Novel heterojunction battery piece

Abstract

The utility model discloses a novel heterojunction battery piece, which comprises first transmission layers respectively arranged on the front surface and the back surface of the novel heterojunction battery piece, metal grid lines arranged on the first transmission layers, and a second transmission layer at least arranged on one surface of the battery piece, and the second transmission layer covers the surface of the metal grid line on the corresponding surface and the surface, which is not covered by the metal grid line, of the first transmission layer. Therefore, the top surface of the metal grid line and the two side surfaces in the thickness direction are also covered by the second transmission layer, so that the function of preventing the metal grid line from being oxidized can be achieved, and the anti-oxidation effect is very good; besides, the first transmission layer and the second transmission layer together form a two-layer composite function transmission layer, so that even if the thickness of the first transmission layer is reduced to reduce the cost of indium, the overall transmission conductive effect of the cell is not affected.

Description

Technical Field

[0001] The utility model belongs to the field of photovoltaic cells, and in particular relates to a novel heterojunction cell. Background Art

[0002] Currently, on the market, the heterojunction cells generally have a first transport layer deposited on both their front and back surfaces, and then metal grid lines are prepared on the first transport layer. The first transport layer is generally a TCO thin film layer, because TCO can achieve the lateral transport (conductivity) of carriers and does not affect the light incident on the cell (transmittance). Currently, the most widely used is the indium-containing TCO thin film layer, and among the indium-containing TCO thin film layers, ITO material is representative (IWO material is also used). There are currently two conventional methods for metal grid lines. One is made by printing silver paste, and the other is prepared by electroplating copper or electroplating silver-coated copper and other feasible metals.

[0003] The above-mentioned traditional heterojunction cells have the following problems:

[0004] 1. The metal grid lines are easily oxidized. Oxidation will not only increase the resistance of the cell string series connection and thus affect the photoelectric conversion efficiency, but also make the overall color uneven and affect the appearance. To solve the oxidation problem, some manufacturers use the method of coating an antioxidant or other metal (the most commonly used is tin) on the top surface of each metal grid line one by one. Although this method can play a certain antioxidant role, the operation is carried out on each metal grid line one by one, which greatly increases the difficulty of process site setting and production operation management; moreover, the two sides of the metal grid line in terms of thickness are still not covered by the antioxidant, so the antioxidant effect is limited;

[0005] 2. The ITO layer contains indium, and the industry is currently moving towards reducing indium or even eliminating indium because indium is expensive, but simply reducing the indium content or removing indium is unrealistic. Because if the thickness of the ITO layer (i.e., the first transport layer) is simply thinned, only the transport conductivity will become worse (Rs increases), and ultimately the efficiency of the cell will decrease. Summary of the Utility Model

[0006] The purpose of the utility model is to overcome the above-mentioned disadvantages and provide a novel heterojunction cell, which is provided with a second transport layer in addition to the first transport layer, and the second transport layer covers the surface of the metal grid lines on this side and the surface of the first transport layer that is not covered by the metal grid lines, so that it can not only prevent the oxidation of the metal grid lines, but also form a composite functional transport layer together with the first transport line. Thus, even if the thickness of the first transport layer is thinned to reduce the indium cost, it will not affect the overall transport and conductivity effect of the cell.

[0007] To achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A novel heterojunction cell includes a first transmission layer disposed on at least one of the front and back surfaces thereof, a metal grid line disposed on the first transmission layer, and a second transmission layer disposed on at least one surface of the cell. The second transmission layer covers the surface of the metal grid line on the corresponding surface and the surface of the first transmission layer that is not covered by the metal grid line.

[0009] The first transmission layer is a TCO thin film layer.

[0010] The first transmission layer is set as an ITO layer or an IWO layer.

[0011] The second transmission layer is also a TCO thin film layer.

[0012] The second transmission layer is set as an AZO layer.

[0013] The thickness of the second transmission layer is set to be 5 - 70 nm.

