A battery piece with a composite metal electrode structure
By setting a titanium nitride layer on the back of the solar cell as a bonding layer, the problem of silver grain burn-through was solved, the photoelectric conversion efficiency and voltage opening of the solar cell were improved, the process steps were simplified and the cost was reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SUZHOU JBAO TECH LTD
- Filing Date
- 2025-06-20
- Publication Date
- 2026-06-02
AI Technical Summary
In existing technologies, when preparing the ohmic contact layer, the metallic silver grains are prone to burn through the doped polycrystalline silicon film, damaging the passivation effect, resulting in a decrease in the on-state voltage of the solar cell and affecting the conversion efficiency.
A titanium nitride layer is used as the bonding layer, and the traditional ohmic contact layer is replaced by an ALD deposition process, which simplifies the process steps, maintains conductivity, and avoids the annealing and sintering process.
It improves the photoelectric conversion efficiency and voltage opening of the solar cells, reduces production costs, and simplifies the process steps.
Smart Images
Figure CN224319814U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of photovoltaic cells, specifically to a battery cell with a composite metal electrode structure. Background Technology
[0002] Currently, the industry is continuously improving two main aspects of solar module power generation efficiency. One is in cell production, where the electroplating copper process can be selectively combined with photolithography to achieve an overall grid line width of less than 15µm or even finer. This reduces shading and contact resistance. Furthermore, this method represents a complete silver-free solution that improves efficiency and reduces costs.
[0003] In the case of currently produced TOPCon cells, the back side uses silver paste to burn through the anti-reflection layer and the doped poly layer to form an ohmic contact. However, during the paste sintering process, there is a high probability that the metallic silver grains will burn through the doped polycrystalline silicon film and come into contact with the silicon oxide tunneling layer, thus destroying the passivation effect of the cell, i.e., reducing Voc.
[0004] The introduction of low-temperature electroplating deposition and baking processes for BC batteries is a direction that the industry is continuously advancing. The basic approach involves patterning and grooving using dry or wet processes, followed by the fabrication of an ohmic contact layer to connect the doped semiconductor to the metal electrode. Currently, the two most commonly used fabrication processes are: one is chemical nickel plating or vacuum deposition, followed by sintering to obtain the ohmic contact layer. Chemical nickel plating has been phased out due to the difficulty in precisely controlling the deposition thickness and the complex and difficult-to-operate chemical wet process. The other is magnetron sputtering or physical vapor deposition. While these methods allow for precise control of the deposition thickness, the high-energy plasma and charge accumulation often damage the prepared doped poly layer, leading to a decrease in the cell's on-state voltage and a loss of conversion efficiency. Utility Model Content
[0005] The purpose of this invention is to provide a battery cell with a composite metal electrode structure to solve the above-mentioned technical problems.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a battery cell with a composite metal electrode structure, comprising a battery cell body, an n-type polycrystalline silicon layer and a passivation layer disposed on the back side of the battery cell body, a first opening disposed on the passivation layer, a connecting layer disposed at the first opening, the connecting layer abutting against the n-type polycrystalline silicon layer, and a metal grid layer disposed on the side of the connecting layer away from the battery cell body, wherein the connecting layer is a titanium nitride layer.
[0007] By replacing the traditional ohmic contact layer with a conductive titanium nitride layer, an annealing and sintering process is eliminated. This solves the problem that in traditional processes, during the sintering of the ohmic contact layer, there is a high probability that the metallic silver grains will burn through the doped polycrystalline silicon film and contact the silicon oxide tunneling layer, thus compromising the passivation effect of the solar cell and causing a decrease in the on-state voltage. Furthermore, because the titanium nitride layer itself has excellent conductivity, an annealing and sintering process is unnecessary, simplifying the solar cell manufacturing process and reducing production costs.
[0008] Furthermore, the thickness of the connecting layer is 0.5–5 nm. For example, the thickness of the connecting layer can be 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, or any combination of two sets of values. Since no annealing sintering process is required, there is no particular limitation on the thickness of the connecting layer; it only needs to connect the polycrystalline silicon layer and the metal gate layer. The thickness of the connecting layer can be as low as 0.5 nm, reducing the production cost of the solar cells.
