A light-to-adhesive film for a heterojunction cell and a method of manufacturing the same

Abstract

This invention provides a light transfer film for heterojunction solar cells and its preparation method, belonging to the field of photovoltaic module technology. It includes a first light transfer film layer and a second light transfer film layer. The first light transfer film layer is prepared from the following components by weight: 40-100 parts EVA matrix resin or POE matrix resin, 0.75-1.55 parts UV light transfer agent, 0.05-1.5 parts crosslinking agent, 0.05-1 part UV absorber, 0.05-1.2 parts light stabilizer, and 0.03... ~0.6 parts antioxidant, 1~3 parts water-blocking agent; the second phototransfer film layer is made of the following components by weight: 40~100 parts barrier layer matrix resin, 0.05~1.5 parts crosslinking agent, 0.05~1 part ultraviolet absorber, 0.05~1.2 parts light stabilizer, 0.03~0.6 parts antioxidant, 1~3 parts water-blocking agent; the present invention can significantly reduce the cost of phototransfer film by carefully selecting material ratios and layered structures, thereby further improving the cost-effectiveness of phototransfer film.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, specifically to a light transfer film for heterojunction solar cells and its preparation method. Background Technology

[0002] Heterojunction solar cells use single-sided or double-sided microcrystalline technology. The surface is more susceptible to damage from ultraviolet radiation due to the Si-H groups, resulting in defects on the original silicon surface. Compared with other battery technologies, heterojunction solar cells under ultraviolet radiation have greater power decay and higher requirements for encapsulation materials. Against this background, phototransfer films have emerged.

[0003] However, the core material for phototransfer coating—the phototransfer agent—is currently subject to a monopoly by Japan, raising concerns and anxieties from various quarters. Firstly, Japan's monopoly could lead to supply chain instability. If Japanese suppliers experience production problems, logistical disruptions, or trade restrictions, global heterojunction solar cell manufacturers will face a shortage of phototransfer agents, impacting production schedules and delivery times. Secondly, Japan's monopoly could also cause cost issues. Due to supply chain uncertainties and reliance on Japanese suppliers, heterojunction solar cell manufacturers may need to pay higher prices to ensure a stable supply of phototransfer agents, increasing production costs and reducing the competitiveness of heterojunction solar cells. Furthermore, Japan's monopoly could constrain technological innovation and industrial upgrading. Since the phototransfer agent is a core material in phototransfer coating technology, its performance and stability directly affect the performance and lifespan of heterojunction solar cells. If Japanese suppliers maintain a leading position in phototransfer agent technology or impose patent restrictions, it will limit innovation and breakthroughs in phototransfer coating technology by other countries and regions. Summary of the Invention

[0004] The purpose of this invention is to provide a light transfer film for heterojunction solar cells and its preparation method, so as to overcome the problems existing in the prior art. This invention can significantly reduce the cost of light transfer film by carefully selecting material ratios and hierarchical structures, thereby further improving the cost-effectiveness of light transfer film.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A light transfer adhesive film for a heterojunction solar cell includes a first light transfer adhesive film layer and a second light transfer adhesive film layer. The first phototransfer film layer is prepared from the following components in parts by weight: 40-100 parts EVA matrix resin or POE matrix resin, 0.75-1.55 parts UV light transfer agent, 0.05-1.5 parts crosslinking agent, 0.05-1 part UV absorber, 0.05-1.2 parts light stabilizer, 0.03-0.6 parts antioxidant, and 1-3 parts water-blocking agent; The second phototransfer film layer is prepared from the following components in parts by weight: 40-100 parts of barrier layer matrix resin, 0.05-1.5 parts of crosslinking agent, 0.05-1 part of ultraviolet absorber, 0.05-1.2 parts of light stabilizer, 0.03-0.6 parts of antioxidant, and 1-3 parts of water-blocking agent; Furthermore, the thickness of the first phototransfer film layer is 0.1~0.5 mm; Furthermore, the thickness of the second phototransfer film layer is 0.3~0.6 mm; Furthermore, the first light transfer film layer and the second light transfer film layer are formed by double-layer co-pressing. Furthermore, the crosslinking agent is a silane coupling agent or an isocyanate coupling agent; Furthermore, the UV phototransfer agent is a pyrolysis-type free radical photoinitiator or a cationic photoinitiator; Furthermore, the water-blocking agent contains butyl rubber and silicone rubber.