[0014] The second transmission layer is a metal layer.

[0015] The thickness of the second transmission layer is set to be 5 - 50 nm.

[0016] The thickness of the first transmission layer is set to be 20 - 150 nm.

[0017] The second transmission layer is set as an integral structure.

[0018] The metal grid line includes a bus bar and multiple fine grids arranged in parallel. The bus bar is arranged along the periphery of the cell. The multiple fine grids are parallel to the short side of the cell or the multiple fine grids are parallel to the long side of the cell, and both ends of each fine grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a bus bar, multiple main grids and multiple fine grids. The bus bar is arranged along the periphery of the cell. The multiple main grids intersect with the multiple fine grids, and both ends of each main grid and fine grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a main grid parallel to the long side of the cell and multiple fine grids, and the main grid is arranged on one side of the cell. All the fine grids are arranged on one side of the main grid, and one end of each fine grid is connected to the main grid.

[0019] The thickness of the fine grid is 5 - 50 μm, and the width is 5 - 50 μm; the line width of the bus bar is 50 μm - 500 μm, and the thickness range is 5 μm - 50 μm, and the distance between the bus bar and the edge of the cell is 0.01 mm - 2.5 mm; or / and, the thickness of the main grid is set to be 5 - 50 μm, and the width is 50 - 150 μm.

[0020] Since the present utility model adopts the above technical solutions, the following beneficial effects are achieved:

[0021] 1. A second transmission layer is provided, and the second transmission layer covers the surface of the metal gate line and the surface of the first transmission layer that is not covered by the metal gate line. Thus, the top surface and the two side surfaces in the thickness direction of the metal gate line are also covered by the second transmission layer. In this way, not only can it prevent the oxidation of the metal gate line, but also the anti-oxidation effect is particularly good. In addition, the first transmission layer and the second transmission layer together form a two-layer composite functional transmission layer. Thus, even if the thickness of the first transmission layer is reduced to reduce the cost of indium, it will not affect the overall transmission and conductivity effect of the battery cell.

[0022] 2. The second transmission layer on either side of the battery cell is an integral single layer. Thus, it can be prepared integrally during preparation, such as by using a deposition method. Therefore, the preparation and production operation of the second transmission layer is relatively simpler. Brief Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the battery cell of the present utility model with the second transmission layer covering both sides;

[0024] Figure 2 It is a schematic diagram of the battery cell of the present utility model with the second transmission layer covering one side;

[0025] Figure 3 It is a schematic diagram of Embodiment 1 of the metal gate line distribution of the battery cell of the present utility model;

[0026] Figure 4 It is a schematic diagram of Embodiment 2 of the metal gate line distribution of the battery cell of the present utility model;

[0027] Figure 5 It is a schematic diagram of Embodiment 3 of the metal gate line distribution of the battery cell of the present utility model;

[0028] Figure 6 It is a schematic diagram of Embodiment 4 of the metal gate line distribution of the battery cell of the present utility model;

[0029] Figure 7 It is a schematic diagram of Embodiment 5 of the metal gate line distribution of the battery cell of the present utility model. Detailed Description of the Embodiment

[0030] As Figure 1 、 2 shown, the present utility model discloses a new type of heterojunction battery cell 1, which includes a first transmission layer 4 provided on at least one of the front surface 2 and the back surface 3 of the battery cell, a metal gate line 5 provided on the first transmission layer 4, and further includes a second transmission layer 6 provided on at least one side of the battery cell. The second transmission layer 6 covers the surface of the metal gate line 5 on the corresponding side and the surface of the first transmission layer 4 that is not covered by the metal gate line 5.

[0031] In one embodiment, as Figure 1 described, the first transmission layer 4, the metal grid lines 5, and the second transmission layer 6 are provided on both the front surface 2 and the back surface 3 of the novel heterojunction cell 1.

