Antireflection film and method for producing the same

Abstract

This invention discloses an antireflective film and its preparation method. The antireflective film comprises a substrate layer, a first coating layer, a second coating layer, a third coating layer, and a fourth coating layer stacked sequentially. The fourth coating layer is made of any one of aluminum-doped silicon dioxide, boron-doped silicon dioxide, or hafnium-silicon composite oxide. The refractive index of the first coating layer is greater than that of the second and fourth coating layers. The refractive index of the third coating layer is greater than that of the second and fourth coating layers. This invention uses material doping modification (such as aluminum-doped silicon dioxide or boron-doped silicon dioxide) and high-performance composite materials (Hf-Si-O composite) to prepare the antireflective film, giving it low reflectivity, high transmittance, high weather resistance, and excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of optical film technology, specifically relating to an antireflective film and its preparation method. Background Technology

[0002] AR film (also known as anti-reflective coating) is a high-transmittance optical film that reduces reflection and allows light to pass through more completely. It is widely used in high-end smartphone cover plates, tablet screens, automotive displays and other fields that have high requirements for optical performance, thinness and durability.

[0003] AR films typically consist of a substrate and functional layers. By incorporating these functional layers, the anti-reflective and anti-reflective properties of the AR film are achieved. SiO2, with its relatively ideal refractive index, is often used as the surface layer of AR films. However, a pure SiO2 layer as the surface layer suffers from weak weather resistance and poor chemical stability, limiting the performance and lifespan of AR films in high-end applications and making it difficult to meet consumer demands for high-quality optical products. Summary of the Invention

[0004] The purpose of this invention is to provide an antireflective film and its preparation method, wherein the antireflective film has low reflectivity, high transmittance, high weather resistance and excellent mechanical properties.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0006] An antireflective film, the antireflective film comprising a substrate layer, a first coating layer, a second coating layer, a third coating layer, and a fourth coating layer stacked sequentially;

[0007] The material of the fourth coating layer is any one of aluminum-doped silicon dioxide, boron-doped silicon dioxide, and hafnium-silicon composite oxide;

[0008] The refractive index of the first coating layer is greater than the refractive index of the second coating layer and the refractive index of the fourth coating layer;

[0009] The refractive index of the third coating is greater than that of the second coating and the fourth coating.

[0010] In one or more embodiments of the present invention, the mass fraction of aluminum in the aluminum-doped silicon dioxide is 2%-10%; or,

[0011] The mass fraction of boron in the boron-doped silicon dioxide is 5%-15%; or,

[0012] In the hafnium-silicon composite oxide, the molar ratio of hafnium atoms to silicon atoms is 1:4 to 1:1.5.

[0013] In one or more embodiments of the present invention, the refractive index of the first coating is 2.0-2.5; and / or,

[0014] The refractive index of the second coating is 1.38-1.46; and / or,

[0015] The refractive index of the third coating is 2.0-2.5; and / or,

[0016] The refractive index of the fourth coating is 1.46-1.67.

[0017] In one or more embodiments of the present invention, the material of the first coating is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide; and / or,

[0018] The material of the second coating is any one or more of silicon dioxide, magnesium fluoride, and aluminum oxide; and / or,

[0019] The material of the third coating is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide.

[0020] In one or more embodiments of the present invention, the thickness of the first coating is 10 nm-20 nm; and / or,

[0021] The thickness of the second coating is 29nm-39nm; and / or,

[0022] The thickness of the third coating is 115nm-125nm; and / or,

[0023] The thickness of the fourth coating is 80nm-100nm.

[0024] In one or more embodiments of the present invention, an underlayer is further provided between the substrate layer and the first coating layer. The material of the underlayer is any one or more of silicon dioxide, aluminum oxide, hafnium dioxide, elemental titanium, and elemental silicon, and the thickness of the underlayer is 1nm-5nm.

[0025] In one or more embodiments of the present invention, an acrylic resin curing layer is provided on both sides of the substrate layer, and the thickness of the acrylic resin curing layer is 210nm-230nm.

[0026] In one or more embodiments of the present invention, the material of the substrate layer is any one of PET, PI, PEN, COP, PMMA, TAC, LCP, and SRF; and / or,

[0027] The thickness of the substrate layer is 7.5μm-250μm.

[0028] In one or more embodiments of the present invention, the fourth coating layer is further provided with an AF layer, the thickness of which is 5nm-15nm.

[0029] Another specific embodiment of the present invention provides the following technical solution:

[0030] A method for preparing an antireflective film, the method comprising the following steps:

[0031] Take a substrate and deposit a first coating layer, a second coating layer, a third coating layer and a fourth coating layer on the substrate in sequence to obtain an anti-reflective film.

[0032] Compared with existing technologies, this invention uses material doping modification (such as aluminum-doped silicon dioxide, boron-doped silicon dioxide) and high-performance composite materials (Hf-Si-O composite) to prepare antireflective films, achieving: (1) comprehensive optimization of optical performance: lower reflectivity, higher transmittance, better color difference control and angular stability; (2) significant improvement in environmental reliability: stronger resistance to damp heat, weathering and chemical corrosion, ensuring stable performance in long-term use; (3) enhancement of mechanical properties: higher surface hardness, better wear resistance, stronger film adhesion and structural integrity; (4) professional expansion of functionality: a better surface protection foundation, providing a better platform for additional functions such as anti-fingerprint. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the antireflective film in one embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of an antireflective film with an acrylic resin curing layer in one embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of the antireflective film with an underlayer in one embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of an antireflective film with an AF layer in one embodiment of the present invention.

[0038] Explanation of key figure labels:

[0039] 1. Substrate layer; 2. First coating layer; 3. Second coating layer; 4. Third coating layer; 5. Fourth coating layer; 6. Acrylic resin curing layer; 7. Undercoat layer; 8. AF layer. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0041] While a pure SiO2 layer serves as the surface layer of an AR film and possesses an ideal refractive index, it suffers from the following drawbacks:

[0042] 1. Insufficient hardness: Although SiO2 itself has a high hardness, the structure of the film prepared by conventional evaporation may not be dense enough, resulting in the wear resistance (scratch resistance) not meeting the highest requirements.

[0043] 2. Poor chemical stability: It is relatively weak in its resistance to strong alkalis (such as sweat and detergents), and long-term exposure may result in "white fog" corrosion.

