Adhesive film, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention relates to the field of photovoltaic cells, and provides an adhesive film, a preparation method thereof and a photovoltaic module, and the preparation method comprises the steps: preparing an acrylate monomer which contains a metal element with a light conversion function; weighing an acrylate monomer, an ethylene monomer and a comonomer; the preparation method comprises the following steps: adding an acrylate monomer, an ethylene monomer and a comonomer into a high-pressure reactor, and reacting to obtain the adhesive film consisting of an acrylate block, an ethylene block and a copolymer block. The adhesive film, the preparation method thereof and the photovoltaic module provided by the embodiment of the invention are at least beneficial to improving the light conversion efficiency of the photovoltaic module.

Description

[0001] This application is a divisional application of the patent application with the application number 202310100976.5, the application date of February 6, 2023, and the invention title of "Adhesive film and its preparation method, photovoltaic module". TECHNICAL FIELD

[0002] Embodiments of the present application relate to the field of photovoltaic cells, in particular to an adhesive film and its preparation method, and a photovoltaic module. BACKGROUND

[0003] A solar cell is a device that converts light energy into electricity through the photoelectric effect or photochemical effect. A single solar cell cannot be directly used as a power source. To be used as a power source, a number of single cells must be connected in series and parallel through a solder strip and sealed tightly into a module. The solar cell module (also called solar cell panel) is the core part of a solar power generation system and the most important part of the solar power generation system. The role of the solar cell module is to convert solar energy into electrical energy, which is either stored in a storage battery or used to drive a load.

[0004] The cell sheet is very fragile, and generally needs to be provided with an adhesive film and a cover plate on the upper and lower surfaces of the cell module for protection. The cover plate is generally photovoltaic glass, which cannot be directly attached to the cell sheet, and the adhesive film is needed to play a bonding role in the middle. However, the transparent polymer adhesive film that fixes, seals and protects the cell sheet is easily aged and yellowed, or even delaminated and cracked in the outdoor harsh weather environment, causing the cell module to break or be weathered, thereby causing the entire cell module to have a decreased photoelectric conversion efficiency or be damaged by short circuit and fail.

[0005] To prevent ultraviolet light in sunlight from causing the adhesive film or backsheet and other polymer materials in the module to age and fail, a method of adding an ultraviolet light absorber to the formula is usually used to directly filter out ultraviolet light, so that high-energy ultraviolet light cannot be effectively used to generate electricity in a conventional photovoltaic module, and the module packaging efficiency cannot be substantially improved. SUMMARY

[0006] Embodiments of the present application provide an adhesive film and its preparation method, and a photovoltaic module, which at least help to improve the light conversion performance of the photovoltaic module.

[0007] According to some embodiments of the present application, the embodiments of the present application provide a preparation method of an adhesive film, which comprises: preparing an acrylic salt monomer, the acrylic salt monomer containing a metal element having a light conversion function; weighing the acrylic salt monomer, an ethylene monomer and a comonomer; and adding the acrylic salt monomer, the ethylene monomer and the comonomer into a high-pressure reactor to react, so as to obtain an adhesive film composed of an acrylic salt block, an ethylene block and a copolymer block.

[0008] In some embodiments, the reaction conditions for adding the acrylic monomer, the ethylene monomer and the comonomer into the high-pressure reactor for reaction include: a temperature range of 200-220℃; and a pressure range of 14.70-15.68 MPa.

[0009] In some embodiments, the metal element of the light conversion function includes at least one of europium (Eu), lanthanum (La), cerium (Ce), gallium (Ga), terbium (Tb), ytterbium (Yb) or lutetium (Lu).

[0010] In some embodiments, the acrylic monomer is in a mass fraction of 0.1-5, the ethylene monomer is in a mass fraction of 67-79, and the comonomer is in a mass fraction of 20-33.

[0011] In some embodiments, the comonomer includes one of a vinyl acetate monomer or an octene monomer.

[0012] In some embodiments, the step of preparing the acrylic salt includes: weighing metal oxide powder, acrylic acid and concentrated hydrochloric acid, the metal oxide powder containing a metal element with a light conversion function; slowly adding the metal oxide powder into the acrylic acid containing the concentrated hydrochloric acid for reaction until the metal oxide powder is dissolved, to obtain an initial acrylic salt; and introducing steam into the initial acrylic salt, to obtain the acrylic salt.

[0013] In some embodiments, the temperature of the steam is greater than or equal to 100℃.

