A method for preparing superhydrophobic glass with dense array nanostructures

Abstract

This invention discloses a method for preparing superhydrophobic glass with a dense array nanostructure. The method comprises: performing a first vapor deposition on a pretreated glass substrate to form a metal film on the surface of the glass substrate; followed by heat treatment to form a metal nanoparticle mask on the surface of the glass substrate; performing a second vapor deposition and subsequent heat treatment on the glass substrate under the same conditions to form a dense metal nanoparticle mask on the surface of the glass substrate; and finally performing reactive ion etching, acid washing, and hydrophobic modification treatments on the glass substrate to obtain superhydrophobic glass with a dense array nanostructure. This invention significantly increases the particle size and density of the metal nanoparticles on the glass substrate surface through two solid-state dewetting processes, thereby giving the final glass with a dense array nanostructure excellent dustproof, anti-condensation, anti-frost, anti-icing, and antibacterial properties.

Description

Technical Field

[0001] This invention relates to a method for preparing superhydrophobic glass with a dense array nanostructure. Background Technology

[0002] Glass products are widely used on the surface of solar cells. Since most photovoltaic modules such as solar cells are installed outdoors, dust and dirt easily accumulate on their surfaces, affecting the light transmittance of the solar cell window glass and thus significantly reducing the photoelectric conversion efficiency of the solar cells.

[0003] Since the late 20th century, superwetting surfaces inspired by the biomimetic "lotus effect" have attracted widespread attention. The unique wettability of superwetting surfaces gives them excellent self-cleaning, anti-fogging, anti-fogging, and anti-icing properties, providing inspiration for the design of artificial functional surface materials. Since then, numerous scientists have dedicated themselves to mimicking the surface structures and microscopic morphological features of various organisms in nature to create superwetting surfaces with similar functions.

[0004] With the continuous improvement of superwetting theory and fabrication processes, significant progress has been made in the research and development of transparent superwetting surfaces. However, there are still relatively few reports in the literature on transparent multifunctional antifouling glass. For glass, a material with high light transmittance, the requirements for optical performance are very high. However, the necessary rough structure of a superwetting surface can lead to a decrease in the optical properties of the material, which contradicts the high light transmittance of the glass product itself. Currently, dry etching combined with metal template method is considered the best fabrication process for building transparent superhydrophobic and antifouling surfaces on glass products. However, when glass with functional array nanostructures constructed by this method is used as an outdoor self-cleaning surface, it is often subjected to impacts from gravel and cannot avoid impacts from rain, frost, and ice. This requires the functional array nanostructure glass surface to have good mechanical stability and hydraulic resistance, which places higher demands on the column spacing and column density of the array nanostructure. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for preparing transparent superhydrophobic glass. The transparent superhydrophobic glass prepared by this method can significantly improve the density and size of the nanostructure array on the glass surface while maintaining the excellent optical properties of the glass itself, thereby greatly improving the wettability of the glass.

[0006] Technical Solution: The preparation method of the superhydrophobic glass with a dense array nanostructure according to the present invention specifically includes: performing a first vapor deposition on a pretreated glass substrate to form a metal film on the surface of the glass substrate after vapor deposition; performing heat treatment after vapor deposition to form a metal nanoparticle mask on the surface of the glass substrate; performing a second vapor deposition and heat treatment after vapor deposition on the glass substrate under the same conditions to form a dense metal nanoparticle mask on the surface of the glass substrate; and finally performing reactive ion etching, acid washing and hydrophobic modification treatment on the glass substrate in sequence to obtain the superhydrophobic glass with a dense array nanostructure.

[0007] The thickness of the metal film formed after each evaporation is 3 to 10 nm.

[0008] The pretreatment of the glass substrate specifically involves immersing it in a mixed solution of sulfuric acid and hydrogen peroxide at 75–95°C. After immersion, the substrate is ultrasonically treated with acetone, anhydrous ethanol, and deionized water for 10–30 minutes each, and then dried with nitrogen. The mass ratio of sulfuric acid to hydrogen peroxide in the mixed solution is 5–10:3. The purpose of the pretreatment is to clean the surface of the glass substrate.

