Solar cell

Abstract

The application relates to the photovoltaic technical field and provides a solar cell which comprises a solar cell base body and an electrode layer, at least one side surface of the solar cell base body is provided with an electrode groove; the electrode layer is arranged in the electrode groove and comprises a plurality of conductive layers which are arranged in a laminated mode in a direction away from the solar cell base body; the conductive layer comprises a plurality of conductive particles which are spliced with each other. The conductive particles in the conductive layer are spliced with each other in a complementary mode, the adjacent conductive particles are tightly attached to each other without any gap, and the compactness of the conductive layer is improved. Not only the water vapor erosion resistance can be improved, but also the process cost of the electrode layer is effectively reduced.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell. Background Technology

[0002] In solar cells, silver electrodes are mostly fabricated using screen-printed silver paste. However, metallic silver is expensive, resulting in high manufacturing costs. Therefore, current research focuses on using relatively low-cost copper paste or silver-coated copper paste for screen printing electrodes, or combining copper or nickel seed layer deposition with electroplating. However, these techniques have high process costs, hindering efforts to reduce the overall cost of solar cell manufacturing. Utility Model Content

[0003] Based on this, this application provides a solar cell with low manufacturing cost.

[0004] This application provides a solar cell, the solar cell comprising:

[0005] A solar cell substrate, wherein an electrode groove is formed on at least one side surface of the solar cell substrate;

[0006] An electrode layer is disposed in the electrode groove, the electrode layer comprising multiple conductive layers stacked along the direction away from the solar cell substrate; the conductive layers comprising multiple conductive particles spliced ​​together.

[0007] In some embodiments, adjacent conductive layers diffuse into each other.

[0008] In some embodiments, the solar cell further includes a plurality of catalyst particles dispersed between the electrode layer and the solar cell substrate.

[0009] In some embodiments, at least a bonding layer is provided between the electrode layer and the solar cell substrate.

[0010] In some embodiments, the conductive particles are nickel particles, and the bonding layer is a nickel-silicon alloy layer.

[0011] In some embodiments, the solar cell further includes solder strips disposed on the surface of the electrode layer opposite to the solar cell substrate.

[0012] In some embodiments, the cross-section of the solder strip is triangular, and the outer wall of the solder strip includes a welding surface, a first light-reflecting surface and a second light-reflecting surface connected in sequence, wherein the welding surface is connected to the electrode layer.

[0013] In some embodiments, the volume average particle size D50 of the conductive particles is 0.1 μm to 6 μm.

[0014] In some embodiments, the thickness of the electrode layer is 0.5 μm to 10 μm.

[0015] And / or, the width of the electrode groove is 10μm~100μm.

[0016] In some embodiments, the solar cell substrate includes a silicon substrate having a first surface, and a tunneling layer, a polycrystalline silicon layer and a first dielectric layer sequentially stacked on the first surface in a direction away from the silicon substrate, wherein the electrode groove is formed on the first dielectric layer and the electrode layer is electrically connected to the polycrystalline silicon layer.

[0017] Compared with traditional technologies, this application has at least the following beneficial effects:

[0018] In this application, the conductive particles in the conductive layer are complementary and spliced ​​together, with adjacent conductive particles tightly bonded without gaps, thus improving the density of the conductive layer. This not only enhances resistance to moisture erosion but also effectively reduces the manufacturing cost of the electrode layer. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this application;

[0020] Figure 2 This is a cross-sectional schematic diagram of the connection between the electrode layer and the solar cell provided in one embodiment of this application;

[0021] Figure 3 For this application Figure 2 A magnified view of a section at point A in the middle;

[0022] Figure 4 This is a schematic diagram of the structure of a welding strip provided in one embodiment of this application.

[0023] Among them, 100-solar cell substrate; 110-silicon substrate; 120-tunneling layer; 130-polycrystalline silicon layer; 140-first dielectric layer; 150-second dielectric layer; 200-electrode layer; 210-conductive particles; 300-catalyst particles; 400-bonding layer; 500-solder ribbon; 501-first light reflecting surface; 502-second light reflecting surface; 503-welding surface; 510-solder layer. Detailed Implementation

[0024] In traditional techniques, nickel and / or copper seed layers are formed using vapor deposition, followed by electroplating with copper or tin to thicken the gate lines and form the electrodes. However, the nickel seed layer obtained by vapor deposition is formed by the accumulation of conductive particles, resulting in numerous gaps, poor density, and susceptibility to moisture corrosion. This leads to poor electrode reliability and high manufacturing costs. Furthermore, during magnetron sputtering, sputtered atoms can damage the silicon substrate, thereby increasing carrier recombination losses.

