Conductive silver paste for photovoltaic cells and method for preparing the same

Abstract

The application discloses a conductive silver paste for photovoltaic cells and a preparation method thereof. The conductive silver paste comprises the following raw materials in percentage: 65-85% of silver powder and 1-3% of modified binder, and the rest is an organic carrier. In the printing process of the conductive silver paste, the substances in the organic carrier contact the silver powder, so that the silver chelate in the organic carrier is fully contacted, and then a stable conductive path can be formed during baking. The modified binder is a lead-free glass formed by taking bismuth trioxide as a main raw material to form a bismuth-based glass. The addition of calcium fluoride in the raw material can reduce the water absorption of the bismuth-based glass, thereby ensuring the stability of the resistivity. The addition of titanium dioxide can exist in a quadruple coordination form, so that the Si-O-Si bond in the glass is changed into a Si-O-Ti bond, thereby forming an interconnected tetrahedral structure, increasing the network connectivity of the glass, and simultaneously increasing the antireflection effect of the glass and the utilization rate of light energy.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell manufacturing technology, specifically to a conductive silver paste for photovoltaic cells and its preparation method. Background Technology

[0002] Photovoltaic cells, as a significant representative of renewable energy, have become a crucial technology for addressing energy shortages and mitigating environmental pollution. With the increasing global demand for clean energy, the research and application of photovoltaic cells have made substantial progress. Conductive silver paste, a vital component of photovoltaic cells, plays a crucial role in improving cell performance. Conductive silver paste is a conductive colloidal solution formed by dispersing silver particles in a stable solvent. It possesses excellent conductivity, photoelectric properties, and chemical stability, making it suitable for various types of photovoltaic cells. Conductive silver paste mainly consists of silver powder, glass binder, and organic carrier. Currently, in the manufacturing process of photovoltaic cells, the presence of lead in the conductive silver paste makes it corrosive, thus affecting the stability of the cell. Some photovoltaic cells use bismuth-based glass instead of lead-based glass to reduce corrosivity; however, bismuth-based glass is hygroscopic, absorbing moisture from the air during use, leading to resistivity fluctuations and affecting conversion efficiency, thus limiting the conversion of light energy. Summary of the Invention

[0003] The purpose of this invention is to provide a conductive silver paste for photovoltaic cells and its preparation method, thereby solving the problem of low conversion efficiency in photovoltaic cells at present.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing conductive silver paste for photovoltaic cells specifically includes the following steps:

[0006] Weigh out the following percentages of raw materials: 65-85% silver powder and 1-3% modified binder, with the remainder being an organic carrier. Grind and blend the raw materials to obtain conductive silver paste for photovoltaic cells.

[0007] Furthermore, the silver powder has a particle size of 2-2.5 μm.

[0008] Furthermore, the organic carrier is prepared by the following steps:

[0009] Step A1: N-hydroxyphthalimide, copper chloride, sodium hypochlorite and deionized water are mixed evenly. Under the conditions of 200-300 r / min and 60-65℃, cellulose is added while stirring and the reaction is carried out for 1-1.5 h. The filtrate is filtered to remove the filtrate and carboxylated cellulose is obtained. Carboxylated cellulose, diethanolamine, dicyclohexylcarbodiimide and dimethyl sulfoxide are mixed and reacted under the conditions of 150-200 r / min and 40-50℃ for 3-5 h to obtain pretreated cellulose.

[0010] Step A2: Mix pretreated cellulose, epichlorohydrin, boron trifluoride ether, and dimethyl sulfoxide evenly. React at 60-80 r / min and 65-70℃ for 2-3 hours. Add sodium hydroxide solution, raise the temperature to 75-80℃, and continue the reaction for 3-4 hours to obtain epoxy cellulose. Mix epoxy cellulose, iminodiacetic acid, and dimethyl sulfoxide evenly. React at 120-150 r / min, 50-60℃, and pH 9-10 for 4-6 hours. Adjust the pH to 6 to obtain modified cellulose.

[0011] Step A3: Weigh the following raw materials in parts by weight: 65-80 parts terpineol, 20-25 parts butyl carbitol acetate, 1-3 parts ethyl cellulose, 3-5 parts modified fiber, 0.5-1 parts tributyl phosphate, 0.5-1 parts methacryloyloxypropyltrimethoxysilane, 1-3 parts soybean lecithin, 1-3 parts stearamide, and 3-5 parts silver nitrate solution. Stir the raw materials at a speed of 300-500 r / min and a temperature of 40-50℃ for 8-10 hours to obtain the organic carrier.

