Laser sintering device and method and photovoltaic cell

Abstract

The invention discloses a laser sintering device and method and a photovoltaic cell, and belongs to the technical field of photovoltaic cells. The laser sintering device comprises a conductive platform deck, a probe module, a constant-voltage power supply and a laser system, the conductive platform deck is used for bearing a battery piece; the probe module comprises a first probe row and a second probe row, and the first probe row and the second probe row are both movably arranged above the conductive platform deck and are used for being in contact with grid lines on a battery piece; the positive electrode of the constant-voltage power supply is electrically connected with the conductive platform deck, and the negative electrode of the constant-voltage power supply is electrically connected with the first probe row and the second probe row and used for applying reverse voltage to the battery piece; and the laser system is used for scanning the battery piece while applying the backward voltage to the battery piece. According to the invention, the consistency of laser sintering can be improved, so that the photoelectric conversion efficiency of a photovoltaic cell can be improved.

Description

Technical Field

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

[0002] In photovoltaic cells, contact is the core technology for improving cell conversion efficiency. It refers to the formation of low-resistance ohmic contact through electrical connection between metal electrodes and semiconductor materials to achieve efficient collection and transmission of carriers.

[0003] High-temperature sintering metallization is the primary method for achieving low-resistance contacts. Metal elements (such as Ag) in metal pastes (e.g., silver paste) alloy with the doped layer on the silicon wafer surface, forming an Ag-Si eutectic layer. This alloy layer eliminates the Schottky barrier and reduces contact resistance. Laser sintering significantly minimizes damage to the passivation layer while forming high-quality silver-silicon alloy contact sites within limited etch channels, reducing metal recombination while ensuring low contact resistance.

[0004] However, existing laser sintering devices have the problem of uneven voltage distribution on the battery cell, which affects the consistency of the laser sintering effect and leads to a decrease in photoelectric conversion efficiency. Summary of the Invention

[0005] The main purpose of the present invention is to provide a laser sintering device and method, and a photovoltaic cell, aiming to improve the consistency of laser sintering.

[0006] In the first aspect, the present invention provides a laser sintering device, comprising a conductive carrier, a probe module, a constant voltage power supply and a laser system; the conductive carrier is used to carry a battery cell; the probe module comprises a first probe row and a second probe row, and the first probe row and the second probe row can be movably arranged above the conductive carrier, for contacting the grid lines on the battery cell; the positive pole of the constant voltage power supply is electrically connected to the conductive carrier, and the negative pole of the constant voltage power supply is electrically connected to the first probe row and the second probe row, for applying a reverse voltage to the battery cell; the laser system is used to scan the battery cell while applying a reverse voltage to the battery cell.

[0007] In one embodiment, the probe module includes: a first fixed frame, a second fixed frame, a first translation unit, a second translation unit, a first fixed plate, a second fixed plate, a first lifting unit, a second lifting unit and a mounting plate; the first fixed frame is provided with a first probe row, and the second fixed frame is provided with a second probe row; the first translation unit is connected to the first fixed frame to drive the first probe row to move horizontally, and the second translation unit is connected to the second fixed frame to drive the second probe row to move horizontally; the first translation unit is provided on the first fixed plate, and the second translation unit is provided on the second fixed plate; the first lifting unit is connected to the first fixed plate to drive the first probe row to move up and down, and the second lifting unit is connected to the second fixed plate to drive the second probe row to move up and down; the first lifting unit and the second lifting unit are provided on the mounting plate.

[0008] In one embodiment, the first translation unit includes a first translation motor, a first driving wheel, a first driven wheel and a first synchronous belt; the first translation motor is vertically arranged on the first fixed plate; the first driving wheel and the first driven wheel are both toothed pulleys, and the first driving wheel and the first driven wheel are distributed in the horizontal direction, the first driving wheel is connected to the output shaft of the first translation motor, and the first driven wheel is rotatably arranged on the first fixed plate; the first synchronous belt is wound around the first driving wheel and the first driven wheel, and the first synchronous belt is connected to the first fixed frame; the second translation unit has the same structure as the first translation unit; and / or, the first lifting unit includes a ball screw transmission structure, and the second lifting unit has the same structure as the first lifting unit.

[0009] In one embodiment, the laser system includes a first laser assembly, a second laser assembly, an integration assembly, and a galvanometer; the first laser assembly includes a first laser, the wavelength of a first laser output by the first laser is 780nm-1400nm; the second laser assembly includes a second laser, the wavelength of a second laser output by the second laser is 400nm-700nm; the integration assembly is used to combine the first laser and the second laser at the galvanometer.

[0010] In one embodiment, the first laser assembly further includes a first shaping device, which is arranged on the output side of the first laser; and / or the second laser assembly further includes a second shaping device, a first lens, and a second lens, which are sequentially arranged on the output side of the second shaping device; the laser spots output by the first shaping device and the second shaping device are both rectangular flat-top spots.

[0011] In one embodiment, the integrated component includes a first reflector, a beam combiner and a second reflector; the first laser extends horizontally, the first reflector is arranged on the output side of the first laser, and the angle between the plane of the first reflector and the first laser is 45°; the second laser extends horizontally, the beam combiner is arranged on the output side of the second laser, and is located on the output side of the first reflector, and the angle between the plane of the beam combiner and the second laser is 45°, which is used to combine the first laser and the second laser; the second reflector is arranged on the output side of the beam combiner and is located on the input side of the galvanometer, and the angle between the second reflector and the combined laser is 45°; and / or, the first shaping device and the second shaping device each include at least one of a diffractive optical element, a refractive optical element, a microlens array, and a spatial light modulator; and / or, the long side dimension of the rectangular flat-top spot is 0.5mm-3mm.

