Metal electrode for solar cell, its manufacturing method and mask

Abstract

The present invention provides a metal electrode for solar cells, a method for manufacturing the same, and a mask. The method for manufacturing a metal electrode for solar cells includes the steps of: etching a polymer thin film with a laser according to the desired electrode shape to manufacture a mask; and fixing the mask on a substrate and plating a metal film on the mask by physical vapor deposition to grow a metal electrode or electrode seed layer of the desired shape on the substrate. The method of the present invention has low manufacturing costs, and the manufactured electrode has high conductivity, a small light-blocking area, and a high photoelectric conversion rate.

Description

[Technical field]

[0001] The present invention relates to a metal electrode for a solar cell, a method for producing the same, and a mask used in the method. [Background technology]

[0002] Solar cells can convert solar energy into electrical energy and are an important source of clean energy. Electrodes are the key components of solar cells, and are mainly array grid structures with line widths of less than 100 μm.

[0003] Currently, the production of electrodes for solar cells generally involves the process of screen printing silver paste, and the resulting electrode line width is 30 μm or more. Silver paste is mainly composed of silver, so it is expensive. In addition, its electrical conductivity is much lower than that of metallic silver, so a relatively thick electrode grid line is required to achieve a certain electrical conductivity, which results in more raw materials being required, further increasing costs, and more sunlight being blocked when the electrode is thick. In addition, when printing electrodes for thin-film solar cells, the printing area is 0.72 m. 2 As a result, the yield is low and the requirements for equipment and processes are high. Summary of the Invention [Problem to be solved by the invention]

[0004] One of the objects of the present invention is to provide a new method for manufacturing electrodes.

[0005] Another object of the present invention is to provide a fabricated metal electrode.

[0006] Another object of the present invention is to provide a solar cell comprising the above-mentioned metal electrode. [Means for solving the problem]

[0007] In one aspect, the present invention provides a method for producing a composition comprising: Etching the polymer thin film with a laser according to a desired electrode shape to produce a mask; and b) fixing the mask onto the substrate and plating a metal film onto the mask by a physical vapor deposition (PVD) method to grow a metal electrode or an electrode seed layer of a desired shape on the substrate.

[0008] According to a specific embodiment of the present invention, in the method for manufacturing a metal electrode for a solar cell of the present invention, the material of the polymer thin film is polyethylene terephthalate (PET), polyolefin thin film (PO), polyimide (PI), polyvinyl chloride (PVC), or other polymer thin film with a thickness that meets the requirements. The polymer thin film may be a non-adhesive thin film or an adhesive polymer thin film, that is, a so-called adhesive tape.

[0009] According to a specific embodiment of the present invention, in the method for producing a metal electrode for a solar cell of the present invention, the polymer thin film has a thickness of 1 μm to 500 μm.

[0010] According to a specific embodiment of the present invention, in the method for producing a metal electrode for a solar cell of the present invention, the step of producing a mask includes producing a slit having a desired electrode shape in a polymer thin film using an ultrafast laser (a laser having a pulse width on the order of ps to fs). By using the method of the present invention, a finely processed polymer thin film mask can be produced.

[0011] According to a specific embodiment of the present invention, in the method for producing a metal electrode for a solar cell of the present invention, the width of the slit in the laser-etched polymer thin film (i.e., the width of the produced electrode line) is 1 μm to 1000 μm. Specifically, when producing fingers or normal grid lines of a crystalline silicon solar cell, the width of the slit is preferably 1 μm to 100 μm, more preferably 1 μm to 20 μm, and when producing bus bars of a crystalline silicon solar cell, the width of the slit is preferably 100 μm to 500 μm. The specific width of the slit may be determined according to the desired electrode shape. The slit length is determined according to the electrode design of the battery.

[0012] According to a specific embodiment of the present invention, in the manufacturing method of the metal electrode for solar cells of the present invention, the substrate may be a solar cell. A mask is fixed to the solar cell, and a metal film is plated on the mask by a PVD method to directly grow a metal electrode of a desired shape on the solar cell. The substrate may be another film plate (here, the other film plate refers to another film plate different from the mask). After plating the metal electrode on the substrate, it is transferred to the solar cell to become a solar electrode. For example, the purpose of making an electrode for a solar cell can be achieved by growing an electrode on a plastic thin film (any film having a perfect plane, for example, a transparent PET thin film), and then directly inverting the thin film with the electrode and attaching it to the solar cell.

