Battery piece manufacturing method and battery piece
Through the laser activation process and the post-boron process, the lattice defects and mismatch problems in the formation process of the TOPCON cell are solved, and the performance and opening pressure of the cell are improved.
Patent Information
- Application Number
- CN202510331758.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-20
AI Technical Summary
The existing TOPCON cell has lattice defects and mismatch problems during the formation process, resulting in a degradation of performance.
The excess ions in the substrate are activated through the laser activation process, so that they diffuse into the substrate, forming an ordered third region, and improving lattice defects and mismatch problems. At the same time, a post-boron process is used to precipitate some doped ions to form a diffusion barrier layer to prevent doped ions from entering the third zone.
The performance of the cell is improved, the defect state density of the front-doped layer surface is reduced, the opening pressure is increased, and the parasitic absorption of the back-doped layer to the substrate is reduced, and the overall performance is improved.
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Figure CN120187139A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of photovoltaics, and particularly to a method for manufacturing a cell and a cell. Background Art
[0002] Photovoltaic power generation refers to the conversion of solar energy into electrical energy through the photovoltaic effect of semiconductors. For example, TOPCON (Tunnel Oxide Passivated Contact) cells have received increasing attention due to their good photovoltaic conversion performance.
[0003] TOPCON cells are a type of tunnel oxide passivated contact solar cell technology based on the principle of selective carriers. In TOPCON solar cells, a passivated contact structure is formed on the substrate surface to achieve selective carrier transport. The passivated contact structure includes a tunneling layer and a doped conductive layer.
[0004] Currently, it is necessary to improve the performance of the formed cells. Summary of the Invention
[0005] Embodiments of the present disclosure provide a method for manufacturing a cell and a cell, which can at least improve the performance of the formed cell.
[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a method for manufacturing a cell, including: providing a substrate, the substrate including opposite front and back surfaces, a front doping layer being formed on the front surface of the substrate, the front doping layer being doped with first-doped type ions, the front doping layer including a plurality of first regions arranged at intervals; performing laser irradiation on the first regions to perform a laser activation process, in the laser activation process, the first-doped type ions in the first regions diffuse into the substrate in a direction close to the back surface to form a plurality of third regions arranged at intervals in the substrate; removing the front doping layer to expose the surfaces of the third regions; adopting a post-boron process to form a diffusion barrier layer on the front surface, the post-boron process also being used to precipitate some of the first-doped type ions in the substrate; forming a back doping layer, the back doping layer covering the back surface, the back doping layer containing second-doped type ions; forming a front electrode, the front electrode being in electrical contact with the third regions; forming a back electrode, the back electrode being in electrical contact with the back doping layer.
[0007] In some embodiments, the process parameters of the laser activation process include: the laser power is 20w - 40w, and the laser speed is 26000mm / s - 30000mm / s.
[0008] In some embodiments, the process of forming the back doping layer includes: forming an initial back doping layer that covers the back surface; removing a portion of the initial back doping layer to form grooves arranged at intervals, where the grooves expose the surface of the substrate.
[0009] In some embodiments, before forming the back doping layer, it further includes: forming a diffusion barrier layer on the front surface, and after forming the back doping layer, it further includes: removing the diffusion barrier layer.
[0010] In some embodiments, the method of forming the diffusion barrier layer includes: the method of forming the back doping layer includes: forming an initial back doping layer that covers the back surface; removing a portion of the initial back doping layer to form grooves arranged at intervals, where the grooves expose the surface of the substrate, and the remaining initial back doping layer serves as the back doping layer, the first doping type ion is one of N-type ions or P-type ions, and the second doping type ion is the other of N-type ions or P-type ions.
[0011] In some embodiments, the method of removing the initial back doping layer includes: performing a laser opening process that uses a laser to irradiate the surface of the initial back doping layer; a wet etching process that etches the initial back doping layer irradiated by the laser opening process to form grooves arranged at intervals.
[0012] In some embodiments, the area irradiated by the laser opening process is misaligned with the position corresponding to the first region.
[0013] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a solar cell, including: a substrate, the substrate includes an opposite front surface and a back surface, the substrate includes a plurality of third regions arranged at intervals, and the third regions contain first doping type ions; a front electrode that is in electrical contact with the third regions; a back doping layer that is located on the back surface, the back doping layer includes a plurality of grooves arranged at intervals, the grooves expose the surface of the substrate, the back doping layer contains second doping type ions, the first doping type ion is one of N-type ions or P-type ions, and the second doping type ion is the other of N-type ions or P-type ions; a back electrode that is in electrical contact connection with the back doping layer.
[0014] In some embodiments, the junction depth of the third region is 0.8 μm to 1.5 μm.
