A low-temperature conductive silver paste for solar heterojunction cells and a preparation method thereof
By using additives and modified resins in conductive silver paste and introducing imide structures in combination with chemical bonds, the problem of poor performance of conductive silver paste under low temperature conditions is solved, good conductivity, viscosity and tension are achieved, and the application needs of solar heterojunction batteries are met.
Patent Information
- Application Number
- CN202311216415.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-20
- Publication Date
- 2025-04-01
AI Technical Summary
In the prior art, the conductive silver paste of solar heterojunction batteries has poor performance in conductivity, viscosity and tension under low temperature conditions, making it difficult to meet the practical application needs.
By combining additives with modified resins for the preparation of conductive silver paste, the viscosity and tension of conductive silver paste are improved, and the imide structure is introduced through chemical bonding to improve the bonding strength.
It achieves good conductivity, enhanced viscosity and tension of conductive silver paste, and meets the application needs of solar heterojunction batteries.
Smart Images
Figure BDA0004459141320000071 
Figure BDA0004459141320000081
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of conductive silver paste, and more specifically, to a low-temperature conductive silver paste for solar heterojunction cells and a preparation method thereof. Background Art
[0002] Solar heterojunction cells usually use n-type crystalline silicon as the substrate and wide-bandgap amorphous silicon as the emitter. The cell has a double-sided symmetrical structure, with two thin intrinsic amorphous silicon layers on both sides of the n-type silicon substrate, a p-type amorphous silicon emitter layer on the front, and an n-type amorphous silicon film back surface field on the back; a transparent conductive oxide film is deposited on the amorphous silicon thin layers on both sides by sputtering, and finally a conductive gate is prepared.
[0003] The traditional sputtering method for preparing conductive gates has the disadvantages of high cost, complex process, and low efficiency. However, since HIT batteries use a-si to form PN junctions, HIT batteries can be completed at low temperatures below 200°C. Therefore, the conductive gates of HIT batteries can now be prepared using silver paste through screen printing technology. The specific method is to pour the silver paste into one end of the screen printing plate, use a scraper to apply a certain pressure to the silver paste part on the screen printing plate, and move it at a uniform speed toward the other end of the screen printing plate. During the movement, the silver paste is squeezed from the mesh holes of the scraper onto the crystalline silicon to form a conductive gate of a specific shape.
[0004] The conductivity, viscosity, and tension of low-temperature conductive silver paste directly affect whether the conductive grid of HIT batteries can be used normally. The conductivity, viscosity, and tension of silver paste on the market are not very good. As we all know, conductivity is affected by the silver powder content in the silver paste. If the silver powder content is too small, it cannot form a good contact. If it is below the threshold, it cannot be conductive. If the silver powder content is too high, it is not easy to disperse and is easy to agglomerate, reducing viscosity and affecting use. In addition, because HIT batteries are completed at low temperatures below 200°C, there is no silver powder sintering process when preparing silver paste. The silver powder tension is too small, generally less than 1N. When subjected to a tension greater than 1N, it is easy to tear. The comprehensive performance is difficult to meet the needs of actual applications.
[0005] Therefore, it is necessary to prepare a low-temperature conductive silver paste whose conductivity, viscosity and tensile properties can meet the requirements for use in solar heterojunction cells. Summary of the invention
[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a low-temperature conductive silver paste for solar heterojunction cells and a preparation method thereof.
[0007] To achieve the above object, the present invention provides the following technical solutions:
[0008] A low-temperature conductive silver paste for solar heterojunction cells, comprising the following raw materials in parts by weight:
[0009] 250-450 parts of silver powder, 10-15 parts of modified resin, 10-15 parts of auxiliary agent, 1-5 parts of thixotropic agent, and 1-5 parts of dispersant.
[0010] Preferably, the preparation method of the modified resin comprises the following steps:
[0011] (1) Add maleic anhydride to toluene, heat to 40-45°C, stir to dissolve, and obtain a mixed solution.
[0012] (2) Dissolve 4,4'-diaminodiphenylmethane in N,N-dimethylformamide, then add the mixture to the system, react at 23±3°C for 2-3h, then add p-toluenesulfonic acid and dimethylacetamide, heat and reflux to react for 1-4h, cool to 23±3°C, collect the product, and dry to obtain a light yellow solid.
