Functional additive slurry, low-temperature curing copper slurry of N-type TOPCon solar cell, electrode and preparation method

Abstract

The invention provides functional additive slurry, low-temperature curing copper slurry of an N-type TOPCon solar cell, an electrode and a preparation method, and belongs to the technical field of solar cells. The functional additive slurry comprises 50-90 parts by mass of an organic carrier; 0.1-30 parts by mass of a functional additive; the functional additive comprises at least one of magnesium powder, silicon powder, lead powder, graphite, carbon black, tin-bismuth alloy, gallium, iron powder, vitamin C and aluminum powder; 0.1-10 parts by mass of a dispersant; and 5-40 parts by mass of a solvent. When the functional additive slurry is used in the copper slurry, the copper powder can be uniformly dispersed, and the copper powder is not easy to oxidize in the printing and curing process, so that the resistance is reduced.

Description

Technical Field

[0001] This disclosure belongs to the field of solar cell technology, specifically relating to a functional additive paste, a low-temperature curing copper paste for N-type TOPCon solar cells, electrodes, and preparation methods. Background Technology

[0002] In recent years, with the advancement and application of technology, monocrystalline silicon solar cell technology using TOPCon technology has achieved rapid development. Its key technologies and processes are constantly being updated, placing new and higher demands on conductive pastes, a component of solar cells. This has prompted more researchers to continuously develop application materials with better performance. Currently, conductive silver paste occupies the main market share of global photovoltaic pastes. Due to electron migration phenomena during the use of conductive silver paste, the rising price of silver, coupled with increasing raw material costs and volatile international trade policies, cost reduction is an inevitable trend. Copper has similar resistivity to silver and is lower in cost; therefore, the development of low-cost copper-based conductive pastes has become a new hot topic.

[0003] Currently, copper paste preparation mainly focuses on the pretreatment and curing methods of copper powder. Acid treatment reduces the oxygen content of the copper powder, followed by curing using specialized equipment that provides the appropriate temperature, atmosphere, and pressure. Alternatively, the printed solar cells can be cured under a nitrogen atmosphere. Copper grid lines are overlaid on a silver seed layer to conduct current. Because copper replaces some silver, costs are reduced, and the lower line resistance of copper grid lines allows the solar cell efficiency to be comparable to that of pure silver grid lines.

[0004] However, current technologies suffer from uneven copper powder processing and oxidation of copper powder during printing and curing, leading to increased resistance. Further improvements to the process and equipment are needed to meet higher electrical performance requirements. Summary of the Invention

[0005] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a functional additive slurry, a low-temperature curing copper slurry for N-type TOPCon solar cells, an electrode, and a preparation method thereof.

[0006] One aspect of this disclosure provides a functional additive paste for low-temperature curing copper paste, the functional additive paste comprising:

[0007] 50-90 parts by weight of organic carrier;

[0008] 0.1-30 parts by weight of functional additives; the functional additives include at least one of magnesium powder, silicon powder, lead powder, graphite, carbon black, tin-bismuth alloy, gallium, iron powder, vitamin C, and aluminum powder;

[0009] 0.1-10 parts by weight of dispersant;

[0010] 5-40 parts by weight of solvent.

[0011] Optionally, the D50 particle size of the functional additive is 0.05-2 μm.

[0012] Optionally, the organic carrier comprises PVB resin and acrylic resin; wherein,

[0013] The mass ratio of the PVB resin to the acrylic resin is (3-5):

[0014] (5-10).

[0015] Optionally, the dispersant includes at least one of pigment-containing copolymers, highly branched polyesters, fatty acids, polyamides, and acid-containing copolymers.

[0016] Optionally, the solvent includes at least one of diethylene glycol butyl ether, polymethoxydimethyl ether, butyl carbohydrate, dibutyl phthalate, and diethylene glycol butyl ether acetate.

