Manufacturing method of solar cell and solar cell

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a manufacturing method of a solar cell piece and the solar cell piece, and the manufacturing method of the solar cell piece comprises the steps: providing a substrate, forming a first doping layer on the front surface of the substrate, and doping ions of a first doping type in the first doping layer; performing laser irradiation on the first region to perform a laser induction process, and diffusing the first doping type ions in the first region into the substrate along a first direction to form a third region; forming an initial second doping layer; performing a texturing process to form a second doped layer, wherein the second doped layer contains ions of a second doping type; forming a second pyramid morphology on the surface of the second doping layer; forming a front electrode; and forming a back electrode. The performance of the formed solar cell can be improved.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of photovoltaics, and in particular to a method for manufacturing a solar cell and a solar 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 tunneling oxide passivated contact solar cell technology based on the principle of selective carriers. In a TOPCON solar cell, a passivated contact structure is formed on the surface of the substrate 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 solar cells. Summary of the Invention

[0005] Embodiments of the present disclosure provide a method for manufacturing a solar cell and a solar cell, which can at least improve the performance of the solar cell.

[0006] According to some embodiments of the present disclosure, on the one hand, a method for manufacturing a solar cell is provided, including: providing a substrate, the substrate including a front surface and a back surface opposite to each other, a first doped layer being formed on the front surface of the substrate, the first doped layer being doped with first-doped type ions, the first doped layer including alternately arranged first regions and second regions; performing laser irradiation on the first regions to perform a laser-induced process, in the laser-induced process, the first-doped type ions in the first regions diffuse into the substrate along a first direction, so as to form a plurality of third regions arranged at intervals in the substrate, the first direction being the direction from the front surface to the back surface; forming an initial second doped layer, the initial second doped layer being located on the front surface and the back surface; performing a texturing process, the texturing process removing the initial second doped layer on the front surface and etching the initial second doped layer located on the back surface to form a groove on the back surface, the groove exposing the surface of the substrate, the texturing process further forming a first pyramid morphology on the surface of the substrate exposed by the groove, and the remaining initial second doped layer serving as a second doped layer, the second doped layer containing second-doped type ions; forming a second pyramid morphology on the surface of the second doped layer, the first pyramid morphology being different from the second pyramid morphology; forming a front electrode, the front electrode being in electrical contact with the third regions; and forming a back electrode, the back electrode being in electrical contact with the second doped layer.

[0007] In some embodiments, the process parameters of the laser-induced process include: the laser power is 20w to 40w, and the scanning speed is 25000mm / s - 30000mm / s.

[0008] In some embodiments, after performing the laser-induced process, it further includes: etching a part of the first doped layer, and the difference in junction depth between the corresponding positions of the first region and the second region of the remaining first doped layer is 0.8μm to 1.4μm.

[0009] In some embodiments, the process parameters for etching the first doped layer include: the etching reagent is hydrofluoric acid or nitric acid, and the etching time is 100s to 200s.

[0010] In some embodiments, before forming the initial second doped layer, it further includes: forming a diffusion barrier layer, the diffusion barrier layer is located on the surface of the first doped layer away from the front side and the back side of the substrate; performing a back grinding process, and the back grinding process removes the diffusion barrier layer located on the back side to expose the surface of the substrate.

[0011] In some embodiments, the initial second doped layer also covers the surface of the diffusion barrier layer away from the front side. During the process of forming the grooves arranged at intervals, it further includes: removing the initial second doped layer and the diffusion barrier layer located on the front side in the same process step until the surface of the first doped layer is exposed.

[0012] In some embodiments, before performing the texturing process, it further includes: performing a laser opening process on the initial second doped layer located on the back side, and the irradiated area of the laser opening process corresponds to the area removed by the texturing process.

[0013] According to some embodiments of the present disclosure, on the other hand, the present disclosure embodiments further provide a solar cell, including: a substrate, the substrate includes opposite front and back sides, and the front side of the substrate includes a third region and a fourth region extending toward the back side, the third region and the fourth region are arranged alternately, the third region and the fourth region contain ions of a first doping type, the third region and the fourth region constitute a first doped layer, and the junction depth of the third region is greater than the junction depth of the fourth region; a second doped layer, the second doped layer is located on the back side, the second doped layer includes grooves, the grooves expose the surface of the substrate, and the exposed surface of the substrate by the grooves has a first pyramid morphology, the surface of the second doped layer has a second pyramid morphology, the first pyramid morphology is different from the second pyramid morphology, and the second doped layer contains ions of a second doping type; a front electrode, the front electrode is in electrical contact with the third region; a back electrode, the back electrode is in electrical contact with the second doped layer.

[0014] In some embodiments, the difference in junction depth between the third region and the fourth region is 0.8 μm to 1.4 μm.

[0015] In some embodiments, both the third region and the fourth region are pyramid-shaped, and the height of the pyramid shape of the third region is greater than the height of the pyramid shape of the fourth region.

