Method for manufacturing battery sheet and solar cell

Abstract

The embodiment of the present disclosure provides a manufacturing method of a battery piece and a solar cell. The manufacturing method of the battery piece comprises the following steps: providing an initial battery piece; cutting the initial battery piece to form a cut battery piece with at least one cutting surface; forming a first passivation layer, the first passivation layer covering at least part of the cutting surface of the cut battery piece; forming a second passivation layer, the second passivation layer covering at least the surface of the first passivation layer; forming a third passivation layer, the third passivation layer covering at least the surface of the second passivation layer; forming a fourth passivation layer, the fourth passivation layer covering at least the surface of the third passivation layer; wherein the material of the first passivation layer is a semiconductor oxide, the material of the second passivation layer is a metal semiconductor oxide, the material of the third passivation layer and the fourth passivation layer is a metal oxide, the density of the third passivation layer is greater than that of the fourth passivation layer, and the thickness of the third passivation layer is less than that of the fourth passivation layer, so that the battery efficiency and the production efficiency can be considered.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the field of photovoltaics, and in particular to a method for manufacturing a cell piece and a solar cell. BACKGROUND

[0002] In order to reduce the power reduction and hot spot of photovoltaic modules caused by the difference in electrical performance of the cells, the high current of the whole piece solar cell can easily lead to significant resistance loss. In order to improve the problem of large power loss of the whole piece solar cell, the half piece and the shingled photovoltaic module are favored by terminal module manufacturers and users.

[0003] However, whether it is a half piece module or a shingled module, laser cutting technology is needed to cut the whole piece solar cell into half or multiple small piece cut cell pieces. Due to the mechanical damage in the cutting process and the existence of the cutting surface, the efficiency of the cut cell is reduced, thereby reducing the power of the module. SUMMARY

[0004] Embodiments of the present disclosure provide a method for manufacturing a cell piece and a solar cell, which can at least take into account the cell efficiency and production efficiency.

[0005] According to some embodiments of the present disclosure, the present disclosure provides a method for manufacturing a cell piece, comprising: providing an initial cell piece; cutting the initial cell piece to form a cut cell piece having at least one cutting surface; forming a first passivation layer covering at least part of the cutting surface of the cut cell piece; forming a second passivation layer covering at least one side surface of the first passivation layer away from the cut cell piece; forming a third passivation layer covering at least one side surface of the second passivation layer away from the first passivation layer; and forming a fourth passivation layer covering at least one side surface of the third passivation layer away from the second passivation layer; wherein the material of the first passivation layer is a semiconductor oxide, the material of the second passivation layer is a metal semiconductor oxide, the material of the third passivation layer and the fourth passivation layer is a metal oxide, the third passivation layer and the fourth passivation layer are formed by different processes, the density of the third passivation layer is greater than that of the fourth passivation layer, and the thickness of the third passivation layer is less than that of the fourth passivation layer.

[0006] In some embodiments, the process for forming the third passivation layer comprises: forming the third passivation layer by atomic layer deposition process, and the process parameters for forming the third passivation layer comprise: process temperature: 150-350℃, and sequentially introducing a gas source containing a metal element, nitrogen, water vapor / nitrogen, and nitrogen, each gas flow being 500-3000sccm, the time for introducing each gas being 3-15s, and the number of rounds of introducing the gas being 10-600 rounds.

[0007] In some embodiments, the method of forming the second passivation layer comprises: during the process of forming the third passivation layer, controlling the diffusion of the metal element of the third passivation layer into part of the first passivation layer, so as to convert part of the first passivation layer into the second passivation layer.

[0008] In some embodiments, the process of forming the fourth passivation layer comprises: forming the fourth passivation layer by chemical vapor deposition, and the process parameters of forming the fourth passivation layer comprise: a process temperature of 150-600°C, while introducing a metal element-containing gas source, an oxygen element-containing gas source, and nitrogen gas, each gas flow being 300-2000sccm, and exciting plasma.

[0009] In some embodiments, the sliced battery piece comprises a substrate, and the method of forming the first passivation layer comprises: oxidizing the cutting surface of the sliced battery piece, so as to convert part of the substrate of the sliced battery piece into the first passivation layer, and the process parameters of forming the first passivation layer comprise: a process temperature of 100-150°C, a water vapor gas flow of 1000-2000sccm, and a time length of 5-60s.

[0010] In some embodiments, the process parameters of cutting the initial battery piece comprise: laser power of 80-100w, water flow of 1-5ml, and a cutting angle of 45-90°.

[0011] According to some embodiments of the present disclosure, another aspect of the present disclosure further provides a solar cell, comprising: a sliced battery piece, at least two of the sliced battery pieces being formed after cutting processing of a same whole solar cell, the sliced battery piece having a cutting surface; a first passivation layer, the first passivation layer covering at least part of the cutting surface of the sliced battery piece; a second passivation layer, the second passivation layer covering at least a side surface of the first passivation layer away from the sliced battery piece; a third passivation layer, the third passivation layer covering at least a side surface of the second passivation layer away from the first passivation layer; and a fourth passivation layer, the fourth passivation layer covering at least a side surface of the third passivation layer away from the second passivation layer; wherein the material of the first passivation layer is a semiconductor oxide, the material of the second passivation layer is a metal-semiconductor oxide, the materials of the third passivation layer and the fourth passivation layer are metal oxides, the compactness of the third passivation layer is greater than that of the fourth passivation layer, and the thickness of the third passivation layer is less than that of the fourth passivation layer.

[0012] In some embodiments, the metal element of the second passivation layer is the same as the metal element of the third passivation layer, and the doping concentration of the metal element of the second passivation layer is less than the doping concentration of the metal element of the third passivation layer.

[0013] In some embodiments, the third passivation layer has a thickness of 5-15 nm, and / or the fourth passivation layer has a thickness of 20-100 nm.

