A grid electrode structure of a solar cell, a manufacturing method thereof, and a solar cell

Abstract

This invention provides a grid electrode structure, fabrication method, and solar cell for a solar cell. The grid electrode structure includes parallel-distributed base metal main grid electrodes and fine grid electrodes perpendicular to the base metal main grid electrodes. Each fine grid electrode consists of a burn-through silver fine grid electrode and a non-burn-through silver fine grid electrode arranged in a straight line. The non-burn-through silver fine grid electrode is located at the overlap between the base metal main grid electrode and the fine grid electrode, while burn-through silver fine grid electrodes are located at other positions. A base metal fine grid electrode is also disposed on the surface of the burn-through silver fine grid electrode away from the cell. This invention effectively prevents the diffusion of base metal ions into the silicon substrate by placing a non-burn-through silver fine grid electrode at the overlap, realizing the application of base metal in the grid electrode structure, ensuring good light conversion efficiency of the cell, and significantly reducing costs.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to solar cells, and more particularly to a grid electrode structure, fabrication method, and solar cell of a solar cell. Background Technology

[0002] In the manufacturing of solar cells, metallization is a crucial step, playing a decisive role in the cell's performance and cost. For a long time, silver paste, with its excellent conductivity, has been the preferred choice for metallizing solar cell electrodes. However, with the rapid expansion of the solar energy industry, the scarcity of silver and its high cost (exceeding 30% of the total cost of a solar cell) pose serious challenges to the industry's sustainable development.

[0003] To overcome this bottleneck, the industry is actively exploring various cost reduction paths, among which replacing silver paste with copper paste has become one of the most promising directions. However, in practical applications, completely replacing silver paste with copper paste is not something that can be achieved overnight. Compared with silver, copper is more chemically reactive and is prone to oxidation at high temperatures. Furthermore, at high temperatures, copper atoms diffuse into the silicon substrate, which can lead to the formation of deep energy level centers inside the battery, thereby damaging the passivation effect and seriously affecting the battery's performance.

[0004] CN119541924A discloses a copper electrode material and a method for preparing copper electrodes for silicon solar cells using the same. The method involves sequentially coating a modified rosin layer, a tin-bismuth alloy layer, and another modified rosin layer onto the surface of a copper wire using non-liquid slurry technology and layer-by-layer assembly technology to obtain a copper electrode for silicon solar cells. This copper electrode exhibits low bulk resistance and good oxidation stability. Furthermore, the invention combines modified rosin with the tin-bismuth alloy, which improves the fluidity and wettability of the composite solder during fusion welding, resulting in a tighter weld and effectively reducing the interfacial contact resistance between the copper electrode and the substrate. The copper electrode also exhibits excellent adhesion and low interfacial contact resistance when fused and welded to the substrate surface.

[0005] CN117457795A discloses a base metal conductive electrode for solar cells, its fabrication method, and the solar cell itself. First, a silicon wafer covered with a protective film is selected as the silicon substrate. A laser is used to open the protective film, obtaining a laser-engraved pattern of a metal electrode with a certain width and depth. Then, a contact layer is prepared above the laser-engraved area, in contact with the silicon substrate, using inkjet printing, screen printing, vapor deposition, or electroplating. A base metal layer is then electroplated or screen-printed on top of the contact layer, serving as the main part of the base metal conductive electrode. Finally, a metal protective layer is electroplated or inkjet-printed on top of the metal layer, followed by heat treatment to obtain the base metal conductive electrode for the solar cell. This invention uses base metal instead of silver electrodes, and the contact layer protects the diffusion of base metal to the silicon substrate, reducing the surface recombination efficiency of the cell and ultimately improving the photoelectric conversion efficiency.

[0006] CN118969868A discloses a solar cell and its manufacturing method, as well as a photovoltaic module. At least one of the first grid electrode on the front side and the second grid electrode on the back side of the solar cell is configured as a silver-copper electrode. The silver-copper electrode is further designed to include a silver contact layer and a silver-clad copper layer. On one hand, the silver-copper electrode is connected to a silicon substrate through the silver contact layer, and the silver contact layer and the silicon substrate have good conductivity, resulting in low contact resistance between the silver-copper electrode and the silicon substrate, which is beneficial for ensuring good photoelectric conversion efficiency of the solar cell. On the other hand, the silver-clad copper layer includes silver-clad copper particles and silver particles, reducing the silver consumption of the first and second grid electrodes, effectively reducing the production cost of the solar cell, and improving its competitiveness.

