Solar cell and preparation method thereof

Abstract

The embodiment of the invention provides a solar cell and a preparation method thereof, and the method comprises the steps: providing a cell piece which is provided with a first surface and a second surface which are opposite, the first surface is provided with a plurality of first grid lines, and the second surface is provided with a plurality of second grid lines; acquiring an overlapping index of each first grid line on the battery piece; classifying the first grid lines according to the overlapping index of each first grid line so as to at least divide the first grid lines into a first type of grid lines and a second type of grid lines; and the laser-assisted sintering process is carried out, the process parameters adopted by the first type of grid lines are within a first parameter range, the process parameters adopted by the second type of grid lines are within a second parameter range, and the maximum value of at least one parameter range in the first parameter range is smaller than or equal to the minimum value of the corresponding parameter range in the second parameter range. According to the solar cell and the preparation method thereof provided by the embodiment of the invention, the yield and the efficiency of the solar cell are at least improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of solar cells, and in particular to a solar cell and a method for preparing the same. Background Art

[0002] The laser-enhanced contact optimization (LECO) process uses high-intensity laser irradiation to stimulate charge carriers on the cell, while applying a reverse voltage of 10V or more to the grid line on the cell, thereby generating a local current of several amperes, and sintering occurs at the corresponding location to induce mutual diffusion of silver paste and substrate, which is beneficial to reduce the contact resistance between metal and semiconductor. The laser-assisted sintering process allows a larger sintering temperature window, achieves correct contact on ultra-low doped emitters, and allows higher open circuit voltage.

[0003] However, during the laser-assisted sintering process, under-firing or under-firing problems are prone to occur, which in turn leads to reduced yield and efficiency of solar cells. Summary of the invention

[0004] The embodiments of the present application provide a solar cell and a method for preparing the same, which are at least beneficial to improving the yield and efficiency of the solar cell.

[0005] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a method for preparing a solar cell, including: providing a cell sheet, the cell sheet having a first surface and a second surface relative to each other, a plurality of first grid lines on the first surface, a plurality of second grid lines on the second surface, and the first grid lines and the second grid lines having the same extension direction; obtaining an overlap index of each first grid line on the cell sheet, the overlap index being represented by the degree of overlap between the orthographic projection of the first grid line on the first surface and the orthographic projection of the second grid line on the first surface; classifying the first grid lines according to the overlap index of each first grid line to divide the first grid lines into at least a first type of grid lines and a second type of grid lines, the overlap index corresponding to the first grid lines in the first type of grid lines being within a first range, the overlap index corresponding to the first grid lines in the second type of grid lines being within a second range, and the minimum value of the first range being greater than or equal to the maximum value of the second range; performing a laser-assisted sintering process, the process parameters used for the first type of grid lines being within a first parameter range, the process parameters used for the second type of grid lines being within a second parameter range, and the maximum value of at least one parameter range in the first parameter range being less than or equal to the minimum value of the corresponding parameter range in the second parameter range.

[0006] In some embodiments, a laser-assisted sintering process is performed, including: each first-type grid line corresponds to a set of first parameters in a first parameter range, and each first-type grid line is individually subjected to a laser-assisted sintering process using its respective corresponding first parameters; each second-type grid line corresponds to a set of second parameters in a second parameter range, and each second-type grid line is individually subjected to a laser-assisted sintering process using its respective corresponding second parameters.

[0007] In some embodiments, the steps of performing the laser-assisted sintering process include at least two laser light sources, the laser power of one laser light source is adjusted according to the first parameter corresponding to each first type of grid line, and the laser power of the other laser light source is adjusted according to the second parameter corresponding to each second type of grid line.

[0008] In some embodiments, after classifying the first grid lines according to the overlapping index of each first grid line, the method includes: dividing the first surface into at least a first area and a second area, the area where the adjacent multiple first-type grid lines are located is the first area, and the area where the adjacent multiple second-type grid lines are located is the second area; in the step of performing a laser-assisted sintering process, each first area corresponds to a set of first parameters in the first parameter range, each second area corresponds to a set of second parameters in the second parameter range, each first area uses the corresponding first parameter pair for laser-assisted sintering, and each second area uses the corresponding second parameter for laser-assisted sintering.

[0009] In some embodiments, a first parameter corresponding to each first region is obtained according to an average value of overlapping indexes of multiple first-type gate lines in each first region; a second parameter corresponding to each second region is obtained according to an average value of overlapping indexes of multiple second-type gate lines in each second region.

[0010] In some embodiments, a first parameter corresponding to each first area is obtained according to the median of overlapping indexes of multiple first-type gate lines in each first area; a second parameter corresponding to each second area is obtained according to the median of overlapping indexes of multiple second-type gate lines in each second area.

[0011] In some embodiments, the step of performing the laser-assisted sintering process includes at least two laser light sources, the laser power of one laser light source corresponds to the first parameter, and the laser power of the other laser light source corresponds to the second parameter.