[0015] In some embodiments, the grooves are misaligned with the third regions.
[0016] In some embodiments, the ratio of the area of the groove's orthographic projection on the substrate surface to the area of the back doping layer's orthographic projection on the substrate surface is 1:1 to 4:1.
[0017] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: During the formation of the front doping layer, the concentration of the first doping type ions on the front will be too high. This part of the excess ions will form interstitial atoms in the substrate, causing lattice defects. Moreover, the radii of the first doping type ions and the substrate elements do not match each other. The high concentration of the first doping type ions will also cause lattice mismatch. By activating this part of the excess ions through the laser activation process, the activated ions diffuse towards the interior of the substrate, thereby improving the lattice defect problem and the lattice mismatch problem of the substrate. Moreover, for the position of the first region, the first doping type ions all diffuse towards the interior of the substrate. As the diffusion progresses, the lattice order in the third region increases, reducing the surface defect state density of the front doping layer, thereby improving the performance of the formed solar cell. Moreover, by removing the front doping layer and only retaining the third region, local doping on the front is formed, thereby reducing the recombination of front carriers and increasing the open voltage of the solar cell.
[0018] On the other hand, through the post-boron process, some of the first doping type ions that have not advanced into the substrate 100 are precipitated, thereby improving the performance of the formed solar cell. At the same time, a diffusion barrier layer 103 is also formed. The diffusion barrier layer 103 is used to prevent doping ions from doping into the third region 102 during the subsequent formation of the back doping layer, improving the reliability of the formed solar cell and passivating the third region 102 at the same time. Description of the Drawings
[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the traditional technology, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the following described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0020] Figures 1 to 10 It is a schematic structural diagram corresponding to each step of a method for manufacturing a solar cell provided by an embodiment of the present disclosure. Detailed Embodiments
[0021] During the process of forming the front doping layer on the front side, when the surface concentration of ions of the first doping type is too high, the excess inactive ions of the first doping type exist in the substrate to form interstitial atoms, which can cause lattice defects. Moreover, due to the mismatch between the atomic radii of the ions of the first doping type and the atoms of the substrate, the high concentration of ions of the first doping type can also cause lattice mismatch. Therefore, in the surface layer of a silicon solar cell with an excessively high surface impurity concentration, these interstitial atoms, dislocations, and defects will recombine, resulting in a decrease in Isc and Uoc, and further leading to a reduction in efficiency. This surface layer is called the "dead layer".
[0022] The present disclosure activates the ions in the dead layer through a laser activation process, causing these activated ions to diffuse towards the interior of the substrate. As the diffusion progresses, the lattice orderliness in the third region increases, reducing the surface defect state density of the front doping layer, and can improve the lattice defect problem and the lattice mismatch problem of the substrate, thereby improving the performance of the formed solar cell. Moreover, by removing the front doping layer and only retaining the third region, local doping on the front side is formed, thereby reducing the recombination of front carriers and increasing the open-circuit voltage of the solar cell. On the other hand, a plurality of grooves arranged at intervals are formed on the back side, thereby reducing the contact area between the back doping layer and the back surface of the substrate, and reducing the parasitic light absorption of the back doping layer on the substrate, which can further improve the performance of the formed solar cell. On the other hand, through a post-boron process, some of the ions of the first doping type that have not advanced into the substrate are precipitated, thereby improving the performance of the formed solar cell. At the same time, a diffusion barrier layer is also formed, and the diffusion barrier layer is used to prevent doping ions from doping into the third region during the subsequent process of forming the back doping layer, improving the reliability of the formed solar cell while passivating the third region.
[0023] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise specifically and clearly defined.
[0024] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.
[0025] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can mean: there is A, there is both A and B, and there is B, these three situations. In addition, the character " / " in this text generally indicates that the objects before and after are in an "or" relationship.
[0026] In the description of the embodiments of the present disclosure, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).
[0027] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the embodiments of the present disclosure.
[0028] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can also be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.
[0029] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when a surface of a component forms or is provided with another component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.
[0030] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / above" another component, it may be "directly on" another component (i.e., on the surface of another component with no other components therebetween), or there may be another component therebetween. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is on the surface of another component, it means that no other components are therebetween.
[0031] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, the component includes components such as a layer, film, region, or plate.
[0032] The embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented for the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.
[0033] In some embodiments, the method for manufacturing a battery cell may include: providing a substrate 100, the substrate 100 including opposite front surface 110 and back surface 120, a front doping layer 101 being formed on the front surface 110 of the substrate 100, the front doping layer 101 being doped with ions of a first doping type, and the front doping layer 101 including a plurality of first regions 130 arranged at intervals.