[0013] According to a specific embodiment of the present invention, in the method for manufacturing a metal electrode for a solar cell of the present invention, the method for fixing the polymer thin film mask on the substrate includes a method using one or a combination of two or more of double-sided tape, adhesive, a fixing slot, and a slide stage. When an adhesive tape having adhesive properties is used for the mask, the fixing method can also be direct adhesion.

[0014] In the present invention, the solar cell is a generic term for a device in which one or more PN junctions are fabricated and capable of generating a photovoltaic effect.

[0015] According to a specific embodiment of the present invention, in the method for manufacturing a metal electrode for a solar cell of the present invention, when plating a metal film on a mask by a physical vapor deposition method, the PVD method includes a single PVD process or a combination of multiple PVD processes.

[0016] According to a specific embodiment of the present invention, in the method for producing a metal electrode for a solar cell of the present invention, the metal used includes a single metal, an alloy, a stack of multiple metals, a stack of a metal and an alloy, or a stack of an alloy and an alloy.

[0017] According to a specific embodiment of the present invention, in the method for manufacturing a metal electrode for a solar cell of the present invention, optionally, a single layer of non-metallic film is pre-deposited as a buffer layer before depositing a metal by PVD, and this buffer layer may not be added.

[0018] According to a specific embodiment of the present invention, in the method for manufacturing a metal electrode for a solar cell of the present invention, after growing a metal electrode of a desired shape (i.e., a thin line whose shape roughly matches the slit in the mask) on the solar cell, the mask may be removed.

[0019] In the manufacturing method of the present invention, an electrode that meets the electrical conductivity requirements can be directly manufactured and used, or an electrode that does not yet reach the electrical conductivity requirements can be manufactured as an electrode seed layer, and then a complete electrode can be continued to be manufactured by a non-vacuum process such as electroplating, i.e., a less expensive process.

[0020] In another aspect, the present invention also provides a metal electrode produced by the above method. The electrode produced by the present invention may be used directly or as an electrode seed layer.

[0021] In another aspect, the present invention also provides a solar cell comprising a metal electrode produced by the above method.

[0022] In another aspect, the present invention also provides a method for producing a solar cell, comprising the step of producing a metal electrode by the method for producing a metal electrode for a solar cell of the present invention.

[0023] In another aspect, the present invention also provides a mask fabricated by laser etching a thin polymer film according to a desired electrode shape.

[0024] In the present invention, a mask having thin (any width of, for example, 1 to 20 μm), accurate and controllable slits can be manufactured by using an inexpensive polymer thin film as a mask and scribing with a laser, and the mask can be used to manufacture electrodes.

[0025] According to some specific embodiments of the present invention, the present invention provides a mask having electrode-shaped slits in a thin polymer film, that is, the mask of the present invention is a thin polymer film having electrode-shaped slits formed therein.

[0026] In some embodiments of the present invention, in the mask of the present invention, the polymer thin film comprises: (1) The material of the polymer thin film is one or more of polyethylene terephthalate (PET), polyolefin thin film (PO), polyimide (PI), and polyvinyl chloride (PVC); and / or (2) The polymer thin film may have one or more of the following characteristics:

[0027] In some embodiments of the present invention, the polymer thin film mask has adhesiveness, and the adhesiveness may be a property of the polymer thin film itself, or may be a property of adding an adhesive layer to the surface of the polymer thin film. The adhesive surface of the polymer thin film may be used to adhesively fix the polymer thin film mask onto a substrate.

[0028] In some embodiments of the present invention, in the mask of the present invention, the slit has a width of 1 μm to 1000 μm.

[0029] In some embodiments of the present invention, in the mask of the present invention, the width of the slits is between 1 μm and 100 μm, preferably between 1 μm and 20 μm, and the mask is for producing fingers or regular gridlines of crystalline silicon solar cells.

[0030] In some embodiments of the present invention, in the mask of the present invention, the slits have a width of 100 μm to 500 μm, and the mask is for producing bus bars for crystalline silicon solar cells.

