PTFE-SiO2 transparent anti-reflection hydrophobic film as well as preparation method and application thereof

Abstract

The invention discloses a PTFE-SiO2 transparent anti-reflection hydrophobic film as well as a preparation method and application thereof, and relates to the technical field of optical films. According to the method, glass is used as a substrate, a radio frequency magnetron co-sputtering method is adopted, a PTFE target and an SiO target with the purity of 99.9% are used as target materials, high-purity Ar gas is used as sputtering gas, and the PTFE-SiO composite film is deposited on the substrate. The average light transmittance of the film in the wave band of 400-1100 nm is 91.0%-93.5%, and the peak transmittance reaches 94.7%; the surface water contact angle ranges from 100 degrees to 105 degrees; and the hardness of the pencil is 4H-7H. The process does not need subsequent etching, coating or curing treatment, is suitable for large-area industrial preparation, and can be applied to solar cells, display equipment, optical lenses, transparent electric heating devices, building glass and automobile glass.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, and in particular to a PTFE-SiO2 transparent antireflective hydrophobic thin film, its preparation method and application. Background Technology

[0002] Transparent anti-reflective hydrophobic coatings, with their dual functions of improving light transmittance and self-cleaning / anti-fouling, have become a key technology for upgrading products such as solar cells, automotive displays, optical lenses, and architectural glass. From a technical perspective, transparent self-cleaning coatings are mainly divided into two categories: hydrophobic and hydrophilic. Hydrophobic coatings remove dirt by allowing water droplets to roll off, making them suitable for complex outdoor environments and attracting more industry attention. Excellent mechanical properties (hardness, abrasion resistance) are a crucial prerequisite for their practical application. However, the practical application of hydrophobic coatings is limited by two major technological bottlenecks: first, the contradiction between optical and mechanical properties. Many hydrophobic coatings introduce fluorine-based materials (such as PTFE) to achieve low surface energy, resulting in extremely low film hardness (typically ≤2H) and poor abrasion resistance, making them difficult to withstand everyday scratches; second, the issue of process compatibility, requiring large-area, low-cost, and environmentally friendly industrial production while ensuring performance uniformity.

[0003] Currently, the mainstream preparation technologies for transparent antireflective and hydrophobic films have significant shortcomings: the sol-gel method can achieve transparency, antireflection, and hydrophobicity, but the film layer is loose, with a hardness ≤3H, making it easy to scratch and peel off. In addition, the process is complex, pollutes the environment, and has poor repeatability, making it unsuitable for large-scale industrial production. Although chemical vapor deposition can prepare dense films with strong adhesion, it still faces challenges in achieving comprehensive control of high light transmittance, high hydrophobicity, and good antireflection performance. Moreover, the process equipment is complex and costly, and toxic precursors may be used during the reaction, posing certain pressures on the environment and operational safety.

[0004] Magnetron sputtering is a preferred technology for preparing high-quality optical thin films, possessing advantages such as environmental friendliness, controllable process parameters, high film density, and suitability for large-area deposition. However, existing magnetron sputtering-based technologies still have performance shortcomings: The ZnO-PTFE transparent hydrophobic film reported by Lippili et al. in *J. Mater. Chem. A*, Vol. 10, 2022, while achieving a contact angle of 105.2° and a hardness of 5.21±0.66 GPa, only achieved a transmittance of 87.4% at the critical wavelength of 550 nm, failing to meet the core requirement for anti-reflection (typically ≥90%). The SZO / PTFE bilayer film disclosed in *ACS Sustainable Chem. Eng.*, Vol. 10, 2022, achieved a 550 nm transmittance of 91.86%, but this did not exceed the transmittance of the glass substrate used (92%), and the bilayer structure design increased process complexity and production costs. Chinese patent CN 117169996... The disclosed moth-eye structure antireflective hydrophobic film based on a flexible substrate integrates high transmittance, scratch resistance and hydrophobicity, but adopts a multi-step process of "magnetron sputtering coating + wet / dry etching + fluorosilane coating + curing". The etching process is prone to introducing surface defects, affecting optical uniformity. Moreover, the coupling of multiple processes leads to low production efficiency and difficulty in controlling yield, making it unsuitable for large-scale applications. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for preparing a PTFE-SiO2 transparent antireflective hydrophobic film that is simple in process, environmentally friendly, can be mass-produced, and has high light transmittance, high hardness and excellent hydrophobicity, so as to overcome the shortcomings of existing transparent antireflective hydrophobic films that are difficult to balance optical and mechanical properties and have complex processes.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a PTFE-SiO2 transparent antireflective hydrophobic film, comprising the following steps: using radio frequency magnetron co-sputtering, using PTFE target and SiO2 target with a purity of 99.9% as target materials, and Ar gas with a purity of ≥99.99% as sputtering gas, by controlling the sputtering pressure, target power density and substrate temperature, uniform dispersion and phase structure control of SiO2 in the PTFE matrix are achieved, and finally a PTFE-SiO2 transparent antireflective hydrophobic film is deposited on the substrate.

