Laser-induced sintering processing method and processing device

Abstract

The invention provides a laser-induced sintering processing method and a laser-induced sintering processing device, which are used for carrying out partitioned laser-induced sintering on a double-sided electrode photovoltaic cell. Respectively arranging a second electrode and a first electrode on the second surface and the first surface of the battery piece to contact the second surface and the first surface grid line, applying a first reverse bias to the battery piece, enabling the first electrode to contact the edge area, and scanning the middle area by laser; and arranging a second electrode and a third electrode on the second surface and the first surface of the cell to contact the second surface and the first surface grid line, applying a second reverse bias to the cell, enabling the third electrode to contact the middle area, and scanning the edge area by laser. The middle region is the middle region in the extending direction of the fine grid, and the edge regions are regions at two ends. The second reverse bias voltage is smaller than the first reverse bias voltage, higher reverse bias voltage is loaded to the middle area of the photovoltaic cell to promote the laser-induced sintering treatment degree, lower reverse bias voltage is applied to the edge area, reverse breakdown is avoided, and the poor EL black edge caused by over-treatment is prevented.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a laser induced sintering processing method and processing device. Background Art

[0002] The contact resistance between the electrodes of crystalline silicon solar cells significantly impacts the cell's fill factor and conversion efficiency. Lower contact resistance leads to higher fill factor and conversion efficiency, making reducing contact resistance a pressing need for major cell manufacturers. Existing technology utilizes laser-induced sintering (LIS) technology, which stimulates charge carriers through laser excitation and promotes interdiffusion between metal and silicon under an external reverse bias, resulting in excellent post-sintering contact properties.

[0003] The existing laser-induced sintering (LIS) process for mass-produced solar cell processing uses the same reverse bias and laser parameters to process the entire cell. However, within the same cell, due to the influence of process technologies such as diffusion, wet chemical etching, and coating, the LIS parameters required on both sides of the cell and in the middle are different. In the existing technology, using the same parameters for processing will inevitably affect the cell's photoelectric conversion efficiency or quality rate. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a laser induced sintering processing method and processing device.

[0005] To achieve the above purpose, the present invention provides a laser induced sintering processing method, which performs laser induced sintering on double-sided electrode photovoltaic cells in different zones.

[0006] Setting a second electrode in contact with a second surface grid line of the photovoltaic cell, setting a first electrode in contact with a first surface grid line of the photovoltaic cell, connecting the first electrode and the second electrode to an external power source, applying a first reverse bias voltage to the photovoltaic cell, wherein the first electrode contacts an edge region of the photovoltaic cell, and a laser scans a middle region of the photovoltaic cell to perform laser-induced sintering of the middle region;

[0007] Setting a second electrode in contact with the second surface grid line of the photovoltaic cell, setting a third electrode in contact with the first surface grid line of the photovoltaic cell, the third electrode and the second electrode being connected to an external power supply, applying a second reverse bias voltage to the photovoltaic cell, wherein the third electrode contacts the middle area of ​​the photovoltaic cell, and the laser scans the edge area of ​​the photovoltaic cell to perform laser induced sintering on the edge area;

[0008] wherein the second reverse bias voltage is less than the first reverse bias voltage;

[0009] The middle region is the middle region of the photovoltaic cell sheet in the extension direction of the fine grid, and the edge region is the region at both ends of the photovoltaic cell sheet in the extension direction of the fine grid.

[0010] As a further improvement of the present invention, the area of ​​the edge region is not greater than the area of ​​the middle region.

[0011] As a further improvement of the present invention, the ratio of the area of ​​the edge region to the area of ​​the middle region is 1:4 to 1:1.

[0012] As a further improvement of the present invention, the edge regions at both ends have equal areas.

[0013] As a further improvement of the present invention, there are two first electrodes, which are respectively arranged at positions of the edge regions at both ends close to the middle region.

[0014] As a further improvement of the present invention, there is one third electrode, which is arranged on the center line of the photovoltaic cell; or, there are two third electrodes, which are respectively arranged at positions of the edge areas near both ends of the middle area.

