A screen processing method for improving the performance of heterojunction solar cells

Abstract

The present invention provides a screen processing method for improving the performance of heterojunction solar cells, comprising the following steps: preparing a super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution; preparing a super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution; applying the coating solution to the scraper surface of the screen and drying it; applying the coating solution to the printing surface of the screen, attaching a film to the printing surface of the screen, and curing it with ultraviolet light; after curing, removing the film, and rinsing the printing surface with water to form a desired pattern to prepare the screen. This method effectively improves the performance of the screen by bonding a layer of super-hydrophobic ionic liquid / silicon dioxide / polyimide composite film to the stretched screen, reduces the adhesion of the slurry to the screen, and greatly reduces the amount of slurry used during printing.

Description

Technical Field

[0001] The present invention relates to the technical field of battery printing screens, and in particular to a screen processing method for improving the performance of heterojunction solar cells. Background Art

[0002] Resources like oil and coal are non-renewable. With their continued use and development, Earth's reserves are no longer sufficient to meet the needs of human development and progress. Furthermore, with air pollution becoming increasingly severe, the development of new energy sources has become a global concern. Photovoltaic power generation, a green energy source, has seen rapid growth in recent years. The long hours of sunshine in most parts of my country are ideal for the development of the photovoltaic industry, and in recent years, my country has become a major photovoltaic power generation country. Heterojunction cells, also known as crystalline silicon heterojunction solar cells, are constructed by depositing an amorphous silicon thin film on crystalline silicon. They combine the advantages of crystalline silicon cells and thin-film cells, offering the excellent absorption properties of conventional crystalline silicon cells with the superior passivation characteristics of thin-film amorphous silicon. Heterojunction solar cells are a fusion of two different materials. They offer significant potential for improving photoelectric conversion efficiency, greater cost reduction potential, higher bifaciality, reduced heat loss, lower light-induced degradation, and a simpler fabrication process, making them a hot investment area for next-generation solar cells.

[0003] The electrodes of heterojunction solar cells are formed using screen printing. The screen structure consists of a screen frame, a mesh, and a pattern. The pattern is applied to the mesh, the edges of which are fixed within the frame. The mesh is composed of multiple mesh threads arranged according to specific requirements. To improve screen printing life and printability, the material used for screen patterns has shifted from traditional photosensitive adhesives to polyimide films, and the manufacturing process has also changed from exposure-development to laser cutting. Polyimide films are also more adaptable to various pastes than traditional photosensitive adhesives and have become the mainstream screen printing material for solar cells. However, as cell factories increasingly demand cost reduction and efficiency, screen patterns are becoming finer and the printed film thickness is becoming thinner. This leads to a decrease in the adhesion of the paste to the silicon wafer. This can cause printed lines to be easily carried away by the screen, or the paste to stick to the screen surface, reducing the amount of paste attached to the silicon wafer, resulting in false prints or broken gates. Therefore, reducing the adhesion of the paste to the screen has become a research focus. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to address the shortcomings of the existing technology, a screen processing method for improving the performance of heterojunction solar cells is provided. This method effectively improves the performance of the screen and reduces the adhesion of the slurry to the screen, thereby greatly reducing the amount of slurry used during printing.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A screen processing method for improving the performance of heterojunction solar cells comprises the following steps:

[0007] preparing a super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution;

[0008] Apply the coating solution to the scraper surface of the screen and dry it;

[0009] Apply the coating solution to the printing surface of the screen, and attach a film to the printing surface of the screen, and perform ultraviolet irradiation curing;

[0010] After curing, the film is removed and the printed surface is rinsed with water to form the desired pattern and prepare the screen.

[0011] Preferably, the method for preparing the super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution comprises the following steps:

[0012] (1) adding 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride to a solvent and stirring to mix, then adding an ionic liquid and continuing to stir to prepare a mixed solution;

[0013] (2) mixing ethyl orthosilicate and ethanol and stirring them uniformly, then adding APTES and continuing stirring to obtain a dispersion; dissolving 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride in an ethanol solution, heating and hydrolyzing, mixing the obtained hydrolyzate and the dispersion, adding 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, stirring and reacting, filtering the reaction solution after the reaction is completed, and drying the obtained precipitate to obtain modified nano-silica;

[0014] (3) Adding the modified nano-silica to the mixed solution prepared in step (1), and performing ultrasonic dispersion treatment to prepare a coating solution.

[0015] Preferably, in step (1), the molar ratio of the 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, and the ionic liquid is 1:1:(1-2).

[0016] Preferably, in step (1), the solvent is one of dimethylformamide and dimethylacetamide.

[0017] Preferably, in step (1), the stirring speed during the stirring and mixing is 1000-2000 rpm, and the stirring time is 10-15 hours.

