Perovskite solar cell encapsulation composite film and low-temperature encapsulation method using the same

Abstract

The present application provides a solar cell packaging composite film and a low-temperature packaging method using the same, the solar cell packaging composite film comprising a heat-sealing layer, a material of which comprises a first polyolefin elastomer having an alkyl group with a carbon number of 2 to 8 as a side chain and a melting point of 60°C to 120°C; a first adhesive layer; an oxygen barrier layer, a material of which comprises an ethylene / vinyl alcohol copolymer (ethylene content: 25 to 50 mole percent); a second adhesive layer; and a functional surface layer, a material of which comprises a second polyolefin elastomer having an alkyl group with a carbon number of 2 to 8 as a side chain and a melting point of 60°C to 160°C. The solar cell packaging composite film can be used in a low-temperature packaging process for a perovskite solar cell, thereby maintaining the photoelectric conversion efficiency thereof while improving the stability thereof, and maintaining the flexible or flexible characteristics thereof.

Description

Technical Field

[0001] This invention relates to a solar cell encapsulation film and an encapsulation method using the same, and more particularly to a solar cell encapsulation composite film and a low-temperature encapsulation method using the same. Background Technology

[0002] With the development and progress of science and technology, the demand for energy is increasing day by day. In addition, with the emphasis placed on net-zero carbon emission goals by various countries in recent years, how to improve the utilization rate of renewable energy has become an indispensable research focus for the future. Renewable energy usually includes solar energy, geothermal energy, hydropower, and wind power. Among them, solar energy has advantages such as stable energy source, low cost, and high security, so the related technologies have developed relatively quickly and matured.

[0003] A solar cell is a device that converts sunlight into electrical energy through the photovoltaic effect. Currently, the most common type of solar cell is the silicon solar cell, which uses silicon (Si) as its primary material. It boasts advantages such as high power conversion efficiency (PCE) and high stability. However, it also suffers from drawbacks such as high energy consumption during manufacturing, high cost, and limited space constraints, hindering its widespread application in urban buildings and residential buildings. Therefore, both industry and academia are actively developing novel materials applicable to solar cells.

[0004] Perovskite solar cells (PSCs) are novel solar cells that use compounds (or perovskite materials) with the same crystal structure as perovskite (chemical formula CaTiO3) as their main material. The perovskite crystal structure is generally cubic or octahedral and can be represented by the general formula ABX3, where A ions usually refer to organic cations, with CH3NH3 being a common example. + (abbreviated as MA) and CH(NH2)2 + (Abbreviated as FA); B ions usually refer to metal cations, the most common of which is Pb. 2+ and Sn 2+ X ions typically refer to halide anions, the most common type being I... - Cl - and Br -In the perovskite crystal structure, the A ion is located at the corner of the cubic unit cell and is surrounded by 12 X ions to form a coordinated octahedron with a coordination number of 12. The radii of the A and X ions are similar, and together they form a cubic close packing. The B ion is located at the center of the cubic unit cell and is surrounded by 6 X ions to form a coordinated cubic octahedron with a coordination number of 6.

[0005] Perovskite solar cells are simple to manufacture, low in cost, and can be made into thin, flexible (or pliable) solar cells, making them suitable for a wide range of applications and attracting considerable attention in recent years. However, currently, perovskite solar cells have only achieved a photoelectric conversion efficiency of approximately 26.1% in academic research. For practical application or commercial development, the perovskite material's susceptibility to reaction with oxygen and moisture in the air can affect its performance. Therefore, how to prevent perovskite material from contacting oxygen and moisture to improve the stability of perovskite solar cells remains a pressing issue that needs to be addressed.

[0006] To address the stability issues of perovskite solar cells, existing technologies have developed encapsulation processes to effectively prevent the perovskite material from contacting oxygen and moisture in the air. Generally, this encapsulation process involves placing the solar cell module within an encapsulation material (usually an encapsulation film) and then completing the encapsulation through a hot-pressing process. Thermoplastic organic materials are frequently chosen as encapsulation materials due to their high flexibility, bendability, and low cost; examples include ethylene / vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), and polyisobutylene (PIB). However, the hot-pressing temperature for encapsulation using thermoplastic organic materials typically exceeds 130°C. To improve the photoelectric conversion efficiency of perovskite solar cells, they require organic carriers with a thermal stability temperature below 85°C as transport materials. Therefore, thermoplastic organic materials are generally unsuitable for the encapsulation process of perovskite solar cells.

[0007] Due to the temperature limitations of hot-pressing in the encapsulation process of perovskite solar cells, ultraviolet-curable materials with lower encapsulation operating temperatures, such as epoxy resin, are currently mostly chosen as encapsulation materials for perovskite solar cells. However, since ultraviolet-curable materials typically have insufficient oxygen barrier properties, they generally need to be encapsulated together with rigid transparent glass. Furthermore, ultraviolet-curable materials have poor flexibility after curing. Therefore, perovskite solar cells encapsulated with ultraviolet-curable materials lack flexibility and adaptability, significantly limiting their application range.

[0008] Therefore, it is evident that there is still a need to research and develop novel encapsulation materials that can complete the encapsulation process of perovskite solar cells at low temperatures (e.g., below 85°C) to maintain their photoelectric conversion efficiency and improve their stability. At the same time, these encapsulated perovskite solar cells should retain their flexibility or adaptability, thereby expanding their application range. This would facilitate their widespread use in urban buildings or general residences, thus meeting the goal of increasing the utilization rate of renewable energy. Summary of the Invention

[0009] In view of the problems that still exist in the prior art, the purpose of the present invention is to provide a novel encapsulation material that can be used to complete the encapsulation process of perovskite solar cells at low temperature (e.g., below 85°C), thereby achieving a photoelectric conversion efficiency similar to that before encapsulation while improving its stability through low-temperature encapsulation, and at the same time enabling the encapsulated perovskite solar cells to retain flexible or pliable characteristics.

