Solar cell, cell module, and photovoltaic system

Abstract

The present application is applicable to the technical field of solar cells, and provides a solar cell (100), a cell module (200), and a photovoltaic system (1000). In the solar cell (100), a P-type doped layer (20) and an N-type doped layer (30) are disposed on a first surface (11) of a silicon wafer (10), and the thickness of a passivation film layer (40) on at least part of the N-type doped layer (30) is greater than the thickness of at least part of the passivation film layer (40) on the P-type doped layer (20). In this way, a coordinated optimization design of different thicknesses is performed on the passivation film layer (40) on the at least part of the N-type doped layer (30) and on the at least part of the P-type doped layer (20), and the passivation film layer (40) on the at least part of the N-type doped layer (30) has a thicker thickness, so that the passivation effects in different doped regions of the solar cell (100) can be better matched, thereby reducing material usage and costs while improving the performance of the solar cell (100).

Description

Solar cell, cell module and photovoltaic system

[0001] Priority information

[0002] This application claims priority to and the benefit of the filing date of Chinese Patent Application No. 202411000880.2, filed July 24, 2024, in the State Intellectual Property Office of China, and is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of solar cells, and in particular to a solar cell, a cell module and a photovoltaic system. BACKGROUND

[0004] Solar cell power generation is a sustainable clean energy source that can convert sunlight into electrical energy using the photovoltaic effect of a semiconductor p-n junction. In a solar cell, a P-type doped layer and an N-type doped layer are provided on a silicon wafer, and a passivation film layer is provided on each of the doped layers to passivate the cell. SUMMARY

[0005] The present application provides a solar cell, a cell module and a photovoltaic system.

[0006] The present application is implemented in the following manner. The solar cell of an embodiment of the present application comprises:

[0007] a silicon wafer having opposite first and second surfaces;

[0008] a P-type doped layer and an N-type doped layer provided on the first surface of the silicon wafer; and

[0009] a passivation film layer provided on each of the P-type doped layer and the N-type doped layer; wherein the passivation film layer on at least a portion of the N-type doped layer has a first thickness, and the passivation film layer on at least a portion of the P-type doped layer has a second thickness, the first thickness being greater than the second thickness.

[0010] The present application also provides a cell module comprising a plurality of the solar cell described in any one of the above.

[0011] The present application also provides a photovoltaic system comprising the cell module described above.

[0012] In the solar cell, the solar cell module and the photovoltaic system provided in the embodiments of the present application, the P-type doped layer and the N-type doped layer are arranged on the first surface of the silicon wafer, and the thickness of the passivation film layer on at least part of the N-type doped layer is greater than the thickness of the passivation film layer on at least part of the P-type doped layer. In this way, by optimizing the thickness of the passivation film layer on at least part of the N-type doped layer and at least part of the P-type doped layer, and by making the thickness of the passivation film layer on at least part of the N-type doped layer greater, the passivation effect of the different doped regions of the solar cell can be optimized, so as to improve the performance of the solar cell, and meanwhile, the use of materials can be saved and the cost can be reduced.

[0013] Additional aspects and advantages of the present application will be made apparent by the following description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 is a schematic diagram of a module of a photovoltaic system according to an embodiment of the present application;

[0015] Fig. 2 is a schematic diagram of a cross-sectional structure of a solar cell according to an embodiment of the present application;

[0016] Fig. 3 is a schematic diagram of a planar structure of a partial structure of a solar cell according to an embodiment of the present application;

[0017] Fig. 4 is a schematic diagram of a cross-sectional structure of a solar cell in a middle region according to an embodiment of the present application;

[0018] Fig. 5 is a schematic diagram of a structure of a passivation film layer according to an embodiment of the present application;

[0019] Fig. 6 is another schematic diagram of a cross-sectional structure of a solar cell in a middle region according to an embodiment of the present application;

[0020] Fig. 7 is still another schematic diagram of a cross-sectional structure of a solar cell in a middle region according to an embodiment of the present application;

[0021] Fig. 8 is yet another schematic diagram of a cross-sectional structure of a solar cell in a middle region according to an embodiment of the present application;

[0022] Fig. 9 is still yet another schematic diagram of a cross-sectional structure of a solar cell in a middle region according to an embodiment of the present application. Embodiments of the present application

[0023] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. It should be noted that the embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and should not be understood as a limitation on the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0024] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "side" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0025] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "several" is two or more, unless otherwise explicitly specified and limited.