[0009] Furthermore, a p-type polycrystalline silicon layer is disposed on the back side of the solar cell body, and a third opening is disposed on the passivation layer. The third opening is located on the side of the p-type polycrystalline silicon layer away from the solar cell body, and the bonding layer is disposed at the third opening. The back side of the BC solar cell uses a bonding layer instead of the traditional ohmic contact layer, which simplifies the cell manufacturing process and solves the technical problem of voltage drop caused by the fabrication of ohmic contact layers.
[0010] Furthermore, the bonding layer is prepared using an ALD deposition process. Replacing the vacuum sputtering process with ALD deposition avoids damage to the doped poly layer during vacuum sputtering, which would otherwise reduce the on-state voltage of the solar cell.
[0011] Furthermore, a bonding layer is provided between the metal grid layer and the connecting layer, and the thickness of the bonding layer is 0.1 to 5 μm.
[0012] Furthermore, the material of the bonding layer is metallic nickel or an alloy of metallic nickel.
[0013] Furthermore, the thickness of the metal grid layer is 5–25 μm, and the material of the metal grid layer is selected from any one of gold, silver, copper, and bismuth.
[0014] Furthermore, it also includes a protective layer located on the side of the metal grid layer away from the battery cell body, the thickness of the protective layer being 0.1–5 μm, and the material of the protective layer being selected from any one of gold, silver, bismuth, and tin.
[0015] Furthermore, a passivation layer is provided on the front side of the battery cell, a second opening is provided on the passivation layer, and a p-type ohmic contact layer is provided at the second opening.
[0016] Furthermore, the thickness of the p-polar ohmic contact layer is 5–200 nm, and the material is aluminum or an aluminum alloy. Attached Figure Description
[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.
[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 A schematic diagram of the slots on a TOPCon solar cell;
[0020] Figure 2 Schematic diagram of fabrication of bonding layer and ohmic contact layer on TOPCon solar cell;
[0021] Figure 3 A schematic diagram showing the removal of the bonding layer and ohmic contact layer on the passivation layer of a TOPCon solar cell;
[0022] Figure 4 A schematic diagram of fabricating a bonding layer, a wire grid layer, and a protective layer on a TOPCon solar cell;
[0023] Figure 5 A schematic diagram of the slots on a BC solar cell;
[0024] Figure 6 Schematic diagram of the fabrication of the bonding layer on the BC solar cell;
[0025] Figure 7 A schematic diagram showing the removal of the bonding layer on the passivation layer of a BC solar cell.
[0026] Figure 8 A schematic diagram of fabricating a bonding layer, a wire grid layer, and a protective layer on a BC solar cell;
[0027] In the figure: 1. Cell body; 2. n-type polycrystalline silicon layer; 3. Passivation layer; 4a. First opening; 4b. Second opening; 4c. Third opening; 5. Alumina layer; 6. p-type polycrystalline silicon layer; 7. Connecting layer; 8. p-electrode ohmic contact layer; 9. Bonding layer; 10. Metal grid layer; 11. Protective layer. Detailed Implementation
[0028] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.
[0029] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.
[0030] A battery cell with a composite metal electrode structure in this embodiment includes a battery cell body, an n-type polycrystalline silicon layer and a passivation layer disposed on the back side of the battery cell body, a first opening disposed on the passivation layer, a connecting layer disposed at the first opening, the connecting layer abutting against the n-type polycrystalline silicon layer, and a metal grid layer disposed on the side of the connecting layer away from the battery cell body, the connecting layer being a titanium nitride layer.
[0031] The bonding layer is prepared by the following process: a TOPCon cell with a completed p electrode, n poly doped layer and anti-reflection layer is patterned and exposed to expose the p electrode region and n poly region corresponding to the composite metal electrode preparation process.