[0014] In some embodiments, the sliced cell piece includes opposite front and back surfaces, and an included angle between the cutting surface and the front surface or the back surface is an acute angle.

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

[0016] On the one hand, the first passivation layer, the second passivation layer, the third passivation layer, and the fourth passivation layer are sequentially formed on the section, and the passivation effect on the section can be improved by the multi-layer stacking mode. Moreover, the third passivation layer and the fourth passivation layer are metal oxides, and the metal oxides have good chemical passivation ability and field effect passivation ability, so that the performance of the formed cell piece can be improved.

[0017] On the other hand, for the third passivation layer and the fourth passivation layer, the third passivation layer and the fourth passivation layer exposed to the air can absorb water vapor in the air or adsorb particles in the air, resulting in failure of the third passivation layer and the fourth passivation layer. Therefore, the third passivation layer and the fourth passivation layer need to have a certain thickness and density to have a good passivation effect. However, for the metal oxide layer, if only the density is considered, a longer process time will be required, which will greatly affect the yield. If only the thickness is considered, the metal oxide layer will fail. Therefore, different processes are adopted when forming the third passivation layer and the fourth passivation layer to form the third passivation layer with a larger density and the fourth passivation layer with a greater thickness, so that the reliability and production efficiency can be considered at the same time, so that the battery efficiency and production efficiency of the formed cell piece can be considered. BRIEF DESCRIPTION OF DRAWINGS

[0018] One or more embodiments are illustrated by way of example in the drawings that are for illustrative purposes only, and not for the purposes of limiting the embodiments, unless otherwise explicitly stated and limited. Except for the drawings, the figures in the drawings do not constitute a proportional limit; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creating any creative labor on the basis of these drawings.

[0019] Figures 1 to 5 A structure schematic diagram corresponding to each step of a battery piece manufacturing method provided by an embodiment of the present disclosure is provided.

[0020] Figure 6A structural schematic diagram of a photovoltaic module provided by an embodiment of the present disclosure;

[0021] Figure 7 A cross-sectional schematic diagram of a photovoltaic module provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] As known from the background, the photoelectric conversion efficiency of the solar cell after cutting needs to be improved.

[0023] It is found through analysis that, in order to improve the problem of large power loss of the whole solar cell, the whole solar cell is cut into half or multiple small piece cell pieces by using laser cutting technology, and then the piece cell pieces are connected in series by using conductive welding strips. The series current is lower than the whole current, and the decrease of the current of the piece cell pieces can improve the power loss of the photovoltaic module.

[0024] However, in the laser cutting process, if the laser locally melts the whole solar cell along a set path, and then the cell piece is cracked along the set path by mechanical force to realize cutting, a cutting surface is left on the piece cell piece, and the cutting surface forms a laser damage area and a mechanical fracture area, so that the silicon atoms at the cutting surface cannot maintain the original ordered arrangement state, and there are a large number of defect states, which become effective recombination centers of carriers. A large number of carriers are recombined based on the recombination centers, which seriously reduces the photoelectric conversion efficiency of the piece cell piece.

[0025] The embodiments of the present disclosure provide a piece cell manufacturing method, a solar cell and a photovoltaic module. In the piece cell manufacturing method, on the one hand, a first passivation layer, a second passivation layer, a third passivation layer and a fourth passivation layer are sequentially formed on the fracture surface. The passivation effect on the fracture surface can be improved by the multi-layer stacking mode. Moreover, the third passivation layer and the fourth passivation layer are metal oxides, which have good chemical passivation ability and field effect passivation ability, and can improve the performance of the formed piece cell. On the other hand, for the third passivation layer and the fourth passivation layer, the third passivation layer and the fourth passivation layer exposed to the air may absorb water vapor in the air or adsorb particles in the air, resulting in failure of the third passivation layer and the fourth passivation layer. Therefore, the third passivation layer and the fourth passivation layer need to have a certain thickness and density to have good passivation effect. However, for the metal oxide layer, if only the density is considered, a long process time is needed, which greatly affects the yield. If only the thickness is considered, the metal oxide layer will fail. Therefore, different processes are adopted when the third passivation layer and the fourth passivation layer are formed, so that the third passivation layer with greater density and the fourth passivation layer with greater thickness can simultaneously consider reliability and production efficiency, so as to consider the cell efficiency of the formed piece cell and the production efficiency.

[0026] In the description of the embodiments of the disclosure, the technical terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the disclosure, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0027] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the disclosure. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments of the disclosure, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean: A exists, A and B exist, and B exists. In addition, the character " / " herein generally represents that the front and rear associated objects are in an "or" relationship.

[0029] In the description of the embodiments of the disclosure, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0030] In the description of the embodiments of the disclosure, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the disclosure and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the disclosure.

[0031] In the description of the embodiments of the disclosure, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection", "fixing", and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the disclosure can be understood according to the specific circumstances.

[0032] In the drawings corresponding to the embodiments of the present disclosure, the thickness and area of layers are exaggerated for clarity. When a component (such as a layer, film, region, or substrate) is described as being "on" or "in" another component, it can be "directly on" the other component (i.e., in the case of no other component therebetween) or there can be another component therebetween. Conversely, when a component is described as being "directly on" another component, it is meant that there is no other component therebetween. Also, when a component is described as being "formed on" another component, it is meant that the component is formed on an entire surface (or front surface) of the other component, or on a partial edge of the entire surface.

[0033] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, it does not exclude the presence of other components, and other components can also be further included. Also, when a layer, film, region, or plate, etc. component is referred to as "on" another component, it can be "directly on" the other component (i.e., between the other component surface and another component, there is no other component), or there can be another component therebetween. Also, when a layer, film, region, plate, etc. component is "directly on" another component, or when a layer, film, region, plate, etc. component is on another component surface, it is meant that there is no other component therebetween.