[0026] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "above", "over" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0027] The disclosure hereafter provides a number of different embodiments or examples for implementing various aspects of the present application. In the interest of simplifying the present disclosure, the components and arrangements of certain examples are described below. These are, of course, merely examples and are not intended to limit the present application. Moreover, the present application can employ a number of components, materials, and methods similar to those described below, and none such employments are a departure from the spirit and scope of the present application. Additionally, the present application provides a number of specific examples of various processes and materials, but one of ordinary skill in the art can recognize that other processes can be employed and / or other materials can be used.

[0028] Referring to FIG. 1, a photovoltaic system 1000 in embodiments of the present application can include a battery assembly 200 in embodiments of the present application, the battery assembly 200 in embodiments of the present application can include a plurality of solar cell pieces 100 in embodiments of the present application, the plurality of solar cell pieces 100 can be connected together by solder strips to form a plurality of cell strings, and each cell string can form the battery assembly 200 by being connected in series, in parallel, or in series-parallel.

[0029] Referring to FIG. 2, the solar cell piece 100 in embodiments of the present application can include a silicon wafer 10, a P-type doped layer 20, an N-type doped layer 30, and a passivation film layer 40.

[0030] The silicon wafer 10 has a first surface 11 and a second surface 12 opposite to each other, the P-type doped layer 20 and the N-type doped layer 30 are both disposed on the first surface 11 of the silicon wafer 10, and the passivation film layer 40 covers the first surface 11, and the P-type doped layer 20 and the N-type doped layer 30 are both disposed with the passivation film layer 40.

[0031] As shown in FIG. 2, the passivation film layer 40 on at least a partial region of the N-type doped layer 30 has a first thickness D1, the passivation film layer 40 on at least a partial region of the P-type doped layer 20 has a second thickness D2, and the first thickness D1 is greater than the second thickness D2.

[0032] In related technologies, in a solar cell piece, a P-type doped layer and an N-type doped layer are disposed on a silicon wafer, and a passivation film layer is disposed on each doped layer to passivate the cell. However, in current solar cell pieces, the cooperation between the passivation film layers on the P-type doped layer and the N-type doped layer is not fully optimized, so as to improve the passivation effect, and therefore, the performance of current solar cell pieces is poor.

[0033] In the solar cell sheet 100, the cell assembly 200 and the photovoltaic system 1000 in the embodiments of the present application, the P-type doped layer 20 and the N-type doped layer 30 are arranged on the first surface 11 of the silicon sheet 10, and the thickness of the passivation film layer 40 on at least part of the N-type doped layer 30 is greater than the thickness of the passivation film layer 40 on at least part of the P-type doped layer 20, that is, the first thickness D1 is greater than the second thickness D2. In this way, by optimizing the design of the passivation film layer 40 on at least part of the N-type doped layer 30 and at least part of the P-type doped layer 20 in different thicknesses, and the thickness of the passivation film layer 40 on at least part of the N-type doped layer 30 being thicker, the passivation effect of different doped regions of the solar cell sheet 100 can achieve a better matching effect, thereby improving the performance of the solar cell sheet 100, while also saving material use and reducing costs.

[0034] Specifically, in the embodiments of the present application, the first surface 11 can be the back surface of the silicon sheet 10, and the second surface 12 can be the front surface of the silicon sheet 10. The solar cell sheet 100 is preferably a back contact solar cell sheet. Of course, in some embodiments, the solar cell sheet 100 can also be other types of cell sheets having both P-type doped layer 20 and N-type doped layer 30 on the same surface, which is not limited here.

[0035] The silicon sheet 10 can be a P-type silicon sheet or an N-type silicon sheet, which is not limited here. The P-type doped layer 20 can be a P-type doped polysilicon layer, a P-type doped microcrystalline silicon layer, etc., and the N-type doped layer 30 can be an N-type doped polysilicon layer, an N-type doped microcrystalline silicon layer, etc., which are not limited here. The P-type doped layer 20 and the N-type doped layer 30 can be prepared by diffusion, deposition, etc., which is not limited here.

[0036] It should be noted that in the present application, the thickness of the passivation film layer 40 on the N-type doped layer 30 refers to the thickness of the passivation film layer 40 on all surfaces of the N-type doped layer 30 covered by the passivation film layer 40, and similarly, the thickness of the passivation film layer 40 on the P-type doped layer 20 refers to the thickness of the passivation film layer 40 on all surfaces of the P-type doped layer 20 covered by the passivation film layer 40.

[0037] In addition, in this document, a certain film layer covering a certain surface or a certain film layer can be that the film layer is directly stacked on the surface or the certain film layer, or that there is another film layer between the film layer and the surface or the film layer, and the covering only means to define the specific arrangement range of the film layer.