[0032] In another embodiment, the first transmission layer 4 and the metal grid lines 5 are provided on both the front surface 2 and the back surface 3 of the novel heterojunction cell 1, and the second transmission layer 6 is provided only on one side of the cell 1. The second transmission layer covers the surface of the metal grid lines 5 on this side and the surface of the first transmission layer 4 that is not covered by the metal grid lines 5. Figure 2 As shown in the figure, the second transmission layer 6 is provided on the side where the back surface 3 of the cell is located. In still another embodiment, the second transmission layer 6 can also be provided only on the side where the front surface 2 is located (not shown in the figure).

[0033] The front surface 2 and the back surface 3 of the heterojunction cell can be the P surface and the N surface respectively, that is, the front surface 2 can be the P surface and the back surface 3 can be the N surface, or the front surface 2 can be the N surface and the back surface can be the P surface.

[0034] In other embodiments, it is also possible that the first transmission layer 4, the metal grid lines 5, and the second transmission layer 6 are provided only on one of the front surface 2 and the back surface 3 of the heterojunction cell (not shown in the figure).

[0035] As Figure 3 shown in the first embodiment of the distribution of the metal grid lines 5 of the cell of the present invention, in this embodiment, the metal grid lines 5 include a bus bar 51 and a plurality of parallel thin grids 52. The bus bar 51 is provided along the periphery of the cell, and the plurality of thin grids 52 are parallel to the short side of the cell, and both ends of each thin grid 52 are respectively connected to the bus bar 51 on the corresponding side, that is, both ends of the thin grid 52 are respectively connected to the part of the bus bar 51 in the long side direction of the cell.

[0036] As Figure 4 shown in the second embodiment of the distribution of the metal grid lines 5 of the cell of the present invention, the difference between this embodiment and the first embodiment is that the plurality of thin grids 52 are parallel to the long side of the cell, and both ends of each thin grid 52 are respectively connected to the bus bar 51 on the corresponding side, that is, both ends of the thin grid 52 are respectively connected to the part of the bus bar 51 in the short side direction of the cell.

[0037] As Figure 5The third embodiment of the distribution of the metal grid lines 5 on the battery cell of the present utility model is shown. In this embodiment, the metal grid lines 5 include a bus bar 51, a plurality of main grid lines 53, and a plurality of fine grid lines 52. The bus bar 51 is arranged along the periphery of the battery cell. The plurality of main grid lines 53 intersect with the plurality of fine grid lines 52, and both ends of each main grid line 53 and the fine grid line 52 are respectively connected to the bus bar 51 on the corresponding side. And in this embodiment, the plurality of main grid lines 53 are arranged parallel to the long side of the battery cell, and the plurality of fine grid lines 52 are arranged parallel to the short side of the battery cell, and the main grid lines 53 and the fine grid lines 52 intersect perpendicularly.

[0038] As Figure 6 The fourth embodiment of the distribution of the metal grid lines 5 on the battery cell of the present utility model is shown. The difference between this embodiment and the fourth embodiment is that in this embodiment, the plurality of main grid lines 53 are arranged parallel to the short side of the battery cell, and the plurality of fine grid lines 52 are arranged parallel to the long side of the battery cell, and the main grid lines 53 and the fine grid lines 52 intersect perpendicularly.

[0039] As Figure 7 The fifth embodiment of the distribution of the metal grid lines 5 on the battery cell of the present utility model is shown. In this embodiment, the metal grid lines 5 include a main grid line 53 parallel to the long side of the battery cell and a plurality of fine grid lines 52. And the main grid line 53 is arranged on one side of the battery cell, and all the fine grid lines 52 are arranged on one side of the main grid line 53, and one end of each fine grid line 52 is connected to the main grid line 53. In this embodiment, the plurality of fine grid lines 52 are arranged parallel to each other and perpendicular to the main grid line 53.