[0012] In a second aspect, the present invention provides a laser sintering method, comprising: Provide any of the above-mentioned laser sintering devices; place a battery cell on a conductive carrier, so that the grid lines on the battery cell are arranged along the extension direction of the first probe row and the second probe row, and apply a reverse voltage to the battery cell through a constant voltage source; divide the battery cell into 2n areas along a first direction, where n is a positive integer and n≥2, and the first direction is perpendicular to the extension direction of the grid lines; move the first probe row and the second probe row down until they are in contact with the grid lines; power on the first probe row and power off the second probe row, and control the laser system to scan the area adjacent to the area where the first probe row is located from the proximal end of the first probe row; power on the second probe row and power off the first probe row, and control the laser system to scan the area adjacent to the area where the second probe row is located from the proximal end of the second probe row; when laser scanning the area adjacent to the area where the first probe row / second probe row is located, control the second probe row / first probe row to move to the next area; repeat the above steps until all areas are scanned.

[0013] In one embodiment, the battery cell is divided into a first area, a second area, a third area and a fourth area distributed in sequence along a first direction; the first probe row is moved to the second area, and the first probe row is pressed down to press the gate line, and the second probe row is moved to the third area, and the second probe row is pressed down to press the gate line; the first probe row is powered on, the second probe row is powered off, and the laser system is controlled to scan the first area from the proximal end of the first probe row; the second probe row is powered on, the first probe row is powered off, and the laser system is controlled to scan the fourth area from the proximal end of the second probe row, while the first probe row is controlled to move to the first area; the first probe row is powered on, the second probe row is powered off, and the laser system is controlled to scan the second area from the proximal end of the first probe row, while the second probe row is controlled to move to the fourth area; the second probe row is powered on, the first probe row is powered off, and the laser system is controlled to scan the third area from the proximal end of the second probe row.

[0014] In one embodiment, the time required for the first probe row and the second probe row to move to the next area is less than or equal to the time required for the laser system to scan the current area; and / or the reverse voltage is 8V-20V.

[0015] In a third aspect, the present invention provides a photovoltaic cell, which is processed by any of the above-mentioned laser sintering devices or any of the above-mentioned laser sintering methods.

[0016] The laser sintering device of the present invention includes two sets of probe rows, which can realize the regional processing of the battery cell. The probe row will move to the optimal position of the grid line according to the area scanned by the laser to energize, thereby reducing the fixed downward pressure of the probe row in a certain area, so that the voltage drop caused by the lateral resistance and the grid line resistance at the far end of the probe row is maintained, thereby making the surface of the battery cell basically maintain voltage uniformity during the laser sintering process. When the voltage uniformity is maintained on the surface of the battery cell, it means that the potential difference on the surface of the battery cell is basically consistent, and the photogenerated carriers (electrons and holes) are efficiently collected by the electrodes during the diffusion process, which helps to form a stable high-density current, improve the front uniformity of the laser sintering of the battery cell, and optimize the series resistance of the entire surface of the battery cell, thereby helping to improve the photoelectric conversion efficiency of the photovoltaic cell. In addition, compared with the conventional double-station processing method, the laser sintering device of the present invention can improve efficiency by more than 0.05%-0.1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 This is a schematic structural diagram of a laser sintering device in one embodiment of the present invention; Figure 2 A schematic structural diagram of a probe module according to an embodiment of the present invention; Figure 3 Schematic diagram of the structure of the first translation unit of the probe module in one embodiment of the present invention; Figure 4 2 is a schematic structural diagram of a first lifting unit of a probe module according to an embodiment of the present invention; Figure 5 A schematic structural diagram of a laser system according to an embodiment of the present invention; Figure 6 Schematic diagram of the initial states of the first probe row and the second probe row in the laser sintering method according to one embodiment of the present invention; Figure 7Schematic diagram of a state when a laser scans a first area in a laser sintering method according to an embodiment of the present invention; Figure 8 Schematic diagram of a state when the laser scans the fourth area in the laser sintering method according to one embodiment of the present invention; Figure 9 Schematic diagram of a state when the laser scans the second area in the laser sintering method according to one embodiment of the present invention; Figure 10 FIG. 1 is a schematic diagram of a state when the laser scans the third area in the laser sintering method according to an embodiment of the present invention.

[0019] Explanation of Figure Numbers 100, laser sintering device; 11, conductive carrier; 12, probe module; 121, first probe row; 122, second probe row; 123, first fixed frame; 124, second fixed frame; 125, first translation unit; 1251, first translation motor; 1252, first driving wheel; 1253, first driven wheel; 1254, first synchronous belt; 126, second translation unit; 127, first fixed plate; 128, second fixed plate; 129, first lifting unit; 1291, first lifting motor Machine; 1292, first ball screw; 1293, first support base; 1294, first slide; 1210, second lifting unit; 1211, mounting plate; 13, constant voltage power supply; 14, laser system; 141, galvanometer; 142, first laser; 143, second laser; 144, first shaping device; 145, second shaping device; 146, first lens; 147, second lens; 148, first reflector; 149, beam combiner; 1410, second reflector; 1411, field mirror; 200, battery cell; 21, first region; 22, second region; 23, third region; 24, fourth region. DETAILED DESCRIPTION It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. "At least one" appearing in the embodiments of the present invention refers to one or more, and "more" refers to two or more.

[0020] The "ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range.

[0021] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] During laser sintering metallization, the laser irradiates the cell, and the cell absorbs the laser photons to generate photogenerated carriers, electrons and holes. Under the action of an external reverse voltage, a loop current is formed. Externally injected electrons compensate for the electron loss on the cell surface, greatly reducing the damage to the passivation layer. At the same time, high-quality silver-silicon alloy contact sites can be formed within a limited etching channel, reducing metal recombination while ensuring low contact resistance.

[0023] In laser sintering technology, a probe row is required to apply a reverse voltage to the cell surface. This causes the laser to be blocked by the probe row when irradiating the entire cell surface, resulting in poor electroluminescence (EL) detection of the cell. To this end, the prior art uses two processing stations for laser sintering. In the first processing station, the electrical input module is pressed down on the left half of the cell, and the first laser illuminates the right half of the cell. The cell is then transferred to the second processing station, where the electrical input module is pressed down on the right half of the cell, and the second laser illuminates the left half of the cell, completing the processing of the entire cell. While this prior art solves the laser blocking problem, the electrical input module is only pressed down on a certain area of ​​the cell during processing. Due to the lateral resistance of the cell substrate and the line resistance of the gate lines themselves, a voltage drop occurs at the far end of the electrical input module, resulting in uneven voltage distribution across the entire cell, which affects the consistency of the laser sintering effect across the entire surface and reduces the photoelectric conversion efficiency.