[0038] It can be understood that in the back contact solar cell, the first surface 11 has a plurality of P-type doped layers 20 and a plurality of N-type doped layers 30, and the plurality of P-type doped layers 20 and the plurality of N-type doped layers 30 are arranged alternately in sequence. In addition, it can be understood that in the back contact solar cell, a tunneling layer (not shown) can also be arranged between the P-type doped layer 20 and the N-type doped layer 30 and the silicon wafer 10.

[0039] Please refer to FIG. 2 and FIG. 4, in some embodiments, the first surface 11 has an edge region 111 and a middle region 112, the middle region 111 is located inside the edge region 112, and the edge region 111 is closer to the edge of the first surface 11 than the middle region 112.

[0040] In the above embodiments, the passivation film layer 40 on the portion of the N-type doped layer 30 on the middle region 112 has a first thickness D1, and the passivation film layer 40 on the portion of the P-type doped layer 20 on the middle region 112 has a second thickness D2.

[0041] In this way, the passivation effect of the area corresponding to the N-type doped layer 30 and the P-type doped layer 20 at the middle region 112 position can be optimized, thereby improving the performance of the solar cell 100.

[0042] Specifically, as shown in FIG. 2, in such embodiments, the silicon wafer 10 further includes a plurality of side surfaces 13 connecting the first surface 11 and the second surface 12, the edge region 111 is located at the edge position where the first surface 11 and the side surface 13 meet, and the middle region 112 is located at the middle position of the first surface 11, and the edge region 111 is located between the middle region 112 and the side surface 13.

[0043] As shown in FIG. 2, the "edge region 111" refers to the region adjacent to the edge where the first surface 11 and the side surface 13 meet, and the "middle region 112" refers to the region of the first surface 11 other than the edge region 111.

[0044] As shown in FIG. 3 (the passivation film layer 40 is not shown in FIG. 3), in some embodiments, the middle region 112 and the edge region 111 can be arranged as shown in FIG. 3, in such embodiments, the edge region 111 can be arranged around the middle region, that is, the edge of the first surface 11 has the edge region 111 at the junction with all the side surfaces 13, and the middle region 112 is located inside the edge region 110, that is, the edge region 111 is the region located at each edge position of the first surface 11.

[0045] Of course, in some embodiments, there can also be no edge region at the edge where the first surface 11 meets the side surface 13, for example, in one possible embodiment, after cutting is completed, a cutting surface will be formed on the half-cell, the cutting surface is also the side surface 13, in such a case, the edge where the first surface 11 meets the cutting surface has no edge region 110, while the edge regions 110 are present around the other edges.

[0046] Referring to FIG. 2, in some embodiments, the passivation film layer 40 on the portion of the N-type doped layer 30 on the edge region 111 has a third thickness D3, the passivation film layer 40 on the portion of the P-type doped layer 20 on the edge region 111 has a fourth thickness D4, the third thickness D3 is greater than the first thickness D1, and the fourth thickness D4 is greater than the second thickness D2.

[0047] In this way, by setting the thickness of the passivation film layer on the doped layer on the edge region 111 to be thicker, the passivation effect of the edge region 111 can be improved, the edge recombination can be reduced, and the efficiency of the solar cell 100 can be further improved.

[0048] Further, in such embodiments, the third thickness D3 can be greater than the fourth thickness D4. In this way, by optimizing the design of the passivation film layer 40 on the N-type doped layer 30 and the P-type doped layer 20 of the edge region 111 in different thicknesses, and the thickness of the passivation film layer 40 on the N-type doped layer 30 being thicker, the passivation effect of the edge region 11 can be optimized.

[0049] In some embodiments, the passivation film layer 40 covering the middle region 112 is a one-piece continuous structure.

[0050] In this way, the passivation film layer 40 on this portion can be prepared by PECVD process in one-time, and in the preparation process, different thicknesses of different regions can be achieved by controlling the electrical conductivity of different regions.

[0051] Specifically, in this article, the "one-piece continuous structure" refers to the fact that the material and structure of the passivation film layer 40 on each portion are the same, and the passivation film layer 40 on each portion is prepared by one process to form a whole layer of continuous film, only the thicknesses of different regions are different. In the following, if the same description appears, please refer to this processing solution.

[0052] It can be understood that in the solar cell 100, the metal electrode also penetrates the passivation film layer 40 and contacts the doped layer, that is, in the subsequent preparation process, the passivation film layer 40 at the position corresponding to the metal electrode is removed or ablated when the metal electrode is made. Specifically, in the back contact solar cell, the P-type electrode and the N-type electrode (not shown in the figure) are provided, the P-type electrode penetrates the passivation film layer 40 and contacts the P-type doped layer 20, and the N-type electrode penetrates the passivation layer 20 and contacts the N-type doped layer 13.