[0007] In existing technologies, complex modifications are usually required to base metals such as copper to enable their application in solar cell grid electrodes. Therefore, it is of great significance to provide a simple grid electrode structure that includes base metals and its preparation method that is suitable for industrial production. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a grid electrode structure, fabrication method, and solar cell for solar cells. By setting a non-burn-through silver fine grid electrode at the junction of the base metal main grid electrode and the fine grid electrode, the present invention effectively prevents the diffusion of base metal ions into the silicon substrate, avoids the efficiency and power attenuation problems caused by the recombination centers generated by copper ions through grain boundary diffusion, realizes the application of base metal in the grid electrode structure, ensures good light conversion efficiency of the cell, and significantly reduces costs.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a grid electrode structure for a solar cell, the grid electrode structure comprising parallel-distributed base metal main grid electrodes and fine grid electrodes perpendicular to the base metal main grid electrodes; each of the fine grid electrodes is composed of burn-through silver fine grid electrodes and non-burn-through silver fine grid electrodes arranged along a straight line, the non-burn-through silver fine grid electrodes being disposed at the overlap between the base metal main grid electrodes and the fine grid electrodes, and the burn-through silver fine grid electrodes being disposed at other positions; a base metal fine grid electrode is also disposed on the surface of the burn-through silver fine grid electrode away from the cell.

[0011] This invention selects a base metal as the material for the base metal main grid electrode, which significantly reduces the amount of silver paste used and saves costs. At the same time, the fine grid electrode in this invention is made of silver, and the burn-through silver fine grid electrode maintains good ohmic contact with the silicon substrate to achieve low contact resistance. A non-burn-through silver fine grid electrode is set at the junction of the base metal main grid electrode and the fine grid electrode, which effectively prevents copper from diffusing into the fine grid electrode during aging, and then into the silicon substrate, generating recombination centers, which leads to the problem of solar cell efficiency and power degradation.

[0012] In this invention, the non-burn-through silver fine gate electrode refers to a fine gate electrode that has no ohmic contact with the silicon substrate; the burn-through silver fine gate electrode refers to a fine gate electrode that has an ohmic contact with the silicon substrate and is capable of collecting holes or charge carriers. The base metal includes any one or a combination of at least two of copper, aluminum, or zinc.

[0013] Preferably, the length of the non-burn-through silver fine grid electrode is 1.0 mm to 3.0 mm.

[0014] Preferably, the width of the non-burn-through silver fine grid electrode is 0.10 mm to 0.40 mm.

[0015] Preferably, the width of the burn-through silver fine grid electrode is 5μm to 80μm.

[0016] Preferably, the height of the burn-through silver fine grid electrode is less than 1.5 μm.

[0017] Preferably, the width of the base metal fine gate electrode is 30 μm to 100 μm.

[0018] Preferably, the height of the base metal fine gate electrode is 3 μm to 12 μm.

[0019] Preferably, the width of the base metal main gate electrode is 10 μm to 300 μm.

[0020] Preferably, the height of the base metal main gate electrode is 2μm to 6μm.

[0021] In a second aspect, the present invention provides a method for fabricating a gate electrode structure as described in the first aspect, the method comprising:

[0022] (1) Print non-burn-through silver grid electrode paste on the surface of the battery; dry; sinter.

[0023] (2) Print burn-through silver grid electrode paste and base metal grid electrode paste on the surface of the battery respectively, dry and sinter.

[0024] (3) Print base metal fine grid electrode paste on the battery surface, dry and cure.

[0025] This invention first prints a non-burn-through silver fine gate electrode at the junction of the main gate and the fine gate to form a barrier, preventing the base metal main gate electrode from diffusing into the silicon substrate during subsequent sintering. Therefore, only conventional processes are needed to print the base metal main gate electrode. This invention designs the gate electrode structure so that only the corresponding electrodes need to be printed at the corresponding positions, without the need for additional complex processes, making it suitable for industrial production.

[0026] Preferably, the printing chain speed in each of steps (1) to (3) is independently 50 mm / s to 300 mm / s.

