Solar cell and method of manufacturing the same

Abstract

The embodiment of the present application relates to the field of solar cells, and provides a solar cell and a preparation method thereof, and at least can solve the problem of poor performance of a split cell. The solar cell comprises: a split cell, at least two split cells are formed by splitting a whole solar cell along a first direction, the split cell comprises a first surface, a second surface and a third surface connecting the first surface and the second surface, the first surface is a partial area of a front surface of the whole solar cell, the second surface is a partial area of a back surface of the whole solar cell, and the third surface is a section surface of the split cell after the splitting; a silicon passivation layer, the silicon passivation layer is located on the third surface; a silicon oxide layer, the silicon oxide layer is located on a surface of the silicon passivation layer; and a metal oxide layer, the metal oxide layer is located on the silicon oxide layer.

Description

Technical Field

[0001] This application relates to the field of solar cells, and in particular to a solar cell and a method for its fabrication. Background Technology

[0002] Currently, with the gradual depletion of fossil fuels, solar cells are becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient utilization of electrical energy.

[0003] Current solar cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells. Different film layer configurations and functional limitations are used to reduce optical losses and decrease photogenerated carrier recombination on and within the silicon substrate, thereby improving the photoelectric conversion efficiency of solar cells.

[0004] In the process of assembling solar cells into strings, the entire cell is typically sliced, and the sliced ​​cells are then assembled into strings. This helps reduce encapsulation losses, optimize process issues in module manufacturing, improve module reliability, and also helps reduce manufacturing costs. However, this technology also brings some new challenges and problems, such as the probability of cell breakage and efficiency losses at the cutting surface, which require further optimization and improvement. Summary of the Invention

[0005] This application provides a solar cell and its fabrication method, which at least helps to solve the problem of poor performance of segmented solar cells.

[0006] According to some embodiments of this application, one aspect of this application provides a solar cell, comprising: a segmented cell, wherein at least two of the segmented cells are formed by dividing the same whole solar cell along a first direction, the segmented cell comprising a first surface, a second surface, and a third surface connecting the first surface and the second surface, the first surface being a portion of the front side of the whole solar cell, the second surface being a portion of the back side of the whole solar cell, and the third surface being a cross-section of the segmented cell along the division process; a silicon passivation layer located on the third surface; a silicon oxide layer located on the surface of the silicon passivation layer; and a metal oxide layer located on the silicon oxide layer.

[0007] In some embodiments, the silicon passivation layer is an amorphous silicon layer or a microcrystalline silicon layer; the thickness of the silicon passivation layer is 1 nm to 10 nm.

[0008] In some embodiments, the metal element in the metal oxide layer is an amorphous metal element.

[0009] In some embodiments, the angle between the first surface and the third surface is an acute angle.

[0010] In some embodiments, the system further includes: an intermediate passivation layer located between the silicon oxide layer and the metal oxide layer, wherein the intermediate passivation layer contains at least one of a silicon element in the silicon oxide layer or a metal element in the metal oxide layer.

[0011] In some embodiments, the intermediate passivation layer contains the metal element, and the metal element increases in number along the direction from the silicon oxide layer to the metal oxide layer.

[0012] According to some embodiments of this application, another aspect of this application provides a method for fabricating a solar cell, comprising: providing a whole solar cell, the whole solar cell including a front side and a back side disposed opposite to each other; dividing the whole solar cell along a first direction to form at least two segmented cells, each segmented cell including a first side, a second side, and a third side connecting the first side and the second side, the first side being a partial area of ​​the front side of the whole solar cell, the second side being a partial area of ​​the back side of the whole solar cell, and the third side being a cross-section of the segmented cell along the divided surface; forming a silicon passivation layer located on the third side; forming a silicon oxide layer located on the surface of the silicon passivation layer; and forming a metal oxide layer located on the silicon oxide layer.

[0013] In some embodiments, the reaction temperature for forming the silicon passivation layer, the silicon oxide layer, and the metal oxide layer is less than or equal to 300°C.

[0014] In some embodiments, the entire solar cell includes a substrate, which is laser-processed to convert a portion of the substrate into the silicon passivation layer.

[0015] In some embodiments, the laser processing parameters include: laser wavelength of 300nm~550nm, pulse width of 5ps~100ns, laser power of 1W~25W, pulse frequency of 50kHz~1250kHz, and spot area of ​​5000um. 2 ~50000um 2The scanning speed is 300mm / s to 80000mm / s.

