A uv-curable composition, photovoltaic cell containing same and use thereof

Abstract

The application provides a UV curing composition, a photovoltaic cell containing the same and an application thereof. The cured glue point of the UV curing composition is greater than 120 microns; the modulus of the UV curing composition at 120 degrees Celsius is greater than or equal to 8 MPa. By arranging the UV curing composition of the application on the surface of the cell, the UV curing composition can have good support at high temperature, reduce the risk of hard contact between upper and lower cells in the laminated area of the photovoltaic cell, and reduce the hidden cracking rate of the photovoltaic module.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic technology, in particular to a UV curing composition, a photovoltaic cell containing the same and application thereof. BACKGROUND

[0002] A photovoltaic module is usually composed of a plurality of solar cell pieces (referred to as cell pieces) connected in series or parallel. In order to improve the output power of the photovoltaic module, a commonly used method is to use a laminated design, that is, to stack a plurality of cell pieces together and connect them together by soldering with a solder strip. This design can increase the power generation efficiency and power density of the photovoltaic module, thereby improving its energy output efficiency. The laminated technology realizes the negative spacing of the cell pieces by cutting the cell pieces into small pieces and interconnecting them, which can place more cell pieces in the same area, optimize the space utilization, thereby effectively expanding the light receiving area of the cell pieces and improving the absorption and utilization of solar energy. The laminated module adopts a special series-parallel connection structure, which greatly reduces the internal resistance and internal power consumption of the module, so the laminated design is deeply pursued by the market. At the same time, the solar cell piece is a brittle material, and when subjected to external stress or internal stress, the solder strip at the laminated position is in hard contact with the cell piece, which is prone to hidden cracks. The existing solution is to add a buffer layer at the laminated position to relieve stress concentration.

[0003] CN113594302B discloses a photovoltaic module processing method, a photovoltaic module and a glue dropping device. The photovoltaic module processing method comprises the following steps: arranging a plurality of cell pieces in sequence, the cell pieces comprising a single-layer region and a laminated region, and two adjacent cell pieces being placed in a laminated manner in the laminated region; electrically connecting each cell piece to obtain a cell string; and dropping liquid encapsulating material between the laminated regions of two adjacent cell pieces to fill the gap between the laminated regions, thereby providing a buffer effect for the cell pieces in the subsequent lamination process, reducing the risk of hidden cracks in the laminated regions, reducing production costs, simplifying the processing technology of the photovoltaic module, and improving production efficiency. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a UV curing composition, a photovoltaic cell containing the same and application thereof. By arranging the UV curing composition of the present application in the laminated region of the photovoltaic cell piece, the UV curing composition can have good supportability at high temperatures, thereby reducing the risk of hard contact between the upper and lower cell pieces in the laminated region, and thus reducing the hidden crack rate of the photovoltaic module.

[0005] Specifically, the first aspect of the present application provides a UV curing composition for reducing the hidden cracks of a photovoltaic module; the cured glue point height of the UV curing composition is > 120 μm; and the modulus of the UV curing composition at 120 degrees Celsius is ≥ 8 MPa.

[0006] In one or more embodiments, the UV-cured composition has a cured bead height of 120-160 μm.

[0007] In one or more embodiments, the UV-cured composition has a modulus at 120 degrees Celsius of 8-20 MPa or 10 MPa-20 MPa.

[0008] In one or more embodiments, the UV-cured composition has a viscosity at 25 ± 0.2 °C of 15000-45000 cps, such as 20000-40000 cps.

[0009] In one or more embodiments, the UV-cured composition has a thixotropic index at 25 ± 0.2 °C of 3-6, such as 4-5.

[0010] In one or more embodiments, the UV-cured composition has a Shore hardness of greater than or equal to D65, such as D65-D80.

[0011] A second aspect of the present application provides a UV-cured composition for reducing the incidence of microcracking in photovoltaic modules, the UV-cured composition comprising an acrylate-based oligomer, a multifunctional reactive diluent monomer, a photoinitiator, a coupling agent, silica, a dispersant, a light stabilizer, and a surface tension enhancer.

[0012] In one or more embodiments, the UV-cured composition has a cured bead height > 120 μm; and the UV-cured composition has a modulus at 120 degrees Celsius > 8 MPa.

[0013] In one or more embodiments, the UV-cured composition has a cured bead height of 120-160 μm.

[0014] In one or more embodiments, the UV-cured composition has a modulus at 120 degrees Celsius of 8-20 MPa or 10 MPa-20 MPa.

[0015] In one or more embodiments, the UV-cured composition has a viscosity at 25 ± 0.2 °C of 15000-45000 cps, such as 20000-40000 cps.

[0016] In one or more embodiments, the UV-cured composition has a thixotropic index at 25 ± 0.2 °C of 3-6, such as 4-5.

[0017] In one or more embodiments, the UV-cured composition has a Shore hardness of greater than or equal to D65, such as D65-D80.

[0018] In one or more embodiments, the acrylate-based oligomer is an acrylate-based oligomer having a molecular weight of 500-10,000 Da.

