CN115763581A

CN115763581A - Solar cell front plate and preparation method thereof

Info

Publication number: CN115763581A
Application number: CN202211491249.8A
Authority: CN
Inventors: 吴培服; 吴迪; 孙化斌; 臧辉; 张迪
Original assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Current assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Priority date: 2022-11-25
Filing date: 2022-11-25
Publication date: 2023-03-07

Abstract

A solar cell front plate and a preparation method thereof comprise a weather-resistant film on the outer side and a supporting base film on the inner side, wherein the weather-resistant film and the supporting base film are bonded into a whole through a bonding layer; the supporting base film comprises a base material layer, two side surfaces of the base material layer are respectively provided with an online coating layer, and the outer side of the online coating layer is sputtered to form a barrier layer; the substrate layer includes inner layer membrane and outer layer membrane, and the cross-section that is formed with a plurality of equidistant parallel arrangement on the inner layer membrane is isosceles trapezoid's inner layer prism structure, and the inner layer prism structure outside is formed with one deck refraction layer, and it has outer prism structure to fill in the sunken cavity between outer layer membrane and the refraction layer, and outer layer membrane is connected as an organic wholely through outer prism structure with the refraction layer. The utility model provides a weather resistant membrane in the front bezel outside has effects such as reinforcing, resistant time, and inboard support base film provides support protect function and stronger separation nature, and the substrate layer that supports the base film is through setting up the refraction layer between inlayer prism structure and outer prism structure, has improved the utilization ratio of sunshine.

Description

Solar cell front plate and preparation method thereof

Technical Field

The application belongs to the technical field of solar batteries, and particularly relates to a solar battery front plate and a preparation method thereof.

Background

A solar cell photovoltaic module with a typical structure is composed of a front plate, a solar cell piece, an encapsulating material and a back plate. The solar cell photovoltaic module is generally applied to outdoor environment and is subjected to tests such as wind, sunlight, rain, dust, abrasion and the like, so that the performance requirement on the front plate, namely the light receiving surface, is high, and the front plate, namely the solar cell photovoltaic module needs to have high light transmittance, water resistance, UV resistance and certain mechanical strength.

CN 115179631A is an encapsulating material and a photovoltaic module. The packaging material comprises a fluorine-containing plastic film and a water-blocking film, wherein the fluorine-containing plastic film and the water-blocking film are connected through a weather-resistant pressure-sensitive adhesive layer, and a wear-resistant water-blocking layer is arranged on the surface of one side of the fluorine-containing plastic film, which is far away from the water-blocking film; wherein the fluorine-containing plastic film is subjected to low-pressure low-temperature plasma surface treatment; the raw materials of the weather-resistant pressure-sensitive adhesive layer comprise acrylate pressure-sensitive adhesive, liquid ultraviolet absorbent combination and solid ultraviolet absorbent combination. The fluoroplastic film adopted by the front plate packaging material in the prior art has the characteristics of high water permeability, poor wear resistance, low surface energy, easiness in delaminating, easiness in dust adsorption and the like, and risks such as reduction of power generation power of a component, delaminating and the like can occur after the front plate packaging material is used outdoors for a period of time. In the prior art, in order to avoid the problems of water absorption and wear resistance of the fluorine-containing plastic film, a water-blocking film is additionally arranged, but the weather resistance of the water-blocking film is weaker than that of the fluorine-containing plastic film, and the water-blocking film becomes brittle and cracks before the fluorine-containing plastic film, so that the defects of the fluorine-containing plastic film cannot be fundamentally overcome.

Disclosure of Invention

The present application addresses the problem of providing a solar cell front sheet and a method for manufacturing the same, so as to reduce or avoid the aforementioned problems.

In order to solve the technical problem, the application provides a solar cell front plate which comprises a weather-resistant film on the outer side and a supporting base film on the inner side, wherein the weather-resistant film and the supporting base film are bonded into a whole through a bonding layer; the supporting base film comprises a base material layer, two side surfaces of the base material layer are respectively provided with an online coating layer, and the outer side of the online coating layer is sputtered to form a barrier layer; the substrate layer includes towards the inner film of solar wafer one side and keeps away from the outer membrane of solar wafer one side, the cross-section that is formed with a plurality of equidistant parallel arrangement on the inner film is isosceles trapezoid's inner prismatic structure, and the inner prismatic structure outside is formed with one deck refraction layer through vacuum sputtering, has filled outer prismatic structure in the sunken cavity between outer membrane and the refraction layer, and outer membrane is connected as an organic wholely through outer prismatic structure with the refraction layer.