[0034] The method for manufacturing a battery cell may further include: performing laser irradiation on the first regions 130 to carry out a laser activation process, in which the ions of the first doping type in the first regions 130 diffuse into the interior of the substrate 100 in a direction close to the back surface 120, so as to form a plurality of third regions 102 arranged at intervals in the substrate 100.
[0035] The method for manufacturing a battery cell may further include: removing the front doping layer 101 to expose the surfaces of the third regions 102.
[0036] The method for manufacturing a battery cell may further include: adopting a post-boron process to form a diffusion barrier layer 103 on the front surface 110, and the post-boron process is also used to precipitate part of the ions of the first doping type in the substrate 100.
[0037] The manufacturing method of the cell may further include: forming a back doping layer 105, the back doping layer 105 covering the back surface 120, and the back doping layer 105 containing ions of a second doping type.
[0038] The manufacturing method of the cell may further include: forming a front electrode 109, the front electrode 109 being in electrical contact with the third region 102.
[0039] The manufacturing method of the cell may further include: forming a back electrode 200, the back electrode 200 being in contact electrical connection with the back doping layer 105.
[0040] In the embodiments of the present disclosure, the redundant ions in the substrate are activated through a laser activation process, so that the activated ions diffuse towards the inside of the substrate 100. As the diffusion proceeds, the lattice orderliness in the third region 102 is improved, and the surface defect state density of the front doping layer 101 is reduced, which can improve the lattice defect problem and lattice mismatch problem of the substrate 100, thereby improving the performance of the formed cell. Moreover, by removing the front doping layer 101 and only retaining the third region 102, local doping on the front is formed, thereby reducing the recombination of front carriers and increasing the open voltage of the cell; on the other hand, through the post-boron process, some of the ions of the first doping type that have not advanced into the substrate 100 are precipitated, thereby improving the performance of the formed cell. At the same time, a diffusion barrier layer 103 is also formed, and the diffusion barrier layer 103 is used to prevent doping ions from doping into the third region 102 during the subsequent formation of the back doping layer, improving the reliability of the formed cell and passivating the third region 102 at the same time.
[0041] Reference Figure 1 , Figure 1 is a schematic structural diagram of a substrate provided by the embodiments of the present disclosure.
[0042] A substrate 100 is provided, and the substrate 100 has opposite front surface 110 and back surface 120. In some embodiments, the cell is a single-sided cell, then the front surface 110 of the substrate 100 can be used as the light-receiving surface for receiving incident light, and the back surface 120 is used as the backlight surface. In some embodiments, the cell is a double-sided cell, then both the front surface 110 and the back surface 120 of the substrate 100 can be used as the light-receiving surface and can be used to receive incident light. It can be understood that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of receiving incident light is weaker than that of the light-receiving surface for receiving incident light, so it is defined as the backlight surface.
[0043] In some embodiments, the texturing process can be performed on at least one surface of the front surface 110 or the back surface 120 of the substrate 100 to form a textured surface on at least one surface of the front surface 110 or the back surface 120 of the substrate 100. In this way, the absorption and utilization rate of the incident light by the front surface 110 and the back surface 120 of the substrate 100 can be enhanced. In some embodiments, the textured surface can be a pyramid textured surface. As a common textured surface, the pyramid textured surface not only reduces the reflectivity of the substrate 100 surface, but also forms an optical trap, enhances the absorption effect of the substrate 100 on the incident light, and improves the photoelectric conversion efficiency of the solar cell.
[0044] Specifically, if the solar cell is a single-sided solar cell, a textured surface can be formed on the light-receiving surface of the substrate 100, for example, it can be a pyramid textured surface, and the backlight surface of the substrate 100 can be a polished surface, that is, the backlight surface of the substrate 100 is flatter than the light-receiving surface. It should be noted that for a single-sided solar cell, a textured surface can also be formed on both the light-receiving surface and the backlight surface of the substrate 100.
[0045] If the solar cell is a double-sided solar cell, textured surfaces can be formed on both the light-receiving surface and the backlight surface of the substrate 100.
[0046] Reference Figure 2 , Figure 2 For forming a front doping layer on the basis of Figure 1
[0047] To form the front doping layer 101, in some embodiments, the front doping layer 101 can be formed by a boron diffusion process. By introducing a boron source on the surface of the substrate 100, part of the boron element diffuses to the surface of the substrate 100, thereby forming the front doping layer 101.
[0048] In some embodiments, during the process of forming the front doping layer 101 on the front surface 110, part of the substrate 100 on the back surface 120 is also doped with boron element, and a front doping layer 101 is also formed on the back surface 120.
[0049] In some embodiments, the thickness of the front doping layer 101 is 0.3 - 0.5 μm.
