TOPCon battery silver paste based on composite functional layer as well as preparation method and application of TOPCon battery silver paste

Abstract

The invention discloses a TOPCon battery silver paste based on a composite functional layer and a preparation method and application of the TOPCon battery silver paste, and belongs to one kind of paste in the technical field of photovoltaic battery manufacturing. 2-8% of a glass phase; 10-16% of an organic carrier; wherein the metal phase comprises flake silver powder, spherical nano silver powder and a doping phase, the flake silver powder D50 is equal to 1-3 microns, the spherical nano silver powder D50 is equal to 50-200 nm, and the compounding mass ratio of the flake silver powder to the spherical nano silver powder is (5: 1)-(3: 1); the glass phase is low-melting-point lead borosilicate glass (the softening point is 450-550 DEG C) and contains 0.5-2% of titanium oxide (TiO2); the organic carrier comprises a mixed solvent composed of alpha-terpilenol and butyl carbitol acetate, and a thickening agent composed of ethyl cellulose and polyester resin; according to the TOPCon cell silver paste based on the composite functional layer and the preparation method and application thereof, the silver paste is optimized, contact is improved, metal recombination is reduced, and the efficiency and photoelectric conversion efficiency of a solar cell are further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic cell manufacturing, and in particular relates to a TOPCon cell silver paste based on a composite functional layer, a preparation method and an application thereof. Background Art

[0002] Industrially, the production and operating costs of N-type crystalline silicon TOPCon cells are higher than those of PERC cells. Therefore, N-type crystalline silicon TOPCon cells face the dual pressure of increasing efficiency while reducing costs. Currently, the thickness of the polysilicon layer is approximately 160-200nm, and cell manufacturers are attempting to reduce this thickness to around 50nm. Reducing the thickness of the polysilicon (Poly-Si) layer can reduce parasitic light absorption by the polysilicon layer, thereby improving light utilization efficiency, while increasing the throughput of the deposition process and reducing cell costs. However, the thinning of the polysilicon thickness places higher demands on the backside slurry. During the sintering process, the backside slurry easily penetrates the thin polysilicon layer, resulting in a poor passivation effect and a reduction in the cell's open-circuit voltage.

[0003] TOPCon cells, due to their superior passivated contact structure and theoretical efficiency potential, have become a core direction for next-generation high-efficiency photovoltaic technology. The silver paste used in the metallized electrodes directly determines the cell's series resistance, fill factor, and efficiency, and is a key bottleneck for industrialization.

[0004] Existing silver paste technical problems:

[0005] 1. Traditional silver paste is prone to high recombination when in contact with the n++ polysilicon layer of TOPCon cells, resulting in high contact resistance (ρc);

[0006] 2. During high temperature sintering, silver particles easily diffuse into the passivation layer, destroying the tunneling silicon oxide (SiO x )’s passivation effect;

[0007] 3. The high silver content leads to great cost pressure, and the volatile residue of the organic carrier affects the density of the electrode. Summary of the Invention

[0008] The first purpose of the present invention is to provide a TOPCon battery silver paste based on a composite functional layer, which optimizes the silver paste to improve contact, reduce metal recombination, and further improve the efficiency and photoelectric conversion efficiency of solar cells;

[0009] The second object of the present invention is to provide a method for preparing TOPCon battery silver paste based on a composite functional layer, thereby improving battery efficiency and reducing silver consumption of the silver paste;

[0010] The third object of the present invention is to provide a TOPCon battery silver paste based on a composite functional layer to achieve effective efficiency gain.

[0011] The object of the present invention is achieved by providing a TOPCon battery metallization silver paste based on a composite functional layer design, comprising the following components by mass percentage:

[0012] Metal phase: 70-85%;

[0013] Glass phase: 2-8%;

[0014] Organic carrier: 10-16%; of which,

[0015] The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 1-3 μm, the spherical nano silver powder has a D50 of 50-200 nm, and the flaky silver powder and the spherical nano silver powder are mixed in a mass ratio of 5:1-3:1;

[0016] The glass phase is low melting point lead borosilicate glass containing 0.5-2% titanium oxide;

[0017] The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

[0018] Furthermore, the doping phase includes 0.1-1% of bismuth or tellurium nanoparticles.