[0015] As a further improvement of the present invention, the first reverse bias voltage is 12 to 23 V, and / or the second reverse bias voltage is 1 to 5 V lower than the first reverse bias voltage.

[0016] As a further improvement of the present invention, the first laser power density for laser induced sintering of the middle region is 20 to 100 W / mm 2 , a second laser power density for laser-induced sintering of the edge region is 50% to 100% of the first laser power density.

[0017] As a further improvement of the present invention, laser induced sintering of the middle area and laser induced sintering of the edge area of ​​the photovoltaic cell are respectively carried out at two workstations set up successively, and the workstation for laser induced sintering of the middle area is before or after the workstation for laser induced sintering of the edge area.

[0018] As a further improvement of the present invention, the area of ​​the edge region is smaller than that of the middle region, and the laser scanning speed for laser induced sintering of the middle region is greater than the laser scanning speed for laser induced sintering of the edge region.

[0019] As a further improvement of the present invention, when laser induced sintering is performed on the middle area, at least two split light beams are used to laser scan the middle area, and the union of the scanning areas of the multiple split light beams covers the middle area; and / or,

[0020] When performing laser induced sintering on the edge region, at least two split light beams are used to perform laser scanning on the edge region, and a union of scanning areas of the multiple split light beams covers the edge region.

[0021] In another aspect, a laser induced sintering processing device is provided for implementing the aforementioned method, comprising a carrying device, the carrying device comprising at least two carrying units and a driving mechanism for driving the carrying units to move to a middle area laser induced sintering station and an edge area laser induced sintering station;

[0022] The photovoltaic cell is placed on the carrying unit and is moved to the middle area laser induced sintering station and the edge area laser induced sintering station respectively via the driving mechanism;

[0023] A first electrode that can be raised and lowered is provided above the laser-induced sintering station in the middle area to contact the edge area of ​​the first surface of the photovoltaic cell, and a first laser processing module is provided to perform laser scanning on the middle area of ​​the photovoltaic cell;

[0024] A third electrode that can be raised and lowered is provided above the edge area laser induced sintering station to lower and contact the middle area of ​​the first surface of the photovoltaic cell, and a second laser processing module is provided to perform laser scanning on the edge area of ​​the photovoltaic cell;

[0025] The second electrode is a conductive plate provided on the upper surface of the carrier platform. When the photovoltaic cell is placed on the carrier platform, the conductive plate contacts the second surface grid line of the photovoltaic cell. A movable conductive contact portion is provided above the laser induced sintering station in the middle area and the laser induced sintering station in the edge area to contact the conductive plate.

[0026] The first electrode and the conductive contact portion are connected to the positive and negative poles of the power supply respectively, and the third electrode and the conductive contact portion are connected to the positive and negative poles of the power supply respectively;

[0027] Wherein, the middle area laser induced sintering station is arranged before or after the edge area laser induced sintering station.

[0028] As a further improvement of the present invention, the first laser processing module is provided with a light splitting component to split the laser into at least two beams.

[0029] As a further improvement of the present invention, the carrying device is a turntable module, the driving mechanism is a rotary motor, and the carrying unit is four carrying platforms evenly arranged along the circumference of the rotary motor. The rotary motor drives the carrying platforms to rotate 90 degrees in steps, driving the carrying platforms to pass through the middle area laser induced sintering station and the edge area laser induced sintering station;

[0030] The laser induced sintering station in the middle area is adjacent to the laser induced sintering station in the edge area.

