Back contact photovoltaic cell capable of preventing stack scratch in high-temperature passivation process

Abstract

The invention provides a back contact photovoltaic cell piece capable of preventing stacking scratch in a high-temperature passivation process. The back contact photovoltaic cell piece comprises a back contact photovoltaic cell piece body and a plurality of soft isolation protrusions located on the light receiving face of the back contact photovoltaic cell piece body. The soft isolation protrusions are used for supporting photovoltaic cells to be mutually isolated when the photovoltaic cells are stacked layer by layer, and the soft isolation protrusions are resistant to high temperature of 300 DEG C and do not become sticky or yellow within 3 hours. According to the invention, the soft isolation projections are arranged on the light receiving surface of the back contact photovoltaic cell sheet body to support mutual isolation of the photovoltaic cell sheets when the photovoltaic cell sheets are stacked layer by layer, so that the photovoltaic cell sheets can be protected from being scratched in the stacking and moving process; the flexible isolation protrusions are arranged on the back contact photovoltaic cell piece, the flexible isolation protrusions can be prevented from scratching the surface of the photovoltaic cell piece due to the specific flexibility of the flexible isolation protrusions, meanwhile, the flexible isolation protrusions can bear the passivation temperature of 300 DEG C or above and do not crack or yellow or adhere to the cell piece, and therefore it can be ensured that the back contact photovoltaic cell piece is subjected to high-temperature passivation in a multi-layer stacking mode, and the passivation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and in particular to a back-contact photovoltaic cell that can prevent stacking scratches during high-temperature passivation process. Background Technology

[0002] Interfacial passivation of photovoltaic cells is a key means to improve the efficiency of crystalline silicon photovoltaic cells. It can deactivate surface defects formed during silicon wafer cutting, thereby reducing the surface recombination of charge carriers. Chemical passivation is one of the more effective passivation methods. Its principle is to deposit a hydrogen-rich dielectric layer, and the free hydrogen released during the sintering process occupies the vacancies of dangling bonds, thereby achieving the passivation effect.

[0003] Because the electrodes of back-contact photovoltaic cells (BC type photovoltaic cells) are on the back of the solar cell and there are no metal electrodes on the front, they are easily scratched when multiple back-contact photovoltaic cells are stacked. Currently, only individual photovoltaic cells can be passivated at high temperature, resulting in low production efficiency. Summary of the Invention

[0004] To address the technical problems existing in the background art, this invention proposes a back-contact photovoltaic cell that can prevent scratches during high-temperature passivation stacking. By providing several soft isolation protrusions on the light-receiving surface of the photovoltaic cell, it supports the isolation between photovoltaic cells when stacked layer by layer. This not only protects the photovoltaic cells from scratches during stacking and movement, but also prevents the soft isolation protrusions from scratching the surface of the photovoltaic cells themselves due to their unique flexibility. At the same time, the soft isolation protrusions can withstand passivation temperatures above 300°C without cracking, yellowing, or sticking to the cells. Therefore, it can ensure that the back-contact photovoltaic cells can be directly passivated at high temperatures in a multi-layer stacking manner, improving passivation efficiency.

[0005] The present invention proposes a back-contact photovoltaic cell that can prevent stacking scratches during high-temperature passivation process, comprising a back-contact photovoltaic cell body and a plurality of soft isolation protrusions located on the light-receiving surface of the back-contact photovoltaic cell body; the soft isolation protrusions are used to support the isolation between photovoltaic cells when stacked layer by layer, and the soft isolation protrusions are resistant to high temperature of 300°C and do not become sticky or yellow after 3 hours.

[0006] In this invention, several soft insulating protrusions on the light-receiving surface of the photovoltaic cells are used to support and isolate the photovoltaic cells from each other when they are stacked layer by layer, thus preventing the surface of the photovoltaic cells from being scratched during stacking. At the same time, the soft insulating protrusions are resistant to high temperatures of 300°C and do not become sticky or yellow after 3 hours. Therefore, they can withstand passivation temperatures above 300°C without cracking, yellowing, or sticking to the cells, thereby ensuring that the back-contact photovoltaic cells can be directly passivated at high temperatures in a multi-layer stacking manner, improving passivation efficiency.

