A super-hydrophobic surface design using a spherical curved cone to achieve anti-reflection and anti-transmittance

Abstract

The present invention discloses a method for designing a super-hydrophobic surface by using a spherical head arc-surface frustum to achieve anti-reflection and anti-transmittance. The microstructure of the surface is composed of micron-scale spherical head arc-surface frustums with equal spacing. Due to the characteristics of the arc surface such as light capture and multiple reflection of light, the designed spherical head arc-surface frustum can play a role in reducing reflection and increasing transmittance of incident sunlight, so that the solar cell glass cover has both super-hydrophobic function and high light transmittance. Based on the micro-morphological structural characteristics of the spherical head arc-surface frustum and combined with the Cassie-Baxter infiltration model, a mathematical equation is derived to quantitatively characterize the numerical relationship between the micro-morphological structural characteristics of the spherical head arc-surface frustum and the super-hydrophobic function, namely the water droplet contact angle. Based on the numerical relationship, the design characteristics of the micro-morphological structure are introduced to solve the water droplet contact angle, and the corresponding micro-morphological structural characteristic parameters when the contact angle is greater than 150° are clarified. The design method of the present invention can provide a design approach for solar cell glass cover plates that have both superhydrophobicity and high transmittance. It can achieve automatic removal of dust deposited on the surface of the solar cell glass cover plate and reduce reflection and increase transmittance of incident sunlight, thereby allowing the solar cell to maintain high photoelectric conversion efficiency for a long time.

Description

Technical Field

[0001] The present invention belongs to the field of super-hydrophobic structure design on the surface of solar cell glass cover plates, and in particular relates to a super-hydrophobic surface design method for achieving anti-reflection and anti-transmittance by a spherical head arc cone. The provided spherical head arc cone micro-morphology structure can enable the solar cell glass cover plate to have both super-hydrophobic function and high transmittance, realize automatic removal of dust deposited on the surface of the solar cell glass cover plate and anti-reflection and anti-transmittance of incident sunlight, thereby enabling the solar cell to maintain high photoelectric conversion efficiency for a long time. Background Art

[0002] my country's photovoltaic industry is experiencing rapid growth. Dust accumulation in service environments significantly reduces light transmittance on glass cover panels, impacting photovoltaic conversion efficiency. Traditional cleaning methods for these deposited dusts are labor-intensive, energy-intensive, and prone to damage. Therefore, efforts are underway to impart a superhydrophobic property to glass cover panels, enabling automated removal of deposited dust and maintaining high photovoltaic conversion efficiency for solar cells. However, current challenges include complex superhydrophobic microstructure preparation and low light transmittance.

[0003] A super-hydrophobic surface refers to a material surface with a water droplet contact angle greater than 150° and a rolling angle less than 10°. It has important application value in the fields of self-cleaning, corrosion prevention, and frost suppression. The contact angle of a droplet on a solid surface is an important indicator for measuring wetting properties. The contact angle is the result of the surface tension balance between the three interfaces of solid, liquid, and gas. When the tension is balanced, the total energy of the system tends to be the lowest, and the droplet on the solid surface is in a stable state. Wenzel believed that when a droplet contacts a solid surface, it can completely immerse the microstructure of the rough surface, and proposed the Wenzel equation cos i w =rcos i ,in i w is the droplet contact angle, r is the roughness factor, i is the intrinsic contact angle of a droplet on a smooth surface. However, the droplet cannot completely wet the microstructure of a rough surface, so the Cassie-Baxter wetting model was proposed, which believes that the contact surface is composed of three parts: the droplet, the microstructure of the solid surface, and the air trapped inside the microstructure. Based on this, the Cassie-Baxter equation cos i T = f sl ( f r cos i c +1)-1, where i T is the contact angle, ic is the intrinsic contact angle, f s1 is the ratio of the actual wetted solid area of ​​the droplet to the apparent geometric contact area. f r The roughness coefficient represents the degree of surface roughness. The superhydrophobic nature of a material surface is primarily due to the microtopography forming a large air-liquid interface that maintains the Cassie-Baxter wetting state, resulting in a large contact angle on the surface. Microtopography is a key factor influencing the high contact angle exhibited by water droplets on a material surface. Therefore, superhydrophobic surface preparation primarily involves modifying low-surface-energy materials onto rough surfaces with microtopography, or constructing microtopography on the surface of low-surface-energy materials.