[0013] (3) Mix the epoxy resin with the light yellow solid, stir at 100-110°C, and after it is completely dissolved, heat to 145-155°C, react for 1-2 hours, cool and discharge the material. The product is the modified resin.
[0014] Preferably, the mass ratio of maleic anhydride to 4,4'-diaminodiphenylmethane is 2-3:1.
[0015] Preferably, the temperature of the heating reflux reaction in step (2) is 60-65° C., and the mass of the epoxy resin in step (3) is 1-3 times that of the light yellow solid.
[0016] Preferably, the preparation method of the auxiliary agent comprises the following steps:
[0017] (1) Add cellulose and sodium hydroxide solution to tetrahydrofuran, mix, pass nitrogen protection, heat to 60-70°C, stir and react for 1-2h, cool to 23±3°C, add ethyl bromide, heat to 60-70°C and react for 4-6h, after the reaction is completed, cool to 23±3°C, add acid to neutralize, distill and separate tetrahydrofuran, wash the product with water and dry to obtain an intermediate product.
[0018] (2) Dissolve soybean oil and the intermediate product in tetrahydrofuran, add sodium methoxide, raise the temperature to 50-60° C., and react under nitrogen protection. After the reaction is completed, use methanol aqueous solution to precipitate the polymer, separate and dry to obtain the additive.
[0019] Preferably, in step (1), the mass ratio of cellulose to sodium hydroxide solution is 1:3-5, the mass fraction of the sodium hydroxide solution is 40-50wt%; and the mass of ethyl bromide is 1-3 times that of cellulose.
[0020] Preferably, the mass of the intermediate product in step (2) is 2-3 times that of soybean oil; and the mass of the sodium methoxide accounts for 3-5% of that of soybean oil.
[0021] Preferably, the silver powder is a mixture of flaky micron-sized silver powder, submicron-sized spherical silver powder and nanometer-sized spherical silver powder in a mass ratio of 5-20:65-75:1-10.
[0022] The thixotropic agent is selected from one or more combinations of hydrogenated castor oil derivatives, polyamide wax, polyurea, and fumed silica.
[0023] Preferably, a method for preparing a low-temperature conductive silver paste for a solar heterojunction cell comprises the following steps:
[0024] Silver powder, additives, modified resin, thixotropic agent and dispersant are mixed, stirred and rolled into a uniform slurry using a three-roll mill, which is a low-temperature conductive silver paste for solar heterojunction cells.
[0025] Compared with the prior art, the present invention has the following beneficial effects:
[0026] The low-temperature conductive silver paste for solar heterojunction cells provided by the present invention can effectively improve the viscosity and tension of the conductive silver paste by using an auxiliary agent and a modified resin in the preparation of the conductive silver paste, and has good conductivity, and has broad application prospects. Among them, the auxiliary agent used in the present invention is prepared with cellulose, sodium hydroxide solution, and soybean oil as raw materials, which can improve the adhesion of the conductive silver paste, has low resistance, and has good conductivity. At the same time, combined with the use of the modified resin, the imide structure is introduced into the epoxy resin molecule through a chemical bond, and the imide structure has a certain polarity, which helps to improve the bonding strength, thereby further improving the conductive performance. DETAILED DESCRIPTION
[0027] The present invention will be described below in conjunction with specific implementation schemes. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Without departing from the subject matter or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made, and the compounds and related reagents used can be purchased from the market, wherein the silver powder is a mixture of flaky micron-grade silver powder (D50: 5 μm), submicron-grade spherical silver powder (D50: 0.5 μm) and nano-grade spherical silver powder (D50: 5 nm) in a mass ratio of 10:70:3, cellulose is purchased from Shandong Weifang Lite Composite Materials Co., Ltd., dispersant Silok-7423 is purchased from Foshan Shengchuangda Chemical Co., Ltd., 4,4'-diaminodiphenylmethane is purchased from Jiangsu Rayne Environmental Protection Technology Co., Ltd., and epoxy resin E51 is purchased from Weifang Fule New Materials Co., Ltd.