[0010] To achieve the aforementioned objectives, the present invention provides a solar cell encapsulation composite film comprising: a heat-sealing layer, the heat-sealing layer being made of a first polyolefin elastomer (POE), wherein the chemical structure of the first polyolefin elastomer has a first main carbon chain and a plurality of first side chains connected to the first main carbon chain, and each of the plurality of first side chains is independently an alkyl group having 2 to 8 carbon atoms; the melting point of the first polyolefin elastomer is greater than or equal to 60°C and less than or equal to 120°C; a first adhesive layer disposed on the surface of the heat-sealing layer; and an oxygen barrier layer disposed on the surface of the first adhesive layer, wherein the oxygen barrier layer is made of an ethylene / vinyl alcohol copolymer. The ethylene / vinyl alcohol copolymer (EVOH) contains 25 to 50 mol% ethylene; a second adhesive layer disposed on the surface of the oxygen barrier layer; and a functional surface layer disposed on the surface of the second adhesive layer, wherein the material of the functional surface layer comprises a second polyolefin elastomer, wherein the chemical structure of the second polyolefin elastomer has a second main carbon chain and a plurality of second side chains connected to the second main carbon chain, and each of the plurality of second side chains is independently an alkyl group having 2 to 8 carbon atoms; the melting point of the second polyolefin elastomer is greater than or equal to 60°C and less than or equal to 160°C.

[0011] By selecting multilayer bodies with different functions to form a composite film and controlling the forming materials of specific layers, the solar cell encapsulation composite film of the present invention can complete the encapsulation process of perovskite solar cells at low temperatures (e.g., below 85°C). This allows the encapsulated perovskite solar cells to achieve photoelectric conversion efficiency similar to that before encapsulation, while improving stability through low-temperature encapsulation. Furthermore, because the solar cell encapsulation composite film of the present invention is flexible and has good oxygen and water barrier properties, it does not require the use of rigid glass in the encapsulation process. Therefore, the encapsulated perovskite solar cells maintain their flexibility and adaptability, thus expanding their application range and facilitating the development of perovskite solar cells into commercial products or their practical application in urban buildings or general residences.

[0012] In some embodiments of the present invention, the carbon number spacing between any two adjacent first side chains on the first main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 7 carbon atoms. In other embodiments of the present invention, the carbon number spacing between any two adjacent first side chains on the first main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 6 carbon atoms. In still other embodiments of the present invention, the carbon number spacing between any two adjacent first side chains on the first main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 5 carbon atoms.

[0013] In some embodiments of the invention, each of the plurality of first side chains is independently an alkyl group having 2 to 6 carbon atoms. In other embodiments of the invention, each of the plurality of first side chains is independently an alkyl group having 4 to 6 carbon atoms. It should be understood that the melting point of the first polyolefin elastomer is affected by the length (i.e., the number of carbon atoms) of the plurality of first side chains. In some embodiments of the invention, the plurality of first side chains may be n-alkyl groups.

[0014] In some embodiments of the present invention, the melting point of the first polyolefin elastomer is greater than or equal to 80°C and less than or equal to 120°C. In other embodiments of the present invention, the melting point of the first polyolefin elastomer is greater than or equal to 90°C and less than or equal to 110°C.

[0015] In some embodiments of the present invention, the first polyolefin elastomer is copolymerized from a first alkene and a second alkene, wherein the first alkene has 2 to 5 carbon atoms, and the second alkene has 6 to 10 carbon atoms. In other embodiments of the present invention, the first polyolefin elastomer is copolymerized from a first alkene and a second alkene, wherein the first alkene has 2 to 4 carbon atoms, and the second alkene has 6 to 8 carbon atoms. In other embodiments of the present invention, the first polyolefin elastomer is copolymerized from ethylene and octene. In other embodiments of the present invention, the first polyolefin elastomer is copolymerized from ethylene and isooctene. In other embodiments of the present invention, the first polyolefin elastomer is copolymerized from ethylene and 6-methyl-1-heptene. In other embodiments of the invention, the first polyolefin elastomer is copolymerized from ethylene and 2,4,4-trimethyl-1-pentene.

[0016] In some embodiments of the present invention, the carbon number spacing between any two adjacent second side chains on the second main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 7 carbon atoms. In other embodiments of the present invention, the carbon number spacing between any two adjacent second side chains on the second main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 6 carbon atoms. In still other embodiments of the present invention, the carbon number spacing between any two adjacent second side chains on the second main carbon chain is greater than or equal to 3 carbon atoms and less than or equal to 5 carbon atoms.

[0017] In some embodiments of the invention, each of the plurality of second side chains is independently an alkyl group having 2 to 6 carbon atoms. In other embodiments of the invention, each of the plurality of second side chains is independently an alkyl group having 4 to 6 carbon atoms. It should be understood that the melting point of the second polyolefin elastomer is affected by the length (i.e., the number of carbon atoms) of the plurality of second side chains. In some embodiments of the invention, the plurality of second side chains may be n-alkyl groups.

[0018] In some embodiments of the present invention, the melting point of the second polyolefin elastomer is greater than or equal to 60°C and less than or equal to 120°C. In other embodiments of the present invention, the melting point of the second polyolefin elastomer is greater than or equal to 80°C and less than or equal to 120°C. In still other embodiments of the present invention, the melting point of the second polyolefin elastomer is greater than or equal to 90°C and less than or equal to 110°C.