[0024] In order to solve the above problems, the present invention provides a laser sintering device 100, referring to Figure 1-5As shown, it includes a conductive carrier 11, a probe module 12, a constant voltage power supply 13, and a laser system. The conductive carrier 11 is used to carry the battery cell 200; the probe module 12 includes a first probe row 121 and a second probe row 122, both of which are movably arranged above the conductive carrier 11 and are used to contact the grid lines on the battery cell 200; the positive electrode of the constant voltage power supply 13 is electrically connected to the conductive carrier 11, and the negative electrode of the constant voltage power supply 13 is electrically connected to the first probe row 121 and the second probe row 122, and is used to apply a reverse voltage to the battery cell 200; the laser system 14 is used to scan the battery cell 200 while applying the reverse voltage to the battery cell 200.

[0025] The conductive carrier 11 is not only used to support the battery cell 200, but also needs to apply a reverse voltage to the battery cell 200. Therefore, the conductive carrier 11 can be made of a metal material with good conductivity. In some embodiments, the material of the conductive carrier 11 can be copper, brass, copper, aluminum, or a gold-plated material.

[0026] The first probe row 121 and the second probe row 122 are used to cooperate with the conductive carrier 11 to achieve the purpose of applying a reverse voltage to the battery cell 200. Therefore, the first probe row 121 and the second probe row 122 are also made of conductive materials. In some embodiments, the material of the first probe row 121 and the second probe row 122 can be brass plated with gold or beryllium copper plated with gold.

[0027] The present invention does not impose any specific limitation on the structures of the first probe row 121 and the second probe row 122. In some embodiments, referring to Figure 2 As shown, the first probe row 121 includes a first mounting base and first probes. The first mounting base is a rectangular bar structure whose length matches the length of the grid lines on the cell. Multiple first probes are provided, and the multiple first probes are arranged along the length direction of the first mounting base. The first probes are vertically penetrated on the first mounting base. The second probe row 122 has the same structure as the first probe row 121.

[0028] The first probe row 121 and the second probe row 122 are movable to realize the regional processing of the battery cell 200. The first probe row 121 and the second probe row 122 will move to the optimal position of the gate line in turn according to the laser scanning area to energize, so as to ensure the voltage uniformity on the surface of the battery cell 200 during laser sintering as much as possible.

[0029] The constant voltage power supply 13 is a reverse voltage source. Applying a reverse voltage to the cell 200 through the constant voltage power supply 13 can compensate for the loss of surface electrons of the cell 200 during laser irradiation, thereby significantly reducing damage to the passivation layer.

[0030] The laser system 14 is used to scan the cell 200 to achieve sintering metallization, which is mainly achieved through electrochemical effects and thermal effects: laser carrier (electron) injection compensates for the electron loss on the surface of the cell 200, promotes Ag + Reduced to silver microcrystals, under the guidance of bias, the photogenerated carriers form a local high-density current, the heat generated promotes the local Ag-Si interdiffusion, and forms an extremely low-resistance AgSix alloy contact.

[0031] The present invention utilizes a dual-probe row structure to achieve regional processing of the cell. The probe row moves to the optimal grid line position based on the area scanned by the laser to energize the cell. This reduces the need for the probe row to be fixed downwardly pressed in a specific area, resulting in a voltage drop at the far end of the probe row due to lateral resistance and grid line resistance. This allows the cell surface to maintain substantially uniform voltage during laser sintering. Maintaining voltage uniformity across the cell surface means that the potential difference across the cell surface is essentially consistent. Photogenerated carriers (electrons and holes) are efficiently collected by the electrodes during the diffusion process, contributing to the formation of a stable, high-density current, improving the front-side uniformity of the cell during laser sintering, and optimizing the string resistance across the entire cell surface, thereby helping to increase the photoelectric conversion efficiency of the photovoltaic cell.

[0032] According to some embodiments of the present invention, reference Figure 2 As shown, the probe module 12 also includes: a first fixed frame 123, a second fixed frame 124, a first translation unit 125, a second translation unit 126, a first fixed plate 127, a second fixed plate 128, a first lifting unit 129, a second lifting unit 1210 and a mounting plate 1211; a first probe row 121 is provided on the first fixed frame 123, and a second probe row 122 is provided on the second fixed frame 124; the first translation unit 125 is connected to the first fixed frame 123 to drive the first probe row 121 to move horizontally, and the second translation unit 125 is connected to the first fixed frame 123 to drive the first probe row 121 to move horizontally, and the second translation unit 126 ... Unit 126 is connected to the second fixed frame 124 to drive the second probe row 122 to move horizontally; the first fixed plate 127 is provided with a first translation unit 125, and the second fixed plate 128 is provided with a second translation unit 126; the first lifting unit 129 is connected to the first fixed plate 127 to drive the first probe row 121 to move up and down, and the second lifting unit 1210 is connected to the second fixed plate 128 to drive the second probe row 122 to move up and down; the first lifting unit 129 and the second lifting unit 1210 are provided on the mounting plate 1211.

[0033] by Figure 2For example, first fixing frame 123 is used to connect first probe row 121 to first translation unit 125. The present invention does not specifically limit its shape. In some embodiments, first fixing frame 123 includes a vertical plate, a horizontal plate, and two sets of reinforcing plates fixed to the horizontal plate. The vertical plate is used to connect to first translation unit 123, and the horizontal plate is used to connect to first probe row 121. The structure of first fixing frame 124 is the same as that of first fixing frame 123.

[0034] Further Figure 2 For example, first fixing plate 127 is used to connect first translation unit 125 to first lifting unit 129. The present invention does not specifically limit its shape. In some embodiments, first fixing plate 127 also includes a vertical plate and a horizontal plate. The vertical plate is used to connect to first lifting unit 129, and the horizontal plate is used to connect to first translation unit 125. The structure of second fixing plate 128 is the same as that of first fixing plate 127.