[0044] 3. Weak weather resistance: It has limited resistance to environmental factors such as ultraviolet radiation, ozone, and acidic and alkaline gases. It is prone to aging, yellowing, and performance degradation when used outdoors for a long time or in harsh environments.

[0045] 4. Poor environmental stability: When exposed to a humid and hot environment for a long time, the outer layer of pure SiO2 is prone to physical structural changes, resulting in decreased film adhesion and fluctuations in reflectivity.

[0046] 5. Internal stress: Pure SiO2 film usually exhibits tensile stress. Improper stress matching with the underlying film may affect the overall bonding force or lead to cracking.

[0047] To address the above deficiencies, this invention obtains an antireflective coating that can meet consumers' demands for high-quality optical products through material modification, structural optimization, or the introduction of a protective functional layer.

[0048] A specific embodiment of the present invention provides an antireflective film, such as... Figure 1 As shown, it includes a substrate layer 1, a first plating layer 2, a second plating layer 3, a third plating layer 4, and a fourth plating layer 5, which are stacked in sequence.

[0049] Furthermore, the material of the substrate layer 1 is any one of PET, PI, PEN, COP, PMMA, TAC, LCP, and SRF; the thickness of the substrate layer 1 is 7.5μm-250μm.

[0050] Specifically, PET (polyethylene terephthalate) is low in cost, has good mechanical properties, and excellent chemical resistance, with thicknesses ranging from 12μm to 250μm. PI (polyimide) is heat-resistant (>350℃) and has excellent dimensional stability, with thicknesses ranging from 7.5μm to 125μm. PEN (polyethylene naphthalate) has similar but better properties to PET, with higher temperature resistance and better barrier properties, with thicknesses ranging from 214μm to 216μm. COP (cyclic olefin polymer) has high transparency, low birefringence, and low moisture absorption, with thicknesses ranging from 10μm to 250μm. PMMA (polymethyl methacrylate) has high hardness, high transparency, and is easy to dye, with thicknesses ranging from 50μm to 500μm. TAC (cellulose triacetate) has good optical properties and excellent light transmittance, with thicknesses ranging from 20μm to 100μm. LCP (liquid crystal polymer) has good high-frequency performance and extremely low moisture absorption, with thicknesses ranging from 25μm to 100μm. SRF (Surface Treated Barrier Film) has ultra-high water and oxygen barrier properties, and its thickness can range from 50μm to 150μm.

[0051] In actual production, the type and thickness of the various substrates mentioned above need to be precisely determined based on the specific performance indicators of the product. If cost-effectiveness is the priority, PET substrate can be chosen, as it has the lowest cost, balanced overall performance, and the most mature processing technology. If optical performance or high transparency is the priority, COP, PMMA, or TAC can be chosen, with light transmittance >90%.

[0052] Furthermore, the material of the first coating layer 2 is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide, and the material of the third coating layer 4 is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide.

[0053] Specifically, the core functional layer in the construction of interference films is usually prepared using electron beam evaporation or magnetron sputtering. Thermal evaporation is achieved by bombarding high-purity target materials with a high-energy electron beam, or sputtering effect is generated by ionizing argon ions with a high-voltage electric field, so that target atoms / molecules are deposited on the substrate surface, ultimately forming a functional thin film with an optical thickness of λ / 4 (quarter wavelength).

[0054] Furthermore, the material of the second coating layer 3 is any one or more of silicon dioxide, magnesium fluoride, and aluminum oxide, and the material of the fourth coating layer 5 is any one of aluminum-doped silicon dioxide, boron-doped silicon dioxide, and hafnium-silicon composite oxide.

[0055] Specifically, low-refractive-index and high-refractive-index films are periodically stacked alternately to collaboratively construct a multi-wavelength interference system. By adjusting the interference destructive conditions, the low-refractive-index films effectively extend the operating range of the anti-reflection band. The optimized design of the multilayer film system allows multiple characteristic wavelengths in the visible light band to simultaneously satisfy the interference destructive conditions, significantly reducing the overall reflectivity.

[0056] The first coating, as the initial high-refractive-index layer, primarily functions to establish the basic interference effect. The second coating, together with the first coating, forms the first interference matching pair, serving as a key structural unit for achieving the basic antireflection effect and forming preliminary reflection suppression. The third coating further enhances the cumulative effect of the high-refractive-index components, effectively expanding the coverage range of the low-reflection spectrum. The fourth coating, through optimized design, improves the overall performance of the antireflection film.

[0057] This invention optimizes the design of the outermost fourth coating layer, as follows:

[0058] The first and fourth coatings are made of aluminum-doped silicon dioxide. Doping modification technology (introducing Al elements into the Si matrix) is the most direct modification method. This scheme optimizes performance by controlling the chemical composition of the target material, specifically using an aluminum-doped silicon dioxide system.

[0059] 1. Target material preparation (the physical basis of doping) mainly adopts the following three process routes:

[0060] (1) Hybrid Sintered Target (Mainstream Solution, Balancing Stability and Consistency). Process Description: High-purity Si powder and Al powder are mixed at a preset mass ratio or atomic percentage, dispersed by ball milling, molded, and sintered at high temperature to form a composite target. Proportion: Al mass fraction is controlled at 2%-10% (corresponding to approximately 3 at%-15 at% Al atomic percentage). It is recommended to use 5 wt% Al (approximately 7 at% Al) for initial experiments, as this ratio exhibits excellent performance in hardness control and refractive index balance. Advantages: High compositional uniformity, good process repeatability, suitable for large-scale production.

[0061] (2) Embedded Target (Flexible Solution, Suitable for Small-Scale Exploration). Process Description: High-purity aluminum (Al) or aluminum oxide (Al2O3) sheets are regularly embedded on the surface of a pure Si-based target. The doping level is roughly controlled by adjusting the number, size, and distribution of the embedded elements. Proportion Control: The doping concentration is indirectly controlled by the aluminum sheet parameters (number / size / distribution). Advantages: No need to customize new targets; different doping levels can be quickly verified. Limitations: Insufficient uniformity of film composition; not suitable for large-scale mass production.

[0062] (3) Co-sputtering (high-precision scheme, achieving atomic-level control). Process description: Simultaneous sputtering of a pure Si target and a pure Al (or Al2O3) target with independent settings is used. The deposition rate of Si and Al is independently controlled by precisely adjusting the sputtering power (kW) of the two targets, achieving atomic-level precise doping. Doping amount calculation: The Al doping ratio is directly determined by the ratio of Al target power to the total power of the two targets (Al target power / (Si target power + Al target power)). Advantages: Supports real-time, stepless, and high-precision doping control, with excellent compositional uniformity.