[0014] In some embodiments, the conditions for slowly adding the metal oxide powder into the acrylic acid containing the concentrated hydrochloric acid for reaction include: a temperature range of 50-80℃.

[0015] In some embodiments, the molar ratio of the metal oxide powder to the acrylic acid ranges from 1:1 to 1:2; and the concentrated hydrochloric acid accounts for 1-5% of the total mass of the metal oxide powder and the acrylic acid.

[0016] In some embodiments, the particle size of the metal oxide powder ranges from 10 μm to 100 μm.

[0017] According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a film, including: a molecular chain segment of the film is composed of an acrylic salt block, an ethylene block and a copolymer block, wherein the acrylic salt block contains a metal element with a light conversion function.

[0018] According to some embodiments of the present application, the photovoltaic module further includes a cover plate covering a surface of the adhesive film away from the cell string.

[0019] The technical scheme provided by the embodiments of the present application has at least the following advantages: the adhesive film is formed by directly adding the acrylic salt monomer, the ethylene monomer and the comonomer containing the metal element with the light conversion function into the high-pressure reactor for reaction, so that the acrylic salt monomer, the ethylene monomer and the comonomer are directly polymerized to form the adhesive film. The acrylic salt monomer, the ethylene monomer and the comonomer can be connected at will during the polymerization process to form a high molecular chain segment. When the comonomer is vinyl acetate, the high molecular chain segment of the adhesive film is equivalent to a part of the acrylic salt chain segment embedded in the EVA molecular chain segment. When the comonomer is octene, the high molecular chain segment of the adhesive film is equivalent to a part of the acrylic salt chain segment embedded in the POE molecular chain segment. Since the acrylic salt contains the metal element with the light conversion function, the finally formed adhesive film can have the performance of the EVA polymer or the POE polymer itself, and can also have the light conversion function, thereby improving the light conversion capability of the adhesive film, and further facilitating the increase of the intensity of the photovoltaic module receiving irradiation and the improvement of the light conversion efficiency of the photovoltaic module. In addition, the adhesive film formed by the embodiments can connect the metal ions to the polymer skeleton through ionic bonds, so that the metal ions with the light conversion function are not easy to fall off. Compared with the way of simply mixing the light conversion substance with the adhesive film, the acrylic salt chain segment is more uniformly distributed on the molecular chain of the adhesive film, and will not gradually separate out due to the polarity of the adhesive film, and has better quality and stability. BRIEF DESCRIPTION OF DRAWINGS

[0020] One or more embodiments are illustrated by way of example in the drawings that are for illustrative purposes only, and not for the purposes of limiting the embodiments, unless otherwise specifically stated herein. In the drawings, the figures are not necessarily to scale, except if so expressly indicated. In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0021] Figure 1 A flow chart corresponding to the preparation method of the adhesive film provided by an embodiment of the present application; Figure 2 A flow chart corresponding to the step of preparing the acrylic salt provided by an embodiment of the present application; Figure 3A structural schematic diagram of a first photovoltaic module according to another embodiment of the present application is provided. Figure 4 A structural schematic diagram of a second photovoltaic module according to another embodiment of the present application is provided. DETAILED DESCRIPTION

[0022] It is found through analysis that, due to the limitation of the band gap of the solar cell, the band gap of the amorphous silicon thin film cell is about 1.7eV, the band gap of the microcrystalline silicon thin film cell can be adjusted between 1.1eV and 1.4eV, and the solar cell can only absorb the visible light to near red light part of the solar spectrum, and the ultraviolet and infrared bands of the sunlight cannot be effectively absorbed. By modifying the adhesive film, the modified adhesive film can convert the non-absorbable band into an absorbable band to improve the light conversion efficiency of the solar cell.

[0023] In the related art, the substances with light conversion function such as organic fluorescent pigments, rare earth metal organic / inorganic copolymerization, quantum dots, etc. are mixed with the adhesive film to disperse in the adhesive film, so that the adhesive film has light conversion capability, and the light conversion efficiency of the photovoltaic module is improved. However, most of these substances with light conversion function have poor compatibility with the adhesive film, which can easily affect the light transmittance of the adhesive film, and the dispersibility of the substances in the adhesive film is poor, which can gradually precipitate in the use process of the adhesive film, resulting in the decline of the use performance of the adhesive film, and further affecting the service life of the photovoltaic module. In addition, the organic substances are unstable and easy to decompose, and the quantum dot substances are difficult to synthesize and high in price, which increases the difficulty of modifying the adhesive film.