[0050] Reference Figure 3 , Figure 3 For performing a laser activation process on the basis of Figure 2
[0051] The first region 130 is irradiated with a laser to perform the laser activation process.
[0052] In some embodiments, the process parameters of the laser activation process include: the laser power is 20w to 40w, and the laser speed is 26000mm / s to 30000mm / s. By controlling the process parameters of the laser activation process to be the laser power: 20w to 40w, and the laser speed: 26000mm / s to 30000mm / s, the depth of the formed third region 102 can be controlled so that the depth of the third region 102 is within a suitable range.
[0053] The laser activation process can use red nano-laser, green nano-laser or purple nano-laser. Red nano-laser, green nano-laser or purple nano-laser all belong to nanosecond lasers, that is, the laser used in the laser activation process can be a short-pulse laser.
[0054] In some examples, the red nano-laser used in the laser activation process has a wavelength range that can be 700nm to 1500nm, for example, it can be 750nm, 800nm, 827nm, 849nm, 900nm, 920nm, 950nm, 1000nm, 1033nm, 1050nm, 1060nm, 1200nm, 1300nm, 1350nm, 1450nm or 1480nm, etc.
[0055] In some examples, the green nano-laser used in the laser activation process has a wavelength range that can be 492nm to 577nm, for example, it can be 493nm, 495nm, 496nm, 500nm, 502nm, 505nm, 508nm, 510nm, 513nm, 515nm, 516nm, 520nm, 522nm, 525nm, 528nm, 530nm, 532nm, 535nm, 538nm, 540nm, 542nm, 545nm, 548nm, 550nm, 552nm, 555nm, 558nm, 560nm, 562nm, 565nm, 568nm, 570nm, 572nm, 575nm or 578nm, etc.
[0056] In some examples, the purple laser used in the laser activation process has a wavelength range of 200 nm to 400 nm, for example, it can be 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, 245 nm, 250 nm, 255 nm, 260 nm, 265 nm, 270 nm, 275 nm, 280 nm, 285 nm, 290 nm, 295 nm, 300 nm, 305 nm, 310 nm, 315 nm, 320 nm, 325 nm, 330 nm, 335 nm, 340 nm, 345 nm, 350 nm, 355 nm, 360 nm, 365 nm, 370 nm, 375 nm, 380 nm, 385 nm, 390 nm or 395 nm, etc.
[0057] In some embodiments, the depth of the third region 102 can be 1.3 μm to 2 μm. For the third region 102, the shallower the depth of the third region 102, the more likely the third region 102 will be removed together during the subsequent removal of the front doping layer. The deeper the depth of the third region 102, the more it will affect the light absorption of the substrate. Therefore, by setting the depth of the third region 102 to be 1.3 μm to 2 μm, the finally formed third region can have an appropriate thickness.
[0058] It should be noted that the junction depth of the third region 102 at this time includes a part of the front doping layer 101 and a part diffused into the substrate 100.
[0059] Moreover, for the front doping layer 101, with the continuous doping process, a large number of doping ions will accumulate in the atomic voids. As the doping ions accumulate, it becomes increasingly difficult for the doping ions to be doped into the interior of the substrate, resulting in the junction depth being difficult to be the required junction depth. Therefore, the laser activation process can also increase the junction depth of some regions.
[0060] During the laser activation process, the first-doped type ions in the first region 130 will diffuse towards the direction close to the back surface 120, thereby increasing the doping depth at the corresponding position of the first region 130. At the same time, the doping concentration of the first region 130 basically does not change, so as to form a third region 102 with an increased junction depth and an unchanged doping concentration.
[0061] It can be understood that the doping process has been completed. However, since a dead layer will be formed on the surface layer during the doping process and the doped ions in the dead layer will be replenished to the corresponding positions in the third region, during the laser activation process, the concentration of doped ions at the corresponding position in the first region 130 is basically the same as that at the corresponding position in the second region. Therefore, through the laser activation process, while not changing the concentration of doped ions at the corresponding position in the first region 130, the junction depth of the formed third region 102 can be controlled to increase, so that both the junction depth and the concentration of doped ions in the third region 102 are within the required ranges.
[0062] It should be noted that the second region refers to the part of the front doping layer excluding the first region 130.
[0063] Reference Figure 4 , Figure 4 For removing the front doping layer on the basis of Figure 3 .
