**6. Conclusion and prospects**

nanostructures have been fabricated to enhance the thermochromic properties, and the hydrophobic surface (contact angle 120°) can be achieved with additional overcoat [85]. Fused silica substrates with AR patterns of different periods (0, 210, 440, 580, and 1000 nm) were prepared by reactive ion etching using 2D polystyrene colloidal crystals as a mask. Nipple arrays based

antibacterial property proved by SEM observation results that ZnO-coated samples cause the membrane disruption and cytoplasm leakage of *E. coli* cells and fluorescence staining results that the amounts of viable bacteria are evidently lower on the surface of ZnO-coated films than that of uncoated films (see **Figure 9**). The sterilization mechanism of ZnO films is believed to be attributed to the synergistic effect of released zinc ions and ZnO nanoparticles by elaborately designing a verification experiment. More importantly, the ZnO layer with an

 **smart coatings**

For commercial applications on building fenestrations in our daily life, large-scale produc-

films, magnetron sputtering is the most commonly used method and several works about

bination of energy-saving, antifogging, and self-cleaning functions has been achieved (see

quency reactive magnetron sputtering (MFRMS, see **Figure 10(b)**) system to sputter planar rectangular metal targets in a suitable atmosphere. The proposed structure shows excellent ability to block out infrared irradiation, which causes a temperature reduction of 12°C com-

The magnetron sputtering coating system could be applied in architecture commercial glasses, and the designed large area sputtering cathode can make the coating on large area glass substrates. The optimized design and precise manufacturing can guarantee to get a higher vacuum and a shorter cycle time by using a smaller pumping system. Sputtering is a vacuum process used to deposit thin films on substrates. It is performed by applying a high voltage across a low-pressure gas (usually argon) to create a "plasma," which consists of electrons and gas ions in a high-energy state. During sputtering, energized plasma ions strike the target, which is composed of the desired coating material, and causes atoms from that target to be ejected with enough energy to travel to and bond with the substrate (see



using magnetron sputtering method by Zheng et al. [11], where a com-

(A) multilayer film was prepared on a glass with the area

(A) multilayer film was deposited using medium fre-

have been realized and the additional fluorooctyl triethoxysilane (FOS) overcoat

is also under consideration, while the ZnO layer has been used to

thin films exhibited excellent

and thus promote the


on VO2

VO2

tion of VO2

large-scale TiO2

of 400 × 400 mm2

**Figure 10(a)**). TiO2

**Figure 10(d)**).

/SiO2

16 Emerging Solar Energy Materials

The biosafety of VO2

biosafety.

**5. Large-scale production of VO2**

(R)/VO2

(R)/VO2

pared with the blank glass (see **Figure 10(c)**).

(M)/TiO<sup>2</sup>

(M)/TiO<sup>2</sup>

large-scale production of VO2

provides hydrophobicity of the surface (see **Figure 8**).

provide the antibacterial property [86]. ZnO-coated VO2

appropriate thickness can significantly reduce the cytotoxicity of VO<sup>2</sup>

As the most attractive thermochromic technology, VO<sup>2</sup> -based smart coatings have gained great attention by researchers and many efforts have been made to promote the real commercialization. Method of multilayer structures has been carried out to improve thermochromic performance with enhanced luminous transmittance, solar modulation ability, and environmental stability. However, more efforts are still needed to make this technology into our daily lives.


Future work can be carried out by choosing materials with versatility for protective, antireflection, and self-cleaning functions.

[4] Granqvist CG. Recent progress in thermochromics and electrochromics: A brief survey.

Solar Modulation Utilizing VO2-Based Thermochromic Coatings for Energy-Saving Applications

[5] Granqvist CG, Green S, Niklasson GA, et al. Advances in chromogenic materials and

[6] Granqvist CG, Pehlivan IB, Ji YX, et al. Electrochromics and thermochromics for energy

mic and related applications. Solar Energy Materials and Solar Cells. 2008;**92**(2):245-258

[8] Granqvist CG. Oxide-based chromogenic coatings and devices for energy efficient fenestration: brief survey and update on thermochromics and electrochromics. Journal of

[9] Wang J, Zhang L, Yu L, et al. A bi-functional device for self-powered electrochromic window and self-rechargeable transparent battery applications. Nature Communications.

[10] Granqvist CG. Oxide electrochromics: An introduction to devices and materials. Solar

(M)/TiO<sup>2</sup>

[12] Chang T, Cao X, Li N, et al. Facile and low-temperature fabrication of thermochro-

Combination of energy-saving, antifogging and self-cleaning functions. Nano Energy.

transmittance and UV-shielding function. ACS Applied Materials & Interfaces.

its visible transmittance. Journal of Infrared and Millimeter Waves. 2006;**25**(3):199-202

[16] Soltani M, Chaker M, Haddad E, et al. Thermochromic vanadium dioxide smart coatings grown on Kapton substrates by reactive pulsed laser deposition. Journal of Vacuum

[17] Binions R, Hyett G, Piccirillo C, et al. Doped and un-doped vanadium dioxide thin films prepared by atmospheric pressure chemical vapour deposition from vanadyl acetylacetonate and tungsten hexachloride: The effects of thickness and crystallographic orientation on thermochromic properties. Journal of Materials Chemistry. 2007;**17**(44):4652-4660

Science & Technology A: Vacuum, Surfaces, and Films. 2006;**24**(3):612-617

smart coatings: Enhanced solar modulation ability, high luminous

O3

http://dx.doi.org/10.5772/intechopen.75584

(A) multilayer film as smart window:

films with nanostructure and improvement on

: Sn and VO2

for electrochro-

films for energy-

V1−*<sup>x</sup>* O2

. Thin

19

efficient fenestration: Functionalities based on nanoparticles of In<sup>2</sup>

[7] Deb SK. Opportunities and challenges in science and technology of WO3

(R)/VO2

[13] Babulanam SM, Eriksson TS, Niklasson GA, et al. Thermochromic VO<sup>2</sup>

films. Solar Energy Materials and Solar Cells. 1996;**44**(4):451-455

[14] Sobhan MA, Kivaisi RT, Stjerna B, et al. Thermochromism of sputter deposited W*<sup>x</sup>*

efficient windows. Solar Energy Materials. 1987;**16**(5):347-363

Vacuum Science & Technology B. 2014;**32**(6), 060801:1-13

Energy Materials and Solar Cells. 2012;**99**:1-13

Thin Solid Films. 2016;**614**:90-96

Solid Films. 2014;**559**:2-8

2014;**5**(4921):1-7

2015;**11**:136-145

O3 /VO2

2017;**9**(31):26029-26037

[15] Shen N, Li Y, Yi XJ. Preparation of VO2

mic Cr2

[11] Zheng J, Bao S, Jin P. TiO2

devices. Thin Solid Films. 2010;**518**(11):3046-3053

**III.** Large-scale production of VO2 smart coatings is necessary to turn this technology from the lab into the industrial and commercial application. Traditional methods, such as hydrothermal synthesis, spray pyrolysis, and sol–gel, etc., are limited due to their low production and complicated process. An effective way to solve this problem is fabricating VO2 -based smart coatings during the production of glasses, just like the deposition of low-emissivity (low-E) coatings on the glass production lines.
