Glass frit for silver paste and method for preparing the same

Abstract

The application discloses a glass powder for silver paste and a preparation method thereof, and comprises glass powder A, glass powder B and a modified coupling agent; the glass powder A comprises oxide powder; the glass powder B is prepared by electroless silver plating on the surface of the glass powder A; and the modified coupling agent has the structure shown in formula I. The glass powder for silver paste is prepared by the following steps: (1) uniformly mixing the glass powder A, the modified coupling agent and deionized water, filtering, washing, drying and reserving; (2) uniformly mixing the glass powder B, the modified coupling agent and deionized water, filtering, washing, drying and reserving; and (3) mixing the products of the steps (1) and (2) and crushing, so that the particle size is D50=200-500 nm, thereby obtaining the glass powder for silver paste. The glass powder for silver paste has excellent dispersibility, can enhance the printing performance of the silver paste and can significantly improve the photoelectric conversion efficiency of a battery.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a glass powder for silver paste and its preparation method. Background Technology

[0002] Since the invention of solar cells, crystalline silicon solar cells have been widely used, with their conversion efficiency continuously improving and production costs steadily decreasing. The important role of crystalline silicon solar cells as a clean energy source in changing the energy structure and alleviating environmental pressures is becoming increasingly prominent.

[0003] Based on the doping type of the substrate, crystalline silicon solar cells are classified into P-type and N-type crystalline silicon solar cells. Compared with P-type crystalline silicon solar cells, N-type crystalline silicon solar cells have higher conversion efficiency and impurity tolerance, and virtually no light-induced degradation. Because N-type crystalline silicon has a longer minority carrier lifetime than P-type crystalline silicon, N-type crystalline silicon cells can often be fabricated into bifacial PERC cells to increase the cell's output power, typically by more than 20%.

[0004] Bifacial PERC solar cells are a special type of crystalline silicon solar cell. Their main characteristic is the addition of one or more passivation film structures on both the front and back sides of the cell, based on silver paste. The front electrode, formed by sintering the silver paste printed on the front side of the cell, serves to collect current. The conductive electrode paste for solar cells is a homogeneous suspension system composed of inorganic solid particles such as aluminum powder, silver powder, glass powder, and additives dispersed in an organic carrier. The physicochemical properties of the inorganic phases, including aluminum powder, silver powder, glass powder, and additives, are the most important factors determining the sintering behavior and ohmic contact performance of the paste. The organic carrier primarily imparts suitable viscosity and rheological properties to the paste, making it suitable for printing. Although glass powder constitutes a small proportion of the conductive silver paste, it plays a crucial role in etching the silicon nitride and silicon wafer, and in bonding the silver film and silicon wafer. After the organic carrier evaporates, the glass powder softens into molten glass, wetting the silver particles and silicon wafer surfaces. This effectively reduces the surface tension of the molten metal and increases the surface contact between the silver particles and the silicon wafer.

[0005] With improvements in solar cell structures and advancements in screen printing technology, more specific requirements are being placed on the paste. The reduction in grid line width and the increase in aspect ratio necessitate stricter requirements on powder particle size. As the powder particle size decreases, the surface energy increases, making it prone to agglomeration under current processing techniques. This results in uneven distribution of the powder in the paste, affecting the printing performance of the silver paste and further hindering the improvement of the photoelectric conversion efficiency of the resulting solar cells.

[0006] Therefore, there is an urgent need for a glass powder for silver paste that has excellent dispersibility, can enhance the printing performance of silver paste, and can significantly improve the photoelectric conversion efficiency of batteries. Summary of the Invention

[0007] Purpose of the invention: In view of the deficiencies of the prior art, the purpose of this invention is to provide a glass powder for silver paste with excellent dispersibility, which can enhance the printing performance of silver paste and significantly improve the photoelectric conversion efficiency of batteries, and a method for preparing the same.

