Metal-doped silver powder, preparation method thereof and photovoltaic cell silver paste
By preparing silver powder doped with metal, the problem of the influence of silver powder morphology and particle size on efficiency in photovoltaic silver paste was solved, and high-efficiency photoelectric conversion of photovoltaic cells was achieved.
Patent Information
- Application Number
- CN202511359889.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-23
- Publication Date
- 2026-01-02
AI Technical Summary
The morphology, particle size, and distribution characteristics of silver powder in existing photovoltaic silver pastes affect photoelectric conversion efficiency, and TOPCON crystalline silicon cells have significant room for efficiency improvement.
Silver powder doped with metals, including silver salts, metal salts, reducing agents, modifiers, and dispersants, is prepared using a specific process to form spherical particles, thereby reducing the contact resistance of silver grid lines.
It improves the photoelectric conversion efficiency of photovoltaic cells, reduces the contact resistance of silver grid lines, and improves the dispersibility and sintering activity of silver powder.
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Figure CN121244979A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure belongs to the technical field of photovoltaic silver paste, and particularly relates to a metal-doped silver powder, a preparation method thereof, and a photovoltaic cell silver paste. BACKGROUND
[0002] As an electrode material of a photovoltaic crystalline silicon cell, the photovoltaic silver paste mainly serves to collect and export photogenerated carriers, and is commonly used on the light-receiving surface of a P-type cell and the double surface of an N-type cell. The photovoltaic silver powder is the most important material for producing the photovoltaic silver paste, and has the highest composition ratio and cost ratio in the production of the silver paste. With the continuous rise in the penetration rate of N-type cells, the consumption of photovoltaic silver paste will continue to grow in the future.
[0004] The morphology structure, particle size and distribution characteristics, bulk density and tap density, specific surface area, and sintering performance of the silver powder all affect the performance of the paste, and the morphology, particle size characteristics, and sintering performance are the most critical characteristics, which directly or indirectly determine the photoelectric conversion efficiency of the crystalline silicon cell. The efficiency of the currently mainstream TOPCON crystalline silicon cell has reached 26%, and there is still a large room for improvement compared with the theoretical efficiency of 28.7% of the TOPCON crystalline silicon cell. Therefore, the present application further improves the photoelectric conversion efficiency of the crystalline silicon cell by preparing a metal-doped spherical silver powder. SUMMARY
[0005] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides a metal-doped silver powder, a preparation method thereof, and a photovoltaic cell silver paste.
[0006] In one aspect of the present disclosure, a metal-doped silver powder is provided, which includes:
[0007] 10-50 parts by mass of a silver salt;
[0008] 1-3 parts by mass of a metal salt;
[0009] 3-15 parts by mass of a reducing agent;
[0010] 2-5 parts by mass of a modifier;
[0011] 5-25 parts by mass of a dispersant;
[0012] 2000 parts by mass of a solvent.
[0013] Optionally, the silver salt includes at least one of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate.
[0014] Optionally, the metal salt includes at least one of lead nitrate, lead acetate, bismuth nitrate, sodium tellurite, potassium tellurate, and indium nitrate hydrate.
[0015] Optionally, the reducing agent comprises at least one of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride, hydrazine hydrate and glucose.
[0016] Optionally, the modifying agent comprises at least one of lauric acid, myristic acid, palmitic acid and stearic acid.
[0017] Optionally, the dispersing agent is at least one of gelatin, polyvinylpyrrolidone and polyvinyl alcohol.