Preferably, the refractive index of each of the inner and outer prism structures is less than the refractive index of the refractive layer.

Preferably, the refractive layer is made of Nb with the refractive index of 2.01-2.48 ₂ O ₅ And (4) forming.

Preferably, the barrier layer is composed of silicon dioxide; the thickness was 200nm.

Preferably, the online coating layer is formed by uniformly mixing acrylic resin, silica nanoparticles with the particle size of 5-10nm, 1,4-dioxane, polyethylene oxide and ethylene-vinyl acetate copolymer into a primer solution and then performing online coating and curing; the mass ratio of each component of the online coating layer (22) is respectively that: silica nanoparticles: 1,4-dioxane: polyethylene oxide: the ethylene-vinyl acetate copolymer is 100: (10-15): (20 to 30): (10-15): (5-10).

Preferably, the length of the lower base of the isosceles trapezoid of the cross section of the inner layer prism structure is 20 to 30 μm, the lower base angle is 30 to 60 degrees, the height is 25 to 50 μm, and the minimum gap between adjacent inner layer prism structures is 50 to 100 μm.

Preferably, the inner film and the outer film are made of PET having a visible light transmittance of more than 85% at the same thickness.

In addition, the application also provides a preparation method of the solar cell front plate, which comprises a preparation step of a supporting base film and a bonding step of the supporting base film and a weather-resistant film; wherein the preparation of the support base film comprises: the preparation method comprises the following steps of taking PET slices as raw materials for preparing the PET film, obtaining a single-layer thick sheet through melt extrusion, longitudinally stretching the raw materials into a film after preheating, coating a mixture of components forming an online coating layer on one side of the film on line through a coating machine after longitudinally stretching, transversely stretching, shaping, cooling and rolling to form the online coating layer on the surface of the film, and sputtering the outer side of the online coating layer to form a barrier layer formed by silicon dioxide, so that an inner layer film and an outer layer film with the online coating layer and the barrier layer are obtained for later use; curing the side of the inner layer film, on which the on-line coating layer and the barrier layer are not formed, to form a plurality of inner layer prism structures with isosceles trapezoid cross sections, which are arranged in parallel at equal intervals; forming a refraction layer on the inner layer prism structure through vacuum sputtering; filling ultraviolet curing acrylic resin in the concave cavity on the outer side of the refraction layer, and attaching an outer layer film on one side far away from the solar cell piece to the outer sides of the refraction layer and the filled ultraviolet curing acrylic resin; wherein the side of the outer layer film, on which the on-line coating layer and the barrier layer are not formed, faces the refraction layer for bonding; and irradiating ultraviolet light through one side of the barrier layer of the outer layer film to enable the filled ultraviolet light curing acrylic resin to be cured to form an outer layer prism structure, and connecting the outer layer film and the refraction layer into a whole through the outer layer prism structure while curing the outer layer prism structure, so that the base film is prepared.

Preferably, the bonding step of the support base film and the weather-resistant film comprises: and (3) bonding one side of the outer layer membrane of the support base membrane with a weather-resistant membrane into a whole through a bonding layer, wherein the weather-resistant membrane is formed by a PVDF membrane taking PVDF as a main body.

Preferably, the weatherable film has a thickness of 20 to 30 μm.

The utility model provides a resistant time membrane that waits in the front bezel outside has effects such as reinforcing, resistant time, and inboard support base film provides support protect function and stronger separation nature, and the substrate layer that supports the base film is through setting up the refraction layer between inlayer prism structure and outer prism structure, has improved the utilization ratio of sunshine.

Drawings

The drawings are only for purposes of illustrating and explaining the present application and are not to be construed as limiting the scope of the present application.

Fig. 1 shows a schematic cross-sectional view of a solar cell front sheet according to an embodiment of the present application.

Fig. 2 shows a schematic diagram of a specific structure of a support base film that can be used for a front sheet of a solar cell according to an embodiment of the present application.

Fig. 3 shows a schematic view of a supporting base film that can be used for a solar cell front sheet according to another embodiment of the present application.

Fig. 4 shows an exploded perspective view of a substrate layer of a support base film that can be used in a solar cell front sheet according to yet another embodiment of the present application.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present application, embodiments of the present application will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

As shown in fig. 1, the present application proposes a solar cell front panel, which includes an outer weatherable film 100 and an inner support base film 200, wherein the weatherable film 100 and the support base film 200 are integrally bonded together by an adhesive layer 300. In a specific embodiment, the total thickness of the front plate is about 125-240 μm; the weatherable film 100 may have a thickness of about 20 to 30 μm; the thickness of the support base film 200 is about 100 to 200 μm; the adhesive layer 300 has a thickness of about 5 to 10 μm.

