Vanadium dioxide nanogrid films for high transparency smart architectural window applications

Liu, Chang; Balin, Igal; Magdassi, Shlomo; Abdulhalim, Ibrahim; Long, Yi

doi:10.1364/oe.23.00a124

Cited by 88 publications

(69 citation statements)

References 27 publications

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“…When the VO 2 layer was under the light illumination, the energy input and output at the VO 2 layer included the absorbed solar energy ( q s ), the heat flux from the reversible SSPT ( q SSPT ), evaporation heat loss ( q evap ), convective heat loss ( q conv ), radiative heat loss ( q rad ), and conductive heat loss ( q cond ). The heat transfer without considering the SSPT should satisfy Equation 11

α q_{s} = q_{rad} + q_{conv} + q_{cond} + q_{evap}

where α is the average solar absorptance of VO 2 layer, which can be calculated using Equation

α = \frac{\int_{280}^{2500} I false(λ false) \times A false(λ false) \times d λ}{\int_{280}^{2500} I false(λ false) \times d λ}

where A (λ) is the solar absorptance at the wavelength of λ. I (λ) is the energy density at the wavelength of λ 38. According to the absorption spectrum in Figure S1b (Supporting Information), the calculated average absorptances of VO 2 layer were α1 = 93.85% and α2 = 92.88% at ≈26.0°C and ≈53.9°C, respectively.…”

Section: Resultsmentioning

confidence: 99%

Bioinspired Temperature Regulation in Interfacial Evaporation

Jiang

Shen

Zhang

et al. 2020

Adv Funct Materials

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Human skin shows self‐adaptive temperature regulation through both enhanced heat dissipation in high temperature environments and depressed heat dissipation in cold environments. Inspired by such thermal regulation processes, an interfacial material system with self‐adaptive temperature regulation in the solar‐driven interfacial evaporation system, which can exhibit automatic temperature oscillation to enable pyroelectricity generation while producing water vapor, is reported. The bioinspired interface system is designed with the combination of a thermochromism‐based temperature regulator consisting of tungsten‐doped vanadium dioxide nanoparticles and a polymeric pyroelectric thin film of polyvinylidene fluoride. Under the simulated solar illumination with power density of 1.1 kW m−2, the bioinspired interfacial evaporation system achieves a self‐adaptive temperature oscillation with the maximum temperature difference of ≈7 °C and this system can simultaneously generate water vapor as well as electricity with an evaporation efficiency of 71.43% and a maximum output electrical power density of 104 µW m−2, respectively. The study demonstrates a design of thermal management at the interface of solar‐driven evaporation system to exhibit a self‐adaptive temperature oscillation and offers an alternative approach for the multifunctional harvesting of solar energy.

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α q_{s} = q_{rad} + q_{conv} + q_{cond} + q_{evap}

where α is the average solar absorptance of VO 2 layer, which can be calculated using Equation

α = \frac{\int_{280}^{2500} I false(λ false) \times A false(λ false) \times d λ}{\int_{280}^{2500} I false(λ false) \times d λ}

Section: Resultsmentioning

confidence: 99%

Bioinspired Temperature Regulation in Interfacial Evaporation

Jiang

Shen

Zhang

et al. 2020

Adv Funct Materials

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“…However, in most case, the reduced τ c by doping is always gained at the expense of lower T lum and smaller Δ T sol . To overcome this trade‐off, many methods including nano‐thermochromic, porous films, photonic crystals structure, biomimetic surface reconstruction, co‐doping, gridded structure, and multilayered antireflective overcoating are developed. Compared with other approaches, nanothermochromic (the oval line marked in Figure a,b), which is to mix VO 2 nanoparticles with a glass or polymer matrix, has the optimum performance from both experiment data and theoretical results .…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Synthesis of VO₂ Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows

Magdassi

Gao

et al. 2017

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Vanadium dioxide (VO ) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical temperature of τ ≈ 68 °C. The abrupt decrease of infrared transmittance in the metallic phase makes VO a potential candidate for thermochromic energy efficient windows to cut down building energy consumption. However, there are three long-standing issues that hindered its application in energy efficient windows: high τ , low luminous transmittance (T ), and undesirable solar modulation ability (ΔT ). Many approaches, including nano-thermochromism, porous films, biomimetic surface reconstruction, gridded structures, antireflective overcoatings, etc, have been proposed to tackle these issues. The first approach-nano-thermochromism-which is to integrate VO nanoparticles in a transparent matrix, outperforms the rest; while the thermochromic performance is determined by particle size, stoichiometry, and crystallinity. A hydrothermal method is the most common method to fabricate high-quality VO nanoparticles, and has its own advantages of large-scale synthesis and precise phase control of VO . This Review focuses on hydrothermal synthesis, physical properties of VO polymorphs, and their transformation to thermochromic VO (M), and discusses the advantages, challenges, and prospects of VO (M) in energy-efficient smart windows application.