[0019] In one or more embodiments, the multifunctional reactive diluent monomer is a compound having a molecular weight of 100-500 Da and containing two or more polymerizable functional groups.

[0020] In one or more embodiments, the photoinitiator is a free radical type photoinitiator.

[0021] In one or more embodiments, the coupling agent is a silane coupling agent.

[0022] In one or more embodiments, the silica has a particle size of 200-500 nm.

[0023] In one or more embodiments, the dispersant is an inorganic colloidal dispersant.

[0024] In one or more embodiments, the light stabilizer is a hindered amine light stabilizer.

[0025] In one or more embodiments, the surface tension enhancer is a hydroxyl-based compound for increasing surface tension.

[0026] In one or more embodiments, the acrylate-based oligomer is one or more of a urethane acrylate, an epoxy acrylate, and a polyester acrylate.

[0027] In one or more embodiments, the multifunctional reactive diluent monomer is one or more of trimethylolpropane triacrylate, diethylene glycol diacrylate, divinylbenzene, and N,N'-methylenebisacrylamide.

[0028] In one or more embodiments, the photoinitiator is one or more of 1-hydroxycyclohexyl phenyl ketone, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, 2-hydroxy-2-methyl- propiophenone, and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide.

[0029] In one or more embodiments, the silane coupling agent is one or more of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxy (ethoxy) silane.

[0030] In one or more embodiments, the silica is fumed silica.

[0031] In one or more embodiments, the dispersant is at least one of a silicate and alumina.

[0032] In one or more embodiments, the light stabilizer is selected from one or more of Tinuvin 123, Tinuvin 292 and Tinuvin 622.

[0033] In one or more embodiments, the surface tension enhancer is selected from one or more of glycol, polyvinyl alcohol and hydroxyethyl methyl cellulose.

[0034] In one or more embodiments, the glycol is selected from ethylene glycol and / or propylene glycol.

[0035] In one or more embodiments, the mass fraction ratio of the acrylate oligomer, the multifunctional reactive diluent monomer, the photoinitiator, the coupling agent, the silica, the dispersant, the light stabilizer and the surface tension enhancer is (50-85):(15-30):(1-3):(0.4-2):(1-3):(0.2-3.5):(0.3-2):(0.3-2).

[0036] The third aspect of the present application provides a UV cured adhesive, which is obtained by curing the UV curing composition as described in any one of the embodiments herein.

[0037] The fourth aspect of the present application provides a photovoltaic cell, which comprises a cell body and the UV curing composition as described in any one of the embodiments herein disposed on the front side or the back side of the cell body.

[0038] In one or more embodiments, the cell is a single crystal silicon cell, a polycrystalline silicon cell or an amorphous silicon cell.

[0039] The fifth aspect of the present application provides a photovoltaic module, which comprises a cell string, the cell string comprising a plurality of photovoltaic cells as described in any one of the embodiments herein stacked, and the UV curing composition as described in any one of the embodiments herein contained between the stacking areas of two adjacent stacked photovoltaic cells.

[0040] In one or more embodiments, the photovoltaic module further comprises a solder ribbon for string soldering connection of the photovoltaic cells; the height of the cured adhesive point of the UV curing composition is greater than or equal to the height of the solder ribbon.

[0041] The sixth aspect of the present application provides the use of a surface tension enhancer in the preparation of a UV curing composition for adjusting the stacking effect of the UV curing composition on a photovoltaic cell; the surface tension enhancer is a hydroxyl compound for increasing surface tension, preferably selected from one or more of glycol, polyvinyl alcohol and hydroxyethyl methyl cellulose.

[0042] The seventh aspect of the present application provides the use of the UV-curable composition as described in any embodiment herein in reducing the rate of hidden cracks of a photovoltaic module.

[0043] The present application has the following advantages: by selecting a surface tension enhancer as an auxiliary agent in the acrylate oligomer system, and further adjusting the amount and ratio of the diluent monomer and silica in the system, a UV-curable composition with a cured glue point height of >120 μm and a high-temperature (120°C) modulus of ≥8 MPa can be obtained, which has good supportability at high temperature, can reduce the risk of hard contact between upper and lower cell sheets in the cell sheet stacking area of the battery sheet, and reduce the hidden cracks of the photovoltaic module. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a cross-sectional schematic diagram after printing of Example 1.

[0045] Figure 2 It is a schematic diagram of front point gluing of Example 1.

[0046] In the figure, 1 represents a cell sheet, 2 represents a glue point (UV-curable composition), 3 represents another cell sheet, and 4 represents a solder strip. DETAILED DESCRIPTION

[0047] In order for those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned herein. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in the event of conflict, the definitions herein shall prevail.

[0048] Theories or mechanisms described and disclosed herein, whether correct or not, should not in any way limit the scope of the present application, i.e. the present application can be practiced without being limited by any particular theory or mechanism.

[0049] In this document, "comprising", "including", "containing", and similar phrases encompass the meanings of "consisting essentially of" and "consisting of", e.g. when this document discloses "A comprising B and C", "A consisting essentially of B and C" and "A consisting of B and C" should be considered to have been disclosed herein.