The outermost weatherable film 100 of the front panel mainly functions to reinforce, weather-proof, UV-resistant, moisture-proof, low dielectric constant, high breakdown voltage, etc., and preferably a PVDF film having a thickness of 20 to 30 μm may be used as the weatherable film 100, for example, a commercially available PVDF film having a thickness of 20 to 30 μm may be used, or a PVDF raw material particle having a mass content of 90% or more may be used, and an ultraviolet absorber, an abrasion-resistant filler, etc. are added to the PVDF film to form a PVDF film through melt co-extrusion and then biaxial stretching.

The supporting base film 200 is adjacent to the circuit side of the solar cell panel, and needs to provide a stronger barrier property to protect the internal circuit in addition to providing a stronger supporting protection function.

The adhesive layer 300 may be a conventional EVA adhesive, or an ultraviolet light curing adhesive.

The support base film 200 may be made of a PET film having a visible light transmittance of more than 85%, and may have a single-layer or multi-layer structure formed by biaxial stretching. The PET film can provide excellent insulation, water resistance, mechanical properties and dimensional stability. However, for solar cells, especially for CI (G) S flexible solar cells, which are mainstream products, the requirements for the front plate are high due to the process characteristics of the solar cells, which require stronger barrier property to protect the internal circuits, and the barrier property is usually required to be up to 10 ^-3 g/m ² Day level. The general idea behind enhancing the barrier properties is to increase the thickness of the material, which results in increased material costs, while increasing the unit weight and decreasing the flexibility of the material, too thick a material also results in slippage leakage when the edges of the sheet are bent. The traditional packaging process in China is difficult to achieve the required barrier property, and even in Japan with the strongest packaging process, the flexible solar cell still does not reach the level of large-scale mass production, so that the cost of the traditional flexible solar cell sold in the market is high, and the actual service life of the flexible solar cell is slightly insufficient compared with that of a crystalline silicon solar cell due to the limitation of the packaging process.

In view of this, in one embodiment of the supporting base film 200 shown in fig. 2, the supporting base film 200 includes a substrate layer 21, an in-line coating layer 22 is formed on each of both side surfaces of the substrate layer 21, and a barrier layer 23 is formed on the outside of the in-line coating layer 22 by sputtering. The thickness of the substrate layer 21 is preferably 100 to 200 μm, and may be, for example, 188 μm biaxially oriented PET film of a single layer structure, or may be formed by laminating a plurality of films (as will be described in further detail below). The barrier layer 23 is preferably composed of silicon dioxide; the thickness was 200nm.

The barrier property of the substrate layer 21 can be improved by the barrier layer 23, the thickness of the substrate layer 21 does not need to be increased, and the adaptability of the flexible solar cell is improved. In order to improve the surface smoothness and the adhesion of the barrier layer 23, it is preferable to perform an in-line coating process on both surfaces of the base material layer 21 before forming the barrier layer 23 by sputtering, and to form an in-line coating layer 22 having a thickness of preferably 0.1 to 0.3 μm on each of both sides.

The online coating can be directly through online coating machine with the coating of chemical article on the substrate layer in the production process of substrate layer 21, and online coating can be directly formed in the later stage of the production process of substrate layer, need not launch the operation again with the coiled material, and the coating forms evenly, fast, efficient, and is with low costs.

In one embodiment, the primer solution constituting the in-line coating layer 22 may be applied to the slab before or during the stretching of the polyester film constituting the substrate layer 21, and then the primer solution applied to the surface of the slab is cured to form the in-line coating layer 22 at a high temperature during the stretching process as the slab is stretched to a film having a desired thickness and the thickness is reduced.

In one embodiment, the in-line coating layer 22 is formed by uniformly mixing an acrylic resin, silica nanoparticles having a particle size of 5 to 10nm, 1,4-dioxane, polyethylene oxide, and an ethylene-vinyl acetate copolymer into a primer solution, and then curing by in-line coating.

