HJT battery low-temperature silver paste and preparation method thereof, silver grid line electrode and HJT battery

Abstract

The invention provides HJT battery low-temperature silver paste and a preparation method thereof, a silver grid line electrode and an HJT battery, and belongs to the technical field of HJT batteries. The total mass of the low-temperature silver paste is 100%, the low-temperature silver paste comprises the following components: 70-75% of micron-scale spherical silver powder, 3-5% of nano-scale spherical silver powder, 3-5% of silver nanowires, 6-8% of thermosetting resin, 0.2-0.5% of a curing agent, 1-3% of a conductive polymer monomer, 0.1-0.2% of an initiator and the balance of an organic solvent, the length of the silver nanowires is micron-scale, and the length of the conductive polymer monomer is 1-3%. And the diameter of the silver nanowire is nanoscale. The silver grid line electrode prepared from the low-temperature silver paste has excellent conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of HJT batteries, and in particular relates to a low-temperature silver paste for HJT batteries and a preparation method thereof, a silver grid line electrode and a HJT battery. Background Art

[0002] The PN junction of the HJT battery is composed of two semiconductor materials: an N-type silicon wafer substrate (c-Si) and a doped amorphous silicon film (a-Si), so it is called a heterojunction battery. From the perspective of battery structure, HJT batteries use N-type silicon wafers as substrates. First, intrinsic hydrogenated amorphous silicon (a-Si:H) films are deposited on the front and back surfaces as a passivation structure; then a P-type doped hydrogenated amorphous silicon layer is deposited on the front surface to form a PN junction with the silicon wafer substrate, and an N-type doped hydrogenated amorphous silicon layer is deposited on the back to form a high-low junction (N+ / N) structure with the silicon wafer substrate; since hydrogenated amorphous silicon has a large contact resistance, a metal oxide layer is required as a transparent conductive film (TCO layer) to promote carrier passage and reduce reflection (ARC); finally, silver paste is printed on the TCO layers on the front and back surfaces through screen printing to form silver grid electrodes. Since hydrogenated amorphous silicon has very strict temperature requirements (not exceeding 200°C), the preparation of HJT batteries needs to adopt a low-temperature route, and the silver paste for preparing metal electrodes also needs to use low-temperature silver paste.

[0003] Low-temperature silver paste generally includes the following components: silver powder, thermosetting resin, curing agent, and organic solvent. For example, patent application document CN 109686472 A discloses a low-temperature silver paste for a single-component HJT battery, characterized in that it includes the following components in parts by weight: 50 to 90 parts of a first conductive powder, 5 to 40 parts of a second conductive powder, 1 to 2 parts of a thermosetting resin, 0 to 5 parts of a curing agent, and 0 to 5 parts of an auxiliary agent; the first conductive powder is flaky silver powder, and the second conductive powder is at least one of nano conductive powder, low-melting-point conductive metal powder, low-melting-point conductive alloy powder, high-melting-point conductive metal powder, and high-melting-point conductive alloy powder.

[0004] However, the conductivity of the silver grid line electrode formed by the low-temperature silver paste in the prior art is not high enough and still needs to be further improved. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiments of the present invention provide a HJT battery low-temperature silver paste and a preparation method thereof, a silver grid line electrode and a HJT battery.

[0006] In the first aspect, an embodiment of the present invention provides a low-temperature silver paste for an HJT battery. Taking the total mass of the low-temperature silver paste as 100%, the low-temperature silver paste includes the following components: 70-75% of micron-sized spherical silver powder, 3-5% of nano-sized spherical silver powder, 3-5% of silver nanowires, 6-8% of thermosetting resin, 0.2-0.5% of curing agent, 1-3% of conductive polymer monomer, 0.1-0.2% of initiator, and the balance is an organic solvent. The length of the silver nanowire is in the micron level, and the diameter of the silver nanowire is in the nanometer level.

[0007] The advantages and technical effects brought by the low-temperature silver paste of the embodiment of the present invention are as follows:

[0008] (1) The low-temperature silver paste of the embodiment of the present invention contains micron-sized spherical silver powder and nano-sized spherical silver powder. The pores between the spherical silver powder can be reduced by particle size grading, thereby improving the conductive performance of the silver grid line electrode.