[0040] In other embodiments, the metal grid lines 5 can also be other distribution methods, such as based on Figure 5 , Figure 6 the variation state of the shown embodiment, that is, the main grid line 53 and the fine grid line 52 are not parallel to the long side and the short side of the battery cell, but the main grid line 53 and the fine grid line 52 are arranged obliquely, and the main grid line 53 and the fine grid line 52 may not intersect perpendicularly, and after intersection, N rhombuses are formed; or based on Figure 7 the variation state of the shown embodiment, the fine grid line 52 may not be a straight grid line perpendicular to the main grid line 53, but an arc shape, as long as one end of it is connected to the main grid line 53.

[0041] That is to say, no matter which distribution method of the metal grid lines 5, the second transmission layer 6 of the present utility model can be set as needed.

[0042] In the metal grid line 5, the thickness of the main grid 53 is set to be 5 - 50 μm, and the width is 50 - 150 μm; the thickness of the fine grid 52 is 5 - 50 μm, and the width is 5 - 50 μm. The line width of the bus bar 51 is 50 μm - 500 μm; the thickness range is 5 μm - 50 μm, and the distance between the bus bar 51 and the edge of the cell is 0.01 mm - 2.5 mm. Preferably, the thickness of the main grid 53 is 8, 10, 15, 20, 25, 30, 35, 40 or 45 μm, and the width is 80, 90, 100, 110, 120, 130 or 140 μm. The thickness of the fine grid 52 is 5, 10, 15, 20, 25, 30, 35, 40 or 45 μm, and the width is 8, 10, 15, 20, 25, 30, 35, 40 or 45 μm. The line width of the bus bar 51 is 80, 100, 200, 300, 400 or 450 μm; the thickness range is 8, 10, 15, 20, 25, 30, 35, 40 or 45 μm.

[0043] In this embodiment, the first transmission layer 4 is set as a TCO thin film layer, and its materials include, but are not limited to, indium tin oxide (ITO) thin film, indium tungsten oxide thin film (IWO), indium aluminum oxide thin film, indium titanium oxide thin film, indium cesium oxide thin film, aluminum zinc oxide, gallium zinc oxide, aluminum gallium zinc oxide, tin oxide SnOx, etc., or a combination of one or more of them in different ratios to form a thin film material. In this embodiment, the first transmission layer 4 is set as an indium-containing TCO thin film layer. Further, it is an ITO layer, and it can be the ITO layer of 991, or an IWO layer, and its thickness is set to be 20 - 150 nm.

[0044] The second transmission layer 6 can also be a TCO thin film layer, and it is an indium-free TCO thin film layer. Further, it is an AZO layer, and it can be the AZO layer of 90 / 10, and the thickness is set to be 5 - 70 nm.

[0045] The second transmission layer 6 can also be a metal layer or a metal compound layer, including, but not limited to, one of metals such as gold, silver, copper, aluminum, tin, nickel, tungsten, etc., or an alloy composition thereof. The alloy also belongs to a metal, and its thickness is set to be 5 - 50 nm.

[0046] Preferably, the second transmission layer 6 is set as an integral structure, that is, an integral layer.

[0047] When fabricating the heterojunction solar cell of the present utility model, vacuum deposition processes such as PVD and RPD can be used to deposit the first transport layer 4 on the front and back surfaces of the solar cell; then, the metal grid lines 5 are fabricated on the first transport layer 4. The metal grid lines 5 can be formed on the first transport layer 4 by screen-printing silver paste or by electroplating; after the metal grid lines 5 are fabricated, the second transport layer 6 is deposited on the side surfaces of the solar cell as required by PVD deposition process. For example, if the second transport layer 6 is to be provided on both sides of the solar cell, after the first transport layer 4 and the metal grid lines 5 are fabricated on the front and back surfaces, the second transport layer 6 is deposited on both side surfaces. During deposition, as long as the exposed parts of the side surfaces where the second transport layer 6 needs to be provided are covered by the second transport layer 6. Thus, after deposition, the surfaces of the metal grid lines 5 on the corresponding surfaces (including the top surface and the two side surfaces in the thickness direction of the metal grid lines 5) are covered by the second transport layer 6, and the parts of the first transport layer 4 surface not covered by the metal grid lines 5 are also covered by the second transport layer 6.