[0006] A method for preparing a light transfer adhesive film for a heterojunction solar cell, based on the aforementioned light transfer adhesive film for a heterojunction solar cell, includes the following steps: (1) Mix EVA matrix resin or POE matrix resin with crosslinking agent, and granulate by reactive extrusion through a twin-screw granulation line to obtain graft material A. After mixing graft material A with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence, the mixture is extruded and cast to obtain the first light transfer film layer. (2) The barrier layer matrix resin is mixed with the crosslinking agent and granulated by reaction extrusion through a twin-screw granulation line to obtain graft material B. Graft material B is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast to obtain the second light transfer film layer. (3) The first light transfer film layer obtained in (1) and the second light transfer film layer obtained in (2) are synthesized by co-pressing to form a light transfer film; Furthermore, the extrusion casting temperature in (1) is 80~110 ℃; Furthermore, the extrusion casting temperature in (2) is 100~150 ℃.

[0007] The above technical solution has the following advantages or beneficial effects: This invention provides a light transfer film for heterojunction solar cells. Through precise material formulation, the amount of high-cost materials, such as UV light transfer agents and specific matrix resins, is reduced while ensuring the basic functions of the light transfer film, thereby significantly reducing production costs. The layered structure design allows each layer of material to fully exert its maximum effectiveness, avoiding material waste and further reducing overall costs. Addressing the sensitivity of heterojunction solar cells to moisture, this invention also features a specially designed water-blocking layer, effectively improving the water-blocking performance of the light transfer film, thus extending the lifespan and performance stability of the heterojunction solar cell. By selecting relatively low-cost but high-performance EVA or POE matrix resins as base materials, the overall material cost of the light transfer film is reduced.

[0008] Furthermore, the thickness of the first light transfer film layer is 0.1~0.5 mm, which ensures that the UV light transfer agent can be evenly distributed and play an effective role, efficiently converting ultraviolet light into light that is harmless to the battery. The appropriate thickness also reduces the reflection and scattering of light inside the film, improving the light transmittance and the photoelectric conversion efficiency of the battery module.

[0009] Furthermore, the second phototransfer film layer has a thickness of 0.3~0.6 mm. As a barrier layer, its thicker structure provides a stronger water barrier, which can effectively prevent water vapor from entering the heterojunction cell even under extreme weather conditions, ensuring the stability and service life of the cell.

[0010] Furthermore, the dual-layer co-pressing process simplifies the production process, avoids the errors and increased costs that may result from multi-step processing, and at the same time, reduces the waste of raw materials and improves the utilization rate of materials through one-time molding, thereby reducing production costs.

[0011] Furthermore, silane coupling agents are a special type of molecule that can react with both inorganic and organic materials. They can significantly improve the bonding strength between the phototransfer film and the heterojunction solar cell. Through chemical bonding, silane coupling agents can couple organic polymers and inorganic materials together, thereby enhancing the bonding force between the phototransfer film and the solar cell. Isocyanate coupling agents also have excellent bonding properties. They can react chemically with other components in the phototransfer film to form strong chemical bonds, which helps to improve the overall strength and stability of the phototransfer film and reduce delamination or failure caused by insufficient bonding force.

[0012] Furthermore, by using pyrolytic free radical photoinitiators or cationic photoinitiators as UV light transfer agents, the spectral response characteristics of the light transfer film can be adjusted, thereby customizing a light transfer film with specific spectral response characteristics to further improve the photoelectric conversion efficiency of the battery.

[0013] Furthermore, butyl rubber is an organic polymer material with excellent aging resistance, chemical corrosion resistance, and high temperature resistance. It can form a tight waterproof layer, effectively preventing moisture from penetrating into the interior of the heterojunction cell and protecting the battery components from moisture erosion. Silicone also has good waterproof properties, and when used in conjunction with butyl rubber, it can further enhance the waterproof effect of the phototransfer film.

[0014] This invention also provides a method for preparing a light transfer film for heterojunction solar cells. A crosslinking agent reacts chemically with a matrix resin to form a graft copolymer, improving the crosslinking degree and heat resistance of the material. The addition of a UV light transfer agent enables the film to convert ultraviolet light into other wavelengths of light that are harmless to the heterojunction solar cell, thus improving the photoelectric conversion efficiency. The addition of a water-blocking agent (including butyl rubber and silicone, etc.) significantly enhances the waterproof performance of the film, effectively preventing moisture from penetrating into the heterojunction solar cell and extending its lifespan. The addition of ultraviolet absorbers, light stabilizers, and antioxidants enhances the weather resistance and stability of the film, enabling it to resist the erosion of environmental factors such as ultraviolet radiation and ozone, maintaining long-term performance stability. This preparation method employs a twin-screw granulation line and extrusion casting process, achieving continuous and automated production of the film, improving production efficiency and reducing production costs.

[0015] Furthermore, within a temperature range of 80~110 ℃, the EVA or POE matrix resin and its additives (such as crosslinking agents, UV light transfer agents, UV absorbers, etc.) exhibit good flowability, ensuring that the material can be evenly distributed during the extrusion casting process, avoiding material accumulation or uneven distribution problems caused by insufficient flowability.