[0016] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: During the process of forming the first doped layer in the substrate, it will cause the formation of a dead layer on the surface of the substrate. The dead layer refers to a region rich in a large number of interstitial atoms, dislocations, and defects formed inside the substrate when the doping concentration is too high. The photogenerated carrier lifetime in these regions is extremely short and cannot effectively contribute to the photoelectric conversion process. Therefore, after forming the first doped layer, a laser-induced process is also performed on the first region. Through the laser-induced process, the first region is induced and activated, so that the doped ions diffuse into the substrate to form the third region, in order to improve the problem of lattice mismatch caused by the mismatch between the atomic radii of the doped ions and the atoms of the substrate. Moreover, during the laser-induced process, as the diffusion proceeds, the lattice order in the third region increases, reducing the surface defect state density of the first doped layer. When forming the front electrode subsequently, the contact resistance between the front electrode and the third region can be reduced, and the open-circuit voltage of the formed solar cell can be increased.

[0017] On the other hand, due to the existence of the dead layer, during the laser-induced process, the doped ions will diffuse into the substrate, and the doped ions in the dead layer will be replenished into the first region. During this process, the doped ion concentration in the third region will basically not change, so as to form a third region with an increased junction depth and an unchanged doped ion concentration;

[0018] Moreover, a first pyramid morphology is formed in the groove, and a second pyramid morphology is formed on the surface of the second doped layer, so that a differentiated textured surface can be formed on the back surface of the formed solar cell, thereby improving the compactness of the subsequent formed second passivation layer, improving the passivation ability of the second passivation layer, and increasing the open-circuit voltage of the solar cell. BRIEF 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 scale limitation; In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the following will briefly introduce the drawings required to be used in the embodiments. 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 12Structural schematic diagrams corresponding to the steps of a method for manufacturing a solar cell provided by an embodiment of the present disclosure. Detailed implementation manners

[0021] During the process of forming the first doped layer on the front surface, when the surface concentration of ions of the first doping type is too high, excess inactive ions of the first doping type exist in the substrate to form interstitial atoms, which will 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 will 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] In the embodiment of the present disclosure, after forming the first doped layer, a laser-induced process is further performed on the first region. The first region is induced and activated through the laser-induced process, so that the doped ions diffuse into the substrate to form a third region, thereby improving the problem of lattice mismatch caused by the mismatch between the atomic radii of the doped ions and the substrate. Moreover, during the laser-induced process, as the diffusion proceeds, the lattice order in the third region increases, reducing the surface defect state density of the first doped layer. When forming the front electrode subsequently, the contact resistance between the front electrode and the third region can be reduced, and the open voltage of the formed solar cell can be increased; on the other hand, due to the existence of the dead layer, during the laser-induced process, the doped ions will diffuse into the substrate, and the doped ions in the dead layer will supplement and enter the first region. During this process, the concentration of doped ions in the third region will basically not change, so as to form a third region with an increased junction depth and an unchanged doped ion concentration; moreover, a first pyramid morphology is formed in the groove, and a second pyramid morphology is formed on the surface of the second doped layer, so that a differentiated textured surface can be formed on the back surface of the formed solar cell, thereby improving the compactness of the second passivation layer formed subsequently, improving the passivation ability of the second passivation layer, and increasing the open voltage of the solar cell.

[0023] In the description of the embodiment 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 embodiment of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise specifically defined.

[0024] References to "embodiments" in this disclosure mean 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 and does not necessarily refer to the same embodiment each time, nor are they independent or alternative embodiments mutually exclusive of 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 association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can mean: the existence of A, the simultaneous existence of A and B, and the existence of B. Additionally, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[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", "lateral", "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 thus should not 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", "coupling", "fixing", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it 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 circumstances.

[0029] In the accompanying drawings corresponding to the embodiments of the present disclosure, for better understanding and description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" on the surface of the other component, or there may be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component being "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 specified, other components are not excluded, and other components may further be included. In addition, when components such as layers, films, regions, or plates are referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., on the surface of the other component with no other components therebetween), or there may be another component therebetween. In addition, when components such as layers, films, regions, or plates are "directly located on" another component, or when components such as layers, films, regions, or plates are located on the surface of another component, it means that no other components are located 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 layers, films, regions, or plates.

[0032] The following will elaborate on the embodiments of the present disclosure 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] Reference Figures 1 to 12 , Figures 1 to 12 is a schematic structural diagram corresponding to each step of a method for manufacturing a solar cell provided in an embodiment of the present disclosure.

[0034] In some embodiments, the method for fabricating a solar cell may include: providing a substrate 100, the substrate 100 including opposite front surface 110 and back surface 120, a first doped layer 101 being formed on the front surface 110 of the substrate 100, the first doped layer 101 being doped with ions of a first doping type, and the first doped layer 101 including alternately arranged first regions 111 and second regions 121.

[0035] The method for fabricating a solar cell may further include: performing laser irradiation on the first regions 111 to carry out a laser-induced process, in which, during the laser-induced process, the ions of the first doping type in the first regions 111 diffuse into the interior of the substrate 100 along a first direction to form a plurality of third regions 130 arranged at intervals in the substrate 100, the first direction being the direction from the front surface 110 pointing to the back surface 120.

[0036] The method for fabricating a solar cell may further include: forming an initial second doped layer 114, the initial second doped layer 114 being located on the front surface 110 and the back surface 120.

[0037] The method for fabricating a solar cell may further include: performing a first etching process to remove the glass layer on the front surface 110.

