Showing papers by "Claes-Göran Granqvist published in 2011"
TL;DR: Li et al. as discussed by the authors presented calculations based on effective medium theory applied to dilute suspensions of core-shell nanoparticles and demonstrated that moderately thin-walled hollow spherical VO2 nanoshells can give significantly higher values of ΔTsol than solid nanoparticles at the expense of a somewhat lowered Tlum.
Abstract: Composites including VO2-based thermochromic nanoparticles are able to combine high luminous transmittance Tlum with a significant modulation of the solar energy transmittance ΔTsol 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 ΔTsol than solid nanoparticles at the expense of a somewhat lowered Tlum. 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)].
100 citations
TL;DR: In this article, mixed nickel-tungsten oxide, denoted NixW1−x oxide, were prepared by reactive DC magnetron cosputtering from metallic targets and were characterized by Rutherford backscattering spectromet.
60 citations
TL;DR: In this article, the growth of gold-based nanoparticles and thin films was studied by depositing gold on glass slides and on SnO2 base layers, where gold was deposited on heated and non-heated substrates, where the latter were also postheated, with a temperature range between 25oC and 140oC.
20 citations
TL;DR: In this article, the authors used X-ray diffraction, scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE) to characterize thin films of NixW1−−x oxides.
20 citations
TL;DR: In this paper, the conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70°C and molar ratios of 20:1 and 400:1.
20 citations
TL;DR: In this article, the Bruggeman effective medium theory was applied to thin films comprising a heavily doped wide band gap semiconductor (specifically In2O3:Sn (ITO)) and VO2 Films with ∼20 vol % of VO2.
Abstract: Calculations based on the Bruggeman effective medium theory were applied to thin films comprising a heavily doped wide band gap semiconductor (specifically In2O3:Sn (ITO)) and VO2 Films with ∼20 vol % of VO2 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 ∼13% and occurs at ∼35 vol % VO2 Coatings of ITO-VO2 are of interest for energy efficient fenestration
20 citations
TL;DR: In this article, the authors survey and show earlier results about three different ways of fluctuation-enhanced sensing of bio agent, 1) the phage-based method for bacterium detection, 2) sensing and evaluating the odors of microbes, and 3) spectral and amplitude distribution analysis of noise in light scattering to identify spores based on their diffusion coefficient.
Abstract: We survey and show our earlier results about three different ways of fluctuation-enhanced sensing of bio agent, 1) the phage-based method for bacterium detection published earlier; 2) sensing and evaluating the odors of microbes; and 3) spectral and amplitude distribution analysis of noise in light scattering to identify spores based on their diffusion coefficient.
16 citations
01 Jan 2011
TL;DR: In this paper, the authors discuss some of these technologies, mainly related to efficient solar energy utilization and to energy savings in the built environment, and discuss their application in the context of renewable energy.
Abstract: New energy sources and increased energy efficiency are important for development, and revolutionary advances in technology appear necessary even to maintain today’s general standard of living and economic prosperity [1]. The problems ahead of us may seem daunting. For example, it has been stated that the warming and precipitation trends due to antropogenic, energy-related climate changes during the past 30 years already claim over 150,000 human lives annually [2, 3]. These climate changes are also expected to be accompanied by more common and/or extreme events such as heatwaves, heavy rainfall, and storms and coastal flooding; there are also fears that non-linear climate responses will lead to breakdown of ocean “conveyor belt” circulation, collapse of major ice sheets, and/or release of large quantities of methane at high latitudes thus intensifying global warming [4]. Adding to the precarious situation, the urgently needed advances in energy related technology must take place for an increasing population, whose growing concentration in mega-cities leads to “heat islands” which tend to aggravate the warming [5] and can increase the urban cooling load by up to 25% compared to the case of surrounding rural areas [6]. By 2050 there will be some ten billion people in the World. Energy must be available to them all, and it has to be clean. New technologies are necessary to accomplish this. Some of these technologies – mainly related to efficient solar energy utilization and to energy savings in the built environment – will be discussed in this Chapter.
14 citations
TL;DR: Soderlund et al. as mentioned in this paper showed that the skewness of the photon number distribution is caused by the longitudinal diffusive component of the motion of the molecules as they traverse the laser beam.