[0027] Preferably, the drying temperature in each of steps (1) to (3) is independently 80 to 200°C.

[0028] Preferably, the drying time in each of steps (1) to (3) is 5s to 20s.

[0029] Preferably, the sintering temperatures in steps (1) and (2) are each independently 600°C to 800°C.

[0030] Preferably, the belt speed for sintering in step (1) and step (2) is independently 6 m / min to 15 m / min.

[0031] Preferably, the curing temperature in step (3) is 150℃~400℃.

[0032] Preferably, the curing time in step (3) is 5s to 30s.

[0033] Preferably, in step (2), the order of the printed burn-through silver fine grid electrode paste and the base metal main grid electrode paste is not important.

[0034] Preferably, in step (2), the burn-through silver fine grid electrode paste and the base metal main grid electrode paste are printed simultaneously.

[0035] Preferably, step (2) further includes laser-assisted sintering of the burn-through silver fine grid electrode, wherein the preparation sequence is as follows:

[0036] First, the burn-through silver fine grid electrode paste is printed, dried, sintered, and laser-assisted sintered; then, the base metal main grid electrode paste is printed, dried, and sintered.

[0037] Preferably, the laser power of the laser-assisted sintering is 10W to 20W.

[0038] Preferably, the laser voltage for laser-assisted sintering is 30V to 50V.

[0039] Thirdly, the present invention provides a solar cell, the solar cell comprising the grid electrode structure as described in the first aspect, or comprising the grid electrode structure prepared by the preparation method described in the second aspect.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This invention significantly reduces costs by setting the base metal main grid electrode of the battery to copper and setting a non-burn-through silver fine grid electrode at the overlap, effectively preventing the diffusion of copper into the silicon substrate, avoiding the efficiency and power decay problems caused by the recombination centers generated by the diffusion of copper ions through grain boundaries, and ensuring that the battery has good light conversion efficiency. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the solar cell grid electrode structure provided in Example 1.

[0043] Wherein, 1-copper main gate electrode; 2-fine gate electrode; 21-non-burn-through silver fine gate electrode; 22-burn-through silver fine gate electrode; 23-copper fine gate electrode. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having” and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0046] In the description of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0047] In one specific embodiment, the present invention provides a grid electrode structure for a solar cell, the grid electrode structure comprising parallel-distributed base metal main grid electrodes and fine grid electrodes perpendicular to the base metal main grid electrodes; each of the fine grid electrodes is composed of burn-through silver fine grid electrodes and non-burn-through silver fine grid electrodes arranged along a straight line, the non-burn-through silver fine grid electrodes being disposed at the overlap between the base metal main grid electrodes and the fine grid electrodes, and the burn-through silver fine grid electrodes being disposed at other positions; a base metal fine grid electrode is also disposed on the surface of the burn-through silver fine grid electrode away from the cell.

[0048] This invention selects a base metal as the material for the base metal main grid electrode, which significantly reduces the amount of silver paste used and saves costs. At the same time, the fine grid electrode in this invention is made of silver, and the burn-through silver fine grid electrode maintains good ohmic contact with the silicon substrate to achieve low contact resistance. A non-burn-through silver fine grid electrode is set at the junction of the base metal main grid electrode and the fine grid electrode, which effectively prevents copper from diffusing into the fine grid electrode during aging, and then into the silicon substrate, generating recombination centers, which leads to the problem of solar cell efficiency and power degradation.

[0049] In this invention, the base metal includes alloys comprising any one or at least two of copper, aluminum, or zinc, such as copper-aluminum alloys, copper-zinc alloys, or aluminum-zinc alloys.

[0050] In the gate electrode structure provided by the present invention, the appropriate length of the non-burn-through silver fine gate electrode can ensure that copper diffusion into the silicon substrate is prevented without significantly reducing the contact resistance.