[0038] The method for fabricating a solar cell may further include: performing a texturing process to remove the initial second doped layer 114 on the front surface and etch the initial second doped layer 114 located on the back surface to form grooves 140 on the back surface, the grooves 140 exposing the surface of the substrate 100, and the texturing process further forming a first pyramid morphology on the surface of the substrate 100 exposed by the grooves 140, and the remaining initial second doped layer 114 serving as a second doped layer 104, the second doped layer 104 containing ions of a second doping type.

[0039] The method for fabricating a solar cell may further include: forming a second pyramid morphology on the surface of the second doped layer 104, the first pyramid morphology being different from the second pyramid morphology.

[0040] The method for fabricating a solar cell may further include: forming a front electrode 108, the front electrode 108 being in electrical contact with the third regions 130.

[0041] The method for fabricating a solar cell may further include: forming a back electrode 109, the back electrode 109 being in electrical contact with the second doped layer 104.

[0042] In the embodiment of the present disclosure, after forming the first doped layer 101, a laser-induced process is also performed on the first region 111. The first region 111 is induced and activated through the laser-induced process, so that the doped ions diffuse into the substrate 100 to form the third region 130, thereby improving the problem of lattice mismatch caused by the mismatch between the atomic radii of the doped ions and the atoms of the substrate 100. Moreover, during the laser-induced process, as the diffusion proceeds, the lattice order in the third region 130 is improved, and the surface defect state density of the first doped layer 101 is reduced. When forming the front electrode 108 subsequently, the contact resistance between the front electrode 108 and the third region 130 can be reduced, and the open voltage of the formed solar cell can be increased; on the other hand, due to the existence of the dead layer, during the laser-induced process, the doped ions will diffuse into the substrate 100, and the doped ions in the dead layer will be replenished into the first region 111. During this process, the concentration of the doped ions in the third region 130 will basically not change, so as to form the third region 130 with an increased junction depth and an unchanged doped ion concentration; moreover, a first pyramid morphology is formed in the groove 140, and a second pyramid morphology is formed on the surface of the second doped layer 104, so that a differential textured surface can be formed on the back surface of the formed solar cell, thereby improving the compactness of the second passivation layer 107 formed subsequently, improving the passivation ability of the second passivation layer 107, and increasing the open voltage of the solar cell.

[0043] Reference Figure 1 , Figure 1 is a schematic structural diagram of a substrate provided by an embodiment of the present disclosure.

[0044] A substrate 100 is provided, and the substrate 100 has opposite front 110 and back 120 surfaces. In some embodiments, if the solar cell is a single-sided cell, the front 110 surface of the substrate 100 can be used as the light-receiving surface for receiving incident light, and the back 120 surface can be used as the backlight surface. In some embodiments, if the solar cell is a double-sided cell, both the front 110 and back 120 surfaces of the substrate 100 can be used as the light-receiving surfaces and can be used to receive incident light. It can be understood that the backlight surface referred to in the embodiment 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, so it is defined as the backlight surface.

[0045] In some embodiments, a texturing process can be performed on at least one of the front 110 or back 120 surfaces of the substrate 100 to form a textured surface on at least one of the front 110 or back 120 surfaces of the substrate 100. In this way, the absorption and utilization rate of incident light by the front 110 and back 120 surfaces 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 surface of the substrate 100, but also can form a light trap, enhancing the absorption effect of the substrate 100 on incident light and improving the photoelectric conversion efficiency of the solar cell.

[0046] Specifically, if the cell is a single-sided cell, a textured surface can be formed on the light-receiving surface of the substrate 100, for example, 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 cell, a textured surface can also be formed on both the light-receiving surface and the backlight surface of the substrate 100.

[0047] If the cell is a double-sided cell, a textured surface can be formed on both the light-receiving surface and the backlight surface of the substrate 100.

[0048] Reference Figure 2 , Figure 2 For forming the first doping layer on the basis of Figure 1 the above.

[0049] The first doping layer 101 is formed. In some embodiments, the first 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 first doping layer 101.

[0050] In some other embodiments, the boron diffusion process can also be to first form a layer of amorphous silicon on the surface of the substrate, and then convert the amorphous silicon layer into the first doping layer by doping.

[0051] In some embodiments, during the process of forming the first doping layer 101 on the front surface 110, part of the substrate 100 on the back surface 120 will also be doped with boron elements, and the first doping layer 101 will also be formed on the back surface 120.

[0052] Reference Figure 3 , Figure 3 For performing a laser-induced process on the basis of Figure 2 the above.

[0053] A laser-induced process is performed on the first region 111. In some embodiments, the process parameters of the laser-induced process include: the laser power is 20W - 40W, and the scanning speed is 25000mm / s - 30000mm / s. By controlling the laser power and scanning speed of the laser-induced process, the formed third region 130 can be at an appropriate depth.

[0054] The laser-induced 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 nano-second laser, that is, the laser used in the first laser treatment can be a short-pulse laser.

[0055] In some examples, the red laser used in the laser-induced process has a wavelength range of 700 nm to 1500 nm, for example, it can be 750 nm, 800 nm, 827 nm, 849 nm, 900 nm, 920 nm, 950 nm, 1000 nm, 1033 nm, 1050 nm, 1060 nm, 1200 nm, 1300 nm, 1350 nm, 1450 nm, 1480 nm, etc.