[0034] The terms used in the description of various described embodiments herein are only used to describe specific embodiments, and are not intended to be limiting. As used in the description of various described embodiments and the appended claims, "the component" is also intended to include the plural, unless the context clearly indicates otherwise. Among them, the components include layers, films, regions, or plates, etc.

[0035] The various embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in various embodiments of the present disclosure, many technical details are presented in order to enable the reader to better understand the present disclosure. However, the technical solutions claimed by the present disclosure can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0036] Reference Figures 1 to 5 , Figures 1 to 5 A structure schematic diagram corresponding to each step of a solar cell provided by an embodiment of the present disclosure.

[0037] Reference Figure 1 , Figure 1 A structure schematic diagram of an initial cell piece, in some implementations, the manufacturing method of the cell piece can include: providing an initial cell piece 100.

[0038] The initial solar cell 100 includes, but is not limited to, one or any combination of PERC (Passivated Emitter Rear Cell), IBC (Interdigitated Back Contact), TOPCon (Tunnel Oxide Passivated Contact), HIT / HJT (Heterojunction Technology), thin-film solar cells, and tandem solar cells. Thin-film solar cells include, but are not limited to, perovskite thin-film solar cells, copper indium selenide (CIGS) thin-film solar cells, gallium arsenide (GaAs) thin-film solar cells, and cadmium sulfide (CdS) thin-film solar cells. Tandem solar cells include, but are not limited to, perovskite cells stacked with crystalline silicon cells, perovskite cells stacked with perovskite cells, and perovskite cells stacked with thin-film cells.

[0039] Taking TOPCon battery as an example, the initial cell 100 may have a front emitter 120, a front passivation layer 130, a front electrode 140, a back oxide layer 150, a back doped conductive layer 160, a back passivation layer 170 and a back electrode 180 already formed on the surface of the substrate 110.

[0040] refer to Figure 2 , Figure 2 In order to be in Figure 1 Based on the above, a structural diagram of a sliced ​​battery cell is formed. The method of manufacturing the battery cell may also include: cutting the initial battery cell 100 to form a sliced ​​battery cell 101 having at least one cut surface 111.

[0041] It is understandable that, for the sliced ​​solar cell 101, the sliced ​​solar cell 101 can also have a substrate 110, a front emitter 120, a front passivation layer 130, a front electrode 140, a back oxide layer 150, a back doped conductive layer 160, a back passivation layer 170, and a back electrode 180.

[0042] In some embodiments, the method of cutting the initial battery cell 100 may include using laser cutting.

[0043] The process parameters for cutting the initial solar cell 100 may include: laser power of 80-100W, such as 80W, 85W, 90W, 93W or 98W, etc.; water flow rate of 1-5ml, such as 1ml, 2ml, 3ml, 4ml or 5ml, etc.; and cutting angle of 45-90°, such as 60°, 70°, 80° or 85°, etc.

[0044] For the laser power, the greater the laser power, the faster the cutting speed, but the greater the damage to the formed sliced battery piece, therefore, by setting the laser power to 80-100w, the process efficiency can be guaranteed while ensuring the reliability of the formed sliced battery piece 101.

[0045] For the water flow, the water flow is introduced to cool down during the process of cutting the initial battery piece 100, which serves to protect the battery piece, therefore, by setting the water flow to 1-5ml, the cutting process can be affected while the damage to the formed sliced battery piece is minimized.

[0046] For the cutting angle, the cutting angle can be adjusted according to the needs, the smaller the cutting angle, the more conducive to reducing the probability of carrier recombination on the cutting surface, but the smaller the cutting angle, the more it will affect the reliability of the formed sliced battery piece 101, therefore, the cutting angle is set to 45-90° to balance the reliability and performance of the formed sliced battery piece 101.

[0047] Reference Figure 3 , Figure 3 To form a first passivation layer on the basis of Figure 2 The method for manufacturing a battery piece can further include: forming a first passivation layer 102 covering at least part of the cutting surface 111 of the sliced battery piece 101.

[0048] In some embodiments, the method for forming the first passivation layer 102 can include: oxidizing the cutting surface 111 of the sliced battery piece 101 to convert part of the substrate 110 of the sliced battery piece 101 into the first passivation layer 102. By oxidizing the substrate 110, on the one hand, the cutting surface 111 can be repaired, thereby reducing the recombination center of the carrier; on the other hand, the film layer formed by oxidizing the substrate 110 has high density, which can improve the passivation effect of the first passivation layer 102.

[0049] The process parameters for forming the first passivation layer 102 can include: process temperature: 100-150℃, for example, 110℃, 120℃, 130℃, or 140℃, water vapor inlet gas flow: 1000-2000sccm, for example, 1200sccm, 1400sccm, 1600sccm, 1700sccm, or 1900sccm, time length: 5-60s, for example, 10s, 20s, 30s, 40s, or 50s, etc.

[0050] For the process temperature, the higher the process temperature, the faster the rate of forming the first passivation layer 102, but the higher the depth of the first passivation layer 102 passivating the sliced battery piece, therefore, the process temperature is set to 100-150℃, which can improve the process efficiency while avoiding affecting the photoelectric conversion efficiency of the sliced battery piece.

[0051] For the water vapor gas flow, it can be understood that the cutting surface of the sliced battery piece 10 has a certain reaction area, and based on this, the rate of forming the first passivation layer 102 has a certain upper limit of reaction. Setting the water vapor gas flow to 1000-2000 sccm can make the entire passivation process have a certain rate while avoiding waste of water vapor.

[0052] For the process time, the longer the process time, the thicker the first passivation layer 102 formed, therefore, setting the time to 5-60 s can make the first passivation layer 102 have a certain thickness while avoiding the first passivation layer affecting the photoelectric conversion efficiency of the sliced battery piece.