[0019] Furthermore, the glass phase includes 0.1-0.5% cerium oxide as a passivation layer protective agent.

[0020] Furthermore, the volume ratio of the α-terpineol to the butyl carbitol acetate is 7:3.

[0021] Furthermore, the mass ratio of the ethyl cellulose to the polyester resin is 2:1.

[0022] Furthermore, the silver paste further comprises a functional additive, wherein the functional additive is 0.05-0.2% of mercaptopropionic acid.

[0023] A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design comprises the following steps:

[0024] S1. Distributive mixing: pre-mix the spherical nano-silver powder and the doping phase in an organic carrier by ball milling, and then disperse them with the flaky silver powder and the glass phase by high-speed shear in an inert atmosphere at a stirring speed of 800-1200 r / min for 2-6 hours;

[0025] S2. Gradient sintering: After screen printing, the slurry fully mixed in S1 is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and activate the hydrogen atoms in the Sinx film.

[0026] The invention discloses an application of a TOPCon battery metallization silver paste based on a composite functional layer design in the preparation of TOPCon batteries.

[0027] The beneficial effects of the present invention are embodied in:

[0028] In the present invention, the contact resistivity of the produced slurry is effectively reduced, the efficiency of the battery is improved, and the silver consumption is effectively reduced. Therefore, by optimizing the silver paste, the silver consumption is reduced by 15-20%, the contact is improved, and the contact resistance is reduced to 0.5mΩ·cm 2 Below (compared to traditional slurry> 1.5mΩ·cm 2 ), reducing metal recombination while protecting the integrity of the passivation layer, further improving the efficiency of solar cells, and increasing cell efficiency by 0.3-0.5% (absolute efficiency value) and photoelectric conversion efficiency. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present invention are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only used as examples and are not intended to limit the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0031] Example 1

[0032] A TOPCon battery metallization silver paste based on a composite functional layer design includes the following components by mass percentage:

[0033] Metal phase: 70%;

[0034] Glass phase: 2%;

[0035] Organic carrier: 10%; of which,

[0036] The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 1 μm, the spherical nano silver powder has a D50 of 50-200 nm, and the flaky silver powder and the spherical nano silver powder are compounded in a mass ratio of 5:1;

[0037] The glass phase is low-melting-point lead borosilicate glass (softening point 450-550° C.) containing 0.5% titanium oxide (TiO2);

[0038] The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

[0039] The doping phase includes 0.1% of bismuth (Bi) nanoparticles.

[0040] The glass phase includes 0.1% cerium oxide (CeO2) as a passivation layer protective agent.

[0041] The volume ratio of the α-terpineol to the butyl carbitol acetate is 7:3.

[0042] The mass ratio of the ethyl cellulose to the polyester resin is 2:1.

[0043] The silver paste further includes a functional additive, which is 0.05% mercaptopropionic acid.

[0044] A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design comprises the following steps:

[0045] S1. Distributive mixing: Spherical nano-silver powder and doping phase were pre-mixed by ball milling in an organic carrier, and then dispersed with flaky silver powder and glass phase by high-speed shearing in an inert atmosphere at a stirring speed of 800 r / min for 2 h;

[0046] S2, gradient sintering: After the slurry fully mixed in S1 is screen-printed, it is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and activate the hydrogen atoms in the Sinx film, thereby passivating the lattice defects inside the silicon wafer.