[0024] According to some embodiments of the present application, an embodiment of the present application provides a preparation method of an adhesive film to improve the light conversion efficiency of a photovoltaic module.

[0025] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art can understand that in the embodiments of the present application, many technical details are proposed in order to make the readers better understand the present application. However, the technical solutions claimed by the present application can be realized even without these technical details and various changes and modifications based on the following embodiments.

[0026] Figure 1 A flow chart corresponding to the preparation method of the adhesive film provided by an embodiment of the present application is shown in FIG. 1. Figure 2 A flow chart corresponding to the step of preparing the acrylic salt provided by an embodiment of the present application is shown in FIG. 2. The preparation method of the photovoltaic module provided by the present embodiment will be described in detail below with reference to the accompanying drawings, and the specific steps are as follows. Reference Figure 1 The preparation method of the photovoltaic module comprises: Step 101: preparing an acrylic salt monomer containing a metal element with light conversion function. Step 102: weigh the acrylic salt monomer, ethylene monomer and comonomer; Step 103: add the acrylic salt monomer, ethylene monomer and comonomer into the high-pressure reactor to react, to obtain a film composed of acrylic salt block, ethylene block and copolymer block.

[0027] The film is formed by directly adding the acrylic salt monomer, ethylene monomer and comonomer containing metal elements with light conversion function into the high-pressure reactor to react, so that the acrylic salt monomer, ethylene monomer and comonomer are directly polymerized. The acrylic salt monomer, ethylene monomer and comonomer can be connected arbitrarily during polymerization to form a high molecular chain segment. When the comonomer is vinyl acetate, the high molecular chain segment of the film corresponds to the embedded part of the acrylic salt chain segment in the EVA molecular chain segment; when the comonomer is octene, the high molecular chain segment of the film corresponds to the embedded part of the acrylic salt chain segment in the POE molecular chain segment. Since the acrylic salt contains metal elements with light conversion function, the finally formed film can have the performance of EVA polymer or POE polymer itself, and also has light conversion function, which improves the light conversion ability of the film, and further helps to increase the intensity of photovoltaic components receiving irradiation and improve the light conversion efficiency of photovoltaic components. In addition, the film formed in the embodiment can connect metal ions to the polymer skeleton through ionic bonds, so that the metal ions with light conversion function are not easy to fall off. Compared with the way of simply mixing light conversion substances with the film, the acrylic salt chain segment is more uniformly distributed on the molecular chain of the film, and will not gradually separate out due to the polarity of the film, and has better quality and stability.

[0028] When the photovoltaic module is prepared by using the adhesive film with the acrylic salt block embedded in the EVA molecular segment or the adhesive film with the acrylic salt block embedded in the POE molecular segment, the power generation of the prepared photovoltaic module is 2% to 4% more than that of the photovoltaic module prepared by using the ordinary EVA adhesive film or the ordinary POE adhesive film. In the test conditions of the IEC61215 standard, when the EVA molecular segment has the embedded acrylic salt block, the yellowing index of the EVA adhesive film is at the 0 level after the hot and humid aging for 1000 hours under the condition of 85°C / 85%RH, and the yellowing index of the EVA adhesive film is at the 1 level or below after the ultraviolet pretreatment for 1200 kWh; when the POE molecular segment has the embedded acrylic salt block, the yellowing index of the POE adhesive film is at the 0 level after the hot and humid aging for 1000 hours under the condition of 85°C / 85%RH, and the yellowing of the POE adhesive film is at the 1 level or below after the ultraviolet pretreatment for 1200 kWh. Therefore, the adhesive film preparation method provided in the embodiments of the present application can convert the ultraviolet light into the visible light available for the photovoltaic module by adding the acrylic salt block with the light conversion function in the molecular segment of the adhesive film, so as to improve the light conversion efficiency of the photovoltaic module, and at the same time, the aging effect of the ultraviolet light on the photovoltaic module can be greatly reduced, and the service life of the photovoltaic module is improved.

[0029] For the acrylic salt monomer, the acrylic salt monomer contains a metal element with a light conversion function. In some embodiments, the metal element with the light conversion function includes at least one of europium (Eu), lanthanum (La), cerium (Ce), gallium (Ga), terbium (Tb), ytterbium (Yb) or lutetium (Lu), and the corresponding acrylic salt can be europium acrylate, lanthanum acrylate, cerium acrylate, gallium acrylate, terbium acrylate, ytterbium acrylate or lutetium acrylate, etc. The metal element in the above-mentioned acrylic salt can be colorless in the ionic state, and therefore the prepared acrylic salt monomer can form a colorless adhesive film after polymerization with ethylene and a comonomer, so as to maintain the transparency of the adhesive film and avoid the color adhesive film from causing part of the light to be absorbed, thereby avoiding the adhesive film from causing the light conversion performance of the photovoltaic module to decrease.