[0016] The technical solution provided in this application has at least the following advantages:

[0017] In the solar cell provided in this application embodiment, a silicon passivation layer is formed on the third surface of the segmented cell. The silicon passivation layer passivates dangling bonds, thereby reducing the number of dangling bonds on the cross-section of the segmented cell. This prevents the reduction in photoelectric conversion efficiency caused by the capture and recombination of minority carriers excited by light upon reaching the surface. It effectively hydrogenates dangling bonds and reduces surface defects, significantly improving minority carrier lifetime, increasing open-circuit voltage, and ultimately improving photoelectric conversion efficiency. Furthermore, a silicon oxide layer and a metal oxide layer are formed on the silicon passivation layer. The silicon oxide layer provides chemical passivation, and the metal oxide layer provides both field passivation and chemical passivation, thereby reducing the recombination rate on the cross-section and improving the photoelectric conversion efficiency of the segmented cell.

[0018] In addition, the crystals in the silicon passivation layer have a disordered structure or are mostly disordered, with low electron and hole migration rates and poor lateral conductivity. This can effectively avoid short circuits and leakage currents caused by the first and second sides of the segmented cell passing through the silicon passivation layer, thereby improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a first top view of a solar cell provided in an embodiment of this application;

[0021] Figure 2 This is a first cross-sectional view of a segmented cell in a solar cell provided in an embodiment of this application;

[0022] Figure 3 This is a second top view of a solar cell provided in an embodiment of this application;

[0023] Figure 4 This is a third top view of a solar cell provided in an embodiment of this application;

[0024] Figure 5This is a second cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application;

[0025] Figure 6 This is a third cross-sectional view of a segmented cell in a solar cell provided in an embodiment of this application;

[0026] Figure 7 This is a fourth cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application;

[0027] Figure 8 A fifth cross-sectional view of a segmented cell in a solar cell provided in an embodiment of this application;

[0028] Figure 9 A sixth cross-sectional view of a segmented cell in a solar cell provided in an embodiment of this application;

[0029] Figure 10 A cross-sectional view of a method for fabricating a solar cell according to an embodiment of this application, showing the formation of a segmented cell.

[0030] Figure 11 This is a cross-sectional view of a photovoltaic module provided in an embodiment of this application. Detailed Implementation

[0031] As can be seen from the background technology, the performance of current segmented batteries is relatively poor.

[0032] The solar cell provided in this application improves the performance of the cell by providing a silicon passivation layer, a silicon oxide layer, and a metal oxide layer on the third side of the cell and performing passivation treatment on the third side through a multi-layer passivation structure, thereby reducing the recombination rate of the cell section without damaging the original performance of the cell.

[0033] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0038] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0039] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. 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" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0040] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0041] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0042] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0043] Figure 1 This is a first top view of a solar cell provided in an embodiment of this application; Figure 2 This is a first cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application.

[0044] According to some embodiments of this application, one aspect of this application provides a solar cell that can improve the photoelectric conversion efficiency of segmented cells.

[0045] refer to Figure 1 and Figure 2The solar cell includes: sectional cells 110, at least two sectional cells 110 being formed by dividing the same whole solar cell 100 along a first direction. Each sectional cell 110 includes a first surface 110a, a second surface 110b, and a third surface 110c connecting the first surface 110a and the second surface 110b. The first surface 110a is a portion of the front side of the whole solar cell 100, the second surface 110b is a portion of the back side of the whole solar cell 100, and the third surface 110c is a cross-section of the sectional cell 110 after being divided along the first direction. The solar cell includes: a silicon passivation layer 111, located on the third surface 110c. The solar cell includes: a silicon oxide layer 121, located on the surface of the silicon passivation layer 111. The solar cell includes: a metal oxide layer 122, located on the silicon oxide layer 121.

[0046] The solar cell provided in this application embodiment has a silicon passivation layer 111 disposed on the third surface 110c of the segmented cell 110. The silicon passivation layer 111 passivates dangling bonds, thereby reducing the number of dangling bonds on the cross-section of the segmented cell 110. This prevents the reduction in photoelectric conversion efficiency caused by the capture and recombination of light-excited minority carriers after they reach the surface. It effectively hydrogenates dangling bonds and reduces surface defects, significantly improving minority carrier lifetime, increasing open-circuit voltage, and ultimately improving photoelectric conversion efficiency. Furthermore, a silicon oxide layer 121 and a metal oxide layer 122 are disposed on the silicon passivation layer 111. The silicon oxide layer 121 provides chemical passivation, and the metal oxide layer 122 provides both field passivation and chemical passivation, thereby reducing the recombination rate on the cross-section and improving the photoelectric conversion efficiency of the segmented cell 110.

[0047] Furthermore, the crystals in the silicon passivation layer 111 have a disordered structure or are mostly disordered, resulting in low electron and hole migration rates and poor lateral conductivity. This effectively avoids short circuits and leakage currents caused by the silicon passivation layer 111 on the first side 110a and the second side 110b of the segmented cell 110, thereby improving the photoelectric conversion efficiency of the solar cell.

[0048] In some embodiments, the monolithic solar cell 100 can be any one of an IBC cell, a TOPCON cell, a PERC cell, and a heterojunction cell. Correspondingly, the segmented cell 110 can be any one of an IBC cell, a TOPCON cell, a PERC cell, and a heterojunction cell.

