Super-hydrophobic self-cleaning optical panel and preparation method thereof

Abstract

The invention discloses a super-hydrophobic self-cleaning optical panel and a preparation method thereof, and relates to the field of optical elements. A preparation method of a super-hydrophobic self-cleaning optical panel comprises the following steps: S1, cleaning a glass substrate to ensure that the surface is clean; s2, putting the cleaned glass substrate into a PECVD (Plasma Enhanced Chemical Vapor Deposition) reaction cavity, and vacuumizing; s3, nano peak structures which are uniformly arranged and have a cone-like shape are deposited on the glass substrate; s4, activating the glass substrate deposited with the nano peak structure by adopting oxygen plasma; s5, plating an AF (anti-fingerprint) layer on the nano peak structure of the activated glass substrate; the height range of the nanometer peak structures is 200-300 nm, the distance range of the adjacent nanometer peak structures is 30-50 nm, and the aspect ratio of the nanometer peak structures is 1.2-1.5. The preparation process is simple, and the super-hydrophobic self-cleaning optical panel with good stability can be prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical elements, in particular to a super-hydrophobic self-cleaning optical panel and a preparation method thereof. BACKGROUND

[0002] Optical panels are easily contaminated by water droplets, oil stains and fingerprints in daily use, which seriously affects their light transmission performance and aesthetics. In order to improve this problem, super-hydrophobic self-cleaning technology has attracted widespread attention.

[0003] At present, the common method to improve the hydrophobic performance of optical panels is to construct micro-nano structures on the substrate through nano-imprinting or photolithography technology. However, nano-imprinting and photolithography technology have many limitations in practical application.

[0004] Nano-imprinting technology requires the pre-preparation of high-precision templates, which not only has high cost, but also has a long preparation period of the template, which is difficult to meet the demand of large-scale rapid production. At the same time, the template is easy to wear during use, which leads to the decline of the quality of the micro-nano structure imprinted, and further affects the hydrophobic performance of the optical panel. Although photolithography technology can realize the preparation of high-precision micro-nano structures, it is expensive and complicated to operate, and has very high requirements for the environment, which needs to be carried out in a super-clean room, which undoubtedly increases the production cost. Moreover, photolithography technology usually uses photosensitive materials, which may introduce impurities in the process of exposure and development, and have an adverse effect on the performance of the optical panel.

[0005] In addition, the super-hydrophobic surface of the optical panel prepared by the existing method has poor stability, and the micro-nano structure is easy to be worn or damaged during long-term use, which leads to the gradual decrease of the hydrophobic performance. Therefore, it is of great practical significance to develop a method which has simple preparation process and can prepare a super-hydrophobic self-cleaning optical panel with good stability. SUMMARY

[0006] The present application provides a super-hydrophobic self-cleaning optical panel and a preparation method thereof, which has the advantages of simple preparation process and can prepare a super-hydrophobic self-cleaning optical panel with good stability.

[0007] In the first aspect, the present application provides a preparation method of a super-hydrophobic self-cleaning optical panel, which adopts the following technical scheme: A preparation method of a super-hydrophobic self-cleaning optical panel, comprising the following steps: S1, cleaning the glass substrate to ensure the surface is clean; S2, placing the cleaned glass substrate into a PECVD reaction chamber, and pumping to vacuum to remove impurity gas; S3, depositing a nano-spiked structure with uniform arrangement and conical shape on the glass substrate, the nano-spiked structure being made of silicon oxide and silicon nitride materials; S4, activating the glass substrate with the nano-pyramid structure by oxygen plasma; S5, plating an AF anti-fingerprint layer on the nano-pyramid structure of the activated glass substrate to obtain the super-hydrophobic self-cleaning optical panel; The height of the nano-pyramid structure ranges from 200 to 300 nm, the interval between adjacent nano-pyramid structures ranges from 30 to 50 nm, and the aspect ratio of the nano-pyramid structure is 1.2-1.5.