[0050] In this document, all features defined by numerical ranges or percentage ranges, such as values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0051] In this document, unless otherwise specified, percentages refer to mass percentages, and ratios refer to mass ratios.

[0052] Herein, the description of the embodiments or examples is not intended to limit the present application to these embodiments or examples. Rather, all alternatives, modifications and equivalents of the methods and materials described herein, made in the light of the present application, are to be included within the scope of claims.

[0053] Herein, all possible combinations of the various technical features described in the various embodiments or examples are not described in order to simplify the description. Therefore, the various technical features in the various embodiments or examples can be combined in any manner as long as there is no contradiction, and all possible combinations should be considered as within the scope of the present specification.

[0054] UV curable composition

[0055] One of the purposes of the present application is to provide a UV curable composition for reducing the hidden cracks of photovoltaic modules. The cured spot height of the UV curable composition can be > 120 μm, and the high temperature (at 120°C) modulus can be ≥ 8 MPa, so that it has good support at high temperature, can reduce the risk of hard contact between the upper and lower cell sheet in the cell sheet stacking area, and reduce the hidden crack rate of photovoltaic modules.

[0056] Herein, the cured spot height refers to the maximum dimension of the spot formed by the UV curable composition in the vertical direction after curing, which is usually the distance from the surface of the substrate to the top of the spot. In some embodiments, the UV curable composition can be coated on the surface of the substrate by using a screen printing device, and the cured spot is formed after curing.

[0057] In the present application, the raw materials of the UV curable composition include acrylate oligomers, multifunctional reactive diluent monomers, photoinitiators, coupling agents, silicon dioxide, dispersants, light stabilizers and surface tension enhancers.

[0058] In the present application, the acrylate oligomer can be an acrylate oligomer with a molecular weight of 500-10,000 Da. Exemplary acrylate oligomers include, but are not limited to, polyurethane acrylate (PUA), epoxy acrylate (EA), polyester acrylate, etc. In some embodiments, the acrylate oligomer is selected from at least one of polyurethane acrylate and epoxy acrylate. In some embodiments, the epoxy acrylate can be an epoxy diacrylate resin oligomer, such as E51 epoxy diacrylate resin oligomer. In some embodiments, the polyester acrylate can be a polyurethane acrylate containing one, two or more acrylate groups, such as a difunctional polyurethane acrylate (a polyurethane acrylate containing two acrylate groups).

[0059] In the present invention, the multifunctional reactive diluent monomer is a low molecular weight (e.g., 100-500 Da) compound having two or more polymerizable functional groups in the molecule. Exemplary polymerizable functional groups include, but are not limited to, acrylate, methacrylate, vinyl ether, acrylamide, vinyl benzene, and the like. In some embodiments, the multifunctional reactive diluent monomer is selected from one or more of trimethylolpropane triacrylate (TMPTA), diethylene glycol dimethacrylate (DEGDM), divinyl benzene (DVB), and N,N'-methylenebisacrylamide (MBAAm).

[0060] In the present invention, the photoinitiator can be a free radical type photoinitiator. The free radical type photoinitiator can include a cleavage type photoinitiator and a hydrogen abstraction type photoinitiator. In some embodiments, the photoinitiator is a cleavage type photoinitiator. In some particular embodiments, the photoinitiator is selected from one or more of 1-hydroxycyclohexyl phenyl ketone, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, 2-hydroxy-2-methyl-phenylpropanone, and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide.

[0061] In the present invention, the coupling agent can be a silane coupling agent, which can be represented by the structural formula Y-R-SiX3, wherein Y is an organic functional group, R is an alkylene group, and X is an alkoxy group. In some embodiments, Y is an amino group, an alkoxy group, a vinyl group, an epoxy group, an epoxy alkoxy group, or a mercapto group. In some embodiments, R is a C 1-10 alkylene group or a C 1-3 alkylene group. In some embodiments, X is a C 1-10 alkoxy group or a C 1-3 alkoxy group. The silane coupling agent is one or more of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxy (ethoxy) silane.

[0062] In the present invention, the silica is used to thicken and adjust the thixotropic index, to improve the toughness and wear resistance of the coated film, and the inorganic nanoparticles adjust the visibility to the naked eye by diffusing some of the incident light, without losing transparency. In some embodiments, the silica has a particle size of about 200-500 nm. Preferably, the silica is fumed silica.

[0063] In the present invention, the dispersant can be an inorganic colloidal dispersant. Exemplary inorganic colloidal dispersants include, but are not limited to, silicates, aluminum oxides, and the like.

[0064] In the present invention, the light stabilizer can be a hindered amine light stabilizer. Exemplary light stabilizers include, but are not limited to, at least one selected from the group consisting of Tinuvin 123, Tinuvin 292, and Tinuvin 622 (all available from BASF Corporation).