[0051] In some embodiments, the length of the non-burn-through silver fine grid electrode is 1.0 mm to 3.0 mm, for example, it can be 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm or 3.0 mm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] In some embodiments, the width of the non-burn-through silver fine grid electrode is 0.10 mm to 0.40 mm, for example, it can be 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm or 0.40 mm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0053] In some embodiments, the width of the burn-through silver fine grid electrode is 5μm to 80μm, for example, it can be 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm or 80μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] In some embodiments, the height of the burn-through silver grid electrode is less than 1.5 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm or 1.4 μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] Preferably, the width of the base metal fine gate electrode is 30μm to 100μm, for example, it can be 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0056] In some embodiments, the height of the base metal fine gate electrode is 3μm to 12μm, for example, it can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm or 12μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0057] In some embodiments, the width of the base metal main gate electrode is 10μm to 300μm, for example, it can be 10μm, 20μm, 40μm, 60μm, 80μm, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 240μm, 260μm, 280μm or 300μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] In some embodiments, the height of the base metal gate electrode is 2μm to 6μm, for example, it can be 2μm, 3μm, 4μm, 5μm or 6μm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0059] In another specific embodiment, the present invention provides a method for fabricating a gate electrode structure as described in the foregoing specific embodiment, the method comprising:

[0060] (1) Print non-burn-through silver grid electrode paste on the surface of the battery; dry; sinter.

[0061] (2) Print burn-through silver grid electrode paste and base metal grid electrode paste on the surface of the battery respectively, dry and sinter.

[0062] (3) Print base metal fine grid electrode paste on the battery surface, dry and cure.

[0063] This invention first prints a non-burn-through silver fine gate electrode at the junction of the main gate and the fine gate to form a barrier, preventing the base metal main gate electrode from diffusing into the silicon substrate during subsequent sintering. Therefore, only conventional processes are needed to print the base metal main gate electrode. This invention designs the gate electrode structure so that only the corresponding electrodes need to be printed at the corresponding positions, without the need for additional complex processes, making it suitable for industrial production.

[0064] In this invention, the composition of the silver paste is not particularly limited. For example, the composition of the silver paste may include 70wt% to 90wt% silver powder, 10% to 20% resin and 0.1wt% to 5% glass powder. The resin includes, but is not limited to, epoxy resin or acrylate resin. This invention does not impose specific limitations, and those skilled in the art can select according to their needs.

[0065] In this invention, the burn-through silver fine gate electrode paste also includes components capable of corroding the passivation layer, such as at least one of 0.1wt%-5wt% PbO2, 0.1wt%-3wt% Al2O3, or 0.1wt%-3wt% BiF3. During sintering, the burn-through silver fine gate electrode paste corrodes the passivation layer, and the resulting burn-through silver fine gate electrode forms a good ohmic contact with the silicon substrate. The non-burn-through silver fine gate electrode paste has a high glass transition temperature of glass powder, usually above 800°C, and does not contain components capable of corroding the passivation layer. Therefore, it does not corrode the passivation layer during sintering and cannot form an ohmic contact with the silicon substrate.

[0066] In some embodiments, the printing chain speed in each of steps (1) to (3) is independently 50 mm / s to 300 mm / s, for example, it can be 50 mm / s, 75 mm / s, 100 mm / s, 125 mm / s, 150 mm / s, 175 mm / s, 200 mm / s, 225 mm / s, 250 mm / s, 275 mm / s or 300 mm / s, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0067] In some embodiments, the drying temperature in each of steps (1) to (3) is independently 80 to 200°C, for example, it can be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0068] In some embodiments, the drying time in each of steps (1) to (3) is independently 5s to 20s, for example, it can be 5s, 7s, 9s, 11s, 13s, 15s, 17s, 19s or 20s, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0069] In some embodiments, the sintering temperatures in steps (1) and (2) are each independently 600°C to 800°C, for example, 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C or 800°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0070] In some embodiments, the belt speed for sintering in step (1) and step (2) is independently 6 m / min to 15 m / min, for example, it can be 6 m / min, 7 m / min, 8 m / min, 9 m / min, 10 m / min, 11 m / min, 12 m / min, 13 m / min, 14 m / min or 15 m / min, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0071] In some embodiments, the curing temperature in step (3) is 150°C to 400°C, for example, it can be 150°C, 200°C, 250°C, 300°C, 350°C or 400°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0072] In some embodiments, the curing time in step (3) is 5s to 30s, for example, it can be 5s, 10s, 15s, 20s, 25s or 30s, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0073] In some embodiments, in step (2), the order of the printed burn-through silver fine grid electrode paste and the base metal main grid electrode paste is not important.