[0053] Referring to FIG. 5, in some embodiments, the passivation film layer 40 located in the middle region 112 can include the first type passivation sub-layer 41 and the second type passivation sub-layer 42 arranged in a stack, and the thickness of the passivation film layer 40 located in the middle region 112 is the sum of the thicknesses of the first type passivation sub-layer 41 and the second type passivation sub-layer 42.

[0054] In the above embodiment, the thickness of the first type passivation sub-layer 41 located on the N-type doped layer 30 is greater than the thickness of the first type passivation sub-layer 41 located on the P-type doped layer 20.

[0055] In this way, on the one hand, the passivation film layer 40 on the middle region 112 adopts the structure of different types of passivation sub-layers, which can improve the passivation effect, and on the other hand, by setting the thickness of the first type passivation sub-layer 41 located on the N-type doped layer 30 to be greater than the thickness of the first type passivation sub-layer 41 located on the P-type doped layer 20, the thickness of the passivation film layer 40 on the middle region 112 located on the N-type doped layer 30 can be greater than the thickness of the passivation film layer 40 on the middle region 112 located on the P-type doped layer 20.

[0056] Further, in such embodiments, the thickness of the second type passivation sub-layer 42 located on the N-type doped layer 30 is equal to the thickness of the second type passivation sub-layer 42 located on the P-type doped layer 20.

[0057] In some embodiments, the first type passivation sub-layer 41 is prepared by a PECVD process or a thermal growth process, and the second type passivation sub-layer 42 is prepared by an atomic deposition process.

[0058] Specifically, in the embodiments of the present application, the first type passivation sub-layer 41 can include at least one of a silicon oxide film layer, a silicon nitride film layer, and a silicon oxynitride film layer, and the second type passivation sub-layer 42 can include an aluminum oxide film layer. As shown in FIG. 4,

[0059] As shown in FIG. 5, in some embodiments, the passivation film layer 40 on the intermediate region 112 can adopt a three-layer stacked structure of a silicon oxide film layer 401, an aluminum oxide film layer 402, and a silicon nitride film layer 403, the thickness of the aluminum oxide film layer 401 on the P-type doped layer 20 and the N-type doped layer 30 can be substantially the same, the thickness of the silicon oxide film layer 401 on the N-type doped layer 30 can be greater than the thickness of the silicon oxide film layer 401 on the P-type doped layer 20, and the thickness of the silicon nitride film layer 403 on the N-type doped layer 30 can be greater than the thickness of the silicon nitride film layer 403 on the P-type doped layer 20.

[0060] Of course, in some embodiments, the passivation film layer 40 on the intermediate region 112 can also adopt a two-layer stacked structure of only the aluminum oxide film layer 402 and the silicon nitride film layer 403, the thickness of the aluminum oxide film layer 401 on the P-type doped layer 20 and the N-type doped layer 30 can be substantially the same, and the thickness of the silicon nitride film layer 403 on the N-type doped layer 30 can be greater than the thickness of the silicon nitride film layer 403 on the P-type doped layer 20.

[0061] Further, it should be noted that, in some embodiments, the silicon nitride film layer 403 can be a single-layer film structure or a multi-layer film structure composed of multiple layers of silicon nitride layers with different refractive indexes, which is not limited in particular herein.

[0062] Further, in some embodiments, in the solar cell wafer 100, the silicon oxide film layer can be a plurality of silicon oxide layers stacked in sequence, the silicon nitride film layer can be a plurality of silicon nitride layers stacked in sequence, and the silicon oxynitride film layer can be a plurality of silicon oxynitride layers stacked in sequence. That is, in some possible embodiments, the silicon oxide film layer, the silicon nitride film layer, and the silicon oxynitride film layer can all be multi-layer structures.

[0063] In some embodiments, the ratio of the first thickness D1 to the second thickness D2 is greater than 1 and less than or equal to 2, that is, 1 < D1 / D2 ≤ 2.

[0064] In this way, the passivation film layer 40 on the N-type doped layer 30 on the intermediate region 112 has a greater thickness, which can improve the passivation effect of the corresponding region of the N-type doped layer 30, so that the passivation effects of the corresponding regions of the P-type doped layer 20 and the N-type doped layer 30 achieve a relatively optimal matching effect, thereby improving the performance of the solar cell wafer 100.

[0065] Specifically, in such embodiments, the ratio of the first thickness D1 to the second thickness D2 can be, for example, 1.01, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2, or any value greater than 1 and less than or equal to 2, which is not limited in particular herein.

[0066] In some embodiments, the ratio of the first thickness D1 to the second thickness D2 can preferably be in the range of 1.025-1.6. Through repeated research and verification by the inventors of the present application, it is found that setting the ratio of the first thickness D1 to the second thickness D2 in this preferred range can make the passivation effect of the regions corresponding to the P-type doped layer 20 and the N-type doped layer 30 reach the optimal matching effect while keeping the cost relatively low.