[0009] The glass substrate is any one of ordinary glass, quartz glass, potassium glass, borate glass, optical glass, or microcrystalline glass.

[0010] The method of forming a metal film on a glass substrate by evaporation specifically involves placing the glass substrate in a vacuum chamber for electron beam evaporation at a depth of 5 × 10⁻⁶. -7 Torr deposits a metal film under chamber pressure; the metal film can be any one of gold, silver, copper, platinum or titanium.

[0011] The heat treatment conditions after vapor deposition involved heating to 400–600°C at a rate of 40–80°C / min and holding for 1–30 min. By adjusting the heat treatment conditions, the particle size and distribution of the metal nanospheres on the glass substrate became more uniform.

[0012] Specifically, reactive ion etching involves placing a glass substrate with a dense metal nanoparticle mask into a reactive ion etching chamber for etching. The reactive ion etching gas is a combination of argon and trifluoromethane, tetrafluoromethane, or sulfur hexafluoride, with a flow rate ratio of argon:trifluoromethane, tetrafluoromethane, or sulfur hexafluoride of 10–50:1–10. During etching, the radio frequency power is 100–400 W, the etching chamber pressure is 5–25 Pa, and the etching time is 5–15 min. The height of the final nanostructure is adjusted by modifying the etching parameters to achieve a large aspect ratio.

[0013] Hydrophobic modification refers to chemical vapor deposition modification of the etched and acid-washed glass substrate; the selected chemical vapor deposition modifier is at least one of tridecafluorooctyltriethoxysilane, perfluoropolyether, heptadecafluorodecyltrichlorosilane or heptadecafluorodecyltriethoxysilane.

[0014] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: This invention effectively solves the technical problem of dust and dirt easily accumulating on the outdoor surface of transparent glass after long-term exposure. Based on the metal template method combined with reactive ion etching technology, this invention can construct a uniformly distributed and dense array nanostructure on the surface of glass products. This not only effectively improves the light transmittance of glass products, achieving the effect of increasing light transmittance and reducing reflection, but also significantly improves the wettability of the glass product surface. Through two solid-state dewetting processes, this invention can significantly increase the particle size of metal nanoparticles on the glass substrate surface while also significantly increasing the density of nanoparticles. As a result, the glass with a dense array nanostructure prepared in the end has good mechanical stability and hydraulic resistance (resistance to external impact and liquid penetration). At the same time, it also has excellent dustproof, anti-condensation, anti-frost, anti-icing and antibacterial properties, thereby significantly improving the durability and service life of solar cell cover glass for outdoor use. Attached Figure Description

[0015] Figure 1 This is a digital image of the water droplet morphology on a dense array nanostructured transparent superhydrophobic glass as shown in Example 1.

[0016] Figure 2 This is a scanning electron microscope image of the dense array nanostructure on glass in Example 2;

[0017] Figure 3 This is a digital image showing the low-temperature condensation and low-temperature bouncing of water droplets on a dense array nanostructured transparent superhydrophobic glass in Example 1.

[0018] Figure 4 This is a digital image of condensation on the surface of a dense array nanostructured transparent superhydrophobic glass, as shown in Example 1.

[0019] Figure 5 A digital photograph of frost covering the surface of a dense array nanostructured transparent superhydrophobic glass, as shown in Example 1.

[0020] Figure 6 This is a digital photograph of the frost thickness on the surface of the dense array nanostructured transparent superhydrophobic glass in Example 1.

[0021] Figure 7 Digital image of delayed icing on a dense array nanostructured transparent superhydrophobic glass in Example 2;

[0022] Figure 8Digital image of droplet bouncing dust removal on a dense array nanostructure transparent superhydrophobic glass in Example 2;

[0023] Figure 9 This is a digital image of antibacterial activity on a dense array nanostructured transparent superhydrophobic glass, as shown in Example 2.

