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  • 101.
    Granqvist, Claes Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Solar energy materials for heating and cooling: Part One2018In: SVC Society of Vacuum Coaters Bulletin, no spring issue, p. 36-45Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Solar energy materials have properties that are tailored to the characteristics of the electromagneti cradiation in our natural surroundings, specifically its spectral distribution, angle of incidence, and intensity. This tailoring can be made withregard to solar irradiation, thermal emission, atmospheric absorption, visiblelight, photosynthetic efficienry and more. Solarenergy materials can be of many kinds, e.g., metallic, semiconducting, dielectric, glassy, polymeric, gaseous, etc.

  • 102.
    Granqvist, Claes Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Solar energy materials for heating and cooling: Part Two2018In: SVC Bulletin, no summer issue, p. 26-41Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Solar energy materials have properties that are tailored to the characteristics of the electromagnetic radiation in our natural surroundings, specifically its spectral distribution, angle of incidence, and intensity. This tailoring can be made with regard to solar irradiation, thermal emission, atmospheric absorption, visible light, photosynthetic efficiency and more. Solar energy materials can be of many kinds, e.g., metallic, semiconducting, dielectric, glassy, polymeric, gaseous, etc. They can be bulk-like, as outlined in an earlier article in SVC Bulletin, spring issue, pp. 36–45, 2018, and they can be based on thin surface coatings as discussed below. The purpose of both articles is to provide a bird’s eye view over a wide class of materials of rising importance rather than giving detailed accounts of highly specialized topics. The two articles are based on a recent paper in Solar Energy Materials and Solar Cells 180, pp. 213–226, 2018 (with permission from Elsevier).

  • 103.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Azens, A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Isidorsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Kharrazi, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Kullman, Lisen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Lindström, T
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Ribbing, Carl-Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Rönnow, D
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Veszelei, M
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Towards the smart window: progress in electrochromics1997In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 218, p. 273-279Article in journal (Refereed)
    Abstract [en]

    Electrochromic devices have the ability to produce reversible and persistent changes of their optical properties. The phenomenon is associated with joint ion and electron transport into/out of an electrochromic thin film, in most cases being a transition metal oxide. This paper outlines the various applications of such devices in smart windows suitable for energy-conscious architecture, in variable-reflectance mirrors, and in display devices. Critical materials issues and design concepts are discussed. The paper also covers two specific research topics: computed electronic structure of crystalline WO3 incorporating ionic species, showing how reflectance modulation emerges from a first-principles calculation; and Li+ dynamics in heavily disordered Ti oxide, illustrating how diffusion constants derived from impedance spectroscopy can be reconciled with the Anderson—Stuart model.

  • 104.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lansåker, Pia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Oxide-based electrochromics: Advances in materials and devices.2011In: Materials Research Society Symposium Proceedings, vol. 1328, Materials Research Society, 2011, p. 11-22Conference paper (Refereed)
  • 105.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ji, Yu -Xia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shu-Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromics and thermochromics for energy efficient fenestration: Functionalities based on nanoparticles of In2O3:Sn and VO22014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 559, p. 2-8Article in journal (Refereed)
    Abstract [en]

    Windows incorporating electrochromic (EC) and thermochromic (TC) materials are of great interest for today's and tomorrow's buildings and can create energy efficiency jointly with indoor comfort. This paper summarizes several recent studies and shows that nanoparticles of transparent conducting oxides-specifically In2O3: Sn (ITO) and thermochromic VO2-can lead to desirable functionalities. We consider three examples: (i) the use of ITO nanoparticles in conventional polaronic EC devices in order to suppress near-infrared solar transmittance, (ii) performance limits for plasmonic EC devices based on ITO nanoparticles, and (iii) ITO-VO2-based nanocomposites combining low thermal emittance with TC properties. We also consider Mg doping of VO2 to enhance the luminous transmittance and Al2O3/VO2 double layers with improved durability. Both experimental and theoretical results are reported. (C) 2013 Elsevier B. V. All rights reserved.