[0032] The aforementioned solar cells were fed into an ALD deposition apparatus to prepare a bonding layer in the composite metal electrode for the n-poly doped layer of the solar cells. The production parameters and ranges were as follows: the titanium precursor included, but was not limited to, titanium tetrachloride (TiCl4) and titanium tetraisopropoxy (Ti(OiPr)4), with a flow rate ranging from 0.2 to 5.0 sccm; the nitrogen precursor included, but was not limited to, anhydrous hydrazine (N2H4), with a flow rate ranging from 0.2 to 5.0 sccm; the deposition temperature ranged from 100 to 300 °C; the sputtering current ranged from 0.1 to 5 A; the deposition pressure ranged from 0.1 to 10 Torr; and the deposition time ranged from 1 to 60 min. The resulting bonding layer thickness ranged from 0.5 to 5 nm.
[0033] In some embodiments, a passivation layer is provided on the front side of the battery cell, a second opening is provided on the passivation layer, and an ohmic contact layer is provided at the second opening. The thickness of the ohmic contact layer is 5-200 nm, and the material is aluminum or an aluminum alloy.
[0034] The method for preparing the ohmic contact layer is as follows: The aforementioned solar cell is fed into a PVD deposition apparatus to prepare an ohmic contact layer on the exposed p-electrode region of the solar cell. An ohmic contact metal layer is deposited using a PVD vacuum apparatus; the material is a single metal such as aluminum or an alloy. The deposition thickness ranges from 5 to 200 nm. Specific operating conditions include an operating power of 1–10 kW, a time of 30–600 seconds, and a temperature control range of 200–350 °C, to prepare the ohmic contact metal layer on the exposed p-electrode region of the solar cell.
[0035] In some embodiments, a p-type polycrystalline silicon layer is disposed on the back side of the cell body, and a passivation layer is disposed on the side of the p-type polycrystalline silicon layer away from the cell body. A third opening is disposed on the passivation layer, the third opening exposing the p-type polycrystalline silicon layer. A connecting layer is disposed at the third opening, the connecting layer abutting against the p-type polycrystalline silicon layer, and the connecting layer is used to connect the p-type polycrystalline silicon layer and the metal grid layer.
[0036] In some embodiments, a bonding layer is provided between the metal gate layer and the connecting layer, the thickness of the bonding layer being 0.1–5 μm. The bonding layer is prepared by an electroplating deposition process. The material of the bonding layer is metallic nickel or a nickel alloy.
[0037] In some embodiments, the thickness of the metal gate layer is 5–25 μm, and the material of the metal gate layer is selected from any one of gold, silver, copper, and bismuth. The metal gate layer is prepared by an electroplating deposition process.
[0038] In some embodiments, a protective layer is further included, located on the side of the metal grid layer away from the cell body, the thickness of the protective layer being 0.1–5 μm, and the material of the protective layer being selected from any one of gold, silver, bismuth, and tin.
[0039] Example 1
[0040] Fabrication of composite metal electrodes on TOPCon solar cells
[0041] S1, see appendix Figure 1 and attached Figure 2 As shown, a first opening 4a is formed on the back side of the TOPCon cell by laser grooving, exposing the n-type polycrystalline silicon layer 2, and a second opening 4b is formed on the front side of the cell, exposing the p-type polycrystalline silicon layer 6.
[0042] The TOPCon solar cell with the n-poly area to be electroplated opened was fed into an ALD device to prepare the bonding layer 7. Specifically, titanium tetrachloride (TiCl4) gas was introduced as the titanium source at a flow rate of 3.0 sccm; anhydrous hydrazine (N2H4) was used as the nitrogen precursor at a flow rate of 1.0 sccm; the deposition temperature was 200℃; the sputtering current was 3 A; the deposition pressure was 2.5 Torr; and the deposition time was 3 min. The resulting bonding layer 7 had a thickness of 1.4 nm.
[0043] S2. A p-type ohmic contact metal layer 8 is deposited at the second opening 4b of the TOPCon solar cell using a PVD vacuum apparatus. The material of the p-type ohmic contact metal layer 8 is aluminum. The deposition thickness ranges from 30 nm. The specific operating conditions are: operating power 3 kW, time 150 seconds, and temperature control range 250 °C.
[0044] S3, see appendix Figure 3 As shown, HF with a volume concentration of 1% was used, with an operating temperature range of 25℃, an operating time of 30 seconds, and a spraying pressure of 0.5 kg / cm². 2 The bonding layer 7 and aluminum metal exposed on the surface of the battery cell are etched away.