[0008] In the present application, the core of the super-hydrophobic self-cleaning optical panel lies in two aspects: one is to deposit a periodic arrangement of nano-pyramid structures with specific specifications on the glass substrate, and the other is to activate and anti-fingerprint the glass substrate with the nano-pyramid structure.

[0009] The rough surface created by the nano-pyramid structure can effectively trap air, improve the hydrophobicity of the optical panel, and achieve the "lotus effect". However, the size and interval parameters of the nano-pyramid structure are very critical. In the present application, the height of the nano-pyramid structure should not exceed 300 nm, and the aspect ratio should not be too large. If the height or aspect ratio is too large, the nano-pyramid structure is prone to breakage and collapse under external force, resulting in weakened hydrophobicity. If the interval between the two adjacent peaks of the nano-pyramid structure is too small, the capillary force between the water droplets and the surface will be enhanced, resulting in an increase in the water droplet rolling angle and a decrease in the self-cleaning effect of the optical panel.

[0010] In view of the shortcomings of poor hydrophobic durability of the nano-pyramid structure alone (for example, the lotus hydrophobic effect of the optical panel will disappear after the nano-pyramid structure is damaged by multiple wiping), the present application adds the activation and anti-fingerprint treatment steps of the nano-pyramid structure. The activation step improves the adhesion of the AF anti-fingerprint layer to the nano-pyramid structure. The low surface energy and wrapping protection of the AF anti-fingerprint layer are conducive to further improving the hydrophobicity of the optical panel, achieving stable and persistent super-hydrophobic effect (water contact angle > 150°), and providing excellent anti-fingerprint pollution effect, which can improve the cleaning difficulty of the existing optical panel.

[0011] In some specific embodiments, when the nano-pyramid structure is a silicon nitride material, the S3 step is specifically as follows: SiH4, NH3 and fluorine-containing etching gas are introduced into the PECVD reaction chamber, and after high-frequency ionization, a nano-pyramid structure with uniform arrangement and conical shape is deposited on the glass substrate. The specific parameters are as follows: the glass substrate temperature is 230-250°C, the radio frequency power is 300-400W, the radio frequency frequency is 13.56 MHz, the pressure of the PECVD reaction chamber is 80-100Pa, the flow rate of the fluorine-containing etching gas is 15-25sccm, and the flow rate ratio of SiH4, NH3 and fluorine-containing etching gas is (1-1.5):(2-3):1.

[0012] In the present application, the reaction gas (SiH4, NH3) and the fluorine-containing etching gas are simultaneously introduced when the silicon nitride nano-peak structure is deposited, so that the silicon nitride deposition and the plasma etching are simultaneously performed, and the silicon nitride nano-peak structure with regular arrangement and uniform size is formed on the entire glass substrate. The process flow is simplified without the need of adding a mask plate for auxiliary molding and the subsequent photolithography etching step. The key of the step lies in the synergistic cooperation between various parameters, such as the radio frequency power, the radio frequency frequency, the PECVD reaction cavity pressure, and the control of the flow rates of SiH4, NH3 and the fluorine-containing etching gas, so as to balance the deposition rate and the etching rate of the silicon nitride, and form the silicon nitride nano-peak structure with uniform arrangement and a specific size range and a conical shape.

[0013] In some specific embodiments, the fluorine-containing etching gas uses any one of CF4, NF3 and SF6.

[0014] In some specific embodiments, when the nano-peak structure is a silicon oxide material, the S3 step is specifically as follows: The SiH4, N2O and inert gas are introduced into the PECVD reaction cavity, and the nano-peak structure with uniform arrangement and a conical shape is deposited on the glass substrate after high-frequency ionization. The specific parameters are as follows: the glass substrate temperature is 230-250°C, the radio frequency power is 300-400W, the radio frequency frequency is 13.56 MHz, the PECVD reaction cavity pressure is 3-8 Pa, the N2O flow rate is 5-10 sccm, and the flow rate ratio of SiH4, N2O and inert gas is (8-10):1:100.