[0012] In some embodiments, the first range corresponds to multiple non-overlapping first sub-ranges, the first parameter range corresponds to multiple non-overlapping first sub-parameter ranges, and the first sub-ranges correspond one-to-one to the first sub-parameter ranges; the second range corresponds to multiple non-overlapping second sub-ranges, the second parameter corresponds to multiple non-overlapping second sub-parameter ranges, and the second sub-ranges correspond one-to-one to the second sub-parameter ranges.

[0013] In some embodiments, the overlap index is a ratio of an overlap width of an orthographic projection of a first grid line on the first surface to an orthographic projection of a second grid line on the first surface to a width of the first grid line.

[0014] According to some embodiments of the present application, the embodiments of the present application further provide a solar cell, which is formed by the solar cell preparation method in the above embodiment.

[0015] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0016] In the preparation method of the solar cell provided in the embodiment of the present application, before the laser-assisted sintering process, the first surface of the cell has a plurality of first grid lines, and the second surface of the cell has a plurality of second grid lines, and the first grid lines and the second grid lines are used to collect carriers on the first surface and the second surface, respectively. The laser-assisted sintering process is used to perform laser-assisted sintering on the first grid lines, and the first grid lines are not electrically connected to the structure in the cell before the laser-assisted sintering, and the second grid lines are electrically connected to the structure in the cell before the laser-assisted sintering process. Before the laser-assisted sintering process, the overlap index of each first grid line on the cell is first obtained, and the first grid lines are classified according to the overlap index of each first grid line, so as to divide the first grid lines into at least a first type of grid lines and a second type of grid lines, and the overlap degree of the first type of grid lines is greater than that of the second type of grid lines, so that in the subsequent laser-assisted sintering process, the problem of overburning is more likely to occur than that of the second type of grid lines. During the laser-assisted sintering process, laser-assisted sintering is performed on the first type of grid lines and the second type of grid lines respectively using the corresponding first parameter range and second parameter range, and the maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range. In this way, the first type of grid lines and the second type of grid lines can be laser-assisted sintered under relatively matched process conditions, avoiding the problem of over-burning of the first type of grid lines and the problem of under-burning of the second type of grid lines, thereby improving the yield and efficiency of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1A flowchart corresponding to the method for preparing a solar cell provided in an embodiment of the present application;

[0019] Figures 2 to 4 A schematic diagram of the structures corresponding to the various steps of the method for preparing a solar cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] As known from the background art, under-firing or over-firing problems are likely to occur during the laser-assisted sintering process, thereby reducing the yield and efficiency of solar cells.

[0021] In the related art, during the laser-assisted sintering process, after the grid lines are formed on the front and back of the cell, due to the different numbers and arrangement spacings of the front grid lines and the back grid lines, it is inevitable that the orthographic projection of some of the front grid lines on the front of the cell overlaps with the orthographic projection of the back grid lines on the front of the cell. In view of the different overlapping degrees of the front grid lines and the back grid lines, laser-assisted sintering usually uses the same laser power and reverse current to perform the laser-assisted sintering process on all the front grid lines. In this way, for the front grid lines with a smaller overlap with the back grid lines, the problem of under-burning is prone to occur, which leads to the inability of such front grid lines to form good electrical contact with the substrate; for the front grid lines with a larger overlap with the back grid lines, the phenomenon of silver burning through the passivation layer is prone to occur, which leads to the destruction of the structure of the cell and the generation of irreversible defects. In the electroluminescence detection or photoluminescence detection, the under-burned or over-burned front grid lines appear as dark stripes, affecting the efficiency and yield of the cell.

[0022] The present application provides a method for preparing a solar cell, which is at least beneficial to improving the yield and efficiency of the solar cell.

[0023] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, when a certain component “includes” another component, unless otherwise stated, other components are not excluded and other components may be further included.

[0026] The terms used in the description of the various described embodiments herein are used only to describe specific embodiments and are not intended to be limiting. As used in the description of the various described embodiments and the appended claims, "components" are also intended to include plural forms unless the context clearly indicates otherwise.

[0027] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0028] Figure 1 This is a flow chart corresponding to the method for preparing a solar cell provided in an embodiment of the present application. Figures 2 to 4 The schematic diagram of the structure corresponding to each step of the method for preparing a solar cell provided in the embodiment of the present application. Figure 2 A top view of a battery cell provided in an embodiment of the present application; Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along the AA1 direction; Figure 4 A structural schematic diagram corresponding to the step of dividing the first surface into regions provided in an embodiment of the present application.

[0029] refer to Figure 1 According to some embodiments of the present application, a method for preparing a solar cell provided in an embodiment of the present application includes:

[0030] Step 11: Reference Figure 2 and Figure 3 A battery cell 100 is provided, wherein the battery cell 100 has a first surface 101 and a second surface 102 opposite to each other, wherein the first surface 101 has a plurality of first grid lines 110, and the second surface 102 has a plurality of second grid lines 120, and the first grid lines 110 and the second grid lines 120 extend in the same direction.