[0045] S4, see appendix Figure 4 As shown, for the battery cell that has completed the above steps, an electroplating process is used to deposit a bonding layer 9 with a thickness of 0.5 μm. The material of the bonding layer 9 is nickel.
[0046] S5. For the battery cell that has completed the above steps, use an electroplating process to deposit a copper metal grid layer 10 with a thickness of 10um.
[0047] S6. For the battery cell that has completed the above steps, an electroplating process is used to deposit a tin protective layer 11 with a thickness of 0.5 μm onto the metal grid layer 10. This yields a TOPCon battery cell with a composite metal electrode.
[0048] Example 2
[0049] Example 2 is basically the same as Example 1, the main difference being that the thickness of the connecting layer 7 prepared in step S1 is 1.7 nm.
[0050] Example 3
[0051] Example 3 is basically the same as Example 1, the main difference being that the thickness of the connecting layer 7 prepared in step S1 is 2.7 nm.
[0052] Example 4
[0053] Example 4 is basically the same as Example 1, the main difference being that the thickness of the connecting layer 7 prepared in step S1 is 2.5 nm.
[0054] Example 5
[0055] Fabrication of composite metal electrodes on BC solar cells
[0056] S1, see appendix Figure 5 As shown, by laser grooving, a first opening 4a and a third opening 4c are formed on the back of the BC cell, exposing an n-type polycrystalline silicon layer 2 and a p-type polycrystalline silicon layer 6.
[0057] See appendix Figure 6 As shown, a BC solar cell with the first opening 4a and the third opening 4c completed was fed into an ALD (Alternating Discharge) device to prepare a bonding layer 7. The operating conditions were as follows: titanium tetrachloride (TiCl4) gas was introduced as the titanium source at a flow rate of 3.0 sccm; anhydrous hydrazine (N2H4) was used as the nitrogen precursor at a flow rate of 1.0 sccm; the deposition temperature was 200 °C; the sputtering current was 3 A; the deposition pressure was 2.5 Torr; and the deposition time was 3 min. The resulting bonding layer 7 had a thickness of 1.8 nm.
[0058] S2, see appendix Figure 7 As shown, HF with a volume concentration of 1% was used, with an operating temperature range of 25℃, an operating time of 30 seconds, and a spraying pressure of 0.5 kg / cm². 2 After etching away the bonding layer 7 exposed on the surface of the solar cell.
[0059] S3, see appendix Figure 8 As shown, for the battery cell that has completed the above steps, an electroplating process is used to deposit a nickel bonding layer 9 with a thickness of 0.5 μm.
[0060] S4. For the battery cell that has completed the above steps, use an electroplating process to deposit a copper metal grid layer 10 with a thickness of 10 μm.
[0061] S5. For the battery cell that has completed the above steps, an electroplating process is used to deposit a tin protective layer 11 with a thickness of 0.5 μm on the metal grid layer 10, thereby obtaining a BC battery cell with a composite metal electrode.
[0062] Example 6
[0063] Example 6 is basically the same as Example 5, the main difference being that the thickness of the bonding layer prepared in step S1 is 1.7 nm.
[0064] Example 7
[0065] Example 7 is basically the same as Example 5, the main difference being that the thickness of the bonding layer prepared in step S1 is 2.3 nm.
[0066] Example 8
[0067] Example 8 is basically the same as Example 5, the main difference being that the thickness of the bonding layer prepared in step S1 is 2.5 nm.
[0068] Comparative Example 1
[0069] Comparative Example 1 is basically the same as Example 1, the main difference being that in step S1, an N-type ohmic contact layer is prepared to replace the bonding layer. That is, the bonding layer 7 on the back of the battery cell is replaced by an N-type ohmic contact layer, the material of which is metallic nickel, and the thickness of which is 18.5 nm.
[0070] Comparative Example 2
[0071] Comparative Example 2 and Example 5 are basically the same, the main difference being that in step S1, an ohmic contact layer is prepared to replace the bonding layer. That is, the bonding layer on the back of the cell is replaced by the ohmic contact layer, the material of which is metallic nickel, and the thickness of the N-electrode ohmic contact layer is 15.3 nm.