[0028] Embodiment 1
[0029] A low-temperature conductive silver paste for solar heterojunction cells, comprising the following raw materials in parts by weight:
[0030] 450 parts of silver powder, 15 parts of auxiliary agent, 15 parts of modified resin, 5 parts of polyamide wax, and 5 parts of dispersant.
[0031] The preparation method of the modified resin comprises the following steps:
[0032] (1) Add 100 g of maleic anhydride to 1000 g of toluene, heat to 45°C, stir to dissolve, and set aside.
[0033] (2) Dissolve 50 g of 4,4'-diaminodiphenylmethane in 1000 g of N,N-dimethylformamide, and then add the mixture to the system of step (1). React at 23°C for 2 h. Then add 5 g of p-toluenesulfonic acid and 1 g of dimethylacetamide, heat the mixture to 60°C and reflux for 1 h. Cool the mixture to 23°C, collect the product, and dry it to obtain a light yellow solid for later use.
[0034] (3) Mix 100 g of epoxy resin E51 with 100 g of the light yellow solid obtained in step (2), stir at 100° C., and after complete dissolution, heat to 145° C., react for 2 h, cool and discharge. The product is the modified resin.
[0035] The preparation method of the auxiliary agent comprises the following steps:
[0036] (1) 20 g of cellulose and 80 g of 50 wt% sodium hydroxide solution were added to 200 g of tetrahydrofuran, and the mixture was protected by nitrogen. The mixture was heated to 70° C. for reaction for 2 h. After the mixture was cooled to 23° C., 40 g of ethyl bromide was added, and the mixture was heated to 70° C. for reaction for 5 h. After the reaction was completed, the mixture was cooled to 23° C., acetic acid was added for neutralization, and tetrahydrofuran was separated by distillation. The product was washed with water and dried to obtain an intermediate product.
[0037] (2) 10 g soybean oil and 25 g intermediate product were dissolved in 200 g tetrahydrofuran, 0.5 g sodium methoxide was added, the temperature was raised to 60° C., and the reaction was carried out under nitrogen protection. After the reaction was completed, a 10 wt % methanol aqueous solution was used to precipitate the polymer, and the auxiliary agent was obtained after separation and drying.
[0038] A method for preparing low-temperature conductive silver paste for solar heterojunction cells comprises the following steps:
[0039] Silver powder, additives, modified resin, polyamide wax and dispersant are mixed, stirred and rolled into a uniform slurry using a three-roll mill, which is a low-temperature conductive silver paste for solar heterojunction cells.
[0040] Embodiment 2
[0041] A low-temperature conductive silver paste for solar heterojunction cells, comprising the following raw materials in parts by weight:
[0042] 400 parts of silver powder, 10 parts of auxiliary agent, 15 parts of modified resin, 5 parts of polyamide wax, and 5 parts of dispersant.
[0043] The preparation method of the modified resin comprises the following steps:
[0044] (1) Add 100 g of maleic anhydride to 1000 g of toluene, heat to 45°C, stir to dissolve, and set aside.
[0045] (2) Dissolve 50 g of 4,4'-diaminodiphenylmethane in 1000 g of N,N-dimethylformamide, and then add the mixture to the system of step (1). React at 23°C for 2 h. Then add 5 g of p-toluenesulfonic acid and 1 g of dimethylacetamide, heat the mixture to 60°C and reflux for 1 h. Cool the mixture to 23°C, collect the product, and dry it to obtain a light yellow solid for later use.
[0046] (3) Mix 100 g of epoxy resin E51 with 100 g of the light yellow solid obtained in step (2), stir at 100° C., and after complete dissolution, heat to 145° C., react for 2 h, cool and discharge. The product is the modified resin.
[0047] The preparation method of the auxiliary agent comprises the following steps:
[0048] (1) 20 g of cellulose and 80 g of 50 wt% sodium hydroxide solution were added to 200 g of tetrahydrofuran, and the mixture was protected by nitrogen. The mixture was heated to 70° C. for reaction for 2 h. After the mixture was cooled to 23° C., 40 g of ethyl bromide was added, and the mixture was heated to 70° C. for reaction for 5 h. After the reaction was completed, the mixture was cooled to 23° C., acetic acid was added for neutralization, and tetrahydrofuran was separated by distillation. The product was washed with water and dried to obtain an intermediate product.