[0007] Preferably, the soft insulating protrusion is an adhesive dot protrusion, an adhesive strip protrusion, or an adhesive tape protrusion; Preferably, the height of the soft insulating protrusion relative to the light-receiving surface of the back contact photovoltaic cell body is 5-30 μm; Preferably, the maximum diameter of the projection of the adhesive dot protrusion onto the light-receiving surface of the back-contact photovoltaic cell body is 10-20 μm.

[0008] Preferably, the plurality of soft insulating protrusions are arranged in an array at intervals on the light-receiving surface of the back-contact photovoltaic cell body; Preferably, the sum of the projected areas of the plurality of soft insulating protrusions on the light-receiving surface of the back contact photovoltaic cell body accounts for 1-10% of the light-receiving surface area of ​​the back contact photovoltaic cell body.

[0009] Preferably, the side of the soft insulating protrusion away from the light-receiving surface of the back contact photovoltaic cell body has a planar or curved structure; Preferably, the soft insulating protrusion is hemispherical, cylindrical, trapezoidal, cuboid, or square trapezoidal.

[0010] Preferably, the Shore hardness of the soft insulating protrusion is 50-70A; Preferably, the light transmittance of the soft insulating protrusion is not less than 90%.

[0011] Preferably, the soft insulating protrusion is made of silicone material; Preferably, the organosilicon material comprises the following raw materials in parts by weight: 70-100 parts of vinyl silicone oil, 30-50 parts of vinyl silicone resin, 4-10 parts of hydrosilicone curing agent, 1-10 parts of inorganic filler, 0-5 parts of coupling agent, 10-30 parts of diluent, 0.1-1 parts of catalyst and 0.01-0.1 parts of inhibitor.

[0012] In this invention, vinyl silicone oil, vinyl silicone resin, and hydrosilicone curing agent undergo a hydrosilylation addition reaction under the action of a catalyst to achieve crosslinking and vulcanization. On the one hand, by using vinyl silicone oil and vinyl silicone resin with low hydroxyl content, low volatility, and appropriate molecular weight, the high-temperature decomposition resistance of the organosilicon material is improved. On the other hand, by adding structural reinforcing fillers, the tensile strength and elongation at break of the organosilicon material are adjusted, thereby significantly improving the cohesive energy density and heat resistance of the organosilicon polymer. This results in the cured organosilicon material having good heat resistance, mechanical properties, and compression resilience.

[0013] Preferably, the vinyl silicone oil is at least one of terminal vinyl polydimethylsiloxane, phenyl vinyl polydimethylsiloxane, or end-side vinyl polydimethylsiloxane; the vinyl silicone resin is at least one of methyl silicone resin, methoxy silicone resin, hydrogen-containing silicone resin, phenyl-modified silicone resin, or vinyl MQ silicone resin. Preferably, the silane curing agent is at least one of trimethylsiloxane-terminated dimethylmethylhydropolysiloxane, hydrogen-terminated dimethylpolysiloxane, or monofunctional polysiloxane. Preferably, the inorganic filler is at least one of fumed silica, glass microspheres, ceramic microspheres, expanded perlite, silica powder, barium sulfate, calcium carbonate, silicon carbide, or alumina. In this invention, fumed silica, glass microspheres, etc. are used as lightweight thermal insulation fillers, which have the characteristics of high softening point and can effectively suppress the high-temperature deformation of soft insulation protrusions, and have good high-temperature stability. Preferably, the coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, methacryloyloxysilane, or γ-aminopropyltriethoxysilane; and the diluent is at least one of a mixture of short-chain alkanes, a silicone oil oligomer, or ethyl acetate.

[0014] In this invention, the silane coupling agent helps to improve the polarity difference between the inorganic filler and the organosilicon matrix, thereby increasing the wettability between the inorganic filler and the organosilicon groups and further improving the bonding effect.

