| 1. |
- Granqvist, C.-G., et al.
(författare)
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Recent advances in electrochromics for smart windows applications
- 1998
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Ingår i: Solar Energy. - 0038-092X .- 1471-1257. ; 63:4, s. 199-216
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Electrochromic smart windows are able to vary their throughput of radiant energy by low-voltage electrical pulses. This function is caused by reversible shuttling of electrons and charge balancing ions between an electrochromic thin film and a transparent counter electrode. The ion transport takes place via a solid electrolyte. Charge transport is evoked by a voltage applied between transparent electrical conductors surrounding the electrochromic film/electrolyte/counter electrode stack. This review summarizes recent progress concerning: (i) calculated optical properties of crystalline WO3, (ii) electrochromic properties of heavily disordered W oxide and oxyfluoride films produced by reactive magnetron bias sputtering, (iii) novel transparent reactively sputter-deposited Zr-Ce oxide counter electrodes and (iv) a new proton-conducting antimonic-acid-based polymer electrolyte. Special in depth presentations are given on elastic light scattering from W-oxide-based films and of electronic band structure effects affecting opto-chronopotentiometry data in Zr-Ce oxide. The review also contains some new device data for an electrochromic smart window capable of very high optical transmittance.Electrochromic smart windows are able to vary their throughput of radiant energy by low-voltage electrical pulses. This function is caused by reversible shuttling of electrons and charge balancing ions between an electrochromic thin film and a transparent counter electrode. The ion transport takes place via a solid electrolyte. Charge transport is evoked by a voltage applied between transparent electrical conductors surrounding the electrochromic film/electrolyte/counter electrode stack. This review summarizes recent progress concerning: (i) calculated optical properties of crystalline WO3, (ii) electrochromic properties of heavily disordered W oxide and oxyfluoride films produced by reactive magnetron bias sputtering, (iii) novel transparent reactively sputter-deposited Zr-Ce oxide counter electrodes and (iv) a new proton-conducting antimonic-acid-based polymer electrolyte. Special in depth presentations are given on elastic light scattering from W-oxide-based films and of electronic band structure effects affecting opto-chronopotentiometry data in Zr-Ce oxide. The review also contains some new device data for an electrochromic smart window capable of very high optical transmittance.
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| 2. |
- Granqvist, Claes-Göran, et al.
(författare)
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Towards the smart window : progress in electrochromics
- 1997
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Ingår i: Journal of Non-Crystalline Solids. - 0022-3093 .- 1873-4812. ; 218, s. 273-279
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Kullman, Lisen
(författare)
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Components of smart windows : Investigations of electrochromic films, transparent counter electrodes and sputtering techniques
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In smart windows, the transmittance of visible and near infrared radiation can be reversibly and persistently modulatcd by an applied voltage pulse (~2 V). The micrometer-thick multi-layer structure contains two electrodes capable of charge insertion. One of these electrodes must be electrochromic; usually it consists of tungsten oxide. The other, i.e., the counter electrode, can either be a complementary coloring electrochromic material or a material remaining transparent upon charge insertion. The lack of a suitable counter electrode has been an obstacle for commercialization of electrochromic devices.This thesis investigates the optical modulation mechanisms and deterioration of electrochromic materials, including oxidas of W, Mo, Ti, La, Ce, Pr, Hf, Zr, Ni, Cr, and their mixtures. New counter electrodes have been developed. The materials were deposited by multi-target sputtering, which is a method well suited for operation in metallic target-oxidized substrate mode. The materials were characterized by physical, optical and electrochemical methods.To study the interface roughness, light scattering was measured with a specially designed total integrated scattering instrument. Experiments on tungsten-oxide-based films show that optical modulation and electrochemical degradation do not change the interface topography. Using electrochromic films in light scattering measurements offers a new possibility to study cross-correlation since the contribution to the scattering from different interfaces can be separated.The coloration mechanisms are discussed in terms of the electron structure of the materials. Optical and electrochemical measurements indicate that the cerium 4f states can be filled without causing optical absorption in oxides containing cerium. For nickel oxide and chromium oxide it is suggested that the metallic non-bonding character of electron states at the top of the valence band is essential for the anodic electrochromism of these materials.Devices exhibiting good performance were assembled using tungsten oxide, various counter electrodes, and electrolytes of lithium polymer and proton composites. Transparent nickel-oxide-containing devices can be assembled without pretreatment of the components. Zirconium-cerium oxide is fully transparent throughout the whole visible range and can be employed in devices where a high transmittance is essential.