[0056] In some examples, the green laser used in the laser-induced process has a wavelength range of 492 nm to 577 nm, for example, it can be 493 nm, 495 nm, 496 nm, 500 nm, 502 nm, 505 nm, 508 nm, 510 nm, 513 nm, 515 nm, 516 nm, 520 nm, 522 nm, 525 nm, 528 nm, 530 nm, 532 nm, 535 nm, 538 nm, 540 nm, 542 nm, 545 nm, 548 nm, 550 nm, 552 nm, 555 nm, 558 nm, 560 nm, 562 nm, 565 nm, 568 nm, 570 nm, 572 nm, 575 nm, 578 nm, etc.

[0057] In some examples, the purple laser used in the laser-induced 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, 395 nm, etc.

[0058] During the laser-induced process, the ions of the first doping type in the first region 111 will diffuse into the substrate 100 along the first direction to form the third region 130. By controlling the diffusion of the ions of the first doping type towards the substrate 100, the doping depth of the first doping layer 101 at the position of the first region 111 is increased, which is convenient for the subsequent formation of the front electrode 108. By contacting the electrode with the third region 130 with a deeper junction depth, the recombination of the first doping layer 101 is reduced, and the open voltage of the formed solar cell is improved.

[0059] In some embodiments, the area of the orthographic projection of the first region 111 on the surface of the substrate 100 is 5% to 50% of the area of the orthographic projection of the first doping layer 101 on the surface of the substrate.

[0060] In some embodiments, after the laser-induced process, it further includes: etching a part of the first doping layer 101, and the difference in the junction depth between the corresponding positions of the first region 111 and the second region 121 of the remaining first doping layer 101 is 0.8 μm to 1.4 μm, such as 0.9 μm, 1 μm, 1.2 μm or 1.3 μm, etc.

[0061] For the first doping layer 101, if the thickness of the first doping layer 101 is too large, it will lead to a relatively large thickness of the formed dead layer. Moreover, the increase in the thickness of the first doping layer 101 will cause the light absorption ability of the substrate 100 to weaken. Therefore, after the laser-induced process, a part of the first doping layer 101 will be etched. For the first region 111 and the second region 121, the smaller the difference in the junction depth between the first region 111 and the second region 121, on the one hand, it indicates that the effect of activating the dead layer by the laser-induced process is poor. On the other hand, during the process of etching the first doping layer 101, it may cause both the first region 111 and the second region 121 to be etched. And if the junction depth of the first region 111 and the second region 121 is too large, it will lead to an excessive depth of the third region 130, which will affect the light absorption ability of the substrate 100.

[0062] In some embodiments, a part of the first doping layer 101 can be etched by wet etching. It can be understood that for the first doping layer 101, although the doping ion concentration in the first region 111 basically remains unchanged, the lattice order in the first region 111 is improved, resulting in different etching selectivity ratios between the first region 111 and the second region 121. By utilizing this characteristic, the difference in the junction depth between the corresponding positions of the first region 111 and the second region 121 of the first doping layer 101 can be adjusted, so that the difference in the junction depth between the corresponding positions of the first region 111 and the second region 121 of the remaining first doping layer 101 can be 0.8 μm to 1.4 μm.

[0063] In some embodiments, the process parameters for etching the first doping layer 101 include: the etching reagent is hydrofluoric acid or nitric acid, and the etching time is 100 s to 200 s. By controlling the etching time between 100 s and 200 s, the phenomenon of over-etching can be avoided during the process of etching the first doping layer 101. Similarly, controlling the etching time between 100 s and 200 s can also control the thickness of the remaining first doping layer 101, thereby further controlling the difference in the junction depth between the corresponding positions of the first region 111 and the second region 121 of the first doping layer 101.

[0064] In some embodiments, the volume percentage of hydrofluoric acid in the hydrofluoric acid solution used for etching the first doped layer 101 may be 10% to 40%, and the volume percentage of water may be 60% to 90%.

[0065] Reference Figure 4 and Figure 5 , before forming the initial second doped layer 114, it further includes: forming a diffusion barrier layer 102, the diffusion barrier layer 102 is located on the surface of the first doped layer 101 away from the front surface 110 and the back surface 120 of the substrate; performing a back grinding process, the back grinding process removes the diffusion barrier layer 102 located on the back surface 120, exposing the surface of the substrate 100. By forming the diffusion barrier layer 102 on the front surface 110 first, it is possible to avoid contaminating the first doped layer 101 on the front surface 110 during subsequent doping of the back surface 120, and then removing the first doped layer 101 and the borosilicate glass layer formed on the back surface 120 during the previous process through the back grinding process to expose the back surface 120 of the substrate, thereby facilitating the formation of the second doped layer 104.

[0066] Reference Figure 4 , Figure 4 To form a diffusion barrier layer on the basis of Figure 3 .

[0067] In some embodiments, the method for forming the diffusion barrier layer 102 may include: adopting a post-boron process to form the diffusion barrier layer 102 on the front surface 110. The post-boron process may be to form an oxide layer by oxidizing a part of the first doped layer 101. On the one hand, the diffusion barrier layer 102 can be formed through the post-boron process to passivate the third region 130 while avoiding affecting the third region 130, thereby improving the performance of the formed solar cell; on the other hand, the doping source on the surface is precipitated through the post-boron process, thereby further improving the performance of the formed solar cell.