[0031] In some embodiments of the present invention, the mask of the present invention has a thickness that is the thickness of a polymer thin film, which may be 1 μm to 500 μm. Effect of the Invention

[0032] As described above, the present invention provides a method for producing a metal electrode for a solar cell having the following characteristics. 1. Low manufacturing cost: For the mask used in the present invention, the cost of laser manufacturing process and PVD process is low. 2. The conductivity of the produced electrodes is high. The conductivity of the metals used is higher than that of the silver paste. 3. Smaller light blocking area: The slits produced by laser can be as narrow as 1-20μm, even 1-10μm, which is narrower than those produced by traditional printing processes (30μm-80μm), has a smaller light blocking area, is more efficient, and is more precise and controllable. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a polymer thin film mask according to a first embodiment. [Diagram 2] 4 is a schematic diagram showing a state in which a mask is fixed to a solar cell in Example 1. FIG. [Diagram 3] FIG. 1 is a schematic diagram of a polymer thin film mask according to a second embodiment. [Figure 4] 11 is a schematic diagram showing a state in which a mask is fixed onto a solar cell in Example 2. FIG. [Diagram 5] FIG. 11 is a schematic diagram of a polymer thin film mask according to a third embodiment. [Figure 6] FIG. 11 is a schematic diagram showing a state in which a mask is fixed onto a solar cell in Example 3. [Figure 7] FIG. 11 is a schematic diagram showing a solar cell in which an electrode produced according to the present invention is integrated in Example 3. [Figure 8] FIG. 11 is a schematic diagram of a polymer thin film mask according to Example 4. [Figure 9] FIG. 13 is a schematic diagram showing a state in which a mask is fixed onto a solar cell in Example 4. [Figure 10] FIG. 11 is a schematic diagram showing a solar cell in which an electrode produced according to the present invention is integrated in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In order to make the technical features, objectives and beneficial effects of the present invention more clearly understandable, the technical solutions of the present invention are described in detail hereinafter, which should not be construed as limiting the possible scope of the present invention.

[0035] Example 1: Manufacturing of electrodes for HIT solar cells This example provides a method for manufacturing a finger electrode of a HIT solar cell, which includes the following steps (1) to (5). (1) A polymer thin film mask is produced by a laser, specifically, slits with a width of 20 μm and a distance of 2 mm are cut by a laser in a PET or PI plastic thin film with a thickness of 30 μm to obtain a PET or PI thin film mask 10 shown in Figure 1. The shape of the slits is determined as needed. (2) As shown in FIG. 2, the mask 10 is fixed onto the HIT solar cell 20 on which the transparent conductive film has been fabricated with double-sided tape, provided that the double-sided tape avoids the slits in step (1). (3) A film is plated by a physical vapor deposition (PVD) method to produce a metal electrode. Specifically, nickel is first plated to a thickness of 20 nm by a magnetron sputtering method, and then aluminum is plated to a thickness of 8 μm by an evaporation method. (4) The PET or PI thin film is peeled off to obtain electrode grid lines with a spacing of 2 mm, a line width of 20 μm, and a height of 8 μm. (5) Repeat steps (1) to (4) on the other side of the battery cell to obtain electrode grid lines on the other side.

[0036] The electrodes of this embodiment are much less expensive than screen-printing silver paste processes, and the 20 μm gridlines are narrower than prior art gridlines, thereby reducing solar blockage and improving the conversion efficiency of the solar cell.

[0037] Taking a 166 mm silicon wafer as an example, the results of comparing the electrode process in the prior art with the electrode manufactured by the present invention are as follows: (1) Cost Comparison In the prior art process, the amount of silver paste used in the finger is 92-125mg, the unit price of silver paste is 4800-5500CNY / kg, and the cost is about 0.5CNY / sheet; Technology of the present invention: The cost of a 30 μm thick PET film is 0.1 CNY / sheet (the cost of a 30 μm thick PI film is 0.12 CNY / sheet, Note: PI is resistant to high temperatures, has little deformation, and can be used repeatedly, calculated for 5 times), the amount of Al used (including wear and tear) is 2.8 g, 1.7 CNY / kg, 0.05 CNY / sheet, the total of adhesive and laser is 0.03 CNY / sheet, and the total is 0.18 CNY / sheet (or 0.20 CNY / sheet for PI film). (2) Comparison of shading areas Prior art process: finger is 40 μm, spacing is 1.7 mm, and light blocking rate is 2.35%; The present invention's technology: the fingers are 20 μm, the spacing is 2.0 mm, and the light blocking rate is 1.0%.

[0038] From the above comparison, it can be seen that the present invention reduces shading by 57% and costs by 60% compared to the prior art.

[0039] <Example 2> Manufacturing of electrodes (finger + bus bar) for HIT solar cells This example provides a method for producing an electrode for a HIT solar cell, comprising the following steps (1) to (5). (1) A polymer thin film mask is manufactured by a laser. Specifically, a PO plastic thin film having a thickness of 35 μm and a viscosity of its own is used to cut desired slits in the electrodes having the pattern shown in FIG. 3 by a laser, thereby obtaining a PO thin film mask 30 as shown in FIG. 3. (2) As shown in FIG. 4, a mask 30 is adhered onto the HIT solar cell 40 on which the transparent conductive film has been formed. (3) A film is plated by a physical vapor deposition (PVD) method to produce a metal electrode. Specifically, nickel is first plated to a thickness of 20 nm by a magnetron sputtering method, and then aluminum is plated to a thickness of 8 μm by an evaporation method. (4) After peeling off the PO thin film, we obtain fingers with a spacing of 2 mm, a line width of 20 μm, and a height of 8 μm, and one bus bar every 33 mm, with a width of 300 um and a height of 8 um. (5) Repeat steps (1) to (4) on the other side of the battery cell to obtain electrode grid lines on the other side. The electrodes of this embodiment are much less expensive than screen printing silver paste processes, and the 20 μm fingers and 300 μm busbars are all narrower than prior art gridlines, thereby reducing solar blockage and improving the conversion efficiency of the solar cell.

[0040] Taking a 166 mm silicon wafer as an example, the results of comparing the electrode process in the prior art with the electrode manufactured by the present invention are as follows: (1) Cost Comparison In the prior art process, the amount of silver paste used in the finger is 165-180mg, the unit price of silver paste is 4800-5500CNY / kg, and the cost is about 0.85CNY / sheet; The present invention technology: The cost of a PO film with a thickness of 35 μm is 0.18 CNY / sheet, the amount of Al used (including wear and tear) is 2.8 g, 1.7 CNY / kg, and 0.05 CNY / sheet, and the laser is 0.01 CNY / sheet, for a total of 0.26 CNY / sheet. (2) Comparison of shading areas Prior art process (5BB): finger is 40 μm, spacing is 1.7 mm, busbar is 0.7 mm, spacing is 33 mm, shading rate is 4.5%; The present invention's technology: fingers are 20 μm, spacing is 2.0 mm, bus bars are 0.3 mm, spacing is 33 mm, and light blocking rate is 1.9%.

[0041] From the above comparison, it can be seen that the present invention reduces shading by 58% and costs by 70% compared to the prior art.

[0042] Example 3: Manufacturing of electrodes for thin-film solar cells This embodiment provides a method for manufacturing an electrode for thin-film solar cells (cadmium telluride solar cells, copper-indium-gallium-selenium solar cells, perovskite solar cells) including the following steps (1) to (5). (1) A polymer thin film mask is manufactured by a laser. Specifically, a 65 μm-thick, inherently viscous PVC plastic thin film is cut by a laser to form slits with a spacing of 4 mm and a width of 80 μm in the pattern shown in FIG. 5, thereby obtaining the PVC thin film mask 50 shown in FIG. 5. (2) As shown in FIG. 6, a mask 50 is adhered onto a PET thin film 60 having a thickness of 100 μm. (3) A film is plated by a physical vapor deposition (PVD) method to produce a metal electrode. Specifically, nickel is first plated to a thickness of 20 nm by a magnetron sputtering method, then copper is plated to a thickness of 2 μm by an evaporation method, and then nickel is plated to a thickness of 20 nm by a magnetron sputtering method. (4) The PVC thin film is peeled off to obtain electrodes grown on the PET film with a spacing of 4 mm, a line width of 80 μm, and a height of 2 μm. (5) The electrode 70 grown on the PET thin film 60 obtained in step (4) is attached onto the thin-film solar cell 80 plated with a transparent conductive film layer, with one side of the electrode 70 facing the solar cell, thus completing the manufacture of the electrode, as shown in Figure 7. The electrode is attached to the surface of the cell by a subsequent process such as lamination.

