Blackening liquid for photovoltaic module as well as preparation method and application of blackening liquid

Abstract

The invention relates to the technical field of solar cells, and discloses a blackening solution for a photovoltaic module and a preparation method and application thereof. The blackening liquid for the photovoltaic module is used for being coated on a welding strip or a bus bar of the photovoltaic module, the welding strip or the bus bar comprises a welding surface and a non-welding surface, and the surface of the non-welding surface contains IVA group metal Pb and / or Sn; the blackening liquid comprises a sulfide, a carboxyl compound and an oxygen-containing polar solvent, the blackening liquid and the non-welding surface are subjected to vulcanization reaction, in-situ blackening treatment is carried out on the non-welding surface of the welding strip or the bus bar, and a blackening layer is formed. By implementing the method, the uniform blackening layer can be quickly formed on the welding strip or the bus bar, the welding strip or the bus bar is not easy to layer or crack when being bent, and the cost is low.

Description

Technical Field

[0001] This invention relates to the technical field of solar cells, and more particularly to a blackening solution for photovoltaic modules, its preparation method, and its application. Background Technology

[0002] In the field of photovoltaic module manufacturing, solder ribbons and busbars are core conductive connection components, and their performance directly affects the photoelectric conversion efficiency and long-term reliability of the module. As the requirements for the aesthetics and light absorption utilization of photovoltaic modules continue to increase, single-sided black-coated solder ribbons or busbars have been widely used because they can reduce light reflection from non-light-receiving surfaces and optimize the overall visual effect of the module.

[0003] Conventional black solder ribbons or busbars are mainly prepared by uniformly coating a black layer onto their non-soldering surfaces. This black coating is usually composed of black paint with added curing agents. After coating, it needs to undergo solvent evaporation and curing processes (such as heat curing or UV curing) to improve the adhesion between the black coating and the solder ribbon or busbar substrate, thus achieving single-sided black coating of the solder ribbon or busbar.

[0004] This type of preparation method has certain advantages. For example, the color and application location of the coating can be adjusted according to actual needs; the resulting black coating has good weather resistance, ensuring the long-term stability of the module; and the coating does not affect the conductivity of the solder strip or busbar. However, this type of preparation method also has significant technical drawbacks. For example, firstly, the coating itself usually does not have conductive properties. If a deviation occurs during the coating process and the coating is mistakenly applied to the welding surface, it will directly affect the welding effect of the solder strip or busbar; when the solder strip or busbar is bent or subjected to local stress, the coating is prone to delamination, cracking, and other problems, affecting the front appearance of the module; and the thickness of conventional black coatings is generally large, resulting in relatively high product manufacturing costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a blackening liquid for photovoltaic modules, its preparation method and application, which can quickly form a uniform blackening layer on the solder strip or busbar, and is not prone to delamination or cracking when the solder strip or busbar is bent, and is low in cost.

[0006] To solve the above-mentioned technical problems, the first aspect of the present invention provides a blackening liquid for photovoltaic modules, used to coat the solder strips or busbars of the photovoltaic modules, wherein the solder strips or busbars include a soldering surface and a non-soldering surface, and the surface of the non-soldering surface contains group IVA metals Pb and / or Sn. The blackening solution includes sulfides, carboxyl compounds, and oxygen-containing polar solvents. The blackening solution undergoes a sulfidation reaction with the non-welded surface, and in-situ blackening treatment is performed on the non-welded surface of the weld strip or busbar to form a blackening layer.

[0007] As an improvement to the above scheme, the blackening liquid, by mass percentage, includes 4-12% sulfides, 2-7% carboxyl compounds, 0.03-0.1% additives, 0-0.2% functional auxiliaries, and the balance being oxygen-containing polar solvents.

[0008] As an improvement to the above scheme, the group IVA metals are Pb and Sn, and the content ratio of Pb to Sn is 1:(0.5-5).