[0012] Furthermore, the ratio of N-hydroxyphthalimide, copper chloride, sodium hypochlorite, deionized water and cellulose in step A1 is 10 mmol:10 mmol:50 mmol:100 mL:5 g, and the molar ratio of carboxyl group, diethanolamine and dicyclohexylcarbodiimide on carboxylated cellulose is 1:1:1.1.

[0013] Furthermore, in step A2, the ratio of the amount of hydroxyl groups on the pretreated cellulose, epichlorohydrin, boron trifluoride ether, dimethyl sulfoxide, and sodium hydroxide solution is 200 mmol: 200 mmol: 0.9 g: 80 mL: 15 mL, the mass fraction of the sodium hydroxide solution is 25%, and the molar ratio of the epoxy groups on the epoxy cellulose to iminodiacetic acid is 1:1.

[0014] Furthermore, the silver nitrate solution described in step A3 has a mass fraction of 2%.

[0015] Furthermore, the modified adhesive is prepared by the following steps:

[0016] Step B1: Weigh the following raw materials in parts by weight: 50-60 parts bismuth trioxide, 8-10 parts boric acid, 3-5 parts zinc oxide, 3-5 parts barium oxide, 1-3 parts strontium oxide, 5-10 parts titanium dioxide, 5-10 parts silicon dioxide, and 1-3 parts calcium fluoride;

[0017] Step B2: Mix the raw materials with anhydrous ethanol, sonicate at a frequency of 40-50kHz for 10-15 minutes, stir at a speed of 300-500r / min for 2-3 hours, grind and mix evenly to obtain composite raw material powder.

[0018] Step B3: Add the composite raw material powder to a muffle furnace, heat it to 400-420℃ at a heating rate of 5℃ / min, hold it for 30-40min, then heat it to 1400-1600℃ at a heating rate of 10℃ / min, hold it for 30-40min, cool and grind it through a 400-mesh sieve to obtain the modified binder.

[0019] Furthermore, the ratio of the raw material to anhydrous ethanol mentioned in step B2 is 1g:5mL.

[0020] The beneficial effects of this invention are as follows: This invention discloses a conductive silver paste for photovoltaic cells comprising the following raw materials: silver powder, modified binder, and organic carrier. The organic carrier is prepared by oxidizing cellulose to obtain carboxylated cellulose. The carboxylated cellulose and diethanolamine are reacted under the action of dicyclohexylcarbodiimide, causing the carboxyl groups on the carboxylated cellulose and the imino groups on the diethanolamine to undergo dehydration reaction, thereby obtaining pretreated cellulose. The pretreated cellulose is reacted with epichlorohydrin, causing the hydroxyl groups on the pretreated cellulose and the epoxy groups on the epichlorohydrin to react, and then the ring is closed under the action of sodium hydroxide solution to form new epoxy groups, thereby obtaining epoxy cellulose. The epoxy cellulose is reacted with iminodiacetic acid, causing the epoxy groups on the epoxy cellulose and the imino groups on the iminodiacetic acid to react, thereby obtaining modified cellulose. Then, terpineol, butyl carbitol acetate, ethyl cellulose, modified cellulose, tributyl phosphate, methacryloxypropyltrimethoxysilane, soybean lecithin, stearamide, and silver nitrate solution are added.

[0021] The modified binder is made from the following raw materials: bismuth trioxide, boric acid, zinc oxide, barium oxide, strontium oxide, titanium dioxide, silicon dioxide and calcium fluoride. The raw materials are mixed evenly and then melted in a muffle furnace to form glass, thus obtaining the modified binder.