  • 106.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Progress in Chromogenic Materials and Devices: New Data on Thermochromic Vanadium-Oxide-Based Materials and on Electrochromic Nickel-Tungsten-Oxide Based Foils2010Conference paper (Refereed)
  • 107.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Avendaño, Esteban
    Chromogenics for Sustainable Energy: Some Advances in Thermochromics and Electrochromics2010In: Advances in Science and Technology, ISSN 1662-0356, Vol. 75, p. 55-64Article in journal (Refereed)
    Abstract [en]

    Chromogenic materials are able to change their optical properties in response to external stimuli such as temperature (in thermochromic materials) and electrical charge insertion (in electrochromic materials). Below we review some recent advances for these types of materials. Specifically we first discuss the limitations of thermochromic VO2 films for energy efficient fenestration and show from calculations that nanocomposites containing VO2 can have superior properties and display high luminous transmittance and large temperature-dependent solar transmittance modulation. Even better results may be found for nanoparticles of VO2:Mg. In the second part of the paper we survey some recent progress for electrochromic devices and show that W oxide films have increased coloration efficiency when some Ni oxide is added. We also present initial results for flexible electrochromic foils produced by roll-to-roll coating and continuous lamination.

  • 108.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru R.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    von Kraemer, S.
    Georén, P.
    Advances in chromogenic materials and devices2010In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 518, no 11, p. 3046-3053Article in journal (Refereed)
    Abstract [en]

    Chromogenic materials allow the transmittance of visible light and solar energy to be varied under the action of an external stimulus This paper first discusses buildings related energy savings that can be accomplished by chromogenic technologies, and their beneficial effects on comfort issues We then summarize recent work on thermochromic VO2-based thin films with particular attention to multi-layers of VO2 and TiO2 and to new VO2 Mg films for which the doping gives significantly lowered absorption of visible light The final part covers electrochromic materials and devices with foci on coloration efficiency and on durability issues for foil-type constructions based on films of WO3 and NiO.

  • 109.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Green, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    von Kræmer, S.
    Georén, P.
    Advances in chromogenic materials and devices2009In: Proceedings of 6th International Symposium on Transparent Oxide Thin Films for Electronics and Optics, April 15-17, 2009, Tokyo Fashin Town Building, Japan, 2009, p. 27-36Conference paper (Refereed)
  • 110.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ji, Yu -Xia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Montero, José Amenedo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromic Fenestration Based on VO2:: Finally a Technology of Practical Interest?2016Conference paper (Refereed)
    Abstract [en]

    Vanadium-dioxide-based thermochromic thin films and nanoparticle composites can have significant transmittance for visible light, Tlum, while they are able to transmit more near-infrared solar radiation at τ < τc than at τ > τc, where τ denotes temperature and τc ≈ 68 °C. It has been realized for many years that these properties are of principle interest for energy efficient fenestration, but the technology has been slow to mature. This paper summarizes the state-of-the-art and points at the many advances that have been made during recent years. Specifically, we discuss how to use doping to adjust τc to room temperature and to increase Tlum, how to use nanomaterials to enhance the solar energy transmittance modulation and Tlum, and how to prepare nanoparticle composites by sputtering. We also discuss thermochromic light scattering, which is a recently discovered phenomenon.

  • 111.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ji, Yu-Xia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Montero, José Amenedo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromic vanadium-dioxide-based thin films and nanoparticles: Survey of some buildings-related advances2016In: Journal of Physics: Conference Series: INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures, Institute of Physics Publishing (IOPP), 2016, Vol. 764, article id 012002Conference paper (Refereed)
    Abstract [en]

    Today’s architecture uses large glazings (windows and glass facades) to obtain good indoors–outdoors contact and day-lighting. However glazings offer challenges and often lead to excessive solar energy inflow and thereby a need for energy-demanding space cooling. This paper summarizes recent work on thermochromic (TC) materials intended for energy-efficient buildings and outlines how vanadium-dioxide-based thin films and nanoparticle composites can be used in TC glazings which admit more solar energy below a comfort temperature than above this temperature, so that the cooling need is diminished, while the transmittance of visible light remains high. We also report on some very recent work on TC light scattering.