[0016] Furthermore, within a temperature range of 100~150 ℃, the barrier layer matrix resin (such as PET, PEN, etc.) and its additives (such as crosslinking agents, UV light transfer agents, ultraviolet absorbers, etc.) can maintain good physical and chemical properties, which helps to ensure that the light transfer film will not degrade or lose performance due to excessively high temperature during the preparation process. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart illustrating the light transfer film for a heterojunction solar cell and its preparation method according to the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention. To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention. It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0019] Example 1: This invention provides a light transfer film for a heterojunction solar cell, comprising a first light transfer film layer and a second light transfer film layer; The first phototransfer film layer is prepared from the following components in parts by weight: 40 parts EVA matrix resin, 0.75 parts pyrolysis free radical photoinitiator, 0.05 parts silane coupling agent, 0.05 parts ultraviolet absorber, 0.05 parts light stabilizer, 0.03 parts antioxidant, 1 part water barrier agent; The second phototransfer film layer is prepared from the following components in parts by weight: 40 parts barrier layer matrix resin, 0.05 parts silane coupling agent, 0.05 parts ultraviolet absorber, 0.05 parts light stabilizer, 0.03 parts antioxidant, 1 part water-blocking agent; Preferably, the thickness of the first phototransfer film layer is 0.1 mm, and the thickness of the second phototransfer film layer is 0.3 mm; Preferably, the first light transfer film layer and the second light transfer film layer are formed by double-layer co-pressing. Preferably, the water-blocking agent contains butyl rubber and silicone.

[0020] Example 2: This invention provides a light transfer film for a heterojunction solar cell, comprising a first light transfer film layer and a second light transfer film layer; The first phototransfer film layer is prepared from the following components in parts by weight: 80 parts EVA matrix resin, 1 part pyrolysis free radical photoinitiator, 1 part silane coupling agent, 0.5 parts UV absorber, 1 part light stabilizer, 0.3 parts antioxidant, 2 parts water barrier agent; The second phototransfer film layer is prepared from the following components in parts by weight: 80 parts barrier layer matrix resin, 1 part silane coupling agent, 0.5 parts ultraviolet absorber, 1 part light stabilizer, 0.3 parts antioxidant, 2 parts water barrier agent; Preferably, the thickness of the first phototransfer film layer is 0.3 mm, and the thickness of the second phototransfer film layer is 0.5 mm; Preferably, the first light transfer film layer and the second light transfer film layer are formed by double-layer co-pressing. Preferably, the water-blocking agent contains butyl rubber and silicone.

[0021] Example 3: This invention provides a light transfer film for a heterojunction solar cell, comprising a first light transfer film layer and a second light transfer film layer; The first phototransfer film layer is prepared from the following components in parts by weight: 100 parts POE matrix resin, 1.55 parts cationic photoinitiator, 1.5 parts isocyanate coupling agent, 1 part UV absorber, 1.2 parts light stabilizer, 0.6 parts antioxidant, 3 parts water barrier agent; The second phototransfer film layer is prepared from the following components in parts by weight: 100 parts barrier layer matrix resin, 1.5 parts isocyanate coupling agent, 1 part ultraviolet absorber, 1.2 parts light stabilizer, 0.6 parts antioxidant, 3 parts water barrier agent; Preferably, the thickness of the first phototransfer film layer is 0.5 mm, and the thickness of the second phototransfer film layer is 0.6 mm; Preferably, the first light transfer film layer and the second light transfer film layer are formed by double-layer co-pressing. Preferably, the water-blocking agent contains butyl rubber and silicone.

[0022] Example 4: like Figure 1 As shown, this invention provides a method for preparing a light transfer film for a heterojunction solar cell. Based on the aforementioned light transfer film for a heterojunction solar cell, the method includes the following steps: (1) EVA matrix resin is mixed with silane coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material A. Graft material A is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 80 °C to obtain the first light transfer film layer. (2) The barrier layer matrix resin is mixed with silane coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material B. Graft material B is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 100°C to obtain the second light transfer film layer. (3) The first light transfer film layer obtained in (1) and the second light transfer film layer obtained in (2) are co-pressed to synthesize a light transfer film.

[0023] Example 5: like Figure 1 As shown, this invention provides a method for preparing a light transfer film for a heterojunction solar cell. Based on the aforementioned light transfer film for a heterojunction solar cell, the method includes the following steps: (1) POE matrix resin is mixed with silane coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material A. Graft material A is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 100 °C to obtain the first light transfer film layer. (2) The barrier layer matrix resin is mixed with silane coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material B. Graft material B is then mixed with UV light transfer agent, ultraviolet absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 125°C to obtain the second light transfer film layer. (3) The first light transfer film layer obtained in (1) and the second light transfer film layer obtained in (2) are co-pressed to synthesize a light transfer film.