[0022] During the blending process of organic carrier raw materials, the modified fiber molecular chain side chain contains an imine diacetic acid structure. The imine diacetic acid molecule contains one amino nitrogen and two carboxyl oxygen groups, which can provide three coordination sites for the anions in the silver nitrate solution, thereby forming a chelate. During the conductive silver paste printing process, the substances in the organic carrier come into contact with the silver powder, allowing the silver chelate in the organic carrier to fully contact, thereby forming a stable conductive path during calcination. The modified binder is lead-free glass with bismuth trioxide as the main raw material to form bismuth-based glass. The addition of calcium fluoride to the raw materials introduces fluorine, which can reduce the water absorption of bismuth-based glass, thereby ensuring the stability of resistivity. The addition of titanium dioxide will exist in a fourfold coordination form, which will transform the Si-O-Si bond in the glass into a Si-O-Ti bond, thereby forming an interconnected tetrahedral structure, increasing the network connectivity of the glass, and at the same time increasing the anti-reflection effect of the glass, increasing the utilization rate of light energy. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing conductive silver paste for photovoltaic cells, specifically including the following steps:

[0025] Weigh out the following percentages of raw materials: 65% silver powder and 1% modified binder, with the remainder being an organic carrier. Grind and blend the raw materials to obtain conductive silver paste for photovoltaic cells.

[0026] The silver powder has a particle size of 2 μm.

[0027] The organic carrier is prepared by the following steps:

[0028] Step A1: N-hydroxyphthalimide, copper chloride, sodium hypochlorite and deionized water are mixed evenly. Cellulose is added while stirring at 200 r / min and 60°C. The mixture is reacted for 1 h. The filtrate is removed by filtration to obtain carboxylated cellulose. Carboxylated cellulose, diethanolamine, dicyclohexylcarbodiimide and dimethyl sulfoxide are mixed and reacted at 150 r / min and 40°C for 3 h to obtain pretreated cellulose.

[0029] Step A2: Pretreated cellulose, epichlorohydrin, boron trifluoride ether, and dimethyl sulfoxide are mixed evenly and reacted at 60 r / min and 65°C for 2 hours. Then, sodium hydroxide solution is added, the temperature is raised to 75°C, and the reaction continues for 3 hours to obtain epoxy cellulose. Epoxy cellulose, iminodiacetic acid, and dimethyl sulfoxide are mixed evenly and reacted at 120 r / min, 50°C, and pH 9 for 4 hours. The pH is then adjusted to 6 to obtain modified cellulose.

[0030] Step A3: Weigh the following raw materials in parts by weight: 65 parts terpineol, 20 parts butyl carbitol acetate, 1 part ethyl cellulose, 3 parts modified fiber, 0.5 parts tributyl phosphate, 0.5 parts methacryloyloxypropyltrimethoxysilane, 1 part soybean lecithin, 1 part stearamide, and 3 parts silver nitrate solution. Stir the raw materials at a speed of 300 r / min and a temperature of 40℃ for 8 hours to obtain the organic carrier.

[0031] The ratio of N-hydroxyphthalimide, copper chloride, sodium hypochlorite, deionized water and cellulose in step A1 is 10 mmol:10 mmol:50 mmol:100 mL:5 g, and the molar ratio of carboxyl group, diethanolamine and dicyclohexylcarbodiimide on carboxylated cellulose is 1:1:1.1.

[0032] In step A2, the ratio of hydroxyl groups on the pretreated cellulose, epichlorohydrin, boron trifluoride ether, dimethyl sulfoxide, and sodium hydroxide solution is 200 mmol:200 mmol:0.9 g:80 mL:15 mL, the mass fraction of sodium hydroxide solution is 25%, and the molar ratio of epoxy groups on the epoxy cellulose to iminodiacetic acid is 1:1.

[0033] The silver nitrate solution described in step A3 has a mass fraction of 2%.

[0034] The modified adhesive is prepared by the following steps:

[0035] Step B1: Weigh the following raw materials in parts by weight: 50 parts bismuth trioxide, 8 parts boric acid, 3 parts zinc oxide, 3 parts barium oxide, 1 part strontium oxide, 5 parts titanium dioxide, 5 parts silicon dioxide, and 1 part calcium fluoride;

[0036] Step B2: Mix the raw materials with anhydrous ethanol, sonicate at a frequency of 40kHz for 10 minutes, stir at a speed of 300r / min for 2 hours, grind and mix evenly to obtain composite raw material powder.

[0037] Step B3: Add the composite raw material powder into a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min, hold it for 30min, then heat it to 1400℃ at a heating rate of 10℃ / min, hold it for 30min, cool and grind it through a 400-mesh sieve to obtain the modified binder.