[0017] In another aspect of this disclosure, a low-temperature curing copper paste for an N-type TOPCon solar cell is provided, the low-temperature curing copper paste comprising:

[0018] 80-98 parts by weight of conductive copper powder;

[0019] 0.1-20 parts by weight of functional additive slurry, wherein the functional additive slurry is the functional additive slurry according to any one of claims 1-5;

[0020] 1-10 parts by weight of organic carrier;

[0021] 0.1-2 parts by weight of the additive.

[0022] Optionally, the additives include leveling agents and dispersants.

[0023] Optionally, the leveling agent is at least one of acrylate, silicone, polyether-modified siloxane, and dibutyl phthalate;

[0024] The dispersant is at least one of polyethylene glycol, sodium dodecyl sulfate, sorbitan trioleate, and lecithin.

[0025] In another aspect of this disclosure, an electrode is provided, the electrode comprising: a battery cell, a silver seed layer on the battery cell, and copper grid lines superimposed on the silver seed layer; the copper grid lines are formed by sintering the low-temperature curing copper paste described above.

[0026] In another aspect of this disclosure, a method for preparing the electrode described above is provided, the method comprising:

[0027] Conductive copper powder, functional additive slurry, organic carrier and additives are mixed and ground until the slurry fineness is ≤10μm to obtain copper slurry.

[0028] The copper paste is overprinted onto a solar cell with a silver grid seed layer, cured in a nitrogen atmosphere at 250-330°C for 5-20 minutes, and then cooled to obtain an electrode.

[0029] This disclosure discloses a functional additive slurry, a low-temperature curing copper paste for N-type TOPCon solar cells, and electrodes. The functional additive slurry comprises: 50-90 parts by weight of an organic carrier; 0.1-30 parts by weight of a functional additive, including at least one selected from magnesium powder, silicon powder, lead powder, graphite, carbon black, tin-bismuth alloy, gallium, iron powder, vitamin C, and aluminum powder; 0.1-10 parts by weight of a dispersant; and 5-40 parts by weight of a solvent. When used in copper paste, this functional additive slurry enables uniform dispersion of copper powder, preventing oxidation during printing and curing, thereby reducing electrical resistance. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the electrode preparation method according to a specific embodiment of the present disclosure;

[0031] Figure 2 This is a schematic diagram of the slurry after curing in Embodiment 4 and Comparative Example 1 of this disclosure; wherein, Figure 2 (A) in the figure represents the result of Example 4; Figure 2 (B) in the figure represents the result of Comparative Example 1;

[0032] Figure 3 This is a schematic diagram of the line shape after copper paste printing according to Embodiment 4 of this disclosure. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0034] One aspect of this disclosure provides a functional additive slurry for low-temperature curing copper paste, the functional additive slurry comprising: 50-90 parts by weight of an organic carrier; 0.1-30 parts by weight of a functional additive; the functional additive comprising at least one of magnesium powder, silicon powder, lead powder, graphite, carbon black, tin-bismuth alloy, gallium, iron powder, vitamin C, and aluminum powder; 0.1-10 parts by weight of a dispersant; and 5-40 parts by weight of a solvent.

[0035] In this embodiment, a novel functional additive material is designed for low-temperature curing copper paste. When applied to copper paste, this material can preferentially react with oxygen in the atmosphere or react with the oxide layer on the surface of copper powder to generate an oxidation-reduction reaction to replace copper, thereby inhibiting copper oxidation and reducing the line resistance of the battery cell on the original basis.

[0036] It should be understood that, according to actual needs, the components and their contents of the functional additive slurry can be adjusted and applied to low-temperature curing copper paste.

[0037] In some preferred embodiments, the content of the functional additive can preferably be 0.1 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, etc., and its D50 particle size is 0.05-2μm, for example, 0.05μm, 0.5μm, 1μm, 1.5μm, 2μm, etc. are preferred.