[0068] As the post-boron process progresses, the doped ions in the first doped layer 101 and the doped ions in the third region 130 will continue to precipitate, which will simultaneously reduce the doped ions in the first doped layer 101 and the third region 130. Moreover, due to the laser-induced process at the corresponding position of the third region 130, the doped ions in the dead layer at the corresponding position of the third region 130 diffuse towards the substrate 100, while the dead layer at the corresponding position of the fourth region remains unchanged, resulting in a higher doping concentration and faster precipitation at the dead layer position of the fourth region. Thus, as the post-boron process progresses, the doping ion concentration in the fourth region will be less than the doping ion concentration in the third region 130.

[0069] In some embodiments, the doping ion concentration in the third region 130 is 1E19 atom / cm 3 ~2E19 atom / cm 3, the doping ion concentration at the corresponding position in the fourth region is 5E18 atom / cm 3 ~8E18 atom / cm 3 .

[0070] In some embodiments, the diffusion barrier layer 102 formed by the post-boron process may be a borosilicate glass layer.

[0071] Reference Figure 5 , Figure 5 For performing a back grinding process on the back surface based on Figure 4 .

[0072] By means of the back grinding process, the diffusion barrier layer 102 and the first doping layer 101 located on the back surface 120 are removed, so as to expose the back surface 120 of the substrate 100 to facilitate the formation of the second doping layer 104 on the back surface 120.

[0073] Reference Figure 6 , Figure 6 For forming an initial second doping layer based on Figure 5 .

[0074] In some embodiments, an amorphous silicon layer may be first deposited on the back surface 120, and then the amorphous silicon layer is converted into the initial second doping layer 114 through a diffusion process and an annealing process. Meanwhile, a glass layer 105 is formed on the surface of the initial second doping layer 114 during the formation of the initial second doping layer 114.

[0075] During the process of depositing a polysilicon layer on the back surface 120, a polysilicon layer is also formed on the front surface 110. Similarly, during the formation of the initial second doping layer 114 on the back surface 120, a second initial doping layer 114 is formed on the front surface, and similarly, a glass layer 105 is also formed on the front surface 110 during the diffusion process.

[0076] It should be noted that the glass layer 105 here may be a phosphosilicate glass layer.

[0077] In some embodiments, a tunneling oxide layer 200 is also formed before the formation of the initial second doping layer 114. The tunneling oxide layer may be a single layer of silicon dioxide or titanium oxide or a stack of multiple layers.

[0078] It should be noted that 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 For performing a laser die opening process based on Figure 6 .

[0080] Before the texturing process, it also includes: performing laser scribing on the initial second doping layer 114 located on the back. The area irradiated by the laser scribing corresponds to the area removed by the texturing process. On the one hand, the laser scribing modifies this part of the initial second doping layer 114 that needs to be removed, making this part of the initial second doping layer 114 easier to remove and facilitating the subsequent etching process.

[0081] The laser scribing 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 ultra-short pulse lasers, that is, the laser used for the second laser treatment can be an ultra-short pulse laser.

[0082] In some examples, the wavelength range of the green laser or green-flying laser used for the laser scribing can be 492 nm to 577 nm, for example, it can be 493 nm, 495 nm, 496 nm, 500 nm, 502 nm, 505 nm, 508 nm, 510 nm, 513 nm, 515 nm, 516 nm, 520 nm, 522 nm, 525 nm, 528 nm, 530 nm, 532 nm, 535 nm, 538 nm, 540 nm, 542 nm, 545 nm, 548 nm, 550 nm, 552 nm, 555 nm, 558 nm, 560 nm, 562 nm, 565 nm, 568 nm, 570 nm, 572 nm, 575 nm or 578 nm, etc.

[0083] In some examples, the wavelength range of the purple laser or purple-flying laser used for the laser scribing can be 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.

[0084] In some embodiments, the area irradiated by the laser die-cutting process is misaligned with the position corresponding to the first region 111. 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 109 in the subsequent process to extract carriers. The position corresponding to the first region 111 is the position where the front electrode 108 is located. By making the area irradiated by the laser die-cutting process misaligned with the position corresponding to the first region 111, that is, controlling the positions of the front electrode 108 and the back electrode 109 to be directly opposite, the fill factor of the formed solar cell can be improved.

[0085] 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, which will inevitably cause damage to the solar cell. Therefore, setting the area irradiated by the laser die-cutting process to be misaligned with the position corresponding to the first region 111 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.

[0086] Reference Figure 8 , Figure 8 For the first etching process on the basis of Figure 7 .

[0087] The first etching process is used to remove the glass layer 105 located on the front surface 110. The glass layer 105 on the front surface 110 can be removed by directly immersing the front surface of the solar cell in the etching tank.

[0088] Reference Figure 9 , Figure 9 For the texturing process on the basis of Figure 8 .

[0089] The texturing process is used to remove the initial second doped layer 114 irradiated by the laser die-cutting process to form grooves 140, and a pyramid morphology is formed on the surface of the substrate 100 exposed in the grooves 140. Using the structure of the pyramid morphology can cause light to be reflected in the pyramid morphology region when the light is transmitted from the front surface 110 of the substrate 100 to the back surface 120, so that the light re-enters the interior of the solar cell, thereby improving the light absorption of the solar cell, reducing the light passing through, and increasing the short-circuit current of the formed solar cell.