[0030] In some embodiments, the step of preparing the acrylic salt includes: Step 201: weighing the metal oxide powder, the acrylic acid and the concentrated hydrochloric acid, and the metal oxide powder contains a metal element with a light conversion function; Step 202: slowly adding the metal oxide powder into the acrylic acid containing the concentrated hydrochloric acid to react until the metal oxide powder is dissolved, so as to obtain an initial acrylic salt; Step 203: introducing steam into the initial acrylic salt to obtain the acrylic salt.

[0031] In some embodiments, the metal oxide powder can be at least one of europium oxide (Eu2O3), lanthanum oxide (La2O3), cerium oxide (CeO2), gallium oxide (Ga2O3), terbium oxide (Tb2O3), ytterbium oxide (Yb2O3), or lutetium oxide (Lu2O3).

[0032] For example, the reaction equation of the europium oxide powder, acrylic acid, and concentrated hydrochloric acid is as follows:

[0033] It can be understood that based on the reaction equation of the europium oxide, acrylic acid, and concentrated hydrochloric acid, the reaction equation of lanthanum oxide (La2O3), cerium oxide (CeO2), gallium oxide (Ga2O3), terbium oxide (Tb2O3), ytterbium oxide (Yb2O3), or lutetium oxide (Lu2O3) with acrylic acid and concentrated hydrochloric acid can be obtained. The present embodiment does not limit the specific type of metal oxide powder.

[0034] In some embodiments, the conditions for slowly adding the metal oxide powder to the acrylic acid containing concentrated hydrochloric acid for reaction include a temperature range of 50°C to 80°C, for example, 50°C, 60°C, 65.5°C, 70°C, or 80°C. It can be understood that the metal oxide, concentrated hydrochloric acid, and acrylic acid salt need to be reacted under appropriate temperature conditions, but a too high reaction temperature is easy to produce a side reaction, and therefore, the reaction of slowly adding the metal oxide powder to the acrylic acid containing concentrated hydrochloric acid needs to be carried out within an appropriate temperature range.

[0035] In some embodiments, the particle size of the metal oxide powder ranges from 10 μm to 100 μm, for example, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, or 100 μm. When the particle size of the metal oxide powder is small, the contact area between the metal oxide and the acid can be increased, and thus the reaction rate can be improved, but a too small particle size increases the manufacturing cost of the metal oxide powder. Therefore, the particle size of the metal oxide powder needs to be selected within an appropriate range to improve the reaction rate of the metal oxide and the acid, while avoiding a too high manufacturing cost of the metal oxide powder.

[0036] For the steam, the steam can be an inert gas such as nitrogen or argon to avoid other gases reacting with the initial acrylic acid to produce byproducts.

[0037] In some embodiments, the temperature of the steam is greater than or equal to 100°C, for example, 100°C, 105°C, 110°C, or 120°C. By introducing steam with a temperature greater than or equal to 100°C into the initial acrylic acid, the concentrated hydrochloric acid in the initial acrylic acid can be volatilized to obtain an acrylic acid salt without dissolved concentrated hydrochloric acid.

[0038] For the concentrated hydrochloric acid, the concentrated hydrochloric acid can be a concentrated hydrochloric acid with a molar concentration of 12 mol / L or a mass fraction of 38%.

[0039] In some embodiments, the molar ratio of the metal oxide powder to the acrylic acid ranges from 1:1 to 1:2, for example, 1:1.1, 1:1.5, 1:1.75, or 1:2; the concentrated hydrochloric acid accounts for 1% to 5% of the total mass of the metal oxide powder and the acrylic acid, for example, 1%, 2%, 3%, 4%, or 5%. It can be understood that the amount of substance of the acrylic acid needs to be greater than that of the metal oxide powder so that the metal oxide powder can completely react with the acrylic acid to generate the acrylic acid salt. The addition of the concentrated hydrochloric acid can enhance the acidity in the reaction system, promote the metal oxide powder to react with the concentrated hydrochloric acid to generate a salt and water, and thus be conducive to the formation of the acrylic acid salt.

[0040] In some embodiments, the comonomer includes one of a vinyl acetate monomer or an octene monomer.