[0024] Figure 10 A digital photograph of a packaged solar cell. Detailed Implementation

[0025] Example 1

[0026] The present invention provides a method for preparing superhydrophobic glass with a dense array nanostructure, comprising the following steps:

[0027] (1) The glass substrate was placed in a mixed solution of sulfuric acid and hydrogen peroxide at 85℃ and soaked for 2 hours. Then it was ultrasonicated with acetone, anhydrous ethanol and deionized water for 15 minutes respectively. It was then dried with nitrogen gas for later use to obtain a clean glass substrate. The mass ratio of sulfuric acid to hydrogen peroxide in the mixed solution was 5:3.

[0028] (2) The cleaned glass substrate was placed in a vacuum chamber for electron beam evaporation, and a 5 nm gold film was deposited at a chamber pressure of 5 × 10⁻⁷ Torr. Subsequently, the deposited substrate sample was placed in a rapid heating furnace for solid-state dewetting treatment to form a gold nanoparticle mask on the surface of the glass substrate. The solid-state dewetting temperature was 450 °C, the heating time was 40 °C / min, and the holding time was 30 min. At this time, the gold nanoparticle mask particle density was 112 ± 7 Particles·μm. -2 The particle size is 55.2±15.8 nm;

[0029] (3) The glass substrate with the gold nanoparticle mask is placed back into the vacuum chamber for electron beam evaporation, and a 5 nm gold film is deposited again under the same deposition conditions. After the two gold film depositions, the glass substrate is placed in a rapid heating furnace for a second solid-state dewetting treatment to form a dense gold nanoparticle mask on the surface of the glass substrate. At this time, the gold nanoparticle density is 182±4 particles·μm. -2 The particle size is 87.2±11.8 nm;

[0030] (4) The glass substrate with the dense gold nanoparticle mask is placed in the reactive ion etching chamber for etching. The specific etching process is as follows: the etching gas is a mixture of SF6 and Ar, and the gas flow ratio of SF6 and Ar in the mixture is 5 sccm:40 ccm; the chamber pressure is 0.4 Pa, the radio frequency power is 400 W, and the etching time is 630 s.

[0031] (5) The etched glass substrate is rinsed in aqua regia to remove the residual gold nanoparticle mask.

[0032] (6) The etched and acid-washed glass substrate is placed in a vacuum drying oven at 150°C and modified by chemical vapor deposition of fluorosilane to obtain superhydrophobic glass with a dense array nanostructure.

[0033] Figure 1 Digital photographs of water droplets and hexadecane on the surface of the final transparent superhydrophobic glass show that the water contact angle reaches 158° and the roll-off angle is as low as 3°, while the contact angle of hexadecane reaches 118°. The light transmittance and haze both reach 93.5%, indicating that the transparent superhydrophobic glass prepared in Example 1 possesses excellent superhydrophobicity and optical properties. In contrast, the water contact angle of the flat glass sample without the hydrophobic modification using a dense array nanostructure is only 118°, exhibiting only a moderate hydrophobic effect. The dense array nanostructure can significantly improve wettability and reduce the contact area between liquid or dust particles and the array surface, thus reducing adhesion and providing a series of effects such as dust prevention and anti-condensation.

[0034] Example 2

[0035] The present invention provides a method for preparing superhydrophobic glass with a dense array nanostructure, comprising the following steps:

[0036] (1) The glass substrate was placed in a mixed solution of sulfuric acid and hydrogen peroxide at 95℃ and soaked for 2 hours. Then it was ultrasonicated with acetone, anhydrous ethanol and deionized water for 10 minutes respectively. It was then dried with nitrogen gas for later use to obtain a clean glass substrate. The mass ratio of sulfuric acid to hydrogen peroxide in the mixed solution was 5:3.