[0009] (2) The low-temperature silver paste of the embodiment of the present invention contains silver nanowires, the length of the silver nanowires is in the micrometer order, and the diameter of the silver nanowires is in the nanometer order. The silver nanowires can play a series role between the spherical silver powders, construct more conductive channels for the low-temperature silver paste, and improve the conductive performance of the silver grid electrode.

[0010] (3) The low-temperature silver paste of the embodiment of the present invention contains a conductive polymer monomer and an initiator. After the low-temperature silver paste is subsequently printed and formed, a conductive polymer will be formed in the silver grid line electrode. The conductive polymer exists in the form of a three-dimensional network, which further improves the conductive performance of the silver grid line electrode.

[0011] In some embodiments, the Dv50 of the micron-sized spherical silver powder is 5-20 μm.

[0012] In some embodiments, the Dv50 of the nano-sized spherical silver powder is 2-6 nm.

[0013] In some embodiments, the silver nanowires have a length of 5-50 μm.

[0014] In some embodiments, the silver nanowires have a diameter of 2-6 nm.

[0015] In some embodiments, the conductive polymer monomer is selected from pyrrole and / or thiophene.

[0016] In a second aspect, an embodiment of the present invention provides a method for preparing a low-temperature silver paste for a HJT battery, comprising the following steps:

[0017] S1. mixing the micron-sized spherical silver powder, the nano-sized spherical silver powder, the silver nanowires and the organic solvent to obtain a silver powder dispersion;

[0018] S2. mixing the thermosetting resin with the silver powder dispersion to obtain a silver powder resin dispersion;

[0019] S3. mixing the curing agent, the conductive polymer monomer, the initiator and the silver powder resin dispersion to obtain a semi-finished low-temperature silver paste;

[0020] S4. Grind the semi-finished low-temperature silver paste and sieve it to obtain the low-temperature silver paste of the first aspect.

[0021] The advantages and technical effects brought by the preparation method of the embodiment of the present invention are:

[0022] (1) The preparation method of the embodiment of the present invention is simple to operate and is convenient for industrial promotion.

[0023] (2) The low-temperature conductive silver paste obtained by the preparation method of the embodiment of the present invention can significantly improve the conductive performance of the silver grid line electrode prepared subsequently.

[0024] In some embodiments, the fineness of the low-temperature silver paste is less than or equal to 20 μm.

[0025] In a third aspect, an embodiment of the present invention provides a silver grid line electrode for an HJT battery, which is obtained by printing the low-temperature silver paste for the HJT battery of the first aspect.

[0026] The advantages and technical effects brought by the silver grid line electrode of the embodiment of the present invention are as follows:

[0027] Since the low-temperature silver paste of the first aspect is used to prepare the silver grid line electrode, the silver grid line electrode of the embodiment of the present invention has excellent conductive performance.

[0028] In a fourth aspect, an embodiment of the present invention provides a HJT battery, comprising the silver grid line electrode of the third aspect.

[0029] The advantages and technical effects of the HJT battery of the embodiment of the present invention are as follows:

[0030] Since the silver grid line electrode of the third aspect is adopted, the HJT cell of the embodiment of the present invention has excellent photoelectric conversion efficiency. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0032] In the first aspect, an embodiment of the present invention provides a low-temperature silver paste for an HJT battery. Taking the total mass of the low-temperature silver paste as 100%, the low-temperature silver paste includes the following components: 70-75% of micron-sized spherical silver powder, 3-5% of nano-sized spherical silver powder, 3-5% of silver nanowires, 6-8% of thermosetting resin, 0.2-0.5% of curing agent, 1-3% of conductive polymer monomer, 0.1-0.2% of initiator, and the balance is an organic solvent. The length of the silver nanowires is in the micron level, and the diameter of the silver nanowires is in the nanometer level.