[0065] In the present invention, the surface tension enhancer can be a hydroxyl-based compound for increasing surface tension, such as one or more selected from the group consisting of glycol, polyvinyl alcohol, and hydroxyethyl methyl cellulose. In some embodiments, the glycol is selected from the group consisting of ethylene glycol and / or propylene glycol. The inventors have found that by selecting these surface tension increasing aids, a UV-cured composition having a stack height greater than 120 μιη and a high temperature (120°C) modulus greater than or equal to 8 MPa can be obtained, so that the stack height effect of the glue on the cell sheet can be adjusted, and the glue height can be adjusted to follow the solder strip height; thereby reducing the hidden cracking rate of the photovoltaic module.

[0066] In some embodiments, the mass fraction ratio of the acrylate oligomer to the multifunctional reactive diluent monomer is (50-85):(15-30), such as (60-80):(20-25).

[0067] In some embodiments, the mass fraction ratio of the acrylate oligomer to the photoinitiator is (50-85):(1-3), such as (60-80):(0.5-2).

[0068] In some embodiments, the mass fraction ratio of the acrylate oligomer to the silane coupling agent is (50-85):(0.4-2), such as (60-80):(0.5-1.5).

[0069] In some embodiments, the mass fraction ratio of the acrylate oligomer to the fumed silica is (50-85):(1-3), such as (60-80):(1.5-2.5).

[0070] In some embodiments, the mass fraction ratio of the acrylate oligomer to the dispersant is (50-85):(0.2-3.5), such as (60-80):(0.3-2) or (50-85):(0.2-2.5).

[0071] In some embodiments, the mass fraction ratio of the acrylate oligomer to the light stabilizer is (50-85):(0.3-2), such as (60-80):(0.5-1.5).

[0072] In some embodiments, the mass fraction ratio of the acrylate oligomer to other aids is (50-85):(0.3-2), such as (50-85):(0.5-1.5).

[0073] In the present invention, the high temperature modulus (modulus at 120 degrees Celsius) of the cured composition can be > 8 MPa, such as 8-20 MPa, 10-20 MPa, or 10-17 MPa.

[0074] In the present invention, the cured gel point height of the cured composition is > 120 μm, such as 120-160 μm, and further such as 120-155 μm or 145-160 μm.

[0075] In some embodiments, the viscosity of the cured composition at 25 ± 0.2 °C can be 15000-45000 cps, such as 20000-40000 cps.

[0076] In some embodiments, the thixotropic index of the cured composition at 25 ± 0.2 °C can be 3-6, such as 4-5.

[0077] In some embodiments, the Shore hardness of the cured composition can be > D65, such as D65-D80. Herein, D65 means that the hardness value is 65 as measured using a D-type durometer of a Shore durometer. D80 means that the hardness value is 80 as measured using a D-type durometer of a Shore durometer.

[0078] In some embodiments, the raw materials of the UV-cured composition include E51 epoxy bis-acrylate resin oligomer, divinyl benzene, 1-hydroxycyclohexyl phenyl ketone, gamma-aminopropyl triethoxysilane, fumed silica, silicate, Tinuvin 123, and ethylene glycol.

[0079] In some embodiments, the raw materials of the UV-cured composition include E51 epoxy bis-acrylate resin oligomer, trimethylolpropane triacrylate, 1-hydroxycyclohexyl phenyl ketone, gamma-glycidoxypropyltrimethoxysilane, fumed silica (300 μm), silicate, Tinuvin 123, and polyvinyl alcohol.

[0080] In some embodiments, the raw materials of the UV-cured composition include E51 epoxy bis-acrylate resin oligomer, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, gamma-glycidoxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and propylene glycol.

[0081] In some embodiments, the raw materials of the UV-cured composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, gamma-glycidoxypropyltrimethoxysilane, fumed silica, silicate, Tinuvin 123, and ethylene glycol.

[0082] In some embodiments, the raw materials of the UV-curable composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl- diphenylphosphine oxide, gamma-glycidoxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and ethylene glycol.

[0083] In some embodiments, the raw materials of the UV-curable composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl- diphenylphosphine oxide, gamma-glycidoxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and hydroxyethyl methyl cellulose.

[0084] In some embodiments, the raw materials of the UV-curable composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl- diphenylphosphine oxide, gamma-glycidoxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and ethylene glycol.

[0085] Method for preparing a UV-curable composition

[0086] The present application provides a method for preparing a UV-curable composition, which can include the following steps: mixing multifunctional reactive diluent monomer, photoinitiator, coupling agent, silica, dispersant, light stabilizer, and the surface tension enhancer described herein in a certain proportion to obtain a first mixture; and then mixing the first mixture with acrylate oligomer until completely dissolved to obtain the UV-curable composition.

[0087] In some embodiments, the first mixture can be obtained by ball milling and grinding, etc. The operating conditions for mixing are not particularly limited, as long as the first mixture is mixed until uniform. The rotational speed of the exemplary ball milling is 1000-1500 r / min, and the mixing time is 5-10 min. After grinding, the first mixture has a doctor blade fineness of ≤15 um.

[0088] In some embodiments, the manner of the second mixing is not particularly limited, and generally the first mixture can be mixed with the acrylate oligomer together. If necessary, the mixture of the first mixture and the acrylate oligomer can be slightly heated (e.g., 80-100°C) until completely dissolved.