[0049] Figure 3 This is a second top view of a solar cell provided in an embodiment of this application; Figure 4 This is a third top view of a solar cell provided in an embodiment of this application.

[0050] Segmented battery 110 refers to a battery cell that has been cut into two or more segments using a cutting technique. The current of each segmented battery 110 is 1 / n of the current of the original battery cell, where n is the number of segmented batteries 110 formed by cutting the original battery cell. Depending on the value of n, the segmented battery 110 can include any type of segmented battery 110, such as a two-segmented battery 110, a three-segmented battery 110, a four-segmented battery 110, or an eight-segmented battery 110. For example... Figure 1 The two-piece battery 110 shown Figure 3 The shown quadrilateral battery 110 and Figure 4 The nine-segment battery 110 is shown.

[0051] It should be noted that the number of cross-sections or cut surfaces contained in the segmented battery 110 can vary depending on the location of the cut. For example, Figure 1 The segmented battery 110 shown includes a cut surface; Figure 3 The segmented battery 110 shown includes two cut surfaces; Figure 4 The illustrated segmented battery 110 includes two cut surfaces, three cut surfaces, and four cut surfaces in some parts. In this embodiment, the third surface 110c can be... Figure 1 , Figure 3 as well as Figure 4 Any one or more of the cut surfaces shown.

[0052] The segmented battery 110 can be segmented via a first direction, which can be either the X direction or the Y direction. In this embodiment, the first direction is the X direction as an example.

[0053] In some embodiments, the front side of the solar cell 100 refers to the light-receiving surface of the solar cell 100, and the back side refers to the back side of the solar cell 100. The back side can also receive incident light, but its efficiency in receiving incident light is somewhat lower than that of the light-receiving surface.

[0054] In some embodiments, the included angle between the first surface 110a and the third surface 110c can be any value, that is, the cut surface and the thickness direction Z of the entire solar cell 100 can be any value that intersects or is parallel to each other. It is only necessary to ensure the break between two adjacent cell sections 110. For example, Figure 2 The cut surface shown is parallel to the thickness direction Z of the entire solar cell.

[0055] Figure 5 This is a second cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application.

[0056] In some embodiments, reference Figure 5The angle θ between the first surface 110a and the third surface 110c is an acute angle, meaning the cut surface forms an acute angle with the thickness direction Z of the entire solar cell. Thus, the entire solar cell 100 is obliquely cut to form segmented cells 110. For the first surface 110a and the second surface 110b on the segmented cells 110, the cross-section of the segmented cells 110 can be regarded as an oblique surface. Based on this, compared to dividing the entire solar cell along the thickness direction Z to form the cross-section of the segmented cell 110, in one embodiment of this application, the atomic arrangement density and covalent bond density on the inclined cross-section designed on the segmented cell 110 are smaller. Therefore, the connection between adjacent atoms on the cross-section is not strong, which is more conducive to the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 located on the cross-section forming bonds with the dangling bonds on the cross-section. That is, it makes it easier for the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 to saturate the dangling bonds on the cross-section. In addition, the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 can also passivate other surface defects on the cross-section, which is conducive to further improving the ability of the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 to reduce the defect state density of the cross-section, so as to further reduce the recombination center of the cross-section and reduce the carrier recombination probability. In other words, designing the cross-section of the segmented cell 110 to be inclined rather than perpendicular to the first surface 110a, and combining this with the passivation function of the silicon passivation layer 111, silicon oxide layer 121, and metal oxide layer 122, is beneficial to further improve the passivation effect of the silicon passivation layer 111, silicon oxide layer 121, and metal oxide layer 122 on the cross-section, thereby further reducing the probability of carrier recombination on the cross-section, increasing carrier lifetime, and thus further improving the photoelectric conversion efficiency of the segmented cell 110.

[0057] The substrate of the entire solar cell is crystalline silicon, which has a face-centered cubic (FCC) crystal structure. Due to the microscopic anisotropy of crystalline silicon, the distribution of atoms on different crystal planes is different. Among them, the silicon atom density is lowest on the (111) crystal plane and highest on the (110) crystal plane in monocrystalline silicon. In this embodiment, the cell 110 is formed by oblique cutting, that is, more (111) planes are formed on the oblique cross-section designed on the cell 110, so that the cross-section has fewer dangling bonds, and the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 can passivate the cross-section better.