[0009] As an improvement to the above solution, the solder strip or busbar includes a substrate layer and metal plating layers disposed on both sides of the substrate layer, wherein, The substrate layer is selected from one of copper layer, aluminum layer, copper-based alloy layer, and aluminum-based alloy layer; The metal coating is selected from one of lead coating, tin coating, and tin-lead alloy coating.

[0010] As an improvement to the above scheme, the viscosity of the blackening liquid at 25°C is 2 mPa·s-10 mPa·s; The thickness of the blackening layer is 30nm-50nm.

[0011] As an improvement to the above scheme, the pH value of the blackening solution is 2-3.

[0012] As an improvement to the above scheme, the carboxyl compound is selected from at least one of lactic acid, citric acid, and malonic acid.

[0013] As an improvement to the above scheme, the sulfide is a sulfide powder, and the average particle size of the sulfide is 0.1μm-10μm; The sulfide is selected from at least one of Na2S, NaHS, and (NH4)2S.

[0014] As an improvement to the above solution, the additive is selected from at least one of fluorocarbon surfactants, organosilicon wetting agents, and sodium dodecyl sulfate; The fluorocarbon surfactant is a fluorinated nonionic surfactant; The organosilicon wetting agent is a polyether siloxane copolymer with a viscosity of 40 mPa·s-60 mPa·s at 25°C.

[0015] As an improvement to the above scheme, the functional additive is selected from nitrogen-containing heterocyclic compounds and / or phosphates; The nitrogen-containing heterocyclic compound is selected from at least one of benzotriazole, methylbenzotriazole, 3-amino-5-mercapto-1,2,4-triazole, and 3,5-diamino-1,2,4-triazole; The phosphate is selected from at least one of sodium pyrophosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium orthophosphate, and potassium orthophosphate.

[0016] As an improvement to the above scheme, the oxygen-containing polar solvent has a boiling point of 70℃-125℃ and a flash point of 11℃-40℃.

[0017] As an improvement to the above scheme, the oxygen-containing polar solvent is selected from at least one of ethanol, isopropanol, and ethylene glycol monomethyl ether.

[0018] A second aspect of the present invention provides a method for preparing the blackening liquid for photovoltaic modules, comprising the following steps: (1) Mix the sulfide with an oxygen-containing polar solvent to completely dissolve the sulfide and obtain a mixed solution; (2) Add a carboxyl compound to the mixed solution.

[0019] A third aspect of the present invention provides a black solder strip, which is obtained by in-situ blackening the non-welding surface of the solder strip using the blackening liquid for photovoltaic modules.

[0020] As an improvement to the above solution, the non-welding surface of the solder strip is subjected to in-situ blackening treatment, including the following steps: The blackening solution is applied to the non-welding surface of the solder strip and then dried. The solder strip coated with blackening solution is placed in a high-temperature environment for vulcanization to obtain the desired product. During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

[0021] A fourth aspect of the present invention provides a black busbar, which is obtained by in-situ blackening the non-welding surface of the busbar using the blackening liquid for photovoltaic modules.

[0022] As an improvement to the above solution, the non-welded surface of the busbar is subjected to in-situ blackening treatment, including the following steps: The blackening solution is applied to the non-welded surface of the busbar and then dried. The manifold coated with blackening solution is vulcanized in a high-temperature environment to obtain the product. During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

[0023] A fifth aspect of the present invention provides a photovoltaic module, including the black solder strip and / or black busbar.

[0024] Implementing this invention has the following beneficial effects: In this application, by utilizing Pb and / or Sn in the non-soldering surface, and with the sulfides in the blackening solution under the activation of carboxyl compounds, black lead sulfide and / or tin sulfide can be generated in situ on the non-soldering surface, thereby achieving in-situ blackening treatment of the non-soldering surface and forming a uniform blackening layer. This blackening layer can effectively reduce light reflection from the non-light-receiving surface, improve light absorption, and is not prone to delamination or cracking when the solder strip or busbar is bent. Moreover, photogenerated electrons can easily pass through the conductive substrate, making it less susceptible to photobleaching. At the same time, encapsulation in a film can isolate water samples and prevent oxidation.