[0015] In the present application, the reaction gas (SiH4, N2O) and the inert gas are simultaneously introduced when the silicon oxide nano-peak structure is deposited. The inert gas is used to dilute the reaction gas, maintain the stability of the plasma and adjust the ion bombardment effect in the deposition process, and the formation of the silicon oxide nano-peak structure is promoted by adjusting the flow rate ratio of SiH4 and N2O and the control of the PECVD reaction cavity pressure. The process can be completed in one step without the need of adding a mask plate for auxiliary molding or increasing a photolithography etching step.

[0016] In some specific embodiments, the PECVD reaction cavity is vacuumized, and then the oxygen is introduced into the PECVD reaction cavity in the S4 step. The glass substrate with the nano-peak structure is subjected to an oxygen plasma activation treatment with a time length of 30-40 s under the conditions of a radio frequency power of 50-100 W, a radio frequency frequency of 13.56 MHz, a PECVD reaction cavity pressure of 20-50 Pa, and an oxygen flow rate of 4-8 sccm, to obtain the activated glass substrate.

[0017] In this application, when activating a glass substrate with deposited nano-peak structures, the radio frequency power should not be higher than the power when depositing silicon nitride or silicon oxide nano-peak structures. At the same time, the control of the activation time is also very critical. If the activation time is too short, the hydrophobic durability of the optical panel will not be significantly improved. If the activation time is too long, the nano-peak structure is easily damaged, which also affects the hydrophobic effect and stability of the optical panel. Therefore, when activating a glass substrate with deposited nano-peak structures, the activation parameters must be strictly controlled.

[0018] In some specific embodiments, in S5, the AF anti-fingerprint layer is formed by AF coated pellets under a vacuum degree of less than 10. -3 The nano-peak structure is vapor-deposited onto the activated glass substrate under a Pa environment.

[0019] In this application, an AF anti-fingerprint layer is deposited on the nano-peak structure by vapor deposition, which is beneficial to the maintenance of the nano-peak structure, while preventing fingerprint residue and further improving the hydrophobicity and stability of the optical panel.

[0020] In some specific embodiments, the deposition rate of the AF-coated pellet is 0.1-0.5 nm / s.

[0021] In this application, controlling the deposition rate of the AF coating pellet to be 0.1-0.5 nm / s is beneficial to improving the deposition uniformity and density of the AF anti-fingerprint layer on the nano-peak structure, and to improving the adhesion between the AF anti-fingerprint layer and the nano-peak structure.

[0022] In some specific embodiments, the thickness of the AF anti-fingerprint layer is 5-10 nm.

[0023] Secondly, the superhydrophobic self-cleaning optical panel provided in this application adopts the following technical solution: A superhydrophobic self-cleaning optical panel is prepared by any one of the above-described methods for preparing a superhydrophobic self-cleaning optical panel.

[0024] The superhydrophobic self-cleaning optical panel of this application has stable and durable hydrophobic properties, self-cleaning function, and fingerprint resistance.

[0025] In summary, this application includes at least the following beneficial technical effects: (1) In this application, the rough surface created by the nano-peak structure can effectively trap air, which can improve the hydrophobicity of the optical panel and realize the "lotus effect". However, the size and spacing parameters of the nano-peak structure are very critical. In this application, the height of the nano-peak structure should not exceed 300 nm and the aspect ratio should not be too large. When the height or aspect ratio is too large, the nano-peak structure is prone to breakage and collapse under external force, resulting in weakened hydrophobic performance. If the spacing between two adjacent peaks of the nano-peak structure is too small, it will enhance the capillary force between the water droplet and the surface, resulting in an increased water droplet roll-off angle and a worse self-cleaning effect of the optical panel. To address the drawback of poor hydrophobic durability of standalone nano-peak structures (e.g., the lotus leaf hydrophobic effect of the optical panel disappears after repeated wiping that damages the nano-peak structure), this application adds activation and anti-fingerprint treatment steps to the nano-peak structure. The activation step enhances the adhesion between the AF anti-fingerprint layer and the nano-peak structure. The low surface energy and encapsulation protection of the AF anti-fingerprint layer further improve the hydrophobicity of the optical panel, achieving a stable and durable superhydrophobic effect (water contact angle > 150°) and providing excellent anti-fingerprint contamination effect, thus improving the difficulty of cleaning existing optical panels.