[0090] By the method of first depositing the whole surface and then etching, the entire production process can be simplified and it is convenient to control the position of the grooves 140. On the other hand, by forming a plurality of spaced grooves 140 on the back surface 120, the contact area between the second doped layer 104 and the substrate 100 can be reduced, thereby reducing the parasitic light absorption of the second doped layer 104 and reducing the Auger recombination of the second doped layer 104, and further improving the performance of the formed solar cell.

[0091] It can be understood that due to the laser die - sinking treatment, the laser - irradiated part is modified, and this part of the irradiated glass layer 105 becomes easy to etch. Therefore, in the texturing process, the part of the back - side glass layer 105 that has not been irradiated by the laser has not been completely removed, while the initial second doping layer 114 at the corresponding position of the irradiated glass layer 105 has been etched completely.

[0092] Meanwhile, the texturing process is also used to remove the initial second doping layer 114 on the front side. It can be understood that the glass layer 105 on the front side has been removed in the first etching process. Therefore, in the texturing process, the initial second doping layer 114 on the front side 110 is exposed and is etched and removed together with the progress of the texturing process.

[0093] Reference Figure 10 , Figure 10 For performing the second etching process on the basis of Figure 9 .

[0094] The second etching process is used to completely remove the diffusion barrier layer 102 located on the front side 110 to expose the surface of the first doping layer 101. For the diffusion barrier layer 102, due to the etching process and the texturing process in the above - mentioned process steps, the passivation effect of the diffusion barrier layer 102 becomes poor. Therefore, this layer of diffusion barrier layer 102 is removed by etching, and then a passivation layer is formed again, which can improve the performance of the formed solar cell.

[0095] In some embodiments, the initial second doping layer 114 also covers the surface of the diffusion barrier layer 102 away from the front side 110. In the process of forming the spaced - apart grooves 140, it also includes: removing the initial second doping layer 114 and the diffusion barrier layer 102 located on the front side 110 in the same process step until the surface of the first doping layer 101 is exposed. In other words, that is, integrating the first etching process, the texturing process, and the second etching process in the same process step, thereby reducing the process steps of the manufacturing method of the solar cell and reducing the cost of forming the solar cell.

[0096] In some embodiments, the first etching process, the texturing process, and the second etching process can be completed by means of chain - type hydrofluoric acid and chain - type nitric acid.

[0097] Reference Figure 11 , Figure 11 For performing the second texturing process on the basis of Figure 10 .

[0098] In some embodiments, a second texturing process may be performed after the second etching process. The second texturing process may etch the surface of the first doped layer to form different pyramids in the first region 111 and the non-laser-irradiated region 121 of the first doped layer. In this way, different pyramids can be formed on the first doped layer 101, thereby improving the passivation performance of the subsequently formed first passivation layer.

[0099] It can be understood that due to the difference in lattice order, the etching rates of the second texturing process for the corresponding positions of the first region 111 and the non-laser-irradiated region 121 are different, which will result in different pyramids at different positions of the first doped layer 101. The size of the pyramids at the corresponding position of the third region 130 is larger. By setting different pyramids at different positions of the first doped layer 101, a differentiated textured surface can also be formed on the front surface of the solar cell, thereby improving the compactness of the first passivation layer 106, improving the passivation performance of the first passivation layer 106, and improving the open-circuit voltage of the solar cell.

[0100] In some embodiments, the glass layer 105 located on the back surface may be removed in the second texturing process. Moreover, since the groove 140 is formed on the back surface, the second texturing process will also etch the substrate exposed by the groove 140 to further texture the substrate exposed by the groove 140, further expanding the difference between the textured surface at the corresponding position of the back surface groove 140 and the textured surface at the corresponding position of the second doped layer 104, and further improving the compactness of the subsequently formed second passivation layer 107.

[0101] It should be noted that the boron diffusion process and the post-boron process in the above embodiments are examples of 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 diffusion process is also an example of doping with phosphorus element.

[0102] It can be understood that when forming the front surface 110 structure and the back surface 120 structure in the embodiments of the present disclosure, the back surface 120 structure is not processed when forming the front surface 110 structure, and the film layer required to be retained on the front surface 110 is not affected when forming the back surface 120 structure. That is to say, the entire front surface 110 is used as the process window when forming the front surface 110 structure, and the entire back surface 120 is used as the process window when forming the back surface 120 structure, thereby increasing the area of the process window and reducing the difficulty of the entire manufacturing process.

[0103] Reference Figure 12 , Figure 12 For forming the first passivation layer, the second passivation layer, the front electrode, and the back electrode on the basis of Figure 11 .

[0104] The first passivation layer 106 covers the surface of the first doped layer away from the front side, and the second passivation layer 107 covers the surface of the second doped layer 104 away from the back side.

[0105] Among them, the first passivation layer 106 and the second passivation layer 107 can be formed by a double-sided deposition method in the same process step, which can reduce the process duration of the method for manufacturing the battery cell and reduce the cost of the battery cell.