[0063] 2. Optimization of coating process parameters (taking magnetron sputtering as an example)

[0064] Regardless of the target material system used, the following key process parameters must be systematically optimized:

[0065] The sputtering gas is high-purity argon (Ar), and oxygen (O2) needs to be introduced to ensure that Al is completely oxidized to Al2O3. At the same time, the O2 flow rate must be precisely controlled to avoid blackening of the film (light absorption phenomenon). The working pressure is usually maintained in the range of 0.1 Pa to 0.5 Pa. Lower pressure helps to form a higher density film structure.

[0066] 3. Advantages of the solution:

[0067] (1) Increased density: aluminum ions (Al 3+ The introduction of ) can disrupt the periodic structure of the SiO2 amorphous network and promote the formation of a denser, harder ceramic-like microstructure during the deposition process.

[0068] (2) Improved mechanical properties: The bond energy of Al-O bond is significantly higher than that of Si-O bond, which can effectively improve the microhardness and scratch resistance of the film.

[0069] (3) Improved chemical stability: The doped film generally has better tolerance to alkaline environment than the pure SiO2 substrate.

[0070] The second and fourth coatings are made of boron-doped silicon dioxide. The specific implementation scheme for boron-doped silicon dioxide is highly similar to that for aluminum-doped silicon dioxide, but there are significant differences in the selection of doping materials and functional emphasis.

[0071] 1. Hybrid sintering target

[0072] Process Description: Composite targets are prepared by high-temperature sintering of Si and B mixed powders. Doping Ratio: The B doping level can be slightly higher than the conventional Al doping level, with the B mass fraction controlled between 5 wt% and 15 wt%, and an initial experimental concentration of 10 wt% recommended. B has strong hygroscopic properties; excessively high boron content may lead to decreased film environmental stability, requiring systematic optimization to determine the optimal doping ratio.

[0073] 2. Co-sputtering process

[0074] Process Description: Doping is achieved through synergistic sputtering of a Si target with a B (metallic boron) or B₂O₃ target. Key Limitation: If a metallic boron target is used, sufficient oxygen must be introduced to ensure the complete success of the reactive sputtering process.

[0075] Coating process parameters: The basic parameter range is similar to that of the aluminum doping scheme, but the optimization focus of the boron doping process is unique:

[0076] (1) Substrate temperature adaptability: The core advantage of boron doping is that it can obtain high-quality film at lower substrate temperatures. This characteristic has important application value for plastic substrates with limited temperature resistance (such as polycarbonate PC and polymethyl methacrylate PMMA).

[0077] (2) Stress regulation and optimization: The main function of boron doping is to reduce and optimize the stress in the film. During the process development, it is necessary to focus on monitoring the stress change curve and seek process combinations that make the film stress approach neutral or present a state of micro-compressive stress by adjusting parameters (such as temperature, sputtering rate, etc.).

[0078] The third and fourth coatings are made of hafnium-silicon composite oxide (Hf-Si-O composite). The Hf-Si-O composite (completely replacing the surface material) employs a composite system that combines low refractive index with excellent mechanical properties—a composite of hafnium dioxide (HfO2) and silicon dioxide (SiO2). The atomic ratio of Hf to Si is controlled between 1:4 and 1:1.5 (i.e., Hf atoms account for 20%-40%), precisely adjusted through processes such as reactive sputtering to meet different performance requirements.

[0079] Mechanism of action: HfO2, as a typical high-hardness and high-chemical-stability material, has a significantly high intrinsic refractive index (>2.0). By precisely controlling core process parameters such as reactive sputtering, Hf-Si-O mixed oxide materials can be prepared. This material not only achieves continuous tunability of the refractive index between SiO2 and HfO2, but also fully inherits the high hardness and excellent chemical inertness of HfO2.

[0080] Key technical approach: This approach is difficult to implement. It typically uses Hf-Si alloy targets and performs reactive sputtering in an oxygen-argon mixed atmosphere. The composition ratio and refractive index are directionally controlled by precisely adjusting the oxygen flow rate and sputtering power.

[0081] Furthermore, the thickness of the first coating layer is 10nm-20nm, specifically 10nm, 13nm, 18nm, or 20nm; the thickness of the second coating layer is 29nm-39nm, specifically 29nm, 35nm, or 39nm; the thickness of the third coating layer is 115nm-125nm, specifically 115nm, 120nm, or 125nm; and the thickness of the fourth coating layer is 80nm-100nm, specifically 80nm, 83nm, 90nm, 91nm, 93nm, 98nm, or 100nm.

[0082] Specifically, when the fourth coating material is aluminum-doped silicon dioxide, the refractive index of the material is significantly increased (approximately 1.48-1.55). Through optimized design, the physical thickness is reduced while precisely controlling it to a λ / 4 optical thickness of 550 nm (corresponding to a physical thickness range of approximately 90.8 ± 5 nm). When the fourth coating material is boron-doped silicon dioxide, the refractive index of the material is moderately increased due to boron doping (approximately 1.46-1.50). Through optimized design, the physical thickness is reduced while strictly maintaining a λ / 4 optical thickness at a wavelength of 550 nm (corresponding to a physical thickness range of 92.9 ± 5 nm). This outermost layer has the dual functions of low refractive index matching and surface protection. When the fourth coating material is hafnium silicon composite oxide, the oxygen flow rate is precisely controlled during the coating process to ensure that the final film refractive index is stably maintained at about 1.63-1.67. The optical thickness of this layer is designed according to the λ / 4 optical interference condition, corresponding to the 550 nm characteristic wavelength at a refractive index of 1.63-1.67 (corresponding to a physical thickness range of 83.3±5 nm).

[0083] Furthermore, the refractive index of the first coating is 2.0-2.5, the refractive index of the second coating is 1.38-1.46, the refractive index of the third coating is 2.0-2.5, and the refractive index of the fourth coating is 1.46-1.67.

[0084] Furthermore, such as Figure 2 As shown, acrylic resin curing layers 6 are provided on both sides of the substrate layer 1, and the thickness of the acrylic resin curing layer 6 is 210nm-230nm.