[0049] (2) 10 g soybean oil and 25 g intermediate product were dissolved in 200 g tetrahydrofuran, 0.5 g sodium methoxide was added, the temperature was raised to 60° C., and the reaction was carried out under nitrogen protection. After the reaction was completed, a 10 wt % methanol aqueous solution was used to precipitate the polymer, and the auxiliary agent was obtained after separation and drying.
[0050] A method for preparing low-temperature conductive silver paste for solar heterojunction cells comprises the following steps:
[0051] Silver powder, additives, modified resin, polyamide wax and dispersant are mixed, stirred and rolled into a uniform slurry using a three-roll mill, which is a low-temperature conductive silver paste for solar heterojunction cells.
[0052] Embodiment 3
[0053] A low-temperature conductive silver paste for solar heterojunction cells, comprising the following raw materials in parts by weight:
[0054] 260 parts of silver powder, 10 parts of auxiliary agent, 10 parts of modified resin, 1 part of polyamide wax, and 1 part of dispersant.
[0055] The preparation method of the modified resin comprises the following steps:
[0056] (1) Add 100 g of maleic anhydride to 1000 g of toluene, heat to 45°C, stir to dissolve, and set aside.
[0057] (2) Dissolve 50 g of 4,4'-diaminodiphenylmethane in 1000 g of N,N-dimethylformamide, and then add the mixture to the system of step (1). React at 23°C for 2 h. Then add 5 g of p-toluenesulfonic acid and 1 g of dimethylacetamide, heat the mixture to 60°C and reflux for 1 h. Cool the mixture to 23°C, collect the product, and dry it to obtain a light yellow solid for later use.
[0058] (3) Mix 100 g of epoxy resin E51 with 100 g of the light yellow solid obtained in step (2), stir at 100° C., and after complete dissolution, heat to 145° C., react for 2 h, cool and discharge. The product is the modified resin.
[0059] The preparation method of the auxiliary agent comprises the following steps:
[0060] (1) 20 g of cellulose and 80 g of 50 wt% sodium hydroxide solution were added to 200 g of tetrahydrofuran, and the mixture was stirred with nitrogen gas. The mixture was heated to 70° C. for reaction for 2 h. After the mixture was cooled to 233° C., 40 g of ethyl bromide was added. The mixture was heated to 70° C. for reaction for 5 h. After the reaction was completed, the mixture was cooled to 23° C., acetic acid was added for neutralization, and tetrahydrofuran was separated by distillation. The product was washed with water and dried to obtain an intermediate product.
[0061] (2) 10 g soybean oil and 25 g intermediate product were dissolved in 200 g tetrahydrofuran, 0.5 g sodium methoxide was added, the temperature was raised to 60° C., and the reaction was carried out under nitrogen protection. After the reaction was completed, a 10 wt % methanol aqueous solution was used to precipitate the polymer, and the auxiliary agent was obtained after separation and drying.
[0062] A method for preparing low-temperature conductive silver paste for solar heterojunction cells comprises the following steps:
[0063] Silver powder, additives, modified resin, polyamide wax and dispersant are mixed, stirred and rolled into a uniform slurry using a three-roll mill, which is a low-temperature conductive silver paste for solar heterojunction cells.
[0064] Comparative Example 1
[0065] The difference from Example 1 is that no auxiliary agent is added.
[0066] Comparative Example 2
[0067] The difference from Example 1 is that no modified resin is added.
[0068] Comparative Example 3
[0069] The difference from Example 1 is that the modified resin is replaced by epoxy resin E51.
[0070] Comparative Example 4
[0071] The difference from Example 1 is that the auxiliary agent is replaced by cellulose.
[0072] The performance of the low-temperature conductive silver paste for solar heterojunction cells prepared in each embodiment and comparative example was tested, and the test method was as follows:
[0073] Resistivity: measured in accordance with standard GB / T1410-2006;
[0074] Tensile force: measured using a tensile testing machine.
[0075] Viscosity: measured using a Brookfield viscometer.