[0031] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0032] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0033] The technical solution employed in this invention applies a second reverse bias voltage to the edge of a photovoltaic cell during laser-induced sintering, which is lower than the first reverse bias voltage applied to the center of the cell. Applying a higher reverse bias voltage to the center promotes laser-induced sintering, while applying a lower reverse bias voltage to the edge of the cell prevents reverse breakdown and EL black edge defects caused by over-processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 is a schematic diagram of the middle area and edge area of ​​a photovoltaic cell of the present invention;

[0036] Figure 2 Schematic diagram of the relative positions of the first electrode and the photovoltaic cell according to an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of the relative positions of the third electrode and the photovoltaic cell according to an embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of the relative positions of the third electrode and the photovoltaic cell according to another embodiment of the present invention;

[0039] Figure 5 1 is a schematic structural diagram of a laser induced sintering processing device according to an embodiment of the present invention;

[0040] Figure 6 It is a structural schematic diagram of a laser induced sintering station in which a carrier platform is located in the middle area according to an embodiment of the present invention.

[0041] In all the drawings, the same reference numerals represent the same technical features, specifically:

[0042] Middle area A, edge area B, first edge area B1, second edge area B2;

[0043] A first electrode 11 , a second electrode 12 , a conductive contact 121 , a third electrode 13 , a power supply 14 ; a first laser processing module 2 , a rotating motor 31 , and a carrying platform 32 . DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0045] On the one hand, the present invention provides a laser-induced sintering processing method, which applies different reverse bias voltages to different areas of the photovoltaic cell. After laser-induced sintering, the contact resistance can be reduced, and reverse breakdown in the edge area of ​​the photovoltaic cell and EL black edge defects caused by over-processing can be avoided.

[0046] The laser-induced sintering processing method provided by the present invention is applied to double-sided electrode photovoltaic cells. Double-sided electrode photovoltaic cells refer to photovoltaic cells with grid lines for carrier extraction provided on both the front and back sides. The grid lines are sintered or pre-sintered grid lines.

[0047] The method of the present invention is used to perform laser induced sintering on double-sided electrode photovoltaic cells, and to perform zone induced sintering on photovoltaic cells. For details, see Figure 1 , a schematic diagram of the middle and edge regions of a photovoltaic cell. Along the extension direction of the photovoltaic cell's fine grid, the photovoltaic cell is divided into a middle region A and an edge region B. The strip-shaped regions at both ends of the fine grid extension direction are called edge regions B. For ease of description, the edge region at one end is called the first edge region B1, and the edge region at the other end is called the second edge region B2.

[0048] The method of the present invention is used to perform laser induced sintering on double-sided electrode photovoltaic cells. When laser induced sintering is performed on the edge area B, the reverse bias voltage applied (hereinafter referred to as the second reverse bias voltage) is smaller than the reverse bias voltage applied when laser induced sintering is performed on the middle area A (hereinafter referred to as the first reverse bias voltage).

[0049] Specifically, the first reverse bias voltage ranges from 12 to 23 V, and the second reverse bias voltage is 1 to 5 V lower than the first reverse bias voltage.

[0050] Due to the manufacturing process, the sheet resistance of the edge region of a photovoltaic cell is higher than that of the middle region. For example, the high-temperature diffusion process will result in a lower doping concentration in the edge region, and the wet etching process will cause slight over-etching in the edge region. These processes will all lead to higher sheet resistance in the edge region. Currently, when performing laser-induced sintering on the middle and edge regions, technicians in this field apply a higher reverse bias voltage to the edge region than to the middle region, or apply the same reverse bias voltage to the edge region, and achieve the laser-induced sintering effect by controlling the laser power.

[0051] However, the applicant found in the research that the depletion layer width in the high square resistance region of the photovoltaic cell is larger and the carrier mobility is higher. When the reverse bias voltage increases, the electric field strength in the depletion layer is more likely to reach a level that allows the carriers to obtain sufficient energy to induce collision ionization, thereby leading to avalanche breakdown. Therefore, the edge area of ​​the photovoltaic cell is not suitable for applying a higher reverse bias voltage for laser induced sintering treatment.

[0052] Based on this, when laser-induced sintering is performed on photovoltaic cells using the technical solution of the present invention, the second reverse bias applied to the edge region B of the photovoltaic cell is lower than the first reverse bias applied to the middle region A. Applying a higher reverse bias to the middle region of the photovoltaic cell promotes the degree of laser-induced sintering, while applying a lower reverse bias to the edge region avoids reverse breakdown and prevents EL black edge defects caused by over-processing.