Specifically, the mass ratio of each component of the online coating layer 22 is, respectively, acrylic resin: silica nanoparticles: 1,4-dioxane: polyethylene oxide: ethylene-vinyl acetate copolymer 100: (10-15): (20 to 30): (10-15): (5-10). Wherein the ethylene-vinyl acetate copolymer can be ethylene-vinyl acetate copolymer which is sold by the Japan three-well company and has the trademark of Evaflex 550, and the mass percentage of the contained vinyl acetate polymer is 14 percent.

According to the weight ratio of the raw materials in the following table, on-line coating layers are respectively prepared on the two side surfaces of a single-layer 188-micron biaxially oriented PET film, and then a layer of barrier layer made of silicon dioxide is respectively sputtered on the outer sides of the on-line coating layers.

As a comparison, barrier layers of 200nm thick silica were formed by sputtering directly on both side surfaces of a single layer of 188 μm biaxially oriented PET film as comparative examples. The 180 degree peel force (N/25 mm) of the barrier layers of examples 1-5 was measured to be 34.5%, 36.2%, 35.1%, 34.8%, and 36.1% higher than the comparative examples, respectively.

Further, as shown in fig. 3, the present application provides another embodiment of a supporting base film for a front sheet of a solar cell, which is similar to the embodiment shown in fig. 2, the supporting base film 200 of the present embodiment also includes a substrate layer 21, an in-line coating layer 22 is respectively disposed on both sides of the substrate layer 21, and a barrier layer 23 is formed on the outside of the in-line coating layer 22 by sputtering. Unlike the embodiment shown in fig. 2, the substrate layer 21 of the present embodiment is formed by laminating a plurality of films, and the on-line coating layer 22 and the barrier layer 23 may have the same structure and composition as those of the previous embodiment. Only the substrate layer 21 of the multilayer composite structure of the present embodiment will be described in detail below.

As shown in fig. 3-4, the substrate layer 21 of the present embodiment includes an inner layer film 1 facing one side of a solar cell (not shown in the figure) and an outer layer film 2 far away from one side of the solar cell, wherein the inner layer film 1 is formed with a plurality of inner layer prism structures 3 which are arranged in parallel at equal intervals and have isosceles trapezoid cross sections, a layer of refraction layer 4 is formed on the outer side of the inner layer prism structures 3 through vacuum sputtering, an outer layer prism structure 5 is filled in a hollow cavity between the outer layer film 2 and the refraction layer 4, and the outer layer film 2 and the refraction layer 4 are connected into a whole through the outer layer prism structure 5.

The inner layer film 1 and the outer layer film 2 can be made of PET with visible light transmittance of more than 85%, and the PET film with a double-layer structure can provide excellent insulation, water resistance, mechanical properties and dimensional stability. Two layers of prism structures which are mutually nested are formed between the inner layer film 1 and the outer layer film 2, and the two layers of prism structures are separated by the sputtered refraction layer 4, so that a channel between the two layers of prism structures is elongated, and the water resistance and the air tightness are enhanced.

In a particular embodiment, the refractive index of each of the inner and

outer prism structures

3 and 5 is less than the refractive index of the refractive layer 4. For example, the refractive layer 4 may be made of Nb having a refractive index of 2.01 to 2.48 ₂ O ₅ And (4) forming. The outer prism structure 5 may be made of uv curable acrylic resin with a refractive index of preferably 1.4-1.6 (small amounts of high refractive index particles may be added to adjust the overall refractive index, e.g., 1% -5% of lead fluoride nanoparticles, as desired). The inner prism structure 3 may be made of the same material as the outer prism structure 5, i.e., may be made of uv curable acrylic resin, and preferably has a refractive index of 1.4 to 1.6 (again, a small amount of high refractive index particles may be added thereto as needed to adjust the overall refractive index, for example, 1% to 5% of lead fluoride nanoparticles).

As mentioned above, since the flexible solar cell can be integrated in a window or a roof, an outer wall or an inner wall, and the orientation of the flexible solar cell is fixed after installation, the efficiency of the flexible solar cell is greatly affected by the direction of the sunlight, generally the efficiency of the direct sunlight is the greatest, but the time is short, and the direction of the sunlight is inclined for a large period of time. The utility model provides a set up and formed inlayer prismatic structure and outer prismatic structure in the substrate layer 21, one deck refraction layer has been set up between the two, when light slope shines on prismatic structure's trapezoidal edge, owing to there are angle of illumination and refracting index difference, make the light that the incident got into inlayer prismatic structure can assemble to prismatic structure's middle part, make the inclination of light can deflect to the direction of the perpendicular to solar wafer as far as possible to a certain extent, thereby the utilization ratio of sunshine has been improved. In addition, for the flexible solar cell laid on the roof, the efficiency of the stripes of the prism structure pointing to the north-south direction is better, and the utilization rate of the light rays facing the east-west direction at morning and evening can be improved. For the flexible solar cell laid on the vertical wall, the efficiency of the stripes of the prism structure pointing to the east-west direction is better, and the utilization rate of light rays obliquely irradiating the wall from the top when the sunlight is strongest at noon can be improved.