[0074] In some embodiments, in step (2), the burn-through silver fine grid electrode paste and the base metal main grid electrode paste are printed simultaneously.

[0075] In some embodiments, step (2) further includes laser-assisted sintering of the burn-through silver fine grid electrode, wherein the preparation sequence is as follows:

[0076] First, the burn-through silver fine grid electrode paste is printed, dried, sintered, and laser-assisted sintered; then, the base metal main grid electrode paste is printed, dried, and sintered.

[0077] In some embodiments, the laser power of the laser-assisted sintering is 10W to 20W, for example, it can be 10W, 11W, 12W, 13W, 14W, 15W, 16W, 17W, 18W, 19W or 20W, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0078] In some embodiments, the laser voltage for laser-assisted sintering is 30V to 50V, for example, it can be 30V, 32V, 34V, 36V, 38V, 40V, 42V, 44V, 46V, 48V or 50V, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0079] In yet another embodiment, the present invention provides a solar cell comprising a grid electrode structure as described in one of the preceding embodiments, or comprising a grid electrode structure prepared by the preparation method described in another of the preceding embodiments.

[0080] To clarify the technical solution of this invention, the structures of the TBC battery and the P-type TOPcon battery in the specific embodiments of this invention are as follows:

[0081] The front of the TBC cell has a textured surface, consisting of a 5nm aluminum oxide layer and a 75nm silicon nitride layer from bottom to top. The back includes P-regions, N-regions, and GAP regions. The P-regions and N-regions are polished, while the GAP regions are textured. The P-region consists of a 2nm silicon oxide tunneling oxide layer, a 300nm boron-doped polycrystalline silicon layer, a 4nm aluminum oxide layer, and a 75nm silicon nitride layer from bottom to top. The N-region consists of a 1nm silicon oxide tunneling oxide layer, a 200nm phosphorus-doped polycrystalline silicon layer, a 4nm aluminum oxide layer, and a 70nm silicon nitride layer from bottom to top. The GAP region on the back has the same structure as the textured surface on the front. The gate electrodes for the P-region and N-region are printed on the corresponding silicon nitride layer surfaces of the P-region and N-region, respectively.

[0082] The front of the P-type TOPCon cell has a textured surface, consisting of a 5nm aluminum oxide passivation layer and an 80nm silicon nitride antireflection layer from bottom to top; the back is polished, consisting of a 2nm silicon oxide tunneling oxide layer, a 150nm phosphorus-doped polycrystalline silicon layer, a 5nm aluminum oxide layer, and a 75nm silicon nitride layer from bottom to top. The gate electrodes are printed on the surface of the silicon nitride layer.

[0083] The above description is only for clearly illustrating the technical solution of the present invention and is not intended to further limit the present invention.

[0084] Example 1

[0085] This embodiment provides a grid electrode structure for a TBC battery, including a P-region grid electrode structure and an N-region grid electrode structure respectively disposed in the P-region and the N-region.

[0086] The P-region gate electrode structure and the N-region gate electrode structure are as follows: Figure 1 As shown, each of the following is independently composed of parallel copper main gate electrodes 1 and fine gate electrodes 2 perpendicular to the copper main gate electrodes. The position where the fine gate electrode 2 overlaps with the main gate electrode is a non-burn-through silver fine gate electrode 21, and the remaining positions are burn-through silver fine gate electrodes 22. The surface of the burn-through silver fine gate electrode 22 is also provided with copper fine gate electrodes 23.

[0087] In the P-region gate electrode structure, the copper main gate electrode 1 has a width of 230 μm and a height of 4 μm; the non-burn-through silver fine gate electrode 21 has a length of 2 mm and a width of 0.25 mm; the burn-through silver fine gate electrode 22 has a width of 35 μm and a height of 0.75 μm; and the copper fine gate electrode 23 has a width of 40 μm and a height of 6 μm.

[0088] In the N-region gate electrode structure, the copper main gate electrode 1 has a width of 240 μm and a height of 4.5 μm; the non-burn-through silver fine gate electrode 21 has a length of 2.5 mm and a width of 0.3 mm; the burn-through silver fine gate electrode 22 has a width of 45 μm and a height of 0.9 μm; and the copper fine gate electrode 23 has a width of 60 μm and a height of 8 μm.