[0058] refer to Figure 5The angle θ between the first surface 110a and the third surface 110c is an acute angle, which can be between 45° and 80°. If the acute angle is less than 45°, the tilt of the third surface 110c relative to the first surface 110a is too large. In this case, the part of the cell 110 including the third surface 110c can be regarded as a tip protruding from the entire cell 110. The smaller the acute angle, the more protruding the tip is, and the easier it is for the tip to break under pressure, which is not conducive to improving the structural stability of the cell 110. If the acute angle is greater than 80°, the tilt of the third surface 110c relative to the first surface 110a is too small, which is not conducive to reducing the atomic arrangement density on the third surface 110c. Therefore, it is not conducive to improving the passivation effect of the silicon passivation layer 111 and the silicon oxide layer 121 on the third surface 110c. Therefore, designing the acute angle to be 45°~80° and controlling the tilt of the third surface 110c relative to the first surface 110a is beneficial to improving the structural stability of the cell 110 and reducing the probability of cell 110 breakage, while effectively reducing the atomic arrangement density on the third surface 110c, so as to improve the passivation effect of the silicon passivation layer 111 and the silicon oxide layer 121 on the third surface 110c.

[0059] In some examples, the acute angle formed between the plane containing the third surface 110c and the first surface 110a can be 45°~50°, for example, the acute angle can be 46°, 47°, 48° or 49°, which is beneficial to make the third surface 110c approach the fcc (111) crystal plane of the segmented cell 110. It is worth noting that, compared with other crystal planes, the fcc(111) crystal plane has the lowest atomic arrangement density and the lowest covalent bond density, and the connection between adjacent atoms is not strong. Based on this, the acute angle formed between the plane containing the third plane 110c and the first plane 110a can be designed to be 45°~50°. This is beneficial to reduce the atomic arrangement density on the third plane 110c as much as possible, and to enhance the ability of the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 to saturate the dangling bonds on the third plane 110c as much as possible. This is beneficial to further improve the passivation effect of the silicon passivation layer 111, silicon oxide layer 121 and metal oxide layer 122 on the third plane 110c, so as to further reduce the probability of carrier recombination on the third plane 110c, improve the carrier lifetime, and thus further improve the photoelectric conversion efficiency of the segmented cell 110.

[0060] In some examples, the acute angle formed between the plane containing the third face 110c and the first face 110a can also be 55°, 60°, 65°, 70°, 75° or 80°, etc.

[0061] Continue to refer to Figure 2In some embodiments, the silicon passivation layer 111 is an amorphous silicon layer or a microcrystalline silicon layer. This ensures that the low-temperature processing of the amorphous silicon layer and microcrystalline silicon layer does not affect the electrodes and various film layers on the sectional cell 110, effectively avoiding warping and reduced doping concentration of the doped layers caused by high temperatures. The doped layer can be an emitter or a doped polycrystalline silicon layer. Furthermore, the amorphous silicon layer and microcrystalline silicon layer contain hydrogen ions, which can saturate dangling bonds, thereby providing better field passivation of the cross-section and improving the photoelectric conversion efficiency of the sectional cell 110.

[0062] In some embodiments, the thickness of the silicon passivation layer 111 is 1 nm to 10 nm. If the thickness of the silicon passivation layer 111 is less than 1 nm, the thickness of the silicon passivation layer 111 is insufficient to provide a large number of hydrogen ions, thus failing to perform hydrogen passivation treatment on the cross-section. If the thickness of the silicon passivation layer 111 is greater than 10 nm, the optical absorption caused by the silicon passivation layer 111 itself is large, which affects the photoelectric conversion efficiency of the segmented cell 110. In one embodiment of this application, the thickness of the silicon passivation layer 111 is set between 1 nm and 10 nm. The silicon passivation layer 111 provides a large number of hydrogen ions and saturates the dangling bonds of the third surface 110c, reducing the carrier recombination rate of the third surface 110c. Furthermore, the silicon passivation layer 111 has less optical absorption, thereby improving the photoelectric conversion efficiency.

[0063] The thickness of the silicon passivation layer 111 can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm.

[0064] In some embodiments, the silicon passivation layer 111 can be an intrinsic crystalline silicon layer, that is, the silicon passivation layer 111 has no doped elements. In this way, the intrinsic crystalline silicon layer has weak conductivity and poor mobility for both electrons and holes, which can effectively avoid edge leakage current.

[0065] In some embodiments, the silicon passivation layer 111 can be a doped crystalline silicon layer, and the type of doped element can be the same as the doped element of the film layer of the adjacent cell 110. The elements in the doped crystalline silicon layer can be diffused from the film layer of the cell 110, or they can be retained through amorphization treatment of a portion of the film layer of the cell 110. Thus, the doped element content in the doped crystalline silicon layer is relatively low, insufficient to form diffusion channels and electric fields, thereby preventing large edge leakage currents, or even eliminating edge leakage currents altogether.

[0066] In some embodiments, the silicon passivation layer 111 can be a doped crystalline silicon layer, and the thickness of the silicon passivation layer 111 is 1nm to 10nm. Thus, the silicon passivation layer 111 itself is thin, and the content of doping elements in the doped crystalline silicon layer is small, so that a large edge leakage current will not be formed, or even there will be no edge leakage current.