The inventor uses the prism film technology in the backlight plate in the field of liquid crystal display for reference about the principle of converging light rays by the prism structure. Since the field of operation of the applicant coincided with years of development on liquid crystal displays, the inventors were able to derive elicitations from the field of liquid crystal displays that vary widely in field, but such elicitations should not be considered obvious to a person of ordinary skill in the solar cell field, since the solar cell field differs considerably from the liquid crystal display field. For example, in the field of liquid crystal displays, light is refracted only from air into prisms, and there is a large difference in refractive index between air and prisms, so that an additional refractive layer is not required. In the solar cell field of the present application, the problems of the sealing property, the waterproof property and the like of the package need to be considered, and the air cannot exist in the substrate layer 21, so that the prism structure is applied to the solar cell field, and the material layers do not have a large refractive index difference, and the prism film technology in the backlight plate in the liquid crystal display field is applied to the solar cell field, so that the technical effect of light convergence cannot be directly obtained.

In addition, since the substrate layer 21 in the solar cell field needs to consider the sealing property, in the case where air is not present, it needs to consider the problem of manufacturing cost while providing a different interface material to form an integral body. The arrangement of two layers of prism structures with different refractive indexes is feasible, however, in consideration of the problem of light transmission, two materials with small light transmission difference and large refractive index difference are difficult to find, and the processing process of the two materials with large property difference has large difference, so that the defect of large cost is brought, and the matching problem of special equipment is also required to be considered, so that the arrangement is not advisable in the practical application process.

Therefore, the two layers of prism structures in the application can be prepared from materials with the same or similar properties, for example, the two layers of prism structures can be prepared from ultraviolet curing acrylic resin commonly used for prism films of liquid crystal display back plates, the processing technology of the two layers of prism structures formed by the two layers of prism structures is the same, the two layers of prism structures can be molded by the same set of ultraviolet curing equipment, and the two layers of prism structures have the same or similar light transmission and refractive indexes, so that the refractive layers can be prepared from materials with the proper refractive index range conveniently. In addition, it should be emphasized that since the solar cell needs to maintain a relatively large light transmittance, it is difficult to change the refractive index of the bulk material by adding a high refractive index material to the two-layered prism structure, because the difference between the refractive index of the added high refractive index material and the refractive index of the bulk material is large, which causes a defect in index matching and results in a decrease in the light transmittance of the material.

In another modified embodiment, the inner prism structure 3 may be made of uv curable acrylic resin with uv activated phosphor added, and the refractive index is preferably 1.6-1.7 (small amount of high refractive index particles may be added to adjust the overall refractive index, e.g., 1% -5% of lead fluoride nanoparticles, as needed). The mass percentage of the ultraviolet light excited fluorescent powder in the inner layer prism structure 3 is preferably 3% -5%. In this embodiment, a proper amount of ultraviolet light is added to excite the commercial fluorescent powder, so that the spectrum of the ultraviolet light converged into the inner layer prism structure can be regulated, and the ultraviolet light harmful to the solar cell is converted into visible light with longer wavelength, so that the technical effects of effectively preventing ultraviolet radiation and improving the light utilization efficiency are achieved.

It should be noted that the commonly used uv excited phosphors in the market usually emit red light, and are typically one or a mixture of silicate, aluminate, nitride and fluoride phosphor materials. The ultraviolet light excited fluorescent powder preferably adopts a fluoride fluorescent powder material, and has the advantages that the refractive index of the fluoride fluorescent powder material is slightly higher than that of ultraviolet light cured acrylic resin, so that the light transmittance of a prism structure prepared by the original ultraviolet light cured acrylic resin can be kept under the condition that a small amount of the fluorescent powder material is added by 3-5% (mass percentage), and the light transmittance of the material in a visible light range is weakened under the condition that the difference between the refractive index of the fluorescent material and the refractive index of a body material is large, so that the light conversion of a solar cell is not facilitated. In addition, a small amount of high refractive index fine particles may be added thereto as needed to adjust the overall refractive index, for example, 1% to 5% (mass percentage) of lead fluoride nanoparticles may be added.