[0004] In the photovoltaic power generation sector, high light transmittance is crucial for glass cover panels. When sunlight strikes the surface of a glass cover panel, a certain percentage of the light is reflected and absorbed, while the remaining light is able to penetrate the object and continue to propagate, resulting in light transmittance. The sum of reflectivity, transmittance, and absorptivity is 1, and a decrease in reflectivity means an increase in transmittance. The design of a spherical head with a curved frustum microtopography reduces the angle of incidence and reflects sunlight multiple times, thereby reducing reflection and increasing transmittance.

[0005] Based on the principle of superhydrophobic surface design, the inventor of this patent application has carried out research on superhydrophobic surface design with the support of projects such as the Hebei Provincial Natural Science Foundation General Project (Research on the Superhydrophobic Mechanism and Bionic Preparation Technology of Micro-Nano Composite Structures in the Slip Zone of Pitcher Plant, E2019208306) and the Central Guidance of Local Science and Technology Development Fund Project (Research on Femtosecond Laser Preparation Technology of Superhydrophobic Micro-Nano Composite Structures on Titanium Alloy Surfaces, 226Z1804G). Using the micro-morphological structure of the slip zone of pitcher plant that can exhibit superhydrophobic properties as a bionic prototype, a superhydrophobic surface was designed and prepared using 3D printing technology and high-voltage electrostatic adsorption technology. The test results showed that the water drop contact angle of the prepared superhydrophobic surface was 152.6°, indicating that it has good superhydrophobic function (authorized invention patent, patent number ZL 202010458218.7; academic paper, Bioinspired, Biomimetic and Nanobiomaterials, 2022, 11(1): 1–7). Therefore, the applicant has the basic conditions for super-hydrophobic surface design.

[0006] Invention Patent 202011525996.X discloses a method for designing and preparing a super-hydrophobic surface. The surface is etched away through cutting to create a microscopic surface topography of pits and bumps. The microscopic topography and surface texture combine to form a multi-level micro-nanostructure, resulting in a super-hydrophobic surface with excellent mechanical wear resistance. This structure boasts high production efficiency, low cost, cleanliness, and strong adaptability. However, its micro-topography lacks both high light transmittance and limited application in this design area, particularly for solar cell glass cover surfaces. Invention Patent 202011352578.5 discloses a method for designing a biomimetic gradient super-hydrophobic structure based on the Marangoni effect. Based on the typical hydrophobic structure of biological surfaces, by constructing a composite array structure and installing nano-heating plates on a single structure, structural gradients and temperature gradients are simultaneously introduced on the solid surface. Under the Marangoni effect caused by the coupling of structural gradients and temperature gradients, the droplets move in a directional manner and roll down automatically, making the structural surface super-hydrophobic and self-cleaning. However, its micro-morphology structure also cannot have high transmittance, and its application in the surface of solar cell glass cover in this design field is limited.

[0007] In summary, in the field of solar cells, although the existing super-hydrophobic surfaces can achieve good super-hydrophobic properties through the designed micro-morphology structure, the high light transmittance of the micro-morphology structure is not taken into account, and the effect of reducing reflection and increasing transmittance of sunlight cannot be achieved. Therefore, the present invention proposes a super-hydrophobic surface design method that achieves anti-reflection and anti-transmittance by a spherical head arc-surface frustum, and the designed spherical head arc-surface frustum micro-morphology structure has both super-hydrophobic function and high light transmittance; based on the micro-morphology structural characteristics of the spherical head arc-surface frustum, combined with the Cassie-Baxter infiltration model, a mathematical equation is derived to obtain the characteristic parameters of the micro-morphology structural characteristics of the spherical head arc-surface frustum, ensuring that the designed surface has both super-hydrophobic function and high light transmittance. This design can realize the automatic removal of dust deposited on the surface of the solar glass cover and the anti-reflection and anti-transmittance of incident sunlight, so that the solar cell can maintain a high photoelectric conversion efficiency for a long time. Summary of the Invention