[0067] The silicon passivation layer 111 is located on the third surface 110c, which includes two cases. The two cases will be explained in detail below with reference to the specific attached figures.

[0068] Figure 6 This is a third cross-sectional view of a segmented cell in a solar cell provided in an embodiment of this application; Figure 7 This is a fourth cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application; Figure 8 This is a fifth cross-sectional view of a solar cell with segmented cells provided in an embodiment of this application.

[0069] It should be noted that, Figures 6-8 The solar cell shown is a TOPCON cell. This application uses a whole solar cell as an example to illustrate the positional relationship between the silicon passivation layer 111 and the film layers in the segmented cell 110. The whole solar cell includes at least a substrate 101, a tunneling oxide layer 104 and a doped polycrystalline silicon layer 105 located on one side of the substrate 101.

[0070] Those skilled in the art can add functional films according to the specific design, for example, adding an emitter and a passivation layer on the other side of the substrate; or, for example, adding a passivation layer on the surface of the doped polysilicon layer; or, for example, adding another tunneling oxide layer and another doped polysilicon layer on the other side of the substrate.

[0071] refer to Figure 6 The cell 110 includes a substrate 101 having opposing first and second sides. The cell 110 includes an emitter 102 located on the first side of the substrate 101. The cell 110 includes a first passivation layer 103 located on the surface of the emitter 102. The cell 110 includes a tunneling oxide layer 104 located on the second side of the substrate 101, and a doped polysilicon layer 105 located on the surface of the tunneling oxide layer 104. The cell 110 includes a second passivation layer 106 located on the surface of the doped polysilicon layer 105.

[0072] It should be noted that the substrate, emitter, first passivation layer, second passivation layer, tunneling oxide layer, and doped polysilicon layer are known to those skilled in the art, and the embodiments of this application do not further describe them. The embodiments of this application use an N-type single-crystal silicon layer as an example, a P-type single-crystal silicon layer as the substrate, a silicon nitride layer as the first passivation layer, a silicon nitride layer as the second passivation layer, a silicon dioxide layer as the tunneling oxide layer, and an N-type polysilicon layer as the doped polysilicon layer.

[0073] First scenario: Reference Figure 6 The silicon passivation layer 111 is located within the cell 110, specifically inside the third surface 110c. The silicon passivation layer 111 is formed by transforming a film containing crystalline silicon crystals within the cell 110 through an amorphization process. This allows for the amorphization of the third surface 110c, thereby reducing the number of dangling bonds and resulting in a lower carrier recombination rate.

[0074] The film containing the crystalline silicon crystal can be a substrate 101, an emitter 102, and a doped polycrystalline silicon layer 105.

[0075] It should be noted that in some cases, due to the thinness of the tunneling oxide layer 104, it may be amorphized into part of the silicon passivation layer 111. In some cases, the silicon element in the tunneling oxide layer 104 is still ordered silicon and has not been transformed into unordered silicon (amorphous silicon or microcrystalline silicon), but due to its thinness, this cannot be easily seen in the diagram or in practice.

[0076] The second scenario, see reference. Figure 7 The silicon passivation layer 111 is located outside the cell 110, that is, the silicon passivation layer 111 is located outside the third surface 110c. The silicon passivation layer 111 is formed by a deposition process.

[0077] In some embodiments, reference Figure 6 or Figure 7 The end face of the silicon passivation layer 111 is flush with the first surface 110a and the second surface 110b. In some embodiments, reference... Figure 8 The silicon passivation layer 111 extends to a portion of the first surface 110a and the second surface 110b.

[0078] The silicon oxide layer 121 contains oxygen atoms, which form silicon-oxygen bonds with silicon dangling bonds. The bonding between O atoms and Si is more stable. At the same time, the transfer of electrons from Si to O passesivates the dangling bonds on the surface of the third surface 110c and the silicon passivation layer 111, thereby passivating the third surface 110c and the silicon passivation layer 111.

[0079] In some embodiments, reference Figure 2 The silicon oxide layer 121 is an amorphous silicon oxide layer. Amorphous silicon oxide absorbs less blue light, allowing more wavelengths of light to be absorbed by the sectional solar cell 110, resulting in lower optical absorption and improved photoelectric conversion efficiency. Furthermore, the amorphous silicon oxide layer exhibits good passivation thermal stability, maintaining a good passivation effect and effectively extending the lifespan of the silicon oxide layer 121 and its passivation lifetime, thus reducing the light decay efficiency of the sectional solar cell 110. The amorphous silicon oxide layer has a wide deposition process window, making it easier and more stable to form, reducing the difficulty of the fabrication process.

[0080] In some embodiments, the silicon oxide layer 121 is a crystalline silicon oxide layer. The crystalline silicon oxide layer has better optical transparency and lower optical loss, thereby reducing optical loss.