[0018] Preferably, in step (1), the stirring time is 5-10 hours.

[0019] Preferably, in step (2), the usage ratio of ethyl orthosilicate, ethanol and APTES is (5-10) g:150 ml:(0.1-0.5) g.

[0020] Preferably, in step (2), the temperature for uniform mixing and stirring is 60-70° C., and the time is 20-30 min.

[0021] Preferably, in step (2), the stirring time is 1-2 hours.

[0022] Preferably, in step (2), the concentration of the ethanol solution is 20-30 v / v%, and the usage ratio of the 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride to the ethanol solution is (0.5-1) g:50 ml.

[0023] Preferably, in step (2), the temperature of the hydrolysis is 65-75° C. and the time is 5-10 h.

[0024] Preferably, in step (2), the volume ratio of the hydrolyzate to the dispersion is (3-5):1.

[0025] Preferably, in step (2), the mass ratio of the 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl to the 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride is (0.5-0.8):(0.5-1).

[0026] Preferably, in step (2), the stirring reaction temperature is 60-70° C. and the time is 1-2 h.

[0027] Preferably, in step (3), the mass ratio of the modified nano-silica to the mixed solution is (0.01-0.05):10.

[0028] Preferably, the process of applying the coating solution to the scraper surface of the screen and drying specifically includes: first keeping it warm at 60°C for 1 hour, then keeping it warm at 80°C for 1 hour, keeping it warm at 100°C for 1 hour, and finally keeping it warm at 200°C for 1 hour.

[0029] Preferably, in step (3), the thickness of the superhydrophobic ionic liquid / silicon dioxide / polyimide composite film is 10-20 μm.

[0030] Preferably, the UV curing time is 200-400s.

[0031] Preferably, the film layer thickness on the screen scraper surface is 3-8 μm, and the film layer thickness on the screen printing surface is 5-10 μm.

[0032] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] The present invention modifies the stretched screen by using the prepared super-hydrophobic ionic liquid / silicon dioxide / polyimide composite film, effectively improving the hydrophobicity of the screen, thereby reducing the adhesion between the slurry and the printing screen, avoiding printing defects caused by strong adhesion of the slurry, such as screen clogging or screen sticking, and also reducing the amount of slurry used to a certain extent.

[0034] The present invention uses ionic liquid, modified silica, and polyimide as a composite membrane when modifying the screen. The ionic liquid has good thermal and chemical stability. When combined with silica and polyimide, it forms a composite material with low surface energy. Silica provides a rough micro-nanostructure, while polyimide imparts good mechanical strength and heat resistance to the composite membrane. A lotus leaf-like microstructure forms on the surface of the composite membrane. This structure can effectively reduce the contact area between the slurry and the solid surface, thereby greatly reducing the adhesion of the slurry. Furthermore, the microstructure promotes a more localized distribution of the slurry on the membrane surface, thereby reducing overall adhesion and improving printing reliability.

[0035] Furthermore, polyimide, as a high-performance polymer, possesses excellent chemical stability and heat resistance, enabling the composite film to maintain its optimal physical state during the curing process. After curing, the bond between the composite film and the screen becomes even stronger, forming a mechanically interlocking structure that enhances the film's overall stability. After laser cutting, the composite film exhibits superior cross-sectional quality, further preventing slurry adhesion to the cut edges. DETAILED DESCRIPTION

[0036] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0037] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0038] Unless otherwise specified, the materials in the following examples and comparative examples are commercially available.

[0039] Unless otherwise specified, the experimental conditions in the following methods are conventional experimental conditions in this field.

[0040] Specifically, in the following examples and comparative examples, the leveling agent is Digo Glide 410 leveling agent; the defoaming agent is TEGOFoamex 825 defoaming agent produced by Digo; and the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate.

[0041] In the following embodiments, the method for preparing the stretched screen is as follows:

[0042] S1: Select a tungsten wire mesh with a mesh size of 300 and a wire diameter of 15 μm, and reduce the thickness of the mesh to 20 μm by high-pressure rolling;

[0043] S2: Stretch the mesh horizontally on a mesh frame, stretch it using a mesh stretching fixture, and ensure that the radial mesh lines and the weft mesh lines after stretching are parallel to the main body directions of two adjacent sides of the mesh frame.

[0044] Example 1

[0045] A screen processing method for improving the performance of heterojunction solar cells comprises the following steps:

[0046] (1) 3 mmol TFMB and 3 mmol 6FDA were added to dimethylacetamide and stirred at 1000 rpm for 15 h. Then, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was added and stirred for 6 h to obtain a mixed solution.