[0053] For the process of forming the first passivation layer 102 by oxidation, the oxidation process will also oxidize part of the front emitter 120 and part of the back doped conductive layer 160.

[0054] In some embodiments, the method of forming the first passivation layer 102 can also include: directly forming the first passivation layer 102 on the surface of the cutting surface 111 by deposition. Compared with the oxidation substrate 110, the deposition method can avoid the thickness of the oxidation process being too deep, and avoid causing too much impact on the ability of the substrate 110 to generate photo-generated carriers. Moreover, by deposition, the thickness of the first passivation layer 102 formed can be controlled. Compared with the oxidation method, the deposition method can more accurately control the first passivation layer 102 to be the required thickness.

[0055] For the process of forming the first passivation layer 102 by deposition, the first passivation layer 102 formed not only covers the side wall of the substrate 110, but also covers the side wall of the front emitter 120, the front passivation layer 130, the front electrode 140, the back oxidation layer 150, the back doped conductive layer 160, the back passivation layer 170 and the back electrode 180.

[0056] In some embodiments, the material of the first passivation layer 102 is a semiconductor oxide, for example, a silicon oxide material. The oxygen atoms of the first passivation layer 102 saturate the dangling bonds on the cutting surface 111 to reduce the defect state density of the cutting surface 111, reduce the recombination center of the cutting surface 111 to reduce the probability of carrier recombination.

[0057] In some embodiments, when the initial battery wafer 100 is cut, the cutting surface 111 is formed at an acute angle with one surface of the substrate 110, that is, the inclined cutting surface 111 is formed, the atomic arrangement density on the inclined cutting surface 111 is smaller, and the covalent bond surface density is smaller, so that the connection between adjacent atoms on the cutting surface 111 is not firm, which is more conducive to promoting the bonding between the first passivation layer 102 on the cutting surface 111 and the dangling bond on the cutting surface 111, that is, the first passivation layer 102 is more easily saturated with the dangling bond on the cutting surface 111, and the first passivation layer 102 can also passivate other surface defects on the cutting surface 111, which is conducive to further improving the ability of the first passivation layer 102 to reduce the defect state density of the cutting surface 111, to further reduce the recombination center of the cutting surface 111 to reduce the carrier recombination probability. In other words, the design of the cutting surface 111 of the sliced battery wafer is inclined relative to the back surface instead of being perpendicular, and cooperates with the passivation function of the first passivation layer 102, which is conducive to further improving the passivation effect of the first passivation layer 102 on the cutting surface 111, to further reduce the probability of carrier recombination on the cutting surface 111, improve the lifetime of the carrier, and thus further improve the photoelectric conversion efficiency of the sliced battery.

[0058] Reference Figure 4 , Figure 4 In Figure 3 addition to the formation of the second passivation layer, the method for manufacturing the battery wafer can further include: forming a second passivation layer 103, the second passivation layer 103 covering at least one side surface of the first passivation layer 102 away from the sliced battery wafer 101; forming a third passivation layer 104, the third passivation layer 104 covering at least one side surface of the second passivation layer 103 away from the first passivation layer 102.

[0059] In some embodiments, the process of forming the third passivation layer 104 includes: forming the third passivation layer 104 by using an atomic layer deposition process, the film thickness of the third passivation layer 104 formed by using the atomic layer deposition process is controllable and uniform, and is highly consistent with the surface shape of the cutting surface 111, and the defect density of the third passivation layer 104 formed by using the atomic layer deposition process is low.

[0060] In some embodiments, the process parameters for forming the third passivation layer 104 may include a process temperature of 150–350°C, such as 200°C, 230°C, 250°C, 300°C, 320°C, or 340°C, and sequentially introducing a gas source containing a metal element, nitrogen, water vapor / nitrogen, and nitrogen, with each gas flow rate of 500–3000 sccm, such as 1000 sccm, 1500 sccm, 1800 sccm, 2200 sccm, 2500 sccm, or 2800 sccm, and the time for each gas introduction is 3–15 s, such as 6 s, 7 s, 10 s, 12 s, 13 s, or 14 s, and the number of gas introduction cycles is 10–600, such as 100 cycles, 150 cycles, 200 cycles, 250 cycles, 300 cycles, 400 cycles, or 500 cycles, etc.

[0061] Regarding process temperature, the higher the process temperature, the faster the rate of forming the third passivation layer 104, but the thickness of the third passivation layer 104 becomes more uncontrollable. Therefore, setting the process temperature to 150-350℃ can improve process efficiency while forming the required thickness of the third passivation layer 104.

[0062] For the gas source, by controlling the sequential introduction of a gas source containing metal elements, nitrogen, water vapor / nitrogen, and nitrogen, with each gas flow rate of 500-3000 sccm, the gas introduction time of each time is 3-15 seconds, and the number of gas introduction cycles is 10-600. By sequentially introducing the gas source containing metal elements, nitrogen, water vapor / nitrogen, and nitrogen, a third passivation layer 104 composed of several film layers is formed, thereby improving the density and reliability of the third passivation layer.

[0063] In some embodiments, the process temperature for forming the third passivation layer 104 is 200-300°C, and the gas flow rate of each gas is 1500-2000 sccm. For the third passivation layer 104, the area of ​​the interface formed is fixed, and the formation rate has a certain upper limit. At this temperature and gas flow rate, the rate of the third passivation layer can be increased while avoiding waste of each gas.

[0064] The third passivation layer 104 is made of a metal oxide material, wherein the metal element includes at least one of Al, Ti, Zn, Zr or Hf, which enables the third passivation layer 104 to have a high density of fixed negative charge, so as to provide a good field passivation effect on the cut surface 111; the metal element in the metal oxide material includes at least one of Mo, W or Ni, which enables the third passivation layer 104 to have a high density of fixed positive charge or a high work function, so as to provide a good field passivation effect on the cut surface 111.