[0048] The following describes the fabrication of the heterojunction solar cell of the present utility model with different fabrication schemes:

[0049] Scheme 1, the steps include:

[0050] S1. Using a deposition process, ITO layers of 991 are fabricated on both the front and back surfaces of the solar cell as the first transport layer 4, and the deposition thickness of the first transport layer 4 on the back surface 3 and the front surface is 40 nm;

[0051] S2. Using a yellow light process and an electroplating process, copper metal grid lines 5 are fabricated on the two first transport layers 4. The thicknesses of the main grid 53 and the fine grid on the front surface are both 10 μm, the thicknesses of the main grid 53 and the fine grid on the back surface are both 5 μm, the width of the main grid on the front and back surfaces is 80 μm, and the width of the fine grid is 18 μm;

[0052] S3. Using a deposition process, AZO layers are fabricated on the back surface 3 and P of the solar cell as the second transport layer 6, and the thickness of the AZO layer is 55 nm.

[0053] Thus, the heterojunction solar cell of the present utility model is obtained.

[0054] Scheme 2, the steps include:

[0055] S1. Using a deposition process, ITO layers of 991 are fabricated on both the back surface 3 and the front surface of the solar cell as the first transport layer 4, and the deposition thickness of the first transport layer 4 on the back surface 3 and the front surface is 40 nm;

[0056] S2. Prepare the metal grid lines 5 on the ITO layers on both sides of the cell, and the thicknesses of the main grids 53 and the fine grids on the front and back are both 10 μm, the width of the main grid is 80 μm, and the width of the fine grid is 30 μm.

[0057] S3. By means of a deposition process, prepare an AZO layer as the second transport layer 6 on the back 3 and P of the cell, and the thickness of the AZO layer is 50 nm.

[0058] Thus, the heterojunction cell of the present utility model is obtained.

[0059] Solution three, the steps include:

[0060] S1. By means of a deposition process, form an ITO layer as the first transport layer 4 on the back 3 and the front of the cell, and the deposition thickness of the first transport layer 4 on the back 3 is 80 nm, and the deposition thickness of the first transport layer 4 on the front is 50 nm.

[0061] S2. Prepare the metal grid lines 5 on the ITO layers on both sides of the cell by means of a printed silver paste process, and the thicknesses of the main grids 53 and the fine grids on the front and back are both 10 μm, the width of the main grid is 80 μm, and the width of the fine grid 52 is 40 μm.

[0062] S3. By means of a deposition process, deposit silver paste on the front of the cell to form a silver layer, which is the second transport layer 6, and the thickness of the second transport layer 6 is 10 nm.

[0063] Thus, the heterojunction cell of the present utility model is obtained.

[0064] The above-mentioned deposition, electroplating, printed silver paste process, yellow light process, etc. are all conventional technologies and are not the invention points of the present utility model, so they will not be elaborated here.

[0065] As described above, because the second transport layer 6 is arranged as above, the second transport layer 6 covers the surface of the metal grid lines 5 and the surface of the first transport layer 4 not covered by the metal grid lines 5, that is, the top surface of the metal grid lines 5 and both side surfaces in the thickness direction are covered by the second transport layer 6. In this way, not only can the oxidation of the metal grid lines 5 be prevented, but also the anti-oxidation effect is particularly good; in addition, the first transport layer 4 and the second transport layer 6 together form a two-layer composite functional transport layer, so that even if the thickness of the first transport layer 4 is reduced to reduce the cost of indium, it will not affect the overall transport and conduction effect of the cell; furthermore, because the second transport layer 6 is an integral structure, it can be prepared integrally during preparation, such as by means of deposition. Therefore, the preparation and production operation of the second transport layer 6 is relatively simpler.

[0066] The above has described the embodiments of the present utility model in detail, but the above content is only the preferred embodiments of the present utility model and cannot be considered as limiting the scope of implementation of the present utility model. Any equivalent changes and improvements made within the scope of the application of the present utility model shall still fall within the scope covered by the patent of the present utility model.