[0089] The obtained UV-curable composition can be stored in a desiccator in the dark, and after light curing, a gel-like UV-curable composition (which can be referred to as a UV-cured gel) is obtained. The light curing can be performed in a UV-curing box. Exemplary light source parameter conditions can be a wavelength of 200-400 nm, such as 300-380 nm, and an energy value of 2000-4000 mj / cm 2 , such as 2500-3500 mj / cm 2 .

[0090] After light curing, the cured gel point height of the UV-cured composition can be greater than 120 pm, such as 120-160 pm, further such as 120-155 pm or 145-160 pm. The high temperature modulus of the cured composition can be > 8 MPa, such as 8-20 MPa, 10 MPa-20 MPa, or 10-17 MPa. The Shore hardness of the cured composition can be > D65, such as D65-D80.

[0091] Photovoltaic cell

[0092] Accordingly, the present application provides a photovoltaic cell comprising a cell body and the UV-cured composition described herein disposed on the front side or back side of the cell body.

[0093] Suitable cell bodies for use in the present application include, but are not limited to, single crystalline silicon cells, polycrystalline silicon cells, or amorphous silicon cells. Single crystalline silicon cells include, but are not limited to, back contact crystalline silicon photovoltaic cells (BC cells) and the like. Suitable BC cells for use in the present application include, but are not limited to, IBC (interdigitated back contact) cells, TBC (tunnel oxide passivated back contact) cells, HBC (heterojunction back contact crystalline silicon cell) cells, and the like.

[0094] The present application also provides a method of making the above photovoltaic cell, which can comprise the following steps:

[0095] The UV-cured composition is coated on the front side or back side edge of the cell body, and then cured.

[0096] In the present application, the coating method can employ one or more of screen printing, dot printing, coating, sputtering, and spraying processes. In some embodiments, the coating method is screen printing.

[0097] After coating, the cell can be placed in a UV-curing box for light curing. In some embodiments, the light source parameter conditions for light curing can be a wavelength of 200-400 nm, such as 300-380 nm, and an energy value of 2000-4000 mj / cm 2 , such as 2500-3500 mj / cm 2 .

[0098] After curing, a cell containing the UV-cured composition described herein (i.e. of the insulating layer) is obtained. After curing, the height of the glue point of the UV-cured composition is greater than 120 μm, for example 120-160 μm, 120-155 μm or 145-160 μm.

[0099] Photovoltaic module

[0100] Therefore, the present application also provides a photovoltaic module, which comprises a cell string; the cell string comprises a plurality of cell pieces arranged in a stack; the UV-cured composition described herein is contained between the lamination areas of two adjacent cell pieces arranged in a stack.

[0101] In some embodiments, the height of the glue point of the UV-cured composition is greater than 120 μm, for example 120-160 μm, 120-155 μm or 145-160 μm.

[0102] In some embodiments, the width of the UV-cured composition can be ≤ the cell piece lamination spacing, for example 0.02-1 mm or 0.03-0.06 mm.

[0103] In some embodiments, the photovoltaic module further comprises a solder ribbon, which is used for string connection of the cell pieces. In some embodiments, the height of the cured glue point of the UV-cured composition can be greater than or equal to the height of the solder ribbons on both sides, so as to achieve the purpose of replacing the solder ribbons with the glue point for buffering. Generally, the height of the solder ribbon here refers to the height of the flattened solder ribbon, i.e. when a conventional round or square solder ribbon (a conductive material used for string connection of solar cell pieces) is used for string connection of the cell pieces, it is flattened by mechanical pressing or rolling, so that its thickness is reduced and its width is increased, forming a flat solder ribbon.

[0104] The present application also provides a method for preparing a photovoltaic module, which comprises: arranging the cell piece containing the UV-cured composition described above in a stack, and then using a solder ribbon to perform string connection and lamination of the photovoltaic cell pieces arranged in a stack.

[0105] In the present application, the arrangement in a stack can be conventional in the art. The cell pieces arranged in a stack comprise a single layer area and a lamination area, and two adjacent cell pieces are arranged in a stack in the lamination area. The UV-cured composition of the present application can be arranged at the lamination area of the two adjacent cell pieces, for example at the edge of the cell piece (which can be as shown in the figure). Figure 1

[0106] Use

[0107] ​In some embodiments, the present application provides the use of a surface tension enhancer in the preparation of a UV-curable composition for achieving the effect of adjusting the stacking height of the UV-curable composition on a photovoltaic cell; preferably the surface tension enhancer is a hydroxyl compound for increasing the surface tension, more preferably one or more selected from dihydric alcohol, polyvinyl alcohol and hydroxyethyl methyl cellulose.

[0108] In some embodiments, the present application also provides the use of a UV-curable composition as described herein in reducing the rate of hidden cracks of a photovoltaic module.

[0109] The present application will be described in detail below with specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present application. The methods, reagents and materials used in the examples are conventional in the art unless otherwise specified. The raw material compounds in the examples can be purchased through commercial channels.