[0065] In some embodiments, the method of forming the second passivation layer 103 comprises: in the process of forming the third passivation layer 104, controlling the diffusion of the metal elements of the third passivation layer 104 into the partial first passivation layer 102 to convert the partial first passivation layer 102 into the second passivation layer 103.

[0066] On the one hand, by forming the second passivation layer 103 by diffusing the metal elements of the third passivation layer 104 into the first passivation layer 102, the process steps of the manufacturing method of the battery piece can be reduced, thereby reducing the overall cost of the battery piece. On the other hand, the second passivation layer 103 is used as an intermediate layer between the first passivation layer 102 and the third passivation layer 104, and the second passivation layer 103 is controlled to have the same semiconductor elements as the first passivation layer and the same metal elements as the third passivation layer 104. In this way, the second passivation layer 103 is beneficial to making the lattice at the interface between the second passivation layer 103 and the first passivation layer 102 more suitable by means of the semiconductor elements, and is also beneficial to making the lattice at the interface between the second passivation layer 103 and the third passivation layer 104 more suitable by means of the metal elements, thereby avoiding the problem of lattice matching between the first passivation layer 102 and the third passivation layer 104 when they are in direct contact, thereby avoiding the problem of surface defects caused by lattice mismatch, and thereby improving the passivation effect of the cutting surface 111 of the battery piece.

[0067] In other words, the second passivation layer 103 plays a transitional role to improve the lattice matching degree at the interfaces between the first passivation layer 102, the second passivation layer 103 and the third passivation layer 104, prevent the occurrence of voids and misalignment at the interfaces between the first passivation layer 102, the second passivation layer 103 and the third passivation layer 104, and improve the uniformity of the overall film layer of the first passivation layer 102, the second passivation layer 103 and the third passivation layer 104, thereby improving the interface passivation effect of the first passivation layer 102, the second passivation layer 103 and the third passivation layer 104 on the battery piece 101. Furthermore, the second passivation layer 103 is beneficial to improving the connection strength between the first passivation layer 102 and the third passivation layer 104, thereby avoiding the problem of mutual sliding or falling off of the first passivation layer 102 and the second passivation layer 103, or the second passivation layer 103 and the third passivation layer 104, thereby improving the structural stability of the first passivation layer 102, the second passivation layer 103 and the third passivation layer 104 as a whole.

[0068] In some embodiments, the content of metal elements in the second passivation layer 103 gradually decreases from the third passivation layer 104 toward the first passivation layer 102, and the content of semiconductor elements in the second passivation layer 103 gradually decreases from the first passivation layer 102 toward the third passivation layer 104. In this way, the semiconductor element content at the interface between the second passivation layer 103 and the first passivation layer 102 can be controlled to be the highest, and the metal element content at the interface between the second passivation layer 103 and the third passivation layer 104 can be the highest. This can further improve the lattice fit at the interface between the second passivation layer 103 and the first passivation layer 102, and further improve the lattice fit at the interface between the second passivation layer 103 and the third passivation layer 104, thereby further improving the overall passivation effect of the first passivation layer 102, the second passivation layer 103, and the third passivation layer 104.

[0069] It should be noted that the gradual decrease in element content mentioned above can mean that the element content gradually decreases in the normal direction of the interface between the second passivation layer 103 and the first passivation layer 102, or it can mean that the average element content in the second passivation layer 103 gradually decreases within a predetermined thickness in the normal direction of the interface between the second passivation layer 103 and the first passivation layer 102.

[0070] In some embodiments, the method of forming the second passivation layer 103 and the third passivation layer 104 may further include: forming the second passivation layer 103 on the surface of the first passivation layer 102 by deposition, and then forming the third passivation layer 104 on the surface of the second passivation layer 103 by deposition. The deposition method can facilitate the control of the thickness of the formed second passivation layer 103 and can also improve the uniformity of the second passivation layer 103 film.

[0071] refer to Figure 5 , Figure 5 exist Figure 4 Based on the formation of a fourth passivation layer, the method for manufacturing the battery cell may further include: forming a fourth passivation layer 105, wherein the fourth passivation layer 105 at least covers the surface of the third passivation layer 104 away from the second passivation layer 103; wherein the material of the fourth passivation layer 105 is a metal oxide, and the third passivation layer 104 and the fourth passivation layer 105 are manufactured using different processes such that the density of the third passivation layer 104 is greater than that of the fourth passivation layer 105, and the thickness of the third passivation layer 104 is less than that of the fourth passivation layer 105.

[0072] For the third passivation layer 104 and the fourth passivation layer 105, the third passivation layer 104 and the fourth passivation layer 105 need to have a certain thickness and density to have a good passivation effect. If only the density is considered, a longer process time is needed, which greatly affects the yield. If only the thickness is considered, the metal oxide layer will fail. Therefore, when forming the fourth passivation layer 105, the process difficulty of the fourth passivation layer 105 is reduced by reducing the density of the fourth passivation layer 105, so as to improve the process speed of forming the fourth passivation layer 105, so that the third passivation layer 104 and the fourth passivation layer 105 as a whole consider both the density and the thickness of the film layer.

[0073] In some embodiments, the process of forming the fourth passivation layer 105 includes forming the fourth passivation layer 105 by chemical vapor deposition. Chemical vapor deposition can quickly prepare a metal oxide layer with a certain thickness, so that the third passivation layer 104 and the fourth passivation layer 105 as a whole have a certain thickness, so as to fully utilize the fixed charges in the film layer to achieve field passivation, thereby improving the passivation effect of the third passivation layer 104 and the fourth passivation layer 105 as a whole.