[0035] The first translation unit 125 is used to drive the first probe row 121 to move horizontally, and the first lifting unit 129 is used to drive the first probe row 121 and the first translation unit 125 to move vertically. The second translation unit 126 is used to drive the second probe row 122 to move horizontally, and the second lifting unit 1210 is used to drive the second probe row 122 and the second translation unit 126 to move vertically. Therefore, through the cooperation of the first translation unit 125, the second translation unit 126, the first lifting unit 129, and the second lifting unit 1210, the first probe row 121 and the second probe row 122 can be moved, thereby realizing the regional processing of the battery cell 200.

[0036] According to some embodiments of the present invention, reference Figure 2 and 3 As shown, the first translation unit 125 includes a first translation motor 1251, a first driving wheel 1252, a first driven wheel 1253 and a first synchronous belt 1254; the first translation motor 1251 is vertically arranged on the first fixed plate 127; the first driving wheel 1252 and the first driven wheel 1253 are both toothed pulleys, and the first driving wheel 1252 and the first driven wheel 1253 are distributed in the horizontal direction, the first driving wheel 1252 is connected to the output shaft of the first translation motor 1251, and the first driven wheel 1253 is rotatably arranged on the first fixed plate 127; the first synchronous belt 1254 is wound around the first driving wheel 1252 and the first driven wheel 1253, and the first synchronous belt 1254 is connected to the first fixed frame 123; the second translation unit 126 has the same structure as the first translation unit 125; and / or, the first lifting unit 129 includes a ball screw transmission structure, and the second lifting unit 1210 has the same structure as the first lifting unit 129.

[0037] by Figure 3 For example, the first driving wheel 1252 is disposed above the transverse plate of the first fixed plate 127. The output shaft of the first translation motor 1251 passes downward through the first fixed plate 127 and is connected to the first driving wheel 1252. The first driven wheel 1253 is rotatably connected to the lower surface of the transverse plate of the first fixed plate 127 and is maintained at the same level as the first driving wheel 1252. When the first synchronous belt 1254 is wound around the first driving wheel 1252 and the first driven wheel 1253, the first driving wheel 1252 can drive the first driven wheel 1253 to move synchronously, thereby driving the first fixed frame 123 connected to the first synchronous belt 1254 to move left and right. The second translation unit 126 is similarly configured.

[0038] by Figure 4 For example, the first lifting unit 129 includes a first lifting motor 1291, a first ball screw 1292, a first support seat 1293, a first slide 1294, and a second sliding assembly. The first lifting motor 1291 is vertically fixed to the mounting plate 1211, and its output shaft is connected to the first ball screw 1292. The two ends of the first ball screw 1292 are rotatably mounted on the first support seat 1293. The first slide 1294 is threadedly connected to the first ball screw 1292, and the second sliding assembly is respectively distributed on both sides of the first ball screw 1292. The vertical plate of the first fixed plate 127 is fixed to the first slide 1294 and the slider of the second sliding assembly, thereby driving the first fixed plate 127 to move up and down.

[0039] In some embodiments, further reference is made to Figure 3 As shown, the first translation unit 125 also includes at least one group of first sliding components, the first sliding components include a first slide rail 1255 and a first slider 1256, the first slide rail 1255 is arranged on the first fixed plate 127 in the horizontal direction, the first slider 1256 is fixed on the first fixed frame 123, and is slidingly connected to the first slide rail 1255.

[0040] by Figure 3 For example, the first translation unit 125 includes two sets of first sliding assemblies, which are distributed vertically and located above the horizontal plate of the first fixed plate 127. The first slide rail 1255 is horizontal and fixed to the vertical plate of the first fixed plate 127. The first slider 1256 is slidably connected to the first slide rail 1255 and fixed to the vertical plate of the first fixed frame 123. The first sliding assembly improves the stability of the first fixed frame 123 during horizontal movement.

[0041] According to some embodiments of the present invention, reference Figure 5As shown, the laser system 14 includes a first laser component, a second laser component, an integration component and a galvanometer 141; the first laser component includes a first laser 142, and the wavelength of the first laser output by the first laser 142 is 780nm-1400nm; the second laser component includes a second laser 143, and the wavelength of the second laser output by the second laser 143 is 400nm-700nm; the integration component is used to combine the first laser and the second laser to the galvanometer 141.

[0042] The second laser's wavelength of 400nm-700nm indicates that the second laser is visible light, and in this case, second laser 143 is a visible light laser. Short-wavelength photons of visible light have weak penetrating power and are more likely to be absorbed by the battery surface. The first laser's wavelength of 780nm-1400nm indicates that the first laser is near-infrared light, and in this case, first laser 142 is a near-infrared laser. Long-wavelength photons of near-infrared light have strong penetrating power and are more likely to be absorbed by the battery interior.

[0043] The energy of photons corresponding to near-infrared light is approximately 0.17eV-0.93eV, so near-infrared light may only partially excite photogenerated carriers. Therefore, the present invention combines near-infrared light with visible light for laser sintering, which can generate sufficient photogenerated current at a lower voltage, reducing the requirement for voltage uniformity, thereby further improving the photoelectric conversion efficiency of photovoltaic cells.

[0044] For 0-busbar (0BB) cells, the hybrid laser sintering method offers even more significant improvements in laser sintering efficiency. Because 0BB cells lack busbars for current conduction, the current conduction distance is long and the current transmission is monotonous. This results in high contact resistance and significant voltage drop across the busbars. The hybrid laser sintering method provides sufficient photogenerated current to minimize this impact.

[0045] The galvanometer 141 is a mirror system driven by a high-speed motor, typically consisting of two galvanometer motors (one for the X-axis and one for the Y-axis). Its operating principle is that, upon receiving a control signal, the galvanometer motors rotate the mirrors to a certain angle, changing the reflection path of the laser beam and thus forming a specific scanning path on the processing surface. The galvanometer motors can complete angular deflection in microseconds, and the laser beam can scan at speeds of several meters per second, significantly reducing the metallization process time (for example, sintering a full cell grid line takes only seconds).