[0047] Example 2

[0048] A TOPCon battery metallization silver paste based on a composite functional layer design includes the following components by mass percentage:

[0049] Metal phase: 75%;

[0050] Glass phase: 5%;

[0051] Organic carrier: 14.2%; of which,

[0052] The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 1 μm, the spherical nano silver powder has a D50 of 50-200 nm, and the flaky silver powder and the spherical nano silver powder are compounded in a mass ratio of 5:1;

[0053] The glass phase is low-melting-point lead borosilicate glass (softening point 450-550° C.) containing 0.5% titanium oxide (TiO2);

[0054] The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

[0055] The doping phase includes 0.1% of bismuth (Bi) nanoparticles.

[0056] The glass phase includes 0.1% cerium oxide (CeO2) as a passivation layer protective agent.

[0057] The volume ratio of the α-terpineol to the butyl carbitol acetate is 7:3.

[0058] The mass ratio of the ethyl cellulose to the polyester resin is 2:1.

[0059] The silver paste further includes a functional additive, which is 0.05% mercaptopropionic acid.

[0060] A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design comprises the following steps:

[0061] S1. Distributive mixing: Spherical nano-silver powder and doping phase were pre-mixed by ball milling in an organic carrier, and then dispersed with flaky silver powder and glass phase by high-speed shear in an inert atmosphere at a stirring speed of 900 r / min for 2 h;

[0062] S2, gradient sintering: After the slurry fully mixed in S1 is screen-printed, it is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and activate the hydrogen atoms in the Sinx film, thereby passivating the lattice defects inside the silicon wafer.

[0063] Comparative Example 1

[0064] A TOPCon battery metallization silver paste based on a composite functional layer design includes the following components by mass percentage:

[0065] Metal phase: 85%;

[0066] Glass phase: 8%;

[0067] Organic carrier: 16%; of which,

[0068] The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 3 μm, the spherical nano silver powder has a D50 of 200 nm, and the flaky silver powder and the spherical nano silver powder are compounded in a mass ratio of 3:1;

[0069] The glass phase is low-melting-point lead borosilicate glass (softening point 450-550° C.) containing 2% titanium oxide (TiO2);

[0070] The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

[0071] The doping phase includes 1% of bismuth (Bi) nanoparticles.

[0072] The glass phase includes 0.5% cerium oxide (CeO2) as a passivation layer protective agent.

[0073] The volume ratio of the α-terpineol to the butyl carbitol acetate is 7:3.

[0074] The mass ratio of the ethyl cellulose to the polyester resin is 2:1.

[0075] The silver paste further includes a functional additive, which is 0.2% mercaptopropionic acid.

[0076] A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design comprises the following steps:

[0077] S1. Distributive mixing: pre-mix the spherical nano-silver powder and the doping phase in an organic carrier by ball milling, and then disperse them with the flaky silver powder and the glass phase by high-speed shear in an inert atmosphere at a stirring speed of 1200 r / min for 6 h;

[0078] S2, gradient sintering: After the slurry fully mixed in S1 is screen-printed, it is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and activate the hydrogen atoms in the Sinx film, thereby passivating the lattice defects inside the silicon wafer.

[0079] Comparative Example 2

[0080] A TOPCon battery metallization silver paste based on a composite functional layer design includes the following components by mass percentage:

[0081] Metal phase: 78%;

[0082] Glass phase: 5%;

[0083] Organic carrier: 13%; of which,

[0084] The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 2 μm, the spherical nano silver powder has a D50 of 120 nm, and the flaky silver powder and the spherical nano silver powder are compounded in a mass ratio of 4:1;

[0085] The glass phase is low-melting-point lead borosilicate glass (softening point 450-550° C.) containing 1.2% titanium oxide (TiO2);

[0086] The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

[0087] The doping phase includes 0.5% of bismuth (Bi) nanoparticles.

[0088] The glass phase includes 0.3% cerium oxide (CeO2) as a passivation layer protective agent.

[0089] The volume ratio of the α-terpineol to the butyl carbitol acetate is 7:3.

[0090] The mass ratio of the ethyl cellulose to the polyester resin is 2:1.

[0091] The silver paste further includes a functional additive, which is 0.125% mercaptopropionic acid.