[0031] The cell 100 may be 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) or a HIT / HJT cell (Heterojunction Technology).

[0032] The cell 100 may be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell or a multi-compound solar cell. The multi-compound solar cell may specifically be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell or a perovskite solar cell.

[0033] In some embodiments, the cell may include a first passivation layer, a cell body, and a second passivation layer stacked in sequence, the surface of the first passivation layer away from the cell body being the first surface, the surface of the second passivation layer away from the cell body being the second surface, the first grid line being located on the first passivation layer, and the second grid line being located on the second passivation layer and electrically connected to the cell body. The cell body is used to receive incident light and generate photogenerated carriers, the first grid line and the second grid line are used to collect photogenerated carriers, and the first passivation layer and the second passivation layer can prevent oxidation or corrosion of the surface of the cell body to improve the stability and life of the cell. It is understandable that before laser sintering is performed, the first grid line has not yet formed an electrical connection with the cell body.

[0034] In some embodiments, the second gate line may penetrate the passivation layer and be electrically connected to the battery cell body, or may be electrically connected to the battery cell body by point contact.

[0035] The material of the first passivation layer may include at least one of aluminum oxide, silicon oxide, silicon nitride or silicon oxynitride. The first passivation layer may be a single-layer structure or a stacked-layer structure. For example, the single-layer structure may be 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-layer structure may be composed of at least two film layers stacked among an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer or a silicon oxynitride film layer.

[0036] The material of the second passivation layer may include at least one of aluminum oxide, silicon oxide, silicon nitride or silicon oxynitride. The second passivation layer may be a single-layer structure or a stacked-layer structure. For example, the single-layer structure may be 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-layer structure may be composed of at least two film layers of an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer or a silicon oxynitride film layer stacked together.

[0037] In some embodiments, the battery cell body may include a substrate and an emitter that are stacked, wherein the emitter may be located on a side of the substrate close to the first passivation layer and in contact with the first passivation layer, or the emitter may be located on a side of the substrate close to the second passivation layer and in contact with the second passivation layer. The doping element type of the emitter is opposite to the doping element type in the substrate. For example, if the doping element in the substrate is a P-type doping element, the doping element in the emitter is an N-type doping element; if the doping element in the substrate is an N-type doping element, the doping element in the emitter is a P-type doping element, thus forming a PN junction with the substrate. The PN junction can receive incident light irradiated to the surface of the substrate and generate electron-hole pairs. For example, when the substrate is an N-type substrate, the separated electrons move into the substrate and the separated holes move into the emitter, thus forming a current.

[0038] In some embodiments, the substrate may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type doping element, which may be any one of the V-group elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type element, which may be any one of the III-group elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0039] In some embodiments, the material of the substrate may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0040] In some embodiments, at least one side surface of the substrate may have a velvet structure, such as a pyramid-structured velvet. In this way, the velvet structure can enhance the substrate's absorption utilization rate of incident light, thereby facilitating the improvement of the light conversion efficiency of the cell. If the solar cell is a single-sided cell, the velvet surface can be formed only on one side of the substrate, and the other side surface of the substrate can be a polished surface, that is, the polished surface of the substrate is flatter than the velvet surface. It should be noted that for single-sided cells, velvet can also be formed on both sides of the substrate. If the solar cell is a double-sided cell, velvet can be formed on both sides of the substrate.

[0041] In some embodiments, the cell body may further include a tunneling layer located on the surface of the substrate and a doped conductive layer located on the surface of the tunneling layer, wherein the tunneling layer is located on the side surface of the substrate away from the emitter, and the doped conductive layer is located on the surface of the tunneling layer away from the substrate. The tunneling layer and the doped conductive layer are used to form a passivation contact structure, and the tunneling layer can play a chemical passivation effect. Due to the presence of interface state defects on the substrate surface, the tunneling layer can saturate the dangling bonds on the substrate surface, reduce the defect state density on the substrate surface, and reduce the recombination center on the substrate surface to reduce the carrier recombination rate, so that the interface state density on the substrate surface is relatively large. The increase in the interface state density will promote the recombination of photogenerated carriers, increase the fill factor, short-circuit current and open-circuit voltage of the solar cell, so as to improve the photoelectric conversion efficiency of the solar cell; the doped conductive layer can have a field passivation effect, and the doped conductive layer can form an electrostatic field, so that the minority carriers escape from the interface, reduce the concentration of the minority carriers, so that the carrier recombination rate at the substrate interface is relatively low, and the open-circuit voltage, short-circuit current and fill factor of the solar cell are increased, so as to improve the photoelectric conversion efficiency of the solar cell.

[0042] The material of the tunneling layer may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

[0043] The material of the doped conductive layer may include at least one of amorphous silicon, polycrystalline silicon or silicon carbide. The doped conductive layer has the same doping element as the substrate. If the doping element type of the substrate is P-type, the doping element type in the doped conductive layer is also P-type; if the doping element type of the substrate is N-type, the doping element type in the doped conductive layer is also N-type.

