 0.5 eV per unit of atom ratio Mg/(Mg + V) for 0 < Mg/(Mg + V) < 0.21. The presence of ∼0.45 at. % Si enhanced the bandgap even more.

  • 194.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Namura, Kyoko
    Kyoto University - Katsura.
    Suzuki, Motofumi
    Kyoto University - Katsura.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling2013Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, nr 3, s. 033516-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reactive dc magnetron sputtering onto glass-based substrates yielded deposits of thermochromic VO2 with well-developed nanorods and nanowires. Their formation was promoted by high substrate temperature (above similar to 500 degrees C), sufficient film thickness, proper inlet of the reactive gas, dispersed gold "seeds," and pronounced substrate roughness. Rutherford back scattering ascertained mass thicknesses, scanning electron microscopy depicted the nanostructures, and glancing incidence X-ray diffraction proved that single-phase VO2 was normally formed. Spectrophotometric measurements of total and diffuse transmittance and reflectance on VO2 thin films, at room temperature and similar to 100 degrees C, allowed us to determine complex dielectric functions below and above the "critical" temperature for thermochromic switching (similar to 68 degrees C). These data were then used in computations based on the Bruggeman effective medium theory applied to randomly oriented prolate spheroidal structural units to derive the optical properties of the deposits. Experimental and computed data on spectral absorptance were found to be in good qualitative agreement.

  • 195.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    A thermochromic low-emittance coating: Calculations for nanocomposites of In2O3:Sn and VO22011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, nr 13, s. 131907-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Calculations based on the Bruggeman effective medium theory were applied to thin films comprising a heavily doped wide band gap semiconductor (specifically In(2)O(3):Sn (ITO)) and VO(2). Films with similar to 20 vol. % of VO(2) can combine a 10% thermochromic modulation of the solar energy throughput with a luminous transmittance of 50%-60% and low thermal emittance. The maximum thermochromic modulation is similar to 13% and occurs at similar to 35 vol. % VO(2). Coatings of ITO-VO(2) are of interest for energy efficient fenestration.

  • 196.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nanothermochromics: Calculations for VO2 nanoparticles in dielectric hosts show much improved luminous transmittance and solar energy transmittance modulation2010Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, nr 6, s. 063525-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    VO2-based films are thermochromic and show infrared reflectance above a "critical" temperature in the vicinity of room temperature. Implementations on energy efficient windows have been discussed for decades but have been severely curtailed since the luminous absorptance is undesirably large and the solar energy transmittance modulation is too small. Here we show by calculations based on effective medium theory that dilute composites with VO2 nanoparticles embedded in hosts with properties mimicking glass or polymer can yield significantly decreased luminous absorption jointly with much enhanced transmittance modulation of solar energy. These results demonstrate that VO2-based nanothermochromics opens new avenues toward energy efficient fenestration.

  • 197.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nanothermochromics with VO2-based core-shell structures: Calculated luminous and solar optical properties2011Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, nr 11, s. 113515-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Composites including VO2-based thermochromic nanoparticles are able to combine high luminous transmittance T-lum with a significant modulation of the solar energy transmittance Delta T-sol at a "critical" temperature in the vicinity of room temperature. Thus nanothermochromics is of much interest for energy efficient fenestration and offers advantages over thermochromic VO2-based thin films. This paper presents calculations based on effective medium theory applied to dilute suspensions of core-shell nanoparticles and demonstrates that, in particular, moderately thin-walled hollow spherical VO2 nanoshells can give significantly higher values of Delta T-sol than solid nanoparticles at the expense of a somewhat lowered T-lum. This paper is a sequel to a recent publication [S.-Y. Li, G. A. Niklasson, and C. G. Granqvist, J. Appl. Phys. 108, 063525 (2010)].

  • 198.
    Li, Shu-Yi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Performance Limits of Thermochromic Undoped and Mg-Doped VO2 Films and Nanoparticles for Energy Efficient Window Applications2014Inngår i: European Materials Research Society (E-MRS) Spring Meeting, Lille, France, 26-30 May: Symposium L: Chromogenic Materials and Devices, 2014Konferansepaper (Fagfellevurdert)
  • 199.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Plasmon-induced near-infrared electrochromism based on transparent conducting nanoparticles: Approximate performance limits2012Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, nr 7, s. 071903-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochromism can be induced in electrochemically post-treated nanoparticles of wide band gap transparent conductors. We model this recently observed phenomenon by effective medium theory applied to nanoparticles of In2O3:Sn, which are represented as a free-electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This semi-quantitative theory is used to derive approximate performance limits showing that high luminous transmittance (e.g., 60%) can be combined with efficient absorption of solar energy and concomitant low solar transmittance (similar to 34%), thereby documenting that plasmonic electrochromism is of interest for energy efficient fenestration.

  • 200.
    Li, Shuyi
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thermochromic fenestration with VO2-based materials: Three challenges and how they can be met2012Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 10, s. 3823-3828Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermochromic VO2-based films have higher infrared transmittance below a "critical" temperature tau(c) than above this temperature and can be used for regulating the solar energy transmittance T-sol in energy efficient windows. Pure VO2 is not practical, though, since (i) the modulation of T-sol is too small at tau(c), (ii) the luminous transmittance is too low, and (iii) tau(c) is too high. This paper discusses how these three challenges can be met. Specifically, using VO2-based nanoparticle composites rather than films makes it possible to significantly alleviate (i) and (ii), Mg doping of VO2 can give further improvements of (ii), and W doping (and to some extent also Mg doping) is important for (iii) and can bring tau(c) to a comfort temperature. The paper hence delineates a path towards practically useful thermochromic fenestration. 

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