[0053] As a preferred embodiment, the width and area of ​​the first edge region B1 and the second edge region B2 are equal, or substantially equal. The area of ​​the edge region B is no larger than that of the middle region A. Specifically, the area ratio of the edge region B to the middle region A is 1:4 to 1:1, with exemplary ranges or point values ​​of 1:4 to 1:3, 1:3 to 1:2, 1:2 to 2:3, 1:1.5 to 1:1, etc. Preferably, the area ratio of the edge region B to the middle region A is 2:5 to 1:1, or 2:3 to 1:1. Taking a 182mm×182mm battery as an example, the widths of the first edge region B1 and the second edge region B2 are both 10 to 45.5mm. This maximizes the degree of laser-induced sintering treatment in the middle and edge regions while avoiding reverse breakdown and EL black edge defects caused by over-treatment in the edge regions.

[0054] Those skilled in the art know that when laser induced sintering is performed on a double-sided electrode photovoltaic cell, a reverse bias is applied to the photovoltaic cell while a laser is used to irradiate the surface of the photovoltaic cell to achieve laser induced sintering. The photovoltaic cell includes two surfaces arranged opposite to each other, a first surface and a second surface, wherein the first surface can be the front side or the back side, and correspondingly, the second surface is the back side or the front side. In the present invention, the front side refers to the light-receiving side of the photovoltaic cell, and the back side refers to the backlight side of the photovoltaic cell. In the present invention, a second electrode is provided on the second surface of the photovoltaic cell, and is in contact with the grid line on the second surface of the photovoltaic cell. A first electrode or a third electrode is provided on the first surface of the photovoltaic cell, and is in contact with the grid line on the first surface of the photovoltaic cell. A first reverse bias is applied to the photovoltaic cell through the second electrode and the first electrode, and a laser scan is performed on the middle area A of the first surface to complete the laser induced sintering. A second reverse bias is applied to the photovoltaic cell through the second electrode and the third electrode, and a laser scan is performed on the edge area B of the first surface to complete the laser induced sintering. It should be noted that in some embodiments, the first surface is described as the front surface and the second surface as the back surface, but the present invention is not limited thereto. The first surface may also be the back surface and the corresponding second surface may be the front surface.

[0055] The first electrode and the third electrode of the present invention are preferably strip electrodes. Among them, the structure of the first electrode and the third electrode can be an elastic probe row structure (i.e., a plurality of elastic probes arranged in a collinear manner are connected under a probe holder, and the plurality of probes are in contact with the grid lines of the photovoltaic cell sheet), or an elastic conductive wire structure, or an elongated elastic electrode sheet structure (the electrode sheet and the photovoltaic cell sheet can be in surface contact). The structures of the first electrode and the third electrode are not limited to this, and any structure that can achieve the same function is acceptable. It should be noted that the strip electrode here refers to the outer contour of the electrode projected on the horizontal plane as a whole being strip-shaped. The length direction of the first electrode and the third electrode is perpendicular to the extension direction of the fine grid, and contacts the front grid lines of the photovoltaic cell sheet.

[0056] See also Figures 2 to 4 , Figure 2 Schematic diagram of the relative positions of the first electrode and the photovoltaic cell according to an embodiment of the present invention. Figure 3 Schematic diagram of the relative positions of the third electrode and the photovoltaic cell according to an embodiment of the present invention. Figure 4 FIG. 1 is a schematic diagram of the relative positions of the third electrode and the photovoltaic cell according to another embodiment of the present invention. Figure 2 As shown, when laser induced sintering is performed on the middle area, two first electrodes 11 for applying voltage on the front are provided, which are respectively arranged in the first edge area B1 and the second edge area B2 close to the middle area A. The laser scans the middle area A and laser induced sintering is performed on the middle area A.

[0057] In the laser induced sintering method of the present invention, the middle region has a larger area and a wider width, and the processing effects at the two lateral ends of the middle region will be very different. This solution sets two first electrodes to achieve conduction nearby, reduce the voltage drop in the middle region, and help improve the laser induced sintering effect.