[0044] In some embodiments, the first surface 101 may be one of the front side and the back side of the battery cell 100 , and the second surface 102 may be the other of the front side and the back side of the battery cell 100 .

[0045] It should be noted that in Figure 2 and Figure 3 In the example, the number of the first gate lines 110 on the first surface 101 is greater than the number of the second gate lines 120 on the second surface 102, which does not constitute a limitation on the number of the first gate lines 110 and the number of the second gate lines 120. The number of the first gate lines 110 and the number of the second gate lines 120 can be adjusted according to actual conditions. Accordingly, the size and spacing of the first gate lines 110 and the size and spacing of the second gate lines 120 can be adjusted according to actual conditions.

[0046] Step 12: Obtaining the overlap index of each first grid line 110 on the cell 100 , where the overlap index is represented by the overlap degree between the orthographic projection of the first grid line 110 on the first surface 101 and the orthographic projection of the second grid line 120 on the first surface 101 .

[0047] For example, the overlap index may be the overlap width of the orthographic projection of the first gate line 110 on the first surface 101 and the orthographic projection of the second gate line 120 on the first surface 101; or, the overlap index may be the ratio of the overlap width of the orthographic projection of the first gate line 110 on the first surface 101 and the orthographic projection of the second gate line 120 on the first surface 101 to the width of the first gate line 110.

[0048] The overlapping width refers to the width of the overlapping area of ​​the orthographic projection of the first gate line 110 on the first surface 101 and the orthographic projection of the second gate line 120 on the first surface 101 along the extending direction perpendicular to the first gate line 110. It can be understood that when one first gate line 110 forms two overlapping areas with two second gate lines 120, the overlapping width refers to the sum of the widths of the overlapping areas of the orthographic projection of the first gate line 110 on the first surface 101 and the orthographic projection of the two second gate lines 120 on the first surface 101. The width of the first gate line 110 refers to the width of the first gate line 110 itself along the extending direction perpendicular to the first gate line 110.

[0049] The overlap index is described below as the ratio of the overlap width of the orthographic projection of the first grid line 110 on the first surface 101 and the orthographic projection of the second grid line 120 on the first surface 101 to the width of the first grid line 110, which does not constitute a limitation on the definition of the overlap index.

[0050] Step 13: Reference Figure 3 The first gate lines 110 are classified according to the overlapping index of each first gate line 110 to divide the first gate lines 110 into at least first-category gate lines 111 and second-category gate lines 112, the overlapping indexes corresponding to the first gate lines 110 in the first-category gate lines 111 are within a first range, the overlapping indexes corresponding to the first gate lines 110 in the second-category gate lines 112 are within a second range, and the minimum value of the first range is greater than or equal to the maximum value of the second range.

[0051] For example, when the ratio of the overlap width of the orthographic projection of the first grid line 110 on the first surface 101 and the orthographic projection of the second grid line 120 on the first surface 101 to the width of the first grid line 110 is less than or equal to 0.5, the first grid line 110 is classified as the second type of grid line 112; when the ratio of the overlap width of the orthographic projection of the first grid line 110 on the first surface 101 and the orthographic projection of the second grid line 120 on the first surface 101 to the width of the first grid line 110 is greater than 0.5, the first grid line 110 is classified as the first type of grid line 111. In this way, the first range is represented as a range greater than 0.5 and less than or equal to 1; the second range is represented as a range greater than or equal to 0 and less than or equal to 0.5.

[0052] In some embodiments, the first range may correspond to multiple non-overlapping first sub-ranges; the second parameter may correspond to multiple non-overlapping second sub-parameter ranges. For example, when the first range is represented as a range greater than 0.5 and less than or equal to 1, the first range may correspond to 3 first sub-ranges, the first first sub-range is represented as a range greater than 0.5 and less than 0.6; the second first sub-range is represented as a range greater than or equal to 0.6 and less than 0.8; the third first sub-range is represented as a range greater than or equal to 0.8 and less than or equal to 1. When the second range is represented as a range greater than or equal to 0 and less than or equal to 0.5, the second range may correspond to 2 second sub-ranges, the first second sub-range is represented as a range greater than or equal to 0 and less than 0.25; the second second sub-range is represented as a range greater than or equal to 0.25 and less than or equal to 0.5.

[0053] It can be understood that the number of the first sub-range and the number of the second sub-range may be the same or different.

[0054] refer to Figure 4 In some embodiments, after classifying the first gate lines 110 according to the overlap index of each first gate line 110, it may also include: dividing the first surface 101 into at least a first area A and a second area B, the area where the adjacent multiple first-type gate lines 111 are located is the first area A, and the area where the adjacent multiple second-type gate lines 112 are located is the second area B.

[0055] It can be understood that the number of the first-type gate lines 111 in the first region A is greater than or equal to 1; and the number of the second-type gate lines 112 in the second region B is greater than or equal to 1.