[0038] In other preferred embodiments, the content of the organic carrier may preferably be 50 parts by mass, 60 parts by mass, 70 parts by mass, 80 parts by mass, 90 parts by mass, etc., which includes PVB resin and acrylic resin; wherein the mass ratio of PVB resin and acrylic resin is (3-5):(5-10).

[0039] As a further preferred embodiment, the molecular weight of the organic resin is 1000-90000, and the organic carrier system volatilizes 15wt% at 150-200℃, 85wt% at 200-240℃, and 100wt% at 240-300℃.

[0040] In other preferred embodiments, the content of the dispersant may preferably be 0.1 parts by weight, 1 part by weight, 3 parts by weight, 5 parts by weight, 8 parts by weight, 10 parts by weight, etc., and includes at least one of pigment-containing copolymers, highly branched polyesters, fatty acids, polyamides, and acid-containing copolymers.

[0041] In other preferred embodiments, the solvent content may preferably be 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, etc., which includes at least one of diethylene glycol butyl ether, polyoxymethylene dimethyl ether, butyl carbolic acid, dibutyl phthalate, and diethylene glycol butyl ether acetate.

[0042] In another aspect of this disclosure, a low-temperature curing copper paste for N-type TOPCon solar cells is provided, comprising: 80-98 parts by weight of conductive copper powder; 0.1-20 parts by weight of functional additive paste, wherein the functional additive paste is the functional additive paste described above, and the specific components and contents are described above; 1-10 parts by weight of organic carrier; and 0.1-2 parts by weight of additives.

[0043] In some preferred embodiments, the content of conductive copper powder may preferably be 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 98 parts by weight, etc.

[0044] In other preferred embodiments, the content of the additives may preferably be 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, etc., and these additives include leveling agents and dispersants. Preferably, the ratio of leveling agent to dispersant is 1:1.

[0045] As a further preferred embodiment, the leveling agent is at least one of acrylate, silicone, polyether-modified siloxane and dibutyl phthalate; the dispersant is at least one of polyethylene glycol, sodium dodecyl sulfate, sorbitan trioleate and lecithin.

[0046] In other preferred embodiments, the organic carrier may be the same as described above, for example, including PVB resin and acrylic resin; wherein the mass ratio of the PVB resin and the acrylic resin is (3-5):(5-10).

[0047] In other preferred embodiments, the content of the functional additive slurry may preferably be 0.1 parts by weight, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, etc., and the specific components can be referred to the above description.

[0048] In this embodiment, by adding a functional additive slurry to the copper paste, the functional additive slurry preferentially reacts with oxygen in the atmosphere or can undergo a redox reaction with the oxide layer on the surface of the copper powder to displace copper, thereby reducing the oxidation of the copper powder during the printing and curing process, i.e., inhibiting copper powder oxidation and thus avoiding increased resistance due to oxidation. By reducing the oxide layer on the surface of the copper powder, the functional additive improves the conductivity of the copper paste, significantly reducing the line resistance of the grid lines. The reduction in line resistance directly improves the conversion efficiency of the solar cell.

[0049] In another aspect of this disclosure, an electrode is provided, comprising: a battery cell, a silver seed layer on the battery cell, and copper grid lines superimposed on the silver seed layer; the copper grid lines are formed by sintering a low-temperature curing copper paste as described above, and the specific preparation process is described below.

[0050] like Figure 1 As shown, another aspect of this disclosure provides a method for preparing an electrode, S100, which specifically includes the following steps S110 to S120:

[0051] S110. Mix conductive copper powder, functional additive slurry, organic carrier and additives, and grind until the slurry fineness is ≤10μm to obtain copper slurry.

[0052] S120. The copper paste is overprinted onto a battery cell with a silver grid seed layer, cured in a nitrogen atmosphere at 250-330°C for 5-20 minutes, and then cooled to obtain an electrode.

[0053] In some preferred embodiments, the sintering temperature is preferably 250°C, 280°C, 300°C, 330°C, etc., and the sintering time is preferably 5 min, 10 min, 15 min, 20 min, etc.