[0037] (2) The cleaned glass substrate was placed in a vacuum chamber for electron beam evaporation, and a 4 nm copper film was deposited under a chamber pressure of 5 × 10⁻⁷ Torr. Subsequently, the deposited substrate sample was placed in a rapid heating furnace for solid-state dewetting treatment to form a copper nanoparticle mask on the surface of the glass substrate. The solid-state dewetting temperature was 600 °C, the heating rate was 60 °C / min, and the holding time was 10 min. At this time, the particle density of the copper nanomask was 367 ± 8 particles·μm. -2 The particle size is 36.4±6.1 nm;

[0038] (3) The glass substrate with the copper nanoparticle mask is placed back into the vacuum chamber for electron beam evaporation, and a 4 nm copper film is deposited again under the same deposition conditions. The glass substrate with the two copper film depositions is then placed in a rapid heating furnace for a second solid-state dewetting treatment to form a dense copper nanoparticle mask on the surface of the glass substrate. At this time, the copper nanoparticle mask particle density is 288±11 particles·μm.-2 The particle size is 48.8±4.2 nm;

[0039] (4) The glass substrate with a dense copper nanoparticle mask is placed in the reactive ion etching chamber for etching. The specific etching process is as follows: the etching gas is a mixture of CHF3 and Ar, and the flow rate of CHF3 and Ar in the mixture is 5 sccm: 40 ccm; the chamber pressure is 10 Pa, the radio frequency power is 300 W, and the etching time is 640 s.

[0040] (5) The etched glass substrate is rinsed in aqua regia to remove the residual copper nanoparticle mask.

[0041] (6) The etched and acid-washed glass substrate is placed in a vacuum drying oven at 150°C and modified by chemical vapor deposition of fluorosilane to obtain superhydrophobic glass with a dense array nanostructure.

[0042] Comparative Example 1

[0043] The only difference between Comparative Example 1 and Example 2 is that step (3) is removed, and only one evaporation deposition is performed, with a copper film thickness of 4 nm. The remaining steps are the same as in Example 2. At this time, the copper nanomask particle density is 367±8 particles·μm. -2 The particle size is 36.4±6.1nm.

[0044] Comparative Example 2

[0045] The only difference between Comparative Example 2 and Example 2 is that step (3) is removed, and only one evaporation deposition is performed, but the thickness of the deposited copper film is 8 nm. The remaining steps are the same as in Example 2. At this time, the copper nanomask particle density is 51±4 particles·μm. -2 The particle size is 79.8±4.5nm.

[0046] Figure 2 The image shown is a scanning electron microscope image of the dense array nanostructure on the glass substrate in Example 2. The water contact angle on the glass sample surface can reach 158°, and the roll-off angle is as low as 1°, while the contact angle of hexadecane can reach 123°, and the transmittance can reach 95.1%. In contrast, the water contact angles of the glass samples obtained in Comparative Examples 1 and 2 are 154° and 151°, respectively, and the transmittances are 93.2% and 92.4%, respectively. This demonstrates that the present invention enables the glass to possess excellent wettability and optical properties through the dense array nanostructure.

[0047] To verify the anti-condensation effect of the dense nanostructured transparent superhydrophobic glass obtained in Example 1, several pieces of the transparent superhydrophobic glass obtained in Example 1 were taken and fixed on a cold stage at -2°C. The ambient temperature and humidity were controlled to 25°C and 80% respectively using a temperature and humidity control system. The condensation bounce effect on the surface of the transparent superhydrophobic glass was observed from the side of the sample using a high-speed camera, and the coverage of condensed droplets was observed from above the sample using a stereomicroscope. After 40 minutes of condensation testing, the surface of the dense nanostructured transparent superhydrophobic glass still showed... Figure 3 The obvious droplet condensation self-bouncing characteristic shown in the image is precisely due to this condensation-driven bouncing away from the sample surface. Figure 4 The condensation digital graph shows that after 40 minutes of condensation testing, the droplet coverage on the surface of the dense nanoarray structure of the transparent superhydrophobic glass sample was only 40%, and the droplet nucleation rate was only 4.5 × 10⁻⁶. 9 m -2 This indicates that the dense nanoarray structure of the transparent superhydrophobic glass surface has good anti-condensation properties.