[0019] In some embodiments of the present invention, the second polyolefin elastomer is copolymerized from a third olefin and a fourth olefin, wherein the third olefin has 2 to 5 carbon atoms, and the fourth olefin has 6 to 10 carbon atoms. In other embodiments of the present invention, the second polyolefin elastomer is copolymerized from a third olefin and a fourth olefin, wherein the third olefin has 2 to 4 carbon atoms, and the fourth olefin has 6 to 8 carbon atoms. In other embodiments of the present invention, the second polyolefin elastomer is copolymerized from ethylene and octene. In other embodiments of the present invention, the second polyolefin elastomer is copolymerized from ethylene and isooctene. In other embodiments of the present invention, the second polyolefin elastomer is copolymerized from ethylene and 6-methyl-1-heptene. In other embodiments of the present invention, the second polyolefin elastomer is copolymerized from ethylene and 2,4,4-trimethyl-1-pentene.

[0020] In some embodiments of the present invention, the first polyolefin elastomer and the second polyolefin elastomer are the same. In other embodiments of the present invention, the first polyolefin elastomer and the second polyolefin elastomer are different.

[0021] In some embodiments of the present invention, the ethylene content in the ethylene / vinyl alcohol copolymer is 28 mol% to 50 mol%. In other embodiments of the present invention, the ethylene content in the ethylene / vinyl alcohol copolymer is 28 mol% to 40 mol%. In still other embodiments of the present invention, the ethylene content in the ethylene / vinyl alcohol copolymer is 28 mol% to 35 mol%. In still other embodiments of the present invention, the ethylene content in the ethylene / vinyl alcohol copolymer is 25 mol% to 30 mol%.

[0022] In some embodiments of the present invention, the material of the first adhesive layer comprises a maleic anhydride-grafted polyolefin resin. By selecting a specific type of material, the first adhesive layer provides good adhesion between the heat-sealing layer with lower polarity and the oxygen barrier layer with higher polarity. In other embodiments of the present invention, the material of the first adhesive layer may be a maleic anhydride-modified polyethylene resin.

[0023] In some embodiments of the present invention, the material of the second adhesive layer comprises a maleic anhydride-modified polyolefin resin. By selecting a specific type of material, the second adhesive layer provides good adhesion between the functional surface layer with lower polarity and the oxygen barrier layer with higher polarity. In other embodiments of the present invention, the material of the second adhesive layer may be a maleic anhydride-modified polyethylene resin.

[0024] In some embodiments of the present invention, the material of the heat-sealing layer further comprises a first additive component, which comprises an ethylene / vinyl acetate copolymer, a tackifying resin, or a combination thereof, wherein the content of the first additive component, based on the total weight of the heat-sealing layer, can be from 10 weight percent (wt%) to 60 wt%. In some embodiments of the present invention, the tackifying resin can be C5 petroleum resin or C9 petroleum resin. In other embodiments of the present invention, the tackifying resin can be C5 petroleum resin. The C5 or C9 petroleum resin generally refers to polymers obtained by using C5 or C9 fractions generated during petroleum cracking as raw materials, and then heating and polymerizing them using catalysts such as sulfuric acid, anhydrous aluminum trichloride, and boron trifluoride. By further including a specific type of first additive component in the material of the heat-sealing layer, the sealing strength of the heat-sealing layer after the encapsulation process can be further improved.

[0025] In some embodiments of the present invention, the material of the heat-sealing layer further includes a first additive component comprising an ethylene / vinyl acetate copolymer, wherein the content of the ethylene / vinyl acetate copolymer may be from 10 wt% to 30 wt% based on the total weight of the heat-sealing layer.

[0026] In some embodiments of the present invention, the material of the heat-sealing layer further includes a first additive component, the first additive component including a tackifying resin, wherein the content of the tackifying resin may be from 10 wt% to 25 wt% based on the total weight of the heat-sealing layer.

[0027] In some embodiments of the present invention, the material of the functional surface layer further comprises a second additive component, which comprises polyethylene (PE), polypropylene (PP), or a combination thereof, wherein the content of the second additive component, based on the total weight of the functional surface layer, can be from 10 wt% to 80 wt%. In other embodiments of the present invention, the content of the second additive component, based on the total weight of the functional surface layer, can be from 10 wt% to 50 wt%. In still other embodiments of the present invention, the content of the second additive component, based on the total weight of the functional surface layer, can be from 10 wt% to 30 wt%. By further comprising a specific type of the second additive component in the material of the functional surface layer, the mechanical strength and protective properties of the functional surface layer can be further improved.

[0028] In some embodiments of the present invention, the material of the functional surface layer further comprises a second additive component, the second additive component comprising polyethylene, wherein the polyethylene content is from 10 wt% to 80 wt% based on the total weight of the functional surface layer; in other embodiments of the present invention, the polyethylene content is from 10 wt% to 50 wt% based on the total weight of the functional surface layer; and in still other embodiments of the present invention, the polyethylene content is from 10 wt% to 30 wt% based on the total weight of the functional surface layer.

[0029] In some embodiments of the present invention, the thickness of the solar cell encapsulation composite film is greater than or equal to 30 micrometers (μm) and less than or equal to 500 μm. In other embodiments of the present invention, the thickness of the solar cell encapsulation composite film is greater than or equal to 30 μm and less than or equal to 400 μm. In other embodiments of the present invention, the thickness of the solar cell encapsulation composite film is greater than or equal to 30 μm and less than or equal to 280 μm. In other embodiments of the present invention, the thickness of the solar cell encapsulation composite film is greater than or equal to 30 μm and less than or equal to 100 μm. The thickness of the solar cell encapsulation composite film is greater than or equal to 30 μm and less than or equal to 60 μm.

[0030] In some embodiments of the present invention, the thickness of the heat-sealing layer may be from 5 μm to 25 μm. In other embodiments of the present invention, the thickness of the heat-sealing layer may be from 5 μm to 20 μm. In still other embodiments of the present invention, the thickness of the heat-sealing layer may be from 5 μm to 15 μm.