[0085] Specifically, a precision coating process (including but not limited to microgravure coating and slot extrusion coating) is used to directionally coat an acrylic resin primer (a conventional type used in the art) onto the upper and lower surfaces of the substrate. This primer primarily consists of a copolymer of (meth)acrylate and (meth)acrylate hydroxyl esters. Its molecular-level formulation design endows the coating with excellent leveling properties, high transparency, and superior adhesion to the plastic substrate and subsequent film layers. The thickness of the hardened coating is precisely controlled within the range of 210nm-230nm. As the direct substrate for subsequent multilayer optical coatings, its extreme flatness and surface smoothness at the microscopic level play a crucial role in optical performance.

[0086] In the actual preparation process, after the acrylic resin primer is applied, a high-temperature protective film (such as a PET film) with a thickness of 120μm-130μm is immediately bonded on. This protective film has dual core functions: firstly, it provides appearance protection, effectively preventing mechanical scratches or environmental contaminant contamination on the film surface caused by subsequent processing steps (including handling operations, coating rack fixing, etc.); secondly, it provides thermal stability support. In the high vacuum environment of the magnetron sputtering process, the vacuum chamber generates significant heat due to plasma excitation. This protective film inhibits the thermal deformation of the plastic substrate through mechanical support, thereby ensuring the process stability of the coating process and the uniform distribution of the final film thickness.

[0087] Furthermore, such as Figure 3 As shown, a base layer 7 is provided between the substrate layer 1 and the first coating layer 2. The material of the base layer 7 is any one or more of silicon dioxide, aluminum oxide, hafnium dioxide, elemental titanium, and elemental silicon. The thickness of the base layer 7 is 1nm-5nm.

[0088] Specifically, the undercoat layer enhances the interfacial bonding between the optical film system and the acrylic resin hardened layer on the substrate. The dense microstructure of the undercoat layer effectively blocks potential damage to the base coating by plasma during the coating process and provides long-term resistance to moisture penetration and chemical corrosion during use. The thickness of the undercoat layer is typically controlled in the range of 1nm-5nm, which is sufficient to form a continuous and defect-free dense film layer.

[0089] Furthermore, such as Figure 4 As shown, the fourth coating layer 5 is also provided with an AF layer 8, the thickness of which is 5nm-15nm.

[0090] Specifically, the AF layer (also known as the anti-fingerprint layer or anti-fouling layer) imparts excellent easy-to-clean and stain-resistant properties to the product surface. The core component of the AF layer is a low surface energy compound containing fluorinated silanes or fluorinated polyethers, whose molecular structure design results in extremely low surface energy. The manufacturing process can employ wet coating technology (including dip coating, spin coating, or spray coating). The specific operation involves: diluting the AF functional coating (a conventional type in this field) in a specific solvent according to a certain ratio to prepare a uniform working solution; applying this working solution to the surface of the formed AR film using a precise coating process; and then using a thermosetting process to drive the AF material to undergo a molecular-level cross-linking reaction on the surface, ultimately forming an ultra-thin monomolecular anti-fouling film layer with a thickness of only 5nm-15nm and high mechanical strength.

[0091] The working mechanism of the AF layer is based on the principle of surface energy regulation. Its extremely low surface energy makes it difficult for water droplets (contact angle > 110°) and oil droplets to spread on its surface, exhibiting a significant spherical rolling effect. This characteristic not only effectively prevents the adhesion of fingerprint grease and environmental stains, but also makes it easier to wipe away existing contaminants, thereby achieving long-term cleaning and maintenance functions for the product surface.

[0092] Another specific embodiment of the present invention provides a method for preparing an antireflective film, comprising the following steps: taking a substrate, and sequentially depositing a first coating layer, a second coating layer, a third coating layer and a fourth coating layer on the substrate to obtain an antireflective film.

[0093] The present invention will be further described in detail below with reference to specific embodiments.

[0094] Example 1

[0095] The antireflective film in this embodiment is prepared as follows:

[0096] Take a PET substrate with a thickness of 180μm, apply an acrylic resin primer to the upper and lower surfaces of the PET substrate respectively, and after curing, form an acrylic resin hardened layer with a thickness of 210nm.

[0097] A 3nm thick underlayer is deposited on the acrylic resin hardened layer using magnetron sputtering. The underlayer material is silicon dioxide.

[0098] On the substrate, magnetron sputtering is used to sequentially deposit the first, second, and third coating layers. The first coating layer is made of niobium pentoxide with a thickness of 15 nm; the second coating layer is made of silicon dioxide with a thickness of 34 nm; and the third coating layer is made of niobium pentoxide with a thickness of 120 nm.

[0099] A fourth coating layer is deposited on the third coating layer. The specific coating process is as follows: a Si-2wt%Al mixed sintering target is used, and the total sputtering power is set to 12kW (the Al content is low, so no high power is needed to avoid excessive sputtering of Al atoms due to excessive energy, and to ensure that Si is the main body of the deposition); the Ar gas (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the Oxygen (O2) flow rate is 30sccm (Ar:O2=4:1) (the low Al content requires a small amount of oxygen to oxidize only part of the Si to form SiO2, and retain a small amount of Si-Si bonds to balance hardness and brittleness); the substrate temperature is 120℃ (gentle heating during the roll-to-roll coating can promote film densification and reduce internal stress).

[0100] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.48 (meets λ / 4 requirements), physical thickness ≈ 91 nm, average reflectivity in the visible light band (400-700 nm) ≈ 1.2%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0101] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0102] Example 2

[0103] The preparation of the antireflective film in this embodiment is basically the same as in Example 1, except that the specific deposition process of the fourth coating layer is as follows: a Si-5wt%Al mixed sintering target is used. The total sputtering power is set to 13kW (slightly increased to compensate for the difference in sputtering yield of Al atoms); the argon (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the oxygen (O2) flow rate is 40sccm (Ar:O2=3:1) (to increase oxygen to oxidize more Al, forming SiO2-Al2O3 composite oxide, increasing the refractive index to ≈1.50); ​​and the substrate temperature is 120℃.

[0104] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.50, physical thickness ≈ 90.5 nm, average reflectivity in the visible light band (400-700 nm) ≈ 1.1%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0105] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0106] Example 3

[0107] The preparation of the antireflection film in this embodiment is basically the same as in Example 1, except that the specific deposition process of the fourth coating layer is as follows: a Si-10wt%Al mixed sintering target is used. The total sputtering power is set to 15kW (high Al content requires higher power to increase sputtering yield and ensure deposition rate); argon (Ar) flow rate: 120sccm (to maintain plasma stability and provide a sputtering particle source); oxygen (O2) flow rate: 50sccm (Ar:O2=2.4:1) (a large amount of oxygen is used to oxidize Al to form Al2O3, so that the refractive index of the film layer is stabilized at ≈1.52); the substrate temperature is 120℃.