[0018] Another aspect of the present disclosure provides a method for preparing the metal-doped silver powder as described above, the method comprising:
[0019] 1000 parts of solvent are added into a first solution preparation kettle, 10-50 parts of silver-containing compound are then added, and after mechanical stirring and sufficient dissolution, 1-3 parts of metal salt are added, and after uniform stirring, a first reaction solution is obtained;
[0020] Another 1000 parts of solvent are added into a second solution preparation kettle, 3-15 parts of reducing agent are then added, and after mechanical stirring and sufficient dissolution, 2-5 parts of modifying agent and 5-25 parts of dispersing agent are added respectively, and after uniform stirring, a second reaction solution is obtained;
[0021] The first reaction solution and the second reaction solution are injected into a constant-temperature reaction kettle respectively, and a reaction solution is obtained by reaction;
[0022] The reaction solution is centrifuged for the first time, and then the upper solution is poured out, 1 part of anhydrous ethanol is added, and ultrasonic treatment, centrifugation for the second time and drying treatment are performed to obtain the metal-doped silver powder.
[0023] Optionally, the injection rate of the first reaction solution and the second reaction solution into the constant-temperature reaction kettle is 700-900 mL / min, the reaction temperature is 30-40℃, and the time is 5-15 min.
[0024] Optionally, the centrifugation rate of the reaction solution for the first time is 1500-2000 r / min, and the time is 10-20 min;
[0025] The centrifugation rate for the second time is 2000-3000 r / min, and the time is 10-20 min;
[0026] The drying treatment temperature is 60-70℃, and the time is 7-9 h.
[0027] Another aspect of the present disclosure provides a photovoltaic cell silver paste comprising the metal-doped silver powder as described above.
[0028] The disclosure provides a kind of metal-doped silver powder and its preparation method, photovoltaic cell silver paste.The silver powder includes: 10-50 mass parts of silver salt;1-3 mass parts of metal salt;3-15
[0029] Mass parts of reducing agent;2-5 mass parts of modifier;5-25 mass parts of dispersing agent;2000 mass parts of solvent.The disclosure can effectively reduce the contact resistance of silver grid line by doping metal salt in silver powder, thereby improving the photoelectric conversion efficiency of cell piece. BRIEF DESCRIPTION OF DRAWINGS
[0030] Figure 1 The flowchart of the preparation method of the metal-doped silver powder of the specific embodiment of the disclosure;
[0031] Figure 2 The SEM image of the silver powder of Example 1 of the disclosure;
[0032] Figure 3 The SEM image of the silver powder of Example 2 of the disclosure;
[0033] Figure 4 The SEM image of the silver powder of Example 3 of the disclosure;
[0034] Figure 5 The SEM image of the silver powder of Comparative Example 1 of the disclosure. DETAILED DESCRIPTION
[0035] In order for those skilled in the art to better understand the technical solutions of the disclosure, the disclosure will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the disclosure and are part of the embodiments of the disclosure, but not all embodiments. Based on the embodiments of the disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the disclosure.
[0036] In one aspect of the disclosure, a metal-doped silver powder is provided, which includes:
[0037] 10-50 mass parts of silver salt;1-3 mass parts of metal salt;3-15 mass parts of reducing agent;
[0038] 2-5 mass parts of modifier;5-25 mass parts of dispersing agent;2000 mass parts of solvent.
[0039] In this embodiment, by doping metal salt in silver powder, the contact resistance of silver grid line can be effectively reduced, thereby improving the photoelectric conversion efficiency of cell piece.
[0040] In some preferred embodiments, the silver salt can preferably be 10 parts by mass, 20 parts by mass, 30 parts by mass, 40 parts by mass, 50 parts by mass, etc., and includes at least one of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate.
[0041] In other preferred embodiments, the metal salt can preferably be 1 part by mass, 2 parts by mass, 3 parts by mass, etc., and includes at least one of lead nitrate, lead acetate, bismuth nitrate, sodium tellurite, potassium tellurate, and indium nitrate hydrate. On the one hand, the doping metal is enriched at the silver particle interface, which can reduce the potential barrier height between silver and the silicon substrate, improve the ohmic contact, thereby reducing the contact voltage (by 10-30%), and directly improving the photoelectric conversion efficiency of the battery; on the other hand, the doping metal (such as Bi, Pb, Te, etc.) can form a low-melting eutectic phase (such as Ag-Bi, Ag-Te, etc.) during sintering, which promotes the melting and densification between silver particles, reduces the sintering temperature, thereby reducing the damage of high temperature to the photovoltaic cell, and forming a more continuous conductive network after sintering, reducing the porosity of the silver grid line, and improving the electrical conductivity.