[0046] According to some embodiments of the present invention, continue to refer to Figure 5As shown, the first laser assembly further includes a first shaping device 144, which is arranged on the output side of the first laser 142; and / or the second laser assembly further includes a second shaping device 145, a first lens 146, and a second lens 147, which are sequentially arranged on the output side of the second shaping device 145; the laser spots output by the first shaping device 144 and the second shaping device 145 are both rectangular flat-top spots.

[0047] The first shaping device 144 is used to shape the first laser light (circular Gaussian spot) output by the first laser 142 into a rectangular flat-top spot. A circular Gaussian spot is a circular spot in which the laser energy follows a Gaussian distribution across its cross section, with the highest energy at the center and exponentially decaying toward the edges. A rectangular flat-top spot is a rectangular area in which the laser energy is evenly distributed across its cross section, with steep edges and consistent energy density at the center and edges. The uniform energy distribution of the rectangular flat-top spot prevents damage to the cell caused by excessive energy at the center of the Gaussian spot. A spot with uniform energy distribution allows the cell to withstand higher laser energy, resulting in a higher photogenerated current density and improved laser sintering. The same applies to the second shaping device 145.

[0048] Because the wavelengths of the first laser light output by first laser 142 and the second laser light output by second laser 143 are different, their focal positions differ significantly. Therefore, focus compensation is performed on the second laser light using first lens 146 and second lens 147. After being shaped by second shaping element 145, the second laser light output by second laser 143 passes through a focus compensation module comprised of first lens 146 and second lens 147 to adjust the relative positions of the lens groups, thereby aligning the focal positions of the two laser lights.

[0049] According to some embodiments of the present invention, further reference is made to Figure 5As shown, the integrated component includes a first reflector 148, a beam combiner 149 and a second reflector 1410; the first laser extends horizontally, the first reflector 148 is arranged on the output side of the first laser 142, and the angle between the plane of the first reflector 148 and the first laser is 45°; the second laser extends horizontally, the beam combiner 149 is arranged on the output side of the second laser 143, and is located on the output side of the first reflector 148, and the angle between the plane of the beam combiner 149 and the second laser is 45°, which is used to combine the first laser and the second laser; the second reflector 1410 is arranged on the output side of the beam combiner 149 and is located on the input side of the galvanometer 141, and the angle between the second reflector 1410 and the combined laser is 45°; and / or, the first shaping device 144 and the second shaping device 145 each include at least one of a diffractive optical element, a refractive optical element, a microlens array, and a spatial light modulator; and / or, the long side size of the rectangular flat-top spot is 0.5mm-3mm.

[0050] by Figure 5 For example, first laser 142 is positioned horizontally, and its output first laser beam extends horizontally. First shaper 144 is positioned to the right of first laser 142, with the plane of first shaper 144 perpendicular to the first laser beam. First reflector 148 is positioned to the right of first shaper 144, with its plane at a 45° angle to the first laser beam. This allows the first laser beam to extend vertically after being reflected by first reflector 148. First laser 143 is positioned below first laser 142, and its output second laser beam extends horizontally. Second shaper 145 is positioned to the right of second laser 143, with its plane perpendicular to the second laser beam. First lens 146 and second lens 147 are positioned sequentially to the right of second shaper 145, with first lens 146 and second lens 147 aligned. Beam combiner 149 is positioned to the right of second lens 147, with its plane at a 45° angle to the second laser beam. The beam combiner combines the second laser beam with the first laser beam and outputs it downward. The second reflecting mirror 1410 is disposed below the beam combining mirror 149 and has an angle of 45° with the combined laser beam, thereby reflecting the combined laser beam to the galvanometer mirror 141 .

[0051] A diffractive optical element (DOE) uses the principle of light diffraction to modulate the wavefront of incident laser light through micro-nanostructures (such as reliefs and phase plates), achieving complex beam shaping. Diffractive optical elements (DOEs) are etched with periodic or aperiodic microstructures (with feature sizes approaching the wavelength) on their surfaces, controlling the propagation direction and interference effects of laser light through phase delay.

[0052] A refractive optical element (ROE) is an optical component that uses the principle of refraction (e.g., lenses and prisms) to alter the direction or focus of a light beam. Refractive optical elements typically have curved surfaces or non-uniform thicknesses, such as spherical / aspherical lenses and cylindrical mirrors, and require high light transmittance.

[0053] A microlens array (MLA) refers to an array structure composed of multiple tiny lenses (with diameters ranging from a few microns to millimeters). The lens units can be arranged regularly (square, hexagonal) or randomly distributed, and the materials are mostly glass, quartz or polymer.

[0054] A spatial light modulator (SLM) is a programmable dynamic optical device that controls the local phase or amplitude through electrical signals and modulates the laser wavefront in real time.

[0055] The long side of the rectangular flat-top spot can be any value between 0.5 mm and 3 mm. For example, the long side of the rectangular flat-top spot can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm. In addition, the rectangular flat-top spot can be square or rectangular. When the rectangular flat-top spot is square, the long side of the rectangular flat-top spot is the side length of the rectangular flat-top spot.

[0056] In some embodiments, the power density of the rectangular flat-top spot is 1000 W / cm 2 -200000W / cm 2 The specific value depends on the type of slurry and the magnitude of the applied reverse voltage.

[0057] In some embodiments, reference Figure 5 As shown, the laser system 14 further includes a field lens 1411 , which is disposed on the output side of the galvanometer mirror 141 .

[0058] by Figure 5 For example, the field lens 1411 is connected to the galvanometer mirror 1410 , and the field lens 1411 is arranged below the galvanometer mirror 1410 .

[0059] Field lens 1411 is a flat-field focusing lens. It focuses the laser beam deflected by galvanometer mirror 141 onto the processing surface, while compensating for aberrations caused by angle variations, ensuring uniform spot size and energy distribution across the entire processing area. The effective working area of ​​field lens 1411 is guaranteed to be larger than the current mainstream maximum cell size of 210mm. To ensure efficiency requirements are met, the effective working area of ​​field lens 1411 is greater than 250mm×250mm.

[0060] It should be noted that the field mirror needs to undergo special designs such as achromatism to be compatible with composite wavelength processing.