[0033] The low-temperature silver paste of the embodiment of the present invention contains micron-sized spherical silver powder and nano-sized spherical silver powder. The pores between the spherical silver powder can be reduced by particle size grading, thereby improving the conductivity of the silver grid line electrode. The low-temperature silver paste of the embodiment of the present invention contains silver nanowires. The length of the silver nanowires is micron-sized, and the diameter of the silver nanowires is nanometer-sized. The silver nanowires can play a series role between the spherical silver powders, build more conductive channels for the low-temperature silver paste, and improve the conductivity of the silver grid line electrode. The low-temperature silver paste of the embodiment of the present invention contains a conductive polymer monomer and an initiator. After the low-temperature silver paste is subsequently printed and formed, a conductive polymer will be formed in the silver grid line electrode. The conductive polymer exists in the form of a three-dimensional network, further improving the conductivity of the silver grid line electrode.

[0034] In some embodiments, the Dv50 of the micron-sized spherical silver powder is 5-20 μm, such as 5 μm, 10 μm, 15 μm, 20 μm, etc.

[0035] In some embodiments, the Dv50 of the nano-sized spherical silver powder is 2-6 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, etc.

[0036] In some embodiments, the length of the silver nanowire is 5-50 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc. When the length of the silver nanowire is too small, it is not conducive to play a good role in the construction of a conductive channel in series. When the length of the silver nanowire is too long, the silver nanowire may agglomerate, which is not conducive to improving the dispersibility of the conductive material in the low-temperature silver paste, and thus is not conducive to improving the conductive uniformity of the silver grid electrode.

[0037] In some embodiments, the diameter of the silver nanowire is 2-6 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, etc. When the diameter of the silver nanowire is too small, the cost of the silver nanowire is high, which is not conducive to reducing the production cost of the low-temperature silver paste. When the diameter of the silver nanowire is too large, it is not conducive to playing a good role in the series connection and building a conductive channel.

[0038] In some embodiments, the conductive polymer monomer is selected from pyrrole and / or thiophene. The conductive polymer formed by the conductive polymer monomers listed above has excellent conductivity, which is beneficial to improve the conductive performance of the silver grid line electrode.

[0039] The low-temperature silver paste of the embodiment of the present invention has no particular restriction on the type of initiator, as long as it can make the conductive polymer monomer generate a conductive polymer. For example, the initiator can be ammonium persulfate, etc.

[0040] The low temperature silver paste of the embodiment of the present invention has no particular restrictions on the type of thermosetting resin, and can be any thermosetting resin used for HJT low temperature silver paste in the prior art. For example, the thermosetting resin can be a bisphenol epoxy resin and / or an alicyclic epoxy resin.

[0041] The low-temperature silver paste of the embodiment of the present invention has no particular restrictions on the type of curing agent, and can be any curing agent used for HJT low-temperature silver paste in the prior art. For example, the curing agent can be a cationic curing agent or an imidazole curing agent.

[0042] The low-temperature silver paste of the embodiment of the present invention has no particular restrictions on the type of organic solvent, and can be any organic solvent used for HJT low-temperature silver paste in the prior art. For example, the organic solvent can be at least one of diethylene glycol butyl ether, terpineol, ethylene glycol phenyl ether, diethylene glycol diethyl ether and dimethyl adipate.

[0043] In a second aspect, an embodiment of the present invention provides a method for preparing a low-temperature silver paste for a HJT battery, comprising the following steps:

[0044] S1. The micron-sized spherical silver powder, the nano-sized spherical silver powder, the silver nanowires and the organic solvent are mixed to obtain a silver powder dispersion;

[0045] S2. The thermosetting resin is mixed with the silver powder dispersion to obtain a silver powder resin dispersion;

[0046] S3. The curing agent, the conductive polymer monomer, the initiator and the silver powder resin dispersion are mixed to obtain a semi-finished low-temperature silver paste;

[0047] S4. Grind the semi-finished low-temperature silver paste and sieve it to obtain the low-temperature silver paste of the first aspect.