[0108] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.52, physical thickness ≈ 90.8 nm, average reflectance in the visible light band (400-700 nm) ≈ 1.0%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0109] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0110] Example 4

[0111] The preparation of the antireflective film in this embodiment is basically the same as in Example 1. The difference lies in the specific deposition process of the fourth coating layer: a Si-5wt%B mixed sintering target is used, and the total sputtering power is set to 11kW (the B content is low, so no high power is needed, and the B sputtering yield is lower than that of Si, avoiding excessive sputtering of B atoms due to excessive energy, and ensuring that Si is the main deposited component); Ar gas (Ar) flow rate: 120sccm (to maintain plasma stability and provide a sputtering particle source); Oxygen gas (O2) flow rate: 25sccm (Ar:O2=4.8:1) (the low B content requires a small amount of oxygen, which only oxidizes part of the Si to form SiO2, and retains a small amount of Si-Si bonds to balance hardness and brittleness); the substrate temperature is 110℃ (gentle heating during the roll-to-roll coating process can promote film densification and reduce internal stress, and the internal stress of B2O3 is lower than that of Al2O3).

[0112] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.46 (meets λ / 4 requirements), physical thickness ≈ 93 nm, average reflectivity in the visible light band (400-700 nm) ≈ 1.3%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0113] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0114] Example 5

[0115] The preparation of the antireflection film in this embodiment is basically the same as in Example 1. The difference lies in the specific deposition process of the fourth coating layer: a Si-10wt%B mixed sintering target is used, and the total sputtering power is set to 12kW (slightly increased to compensate for the difference in sputtering yield of B atoms); the argon (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the oxygen (O2) flow rate is 35sccm (Ar:O2=3.4:1) (increasing oxygen to oxidize more B to form B2O3-SiO2 composite oxide, increasing the refractive index to ≈1.48); and the substrate temperature is 110℃.

[0116] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.48 (meets λ / 4 requirements), physical thickness ≈ 92.8 nm, average reflectivity in the visible light band (400-700 nm) ≈ 1.1%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0117] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0118] Example 6

[0119] The preparation of the antireflection film in this embodiment is basically the same as in Example 1, except that the specific deposition process of the fourth coating layer is as follows: a Si-15wt%B sintered target is used. The total sputtering power is set to 14kW (high B content requires higher power to increase sputtering yield and ensure deposition rate); the argon (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the oxygen (O2) flow rate is 45sccm (Ar:O2=2.7:1) (a large amount of oxygen is used to oxidize B to form B2O3, so that the refractive index of the film is stabilized at ≈1.50); ​​the substrate temperature is 110℃.

[0120] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.50, physical thickness ≈ 92.9 nm, average reflectance in the visible light band (400-700 nm) ≈ 1.0%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0121] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0122] Example 7

[0123] The preparation of the antireflective film in this embodiment is basically the same as in Example 1, except that the specific deposition process of the fourth coating layer is as follows: a 20at%Hf-80at%Si mixed sintering target is used. The total sputtering power is set to 14kW (the Hf content is low, so no high power is needed; the Hf sputtering yield is lower than that of Si, and low power reduces excessive sputtering of Hf atoms, ensuring the deposition of the Si bulk); the argon (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the oxygen (O2) flow rate is 40sccm (Ar:O2=3:1), as the low Hf content requires a small amount of oxygen, and the oxidized part of Si and Hf forms an Hf-Si-O composite phase, with the refractive index controlled at ≈1.63 (slightly lower than the center value); the substrate temperature is 130℃, and gentle heating during the winding deposition process can promote film densification and reduce internal stress (the intrinsic stress of Hf-Si-O is lower than that of Al2O3).

[0124] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.63 (meets λ / 4 requirements), physical thickness ≈ 83 nm, average reflectivity in the visible light band (400-700 nm) ≈ 1.0%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0125] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0126] Example 8

[0127] The preparation of the antireflective film in this embodiment is basically the same as in Example 1, except that the specific deposition process of the fourth coating layer is as follows: a 30at%Hf-70at%Si sintered target is used. The total sputtering power is set to 15kW (to balance the sputtering yield of Hf and Si and ensure the deposition rate); the argon (Ar) flow rate is 120sccm (to maintain plasma stability and provide a sputtering particle source); the oxygen (O2) flow rate is 50sccm (Ar:O2=2.4:1), which increases oxygen to fully oxidize Hf and Si, forming an Hf-Si-O composite phase with a refractive index stable at ≈1.65; and the substrate temperature is 130℃.

[0128] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.65 (meets λ / 4 requirements), physical thickness ≈ 83.2 nm, average reflectivity in the visible light band (400-700 nm) ≈ 0.9%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0129] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0130] Example 9

[0131] The preparation of the antireflection film in this embodiment is basically the same as in Example 1. The difference lies in the specific deposition process of the fourth coating layer: a 40at%Hf-60at%Si sintered target is used; the total sputtering power is set to 17kW (high Hf content requires higher power to increase sputtering yield and compensate for Hf atom sputtering loss); argon (Ar) flow rate: 120sccm (to maintain plasma stability and provide a sputtering particle source); oxygen (O2) flow rate: 60sccm (Ar:O2=2:1), with a large amount of oxygen used to oxidize Hf to form an HfO2-SiO2 composite phase, increasing the refractive index to ≈1.67 (still within the range of 1.63-1.67); and the substrate temperature is 130℃.

[0132] After the fourth coating was applied, the following tests were conducted: refractive index ≈ 1.67 (meets λ / 4 requirements), physical thickness ≈ 83.3 nm, average reflectivity in the visible light band (400-700 nm) ≈ 0.8%, and adhesion to the third coating Nb2O5 (cross-cut test) ≥ 4B.

[0133] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0134] Comparative Example 1

[0135] The antireflective film in this comparative example was prepared as follows:

[0136] Take a PET substrate with a thickness of 180μm, apply an acrylic resin primer to the upper and lower surfaces of the PET substrate respectively, and after curing, form an acrylic resin hardened layer with a thickness of 210nm.

[0137] A 3nm thick underlayer is deposited on the acrylic resin hardened layer using magnetron sputtering. The underlayer material is silicon dioxide.