[0089] This embodiment also provides a method for fabricating the grid electrode structure of the above-mentioned TBC battery, including:

[0090] At a chain speed of 200 mm / s, non-burn-through silver fine grid electrode pastes for the N and P regions were printed on the battery surface, dried at 110°C for 12 s, and sintered at 700°C with a sintering belt speed of 8 m / min to prepare non-burn-through silver fine grid electrodes 21. Then, copper main grid electrodes 1 for the N and P regions were printed on the battery surface using copper paste, and burn-through silver fine grid electrodes 22 for the N and P regions were printed on the battery surface using silver paste. The pastes were dried at 120°C for 15 s and sintered at 750°C with a sintering belt speed of 9 m / min. Finally, copper fine grid electrodes 23 were printed on the surface of the burn-through silver fine grid electrodes 22 for the N and P regions using copper paste, dried at 120°C for 15 s, and cured at 250°C for 20 s to prepare the grid electrode structure.

[0091] Example 2

[0092] This embodiment provides a grid electrode structure for a P-type TOPCon battery;

[0093] The grid line electrode structure includes parallel distributed copper main grid electrodes and fine grid electrodes perpendicular to the copper main grid electrodes. The position where the fine grid electrode overlaps with the main grid electrode is a non-burn-through silver fine grid electrode, and the remaining positions are burn-through silver fine grid electrodes. The surface of the burn-through silver fine grid electrode is also provided with copper fine grid electrodes.

[0094] In the aforementioned gate electrode structure, the copper main gate electrode has a width of 10 μm and a height of 2 μm; the non-burn-through silver fine gate electrode has a length of 1 mm and a width of 0.1 mm; the burn-through silver fine gate electrode has a width of 5 μm and a height of 0.5 μm; and the copper fine gate electrode has a width of 30 μm and a height of 3 μm.

[0095] This embodiment also provides a method for fabricating the grid electrode structure of the above-mentioned P-type TOPCon battery, including:

[0096] At a chain speed of 300 mm / s, non-burn-through silver grid electrodes and burn-through silver grid electrodes were printed on the battery surface using silver paste. They were dried at 90°C for 7 seconds and sintered at 600°C with a belt speed of 6 m / min. Then, the laser power was adjusted to 15 W and the laser voltage to 45 V for laser sintering. Next, copper main grid electrodes and copper fine grid electrodes were printed on the battery surface using copper paste. They were dried at 80°C for 5 seconds and cured at 150°C for 5 seconds to obtain the grid electrode structure.

[0097] Example 3

[0098] This embodiment provides a grid electrode structure for a TBC battery, including a P-region grid electrode structure and an N-region grid electrode structure respectively disposed in the P-region and the N-region.

[0099] The P-region gate electrode structure and the N-region gate electrode structure each independently include parallel distributed copper main gate electrodes and fine gate electrodes perpendicular to the copper main gate electrodes. The position where the fine gate electrode overlaps with the main gate electrode is a non-burn-through silver fine gate electrode, and the other positions are burn-through silver fine gate electrodes. The surface of the burn-through silver fine gate electrode is also provided with copper fine gate electrodes.

[0100] In the P-region gate electrode structure, the copper main gate electrode has a width of 280 μm and a height of 5 μm; the non-burn-through silver fine gate electrode has a length of 2.8 mm and a width of 0.36 mm; the burn-through silver fine gate electrode has a width of 75 μm and a height of 1.2 μm; and the copper fine gate electrode has a width of 95 μm and a height of 11 μm.

[0101] In the N-region gate electrode structure, the copper main gate electrode has a width of 300 μm and a height of 6 μm; the non-burn-through silver fine gate electrode has a length of 3 mm and a width of 0.4 mm; the burn-through silver fine gate electrode has a width of 80 μm and a height of 1.3 μm; and the copper fine gate electrode has a width of 100 μm and a height of 12 μm.