[0074] In some embodiments, the process parameters for forming the fourth passivation layer 105 include a process temperature of 150-600°C, for example, 200°C, 300°C, 400°C, 450°C, 500°C, or 550°C, etc., while introducing a metal element gas source, an oxygen element gas source, and nitrogen gas, each gas flow being 300-2000sccm, for example, 400sccm, 500sccm, 600sccm, 700sccm, 800sccm, 1000sccm, 1500sccm, or 1800sccm, and exciting plasma.

[0075] By controlling the process parameters for forming the fourth passivation layer 105 to be a process temperature of 150-600°C, while introducing a metal element gas source, an oxygen element gas source, and nitrogen gas, each gas flow being 300-2000sccm, and exciting plasma, the formation rate of the fourth passivation layer 105 is improved, so as to quickly form a fourth passivation layer 105 with a certain thickness, so that the third passivation layer 104 and the fourth passivation layer 105 as a whole have a certain thickness, thereby improving the passivation ability and reliability of the third passivation layer 104 and the fourth passivation layer 105 as a whole. Moreover, by quickly forming the fourth passivation layer, the process time of the entire process can be reduced.

[0076] In some embodiments, the process temperature for forming the fourth passivation layer 105 is 400-500°C, and the flow rate of each gas is 400-800sccm. It can be understood that the area of the formation surface of the third passivation layer 104 is fixed, and thus there is an upper limit to the formation speed of the fourth passivation layer 105. In this temperature range and gas flow rate range, the fourth passivation layer 105 can have a certain formation speed without wasting each gas.

[0077] The method for manufacturing a battery piece provided by the embodiments of the present disclosure has the following advantages. On the one hand, the first passivation layer 102, the second passivation layer 103, the third passivation layer 104, and the fourth passivation layer 105 are sequentially formed on the section surface, and the passivation effect on the section surface can be improved by the multi-layer stacking mode. In addition, the third passivation layer 104 and the fourth passivation layer 105 are metal oxides, which have good chemical passivation ability and field effect passivation ability, and thus the performance of the formed battery piece can be improved. On the other hand, the third passivation layer 104 and the fourth passivation layer 105 exposed to the air can absorb water vapor in the air or adsorb particles in the air, which can cause the third passivation layer 104 and the fourth passivation layer 105 to fail. Therefore, the third passivation layer 104 and the fourth passivation layer 105 need to have a certain thickness and density to have a good passivation effect. However, for the metal oxide layer, if only the density is considered, a long process time is required, which can greatly affect the yield. If only the thickness is considered, the metal oxide layer can fail. Therefore, different processes are used to form the third passivation layer 104 and the fourth passivation layer 105, and the third passivation layer 104 with a larger density and the fourth passivation layer 105 with a greater thickness can simultaneously consider reliability and production efficiency, so that the battery efficiency of the formed battery piece and the production efficiency can be considered.

[0078] Another embodiment of the present disclosure also provides a solar cell, which can be formed by using the method for manufacturing a battery piece described above. The solar cell provided by another 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 of the foregoing embodiments can refer to the corresponding descriptions of the foregoing embodiments, which will not be described herein.

[0079] Reference Figure 5 In some embodiments, the solar cell includes the sliced battery piece 101, and the at least two sliced battery pieces 101 are formed by cutting the same whole solar cell. The sliced battery piece 101 has a cutting surface 111.

[0080] The solar cell further includes the first passivation layer 102, which covers at least part of the cutting surface 111 of the sliced battery piece 101.

[0081] The solar cell further comprises a second passivation layer 103 covering at least one side surface of the first passivation layer 102 away from the sliced cell piece 101.

[0082] The solar cell further comprises a third passivation layer 104 covering at least one side surface of the second passivation layer 103 away from the first passivation layer 102.

[0083] The solar cell further comprises a fourth passivation layer 105 covering at least one side surface of the third passivation layer 104 away from the second passivation layer 103, wherein the material of the first passivation layer 102 is a semiconductor oxide, the material of the second passivation layer 103 is a metal-semiconductor oxide, the material of the third passivation layer 104 and the fourth passivation layer 105 is a metal oxide, the density of the third passivation layer 104 is greater than that of the fourth passivation layer 105, and the thickness of the third passivation layer 104 is less than that of the fourth passivation layer 105.

[0084] The solar cell further comprises a fourth passivation layer 105 covering at least one side surface of the third passivation layer 104 away from the second passivation layer 103, wherein the material of the first passivation layer 102 is a semiconductor oxide, the material of the second passivation layer 103 is a metal-semiconductor oxide, the material of the third passivation layer 104 and the fourth passivation layer 105 is a metal oxide, the density of the third passivation layer 104 is greater than that of the fourth passivation layer 105, and the thickness of the third passivation layer 104 is less than that of the fourth passivation layer 105.

[0085] The sliced cell piece 101 formed by the whole solar cell as the TOPCon cell can have a substrate 110, a front emitter 120, a front passivation layer 130, a front electrode 140, a back oxidation layer 150, a back doped conductive layer 160, a back passivation layer 170, and a back electrode 180. The whole solar cell can also be other types of cells, and the sliced cell piece 101 formed thereby also has the basic characteristics of other types of cells.

[0086] In some embodiments, the metal element of the second passivation layer 103 is the same as the metal element of the third passivation layer 104, and the doping concentration of the metal element of the second passivation layer 103 is less than the doping concentration of the metal element of the third passivation layer 104. In this way, on the one hand, the forming process of the second passivation layer 103 can be facilitated by controlling the diffusion of the metal element of the third passivation layer 104 into the second passivation layer 103 when the third passivation layer 104 is formed, and on the other hand, the lattice difference of the contact surface between the second passivation layer 103 and the third passivation layer 104 can be reduced, and the doping concentration of the metal element of the second passivation layer 103 is set to be less than the doping concentration of the metal element of the third passivation layer 104, so that the metal doping elements in different passivation layers gradually change during the process of the first passivation layer 102 to the third passivation layer 104, which is conducive to improving the performance stability of the second passivation layer 103 and the stability of the first passivation layer 102 to the third passivation layer 104 as a whole, and avoiding performance mutation caused by sudden change of the content of metal elements.