[0106] In the embodiment of the present disclosure, after forming the first doped layer 101, a laser-induced process is further performed on the first region 111. The first region 111 is induced and activated through the laser-induced process, so that the doped ions diffuse into the substrate 100 to form the third region 130, so as to improve the problem of lattice mismatch caused by the mismatch between the atomic radii of the doped ions and the atoms of the substrate 100. Moreover, during the laser-induced process, as the diffusion proceeds, the lattice order in the third region 130 is improved, and the surface defect state density of the first doped layer 101 is reduced. When forming the front electrode 108 subsequently, the contact resistance between the front electrode 108 and the third region 130 can be reduced, and the open voltage of the formed solar cell can be increased; on the other hand, due to the existence of the dead layer, during the laser-induced process, the doped ions will diffuse into the substrate 100, and the doped ions in the dead layer will supplement and enter the first region 111. During this process, the doped ion concentration in the third region 130 will basically not change, so as to form a third region 130 with an increased junction depth and an unchanged doped ion concentration; moreover, a first pyramid morphology is formed in the groove 140, and a second pyramid morphology is formed on the surface of the second doped layer 104, so that a differentiated textured surface can be formed on the back surface of the formed solar cell, and thus the compactness of the second passivation layer 107 can be formed subsequently, so as to improve the passivation ability of the second passivation layer 107 and increase the open voltage of the solar cell.

[0107] In some embodiments, the embodiment of the present disclosure further provides a battery cell. The battery cell can be formed by some or all of the above steps. The battery cell provided by the embodiment 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 below.

[0108] Refer to Figure 12 , Figure 12 which is a schematic structural diagram of a solar cell provided by an embodiment of the present disclosure.

[0109] In some embodiments, a solar cell may include: a substrate 100, the substrate 100 includes opposite front surface 110 and back surface 120, and the front surface 110 of the substrate 100 includes a third region 130 and a fourth region extending toward the back surface 120. The third region 130 and the fourth region are arranged alternately. The third region 130 and the fourth region contain ions of a first doping type. The third region 130 and the fourth region constitute a first doping layer 101, and the junction depth of the third region 130 is greater than the junction depth of the fourth region.

[0110] The solar cell may further include: a second doping layer 104, the second doping layer 104 is located on the back surface 120. The second doping layer 104 includes a groove 140. The groove 140 exposes the surface of the substrate 100, and the surface of the substrate 100 exposed by the groove 140 has a first pyramid morphology. The surface of the second doping layer 104 has a second pyramid morphology. The first pyramid morphology is different from the second pyramid morphology. The second doping layer 104 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.

[0111] The solar cell may further include: a front electrode 108, the front electrode 108 is in electrical contact with the third region 130.

[0112] The solar cell may further include: a back electrode 109, the back electrode 109 is in electrical contact with the second doping layer 104.

[0113] By providing the third region 130 on the front surface 110 of the solar cell, the surface defect state density at the third region 130 is lower and the doping concentration is lower. Therefore, the carrier recombination at the third region 130 is also lower, which can improve the reliability of the direct contact between the front electrode 108 and the third region 130, and further improve the open-circuit voltage of the solar cell. Moreover, by providing the first pyramid morphology and the second pyramid morphology on the back surface of the solar cell to form a differential texture, the compactness of the second passivation layer 107 can be improved to improve the passivation ability of the second passivation layer 107 and improve the open voltage of the solar cell.

[0114] In some embodiments, the difference between the junction depth of the third region 130 and the junction depth of the fourth region is 0.8 μm to 1.4 μm.

[0115] By controlling the difference in junction depth between the third region 130 and the fourth region to be 0.8 μm to 1.4 μm, on the one hand, it is convenient for the formation of the process and avoids etching the corresponding position of the fourth region clean during the process of removing part of the first doping layer 101. On the other hand, when a pyramid structure is formed on the front surface 110 of the substrate 100, the conformal coverage effect of the first doping layer 101 can also be controlled, that is, the integrity of the pyramid morphology of the first doping layer 101 is controlled, thereby improving the performance of the solar cell.

[0116] In some embodiments, both the third region 130 and the fourth region are pyramid-shaped, and the height of the pyramid shape of the third region 130 is greater than the height of the pyramid shape of the fourth region. By adjusting the heights of the pyramid shapes of both the third region 130 and the fourth region to form a differential texture, the differential texture can be used to reduce light transmission and increase the light reflectivity, thereby increasing the short-circuit current and the open-circuit voltage.

[0117] In some embodiments, the height of the pyramid shape of the third region 130 can be 2 to 3 μm, such as 2.1 μm, 2.3 μm, 2.5 μm, 2.6 μm, or 2.8 μm, etc., and the height of the pyramid shape of the fourth region can be 1.7 μm to 2.5 μm, such as 1.9 μm, 2 μm, 2.2 μm, or 2.4 μm, etc. On the premise that the height of the pyramid shape of the third region 130 can be 2 to 3 μm and the height of the pyramid shape of the fourth region can be 1.7 μm to 2.5 μm, it is also convenient for the subsequent deposition of the second passivation layer 107, can improve the compactness of the second passivation layer 107, and thereby improve the performance of the solar cell.

[0118] In some embodiments, the width of the bottom of the pyramid shape of the third region 130 is also greater than the width of the bottom of the pyramid shape of the fourth region, that is to say, the overall size of the pyramid shape of the third region 130 is greater than the size of the pyramid shape of the fourth region. In other words, the roughness of the corresponding position of the third region 130 is greater than the roughness of the corresponding position of the fourth region.

[0119] In some embodiments, the area of the orthographic projection of the third region 130 on the surface of the substrate 100 can be 5% to 50% of the area of the substrate 100. By controlling the area of the third region 130, the area of local doping can be controlled, thereby further improving the performance of the solar cell.