[0042] In other preferred embodiments, the reducing agent can preferably be 2 parts by mass, 5 parts by mass, 8 parts by mass, 10 parts by mass, 15 parts by mass, etc., and includes at least one of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride, hydrazine hydrate, and glucose. The reducing agent is used to reduce silver ions (Ag + ) to silver atoms (Ag) to form silver particles. For example, sodium ascorbate is used for mild reduction, which is conducive to controlling the uniformity of particle size, and for another example, hydrazine hydrate has strong reducing property and is suitable for rapid reaction.
[0043] In other preferred embodiments, the modifier can preferably be 2 parts by mass, 3 parts by mass, 4 parts by mass, 5 parts by mass, etc., and includes at least one of lauric acid, myristic acid, palmitic acid, and stearic acid, which is adsorbed on the surface of silver particles to prevent agglomeration, promote the formation of spherical particles, and improve the wettability and printing performance of silver powder in subsequent slurry.
[0044] In other preferred embodiments, the dispersant can preferably be 5 parts by mass, 10 parts by mass, 15 parts by mass, 20 parts by mass, 25 parts by mass, etc., and includes at least one of gelatin, polyvinylpyrrolidone, and polyvinyl alcohol. The dispersant keeps the silver powder uniformly dispersed by steric hindrance or electrostatic repulsion, stabilizes the reaction system, and prevents particle aggregation.
[0045] In other preferred embodiments, the solvent is deionized water.
[0046] As shown in Figure 1 , another aspect of the present disclosure proposes a method S100 for preparing the silver powder doped with metal as described above, which specifically includes the following steps S110-S140:
[0047] S110, 1000 parts of solvent are added into a first liquid preparation kettle, then 10-50 parts of silver-containing compound are added, mechanically stirred and fully dissolved, then 1-3 parts of metal salt are added, stirred uniformly, and a first reaction solution is obtained.
[0048] S120, another 1000 parts of solvent are added into a second liquid preparation kettle, then 3-15 parts of reducing agent are added, mechanically stirred and fully dissolved, then 2-5 parts of modifier and 5-25 parts of dispersant are added respectively, stirred uniformly, and a second reaction solution is obtained.
[0049] S130, the first reaction solution and the second reaction solution are injected into a constant temperature reaction kettle through a syringe pump, and a brown reaction solution is obtained by reaction.
[0050] In step S130, the first reaction solution and the second reaction solution are injected into the constant temperature reaction kettle at a rate of 700-900 mL / min, for example, 800 mL / min can be preferred; the reaction temperature is 30-40℃, for example, 35℃ can be preferred, and the time is 5-15 min, for example, 10 min can be preferred.
[0051] S140, the reaction solution is centrifuged for the first time, then the upper solution is poured out, 1 part of anhydrous ethanol is added, and ultrasonic treatment, second centrifugation and drying treatment are carried out to obtain metal-doped silver powder.
[0052] In step S140, the first centrifugation of the reaction solution is carried out at a rate of 1500-2000 r / min for 10-20 min; the second centrifugation is carried out at a rate of 2000-3000 r / min for 10-20 min; and the drying treatment is carried out at a temperature of 60-70℃ for 7-9 h.
[0053] In another aspect of the present disclosure, a photovoltaic cell silver paste is provided, which comprises the metal-doped silver powder described above.
[0054] The metal-doped silver powder of the present disclosure can be made into a silver paste for a photovoltaic cell, which has better dispersibility, printability and higher sintering activity, and finally realizes the improvement of photoelectric conversion efficiency.