[0056] Step 14: Perform a laser-assisted sintering process, the process parameters used by the first type of gate lines 111 are within a first parameter range, the process parameters used by the second type of gate lines 112 are within a second parameter range, and the maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range.

[0057] In the method for preparing a solar cell provided in an embodiment of the present application, before the laser-assisted sintering process, a plurality of first grid lines 110 are provided on the first surface 101 of the cell 100, and a plurality of second grid lines 120 are provided on the second surface 102 of the cell 100, and the first grid lines 110 and the second grid lines 120 are respectively used to collect carriers on the first surface 101 and the second surface 102. The laser-assisted sintering process is used to perform laser-assisted sintering on the first grid lines 110, and the first grid lines 110 are not electrically connected to the structure in the cell 100 before the laser-assisted sintering, and the second grid lines 120 are electrically connected to the structure in the cell 100 before the laser-assisted sintering process. Before the laser-assisted sintering process, the overlapping index of each first grid line 110 on the battery cell 100 is first obtained, and the first grid lines 110 are classified according to the overlapping index of each first grid line 110, so as to divide the first grid lines 110 into at least first-type grid lines 111 and second-type grid lines 112. The overlapping degree of the first-type grid lines 111 is greater than that of the second-type grid lines 112. Therefore, in the subsequent laser-assisted sintering process, the problem of overburning is more likely to occur than that of the second-type grid lines 112. During the laser-assisted sintering process, laser-assisted sintering is performed on the first type of grid lines 111 and the second type of grid lines 112 respectively using their respective corresponding first parameter ranges and second parameter ranges, and the maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range. In this way, the first type of grid lines 111 and the second type of grid lines 112 can both be laser-assisted sintered under relatively matched process conditions, thereby avoiding the problem of over-burning of the first type of grid lines 111 and the problem of under-burning of the second type of grid lines 112, thereby improving the yield and efficiency of solar cells.

[0058] In some embodiments, a laser-assisted sintering process is performed in step 14, including: each first-class grid line 111 corresponds to a set of first parameters in the first parameter range, and each first-class grid line 111 uses the first parameters corresponding to each other to perform the laser-assisted sintering process separately; each second-class grid line 112 corresponds to a set of second parameters in the second parameter range, and each second-class grid line 112 uses the second parameters corresponding to each other to perform the laser-assisted sintering process separately. That is to say, for each first-class grid line 111, each first-class grid line 111 matches a different first parameter according to the respective degree of overlap; for each second-class grid line 122, each second-class grid line 112 matches a different second parameter according to the respective degree of overlap, so that in the process of laser-assisted sintering, each first grid line 110 is laser-assisted sintered separately one by one, and the process parameters are adjusted in real time with the first parameters or second parameters corresponding to each first grid line 110, so that each first grid line 110 can match a relatively moderate process parameter to make the sintering degree of the first grid line 110 moderate.

[0059] In one example, the laser power of the first parameter is less than the laser power of the second parameter, and the reverse current of the first parameter is the same as the reverse current of the second parameter. In another example, the laser power of the first parameter is the same as the laser power of the second parameter, and the reverse current of the first parameter is different from the reverse current of the second parameter.

[0060] In a specific example, when each first-class grid line 111 is subjected to a laser-assisted sintering process individually using the first parameter corresponding to each, and each second-class grid line 112 is subjected to a laser-assisted sintering process individually using the second parameter corresponding to each, the laser power of the first parameter is less than the laser power of the second parameter, and the reverse current of the first parameter is the same as the reverse current of the second parameter. In the process of performing the laser-assisted sintering process in step 14, at least two laser light sources may be included, the laser power of one laser light source is adjusted according to the first parameter corresponding to each first-class grid line 111, and the laser power of the other laser light source is adjusted according to the second parameter corresponding to each second-class grid line 112. In this way, the laser power of one laser light source is adaptively adjusted according to the first parameter corresponding to each first-class grid line 111 within the first parameter range, and the power of the other laser light source is adaptively adjusted according to the second parameter corresponding to each second-class grid line 112 within the second parameter range. On the one hand, the two laser light sources can synchronously perform laser-assisted sintering on the first type of grid lines 111 and the second type of grid lines 112 respectively, which can improve the efficiency of the laser-assisted sintering process; on the other hand, the power adjustment ranges of the two laser light sources are different, and the power of the laser light sources will not fluctuate, which is beneficial to improving the service life of the laser light sources.

[0061] In some embodiments, the number of laser light sources may be greater than 2, for example, the number of laser light sources may be 3, 4, 6 or 8, etc. In this way, at least two laser light sources may be adaptively adjusted according to first parameters corresponding to different first-type grid lines 111 within a first parameter range, and / or at least two laser light sources may be adaptively adjusted according to second parameters corresponding to different second-type grid lines 112 within a second parameter range. Different first-type grid lines 111 may be synchronously laser-assisted sintered through different laser light sources, and different second-type grid lines 112 may be synchronously laser-internal assisted sintered through different laser light sources, so as to further improve the efficiency of laser-assisted sintering.