[0061] According to some embodiments of the present invention, the present invention further provides a laser sintering method, referring to Figure 6-10 As shown, the method comprises: providing any of the above-mentioned laser sintering devices 100; placing a cell 200 on a conductive carrier 11, so that the grid lines on the cell 200 are arranged along the extension direction of the first probe row 121 and the second probe row 122, and applying a reverse voltage to the cell 200 through a constant voltage source; dividing the cell 200 into 2n areas along a first direction, where n is a positive integer and n≥2, and the first direction is perpendicular to the extension direction of the grid lines; moving the first probe row 121 and the second probe row 122 downward until they are in contact with the grid lines; energizing the first probe row 121 and the second probe row 122; 2. Turn off the power and control the laser system to scan the area adjacent to the area where the first probe row 121 is located from the proximal end of the first probe row 121; power on the second probe row 122, turn off the power to the first probe row 121, and control the laser system to scan the area adjacent to the area where the second probe row 122 is located from the proximal end of the second probe row 122; when the laser scanning is performed on the area adjacent to the area where the first probe row 121 / the second probe row 122 is located, control the second probe row 122 / the first probe row 121 to move to the next area; repeat the above steps until all areas are scanned.

[0062] Dividing the battery cell 200 into 2n regions along the first direction refers to virtual regions, rather than the existence of multiple independent regions on the battery cell 200 .

[0063] Controlling the laser system to scan the area adjacent to the area where the first probe row 121 is located from the proximal end of the first probe row 121 means that the laser system starts scanning from the proximal end of the first probe row 121 until the adjacent area is scanned. The reason for starting scanning from the proximal end of the first probe row 121 is that the voltage drop at the proximal end of the first probe row 121 is the smallest, and scanning the laser from the proximal end to the distal end of the first probe row 121 can reduce the impact of the voltage drop. During the laser scanning process, the slurry of the battery cell will be sintered by the laser to form high-quality silver-silicon alloy contact sites. The line resistance of the laser-processed gate line will decrease rapidly, and the voltage drop will also decrease rapidly. When the laser scans to the distal end of the probe row, the impact of the voltage drop has been greatly reduced. The same is true for controlling the laser system to scan the area adjacent to the area where the second probe row 122 is located from the proximal end of the second probe row 122.

[0064] When performing laser scanning on an area adjacent to the area where the first probe row 121 / the second probe row 122 is located, controlling the second probe row 122 / the first probe row 121 to move to the next area means controlling the second probe row 122 to move to the next area when the first probe row 121 is powered on and the laser system is performing laser scanning. When the second probe row 122 is powered on and the laser system is performing laser scanning, controlling the first probe row 121 to move to the next area can reduce the impact on the processing of the next area and help improve work efficiency.

[0065] The laser sintering method of the present invention divides the battery cell into multiple areas for processing. The probe row processes one area each time. When processing another area, the position of the probe row will be adaptively adjusted to ensure the voltage uniformity of the battery cell surface during laser sintering as much as possible.

[0066] According to some embodiments of the present invention, continue to refer to Figure 6-10 As shown, the cell 200 is divided into a first area 21, a second area 22, a third area 23 and a fourth area 24 distributed in sequence along the first direction; the first probe row 121 is moved to the second area 22, and the first probe row 121 is pressed down on the gate line, the second probe row 122 is moved to the third area 23, and the second probe row 122 is pressed down on the gate line; the first probe row 121 is powered on, the second probe row 122 is powered off, and the laser system is controlled to scan the first area 21 from the proximal end of the first probe row 121; the second probe row 122 is powered on, the first probe row 121 is powered on, the second probe row 122 is powered off, and the laser system is controlled to scan the first area 21 from the proximal end of the first probe row 121; the second probe row 122 is powered on, the first probe row 121 is powered on, the first probe row 121 is powered on, the second probe row 12 ... first probe row 121 is powered on, the second probe row 122 is powered The probe row 121 is powered off, and the laser system is controlled to scan the fourth area 24 from the proximal end of the second probe row 122, while the first probe row 121 is controlled to move to the first area 21; the first probe row 121 is powered on, and the second probe row 122 is powered off, and the laser system is controlled to scan the second area 22 from the proximal end of the first probe row 121, while the second probe row 122 is controlled to move to the fourth area 24; the second probe row 122 is powered on, and the first probe row 121 is powered off, and the laser system is controlled to scan the third area 23 from the proximal end of the second probe row 122.

[0067] by Figure 6-10 For example, the first direction is the horizontal direction in the figure, and the battery cell 200 is divided into a first area 21, a second area 22, a third area 23 and a third area 24 from left to right.

[0068] Initially, the first probe row 121 is located at position 1 of the second region 22, and the second probe row 122 is located at position 2 of the third region 23. The initial positions of the first probe row 121 and the second probe row 122 are not limited thereto. In other embodiments, in the initial state, the first probe row 121 may be located at the first region 21, and the second probe row 122 may be located at the fourth region 24.

[0069] When the first probe row 121 is powered on, Figure 7 As shown, the second probe row 122 is powered off, and the laser system scans the first area 21 from the proximal end of the first probe row 121 to the left. When the scanning of the first area 21 is completed, refer to Figure 8 As shown, the second probe row 122 is powered on, the first probe row 121 is powered off, and the laser system scans the fourth area 24 from the proximal end of the second probe row 122 to the right. At the same time, the first probe row 121 moves to position 3 of the first area 21. After the fourth area 24 is scanned, refer to Figure 9 As shown, the first probe row 121 is powered on, the second probe row 122 is powered off, and the laser system scans the second area 22 from the proximal end of the first probe row 121 to the right. At the same time, the second probe row 122 moves to position 4 of the fourth area 24. After the second area is scanned, refer to Figure 10 As shown, the second probe row 122 is powered on, the first probe row 121 is powered off, and the laser system scans the third area 23 from the proximal end of the second probe row 122 to the left. After the third area 23 is scanned, the laser system completes the scan of the entire surface of the cell 200, so that all grid lines are laser sintered.