[0102] This embodiment also provides a method for fabricating the grid electrode structure of the above-mentioned TBC battery, including:

[0103] At a chain speed of 55 mm / s, non-burn-through silver grid electrode pastes for the N and P regions were printed on the battery surface. The pastes were dried at 160°C for 18 s and sintered at 760°C with a sintering belt speed of 13 m / min to prepare the non-burn-through silver grid electrode. Then, at a chain speed of 50 mm / s, copper main grids for the N and P regions were printed on the battery surface using copper paste. Burn-through silver grid electrodes for the N and P regions were printed on the battery surface using silver paste, respectively. The pastes were dried at 200°C for 25 s and sintered at 800°C with a sintering belt speed of 15 m / min. Finally, copper grid electrodes were printed on the surfaces of the burn-through silver grid electrodes for the N and P regions using copper paste. The pastes were dried at 180°C for 20 s and cured at 350°C for 23 s to prepare the aforementioned grid electrode structure.

[0104] Example 4

[0105] This embodiment provides a grid electrode structure for a TBC battery. Except for the length of the non-burn-through silver fine grid electrode in the P region being 0.92 mm and the length of the non-burn-through silver fine grid electrode in the N region being 0.95 mm, the rest are the same as in Embodiment 1.

[0106] Example 5

[0107] This embodiment provides a grid electrode structure for a TBC battery. Except for the length of the non-burn-through silver fine grid electrode in the P region being 3.3 mm and the length of the non-burn-through silver fine grid electrode in the N region being 3.5 mm, the rest are the same as in Embodiment 1.

[0108] Example 6

[0109] This embodiment provides a grid electrode structure for a TBC battery. Except for the width of the non-burn-through silver fine grid electrode in the P region being 0.08 mm and the width of the non-burn-through silver fine grid electrode in the N region being 0.09 mm, the rest are the same as in Embodiment 1.

[0110] Example 7

[0111] This embodiment provides a grid electrode structure for a TBC battery. Except for the width of the non-burn-through silver fine grid electrode in the P region being 0.45 mm and the width of the non-burn-through silver fine grid electrode in the N region being 0.48 mm, the rest are the same as in Embodiment 1.

[0112] Example 8

[0113] This embodiment provides a grid electrode structure for a TBC battery. Except for the burn-through silver grid electrode and the sintering temperature of the burn-through silver grid electrode being 550°C, the rest are the same as in Embodiment 1.

[0114] Example 9

[0115] This embodiment provides a grid electrode structure for a TBC battery. Except for the burn-through silver grid electrode and the sintering temperature of the burn-through silver grid electrode being 850°C, the rest are the same as in Embodiment 1.

[0116] Comparative Example 1

[0117] This comparative example provides a grid electrode structure for a TBC battery, which is the same as that in Example 1, except that the overlap is set as a burn-through silver grid.

[0118] Comparative Example 2

[0119] This comparative example provides a grid electrode structure for a P-type TOPcon battery, which is the same as that in Example 2, except that the overlap is set as a burn-through silver fine grid.

[0120] Comparative Example 3

[0121] This comparative example provides a grid electrode structure for a TBC battery, which is the same as that of Comparative Example 1, except that all electrode grid lines use silver paste.

[0122] Comparative Example 4

[0123] This comparative example provides a grid electrode structure for a P-type TOPcon battery. Except that all electrode grid lines use silver paste, the structure is the same as that in Comparative Example 2.

[0124] Performance testing:

[0125] The TBC battery and P-type TOPcon battery provided in all the above embodiments and comparative examples were subjected to IV tests, and the test results are shown in Table 1.

[0126] Table 1

[0127] Eta / % Uoc / V Isc / mA FF / % DH1000 power attenuation / % Example 1 26.864 0.7433 14.529 83.26 2.10％ Example 2 25.425 0.7364 13.828 83.57 2.43％ Example 3 26.836 0.743 14.518 83.27 2.1％ Example 4 26.901 0.7426 14.528 83.46 3.39％ Example 5 26.819 0.7433 14.522 83.16 1.83％ Example 6 26.912 0.7429 14.533 83.43 3.62％ Example 7 26.782 0.7437 14.512 83.06 1.49％ Example 8 26.682 0.7441 14.518 82.67 2.24％ Example 9 26.750 0.7426 14.514 83.07 2.16％ Comparative Example 1 26.889 0.7431 14.524 83.39 16.33％ Comparative Example 2 26.901 0.7434 14.519 83.42 18.04％ Comparative Example 3 26.89 0.7427 14.521 83.46 2.08％ Comparative Example 4 25.47 0.7354 13.832 83.81 1.96％

[0128] Based on the test results in Table 1, this invention designs the grid electrode structure of the solar cell and sets a non-burn-through silver fine grid electrode at the junction of the base metal main grid electrode and the fine grid electrode. This effectively prevents the diffusion of base metal ions into the silicon substrate and avoids the efficiency and power attenuation problems caused by the recombination centers generated by the diffusion of copper ions through grain boundaries.