  • 112.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lansåker, Pia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Avendano, Esteban
    Progress in Chromogenics: New Results for Electrochromic and Thermochromic Materials and Devices2009In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 93, no 12, p. 2032-2039Article in journal (Refereed)
    Abstract [en]

    Chromogenic device technology can be used to vary the throughput of   visible light and solar energy for windows in buildings as well as for   other see-through applications. The technologies can make use of a   range of "chromic" materials - such as electrochromic, thermochromic,   photochromic, etc - either by themselves or in combinations. The first   part of this paper points at the great energy savings that can be   achieved by use of chromogenic technologies applied in the built   environment, and that these savings can be accomplished jointly with   improved indoor comfort for the users of the building. Some recent data   are presented on a foil-type electrochromic device incorporating   tungsten oxide and nickel oxide. In particular, we consider the   possibilities of controlling the near-infrared transmittance an   optimize this property for specific climates. To that end we discuss   Au-based transparent conductors for electrochromics as well as   high-transmittance thermochromic multilayer films incorporating VO2 and TiO2.

  • 113.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Behagligt inne med smarta fönster2009In: Miljöforskning, ISSN 1650-4925, no 5, p. 18-19Article in journal (Other (popular science, discussion, etc.))
  • 114.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Pleasant indoors with smart windows2009In: Sustainability, ISSN 1654-8329, no 4Article in journal (Other (popular science, discussion, etc.))
  • 115.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Solar energy materials for thermal applications: A primer2018In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 180, p. 213-226Article in journal (Refereed)
    Abstract [en]

    Solar energy materials have properties that are tailored to the characteristics of the electromagnetic radiation in our natural surroundings, specifically its spectral distribution, angle of incidence and intensity. This tailoring can be made with regard to solar irradiation, thermal emission, atmospheric absorption, visible light, photosynthetic efficiency and more. Solar energy materials can be of many kinds, e.g., metallic, semiconducting, dielectric, glassy, polymeric, gaseous, etc. In particular, thin surface coatings of solar energy materials may exhibit the desired properties in their own right or may yield such properties when backed by an appropriate substrate. This article surveys a number of topics related to thermal applications such as solar thermal converters, transparent thermal insulators, devices for radiative cooling by exposure to the clear sky, and windows and glass facades with static or dynamic properties. The purpose of the present paper is to provide a bird's eye view over a wide class of materials of rising importance rather than giving detailed accounts of highly specialized topics.

  • 116.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings2017In: Buildings, ISSN 2075-5309, E-ISSN 2075-5309, Vol. 7, no 1, article id 3Article, review/survey (Refereed)
    Abstract [en]

    Today's advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facadesjointly known as glazingssince current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO2), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.

  • 117.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Azens, A.
    Electrochromics: Fundamentals and energy-related applications of oxide-based devices2007In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 89, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    We first introduce electrochromic (EC) device technology, which uses transparent conducting oxides as one of its critical components, and consider how this technology can be employed to obtain urgently needed energy savings for modern buildings. The discussion then focuses on two of the most suitable EC materials, WO3 and NiO; we cover recent advances in basic physics and chemistry as well as the properties of flexible foil-type devices combining the two oxides. The final part of the paper provides a broader, more general overview of chromogenic materials.

  • 118.
    Granqvist, Claes-Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mlyuka, Nuru
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    New Thermochromic Coatings for Energy Efficient Windows2009In: Society of Vacuum Coaters 52nd Annual Technical Conference Proceedings, 2009, p. 30-35Conference paper (Refereed)
  • 119.
    Green, S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Mixed Nickel Tungsten Oxide2009Conference paper (Refereed)
  • 120. Green, S. V.
    et al.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lithium Intercalation into Dark Electrochromic Nickel Oxide Thin Films2011Conference paper (Refereed)
  • 121.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Backholm, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Georen, P
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel Oxide and Tungsten Oxide Thin Films: Ion Intercalation from Different Electrolytes2009In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 93, no 12, p. 2050-2055Article in journal (Refereed)
    Abstract [en]

    Electrochromic (EC) NiOz and WOy thin films were prepared by sputtering   and were used in a feasibility study aimed at investigating mixtures of   these two oxides. The object was to identify a suitable electrolyte,   compatible with both NiOz and WOy. To that end we carried out cyclic   voltammetry (CV) in potassium hydroxide (KOH), propionic acid, and   lithium perchlorate in propylene carbonate (Li-PC). WOy could be   coloured in propionic acid and Li-PC, while NiOz could be coloured only   in KOH. Both films showed best stability in Li-PC, which hence is well   suited for further studies of mixed NiOz and WOy.