[0025] In addition, the blackening layer is environmentally friendly, free of heavy metal pollution, and low in cost. Attached Figure Description

[0026] Figure 1 : A schematic diagram of the structure of a welding strip or busbar in this invention; Figure 2 : A schematic diagram of a welding strip or busbar with a blackened layer formed on a non-welded surface in this invention.

[0027] Reference numerals: 1-substrate layer; 2-metal plating layer; 3-blackening layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described in further detail below.

[0029] In the description of this application, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings. They are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0030] To address the aforementioned problems, the first aspect of the present invention provides a blackening liquid for photovoltaic modules, used to coat the solder strips or busbars of the photovoltaic modules, wherein the solder strips or busbars include a soldering surface and a non-soldering surface, and the surface of the non-soldering surface contains group IVA metals Pb and / or Sn. The blackening solution includes sulfides, carboxyl compounds and oxygen-containing polar solvents. The blackening solution undergoes a sulfidation reaction with the non-welded surface, and in-situ blackening treatment is performed on the non-welded surface of the weld strip or busbar to form a blackening layer 3.

[0031] In this application, by utilizing Pb and / or Sn in the non-soldering surface, and with the sulfides in the blackening solution under the activation of carboxyl compounds, black lead sulfide and / or tin sulfide can be generated in situ on the non-soldering surface, thereby achieving in-situ blackening treatment of the non-soldering surface and forming a uniform blackening layer 3 on the non-soldering surface. This blackening layer 3 can effectively reduce light reflection from the non-light-receiving surface, improve light absorption, and is not prone to delamination or cracking when the solder strip or busbar is bent. Moreover, photogenerated electrons can easily pass through the conductive substrate, making it less prone to photobleaching. At the same time, it can be isolated from water samples and is not easily oxidized when encapsulated in a film.

[0032] In addition, the blackening layer 3 is green and environmentally friendly, free of heavy metal pollution, and low in cost.

[0033] Specifically, the reaction mechanism of the blackening solution on the solder strip or busbar is as follows: (1) Pb + 2H + →Pb 2+ +H2↑ (2) Pb 2+ +HS - →PbS↓ (black) +H + Or, (1) Sn+2H + →Sn 2+ +H2↑ (2) Sn 2+ +HS - →SnS↓ (Black) +H + .

[0034] Understandably, the solder strip or busbar includes a substrate layer 1 and metal plating layers 2 disposed on both sides of the substrate layer 1. The substrate layer 1 is selected from one of a copper layer, an aluminum layer, a copper-based alloy layer, and an aluminum-based alloy layer. The filter layer includes a copper-clad aluminum layer. The metal plating layer 2 is selected from one of a lead plating layer, a tin plating layer, and a tin-lead alloy plating layer. Exemplarily, the solder strip is a lead-free solder strip or a Sn60Pb40 solder strip, but is not limited thereto; the busbar is a lead-free busbar or a Sn60Pb40 busbar, but is not limited thereto.

[0035] In some embodiments, the Group IVA metals are Pb and Sn, and the content ratio of Pb to Sn is 1:(0.5-5). 2+ and Sn 2+ Unlike sulfides, Pb has a different reaction rate. 2+ The reaction rate is fast, and the structure of the blackened layer 3 formed is relatively loose, while Sn 2+The reaction rate is slow, resulting in a dense structure of the blackened layer 3. Through the synergistic effect of a specific ratio of Pb and Sn, the reaction rate can be balanced, avoiding localized over-reaction, thereby obtaining a more uniform, dense, and strongly adherent black sulfurized film. Furthermore, it can improve the collection efficiency of photogenerated electrons and enhance the resistance to damp heat and aging of the blackened layer 3. Exemplarily, the Pb to Sn content ratio is 1:0.5, 1:1, 1:2, 1:3, or 1:5, but is not limited to these.