[0008] Technical solution:

[0009] A glass powder for silver paste, comprising glass powder A, glass powder B and a modified coupling agent;

[0010] The glass powder A comprises oxide powder;

[0011] The glass powder B is obtained by chemically plating silver onto the surface of glass powder A;

[0012] The modified coupling agent has the structure shown in Formula I:

[0013]

[0014] In this invention, glass powder B is doped with glass powder. Glass powder B is obtained by chemically plating silver onto the surface of glass powder. A layer of nano-sized silver particles is coated on the surface of the glass powder. On the one hand, this can reduce the softening temperature of the glass powder, improve wettability, and increase the density of the thick film of the battery. On the other hand, it can form a good ohmic contact and deposit more silver crystals at the silver-silicon interface, which can significantly improve the photoelectric conversion efficiency of the solar cell.

[0015] Furthermore, the modified coupling agent is prepared through the following steps:

[0016] (1) In a reactor, 5-methoxy-1-indanone, xylene, water and 1-aminopentane are added, heated to 75-85°C, reacted for 1-2 hours, cooled, filtered, washed and dried to obtain an intermediate;

[0017] (2) In a reactor, 1,1,1,3,5,5,5-heptamethyltrisiloxane and intermediates are added in sequence, a protective gas is introduced, the temperature is raised to 80-100℃ and stirred for 30-40 minutes, a catalyst is added and the reaction is kept at the temperature for 3-4 hours, and low-boiling substances are removed under vacuum at 85-90℃ and 50-60kPa for 30-45 minutes. After cooling, a light yellow liquid is obtained, which is the modified coupling agent.

[0018] In this invention, a modified coupling agent is prepared. The indene ring structure and multi-branched silane structure in its structure can enhance the surface treatment performance of the coupling agent and provide excellent high-temperature resistance. In addition, the silicon dioxide formed after sintering decomposition reduces corrosion of the passivation layer and improves the opening voltage.

[0019] Further, in step (1), the mass ratio of 5-methoxy-1-indanone to 1-aminopentane is 1.8-2.2:1; in step (2), the mass ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to the intermediate is 1:1.1-1.2.

[0020] Furthermore, in step (2), the catalyst is a platinum catalyst; the effective platinum content in the catalyst is 1.0 × 10⁻⁶ of the total mass of the reactants. -5 -5.0×l0 -5 .

[0021] Further, the oxide powder comprises PbO, SiO2, B2O3, Al2O3, Bi2O3, ZnO, MgO, and Na2O; the weight parts of each component in the oxide powder are: PbO 30-60 parts, SiO2 5-15 parts, B2O3 5-10 parts, Al2O3 3-5 parts, Bi2O3 15-25 parts, ZnO 5-10 parts, MgO 5-10 parts, and Na2O 1-10 parts.

[0022] Further, the glass powder A is prepared by the following steps: weighing PbO, SiO2, B2O3, Al2O3, Bi2O3, ZnO, MgO and Na2O in proportion, dispersing them evenly, melting and quenching them, performing air jet milling and sand milling, sieving and standing, removing the upper clear liquid, drying and pulverizing to obtain the glass powder A.

[0023] Furthermore, the glass powder B is prepared through the following steps:

[0024] (1) In the reactor, silver nitrate is dissolved in ethylene glycol, glass powder A is added, and then ultrasonic and mechanically stirred for 30-50 minutes before use.

[0025] (2) Heat the reactor from step (1) to 70-80°C, stir for 1-2 hours, filter, wash and dry to obtain the glass powder B.

[0026] In this invention, surface treatment of glass powder A and glass powder B using a modified coupling agent can significantly improve the problem of agglomeration of glass powder A and glass powder B due to their small particle size. Furthermore, it can solve the problem of poor compatibility and uneven dispersion of glass powder B with glass powder A after surface silver plating. Additionally, it can improve the bonding degree between the glass powder and the silver powder in the silver paste, enhance the printing performance of the silver paste, promote the formation of dense electrode films and good ohmic contacts, and improve the photoelectric conversion efficiency of solar cells.

[0027] Furthermore, the mass ratio of the glass powder to silver nitrate is 10:0.8-1.2.

[0028] Further, the mass ratio of glass powder A, glass powder B and modified coupling agent is (15-25):(2-4):(0.3-0.5).