Claims

1. A novel heterojunction cell, comprising a first transmission layer disposed on at least one of the front and back surfaces thereof, and metal grid lines disposed on the first transmission layer, characterized in that: It further includes a second transmission layer disposed at least on one side of the cell, and the second transmission layer covers the surface of the metal grid line on the corresponding side and the surface of the first transmission layer that is not covered by the metal grid line.

2. The novel heterojunction cell according to claim 1, wherein: The first transmission layer is a TCO thin film layer.

3. The novel heterojunction cell according to claim 2, characterized in that: The first transmission layer is set as an ITO layer or an IWO layer.

4. The novel heterojunction cell according to claim 1 or 2 or 3, characterized in that: The second transmission layer is set as a TCO thin film layer.

5. The novel heterojunction cell according to claim 4, characterized in that: The second transmission layer is set as an AZO layer.

6. The novel heterojunction cell according to any one of claims 1 to 3 and 5, characterized in that: The thickness of the second transmission layer is set to 5 - 70 nm.

7. The novel heterojunction cell according to claim 1 or 2 or 3, characterized in that: The second transmission layer is a metal layer.

8. The novel heterojunction cell according to claim 7, wherein: The thickness of the second transmission layer is set to 5 - 50 nm.

9. The novel heterojunction cell according to any one of claims 1 to 3, 5, and 8, characterized in that: The thickness of the first transmission layer is set to 20 - 150 nm.

10. The novel heterojunction cell according to any one of claims 1 to 3, 5, and 8, characterized in that: The second transmission layer is set as an integral structure.

11. The novel heterojunction cell according to any one of claims 1 to 3, 5, and 8, characterized in that: The metal grid line includes a bus bar and multiple parallel thin grids. The bus bar is disposed along the peripheral side of the cell. The multiple thin grids are parallel to the short side of the cell or the multiple thin grids are parallel to the long side of the cell, and both ends of each thin grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a bus bar, multiple main grids and multiple thin grids. The bus bar is disposed along the peripheral side of the cell. The multiple main grids intersect with the multiple thin grids, and both ends of each main grid and thin grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a main grid parallel to the long side of the cell and multiple thin grids, and the main grid is disposed on one side of the cell, all the thin grids are disposed on one side of the main grid, and one end of each thin grid is connected to the main grid.

12. The novel heterojunction cell according to claim 11, characterized in that: The thickness of the thin grid is 5 - 50 μm, and the width is 5 - 50 μm.

13. The novel heterojunction cell according to claim 10, characterized in that: The metal grid line includes a bus bar and multiple parallel thin grids. The bus bar is disposed along the peripheral side of the cell. The multiple thin grids are parallel to the short side of the cell or the multiple thin grids are parallel to the long side of the cell, and both ends of each thin grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a bus bar, multiple main grids and multiple thin grids. The bus bar is disposed along the peripheral side of the cell. The multiple main grids intersect with the multiple thin grids, and both ends of each main grid and thin grid are respectively connected to the bus bar on the corresponding side; or, the metal grid line includes a main grid parallel to the long side of the cell and multiple thin grids, and the main grid is disposed on one side of the cell, all the thin grids are disposed on one side of the main grid, and one end of each thin grid is connected to the main grid.

14. The novel heterojunction cell according to claim 11, wherein: The thickness of the thin grid is 5 - 50 μm, and the width is 5 - 50 μm.

15. The novel heterojunction cell according to claim 12 or 13 or 14, characterized in that: The line width of the bus bar is 50 μm - 500 μm, the thickness range is 5 μm - 50 μm, and the distance between the bus bar and the edge of the cell is 0.01 mm - 2.5 mm.

16. The novel heterojunction cell according to claim 15, characterized in that: The thickness of the main grid is set to 5 - 50 μm, and the width is 50 - 150 μm.

Images