[0026] (2) In this application, when controlling the deposition of silicon nitride nanospike structures, reactive gases (SiH4, NH3) and fluorine-containing etching gases are simultaneously introduced, so that silicon nitride deposition and plasma etching are carried out simultaneously, forming a regularly arranged and uniformly sized silicon nitride nanospike structure on the entire glass substrate. No additional mask is required for shaping, nor is a subsequent photolithography step required, simplifying the process flow. The key to this step lies in the synergistic coordination between various parameters, such as the control of radio frequency power, radio frequency frequency, PECVD reaction chamber pressure, and the flow rates of SiH4, NH3, and fluorine-containing etching gases. This balances the deposition rate and etching rate of silicon nitride to form a uniformly arranged, cone-shaped silicon nitride nanospike structure with a specific size range.

[0027] (3) In this application, when controlling the deposition of silicon oxide nanospike structures, reactive gases (SiH4, N2O) and inert gases are simultaneously introduced. The inert gas is used to dilute the reactive gases, maintain plasma stability, and regulate the ion bombardment effect during the deposition process. The formation of silicon oxide nanospike structures is promoted by adjusting the flow ratio of SiH4 and N2O and controlling the pressure inside the PECVD reaction chamber. This process does not require the addition of a mask to assist in the forming or an additional photolithography step, and can be completed in one step. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the optical panel of this application.

[0029] 1. Glass substrate; 2. Nanoscale spike structure; 3. AF anti-fingerprint layer. Detailed Implementation

[0030] The following detailed experiments further illustrate this application. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application can be obtained through commercial channels. Example

[0031]

Example 1

[0032]

Example 2

[0033]

Example 3

[0034]

Example 4

[0035] Comparative Example Comparative Example 1 A method for preparing a superhydrophobic self-cleaning optical panel differs from [Example 1] in that: in step S3, the deposition height of the silicon nitride nanospike structure is 440-450 nm, the spacing between adjacent silicon nitride nanospike structures is 20-25 nm, and the aspect ratio of the nanospike structure is 1.6-1.8.

[0036] Comparative Example 2 A method for preparing a superhydrophobic self-cleaning optical panel differs from [Example 3] in that: in step S3, the deposition height of the silicon oxide nanospike structure is 440-450 nm, the spacing between adjacent silicon oxide nanospike structures is 28-34 nm, and the aspect ratio of the nanospike structure is 1.55-1.68.

[0037] Comparative Example 3 A method for fabricating a superhydrophobic self-cleaning optical panel differs from [Example 1] in that: in step S3, SiH4, NH3, and CF4 are introduced into the PECVD reaction chamber, and after high-frequency ionization, uniformly arranged, cone-shaped nano-peak structures are deposited on a glass substrate; the specific parameters are as follows: the glass substrate temperature is 230℃, the RF power is 300W, the RF frequency is 13.56 MHz, the PECVD reaction chamber pressure is 40Pa, the CF4 flow rate is 15sccm, the flow ratio of SiH4, NH3, and CF4 is 1:2:10, the deposition height of the silicon nitride nano-peak structure is 200-210nm, the spacing between adjacent silicon nitride nano-peak structures is 100-120nm, and the aspect ratio of the nano-peak structure is 1.8-2.0.

[0038] Comparative Example 4 A method for fabricating a superhydrophobic self-cleaning optical panel differs from [Example 3] in that: In step S3, SiH4, N2O, and Ar are introduced into the PECVD reaction chamber. After high-frequency ionization, uniformly arranged, cone-shaped nanospike structures are deposited on the glass substrate. The specific parameters are as follows: glass substrate temperature is 230℃, RF power is 300W, RF frequency is 13.56 MHz, PECVD reaction chamber pressure is 50Pa, N2O flow rate is 5sccm, SiH4, N2O, and Ar flow ratio is 8:1:50, the deposition height of the silicon oxide nanospike structure is 240-250nm, the spacing between adjacent silicon oxide nanospike structures is 10-15nm, and the aspect ratio of the nanospike structure is 0.5-0.7.

