Showing papers by "Claes-Göran Granqvist published in 2012"
TL;DR: In this article, the authors discuss basic electrochromic device designs, useful oxide materials and their nanostructures, and elements of a theoretical description of the electro chromic phenomenon.
388 citations
TL;DR: In this paper, the authors used thermochromic VO2-based films for regulating the solar energy transmittance, which can be used for controlling the solar power consumption.
254 citations
TL;DR: In this paper, the main band gap was widened 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.
Abstract: 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 < ħω < 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.
72 citations
TL;DR: In this article, thin films of NixW1-x oxide were prepared by reactive DC magnetron co-sputtering and investigated by optical and electrochemical measurements, finding only for 0
70 citations
TL;DR: A purely electrical version of Maxwell's demon which does not involve mechanically moving parts and has purely electronic controls and is free of the major weakness of the original Szilard engine in not requiring removal and repositioning the piston at the end of the cycle.
Abstract: We introduce a purely electrical version of Maxwell's demon which does not involve mechanically moving parts such as trapdoors, etc. It consists of a capacitor, resistors, amplifiers, logic circuitry and electronically controlled switches and uses thermal noise in resistors (Johnson noise) to pump heat. The only types of energy of importance in this demon are electrical energy and heat. We also demonstrate an entirely electrical version of Szilard's engine, i.e., an information-controlled device that can produce work by employing thermal fluctuations. The only moving part is a piston that executes work, and the engine has purely electronic controls and it is free of the major weakness of the original Szilard engine in not requiring removal and repositioning the piston at the end of the cycle. For both devices, the energy dissipation in the memory and other binary informatics components are insignificant compared to the exponentially large energy dissipation in the analog part responsible for creating new information by measurement and decision. This result contradicts the view that the energy dissipation in the memory during erasure is the most essential dissipation process in a demon. Nevertheless the dissipation in the memory and information processing parts is sufficient to secure the Second Law of Thermodynamics.
48 citations
TL;DR: It is shown that a new method to functionalize wide band gap oxide surfaces by means of photoinduced reactions in reactive gases at elevated substrate temperatures is suggested, which yields surfaces with excellent oleophobic properties, as probed by adhesion of stearic acid.
Abstract: Photoinduced SO2 fixation on anatase TiO2 films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO2 films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO2 gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO2. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photoinduced surface reaction products formed on the TiO2 surfa...
42 citations
TL;DR: In this paper, the major preparation technologies and their characteristics for thin films and nanostructured coatings are surveyed and discussed in detail, and perspectives are given on possible future developments.
40 citations
TL;DR: In this paper, effective medium theory is applied to nanoparticles of In2O3:Sn, which are represented as a free-electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange.
Abstract: Electrochromism can be induced in electrochemically post-treated nanoparticles of wide band gap transparent conductors. We model this recently observed phenomenon by effective medium theory applied to nanoparticles of In2O3:Sn, which are represented as a free-electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This semi-quantitative theory is used to derive approximate performance limits showing that high luminous transmittance (e.g., 60%) can be combined with efficient absorption of solar energy and concomitant low solar transmittance (∼34%), thereby documenting that plasmonic electrochromism is of interest for energy efficient fenestration.
36 citations
TL;DR: In this article, a polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolyte was used for opto-ionic devices such as laminated electrochromic smart windows.
Abstract: Chemically prepared ∼13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.
31 citations
TL;DR: Ion conductivity and optical properties were investigated for polymer electrolytes based on poly (ethyleneimine) and lithium bis(trifluoromethylsulfonyl)imide and also containing up to 9% of 7-nm diameter SiO2 nanoparticles.
31 citations
TL;DR: In this article, a reactive RF magnetron sputtering from metallic nickel in the presence of Ar, O-2 and H2O was used to produce a thin thin film.
TL;DR: In this paper, gold films with thicknesses of 5-±-0.5nm were sputter deposited onto SnO 2 : in-coated glass kept at different temperatures up to 140°C, and similar films, deposited onto substrates at 25-°C.