[0015] Preferably, the catalyst is at least one of an amine catalyst, a platinum catalyst, or an organotin catalyst; and the inhibitor is at least one of an alkynol, a modified alkynol, an organophosphorus modified inhibitor, or a maleate ester inhibitor.

[0016] Preferably, the inorganic filler surface is grafted with phenylsilsesquioxane, which is prepared by the following method: After grafting an alkenyl silane coupling agent onto the surface of an inorganic filler, it is then grafted with a phenyl cage-type silsesquioxane to obtain an inorganic filler with a phenyl cage-type silsesquioxane grafted onto its surface. The phenyl cage-type silsesquioxane is obtained by an addition reaction of dimethylsilyl cage-type silsesquioxane and vinylbenzene. The alkenylsilane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyldiethoxysilane, vinyltriisopropoxysilane, methacryloyloxypropyltrimethoxysilane, or methacryloyloxypropyltriethoxysilane.

[0017] In this invention, an alkenyl silane coupling agent is grafted onto the surface of an inorganic filler, giving it an alkenyl group. This alkenyl group can undergo addition with the silanium-hydrogen bonds in a phenyl cage-like silsesquioxane, thereby grafting a hydrogen-containing cyclic siloxane structure with a phenyl group onto the surface of the inorganic filler. This structure not only has good compatibility with the organosilicon matrix, improving the system stability of the inorganic filler in the organosilicon matrix, but also introduces phenyl groups, further improving the high-temperature oxidation resistance of the organosilicon material. Furthermore, during curing, it can chemically react with vinyl silicone oils to form a cross-linked network structure, further regulating the structural properties of the organosilicon matrix and improving the stability of the system.

[0018] Preferably, the preparation method of the organosilicon material includes: mixing vinyl silicone oil, vinyl silicone resin, silane curing agent, coupling agent and diluent in proportions by weight, then adding inorganic filler, mixing evenly under nitrogen protection, then adding catalyst and inhibitor, and mixing evenly at a controlled temperature of 15-20°C under nitrogen protection to obtain the organosilicon material.

[0019] The present invention proposes a method for preparing a back-contact photovoltaic cell that can prevent high-temperature passivation stacking scratches, comprising: printing the organosilicon material on the light-receiving surface of the back-contact photovoltaic cell body, and forming a plurality of soft isolation protrusions after curing.

[0020] Preferably, the printing method is screen printing.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In this invention, by providing a number of soft isolation protrusions on the light-receiving surface of the back-contact photovoltaic cell body, the soft isolation protrusions can form an isolation protection on the surface of the photovoltaic cell during the stacking process, so as to avoid the surface of the photovoltaic cell being scratched. At the same time, by using a specific formulation of organosilicon material, the soft isolation protrusions are ensured to have excellent high temperature resistance and yellowing resistance. If the organosilicon material is printed on the photovoltaic cell to form a number of soft isolation protrusions before the photovoltaic cell is passivated, it can be ensured that the back-contact photovoltaic cell can be directly passivated at high temperature in a multi-layer stacking manner, thereby eliminating the need for inter-cell isolation paper, reducing production costs, and improving the production yield of photovoltaic cells.