[0064] In some embodiments, the front doping layer 101 can be etched directly by means of chain hydrofluoric acid until the surface of the substrate 100 is exposed. It can be understood that since the laser activation process is carried out in the first region 130 to form the third region 102 with a deeper junction depth, during the etching process, the front doping layer 101 with a shallower junction depth will be etched clean first (that is, the front doping layer 101 in the region where the laser activation process is not carried out will be etched clean first), and then the etching is stopped to retain the third region 102. By the way of carrying out the laser activation process first and then removing the front doping layer 101, local doping can exist only in the first region 130, which can reduce the carrier recombination and improve the open voltage of the battery cell.
[0065] In some embodiments, the thickness of the removed front doping layer 101 is greater than or equal to the thickness of the front doping layer 101 where the laser activation process is not carried out, so that the front doping layer 101 can be completely removed.
[0066] In some embodiments, after removing the front doping layer 101, the thickness of the third region 102 is 0.8 μm to 1.5 μm. At this thickness, while ensuring that the substrate of the formed battery cell has good absorption capacity, the contact resistance between the electrode and the third region 102 can be reduced, and the performance of the formed battery cell can be improved.
[0067] In some embodiments, the concentration of doped ions in the third region 102 is 4E19 atom / cm 3 ~8E19 atom / cm 3 .
[0068] Reference Figure 5 , Figure 5 For forming a diffusion barrier layer on the basis of Figure 4 .
[0069] As the post-boron process proceeds, the first doping ions in the third region 102 will continue to precipitate, thereby further reducing the doping ion concentration in the third region 102, further improving the parasitic absorption ability of the third region 102, and further reducing the density of defect states at the corresponding position of the third region 102, thereby improving the photoelectric conversion efficiency of the formed solar cell.
[0070] In some embodiments, the doping ion concentration in the third region 102 formed after the post-boron process is 1E19 atom / cm 3 ~3E19 atom / cm 3 。
[0071] In some embodiments, the diffusion barrier layer 103 formed by the post-boron process can be a borosilicate glass layer.
[0072] In some embodiments, the post-boron process can also be to form an amorphous silicon layer on the surface of the substrate 100, and then oxidize the amorphous silicon layer into a borosilicate glass layer by oxidation. In the oxidized device, doping ions will continuously precipitate into the amorphous silicon layer.
[0073] The process parameters of the post-boron process can include: introducing nitrogen, and the gas flow rate of nitrogen is 8 L / min to 15 L / min, introducing oxygen, and the gas flow rate of oxygen is 2 L / min to 5 L / min, and maintaining the ambient temperature at 800 to 100 °C.
[0074] It can be understood that through the sequential boron diffusion process, laser activation process, and chain hydrofluoric acid process, a third region 102 with a deeper junction depth can be formed in the substrate 100. Then, the front doping layer 101 is removed. In this way, no steps are formed on the front surface, and at the same time, a locally doped structure is formed on the front surface. After that, through the post-boron process, the doping ions that have not been doped into the substrate 100 are precipitated, improving and enhancing the parasitic absorption ability of the third region 102, and further reducing the density of defect states at the corresponding position of the third region 102.
[0075] It should be noted that the statement that no steps are formed on the front surface means that the front surface of the substrate 100 is relatively flat.
[0076] Reference Figure 6 , Figure 6 For performing a back grinding process on the back surface on the basis of Figure 5 。
[0077] The back grinding process is performed to remove the borosilicate glass layer 104 on the back surface 120 and the front doping layer 101 formed by the boron diffusion process on the back surface 120 to expose the back surface 120 of the substrate 100 for subsequent processes.
[0078] Reference Figures 7 to 9 The method of forming the back doping layer 105 includes: forming an initial back doping layer 115 that covers the back surface 120; removing a portion of the initial back doping layer 115 to form spaced-apart grooves 140 that expose the surface of the substrate 100, and the remaining initial back doping layer 115 serves as the back doping layer 105. The first doping type ion is one of an N-type ion or a P-type ion, and the second doping type ion is the other of an N-type ion or a P-type ion.
[0079] Reference Figure 7 , Figure 7 To form the initial back doping layer on the basis of Figure 6 .
[0080] In some embodiments, a layer of amorphous silicon can be deposited on the back surface 120 first, and then the amorphous silicon layer can be converted into the initial back doping layer 115 through a phosphorus diffusion process and an annealing process.
[0081] In some other embodiments, during the phosphorus diffusion process, a phosphosilicate glass layer 106 is also formed on the surface of the initial back doping layer 115, and the initial back doping layer 115 and the phosphosilicate glass layer 106 are formed on the surface of the diffusion barrier layer 103.
[0082] In some embodiments, a tunneling oxide layer 201 can be formed before forming the amorphous silicon layer.
[0083] Reference Figure 8 and Figure 9 , Figure 8 To perform a laser dicing process on the basis of Figure 7 . Figure 9 To perform a wet etching process on the basis of Figure 8 .