[0031] In some embodiments of the present invention, the thickness of the first adhesive layer may be from 1 μm to 10 μm. In other embodiments of the present invention, the thickness of the first adhesive layer may be from 1 μm to 5 μm.

[0032] In some embodiments of the present invention, the thickness of the oxygen barrier layer may be from 1 μm to 10 μm. In other embodiments of the present invention, the thickness of the oxygen barrier layer may be from 2 μm to 8 μm. In still other embodiments of the present invention, the thickness of the oxygen barrier layer may be from 2 μm to 6 μm.

[0033] In some embodiments of the present invention, the thickness of the second adhesive layer may be from 1 μm to 10 μm. In other embodiments of the present invention, the thickness of the second adhesive layer may be from 1 μm to 5 μm.

[0034] In some embodiments of the present invention, the thickness of the functional surface layer may be from 10 μm to 30 μm. In other embodiments of the present invention, the thickness of the functional surface layer may be from 10 μm to 25 μm. In still other embodiments of the present invention, the thickness of the functional surface layer may be from 10 μm to 20 μm.

[0035] In some embodiments of the present invention, the solar cell encapsulation composite film may be a five-layer composite film, namely, composed of the heat-sealing layer, the first adhesive layer, the oxygen barrier layer, the second adhesive layer, and the functional surface layer. In other embodiments of the present invention, the solar cell encapsulation composite film may be a composite film with more than five layers. For example, in addition to the aforementioned five-layer basic structure, without affecting the effectiveness achieved by the present invention, the solar cell encapsulation composite film may also include multiple layers of other oxygen barrier layers identical to the oxygen barrier layer, or multiple layers of other functional surface layers identical to the functional surface layer, but is not limited thereto.

[0036] In some embodiments of the present invention, the oxygen barrier capacity of the solar cell encapsulation composite film is less than or equal to 0.5 cubic centimeters per square meter per day. 3 / m 2 In other embodiments of the present invention, the oxygen barrier capacity of the solar cell encapsulation composite film is 0.1 cm per day. 3 / m 2 Up to 0.5 cm per day 3 / m 2 In other embodiments of the present invention, the oxygen barrier capacity of the solar cell encapsulation composite film is 0.1 cm per day. 3 / m 2 Up to 0.4 cm per day 3 / m 2 Specifically, the oxygen barrier capability refers to the total volume of oxygen that the solar cell encapsulation composite film can block on one side from passing through to the other side, and the oxygen barrier capability of the solar cell encapsulation composite film is tested under the conditions of an ambient temperature of about 20°C and an ambient relative humidity (RH) of about 65%.

[0037] In some embodiments of the present invention, the water-blocking capacity of the solar cell encapsulation composite film is less than or equal to 5 grams per square meter per day (g / m²). 2 In other embodiments of the present invention, the water-blocking capacity of the solar cell encapsulation composite film is 0.5 g / m³ per day. 2 Up to 5 g / m daily 2 In other embodiments of the present invention, the water-blocking capacity of the solar cell encapsulation composite film is 2 g / m³ per day. 2 Up to 5 g / m daily 2Specifically, the water-blocking capability refers to the total weight of water vapor that the solar cell encapsulation composite film can block on one side without passing through to the other side, and the water-blocking capability of the solar cell encapsulation composite film is tested under the conditions of an ambient temperature of approximately 38°C and an ambient relative humidity of approximately 90%.

[0038] In some embodiments of the present invention, the average transmittance of the solar cell encapsulation composite film in the visible light region (i.e., the range of light wavelengths from approximately 380 nm to 750 nm) is greater than 80%. In other embodiments of the present invention, the average transmittance of the solar cell encapsulation composite film in the visible light region is greater than or equal to 82% and less than or equal to 95%.

[0039] In addition, the present invention provides a low-temperature encapsulation method for solar cells, comprising the following steps: step (a): providing a solar cell module, and then sandwiching the solar cell module between two encapsulation films to obtain a stack, wherein the two encapsulation films are the aforementioned solar cell encapsulation composite films of the present invention; and step (b): performing a hot-press encapsulation process on the stack to complete the encapsulation of the solar cell module, wherein the heating temperature of the hot-press encapsulation process is less than 85°C.

[0040] By selecting the aforementioned solar cell encapsulation composite film of the present invention as the encapsulation material, the encapsulation process of the solar cell module (e.g., a perovskite solar cell module) can be completed at a low temperature of less than 85°C. Therefore, if the solar cell is a perovskite solar cell, it will not affect the organic carriers (thermally stable temperature below 85°C) used as the transport material. Thus, while improving stability through a low-temperature encapsulation process, the encapsulated perovskite solar cell can still have a photoelectric conversion efficiency similar to that before encapsulation. At the same time, since the solar cell encapsulation composite film of the present invention itself is flexible and adaptable, and also has good oxygen barrier and water barrier properties, it is not necessary to use rigid glass in the encapsulation process. Therefore, the encapsulated perovskite solar cell can maintain its flexible or adaptable properties.

[0041] In some embodiments of the present invention, in step (b), the heating temperature of the thermopressing encapsulation process is less than or equal to 80°C. In other embodiments of the present invention, in step (b), the heating temperature of the thermopressing encapsulation process is greater than or equal to 70°C and less than or equal to 80°C. It should be understood that the heating temperature of the thermopressing encapsulation process is determined based on the softening temperature of the selected encapsulation material (or encapsulation film).

[0042] In some embodiments of the present invention, the heating time for the thermoforming encapsulation process in step (b) is 5 to 30 minutes. In other embodiments of the present invention, the heating time for the thermoforming encapsulation process in step (b) is 10 to 20 minutes.

[0043] In some embodiments of the present invention, in step (a), the solar cell module includes a substrate, a carrier transport layer, a perovskite layer, a hole transport layer and a back electrode, wherein the carrier transport layer, the perovskite layer, the hole transport layer and the back electrode are respectively stacked sequentially on the surface of the substrate.