[0022] (2) In this invention, a composite organosilicon elastomeric material is generated by reacting vinyl silicone oil, vinyl silicone resin and silane curing agent under the action of a catalyst. The prepared organosilicon material contains a large number of Si-O bonds, whose bond energy is much greater than that of ordinary C-C bonds, giving the organosilicon material excellent high temperature resistance and oxidation resistance, as well as low temperature resistance, flame retardancy, UV resistance and ozone corrosion resistance. Furthermore, by surface treating the inorganic filler, the voids at the particle-polymer interface are reduced, the interfacial thermal resistance of the organosilicon material is reduced and its high temperature resistance is improved. Moreover, due to the introduction of phenyl groups into the structure, its working temperature range is further expanded to -100℃-300℃, which is more heat-resistant than silicone rubber materials without phenyl groups. The heat resistance temperature is further improved, and it can be used for a long time at 350℃. Therefore, it can withstand high temperature passivation. (3) The present invention provides an isolation scheme for high-temperature passivation of back contact photovoltaic cells, which can passivate multiple photovoltaic cells stacked together at the same time, effectively improving the production efficiency of passivating individual photovoltaic cells one by one and reducing costs; the present invention has several soft isolation protrusions formed by high temperature resistant organosilicon material on the light-receiving surface of the back contact photovoltaic cell, and multiple photovoltaic cells are stacked together for high-temperature passivation. After high-temperature passivation, the photovoltaic cells do not stick together, the adhesive dots do not fall off, do not yellow, do not crack, and do not need to be removed after use, and do not affect the battery efficiency. Attached Figure Description

[0023] Figure 1 The following is a schematic diagram of the back-contact photovoltaic cell structure that can prevent stacking scratches during high-temperature passivation process as described in this invention: the left figure is a top view, and the right figure is a side view; Figure 2 This is a schematic diagram of the back-contact photovoltaic cells stacked layer by layer to prevent stacking scratches during the high-temperature passivation process, as described in this invention. Figure 3 This is a schematic diagram of the structure of fumed silica grafted with phenyl silsesquioxane as described in this invention. Detailed Implementation

[0024] Reference Figure 1 , 2 As shown, this invention proposes a back-contact photovoltaic cell that can prevent scratches during high-temperature passivation stacking. It includes a back-contact photovoltaic cell body 10 and several adhesive dot protrusions (soft isolation protrusions) 20 disposed on the light-receiving surface of the back-contact photovoltaic cell body 10. The adhesive dot protrusions 20 are used to support and isolate the back-contact photovoltaic cell body 10 during layer-by-layer stacking, thus forming an isolation protection for the surface of the photovoltaic cell and preventing scratches. Furthermore, the adhesive dot protrusions 20 are heat-resistant up to 300℃ and do not become sticky or yellow after 3 hours, ensuring that the back-contact photovoltaic cell can be directly passivated at high temperatures in a multi-layer stacking manner, improving passivation efficiency.

[0025] In a specific embodiment, the back contact photovoltaic cell body 10 includes, but is not limited to, the BC photovoltaic cell.

[0026] In a specific embodiment, the adhesive dot protrusion can also be replaced by an adhesive strip protrusion or an adhesive tape protrusion.

[0027] In a specific embodiment, the height of the adhesive dot protrusion 20 relative to the light-receiving surface of the photovoltaic cell body 10 is 5-30μm, thus ensuring that the adhesive dot protrusion 20 has a certain height so as to form effective isolation when the photovoltaic cells are stacked layer by layer.

[0028] In a specific embodiment, the maximum diameter of the projection of the adhesive dot protrusion 20 onto the light-receiving surface of the back contact photovoltaic cell body 10 is 10-20 μm.

[0029] Reference Figure 3 As can be seen, in a specific embodiment, a number of adhesive dot protrusions 20 are arranged in an array at intervals on the light-receiving surface of the back contact photovoltaic cell body 10 so that the supporting force of the adhesive dot protrusions 20 on the light-receiving surface of the back contact photovoltaic cell body 10 is evenly distributed.

[0030] In a specific embodiment, the sum of the projected areas of a plurality of adhesive dot protrusions 20 on the light-receiving surface of the back-contact photovoltaic cell body 10 accounts for 1-10% of the light-receiving surface area of ​​the back-contact photovoltaic cell body 10, ensuring that the presence of adhesive dot protrusions does not significantly affect the light absorption rate of the photovoltaic cell.

[0031] In a specific embodiment, the side of the adhesive dot protrusion 20 away from the light-receiving surface of the back contact photovoltaic cell body 10 is a planar or curved structure; for example, the adhesive dot protrusion 20 can be hemispherical, cylindrical, trapezoidal, cuboid or square trapezoidal.