[0007] Preferably, to obtain high antireflectivity, hydrophobicity, and mechanical hardness, the sputtering conditions in the step are optimized as follows: RF co-sputtering of PTFE target and SiO2 target, sputtering gas is high-purity Ar gas with a purity ≥99.99%, sputtering pressure is 0.3~2 Pa, sputtering power density of PTFE target is 2.5~5 W・cm⁻², sputtering power density of SiO2 target is 1.5~3 W・cm⁻², and substrate temperature is room temperature (25℃±5℃)~150 ℃.

[0008] More preferably, the substrate is a glass substrate; a PTFE-SiO2 composite film with a thickness of 70~160 nm is deposited on the surface of the substrate.

[0009] More preferably, the PTFE-SiO2 transparent antireflective hydrophobic film has an average transmittance of 91.0%~93.5% (including the substrate) in the visible-near infrared band of 400~1100 nm, an average transmittance of 92.0%~94.5% (including the substrate) in the visible band of 500~800 nm, a peak transmittance of 92.3%~94.7% (including the substrate), a surface water contact angle of 100°~105°, and a pencil hardness of 4H~7H, which is much higher than that of existing single PTFE films (hardness ≤2H).

[0010] In addition, the present invention also provides a PTFE-SiO2 transparent antireflective hydrophobic film, which is prepared by the above-described preparation method.

[0011] Preferably, the PTFE-SiO2 transparent antireflective hydrophobic film is applied in optoelectronic devices or glass products; the optoelectronic devices or glass products include solar cells, display devices, optical lenses, transparent electric heating devices, architectural glass and automotive glass.

[0012] More preferably, the structure of the transparent electric heating device, from bottom to top, includes: a substrate, an AZO layer, an Ag layer, a PTFE-SiO2 composite film layer, and a metal electrode layer, wherein the material of the metal electrode layer is Ag or Al.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] 1. For the first time, PTFE and SiO2 were uniformly composited by magnetron sputtering co-deposition, which solved the core contradiction of "high hydrophobicity and low hardness" in fluorine-based thin films, while ensuring high light transmittance and anti-reflection function.

[0015] 2. No subsequent etching, coating or curing treatment is required, the process steps are simplified, the repeatability is high, it is suitable for large-area industrial deposition, and there are no toxic precursors used, which is environmentally friendly. The whole process is efficient and environmentally friendly.

[0016] 3. The thin film has a balanced overall performance and can be adapted to the needs of various applications such as optoelectronic devices, transportation glass, and architectural glass, making it widely applicable. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the PTFE-SiO2 transparent antireflective hydrophobic film of the present invention;

[0018] Figure 2 The transmittance spectrum of the PTFE-SiO2 transparent antireflective hydrophobic film in Example 1 in the wavelength range of 300~1100 nm (including the glass substrate).

[0019] Figure 3 This is a test diagram of the surface water contact angle of the PTFE-SiO2 transparent antireflective hydrophobic film in Example 1 (contact angle 103°).

[0020] Figure 4 The results of the pencil hardness test (6H, according to GB / T 6739-2006) of the PTFE-SiO2 transparent antireflective hydrophobic film in Example 1 are shown.

[0021] Figure 5 This is a schematic diagram of the structure of the PTFE-SiO2 transparent antireflective hydrophobic film of the present invention applied to a transparent electric heating device.

[0022] In the picture:

[0023] 1. Glass substrate; 2. AZO thin film; 3. Ag thin film; 4. PTFE-SiO2 composite film; 5. Metal electrode. Detailed Implementation

[0024] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0025] In each embodiment of the present invention, ultra-white glass with a thickness of 1.8 mm is used as the substrate.

[0026] Example 1

[0027] A PTFE-SiO2 transparent antireflective hydrophobic thin film and its preparation method, comprising the following steps:

[0028] A PTFE-SiO2 composite film with a purity of 99.9% was co-sputtered onto a glass substrate using magnetron sputtering, with a thickness of approximately 100 nm. The sputtering conditions were: substrate temperature 150℃, PTFE target power density 3.75 W / cm², SiO2 target power density 2 W / cm², Ar gas flow rate 30 sccm, and working pressure 1 Pa.

[0029] The PTFE-SiO2 transparent antireflective hydrophobic thin film structure prepared by the above method is as follows: Figure 1 As shown, the thickness of the film is 100 nm.

[0030] Figure 2 The transmittance spectrum (including glass substrate) of the PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment is in the wavelength range of 300~1100 nm. Figure 3 This refers to the water contact angle on the surface of the PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment. Figure 4 The pencil hardness of the PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment is given.

[0031] The PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment has a peak transmittance of 93.1% (707 nm, including the substrate) in the wavelength range of 300–1100 nm, an average transmittance of 91.8% (including the substrate) in the wavelength range of 400–1100 nm, an average transmittance of 92.6% (including the substrate) in the wavelength range of 500–800 nm, a surface water contact angle of 103°, and a pencil hardness of 6H.