[0067] Specifically, in such embodiments, the preferred ratio of the first thickness D1 to the second thickness D2 can be, for example, 1.025, 1.03, 1.04, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, or any value in the range of 1.025-1.6.

[0068] In some embodiments, the difference between the first thickness D1 and the second thickness D2 can be in the range of 2nm-50nm. In this way, by reasonably designing the difference between the two thicknesses, the passivation effect of the regions corresponding to the P-type doped layer 20 and the N-type doped layer 30 can reach a relatively optimal matching effect, thereby improving the performance of the solar cell 100.

[0069] In such embodiments, the difference between the first thickness D1 and the second thickness D2 can preferably be in the range of 5nm-30nm. Through repeated research and verification by the inventors of the present application, it is found that setting the difference between the first thickness D1 and the second thickness D2 in this preferred range can make the passivation effect of the regions corresponding to the P-type doped layer 20 and the N-type doped layer 30 reach the optimal matching effect while keeping the cost relatively low.

[0070] Specifically, in such embodiments, the difference between the first thickness D1 and the second thickness D2 can preferably be in the range of 5nm, 7nm, 9nm, 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, 22nm, 24nm, 26nm, 28nm, 30nm, or any value in the range of 5nm-30nm.

[0071] In some embodiments, the first thickness D1 can be in the range of 52nm-250nm, and the second thickness D2 can be in the range of 50nm-200nm. In this way, setting the first thickness D1 and the second thickness D2 in the above ranges can make the passivation film layer 40 achieve good passivation effect while keeping the cost relatively low.

[0072] In such embodiments, the first thickness D1 can be preferably 55nm-230nm, and the second thickness D2 can be 50nm-200nm. Through repeated research and verification by the inventors of the present application, it is found that by setting the sizes of the first thickness D1 and the second thickness D2 in this preferred range, the passivation effects of the corresponding regions of the P-type doped layer 20 and the N-type doped layer 30 can be optimally matched, and the cost can also be relatively low.

[0073] In a preferred embodiment, the first thickness D1 is preferably 55nm-230nm, the second thickness D2 is preferably 50nm-200nm, the difference between the first thickness D1 and the second thickness D2 is preferably 5nm-30nm, and the ratio of the first thickness D1 to the second thickness D2 is preferably 1.025-1.6. In this way, the passivation effects of the corresponding regions of the P-type doped layer 20 and the N-type doped layer 30 can be optimally matched, and the cost can also be relatively low.

[0074] Referring to FIG. 4, in some embodiments, the solar cell 100 is a back contact solar cell, and in such cases, on the middle region 112, there is a spacing region 120 between the adjacent P-type doped layer 20 and N-type doped layer 30, and the passivation film layer 40 also covers the spacing region 120, and the part of the passivation film layer 40 at the spacing region 120 has a fifth thickness D5, wherein the first thickness D1 is greater than the second thickness D2, and the second thickness D2 is greater than the fifth thickness D5.

[0075] In this way, by reasonably optimizing the thicknesses of the N-type doped layer 30, the P-type doped layer 20, and the passivation film layer 40 on the spacing region 120 between the N-type doped layer 30 and the P-type doped layer 20 on the middle region 112, the passivation effects of the corresponding regions can be well matched, and the electrical performance of the solar cell 100 can be improved at a relatively low cost.

[0076] In such embodiments, on the middle region 112, the passivation film layer 40 on the P-type doped layer 20, the passivation film layer 40 on the N-type doped layer 30, and the passivation film layer 40 at the spacing region 120 are in an integrated and continuous structure. In this way, they can be directly prepared at one time through the PECVD process, and during the preparation process, different thicknesses of different regions can be achieved by controlling the electrical conductivity of different regions.

[0077] Further, in some embodiments, the ratio of the second thickness D2 to the fifth thickness D5 can be greater than 1 and less than 2, i.e., 1

[0078] Therefore, the thicknesses of the fifth thickness D5, the second thickness D2 and the first thickness D1 are gradually thickened and designed according to the above-mentioned ratio, so that the passivation effect of the entire solar cell 100 can achieve an optimal matching effect, thereby improving the performance of the solar cell 100, and the cost is relatively low.

[0079] Specifically, in such an embodiment, the ratio of the second thickness D2 to the fifth thickness D5 may, for example, be 1.01, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2, or any value between greater than 1 and less than or equal to 2, which is not particularly limited herein.