[0048] To verify the anti-frost effect of the dense nanostructured transparent superhydrophobic glass obtained in Example 1, several pieces of the transparent superhydrophobic glass obtained in Example 1 were taken and fixed on a cold stage at -10°C. The ambient temperature and humidity were controlled to 25°C and 80% respectively using a temperature and humidity control system. The frost coverage rate was observed from above the sample using a stereomicroscope. After a 50-minute frost test, the surface of the dense nanoarray structured transparent superhydrophobic glass remained in a condensed state, and most areas still exhibited the phenomenon of condensation self-driven bouncing. Figure 5 Digital photograph of the frost coverage on the surface of a dense array nanostructured transparent superhydrophobic glass after a 60-minute frost test. Figure 6 The frost thickness on the sample surface after 60 minutes of frost formation is shown. The 60-minute frost test revealed that the frost coverage of the dense array nanostructured transparent superhydrophobic glass surface was reduced by more than 32.9% compared to the array nanostructured superhydrophobic glass surface prepared in Comparative Example 1, while the frost thickness was reduced by more than 33.3%. This indicates that the dense nanostructured transparent superhydrophobic glass surface possesses excellent delayed frost formation and anti-frost formation properties.

[0049] To verify the delayed icing effect of the dense nanostructured transparent superhydrophobic glass obtained in Example 2, several transparent superhydrophobic glasses obtained in Example 2 were taken out and fixed on a cold stage at -20°C. The temperature and humidity of the environment were controlled at 25°C and 80% respectively by a temperature and humidity control system. The icing adhesion force and icing time on the sample surface were tested by an automatic force gauge. Figure 7 A digital image of delayed icing of droplets on the surface of a dense array of nanostructured transparent superhydrophobic glass, from Figure 7As can be seen, the droplet freezing time on the dense array nanostructured transparent superhydrophobic glass surface is extended to 134 min, which is much shorter than that on the flat glass surface, where it is extended by 120 min. Furthermore, the ice adhesion on the dense array nanostructured transparent superhydrophobic glass surface after freezing is only 3.5 kPa, much lower than the 61.2 kPa on the flat glass sample surface, indicating that the dense nanostructured transparent superhydrophobic glass surface has excellent delayed freezing and easy de-icing properties.

[0050] To verify the low-temperature condensation self-dust removal effect of the dense nanostructured transparent superhydrophobic glass surface obtained in Example 2, several transparent superhydrophobic glasses obtained in Example 2 were taken out and fixed on a cold stage at -2°C. The temperature and humidity of the environment were controlled at 25°C and 80% respectively by a temperature and humidity control system. The phenomenon of droplets on the sample surface self-bouncing and removing dust was observed by a high-speed camera. Figure 8 Digital images showing the self-bouncing dust removal process of droplets condensing on the surface of a dense array of nanostructured transparent superhydrophobic glass. Figure 8 As can be seen, the dense array nanostructured transparent superhydrophobic glass surface, due to its excellent condensation self-driven bouncing characteristics, can detach dust particles from the sample surface at low temperatures by merging and bouncing droplets, achieving a condensation self-driven bouncing dust removal effect. After 25 minutes of condensation bouncing dust removal, the surface dust removal rate reached 85%, indicating that the dense nanostructured transparent superhydrophobic glass surface has excellent low-temperature condensation self-dust removal characteristics.

[0051] To verify the antibacterial effect of the dense nanostructured transparent superhydrophobic glass surface prepared in Example 2, several samples of the transparent superhydrophobic glass obtained in Example 2 were taken and immersed in a prepared E. coli culture for 24 hours. After the culture was completed, the airborne bacteria were gently washed away with PBS solution, and then the samples were placed in a new culture plate. 1 mL of sterile PBS solution was added, and the plates were sonicated for 5 minutes to allow the adhering bacteria to detach completely. 100 μL of the diluted bacterial culture was spread on LB solid medium and incubated at 37°C for 18 hours. The colony count was then photographed and recorded. Figure 9 Digital images of antibacterial agents on a dense array of nanostructured transparent superhydrophobic glass, from Figure 9 As can be seen, the number of residual bacterial colonies on the surface of the dense nanostructured transparent superhydrophobic glass is 4.7 × 10⁻⁶. 5 The number of bacteria was reduced by 68.2% compared to the total number of bacteria on the surface of the flat glass sample, indicating that the dense nanostructured transparent superhydrophobic glass surface has good antibacterial properties.