[0087] In some embodiments, the doping concentration of the metal element in the second passivation layer 103 gradually increases in the direction of the second passivation layer 103 towards the third passivation layer 104, and the proportion of the doping element can increase from 2% to 50%.

[0088] In some embodiments, the thickness of the third passivation layer 104 is 5-15 nm, for example, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, or 14 nm, and the like. It can be understood that for the third passivation layer 104, the thicker the thickness of the third passivation layer 104, the better the passivation effect brought by the third passivation layer 104, and because the third passivation layer 104 has high density, the thicker the thickness of the third passivation layer 104, the higher the stability of the third passivation layer 104 itself. However, because the third passivation layer 104 has high density, the forming process of the third passivation layer 104 requires a long time. By controlling the thickness of the third passivation layer 104 to be 5-15 nm, the passivation effect of the third passivation layer 104 can be considered while the manufacturing time of the battery piece is taken into account.

[0089] In some embodiments, the fourth passivation layer 105 has a thickness of 20-100 nm, for example, 30 nm, 40 nm, 50 nm, 55 nm, 60 nm, 70 nm, 80 nm, or 90 nm, etc. For the fourth passivation layer 105, the fourth passivation layer 105 needs to have a certain thickness to avoid failure of the fourth passivation layer 105 due to adsorption of water vapor or particles in the air, thereby improving the reliability of the fourth passivation layer 105. However, the thicker the thickness of the fourth passivation layer 105, the longer the time for forming the fourth passivation layer 105, which will reduce the production capacity of the battery sheet. Therefore, by setting the thickness of the fourth passivation layer 105 to be 20-100 nm, the reliability of the fourth passivation layer 105 can be considered while the manufacturing time of the battery sheet is also taken into account.

[0090] In some embodiments, the fourth passivation layer 105 has a thickness of 35-60 nm, for example, 40 nm, 44 nm, 50 nm, 53 nm, 57 nm, or 59 nm, etc. For the fourth passivation layer 105, the fourth passivation layer 105 covers the outermost side of the cutting surface 111 of the sliced battery sheet 101. If the thickness of the fourth passivation layer 105 is too thick, the contact area of the fourth passivation layer 105 with the outside world will be larger, and the area of adsorption of water vapor and particles will also be larger. In addition, the failure caused by the mass due to the thickness and the adsorption of impurities will cause the fourth passivation layer 105 to fall off. Therefore, by setting the thickness of the fourth passivation layer 105 to be 35-60 nm, the passivation effect of the fourth passivation layer 105 can be considered while improving the reliability of the fourth passivation layer 105.

[0091] In some embodiments, the sliced battery sheet 101 includes opposite front and back surfaces, and the included angle between the cutting surface 111 and the front or back surface is an acute angle. It can be understood that, taking the example of cutting a whole solar cell into two sliced battery sheets 101, both of the sliced battery sheets 101 have opposite front surfaces. If the included angle between the front surface of one sliced battery sheet 101 and the cutting surface 111 is an acute angle, then the included angle between the front surface of the corresponding other sliced battery sheet 101 and the cutting surface 111 is an obtuse angle. Compared with cutting along the thickness direction of the whole battery sheet, setting the included angle between the cutting surface 111 and the front or back surface to be an acute angle can reduce the atomic arrangement density on the cutting surface 111, reduce the covalent interface density, and the connection between adjacent atoms on the cutting surface 111 is more unstable, which is more conducive to promoting the bonding of the multilayer passivation layer and the dangling bond on the cutting surface 111. This can further improve the passivation ability of the first passivation layer 102, the second passivation layer 103, the third passivation layer 104, and the fourth passivation layer 105 as a whole, further reduce the probability of carrier recombination on the cutting surface 111, improve the carrier lifetime, and further improve the photoelectric conversion efficiency of the solar cell.

[0092] In some embodiments, the acute angle is 45°-80°, for example, 50°, 55°, 60°, 68°, or 73°, etc. It can be understood that the smaller the acute angle, the more conducive to reducing the probability of carrier recombination on the cleavage surface 111, but the acute angle is too small, and the angle less than 45° will make the tip formed between the cleavage surface 111 and the front surface or the back surface easy to break, which will cause the solar cell to be abnormal, and therefore, by setting the angle of the acute angle to 45°-80°, the probability of carrier recombination on the cleavage surface 111 can be further reduced, and the probability of damage to the solar cell can be reduced.

[0093] In some embodiments, the acute angle is 45°-55°, for example, 47°, 48°, 49°, 50°, 51°, 52°, 53°, or 54°, etc. When the acute angle is 45°-55°, for the cleavage surface 111, the crystal plane on the cleavage surface 111 is a <111> crystal plane, which will make the silicon atom density the most sparse under the angle, for example, the base material is silicon, which is more conducive to promoting the bonding of the multi-layer passivation layer and the dangling bond on the cleavage surface 111, and further improving the passivation ability of the first passivation layer 102, the second passivation layer 103, the third passivation layer 104, and the fourth passivation layer 105 as a whole.

[0094] Another embodiment of the present disclosure also provides a photovoltaic module for converting received light energy into electrical energy. The preparation method of the solar cell provided by another embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Figure 6 A partial perspective structure schematic diagram of the photovoltaic module provided by another embodiment of the present disclosure; Figure 7 As Figure 6 A cross-sectional structure schematic diagram along the cross-sectional direction MM1. It should be noted that the same or corresponding parts as the foregoing embodiments are not described herein.