[0032] In a specific embodiment, the Shore hardness of the adhesive dot protrusion 20 is 50-70A, so that the adhesive dot protrusion 20 can provide sufficient support and isolation when photovoltaic cells are stacked.

[0033] In a specific embodiment, the light transmittance of the adhesive dot protrusion 20 is not less than 90%, and it is resistant to high temperature of 300℃ and does not become sticky after 3 hours.

[0034] In a specific embodiment, the adhesive dot protrusion 20 can be prepared by the following method: The silicone material is printed on the light-receiving surface of the back contact photovoltaic cell body 10, and after curing, it forms several adhesive dot protrusions 20.

[0035] In a specific embodiment, screen printing can be used to print the adhesive dots 20. The screen used has a number of mesh holes, which form a preset array pattern.

[0036] The present invention further illustrates the material of the adhesive dot protrusions through specific embodiments below. Unless otherwise stated, the methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art. All raw material compounds in the embodiments are commercially available.

[0037] Example 1 An organosilicon material comprising the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane (vinyl content 0.26 wt%, weight average molecular weight 80,000 Daltons, M w / M n <1.5) 100 parts, vinyl MQ resin (vinyl content 0.97wt%) 50 parts, trimethylsiloxane-terminated dimethylmethylhydrogen polysiloxane (hydrogen content 0.82wt%) 5 parts, fumed silica 6 parts, methacryloxy functional group silane (KH-570 silane coupling agent) 2 parts, short-chain alkane mixture (D60 solvent oil) 20 parts, platinum catalyst (Karstedt platinum catalyst) 0.8 parts, alkynol inhibitor (3,5-dimethyl-1-hexyn-3-ol) 0.1 parts; The preparation method of the above-mentioned organosilicon material includes: adding a mixture of vinyl-terminated polydimethylsiloxane, vinyl MQ resin, trimethylsiloxane-terminated dimethylmethylhydropolysiloxane, methacryloyloxy functional group silane and short-chain alkanes to a mixer according to the specified weight ratio, stirring for 15 min until uniformly mixed, then adding fumed silica, evacuating to a vacuum degree ≤ -0.09 MPa and then filling with nitrogen, stirring for 60 min under nitrogen protection until uniformly mixed, then adding a platinum catalyst and alkynol inhibitor, stirring at a controlled temperature of 20℃ for 120 min under nitrogen protection until uniformly mixed, thus obtaining the organosilicon material.

[0038] Example 2 An organosilicon material comprising the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane (vinyl content 0.26 wt%, weight average molecular weight 80,000 Daltons, M w / M n <1.5) 70 parts, vinyl MQ resin (vinyl content 0.97wt%) 30 parts, trimethylsiloxane-terminated dimethyl methyl hydrogen polysiloxane (hydrogen content 0.82wt%) 4 parts, fumed silica 6 parts, glass microspheres 1 part, γ-glycidyl etheroxypropyltrimethoxysilane (KH-560 silane coupling agent) 5 parts, polydimethylsiloxane (viscosity 50mPa.s) 10 parts, platinum catalyst (Karstedt platinum catalyst) 1 part, alkynol inhibitor (2-methyl-3-butyn-2-ol) 0.01 parts; The preparation method of the above-mentioned organosilicon material includes: adding vinyl-terminated polydimethylsiloxane, vinyl MQ resin, trimethylsiloxane-terminated dimethylmethylhydropolysiloxane, γ-glycidyl etheroxypropyltrimethoxysilane and polydimethylsiloxane to a mixer according to the specified weight ratio, stirring for 15 min until uniformly mixed, then adding fumed silica and glass microspheres, evacuating to a vacuum degree ≤ -0.09 MPa and then filling with nitrogen, stirring for 40 min under nitrogen protection until uniformly mixed, then adding a platinum catalyst and an alkynyl alcohol inhibitor, stirring at a controlled temperature of 18℃ for 180 min under nitrogen protection until uniformly mixed, thus obtaining the organosilicon material.