[0080] In some embodiments, in the back contact solar cell, the ratio of the second thickness D2 to the fifth thickness D5 may be preferably 1.1-1.8. Through repeated research and verification by the inventors of the present application, it is found that by setting the ratio of the second thickness D2 to the fifth thickness D5 in this preferred range, the passivation effect of the corresponding regions of the P-type doped layer 20, the N-type doped layer 30 and the spacing region 120 can achieve an optimal matching effect, and the cost is relatively low.

[0081] Specifically, in such an embodiment, the preferred ratio of the second thickness D2 to the fifth thickness D5 may, for example, be 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, or any value between 1.1 and 1.8.

[0082] In some embodiments, the difference between the second thickness D2 and the fifth thickness D5 may be 2nm-50nm. In this way, by reasonably designing the thickness difference between the two, the passivation effect of the region of the solar cell 100 can achieve an optimal matching effect, thereby improving the performance of the solar cell 100.

[0083] In such an embodiment, the difference between the second thickness D2 and the fifth thickness D5 may be preferably 20nm-40nm. Through repeated research and verification by the inventors of the present application, it is found that in the back contact solar cell, by setting the difference between the second thickness D2 and the fifth thickness D5 in this preferred range, the passivation effect of the corresponding regions of the P-type doped layer 20, the N-type doped layer 30 and the spacing region 120 can achieve an optimal matching effect, thereby improving the performance of the solar cell 100, and the cost is relatively low.

[0084] Specifically, in such embodiments, the difference between the second thickness D2 and the fifth thickness D5 can preferably be 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, or any value between 20 nm and 40 nm.

[0085] In some embodiments, the second thickness D2 can be 50 nm-200 nm, and the fifth thickness D5 can be 48 nm-150 nm. In this way, by setting the second thickness D2 and the fifth thickness D5 within the above ranges, the passivation film layer 40 can achieve good passivation effects and is relatively low in cost.

[0086] In such embodiments, the second thickness D2 can be 50 nm-200 nm, and the fifth thickness D5 can preferably be 30 nm-160 nm. Specifically, through repeated research and verification by the inventors of the present application, it has been found that by setting the second thickness D2 and the fifth thickness D5 within this preferred range, the passivation effects of the regions corresponding to the P-type doped layer 20, the N-type doped layer 30, and the spacing region 120 can achieve optimal matching effects, and the cost is also relatively low.

[0087] In a preferred embodiment, the first thickness D1 is preferably 55 nm-230 nm, the second thickness D2 is preferably 50 nm-200 nm, the fifth thickness D5 is preferably 30 nm-160 nm, the difference between the first thickness D1 and the second thickness D2 is preferably 5 nm-30 nm, the difference between the second thickness D2 and the fifth thickness D5 is preferably 20 nm-40 nm, the ratio of the first thickness D1 to the second thickness D2 is preferably 1.025-1.6, and the ratio of the second thickness D2 to the fifth thickness D5 is preferably 1.1-1.8. In this way, the passivation effects of the regions corresponding to the P-type doped layer 20, the N-type doped layer 30, and the spacing region 120 in the middle region 112 can achieve optimal matching effects, the performance of the solar cell sheet 100 is improved, and the cost is also relatively low.

[0088] In some embodiments, the resistivity of the silicon sheet 10 is greater than 20 ohm.cm, and the difference between the second thickness D2 and the fifth thickness D5 is 10 nm-60 nm.

[0089] In this way, when the silicon sheet 10 is a high-resistance silicon sheet 10 with a resistivity greater than 20 ohm.cm, by setting the difference between the second thickness D2 and the fifth thickness D5 within this range, the passivation effect of the spacing region 120 can be ensured, and the passivation effect of the region corresponding to the P-type doped layer 20 can also be brought to a better state.

[0090] Referring to FIG. 6, in some embodiments, the interval region 120 is a trench 121 formed on the back surface 12 (i.e., the trench 121 is formed on the back surface 12 of the silicon wafer 10, and the P-type doped layer 20 and the N-type doped layer 30 are separated by the trench 121), and the passivation film layer 40 covers the side surface 1211 and the bottom surface 1222 of the trench 121, and the thickness of at least a portion of the passivation film layer 40 on the side surface 1211 of the trench 121 is greater than the thickness of the passivation film layer 40 on the bottom surface 1212 of the trench 121.

[0091] In this way, the passivation matching effect at the trench 121 can be improved, and thus the overall passivation performance can be improved, and the performance of the solar cell wafer 100 can be improved.

