Department of Physics

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Browsing Department of Physics by Author "Avendaño, E."

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    Chromogenics for Sustainable Energy: Some Advances in Thermochromics and Electrochromics
    (2010-10) Granqvist, C. G.; Green, Sara V.; Li, S.-Y.; Mlyuka, N.R.; Niklasson, Gunnar A.; Avendaño, E.
    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.
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    Progress in chromogenics: New results for electrochromic and thermochromic materials and devices
    (2009-12) Granqvist, C. G.; Lansåker, Pia; Mlyuka, N.R.; Niklasson, Gunnar A.; Avendaño, E.
    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 and 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