[0024] Example 6: like Figure 1 As shown, this invention provides a method for preparing a light transfer film for a heterojunction solar cell. Based on the aforementioned light transfer film for a heterojunction solar cell, the method includes the following steps: (1) The POE matrix resin is mixed with the isocyanate coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material A. Graft material A is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 110°C to obtain the first light transfer film layer. (2) The barrier layer matrix resin is mixed with isocyanate coupling agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material B. Graft material B is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast at 150 °C to obtain the second light transfer film layer. (3) The first light transfer film layer obtained in (1) and the second light transfer film layer obtained in (2) are co-pressed to synthesize a light transfer film.

[0025] The present invention has the following beneficial effects: Initially, the core material for light transfer film, light transfer agent, was exclusively supplied by Japan. To further reduce the cost of the components, the project team proactively collaborated with domestic manufacturers to promote the localization of light transfer agent production, which significantly reduced the cost of light transfer film and further improved its cost-effectiveness. Besides technological innovations in encapsulation films, other encapsulation materials are also expected to contribute to cost reduction in heterojunction modules. Addressing the moisture sensitivity of heterojunction cells, this invention introduces butyl rubber and traditional silicone for water blocking. However, butyl rubber is blended with key raw materials such as polyisobutylene, and currently, these raw materials are mainly imported, resulting in high costs. As of November 2023, the project team's cost calculations for heterojunction modules showed that the material cost of heterojunction modules had decreased to 0.4788 yuan / W, which is 0.0007 yuan / W lower than that of PERC modules. In the future, combined with cost reduction measures for heterojunction module encapsulation materials, the encapsulation cost is expected to be lower than that of PERC modules, and the module power and efficiency will also have higher advantages.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light transfer adhesive film for heterojunction solar cells, characterized in that, Includes a first light transfer film layer and a second light transfer film layer; The first phototransfer film layer is prepared from the following components in parts by weight: 40-100 parts EVA matrix resin or POE matrix resin, 0.75-1.55 parts UV light transfer agent, 0.05-1.5 parts crosslinking agent, 0.05-1 part UV absorber, 0.05-1.2 parts light stabilizer, 0.03-0.6 parts antioxidant, and 1-3 parts water-blocking agent; The second phototransfer film layer is prepared from the following components in parts by weight: 40-100 parts of barrier layer matrix resin, 0.05-1.5 parts of crosslinking agent, 0.05-1 part of ultraviolet absorber, 0.05-1.2 parts of light stabilizer, 0.03-0.6 parts of antioxidant, and 1-3 parts of water-blocking agent.

2. The light transfer adhesive film for a heterojunction solar cell according to claim 1, characterized in that, The thickness of the first phototransfer film layer is 0.1~0.5 mm.

3. The light transfer adhesive film for a heterojunction solar cell according to claim 1, characterized in that, The thickness of the second phototransfer film layer is 0.3~0.6 mm.

4. The light transfer adhesive film for a heterojunction solar cell according to claim 1, characterized in that, The first light transfer film layer and the second light transfer film layer are formed by double-layer co-pressing.

5. The light transfer adhesive film for a heterojunction solar cell according to claim 1, characterized in that, The crosslinking agent is a silane coupling agent or an isocyanate coupling agent.

6. The light transfer adhesive film for a heterojunction solar cell according to claim 1, characterized in that, The UV phototransfer agent is a pyrolysis-type free radical photoinitiator or a cationic photoinitiator.

7. The phototransfer film for heterojunction solar cells according to claim 1, characterized in that, The water-blocking agent contains butyl rubber and silicone.

8. A method for preparing a light transfer adhesive film for a heterojunction solar cell, based on the light transfer adhesive film for a heterojunction solar cell according to any one of claims 1-7, characterized in that, Includes the following steps: S1, mix EVA matrix resin or POE matrix resin with crosslinking agent, and granulate by reactive extrusion through a twin-screw granulation line to obtain graft material A. Graft material A is then mixed sequentially with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent, and then extruded and cast to obtain the first light transfer film layer. S2, the barrier layer matrix resin is mixed with a crosslinking agent and granulated by reactive extrusion through a twin-screw granulation line to obtain graft material B. Graft material B is then mixed with UV light transfer agent, UV absorber, light stabilizer, antioxidant and water barrier agent in sequence and extruded and cast to obtain the second light transfer film layer. S3, the first light transfer film layer obtained in S1 and the second light transfer film layer obtained in S2 are co-pressed to synthesize a light transfer film.

9. A method for preparing a light transfer film for a heterojunction solar cell according to claim 8, characterized in that, The extrusion casting temperature in S1 is 80~110 ℃.

10. A method for preparing a light transfer film for a heterojunction solar cell according to claim 8, characterized in that, The extrusion casting temperature in S2 is 100~150 ℃.

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