[0039] Example 3 An organosilicon material comprises the following raw materials in parts by weight: 80 parts of phenyl vinyl silicone oil (vinyl content 0.32 wt%, phenyl content 5 wt%), 40 parts of vinyl MQ resin (vinyl content 0.97 wt%), 10 parts of trimethylsiloxane-terminated dimethyl methyl hydrogen polysiloxane (hydrogen content 0.82 wt%), 1 part of fumed silica, 2 parts of γ-aminopropyltriethoxysilane (KH-550 silane coupling agent), 30 parts of ethyl acetate, 0.1 parts of platinum catalyst (Karstedt platinum catalyst), and 0.05 parts of alkynyl alcohol inhibitor (acetylenylcyclohexanol); The preparation method of the above-mentioned organosilicon material includes: adding phenyl vinyl silicone oil, vinyl MQ resin, trimethylsiloxane-terminated dimethyl methyl hydrogen polysiloxane, γ-aminopropyltriethoxysilane and ethyl acetate to a stirrer according to the specified weight ratio, stirring for 15 min until uniformly mixed, then adding fumed silica, evacuating to a vacuum degree ≤ -0.09 MPa and then filling with nitrogen, stirring for 60 min under nitrogen protection until uniformly mixed, then adding a platinum catalyst and an alkynol inhibitor, stirring for 120 min under nitrogen protection at a controlled temperature of 20℃ until uniformly mixed, thus obtaining the organosilicon material.

[0040] Example 4 An organosilicon material comprising the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane (vinyl content 0.26 wt%, weight average molecular weight 80,000 Daltons, M w / M n <1.5) 100 parts, vinyl MQ resin (vinyl content 0.97wt%) 50 parts, trimethylsiloxane-terminated dimethyl methyl hydrogen polysiloxane (hydrogen content 0.82wt%) 5 parts, fumed silica 6 parts, methacryloxy functional group silane (KH-570 silane coupling agent) 2 parts, short-chain alkane mixture (D60 solvent oil) 20 parts, platinum catalyst (Karstedt platinum catalyst) 0.8 parts, alkynol inhibitor (3,5-dimethyl-1-hexyn-3-ol) 0.1 parts; The fumed silica is grafted phenylsilsesquioxane fumed silica, which is prepared by the following method: Fumed silica is added to anhydrous toluene and ultrasonically dispersed until uniform; 15 wt% (by weight) of vinyltriethoxysilane is added to the fumed silica under nitrogen protection; the mixture is heated to 110°C and stirred for 12 h; the mixture is then centrifuged, washed with acetone, and dried to obtain silica with surface-grafted alkenyl silane coupling agent; dimethylsilyl cage-like silsesquioxane is completely dissolved in anhydrous toluene. Under nitrogen protection, 35 wt% vinyltoluene and 0.005 wt% Karstedt platinum catalyst of dimethylsilyl cage silsesquioxane were added. The mixture was heated to 80°C and stirred for 6 hours. Then, 10 times the mass of dimethylsilyl cage silsesquioxane surface-grafted alkenyl silane coupling agent silica was added, and the reaction was continued for 24 hours. After centrifugation and drying, the fumed silica of the grafted phenyl silsesquioxane was obtained.

[0041] The preparation method of the above-mentioned organosilicon material includes: adding a mixture of vinyl-terminated polydimethylsiloxane, vinyl MQ resin, trimethylsiloxane-terminated dimethylmethylhydropolysiloxane, methacryloyloxy functional group silane and short-chain alkanes to a mixer according to the specified weight ratio, stirring for 15 min until uniformly mixed, then adding fumed silica, evacuating to a vacuum degree ≤ -0.09 MPa and then filling with nitrogen, stirring for 60 min under nitrogen protection until uniformly mixed, then adding a platinum catalyst and alkynol inhibitor, stirring at a controlled temperature of 20℃ for 120 min under nitrogen protection until uniformly mixed, thus obtaining the organosilicon material.