[0055] The silver powder and its preparation method will be further described below in combination with specific examples:
[0056] Example 1
[0057] 1000 parts of solvent are added into a first liquid preparation kettle I, then 30 parts of silver nitrate are added, mechanically stirred and fully dissolved, then 2 parts of lead nitrate are added, stirred uniformly, and a first reaction solution A is obtained.
[0058] Into the second liquid preparation vessel II, 1000 parts of solvent were added, followed by 6 parts of reducing agent sodium ascorbate. After mechanical stirring and complete dissolution, 2 parts of modifier oleic acid and 10 parts of dispersant polyvinyl alcohol were added in sequence. After uniform stirring, the second reaction solution B was obtained.
[0059] The first reaction solution A and the second reaction solution B were injected into the constant-temperature reaction vessel at a speed of 800 mL / min through the injection pump. The reaction temperature was 35°C, and the stirring reaction was carried out for 10 min to obtain a yellowish-brown solution.
[0060] The reaction solution was centrifuged at a centrifugal speed of 2000 r / min for 15 min. Then, the supernatant was poured out, 1 part of anhydrous ethanol was added, and ultrasonic treatment was carried out for 30 s. Subsequently, the centrifugal separation was continued at a centrifugal speed of 3000 r / min for 15 min. Then, the supernatant was poured out, and the mixture was placed in a drying oven for air-drying at 65°C for 8 h to obtain the metal-doped silver powder 1.
[0061] The micro-morphology of the silver powder prepared in this example is shown in FIG. 1. The silver powder is spherical particles with uniform particle size distribution and smooth surface. Figure 2
[0062] As shown in Table 1, the silver powder in this example was formed into silver paste, and the line resistance of the silver paste printed to form the silver gate line was 2.19-2.25 Ω / cm, the line resistivity was 3.52×10 -6 -3.62×10 -6 Ω·cm, the contact resistance was 0.59-0.64 mΩ·cm2, and the contact resistivity was 0.76-0.88 mΩ·cm 2 .
[0063] Example 2
[0064] Into the first liquid preparation vessel I, 1000 parts of solvent were added, followed by 50 parts of silver nitrate. After mechanical stirring and complete dissolution, 3 parts of bismuth nitrate were added. After uniform stirring, the first reaction solution A was obtained.
[0065] Into the second liquid preparation vessel II, 1000 parts of solvent were added, followed by 15 parts of reducing agent hydrazine hydrate. After mechanical stirring and complete dissolution, 4 parts of modifier oleic acid and 25 parts of dispersant polyvinyl alcohol were added in sequence. After uniform stirring, the second reaction solution B was obtained.
[0066] The first reaction solution A and the second reaction solution B were injected into the constant-temperature reaction vessel at a speed of 800 mL / min through the injection pump. The reaction temperature was 35°C, and the stirring reaction was carried out for 10 min to obtain a yellowish-brown solution.
[0067] The reaction solution was centrifuged at a centrifugal rate of 1500 r / min for 15 min, then the supernatant was poured out, 1 part of anhydrous ethanol was added, and ultrasonic treatment was performed for 30 s, then the centrifugal separation was continued at a centrifugal rate of 2000 r / min for 15 min, then the supernatant was poured out, and the mixture was placed in a drying oven and dried at 65 ℃ under blast for 8 h to obtain metal-doped silver powder 2.
[0068] The micro-morphology of the silver powder prepared in this example is shown in FIG. 2, and the silver powder particles have good morphology, but there is slight agglomeration of some particles, which may be related to the doping of bismuth nitrate or the high amount of dispersant. Figure 3
[0069] As shown in Table 1, the silver powder in this example was formed into silver paste, and the line resistance of the silver gate line formed by printing the paste was 2.20-2.29 Ω / cm, the line resistivity was 3.63×10 -6 -3.78×10 -6 Ω·cm, the contact resistance was 0.54-0.63 mΩ·cm2, and the contact resistivity was 0.63-0.84 mΩ·cm2.