[0029] The preparation method of glass powder for silver paste described above includes the following steps:

[0030] (1) After mixing glass powder A, modified coupling agent and deionized water evenly, filter, wash and dry for later use;

[0031] (2) After mixing glass powder B, modified coupling agent and deionized water evenly, filter, wash and dry for later use;

[0032] (3) The products of steps (1) and (2) are mixed and pulverized until the particle size is D50 = 200-500nm, so as to obtain the glass powder for silver paste.

[0033] Further, the mass ratio of glass powder A to modified coupling agent is (15-25):(0.2-0.3); the mass ratio of glass powder B to modified coupling agent is (2-4):(0.1-0.2).

[0034] Beneficial effects:

[0035] (1) The glass powder for silver paste provided by the present invention is doped with glass powder B. Glass powder B is obtained by chemically plating silver on the surface of glass powder. A layer of nano-sized silver particles is plated on the surface of the glass powder. On the one hand, it can reduce the softening temperature of the glass powder, improve the wetting performance, and increase the density of the battery thick film. On the other hand, it can form a good ohmic contact and deposit more silver crystals at the silver-silicon interface, which can significantly improve the photoelectric conversion efficiency of the solar cell.

[0036] (2) The modified coupling agent prepared in the glass powder for silver paste provided by the present invention has an indene ring structure and a multi-branched silane structure that can enhance the surface treatment performance of the coupling agent and provide excellent high-temperature resistance. In addition, after sintering and decomposition, silicon dioxide is formed, which reduces the corrosion of the passivation layer and improves the opening voltage.

[0037] (3) The glass powder for silver paste provided by the present invention is surface treated with a modified coupling agent to treat glass powder A and glass powder B. On the one hand, it can significantly improve the problem that glass powder A and glass powder B are prone to agglomeration due to their small particle size; on the other hand, it can solve the problem that glass powder B has poor compatibility with glass powder A after surface silvering and cannot be uniformly dispersed; and it can improve the degree of bonding between glass powder and silver powder in silver paste, improve the printing performance of silver paste, promote the formation of dense electrode thick film and good ohmic contact, and improve the photoelectric conversion efficiency of solar cells. Detailed Implementation

[0038] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0039] The platinum catalyst, 965005, purchased from Bailingwei Technology Co., Ltd., was diluted to a mass fraction of 4.0 × 10⁻⁶. -3 The commercially available glass powder was purchased from Guizhou Baibo New Material Technology Co., Ltd. as BYBP-1; the other reagents and equipment were conventional reagents and equipment in this technical field.

[0040] Preparation of modified coupling agents

[0041] The modified coupling agent was prepared by the following steps:

[0042] (1) Add 10g of 5-methoxy-1-indanone to a four-necked flask equipped with a stirrer, reflux separator, thermocouple and feeding funnel, then add 30ml xylene, 20ml water and 5g of 1-aminopentane to the flask, stir evenly, heat to 85℃, react for 2 hours, cool, filter, wash and dry to obtain the intermediate;

[0043] (2) In a three-necked flask equipped with a stirrer, thermometer and reflux condenser, 10g of 1,1,1,3,5,5,5-heptamethyltrisiloxane and 12g of intermediate were added in sequence. Nitrogen gas was introduced, the temperature was raised to 90℃ and stirred for 30 minutes. Then, 0.2mL of platinum catalyst was added and the reaction was kept at the temperature for 3-4 hours. Low-boiling substances were removed under vacuum at 90℃ and 60kPa for 45 minutes. After cooling, a light yellow liquid was obtained, which is the modified coupling agent.

[0044] Mass spectrometry data of the product: The product was analyzed by LC-MS, and the m / z of the product was 453.26 (100.0%), 454.27 (40.5%), 455.26 (17.8%), 456.27 (4.5%), and 457.26 (1.0%).

[0045] Preparation of glass powder A:

[0046] Glass powder A is prepared by the following steps:

[0047] Weigh out 60 parts of PbO, 15 parts of SiO2, 10 parts of B2O3, 5 parts of Al2O3, 25 parts of Bi2O3, 10 parts of ZnO, 10 parts of MgO, and 5 parts of N2O according to the following weight proportions. Disperse them evenly, melt them, quench and cool them, and then perform air jet milling and sand milling. After sieving, let them stand, remove the supernatant, dry them, and pulverize them to obtain the glass powder A.