[0047] (2) 6 g of tetraethyl orthosilicate and 150 ml of ethanol were mixed, stirred at 60° C. for 30 min, 0.5 g of APTES was added to the flask, and stirring was continued for 1 h to obtain a dispersion; 0.91 g of 6FDA was dissolved in 50 ml of a 30 v / v% ethanol solution, heated to 70° C. and hydrolyzed for 6 h to obtain a hydrolyzate; the above dispersion and hydrolyzate were mixed, 0.66 g of TFMB was added, and the mixture was stirred at 70° C. for 2 h. After the reaction was completed, the reaction solution was cooled to room temperature and then centrifuged at 3000 rpm for 1 h. The precipitate after centrifugation was dried to obtain modified nano-silica;

[0048] (3) adding 0.1 g of the modified nano-silica to 100 g of the mixed solution obtained in step (1), and performing ultrasonic dispersion treatment at a power of 500 W for 30 min to obtain a coating solution;

[0049] (4) applying the above coating solution to the scraper surface of the screen, and then keeping the temperature at 60°C, 80°C, 100°C, and 200°C for 1 hour respectively to obtain a first film layer with a thickness of 7 μm;

[0050] (5) The above coating solution is applied to the printing surface of the screen, and a film is attached to the printing surface of the screen, and ultraviolet light (wavelength of 380-450nm) is irradiated and cured for 400s; after curing, the film is removed and the printing surface is rinsed with water to form the desired pattern, thereby obtaining a screen having a second film layer with a thickness of 10μm.

[0051] Example 2

[0052] A screen processing method for improving the performance of heterojunction solar cells comprises the following steps:

[0053] (1) 3 mmol TFMB and 3 mmol 6FDA were added to dimethylacetamide and stirred at 2000 rpm for 12 h. Then, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was added and stirred for 6 h to obtain a mixed solution.

[0054] (2) 6 g of tetraethyl orthosilicate and 150 ml of ethanol were mixed, stirred at 60° C. for 30 min, 0.5 g of APTES was added to the flask, and stirring was continued for 1 h to obtain a dispersion; 0.91 g of 6FDA was dissolved in 50 ml of a 30 v / v% ethanol solution, heated to 70° C. and hydrolyzed for 6 h to obtain a hydrolyzate; the above dispersion and hydrolyzate were mixed, 0.66 g of TFMB was added, and the mixture was stirred at 70° C. for 2 h. After the reaction was completed, the reaction solution was cooled to room temperature and then centrifuged at 3000 rpm for 1 h. The precipitate after centrifugation was dried to obtain modified nano-silica;

[0055] (3) adding 0.3 g of the modified nano-silica to 100 g of the mixed solution obtained in step (1), and performing ultrasonic dispersion treatment at a power of 500 W for 30 min to obtain a coating solution;

[0056] (4) applying the above coating solution to the scraper surface of the screen, and then keeping the temperature at 60°C, 80°C, 100°C, and 200°C for 1 hour respectively to obtain a first film layer with a thickness of 7 μm;

[0057] (5) The above coating solution is applied to the printing surface of the screen, and a film is attached to the printing surface of the screen, and ultraviolet light (wavelength of 380-450nm) is irradiated and cured for 400s; after curing, the film is removed and the printing surface is rinsed with water to form the desired pattern, thereby obtaining a screen having a second film layer with a thickness of 10μm.

[0058] Example 3

[0059] A screen processing method for improving the performance of heterojunction solar cells comprises the following steps:

[0060] (1) 3 mmol TFMB and 3 mmol 6FDA were added to dimethylacetamide and stirred at 2000 rpm for 15 h. Then, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was added and stirred for 6 h to obtain a mixed solution.

[0061] (2) 6 g of tetraethyl orthosilicate and 150 ml of ethanol were mixed, stirred at 60° C. for 30 min, 0.5 g of APTES was added to the flask, and stirring was continued for 1 h to obtain a dispersion; 0.91 g of 6FDA was dissolved in 50 ml of a 30 v / v% ethanol solution, heated to 70° C. and hydrolyzed for 6 h to obtain a hydrolyzate; the above dispersion and hydrolyzate were mixed, 0.66 g of TFMB was added, and the mixture was stirred at 70° C. for 2 h. After the reaction was completed, the reaction solution was cooled to room temperature and then centrifuged at 3000 rpm for 1 h. The precipitate after centrifugation was dried to obtain modified nano-silica;

[0062] (3) adding 0.2 g of the modified nano-silica to 100 g of the mixed solution obtained in step (1), and performing ultrasonic dispersion treatment at a power of 500 W for 30 min to obtain a coating solution;

[0063] (4) applying the above coating solution to the scraper surface of the screen, and then keeping the temperature at 60°C, 80°C, 100°C, and 200°C for 1 hour respectively to obtain a first film layer with a thickness of 7 μm;

[0064] (5) The above coating solution is applied to the printing surface of the screen, and a film is attached to the printing surface of the screen, and ultraviolet light (wavelength of 380-450nm) is irradiated and cured for 400s; after curing, the film is removed and the printing surface is rinsed with water to form the desired pattern, thereby obtaining a screen having a second film layer with a thickness of 10μm.