[0129] According to the test results of Example 1 and Comparative Example 1, and Example 2 and Comparative Example 2, if the non-burn-through silver grid electrode is not set at the overlap, but is set entirely with burn-through silver grid electrodes, it will not be able to effectively prevent the diffusion of copper ions into the silicon mass, thereby leading to a decrease in the performance of the solar cell.

[0130] Based on the test results of Example 1 and Comparative Example 3, and Example 2 and Comparative Example 4, the grid electrode structure provided by the present invention has comparable performance to the solar cells prepared entirely with silver electrodes in Comparative Example 3 and Comparative Example 4, while greatly reducing the amount of silver paste used.

[0131] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A grid electrode structure of a solar cell, characterized by, The gate electrode structure includes parallel-distributed base metal main gate electrodes and fine gate electrodes perpendicular to the base metal main gate electrodes. Each of the fine gate electrodes is composed of burn-through silver fine gate electrodes and non-burn-through silver fine gate electrodes arranged along a straight line. The non-burn-through silver fine gate electrodes are disposed at the junction of the base metal main gate electrode and the fine gate electrode, and the burn-through silver fine gate electrodes are disposed at other positions. The burn-through silver grid electrode also has a base metal grid electrode on the side of its surface away from the battery.

2. The grid line electrode structure of claim 1, wherein, The non-burn-through silver fine grid electrode has a length of 1.0 mm to 3.0 mm and a width of 0.10 mm to 0.40 mm. And / or, the width of the burn-through silver fine grid electrode is 5μm to 80μm, and the height is less than 1.5μm; And / or, the width of the base metal fine gate electrode is 30μm to 100μm, and the height is 3μm to 12μm; And / or, the width of the base metal main gate electrode is 10μm to 300μm, and the height is 2μm to 6μm.

3. A method of manufacturing a gate line electrode structure as claimed in claim 1 or 2, characterized in that, The preparation method includes: (1) Print non-burn-through silver fine grid electrode paste on the battery surface; dry; sinter; (2) Print burn-through silver fine grid electrode paste and base metal main grid electrode paste on the surface of the battery respectively, dry; sinter; (3) Print base metal fine grid electrode paste on the battery surface, dry and cure.

4. The production method according to claim 3, wherein The printing chain speed in each of steps (1) to (3) is independently 50 mm / s to 300 mm / s.

5. The production method according to claim 3, wherein The drying temperature in each of steps (1) to (3) is 80 to 200°C, and the drying time is 5 to 20 seconds. And / or, the sintering temperature in step (1) and step (2) is independently 600°C to 800°C; And / or, the belt speed for sintering in step (1) and step (2) is independently 6 m / min to 15 m / min; And / or, the curing temperature in step (3) is 150℃~400℃, and the curing time is 5s~30s.

6. The production method according to claim 3, wherein In step (2), the order of the printed burn-through silver fine grid electrode paste and the base metal main grid electrode paste is not important.

7. The preparation method according to claim 3, characterized in that, In step (2), the burn-through silver fine grid electrode paste and the base metal main grid electrode paste are printed simultaneously.

8. The preparation method according to claim 3, characterized in that, Step (2) further includes laser-assisted sintering of the burn-through silver fine grid electrode, and the preparation sequence is as follows: First, the burn-through silver fine grid electrode paste is printed, dried, sintered, and laser-assisted sintered; then, the base metal main grid electrode paste is printed, dried, and sintered.

9. The preparation method according to claim 8, characterized in that, The laser power of the laser-assisted sintering is 10W to 20W, and the laser voltage is 30V to 50V.

10. A solar cell, characterized in that, The solar cell includes the grid electrode structure as described in claim 1 or 2, or includes the grid electrode structure prepared by the preparation method described in any one of claims 3 to 9.

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