[0048] Preparation of glass powder B

[0049] Glass powder B is prepared by the following steps:

[0050] (1) In the reactor, 1g of silver nitrate was dissolved in 30mL of ethylene glycol, 10g of glass powder A was added, and the mixture was sonicated and mechanically stirred for 45 minutes before use.

[0051] (2) The reactor from step (1) is heated to 75°C, stirred for 2 hours, filtered, washed and dried to obtain the glass powder B.

[0052] Example 1

[0053] Glass powder for silver paste is prepared by the following steps:

[0054] (1) Mix 25g of glass powder A, 0.3g of modified coupling agent and 50mL of deionized water evenly, filter, wash and dry, and set aside for later use;

[0055] (2) Mix 4g of glass powder B, 0.2g of modified coupling agent and 20mL of deionized water evenly, then filter, wash and dry for later use;

[0056] (3) The products of step (1) and step (2) are mixed and pulverized until the particle size is D50 = 500 nm to obtain the glass powder for silver paste.

[0057] Example 2

[0058] The process is basically the same as in Example 1, except that step (1) is changed to 20g of glass powder A and 0.25g of modified coupling agent; and step (2) is changed to 3g of glass powder B and 0.15g of modified coupling agent.

[0059] Example 3

[0060] The process is basically the same as in Example 1, except that step (1) is changed to 15g of glass powder A and 0.2g of modified coupling agent; and step (2) is changed to 2g of glass powder B and 0.1g of modified coupling agent.

[0061] Comparative Example 1

[0062] Commercially available glass powder.

[0063] Comparative Example 2

[0064] Glass powder A and glass powder B are mixed and pulverized until the particle size is D50 = 500 nm to obtain glass powder.

[0065] Comparative Example 3

[0066] The process is basically the same as in Example 1, except that step (1) is omitted and the product of step (1) in step (3) is replaced with an equal amount of glass powder A.

[0067] Comparative Example 4

[0068] The process is basically the same as in Example 1, except that step (2) is omitted and the product of step (2) in step (3) is replaced with an equal amount of glass powder B.

[0069] Comparative Example 5

[0070] The process is basically the same as in Example 1, except that the modified coupling agent is replaced with an equal amount of γ-aminopropyltriethoxysilane.

[0071] Performance testing

[0072] The glass powders obtained in Examples 1-3 and Comparative Examples 1-5 were used to prepare conductive silver paste. The conductive silver paste was composed of the following components in the following mass ratio: 85% silver powder, 3% aluminum powder, 3% glass powder, and 9% organic binder.

[0073] Dispersion test: The fineness of the scraper used to prepare the conductive silver paste was tested using a scraper fineness meter.

[0074] The conductive silver paste prepared above was printed onto the front surface of an N-type PERC solar cell using the same construction process and then tested.

[0075] Contact resistance testing: The commonly used TLM (Line Transmission Line Model) is selected to test the contact resistance.

[0076] Photovoltaic conversion efficiency testing: The photovoltaic conversion efficiency of the cell was tested using the TMC-PV1A solar cell tester to detect the IV curve.

[0077] The test results are shown in the table below:

[0078]

[0079]

[0080] According to the comparison of the test results of Examples 1-3 and Comparative Example 1, the glass powder for silver paste provided by the present invention has excellent dispersibility compared with commercially available glass powder, which can enhance the printing performance of silver paste and significantly improve the photoelectric conversion efficiency of solar cells.

[0081] According to the comparison of the test results of Examples 1-3 and Comparative Examples 2-4, the glass powder for silver paste provided by the present invention can solve the problem of easy agglomeration of glass powder by surface treatment of glass powder A and glass powder B with a modified coupling agent, improve the dispersibility between glass powder A and glass powder B, enhance the printing performance of silver paste, and improve the photoelectric conversion efficiency of solar cells.

