Slotting process of solar cell

Abstract

The invention discloses a grooving process of a solar cell, which comprises the following steps: S1, printing slurry: printing etching slurry on the cell by using a silk-screen printing screen to form a printing layer; s2, high-temperature grooving: heating and baking the battery piece, etching the battery piece by the etching slurry, and forming a groove in the surface of the battery piece; and S3, cleaning: cleaning the silicon wafer by adopting a rinsing or high-temperature steam cleaning method, and removing the etching slurry on the battery piece. According to the method, production processes such as strong acid etching and strong base cleaning are avoided, the acid-base soaking process is omitted, damage of strong acid and strong base to the conductive film needing to be reserved in the soaking process is avoided, and the technological process is simplified. And moreover, acid and alkali soaking and use of an organic solvent are avoided, the environmental protection cost is reduced, the etching quality of a product is improved, and the effects of high efficiency, energy conservation and environmental protection are achieved.

Description

Technical Field

[0001] The invention relates to the field of solar cells, and in particular to a grooving process for a solar cell sheet. Background Art

[0002] Grooving is an important step in the production of solar cells. It refers to opening a groove on the passivation layer of the solar cell so that the front or back electrode can form a better contact with the solar cell, which is convenient for preparing the electrode grid line, so that the solar cell can collect and transport electrons. At present, there are three main ways to groove the passivation layer of the solar cell: 1) Laser groove technology, using a high-energy pulsed laser beam to irradiate the passivation layer of the cell substrate, the irradiated area quickly heats up, melts, and forms a groove. The laser beam is irradiated along a certain graphic trajectory to form a corresponding groove on the surface of the cell substrate; 2) Photolithography technology, first use photolithography and hard baking to copy the target pattern to the photoresist film, and then mainly use wet etching technology to etch the pattern onto the cell substrate; 3) Screen etching technology, the etching slurry is applied to the passivation layer on the surface of the cell substrate through a screen with a pattern, and then the corresponding pattern is etched on the passivation layer to obtain a cell with a surface groove.

[0003] Among the three grooving methods mentioned above, laser etching has high cost and is easy to damage the battery substrate material, thus affecting the subsequent use of the substrate. Photolithography technology requires the use of wet etching technology, and its operation process is very complicated. In addition, the photoresist is easily damaged during the etching process, making it difficult to obtain a complete pattern. Screen etching has low cost and less damage, making it the preferred method for etching battery substrates.

[0004] CN103865541B discloses an etching slurry for solar cells and a preparation method and a use method thereof. After the back of the solar cell is screen-printed and sintered, the etching slurry is screen-printed on the front, and then etched statically, and then the slurry is cleaned with a potassium hydroxide solution. In the process of cleaning the cell with a strong alkali, the conductive film of the cell will be damaged, and the operation process will be complicated. Summary of the invention

[0005] In order to overcome the above disadvantages, the present invention aims to provide a solar cell slotting process, which is simple to operate and environmentally friendly. In order to achieve the above purpose, the technical solution adopted by the present invention is: a solar cell slotting process, comprising the following steps: S1, printing paste: using a screen printing stencil to print etching paste on the cell to form a printing layer; S2, high temperature slotting: heating and baking the cell, etching the cell with etching slurry, and forming grooves on the surface of the cell; S3. Cleaning: Clean the silicon wafer by rinsing or high-temperature evaporation to remove the etching slurry on the battery cell.

[0006] Furthermore, in S1, the etching slurry is applied to the P-type silicon surface or the N-type silicon surface of the cell.

[0007] Further, in S1, the thickness of the etching slurry coated on the cell is 15-25 μm. Exemplarily, the thickness of the etching slurry coated on the cell is 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm or a range consisting of any two thereof.

[0008] Further, in S1, the etching slurry includes, by weight: 50 to 60 parts of waterborne polymer, 1 to 5 parts of resin, 5 to 30 parts of filler, 20 to 40 parts of organic acid, 20 to 40 parts of solvent, and 1 to 5 parts of auxiliary agent. Exemplarily, the waterborne polymer is in the range of 50 parts, 52 parts, 54 parts, 55 parts, 58 parts, 60 parts, or any two of them; the resin is in the range of 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any two of them; the filler is in the range of 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, or any two of them; the organic acid is in the range of 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any two of them; the solvent is in the range of 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any two of them; the auxiliary agent is in the range of 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any two of them.

[0009] Furthermore, in S1, corresponding portions of water-based high molecular polymer, resin, filler, organic acid, solvent and additive are weighed, and the raw materials of each component are added together and stirred evenly until they become viscous, and the viscosity is controlled to be 10000-40000 MPa·s to obtain a mixed slurry.