[0081] In some embodiments, the thickness of the silicon oxide layer 121 is 1 nm to 10 nm. In this way, the silicon oxide layer 121 provides more oxygen atoms and saturates the dangling bonds of the third surface 110c, thereby reducing the carrier recombination rate of the third surface 110c and thus improving the photoelectric conversion efficiency.

[0082] In some embodiments, the thickness of the silicon oxide layer 121 is 4 nm to 7 nm. The film formed by the silicon oxide layer 121 has high density, which can effectively prevent metal elements in the metal oxide layer from entering the silicon passivation layer 111 and the segmented cell 110.

[0083] Furthermore, silicon oxide materials exhibit good resistance to PID (Potential Insulation Discharge). Since the encapsulation materials of photovoltaic modules formed from solar cells cannot achieve 100% isolation from the external environment, moisture may enter the solar cell through the encapsulation material used for sealing or the backsheet in humid environments. In this case, sodium ions are generated in the glass of the encapsulation material. Under the influence of an applied electric field, these sodium ions migrate towards the surface of the solar cell, causing PID and reducing the photoelectric conversion efficiency of the solar cell. Silicon oxide materials, with their excellent density and insulation properties, are effective in preventing moisture from entering the third surface 110c and then into the cell 110, thus providing good resistance to PID. Therefore, even if the encapsulation material of the photovoltaic module cannot achieve complete insulation, and moisture enters the environment of the solar cell through the encapsulation material used for sealing, the silicon oxide film layer can prevent sodium ions in the glass of the encapsulation material from migrating towards the third surface 110c, thereby preventing PID and maintaining a high photoelectric conversion efficiency of the solar cell.

[0084] For example, the thickness of the silicon oxide layer 121 can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm.

[0085] The metal oxide layer 122 can provide metal elements, which give the metal oxide layer 122 itself a high density of fixed charge. The high density of fixed charge can generate a large electric field, thereby effectively passivating the third surface 110c. For example, it can cause a large band bending between the metal oxide layer 122 and the third surface 110c, hindering the migration of minority carriers to the third surface 110c and reducing the concentration of minority carriers at the third surface 110c. This is beneficial to reducing the recombination probability of majority carriers and minority carriers at the third surface 110c.

[0086] The formation energy of oxygen vacancies in the metal oxide layer 122 is less than that in the silicon oxide layer 121, making it easier for O atoms to migrate from the metal oxide layer 122 to the substrate and the silicon passivation layer 111, thereby further passivating the substrate and the silicon passivation layer 111 and converting some silicon dangling bonds into silicon-oxygen bonds, thus continuing to form the silicon oxide layer 121 and increasing the density of the silicon oxide layer 121. In substitutional defects, the formation energy of silicon elements substituting for metal elements in the metal oxide layer 122 is much greater than that of metal elements substituting for silicon in the silicon oxide layer 121, making it easier for metal elements to be doped into silicon oxide and release oxygen holes in the silicon oxide layer 121, further saturating dangling bonds.

[0087] In some embodiments, the metal element in the metal oxide layer 122 is an amorphous metal element. This allows the metal oxide layer 122 to be formed using a low-temperature process, thereby avoiding the thermal damage problems associated with high-temperature processing.

[0088] In some embodiments, the metal element in the metal oxide layer 122 can be any one or more of elements such as Al, Ti, Zn, Zr, Hf, Mo, W, or Ni.

[0089] In some embodiments, the thickness of the metal oxide layer 122 can be 20 nm to 100 nm. The thickness of the metal oxide layer 122 can be 20 nm to 40 nm, 40 nm to 60 nm, 60 nm to 80 nm, or 80 nm to 100 nm. For example, the thickness of the metal oxide layer 122 can be 23 nm, 38 nm, 45 nm, 56 nm, 69 nm, 83 nm, 91 nm, or 99 nm.

[0090] Figure 9 This is a sixth cross-sectional view of the segmented cell 110 in a solar cell provided in an embodiment of this application.

[0091] In some embodiments, the solar cell further includes: an intermediate passivation layer 123, which is located between the silicon oxide layer 121 and the metal oxide layer 122, and the intermediate passivation layer 123 contains at least one of the silicon element in the silicon oxide layer 121 or the metal element in the metal oxide layer 122.

[0092] In some embodiments, the thickness of the intermediate passivation layer 123 can be 4 nm to 15 nm. The thickness of the intermediate passivation layer 123 can be 4 nm, 6 nm, 8 nm, 10 nm, 11 nm, 12 nm, 13 nm or 14 nm.

[0093] In some embodiments, the intermediate passivation layer 123 contains metal elements, and the metal elements increase in number along the direction from the silicon oxide layer 121 to the metal oxide layer 122.