[0110] Example 1

[0111] S1, 20 parts by mass of divinylbenzene, 0.5 parts by mass of 1-hydroxycyclohexyl phenyl ketone, 0.5 parts by mass of γ-aminopropyl triethoxysilane, 2.5 parts by mass of fumed silica, 0.5 parts by mass of silicate, 0.5 parts by mass of Tinuvin 123 and 0.5 parts by mass of ethylene glycol are mixed uniformly and then put into a ball mill for mixing at a speed of 1000 r / min-1500 r / min for 5 min-10 min, and ground to a scraper fineness of ≤15 um to obtain a first mixture.

[0112] S2, the first mixture is mixed with 70 parts by mass of E51 epoxy diacrylate resin oligomer in a watch glass to obtain a UV-curable composition, i.e. glue, which is stored in a desiccator in the dark for light curing.

[0113] S3, the UV-curable composition obtained in step S2 is coated on the edge of the front or back of the cell by a screen printing device according to the cell pattern, and after printing, the cell is placed in a UV curing box for curing under the condition of a wavelength of 365 nm and an energy value of 3000 mj / cm 2 The cell is then stacked and connected in series by soldering.

[0114] Figure 1 The cross-sectional schematic diagram of the UV-curable composition printed in Example 1 is shown in the figure. The glue point 2 (UV-curable composition) is located at the edge of the cell 1 and in the stacking area of the cells 1 and 3. The cells are then connected in series by soldering. Figure 2The schematic diagram of front point gluing, the main grid solder strip 4 contains multiple glue points. The height of the UV curing composition after printing and curing to the surface of the battery is greater than or equal to the height of the two sides of the flattened solder strip, and the width of the printing and curing to the surface of the battery piece is less than or equal to 0.05mm (the spacing between the battery piece laminates).

[0115] Example 2

[0116] The difference between Example 2 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0117] S1, 30 parts by mass of trimethylolpropane triacrylate, 0.8 parts by mass of 1-hydroxycyclohexyl phenyl ketone, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane, 2.5 parts by mass of fumed silica (300μm), 0.2 parts by mass of silicate, 0.5 parts by mass of Tinuvin 123 and 0.5 parts by mass of polyvinyl alcohol are uniformly mixed and then put into a ball mill, and ball-mixed at a speed of 1000r / min-1500r / min for 5min-10min, and ground to a scraper fineness of ≤15um to obtain a first mixture.

[0118] S2, the above first mixture is uniformly mixed with 65 parts by mass of E51 epoxy diacrylate resin oligomer in a watch glass, completely dissolved to obtain a UV curing composition, and stored in a desiccator in the dark, ready for light curing.

[0119] The other operation steps and conditions are the same as those of Example 1.

[0120] Example 3

[0121] The difference between Example 2 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0122] S1, 25 parts by mass of N, N'-methylene bisacrylamide, 1 part by mass of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane, 2.5 parts by mass of fumed silica, 2 parts by mass of aluminum oxide, 1.5 parts by mass of Tinuvin 123 and 1.5 parts by mass of propylene glycol are uniformly mixed and then put into a ball mill, and ball-mixed at a speed of 1000r / min-1500r / min for 5min-10min, and ground to a scraper fineness of ≤15um to obtain a first mixture.

[0123] S2, the above first mixture is uniformly mixed with 66 parts by mass of E51 epoxy diacrylate resin oligomer in a watch glass, completely dissolved to obtain a UV curing composition, and stored in a desiccator in the dark, ready for light curing.

[0124] The other operation steps and conditions are the same as those of Example 1.

[0125] Example 4

[0126] The difference between Example 4 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0127] S1, 25 parts by mass of N, N'-methylenebisacrylamide, 1 part by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane, 2 parts by mass of fumed silica, 2 parts by mass of silicate, 1 part by mass of Tinuvin 123, and 1.5 parts by mass of ethylene glycol are uniformly mixed and then put into a ball mill, and mixed at a speed of 1000 r / min-1500 r / min for 5 min-10 min, and ground to a scraper fineness of ≤15 um to obtain a first mixture.

[0128] S2, the above first mixture is uniformly mixed with 67 parts by mass of a difunctional polyurethane acrylate in a watch glass, completely dissolved, to obtain a UV curing composition, which is stored in a desiccator in the dark, and used for light curing.

[0129] The other operation steps and conditions are the same as those of Example 1.

[0130] Example 5

[0131] The difference between Example 5 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0132] S1, 15 parts by mass of N, N'-methylenebisacrylamide, 1 part by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane, 2 parts by mass of fumed silica, 2.5 parts by mass of alumina, 1 part by mass of Tinuvin 123, and 1 part by mass of ethylene glycol are uniformly mixed and then put into a ball mill, and mixed at a speed of 1000 r / min-1500 r / min for 5 min-10 min, and ground to a scraper fineness of ≤15 um to obtain a first mixture.

[0133] S2, the above first mixture is uniformly mixed with 77 parts by mass of a difunctional polyurethane acrylate in a watch glass, completely dissolved, to obtain a UV curing composition, which is stored in a desiccator in the dark, and used for light curing.