[0070] It should be noted that Figure 6-10 What is shown is a processing method in which the battery cell is divided into 4 areas. In some other embodiments, it can also be adjusted to 6-area processing, 8-area processing, etc. according to needs.

[0071] According to some embodiments of the present application, the time required for the first probe row 121 and the second probe row 122 to move to the next area is less than or equal to the time required for the laser system to scan the current area; and / or the reverse voltage is 8V-20V.

[0072] In some embodiments, the time required for the first probe row 121 and the second probe row 122 to move to the next area can be set to 0.25s, and the time required for the laser system to scan the current area can be set to 0.3s. When the laser system scans the current area, the first probe row 121 and the second probe row 122 have already moved to the next area, and there will be no waiting time, which can further improve efficiency.

[0073] The carriers excited by the laser are minority carriers. To allow these minority carriers to form a high-density current, a reverse voltage (less than the breakdown voltage) must be applied to strengthen the internal electric field. A forward voltage enhances the diffusion current of the majority carriers, making it impossible to precisely control the current density using the laser. For example, the reverse voltage can be 8V, 10V, 12V, 14V, 16V, 18V, or 20V. A reverse voltage between 8V and 20V favors the formation of high-density currents by laser-excited carriers.

[0074] According to some embodiments of the present invention, the present invention further provides a photovoltaic cell, which is processed by any of the above-mentioned laser sintering devices or any of the above-mentioned laser sintering methods.

[0075] Example [Laser sintering device 100] It includes a conductive carrier 11, a first probe row 121, a second probe row 122, a constant voltage power supply 13 and a laser system 14. The conductive carrier 11 is made of gold-plated copper. The first probe row 121 is elastically pressed to contact the grid line with a spring force of 1N-3N. The probe diameter of the first probe row 121 is 5mm, the material is brass gold-plated, the contact resistance is 20mΩ, and the maximum current allowed to pass is 14A. The structure of the second probe row 122 is the same as that of the first probe row 121. The positive pole of the constant voltage power supply 13 is electrically connected to the conductive carrier 11, and the negative pole of the constant voltage power supply 13 is electrically connected to the first probe row 121 and the second probe row 122. The laser system includes a galvanometer 141, a first laser 142, a second laser 143, a first shaping device 144, a second shaping device 145, a first lens 146, a second lens 147, a first reflector 148, a beam combiner 149, a second reflector 1410, and a field lens 1411. The first laser 142 is positioned horizontally, and its output, a first laser beam, extends horizontally. The first shaping device 144 is positioned to the right of the first laser 142, with its plane perpendicular to the first laser beam. Both the first and second shaping devices 144 and 145 are shaping structures composed of a five-dimensional adjustable mirror frame and a DOE lens. The first reflector 148 is positioned to the right of the first shaping device 144, with its plane at a 45° angle to the first laser beam. This allows the first laser beam to extend vertically after being reflected by the first reflector 148. The first laser 143 is positioned below the first laser 142, and its output, a second laser beam, extends horizontally. The second shaping device 145 is positioned to the right of the second laser 143, with the plane of the second shaping device 145 perpendicular to the second laser. A first lens 146 and a second lens 147 are positioned sequentially to the right of the second shaping device 145, with the first lens 146 and the second lens 147 aligned. A beam combiner 149 is positioned to the right of the second lens 147, with the plane of the beam combiner 149 forming a 45° angle with the second laser beam. The beam combiner combines the second laser beam with the first laser beam and outputs the beam downward. A second reflector 1410 is positioned below the beam combiner 149, forming a 45° angle with the combined laser beam, thereby reflecting the combined laser beam toward the galvanometer 141. A field lens 1411 is connected to the galvanometer 1410 and positioned below it.

[0076] [Laser sintering method] Place the cell 200 on the conductive carrier 11, set the grid lines on the cell 200 along the extension direction of the first probe row 121 and the second probe row 122, and apply a reverse voltage of 14V to the cell 200 through a constant voltage source. Divide the cell 200 into a first area 21, a second area 22, a third area 23 and a fourth area 24 distributed in sequence along the first direction; move the first probe row 121 to the second area 22, and press the grid lines down on the first probe row 121; move the second probe row 122 to the third area 23, and press the grid lines down on the second probe row 122; power on the first probe row 121, power off the second probe row 122, and control the laser system to scan the first area 21 from the proximal end of the first probe row 121; power on the second probe row 122, and power on the first probe row 122. The needle row 121 is powered off, and the laser system is controlled to scan the fourth area 24 from the proximal end of the second probe row 122, while the first probe row 121 is controlled to move to the first area 21. The first probe row 121 is powered on, the second probe row 122 is powered off, and the laser system is controlled to scan the second area 22 from the proximal end of the first probe row 121, while the second probe row 122 is controlled to move to the fourth area 24. The second probe row 122 is powered on, the first probe row 121 is powered off, and the laser system is controlled to scan the third area 23 from the proximal end of the second probe row 122. After scanning the third area 23, the laser system has completed scanning the entire surface of the cell 200, ensuring that all grid lines are laser sintered.

[0077] Referencing the international standard IEC 60904, a photoelectric conversion efficiency meter was used to test the photoelectric conversion efficiency of the cell. The test included: placing the prepared cell on the sample stage of the meter, ensuring that the light-receiving surface of the cell was perpendicular to the light emitted by the light source, and that the cell could completely cover the detector window of the meter. The temperature of the cell was controlled at 25°C; the light source was set to a standard light source simulating sunlight with a light intensity of 1000W / m 2 , the spectrum is AM1.5; start the measuring instrument, the light source emits light to illuminate the cell, the cell generates photocurrent and photovoltage; the measuring instrument simultaneously measures the current-voltage (IV) characteristic curve of the cell under different lighting conditions, and calculates the short-circuit current (I sc ), open circuit voltage (V oc ), maximum power point current (I mp ), maximum power point voltage (V mp ). Calculate the photoelectric conversion efficiency of the cell according to the following formula: η=P max / (A×E), where P max =I mp ×V mp , A is the effective area of ​​the cell, E is the energy density of the incident light, the unit is W / m 2The measured photoelectric conversion efficiency of the cell prepared in the embodiment is 26.4%-26.5%.