[0036] Preferably, the blackening solution comprises, by mass percentage, 4-12% sulfides, 2-7% carboxyl compounds, 0.03-0.1% additives, 0-0.2% functional auxiliaries, and the balance being an oxygen-containing polar solvent. Adjusting the amounts of sulfides, carboxyl compounds, additives, functional auxiliaries, and oxygen-containing polar solvents can create a reaction system with low viscosity and high reactivity, which helps control the formation rate, thickness, and uniformity of the blackening layer 3. The use of an oxygen-containing polar solvent allows for rapid dissolution and dispersion of other components and can regulate the viscosity of the reaction system. Under the action of carboxyl compounds, the sulfides can release an appropriate amount of sulfur. 2- The addition of carboxyl compounds can provide H+ to the reaction system. + The addition of additives and functional auxiliaries can improve the quality of the blackening layer 3 and avoid damage to the solder strip or busbar substrate by activating Pb and / or Sn in the non-soldering layer.

[0037] Furthermore, the sulfide is a sulfide powder with an average particle size of 0.1 μm-10 μm. Smaller sulfide particles can dissolve rapidly in oxygen-containing polar solvents, releasing more sulfur. 2- The active sites accelerate the reaction with lead and tin in the tin layer and participate in the reaction more uniformly, forming a denser and more uniformly shaped blackened layer 3 on the solder ribbon or busbar, thus improving the conductivity and corrosion resistance of the blackened layer 3. Exemplarily, the average particle size of the sulfide is 0.1 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, or 10 μm, but is not limited thereto.

[0038] Optionally, the sulfide is selected from at least one of Na₂S, NaHS, and (NH₄)₂S. In some embodiments, the sulfide is Na₂S•9H₂O, and its added mass percentage is 6%-12%; in other embodiments, the sulfide is NaHS, and its added mass percentage is 4%-10%; in still other embodiments, the sulfide is (NH₄)₂S, and its added mass percentage is 5%-10%.

[0039] Furthermore, the addition of the carboxyl compound can adjust the pH of the blackening solution to 2-3, providing sufficient H₂O. +On the basis of this, excessive corrosion of the welding strip or busbar should be avoided. If the pH value of the blackening solution is too low, it will promote the generation of H2S gas, disrupt the chemical balance of the blackening solution, make it difficult to control the sulfidation reaction rate, and result in uneven blackening layer 3 and poor adhesion, causing excessive corrosion of the welding strip or busbar and increasing safety risks.

[0040] Optionally, the carboxyl compound is selected from at least one of lactic acid, citric acid, and malonic acid. In some embodiments, the carboxyl compound is lactic acid, and its added mass percentage is 3%-6%; in other embodiments, the carboxyl compound is citric acid, and its added mass percentage is 2%-5%; in still other embodiments, the carboxyl compound is malonic acid, and its added mass percentage is 2%-4%.

[0041] Furthermore, the additive is selected from at least one of fluorocarbon surfactants, organosilicon wetting agents, and sodium dodecyl sulfate. The fluorocarbon surfactant is a fluorinated nonionic surfactant that can maintain its activity in the presence of carboxyl compounds, improving the wetting performance of the blackening solution on the surface of the solder ribbon or busbar and ensuring process stability. The organosilicon wetting agent is a polyether siloxane copolymer with a viscosity of 40 mPa·s-60 mPa·s at 25°C. Synergistically with oxygen-containing polar solvents, it can improve the flowability of the blackening solution, precisely control the coating thickness, and form a more uniform film. The sodium dodecyl sulfate can effectively disperse sulfide powder, prevent its agglomeration, and reduce the contact angle between the blackening solution and the metal surface, promoting uniform reaction.

[0042] In some embodiments, the fluorinated nonionic surfactant may be fluorocarbon surfactant FS-3100, but is not limited thereto; the organosilicon wetting agent may be TEGO Wet 270, but is not limited thereto.

[0043] Furthermore, the functional additives are selected from nitrogen-containing heterocyclic compounds and / or phosphates, which can regulate the reaction rate of the vulcanization reaction and further ensure the thickness and density of the blackening layer 3. The nitrogen-containing heterocyclic compounds are selected from at least one of benzotriazole, methylbenzotriazole, 3-amino-5-mercapto-1,2,4-triazole, and 3,5-diamino-1,2,4-triazole; the phosphates are selected from at least one of sodium pyrophosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium orthophosphate, and potassium orthophosphate.