[0052] To verify the effect of the dense nanostructured transparent superhydrophobic glass prepared in Example 2 on the photoelectric conversion efficiency after application on the surface of a solar cell, several pieces of the transparent superhydrophobic glass obtained in Example 2 were taken and encapsulated with commercial crystalline silicon cells to prepare a complete solar cell module. To test the photoelectric conversion efficiency of the prepared array nanostructured solar cell, the IV characteristic curve and photoelectric conversion efficiency of the sample were tested under AM 1.5G illumination conditions using a quantum efficiency meter and a solar simulator. During the test, the incident angle of sunlight was kept constant at 90°. Figure 10 This is a digital photograph of the encapsulated solar cell. Tests showed that the photoelectric conversion efficiency of the solar cell encapsulated on the surface of a dense array nanostructured transparent superhydrophobic glass was more than 8.03% higher than that of the solar cell encapsulated with superhydrophobic glass prepared in Comparative Example 1. This indicates that the dense array nanostructured transparent superhydrophobic glass can significantly improve the photoelectric conversion efficiency of solar cells.

Claims

1. A method for preparing superhydrophobic glass with a dense array nanostructure, characterized in that, The method is as follows: A pretreated glass substrate undergoes a first evaporation deposition to form a metal film on its surface. Following evaporation, heat treatment is performed to form a metal nanoparticle mask on the glass substrate surface. Under the same conditions, a second evaporation deposition and subsequent heat treatment are performed on the glass substrate to form a dense metal nanoparticle mask on its surface. Finally, the glass substrate is subjected to reactive ion etching, acid washing, and hydrophobic modification treatments in sequence to obtain a superhydrophobic glass with a dense array of nanostructures. Specifically, the method for forming a metal film on a glass substrate by evaporation deposition involves placing the glass substrate in a vacuum chamber for electron beam evaporation at 5 × 10⁻⁶ ppm. -7 The metal film is deposited under chamber pressure in the Torr system; the metal film can be any one of gold, silver, copper, platinum or titanium; the heat treatment conditions after evaporation are to heat to 400-600℃ at a rate of 40-80℃ / min and hold for 1-30 min.

2. The method for preparing superhydrophobic glass with a dense array nanostructure according to claim 1, characterized in that: The thickness of the metal film formed after each evaporation is 3~10nm.

3. The method for preparing superhydrophobic glass with a dense array nanostructure according to claim 1, characterized in that: The pretreatment of the glass substrate is as follows: the glass substrate is immersed in a mixed solution of sulfuric acid and hydrogen peroxide at 75~95℃, and after immersion, it is ultrasonicated with acetone, anhydrous ethanol and deionized water for 10~30 min respectively, and then dried with nitrogen; the mass ratio of sulfuric acid to hydrogen peroxide in the mixed solution is 5~10:

3.

4. The method for preparing superhydrophobic glass with a dense array nanostructure according to claim 1, characterized in that: The glass substrate is any one of ordinary glass, quartz glass, potassium glass, borate glass, optical glass, or microcrystalline glass.

5. The method for preparing superhydrophobic glass with a dense array nanostructure according to claim 1, characterized in that: The reactive ion etching process involves placing a glass substrate with a dense metal nanoparticle mask into a reactive ion etching chamber for etching. The reactive ion etching gas is a combination of argon and trifluoromethane, tetrafluoromethane, or sulfur hexafluoride. The flow rate ratio of argon to trifluoromethane, tetrafluoromethane, or sulfur hexafluoride in the combination gas is 10-50:1-10. During etching, the radio frequency power is 100-400W, the etching chamber pressure is 5-25Pa, and the etching time is 5-15min.

6. The method for preparing superhydrophobic glass with a dense array nanostructure according to claim 1, characterized in that: Hydrophobic modification refers to chemical vapor deposition modification of etched and acid-washed glass substrates; the selected chemical vapor deposition modifier is at least one of tridecafluorooctyltriethoxysilane, perfluoropolyether, heptadecafluorodecyltrichlorosilane or heptadecafluorodecyltriethoxysilane.

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