[0062] In some embodiments, if in step 13, the first surface 101 is further divided into regions to divide the first surface 101 into at least a first region A and a second region B; in step 14, in the step of performing the laser-assisted sintering process, each first region A corresponds to a set of first parameters in the first parameter range, each second region B corresponds to a set of second parameters in the second parameter range, each first region A uses the first parameter pair corresponding to each other for laser-assisted sintering, and each second region B uses the second parameter pair corresponding to each other for laser-assisted sintering. That is, after the first grid lines 110 are classified, the first surface 101 is divided into regions according to the positions of the first-type grid lines 111 or the second-type grid lines 112, so that the first region A includes at least one first-type grid line 111, and the second region B includes at least one second-type grid line 112. During laser assisted sintering, the first type of grid lines 111 in the first area A are laser assisted sintered using the same first parameters, and the second type of grid lines 112 in the second area B are laser assisted sintered using the same second parameters. This can reduce the number of times the process parameters are adjusted, thereby improving the efficiency of laser assisted sintering.

[0063] In one example, the laser power of the first parameter is less than the laser power of the second parameter, and the reverse current of the first parameter is the same as the reverse current of the second parameter. In another example, the laser power of the first parameter is the same as the laser power of the second parameter, and the reverse current of the first parameter is different from the reverse current of the second parameter.

[0064] In a specific example, in step 13, the first surface 101 is divided into regions to divide the first surface 101 into at least a first region A and a second region B; in step 14, in the step of performing the laser-assisted sintering process, each first region A corresponds to a set of first parameters in the first parameter range, each second region B corresponds to a set of second parameters in the second parameter range, each first region A uses the first parameter pair corresponding to each other for laser-assisted sintering, and each second region B uses the second parameter corresponding to each other for laser-assisted sintering. Wherein, the laser power of the first parameter is different from the laser power of the second parameter, and the reverse current of the first parameter is the same as the reverse current of the second parameter. In step 14, during the laser-assisted sintering process, at least two laser light sources may be included, the laser power of one laser light source is adjusted according to the first parameter corresponding to each first region A, and the laser power of the other laser light source is adjusted according to the second parameter corresponding to each second region B. In this way, the laser power of one laser light source is adaptively adjusted according to the first parameter corresponding to each first region A within the first parameter range, and the power of the other laser light source is adaptively adjusted according to the second parameter corresponding to each second region B within the second parameter range. On the one hand, the two laser light sources can synchronously perform laser-assisted sintering on the first area A and the second area B respectively, and when performing laser-assisted sintering on the first type of grid lines 111 in the first area A, the area of ​​laser irradiation can be adjusted to perform laser-assisted sintering on multiple first type grid lines 111 at the same time; when performing laser-assisted sintering on the second grid lines in the second area B, the area of ​​laser irradiation can be adjusted to perform laser-assisted sintering on multiple second type grid lines 112 at the same time, thereby improving the efficiency of the laser-assisted sintering process; on the other hand, the power ranges of the two laser light sources are different, and the power of the laser light source will not fluctuate, which is beneficial to improving the service life of the laser light source.

[0065] In some embodiments, the number of laser light sources may be greater than 2, for example, the number of laser light sources may be 3, 4, 6 or 8. In this way, at least two laser light sources may be adaptively adjusted according to first parameters corresponding to different first zones A within the first parameter range, and / or at least two laser light sources may be adaptively adjusted according to second parameters corresponding to different second zones B within the second parameter range. Different first zones A may be laser-assisted sintered synchronously by different laser light sources, and different second zones B may be laser-internal assisted sintered synchronously by different laser light sources, so as to further improve the efficiency of laser-assisted sintering.

[0066] In some embodiments, the first parameter corresponding to each first area A may be obtained according to the average value of the overlapping indexes of the plurality of first-type grid lines 111 in each first area A; the second parameter corresponding to each second area B may be obtained according to the average value of the overlapping indexes of the plurality of second-type grid lines 112 in each second area B. In other embodiments, the first parameter corresponding to each first area A may be obtained according to the median of the overlapping indexes of the plurality of first-type grid lines 111 in each first area A; the second parameter corresponding to each second area B may be obtained according to the median of the overlapping indexes of the plurality of second-type grid lines 112 in each second area B.

[0067] In some embodiments, if in step 13, the first range corresponds to multiple non-overlapping first sub-ranges; the second parameter corresponds to multiple non-overlapping second sub-parameter ranges; in step 14, the first parameter range may correspond to multiple non-overlapping first sub-parameter ranges, and the second range may correspond to multiple non-overlapping second sub-ranges, the first sub-ranges correspond one-to-one with the first sub-parameter ranges, and the second sub-ranges correspond one-to-one with the second sub-parameter ranges.