[0044] In some embodiments of the present invention, the substrate is transparent and has good conductivity, and therefore can be used as an electrode. The substrate can be prepared by coating a transparent conductive oxide film onto a substrate, wherein the conductive oxide can be tin dioxide (SnO2) doped with fluorine (F) (called fluorine-doped tin oxide, FTO) or indium tin oxide (called indium tin oxide, ITO), but is not limited thereto.

[0045] According to the present invention, the material of the carrier transport layer is not particularly limited, and those skilled in the art can select and adjust it according to actual needs without affecting the effectiveness of the present invention. In some embodiments of the present invention, the material of the carrier transport layer may be titanium dioxide (TiO2), tin dioxide, or methyl [6,6]-phenylcarbon-61-butyrate ([6,6]-phenyl-C... 61 -butyric acid methyl ester (PCBM), zinc monoxide (ZnO), or combinations thereof, but not limited thereto.

[0046] According to the present invention, the material of the perovskite layer is not particularly limited, and those skilled in the art can select and adjust it according to actual needs without affecting the effectiveness of the present invention. In some embodiments of the present invention, the material of the perovskite layer may be methylammonium lead iodide (MAPbI3), formamidinium lead iodide (FAPbI3), or a combination thereof, but is not limited thereto.

[0047] According to the present invention, the material of the hole transport layer is not particularly limited, and those skilled in the art can select and adjust it according to actual needs without affecting the effectiveness of the present invention. In some embodiments of the present invention, the material of the hole transport layer may be 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), copper thiocyanate (CuSCN), nickel oxide (NiO), or a combination thereof, but is not limited thereto.

[0048] In some embodiments of the present invention, the material of the back electrode may be a metal commonly used to make electrodes, such as gold (Au) or silver (Ag), but is not limited thereto.

[0049] In this specification, the range represented by "smallest value to largest value" means, unless otherwise specified, that the range is greater than or equal to the smallest value and less than or equal to the largest value. For example, a carbon number of 2 to 8 means that the range of carbon numbers is "greater than or equal to 2 and less than or equal to 8". Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the solar cell encapsulation composite film of the present invention. Detailed Implementation

[0051] The following examples and comparative examples are provided to illustrate the implementation of the present invention. Those skilled in the art can easily understand the advantages and effects of the present invention through the content of this specification, and can make various modifications and changes without departing from the spirit of the present invention to implement or apply the content of the present invention.

[0052] Please see Figure 1 The solar cell encapsulation composite film 1 of the present invention includes a heat-sealing layer 11, a first adhesive layer 12, an oxygen barrier layer 13, a second adhesive layer 14, and a functional surface layer 15. The first adhesive layer 12 is disposed on the surface of the heat-sealing layer 11, the oxygen barrier layer 13 is disposed on the surface of the first adhesive layer 12, the second adhesive layer 14 is disposed on the surface of the oxygen barrier layer 13, and the functional surface layer 15 is disposed on the surface of the second adhesive layer 14.

[0053] Examples 1 to 6: Solar Cell Encapsulation Composite Film

[0054] The preparation process of the solar cell encapsulation composite film in Examples 1 to 6 is as follows: First, prepare the materials of each of the five layers according to the components listed in Table 1 below. Then, put the materials of the five layers into a multilayer co-extrusion blown film machine and directly co-extrude blown film to obtain a composite film with a five-layer structure, which is the solar cell encapsulation composite film in Examples 1 to 6.

[0055] In Table 1, ENGAGE ™ 8480 POE (i.e., ENGAGE) ™ 8480 (polyolefin elastomer) is a polyolefin elastomer copolymerized from ethylene and octene, with a melting point of approximately 99°C; ENGAGE ™ 8540 POE (i.e., ENGAGE) ™ 8540 polyolefin elastomer is a polyolefin elastomer copolymerized from ethylene and octene, with a melting point of approximately 104°C; EVA is short for ethylene / vinyl acetate copolymer, trade name EVATHENE; EVOH is short for ethylene / vinyl alcohol copolymer, trade name EVASIN; maleic anhydride modified polyolefin resin, trade name anhydride modified linear low-density polyethylene polymer (LLDPE); polyethylene, trade name TAISOX, with a melting point of approximately 160°C to 165°C; and polypropylene, trade name YUNGSOX, with a melting point of approximately 120°C to 130°C.

[0056] In the solar cell encapsulation composite films of Examples 1 to 6, the thickness of the heat-sealing layer is 10 μm, the thickness of the first adhesive layer is 3 μm, the thickness of the oxygen barrier layer is 4 μm, the thickness of the second adhesive layer is 3 μm, and the thickness of the functional surface layer is 20 μm.

[0057] Comparative Examples 1 and 2: Solar Cell Encapsulation Composite Film

[0058] The preparation process of the solar cell encapsulation composite film of Comparative Examples 1 and 2 is as follows: First, prepare the materials of each of the five layers according to the components listed in Table 1 below. Then, put the materials of the five layers into a multilayer co-extrusion blown film machine and directly co-extrude blown film to obtain a composite film with a five-layer structure, which is the solar cell encapsulation composite film of Comparative Examples 1 and 2.

[0059] In the solar cell encapsulation composite films of Comparative Examples 1 and 2, the thickness of the heat-sealing layer is 25 μm, the thickness of the first adhesive layer is 5 μm, the thickness of the oxygen barrier layer is 10 μm, the thickness of the second adhesive layer is 5 μm, and the thickness of the functional surface layer is 25 μm.