[0041] In one example, when the comonomer is a vinyl acetate monomer, the reaction equation of the acrylic acid salt monomer, the ethylene monomer, and the vinyl acetate monomer is as follows:

[0042] In another example, when the comonomer is an octene monomer, the reaction equation of the acrylic acid salt monomer, the ethylene monomer, and the octene monomer is as follows:

[0043] wherein n, m, and x are all positive integers greater than or equal to 1, for example, n can be 1, 5, 10, 28, or 50, etc.; m can be 1, 8, 9, 43, or 71, etc.; and x can be 1, 4, 10, 20, or 61, etc.

[0044] In some embodiments, the reaction conditions for the reaction of the acrylic salt monomer, the ethylene monomer, and the comonomer added to the high pressure reactor include a temperature range of 200 °C to 220 °C, for example, 200 °C, 205 °C, 210 °C, 215 °C, or 220 °C; and a pressure range of 14.70 MPa to 15.68 MPa, for example, 14.75 MPa, 15.11 MPa, 15.35 MPa, 15.60 MPa, or 15.68 MPa. It can be appreciated that the acrylic salt monomer, the ethylene monomer, and the comonomer need to be at an appropriate temperature to react, and an appropriate increase in temperature can increase the rate of polymerization, but too high of a temperature can easily produce side reactions. Therefore, the reaction of the acrylic salt monomer, the ethylene monomer, and the comonomer needs to be performed within an appropriate temperature range to facilitate the reaction while avoiding the production of side reactions. In addition, the acrylic salt monomer, the ethylene monomer, and the comonomer need to be at an appropriate pressure to react, and an appropriate increase in pressure can increase the rate of polymerization, but too high of a pressure can easily produce side reactions. Therefore, the reaction of the acrylic salt monomer, the ethylene monomer, and the comonomer needs to be performed within an appropriate pressure range to facilitate the reaction while avoiding the production of side reactions.

[0045] In some embodiments, the acrylic salt monomer is in a mass fraction of 0.1 to 5 (for example, 0.5, 1, 2, 3, 4, or 5), the ethylene monomer is in a mass fraction of 67 to 79 (for example, 67, 70, 72, 75, 77, or 79), and the comonomer is in a mass fraction of 20 to 33 (for example, 20, 22, 25, 28, 30, or 33).

[0046] In some embodiments, when the comonomer is vinyl acetate, the acrylic monomer can be 1-3 (e.g., 1, 1.2, 1.5, 1.9, 2.3, 2.6, 2.8 or 3) parts by mass, the ethylene monomer can be 67-72 (e.g., 67, 69, 70, 71.5 or 72) parts by mass, and the vinyl acetate monomer can be 26-32 (e.g., 26, 27, 29, 30, 31.5 or 32) parts by mass. In this way, the polymer chain segment of the film corresponds to a portion of the acrylic segment embedded in the EVA molecular chain segment, and the film formed thereby can have the physical and chemical properties of EVA itself, while also having light conversion performance, which can be conducive to improving the light conversion efficiency of the photovoltaic module. When the content of vinyl acetate in the molecular chain segment of the film is low, the EVA film has the characteristics of plastic; when the content of vinyl acetate in the molecular chain segment of the film is high, the EVA film has the characteristics of a rubber-like elastomer, and thus the parts by mass of vinyl acetate between 26 and 32 can make the EVA film have the characteristics of plastic to meet the packaging needs of the cell sheet. In addition, due to the addition of the acrylic monomer, the amount of vinyl acetate used in the formation of EVA can be appropriately reduced, and thus the performance of the EVA film can be adjusted within a certain range by adjusting the amount of vinyl acetate.

[0047] In some embodiments, when the comonomer is octene, the acrylic monomer can be 1-3 (e.g., 1, 1.2, 1.5, 1.9, 2.3, 2.6, 2.8 or 3) parts by mass, the ethylene monomer can be 67-69 (e.g., 67, 67.5, 68, 68.5 or 69) parts by mass, and the octene monomer can be 20-30 (e.g., 20, 22, 25, 28 or 30) parts by mass. In this way, the polymer chain segment of the film corresponds to a portion of the acrylic segment embedded in the POE molecular chain segment, and the film formed thereby can have the physical and chemical properties of POE itself, while also having light conversion performance, which can be conducive to improving the light conversion efficiency of the photovoltaic module. Polyolefin elastomer (POE) refers to a random copolymer of ethylene and octene with a content of greater than 20%, and the special structure of POE gives it good elasticity, thermoplasticity and transparency, etc., and it can be used as a lightweight impact-resistant modified material, a durable cable material, a long-life encapsulation material for photovoltaic cells, etc. In addition, due to the addition of the acrylic monomer, the amount of octene used in the formation of POE can be appropriately reduced, and thus the performance of the POE film can be adjusted within a certain range by adjusting the amount of octene.