[0044] In some specific and preferred embodiments, the substrate layer 1 of the solder strip or busbar is a copper layer or a copper-based alloy layer, and the functional additive is a nitrogen-containing heterocyclic compound, specifically benzotriazole, with an added mass percentage of 0.05%-0.2%; or, the nitrogen-containing heterocyclic compound is methylbenzotriazole, with an added mass percentage of 0.03%-0.15%; or, the functional additive is a phosphate, specifically sodium pyrophosphate, with an added mass percentage of 0.02%-0.1%.

[0045] In some other specific and preferred embodiments, the substrate layer 1 of the welding strip or busbar is an aluminum layer or an aluminum-based alloy layer, and the mass percentage of the functional additive in the blackening solution is 0. Of course, the mass percentage of the functional additive may not be 0, and its specific mass percentage can be reasonably adjusted according to the actual situation. This application does not make specific limitations in this regard.

[0046] Furthermore, the oxygen-containing polar solvent has a boiling point of 70℃-125℃ and a flash point of 11℃-40℃, making it highly volatile and safe. This allows the blackening solution to have a viscosity of 2mPa·s-10mPa·s at 25℃, facilitating uniform coating on the surface of solder strips or busbars. It also allows for rapid curing, shortening the preparation time of the blackening layer 3, making it suitable for on-site preparation and use in module production. For example, the viscosity of the blackening solution at 25℃ is 2mPa·s, 4mPa·s, 6mPa·s, 8mPa·s, or 10mPa·s, but is not limited to these. It is understood that if the viscosity of the blackening solution does not meet the requirements, it can be adjusted by adjusting the dosage ratio of the oxygen-containing polar solvent.

[0047] Optionally, the oxygen-containing polar solvent is selected from at least one of ethanol, isopropanol, and ethylene glycol monomethyl ether. The evaporation rate can be adjusted so that the blackening layer 3 completes blackening within 30s-60s and prevents the blackening layer 3 from whitening.

[0048] The PbS and / or SnS are amorphous, resulting in a matte black black black black layer 3. In some embodiments, the thickness of the black layer 3 is 30nm-50nm. It has strong adhesion to solder ribbons or busbars, and its visible light absorption rate can be increased to >90%. It appears "completely black" to the naked eye and can maintain the corresponding hardness. Moreover, it does not cause local resistance to increase or trigger hot spot effects.

[0049] Accordingly, a second aspect of the present invention also provides a method for preparing the blackening liquid for photovoltaic modules, comprising the following steps: (1) Mix the sulfide with an oxygen-containing polar solvent to completely dissolve the sulfide and obtain a mixed solution; (2) Add a carboxyl compound to the mixed solution.

[0050] In some embodiments, the method for preparing the blackening liquid for photovoltaic modules includes the following steps: (1) Mix the sulfide with an oxygen-containing polar solvent to completely dissolve the sulfide and obtain a mixed solution; (2) Add carboxyl compounds, additives and functional auxiliaries to the mixed solution in sequence.

[0051] Accordingly, a third aspect of the present invention also provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip using the blackening liquid for photovoltaic modules.

[0052] In some embodiments, the non-welding surface of the solder strip is subjected to in-situ blackening treatment, including the following steps: S1. Apply the blackening solution to the non-welding surface of the solder strip and dry it; S2. Place the solder strip coated with blackening solution in a high-temperature environment for vulcanization to obtain the desired product. During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

[0053] In some embodiments, in step (1), the blackening liquid can be coated on the non-welding surface of the welding strip using an online coating process. The online coating speed is >30m / min. Specifically, slit extrusion or micro-grooved roller coating can be used to increase the uniformity of the blackening liquid on the non-welding surface.

[0054] In some embodiments, in step (1), the drying process can be carried out by natural drying at room temperature for 5s-10s, or by heating. The heating temperature can be 60℃-80℃. The specific drying time can be reasonably adjusted according to the actual situation. This application does not make any specific limitation on this.