This modified embodiment can further convert the ultraviolet ray in the light that assembles to the long wave visible light that can supply solar cell panel to utilize on utilizing prism structure to assemble the basis of light through add ultraviolet ray excitation phosphor powder in inlayer prism structure 3, can further improve the utilization ratio of light to reduce the harm of ultraviolet ray to solar cell panel. Of course, the addition of ultraviolet light excitation phosphor will reduce the whole light transmissivity of substrate layer 21, therefore does not suggest adding ultraviolet light excitation phosphor in outer prismatic structure 5, and because the ultraviolet light excitation phosphor that adds in inner prismatic structure 3 can convert the light of assembling, can offset the influence to the light transmissivity to a certain extent, therefore this embodiment of improvement is the scheme of compromising efficiency, obtains great sunshine utilization ratio through lower cost, can effectively prevent ultraviolet light to solar cell panel's harm simultaneously.

The method for manufacturing the solar cell front sheet of the present application is described in further detail below with reference to the accompanying drawings. As described above, the solar cell front panel of the present application includes the weather-resistant film 100 on the outer side and the support base film 200 on the inner side, and the weather-resistant film 100 and the support base film 200 are integrally bonded to each other by the adhesive layer 300. The support base film 200 comprises a base material layer 21, wherein an online coating layer 22 is respectively arranged on two side surfaces of the base material layer 21, and a barrier layer 23 is formed on the outer side of the online coating layer 22 in a sputtering mode. The substrate layer 21 is including facing inner film 1 of solar wafer one side and keeping away from outer membrane 2 of solar wafer one side, wherein, inner film 1 is last to be formed with a plurality of equidistant parallel arrangement's cross-section and is isosceles trapezoid's inner prismatic structure 3, and the inner prismatic structure 3 outside is formed with one deck refraction layer 4 through vacuum sputtering, and it has outer prismatic structure 5 to fill in the sunken cavity between outer membrane 2 and the refraction layer 4, and outer membrane 2 is connected as an organic wholely through outer prismatic structure 5 with refraction layer 4. In order to save cost and reduce working procedures, the preparation method adopts PET films with the same thickness as the inner layer film 1 and the outer layer film 2.

Further, the production method of the present application includes a production step of the support base film 200, and an adhesion step of the support base film 200 and the weather-resistant film 100. Wherein the preparation of the support base film 200 comprises:

firstly, using PET slices as raw materials for preparing a PET film, obtaining a single-layer thick sheet through melt extrusion, longitudinally stretching the single-layer thick sheet into a film after preheating, coating a mixture of components forming the on-line coating layer on one side of the film through a coating machine after longitudinally stretching, then transversely stretching, sizing, cooling and rolling to form the on-line coating layer 22 on the surface of the film, and then sputtering and forming a layer of barrier layer 23 formed by silicon dioxide on the outer side of the on-line coating layer 22 to obtain an inner layer film 1 and an outer layer film 2 with the on-line coating layer 22 and the barrier layer 23 for later use. The thicknesses of the inner layer film 1 and the outer layer film 2 are preferably 40-60 mu m, and the visible light transmittance is 85% -95%.

Then, on the side of the inner layer film 1 where the on-line coating layer 22 and the barrier layer 23 are not formed, a plurality of inner layer prism structures 3 having an isosceles trapezoid cross section, which are arranged in parallel at equal intervals, are formed by curing. For example, a roller with a pattern matching the shape of the inner prism structure may be used, the ultraviolet curable acrylic resin may be applied to the roller, the inner film 1 may be pressed and rolled along the surface of the roller, the ultraviolet curable acrylic resin may be pressed onto the inner film 1 according to the shape of the inner prism structure, and then the ultraviolet curable acrylic resin may be cured by irradiating ultraviolet light, so as to form the inner prism structure 3 having a desired shape on the inner film 1, where the refractive index of the formed inner prism structure 3 is 1.4 to 1.6. Or in another embodiment, the ultraviolet curing acrylic resin added with the ultraviolet excited phosphor may be formed into the inner prism structure 3 according to the same process, and the refractive index thereof is 1.6-1.7. The length of the lower base edge of the isosceles trapezoid of the cross section of the formed inner layer prism structure 3 is 20-30 μm, the lower base angle is 30-60 degrees, the height is 25-50 μm, and the minimum gap between adjacent inner layer prism structures 3 is 50-100 μm.