[0048] In some embodiments, the acrylic monomer, the ethylene monomer and the comonomer are added into a high-pressure reactor for reaction, and an initiator is also added. In some embodiments, the initiator includes hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, azobisisobutyronitrile, azobisisoheptyl nitrile, and dimethyl azobisisobutyrate, etc.

[0049] The preparation method of the adhesive film provided in the embodiments of the present application is to directly add the acrylic monomer, the ethylene monomer and the comonomer containing the metal element with light conversion function into a high-pressure reactor for reaction, so that the adhesive film is formed by direct polymerization of the acrylic monomer, the ethylene monomer and the comonomer. In the polymerization process, the acrylic monomer, the ethylene monomer and the comonomer can be connected arbitrarily to form a high molecular chain segment. When the comonomer is vinyl acetate, the high molecular chain segment of the adhesive film is equivalent to a part of the acrylic salt chain segment embedded in the EVA molecular chain segment. When the comonomer is octene, the high molecular chain segment of the adhesive film is equivalent to a part of the acrylic salt chain segment embedded in the POE molecular chain segment. Since the acrylic salt contains the metal element with light conversion function, the finally formed adhesive film can have the performance of the EVA polymer or the POE polymer itself, and can also have the light conversion function, thereby improving the light conversion capability of the adhesive film, and further facilitating the increase of the intensity of the photovoltaic module receiving irradiation and the improvement of the light conversion efficiency of the photovoltaic module. In addition, the metal ion formed in the adhesive film of the present embodiment is connected to the polymer skeleton through an ionic bond, thereby making the metal ion with light conversion function not easy to fall off. Compared with the method of simply mixing the light conversion substance with the adhesive film, the acrylic salt chain segment is more uniformly distributed on the molecular chain of the adhesive film, and will not gradually separate out due to the polarity of the adhesive film, and has better quality and stability.

[0050] According to some embodiments of the present application, another embodiment of the present application provides an adhesive film, which can be formed by using the preparation method of the adhesive film provided in the above embodiments to improve the light conversion efficiency of the photovoltaic module. It should be noted that the same or corresponding parts as the above embodiments can refer to the corresponding description of the foregoing embodiments, which will not be described in detail below.

[0051] The adhesive film comprises: a molecular chain segment of the adhesive film is composed of an acrylic salt block, an ethylene block and a copolymer block, wherein the acrylic salt block contains a metal element with light conversion function.

[0052] The molecular chain segment of the adhesive film is composed of acrylic salt blocks, ethylene blocks and copolymer blocks, and the acrylic salt blocks contain metal elements with light conversion function. Since the metal ions are connected to the polymer skeleton through ionic bonds, the metal ions with light conversion function are not easy to fall off, and compared with the method of simply mixing light conversion substances with the adhesive film, the acrylic salt chain segments are more uniformly distributed on the molecular chain of the adhesive film, and will not gradually separate out due to the polarity of the adhesive film, and have better quality and stability. When the comonomer is vinyl acetate, the high molecular chain segment of the adhesive film is equivalent to the embedded part of the acrylic salt chain segment in the EVA molecular chain segment; when the comonomer is octene, the high molecular chain segment of the adhesive film is equivalent to the embedded part of the acrylic salt chain segment in the POE molecular chain segment. Since the acrylic salt contains metal elements with light conversion function, the finally formed adhesive film can have the performance of EVA polymer or POE polymer itself, and also has light conversion function, thereby improving the light conversion capability of the adhesive film.

[0053] According to some embodiments of the present application, the photovoltaic module provided in the embodiments of the present application has the advantages of at least improving the light conversion efficiency of the photovoltaic module.

[0054] Reference Figure 3 and Figure 4 , Figure 3 FIG. 1 is a structural schematic diagram of a first photovoltaic module provided in another embodiment of the present application, Figure 4 FIG. 2 is a structural schematic diagram of a second photovoltaic module provided in another embodiment of the present application, wherein Figure 3 FIG. 1 is a structural schematic diagram of a first photovoltaic module provided in another embodiment of the present application, Figure 4 FIG. 2 is a structural schematic diagram of a second photovoltaic module provided in another embodiment of the present application, wherein The photovoltaic module comprises: a cell string 101, the cell string 101 comprising a plurality of cell pieces 102 connected in sequence; an adhesive film 103 covering the surface of the cell string 101, wherein the molecular chain segment of the adhesive film 103 is composed of acrylic salt blocks, ethylene blocks and copolymer blocks, and the acrylic salt blocks contain metal elements with light conversion function; and a cover plate 104 covering the surface of the adhesive film away from the cell string.