  • 122.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel Doped Tungsten Oxide2009In: Advances in Transparent Electronics: From Materials to Devices, 2009Conference paper (Refereed)
  • 123.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and optical properties of electrochromic tungsten-containing nickel oxide films2014In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, p. 248-259Article in journal (Refereed)
    Abstract [en]

    Electrochromic NixW1-x oxide thin films with 0.5 < x < 1, were deposited by co-sputtering from one Ni and one W metal target. The different compositions were structurally characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The optical and electrochemical properties were investigated by spectrophotometry and cyclic voltammetry in LiClO4 dissolved in propylene carbonate. It was found that the samples turned amorphous upon W addition and that the NixW1-x oxides probably consisted of hydrated Ni oxides and NiWO4. The charge insertion/extraction and optical modulation was unfortunately very modest. Moreover, an aging effect, resulting in a strong bleaching process of the samples was observed. Nevertheless, it was found that, for electrochromic applications, the advantage of W addition was that the transparency at the bleached state was enhanced for all compositions and for wavelengths of 400 nm up to NIR.

  • 124.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in Nickel-Tungsten Oxides.2012In: IME-10. Tenth International meeting on Electrochromism, Holland, MI USA, August 12-16, 2012., 2012, p. 17-Conference paper (Refereed)
  • 125.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kuzmin, A
    Institute of Solid State Physics, University of Latvia, Riga, Latvia.
    Purans, J
    Institute of Solid State Physics, University of Latvia, Riga, Latvia.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and composition of sputter-deposited nickel-tungsten oxide films2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 7, p. 2062-2066Article in journal (Refereed)
    Abstract [en]

    Films of mixed nickel-tungsten oxide, denoted NixW1-x oxide, were prepared by reactive DC magnetron co-sputtering from metallic targets and were characterized by Rutherford backscattering spectrometry. X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x<0.50 the films comprised a mixture of amorphous WO3 and nanosized NiWO4, at x = 0.50 the nanosized NiWO4 phase was dominating, and at x>0.50 the films contained nanosized NiO and NiWO4.

  • 126.
    Green, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kuzmin, Alexei
    Purans, Juris
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structure and composition of sputter-deposited nickel-tungsten oxide films2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 7, p. 2062-2066Article in journal (Refereed)
    Abstract [en]

    Films of mixed nickel-tungsten oxide, denoted NixW1−x oxide, were prepared by reactive DC magnetron cosputtering from metallic targets and were characterized by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, X-ray diffractometry and Raman spectroscopy. A consistent picture of the structure and composition emerged, and at x<0.50 the films comprised a mixture of amorphous WO3 and nanosized NiWO4, at x=0.50 the nanosized NiWO4 phase was dominating, and at x>0.50 the films contained nanosized NiO and NiWO4.

  • 127.
    Green, Sara V
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Pehlivan, Esat
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism in sputter deposited nickel-containing tungsten oxide films2012In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 99, p. 339-344Article in journal (Refereed)
    Abstract [en]

    Thin films of NixW1-x oxide were prepared by reactive DC magnetron co-sputtering and were investigated by optical and electrochemical measurements. Electrochromism was found only for 0<x<0.3 but not for 0.3<x<0.6, though films with x~0.4 could still sustain reversible charge insertion. The coloration efficiency was largest for 0.10<x<0.15. The charge capacity of the NixW1-x oxide films decreased upon increasing the value of x as a consequence of a decreasing ion diffusion coefficient leading to slower kinetics.

  • 128.
    Green, Sara V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Watanabe, M.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Oka, N.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Shigesato, Y.
    Graduate School of Science and Engineering, Aoyama Gakuin University, Kanagawa, Japan.
    Electrochromic properties of nickel oxide based thin films sputter deposited in the presence of water vapor2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 10, p. 3839-3842Article in journal (Refereed)
    Abstract [en]

    Electrochromic nickel oxide based thin films were prepared by reactive RF magnetron sputtering from metallic nickel in the presence of Ar, O-2 and H2O. The water vapor led to enhanced optical modulation and charge capacity. At a wavelength of 550 nm the bleached state transmittance was 0.73 and the transmittance for the colored state was 0.28 and 0.15 for water partial pressures of p(H2O)<10(-3) Pa and p(H2O) similar to 7 x 10(-2) Pa, respectively. The charge densities were 14 and 25 mC/cm(2) for p(H2O)<10(-3) Pa and P-H2O similar to 7 x 10(-2) Pa, respectively. The coloration efficiency was decreased with increased water partial pressure, from about 0.07 to 0.06 cm(2)/mC. Preliminary results show that the H2O promotes an amorphous structure and makes the films increasingly hydrous. 