[0058] For details, see Figure 3 When laser induced sintering is performed on the edge region B, there is one third electrode 13 for applying voltage on the front side, which is arranged in the middle region A, preferably on the center line of the photovoltaic cell. More preferably, see Figure 4 There are two third electrodes 13, which are arranged in the middle area A close to the edge area B. The laser scans the edge area B to achieve conduction nearby, which is conducive to improving the laser induced sintering effect.

[0059] The laser induced sintering method of the present invention performs laser induced sintering of the middle region A and the edge region B of the photovoltaic cell at two stations, respectively. The following description is made in conjunction with a processing device for realizing laser induced sintering. Specifically, the processing device includes a carrying device, and the carrying device includes at least two carrying units and a driving mechanism for driving the carrying units to move to the middle region laser induced sintering station and the edge region laser induced sintering station. The photovoltaic cell is placed on the carrying unit and is driven by the driving mechanism to move to the middle region laser induced sintering station and the edge region laser induced sintering station, respectively. Laser induced sintering is performed on the middle region laser induced sintering station, and laser induced sintering is performed on the edge region laser induced sintering station. When one carrying unit is located at the middle region laser induced sintering station, the other carrying unit is located at the edge region laser induced sintering station. A feeding device is used to continuously feed the carrier unit, so that the middle area of ​​the same cell can be laser-induced sintered at the middle area laser-induced sintering station and then transferred to the edge area laser-induced sintering station for laser-induced sintering of the edge area. When the previous cell is laser-induced sintering at the edge area laser-induced sintering station, the next cell is laser-induced sintered at the middle area laser-induced sintering station. It can be understood that corresponding laser-induced sintering components are set at the middle area laser-induced sintering station and the edge area laser-induced sintering station. Specifically, a first electrode for contacting the front grid line of the photovoltaic cell from above and a second electrode for contacting the back electrode of the photovoltaic cell from below are set at the middle area laser-induced sintering station. A third electrode for contacting the front grid line of the photovoltaic cell from above and a second electrode for contacting the back electrode of the photovoltaic cell from below are set at the edge area laser-induced sintering station. At the same time, the laser induced sintering station in the middle area and the laser induced sintering station in the edge area also include a first laser processing module and a second laser processing module that irradiate the middle area and the edge area of ​​the battery cell from above. Although the above description is based on the example of passing through the laser induced sintering station in the middle area first, the present invention is not limited to this. The laser induced sintering station in the middle area is set before or after the laser induced sintering station in the edge area. That is, the order of laser induced sintering in the middle area and laser induced sintering in the edge area is not limited. These two stations are preferably set adjacent to each other, and pass through these two stations in sequence to complete the corresponding laser induced sintering.

[0060] As an implementable approach, see Figure 5, is a structural diagram of a laser induced sintering processing device according to an embodiment. Among them, the carrying device is a turntable module, the driving mechanism is a rotary motor 31, and the carrying unit is a carrying platform 32 evenly arranged along the circumference of the rotary motor. Preferably, there are four carrying units, that is, four carrying platforms 32 are evenly distributed around the circumference of the rotary motor 31. The rotary motor 31 drives the carrying platform to rotate 90 degrees in steps, passing through the middle area laser induced sintering station (first station) and the edge area laser induced sintering station (second station) in sequence, and the photovoltaic cells complete the corresponding area processing at the corresponding stations. The middle area laser induced sintering station and the edge area laser induced sintering station are preferably arranged adjacent to each other. At the remaining two stations, photovoltaic cell loading and unloading, visual positioning, etc. can be performed. It is only necessary to set the corresponding cell handling mechanism and visual positioning camera at the corresponding station. This is a prior art and will not be described here.