Thereafter, a refractive layer 4 is formed on the inner prism structure 3 by vacuum sputtering. For example, a layer having a refractive index of 0.5 to 2 μm in thickness can be formed on the inner prism structure 3 by vacuum sputtering2.01 to 2.48 of Nb ₂ O ₅ Since the thickness of the refractive layer 4 is formed to be relatively very thin, the refractive layer 4 is not shown in fig. 4, and the refractive layer 4 is enlarged in fig. 3 for easy understanding. It should be noted that the refraction layer 4 mainly provides an interface refraction function, and plays a certain role of isolation while ensuring light transmittance. In addition, since the inner layer prism structures 3 protrude from the surface of the inner layer film 1 during sputtering, the thickness of the refractive layer 4 formed on the surface of the inner layer prism structures 3 is slightly thicker, and the refractive layer 4 formed on the surface of the inner layer film 1 between the inner layer prism structures 3 is slightly thinner. The refractive layer 4 on the surface of the inner film 1 does not contribute to the convergence of light, and mainly functions as an insulator, and the refractive layer 4 having a thickness of 0.5 to 2 μm does not affect the light transmittance.

And then, filling ultraviolet curing acrylic resin in the concave cavity on the outer side of the refraction layer 4, and attaching an outer layer film 2 on one side far away from the solar cell piece to the outer sides of the refraction layer 4 and the filled ultraviolet curing acrylic resin, wherein the side, on which the online coating layer 22 and the barrier layer 23 are not formed, of the outer layer film 2 faces the refraction layer 4 for attachment. Preferably, when filling ultraviolet curing acrylic resin in the sunken cavity in the outside of refraction layer 4, scrape the resin outside the top of refraction layer 4 through the scraper blade for the ultraviolet curing acrylic resin who fills flushes with the top of refraction layer 4, and it is more firm to eliminate the space and guarantee bonding between each layer of laminating. Since the thickness of the refractive layer 4 is relatively very thin, the thickness of the filled uv curable acrylic resin is almost equal to that of the inner prism structure 3.

Then, irradiating ultraviolet light through one side of the barrier layer 23 of the outer layer film 2 to cure the filled ultraviolet light-cured acrylic resin to form an outer layer prism structure 5, and at the same time of curing the outer layer prism structure 5, connecting the outer layer film 2 and the refraction layer 4 into a whole through the outer layer prism structure 5, thereby preparing and obtaining the support base film 200.

The bonding step of the support base film 200 and the weather-resistant film 100 includes: one side of the outer layer film 2 supporting the base film 200 is integrally bonded to the weather-resistant film 100 through the adhesive layer 300, wherein the weather-resistant film 100 may be formed of PVDF-based PVDF film. The PVDF film can be a PVDF film with the thickness of 20-30 μm sold in the market, or a PVDF raw material particle with the mass content of more than or equal to 90 percent is added with an ultraviolet absorber, an abrasion-resistant filler and the like, and the PVDF film is formed by melt co-extrusion and then two-way stretching.

Examples 6 to 11

A substrate layer for a support base film of a solar cell front sheet was prepared according to the parameters of the following table.

Comparative examples 12 to 14

Comparative examples 12-14 used a monolayer PET film as the substrate layer, with the following parameters.

	Comparative example 12	Comparative example 13	Comparative example 14
				Thickness μm	100	150	200
Visible light transmittance	85％	90％	95％

The parametric properties of the examples were measured and compared as follows.

As can be seen from the comparison of the performance parameters of the above embodiments, the insulating property, the light transmittance, the mechanical property, the ultraviolet light blocking property, the dimensional stability and the like of the substrate layer for the front panel of the solar cell are all greatly improved, and the ultraviolet light transmittance of the improved example added with the phosphor powder is greatly reduced.

It should be appreciated by those skilled in the art that while the present application is described in terms of several embodiments, not every embodiment includes only a single embodiment. The description is thus given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including all technical equivalents which are encompassed by the claims and are to be interpreted as combined with each other in a different embodiment so as to cover the scope of the present application.

The above description is only illustrative of the present invention and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations that may be made by those skilled in the art without departing from the spirit and principles of this application shall fall within the scope of this application.