[0055] In some embodiments, step (1), coating the blackening liquid onto the non-welding surface of the solder strip, further includes: performing surface cleaning treatment on the solder strip to remove oil stains and increase the contact area between the blackening liquid and the surface of the solder strip. Specifically, alcohol or plasma can be used to perform surface cleaning treatment on the solder strip, and this application does not specifically limit this.

[0056] Accordingly, a fourth aspect of the present invention also provides a black busbar, which is obtained by in-situ blackening treatment of the non-welding surface of the busbar using the blackening liquid for photovoltaic modules.

[0057] In some embodiments, the non-welded surface of the busbar is subjected to in-situ blackening treatment, including the following steps: S1. Apply the blackening liquid to the non-welding surface of the busbar and dry it; S2. Place the manifold coated with blackening liquid in a high-temperature environment for vulcanization to obtain the product; During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

[0058] In some embodiments, in step (1), the blackening liquid can be coated on the non-welded surface of the busbar using an online coating process. The online coating linear speed is >30m / min. Specifically, slit extrusion or micro-grooved roller coating can be used to increase the uniformity of the blackening liquid on the non-welded surface.

[0059] In some embodiments, in step (1), the drying process can be carried out by natural drying at room temperature for 5s-10s, or by heating. The heating temperature can be 60℃-80℃. The specific drying time can be reasonably adjusted according to the actual situation. This application does not make any specific limitation on this.

[0060] In some embodiments, step (1), coating the non-welded surface of the busbar with the blackening liquid, further includes: performing surface cleaning treatment on the busbar to remove oil stains and increase the contact area between the blackening liquid and the surface of the busbar. Specifically, alcohol or plasma can be used to perform surface cleaning treatment on the busbar, and this application does not specifically limit this.

[0061] Accordingly, the fifth aspect of the present invention also provides a photovoltaic module, including the aforementioned black solder strip and / or the aforementioned black busbar.

[0062] In some embodiments, photovoltaic (PV) systems can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. They can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of PV systems are not limited to these; that is, PV systems can be applied in all areas that require solar energy for power generation. Taking a photovoltaic power generation network as an example, a PV system may include a PV array, a combiner box, and an inverter. The PV array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple PV arrays. The PV array is connected to the combiner box, which collects the current generated by the PV array. The collected current flows through the inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0063] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a blackening liquid for photovoltaic modules, used to coat the solder strips of the photovoltaic modules, wherein the solder strips include a soldering surface and a non-soldering surface; The solder strip includes a substrate layer and metal plating layers disposed on both sides of the substrate layer, wherein the substrate layer is a copper layer and the metal plating layers are tin plating layers; The blackening solution, by mass percentage, comprises 8% Na2S•9H2O micro powder (average particle size <10μm), 5% lactic acid, 0.05% fluorocarbon surfactant FS-3100, and the balance ethanol.

[0064] Accordingly, this embodiment provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip using the blackening solution, specifically including: The blackening solution is applied to the non-welding surface of the solder strip to a thickness of 8 μm and then dried. The solder strip coated with blackening solution is placed in a high-temperature environment for vulcanization to obtain the desired product. During the vulcanization process, the vulcanization temperature is controlled at 120°C and the vulcanization time is 45 seconds, resulting in a dry film thickness of 180 nm for the blackened layer.

[0065] Example 2 This embodiment provides a blackening solution for photovoltaic modules, which is basically the same as that in Embodiment 1, except that: The blackening solution, by mass percentage, comprises 9% NaHS micro powder (average particle size <10μm), 4% citric acid, 0.03% TEGO Wet 270 organosilicon wetting agent, and the balance isopropanol.

[0066] Accordingly, this embodiment provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip with the blackening liquid, and the specific steps are the same as in Embodiment 1; The blackening liquid is applied to the non-welding surface of the solder strip, with a coating thickness of 6 μm. During the vulcanization process, the vulcanization time is 30 seconds, and the dry film thickness of the resulting blackened layer is 140 nm.