  • 129.
    Greenwood, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gevert, Börje S.
    Otterstedt, Jan-Erik
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Vargas, William
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Novel nano-composite particles: titania-coated silica cores2010In: Pigment & Resin Technology, ISSN 0369-9420, E-ISSN 1758-6941, Vol. 39, no 3, p. 135-140Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to develop methods to produce white composite pigments consisting of a silica core with a titania shell. Design/methodology/approach - Silica cores were coated with titanium dioxide (TiO2) via forced hydrolysis of a solution prepared from titanium tetrachloride (TiCl4). The morphology, surface charge and particle size of obtained composite particles were studied. Findings - Dispersions of well-dispersed composite particles, having silica cores of uniform size in the range from 300 to 500 nm with a homogeneous titania coating are obtained. The coating thickness corresponded to 150-400 per cent by weight of titania based on the core. Modification of the silica core by incorporation of 1.5 aluminosilicate sites per square nanometre of core surface proves to be favourable in achieving a homogeneous coating on the silica core. Deposition of such titania coating is also favoured by agitating the dispersion well, keeping electrolyte content low, maintaining pH at 2.0 and the temperature at 75 degrees C during the coating process. Research limitations/implications - Only TiCl4 is used as titania source. In addition, only silica cores obtained by Stober synthesis are used while commercially available silica solutions made from sodium silicate are not used. Practical implications - The process offers a method of producing a white composite pigment with a narrow particle size distribution in order to maximise light scattering as well as using a core with lower density than the shell. This kind of particle would be of interest for coating applications and white inorganic inks. Originality/value - The developed method provides a straightforward process to produce well-defined composite particles.

  • 130.
    Gómez, M.M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Beermann, N.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lu, J.
    Olsson, E.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Niklasson, G A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dye-sensitized sputtered titanium oxide films for photovoltaic applications: influence of the O2/Ar gas flow ratio during the deposition2003In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 76, no 1, p. 37-56Article in journal (Refereed)
    Abstract [en]

    Titanium oxide films were prepared by reactive DC magnetron sputtering onto SnO2:F coated glass substrates. The O-2/Ar gas flow ratio was kept at a constant value Gamma during the deposition, and a series of films were deposited with 0.050 < Gamma < 0.072. Structural studies were performed by X-ray diffraction and transmission electron microscopy; the structure displayed penniform features with a clear dependence on F. Charge transport in the films was evaluated by use of time-resolved photocurrents; a diffusion model was fitted to the experimental data and two different transport mechanisms were proposed depending on the film stoichiometry. Dye sensitization in cis-dithiocyanato-bis(2,2'-bipyridyl-4,4'-dicarboxylate) ruthenium (II) was performed to evaluate incident photon-to-current conversion efficiency and solar cell properties of the films. These parameters showed a clear dependence on Gamma. Optical measurements gave evidence for the presence of polaron absorption for the film deposited at Gamma = 0.050.

  • 131.
    Hu, Shuanglin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Scheicher, Ralph H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Optical properties of Mg-doped VO2: Absorption measurements and hybrid functional calculations2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 20, p. 201902-Article in journal (Refereed)
    Abstract [en]

    Mg-doped VO2 thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < <(h)over bar>omega < 3.5 eV energy range. Clear evidence was found for a widening of the main band gap from 1.67 to 2.32 eV as the Mg/(V + Mg) atomic ratio went from zero to 0.19, thereby significantly lowering the luminous absorption. This technologically important effect could be reconciled with spin-polarized density functional theory calculations using the Heyd-Scuseria-Ernzerhof [Heyd et al., J. Chem. Phys. 118, 8207 (2003); ibid. 124, 219906 (2006)] hybrid functional. Specifically, the calculated luminous absorptance decreased when the Mg/(V + Mg) ratio was increased from 0.125 to 0.250.