[0048] The preparation method of the embodiment of the present invention is simple to operate and is convenient for industrial promotion. The low-temperature conductive silver paste obtained by the preparation method of the embodiment of the present invention can significantly improve the conductive properties of the subsequently prepared silver grid line electrode.

[0049] In some embodiments, the fineness of the low temperature silver paste is less than or equal to 20 μm, such as 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc. The fineness of the low temperature silver paste is less than or equal to 20 μm, which is conducive to improving the uniformity of the silver grid line electrode obtained by subsequent printing.

[0050] In a third aspect, an embodiment of the present invention provides a silver grid line electrode for an HJT battery, which is obtained by printing the low-temperature silver paste for the HJT battery of the first aspect.

[0051] Since the low-temperature silver paste of the first aspect is used to prepare the silver grid line electrode, the silver grid line electrode of the embodiment of the present invention has excellent conductive performance.

[0052] In a fourth aspect, an embodiment of the present invention provides a HJT battery, comprising the silver grid line electrode of the third aspect.

[0053] Since the silver grid line electrode of the third aspect is adopted, the HJT cell of the embodiment of the present invention has excellent photoelectric conversion efficiency.

[0054] The present invention is described in detail below with reference to embodiments.

[0055] Example 1

[0056] A low-temperature silver paste for an HJT battery. The low-temperature silver paste comprises the following components, based on the total mass of the low-temperature silver paste being 100%, 70% of spherical silver powder with a Dv50 of 5 μm, 3% of nanoscale spherical silver powder with a Dv50 of 2 nm, 3% of silver nanowires, the length of the silver nanowires being 5 μm, the diameter of the silver nanowires being 2 nm, 6% of bisphenol A epoxy resin, 0.2% of 2-methylimidazole, 1% of thiophene, 0.1% of ammonium persulfate, and the balance being dimethyl adipate.

[0057] The preparation method of the low-temperature silver paste is as follows:

[0058] (1) Mixing micron-sized spherical silver powder, nano-sized spherical silver powder, silver nanowires and an organic solvent to obtain a silver powder dispersion.

[0059] (2) The thermosetting resin and the silver powder dispersion are stirred and mixed to obtain a silver powder resin dispersion.

[0060] (3) Stirring and mixing the curing agent, the conductive polymer monomer, the initiator and the silver powder resin dispersion to obtain a semi-finished low-temperature silver paste.

[0061] (4) Grinding the semi-finished low-temperature silver paste and sieving it to obtain a low-temperature silver paste, wherein the fineness of the low-temperature silver paste is less than or equal to 20 μm.

[0062] Example 2

[0063] A low-temperature silver paste for an HJT battery. The low-temperature silver paste comprises the following components, based on the total mass of the low-temperature silver paste being 100%, 75% of spherical silver powder with a Dv50 of 20 μm, 3% of nanoscale spherical silver powder with a Dv50 of 6 nm, 5% of silver nanowires, the length of the silver nanowires being 5 μm, the diameter of the silver nanowires being 2 nm, 8% of bisphenol A type epoxy resin, 0.5% of 2-methylimidazole, 3% of thiophene, 0.2% of ammonium persulfate, and the balance being dimethyl adipate.

[0064] The preparation method of the low-temperature silver paste of this embodiment is the same as that of Example 1.

[0065] Example 3

[0066] A low-temperature silver paste for an HJT battery. The low-temperature silver paste comprises the following components, based on the total mass of the low-temperature silver paste being 100%, 72% of spherical silver powder with a Dv50 of 15 μm, 4% of nanoscale spherical silver powder with a Dv50 of 4 nm, 3% of silver nanowires, the length of the silver nanowires being 5 μm, the diameter of the silver nanowires being 2 nm, 8% of bisphenol A type epoxy resin, 0.5% of 2-methylimidazole, 3% of thiophene, 0.2% of ammonium persulfate, and the balance being dimethyl adipate.

[0067] The preparation method of the low-temperature silver paste of this embodiment is the same as that of Example 1.

[0068] Example 4

[0069] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of embodiment 3, except that the silver nanowires in the low-temperature silver paste of this embodiment contain 4%.