[0076] The measurement results are shown in Table 1:
[0077] Table 1
[0078]
[0079]
[0080] By comparing the test results of the embodiments in Table 1 with the comparative examples, it can be seen that the low-temperature conductive silver paste for solar heterojunction cells provided by the present invention can effectively improve the viscosity and tensile force of the conductive silver paste by using additives and modified resins for preparation, and has good conductivity and broad application prospects.
[0081] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.
Claims
1. A low-temperature conductive silver paste for solar heterojunction cells, characterized in that: The invention comprises the following raw materials in parts by weight: 250-450 parts of silver powder, 10-15 parts of modified resin, 10-15 parts of auxiliary agent, 1-5 parts of thixotropic agent, and 1-5 parts of dispersant.
2. The low-temperature conductive silver paste for solar heterojunction cells according to claim 1, characterized in that: The preparation method of the modified resin comprises the following steps: (1) adding maleic anhydride to toluene, heating to 40-45° C., stirring to dissolve, and obtaining a mixed solution; (2) Dissolve 4,4'-diaminodiphenylmethane in N,N-dimethylformamide, then add the mixture to the system, react at 23±3°C for 2-3h, then add p-toluenesulfonic acid and dimethylacetamide, heat and reflux for 1-4h, cool to 23±3°C, collect the product, and dry to obtain a light yellow solid; (3) Mix the epoxy resin with the light yellow solid, stir at 100-110°C, and after it is completely dissolved, heat to 145-155°C, react for 1-2 hours, cool and discharge the material. The product is the modified resin.
3. The low-temperature conductive silver paste for solar heterojunction cells according to claim 2, characterized in that: The mass ratio of maleic anhydride to 4,4'-diaminodiphenylmethane is 2-3:
1.
4. The low-temperature conductive silver paste for solar heterojunction cells according to claim 2, characterized in that: The temperature of the heating reflux reaction in step (2) is 60-65° C., and the mass of the epoxy resin in step (3) is 1-3 times that of the light yellow solid.
5. The low-temperature conductive silver paste for solar heterojunction cells according to claim 1, characterized in that: The preparation method of the auxiliary agent comprises the following steps: (1) Add cellulose and sodium hydroxide solution to tetrahydrofuran, mix, pass nitrogen protection, heat to 60-70°C, stir and react for 1-2h, add ethyl bromide after cooling to 23±3°C, heat to 60-70°C and react for 4-6h, after the reaction is completed, cool to 23±3°C, add acid to neutralize, distill and separate tetrahydrofuran, wash the product with water and dry to obtain an intermediate product; (2) Dissolve soybean oil and the intermediate product in tetrahydrofuran, add sodium methoxide, raise the temperature to 50-60° C., and react under nitrogen protection. After the reaction is completed, use methanol aqueous solution to precipitate the polymer, separate and dry to obtain the additive.
6. The low-temperature conductive silver paste for solar heterojunction cells according to claim 5, characterized in that: In step (1), the mass ratio of cellulose to sodium hydroxide solution is 1:3-5, the mass fraction of the sodium hydroxide solution is 40-50wt%; and the mass of ethyl bromide is 1-3 times that of cellulose.
7. The low-temperature conductive silver paste for solar heterojunction cells according to claim 5, characterized in that: The mass of the intermediate product in step (2) is 2-3 times that of soybean oil; the mass of the sodium methoxide accounts for 3-5% of that of soybean oil.
8. The low-temperature conductive silver paste for solar heterojunction cells according to claim 1, characterized in that: The silver powder is a mixture of flaky micron-sized silver powder, submicron-sized spherical silver powder and nanometer-sized spherical silver powder in a mass ratio of 5-20:65-75:1-10; The thixotropic agent is selected from one or more combinations of hydrogenated castor oil derivatives, polyamide wax, polyurea, and fumed silica.
9. A method for preparing a low-temperature conductive silver paste for a solar heterojunction cell, comprising preparing a low-temperature conductive silver paste for a solar heterojunction cell as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: Silver powder, additives, modified resin, thixotropic agent and dispersant are mixed, stirred and rolled into a uniform slurry using a three-roll mill, which is a low-temperature conductive silver paste for solar heterojunction cells.