[0068] In a specific example, the overlap index is taken as the overlap width of the orthographic projection of the first gate line 110 on the first surface 101 and the orthographic projection of the second gate line 120 on the first surface 101. The first range is an overlap width greater than or equal to 0.1 μm; the second range is a range greater than or equal to 0 and less than 0.1 μm, wherein the first range may include two first sub-ranges, the first first sub-range may be a range greater than or equal to 0.1 μm and less than or equal to 0.2 μm, and the second first sub-range may be a range greater than 0.2 μm; the second range may include two second sub-ranges, the first second sub-range may be a range greater than or equal to 0 and less than or equal to 0.05 μm, and the second second sub-range may be a range greater than 0.05 μm and less than or equal to 0.2 μm. In this way, the first second sub-range, the second second sub-range, the first first sub-range, and the second first sub-range increase in sequence. The corresponding second parameter range may correspond to two second sub-parameter ranges, and the first parameter range may correspond to two first sub-parameter ranges. Taking the unchanged reverse current during laser-assisted sintering as an example, the reverse current in the first second sub-parameter range, the reverse current in the second second sub-parameter, the reverse current in the first first sub-parameter range and the reverse current in the second first sub-parameter range are all equal, the laser power in the first second sub-parameter range is W, the laser power range in the second second sub-parameter is 0.7W~0.9W, the laser power in the first first sub-parameter range is 0.5W~0.7W, and the laser power in the second first sub-parameter range is 0.3W~0.5W.

[0069] That is, different first grid lines 110 are divided into four levels according to the overlap index of the first grid lines 110 , and each level of the first grid lines 110 corresponds to a respective level of laser power, so that each first grid line 110 can achieve a relatively moderate sintering degree.

[0070] It can be understood that the first type of grid lines 111 and the corresponding first parameter range, and the second type of grid lines 112 and the corresponding second parameter range can be obtained based on previous test data, and the optimal parameter ranges corresponding to the first grid lines 110 with different overlapping degrees can be obtained based on multiple sets of empirical data. For example, during the test process, a test cell is formed, and the test cell has first grid lines with different overlapping degrees; the test cell is subjected to laser-assisted sintering, and then the test cell is subjected to electroluminescence or photoluminescence testing, so that the first grid lines with a relatively moderate sintering degree under the parameters of the laser-assisted sintering can be obtained; and then the overlapping degree corresponding to the first grid lines is obtained, so that the corresponding relationship between the overlapping degree and the parameter range can be obtained.

[0071] In the method for preparing a solar cell provided in an embodiment of the present application, before the laser-assisted sintering process, a plurality of first grid lines 110 are provided on the first surface 101 of the cell 100, and a plurality of second grid lines 120 are provided on the second surface 102 of the cell 100, and the first grid lines 110 and the second grid lines 120 are respectively used to collect carriers on the first surface 101 and the second surface 102. The laser-assisted sintering process is used to perform laser-assisted sintering on the first grid lines 110, and the first grid lines 110 are not electrically connected to the structure in the cell 100 before the laser-assisted sintering, and the second grid lines 120 are electrically connected to the structure in the cell 100 before the laser-assisted sintering process. Before the laser-assisted sintering process, the overlapping index of each first grid line 110 on the battery cell 100 is first obtained, and the first grid lines 110 are classified according to the overlapping index of each first grid line 110, so as to divide the first grid lines 110 into at least first-type grid lines 111 and second-type grid lines 112. The overlapping degree of the first-type grid lines 111 is greater than that of the second-type grid lines 112. Therefore, in the subsequent laser-assisted sintering process, the problem of overburning is more likely to occur than that of the second-type grid lines 112. During the laser-assisted sintering process, laser-assisted sintering is performed on the first type of grid lines 111 and the second type of grid lines 112 respectively using their respective corresponding first parameter ranges and second parameter ranges, and the maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range. In this way, the first type of grid lines 111 and the second type of grid lines 112 can both be laser-assisted sintered under relatively matched process conditions, thereby avoiding the problem of over-burning of the first type of grid lines 111 and the problem of under-burning of the second type of grid lines 112, thereby improving the yield and efficiency of solar cells.

[0072] Correspondingly, another embodiment of the present application further provides a solar cell, which is formed by the solar cell preparation method in the above embodiment. For the parts that are the same or corresponding to the previous embodiment, refer to the corresponding description of the above embodiment, and will not be described in detail below.

[0073] The solar cell can be 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) or a HIT / HJT cell (Heterojunction Technology).

[0074] The solar cell can be a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell or a multi-compound solar cell. The multi-compound solar cell can specifically be a cadmium sulfide solar cell, a gallium arsenide solar cell, a copper indium selenide solar cell or a perovskite solar cell.