[0067] Example 3 This embodiment provides a blackening solution for photovoltaic modules, which is basically the same as that in Embodiment 1, except that: The blackening solution, by mass percentage, comprises 10% (NH4)2S micro powder (average particle size <10μm), 6% malonic acid, 0.03% organosilicon wetting agent TEGO Wet 270, and the balance being ethylene glycol monomethyl ether.

[0068] Accordingly, this embodiment provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip with the blackening liquid, and the specific steps are the same as in Embodiment 1.

[0069] Specifically, the blackening solution is applied to the non-welding surface of the solder strip, with a coating thickness of 10 μm. During the vulcanization process, the vulcanization time is 60 seconds, and the dry film thickness of the resulting blackened layer is 220 nm.

[0070] Example 4 This embodiment provides a blackening solution for photovoltaic modules, which is basically the same as that in Embodiment 1, except that: The blackening solution, by mass percentage, comprises 8% Na2S•9H2O micro powder (average particle size <10μm), 5% lactic acid, 0.05% fluorocarbon surfactant FS-3100, 0.08% methylbenzotriazole, and the balance ethanol.

[0071] Accordingly, this embodiment provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip with the blackening liquid, and the specific steps are the same as in Embodiment 1; During the vulcanization process, the vulcanization time is 35 seconds, and the dry film thickness of the resulting blackened layer is 100 nm.

[0072] Example 5 This embodiment provides a blackening solution for photovoltaic modules, which is basically the same as that in Embodiment 4, except that: The metal coating is a tin-lead alloy coating, wherein the content ratio of Pb to Sn is 40:60.

[0073] Accordingly, this embodiment provides a black solder strip, which is obtained by in-situ blackening treatment of the non-welding surface of the solder strip with the blackening liquid, and the specific steps are the same as in Embodiment 1; During the vulcanization process, the vulcanization time is 40 seconds, and the dry film thickness of the resulting blackened layer is 110 nm.

[0074] Performance testing: 1. Absorbance: The absorbance of the non-welded surface of the black solder strips obtained in Examples 1-5 was tested, and the test results are shown in Table 1.

[0075] 2. Hardness: The pencil hardness of the blackened layer of the black solder strips obtained in Examples 1-5 was tested, and the test results are shown in Table 1.

[0076] 3. Weather resistance: The black solder strips obtained in Examples 1-5 were tested in a neutral salt spray test for 48 hours to observe whether peeling, blistering or delamination occurred. The color change (ΔE) before and after the test was observed and calculated. The test results are shown in Table 1.

[0077] 4. UV resistance: The black solder ribbons obtained in Examples 1-5 were placed in a UV aging chamber and accelerated for 1000 hours. The color change (ΔE) before and after the test was observed and calculated. The test results are shown in Table 1.

[0078] Table 1 Performance test results of the blackening layer in Examples 1-5

[0079] The above results show that by reacting Pb and / or Sn in the non-welding surface with the blackening solution, a black blackening layer can be generated in situ on the non-welding surface. This blackening layer has a high light absorption rate, strong adhesion to the solder strip or busbar, and is not easy to delaminate or crack. Moreover, the blackening layer has a certain hardness, and photogenerated electrons can easily pass through the conductive substrate. It is not easy to be photobleached. At the same time, it can be isolated from water samples and is not easily oxidized when encapsulated in a film.

[0080] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A blackening liquid for photovoltaic modules, used to coat the solder ribbons or busbars of the photovoltaic modules, characterized in that, The welding strip or busbar includes a welding surface and a non-welding surface, wherein the surface of the non-welding surface contains Group IVA metals Pb and / or Sn; The blackening solution includes sulfides, carboxyl compounds, and oxygen-containing polar solvents. The blackening solution undergoes a sulfidation reaction with the non-welded surface, and in-situ blackening treatment is performed on the non-welded surface of the weld strip or busbar to form a blackening layer.