[0008] The present invention provides a method for designing a super-hydrophobic surface that achieves anti-reflection and anti-transmittance by a spherical head arc-shaped cone, wherein the super-hydrophobic surface is a spherical head arc-shaped cone micro-morphology structure; based on the micro-morphology structural characteristics of the spherical head arc-shaped cone, a mathematical equation is derived in combination with the Cassie-Baxter infiltration model to accurately calculate the three-dimensional structural parameters of the spherical head arc-shaped cone, so that the designed solar cell glass cover has both super-hydrophobic function and high transmittance. This method is to directly design a micro-morphology structure on the surface, so that it has both super-hydrophobic function and high transmittance. To achieve the above functions, the technical solution adopted by the present invention is:

[0009] A method for designing a super-hydrophobic surface for achieving anti-reflection and anti-transmission by using a spherical end arc cone is characterized by comprising the following steps:

[0010] Step 1, designing the microstructure of the super-hydrophobic surface, that is, a spherical head arc-shaped cone micro-morphology structure composed of a spherical head and an arc circle; the radius of the spherical head is r ; The radius of the arc surface structure of the arc cone is R ;

[0011] Step 2: Based on the Cassie-Baxter wetting model, a mathematical equation is derived to establish a numerical relationship between the micro-morphological structural characteristics of the spherical head arc-shaped frustum and the superhydrophobic function, i.e., the contact angle of the water droplet;

[0012] Step 3: Calculate the structural characteristic parameters of the spherical head arc-surface frustum microstructure corresponding to the water drop contact angle being greater than 150° based on the established numerical relationship.

[0013] Based on the above technical solution, the method for designing a super-hydrophobic surface by using a spherical head arc cone to achieve anti-reflection and anti-transmittance is described. Its microstructure is composed of micron-level spherical head arc cones distributed at equal intervals. The spherical head arc cone is composed of a spherical head and an arc cone. The interaction between the spherical head arc cone plays the role of anti-reflection and anti-transmittance of sunlight. In terms of characteristic parameters, the radius of the spherical head is r Designed to be 10~15 μm, the radius of the arc surface structure of the arc cone R Designed to be 45-55 μm. The structures are evenly spaced and possess characteristic micrometer-scale structural parameters. When water droplets infiltrate the microstructures, the gaps between the spherical curved cones trap air, forming a liquid-air-solid interface and exhibiting superhydrophobic properties. When incident sunlight strikes the microstructures, the curved surface of the cones reduces the angle of incidence and reflects the sunlight multiple times, thereby reducing reflection and increasing transmittance.

[0014] On the basis of the above technical solution, the super-hydrophobic surface design method using a spherical head arc cone to achieve anti-reflection and anti-transmittance is as follows: Where: i T and i c Represent the theoretical contact angle and the intrinsic contact angle, respectively. The intrinsic contact angle of a water drop on a smooth surface i c 100°~110°; r、R are the arc structure radius of the spherical head and arc frustum respectively; l The wettability coefficient is the degree of wetting of the spherical head arc cone by the water drop. When the water drop floats on the top of the spherical head, l =0, when the water droplet completely soaks the spherical head arc cone, λ=1, so 0≤λ≤1.

[0015] On the basis of the above technical solution, the micro-morphological structural characteristic parameters of the spherical head arc cone are brought into the numerical relationship to control l The theoretical value of the water droplet contact angle is calculated, and whether the designed super-hydrophobic surface has super-hydrophobic properties is determined based on whether the theoretical value of the contact angle is greater than 150°.