[0060] Table 1: Composition of each layer of the solar cell encapsulation composite film in Examples 1 to 6 and Comparative Examples 1 and 2

[0061]

[0062] Example 1A: Solar Cell Packaging Process

[0063] A solar cell module is provided, and then the solar cell module is sandwiched between two encapsulation films to obtain a stack, wherein the two encapsulation films are the solar cell encapsulation composite films of Example 1. Next, a hot-press encapsulation process is performed on the stack, which is heated at a temperature of 80°C (i.e., the encapsulation operation temperature) for about 5 to 30 minutes to complete the encapsulation process of the solar cell module and obtain a solar cell encapsulated with the solar cell encapsulation composite film of Example 1, which is referred to below as "the solar cell of Example 1A". The solar cell module comprises a substrate, a carrier transport layer, a perovskite layer, a hole transport layer, and a back electrode, wherein the carrier transport layer, the perovskite layer, the hole transport layer, and the back electrode are sequentially stacked on the surface of the substrate; wherein the substrate is an FTO (fluorine-doped tin oxide) conductive substrate (manufacturer: Dyesol; trade name: 2.2mm conductive glass), the material of the carrier transport layer is titanium dioxide, the material of the perovskite layer is MAPbI3, the material of the hole transport layer is Spiro-OMeTAD, and the material of the back electrode is gold.

[0064] Examples 2A to 6A: Solar Cell Packaging Process

[0065] The processes of Examples 2A to 6A are similar to those of Example 1A, except that Examples 2A to 6A each use the solar cell encapsulation composite film of Examples 2 to 6 respectively. All other processes are carried out in accordance with Example 1A to complete the encapsulation process of the solar cell module and obtain solar cells encapsulated with the solar cell encapsulation composite film of Examples 2 to 6 respectively, which will be referred to as "solar cells of Examples 2A to 6A" below.

[0066] Comparative Examples 1A and 2A: Solar Cell Packaging Process

[0067] The processes of Comparative Examples 1A and 2A are similar to those of Example 1A, with the main difference being that Comparative Examples 1A and 2A respectively use the solar cell encapsulation composite films of Comparative Examples 1 and 2, and the temperature for the hot-press encapsulation process in Comparative Example 1A is 130°C, while the temperature for the hot-press encapsulation process in Comparative Example 2A is 100°C. All other processes are performed according to Example 1A to complete the encapsulation process of the solar cell module, resulting in solar cells encapsulated with the solar cell encapsulation composite films of Comparative Examples 1 and 2, respectively, which will be referred to below as "solar cells of Comparative Examples 1A and 2A".

[0068] Experimental Example 1: Characteristic Analysis of Composite Films for Solar Cell Encapsulation

[0069] (1) Oxygen barrier capacity

[0070] The oxygen barrier capacity of solar cells from Examples 1A to 6A and Comparative Examples 1A and 2A was tested. Specifically, these solar cells were placed in an environment with a temperature of approximately 20°C and a relative humidity of approximately 65%, and their oxygen barrier capacity was determined using an oxygen flow rate tester (manufacturer: MOCON, Inc.; model: OX-TRAN Model 2 / 61) according to the ASTM D3985 standard test method. The oxygen barrier capacity was evaluated based on the volume of oxygen blocked per square meter of composite film per day; a higher measured volume of blocked oxygen indicated better oxygen barrier capacity. The oxygen barrier capacity test results for the solar cells from Examples 1A to 6A and Comparative Examples 1A and 2A are listed in Table 2 below, with units expressed in cubic centimeters per square meter (cm²). 3 / m 2 )express.

[0071] (2) Water resistance

[0072] The water-blocking ability of solar cells from Examples 1A to 6A and Comparative Examples 1A and 2A was tested. Specifically, these solar cells were placed in an environment with a temperature of approximately 38°C and a relative humidity of approximately 90%, and their water-blocking ability was measured using a water vapor transmission rate tester (manufacturer: MOCON, Inc.; model: Aquatran Model 2) according to the ASTM F3299 standard test method. The water-blocking ability was evaluated based on the weight of water vapor that the composite film could block per square meter per day. The greater the weight of water vapor blocked, the better the water-blocking ability. The water-blocking ability test results of the solar cells from Examples 1A to 6A and Comparative Examples 1A and 2A are listed in Table 2 below, with the unit being grams per square meter (g / m²). 2 )express.

[0073] Table 2: Results of oxygen barrier and water barrier capacity measurements of solar cells in Examples 1A to 6A and Comparative Examples 1A and 2A

[0074]

[0075] As can be seen from the results in Table 2 above, since Comparative Examples 1A and 2A respectively use existing thermoplastic organic materials (i.e., polyethylene and polypropylene) as encapsulation materials, their oxygen barrier and water barrier capabilities can be regarded as the standard for improving the stability of the encapsulated solar cells. The oxygen barrier and water barrier capabilities of Examples 1A to 6A are comparable to those of Comparative Examples 1A and 2A. This proves that when the solar cell encapsulation composite film of Examples 1 to 6 is used as the encapsulation material, the encapsulation can be carried out at low temperature and the same effect of improving the stability of the encapsulated solar cells can be achieved.

[0076] (3) Light transmittance

[0077] The solar cell encapsulation composite films of Examples 1 to 6 and Comparative Examples 1 and 2 were selected for transmittance testing. Specifically, an ultraviolet-visible (UV-Vis) spectrometer (manufacturer: Hitachi, Ltd., model: U3900) was used. The solar cell encapsulation composite films of these groups were placed in the center of the light source and the detector, and air was used as the background value. The transmittance of each group after subtracting the background value was measured to obtain the average transmittance of the solar cell encapsulation composite films of these groups in the visible light region. The measurement results of the average transmittance of the solar cell encapsulation composite films of Examples 1 to 6 and Comparative Examples 1 and 2 in the visible light region are listed in Table 3 below, and the units are expressed as percentages (%).