[0025] Based on this, this application provides a solar cell. For example... Figure 1 As shown, the solar cell includes a solar cell substrate 100 and an electrode layer 200.

[0026] For example, Figure 1 As shown, electrode grooves are formed on at least one surface of the solar cell substrate 100. Figure 2 As shown, the electrode layer 200 is disposed in the electrode groove and includes multiple conductive layers stacked along the direction away from the solar cell substrate 100. Combined with... Figure 3 As shown, the conductive layer includes multiple conductive particles 210 that are spliced ​​together.

[0027] In this application, the conductive particles 210 in the conductive layer are complementary and spliced ​​together, with adjacent conductive particles 210 tightly bonded together without gaps, thus improving the density of the conductive layer. This not only improves the resistance to moisture erosion but also effectively reduces the manufacturing cost of the electrode layer 200.

[0028] It is understood that in this application, the conductive layer is formed by splicing together multiple conductive particles 210, meaning that the shapes of adjacent conductive particles 210 are complementary and can be spliced ​​together to form a complete and dense conductive layer. Therefore, the shapes of each conductive particle 210 can be the same or different.

[0029] In some embodiments, the electrode layer 200 in this application can be formed by electroless plating. Specifically, taking nickel particles as an example for the conductive particles 210, the solar cell substrate 100 with electrode grooves is placed in a nickel-containing plating solution (e.g., nickel sulfate), and electroless nickel plating is performed in the electrode grooves to form the electrode layer 200. During the electroless nickel plating process, multiple crystal nuclei are first formed in the electrode grooves, and as the crystal nuclei grow, multiple conductive particles 210 are formed and interlocked, thereby forming a dense conductive layer. Then, crystal nuclei continue to form and grow on the conductive layer to form conductive particles 210, ultimately forming an electrode layer 200 composed of multiple conductive layers.

[0030] It is understood that the solar cell substrate 100 in this application refers to a solar cell without an electrode structure. Furthermore, the electrode grooves in the solar cell substrate 100 can be formed by laser ablation. In addition, the laser-ablated electrode grooves are cleaned with a hydrofluoric acid solution to remove residues and oxides from the electrode grooves.

[0031] In some of these embodiments, for example... Figure 3 As shown, adjacent conductive layers diffuse into each other. It is understood that in this application, mutual diffusion between adjacent conductive layers refers to the close contact and mutual complementarity between two adjacent conductive layers, resulting in a tight connection between the two conductive layers. This tight connection between adjacent conductive layers further reduces the manufacturing cost of the electrode layer 200.

[0032] In some of these embodiments, such as Figure 2 As shown, the solar cell also includes multiple catalyst particles 300 dispersed between the electrode layer 200 and the solar cell substrate 100. In this application, the catalyst particles 300 are distributed on the surface of the solar cell substrate 100 in contact with the electrode layer 200, enabling the catalyst particles 300 to form an alloy phase with lower resistivity at the contact portion with the conductive particles 210. This further improves the conductivity of the contact portion between the electrode layer 200 and the solar cell substrate 100. Furthermore, during the preparation of the electrode layer 200 using electroless plating, the catalyst particles 300 can increase the growth rate of the conductive particles 210 under catalytic action.

[0033] Understandably, different catalyst particles 300 can be selected based on the material of the conductive particles 210. For example, if the conductive particles 210 are nickel particles, the catalyst particles 300 can be at least one of palladium particles, platinum particles, iridium particles, and ruthenium particles. Taking palladium particles as an example, the resulting nickel-palladium alloy phase has a lower resistivity.

[0034] In some of these embodiments, as well as Figure 2 As shown, at least a portion of the surface between the electrode layer 200 and the solar cell substrate 100 is provided with an bonding layer 400. In this application, providing a bonding layer 400 between the electrode layer 200 and the solar cell substrate 100 can improve the bonding strength between the electrode layer 200 and the solar cell substrate 100.