[0138] On the substrate, magnetron sputtering is used to sequentially deposit the first, second, third, and fourth coating layers. The first coating layer is made of niobium pentoxide with a thickness of 15 nm; the second coating layer is made of silicon dioxide with a thickness of 34 nm; the third coating layer is made of niobium pentoxide with a thickness of 120 nm; and the fourth coating layer is made of silicon dioxide with a thickness of 94.2 nm.

[0139] An AF coating is applied to the fourth layer, and after curing, an AF layer with a thickness of 10 nm is formed.

[0140] Comparative Example 2

[0141] The preparation of the antireflective film in this comparative example is basically the same as that in Example 1, except that a fourth coating layer is deposited using a Si-1wt%Al mixed sintering target.

[0142] Comparative Example 3

[0143] The preparation of the antireflective film in this comparative example is basically the same as in Example 1, except that a fourth coating layer is deposited using a Si-12wt%Al mixed sintering target.

[0144] Comparative Example 4

[0145] The preparation of the antireflective film in this comparative example is basically the same as that in Example 4, except that a fourth coating layer is deposited using a Si-3wt%B mixed sintering target.

[0146] Comparative Example 5

[0147] The preparation of the antireflective film in this comparative example is basically the same as that in Example 4, except that a fourth coating layer is deposited using a Si-18wt%B mixed sintering target.

[0148] Comparative Example 6

[0149] The preparation of the antireflective film in this comparative example is basically the same as in Example 7, except that a fourth coating layer is deposited using a 15at%Hf-85at%Si mixed sintering target.

[0150] Comparative Example 7

[0151] The preparation of the antireflective film in this comparative example is basically the same as in Example 7, except that a fourth coating layer is deposited using a 50at%Hf-50at%Si mixed sintering target.

[0152] The antireflective films in each embodiment and comparative example were tested:

[0153] (1) The optical properties of the antireflective coating were tested, as shown in Table 1.

[0154] Table 1 Optical properties of antireflective coatings

[0155]

[0156] (2) Environmental reliability test results are shown in Table 4. The YI value was measured using a colorimeter. The principle is that the instrument emits a standard light source (such as D65 simulated sunlight) to irradiate the sample surface. The spectral information transmitted by the sample is collected through the integrating sphere to obtain accurate spectral data. Various color parameters, including the YI value, are then calculated according to the built-in formula. Thus, ΔYI = YI (after aging) - YI (before aging) can be obtained.

[0157] The following are the reference standards for yellowing ΔYI grading: Grade 0: No discoloration, ΔYI≤1.5; Grade 1: Very slight discoloration, 1.6<ΔYI≤3.0; Grade 2: Slight discoloration, 3.1<ΔYI≤6.0; Grade 3: Obvious discoloration, 6.1<ΔYI≤9.0; Grade 4: Significant discoloration, 9.1<ΔYI≤12.0; Grade 5: Severe discoloration, 12.0<ΔYI.

[0158] Chemical resistance test:

[0159] ① Three parallel samples were prepared for each embodiment and each comparative example to ensure that there were no defects visible to the naked eye (such as scratches or bubbles).

[0160] ② Initial performance record: Before testing, the basic performance of each sample must be measured, including: average visible light transmittance (400-700nm spectrophotometer); film adhesion (cross-cut test, ASTM D3359); surface roughness (AFM or white light interferometer).

[0161] ③ Chemical reagent contact simulation (based on the target scenario, the contact method, time, and temperature are set to simulate daily use conditions), as shown in Table 2:

[0162] Table 2. Chemical Reagent Contact Simulation Methods

[0163]

[0164] ④ After the chemical treatment is completed, immediately rinse the sample surface with deionized water for 30 seconds to remove residual reagents (especially concentrated sulfuric acid / sodium hydroxide, to avoid continuous reaction), and then gently wipe it with a clean, lint-free cloth (to avoid watermarks and ensure that the film surface is not scratched). After air drying for 30 minutes, conduct performance tests.

[0165] Retest the relevant properties of the treated samples, focusing on the following changes: transmittance: compare the average transmittance of 400-700nm before and after treatment to assess the degradation of the film's optical performance; adhesion: perform a cross-cut test (1mm spacing between the cross-cuts, peeling off the tape after application) to observe the percentage of detached area; surface morphology: use AFM or white light interferometer to observe for corrosion, cracks, and detachment (quantify roughness changes); film integrity: use a microscope (50-200x) to check for film peeling.

[0166] The judgment criteria are shown in Table 3:

[0167] Table 3 Criteria for Chemical Resistance Testing

[0168]

[0169] ⑤ The ambient temperature and humidity must be controlled during testing (25±2℃, 50±5%RH) to avoid environmental interference. A blank control group (untreated identical sample) should be set up for each test group to eliminate testing errors.

[0170] Table 4 Environmental Reliability Test Results

[0171]

[0172] (3) Mechanical performance test results are shown in Table 5. The reflectance R of the friction area before and after the test was measured using a spectrophotometer, and the change in reflectance ΔR was calculated. Thus, ΔR = R after wear resistance - R before wear resistance (R value is the reflectance value at a wavelength of 550nm). The smaller ΔR is, the less wear is caused, indicating that the AR film has better wear resistance.

[0173] Table 5 Mechanical Performance Test Results

[0174]

[0175] Combining Tables 1, 4, and 5, we can see the following: Transmittance: With increasing dopant content (Al / B / Hf), transmittance shows a slight upward trend, especially in the Hf-Si system. Color difference (ΔE): Generally increases with increasing doping amount, but is better controlled in the Hf-Si system. Moisture and heat resistance: Pure Si and low-doped samples are prone to fogging or yellowing, while high-Hf-content samples exhibit excellent stability. Salt spray resistance and weather resistance: The Hf-Si system is significantly better than pure Si and Al / B-containing samples; although Al / B doping improves the surface, long-term corrosion resistance is still insufficient. Pencil hardness: The Hf-Si system can reach 3H–4H, far higher than pure Si (HB–H). Abrasion resistance: The Hf-Si system performs excellently, ΔR < 0.15%, while other samples are mostly above 0.20%. Film adhesion: The Hf-Si system reaches 5B (no peeling), while the others are mostly 3–4B or lower. Surface roughness: The Hf-Si system has the lowest Ra value (0.55–0.99 nm), indicating that the film is denser and smoother.