[0075] The solar cell provided in the embodiment of the present application is formed by the preparation method of the solar cell in the above-mentioned embodiment. Before the laser-assisted sintering process, the overlap index of each first grid line on the cell sheet is first obtained, and the first grid lines are classified according to the overlap index of each first grid line, so as to divide the first grid lines into at least a first type of grid lines and a second type of grid lines. The overlap degree of the first type of grid lines is greater than that of the second type of grid lines. Therefore, in the subsequent laser-assisted sintering process, the first type of grid lines are more likely to have overburning problems than the second type of grid lines. In the process of performing the laser-assisted sintering process, laser-assisted sintering is performed for the first type of grid lines and the second type of grid lines respectively using the first parameter range and the second parameter range corresponding to each other. The maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range. In this way, the first type of grid lines and the second type of grid lines can both be laser-assisted sintered under relatively matched process conditions, avoiding the problem of overburning of the first type of grid lines and the problem of underburning of the second type of grid lines, thereby improving the yield and efficiency of solar cells.

[0076] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: Providing a battery cell, the battery cell having a first surface and a second surface opposite to each other, the first surface having a plurality of first grid lines, the second surface having a plurality of second grid lines, the first grid lines and the second grid lines extending in the same direction; Obtaining an overlap index of each of the first grid lines on the cell, wherein the overlap index is represented by an overlap degree between an orthographic projection of the first grid line on the first surface and an orthographic projection of the second grid line on the first surface; Classifying the first gate lines according to the overlap index of each of the first gate lines, so as to divide the first gate lines into at least a first type of gate lines and a second type of gate lines, wherein the overlap indexes corresponding to the first gate lines in the first type of gate lines are within a first range, the overlap indexes corresponding to the first gate lines in the second type of gate lines are within a second range, and a minimum value of the first range is greater than or equal to a maximum value of the second range; A laser-assisted sintering process is performed, wherein the process parameters used by the first type of grid lines are within a first parameter range, the process parameters used by the second type of grid lines are within a second parameter range, and the maximum value of at least one parameter range in the first parameter range is less than or equal to the minimum value of the corresponding parameter range in the second parameter range.

2. The method for preparing a solar cell according to claim 1, characterized in that: The laser-assisted sintering process comprises: Each of the first-type grid lines corresponds to a set of first parameters in the first parameter range, and each of the first-type grid lines is individually subjected to a laser-assisted sintering process using the first parameters corresponding to the first grid lines; Each of the second-type grid lines corresponds to a set of second parameters in the second parameter range, and each of the second-type grid lines is individually subjected to a laser-assisted sintering process using the second parameters corresponding to the second parameters.

3. The method for preparing a solar cell according to claim 2, characterized in that: The step of performing the laser-assisted sintering process includes at least two laser light sources, the laser power of one laser light source is adjusted according to the first parameter corresponding to each of the first-type grid lines, and the laser power of the other laser light source is adjusted according to the second parameter corresponding to each of the second-type grid lines.

4. The method for preparing a solar cell according to claim 1, characterized in that: After classifying the first gate lines according to the overlap index of each of the first gate lines, the method comprises: Dividing the first surface into at least a first area and a second area, wherein an area where a plurality of adjacent first-type gate lines are located is the first area, and an area where a plurality of adjacent second-type gate lines are located is the second area; In the step of performing the laser-assisted sintering process, each of the first zones corresponds to a set of first parameters in the first parameter range, each of the second zones corresponds to a set of second parameters in the second parameter range, each of the first zones uses the first parameter pair corresponding to it for laser-assisted sintering, and each of the second zones uses the second parameter pair corresponding to it for laser-assisted sintering.

5. The method for preparing a solar cell according to claim 4, characterized in that: The first parameter corresponding to each first area is obtained according to the average value of the overlapping indexes of multiple first-type gate lines in each first area; the second parameter corresponding to each second area is obtained according to the average value of the overlapping indexes of multiple second-type gate lines in each second area.

6. The method for preparing a solar cell according to claim 4, characterized in that: The first parameter corresponding to each first area is obtained according to the median of the overlapping indexes of multiple first-type gate lines in each first area; the second parameter corresponding to each second area is obtained according to the median of the overlapping indexes of multiple second-type gate lines in each second area.

7. The method for preparing a solar cell according to claim 4, characterized in that: The step of performing the laser-assisted sintering process includes at least two laser light sources, the laser power of one laser light source corresponds to the first parameter, and the laser power of the other laser light source corresponds to the second parameter.

8. The method for preparing a solar cell according to claim 1, characterized in that: The first range corresponds to multiple non-overlapping first sub-ranges, the first parameter range corresponds to multiple non-overlapping first sub-parameter ranges, and the first sub-ranges correspond one-to-one to the first sub-parameter ranges; the second range corresponds to multiple non-overlapping second sub-ranges, the second parameter corresponds to multiple non-overlapping second sub-parameter ranges, and the second sub-ranges correspond one-to-one to the second sub-parameter ranges.

9. The method for preparing a solar cell according to claim 1, characterized in that: The overlap index is a ratio of an overlap width of an orthographic projection of the first gate line on the first surface to an orthographic projection of the second gate line on the first surface to a width of the first gate line.

10. A solar cell, characterized in that: The solar cell is formed by the method for preparing a solar cell according to any one of claims 1 to 9.

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