[0042] Comparative Example 1 A polyurethane coating comprises the following raw materials in parts by weight: 30 parts of polyurethane acrylate oligomer (glass transition temperature about 22°C), 70 parts of isobornyl acrylate, 1 part of benzoyl peroxide, and 5 parts of fumed silica.

[0043] The above-mentioned method for preparing polyurethane coating includes: adding polyurethane acrylate oligomer, isobornyl acrylate and benzoyl peroxide to a mixer according to the specified weight ratio, stirring for 10 minutes until uniformly mixed, then adding fumed silica, evacuating to a vacuum degree ≤ -0.09 MPa and then filling with nitrogen gas, stirring for 20 minutes under nitrogen protection until uniformly mixed, thus obtaining the polyurethane coating.

[0044] Comparative Example 2 An epoxy coating comprises the following raw materials in parts by weight: 50 parts of 128 epoxy resin, 10 parts of phenolic resin, 2 parts of dicyandiamide curing agent, 0.3 parts of imidazole curing agent, and 5 parts of fumed silica. The above-mentioned method for preparing epoxy coating includes: adding 128 epoxy resin, phenolic resin, dicyandiamide curing agent and imidazole curing agent to a mixer according to the specified weight ratio, stirring for 20 minutes until uniformly mixed, then adding fumed silica, evacuating to a vacuum degree ≤ -0.09MPa and then filling with nitrogen gas, stirring for 60 minutes under nitrogen protection until uniformly mixed, thus obtaining the epoxy coating.

[0045] Performance testing: Reference Figure 1 The viscosity of the silicone material described in the examples or comparative examples was controlled at 15000-20000 mPas, and the thixotropy was controlled at 4-5. It was printed onto photovoltaic cells using a dot-matrix printing method and cured in a 180℃ high-temperature oven for 1 minute. Twenty photovoltaic cells were printed, and the cured cells were stacked together and baked in a 300℃ oven for 3 hours to simulate passivation. After removal, the transmittance and yellowing of the silicone material, scratches on the photovoltaic cells, and whether the photovoltaic cells adhered were observed. The results are shown in Table 1 below. Table 1 Performance test results of the photovoltaic module insulating sealing tape described in the examples and comparative examples

[0046] Based on the data from Examples 1-4 above, the present invention can effectively solve the problem of scratches on photovoltaic cells during passivation. Furthermore, in Example 2, after simulated passivation, there was no yellowing and no adhesion of photovoltaic cells, which can meet the requirements of the high-temperature passivation process for back-contact photovoltaic cells.

[0047] Based on the data from Comparative Examples 1-2, conventional high-temperature resistant polyurethane acrylic adhesives exhibit yellowing at high temperatures. Furthermore, after being exposed to high temperatures, the molecular chains gradually age and break down, resulting in a significant decrease in physical properties. In contrast, epoxy resins exhibit very obvious yellowing at high temperatures and become brittle due to their high glass transition temperature, making them unsuitable for this application.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A back-contact photovoltaic cell that can prevent stacking scratches during high-temperature passivation process, characterized in that, It includes a back-contact photovoltaic cell body and several soft isolation protrusions located on the light-receiving surface of the back-contact photovoltaic cell body; the soft isolation protrusions are used to support the photovoltaic cells to isolate each other when they are stacked layer by layer, and the soft isolation protrusions are resistant to high temperature of 300℃ and do not become sticky or yellow after 3 hours.

2. The back-contact photovoltaic cell according to claim 1, which prevents stacking scratches during high-temperature passivation process, is characterized in that, The soft insulating protrusions are adhesive dot protrusions, adhesive strip protrusions, or adhesive tape protrusions; Preferably, the height of the soft insulating protrusion relative to the light-receiving surface of the back contact photovoltaic cell body is 5-30 μm; Preferably, the maximum diameter of the projection of the adhesive dot protrusion onto the light-receiving surface of the back-contact photovoltaic cell body is 10-20 μm.