[0176] As can be seen from the above, the antireflective film in this embodiment of the invention has superior optical performance compared to the comparative example. The use of the Hf-Si-O composite enables the antireflective film to achieve a more excellent antireflection effect, with an average reflectivity of 0.54%-0.89%, while also exhibiting excellent chromatic aberration control (ΔE<1.23). The schemes using aluminum-doped silicon dioxide and boron-doped silicon dioxide have optical performance comparable to the comparative example, with boron-doped silicon dioxide offering a greater advantage in cost control.

[0177] In Comparative Example 2, the Al mass fraction was <2%, resulting in deteriorated optical performance: the extremely low Al content led to a SiO2-based film (refractive index ≈1.46), failing to meet the λ / 4 requirement of n≈1.51. The visible light reflectance increased to ≈2.0% (67% higher than the 2% example), losing its low-reflection function; mechanical properties declined: SiO2 has low hardness, and the interfacial bonding between the film and Nb2O5 is weak (low Al content leads to a lack of an interfacial transition layer), making it prone to detachment during the roll-to-roll coating process due to substrate stretching; poor process stability: the low Al content resulted in significant Al atom sputtering loss during sputtering (low sputtering yield), leading to a thickness uniformity deviation of over ±6%, resulting in poor consistency in batch production.

[0178] In Comparative Example 3, the Al mass fraction was >10%, resulting in deviations in optical performance: Excessive Al content increased the proportion of Al2O3 in the film (refractive index ≈1.62), raising the overall refractive index to ≈1.58 (exceeding the upper limit of 1.55), leading to overcompensation of the λ / 4 optical thickness and increasing visible light reflectance to ≈1.8% (an 80% increase compared to the 10% example); excessive internal stress: Al2O3 has a high intrinsic stress of ~150MPa, and the high Al content increased the total internal stress of the film to ≈250MPa, making it prone to transverse cracks during the roll-to-roll coating process, leading to film failure; reduced process controllability: High Al content caused excessive Al atom sputtering during sputtering (sputtering yield fluctuation ±12%), requiring a significant increase in oxygen flow rate (>60sccm) to compensate for oxidation, but this easily caused porosity in the film (refractive index dropping below 1.50), which in turn worsened the reflectivity.

[0179] Therefore, the Al mass fraction of the fourth-layer Si-Al alloy target material needs to be strictly controlled between 2% and 10%. The endpoint values ​​(2% and 10%) can be adjusted by changing the sputtering power and oxygen flow rate to achieve a λ / 4 optical thickness and extremely low reflectivity (<1.2%). Exceeding these ranges can lead to optical performance failure, decreased mechanical strength, or process instability. In actual production, it is recommended to prioritize targets with an Al mass fraction of 5%, which balances refractive index stability, process controllability, and film durability, representing the optimal ratio for the AR outer layer in roll-to-roll coating.

[0180] In Comparative Example 4, the B mass fraction was <5%; optical performance deteriorated: the B content was extremely low, and the film was mainly composed of SiO2 (refractive index ≈1.46), which could not meet the λ / 4 requirement of n≈1.48 - the visible light reflectance increased to ≈2.2% (69% higher than the 5% example), and the low reflectance function was lost; mechanical properties decreased: SiO2 has low hardness, and the interfacial bonding force between the film and Nb2O5 is weak (low B content leads to the absence of the interfacial transition layer), and it is easy to fall off due to substrate stretching during the roll-to-roll coating process; poor process stability: the low B content resulted in large B atom sputtering loss during sputtering (low sputtering yield), which led to the thickness uniformity deviation increasing to more than ±7%, resulting in poor consistency in batch production.

[0181] In Comparative Example 5, the B mass fraction was >15%, resulting in deviations in optical performance: Excessive B content increased the proportion of B2O3 in the film (refractive index ≈1.52), raising the overall refractive index to ≈1.53 (exceeding the upper limit of 1.50), leading to overcompensation of the λ / 4 optical thickness and increasing visible light reflectance to ≈1.9% (a 90% increase compared to the 15% example); excessive internal stress: The intrinsic stress of B2O3 is relatively high (~120MPa), and the high B content increases the total internal stress of the film to ≈200MPa, making longitudinal cracks more likely to occur during roll-to-roll coating, leading to film failure; reduced process controllability: High B content caused excessive B atom sputtering during sputtering (sputtering yield fluctuation ±15%), requiring a significant increase in oxygen flow rate (>50sccm) to compensate for oxidation, but this easily caused porosity in the film (refractive index dropping below 1.47), which in turn worsened the reflectivity.

[0182] Therefore, the boron (B) mass fraction of the fourth-layer Si-B alloy target material needs to be strictly controlled between 5% and 15%. The endpoint values ​​(5% and 15%) can be adjusted by controlling the sputtering power and oxygen flow rate to achieve a λ / 4 optical thickness and extremely low reflectivity (<1.3%). Exceeding these ranges can lead to optical performance failure, decreased mechanical strength, or process instability. In actual production, it is recommended to prioritize targets with a boron mass fraction of 10%, which balances refractive index stability, process controllability, and film durability, representing the optimal ratio for the AR outer layer in roll-to-roll coating.

[0183] In Comparative Example 6, the Hf:Si atomic ratio was <20:80, resulting in deteriorated optical performance: the Hf content was extremely low, and the film was mainly composed of SiO2 (refractive index ≈1.46), failing to meet the λ / 4 requirement of n≈1.65—the visible light reflectance increased to ≈1.5% (50% higher than the 20:80 example), losing its low-reflection function; mechanical properties decreased: SiO2 has low hardness, and the interfacial bonding force between the film and Nb2O5 is weak (low Hf content leads to the absence of an interfacial transition layer), making it prone to detachment due to substrate stretching during roll-to-roll coating; poor process stability: the low Hf content resulted in significant Hf atom sputtering loss during sputtering (low sputtering yield), leading to a thickness uniformity deviation of over ±7%, resulting in poor consistency in batch production.

[0184] In Comparative Example 7, the Hf:Si atomic ratio was >40:60, resulting in deviations in optical performance: Excessive Hf content increased the proportion of HfO2 in the film (refractive index ≈2.0), raising the overall refractive index to ≈1.70 (exceeding the upper limit of 1.67), leading to overcompensation of the λ / 4 optical thickness and increasing visible light reflectivity to ≈1.3% (a 63% increase compared to the 40:60 example); excessive internal stress: The intrinsic stress of HfO2 is relatively high (~180MPa), and the high Hf content increases the total internal stress of the film to ≈220MPa, making it prone to transverse cracks during roll-to-roll coating, leading to film failure; reduced process controllability: High Hf content caused excessive sputtering of Hf atoms during sputtering (sputtering yield fluctuation ±16%), requiring a significant increase in oxygen flow (>70sccm) to compensate for oxidation, but this easily caused porosity in the film (refractive index dropping below 1.63), which in turn worsened the reflectivity.