[0092] Specifically, in such embodiments, at the doped layer on both sides of the trench 121, the P-type doped layer 20 generally forms a P-type inner expansion layer (not shown in the figure) in the silicon wafer 10, and the N-type doped layer 30 generally forms an N-type inner expansion layer (not shown in the figure) in the silicon wafer 10, and on the side surface 1211 of the trench 121, the P-type inner expansion layer and the N-type inner expansion layer are exposed. Therefore, in order to improve the passivation effect at the trench 121, the thickness of the passivation film layer 40 on the P-type inner expansion layer and the N-type inner expansion layer exposed from the trench 121 can be set to be relatively thick, so as to improve the electrical performance of the solar cell wafer 100.

[0093] More specifically, the thickness of the passivation film layer 40 on the N-type inner expansion layer at the trench 121 can be substantially the same as or slightly less than the first thickness D1, and the thickness of the passivation film layer 40 on the P-type inner expansion layer can be substantially the same as or slightly less than the second thickness D2.

[0094] Referring to FIG. 7, in some embodiments, the N-type doped layer 30 can have a first extension portion 31 extending above the trench 121 and suspended above the trench 121, and the end of the first extension portion 31 and the surface 311 of the first extension portion 31 facing the trench 121 each have the passivation film layer 40, and the thickness of the passivation film layer 40 on the surface 311 of the first extension portion 31 facing the trench 121 is greater than the thickness of the passivation film layer 40 on the bottom surface 1212 of the trench 121. In this way, when the N-type doped layer 30 has the first extension portion 31, the passivation effect of the N-type doped layer 30 can be further improved.

[0095] In addition, referring to FIG. 8, in some embodiments, the P-type doped layer 20 can have a second extension portion 21 extending above and overhanging the trench 121, the end of the second extension portion 21 and the surface 211 of the second extension portion 21 facing the trench 121 each having a passivation film layer 40, wherein the thickness of the passivation film layer 40 on the surface 211 of the second extension portion 21 facing the trench 121 is greater than the thickness of the passivation film layer 40 on the bottom surface 1212 of the trench 121. In this way, when the P-type doped layer 20 has the second extension portion 21, the passivation effect of the P-type doped layer 20 can be further improved.

[0096] Referring to FIG. 9, in some embodiments, the spacing region 120 can also be a protrusion 122 between the adjacent P-type doped layer 20 and N-type doped layer 30, the top surface 1221 of the protrusion 122 being higher than the top of the P-type doped layer 20 and N-type doped layer 30, the top surface 1221 and side surface 1222 of the protrusion 122 each having a passivation film layer 40, the thickness of the passivation film layer 40 on the top surface 1221 of the protrusion 122 being greater than the thickness of the passivation film layer 40 on the side surface 1222 of the protrusion 122.

[0097] In this way, when doping is performed on the top of the protrusion 122, the passivation effect can be improved by setting the passivation film layer 40 on the top to be thicker. It can be understood that the side surface 1222 of the protrusion 122 refers to the sidewall surface of the protruding portion of the protrusion 122 protruding from the P-type doped layer 20 and N-type doped layer 30.

[0098] In the description of the present specification, the description referring to the terms “some embodiments”, “illustrative embodiments”, “examples”, “specific examples”, or “some examples” etc. means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0099] In addition, the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized by, The application relates to a silicon wafer, comprising: a silicon wafer having opposite first and second surfaces; a P-type doped layer and an N-type doped layer arranged on the first surface of the silicon wafer; and a passivation film layer arranged on the P-type doped layer and the N-type doped layer; wherein the passivation film layer on at least a part of the N-type doped layer has a first thickness, and the passivation film layer on at least a part of the P-type doped layer has a second thickness, and the first thickness is greater than the second thickness. The first surface has an edge region and a middle region, the middle region is located inside the edge region, and the edge region is closer to the edge of the first surface than the middle region; 2. The solar cell according to claim 1, wherein wherein the passivation film layer on the part of the N-type doped layer located on the middle region has the first thickness, and the passivation film layer on the part of the P-type doped layer located on the middle region has the second thickness. The passivation film layer on the part of the N-type doped layer located on the edge region has a third thickness, and the passivation film layer on the part of the P-type doped layer located on the edge region has a fourth thickness, the third thickness is greater than the first thickness, and the fourth thickness is greater than the second thickness.

3. The solar cell according to claim 2, wherein The third thickness is greater than the fourth thickness.

4. The solar cell of claim 3, wherein, The passivation film layer covering the middle region is a unitary continuous structure.

5. The solar cell of claim 2, wherein, The ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 2.

6. The solar cell according to any one of claims 1 to 5, wherein The ratio of the first thickness to the second thickness is 1.025-1.

6.

7. The solar cell of claim 6, wherein, The difference between the first thickness and the second thickness is 2nm-50nm.

8. The solar cell according to any one of claims 1 to 5, wherein The difference between the first thickness and the second thickness is 5nm-30nm.