[0010] Furthermore, the water-based high molecular polymer is at least one of water-based polyurethane, polyvinyl alcohol, water-soluble epoxy resin, water-soluble alkyd resin, polyethylene glycol, modified starch, modified fiber resin, modified cellulose ether, water-soluble oil, rosin-modified resin and gum arabic.

[0011] Furthermore, the number average molecular weight of the resin is 30,000 to 70,000; and the resin is selected from at least one of sodium hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone and polypropylene glycol.

[0012] Furthermore, the filler is selected from at least one of lithium montmorillonite, water-based organic bentonite, kaolin, acrylic light diffuser, titanium dioxide, hydrophilic silica, attapulgite, aluminum hydroxide, calcium chloride, calcium carbonate and barium sulfate.

[0013] Furthermore, the organic acid is selected from at least one of vinyl phosphoric acid, ethyl phosphoric acid, cyanoethyl phosphoric acid and phenyl phosphoric acid.

[0014] Furthermore, the solvent is selected from at least one of water, glycerol and ethylene glycol.

[0015] Furthermore, the auxiliary agent is selected from at least one of a defoamer, a leveling agent and an emulsifier.

[0016] Furthermore, the defoaming agent is selected from one or more of alkyl silicone oil, alcohols, palm oil and oleic acid.

[0017] Furthermore, the leveling agent is selected from a polyacrylate leveling agent and a polyester-modified polysiloxane leveling agent.

[0018] Furthermore, the emulsifier is selected from polyoxyethylene castor oil, polyoxyethylene 40 hydrogenated castor oil, Tween 80, and 15-hydroxystearate polyethylene glycol.

[0019] Furthermore, in S2, the temperature of the heating baking etching is 120-200° C., and the etching time is 10-50 minutes.

[0020] The beneficial effects of the present invention are as follows: the present invention avoids the use of production processes such as strong acid etching and strong alkali cleaning, eliminates the acid-alkali soaking process, avoids the damage of the conductive film to be retained by the strong acid and strong alkali during the soaking process, simplifies the process flow, and eliminates the use of acid-alkali soaking and organic solvents, reduces environmental protection costs, improves the etching quality of the product, and has the effects of high efficiency, energy saving, and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 The present invention is a flow chart of the grooving process of the solar cell; Figure 2It is a schematic diagram of the printing paste of the present invention; Figure 3 It is a schematic diagram of high temperature grooving of the present invention.

[0024] Among them: 1. Battery cell; 2. Printing layer; 3. Groove. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0026] Except as shown in the operating examples or otherwise indicated, all numbers used in the specification and claims to indicate the amount of ingredients, physicochemical properties, etc. are understood to be adjusted by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0027] A solar cell slotting process comprises the following steps: S1, printing paste: using a screen printing stencil to print etching paste on the battery cell 1 to form a printing layer 2; Weigh 50-60 parts of waterborne polymer, 1-5 parts of resin, 5-30 parts of filler, 20-40 parts of organic acid, 20-40 parts of solvent, 1-5 parts of auxiliary agent, add all the raw materials together and stir evenly until viscous, and control the viscosity to 10000-40000 MPa·s to obtain a mixed slurry. After the solar cell is sequentially subjected to texturing, front cleaning, diffusion, post-cleaning, SiNx deposition, back screen printing and sintering, it is coated on the surface of P-type silicon and N-type silicon respectively by 325 mesh screen printing, wherein the coating thickness on the surface of P-type silicon is 15-25 μm, and the coating thickness on the surface of N-type silicon is 15-25 μm.

[0028] In some embodiments, the water-based polymer is at least one of water-based polyurethane, polyvinyl alcohol, water-soluble epoxy resin, water-soluble alkyd resin, polyethylene glycol, modified starch, modified fiber resin, modified cellulose ether, water-soluble oil, rosin-modified resin and gum arabic.

[0029] In some embodiments, the number average molecular weight of the resin is 30,000 to 70,000; the resin is selected from at least one of sodium hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone and polypropylene glycol.

[0030] In some embodiments, the filler is selected from at least one of lithium montmorillonite, water-based organic bentonite, kaolin, acrylic light diffuser, titanium dioxide, hydrophilic silica, attapulgite, aluminum hydroxide, calcium chloride, calcium carbonate and barium sulfate.

[0031] In some embodiments, the organic acid is selected from at least one of vinyl phosphonic acid, ethyl phosphonic acid, cyanoethyl phosphonic acid, and phenyl phosphonic acid.

[0032] In some embodiments, the solvent is selected from at least one of water, glycerol, and ethylene glycol.

[0033] In some embodiments, the auxiliary agent is selected from at least one of a defoaming agent, a leveling agent, and an emulsifier.