[0054] The copper paste of this embodiment can function under low-temperature curing conditions, eliminating the need for complex equipment or expensive protective atmospheres (such as requiring only a nitrogen atmosphere), thus simplifying the production process. Furthermore, by replacing expensive silver paste with copper paste, similar electrical properties are achieved using functional additives, significantly reducing raw material costs.

[0055] The functional additives and low-temperature curing copper paste will be further explained below with reference to specific embodiments:

[0056] Example 1

[0057] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0058] As shown in Table 1, functional additive slurry A includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of silica powder.

[0059] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry A.

[0060] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0061] As shown in Table 3, the contact resistance of the solar cell is 1.71 mΩ·cm. 2 The line resistance is 1.90 mΩ·cm 2The conversion efficiency is 26.07%.

[0062] Example 2

[0063] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0064] As shown in Table 1, functional additive slurry B includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of graphite.

[0065] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry B.

[0066] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0067] As shown in Table 3, the contact resistance of the solar cell is 1.74 mΩ·cm. 2 The line resistance is 1.88 mΩ·cm. 2 The conversion efficiency is 26.05%.

[0068] Example 3

[0069] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0070] As shown in Table 1, the functional additive slurry C includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of aluminum powder.

[0071] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry C.

[0072] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0073] As shown in Table 3, the contact resistance of the solar cell is 1.70 mΩ·cm. 2 The line resistance is 1.95 mΩ·cm. 2The conversion efficiency is 26.05%.

[0074] Example 4

[0075] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0076] As shown in Table 1, the functional additive slurry D includes 55 parts by mass of organic carrier, 1 part by mass of highly branched polyester dispersant, 1 part by mass of polyamide dispersant, 30 parts by mass of diethylene glycol butyl ether, and 13 parts by mass of carbon black.

[0077] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of organosilicon leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry D.

[0078] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0079] As shown in Table 3, the contact resistance of the solar cell is 1.72 mΩ·cm. 2 The line resistance is 1.92 mΩ·cm 2 The conversion efficiency is 26.07%.

[0080] Example 5

[0081] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0082] As shown in Table 1, the functional additive slurry E includes 55 parts by mass of organic carrier, 1 part by mass of highly branched polyester dispersant, 1 part by mass of polyamide dispersant, 30 parts by mass of diethylene glycol butyl ether, and 13 parts by mass of vitamin C.

[0083] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry E.

[0084] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0085] As shown in Table 3, the contact resistance of the solar cell is 1.72 mΩ·cm. 2 The line resistance is 1.94 mΩ·cm 2The conversion efficiency is 26.04%.

[0086] Example 6

[0087] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0088] As shown in Table 1, the functional additive slurry F includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of magnesium powder.

[0089] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry F.

[0090] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0091] As shown in Table 3, the contact resistance of the solar cell is 1.72 mΩ·cm. 2 The line resistance is 1.93 mΩ·cm 2 The conversion efficiency is 26.05%.

[0092] Example 7

[0093] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0094] As shown in Table 1, the functional additive slurry G includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of lead powder.

[0095] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry G.

[0096] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0097] As shown in Table 3, the contact resistance of the solar cell is 1.73 mΩ·cm. 2 The line resistance is 1.93 mΩ·cm 2The conversion efficiency is 26.05%.

[0098] Example 8

[0099] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0100] As shown in Table 1, the functional additive slurry H includes 55 parts by mass of organic carrier, 1 part by mass of highly branched polyester dispersant, 1 part by mass of polyamide dispersant, 30 parts by mass of diethylene glycol butyl ether, and 13 parts by mass of tin-bismuth alloy.

[0101] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry H.

[0102] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0103] As shown in Table 3, the contact resistance of the solar cell is 1.70 mΩ·cm. 2 The line resistance is 1.89 mΩ·cm. 2 The conversion efficiency is 26.07%.