[0035] Optionally, the conductive particles 210 are nickel particles, and the bonding layer 400 is a nickel-silicon alloy layer. It is understood that the bonding layer 400 can be formed by the interdiffusion of nickel elements in the electrode layer 200 and silicon elements in the solar cell substrate 100. This transforms the portion of the surface where the electrode layer 200 contacts the solar cell substrate 100 into the bonding layer 400. For example, the bonding layer 400 can be formed between a portion of the solar cell substrate 100 and a portion of the electrode layer 200 by annealing the electroless nickel-plated solar cell, causing the nickel and silicon elements to interdiffusion at the contact portion between the electrode layer 200 and the solar cell substrate 100.

[0036] In some of these embodiments, such as Figure 1 As shown, the solar cell also includes a solder ribbon 500 disposed on the surface of the electrode layer 200 facing away from the solar cell substrate 100. Since the conductive layer in the electrode layer 200 of this application is formed by splicing conductive particles 210, the solder ribbon 500 can be directly connected to the surface of the electrode layer 200.

[0037] Understandably, the shape of the 500 solder strip can be selected according to actual needs. For example... Figure 4 As shown, the cross-section of the solder strip 500 is triangular or triangular-like, and the outer wall of the solder strip 500 includes a welding surface 503, a first light-reflecting surface 501, and a second light-reflecting surface 502 connected in sequence. The welding surface 503 is connected to the electrode layer 200. Furthermore, the length of the cross-section containing the welding surface 503 is less than the width of the electrode groove, allowing the electrode groove to accommodate the welding surface. This application sets the solder strip 500 into a triangular or triangular-like structure, which can improve the reflection of light by the first light-reflecting surface 501 and the second light-reflecting surface 502, as well as the secondary utilization of the reflected light by the silicon substrate, enabling more light to enter the solar cell and improving the photoelectric conversion efficiency of the solar cell.

[0038] Furthermore, for example Figure 4 As shown, a solder layer 510 is provided on the soldering surface 503 of the solder strip 500. For example, the solder layer 510 may be a tin-lead based alloy layer.

[0039] In some embodiments, the volume average particle size D50 of the conductive particles 210 is 0.1 μm to 6 μm, for example, it can be 0.1 μm, 0.2 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, or 6.0 μm. By setting the particle size of the conductive particles 210 as described above, this application can further improve the compactness of the electrode layer 200.

[0040] In some embodiments, the thickness of the electrode layer 200 is 0.5 μm to 10 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm. The selection of the electrode layer 200 thickness as described above in this application can improve the bonding tightness between adjacent conductive layers and further improve the compactness of the electrode layer 200.

[0041] In some embodiments, the width of the electrode groove is 10μm to 100μm, for example, it can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm. The electrode groove width set as described above in this application enables the multiple conductive particles 210 to be evenly dispersed in the electrode groove, further improving the splicing stability between the conductive particles 210.

[0042] This application does not specify the type of solar cell substrate 100, such as PERC (Passivated Emitter and Rear Cell), TOPCon (Tunnel Oxide Passivated Contact), and derived TBC (TOPCon Back Contact) and HTBC (Heterojunction Back Contact).

[0043] In some of these embodiments, for example... Figure 1 As shown, the solar cell substrate 100 includes a silicon substrate 110 having a first surface, and a tunneling layer 120, a polycrystalline silicon layer 130, and a first dielectric layer 140 sequentially stacked on the first surface in a direction away from the silicon substrate 110. The first dielectric layer 140 has electrode grooves formed on it, and the electrode layer 200 is electrically connected to the polycrystalline silicon layer 130.

[0044] Furthermore, the silicon substrate 110 also includes a second surface opposite to the first surface. A second dielectric layer 150 is disposed on the second surface. Alternatively, an emitter layer and a second dielectric layer 150 may be sequentially stacked on the second surface in a direction away from the silicon substrate 110.

[0045] In some embodiments, the first dielectric layer 140 and the second dielectric layer 150 may each independently include at least one of a silicon nitride layer, a silicon oxide layer, an aluminum oxide layer, a silicon carbide layer, or a silicon oxynitride layer.