3. The back-contact photovoltaic cell according to claim 1 or 2, which prevents stacking scratches during high-temperature passivation process, is characterized in that... The plurality of soft insulating protrusions are arranged in an array at intervals on the light-receiving surface of the back contact photovoltaic cell body. Preferably, the sum of the projected areas of the plurality of soft insulating protrusions on the light-receiving surface of the back contact photovoltaic cell body accounts for 1-10% of the light-receiving surface area of ​​the back contact photovoltaic cell body.

4. The back-contact photovoltaic cell according to any one of claims 1-3, characterized in that, The side of the soft isolation protrusion away from the light-receiving surface of the back contact photovoltaic cell body has a planar or curved structure. Preferably, the soft insulating protrusion is hemispherical, cylindrical, trapezoidal, cuboid, or square trapezoidal.

5. The back-contact photovoltaic cell according to any one of claims 1-4, characterized in that, The Shore hardness of the soft isolation protrusion is 50-70A; Preferably, the light transmittance of the soft insulating protrusion is not less than 90%.

6. The back-contact photovoltaic cell according to any one of claims 1-5, characterized in that, The soft insulating protrusion is made of silicone material; Preferably, the organosilicon material comprises the following raw materials in parts by weight: 70-100 parts of vinyl silicone oil, 30-50 parts of vinyl silicone resin, 4-10 parts of hydrosilicone curing agent, 1-10 parts of inorganic filler, 0-5 parts of coupling agent, 10-30 parts of diluent, 0.1-1 parts of catalyst and 0.01-0.1 parts of inhibitor.

7. The back-contact photovoltaic cell according to claim 6, which prevents stacking scratches during high-temperature passivation process, is characterized in that... The vinyl silicone oil is at least one of terminal vinyl polydimethylsiloxane, phenyl vinyl polydimethylsiloxane, or end-side vinyl polydimethylsiloxane; the vinyl silicone resin is at least one of methyl silicone resin, methoxy silicone resin, hydrogen-containing silicone resin, phenyl-modified silicone resin, or vinyl MQ silicone resin. The silane curing agent is at least one of trimethylsiloxane-terminated dimethylmethylhydropolysiloxane, hydrogen-terminated dimethylpolysiloxane, or monofunctional polysiloxane. The inorganic filler is at least one of fumed silica, glass microspheres, ceramic microspheres, expanded perlite, silica powder, barium sulfate, calcium carbonate, silicon carbide, or alumina. The coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, methacryloxysilane, or γ-aminopropyltriethoxysilane; the diluent is at least one of a mixture of short-chain alkanes, silicone oil oligomer, or ethyl acetate. The catalyst is at least one of an amine catalyst, a platinum catalyst, or an organotin catalyst; the inhibitor is at least one of an alkynol, a modified alkynol, or a maleate ester inhibitor.

8. The back-contact photovoltaic cell according to claim 6 or 7 that prevents stacking scratches during high-temperature passivation process, characterized in that, The inorganic filler is grafted with phenylsilsesquioxane on its surface, and is prepared by the following method: After grafting an alkenyl silane coupling agent onto the surface of an inorganic filler, it is then grafted with a phenyl cage-type silsesquioxane to obtain an inorganic filler with a phenyl cage-type silsesquioxane grafted onto its surface. The phenyl cage-type silsesquioxane is obtained by adding dimethylsilyl cage-type silsesquioxane and vinylbenzene. The alkenylsilane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyldiethoxysilane, vinyltriisopropoxysilane, methacryloyloxypropyltrimethoxysilane, or methacryloyloxypropyltriethoxysilane.

9. A method for preparing a back-contact photovoltaic cell as described in any one of claims 1-8, characterized in that, include: The silicone material is printed on the light-receiving surface of the back-contact photovoltaic cell body, and after curing, it forms several soft isolation protrusions.

10. The method for preparing a back-contact photovoltaic cell that prevents stacking scratches during high-temperature passivation process according to claim 9, characterized in that, The printing method is screen printing.

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