  • 132.
    Isidorsson, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Gåhlin, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Ion transport in porous Sn oxide films: Cyclic voltammetry interpreted in terms of a fractal dimension1996In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 99, no 2, p. 109-111Article in journal (Refereed)
    Abstract [en]

    Sn oxide films, made by reactive r.f. magnetron sputtering, were studied in a Li+-conducting electrolyte. Cyclic voltammograms taken at different sweep rates were interpreted in terms of a unique structural parameter related to the fractal dimension of a self-affine surface relief.

  • 133.
    Isidorsson, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Gåhlin, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Physical and Electrochemical properties of Li-intercalated Sn oxide films made by sputtering1995In: Ionics (Kiel), ISSN 0947-7047, E-ISSN 1862-0760, Vol. 1, no 5-6, p. 400-405Article in journal (Refereed)
    Abstract [en]

    Sn oxide films were made by reactive rf magnetron sputtering under conditions that led to both electronic and ionic conductivity. The film structure was studied by X-ray diffraction and Atomic Force Microscopy (AFM). Li+ intercalation produced electrochromism with coloration efficiency peaked in the infrared. Cyclic voltammograms taken at different sweep rates were interpreted in terms of a unique structural parameter related to the fractal dimension of a self-affine surface relief and in excellent agreement with the fractal dimension as obtained with AFM. Mössbauer spectroscopy was used to determine the valence state of the Sn-atoms; a change from Sn4+ to Sn2+ was detected after electrochemical intercalation of Li+.

  • 134.
    Ji, Y.- X.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Boman, M.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromics for Energy Efficient Buildings: Thin Surface Coatings and Nanoparticle Composites2015In: Nano- and Biotech-Based Materials for Energy Building Efficiency / [ed] F. Pacheco-Torgal, C. Buratti, S. Kalaiselva, C.G. Granqvist, V. Ivanov, London, UK: Springer London, 2015, p. 71-96Chapter in book (Refereed)
  • 135. Ji, Y.- X.
    et al.
    Li, S.- Y.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Effect of Al Oxide Top Coatings on the Durability of Thermochromic VO2 Thin Films2014In: Abstracts European Materials Research Society (E-MRS) Spring Meeting: Abstract L VIII-17, 2014, Vol. L VIII-17Conference paper (Refereed)
  • 136.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Boman, M.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromics for Energy Efficient Buildings: Thin Surface Coatings and Nanoparticle Composites2016In: Nano- and Biotech-Based Materials for Energy Building Efficiency / [ed] F. Pacheco-Torgal, C. Buratti, S. Kalaiselvam, C.G. Granqvist and V. Ivanov, London, UK: Springer London, 2016, p. 71-96Chapter in book (Refereed)
  • 137.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Li, Shu-Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Durability of thermochromic VO2 thin films under heating and humidity: Effect of Al oxide top coatings2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 562, p. 568-573Article in journal (Refereed)
    Abstract [en]

    An explorative study was performed on sputter-deposited thermochromic (TC) VO2 films exposed to heat treatment under dry and humid conditions. The ambient conditions were harsh and 80-nm-thick VO2 films were rapidly converted to non-TC V2O5. It was found that a 30-nm-thick sputter-deposited Al oxide top coating provided good protection and delayed the oxidation for more than one day upon heating in dry air at 300 degrees C and that protection occurred for several days at 95% relative humidity and 60 degrees C. The thickness of the Al oxide was important and, expectedly, increased thickness yielded enhanced protection. Our results are important for TC fenestration as well as for other technical applications.

  • 138.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Direct Formation of Thermochromic Composite Films of VO2 Nanoparticles in SiO2 Hosts2016In: 2016 Ieee 16th International Conference On Nanotechnology (IEEE-NANO), 2016, p. 823-825Conference paper (Refereed)
    Abstract [en]

    Vanadium dioxide (VO2) is a key material for modern thermochromic energy-efficient window coatings. Nanocomposite VO2-SiO2 films were fabricated by reactive magnetron sputtering. VO2 nanoparticles with grain sizes of about 100 nm were distributed uniformly in the SiO2 host, and the composite film showed excellent thermochromic properties with plasmonic effect.