TL;DR: In this article, the power density spectra variance for the product of two Gaussian band-limited white noises with zero-mean and the same bandwidth was calculated using Rice's random phase oscillator formalism.
Abstract: Products of Gaussian noises often emerge as the result of non-linear detection techniques or as parasitic effects, and their proper handling is important in many practical applications, including fluctuation-enhanced sensing, indoor air or environmental quality monitoring, etc. We use Rice’s random phase oscillator formalism to calculate the power density spectra variance for the product of two Gaussian band-limited white noises with zero-mean and the same bandwidth W. The ensuing noise spectrum is found to decrease linearly from zero frequency to 2W, and it is zero for frequencies greater than 2W. Analogous calculations performed for the square of a single Gaussian noise confirm earlier results. The spectrum at non-zero frequencies, and the variance of the square of a noise, is amplified by a factor two as a consequence of correlation effects between frequency products. Our analytic results are corroborated by computer simulations.
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 (FES) 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/f2 (red) noise spectra.
TL;DR: In this paper, NixW1−x oxide with 0.05 ≤ x ≤ 0.53 were produced by reactive dc magnetron co-sputtering onto Si.
Abstract: Films of NixW1−x oxide with 0.05 ≤ x ≤ 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract ...
01 Jan 2012
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TL;DR: In this article, the power density spectra variance for the product of two Gaussian band-limited white noises with zero-mean and the same bandwidth was calculated using Rice's random phase oscillator formalism.
Abstract: Products of Gaussian noises often emerge as the result of non-linear detection techniques or as a parasitic effect, and their proper handling is important in many practical applications, including in fluctuation-enhanced sensing, indoor air or environmental quality monitoring, etc. We use Rice's random phase oscillator formalism to calculate the power density spectra variance for the product of two Gaussian band-limited white noises with zero-mean and the same bandwidth W. The ensuing noise spectrum is found to decrease linearly from zero frequency to 2W, and it is zero for frequencies greater than 2W. Analogous calculations performed for the square of a single Gaussian noise confirm earlier results. The spectrum at non-zero frequencies, and the variance of the square of a noise, is amplified by a factor two as a consequence of correlation effects between frequency products. Our analytic results is corroborated by computer simulations.
TL;DR: Kish et al. as discussed by the authors showed that an increase of the drift velocity enhances the relative shot noise and decreases the relative residence time fluctuations, which leads to an optimum drift velocity which minimizes the histogram width and maximizes the ability to identify single molecules.
Abstract: Photonic burst histograms can be used to identify single protein molecules in micro/nano-fluidic channels provided the width of the histogram is narrow. Photonic shot noise and residence time fluctuations, caused by longitudinal diffusion, are the major sources of the histogram width. This Communication is a sequel to an earlier Letter of ours [L. L. Kish et al., Appl. Phys. Lett. 99, 143121 (2011)] and demonstrates that, for a given diffusion coefficient, an increase of the drift velocity enhances the relative shot noise and decreases the relative residence time fluctuations. This leads to an optimum drift velocity which minimizes the histogram width and maximizes the ability to identify single molecules, which is an important result for applications.
TL;DR: Kish et al. as discussed by the authors showed that an increase of the drift velocity enhances the relative shot noise and decreases the relative residence time fluctuations, which leads to an optimum drift velocity that minimizes the histogram width.
Abstract: Photonic burst histograms can be used to identify single protein molecules in micro/nano-fluidic channels provided the width of the histogram is narrow. Photonic shot noise and residence time fluctuations, caused by longitudinal diffusion, are the major sources of the histogram width. This paper is a sequel to an earlier one of ours [L. L. Kish et al., Appl. Phys. Lett. 99, 143121 (2011)] and demonstrates that, for a given diffusion coefficient, an increase of the drift velocity enhances the relative shot noise and decreases the relative residence time fluctuations. This leads to an optimum drift velocity that minimizes the histogram width and maximizes the ability to identify single molecules, which is an important result for applications.
10 Jan 2012