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“…[6][7][8][9][10][11][12] Thermochromic materials are the most cost effective smart window materials which can regulate solar transmission automatically without any extra energy input. 14, 15 To attain good thermochromic properties, much efforts such as doping (such as Mg 2+ /W, rare earth doping such as Tb, La and Eu 3+ ), [16][17][18][19][20][21] antireflective coating, 22, 23 nanoporus structuring, [24][25][26] nanoparticle-based composites [27][28][29][30][31][32] and biomimetic nanostructuring 33,34 and nanogriding 35 have been investigated. 13 Inorganic materials based vanadium dioxide (VO 2 ) are common used in smart windows.…”

Section: Introductionmentioning

confidence: 99%

Temperature-responsive hydroxypropylcellulose based thermochromic material and its smart window application

et al. 2016

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Thermochromic materials are the most cost effective smart window materials and the organic hydrogel material has large solar modulating ability (∆T sol ) and the luminous transmittance (T lum ) compared with inorganic VO 2 based materials. Here we report a green and new organic thermochroic material based on hydroxypropylcellulose. With increasing addition of NaCl from 0.5% (wt. %) to 5% (wt. %), the LCST (lower critical solution temperature) could reduce from 42 o C to 30 o C. The morphology change of freeze dried samples below and above LCST proves that the phase change of this hydroxypropylcellulose based hydrogel is due to the solubility change of polymer in water. The fine-tuned recipe can give an outstanding solar modulating ability (∆T sol ) of 25.7% and high averaged T lum of 67.4% with LCST of 38 o C.As shown in Fig 3b, DSC suggests that LCST of pure HPC is 46 o C, with dramatically reduced LCST to 38 o C when adding 0.5% NaCl. When the concentration of NaCl increases to 5%, the τ c of HPC could reduce to 31 o C. In pure HPC, at low temperatures more hydrogen bonds exist between water and the HPC polymer fibers, as the temperature increases, these hydrogen bonds are gradually broken, indicating a continuous phase separation. By adding NaCl, the hydrogen bonding between HPC and water weakens, facilitating the formation of finer polymeric web structure, which acts as a scattering center to block the visible light, resulting in opaque status above LCST. 43 The solar light transmittance (250-2500 nm) profiles at 20 °C and 45 °C are shown in Fig. 3c with fixed thickness of 0.35 mm for all samples. For pure HPC film, it has the highest solar transmittance for both temperatures. T lum(20 °C) for all the samples are larger than 80% remains constant (Table 1). Both T lum(45 °C) and T sol(45 °C) decrease with increasing NaCl concentration from 0.5% to 5%, which is due to the reduced LCST (Fig. 3a). As can be seen from Fig. 3d, the ∆T sol , ∆T IR, ∆T lum were all increased with increasing NaCl concentration. For HPC/NaCl (0.5%) sample, the ∆T sol is 25.7% with high averaged T lum at 67.4 % (Table 1), which indicates it is a suitable candidate for smart window application. Fig. 3 (a). Hysteresis loop for the temperature-dependent transmittance of the HPC/NaCl (0-5%) samples with 0.7 mm thickness at a wavelength 580 nm and the curve of LCST vs NaCl

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Vanadium dioxide nanogrid films for high transparency smart architectural window applications

Cited by 88 publications

References 27 publications

Bioinspired Temperature Regulation in Interfacial Evaporation

Bioinspired Temperature Regulation in Interfacial Evaporation

Hydrothermal Synthesis of VO₂ Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows

Temperature-responsive hydroxypropylcellulose based thermochromic material and its smart window application

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Vanadium dioxide nanogrid films for high transparency smart architectural window applications

Cited by 88 publications

References 27 publications

Bioinspired Temperature Regulation in Interfacial Evaporation

Bioinspired Temperature Regulation in Interfacial Evaporation

Hydrothermal Synthesis of VO2 Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows

Temperature-responsive hydroxypropylcellulose based thermochromic material and its smart window application

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Hydrothermal Synthesis of VO₂ Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows