Method for preparing a solar cell

Abstract

This application relates to the technical field of solar cells, and provides a preparation method of a solar cell, which is at least beneficial to improving the efficiency and yield of the solar cell. The preparation method includes: providing a cell wafer, the cell wafer includes a substrate and a first passivation layer and a second passivation layer located on both surface sides of the substrate, and a first grid line is provided on the first passivation layer; placing the cell wafer on glass, with the second passivation layer facing the glass and the first passivation layer facing away from the glass; performing a double-sided light treatment on the cell wafer, the double-sided light treatment includes: performing a first laser treatment on the first passivation layer and performing a second laser treatment on the second passivation layer through the glass, the first laser treatment and the second laser treatment burn through the first passivation layer and the substrate to form an ohmic contact, the first laser treatment is used to generate heat, the second laser treatment is used to generate carriers, and the laser power of the first laser treatment is higher than the laser power of the second laser treatment.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and particularly relates to a method for manufacturing a solar cell. Background Art

[0002] The contact resistance between the electrodes on a crystalline silicon solar cell and the semiconductor substrate has a great influence on the fill factor and conversion efficiency. The lower the contact resistance, the higher the fill factor and conversion efficiency. Reducing the contact resistance has become an urgent need for solar cell manufacturers.

[0003] The sintering processes of conventional electrodes include thermal sintering and laser-assisted sintering. Thermal sintering uses a traditional gas-flow thermal cycle sintering furnace to sinter the paste on the solar cell; laser-assisted sintering combines laser and reverse current to promote the sintering of the paste.

[0004] However, the sintering processes of conventional electrodes are likely to cause damage to the cell wafers, thereby resulting in a reduction in the efficiency and yield of solar cells. Summary of the Invention

[0005] An embodiment of this application provides a method for manufacturing a solar cell, which is at least conducive to improving the efficiency and yield of the solar cell.

[0006] According to some embodiments of this application, on the one hand, an embodiment of this application provides a method for manufacturing a solar cell, including: providing a cell wafer, the cell wafer including a substrate and a first passivation layer and a second passivation layer located on both surface sides of the substrate, and a first grid line on the first passivation layer; placing the cell wafer on glass, with the second passivation layer facing the glass and the first passivation layer facing away from the glass; performing a double-sided light treatment on the cell wafer, the double-sided light treatment including: performing a first laser treatment on the first passivation layer and performing a second laser treatment on the second passivation layer through the glass. The first laser treatment and the second laser treatment burn through the first passivation layer to form an ohmic contact with the substrate, the area of the first laser treatment is the first laser area, and the first laser area is located around the first grid line; the area of the second laser treatment is the second laser area, and the second laser area covers the second passivation layer. The first laser treatment is used to generate heat, the second laser treatment is used to generate carriers, and the laser power of the first laser treatment is higher than the laser power of the second laser treatment.

[0007] In some embodiments, there is a second grid line on the second passivation layer. When performing the double-sided light treatment on the cell wafer, it further includes: performing a third laser treatment on the first passivation layer. The third laser treatment and the second laser treatment burn through the second passivation layer to form an ohmic contact with the substrate. The area of the third laser treatment is the third laser area, and the orthographic projection of the third laser area on the surface of the first passivation layer is located around the orthographic projection of the second grid line on the first passivation layer. The third laser treatment is used to generate heat.

[0008] In some embodiments, the temperature generated by the laser in the third laser treatment is higher than the temperature generated by the laser in the first laser treatment.

[0009] In some embodiments, a second gate line is further provided on the first passivation layer, and the first laser region is also located around the second gate line. During the double-sided light treatment of the cell, the first laser treatment and the second laser treatment also burn through the second gate line to form an ohmic contact with the substrate through the first passivation layer.

[0010] In some embodiments, the double-sided light treatment further includes: performing a fourth laser treatment on the first passivation layer. The area of the fourth laser treatment is the fourth laser region, and the fourth laser region covers at least the area on the first passivation layer other than the first laser region. The laser power of the fourth laser treatment is less than the laser power of the first laser treatment, and the fourth laser treatment is used to generate carriers.

[0011] In some embodiments, the process parameters of the fourth laser treatment are the same as those of the second laser treatment.

[0012] In some embodiments, the laser of the process of the first laser treatment is infrared light, and the laser power is 0.5W - 50W; the laser of the second laser treatment is infrared light or visible light, and the laser power is 0.5W - 50W.

[0013] In some embodiments, the paste of the first gate line includes: silver powder, glass powder, organic carrier, and inorganic auxiliary agent with a mass ratio of (83 - 92):(2 - 7):(4 - 9):(0.1 - 1.5).

[0014] In some embodiments, the distance between the edge of the first laser region and the edge of the first gate line is 6μm - 9μm.

[0015] In some embodiments, the temperature range of the first laser treatment is 50°C - 150°C.

[0016] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0017] In the method for manufacturing a solar cell provided by an embodiment of the present application, a double-sided laser treatment method is adopted. By performing a first laser treatment on the area around the first grid line on the first passivation layer, a local thermal effect is generated around the first grid line, and by performing a second laser treatment on the entire surface of the second passivation layer to promote the generation of a large number of carriers in the cell, the first grid line burns through the first passivation layer under the combined action of heat and carriers and forms an ohmic contact with the substrate. Thus, compared with the thermal sintering process, the method for manufacturing a solar cell provided by an embodiment of the present application avoids the problem of high-temperature damage caused by heating the entire cell; compared with the laser-assisted sintering process, the method for manufacturing a solar cell provided by an embodiment of the present application does not require using a pressure pin to pass a reverse current through the grid line, avoiding damage to the cell caused by the pressure pin. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are illustrated by way of example in the accompanying drawings, which do not constitute a limitation on the embodiments unless otherwise stated. The figures in the drawings do not constitute a scale limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following-described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a flowchart corresponding to the method for manufacturing a solar cell provided by an embodiment of the present application;

[0020] Figure 2 It is a first structural schematic diagram corresponding to the step of providing a cell provided by an embodiment of the present application;

[0021] Figure 3 It is a second structural schematic diagram corresponding to the step of providing a cell provided by an embodiment of the present application;

[0022] Figure 4 It is a first structural schematic diagram corresponding to the step of placing a cell on glass provided by an embodiment of the present application;

[0023] Figure 5 It is a second structural schematic diagram corresponding to the step of placing a cell on glass provided by an embodiment of the present application;

[0024] Figure 6 It is a first structural schematic diagram corresponding to the step of performing double-sided light treatment on a cell provided by an embodiment of the present application;

[0025] Figure 7It is the second structural schematic diagram corresponding to the steps of performing double-sided light treatment on the battery slice provided by the embodiment of the present application;

[0026] Figure 8 It is the third structural schematic diagram corresponding to the steps of performing double-sided light treatment on the battery slice provided by the embodiment of the present application;

[0027] Figure 9 It is the fourth structural schematic diagram corresponding to the steps of performing double-sided light treatment on the battery slice provided by the embodiment of the present application;

[0028] Figure 10 is Figure 6 the corresponding top view. Detailed implementation manners

[0029] Currently, the sintering process of conventional electrodes is likely to cause damage to the battery slice, thereby reducing the efficiency and yield of the solar cell.

[0030] Thermal sintering uses a traditional air-flow thermal cycle sintering furnace to sinter the paste on the solar cell. During the thermal sintering process, the whole solar cell slice needs to be heated, which will cause the passivation layer over a large area to be damaged, magnify the defects inside the substrate, and is also likely to activate the impurities in the substrate, resulting in a reduction in the efficiency of the solar cell.

[0031] The laser-assisted sintering technology excites the carriers in the solar cell by laser, and under the action of the reverse voltage of the external electric field, they flow directionally and form a loop. When the loop current flows through the metal-semiconductor interface, due to the relatively large contact resistance between the metal and the semiconductor, an obvious thermal effect is generated, and the heat can further promote the mutual diffusion between the metal and the semiconductor to obtain excellent contact characteristics after sintering. However, the pressure needle for introducing the reverse current is likely to cause abrasion on the surface of the solar cell slice, and the laser-assisted sintering can only perform single-sided grid sintering. The process of flipping the solar cell slice is prone to failures, resulting in an increased risk of fragmentation, thereby reducing the yield of the solar cell.

[0032] The embodiment of the present application provides a preparation method for a solar cell, which is at least beneficial to improving the efficiency and yield of the solar cell.

[0033] In the description of the embodiment of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features.

[0034] In the description of the embodiment of the present application, "a plurality of" means more than two, unless otherwise clearly and specifically defined.

[0035] References to "embodiments" in this specification mean that the particular features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] In the description of the embodiments of the present application, technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the embodiments of the present application.

[0037] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0038] In the drawings corresponding to the embodiments of the present application, for better understanding and convenience of description, the thickness and area of the layers are enlarged. When describing that a component is on another component or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing that a component is on the surface of another component or a component surface forms or is provided with another component, it means that there is no third component between the two components. In addition, when describing that a component is "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0039] In the description of the embodiments of the present application, when a component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included.

[0040] The terms used in the description of various embodiments in this document are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0041] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0042] Figure 1 It is a flowchart corresponding to the preparation method of the solar cell provided by the embodiment of the present application; Figures 2 to 9 It is a schematic structural diagram corresponding to each step of the preparation method of the solar cell provided by the embodiment of the present application.

[0043] Refer to Figure 1 , the preparation method of the solar cell provided by the embodiment of the present application includes:

[0044] S11: Refer to Figure 2 and Figure 3 , provide a battery chip 100, the battery chip 100 includes a substrate 101 and a first passivation layer 111 and a second passivation layer 112 located on both side surfaces of the substrate 101, and a first grid line 121 is provided on the first passivation layer 111.

[0045] In some embodiments, the battery chip 100 is one of a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, or a multi-component compound solar cell, and the multi-component compound solar cell is specifically one of a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell, or a perovskite solar cell.

[0046] In some embodiments, the solar cell 100 is any one of a PERC cell (Passivated Emitter and Rear Cell), a PERT cell (Passivated Emitter and Rear Totally-diffused cell), a TOPCon cell (Tunnel Oxide Passivated Contact), a HIT / HJT cell (Heterojunction Technology), or a BC cell (Back Contact). Among them, the BC cell includes an IBC cell (Interdigitated Back Contact), an HPBC cell (Hybrid Passivated Back Contact), a TBC cell with the TOPCon technology and the IBC technology stacked, or an HBC cell with the HIT / HJT technology and the IBC technology stacked.

[0047] Reference Figure 2 , a second grid line 122 is further provided on the second passivation layer 112. The first grid line 121 is one of the positive electrode or the negative electrode, and the second grid line 122 is the other of the positive electrode or the negative electrode. In this way, the positive grid line and the negative grid line on the solar cell 100 are respectively located on the two side surfaces of the solar cell 100.

[0048] Reference Figure 3 , a second grid line 122 is further provided on the first passivation layer 111. The first grid line 121 is one of the positive electrode or the negative electrode, and the second grid line 122 is the other of the positive electrode or the negative electrode. In this way, both the positive grid line and the negative grid line on the solar cell 100 are located on the same side surface of the solar cell 100.

[0049] The substrate 101 is used to receive incident light and generate photo-generated carriers. The first grid line 121 and the second grid line 122 are used to collect photo-generated carriers. The first passivation layer 111 and the second passivation layer 112 can prevent oxidation or corrosion on the surface of the substrate 101 to improve the stability and lifespan of the solar cell.

[0050] In some embodiments, the material of the first passivation layer 111 includes at least one of aluminum oxide, silicon oxide, silicon nitride, or silicon oxynitride. In one example, the first passivation layer 111 is a single-layer structure; in another example, the first passivation layer 111 is a stacked structure. For example, the single-layer structure includes a single-layer aluminum oxide film layer, a single-layer silicon oxide film layer, a single-layer silicon nitride film layer, or a single-layer silicon oxynitride film layer; the stacked structure is composed of at least two film layers among the aluminum oxide film layer, the silicon oxide film layer, the silicon nitride film layer, or the silicon oxynitride film layer stacked together.

[0051] In some embodiments, the material of the second passivation layer 112 includes at least one of aluminum oxide, silicon oxide, silicon nitride, or silicon oxynitride. In one example, the second passivation layer 112 is a single-layer structure; in another example, the second passivation layer 112 is a stacked structure. For example, the single-layer structure includes a single-layer aluminum oxide film layer, a single-layer silicon oxide film layer, a single-layer silicon nitride film layer, or a single-layer silicon oxynitride film layer; the stacked structure is composed of at least two film layers among the aluminum oxide film layer, the silicon oxide film layer, the silicon nitride film layer, or the silicon oxynitride film layer stacked together.

[0052] S12: Refer to Figure 4 or Figure 5 , place the cell 100 on the glass 200, with the second passivation layer 120 facing the glass 200 and the first passivation layer 110 facing away from the glass 200.

[0053] Figure 4 In the cell 100 shown in

[0054] Figure 5 , take the example where the first grid line 121 and the second grid line 122 are respectively located on both side surfaces of the cell 100.

[0055] S13: Refer to Figure 6 , Figure 7 , Figure 8 or Figure 9 , perform double-sided light treatment on the cell 100. The double-sided light treatment includes: performing a first laser treatment on the first passivation layer 111 and performing a second laser treatment on the second passivation layer 112 through the glass 200. The first laser treatment and the second laser treatment cause the first grid line 121 to burn through the first passivation layer 111 to form an ohmic contact with the substrate 101. The area of the first laser treatment is the first laser zone I, and the first laser zone I is located around the first grid line 121; the area of the second laser treatment is the second laser zone II, and the second laser zone II covers the second passivation layer 112. The first laser treatment is used to generate heat, and the second laser treatment is used to generate carriers. The laser power of the first laser treatment is higher than the laser power of the second laser treatment.

[0056] In the method for preparing a solar cell provided by an embodiment of the present application, a double-sided laser treatment method is adopted. By performing a first laser treatment on the area around the first grid line 121 on the first passivation layer 111, a local thermal effect is generated around the first grid line 121. And by performing a second laser treatment on the entire surface of the second passivation layer 112 to promote the generation of a large number of carriers in the cell 100, the first grid line 121 burns through the first passivation layer 111 under the combined action of heat and carriers and forms an ohmic contact with the substrate 101. Thus, compared with the thermal sintering process, the method for preparing a solar cell provided by the embodiment of the present application avoids the problem of high-temperature damage caused by heating the entire cell 100. Compared with the laser-assisted sintering process, the method for preparing a solar cell provided by the embodiment of the present application does not need to use a pressure pin to pass a reverse current to the grid line, avoiding damage to the cell 100 caused by the pressure pin.

[0057] The laser for the first laser treatment is infrared light, and the power of the laser is 0.5W to 50W. For example, 0.5W to 2W, 2W to 5W, 5W to 20W, 20W to 30W, 30W to 40W, or 50W to 50W. Specifically, such as 0.5W, 1W, 1.8W, 2.2W, 5.4W, 8.6W, 10.4W, 14.6W, 17.8W, 21W, 25.5W, 29.4W, 33.3W, 38.8W, 45.4W, or 50W.

[0058] The laser for the second laser treatment is infrared light or visible light, and the power of the laser is 0.5W to 50W. For example, 0.5W to 2W, 2W to 5W, 5W to 20W, 20W to 30W, 30W to 40W, or 50W to 50W. Specifically, such as 0.5W, 1W, 1.8W, 2.2W, 5.4W, 8.6W, 10.4W, 14.6W, 17.8W, 21W, 25.5W, 29.4W, 33.3W, 38.8W, 45.4W, or 50W.

[0059] Reference Figure 6 When there is also a second grid line 122 on the second passivation layer 112, in one example, before the double-sided light treatment of the cell 100, the second grid line 122 has already formed an ohmic contact with the substrate 101. Thus, the subsequent double-sided light treatment of the cell 100 only includes the first laser treatment and the second laser treatment, and the first laser treatment and the second laser treatment are used to make the first grid line 121 burn through the first passivation layer 111 and form an ohmic contact with the substrate 101.

[0060] Reference Figure 7, when there is also a second gate line 122 on the second passivation layer 112, in another example, before the double-sided light treatment of the cell 100, the second gate line 122 has not formed an ohmic contact with the substrate 101. Thus, the subsequent double-sided light treatment of the cell 100 further includes: performing a third laser treatment on the first passivation layer 111, and the third laser treatment and the second laser treatment cause the second gate line 122 to burn through the second passivation layer 112 to form an ohmic contact with the substrate 101. The area of the third laser treatment is the third laser area III, and the orthographic projection of the third laser area III on the surface of the first passivation layer 111 is located around the orthographic projection of the second gate line 122 on the first passivation layer 111.

[0061] That is to say, the third laser area III corresponds to the position of the second gate line 122 on the second passivation layer 112. The third laser treatment causes a local thermal effect in the third laser area III, which is further transmitted to the second passivation layer 112 through the substrate 101. The combined action of heat and carriers causes the second gate line 122 to burn through the second passivation layer 112 and then form an ohmic contact with the substrate 101. Thus, when the gate lines are located on both sides of the cell 100, the double-sided gate line sintering can be achieved without flipping the cell 100, reducing the risk of fragmentation caused by the flipping process of the cell 100.

[0062] In some embodiments, the temperature generated by the laser of the third laser treatment is higher than the temperature generated by the laser of the first laser treatment. The relatively high temperature generated by the laser of the third laser treatment is beneficial to the effective transmission of the thermal effect generated by the third laser treatment to the second passivation layer 112 through the substrate 101.

[0063] Reference Figure 7 , in some embodiments, the first laser treatment and the third laser treatment are performed simultaneously. Thus, the first gate line 121 and the second gate line 122 can be sintered simultaneously to improve the efficiency of gate line sintering. Since during the arrangement of the first gate line 121 and the second gate line 122 on both sides of the cell 100, there may be an overlap in the projections of some of the first laser areas I and the third laser areas III on the surface of the cell 100. At this time, the cell 100 is divided into two parts, and the first part is subjected to the first laser treatment and the second laser treatment while the second part is subjected to the third laser treatment and the second laser treatment; then the first part is subjected to the third laser treatment and the second laser treatment while the second part is subjected to the first laser treatment and the second laser treatment. Thus, the sintering of the first gate line 121 and the second gate line 122 is achieved simultaneously to improve the manufacturing efficiency of the solar cell.

[0064] In some other embodiments, the first laser treatment and the third laser treatment are performed successively. In this way, the first gate line 121 and the second gate line 122 are sintered successively. For example, the first laser treatment and the second laser treatment are first performed to burn through the first passivation layer 111 by the first gate line 121 to form an ohmic contact with the substrate 101. Then, the third laser treatment and the second laser treatment are performed to burn through the second passivation layer 112 by the second gate line 122 to form an ohmic contact with the substrate 101. Alternatively, the third laser treatment and the second laser treatment are first performed to burn through the second passivation layer 112 by the second gate line 122 to form an ohmic contact with the substrate 101. Then, the first laser treatment and the second laser treatment are performed to burn through the first passivation layer 111 by the first gate line 121 to form an ohmic contact with the substrate 101.

[0065] Reference Figure 8 , when the second gate line 122 is also present on the first passivation layer 111, in one example, before the double-sided light treatment of the cell 100, the second gate line 122 has already formed an ohmic contact with the substrate 101. In this way, the subsequent double-sided light treatment of the cell 100 only includes the first laser treatment and the second laser treatment, and the first laser treatment and the second laser treatment are used to burn through the first passivation layer 111 by the first gate line 121 to form an ohmic contact with the substrate 101.

[0066] Reference Figure 9 , when the second gate line 122 is also present on the first passivation layer 111, in another example, before the double-sided light treatment of the cell 100, the second gate line 122 has not yet formed an ohmic contact with the substrate 101. In this way, during the subsequent double-sided light treatment of the cell 100, the first laser region I where the first laser treatment is performed is still around the second gate line 122, and the first laser treatment and the second laser treatment also burn through the first passivation layer 111 by the second gate line 122 to form an ohmic contact with the substrate 101.

[0067] That is to say, the first laser treatment simultaneously generates a thermal effect near both the first gate line 121 and the second gate line 122. Combining with the second laser treatment, a large number of carriers generated in the cell 100 are promoted, so that the first gate line 121 and the second gate line 122 can simultaneously burn through the first passivation layer 111 and the substrate 101 to generate an ohmic contact during the double-sided light treatment through the first laser treatment and the second laser treatment.

[0068] In some embodiments, the double-sided light treatment further includes: performing a fourth laser treatment on the first passivation layer, the area of the fourth laser treatment being the fourth laser area, the fourth laser area covering at least the area on the first passivation layer other than the first laser area, the laser power of the fourth laser treatment being less than the laser power of the first laser treatment, and the fourth laser treatment being used to generate carriers. The fourth laser treatment irradiates the first passivation layer, thereby enabling both sides of the cell to be photo-excited to generate carriers, increasing the number and concentration of carriers in the cell, and promoting the efficiency of forming an ohmic contact between at least the first grid line and the substrate.

[0069] When there is also a second grid line on the second passivation layer and an ohmic contact has been formed between the second grid line and the substrate before the double-sided light treatment of the cell, in one example, the fourth laser area only covers the area on the first passivation layer other than the first laser area, or, in another example, the fourth laser area covers the entire area of the first passivation layer.

[0070] When there is also a second grid line on the second passivation layer and an ohmic contact has not been formed between the second grid line and the substrate before the double-sided light treatment of the cell, in one example, the fourth laser area covers the area on the first passivation layer other than the first laser area and the third laser area, or, in another example, the fourth laser area covers the entire area of the first passivation layer.

[0071] When there is also a second grid line on the first passivation layer, regardless of whether an ohmic contact has been formed between the second grid line and the substrate before the double-sided light treatment of the cell, in one example, the fourth laser area only covers the area on the first passivation layer other than the first laser area, or, in another example, the fourth laser area covers the entire area of the first passivation layer.

[0072] In some embodiments, the process parameters of the fourth laser treatment are the same as those of the second laser treatment. Both the second laser treatment and the fourth laser treatment are used to generate carriers, and the process parameters of the fourth laser treatment being the same as those of the second laser treatment is conducive to uniformly generating a large number of carriers in the cell.

[0073] In some embodiments, the paste of the first grid line 121 includes: silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of (83~92):(2~7):(4~9):(0.1~1.5). For example, silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of 85:5:7:1; or silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of 88:6:6:1.1.

[0074] During the double-sided light treatment, when the second gate line 122 burns through the first passivation layer 111 or forms an ohmic contact with the substrate 101 through the second passivation layer 112, the paste of the second gate line 122 includes silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of (83-92):(2-7):(4-9):(0.1-1.5). For example, silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of 85:5:7:1; or silver powder, glass powder, organic carrier, and inorganic additive with a mass ratio of 88:6:6:1.1.

[0075] The organic carrier usually contains a solvent, a thickening agent, or a plasticizer, etc. The solvent is selected from at least one of terpineol, butyl carbitol, or butyl carbitol acetate; the thickening agent is selected from at least one of ethyl cellulose, nitrocellulose, or poly-α-methylstyrene; the plasticizer is selected from at least one of furoic acid, terephthalic acid, or ammonium sulfate. For example, the specific formulation of the organic carrier is terpineol and ethyl cellulose with a mass ratio of 95:5; or tributyl citrate and nitrocellulose with a mass ratio of 97.5:2.5; or butyl carbitol acetate, ethyl cellulose, furoic acid, and ethanol with a mass ratio of 69.2:14.4:6.4:10; or terpineol, ethyl cellulose, and lecithin with a mass ratio of 94.5:5:0.5.

[0076] The inorganic additive is selected from silicon dioxide.

[0077] Figure 10 For Figure 6 the top view corresponding to the shown solar cell.

[0078] Refer to Figure 10 , the first laser area I is located around the first gate line 121, which means that in the direction perpendicular to the surface of the first passivation layer 111, the orthographic projection of the first laser area I is located around the first gate line 121. The distance L between the edge of the first laser area I and the edge of the first gate line 121 is 6μm - 9μm, for example, specifically 6μm, 6.6μm, 7μm, 7.4μm, 8μm, 8.5μm, or 9μm. The size of the first laser area I within a suitable range is beneficial for the thermal effect generated by the first laser treatment to better act on the first gate line 121, promoting the sintering of the first gate line 121.

[0079] It should be noted that in Figure 10 , taking the distance between the two ends of the first gate line 121 and the edge of the solar cell 100 being greater than 9μm as an example, it does not constitute a limitation on the positional relationship between the first gate line 121 and the solar cell 100. In other embodiments, the distance between the two ends of the first gate line and the solar cell is less than 6μm, so that the two edges of the first laser area in the extending direction of the first gate line coincide with or exceed the edge of the solar cell.

[0080] Similarly, during the double-sided light treatment, when the second gate line 122 burns through the first passivation layer 111 or forms an ohmic contact with the substrate 101 through the second passivation layer 112, the two edges of the second laser zone in the extending direction of the second gate line coincide with or extend beyond the edge of the cell.

[0081] When there is also a second gate line on the first passivation layer and the second gate line has not formed an ohmic contact with the substrate before the double-sided light treatment of the cell, during the double-sided light treatment of the cell, the first laser zone is still located around the second gate line so that the first gate line and the second gate line are sintered simultaneously. The distance between the edge of the first laser zone and the edge of the second gate line is 6 μm to 9 μm, for example, specifically 6 μm, 6.6 μm, 7 μm, 7.4 μm, 8 μm, 8.5 μm or 9 μm.

[0082] When there is also a second gate line on the first passivation layer and the second gate line has not formed an ohmic contact with the substrate before the double-sided light treatment of the cell, during the double-sided light treatment of the cell, the first laser treatment and the second laser treatment also cause the second gate line to burn through the first passivation layer and contact the substrate. When the distance between both ends of the second gate line and the cell is less than 6 μm, the two edges of the first laser zone in the extending direction of the second gate line coincide with or extend beyond the edge of the cell.

[0083] When the third laser treatment and the second laser treatment are used to burn through the second passivation layer 112 of the second gate line 122 located on the second passivation layer 112 to form an ohmic contact with the substrate 101, the distance between the edge of the positive projection of the third laser zone III on the surface of the first passivation layer 111 and the edge of the positive projection of the second gate line 122 on the first passivation layer 111 is 6 μm to 9 μm, for example, specifically 6 μm, 6.6 μm, 7 μm, 7.4 μm, 8 μm, 8.5 μm or 9 μm. In this way, the thermal effect generated by the third laser treatment can better act on the second gate line 122 to promote the sintering of the second gate line 122.

[0084] Similarly, when the third laser treatment and the second laser treatment are used to burn through the second passivation layer 112 of the second gate line 122 located on the second passivation layer 112 to form an ohmic contact with the substrate 101, if the distance between both ends of the second gate line 122 and the cell 100 is less than 6 μm, the two edges of the third laser zone in the extending direction of the second gate line coincide with or extend beyond the edge of the cell.

[0085] In some embodiments, the temperature range of the first laser treatment is 50°C to 150°C. For example, specifically, it is 50°C, 58°C, 60°C, 66°C, 70°C, 74°C, 80°C, 84°C, 90°C, 95°C, 100°C, 111°C, 126°C, 134°C, 144°C or 150°C. The temperature of the first laser treatment needs to be within an appropriate range to avoid damaging the solar cell 100.

[0086] When using the third laser treatment to burn through the second passivation layer 112 on the second gate line 122 to form an ohmic contact with the substrate 101, the temperature range of the third laser treatment is 50°C to 150°C. For example, specifically, it is 50°C, 58°C, 60°C, 66°C, 70°C, 74°C, 80°C, 84°C, 90°C, 95°C, 100°C, 111°C, 126°C, 134°C, 144°C or 150°C. The temperature of the third laser treatment needs to be within an appropriate range to avoid damaging the solar cell 100.

[0087] In some embodiments, the light transmittance of the glass is 88% to 92%. For example, specifically, it is 88%, 89%, 90%, 91% or 92%. The transmittance of the glass is relatively high to improve the efficiency of the second laser treatment in promoting the generation of carriers in the solar cell, which is beneficial to the sintering of at least the first gate line 121.

[0088] It should be noted that "burn through" includes that the gate line penetrates the passivation layer and the substrate in a dot shape for electrical contact or penetrates the passivation layer and the substrate in a large area. The embodiments of the present application do not limit the microscopic morphology generated after the gate line burns through the passivation layer. As long as the gate line forms an ohmic contact with the substrate after burning through the passivation layer.

[0089] In the method for preparing a solar cell provided by the embodiments of the present application, a double-sided laser treatment method is adopted. By performing the first laser treatment on the area around the first gate line 121 on the first passivation layer 111, a local thermal effect is generated around the first gate line 121. And by performing the second laser treatment on the entire surface of the second passivation layer 112 to promote the generation of a large number of carriers in the solar cell 100. Through the combined action of heat and carriers, the first gate line 121 burns through the first passivation layer 111 and forms an ohmic contact with the substrate 101. In this way, compared with the thermal sintering process, the method for preparing a solar cell provided by the embodiments of the present application avoids the problem of high-temperature damage caused by heating the entire solar cell 100. Compared with the laser-assisted sintering process, the method for preparing a solar cell provided by the embodiments of the present application does not need to use a pressure pin to pass a reverse current through the gate line, avoiding the damage to the solar cell 100 caused by the pressure pin.

[0090] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present application. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: A cell is provided, the cell comprising a substrate and a first passivation layer and a second passivation layer located on both side surfaces of the substrate, wherein the first passivation layer has a first gate line; Placing the cell on glass, with the second passivation layer facing the glass and the first passivation layer facing away from the glass; The cell is subjected to double-sided light treatment, the double-sided light treatment comprising: performing a first laser treatment on the first passivation layer and performing a second laser treatment on the second passivation layer through the glass, the first laser treatment and the second laser treatment causing the first grid line to burn through the first passivation layer to form an ohmic contact with the substrate, the area subjected to the first laser treatment being a first laser area, the first laser area being located around the first grid line; the area subjected to the second laser treatment being a second laser area, the second laser area covering the second passivation layer, the first laser treatment being used to generate heat, the second laser treatment being used to generate carriers, and the laser power of the first laser treatment being higher than the laser power of the second laser treatment; The double-sided light treatment also includes: performing a fourth laser treatment on the first passivation layer, the area of ​​the fourth laser treatment is a fourth laser zone, the fourth laser zone at least covers the area on the first passivation layer except the first laser zone, the laser power of the fourth laser treatment is less than the laser power of the first laser treatment, and the fourth laser treatment is used to generate carriers.

2. The method for preparing a solar cell according to claim 1, characterized in that: The second passivation layer has a second gate line, and the double-sided light treatment of the cell also includes: performing a third laser treatment on the first passivation layer, the third laser treatment and the second laser treatment cause the second gate line to burn through the second passivation layer to form an ohmic contact with the substrate, the area treated by the third laser is a third laser zone, the orthographic projection of the third laser zone on the surface of the first passivation layer is located around the orthographic projection of the second gate line on the first passivation layer, and the third laser treatment is used to generate heat.

3. The method for preparing a solar cell according to claim 2, characterized in that: The temperature generated by the laser light of the third laser process is higher than the temperature generated by the laser light of the first laser process.

4. The method for preparing a solar cell according to claim 1, characterized in that: The first passivation layer also has a second gate line, and the first laser area is also located around the second gate line. During the double-sided light treatment of the battery cell, the first laser treatment and the second laser treatment also cause the second gate line to burn through the first passivation layer to form an ohmic contact with the substrate.

5. The method for preparing a solar cell according to claim 1, characterized in that: The process parameters of the fourth laser treatment are the same as the process parameters of the second laser treatment.

6. The method for preparing a solar cell according to claim 1, characterized in that: The laser used in the first laser treatment process is infrared light, and the power of the laser is 0.5W~50W; the laser used in the second laser treatment process is infrared light or visible light, and the power of the laser is 0.5W~50W.

7. The method for preparing a solar cell according to claim 1, characterized in that: The slurry of the first gate line includes: silver powder, glass powder, organic carrier and inorganic additive in a mass ratio of (83-92): (2-7): (4-9): (0.1-1.5).

8. The method for preparing a solar cell according to claim 1, characterized in that: The distance between the edge of the first laser region and the edge of the first gate line is 6 μm-9 μm.

9. The method for preparing a solar cell according to claim 1, characterized in that: The temperature range of the first laser treatment is 50°C to 150°C.

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