[0065] In order to better verify that the screen of the present invention has more excellent performance, the following is a detailed description with reference to Example 1 and combined with multiple comparative examples.

[0066] Comparative Example 1

[0067] Compared with Example 1, the difference is that no ionic liquid is added in the preparation of the composite membrane, and other conditions are the same as those in Example 1.

[0068] Comparative Example 2

[0069] Compared with Example 1, the difference is that the nano-silica is not modified in the preparation of the composite film, and the other conditions are the same as those in Example 1.

[0070] Comparative Example 3

[0071] Compared with Example 1, the difference is that no modified nano-silica is added in the preparation of the composite membrane, and other conditions are the same as those in Example 1.

[0072] Comparative Example 4

[0073] Compared with Example 1, the difference is that modified nano-silica and ionic liquid are not added in the preparation of the composite membrane, and other conditions are the same as those in Example 1.

[0074] After testing, the screen printing number of the screen prepared in the above embodiment is more than 6-8 times that of the screen in comparative example 4, and the service life reaches more than 150,000 times. The screen printing number of the screen prepared in comparative example 1 is 3 times that of the screen in comparative example 4, and the service life reaches 80,000 times. The screen printing number of the screen prepared in comparative example 2 is 2 times that of the screen in comparative example 4, and the service life reaches 50,000 times. The screen printing number of the screen prepared in comparative example 3 is 1.5 times that of the screen in comparative example 4, and the service life reaches 30,000 times.

[0075] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A screen processing method for improving the performance of heterojunction solar cells, characterized in that: The following steps are involved: preparing a super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution; Apply the coating solution to the scraper surface of the screen and dry it; Apply the coating solution to the printing surface of the screen, and attach a film to the printing surface of the screen, and perform ultraviolet irradiation curing; After curing, the film is removed and the printed surface is washed with water to form the desired pattern and prepare the screen; The method for preparing the super-hydrophobic ionic liquid / silicon dioxide / polyimide composite coating solution comprises the following steps: (1) adding 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride to a solvent and stirring and mixing, then adding an ionic liquid, wherein the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and continuing to stir to obtain a mixed solution; (2) Ethyl orthosilicate and ethanol are mixed and stirred evenly, and then APTES is added and stirred continuously to obtain a dispersion; 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride is dissolved in an ethanol solution, heated and hydrolyzed, the obtained hydrolyzate and dispersion are mixed, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl is added and stirred for reaction, and after the reaction is completed, the reaction solution is filtered and the obtained precipitate is dried to obtain modified nano-silica; (3) Adding the modified nano-silica to the mixed solution prepared in step (1), and subjecting it to ultrasonic dispersion treatment to prepare a coating solution.

2. A screen processing method for improving the performance of heterojunction solar cells according to claim 1, characterized in that: In step (1), the molar ratio of the 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, and the ionic liquid is 1:1:(1-2); and / or the solvent is one of dimethylformamide and dimethylacetamide; and / or the stirring speed during the stirring and mixing is 1000-2000 rpm, and the stirring time is 10-15 h; And / or the stirring time is continued for 5-10 hours.

3. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: In step (2), the usage ratio of ethyl orthosilicate, ethanol, and APTES is (5-10) g:150 ml:(0.1-0.5) g; and / or the temperature of the mixing and stirring is 60-70° C. and the time is 20-30 min; And / or the time of continuing stirring is 1-2h.

4. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, wherein: In step (2), the concentration of the ethanol solution is 20-30 v / v%, and the ratio of the 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride to the ethanol solution is (0.5-1) g:50 ml; and / or the temperature of the hydrolysis is 65-75° C. and the time is 5-10 h; And / or the volume ratio of the hydrolyzate to the dispersion is (3-5):

1.

5. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: In step (2), the mass ratio of the 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl to the 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride is (0.5-0.8):(0.5-1); And / or the stirring reaction temperature is 60-70° C. and the time is 1-2 hours.

6. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: In step (3), the mass ratio of the modified nano-silica to the mixed solution is (0.01-0.05):

10.

7. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: The coating solution is applied to the scraper surface of the screen and the drying process specifically includes: first keeping the temperature at 60°C for 1 hour, then keeping the temperature at 80°C for 1 hour, keeping the temperature at 100°C for 1 hour, and finally keeping the temperature at 200°C for 1 hour.

8. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: The UV curing time is 200-400s.

9. The method for processing a screen for improving the performance of a heterojunction solar cell according to claim 1, characterized in that: The film thickness on the screen scraper surface is 3-8 μm, and the film thickness on the screen printing surface is 5-10 μm.