[0016] The beneficial effects of the above technical solution are: the present invention provides a method for designing a super-hydrophobic surface that achieves anti-reflection and anti-transmittance by a spherical head arc-surface cone, and the microstructure is composed of a spherical head arc-surface cone; based on the micro-morphological structural characteristics of the spherical head arc-surface cone, combined with the Cassie-Baxter wetting model, a mathematical equation is derived to establish a numerical relationship between the micro-morphological structural characteristics of the spherical head arc-surface cone and the super-hydrophobic function, i.e., the contact angle of the water droplet, and the controllable design of the super-hydrophobic function can be achieved by regulating the characteristic parameters; the arc surface structure of the arc-surface cone can also play a role in reducing reflection and increasing transmittance of sunlight, so the designed super-hydrophobic surface also has the effect of reducing reflection and increasing transmittance of sunlight. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the overall structure of the present invention;

[0018] Figure 2 Schematic diagram of the spherical head arc cone of the present invention;

[0019] Figure 3 A schematic cross-sectional view of the spherical head arc-surface frustum structure of the present invention;

[0020] Figure 4 Schematic diagram of light reflection of the present invention;

[0021] Figure 5 Design flow chart of the present invention.

[0022] In the figure: 1. Spherical head arc-surface frustum; 1-1. Spherical head; 1-2. Arc-surface frustum; 1-2-1. Arc-surface structure of arc-surface frustum; 2. Bottom surface; 3. Base. DETAILED DESCRIPTION

[0023] The following examples are used to illustrate the present invention, but are by no means intended to limit the scope of the present invention. The working process of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] The present invention provides a method for designing a super-hydrophobic surface that achieves anti-reflection and anti-transmittance by using a spherical head cambered cone. The design process comprises the following steps: designing a super-hydrophobic surface microstructure into micron-scale spherical head cambered cones with equal spacing; deriving a mathematical equation based on the Cassie-Baxter wetting model to establish a numerical relationship between the micro-morphological structural characteristics of the spherical head cambered cone and the super-hydrophobic function, namely, the water droplet contact angle; and calculating, based on the numerical relationship, the micro-morphological structural characteristic parameters of the spherical head cambered cone corresponding to a water droplet contact angle greater than 150°.

[0025] like Figure 1 、 Figure 2 As shown, the present invention is a method for designing a super-hydrophobic surface with anti-reflection and anti-transmittance by a spherical head arc cone, which is characterized in that the spherical head arc cone 1 and the base 3 are an integrated structure, the spherical head arc cone 1 is evenly spaced, and the spherical head arc cone 1 is composed of a spherical head 1-1 and an arc cone 1-2. The radius of the spherical head 1-1 is r =10~15 μm, in this embodiment r =14 μm; the radius of the arc surface structure 1-2-1 of the arc surface cone R =45~55 μm, in this embodiment R =45 μm. The value is obtained by calculation.

[0026] Based on the Cassie-Baxter wetting model, a mathematical equation is derived to establish the numerical relationship between microstructural characteristic parameters and the superhydrophobic function, namely the contact angle of a water droplet. The Cassie-Baxter wetting model assumes that when a liquid droplet infiltrates a solid surface, it can retain air in the solid surface microstructure. Therefore, the contact surface is composed of three parts: the liquid droplet, the air, and the solid surface microstructure. Based on this, the Cassie-Baxter equation is proposed: (1)

[0027] Where, i T is the contact angle, i c is the intrinsic contact angle, f s1 is the ratio of the actual wetted solid area of ​​the droplet to the apparent geometric contact area. f r Indicates the roughness coefficient, that is, the non-smoothness of the surface. Figure 1 、 Figure 2 As shown in the figure, the designed super hydrophobic surface is composed of spherical head arc cones 1 with equal spacing. The spherical head arc cone 1 is composed of spherical head 1-1 and arc cone 1-2. The projected area of ​​the unit microstructure is S P It can be calculated by formula (2):

[0028] (2)

[0029] The actual surface area generated by the unit microstructure S S It consists of three parts: the ball head 1-1, the arc surface structure 1-2-1 of the arc cone, and the bottom surface 2, and is calculated using the following formula:

[0030] (3)

[0031] Where, r Indicates the 1-1 radius of the ball head; R The radius of the cambered cone is 1-2-1. D Indicates the spacing of the spherical head arc cone, that is, the sum of the diameter of the spherical head 1-1 and the diameter of the arc structure 1-2-1 of the arc cone. D= 2( r+R ).