[0185] Therefore, the Hf:Si atomic ratio of the fourth-layer Hf-Si alloy target needs to be strictly controlled within the extreme values ​​of 20:80-40:60 (20:80, 40:60). This can be achieved by adjusting the sputtering power and oxygen flow rate, resulting in a λ / 4 optical thickness and extremely low reflectivity (<1.0%). Exceeding this range will lead to optical performance failure, decreased mechanical strength, or process instability. In actual production, it is recommended to prioritize a target with an Hf:Si atomic ratio of 30:70, which balances refractive index stability, process controllability, and film durability, making it the optimal ratio for the AR outer layer in roll-to-roll coating.

[0186] As shown in Table 4, the examples using the Hf-Si-O composite exhibit the best environmental reliability with almost no performance degradation, particularly in chemical resistance and weather resistance. The schemes using aluminum-doped silica and boron-doped silica achieve a good balance between cost control and performance improvement, with significantly better environmental reliability than the comparative examples. All modified schemes showed superior resistance to damp heat, salt spray, and weathering compared to the comparative examples, with the boron / aluminum doped and Hf-Si-O composite films demonstrating a clear advantage in long-term reliability.

[0187] As shown in Table 5, the examples using the Hf-Si-O composite exhibited the best mechanical properties, with a pencil hardness in the range of 3H-5H and the lowest surface roughness. The Hf-Si-O composite achieved excellent mechanical durability through its high hardness, and the film adhesion reached a perfect 5B standard. The schemes using aluminum-doped silicon dioxide and boron-doped silicon dioxide also significantly outperformed the comparative examples in terms of mechanical properties, especially in terms of wear resistance and surface hardness. All modification schemes achieved superior wear resistance, hardness, and adhesion compared to the comparative examples by optimizing the film structure and material selection.

[0188] In summary, the technical solution of this invention can be summarized as follows:

[0189] 1. Overall Performance Ranking (from best to worst): Hf-Si-O composite scheme: Best performance in all aspects, especially showing an excellent balance in optical performance, environmental reliability, and mechanical properties, suitable for high-end applications. Aluminum-doped silicon dioxide and boron-doped silicon dioxide schemes: Best cost-effectiveness, significant improvement in overall performance, suitable for mid-to-high-end applications. Pure Si scheme (Comparative Example 1): Reliable basic performance, lowest cost, suitable for cost-sensitive applications with less stringent performance requirements.

[0190] 2. Application Scenarios: High-end optical devices (such as camera lenses and precision optical instruments): Hf-Si-O composite solutions can be used, whose extremely low reflectivity, excellent chromatic aberration control, and superior environmental stability ensure the highest optical performance and long-term reliability; Consumer electronics and automotive electronics (cost-sensitive high-end applications): Aluminum-doped silicon dioxide and boron-doped silicon dioxide solutions can be used to achieve significant performance improvements while controlling costs; Basic optical applications (cost priority): Pure Si (Comparative Example 1) remains a reliable choice, especially in scenarios where optical performance requirements are not stringent.

[0191] 3. Process Feasibility: Pure Si (Comparative Example 1): The process is the most mature and has the lowest cost, making it suitable for large-scale mass production; Aluminum-doped silicon dioxide and boron-doped silicon dioxide solutions: The process requires less adjustment and can be implemented with existing equipment, making them suitable for rapid production; Hf-Si-O composite solution: The process is more complex and requires precise control of oxygen flow rate and sputtering power, making it suitable for medium-batch production.

[0192] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0193] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An antireflective film, characterized in that, The antireflective film comprises a substrate layer, a first coating layer, a second coating layer, a third coating layer, and a fourth coating layer stacked sequentially. The fourth coating is made of hafnium-silicon composite oxide; the molar ratio of hafnium atoms to silicon atoms in the hafnium-silicon composite oxide is 1:4 to 1:1.

5. The refractive index of the first coating layer is greater than the refractive index of the second coating layer and the refractive index of the fourth coating layer; the refractive index of the third coating layer is greater than the refractive index of the second coating layer and the refractive index of the fourth coating layer; The first coating has a refractive index of 2.0-2.5; the second coating has a refractive index of 1.38-1.46; the third coating has a refractive index of 2.0-2.5; and the fourth coating has a refractive index of 1.46-1.

67.

2. The antireflective film according to claim 1, characterized in that, The material of the first coating is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide; and / or, the material of the second coating is any one or more of silicon dioxide, magnesium fluoride, and aluminum oxide; and / or, the material of the third coating is any one or more of niobium pentoxide, zirconium dioxide, silicon nitride, and titanium dioxide.

3. The antireflective film according to claim 1, characterized in that, The thickness of the first coating layer is 10nm-20nm; and / or, the thickness of the second coating layer is 29nm-39nm; and / or, the thickness of the third coating layer is 115nm-125nm; and / or, the thickness of the fourth coating layer is 80nm-100nm.

4. The antireflective film according to claim 1, characterized in that, An underlayer is provided between the substrate layer and the first coating layer. The material of the underlayer is any one or more of silicon dioxide, aluminum oxide, hafnium dioxide, elemental titanium, and elemental silicon. The thickness of the underlayer is 1nm-5nm.

5. The antireflective film according to claim 1, characterized in that, Both sides of the substrate layer are provided with acrylic resin curing layers, and the thickness of the acrylic resin curing layers is 210nm-230nm.

6. The antireflective film according to claim 1, characterized in that, The material of the substrate layer is any one of PET, PI, PEN, COP, PMMA, TAC, LCP, and SRF; and / or the thickness of the substrate layer is 7.5μm-250μm.

7. The antireflective film according to claim 1, characterized in that, The fourth coating layer is further provided with an AF layer, the thickness of which is 5nm-15nm.

8. A method for preparing the antireflective film according to claim 1, characterized in that, The method for preparing the antireflective film includes the following steps: taking a substrate, and sequentially depositing a first coating layer, a second coating layer, a third coating layer and a fourth coating layer on the substrate to obtain an antireflective film.

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