[0061] Continue to see Figure 5 In this embodiment, the loading station is before the first station, and the unloading station is after the second station. When laser induced sintering of photovoltaic cells, the feeding device feeds the cells to the loading station, which is rotated 90 degrees by the rotary motor, passes through the first station and performs laser induced sintering of the middle area at this station, then passes through the second station and performs laser induced sintering of the edge area at this station, and then passes through the unloading station to transfer the photovoltaic cells that have completed laser induced sintering. In this way, continuous laser induced sintering of photovoltaic cells can be achieved. It should be noted that the above embodiment is described as an example in which the laser induced sintering station in the middle area is before the laser induced sintering station in the edge area. The present invention is not limited to this. The laser induced sintering station in the edge area can be before the laser induced sintering station in the middle area.

[0062] See also Figure 6 , Figure 6This is a structural schematic diagram of a carrier platform located in a middle area laser induced sintering station according to an embodiment of the present invention. The photovoltaic cell is placed on the carrier platform 32 with its back side facing downward and its front side facing upward. The first electrode 11 is a probe row that can be raised and lowered above the carrier platform 32 (the middle area laser induced sintering station) by a lifting device such as a cylinder. The second electrode 12 is a conductive plate, such as a conductive copper plate, disposed on the upper surface of the carrier platform 32, which contacts the back grid line of the photovoltaic cell. The first electrode 11 and the second electrode 12 are respectively connected to the positive and negative poles of the power supply 14. The first electrode 11 descends to contact the front grid line of the photovoltaic cell, and the power supply 14 applies a reverse bias to the photovoltaic cell. The first laser processing module 2 is disposed above the first electrode 11 to scan the middle area of ​​the photovoltaic cell. Furthermore, it also includes a conductive contact piece 121 arranged above the carrier platform 32 (middle area laser induced sintering station), which is movably arranged above the carrier platform 32 (middle area laser induced sintering station) by a moving device such as a lifting device, and is connected to the power supply 14. The photovoltaic cell arrives at the middle area laser induced sintering station with the carrier platform 32, and this conductive contact piece 121 descends and contacts the second electrode 12 (conductive plate). The first electrode 11 (probe row) also descends to contact the front grid line of the photovoltaic cell, thereby applying a reverse bias to the photovoltaic cell.

[0063] In this embodiment, the conductive plate is arranged on the supporting platform and can be moved with the supporting platform to the edge area laser induced sintering station, and cooperate with the third electrode located at the edge area laser induced sintering station to apply reverse bias to the photovoltaic cell, and scan the edge area of ​​the photovoltaic cell through the second laser processing module.

[0064] The laser induced sintering of the edge region of the carrier platform is similar to that of the laser induced sintering station in the middle region. A liftable third electrode and a movable conductive contact are provided above the laser induced sintering station in the edge region. The third electrode and the conductive contact are respectively connected to the positive and negative poles of the power supply to apply a reverse bias to the photovoltaic cell. A second laser processing module is provided above the laser induced sintering station in the edge region to perform laser scanning on the edge region to achieve laser induced sintering in the edge region.

[0065] It should be noted that the conductive plate can be a solid copper plate or a hollowed copper plate, with the edge of the conductive plate extending beyond the photovoltaic cell to allow the conductive contact to contact the conductive plate from above. The conductive contact can be a conductive post or a probe array, as long as it can achieve electrical continuity between the power supply and the conductive plate.

[0066] As described in the laser induced sintering processing method, the first electrode 11 and the third electrode 13 are both strip electrodes. There are two first electrodes 11, which are respectively arranged at the edge area B at both ends of the photovoltaic cell near the position of the middle area A. There are two third electrodes 13, which are arranged at the position of the middle area A of the photovoltaic cell near the edge area B at both ends, or arranged at the center line of the photovoltaic cell. Generally speaking, the photovoltaic cell is basically placed at the center of the carrier 32, and the first electrode 11 and the second electrode 13 are correspondingly arranged above the laser induced sintering station in the middle area or the laser induced sintering station in the edge area. It should be noted that when the carrier rotates 90 degrees in steps, the photovoltaic cell is rotated 90 degrees relative to the laser induced sintering station in the middle area and the laser induced sintering station in the edge area, and the first electrode 11 and the second electrode 13 are also correspondingly arranged at the corresponding stations. The position setting of the first electrode and the second electrode avoids blocking the laser, and the laser scanning of the entire width of the photovoltaic cell is completed at the middle induced sintering station and the edge induced sintering station.