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| 5. |
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| 6. |
- Niklasson, Gunnar A., et al.
(författare)
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Surface roughness of pyrolytic tin dioxide films evaluated by different methods
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 359:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- The scaling of surface roughness in thin spray pyrolyzed fluorinated tin dioxide films of different thicknesses was obtained from atomic force microscopy. The data show that, within experimental uncertainties, the effective dimensionality of the surface is 2; hence no evidence of fractal surface roughness was found. Other methods – based upon light scattering and cyclic voltammetry – gave additional information on the surface topography. Cyclic voltammetry measurements show that the reaction sites on the surface are distributed in a fractal structure and may be identified with hillocks seen in surface reliefs.
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| 7. |
- Teijido, Oscar, et al.
(författare)
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Affixing N-terminal α-Helix to the Wall of the Voltage-dependent Anion Channel Does Not Prevent Its Voltage Gating
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:14, s. 11437-11445
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Tidskriftsartikel (refereegranskat)abstract
- The voltage-dependent anion channel (VDAC) governs the free exchange of ions and metabolites between the mitochondria and the rest of the cell. The three-dimensional structure of VDAC1 reveals a channel formed by 19 beta-strands and an N-terminal alpha-helix located near the midpoint of the pore. The position of this alpha-helix causes a narrowing of the cavity, but ample space for metabolite passage remains. The participation of the N-terminus of VDAC1 in the voltage-gating process has been well established, but the molecular mechanism continues to be debated; however, the majority of models entail large conformational changes of this N-terminal segment. Here we report that the pore-lining N-terminal alpha-helix does not undergo independent structural rearrangements during channel gating. We engineered a double Cys mutant in murine VDAC1 that cross-links the alpha-helix to the wall of the beta-barrel pore and reconstituted the modified protein into planar lipid bilayers. The modified murine VDAC1 exhibited typical voltage gating. These results suggest that the N-terminal alpha-helix is located inside the pore of VDAC in the open state and remains associated with beta-strand 11 of the pore wall during voltage gating.
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| 8. |
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| 9. |
- Veszelei, Monica, et al.
(författare)
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Optical and electrochemical properties of Li+ intercalated Zr-Ce oxide and Hf-Ce oxide films
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83:3, s. 1670-1676
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Tidskriftsartikel (refereegranskat)abstract
- Sputter deposited Zr–Ce oxide and Hf–Ce oxide films were investigated with regard to structure,optical absorption, and electrochemicalproperties.X-raydiffractometry and Rutherford backscattering spectrometry showed that polycrystalline Zr–Ce oxide and Hf–Ce oxide films had cubic crystal structures for 40–100 mol % CeO2 and 50–100 mol % CeO2, respectively. Cyclic voltammetry was performed in an electrolyte of propylene carbonate containing LiClO4. The charge capacity was ∼60mC/cm2μm for a Zr–Ce oxide film with a Ce/Zr atom ratio of ∼13 as well as for a Hf–Ce oxide film with a Ce/Hf atom ratio of ∼2. A decrease of the charge capacity was noted after ∼1000 voltammetric cycles, with the mixed oxide films being far more stable than CeO2. In situ optical transmittance measurements showed that both Zr–Ce and Hf–Ce oxide films remained essentially transparent during Li+ intercalation. Chronopotentiometry measurements were used to elucidate effects of the electronic structure during Li+ intercalation.
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| 10. |
- Veszelei, M, et al.
(författare)
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Zr-Ce Oxides as Candidates for Optically Passive Counter Electrodes
- 1999
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Ingår i: Solar Energy Materials and Solar Cells. - 0927-0248 .- 1879-3398. ; 56:3-4, s. 223-230
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Tidskriftsartikel (refereegranskat)abstract
- Zr-Ce oxide films with compositions from pure Zr oxide to pure Ce oxide were made by reactive DC magnetron co-sputtering. The composition and structure were determined by Rutherford backscattering and X-ray diffraction. Pure Ce oxide films have high charge capacity and are optically passive under charge insertion; they are, however, chemically unstable in an electrolyte of LiClO4 in propylene carbonate. Pure Zr oxide has practically zero charge capacity. Zr-Ce oxide films have high (above 80%) optical transmittance, high charge capacity, and good chemical stability. These films remain fully transparent irrespective of their degree of lithiation, which may be reconciled with electrons accommodating 4f states of Ce.
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