[0032] According to this roughness coefficient f r It can be expressed as,

[0033] (4)

[0034] When water droplets infiltrate the designed spherical head arc cone micro-morphology structure, they will produce different degrees of infiltration on the spherical head arc cone, so the infiltration coefficient is introduced l , which represents the degree of wetting of the spherical head arc cone by the water droplet; when the water droplet only infiltrates the top of the spherical head, λ=0, and when the water droplet completely infiltrates the spherical head arc cone, λ=1, so 0≤λ≤1; if the designed superhydrophobic surface has a better superhydrophobic function, the water droplet contact angle must be greater than 150°, which means that the water droplet has a smaller degree of wetting on the spherical head arc cone, that is, l Should be a smaller value.

[0035] At this time, the water droplet infiltrates the surface of the ball head 1-1 and the arc structure 1-2-1 of part of the arc cone, so the ratio of the actual area of ​​the ball head arc cone infiltrated by the water droplet to the apparent geometric contact area is f s1 It can be obtained by formula (5):

[0036] (5)

[0037] Where: f s1 It represents the ratio of the actual solid area wetted by the droplet to the apparent geometric contact area; H Indicates the height of the cambered cone of the ball head, i.e. the radius of the ball head 1-1 r and the 1-2-1 radius of the arc structure of the arc cone R of and; D Indicates the distance between the arc cones of the ball head; r Indicates the 1-1 radius of the ball head; R The radius of the cambered cone is 1-2-1. l Represents the wetting coefficient.

[0038] Substituting formula (4) and formula (5) into formula (1), the numerical relationship between the designed super-hydrophobic surface microstructure characteristic parameters and the super-hydrophobic function, i.e., the water droplet contact angle, can be obtained as follows:

[0039] (6)

[0040] Where: i T and i c The contact angle of a water droplet on a smooth surface is generally 100° to 110°. i c =103°.

[0041] In the designed super-hydrophobic surface, the microstructure is composed of equally spaced micron-sized spherical heads with arc-shaped cones. In this embodiment, the characteristic parameters are set as follows: 1-1 radius of the spherical head r= 14 μm, 1-2-1 radius of the arc-shaped cone R =45 μm. The wettability coefficient of water droplet on the spherical head arc cone is l =0.35. Substitute the above parameters into formula (6) to calculate the contact angle of the designed superhydrophobic surface i T =151.5°, indicating superhydrophobicity.

[0042] The present invention provides a method for designing a super-hydrophobic surface that realizes anti-reflection and anti-transmittance by using a spherical head arc cone. According to formula (6), when determining i c 、 l Under the premise of equal coefficient, by adjusting the radius of the ball head 1-1 r , the arc structure of the arc cone 1-2-1 radius R , that is, to achieve controllable design of superhydrophobic function.

[0043] like Figure 3 、 Figure 4 As shown, a super-hydrophobic surface design that achieves anti-reflection and anti-transmittance by a spherical head arc cone. When sunlight shines on the arc surface structure 1-2-1 of the arc surface cone, the arc surface structure can reduce the incident angle and reflect the sunlight multiple times, thereby playing the role of anti-reflection and anti-transmittance for the sunlight.