[0046] By way of example, a method for preparing the above-mentioned solar cell is provided, comprising the following steps:

[0047] S1. Electrode grooves are formed on the solar cell substrate 100 by laser ablation, and then the electrode grooves are cleaned with hydrofluoric acid solution to remove residues and oxides. For example, the first dielectric layer 140 can be removed by laser ablation, thereby exposing the polycrystalline silicon layer 130.

[0048] S2. Place the electrode in a solution containing catalyst particles 300, so that the catalyst particles 300 are dispersed on the wall of the electrode tank.

[0049] S3. Placed in a process tank containing a nickel plating solution, under the catalytic action of catalyst particles 300, multiple crystal nuclei are formed in the electrode tank, and the crystal nuclei gradually grow to form conductive particles 210. Multiple conductive particles 210 are spliced ​​together to form a conductive layer. Crystal nuclei continue to form on the conductive layer and grow to form conductive particles 210, thereby forming an electrode layer 200.

[0050] S4. Annealing is performed to allow nickel atoms in the conductive particles 210 to diffuse into each other with silicon atoms in the silicon material, forming a bonding layer 400 at the contact portion between the electrode layer 200 and the solar cell substrate 100; at the same time, a nickel-silicon based alloy layer containing trace amounts of catalyst atoms is formed at the contact portion between the conductive particles 210 and the catalyst particles 300.

[0051] S5, weld 500 welding strips to produce solar cells.

[0052] In summary, this application allows for the fabrication of a nickel-based electrode layer 200 on a solar cell using electroless nickel plating. Compared to magnetron sputtering for nickel seed layer fabrication, this method is not only simpler and less expensive, but also results in lower overall costs. Furthermore, the electrode layer 200 fabricated in this application avoids the sputtering damage to the silicon substrate 110 that occurs during magnetron sputtering. In this application, the conductive particles 210 in the conductive layer are complementary and seamlessly joined, improving the density of the conductive layer. This not only enhances resistance to moisture erosion but also effectively reduces the manufacturing cost of the electrode layer 200. Moreover, the conductive particles 210 in the electrode layer 200 can be nickel particles, enabling the use of nickel as an electrode in the solar cell.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, The solar cell includes: A solar cell substrate (100) has an electrode groove formed on at least one side surface; An electrode layer (200) is disposed in the electrode groove. The electrode layer (200) includes multiple conductive layers stacked in a direction away from the solar cell substrate (100). The conductive layers include multiple conductive particles (210) spliced ​​together.

2. The solar cell as described in claim 1, characterized in that, The conductive layers diffuse into each other.

3. The solar cell as described in claim 1, characterized in that, The solar cell also includes a plurality of catalyst particles (300) dispersed between the electrode layer (200) and the solar cell substrate (100).

4. The solar cell of claim 1, wherein At least a bonding layer (400) is provided between the electrode layer (200) and the solar cell substrate (100).

5. The solar cell as described in claim 4, characterized in that, The conductive particles (210) are nickel particles, and the bonding layer (400) is a nickel-silicon alloy layer.

6. The solar cell of claim 1, wherein The solar cell also includes a solder strip (500) disposed on the surface of the electrode layer (200) on the side opposite to the solar cell substrate (100).

7. The solar cell as described in claim 6, characterized in that, The cross-section of the welding strip (500) is triangular, and the outer wall of the welding strip (500) includes a welding surface (503), a first light reflecting surface (501) and a second light reflecting surface (502) connected in sequence. The welding surface (503) is connected to the electrode layer (200).

8. Solar cell according to any of claims 1 to 7, characterized in that The volume average particle size D50 of the conductive particles (210) is 0.1 μm to 6 μm.

9. The solar cell according to any one of claims 1-7, characterized in that, The thickness of the electrode layer (200) is 0.5 μm to 10 μm; And / or, the width of the electrode groove is 10μm~100μm.

10. The solar cell according to any one of claims 1-7, characterized in that, The solar cell substrate (100) includes a silicon substrate (110) having a first surface, and a tunneling layer (120), a polycrystalline silicon layer (130) and a first dielectric layer (140) sequentially stacked on the first surface in a direction away from the silicon substrate (110). The first dielectric layer (140) has the electrode groove formed thereon, and the electrode layer (200) is electrically connected to the polycrystalline silicon layer (130).

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