9. The solar cell of claim 8, wherein, The first thickness is 52nm-250nm, and the second thickness is 50nm-200nm.

10. The solar cell as claimed in any one of claims 1-5, wherein, The first thickness is 55nm-230nm, and the second thickness is 50nm-200nm.

11. The solar cell of claim 10, wherein, On the middle region, the passivation film layer further covers a spacing region between adjacent P-type doped layers and N-type doped layers, and the part of the passivation film layer located at the spacing region has a fifth thickness, and the second thickness is greater than the fifth thickness.

12. The solar cell of claim 2, wherein, On the middle region, the passivation film layer on the P-type doped layer, the passivation film layer on the N-type doped layer, and the passivation film layer at the spacing region are a unitary continuous structure.

13. The solar cell of claim 12, wherein, The ratio of the second thickness to the fifth thickness is greater than 1 and less than or equal to 2.

14. The solar cell of claim 12, wherein, The ratio of the second thickness to the fifth thickness is 1.1-1.

8.

15. The solar cell of claim 14, wherein, The difference between the second thickness and the fifth thickness is 2nm-50nm.

16. The solar cell of claim 12, wherein, The difference between the second thickness and the fifth thickness is 20nm-40nm.

17. The solar cell of claim 16, wherein, The second thickness is 50nm-200nm, and the fifth thickness is 48nm-150nm.

18. The solar cell of claim 12, wherein, The second thickness is 50nm-200nm, and the fifth thickness is 30nm-160nm.

19. The solar cell of claim 18, wherein, The resistivity of the silicon wafer is greater than 20ohm.cm, and the difference between the second thickness and the fifth thickness is 10nm-60nm.

20. The solar cell of claim 12, wherein, ​ 21. The solar cell of claim 12, wherein, The interval region is a groove formed on the first surface, and the passivation film layer covers the side and bottom surfaces of the groove, wherein the thickness of at least a part of the passivation film layer on the side surface of the groove is greater than the thickness of the passivation film layer on the bottom surface of the groove.

22. The solar cell of claim 21, wherein, The N-type doped layer has a first extension part extending above and overhanging above the groove, and the end of the first extension part and the surface of the first extension part towards the groove are both provided with the passivation film layer, wherein the thickness of the passivation film layer on the surface of the first extension part towards the groove is greater than the thickness of the passivation film layer on the bottom surface of the groove; and / or The P-type doped layer has a second extension part extending above and overhanging above the groove, and the end of the second extension part and the surface of the second extension part towards the groove are both provided with the passivation film layer, wherein the thickness of the passivation film layer on the surface of the second extension part towards the groove is greater than the thickness of the passivation film layer on the bottom surface of the groove.

23. The solar cell of claim 12, wherein, The interval region is a protrusion between the adjacent P-type doped layer and N-type doped layer, the top surface of the protrusion is higher than the top of the P-type doped layer and N-type doped layer, and the top surface and side surface of the protrusion are both provided with the passivation film layer, wherein the thickness of the passivation film layer on the top surface of the protrusion is greater than the thickness of the passivation film layer on the side surface of the protrusion.

24. The solar cell of claim 2, wherein, The passivation film layer on the part of the intermediate region comprises a first type of passivation sub-layer and a second type of passivation sub-layer arranged in a stack, and the thickness of the passivation film layer on the intermediate region is the sum of the thicknesses of the first type of passivation sub-layer and the second type of passivation sub-layer. The thickness of the part of the first type of passivation sub-layer on the N-type doped layer is greater than the thickness of the part of the first type of passivation sub-layer on the P-type doped layer.

25. The solar cell of claim 24, wherein, The thickness of the part of the second type of passivation sub-layer on the N-type doped layer is equal to the thickness of the part of the second type of passivation sub-layer on the P-type doped layer.

26. The solar cell of claim 25, wherein, The first type of passivation sub-layer is prepared by a PECVD process or a thermal growth process, and the second type of passivation sub-layer is prepared by an atomic deposition process.

27. The solar cell as claimed in any one of claims 24-26, wherein, The first type of passivation sub-layer comprises at least one of a silicon oxide film layer, a silicon nitride film layer and a silicon oxynitride film layer, and the second type of passivation sub-layer comprises an aluminum oxide film layer.

28. The solar cell of claim 27, wherein, The silicon oxide film layer is a plurality of layers of silicon oxide arranged in a stack, the silicon nitride film layer is a plurality of layers of silicon nitride arranged in a stack, and the silicon oxynitride film layer is a plurality of layers of silicon oxynitride arranged in a stack.

29. A battery assembly comprising: The solar cell module comprises a plurality of solar cell pieces according to any one of claims 1-29.

30. A photovoltaic system characterized by, The battery assembly comprises the battery module according to claim 29.

Images