[0039] Comparative Example 5 A method for preparing a superhydrophobic self-cleaning optical panel differs from [Example 1] in that step S4 is omitted, and the AF coating pellet (Dongguan Maicheng New Material Co., Ltd.) is directly vapor-deposited onto the nano-peak structure surface of the glass substrate according to step S5.

[0040] Comparative Example 6 A method for preparing a superhydrophobic self-cleaning optical panel differs from [Example 1] in that steps S4 and S5 are omitted.

[0041] Performance testing (1) Water contact angle: The contact angle between the optical panel test surface and water before and after wiping in the examples and comparative examples was tested by the seat drop method. The test surface of Examples 1-4 and Comparative Examples 1-5 was the AF anti-fingerprint layer, and the test surface of Comparative Example 6 was the nano-peak structure surface. The wiping was performed with non-woven cloth, and the number of wiping times was 1000.

[0042] (2) Roll-off angle: The roll-off angle of water droplets on the optical panel test surface before and after wiping in each embodiment and comparative example was tested using the inclined platform method. The test surface of Embodiments 1-4 and Comparative Examples 1-5 was the AF anti-fingerprint layer, and the test surface of Comparative Example 6 was the nano-peak structure surface. Wiping was performed using non-woven fabric, and the number of wipes was 1000. A roll-off angle < 10° indicates good self-cleaning effect of the optical panel, while a roll-off angle > 10° indicates poor self-cleaning effect.

[0043] (3) Anti-fingerprint level: Press the test surface of the optical panel of each embodiment and comparative example with the index finger for 5 seconds before and after wiping. After removing the finger for 3 seconds, observe the fingerprint residue: Level 4 - no trace; Level 3 - slight trace, which can be easily wiped off with the finger; Level 2 - slight trace, which cannot be wiped off with the finger; Level 1 - obvious trace, which cannot be wiped off with the finger. Among them, the test surface of Examples 1-4 and Comparative Examples 1-5 is the AF anti-fingerprint layer, and the test surface of Comparative Example 6 is the nano-peak structure surface. The wiping is performed with non-woven cloth, and the number of wiping times is 1000.

[0044] Table 1

[0045] Based on the test data in Examples 1-4 of this application and Table 1, it can be seen that the optical panels prepared in Examples 1-4 of this application have a water contact angle greater than 150° and a roll-off angle less than 10° before and after wiping. They have the superhydrophobicity and low adhesion effect of lotus leaves. In addition, the anti-fingerprint level is 4. That is, the optical panels in Examples 1-4 have durable and stable superhydrophobicity, self-cleaning performance and anti-fingerprint contamination performance.

[0046] Based on the test data in Example 1 and Comparative Example 1, Example 3 and Comparative Example 2 of this application, and Table 1, it can be seen that when the same deposition process is used, but the size and spacing of the nano-peak structure are not within the scope of this application, the water contact angle of the optical panel after wiping is less than 150°, the roll-off angle is greater than 10°, and the anti-fingerprint level is reduced to 3. It can be seen that the size and spacing of the nano-peak structure affect the superhydrophobicity, self-cleaning ability and anti-fingerprint contamination ability of the optical panel.

[0047] Based on the data from Examples 1 and 3, Examples 3 and 4, and Table 1, it can be seen that while the deposition process parameters control the height of the nanospike structures to be the same, the spacing and aspect ratio of the nanospike structures are outside the scope of this application. This indicates that the deposition process is crucial for obtaining nanospike structures of specific dimensions and spacing. Furthermore, the optical panel obtained in Comparative Example 3 exhibits a reduced water contact angle, and after wiping, the water contact angle is less than 150° and the roll-off angle is greater than 10°, which is detrimental to achieving durable superhydrophobicity and self-cleaning properties. Similarly, the optical panel obtained in Comparative Example 4 exhibits a reduced water contact angle and increased roll-off angle, and after wiping, the water contact angle is less than 150° and the roll-off angle is greater than 10°, which is also unfavorable for obtaining an optical panel with both superhydrophobic and self-cleaning properties.