[0044] like Figure 5As shown, a design process of a super-hydrophobic surface design method for realizing anti-reflection and anti-transmission by a ball head cambered cone, first designing a super-hydrophobic surface microstructure model, i.e. designing a ball head 1-1 and a cambered cone 1-2; deriving a mathematical equation in combination with the Cassie-Baxter wetting model, establishing a numerical relationship between the micro-morphological structural characteristic parameters of the ball head cambered cone and the super-hydrophobic function, i.e. the contact angle of a water droplet; preset structural characteristic parameters according to the mathematical equation, calculating the contact angle and determining whether it is greater than 150 °; optimizing the design of the super-hydrophobic surface by regulating and controlling the structural characteristic parameters, until the contact angle is greater than 150 °, realizing the controllable design of the super-hydrophobic surface. A super-hydrophobic surface design method for realizing anti-reflection and anti-transmission by a ball head cambered cone provided by the present invention, can obtain a solar cell glass cover with both super-hydrophobic function and high transmittance, realize the automatic removal of dust deposited on the surface of the solar cell glass cover and the anti-reflection and anti-transmission of incident sunlight, thereby making the solar cell maintain a high photoelectric conversion efficiency for a long time.

[0045] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are in no way intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention are intended to be encompassed by the claims of the present invention.

Claims

1. A method for designing a super-hydrophobic surface with anti-reflection and anti-transmittance by using a spherical end arc cone, characterized in that The design steps include: Step 1, designing a microstructure of a super-hydrophobic surface, namely, a spherical head and a cambered cone microstructure composed of a spherical head and a cambered cone; Step 2: Based on the Cassie-Baxter wetting model, a mathematical equation is derived to establish the numerical relationship between the micro-morphological structural characteristics of the spherical head arc cone and the superhydrophobic function, that is, the contact angle of the water droplet, namely: ， Where: θ T and θ c Represent the theoretical contact angle and the intrinsic contact angle, respectively. The intrinsic contact angle of a water drop on a smooth surface θ c 100°~110°; r、R are the arc structure radius of the spherical head and arc frustum respectively; λ The wetting coefficient is the degree of wetting of the spherical head arc cone by the water drop. When the water drop floats on the top of the spherical head, λ =0, when the water droplet completely soaks the spherical head arc cone λ =1; Step 3: Calculate the structural characteristic parameters of the spherical head arc-surface frustum microstructure corresponding to the water drop contact angle being greater than 150° based on the established numerical relationship.

2. The method for designing a super-hydrophobic surface with anti-reflection and anti-transmission by a spherical end arc cone according to claim 1, characterized in that The spherical head arc cone and the base are an integrated structure. The spherical head arc cones are distributed at equal intervals. The spherical head arc cone is composed of a spherical head and an arc cone. The spherical head is a hemisphere, and the curvature of the arc cone is a quarter of a circle. A concave structure is formed between adjacent arc cones, which plays the role of capturing light and reflecting light multiple times.

3. The method for designing a super-hydrophobic surface for achieving anti-reflection and anti-transmission by using a spherical end arc cone according to claim 1, characterized in that The radius r of the spherical head is designed to be 10-15 μm, and the radius R of the arc surface structure of the arc cone is designed to be 45-55 μm; the spherical head and the arc surface cone both have micron-level structural characteristic parameters, and the formed spherical head arc surface cone micro-morphology structure can retain air, and when water droplets infiltrate, a liquid-gas-solid contact interface can be formed, thereby presenting a superhydrophobic function; when incident sunlight illuminates the arc surface structure of the spherical head arc surface cone, the arc surface structure can reduce the incident angle and reflect the sunlight multiple times, thereby playing the role of reducing reflection and increasing transmittance of the sunlight.

4. The method for designing a super-hydrophobic surface for achieving anti-reflection and anti-transmission by using a spherical end arc cone according to claim 1, characterized in that By bringing the design features of microstructures such as the spherical head and the curved frustum into the numerical relationship, the theoretical value of the water droplet contact angle is calculated. The super-hydrophobic function is judged based on whether the contact angle is greater than 150°, thereby realizing the controllable design of the super-hydrophobic surface. The curved surface structure of the curved frustum can also play a role in reducing reflection and increasing transmittance of incident sunlight. Therefore, the super-hydrophobic surface designed by the spherical head curved frustum to achieve anti-reflection and anti-transmittance can enable the solar cell glass cover to have both super-hydrophobic function and high transmittance.

Images