[0094] The solar cell provided in this application embodiment has a silicon passivation layer 111 disposed on the third surface 110c of the segmented cell 110. The silicon passivation layer 111 passivates dangling bonds, thereby reducing the number of dangling bonds on the cross-section of the segmented cell 110. This prevents the reduction in photoelectric conversion efficiency caused by the capture and recombination of light-excited minority carriers after they reach the surface. It effectively hydrogenates dangling bonds and reduces surface defects, significantly improving minority carrier lifetime, increasing open-circuit voltage, and ultimately improving photoelectric conversion efficiency. Furthermore, a silicon oxide layer 121 and a metal oxide layer 122 are disposed on the silicon passivation layer 111. The silicon oxide layer 121 provides chemical passivation, and the metal oxide layer 122 provides both field passivation and chemical passivation, thereby reducing the recombination rate on the cross-section and improving the photoelectric conversion efficiency of the segmented cell 110.

[0095] Furthermore, the crystals in the silicon passivation layer 111 have a disordered structure or are mostly disordered, resulting in low electron and hole migration rates and poor lateral conductivity. This effectively avoids short circuits and leakage currents caused by the silicon passivation layer 111 on the first side 110a and the second side 110b of the segmented cell 110, thereby improving the photoelectric conversion efficiency of the solar cell.

[0096] Accordingly, according to some embodiments of this application, another aspect of the embodiments of this application also provides a method for preparing a solar cell, which is used to prepare the solar cell provided in the above embodiments. The same or corresponding technical features as those in the above embodiments will not be described in detail here.

[0097] Preparation methods include: (reference) Figure 1 Provides a whole solar cell 100, which includes a front side and a back side arranged opposite to each other.

[0098] Figure 10This is a cross-sectional view of a method for fabricating a solar cell according to an embodiment of this application, in which a segmented cell is formed.

[0099] refer to Figure 10 The preparation method includes: dividing the entire solar cell along a first direction to form at least two segmented cells 110. Each segmented cell 110 includes a first surface 110a, a second surface 110b, and a third surface 110c connecting the first surface 110a and the second surface 110b. The first surface 110a is a portion of the front side of the entire solar cell, the second surface 110b is a portion of the back side of the entire solar cell, and the third surface 110c is a cross-section of the segmented cell 110 along the divided surface.

[0100] Preparation methods include: (reference) Figure 2 A silicon passivation layer 111 is formed, and the silicon passivation layer 111 is located on the third surface 110c.

[0101] In some embodiments, the reaction temperature for forming the silicon passivation layer 111 is less than or equal to 300°C.

[0102] In some embodiments, reference Figure 6 The entire solar cell 100 includes a substrate 101, which is laser-processed to convert a portion of the substrate 101 into a silicon passivation layer 111.

[0103] In some embodiments, the laser processing parameters include: laser wavelength of 300nm~550nm, pulse width of 5ps~100ns, laser power of 1W~25W, pulse frequency of 50kHz~1250kHz, and spot area of ​​5000um. 2 ~50000um 2 The scanning speed is 300mm / s to 80000mm / s.

[0104] In some embodiments, reference Figure 7 A silicon passivation layer 111 is formed using a deposition process.

[0105] In some embodiments, reference Figure 8 The silicon passivation layer 111 also extends to a portion of the width of the first surface 110a and the second surface 110b.

[0106] In some embodiments, a silicon passivation layer 111 is formed using a plasma deposition process to contain hydrogen ions within the silicon passivation layer 111. The hydrogen ions can passivate the third surface 110c, passivating the surface dangling bonds of the third surface 110c and reducing the photoelectric conversion efficiency loss caused by recombination.

[0107] In some embodiments, after forming the silicon passivation layer 111, the silicon passivation layer 111 is subjected to hydrogen plasma treatment to increase the hydrogen ion content within the silicon passivation layer 111. By treating the silicon passivation layer 111 with hydrogen ions, the final silicon passivation layer 111 after hydrogen ion treatment has a higher hydrogen ion content. The hydrogen ions can then combine with dangling bonds on the third surface 110c to form non-recombination centers, thereby achieving a good passivation effect.

[0108] In some embodiments, the hydrogen plasma treatment process includes: in the chamber where the silicon passivation layer 111 is formed, after the silicon passivation layer 111 is formed, a hydrogen source gas is continuously introduced, the flow rate of the hydrogen source gas is 5000 sccm to 15000 sccm, and the radio frequency power is 10000W to 15000W.

[0109] The preparation method includes: forming a silicon oxide layer 121, wherein the silicon oxide layer 121 is located on the surface of the silicon passivation layer 111.

[0110] In some embodiments, the reaction temperature for forming the silicon oxide layer 121 is less than or equal to 300°C.

[0111] The preparation method includes: forming a metal oxide layer 122, wherein the metal oxide layer 122 is located on the silicon oxide layer 121.

[0112] In some embodiments, the reaction temperature for forming the metal oxide layer 122 is less than or equal to 300°C.