[0104] Example 9

[0105] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0106] As shown in Table 1, functional additive slurry I includes 55 parts by mass of organic carrier, 1 part by mass of highly branched polyester dispersant, 1 part by mass of polyamide dispersant, 30 parts by mass of diethylene glycol butyl ether, and 13 parts by mass of gallium powder.

[0107] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry I.

[0108] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0109] As shown in Table 3, the contact resistance of the solar cell is 1.70 mΩ·cm. 2 The line resistance is 1.91 mΩ·cm 2The conversion efficiency is 26.05%.

[0110] Example 10

[0111] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0112] As shown in Table 1, the functional additive slurry J includes 55 parts by weight of organic carrier, 1 part by weight of highly branched polyester dispersant, 1 part by weight of polyamide dispersant, 30 parts by weight of diethylene glycol butyl ether, and 13 parts by weight of iron powder.

[0113] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 1 part by weight of organic carrier, 0.5 parts by weight of silicone leveling agent, 0.5 parts by weight of lecithin dispersant, and 8 parts by weight of functional additive slurry J.

[0114] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the effect of functional additive paste on the performance of copper paste printed solar cells.

[0115] As shown in Table 3, the contact resistance of the solar cell is 1.72 mΩ·cm. 2 The line resistance is 1.93 mΩ·cm 2 The conversion efficiency is 26.06%.

[0116] Comparative Example 1

[0117] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0118] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive copper powder, 9 parts by weight of organic carrier, and 1 part by weight of organosilicon leveling agent.

[0119] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the impact of copper paste printing on the performance of the solar cell.

[0120] As shown in Table 3, the contact resistance of the solar cell is 1.75 mΩ·cm. 2 The line resistance is 1.98 mΩ·cm. 2 The conversion efficiency is 26.03%.

[0121] Comparative Example 2

[0122] This example illustrates the properties of low-temperature curing copper paste and its electrode formation:

[0123] As shown in Table 2, the low-temperature curing slurry includes 90 parts by weight of conductive silver powder, 9 parts by weight of organic carrier, and 1 part by weight of organosilicon leveling agent.

[0124] Furthermore, the low-temperature curing paste was overprinted onto the solar cell with a silver grid seed layer, cured at 280°C in a nitrogen atmosphere for 10 minutes, and then cooled down. The IV solar cell efficiency was tested to evaluate the impact of copper paste printing on the performance of the solar cell.

[0125] As shown in Table 3, the contact resistance of the solar cell is 1.70 mΩ·cm. 2 The line resistance is 1.92 mΩ·cm 2 The conversion efficiency is 26.06%.

[0126] In summary, based on the results of the above embodiments and comparative examples, it can be seen that after adding the functional additive paste, compared with Comparative Example 1, the line resistance of the gate line decreases and the overall efficiency increases, indicating that the functional additive material plays a role in the copper paste curing process, improving its electrical performance. At the same time, it achieves performance comparable to or slightly improved with silver paste (Comparative Example 2), thus being able to replace silver paste to reduce costs.

[0127] Combination Figure 2 As shown, after the film curing, the copper paste in Example 4 is more pink than the one on the right, indicating that an oxidation-reduction reaction has occurred. The oxide layer on the surface of the copper powder is reduced to copper, and the color is closer to the original color of copper.

[0128] Combination Figure 3 As shown, the line pattern after copper paste printing in Example 4 is good, with no broken grid lines.