[0043] The electrode of this embodiment has the following advantages. a.By growing the electrodes on the PET thin film and then sticking it upside down on the surface of the battery, it is possible to reduce the waste of the entire module due to the electrode process failure, which is particularly suitable for the manufacture of electrodes for thin film solar cells. Compared to the size of a crystalline silicon solar cell, which is 166mm in both length and width, a thin film solar cell needs to manufacture electrodes on a substrate that is 600mm in size and 1200mm in width or larger, and the larger the size, the lower the manufacturing yield. b. The cost is lower than the cost of the process of screen printing silver paste.

[0044] <Example 4> First, an electrode seed layer is prepared, and then the electrode is fabricated by a non-vacuum process. This embodiment provides a method for first preparing an electrode seed layer and then manufacturing an electrode by a non-vacuum process, which includes steps (1) to (6). (1) A polymer thin film mask is manufactured by a laser. Specifically, a 65 μm-thick, inherently viscous PVC plastic thin film is cut by a laser to form slits with intervals of 2 mm and widths of 30 μm in the pattern shown in FIG. 8, thereby obtaining the PVC thin film mask 90 shown in FIG. 8. (2) As shown in FIG. 9, a mask 90 is adhered onto a PO thin film 100 having a thickness of 100 μm. (3) Plating the film by physical vapor deposition (PVD) method to produce a metal electrode seed layer, specifically, plating copper to a thickness of 200 nm by magnetron sputtering method. (4) The PVC thin film is peeled off to obtain an electrode seed layer grown on the PO film with an interval of 2 mm, a line width of 30 μm, and a height of 200 nm. (5) Continue to plate a film to a height of 3 μm on the electrode seed layer obtained in step (4) by electroplating process. (6) The electrode 110 grown on the PO thin film 100 obtained in step (5) is attached to the thin film solar cell or HIT cell 120 plated with a transparent conductive film layer, with one side of the electrode 110 facing the solar cell, thus producing an electrode. The electrode is attached to the surface of the cell by a subsequent process such as lamination, as shown in FIG.

[0045] The electrode of this embodiment has the following advantages. a. The non-vacuum electroplating process is a low temperature process, which can efficiently carry out electrode growth. b. The cost is lower than the cost of the process of screen printing silver paste.

[0046] The above is merely a preferred embodiment of the present invention, which may be applied to other types of solar cells, and does not limit the present invention. All modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Etching the polymer thin film with a laser according to a desired electrode shape to produce a mask having slits of the desired electrode shape; The mask itself has viscosity, and the mask is moved and fixed on the substrate by adhesion, and a metal film is plated on the mask by a physical vapor deposition method to grow a metal electrode or an electrode seed layer of a desired shape on the substrate; and growing a metal electrode or electrode seed layer of a desired shape on the substrate and then stripping the mask. The metal electrode having a desired shape is used as a metal electrode for a solar cell, The method for producing a metal electrode for a solar cell, wherein the electrode seed layer is an electrode seed layer for producing a metal electrode for a solar cell.

2. 2. The method according to claim 1, wherein the polymer thin film has a thickness of 1 μm to 500 μm.

3. 2. The method according to claim 1, wherein the width of the slits is 1 μm to 100 μm when producing fingers or regular grid lines of crystalline silicon solar cells, or the width of the slits is 100 μm to 500 μm when producing bus bars of crystalline silicon solar cells.

4. 4. The method according to claim 3, wherein when manufacturing fingers or regular grid lines of crystalline silicon solar cells, the width of the slits is between 1 μm and 20 μm.

5. The method of claim 1 , wherein the substrate is a solar cell or other membrane.

6. The method of claim 1, wherein the metal used for plating includes a single metal, an alloy, a combination of multiple metals, a combination of a metal and an alloy, or a combination of an alloy and an alloy.

7. 2. The method of claim 1, further comprising the step of pre-depositing a layer of non-metallic film as a buffer layer before plating a metal film on the mask by the physical vapor deposition method.

8. The polymer thin film is made of polyethylene terephthalate (PET), a polyolefin thin film.

2. The method according to claim 1, wherein the resin is one or more of polyimide (PO), polyimide (PI), and polyvinyl chloride (PVC).

9. A method for producing a solar cell, comprising the step of producing a metal electrode by the method according to any one of claims 1 to 8.

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