[0067] In some other embodiments, the second electrode can be a liftable electrode arranged under the supporting platform, which does not move with the supporting platform. When the supporting platform moves to the middle area laser induced sintering station and the edge area laser induced sintering station, it is lifted up to contact the grid line on the back of the battery cell. At this time, the second electrode is set at both the middle area laser induced sintering station and the edge area laser induced sintering station.

[0068] Any implementation method that can achieve electrical connection between the second electrode and the back grid line of the photovoltaic cell is within the scope of protection of this application. The above are all existing technologies and will not be repeated here.

[0069] Typically, the area of ​​the middle region of a photovoltaic cell is larger than that of the edge region. For example, the area ratio of the edge region B to the middle region A is 1:4 to 1:3. In this way, when two stations are processed in parallel, the laser induced sintering time of the middle region will be much longer than that of the edge region. In order to further improve production capacity, in some preferred embodiments, the laser scanning speed for laser induced sintering of the middle region is greater than the laser scanning speed for laser induced sintering of the edge region, so that the processing time of the two stations is as similar as possible, avoiding waiting time; in other preferred embodiments, at least two split beams are used to scan different positions of the middle region, and the union of the scanning areas of the multiple split beams covers the middle region, so that the processing time of the two stations is as similar as possible. For example, a splitter device can be set in the first laser processing module to be divided into two split beams. As another embodiment, when performing laser induced sintering on the middle region and the edge region, a method of scanning multiple split beams can be used. This can reduce the scanning speed and improve the sintering effect while ensuring processing efficiency.

[0070] In other embodiments, the driving mechanism may be a linear driving mechanism such as a linear motor, and the carrying device may be an interactive module. The positions of the first electrode and the third electrode and the laser scanning position may be set at corresponding workstations.

[0071] In laser induced sintering technology, in addition to reverse bias voltage, laser power is also a key parameter affecting the degree of laser induced sintering treatment. The higher the laser power, the stronger the treatment degree, and the edge area is more likely to be over-treated. In a preferred embodiment, the first laser power density for laser induced sintering of the middle area is 20 to 100 W / mm 2 The second laser power density during laser induced sintering of the edge region is reduced by 0 to 50% compared to the first laser power density. In other words, the second laser power density is 50% to 100% of the first laser power density.

[0072] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A laser induced sintering method, characterized in that: Partitioned laser induced sintering of double-sided electrode photovoltaic cells, Setting a second electrode in contact with a second surface grid line of the photovoltaic cell, setting a first electrode in contact with a first surface grid line of the photovoltaic cell, connecting the first electrode and the second electrode to an external power source, applying a first reverse bias voltage to the photovoltaic cell, wherein the first electrode contacts an edge region of the photovoltaic cell, and a laser scans a middle region of the photovoltaic cell to perform laser-induced sintering of the middle region; Setting a second electrode in contact with the second surface grid line of the photovoltaic cell, setting a third electrode in contact with the first surface grid line of the photovoltaic cell, the third electrode and the second electrode being connected to an external power supply, applying a second reverse bias voltage to the photovoltaic cell, wherein the third electrode contacts the middle area of ​​the photovoltaic cell, and the laser scans the edge area of ​​the photovoltaic cell to perform laser induced sintering on the edge area; wherein the second reverse bias voltage is less than the first reverse bias voltage; The middle region is the middle region of the photovoltaic cell sheet in the extension direction of the fine grid, and the edge region is the region at both ends of the photovoltaic cell sheet in the extension direction of the fine grid.

2. The laser induced sintering method according to claim 1, characterized in that: The area of ​​the edge region is no greater than that of the middle region.

3. The laser induced sintering method according to claim 1, characterized in that: The ratio of the area of ​​the edge region to the area of ​​the middle region is 1:4 to 1:

1.