[0038] The ratio of raw material to anhydrous ethanol used in step B2 is 1g:5mL.

[0039] Example 2: A method for preparing conductive silver paste for photovoltaic cells, specifically including the following steps:

[0040] Weigh out the following percentages of raw materials: 75% silver powder and 2% modified binder, with the remainder being an organic carrier. Grind and blend the raw materials to obtain conductive silver paste for photovoltaic cells.

[0041] The silver powder has a particle size of 2.3 μm.

[0042] The organic carrier is prepared by the following steps:

[0043] Step A1: N-hydroxyphthalimide, copper chloride, sodium hypochlorite and deionized water are mixed evenly. Cellulose is added while stirring at 200 r / min and 65°C. The mixture is reacted for 1 h. The filtrate is removed by filtration to obtain carboxylated cellulose. Carboxylated cellulose, diethanolamine, dicyclohexylcarbodiimide and dimethyl sulfoxide are mixed and reacted at 200 r / min and 45°C for 4 h to obtain pretreated cellulose.

[0044] Step A2: Pretreated cellulose, epichlorohydrin, boron trifluoride ether, and dimethyl sulfoxide are mixed evenly and reacted at 60 r / min and 70°C for 2 hours. Then, sodium hydroxide solution is added, the temperature is raised to 80°C, and the reaction continues for 3 hours to obtain epoxy cellulose. Epoxy cellulose, iminodiacetic acid, and dimethyl sulfoxide are mixed evenly and reacted at 150 r / min, 55°C, and pH 9 for 5 hours. The pH is then adjusted to 6 to obtain modified cellulose.

[0045] Step A3: Weigh the following raw materials in parts by weight: 72 parts terpineol, 23 parts butyl carbitol acetate, 2 parts ethyl cellulose, 4 parts modified fiber, 0.8 parts tributyl phosphate, 0.8 parts methacryloyloxypropyltrimethoxysilane, 2 parts soybean lecithin, 2 parts stearamide, and 4 parts silver nitrate solution. Stir the raw materials at a speed of 300 r / min and a temperature of 45℃ for 9 h to obtain the organic carrier.

[0046] The ratio of N-hydroxyphthalimide, copper chloride, sodium hypochlorite, deionized water and cellulose in step A1 is 10 mmol:10 mmol:50 mmol:100 mL:5 g, and the molar ratio of carboxyl group, diethanolamine and dicyclohexylcarbodiimide on carboxylated cellulose is 1:1:1.1.

[0047] In step A2, the ratio of hydroxyl groups on the pretreated cellulose, epichlorohydrin, boron trifluoride ether, dimethyl sulfoxide, and sodium hydroxide solution is 200 mmol:200 mmol:0.9 g:80 mL:15 mL, the mass fraction of sodium hydroxide solution is 25%, and the molar ratio of epoxy groups on the epoxy cellulose to iminodiacetic acid is 1:1.

[0048] The silver nitrate solution described in step A3 has a mass fraction of 2%.

[0049] The modified adhesive is prepared by the following steps:

[0050] Step B1: Weigh the following raw materials in parts by weight: 55 parts bismuth trioxide, 9 parts boric acid, 4 parts zinc oxide, 4 parts barium oxide, 2 parts strontium oxide, 8 parts titanium dioxide, 8 parts silicon dioxide, and 2 parts calcium fluoride;

[0051] Step B2: Mix the raw materials with anhydrous ethanol, sonicate at a frequency of 45kHz for 13 minutes, stir at a speed of 300r / min for 3 hours, grind and mix evenly to obtain composite raw material powder.

[0052] Step B3: Add the composite raw material powder into a muffle furnace, heat it to 410℃ at a heating rate of 5℃ / min, hold it for 35min, then heat it to 1500℃ at a heating rate of 10℃ / min, hold it for 35min, cool and grind it through a 400-mesh sieve to obtain the modified binder.

[0053] The ratio of raw material to anhydrous ethanol used in step B2 is 1g:5mL.

[0054] Example 3: A method for preparing conductive silver paste for photovoltaic cells, specifically including the following steps:

[0055] Weigh out the following percentages of raw materials: 85% silver powder and 3% modified binder, with the remainder being an organic carrier. Grind and blend the raw materials to obtain conductive silver paste for photovoltaic cells.