[0034] In some embodiments, the defoaming agent is selected from one or more of alkyl silicone oil, alcohols, palm oil and oleic acid.

[0035] In some embodiments, the leveling agent is selected from a polyacrylate leveling agent, a polyester-modified polysiloxane leveling agent, and a high-boiling-point solvent-containing surfactant leveling agent.

[0036] In some embodiments, the emulsifier is selected from polyoxyethylene castor oil, polyoxyethylene 40 hydrogenated castor oil, Tween 80, and polyethylene glycol 15-hydroxystearate.

[0037] S2, high temperature grooving: using heating and baking etching, etching slurry etches the cell to form a groove 3 on the surface of the cell.

[0038] The cell coated with the etching slurry is placed in an oven and etched at 120-200° C. for 10-50 minutes, so that a groove is formed on the passivation layer, and the groove width of the groove is 20-40 μm.

[0039] S3. Cleaning: The silicon wafer is cleaned by rinsing / high-temperature steam cleaning to remove the etching slurry and ensure that no etching slurry remains in the groove.

[0040] The cleaning machine uses pure water to spray, rinse, clean and air-dry the battery cells.

[0041] Alternatively, the battery cells may be subjected to high temperature steam cleaning by spraying high temperature steam onto the battery cells.

[0042] Example The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0043] Example 1 A solar cell slotting process comprises the following steps: S1. Printing slurry: Print etching slurry on the battery cell using a screen printing stencil to form a printing layer.

[0044] Weigh 55 parts of waterborne polymer, 3 parts of resin, 10 parts by weight of filler, 30 parts of organic acid, 30 parts of solvent, and 1 part of auxiliary agent, add the raw materials of each component together and stir evenly until it becomes viscous, with a viscosity of 20000 MPa·s, to obtain a mixed slurry. After the solar cell is sequentially subjected to texturing, front cleaning, diffusion, post-cleaning, SiNx deposition, back screen printing and sintering, a 325 mesh screen is used to apply to the P-type silicon and N-type silicon surfaces, respectively, wherein the coating thickness on the P-type silicon surface is 20 μm, and the coating thickness on the N-type silicon surface is 20 μm.

[0045] The water-based high molecular polymer is water-based polyurethane, the resin is sodium hydroxymethyl cellulose, the filler is lithium montmorillonite, the organic acid is vinyl phosphate, the solvent is glycerol, and the auxiliary agent is alkyl silicone oil.

[0046] S2, high temperature grooving: using heating and baking etching, etching slurry etches the battery cell to form grooves on the surface of the battery cell.

[0047] The cell coated with the etching slurry is placed in an oven and etched and grooved at 150° C., so that grooves are formed on the passivation layer, and the groove width of the groove is 20 μm.

[0048] S3. Cleaning: The cleaning machine uses pure water to spray, rinse, clean and air-dry the battery cells to remove the etching slurry on the surface of the battery and ensure that there is no etching slurry residue in the groove.

[0049] Example 2 A solar cell slotting process comprises the following steps: S1, printing slurry: using a screen printing plate to print the mixed slurry on the substrate to form a printing layer; Weigh 50 parts of waterborne polymer, 5 parts of resin, 5 parts of filler, 20 parts of organic acid, 40 parts of solvent, and 1 part of auxiliary agent, add the raw materials of each component together and stir evenly until it becomes viscous, with a viscosity of 10000 MPa·s to obtain a mixed slurry. After the solar cell is sequentially subjected to texturing, front cleaning, diffusion, post-cleaning, SiNx deposition, back screen printing and sintering, it is coated on the surface of P-type silicon and N-type silicon respectively by screen printing with a 325 mesh screen, wherein the coating thickness on the surface of P-type silicon is 15 μm, and the coating thickness on the surface of N-type silicon is 15 μm.

[0050] The water-based high molecular polymer is water-based polyurethane, the resin is sodium hydroxymethyl cellulose, the filler is lithium montmorillonite, the organic acid is vinyl phosphate, the solvent is glycerol, and the auxiliary agent is alkyl silicone oil.

[0051] S2, high temperature grooving: using heating and baking etching, etching slurry etches the battery cell to form grooves on the surface of the battery cell.

[0052] The cell coated with the etching slurry is placed in an oven and etched and grooved at 120° C., so that grooves are formed on the passivation layer, and the groove width of the groove is 20 μm.

[0053] S3. Cleaning: The cleaning machine uses pure water to spray, rinse, clean and air-dry the battery cells to remove the etching slurry on the surface of the battery and ensure that there is no etching slurry residue in the groove.