[0078] Table 3: Results of average transmittance measurement of solar cell encapsulation composite films in the visible light region for Examples 1 to 6 and Comparative Examples 1 and 2

[0079]

[0080] As can be seen from the results in Table 3 above, the average transmittance of the solar cell encapsulation composite films of Examples 1 to 6 in the visible light region is greater than 80%, and the results are quite similar to those of the solar cell encapsulation composite films of Comparative Examples 1 and 2 (which respectively used existing thermoplastic organic materials as encapsulation materials). Therefore, it can be concluded that when the solar cell encapsulation composite films of Examples 1 to 6 are used as encapsulation materials, they do not hinder the reception of light sources by the encapsulated solar cells.

[0081] Experimental Example 2: Performance Analysis of Solar Cells

[0082] (1) Power conversion efficiency (PCE)

[0083] This experiment followed the procedures of Examples 1A to 6A and Comparative Examples 1A and 2A to perform a packaging process on perovskite solar cells (i.e., perovskite solar cell modules), and measured the photoelectric conversion efficiency (PCE) of the solar cells at different stages during the process. Specifically, before the packaging process, the PCE of each group of solar cells was measured. After completing the packaging process according to Examples 1A to 6A and Comparative Examples 1A and 2A, the PCE of each group of packaged solar cells was measured again. Furthermore, based on the PCE results measured at different time points or stages, the degree of PCE degradation can be further calculated, which represents the impact of different times or stages on the PCE of the solar cells. For example, measuring the PCE of the solar cells before and after packaging, and further calculating the degree of PCE degradation after packaging, can represent the impact of the packaging process on the PCE of the solar cells. The photoelectric conversion efficiency was determined by placing different groups of solar cells in an environment with a temperature of approximately 25°C and a relative humidity of approximately 70%. A solar simulator (manufacturer: Peccell Technologies, Inc.; model: PEC-L01) was used, and a calibration plate (manufacturer: Bunkoukeiki Co., Ltd.; model: BS-520 S / N 153 spectrometer) was used to calibrate the light source to obtain a standard solar spectrum as the test light source. A Keithley 2400 power meter was then connected to the positive and negative terminals of the solar cells to be tested to obtain the current-voltage curves (IV curves) for different groups. The maximum power point (i.e., maximum power output) on the IV curve was then taken as the numerator, and the incident light power was taken as the denominator. The result was divided and expressed as a percentage to obtain the photoelectric conversion efficiency. The calculation method for the degree of photoelectric conversion efficiency degradation is: (first measured photoelectric conversion efficiency - second measured photoelectric conversion efficiency) / first measured photoelectric conversion efficiency × 100%; taking the degree of photoelectric conversion efficiency degradation before and after the packaging process as an example, the calculation method is: (photoelectric conversion efficiency before packaging - photoelectric conversion efficiency before packaging) / photoelectric conversion efficiency before packaging × 100%. The results of the photoelectric conversion efficiency before packaging, photoelectric conversion efficiency after packaging, and degree of photoelectric conversion efficiency degradation after packaging measured in Examples 1A to 6A and Comparative Examples 1A and 2A are listed in Table 4 below; in addition, Table 4 also lists the operating temperature during the packaging process of Examples 1A to 6A and Comparative Examples 1A and 2A.

[0084] (2) Stability

[0085] This experiment continued the above-mentioned (1) photoelectric conversion efficiency test procedure. The encapsulated solar cells of Examples 1A to 6A and Comparative Examples 1A and 2A were placed under an ambient temperature of approximately 25°C and an ambient relative humidity of approximately 70% for 21 days. Then, the photoelectric conversion efficiency of each group was measured, and the degree of photoelectric conversion efficiency degradation of each group after 21 days was further obtained. At the same time, unencapsulated perovskite solar cells were selected as a control group. Their photoelectric conversion efficiency was measured first, and then they were placed under the same conditions of an ambient temperature of approximately 25°C and an ambient relative humidity of approximately 70% for 21 days. Their photoelectric conversion efficiency was then measured, and the degree of photoelectric conversion efficiency degradation of each group after 21 days was further obtained. The results of the photoelectric conversion efficiency degradation after 21 days for Examples 1A to 6A and Comparative Examples 1A and 2A are listed in Table 4 below. The results of the photoelectric conversion efficiency and the degree of photoelectric conversion efficiency degradation after 21 days for the unencapsulated group are also listed in Table 4 below, which are marked as the control group.

[0086] Table 4: Packaging operation temperature, photoelectric conversion efficiency before packaging, photoelectric conversion efficiency after packaging, photoelectric conversion efficiency degradation after packaging, and photoelectric conversion efficiency degradation after 21 days for Examples 1A to 6A and Comparative Examples 1A and 2A, as well as the photoelectric conversion efficiency of the unpackaged group and the photoelectric conversion efficiency degradation after 21 days.

[0087]

[0088] As shown in Table 4 above, the photoelectric conversion efficiency of each group before encapsulation was approximately 12.7% to 13.8%, meaning that the photoelectric conversion efficiency of each group was almost the same before encapsulation. However, the photoelectric conversion efficiency of the unencapsulated group decreased by as much as 78.5% after 21 days, indicating that perovskite solar cells cannot maintain a certain level of stability without encapsulation, resulting in a significant drop in photoelectric conversion efficiency. Looking at the results of Comparative Examples 1A and 2A, although the photoelectric conversion efficiency of Comparative Examples 1A and 2A did not increase significantly after 21 days, showing a certain degree of stability, the photoelectric conversion efficiency of the perovskite solar cell after the encapsulation process of Comparative Example 1 dropped sharply from 13.3% to 6.7%, with a photoelectric conversion efficiency degradation of up to 49.6% after encapsulation; and after the encapsulation process of Comparative Example 2, the photoelectric conversion efficiency also dropped sharply from 13.8% to 9.0%, with a photoelectric conversion efficiency degradation of up to 34.8% after encapsulation. It can be seen that because the encapsulation operation temperature used in Comparative Examples 1A and 2A was higher than the thermal stability temperature of the organic carriers used as the transport layer material, the encapsulated perovskite solar cells could not maintain a photoelectric conversion efficiency similar to that before encapsulation. Looking at the results of Examples 1A to 6A, since the encapsulation operation temperature used in Examples 1A to 6A was only 80°C, which did not exceed the thermal stability temperature of the organic carriers used as the transport layer material, the photoelectric conversion efficiency of the perovskite solar cells after the encapsulation process of Examples 1A to 6A was almost the same as before encapsulation, and the photoelectric conversion efficiency degradation of each group after encapsulation was less than 5.5%. At the same time, the photoelectric conversion efficiency degradation of Examples 1A to 6A did not increase significantly after 21 days, and was even less than 10%, which shows that the stability of perovskite solar cells can also be improved after encapsulation according to Examples 1A to 6A.