[0120] In some embodiments, the second doping layer 104 includes a plurality of grooves 140 arranged at intervals, and the grooves 140 are arranged in a staggered manner with respect to the third region 130. On the one hand, arranging a plurality of grooves 140 in the second doping layer 104 can reduce the parasitic absorption of the second doping layer 104, thereby increasing the short-circuit current of the solar cell. On the other hand, arranging the grooves 140 in a staggered manner with respect to the third region 130 can make the front electrode 108 face the back electrode 109, thereby improving the carrier collection effect and the performance of the solar cell.

[0121] In some embodiments, the area of the orthographic projection of the second doping layer 104 on the surface of the substrate 100 is 5% to 30% of the surface area of the substrate 100. By controlling the proportion of the area of the second doping layer 104, the second doping layer 104 can have a good ability to collect carriers while reducing the parasitic light absorption of the second doping layer 104, thereby improving the performance of the solar cell.

[0122] The solar cell may further include: a first passivation layer 106, and the first passivation layer 106 covers the surface of the first doping layer 101 away from the front surface 110.

[0123] The solar cell may further include: a second passivation layer 107, and the second passivation layer 107 covers the surface of the second doping layer 104 away from the back surface 120.

[0124] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual 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 modifications and changes 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 determined by the scope defined by the claims.

Claims

1. A method for manufacturing a solar cell, characterized in that: include: Providing a substrate, the substrate comprising a front side and a back side opposite to each other, a first doping layer formed on the front side of the substrate, the first doping layer being doped with first doping type ions, and the first doping layer comprising first regions and second regions alternately arranged; irradiating the first region with laser light to perform a laser induction process, wherein the first doping type ions in the first region diffuse into the interior of the substrate along a first direction to form a plurality of third regions arranged at intervals in the substrate, wherein the first direction is a direction from the front surface to the back surface; forming an initial second doping layer, wherein the initial second doping layer is located on the front side and the back side; Performing a texturing process, wherein the texturing process removes the initial second doping layer on the front side and etches the initial second doping layer on the back side to form a groove on the back side, wherein the groove exposes the surface of the substrate, and the texturing process further forms a first pyramid morphology on the surface of the substrate exposed by the groove, and the remaining initial second doping layer serves as a second doping layer, wherein the second doping layer contains second doping type ions; forming a second pyramid morphology on the surface of the second doped layer, wherein the first pyramid morphology is different from the second pyramid morphology; forming a front electrode, the front electrode being in electrical contact with the third region; A back electrode is formed, the back electrode being in electrical contact with the second doped layer.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: The process parameters of the laser induction process include: laser power of 20W-40W, and scanning speed of 25000mm / s-30000mm / s.

3. The method for manufacturing a solar cell according to claim 1, characterized in that: After the laser induction process is performed, the method further includes etching a portion of the first doped layer, and the difference between the junction depths of the first region corresponding to the first area and the second region corresponding to the first doped layer is 0.8 μm to 1.4 μm.

4. The method for manufacturing a solar cell according to claim 3, characterized in that: The process parameters for etching the first doping layer include: the etching agent is hydrofluoric acid or nitric acid, and the etching time is 100s to 200s.

5. The method for manufacturing a solar cell according to claim 1, characterized in that: Before forming the initial second doping layer, the method further comprises: forming a diffusion barrier layer, wherein the diffusion barrier layer is located on a surface of the first doped layer away from the front surface and on a back surface of the substrate; A back polishing process is performed to remove the diffusion barrier layer on the back side to expose the substrate surface.

6. The method for manufacturing a solar cell according to claim 5, characterized in that: The initial second doping layer also covers the surface of the diffusion barrier layer away from the front surface, and the process of forming the grooves arranged at intervals further includes: The initial second doping layer and the diffusion barrier layer on the front side are removed in the same process step until the surface of the first doping layer is exposed.

7. The method for manufacturing a solar cell according to claim 1, characterized in that: Before the texturing process is performed, the method further includes: performing a laser mold opening process on the initial second doping layer located on the back side, wherein the area irradiated by the laser mold opening process corresponds to the area removed by the texturing process.

8. A solar cell, characterized in that: include: A substrate, wherein the substrate comprises a front side and a back side opposite to each other, and the front side of the substrate comprises a third region and a fourth region extending toward the back side, the third region and the fourth region are arranged alternately, the third region and the fourth region contain ions of a first doping type, the third region and the fourth region constitute a first doping layer, and the junction depth of the third region is greater than the junction depth of the fourth region; a second doping layer, the second doping layer being located on the back side, the second doping layer comprising a groove, the groove exposing the surface of the substrate, the surface of the substrate exposed by the groove having a first pyramid morphology, the surface of the second doping layer having a second pyramid morphology, the first pyramid morphology being different from the second pyramid morphology, and the second doping layer containing second doping type ions; a front electrode, the front electrode being in electrical contact with the third region; A back electrode is electrically contacted with the second doped layer.

9. The solar cell according to claim 8, characterized in that: A difference between a junction depth of the third region and a junction depth of the fourth region is 0.8 μm to 1.4 μm.

10. The solar cell according to claim 8, characterized in that: The third region and the fourth region are both pyramid-shaped, and the height of the pyramid of the third region is greater than the height of the pyramid of the fourth region.

Images