[0082] According to the comparison of the test results of Examples 1-3 and Comparative Example 5, the modified coupling agent added to the glass powder for silver paste provided by the present invention has an indene ring structure and a multi-branched silane structure that can enhance the surface treatment performance of the coupling agent. It has a better surface treatment capability than the coupling agent in the prior art and can significantly improve the dispersibility of glass powder and the printing performance of silver paste.

[0083] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A glass powder for silver paste, characterized in that, It contains glass powder A, glass powder B, and a modified coupling agent; The glass powder A comprises oxide powder; The glass powder B is obtained by chemically plating silver onto the surface of glass powder A; The modified coupling agent has the structure shown in Formula I: ； The oxide powder comprises PbO, SiO2, B2O3, Al2O3, Bi2O3, ZnO, MgO, and Na2O; the weight parts of each component in the oxide powder are: PbO 30-60 parts, SiO2 5-15 parts, B2O3 5-10 parts, Al2O3 3-5 parts, Bi2O3 15-25 parts, ZnO 5-10 parts, MgO 5-10 parts, and Na2O 1-10 parts. In silver paste, glass powder A and glass powder B are surface-treated using a modified coupling agent.

2. The glass powder for silver paste according to claim 1, characterized in that, The modified coupling agent is prepared by the following steps: (1) In a reactor, 5-methoxy-1-indanone, xylene, water and 1-aminopentane are added, heated to 75-85°C, reacted for 1-2 hours, cooled, filtered, washed and dried to obtain an intermediate; (2) In the reactor, 1,1,1,3,5,5,5-heptamethyltrisiloxane and intermediate are added in sequence, protective gas is introduced, the temperature is raised to 80-100℃ and stirred for 30-40 minutes, then the catalyst is added and the reaction is kept at the temperature for 3-4 hours. Low boiling substances are removed under vacuum at 85-90℃ and 50-60kPa for 30-45 minutes. After cooling, a light yellow liquid is obtained, which is the modified coupling agent.

3. The glass powder for silver paste according to claim 2, characterized in that, In step (1), the mass ratio of 5-methoxy-1-indanone to 1-aminopentane is 1.8-2.2:1; in step (2), the mass ratio of 1,1,1,3,5,5,5-heptamethyltrisiloxane to the intermediate is 1:1.1-1.

2.

4. The glass powder for silver paste according to claim 2, characterized in that, In step (2), the catalyst is a platinum catalyst; the effective platinum content in the catalyst is 1.0 × 10⁻⁶ of the total mass of the reactants. -5 -5.0×l0 -5 .

5. The glass powder for silver paste according to claim 1, characterized in that, The glass powder A is prepared by the following steps: PbO, SiO2, B2O3, Al2O3, Bi2O3, ZnO, MgO and Na2O are weighed in proportion, dispersed evenly, melted and quenched and cooled, subjected to air jet milling and sand milling, sieved and allowed to stand, the upper clear liquid is removed and then dried and pulverized to obtain the glass powder A.

6. The glass powder for silver paste according to claim 1, characterized in that, The glass powder B is prepared by the following steps: (1) In the reactor, silver nitrate is dissolved in ethylene glycol, glass powder A is added, and then ultrasonic and mechanically stirred for 30-50 minutes before use; (2) Heat the reactor from step (1) to 70-80°C, stir for 1-2 hours, filter, wash and dry to obtain the glass powder B.

7. The glass powder for silver paste according to claim 6, characterized in that, The mass ratio of the glass powder to silver nitrate is 10:0.8-1.

2.

8. The glass powder for silver paste according to claim 1, characterized in that, The mass ratio of glass powder A, glass powder B and modified coupling agent is (15-25):(2-4):(0.3-0.5).

9. A method for preparing the glass powder for silver paste according to any one of claims 1-8, characterized in that, Includes the following steps: (1) After mixing glass powder A, modified coupling agent and deionized water evenly, filter, wash and dry for later use; (2) After mixing glass powder B, modified coupling agent and deionized water evenly, filter, wash and dry for later use; (3) The products of step (1) and step (2) are mixed and crushed until the particle size is D50=200-500nm to obtain the glass powder for silver paste.

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