[0056] The silver powder has a particle size of 2.5 μm.

[0057] The organic carrier is prepared by the following steps:

[0058] Step A1: N-hydroxyphthalimide, copper chloride, sodium hypochlorite and deionized water are mixed evenly. Under the conditions of 300 r / min and 65℃, cellulose is added and the mixture is stirred and reacted for 1.5 h. The filtrate is filtered to remove the filtrate and carboxylated cellulose is obtained. Carboxylated cellulose, diethanolamine, dicyclohexylcarbodiimide and dimethyl sulfoxide are mixed and reacted for 5 h under the conditions of 200 r / min and 50℃ to obtain pretreated cellulose.

[0059] Step A2: Pretreated cellulose, epichlorohydrin, boron trifluoride ether, and dimethyl sulfoxide are mixed evenly and reacted at 80 r / min and 70°C for 3 hours. Then, sodium hydroxide solution is added, the temperature is raised to 80°C, and the reaction continues for 4 hours to obtain epoxy cellulose. Epoxy cellulose, iminodiacetic acid, and dimethyl sulfoxide are mixed evenly and reacted at 150 r / min, 60°C, and pH 10 for 6 hours. The pH is then adjusted to 6 to obtain modified cellulose.

[0060] Step A3: Weigh the following raw materials in parts by weight: 80 parts terpineol, 25 parts butyl carbitol acetate, 3 parts ethyl cellulose, 5 parts modified fiber, 1 part tributyl phosphate, 1 part methacryloyloxypropyltrimethoxysilane, 3 parts soybean lecithin, 3 parts stearamide, and 5 parts silver nitrate solution. Stir the raw materials at a speed of 500 r / min and a temperature of 50℃ for 10 h to obtain the organic carrier.

[0061] The ratio of N-hydroxyphthalimide, copper chloride, sodium hypochlorite, deionized water and cellulose in step A1 is 10 mmol:10 mmol:50 mmol:100 mL:5 g, and the molar ratio of carboxyl group, diethanolamine and dicyclohexylcarbodiimide on carboxylated cellulose is 1:1:1.1.

[0062] In step A2, the ratio of hydroxyl groups on the pretreated cellulose, epichlorohydrin, boron trifluoride ether, dimethyl sulfoxide, and sodium hydroxide solution is 200 mmol:200 mmol:0.9 g:80 mL:15 mL, the mass fraction of sodium hydroxide solution is 25%, and the molar ratio of epoxy groups on the epoxy cellulose to iminodiacetic acid is 1:1.

[0063] The silver nitrate solution described in step A3 has a mass fraction of 2%.

[0064] The modified adhesive is prepared by the following steps:

[0065] Step B1: Weigh the following raw materials in parts by weight: 60 parts bismuth trioxide, 10 parts boric acid, 5 parts zinc oxide, 5 parts barium oxide, 3 parts strontium oxide, 10 parts titanium dioxide, 10 parts silicon dioxide, and 3 parts calcium fluoride;

[0066] Step B2: Mix the raw materials with anhydrous ethanol, sonicate at a frequency of 50kHz for 15 minutes, stir at a speed of 500r / min for 3 hours, grind and mix evenly to obtain composite raw material powder.

[0067] Step B3: Add the composite raw material powder into a muffle furnace, heat it to 420℃ at a heating rate of 5℃ / min, hold it for 40min, then heat it to 1600℃ at a heating rate of 10℃ / min, hold it for 40min, cool and grind it through a 400-mesh sieve to obtain the modified binder.

[0068] The ratio of raw material to anhydrous ethanol used in step B2 is 1g:5mL.

[0069] Comparative Example 1: This comparative example uses ethyl cellulose instead of modified cellulose, while the other steps are the same as in Example 1.

[0070] Comparative Example 2: This comparative example did not include titanium dioxide compared to Example 1, but the remaining steps were the same.

[0071] Comparative Example 3: This comparative example did not include silicon dioxide, but the remaining steps were the same as in Example 1.

[0072] Comparative Example 4: This comparative example did not include calcium fluoride, but the remaining steps were the same as in Example 1.