[0113] It should be noted that the above embodiments use the silicon passivation layer 111 as an example of having hydrogen ions. During the deposition process of the metal oxide layer 122, hydrogen ions can also be formed using a nitrogen or hydrogen source. The working principle of the hydrogen atoms is the same as that of the hydrogen ions in the silicon passivation layer 111, meaning that a large amount of hydrogen also exists within the metal oxide layer 122, which can also chemically passivate the third surface 110c. Alternatively, the hydrogen ion content within the metal oxide layer 122 can be increased by performing hydrogen plasma treatment on the metal oxide layer 122.

[0114] Accordingly, according to some embodiments of this application, another aspect of this application also provides a photovoltaic module, which includes the solar cell provided in the above embodiments.

[0115] Figure 11 This is a cross-sectional view of a photovoltaic module provided in an embodiment of this application.

[0116] refer to Figure 11The photovoltaic module includes: a battery string, which is formed by connecting multiple solar cells 201 as described in any of the above embodiments or solar cells 201 prepared by any of the above embodiments; an encapsulating film 203 for covering the surface of the battery string; and a cover plate 204 for covering the surface of the encapsulating film 203 facing away from the battery string.

[0117] Specifically, in some embodiments, multiple solar cells can be electrically connected via a connecting member 202, which is welded to a main grid on the solar cell. In some embodiments, the connecting member 202 is welded to a sub-grid on the solar cell, the sub-grid including a first electrode and a second electrode.

[0118] In some embodiments, there is no spacing between the solar cells, meaning that the solar cells overlap each other.

[0119] In some embodiments, the encapsulating film 203 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, and the second encapsulating layer covers the other of the front or back sides of the solar cell. 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.

[0120] It is worth noting that the first encapsulation layer and the second encapsulation layer still have a dividing 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 203.

[0121] In some embodiments, the cover plate 204 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 204 facing the encapsulating film 203 can be an uneven surface, thereby increasing the utilization rate of incident light. The cover plate 204 includes a first cover plate and a second cover plate, wherein the first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer; or the first cover plate is opposite to one side of the solar cell, and the second cover plate is opposite to the other side of the solar cell.

[0122] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: Segmented cells, at least two of the segmented cells are formed by dividing the same whole solar cell along a first direction. Each segmented cell includes a first surface, a second surface, and a third surface connecting the first surface and the second surface. The first surface is a portion of the front side of the whole solar cell, the second surface is a portion of the back side of the whole solar cell, and the third surface is the cross-section of the segmented cell along the division process. The angle between the first surface and the third surface is an acute angle; A silicon passivation layer, wherein the silicon passivation layer is located on the third surface; A silicon oxide layer, wherein the silicon oxide layer is located on the surface of the silicon passivation layer; A metal oxide layer is located on the silicon oxide layer.

2. The solar cell according to claim 1, characterized in that, The silicon passivation layer is an amorphous silicon layer or a microcrystalline silicon layer; the thickness of the crystalline silicon layer is 1 nm to 10 nm.

3. The solar cell according to claim 1 or 2, characterized in that, The metal oxide layer is prepared by a low-temperature process.

4. The solar cell according to claim 1, characterized in that, Also includes: An intermediate passivation layer is located between the silicon oxide layer and the metal oxide layer, and the intermediate passivation layer contains at least one of the silicon element in the silicon oxide layer or the metal element in the metal oxide layer.

5. The solar cell according to claim 4, characterized in that, The intermediate passivation layer contains the metal element, and the metal element increases in number along the direction from the silicon oxide layer to the metal oxide layer.

6. A method for preparing a solar cell, characterized in that, include: A complete solar cell is provided, the complete solar cell including a front side and a back side disposed opposite to each other; The entire solar cell is divided along a first direction to form at least two cell segments. Each cell segment includes a first surface, a second surface, and a third surface connecting the first surface and the second surface. The first surface is a portion of the front side of the entire solar cell, the second surface is a portion of the back side of the entire solar cell, and the third surface is the cross-section of the cell segment after the division process. The angle between the first surface and the third surface is an acute angle; A silicon passivation layer is formed, wherein the silicon passivation layer is located on the third surface; A silicon oxide layer is formed on the surface of the silicon passivation layer; A metal oxide layer is formed on the silicon oxide layer.

7. The preparation method according to claim 6, characterized in that, The reaction temperature for forming the silicon passivation layer, the silicon oxide layer, and the metal oxide layer is less than or equal to 300°C.

8. The preparation method according to claim 6, characterized in that, The entire solar cell includes a substrate, which is laser-processed to convert a portion of the substrate into the silicon passivation layer.

9. The preparation method according to claim 8, characterized in that, The laser processing parameters include: laser wavelength of 300nm~550nm, pulse width of 5ps~100ns, laser power of 1W~25W, pulse frequency of 50kHz~1250kHz, and spot area of ​​5000um. 2 ~50000um 2 The scanning speed is 300mm / s to 80000mm / s.

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