[0070] Example 3
[0071] 1000 parts of solvent were added to a first solution preparation kettle I, then 45 parts of silver nitrate were added, mechanical stirring was performed until the silver nitrate was completely dissolved, then 3 parts of potassium tellurate were added, and stirring was performed until the potassium tellurate was uniformly dispersed, thereby obtaining a first reaction solution A;
[0072] Another 1000 parts of solvent were added to a second solution preparation kettle II, then 10 parts of a reducing agent, sodium ascorbate, were added, mechanical stirring was performed until the sodium ascorbate was completely dissolved, then 4 parts of a modifier, oleic acid, and 15 parts of a dispersant, polyvinyl alcohol, were added, and stirring was performed until the modifier and the dispersant were uniformly dispersed, thereby obtaining a second reaction solution B;
[0073] The first reaction solution A and the second reaction solution B were injected into a constant-temperature reaction kettle at a speed of 800 mL / min through a syringe pump, the reaction temperature was 35 ℃, and stirring was performed for 10 min to obtain a yellowish-brown solution.
[0074] The reaction solution was centrifuged at a centrifugal rate of 2000 r / min for 15 min, then the supernatant was poured out, 1 part of anhydrous ethanol was added, and ultrasonic treatment was performed for 30 s, then the centrifugal separation was continued at a centrifugal rate of 2000 r / min for 15 min, then the supernatant was poured out, and the mixture was placed in a drying oven and dried at 65 ℃ under blast for 8 h to obtain metal-doped silver powder 3.
[0075] The micro-morphology of the silver powder prepared in this example is shown in FIG. 2, and the silver powder particles have good morphology, but there is slight agglomeration of some particles, which may be related to the doping of bismuth nitrate or the high amount of dispersant. Figure 4
[0076] As shown in Table 1, the silver powder of the present embodiment is formed into silver paste, and the line resistance of the silver paste printed to form silver grid lines is 2.31-2.36 Ω / cm, the line resistivity is 3.56 x 10 -6 -3.62 x 10 -6 Ω·cm, the contact resistance is 0.64-0.71 mΩ·cm2, and the contact resistivity is 0.88-0.93 mΩ·cm 2 .
[0077] Comparative Example 1
[0078] 1000 parts of solvent were added to a first solution preparation tank I, and then 30 parts of silver nitrate were added. After mechanical stirring and complete dissolution, a first reaction solution A was obtained;
[0079] Another 1000 parts of solvent were added to a second solution preparation tank II, and then 6 parts of a reducing agent, sodium ascorbate, were added. After mechanical stirring and complete dissolution, 2 parts of a modifier, oleic acid, and 10 parts of a dispersant, polyvinyl alcohol, were added in sequence. After uniform stirring, a second reaction solution B was obtained;
[0080] The first reaction solution A and the second reaction solution B were injected into a constant-temperature reaction tank at a speed of 800 mL / min through a syringe pump. The reaction temperature was 35°C, and the stirring reaction was carried out for 10 min to obtain a yellowish-brown solution.
[0081] The reaction solution was centrifuged at a centrifugal speed of 2000 r / min for 15 min, and then the supernatant was poured out. Then 1 part of anhydrous ethanol was added, and ultrasonic treatment was carried out for 30 s. Subsequently, the centrifugal speed was increased to 3000 r / min, and the centrifugal separation was continued for 15 min. Then the supernatant was poured out, and the mixture was placed in a drying oven for air-drying at 65°C for 8 h to obtain ultra-fine silver powder.
[0082] The micro-morphology of the conventional silver powder prepared in the present embodiment is shown in Figure 5 The silver powder particles without metal doping have obvious agglomeration, and the morphology is irregular, which verifies the key role of metal doping in improving the dispersibility and morphology.
[0083] As shown in Table 1, the silver powder of the present embodiment is formed into silver paste, and the line resistance of the silver paste printed to form silver grid lines is 2.31-2.36 Ω / cm, the line resistivity is 3.56 x 10 -6 -4.66 x 10 -6 Ω·cm, the contact resistance is 1.24 -1.71 mΩ·cm2, and the contact resistivity is 1.71-2.52 mΩ·cm 2 .