[0084] In some embodiments, the method of removing the initial back doping layer 115 includes: performing a laser dicing process that uses a laser to irradiate the surface of the initial back doping layer 115; performing a wet etching process that etches the initially irradiated initial back doping layer 115 by the laser dicing process to form spaced-apart grooves 140.
[0085] It can be understood that laser ablation is first performed by laser irradiation at a preset position, so that the initial back doping layer 115 corresponding to the preset position changes, making this part of the initial back doping layer 115 easier to etch. Then, wet etching is used to process this part of the initial back doping layer 115. The etching selectivity of the initial back doping layer 115 after laser ablation is greater than that of the initial back doping layer 115 without laser ablation. Thus, during the wet etching process, a groove 140 corresponding to the preset position is formed.
[0086] In some embodiments, during the wet etching process, the phosphosilicate glass layer 106 on the back surface 120 can also be removed, the phosphosilicate glass layer 106 on the front surface 110 can be removed, the initial back doping layer 115 on the front surface 110 can be removed. Moreover, due to the phosphorus diffusion process and wet etching treatment, the passivation effect of the diffusion barrier layer 103 on the front surface 110 becomes worse, and the diffusion barrier layer 103 on the front surface 110 can also be removed. Subsequently, a new front passivation layer 107 is formed to complete the passivation step of the front surface 110.
[0087] The laser ablation can use purple laser, green laser, green-flying laser or purple-flying laser. Both purple laser and green laser belong to picosecond lasers, and both green-flying laser or purple-flying laser belong to femtosecond lasers. Picosecond lasers and femtosecond lasers are both ultrashort pulse lasers, that is, the laser used for laser ablation can be an ultrashort pulse laser.
[0088] In some examples, the wavelength range of the green laser or green-flying laser used for laser ablation can be 492nm - 577nm, such as 493nm, 495nm, 496nm, 500nm, 502nm, 505nm, 508nm, 510nm, 513nm, 515nm, 516nm, 520nm, 522nm, 525nm, 528nm, 530nm, 532nm, 535nm, 538nm, 540nm, 542nm, 545nm, 548nm, 550nm, 552nm, 555nm, 558nm, 560nm, 562nm, 565nm, 568nm, 570nm, 572nm, 575nm or 578nm, etc.
[0089] In some examples, the purple laser or purple flying laser used in the laser die-cutting process can have a wavelength range of 200 nm to 400 nm, such as 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, 245 nm, 250 nm, 255 nm, 260 nm, 265 nm, 270 nm, 275 nm, 280 nm, 285 nm, 290 nm, 295 nm, 300 nm, 305 nm, 310 nm, 315 nm, 320 nm, 325 nm, 330 nm, 335 nm, 340 nm, 345 nm, 350 nm, 355 nm, 360 nm, 365 nm, 370 nm, 375 nm, 380 nm, 385 nm, 390 nm, or 395 nm, etc.
[0090] In some embodiments, the area irradiated by the laser die-cutting process is misaligned with the position corresponding to the first region 130. It can be understood that the area irradiated by the laser die-cutting process is the part that will be removed later, and the remaining part will form the back electrode 200 in the subsequent process to extract carriers. The position corresponding to the first region 130 is the position where the front electrode 109 is located. By making the area irradiated by the laser die-cutting process misaligned with the position corresponding to the first region 130, that is, controlling the alignment of the position where the front electrode 109 is located and the position where the back electrode 200 is located, the fill factor of the formed solar cell can be improved.
[0091] Moreover, whether it is the laser die-cutting process or the laser activation process, the surface of the solar cell will be irradiated by the laser, and inevitably, the solar cell will be damaged. Therefore, setting the area irradiated by the laser die-cutting process to be misaligned with the position corresponding to the first region 130 can also avoid excessive damage at the same position in the thickness direction of the solar cell, reduce the possibility of abnormalities in the solar cell, and further improve the performance of the formed solar cell.
[0092] In some embodiments, after the groove 140 is formed, the substrate 100 is textured along the groove 140. That is to say, a pyramid morphology is formed on the surface of the substrate 100 exposed by the groove 140. By forming a pyramid morphology at the position corresponding to the groove 140, when light travels from the front surface 110 to the back surface 120 of the substrate 100, reflection occurs in the pyramid morphology region, causing the light to enter the solar cell again, thereby improving the light absorption of the solar cell, reducing light transmission, and increasing the short-circuit current of the formed solar cell.
[0093] In some embodiments, a pyramid morphology is formed on the surface of the substrate 100 in the same process step of forming the groove 140. The pyramid morphology is formed by using the process of etching the groove 140. On the one hand, the remaining back doping layer 105 can be used as a mask layer to protect the unexposed surface of the substrate 100. On the other hand, it can also reduce the process steps of forming the solar cell and thus reduce the cost of forming the solar cell.