[0048] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a superhydrophobic self-cleaning optical panel, characterized in that, The method comprises the following steps: S1, cleaning the glass substrate to ensure the surface is clean; S2, placing the cleaned glass substrate into a PECVD reaction chamber, and evacuating to vacuum to remove impurity gas; S3, depositing a nano-spiked structure with uniform arrangement and conical shape on the glass substrate, the nano-spiked structure being made of silicon oxide and silicon nitride; S4, activating the glass substrate with the nano-spiked structure by oxygen plasma; S5, plating an AF anti-fingerprint layer on the nano-spiked structure of the activated glass substrate to obtain a super-hydrophobic self-cleaning optical panel; The height of the nano-spiked structure ranges from 200 to 300 nm, the distance between adjacent nano-spiked structures ranges from 30 to 50 nm, and the aspect ratio of the nano-spiked structure ranges from 1.2 to 1.

5. 2.The method of claim 1, wherein: When the nano-spiked structure is made of silicon nitride, the step S3 is performed as follows: SiH4, NH3 and a fluorine-containing etching gas are introduced into the PECVD reaction chamber, and a nano-spiked structure with uniform arrangement and conical shape is deposited on the glass substrate after high-frequency ionization; the specific parameters are as follows: the temperature of the glass substrate is 230-250℃, the radio frequency power is 300-400W, the radio frequency is 13.56 MHz, the pressure of the PECVD reaction chamber is 80-100Pa, the flow rate of the fluorine-containing etching gas is 15-25sccm, and the flow rate ratio of SiH4, NH3 and the fluorine-containing etching gas is (1-1.5):(2-3):

1.

3. The method of claim 2, wherein the method further comprises: The fluorine-containing etching gas is any one of CF4, NF3 and SF6.

4. The method of claim 1, wherein the method further comprises: When the nano-spiked structure is made of silicon oxide, the step S3 is performed as follows: SiH4, N2O and an inert gas are introduced into the PECVD reaction chamber, and a nano-spiked structure with uniform arrangement and conical shape is deposited on the glass substrate after high-frequency ionization; the specific parameters are as follows: the temperature of the glass substrate is 230-250℃, the radio frequency power is 300-400W, the radio frequency is 13.56 MHz, the pressure of the PECVD reaction chamber is 3-8Pa, the flow rate of N2O is 5-10sccm, and the flow rate ratio of SiH4, N2O and the inert gas is (8-10):1:

100.

5. The method of claim 1, wherein the method further comprises: In the step S4, the PECVD reaction chamber is evacuated, and then oxygen is introduced into the PECVD reaction chamber; the glass substrate with the nano-spiked structure is activated by oxygen plasma under the conditions of radio frequency power of 50-100W, radio frequency of 13.56 MHz, pressure of the PECVD reaction chamber of 20-50Pa, and oxygen flow rate of 4-8sccm for a time period of 30-40s to obtain the activated glass substrate.

6. The method of claim 1, wherein the method further comprises: In S5, the AF anti-fingerprint layer is deposited by AF coating pills in a vacuum degree less than 10 -3 Pa.

7. The method of claim 6, wherein the method further comprises: The deposition rate of the AF plating film pill is 0.1-0.5nm / s. 8.The method of claim 6, wherein the method further comprises: coating a layer of the hydrophobic material on the surface of the optical panel. The thickness of the AF anti-fingerprint layer is 5-10nm.

9. A superhydrophobic self-cleaning optical faceplate, characterized by: The super-hydrophobic self-cleaning optical panel is prepared by the method of any one of claims 1-8.

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