2. The blackening solution for photovoltaic modules as described in claim 1, characterized in that, The blackening solution, by mass percentage, comprises 4-12% sulfides, 2-7% carboxyl compounds, 0.03-0.1% additives, 0-0.2% functional auxiliaries, and the balance being oxygen-containing polar solvents.

3. The blackening solution for photovoltaic modules as described in claim 1, characterized in that, The group IVA metals are Pb and Sn, and the content ratio of Pb to Sn is 1:(0.5-5).

4. The blackening solution for photovoltaic modules as described in claim 3, characterized in that, The welding strip or busbar includes a substrate layer and metal plating layers disposed on both sides of the substrate layer, wherein, The substrate layer is selected from one of copper layer, aluminum layer, copper-based alloy layer, and aluminum-based alloy layer; The metal coating is selected from one of lead coating, tin coating, and tin-lead alloy coating.

5. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The viscosity of the blackening liquid at 25°C is 2 mPa·s-10 mPa·s; The thickness of the blackening layer is 30nm-50nm.

6. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The pH value of the blackening solution is 2-3.

7. The blackening solution for photovoltaic modules as described in claim 1 or 6, characterized in that, The carboxyl compound is selected from at least one of lactic acid, citric acid, and malonic acid.

8. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The sulfide is a sulfide powder, and the average particle size of the sulfide is 0.1 μm-10 μm; The sulfide is selected from at least one of Na2S, NaHS, and (NH4)2S.

9. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The additive is selected from at least one of fluorocarbon surfactants, organosilicon wetting agents, and sodium dodecyl sulfate. The fluorocarbon surfactant is a fluorinated nonionic surfactant; The organosilicon wetting agent is a polyether siloxane copolymer with a viscosity of 40 mPa·s-60 mPa·s at 25°C.

10. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The functional additives are selected from nitrogen-containing heterocyclic compounds and / or phosphates; The nitrogen-containing heterocyclic compound is selected from at least one of benzotriazole, methylbenzotriazole, 3-amino-5-mercapto-1,2,4-triazole, and 3,5-diamino-1,2,4-triazole; The phosphate is selected from at least one of sodium pyrophosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium orthophosphate, and potassium orthophosphate.

11. The blackening solution for photovoltaic modules as described in claim 2, characterized in that, The oxygen-containing polar solvent has a boiling point of 70℃-125℃ and a flash point of 11℃-40℃.

12. The blackening solution for photovoltaic modules as described in claim 11, characterized in that, The oxygen-containing polar solvent is selected from at least one of ethanol, isopropanol, and ethylene glycol monomethyl ether.

13. A method for preparing a blackening liquid for photovoltaic modules as described in any one of claims 1-12, characterized in that, Includes the following steps: (1) Mix the sulfide with an oxygen-containing polar solvent to completely dissolve the sulfide and obtain a mixed solution; (2) Add a carboxyl compound to the mixed solution.

14. A black solder strip, characterized in that, The non-welding surface of the solder strip is obtained by in-situ blackening treatment with the blackening solution for photovoltaic modules as described in any one of claims 1-12.

15. The black solder strip as described in claim 14, characterized in that, The non-welding surface of the solder strip undergoes in-situ blackening treatment, including the following steps: The blackening solution is applied to the non-welding surface of the solder strip and then dried. The solder strip coated with blackening solution is placed in a high-temperature environment for vulcanization to obtain the desired product. During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

16. A black busbar, characterized in that, The busbar is obtained by in-situ blackening of the non-welded surface using the blackening solution for photovoltaic modules as described in any one of claims 1-12.

17. The black busbar as described in claim 16, characterized in that, The non-welded surface of the busbar is subjected to in-situ blackening treatment, including the following steps: The blackening solution is applied to the non-welded surface of the busbar and then dried. The manifold coated with blackening solution is vulcanized in a high-temperature environment to obtain the product. During the vulcanization process, the vulcanization temperature is controlled at 110℃-130℃, and the vulcanization time is 30s-60s.

18. A photovoltaic module, characterized in that, Includes the black solder strip as described in claim 14 or 15 and / or the black busbar as described in claim 16 or 17.

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