[0129] Table 1 Formulation of functional additive slurry

[0130]

[0131] Table 2 Low-Temperature Curing Copper Paste Formulation

[0132]

[0133] Table 3 Performance results of the battery cells in each embodiment and comparative example

[0134] <![CDATA[Contact resistance mΩ·cm 2 > <![CDATA[Line resistance mΩ·cm 2 > Conversion efficiency / % Example 1 (Silicon Powder) 1.71 1.90 26.07 Example 2 (Graphite) 1.74 1.88 26.05 Example 3 (Aluminum Powder) 1.70 1.95 26.05 Example 4 (Carbon Black) 1.72 1.92 26.07 Example 5 (Vitamin C) 1.72 1.94 26.04 Example 6 (Magnesium Powder) 1.72 1.93 26.05 Example 7 (Lead Powder) 1.73 1.93 26.05 Example 8 (Tin-Bismuth Alloy) 1.70 1.89 26.07 Example 9 (Gallium Powder) 1.70 1.91 26.05 Example 10 (Iron Powder) 1.72 1.93 26.06 Comparative Example 1 1.75 1.98 26.03 Comparative Example 2 1.70 1.92 26.06

[0135] This disclosure proposes a functional additive paste, a low-temperature curing copper paste for N-type TOPCon solar cells, electrodes, and a preparation method. Compared with the prior art, it has the following beneficial effects: The functional additive paste of this disclosure can be used in low-temperature curing copper paste to inhibit copper powder oxidation, thereby reducing the line resistance of the cell, and at the same time, it can replace silver paste and reduce costs.

[0136] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A functional additive paste for low-temperature curing copper paste, characterized in that, Functional additive slurries include: 50-90 parts by weight of organic carrier; 0.1-30 parts by weight of functional additives; the functional additives include at least one of magnesium powder, silicon powder, lead powder, graphite, carbon black, tin-bismuth alloy, gallium, iron powder, vitamin C, and aluminum powder; 0.1-10 parts by weight of dispersant; 5-40 parts by weight of solvent.

2. The functional additive slurry according to claim 1, characterized in that, The D50 particle size of the functional additive is 0.05-2 μm.

3. The functional additive slurry according to claim 1, characterized in that, The organic carrier comprises PVB resin and acrylic resin; wherein... The mass ratio of the PVB resin to the acrylic resin is (3-5):(5-10).

4. The functional additive slurry according to claim 1, characterized in that, The dispersant includes at least one of the following: a pigment-containing copolymer, a highly branched polyester, a fatty acid, a polyamide, and an acid-containing copolymer.

5. The functional additive slurry according to claim 1, characterized in that, The solvent includes at least one of diethylene glycol butyl ether, polymethoxydimethyl ether, butyl carbohydrate, dibutyl phthalate, and diethylene glycol butyl ether acetate.

6. A low-temperature curing copper paste for N-type TOPCon solar cells, characterized in that, The low-temperature curing copper paste includes: 80-98 parts by weight of conductive copper powder; 0.1-20 parts by weight of functional additive slurry, wherein the functional additive slurry is the functional additive slurry according to any one of claims 1-5; 1-10 parts by weight of organic carrier; 0.1-2 parts by weight of the additive.

7. The low-temperature curing copper paste according to claim 6, characterized in that, The additives include leveling agents and dispersants.

8. The low-temperature curing copper paste according to claim 7, characterized in that, The leveling agent is at least one of acrylate, silicone, polyether-modified siloxane, and dibutyl phthalate; The dispersant is at least one of polyethylene glycol, sodium dodecyl sulfate, sorbitan trioleate, and lecithin.

9. An electrode, characterized in that, The electrode comprises: a battery cell, a silver seed layer on the battery cell, and copper grid lines superimposed on the silver seed layer; the copper grid lines are formed by sintering the low-temperature curing copper paste according to any one of claims 6-8.

10. A method for preparing the electrode as described in claim 9, characterized in that, The method includes: Conductive copper powder, functional additive slurry, organic carrier and additives are mixed and ground until the slurry fineness is ≤10μm to obtain copper slurry. The copper paste is overprinted onto a solar cell with a silver grid seed layer, cured in a nitrogen atmosphere at 250-330°C for 5-20 minutes, and then cooled to obtain an electrode.

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