[0054] Example 3 A solar cell slotting process comprises the following steps: S1, printing slurry: using a screen printing plate to print the mixed slurry on the substrate to form a printing layer; Weigh 60 parts of waterborne polymer, 1 part of resin, 30 parts by weight of filler, 40 parts of organic acid, 20 parts of solvent, and 5 parts of additives, add the raw materials of each component together and stir evenly until it becomes viscous, with a viscosity of 35000 MPa·s to obtain a mixed slurry. After the solar cell is sequentially subjected to texturing, front cleaning, diffusion, post-cleaning, SiNx deposition, back screen printing and sintering, it is coated on the surface of P-type silicon and N-type silicon respectively by screen printing with a 325 mesh screen, wherein the coating thickness on the surface of P-type silicon is 25 μm, and the coating thickness on the surface of N-type silicon is 25 μm.

[0055] The water-based high molecular polymer is water-based polyurethane, the resin is sodium hydroxymethyl cellulose, the filler is lithium montmorillonite, the organic acid is vinyl phosphate, the solvent is glycerol, and the auxiliary agent is alkyl silicone oil.

[0056] S2, high temperature grooving: using heating and baking etching, etching slurry etches the battery cell to form grooves on the surface of the battery cell.

[0057] The cell coated with the etching slurry is placed in an oven and etched and grooved at 180° C., so that grooves are formed on the passivation layer, and the groove width of the groove is 25 μm.

[0058] S3. Cleaning: By spraying high-temperature steam onto the battery cell, the battery cell is subjected to high-temperature steam cleaning to remove the etching slurry on the surface of the battery cell and ensure that no etching slurry remains in the groove.

[0059] The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, change of structural morphology, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0060] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0061] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0062] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0063] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A solar cell slotting process, comprising the following steps: S1, printing paste: using a screen printing stencil to print etching paste on the cell to form a printing layer; S2, high temperature slotting: heating and baking the cell, etching the cell with etching slurry, and forming grooves on the surface of the cell; S3. Cleaning: Clean the silicon wafer by rinsing or high-temperature steam cleaning to remove the etching slurry on the battery cell and complete the grooving.

2. The solar cell slotting process according to claim 1, characterized in that: In S1, the etching slurry is applied to the P-type silicon surface or the N-type silicon surface of the cell.

3. The solar cell slotting process according to claim 1, characterized in that: In S1, the thickness of the etching slurry coated on the cell is 15-25 μm.

4. The solar cell slotting process according to claim 1, characterized in that: In S1, the raw materials for preparing the etching slurry include, by weight: 50-60 parts of aqueous high molecular polymer, 1-5 parts of resin, 5-30 parts by weight of filler, 20-40 parts of organic acid, 20-40 parts of solvent, and 1-5 parts of auxiliary agent.

5. The solar cell slotting process according to claim 4, characterized in that: Weigh corresponding portions of waterborne high molecular polymer, resin, filler, organic acid, solvent and additive, add the raw materials of each component together and stir evenly until they become viscous, and control the viscosity to be 10000-40000 MPa·s to obtain a mixed slurry.

6. The solar cell slotting process according to claim 4, characterized in that: The water-based high molecular polymer is selected from at least one of water-based polyurethane, polyvinyl alcohol, water-soluble epoxy resin, water-soluble alkyd resin, polyethylene glycol, modified starch, modified fiber resin, modified cellulose ether, water-soluble oil, rosin-modified resin, and gum arabic.

7. The solar cell slotting process according to claim 4, characterized in that: The resin is selected from at least one of sodium hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinyl pyrrolidone and polypropylene glycol.

8. The solar cell slotting process according to claim 4, characterized in that: The filler is selected from at least one of kaolin, titanium dioxide, lithium montmorillonite, calcium carbonate, water-based organic bentonite, acrylic light diffuser, hydrophilic silica, attapulgite, aluminum hydroxide, calcium chloride and barium sulfate.

9. The solar cell slotting process according to claim 4, characterized in that: The organic acid is selected from at least one of vinyl phosphoric acid, ethyl phosphoric acid, cyanoethyl phosphoric acid and phenyl phosphoric acid; The solvent is selected from at least one of water, glycerol and ethylene glycol; The auxiliary agent is selected from at least one of a defoamer, a leveling agent and an emulsifier; The defoamer is selected from one or more of alkyl silicone oil, alcohols, palm oil and oleic acid; The leveling agent is selected from one of a polyacrylate leveling agent and a polyester modified polysiloxane leveling agent; The emulsifier is selected from polyoxyethylene castor oil, polyoxyethylene 40 hydrogenated castor oil, Tween 80, and 15-hydroxystearate polyethylene glycol.

10. The solar cell slotting process according to claim 1, characterized in that: In S2, the temperature of heating and baking the cell is 120-200°C, and the etching time is 10-50 minutes.

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