  • 139.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Boman, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Thermochromic VO2 films by thermal oxidation of vanadium in SO22016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 144, p. 713-716Article in journal (Refereed)
    Abstract [en]

    Thermochromic films of VO2 were prepared by a two-step procedure: Sputtering was first used to deposit metallic vanadium, and such layers were subsequently oxidized in SO2 at a temperature in the 600-650 degrees C range. X-ray diffraction, Raman spectroscopy, measurements of temperature-dependent electrical resistance, and spectrophotometric transmittance data at different temperatures were employed to demonstrate that the films consisted of polycrystalline VO2 with good thermochromism, especially when oxidized at the highest temperature. Oxidation in SO2 is able to produce VO2 without the stringent process control that can be an obstacle for making VO2 by oxidation in O-2.

  • 140.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Durability of VO 2 -based thin films at elevated temperature: Towards thermochromic fenestration2014In: 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, 2014, p. UNSP 012005-Conference paper (Refereed)
    Abstract [en]

    An explorative study was performed on sputter-deposited thermochromic VO 2 films with top coatings of Al oxide and Al nitride. The films were exposed to dry air at a high temperature. Bare 80-nm-thick VO 2 films rapidly converted to non-thermochromic V 2 O 5 under the chosen conditions. Al oxide top coatings protected the underlying VO 2 films and, expectedly, increased film thickness yielded improved protection. Specifically, it was found that a 30-nm-thick sputter-deposited Al oxide top coating delayed the oxidation by more than one day upon heating at 300°C. The results demonstrate the importance of protective layers in thermochromic windows for practical application.

  • 141.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thermochromic VO2 Films by Thermal Oxidation of Vanadium in SO2: Thermodynamic Feasibility and Experimental Verification2016In: Program & Exhibit Guide: Abstract EE 15.3.15, 2016, p. 1-Conference paper (Refereed)
  • 142.
    Ji, Yu-Xia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Boman, M.
    Thermochromic VO2 Films by Thermal Oxidation of Vanadium in SO22016In: Solar Energy Materials and Solar Cells Journal, no 144, p. 713-716Article in journal (Refereed)
  • 143. Johansson, M.
    et al.
    Alves, P.
    Green, S.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Near-infrared electrochromism in crystalline tungsten oxide thin films2010Conference paper (Refereed)
  • 144.
    Johansson, Malin B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Baldissera, Gustavo
    Kungliga Tekniska Högskolan.
    Valyukh, Iryna
    Linköpings Universitet.
    Persson, Clas
    Kungliga Tekniska Högskolan.
    Arwin, Hans
    Linköpings Universitet.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations2013In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 20, p. 205502-Article in journal (Refereed)
    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.

  • 145.
    Johansson, Malin B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kristiansen, Paw
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Baldissera, G
    Duda, Laurent C
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Persson, C
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Band gap states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy, optical absorption spectroscopy and density functional calculationsManuscript (preprint) (Other academic)
  • 146. Johansson, Malin B
    et al.
    Kristiansen, Paw
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Baldissera, G
    Duda, Laurent C
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Persson, C
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sub-band gap electronic states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy, optical absorption spectroscopy and density functional calculationsManuscript (preprint) (Other academic)
  • 147.
    Johansson, Malin B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mattsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lindquist, Sten-Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    The Importance of Oxygen Vacancies in Nanocrystalline WO3−x ThinFilms Prepared by DC Magnetron Sputtering for Achieving High Photoelectrochemical Efficiency2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 13, p. 7412-7420Article in journal (Refereed)
    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.

  • 148.
    Johansson, Malin B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structural and optical properties of visible active photocatalytic WO3 thin films prepared by reactive dc magnetron sputtering2012In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 27, no 24, p. 3130-3140Article in journal (Refereed)
    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.

  • 149.
    Johansson, Malin B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Xie, Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Thyr, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Göthelid, Mats
    KTH Royal Institute of Technology.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Porous Fractals of MAPbI3 Perovskite: Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation2018Conference paper (Refereed)
    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.

  • 150.
    Johansson, Malin B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zietz, Burkhard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Niklasson, Gunnar A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Optical properties of nanocrystalline WO3 and WO3-x thin films prepared by DC magnetron sputtering2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 21, p. 213510-Article in journal (Refereed)
    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.

1234567 101 - 150 of 378
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