[0089] Therefore, it can be seen that using the solar cell encapsulation composite film of Examples 1 to 6 as the encapsulation material can indeed achieve the encapsulation process of perovskite solar cells under low temperature conditions (e.g., below 85°C), thereby improving the stability of perovskite solar cells while maintaining their photoelectric conversion efficiency almost the same as before encapsulation.

[0090] In summary, the solar cell encapsulation composite film of the present invention, by selecting multilayer bodies with different functions to form a composite film and controlling the forming materials of specific layers therein, can be applied to the low-temperature (e.g., below 85°C) encapsulation process of perovskite solar cells. Thus, while improving stability through the low-temperature encapsulation process, the encapsulated perovskite solar cell has a photoelectric conversion efficiency similar to that before encapsulation, and can also maintain the flexible or flexible characteristics of the perovskite solar cell, thereby expanding its application range. This is conducive to its subsequent development into commercial products or practical application in urban buildings or general residences, and therefore has considerable development potential and economic benefits.

Claims

1. A perovskite solar cell encapsulation composite film, characterized in that, Include: A heat-sealing layer, the material of which comprises a first polyolefin elastomer, wherein the chemical structure of the first polyolefin elastomer has a first main carbon chain and a plurality of first side chains connected to the first main carbon chain, and each of the plurality of first side chains is independently an alkyl group having 2 to 8 carbon atoms; the material of the heat-sealing layer further comprises a first additive component, the first additive component comprising an ethylene / vinyl acetate copolymer, a tackifying resin, or a combination thereof; the melting point of the first polyolefin elastomer is greater than or equal to 80°C and less than or equal to 120°C; A first adhesive layer is disposed on the surface of the heat-sealing layer, and the material of the first adhesive layer comprises a polyolefin resin modified with maleic anhydride; An oxygen barrier layer is disposed on the surface of the first adhesive layer, wherein the material of the oxygen barrier layer comprises an ethylene / vinyl alcohol copolymer, and the ethylene content in the ethylene / vinyl alcohol copolymer is 25 mole percent to 50 mole percent; A second adhesive layer is disposed on the surface of the oxygen barrier layer, and the material of the second adhesive layer comprises a polyolefin resin modified with maleic anhydride; and A functional surface layer is disposed on the surface of the second adhesive layer, wherein the material of the functional surface layer comprises a second polyolefin elastomer, wherein the chemical structure of the second polyolefin elastomer has a second main carbon chain and a plurality of second side chains connected to the second main carbon chain, and each of the plurality of second side chains is independently an alkyl group having 2 to 8 carbon atoms; the melting point of the second polyolefin elastomer is greater than or equal to 80°C and less than or equal to 160°C.

2. The perovskite solar cell encapsulation composite film as described in claim 1, characterized in that, The material of the functional surface layer also includes a second additive component, which includes polyethylene, polypropylene, or a combination thereof.

3. The perovskite solar cell encapsulation composite film as described in claim 1, characterized in that, The thickness of the perovskite solar cell encapsulation composite film is greater than or equal to 30 micrometers and less than or equal to 500 micrometers.

4. The perovskite solar cell encapsulation composite film as described in claim 1, characterized in that, The oxygen barrier capacity of this perovskite solar cell encapsulation composite film is less than or equal to 0.5 cubic centimeters per square meter per day.

5. The perovskite solar cell encapsulation composite film as described in claim 1, characterized in that, The water-blocking capacity of the perovskite solar cell encapsulation composite film is less than or equal to 5 grams per square meter per day.

6. The perovskite solar cell encapsulation composite film as described in claim 1, characterized in that, The average transmittance of the perovskite solar cell encapsulation composite film in the visible light region is greater than 80%.

7. A low-temperature encapsulation method for perovskite solar cells, characterized in that, Includes the following steps: Step (a): Provide a perovskite solar cell module, and then sandwich the perovskite solar cell module between two encapsulation films to obtain a stack, wherein the two encapsulation films are perovskite solar cell encapsulation composite films as described in any one of claims 1 to 6; and Step (b): Perform a thermo-pressing encapsulation process on the stacked layers to complete the encapsulation of the perovskite solar cell module, wherein the heating temperature of the thermo-pressing encapsulation process is less than 85°C.

8. The low-temperature encapsulation method for perovskite solar cells as described in claim 7, characterized in that, In step (b), the heating temperature of the thermo-pressing encapsulation process is less than or equal to 80°C.

9. The low-temperature encapsulation method for perovskite solar cells as described in claim 7, characterized in that, In step (b), the heating time for the thermo-pressing encapsulation process is 5 to 30 minutes.

10. The low-temperature encapsulation method for perovskite solar cells according to any one of claims 7 to 9, characterized in that, In step (a), the perovskite solar cell module includes a substrate, a carrier transport layer, a perovskite layer, a hole transport layer and a back electrode, wherein the carrier transport layer, the perovskite layer, the hole transport layer and the back electrode are sequentially stacked on the surface of the substrate.

Images