Abstract: The width and shape of photon burst histograms pose significant limitations to the identification of single molecules in micro/nano-fluidic channels, and the nature of these histograms is not fully understood. To reach a deeper understanding, we performed computer simulations based on a Gaussian beam intensity profile with various fluidic channel diameters and assuming (1) a deterministic (noise-free) case, (2) photon emission/absorption noise, and (3) photon noise with diffusion. Photon noise in narrow channels yields a Gaussian burst distribution while additional strong diffusion produces skewed histograms. We use the fluctuating residence time picture [J. Soderlund et al., Phys. Rev. Lett. 80, 2386 (1998)] and conclude that the skewness of the photon number distribution is caused by the longitudinal diffusive component of the motion of the molecules as they traverse the laser beam. In the case of strong diffusion in narrow channels, this effect leads to a log-normal distribution. We show that the same ...
12 citations
TL;DR: This work outlines a computational scheme for optimizing DC magnetron-sputtered TiO₂:Nb-based SSRs tailored for silicon solar cells and finds good agreement of the reflectance with an experimental realization of the optimal SSR.
Abstract: The energy conversion efficiency of a conventional pn junction solar cell decreases as the temperature increases, and this may eventually lead to failures in the photovoltaic system, especially if it uses concentrated solar radiation. In this work, we show that spectrally selective reflector (SSR) surfaces can be important for reducing the heat buildup on passively cooled solar cells. We outline a computational scheme for optimizing DC magnetron-sputtered TiO2:Nb-based SSRs tailored for silicon solar cells and find good agreement of the reflectance with an experimental realization of the optimal SSR. A figure of merit for SSRs has also been derived and applied to the experimental data.
12 citations
TL;DR: In this article, a Gaussian beam intensity profile with various fluidic channel diameters and assuming (i) a deterministic (noise-free) case, (ii) photon emission/absorption noise, and (iii) photon noise with diffusion were performed.
Abstract: The width and shape of photon burst histograms pose significant limitations to the identification of single molecules in micro/nano-fluidic channels, and the nature of these histograms is not fully understood. To reach a deeper understanding, we performed computer simulations based on a Gaussian beam intensity profile with various fluidic channel diameters and assuming (i) a deterministic (noise-free) case, (ii) photon emission/absorption noise, and (iii) photon noise with diffusion. Photon noise in narrow channels yields a Gaussian burst distribution while additional strong diffusion produces skewed histograms. We use the fluctuating residence time picture [Phys. Rev. Lett. 80, 2386-2388 (1998)] and conclude that the skewness of the photon number distribution is caused by the longitudinal diffusive component of the motion of the molecules as they traverse the laser beam. In the case of strong diffusion in narrow channels, this effect leads to a log-normal distribution. We show that the same effect can transform the separate peaks of the photon burst histograms of multiple molecule mixtures into a single log-normal shape.
TL;DR: The thermal properties of VO2 nanoparticles and applications to energy efficient windows were discussed in this paper, where the optical properties and applications were discussed as well as their properties in terms of energy efficiency.
Abstract: Thermochromism of VO2 nanoparticles: Calculated optical properties and applications to energy efficient windows.
TL;DR: In this paper, basic electrochromic (EC) device designs, useful oxide materials and their nanostructures, and elements of a theoretical description of the EC phenomenon are surveyed.
Abstract: Electrochromics is a key “green” technology for massive energy savings in the built environment jointly with indoor comfort. This paper surveys basic electrochromic (EC) device designs, useful oxide materials and their nanostructures, and elements of a theoretical description of the EC phenomenon. It also outlines critical manufacturing technologies and their pros and cons. Focus is on EC foil technology, which is shown capable of mass fabrication via roll-to-roll web coating and continuous lamination.
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TL;DR: In this paper, the relationship between the measurement time window and the statistical error of the measurement data in the simplest case, when the output is the mean-square value of the stochastic signal, was studied.
Abstract: Fluctuation-enhanced sensing comprises the analysis of the stochastic component of the sensor signal and the utilization of the microscopic dynamics of the interaction between the agent and the sensor. We study the relationship between the measurement time window and the statistical error of the measurement data in the simplest case, when the output is the mean-square value of the stochastic signal. This situation is relevant at any practical case when the time window is finite, for example, when a sampling of the output of a fluctuation-enhanced array takes place; or a single sensor's activation (temperature, etc) is stepped up; or a single sensor's output is monitored by sampling subsequently in different frequency windows. Our study provides a lower limit of the relative error versus data window size with different types of power density spectra: white noise, 1/f (flicker, pink) noise, and 1/f^2 (red) noise spectra.