[0070] Example 5

[0071] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Embodiment 3, except that the low-temperature silver paste of this embodiment contains 5% silver nanowires.

[0072] Example 6

[0073] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the length of the silver nanowires is 10 μm.

[0074] Example 7

[0075] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the length of the silver nanowires is 15 μm.

[0076] Example 8

[0077] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the length of the silver nanowires is 20 μm.

[0078] Example 9

[0079] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the length of the silver nanowires is 50 μm.

[0080] Example 10

[0081] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the diameter of the silver nanowires is 4 μm.

[0082] Embodiment 11

[0083] The low-temperature silver paste and the preparation method thereof of this embodiment are the same as those of Example 3, except that in the low-temperature silver paste of this embodiment, the diameter of the silver nanowires is 6 μm.

[0084] Comparative Example 1

[0085] The low-temperature silver paste and its preparation method of this embodiment are the same as those of Example 3, except that there are no silver nanowires in the low-temperature silver paste of this embodiment, and the content of spherical silver powder with a Dv50 of 15 μm is 75%.

[0086] The low-temperature silver paste prepared in each embodiment and comparative example was printed on the TCO layer of the semi-finished HJT battery, dried at 140°C, and then cured and sintered at 200°C for 30 minutes to obtain the HJT battery. The volume resistivity of the silver grid electrode was tested, and the results are shown in Table 1.

[0087] Table 1.

[0088] Volume resistivity (mΩ·cm) Example 1 7.14E-06 Example 2 3.84E-06 Example 3 6.00E-06 Example 4 5.20E-06 Example 5 4.37E-06 Example 6 5.80E-06 Example 7 5.75E-06 Example 8 5.70E-06 Example 9 5.96E-06 Example 10 6.05E-06 Embodiment 11 6.08E-06 Comparative Example 1 8.20E-06

[0089] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0090] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A low-temperature silver paste for HJT batteries, characterized in that: Taking the total mass of the low-temperature silver paste as 100%, the low-temperature silver paste includes the following components: 70-75% of micron-sized spherical silver powder, 3-5% of nano-sized spherical silver powder, 3-5% of silver nanowires, 6-8% of thermosetting resin, 0.2-0.5% of curing agent, 1-3% of conductive polymer monomer, 0.1-0.2% of initiator, and the balance is organic solvent. The length of the silver nanowire is in the micron level, and the diameter of the silver nanowire is in the nanometer level.

2. The HJT battery low-temperature silver paste according to claim 1, characterized in that: The Dv50 of the micron-sized spherical silver powder is 5-20 μm.

3. The HJT battery low-temperature silver paste according to claim 1, characterized in that: The Dv50 of the nano-scale spherical silver powder is 2-6 nm.

4. The HJT battery low-temperature silver paste according to claim 1, characterized in that: The length of the silver nanowire is 5-50 μm.

5. The HJT battery low-temperature silver paste according to claim 1 or 4, characterized in that: The diameter of the silver nanowire is 2-6 nm.

6. The HJT battery low-temperature silver paste according to claim 1, characterized in that: The conductive polymer monomer is selected from pyrrole and / or thiophene.

7. The method for preparing low-temperature silver paste for HJT batteries according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. mixing the micron-sized spherical silver powder, the nano-sized spherical silver powder, the silver nanowires and the organic solvent to obtain a silver powder dispersion; S2. mixing the thermosetting resin with the silver powder dispersion to obtain a silver powder resin dispersion; S3. mixing the curing agent, the conductive polymer monomer, the initiator and the silver powder resin dispersion to obtain a semi-finished low-temperature silver paste; S4. Grind the semi-finished low-temperature silver paste and sieve it to obtain the low-temperature silver paste.

8. The preparation method according to claim 7, characterized in that: The fineness of the low-temperature silver paste is less than or equal to 20 μm.

9. A HJT battery silver grid electrode, characterized in that: Obtained by printing the HJT battery low-temperature silver paste according to any one of claims 1-6.

10. A HJT battery, characterized in that: It comprises the silver grid line electrode as claimed in claim 9.