[0084] In summary, the line resistance and contact resistance of Examples 1-3 are significantly lower than those of the undoped comparative example, which illustrates the technical effect of metal salt doping in reducing the contact resistance and improving the photoelectric efficiency.
[0085] Test results of each example and comparative example of Table 1
[0086]
[0087] The present disclosure proposes a metal-doped silver powder, a preparation method thereof, and a photovoltaic cell silver paste, which has the following beneficial effects relative to the prior art:
[0088] First, the present disclosure can effectively reduce the contact resistance of the silver grid line by doping a small amount of metal elements, thereby improving the photoelectric conversion efficiency of the cell piece;
[0089] Second, the present disclosure prepares a metal-doped silver powder by reducing different metal ions together with silver ions through a liquid phase reduction reaction, so that other metal elements can be uniformly distributed in the silver powder, thereby forming a better contact resistance during the sintering process of the silver grid line;
[0090] Third, the photovoltaic cell silver paste of the present disclosure has good dispersibility, printability, and higher sintering activity, thereby improving its photoelectric conversion efficiency.
[0091] It can be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.
Claims
1. A silver powder doped with metal, characterized in that, The silver powder includes: 10-50 parts by weight of silver salt; 1-3 parts by weight of metal salt; 3-15 parts by weight of reducing agent; 2-5 parts by weight of modifier; 5-25 parts by weight of dispersant; 2000 parts by weight of solvent.
2. The silver powder with metal doping according to claim 1, characterized in that, The silver salt includes at least one of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate.
3. The silver powder with metal doping according to claim 1, characterized in that, The metal salt includes at least one of lead nitrate, lead acetate, bismuth nitrate, sodium tellurite, potassium tellurate, and indium hydrate.
4. The silver powder with metal doping according to claim 1, characterized in that, The reducing agent includes at least one of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride, hydrazine hydrate, and glucose.
5. The silver powder with metal doping according to claim 1, characterized in that, The modifier includes at least one of lauric acid, tetradecanoic acid, palmitic acid, and stearic acid.
6. The silver powder with metal doping according to claim 1, characterized in that, The dispersant is at least one of gelatin, polyvinylpyrrolidone, and polyvinyl alcohol.
7. A method for preparing silver powder doped with metal as described in any one of claims 1-6, characterized in that, The method includes: Add 1000 parts of solvent to the first mixing vessel, then add 10-50 parts of silver-containing compound, stir mechanically and dissolve completely, then add 1-3 parts of metal salt, stir evenly and the first reaction solution is obtained. Add another 1000 parts of solvent to the second mixing vessel, then add 3-15 parts of reducing agent, stir mechanically and dissolve completely, then add 2-5 parts of modifier and 5-25 parts of dispersant respectively, stir evenly to obtain the second reaction solution; The first reaction solution and the second reaction solution were injected into a constant temperature reaction vessel, and the reaction was carried out to obtain a reaction solution. The reaction solution was centrifuged for the first time, then the upper layer of solution was poured off, and 1 part of anhydrous ethanol was added. After ultrasonic treatment, a second centrifugation, and drying, metal-doped silver powder was obtained.
8. The method according to claim 7, characterized in that, The first and second reaction solutions are injected into the constant temperature reactor at a rate of 700-900 mL / min, the reaction temperature is 30-40℃, and the reaction time is 5-15 min.
9. The method according to claim 7, characterized in that, The reaction solution is centrifuged for the first time at a rate of 1500-2000 r / min for 10-20 min. The second centrifugation was performed at a rate of 2000-3000 r / min for 10-20 min. The drying process is carried out at a temperature of 60-70℃ for 7-9 hours.
10. A photovoltaic cell silver paste, characterized in that, The photovoltaic cell silver paste includes silver powder with doped metal as described in any one of claims 1-6.