[0073] The conductive silver pastes prepared in Examples 1-3 and Comparative Examples 1-4 were screen-printed onto the surface of a silicon substrate and dried. The substrate was then held at 800°C for 40 seconds and cooled to obtain samples. The samples were then tested using a solar-powered simulated electrical efficiency tester under AM1.5 illumination and an irradiance of 1000 W / m². 2 The conversion efficiency was tested under the conditions of an ambient temperature of 25℃ and ambient humidity of 30%, 50% and 80%, and the test results are shown in Table 1 below.

[0074] Table 1

[0075]

[0076] As shown in Table 1, this application has a very good conversion efficiency, and the conversion efficiency does not decrease significantly in a humid environment.

[0077] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing conductive silver paste for photovoltaic cells, characterized in that: Specifically, the steps include the following: Weigh out the following percentages of raw materials: 65-85% silver powder and 1-3% modified binder, with the remainder being an organic carrier. Grind and blend the raw materials to obtain conductive silver paste for photovoltaic cells. The organic carrier is prepared by the following steps: Step A1: N-hydroxyphthalimide, copper chloride, sodium hypochlorite and deionized water are mixed and stirred, and cellulose is added to carry out the reaction. The filtrate is filtered to remove the filtrate and carboxylated cellulose is obtained. Carboxylated cellulose, diethanolamine, dicyclohexylcarbodiimide and dimethyl sulfoxide are mixed and reacted to obtain pretreated cellulose. Step A2: After mixing and reacting pretreated cellulose, epichlorohydrin, boron trifluoride ether and dimethyl sulfoxide, sodium hydroxide solution is added, and the reaction is continued by heating to obtain epoxy cellulose. After mixing and reacting epoxy cellulose, iminodiacetic acid and dimethyl sulfoxide, the pH is adjusted to acidic to obtain modified cellulose. Step A3: Weigh the following raw materials in parts by weight: 65-80 parts terpineol, 20-25 parts butyl carbitol acetate, 1-3 parts ethyl cellulose, 3-5 parts modified cellulose, 0.5-1 parts tributyl phosphate, 0.5-1 parts methacryloyloxypropyltrimethoxysilane, 1-3 parts soybean lecithin, 1-3 parts stearamide, and 3-5 parts silver nitrate solution. Stir the raw materials evenly to obtain the organic carrier. The modified adhesive is prepared by the following steps: Step B1: Weigh the following raw materials in parts by weight: 50-60 parts bismuth trioxide, 8-10 parts boric acid, 3-5 parts zinc oxide, 3-5 parts barium oxide, 1-3 parts strontium oxide, 5-10 parts titanium dioxide, 5-10 parts silicon dioxide, and 1-3 parts calcium fluoride; Step B2: Mix the raw materials and anhydrous ethanol, sonicate, then stir and grind until uniformly mixed to obtain composite raw material powder; Step B3: Add the composite raw material powder into a muffle furnace, keep it at high temperature, cool and grind it to obtain the modified binder.

2. The method for preparing conductive silver paste for photovoltaic cells according to claim 1, characterized in that: The silver powder has a particle size of 2-2.5 μm.

3. The method for preparing conductive silver paste for photovoltaic cells according to claim 1, characterized in that: The ratio of N-hydroxyphthalimide, copper chloride, sodium hypochlorite, deionized water and cellulose in step A1 is 10 mmol:10 mmol:50 mmol:100 mL:5 g, and the molar ratio of carboxyl group, diethanolamine and dicyclohexylcarbodiimide on carboxylated cellulose is 1:1:1.

1.

4. The method for preparing conductive silver paste for photovoltaic cells according to claim 1, characterized in that: In step A2, the ratio of the amount of hydroxyl groups on the pretreated cellulose, epichlorohydrin, boron trifluoride ether, dimethyl sulfoxide, and sodium hydroxide solution is 200 mmol: 200 mmol: 0.9 g: 80 mL: 15 mL, and the molar ratio of epoxy groups on the epoxy cellulose to iminodiacetic acid is 1:

1.

5. The method for preparing conductive silver paste for photovoltaic cells according to claim 1, characterized in that: The silver nitrate solution mentioned in step A3 has a mass fraction of 2%.

6. The method for preparing conductive silver paste for photovoltaic cells according to claim 1, characterized in that: The ratio of raw material to anhydrous ethanol used in step B2 is 1g:5mL.

7. A conductive silver paste for photovoltaic cells, characterized in that: It is prepared according to any one of the preparation methods described in claims 1-6.

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