[0092] A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design comprises the following steps:

[0093] S1. Distributive mixing: Spherical nano-silver powder and doping phase were pre-mixed by ball milling in an organic carrier, and then dispersed with flaky silver powder and glass phase by high-speed shear in an inert atmosphere at a stirring speed of 1000 r / min for 4 h;

[0094] S2, gradient sintering: After the slurry fully mixed in S1 is screen-printed, it is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and activate the hydrogen atoms in the Sinx film, thereby passivating the lattice defects inside the silicon wafer.

[0095] The interface structure formed between the silver powder and the silicon substrate during the sintering process, as well as the role of the glass phase in metallization, is discussed. During sintering, the glass phase in the silver paste penetrates downward and through the anti-reflection coating, dissolving some of the silver. As the temperature decreases, silver crystals precipitate from the glass to form silver colloids. These colloids help form a good ohmic contact in the glass layer, thereby reducing the silver-silicon contact resistance and improving cell efficiency.

[0096] Table 1 Performance test results of the embodiments and comparative examples

[0097]

[0098] From the table, we can see the experimental results:

[0099] The efficiency gain is 0.23-0.28%, mainly reflected in the 1.2mV higher turn-on voltage, 16-35mA higher current, and 0.46-0.49% higher FF.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A TOPCon battery metallization silver paste based on a composite functional layer design, characterized in that: The composition includes the following components by mass percentage: Metal phase: 70-85%; Glass phase: 2-8%; Organic carrier: 10-16%; of which, The metal phase includes flaky silver powder, spherical nano silver powder and a doped phase, wherein the flaky silver powder has a D50 of 1-3 μm, the spherical nano silver powder has a D50 of 50-200 nm, and the flaky silver powder and the spherical nano silver powder are mixed in a mass ratio of 5:1-3:1; The glass phase is low melting point lead borosilicate glass containing 0.5-2% titanium oxide; The organic carrier comprises a mixed solvent consisting of alpha-terpineol and butyl carbitol acetate, and a thickener consisting of ethyl cellulose and polyester resin.

2. The TOPCon battery metallization silver paste based on the composite functional layer design according to claim 1, characterized in that: The doping phase includes 0.1-1% of bismuth or tellurium nanoparticles.

3. The TOPCon battery metallization silver paste based on the composite functional layer design according to claim 1, characterized in that: The glass phase includes 0.1-0.5% of cerium oxide as a passivation layer protective agent.

4. The TOPCon battery metallization silver paste based on the composite functional layer design according to claim 1, characterized in that: The volume ratio of the α-terpineol to the butyl carbitol acetate is 7:

3.

5. The TOPCon battery metallization silver paste based on the composite functional layer design according to claim 1, characterized in that: The mass ratio of the ethyl cellulose to the polyester resin is 2:

1.

6. The TOPCon battery metallization silver paste based on the composite functional layer design according to claim 1, characterized in that: The silver paste also includes a functional additive, which is 0.05-0.2% of mercaptopropionic acid.

7. A method for preparing a TOPCon battery metallization silver paste based on a composite functional layer design, characterized in that: The steps include: S1. Distributive mixing: pre-mix the spherical nano-silver powder and the doping phase in an organic carrier by ball milling, and then disperse them with the flaky silver powder and the glass phase by high-speed shear in an inert atmosphere at a stirring speed of 800-1200 r / min for 2-6 hours; S2, gradient sintering: After screen printing, the slurry fully mixed in S1 is pre-fired at 300℃-500℃ to evaporate the solvent in the slurry, decompose and discharge the organic resin, and soften the glass; then it is mainly fired at 730℃ to form a good ohmic contact between the glass and the anti-reflection layer, and finally it is quickly annealed at 650℃ to activate the doped atoms, eliminate lattice damage, and stimulate the hydrogen atoms in the Sinx film to combine with the silicon atoms on the silicon wafer surface with dangling bonds.

8. Use of the metallization silver paste of a TOPCon battery based on a composite functional layer design according to any one of claims 1 to 6 in the preparation of a TOPCon battery.

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