[0072] Experimental Example 1
[0073] The performance of the solar cells prepared in Examples 1-4 and Comparative Example 1 was tested, and the test data are shown in Table 1.
[0074] Table 1
[0075] Eta Voc FF Rs Example 1 1.08 5.53 1.17 0.9928 Example 2 1.11 5.36 1.19 0.9921 Example 3 1.14 6.57 1.08 0.9925 Example 4 1.16 6.59 1.13 0.9935 Comparative Example 1 1 1 1 1
[0076] The performance of the solar cells prepared in Examples 5-8 and Comparative Example 2 was tested, and the test data are shown in Table 2.
[0077] Table 2
[0078] Eta Voc FF Rs Example 1 1.15 5.66 1.09 0.9933 Example 2 1.09 5.74 1.07 0.9926 Example 3 1.13 6.95 1.12 0.9916 Example 4 1.17 6.13 1.15 0.9926 Comparative Example 1 1 1 1 1
[0079] The experimental data in Tables 1 and 2 show that by replacing the ohmic contact layer in the traditional process with a bonding layer on the back of the TOPCon or BC cell, the photoelectric conversion efficiency (Eta), turn-on voltage (Voc), and fill factor (FF) of the cell are all improved, especially the turn-on voltage (Voc), which is improved by 5 to 7 times. Furthermore, the series resistance is reduced. Therefore, in this scheme, replacing the traditional ohmic contact layer with a bonding layer with good conductivity improves the performance of the cell.
[0080] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They cannot be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.
Claims
1. A battery cell with a composite metal electrode structure, characterized in that, The device includes a cell body (1), an n-type polycrystalline silicon layer (2) and a passivation layer (3) are disposed on the back side of the cell body (1), a first opening (4a) is disposed on the passivation layer (3), a connecting layer (7) is disposed at the first opening (4a), the connecting layer (7) and the n-type polycrystalline silicon layer (2) abut against each other, and a metal grid layer (10) is disposed on the side of the connecting layer (7) away from the cell body (1), the connecting layer (7) is a titanium nitride layer.
2. The battery cell with a composite metal electrode structure according to claim 1, characterized in that, The thickness of the connecting layer (7) is 0.5 to 5 nm.
3. The battery cell with a composite metal electrode structure according to claim 1, characterized in that, The connecting layer (7) is prepared by ALD deposition process.
4. The battery cell with a composite metal electrode structure according to claim 1, characterized in that, A p-type polycrystalline silicon layer (6) is provided on the back side of the cell body (1), and a third opening (4c) is provided on the passivation layer (3). The third opening (4c) is located on the side of the p-type polycrystalline silicon layer (6) away from the cell body (1), and the connecting layer (7) is provided at the third opening (4c).
5. The battery cell with a composite metal electrode structure according to any one of claims 1-4, characterized in that, A bonding layer (9) is provided between the metal grid layer (10) and the connecting layer (7), and the thickness of the bonding layer (9) is 0.1 to 5 μm.
6. The battery cell with a composite metal electrode structure according to claim 5, characterized in that, The bonding layer (9) is made of metallic nickel or an alloy of metallic nickel.
7. The battery cell with a composite metal electrode structure according to any one of claims 1-4, characterized in that, The thickness of the metal grid layer (10) is 5 to 25 μm, and the material of the metal grid layer (10) is selected from any one of gold, silver, copper and bismuth.
8. The battery cell with a composite metal electrode structure according to any one of claims 1-4, characterized in that, A protective layer (11) is provided on the side of the metal grid layer (10) away from the battery cell body (1). The thickness of the protective layer (11) is 0.1 to 5 μm, and the material of the protective layer (11) is selected from gold, silver, bismuth, and tin.
9. The battery cell with a composite metal electrode structure according to claim 1, characterized in that, A passivation layer (3) is provided on the front side of the battery cell, a second opening (4b) is provided on the passivation layer (3), and a p-type ohmic contact layer (8) is provided at the second opening (4b).
10. The battery cell with a composite metal electrode structure according to claim 9, characterized in that, The thickness of the p-pole ohmic contact layer (8) is 5-200 nm, and the material is aluminum or aluminum alloy.