[0055] For the battery piece 102, the battery piece 102 can be any one of a PERC battery, a PERT battery (Passivated Emitter and Rear Totally-diffused cell), a TOPCon battery (Tunnel Oxide Passivated Contact), and a HIT / HJT battery (Heterojunction Technology). In some embodiments, the battery piece 102 can be a single-crystal silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-element compound solar cell, which can be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell.

[0056] In some embodiments, the connected battery pieces 102 are electrically connected by the connecting component 105, for example, referring to Figure 3 and Figure 4 The front surface of the battery piece 102 has a first electrode, and the back surface of the battery piece 102 has a second electrode, the first electrode is one of a positive electrode or a negative electrode, and the second electrode is the other of the positive electrode or the negative electrode, the adjacent battery pieces 102 are all with the front surface upward, and the first electrode of any battery piece is electrically connected to the second electrode of the adjacent battery piece 102 by the connecting component 105. In other embodiments, the plurality of battery pieces can be arranged with the front surface and the back surface alternately upward in the first direction, and the connecting component can be on the same side surface of the battery piece.

[0057] For the connecting component 105, the connecting component 105 includes a solder strip, which is used for the mutual connection between the battery pieces and the aggregation of current transmission to the elements outside the photovoltaic module. In some embodiments, the solder strip can include a busbar for connecting the photovoltaic cell string and the junction box, and an interconnecting solder strip for connecting adjacent battery pieces.

[0058] In some embodiments, the battery piece can be an Interdigitated back contact (IBC) solar cell, which refers to a back junction and back contact solar cell structure in which the positive and negative metal electrodes are arranged in an interdigital manner on the back surface of the cell. The PN junction and the electrode are located on the back surface of the cell, that is, the electrodes of the emitter region and the base region of the IBC cell are on the back surface, and there is no grid line on the front surface to block the light, which can improve the photoelectric conversion performance of the cell. That is, the back surface of the battery piece has a first electrode and a second electrode, the first electrode is one of a positive electrode or a negative electrode, and the second electrode is the other of the positive electrode or the negative electrode, and the first electrode on any one of the adjacent battery pieces is electrically connected to the second electrode on the adjacent battery piece by the connecting component.

[0059] It should be noted that the number of battery pieces 102 is taken as 3 in the above description, which does not constitute a limitation on the number of battery pieces 102 in the battery string 101. In some embodiments, the number of battery pieces can be 5, 8, or 12, etc. Figure 3 Figure 4 In the above description, the number of battery pieces 102 is taken as 3, which does not constitute a limitation on the number of battery pieces 102 in the battery string 101. In some embodiments, the number of battery pieces can be 5, 8, or 12, etc.

[0060] For the adhesive film 103, the adhesive film 103 can be formed by using the preparation method of the adhesive film 103 provided in the above embodiments, or by using the adhesive film 103 provided in the above embodiments. In some embodiments, the adhesive film 103 can include a first adhesive film 113 covering one of the front surface or the back surface of the battery piece 102, and a second adhesive film 123 covering the other of the front surface or the back surface of the battery piece 102. That is, the front surface and the back surface of the battery piece 102 are both covered by the adhesive film 103 to protect the battery piece 102.

[0061] For the cover plate 104, the cover plate 104 can be a glass cover plate, a plastic cover plate, or the like, which has a light transmission function. In some embodiments, the surface of the cover plate 104 facing the adhesive film can be a concave-convex surface, thereby facilitating an increase in the utilization rate of incident light.

[0062] In some embodiments, the cover plate 104 includes a first cover plate 114 opposite the first adhesive film 123, and a second cover plate 124 opposite the second adhesive film 123. That is, the front surface and the back surface of the battery piece 102 are both covered by the adhesive film 103 and the cover plate 104 to encapsulate the battery piece 102 to form a photovoltaic module, and the adhesive film 103 and the cover plate 104 can protect the battery piece 102.