[0078] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A laser sintering device, characterized in that: include: A conductive carrier for carrying battery cells; A probe module, comprising a first probe row and a second probe row, wherein the first probe row and the second probe row are both movably arranged above the conductive carrier and used for contacting the grid lines on the battery cell; A constant voltage power supply, wherein the positive electrode of the constant voltage power supply is electrically connected to the conductive carrier, and the negative electrode of the constant voltage power supply is electrically connected to the first probe row and the second probe row, and is used to apply a reverse voltage to the battery cell; A laser system is used to scan the cell while applying a reverse voltage to the cell.

2. The laser sintering device according to claim 1, characterized in that The probe module includes: a first fixing frame and a second fixing frame, wherein the first row of probes is provided on the first fixing frame and the second row of probes is provided on the second fixing frame; a first translation unit and a second translation unit, wherein the first translation unit is connected to the first fixed frame to drive the first probe row to move horizontally, and the second translation unit is connected to the second fixed frame to drive the second probe row to move horizontally; a first fixing plate and a second fixing plate, wherein the first translation unit is provided on the first fixing plate and the second translation unit is provided on the second fixing plate; A first lifting unit and a second lifting unit, wherein the first lifting unit is connected to the first fixing plate to drive the first probe row to move up and down, and the second lifting unit is connected to the second fixing plate to drive the second probe row to move up and down; A mounting plate is provided on which the first lifting unit and the second lifting unit are provided.

3. The laser sintering device according to claim 2, characterized in that The first translation unit includes a first translation motor, a first driving wheel, a first driven wheel and a first synchronous belt; The first translation motor is vertically arranged on the first fixing plate; The first driving wheel and the first driven wheel are both toothed pulleys, and the first driving wheel and the first driven wheel are distributed in the horizontal direction. The first driving wheel is connected to the output shaft of the first translation motor, and the first driven wheel is rotatably set on the first fixed plate. The first synchronous belt is wound around the first driving wheel and the first driven wheel, and the first synchronous belt is connected to the first fixing frame; The second translation unit has the same structure as the first translation unit; and / or, The first lifting unit includes a ball screw transmission structure, and the second lifting unit has the same structure as the first lifting unit.

4. The laser sintering device according to any one of claims 1 to 3, characterized in that: The laser system includes a first laser component, a second laser component, an integration component and a galvanometer; The first laser assembly includes a first laser, and the wavelength of the first laser output by the first laser is 780nm-1400nm; the second laser assembly includes a second laser, and the wavelength of the second laser output by the second laser is 400nm-700nm; the integration assembly is used to combine the first laser and the second laser to the galvanometer.

5. The laser sintering device according to claim 4, characterized in that: The first laser assembly further includes a first shaping device, which is arranged at the output side of the first laser; and / or, The second laser assembly further includes a second shaping device, a first lens, and a second lens, wherein the second shaping device, the first lens, and the second lens are sequentially arranged on the output side of the second shaping device; The laser spots output by the first shaping device and the second shaping device are both rectangular flat-top spots.

6. The laser sintering device according to claim 5, characterized in that: The integrated component includes a first reflector, a beam combiner and a second reflector; The first laser extends horizontally, the first reflector is arranged at the output side of the first laser, and the angle between the plane of the first reflector and the first laser is 45°; The second laser extends horizontally, and the beam combiner is arranged at the output side of the second laser and located at the output side of the first reflector. The angle between the plane of the beam combiner and the second laser is 45 degrees, and is used to combine the first laser and the second laser; The second reflector is arranged at the output side of the beam combiner and at the input side of the galvanometer, and the angle between the second reflector and the combined laser beam is 45°; and / or, The first shaping device and the second shaping device each include at least one of a diffractive optical element, a refractive optical element, a microlens array, and a spatial light modulator; and / or, The long side size of the rectangular flat-top light spot is 0.5 mm to 3 mm.

7. A laser sintering method, characterized in that: include: Provide a laser sintering device according to any one of claims 1 to 6; Placing a battery cell on the conductive carrier, arranging the gate lines on the battery cell along the extending direction of the first probe row and the second probe row, and applying a reverse voltage to the battery cell through the constant voltage source; Dividing the cell into 2n regions along a first direction, where n is a positive integer and n≥2, and the first direction is perpendicular to the extending direction of the gate line; Moving the first probe row and the second probe row downward until they are in contact with the gate line; The first probe row is powered on, the second probe row is powered off, and the laser system is controlled to scan an area adjacent to an area where the first probe row is located from a proximal end of the first probe row; The second probe row is powered on, the first probe row is powered off, and the laser system is controlled to scan an area adjacent to an area where the second probe row is located from a proximal end of the second probe row; When performing laser scanning on an area adjacent to the area where the first probe row / second probe row is located, controlling the second probe row / first probe row to move to the next area; Repeat the above steps until all areas are scanned.

8. The laser sintering method according to claim 7, wherein: Dividing the battery cell into a first area, a second area, a third area, and a fourth area distributed in sequence along a first direction; Move the first probe row to the second area and make the first probe row press the gate line downward, move the second probe row to the third area and make the second probe row press the gate line downward; Powering on the first probe row and powering off the second probe row, and controlling the laser system to scan the first area from the proximal end of the first probe row; Powering on the second probe row and powering off the first probe row, controlling the laser system to scan the fourth area from the proximal end of the second probe row, and controlling the first probe row to move to the first area; Powering on the first probe row and powering off the second probe row, controlling the laser system to scan the second area from the proximal end of the first probe row, and controlling the second probe row to move to the fourth area; The second probe row is powered on, the first probe row is powered off, and the laser system is controlled to scan the third area from the proximal end of the second probe row.

9. The laser sintering method according to claim 7 or 8, characterized in that: The time required for the first probe row and the second probe row to move to the next area is less than or equal to the time required for the laser system to scan the current area; and / or, The reverse voltage is 8V-20V.

10. A photovoltaic cell, characterized in that: The laser sintering device is processed by any one of claims 1 to 6 or the laser sintering method is processed by any one of claims 7 to 9.

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