[0095] Reference Figure 6 And Figure 7 The photovoltaic module includes: a cell string formed by connecting a plurality of solar cells formed by the manufacturing method described in all or part of the above embodiments, or formed by connecting a plurality of solar cells described in all or part of the above embodiments; an encapsulation adhesive film 41 for covering the surface of the cell string; and a cover plate 42 for covering the surface of the encapsulation adhesive film 41 away from the cell string.

[0096] It is worth noting that the solar cells 40 are electrically connected to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or parallel. Based on the fact that the solar cell 40 includes the sliced cell piece 101, and the sliced cell piece 101 is formed by slicing the whole solar cell, the current drop of the sliced cell piece 101 can improve the power loss of the photovoltaic module, thereby improving the photoelectric conversion efficiency of the photovoltaic module.

[0097] In some embodiments, reference Figure 7 Multiple battery strings can be electrically connected through conductive strip 402. Figure 7 This illustration only depicts one possible positional relationship between solar cells, where the electrodes of the same polarity are arranged in the same direction, or where the positive electrode of each cell faces the same side, thus the conductive strip connects different sides of two adjacent cells. In some embodiments, the cells can also be arranged with electrodes of different polarities facing the same side, i.e., the electrodes of multiple adjacent cells are arranged in the order of first polarity, second polarity, and first polarity, respectively, then the conductive strip connects two adjacent cells on the same side.

[0098] In some embodiments, there is no spacing between the solar cells, meaning that the solar cells overlap each other.

[0099] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the solar cell 40, and the second encapsulating layer covers the other of the front or back sides of the solar cell 40. Specifically, at least one of the first encapsulating layer or the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film.

[0100] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0101] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0102] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A method for manufacturing a battery cell, characterized in that, include: Provide initial battery cells; The initial battery cell is cut to form a sliced ​​battery cell with at least one cut surface; A first passivation layer is formed, wherein the first passivation layer at least covers a portion of the cut surface of the sliced ​​battery cell; A second passivation layer is formed, the second passivation layer at least covering the surface of the first passivation layer away from the sliced ​​battery cell; A third passivation layer is formed, wherein the third passivation layer at least covers the side surface of the second passivation layer away from the first passivation layer; A fourth passivation layer is formed, wherein the fourth passivation layer at least covers the surface of the third passivation layer away from the second passivation layer; Wherein, the first passivation layer is made of semiconductor oxide, the second passivation layer is made of metal semiconductor oxide, the third passivation layer and the fourth passivation layer are made of metal oxide, and the third passivation layer and the fourth passivation layer are processed by different processes so that the density of the third passivation layer is greater than that of the fourth passivation layer, and the thickness of the third passivation layer is less than that of the fourth passivation layer.

2. The manufacturing method according to claim 1, characterized in that, The process for forming the third passivation layer includes: forming the third passivation layer using atomic layer deposition (ALD) technology. The process parameters for forming the third passivation layer include: process temperature: 150–350°C, and sequentially introducing a gas source containing metal elements, nitrogen, water vapor / nitrogen, and nitrogen, with each gas flow rate of 500–3000 sccm, each gas introduction time of 3–15 s, and 10–600 gas introduction cycles.

3. The manufacturing method according to claim 2, characterized in that, The method for forming the second passivation layer includes: during the formation of the third passivation layer, controlling the diffusion of metal elements of the third passivation layer into a portion of the first passivation layer to convert a portion of the first passivation layer into the second passivation layer.

4. The manufacturing method according to claim 1, characterized in that, The process for forming the fourth passivation layer includes: forming the fourth passivation layer by chemical vapor deposition. The process parameters for forming the fourth passivation layer include: process temperature: 150-600℃, and simultaneously introducing a gas source containing metal elements, a gas source containing oxygen elements, and nitrogen gas, with each gas flow rate of 300-2000 sccm, and exciting plasma.

5. The manufacturing method according to claim 1, characterized in that, The sliced ​​battery cell includes a substrate. The method for forming the first passivation layer includes: oxidizing the cut surface of the sliced ​​battery cell to convert a portion of the substrate of the sliced ​​battery cell into the first passivation layer. The process parameters for forming the first passivation layer include: process temperature: 100-150°C, gas flow rate of water vapor: 1000-2000 sccm, and duration: 5-60 s.

6. The manufacturing method according to claim 1, characterized in that, The process parameters for cutting the initial battery cell include: laser power of 80-100W, water flow rate of 1-5ml, and cutting angle of 45-90°.

7. A solar cell, characterized in that, include: Sliced ​​solar cells, wherein at least two sliced ​​solar cells are formed by cutting the same whole solar cell. The sliced ​​battery cell has a cut surface; A first passivation layer, wherein the first passivation layer at least covers a portion of the cut surface of the sliced ​​battery cell; A second passivation layer, wherein the second passivation layer at least covers the surface of the first passivation layer away from the sliced ​​battery cell; A third passivation layer, wherein the third passivation layer at least covers the surface of the second passivation layer away from the first passivation layer; A fourth passivation layer, wherein the fourth passivation layer at least covers the surface of the third passivation layer away from the second passivation layer; wherein the material of the first passivation layer is a semiconductor oxide, the material of the second passivation layer is a metal semiconductor oxide, the materials of the third passivation layer and the fourth passivation layer are metal oxides, the density of the third passivation layer is greater than that of the fourth passivation layer, and the thickness of the third passivation layer is less than that of the fourth passivation layer.

8. The solar cell according to claim 7, characterized in that, The metal element of the second passivation layer is the same as that of the third passivation layer, and the doping concentration of the metal element in the second passivation layer is less than that in the third passivation layer.

9. The solar cell according to claim 7, characterized in that, The thickness of the third passivation layer is 5–15 nm, and / or the thickness of the fourth passivation layer is 20–100 nm.

10. The solar cell according to claim 7, characterized in that, The sliced ​​battery cell includes a front side and a back side facing each other, and the angle between the cut surface and the front side or the back side is an acute angle.

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