[0032] Example 2

[0033] A PTFE-SiO2 transparent antireflective hydrophobic thin film and its preparation method, comprising the following steps:

[0034] Using PTFE and SiO2 targets with a purity of 99.9%, a 100 nm thick PTFE-SiO2 composite film was co-deposited on a glass substrate by magnetron sputtering. The sputtering conditions were: glass substrate temperature 150 °C, and sputtering power densities of 3.75 W / cm² for the PTFE and SiO2 targets, respectively. 2 and 2.5 W / cm 2 The sputtering gas is Ar, the gas flow rate is 30 sccm, and the working pressure is 1 Pa.

[0035] The PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment has a peak transmittance of 93.0% (672 nm, including the substrate) in the wavelength range of 300–1100 nm, an average transmittance of 91.3% (including the substrate) in the 400–1100 nm band, an average transmittance of 92.5% (including the substrate) in the 500–800 nm band, a surface water contact angle of 102°, and a pencil hardness of 7H.

[0036] Example 3

[0037] A PTFE-SiO2 transparent antireflective hydrophobic thin film and its preparation method, comprising the following steps:

[0038] Using PTFE and SiO2 targets with a purity of 99.9%, a 100 nm thick PTFE-SiO2 composite film was co-deposited on a glass substrate by magnetron sputtering. The sputtering conditions were: glass substrate temperature 100 °C, and sputtering power densities of 3.5 W / cm² for the PTFE and SiO2 targets, respectively. 2 and 2 W / cm 2 The sputtering gas is Ar, the gas flow rate is 30 sccm, and the working pressure is 0.3 Pa.

[0039] The PTFE-SiO2 transparent antireflective hydrophobic film prepared in this embodiment has a peak transmittance of 94.7% (611 nm, including the substrate) in the wavelength range of 300–1100 nm, an average transmittance of 93.5% (including the substrate) in the 400–1100 nm band, and an average transmittance of 94.2% (including the substrate) in the 500–800 nm band. The water contact angle of the film surface is 105°, and the pencil hardness is 4H.

[0040] Example 4

[0041] A PTFE-SiO2 transparent antireflective hydrophobic thin film and its preparation method, comprising the following steps:

[0042] Using PTFE and SiO2 targets with a purity of 99.9%, a 100 nm thick PTFE-SiO2 composite film was co-deposited on a glass substrate by magnetron sputtering. The sputtering conditions were: glass substrate temperature 150 °C, and sputtering power densities of 3.75 W / cm² for the PTFE and SiO2 targets, respectively. 2 and 2 W / cm 2 The sputtering gas is Ar, the gas flow rate is 30 sccm, and the working pressure is 1 Pa.

[0043] The PTFE-SiO2 composite film was applied to a transparent electric heating device. Figure 3 This is a schematic diagram of the transparent electric heating device. Using magnetron sputtering, an AZO thin film with a thickness of approximately 50 nm is first prepared on a glass substrate; then, an ultrathin Ag layer with a thickness of approximately 10 nm is deposited on the AZO film; next, a PTFE-SiO2 layer with a thickness of approximately 100 nm is deposited on the Ag film; finally, a metal Ag or Al electrode is deposited on the top layer. These features constitute the transparent electric heating device.

[0044] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified. The above embodiments are preferred implementations of this invention. In addition, this invention can be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this invention.

Claims

1. A method for preparing a PTFE-SiO2 transparent antireflective hydrophobic thin film, characterized in that: A transparent antireflective hydrophobic PTFE-SiO2 film was deposited on a substrate using radio frequency magnetron co-sputtering with PTFE and SiO2 targets, both with a purity of 99.9%, and Ar gas with a purity of ≥99.99%.

2. The method for preparing a PTFE-SiO2 transparent antireflective hydrophobic thin film according to claim 1, characterized in that: The substrate is a glass substrate.

3. The method for preparing a PTFE-SiO2 transparent antireflective hydrophobic thin film according to claim 1, characterized in that: The sputtering pressure of the radio frequency co-sputtering method is 0.3~2 Pa, and the sputtering power density of the PTFE target is 2.5~5 W / cm³. 2 The sputtering power of the SiO2 target is 1.5~3W / cm. 2 The substrate temperature is 25℃~150℃.

4. The method for preparing a PTFE-SiO2 transparent antireflective hydrophobic thin film according to claim 1, characterized in that: The thickness of the deposited PTFE-SiO2 transparent antireflective hydrophobic film is 70-160 nm.

5. A PTFE-SiO2 transparent antireflective hydrophobic thin film, characterized in that: It is prepared by the preparation method described in any one of claims 1-4.

6. The application of the PTFE-SiO2 transparent antireflective hydrophobic film according to claim 5, characterized in that: It is applied in optoelectronic devices or glass products; the optoelectronic devices or glass products include solar cells, display devices, optical lenses, transparent electric heating devices, architectural glass and automotive glass.

7. The application of the PTFE-SiO2 transparent antireflective hydrophobic film according to claim 5, characterized in that: The structure of the transparent electric heating device, from bottom to top, includes: a substrate, an AZO layer, an Ag layer, a PTFE-SiO2 composite film layer, and a metal electrode layer, wherein the material of the metal electrode layer is Ag or Al.

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