Claims

1. A solar cell front plate comprises an outer weather-resistant film (100) and an inner supporting base film (200), wherein the weather-resistant film (100) and the supporting base film (200) are bonded into a whole through a bonding layer (300); the support base film (200) is characterized by comprising a base material layer (21), wherein two side surfaces of the base material layer (21) are respectively provided with an online coating layer (22), and a barrier layer (23) is formed on the outer side of the online coating layer (22) in a sputtering mode; substrate layer (21) are including inner film (1) towards solar wafer one side and outer membrane (2) of keeping away from solar wafer one side, inner film (1) is gone up and is formed with a plurality of equidistant parallel arrangement's cross-section for isosceles trapezoid's inner prismatic structure (3), and inner prismatic structure (3) outside is formed with one deck refracting layer (4) through vacuum sputtering, and it has outer prismatic structure (5) to fill in the sunken cavity between outer membrane (2) and refracting layer (4), and outer membrane (2) are connected as an organic wholely through outer prismatic structure (5) with refracting layer (4).

2. A front plate according to claim 1, characterised in that the refractive index of the inner prism structures (3) and of the outer prism structures (5) is less than the refractive index of the refractive layer (4).

3. The front plate according to claim 1, characterized in that the refractive layer (4) is made of Nb with a refractive index of 2.01 to 2.48 ₂ O ₅ And (4) forming.

4. -front panel according to claim 1, characterized in that the barrier layer (23) consists of silicon dioxide; the thickness was 200nm.

5. The front plate according to claim 1, wherein the in-line coating layer (22) is formed by uniformly mixing acrylic resin, silica nanoparticles having a particle size of 5-10nm, 1,4-dioxane, polyethylene oxide, ethylene-vinyl acetate copolymer into a primer solution, and then curing by in-line coating; the mass ratio of each component of the online coating layer (22) is respectively that: silica nanoparticles: 1,4-dioxane: polyethylene oxide: the ethylene-vinyl acetate copolymer is 100: (10-15): (20 to 30): (10-15): (5-10).

6. A front plate according to claim 1, wherein the isosceles trapezoid of the cross-section of the inner prism structures (3) has a length of the lower base of 20 to 30 μm, a lower base angle of 30 to 60 degrees and a height of 25 to 50 μm, and the minimum gap between adjacent inner prism structures (3) is 50 to 100 μm.

7. Front panel according to claim 1, characterized in that the inner film (1) and the outer film (2) are made of PET with the same thickness having a visible light transmission of more than 85%.

8. A method for producing a solar cell front sheet according to any one of claims 1 to 7, comprising a production step of a support base film (200), and an adhesion step of the support base film (200) and the weather-resistant film (100); wherein the step of preparing the support base film (200) comprises:

using PET slices as raw materials for preparing a PET film, obtaining a single-layer thick sheet through melt extrusion, longitudinally stretching the raw materials into a film after preheating, coating a mixture of components forming an online coating layer on one side of the film through a coating machine after longitudinally stretching, then transversely stretching, shaping, cooling and rolling to form the online coating layer (22) on the surface of the film, and then sputtering and forming a barrier layer (23) formed by silicon dioxide on the outer side of the online coating layer (22) to obtain an inner layer film (1) and an outer layer film (2) with the online coating layer (22) and the barrier layer (23) for later use;

curing the side of the inner layer film (1) not formed with the on-line coating layer (22) and the barrier layer (23) to form a plurality of inner layer prism structures (3) which are arranged in parallel at equal intervals and have isosceles trapezoid-shaped sections;

forming a refraction layer (4) on the inner layer prism structure (3) through vacuum sputtering;

filling ultraviolet curing acrylic resin in the concave cavity on the outer side of the refraction layer (4), and attaching an outer layer film (2) on one side far away from the solar cell piece to the outer sides of the refraction layer (4) and the filled ultraviolet curing acrylic resin; wherein one side of the outer layer film (2) which is not provided with the on-line coating layer (22) and the barrier layer (23) faces the refraction layer (4) for jointing; one side of the barrier layer (23) penetrating the outer layer film (2) is irradiated with ultraviolet light to enable the filled ultraviolet light curing acrylic resin to be cured to form an outer layer prism structure (5), and the outer layer film (2) and the refraction layer (4) are connected into a whole through the outer layer prism structure (5) while the outer layer prism structure (5) is cured, so that the base film (200) is prepared and obtained.

9. The method of claim 8, wherein the step of bonding the support base film (200) and the weatherable film (100) comprises: one side of an outer layer film (2) supporting a base film (200) is integrally bonded with a weather-resistant film (100) through a bonding layer (300), wherein the weather-resistant film (100) is composed of a PVDF film taking PVDF as a main body.

10. The method of claim 8, wherein the weatherable film (100) has a thickness of 20-30 μ ι η.