| 1. |
- Bayrak Pehlivan, I., et al.
(författare)
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A polymer electrolyte with high luminous transmittance and low solar throughput : Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:24, s. 241902-
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Tidskriftsartikel (refereegranskat)abstract
- Chemically prepared similar to 13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneiminelithium 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.
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| 2. |
- Granqvist, Claes-Göran, et al.
(författare)
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Chromogenics for Sustainable Energy : Some Advances in Thermochromics and Electrochromics
- 2010
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Ingår i: Advances in Science and Technology. - 1662-0356. ; 75, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 3. |
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| 4. |
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| 5. |
- Hu, Shuanglin, et al.
(författare)
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Optical properties of Mg-doped VO2 : Absorption measurements and hybrid functional calculations
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:20, s. 201902-
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Tidskriftsartikel (refereegranskat)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 < <(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.
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| 6. |
- Li, Shuyi, et al.
(författare)
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A thermochromic low-emittance coating : Calculations for nanocomposites of In2O3:Sn and VO2
- 2011
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:13, s. 131907-
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Tidskriftsartikel (refereegranskat)abstract
- Calculations based on the Bruggeman effective medium theory were applied to thin films comprising a heavily doped wide band gap semiconductor (specifically In(2)O(3):Sn (ITO)) and VO(2). Films with similar to 20 vol. % of VO(2) 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 similar to 13% and occurs at similar to 35 vol. % VO(2). Coatings of ITO-VO(2) are of interest for energy efficient fenestration.
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| 7. |
- Li, Shuyi, et al.
(författare)
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Nanothermochromics : Calculations for VO2 nanoparticles in dielectric hosts show much improved luminous transmittance and solar energy transmittance modulation
- 2010
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 108:6, s. 063525-
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Tidskriftsartikel (refereegranskat)abstract
- VO2-based films are thermochromic and show infrared reflectance above a "critical" temperature in the vicinity of room temperature. Implementations on energy efficient windows have been discussed for decades but have been severely curtailed since the luminous absorptance is undesirably large and the solar energy transmittance modulation is too small. Here we show by calculations based on effective medium theory that dilute composites with VO2 nanoparticles embedded in hosts with properties mimicking glass or polymer can yield significantly decreased luminous absorption jointly with much enhanced transmittance modulation of solar energy. These results demonstrate that VO2-based nanothermochromics opens new avenues toward energy efficient fenestration.
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| 8. |
- Li, Shuyi, et al.
(författare)
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Nanothermochromics with VO2-based core-shell structures : Calculated luminous and solar optical properties
- 2011
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 109:11, s. 113515-
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Tidskriftsartikel (refereegranskat)abstract
- Composites including VO2-based thermochromic nanoparticles are able to combine high luminous transmittance T-lum with a significant modulation of the solar energy transmittance Delta T-sol 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 Delta T-sol than solid nanoparticles at the expense of a somewhat lowered T-lum. 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)].
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| 9. |
- Li, Shuyi, et al.
(författare)
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Plasmon-induced near-infrared electrochromism based on transparent conducting nanoparticles : Approximate performance limits
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:7, s. 071903-
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Tidskriftsartikel (refereegranskat)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 (similar to 34%), thereby documenting that plasmonic electrochromism is of interest for energy efficient fenestration.
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