[0094] In some embodiments, the duration of the wet etching treatment can be extended to form the pyramid morphology while forming the groove 140 in the same process step.
[0095] It should be noted that the above-mentioned boron diffusion process and post-boron process are examples given for doping with boron element, and it is not limited that only boron element can be used for doping. Corresponding structures will be formed by doping with other ions, which will not be elaborated here; similarly, the above-mentioned phosphorus diffusion process is also an example given for doping with phosphorus element.
[0096] Reference Figure 10 , Figure 10 To form the front passivation layer 107, the back passivation layer 108, the front electrode 109 and the back electrode 200 on the basis of Figure 9 .
[0097] Among them, the front passivation layer 107 and the back passivation layer 108 can be formed by a double-sided deposition method in the same process step, which can reduce the process duration of the solar cell manufacturing method and reduce the cost of the solar cell.
[0098] In the embodiments of the present disclosure, the redundant ions in the substrate are activated through a laser activation process, and these activated ions diffuse towards the inside of the substrate 100. As the diffusion proceeds, the lattice order in the third region 102 is improved, and the surface defect state density of the front doping layer 101 is reduced, which can improve the lattice defect problem and the lattice mismatch problem of the substrate 100, thereby improving the performance of the formed solar cell. Moreover, by removing the front doping layer 101 and only retaining the third region 102, local doping on the front is formed, thereby reducing the recombination of front carriers and increasing the open-circuit voltage of the solar cell. On the other hand, through the post-boron process, some of the first doping type ions that have not been pushed into the substrate 100 are precipitated, thereby improving the performance of the formed solar cell. At the same time, a diffusion barrier layer 103 is also formed. The diffusion barrier layer 103 is used to prevent doping ions from doping into the third region 102 during the subsequent formation of the back doping layer, improving the reliability of the formed solar cell while passivating the third region 102.
[0099] In some embodiments, the embodiments of the present disclosure further provide a solar cell, which can be formed by some or all of the above steps. The solar cell provided by the embodiments of the present disclosure will be described below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the above embodiments can be referred to the above embodiments, and will not be repeated hereinafter.
[0100] Reference Figure 10 , Figure 10 is a schematic structural diagram of a solar cell provided by an embodiment of the present disclosure.
[0101] In some embodiments, the solar cell may include: a substrate 100, the substrate 100 includes an opposite front surface 110 and a back surface 120, the substrate 100 includes a plurality of third regions 102 arranged at intervals, and the third regions 102 contain ions of a first doping type.
[0102] The solar cell may further include: a front electrode 109, and the front electrode 109 is in electrical contact with the third region 102.
[0103] The solar cell may further include: a back doping layer 105, the back doping layer 105 is located on the back surface 120, the back doping layer 105 includes a plurality of grooves 140 arranged at intervals, the grooves 140 expose the surface of the substrate 100, the back doping layer 105 contains ions of a second doping type, the first doping type ions are one of N-type ions or P-type ions, and the second doping type ions are the other of N-type ions or P-type ions.
[0104] The solar cell may further include: a back electrode 200, and the back electrode 200 is in contact electrical connection with the back doping layer 105.
[0105] On the one hand, the third region 102 is provided on the front surface 110, and the third region 102 is doped with ions of the first doping type to form a local doping structure on the front surface 110 of the solar cell, so as to reduce the recombination of carriers and improve the open-circuit voltage of the solar cell. On the other hand, a plurality of grooves 140 arranged at intervals are formed on the back surface 120, so as to reduce the contact area between the back doping layer 105 and the back surface 120 of the substrate 100, and thus reduce the parasitic light absorption of the back doping layer 105 to the substrate 100, and can further improve the performance of the formed solar cell.
[0106] In some embodiments, the back surface of the substrate 100 includes an alternately arranged fourth region and a fifth region, the back doping layer 105 covers the surface of the fourth region, and the grooves correspond to the fifth region. In other words, the part of the substrate 100 covered by the back doping layer 105 is called the fourth region, and the part of the substrate 100 not covered by the back doping layer 105 (i.e., the grooves) is called the fifth region.
[0107] In some embodiments, the junction depth of the third region 102 is 0.8 μm to 1.5 μm. For the third region 102, the deeper the junction depth of the third region 102, the higher the fill factor and the open voltage. However, at the same time, the deeper the junction depth of the third region 102, the more it will affect the light absorption of the cell. Therefore, setting the junction depth of the third region 102 to 0.8 μm to 1.5 μm can avoid affecting the light absorption while increasing the fill factor and the open voltage.