[0063] ​The photovoltaic module provided by the embodiments of the present application has a molecular chain segment of the adhesive film composed of an acrylic salt block, an ethylene block and a copolymer block, wherein the acrylic salt block contains a metal element having a light conversion function, so that the adhesive film formed can have a light conversion function to improve the light conversion efficiency of the photovoltaic module. Since the metal ion is connected to the polymer skeleton through an ionic bond, the metal ion having the light conversion function is not easy to fall off, compared with the way of simply mixing the light conversion substance with the adhesive film, the acrylic salt chain segment is more uniformly distributed on the molecular chain of the adhesive film, and will not gradually separate out due to the polarity of the adhesive film, and has better quality and stability. When the comonomer is vinyl acetate, the high molecular chain segment of the adhesive film is equivalent to the embedded part of the acrylic salt chain segment in the EVA molecular chain segment; when the comonomer is octene, the high molecular chain segment of the adhesive film is equivalent to the embedded part of the acrylic salt chain segment in the POE molecular chain segment. Since the acrylic salt contains a metal element having a light conversion function, the adhesive film formed finally can have the performance of the EVA polymer or the POE polymer itself, and can also have a light conversion function, thereby improving the light conversion capability of the adhesive film.

[0064] Those skilled in the art can understand that the above-mentioned embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A method for producing a film, characterized by, The method comprises the following steps: Preparation of acrylic acid salt monomer containing metal elements with light conversion function, wherein the metal elements with light conversion function include at least one of europium, lanthanum, cerium, gallium, terbium, ytterbium or lutetium; Weighing the acrylic acid salt monomer, ethylene monomer and comonomer, wherein the comonomer includes one of vinyl acetate monomer or octene monomer; Adding the acrylic acid salt monomer, the ethylene monomer and the comonomer into a high-pressure reactor for reaction, so that the acrylic acid salt monomer, the ethylene monomer and the comonomer are polymerized to obtain a film composed of acrylic acid salt block, ethylene block and copolymer block, wherein the acrylic acid salt monomer, the ethylene monomer and the comonomer are connected randomly during polymerization to form the high molecular chain segment of the film.

2. The method of claim 1, wherein the adhesive film is prepared by the steps of: The reaction conditions for adding the acrylic acid salt monomer, the ethylene monomer and the comonomer into the high-pressure reactor for reaction include that the temperature ranges from 200℃ to 220℃ and the pressure ranges from 14.70MPa to 15.68MPa.

3. The method for preparing the adhesive film according to claim 1, characterized in that, The mass fraction of the acrylic acid salt monomer is 0.1-5, the mass fraction of the ethylene monomer is 67-79, and the mass fraction of the comonomer is 20-33.

4. The method of claim 1, wherein the adhesive film is prepared by the steps of: The step of preparing the acrylic acid salt comprises the following steps: Weighing metal oxide powder containing the metal elements with light conversion function, acrylic acid and concentrated hydrochloric acid; Slowly adding the metal oxide powder into the acrylic acid containing the concentrated hydrochloric acid for reaction until the metal oxide powder is dissolved to obtain initial acrylic acid salt; Passing steam into the initial acrylic acid salt to obtain the acrylic acid salt.

5. The method of claim 4, wherein the adhesive film is prepared by the steps of: The temperature of the steam is greater than or equal to 100℃.

6. The method of claim 4, wherein the adhesive film is prepared by the steps of: The conditions for slowly adding the metal oxide powder into the acrylic acid containing the concentrated hydrochloric acid for reaction include that the temperature ranges from 50℃ to 80℃.

7. The method of claim 4, wherein the adhesive film is prepared by the steps of: The molar ratio of the metal oxide powder to the acrylic acid ranges from 1:1 to 1:2, and the concentrated hydrochloric acid accounts for 1%-5% of the total mass of the metal oxide powder and the acrylic acid.

8. The method of claim 4, wherein the adhesive film is prepared by the steps of: The particle size of the metal oxide powder ranges from 10μm to 100μm.

9. An adhesive film, characterized by The film is prepared by the preparation method of the film according to any one of claims 1-8, the molecular chain segment of the film is composed of acrylic acid salt block, ethylene block and copolymer block, the acrylic acid salt monomer, the ethylene monomer and the comonomer are connected randomly in the high molecular chain segment of the film, and the acrylic acid salt block contains metal elements with light conversion function.

10. A photovoltaic module, characterized by, The method comprises the following steps: A battery string comprising a plurality of sequentially connected battery pieces; A film prepared by the preparation method of the film according to any one of claims 1-8, wherein the molecular chain segment of the film is composed of acrylic acid salt block, ethylene block and copolymer block, and the acrylic acid salt block contains metal elements with light conversion function; A cover plate covering the surface of the film away from the battery string.

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