[0134] The other operation steps and conditions are the same as those of Example 1.

[0135] Example 6

[0136] The difference between Example 6 and Example 1 is only that in step S1, 0.5 parts by mass of ethylene glycol is replaced by 0.6 parts by mass of hydroxyethyl methyl cellulose. The other operation steps and conditions are the same as those of Example 1.

[0137] Example 7

[0138] The difference between Example 7 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0139] S1, 15 parts by mass of N, N'-methylenebisacrylamide, 1 part by mass of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane, 1 part by mass of fumed silica, 3.5 parts by mass of alumina, 1.9 parts by mass of Tinuvin 123, and 0.1 parts by mass of ethylene glycol are uniformly mixed and then fed into a ball mill, which is operated at a speed of 1000 r / min-1500 r / min for 5 min-10 min, and ground to a scraper fineness of ≤15 um to obtain a first mixture.

[0140] S2, the first mixture is uniformly mixed with 77 parts by mass of a difunctional polyurethane acrylate in a watch glass, and after complete dissolution, a UV curing composition is obtained, which is stored in a desiccator in the dark, and used for photocuring.

[0141] The other operation steps and conditions are the same as those of Example 1.

[0142] Comparative Example 1

[0143] The difference between Comparative Example 1 and Example 1 is only in the raw material components of steps S1 and S2, specifically:

[0144] S1, 23 parts by weight of trimethylolpropane triacrylate, 1.5 parts by weight of 1-hydroxycyclohexyl phenyl ketone, 1 part by weight of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, 1.5 parts by weight of γ-aminopropyl triethoxysilane, and 2 parts by weight of titanium white powder are uniformly mixed and then fed into a ball mill, which is operated at a speed of 1000 r / min-1500 r / min for 5 min-10 min, and ground to a scraper fineness of ≤15 um to obtain a first mixture.

[0145] S2, the first mixture is uniformly mixed with 70 parts by weight of an E51 epoxy diacrylate resin oligomer in a watch glass, and after complete dissolution, a UV curing composition is obtained, which is stored in a desiccator in the dark, and used for photocuring.

[0146] The other operation steps and conditions are the same as those of Example 1.

[0147] Test Example 1

[0148] The battery pieces after curing of the printed curing compositions obtained in the above examples and comparative examples are tested as follows, and the results are shown in Table 1.

[0149] (1) Viscosity test method: use Brookfield type rotary viscometer to test the UV curing composition before curing. According to the requirements of GBT 2794-2013, the test is operated according to the operation procedure of the equipment, and the test is carried out when the temperature is (25±0.2) ℃, and the test is carried out at 5 rmp / min.

[0150] (2) Thixotropic index test method: use Brookfield type rotary viscometer to test the UV curing composition before curing. According to the viscosity test method, the viscosity η1 of 0.5 rmp / min is determined, and the viscosity η2 of 5 rmp / min is set again. The ratio of the two viscosities, that is, the thixotropic coefficient of the insulating adhesive, is as follows:

[0151] Ti=η 0.5 / η 5

[0152] In the formula: η0.5-viscosity at 0.5 rmp / min;

[0153] η5-viscosity at 5 rmp / min;

[0154] Ti-thixotropic index.

[0155] (3) Hardness test method: use Shore hardness tester to test the UV curing composition (8mm film) after complete curing;

[0156] (4) High temperature modulus test method: test the UV curing composition after complete curing, DMA-tension mode, strain 0.1%, frequency 1HZ, temperature range:-40℃-200℃, heating rate: 3℃ / min, record the modulus value at 120℃;

[0157] (5) Print size measurement method: use piezoelectric injection valve to apply adhesive with UV curing composition, and record the print size (the maximum size in the vertical direction, which can be the distance from the substrate surface to the top of the glue point) after the adhesive is cured after stable;

[0158] (6) Verification of hidden crack rate of photovoltaic module: stack the above printed UV composition cell and record the hidden crack of photovoltaic module after laminating by laminator.

[0159] The measured results are shown in Table 1.

[0160] Table 1: Test results

[0161]

[0162] As shown in Table 1, the cured spot height (i.e. print height) and high temperature modulus of the UV-cured compositions of Examples 1-7 are greater than those of Comparative Example 1. The UV-cured compositions of Examples 1-6 are used in photovoltaic modules, and the photovoltaic module crack rates are reduced to 0-0.32%.

[0163] Although the present application has been disclosed in its preferred embodiments with reference to the accompanying drawings, it is to be understood that the application is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope or spirit of the application. Therefore, claims are intended to cover all such changes and modifications that fall within the scope of the application.

Claims

1. A UV-curable composition for reducing microcracks in photovoltaic modules, characterized in that, The raw materials of the UV curing composition include acrylate oligomers, multifunctional reactive diluent monomers, photoinitiators, coupling agents, silica, dispersants, light stabilizers, and surface tension enhancers. The mass fraction ratio of acrylate oligomers, multifunctional reactive diluent monomers, photoinitiators, coupling agents, silica, dispersants, light stabilizers, and surface tension enhancers is (50-85):(15-30):(1-3):(0.4-2):(1-3):(0.2-3.5):(0.3-2):(0.3-2). The acrylate oligomers are one or more of polyurethane acrylates, epoxy acrylates, and polyester acrylates. The dispersant is at least one of silicate and alumina; The surface tension enhancer is selected from one or more of diols, polyvinyl alcohol, and hydroxyethyl methyl cellulose; wherein the diol is selected from ethylene glycol and / or propylene glycol.