[0108] In some embodiments, the grooves 140 and the third region 102 are arranged in a staggered manner. On the one hand, arranging a plurality of grooves 140 in the back doping layer 105 can reduce the parasitic absorption of the back doping layer 105, thereby increasing the short-circuit current of the cell. On the other hand, arranging the grooves 140 and the third region 102 in a staggered manner can make the front electrode 109 and the back electrode 200 face each other, thereby improving the carrier collection effect and the performance of the cell.
[0109] In some embodiments, the ratio of the area of the positive projection of the groove 140 on the surface of the substrate 100 to the area of the positive projection of the back doping layer 105 on the surface of the substrate 100 is 1:1 to 4:1. In other words, the area of the positive projection of the remaining back doping layer 105 on the surface of the substrate 100 is 20% to 50% of the surface area of the substrate 100. By controlling the proportion of the area of the back doping layer 105, it is possible to reduce the parasitic light absorption of the back doping layer 105 while enabling the back doping layer 105 to have better carrier collection ability, thereby improving the performance of the cell.
[0110] The cell may further include: a front passivation layer 107, and the front passivation layer 107 is located on the front surface 110.
[0111] The cell may further include: a back passivation layer 108, and the back passivation layer 108 covers the surface of the back doping layer 105 away from the back surface 120.
[0112] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure. In practical applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.
Claims
1. A method for manufacturing a battery cell, characterized in that: include: A substrate is provided, wherein the substrate comprises a front side and a back side opposite to each other, a front side doped layer is formed on the front side of the substrate, the front side doped layer is doped with first doping type ions, and the front side doped layer comprises a plurality of first regions arranged at intervals; the first regions are irradiated with laser to perform a laser activation process, during which the first doping type ions in the first regions diffuse into the interior of the substrate in a direction close to the back side, so as to form a plurality of third regions arranged at intervals in the substrate; removing the front doped layer to expose the surface of the third region; A post-boron process is used to form a diffusion barrier layer on the front surface, and the post-boron process is also used to precipitate a portion of the first doping type ions in the substrate; forming a back doping layer, the back doping layer covering the back surface, the back doping layer containing ions of the second doping type; forming a front electrode, the front electrode being in electrical contact with the third region; A back electrode is formed, wherein the back electrode is in electrical contact with the back doped layer.
2. The method for manufacturing a battery cell according to claim 1, characterized in that: The process parameters of the laser activation process include: laser power of 20W to 40W, and laser speed of 26000mm / s to 30000mm / s.
3. The method for manufacturing a battery cell according to claim 1, characterized in that: After forming the back doping layer, the method further includes: removing the diffusion barrier layer.
4. The method for manufacturing a battery cell according to claim 1, characterized in that: The method for forming the back doping layer includes: forming an initial back doping layer, wherein the initial back doping layer covers the back surface; A portion of the initial back doping layer is removed to form grooves arranged at intervals, wherein the grooves expose the surface of the substrate, and the remaining initial back doping layer serves as a back doping layer, wherein the first doping type ions are one of N-type ions or P-type ions, and the second doping type ions are the other of N-type ions or P-type ions.
5. The method for manufacturing a battery cell according to claim 4, characterized in that: The method for removing the initial back doping layer comprises: Performing a laser mold opening process, wherein the laser mold opening process uses laser to irradiate the surface of the initial back doping layer; A wet etching process is performed to etch the initial back doping layer irradiated by the laser mold opening process to form grooves arranged at intervals.
6. The method for manufacturing a battery cell according to claim 5, characterized in that: The area irradiated by the laser mold opening process is misaligned with the position corresponding to the first area.
7. A battery cell, characterized in that: include: A substrate, wherein the substrate comprises a front side and a back side opposite to each other, and the substrate comprises a plurality of third regions arranged at intervals, wherein the third regions contain ions of a first doping type; a front electrode, the front electrode being in electrical contact with the third region; a back doping layer, the back doping layer being located at the back side, the back doping layer comprising a plurality of grooves arranged at intervals, the grooves exposing the surface of the substrate, the back doping layer containing second doping type ions, the first doping type ions being one of N-type ions or P-type ions, and the second doping type ions being the other of N-type ions or P-type ions; A back electrode is electrically connected to the back doped layer.
8. The battery cell according to claim 7, characterized in that: The junction depth of the third region is 0.8 μm to 1.5 μm.
9. The battery cell according to claim 7, characterized in that: The groove and the third area are arranged in a staggered manner.
10. The battery cell according to claim 7, characterized in that: The ratio of the area of the groove on the surface of the substrate to the area of the back doping layer on the surface of the substrate is 1:1 to 4:1.