Durability of thermochromic VO2 thin films under heating and humidity: Effect of Al oxide top coatings

Ji, Yu; Li, Shu-yi; Niklasson, Gunnar A.; Granqvist, Claes‐Göran

doi:10.1016/j.tsf.2014.03.043

Cited by 73 publications

(44 citation statements)

References 52 publications

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“…Chen et al [199] later reported higher T lum of 61.5.%. The durability of the VO 2 films has also been improved by the addition of an Al 2 O 3 over layer which was shown to provide protection against heat (300 • C for one day) and relative humidity of 95% [200].…”

Section: Improving the Aesthetics Of Thermochromic Filmsmentioning

confidence: 99%

Thin Films for Advanced Glazing Applications

et al. 2016

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Functional thin films provide many opportunities for advanced glazing systems. This can be achieved by adding additional functionalities such as self-cleaning or power generation, or alternately by providing energy demand reduction through the management or modulation of solar heat gain or blackbody radiation using spectrally selective films or chromogenic materials. Self-cleaning materials have been generating increasing interest for the past two decades. They may be based on hydrophobic or hydrophilic systems and are often inspired by nature, for example hydrophobic systems based on mimicking the lotus leaf. These materials help to maintain the aesthetic properties of the building, help to maintain a comfortable working environment and in the case of photocatalytic materials, may provide external pollutant remediation. Power generation through window coatings is a relatively new idea and is based around the use of semi-transparent solar cells as windows. In this fashion, energy can be generated whilst also absorbing some solar heat. There is also the possibility, in the case of dye sensitized solar cells, to tune the coloration of the window that provides unheralded external aesthetic possibilities. Materials and coatings for energy demand reduction is highly desirable in an increasingly energy intensive world. We discuss new developments with low emissivity coatings as the need to replace scarce indium becomes more apparent. We go on to discuss thermochromic systems based on vanadium dioxide films. Such systems are dynamic in nature and present a more sophisticated and potentially more beneficial approach to reducing energy demand than static systems such as low emissivity and solar control coatings. The ability to be able to tune some of the material parameters in order to optimize the film performance for a given climate provides exciting opportunities for future technologies. In this article, we review recent progress and challenges in these areas and provide a perspective for future trends and developments.

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Section: Improving the Aesthetics Of Thermochromic Filmsmentioning

confidence: 99%

Thin Films for Advanced Glazing Applications

et al. 2016

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“…The durability of VO2 is also dependent on the deposition technique and is improved for films with high density and large grain size [66,108]. Figure 15 depicts T(λ) for similar VO2 films over-coated with 10 nm and 30 nm of sputter deposited alumina and heat treated at 300 °C for periods in the range 1 < th < 30 h [105]. Clearly the top layer provides good protection, and only the thinnest Al2O3 layer and the longest heat-treatment period yielded some minor decline of the thermochromism.…”

Section: Towards Vo2-based Thin Films For Glazingsmentioning

confidence: 99%

Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings

Granqvist

Niklasson

2016

Buildings

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Today's advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades-jointly known as "glazings"-since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO 2 ), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO 2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO 2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.

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“…Chemically stable oxide films such as Al 2 O 3 [54,85], CeO 2 [86,87], WO 3 [64], etc., have been studied to keep VO 2 away from oxidant like water and O 2 in air. It should be noted that the selected materials to be used as protective layers might affect the optical properties of VO 2 , where dual enhancement in the optical properties and the stability is preferred.…”

Section: Protective Layers For Vo 2 Filmsmentioning

confidence: 99%

“…Al oxide is a typical material that has been investigated as a protection layer for VO 2 coatings. In work reported by Ji et al [54], different thicknesses of Al oxide protective layers have been deposited for VO 2 by DC magnetron sputtering. The durability of the samples was evaluated at a high temperature around 300°C in dry air and highly humid environment.…”

Section: Protective Layers For Vo 2 Filmsmentioning

confidence: 99%

“…However, VO 2 will finally transform into the V 2 O 5 phase in the real environment, which is the most thermodynamically stable phase of vanadium oxide but does not possess the Fig. 1 a The crystallographic structure of VO 2 (rutile) and VO 2 (monoclinic) [53] and b schematic of thermochromic behavior before and after the phase transition [33] thermochromic property [54]. Therefore, environmental stability of VO 2 is a great challenge for practical applications as smart coatings.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dual phase titanium alloy hot forging process design: experiments and numerical modeling

Ducato¹,

Buffa

Fratini³

et al. 2015

Adv. Manuf.

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With an urgent demand of energy efficient coatings for building fenestrations, vanadium dioxide (VO 2 )-based thermochromic smart coatings have been widely investigated due to the reversible phase transition of VO 2 at a critical transition temperature of 68°C, which is accompanied by the modulation of solar irradiation, especially in the near-infrared region. As for commercial applications in our daily life, there are still some obstacles for VO 2 -based smart coatings, such as the high phase transition temperature, optical properties (luminous transmittance and solar modulation ability), environmental stability in a long-time period, as well as mass production. In this review, recent progress of thermochromic smart coatings to solve above obstacles has been surveyed. Meanwhile, future development trends have also been given to promote the goal of commercial production of VO 2 smart coatings.

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Durability of thermochromic VO2 thin films under heating and humidity: Effect of Al oxide top coatings

Cited by 73 publications

References 52 publications

Thin Films for Advanced Glazing Applications

Thin Films for Advanced Glazing Applications

Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings

Dual phase titanium alloy hot forging process design: experiments and numerical modeling

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