2. The UV-curable composition according to claim 1, characterized in that, The UV-curable composition has one or more of the following characteristics: The acrylate oligomer is an acrylate oligomer with a molecular weight of 500-10,000 Da; The multifunctional reactive diluent monomer is a compound with a molecular weight of 100-500 Da containing two or more polymerizable functional groups. The photoinitiator is a free radical type photoinitiator; The coupling agent is a silane coupling agent; The particle size of the silica is 200-500 nm; The light stabilizer is a hindered amine light stabilizer.

3. The UV-curable composition according to claim 2, characterized in that: The multifunctional reactive diluent monomer is one or more of trimethylolpropane triacrylate, diethylene glycol diacrylate, divinylbenzene, and N,N'-methylenebisacrylamide; The photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-2-methyl-phenylpropanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; The silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane; The silicon dioxide is fumed silicon dioxide; The light stabilizer is selected from one or more of Tinuvin 123, Tinuvin 292 and Tinuvin 622.

4. The UV-curable composition according to claim 1, characterized in that, The UV-curable composition, after photocuring, yields a UV-curable adhesive with a modulus greater than or equal to 8 MPa at 120°C.

5. The UV-curable composition according to claim 4, characterized in that, The UV-curable composition has a modulus of 8-20 MPa after photocuring at 120 degrees Celsius.

6. The UV-curable composition according to claim 5, characterized in that, The UV-curable composition has a modulus of 10 MPa-20 MPa after photocuring at 120 degrees Celsius.

7. The UV-curable composition according to claim 1, characterized in that: The raw materials of the UV curing composition include E51 epoxy diacrylate resin oligomer, divinylbenzene, 1-hydroxycyclohexylphenyl ketone, γ-aminopropyltriethoxysilane, fumed silica, silicate, Tinuvin 123 and ethylene glycol; The raw materials of the UV curing composition include E51 epoxy diacrylate resin oligomer, trimethylolpropane triacrylate, 1-hydroxycyclohexylphenyl ketone, γ-glycidyl etheroxypropyltrimethoxysilane, fumed silica, silicate, Tinuvin 123 and polyvinyl alcohol. The raw materials of the UV curing composition include E51 epoxy diacrylate resin oligomer, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, γ-glycidyl etheroxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123 and propylene glycol. The raw materials of the UV curing composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, γ-glycidyl etheroxypropyltrimethoxysilane, fumed silica, silicate, Tinuvin 123 and ethylene glycol. The raw materials of the UV-curing composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, γ-glycidyl etheroxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and hydroxyethyl methylcellulose; or The raw materials of the UV-curable composition include difunctional polyurethane acrylate, N,N'-methylenebisacrylamide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, γ-glycidyl etheroxypropyltrimethoxysilane, fumed silica, alumina, Tinuvin 123, and ethylene glycol.

8. The UV-curable composition according to any one of claims 1-7, characterized in that: The UV-curable composition has a viscosity of 15,000-45,000 cps at 25±0.2℃; The thixotropic index of the UV-curable composition at 25±0.2℃ is 3-6; The Shore hardness of the UV-curable composition after photocuring is greater than or equal to D65.

9. A UV-curable adhesive, characterized in that, It is obtained by curing the UV curing composition as described in any one of claims 1-8.

10. A photovoltaic cell, characterized in that, The photovoltaic cell includes a cell body and a UV-curing composition as described in any one of claims 1-8 or a UV-curing adhesive as described in claim 9 disposed on the front or back of the cell body.

11. The photovoltaic cell as described in claim 10, characterized in that, The photovoltaic cells are monocrystalline silicon cells, polycrystalline silicon cells, or amorphous silicon cells.

12. The photovoltaic cell as described in claim 10 or 11, characterized in that, The height of the cured adhesive dots in the UV-curable adhesive is >120μm.

13. The photovoltaic cell as described in claim 12, characterized in that, The height of the cured adhesive dots of the UV-curable adhesive is greater than 120 to less than or equal to 160 μm.

14. A photovoltaic module, characterized in that, The photovoltaic module includes a battery string, which includes a plurality of photovoltaic cells stacked as described in any one of claims 10-13, wherein the UV-curable adhesive is contained between the stacked areas of two adjacent photovoltaic cells.

15. The photovoltaic module as described in claim 14, characterized in that, The photovoltaic module also includes solder ribbons for connecting photovoltaic cells in series; the height of the cured adhesive dots of the UV-curable adhesive is greater than or equal to the height of the solder ribbons.

16. The use of a UV-curable composition as described in any one of claims 1-8 in reducing the microcrack rate of photovoltaic modules.

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