4. The laser induced sintering method according to claim 2, characterized in that: The edge regions at both ends have the same area.

5. The laser induced sintering method according to claim 1, characterized in that: There are two first electrodes, which are respectively arranged at positions of the edge areas at both ends close to the middle area.

6. The laser induced sintering method according to claim 1, characterized in that: There is one third electrode, which is arranged on the center line of the photovoltaic cell; or There are two third electrodes, which are respectively arranged at positions of the edge regions near both ends of the middle region.

7. The laser induced sintering method according to claim 1, characterized in that: The first reverse bias voltage is 12-23V, and / or the second reverse bias voltage is 1-5V lower than the first reverse bias voltage.

8. The laser induced sintering method according to claim 1, characterized in that: The first laser power density for laser induced sintering of the middle region is 20 to 100 W / mm 2 , a second laser power density for laser-induced sintering of the edge region is 50% to 100% of the first laser power density.

9. The laser induced sintering method according to claim 1, characterized in that: The laser induced sintering of the middle area and the laser induced sintering of the edge area of ​​the photovoltaic cell are respectively performed at two stations set up successively, and the station for laser induced sintering of the middle area is before or after the station for laser induced sintering of the edge area.

10. The laser induced sintering method according to claim 9, characterized in that: The area of ​​the edge region is smaller than that of the middle region, and the laser scanning speed for laser induced sintering of the middle region is greater than the laser scanning speed for laser induced sintering of the edge region.

11. The laser induced sintering method according to claim 9, characterized in that: When performing laser induced sintering on the middle region, laser scanning the middle region is performed using at least two split beams, and a union of scanning areas of the multiple split beams covers the middle region; and / or, When performing laser induced sintering on the edge region, at least two split light beams are used to perform laser scanning on the edge region, and a union of scanning areas of the multiple split light beams covers the edge region.

12. A laser induced sintering processing device for implementing the laser induced sintering processing method according to any one of claims 1 to 11, characterized in that: The laser induced sintering device comprises a carrying device, the carrying device comprises at least two carrying units and a driving mechanism for driving the carrying units to move to a laser induced sintering station in a middle area and a laser induced sintering station in a peripheral area; The photovoltaic cell is placed on the carrying unit and is moved to the middle area laser induced sintering station and the edge area laser induced sintering station respectively via the driving mechanism; A first electrode that can be raised and lowered is provided above the laser-induced sintering station in the middle area to contact the edge area of ​​the first surface of the photovoltaic cell, and a first laser processing module is provided to perform laser scanning on the middle area of ​​the photovoltaic cell; A third electrode that can be raised and lowered is provided above the edge area laser induced sintering station to lower and contact the middle area of ​​the first surface of the photovoltaic cell, and a second laser processing module is provided to perform laser scanning on the edge area of ​​the photovoltaic cell; The second electrode is a conductive plate provided on the upper surface of the carrier platform. When the photovoltaic cell is placed on the carrier platform, the conductive plate contacts the second surface grid line of the photovoltaic cell. A movable conductive contact portion is provided above the laser induced sintering station in the middle area and the laser induced sintering station in the edge area to contact the conductive plate. The first electrode and the conductive contact portion are connected to the positive and negative poles of the power supply respectively, and the third electrode and the conductive contact portion are connected to the positive and negative poles of the power supply respectively; Wherein, the middle area laser induced sintering station is arranged before or after the edge area laser induced sintering station.

13. The laser induced sintering processing device according to claim 12, characterized in that: The first laser processing module is provided with a light splitting component to split the laser into at least two beams.

14. A laser induced sintering processing device according to claim 12 or 13, characterized in that: The carrying device is a turntable module, the driving mechanism is a rotary motor, and the carrying unit is four carrying platforms evenly arranged along the circumference of the rotary motor. The rotary motor drives the carrying platforms to rotate in 90-degree steps, driving the carrying platforms to pass through the middle area laser induced sintering station and the edge area laser induced sintering station; The laser induced sintering station in the middle area is adjacent to the laser induced sintering station in the edge area.

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