Solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a solar cell piece, a cell assembly and a photovoltaic system. In the solar cell piece, a P-type doping layer and an N-type doping layer are arranged on the first surface of a silicon wafer; and the thickness of the passive film layer on at least partial region of the N-type doped layer is greater than that of at least partial region of the passive film layer on the P-type doped layer. Therefore, the passivation film layer on at least partial region of the N-type doping layer and the passivation film layer on at least partial region of the P-type doping layer are subjected to different-thickness matching optimization design, and the passivation film layer on at least partial region of the N-type doping layer is thicker, so that the passivation effects of different doping regions of the solar cell can achieve a better matching effect; therefore, the performance of the solar cell is improved, materials can be saved, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and particularly to a solar cell chip, a battery module and a photovoltaic system. Background Art

[0002] Solar cell power generation is a sustainable clean energy source, which can convert sunlight into electric energy by using the photovoltaic effect of the semiconductor p-n junction. In a solar cell chip, a P-type doping layer and an N-type doping layer are arranged on a silicon wafer, and a passivation film layer is arranged on each doping layer to passivate the battery.

[0003] In current solar cell chips, the cooperation optimization between the passivation film layers on the P-type doping layer and the N-type doping layer is not fully considered to improve the passivation effect. Therefore, the performance of current solar cells is poor. Summary of the Utility Model

[0004] This application provides a solar cell chip, a battery module and a photovoltaic system.

[0005] This application is implemented as follows. The solar cell chip of the embodiment of this application includes:

[0006] A silicon wafer having opposite first and second surfaces;

[0007] A P-type doping layer and an N-type doping layer arranged on the first surface of the silicon wafer; and

[0008] A passivation film layer, the passivation film layer is covered on both the P-type doping layer and the N-type doping layer; wherein, the passivation film layer on at least part of the area of the N-type doping layer has a first thickness, and the passivation film layer on at least part of the area of the P-type doping layer has a second thickness, and the first thickness is greater than the second thickness.

[0009] Furthermore, 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;

[0010] Wherein, the passivation film layer on the part of the N-type doping layer located in the middle region has the first thickness, and the passivation film layer on the part of the P-type doping layer located in the middle region has the second thickness.

[0011] Furthermore, the passivation film layer on the part of the N-type doping layer located in the edge region has a third thickness, and the passivation film layer on the part of the P-type doping layer located in 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.

[0012] Further, the third thickness is greater than the fourth thickness.

[0013] Further, the passivation film layer covering the intermediate region is an integrally continuous structure.

[0014] Further, the ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 2.

[0015] Further, the ratio of the first thickness to the second thickness is 1.025 - 1.6.

[0016] Further, the difference between the first thickness and the second thickness is 2 nm - 50 nm.

[0017] Further, the difference between the first thickness and the second thickness is 5 nm - 30 nm.

[0018] Further, the first thickness is 52 nm - 250 nm, and the second thickness is 50 nm - 200 nm.

[0019] Further, the first thickness is 55 nm - 230 nm, and the second thickness is 50 nm - 200 nm.

[0020] Further, on the intermediate region, there is a spacer between adjacent P-type doped layers and N-type doped layers, the passivation film layer also covers the spacer, and the portion of the passivation film layer at the spacer has a fifth thickness, and the second thickness is greater than the fifth thickness.

[0021] Further, on the intermediate 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 spacer are an integrally continuous structure.

[0022] Further, the ratio of the second thickness to the third thickness is greater than 1 and less than or equal to 2.

[0023] Further, the ratio of the second thickness to the third thickness is 1.1 - 1.8.

[0024] Further, the difference between the second thickness and the third thickness is 2 nm - 50 nm.

[0025] Further, the difference between the second thickness and the third thickness is 20 nm - 40 nm.

[0026] Further, the second thickness is 50 nm - 200 nm, and the third thickness is 48 nm - 150 nm.

[0027] Further, the second thickness is 50 nm - 200 nm, and the third thickness is 30 nm - 160 nm.

[0028] Further, the resistivity of the silicon wafer is greater than 20 ohm.cm, and the difference between the second thickness and the third thickness is 10 nm - 60 nm.

[0029] Further, the spacer is a groove formed on the first surface, the passivation film layer covers the side surface and the bottom surface of the groove, and 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.

[0030] Further, the N-type doped layer has a first extended portion extending above the groove and suspended above the groove, and the passivation film layer is provided on the end of the first extended portion and the surface of the first extended portion facing the groove. Among them, the thickness of the passivation film layer on the surface of the first extended portion facing the groove is greater than the thickness of the passivation film layer on the bottom surface of the groove; and / or

[0031] The P-type doped layer has a second extended portion extending above the groove and suspended above the groove, and the passivation film layer is provided on the end of the second extended portion and the surface of the second extended portion facing the groove. Among them, the thickness of the passivation film layer on the surface of the second extended portion facing the groove is greater than the thickness of the passivation film layer on the bottom surface of the groove.

[0032] Further, the spacer is a boss located between the adjacent P-type doped layer and N-type doped layer, the top surface of the boss is higher than the tops of the P-type doped layer and the N-type doped layer, and the passivation film layer is provided on the top surface and the side surface of the boss. The thickness of the passivation film layer on the top surface of the boss is greater than the thickness of the passivation film layer on the side surface of the boss.

[0033] Further, the part of the passivation film layer in the intermediate region includes a first-type passivation sub-layer and a second-type passivation sub-layer arranged in a stacked manner, and the thickness of the passivation film layer in the intermediate region is the sum of the thicknesses of the first-type passivation sub-layer and the second-type passivation sub-layer;

[0034] Among them, the thickness of the part of the first-type passivation sub-layer on the N-type doped layer is greater than the thickness of the part of the first-type passivation sub-layer on the P-type doped layer.

[0035] Further, the thickness of the portion of the second-type passivation sub-layer located on the N-type doping layer is equal to the thickness of the portion of the second-type passivation sub-layer located on the P-type doping layer.

[0036] Further, the first-type passivation sub-layer is prepared by a PECVD process or a thermal growth process, and the second-type passivation sub-layer is prepared by an atomic deposition process.

[0037] Further, the first-type passivation sub-layer includes at least one of a silicon oxide film layer and a silicon nitride film layer, and the second-type passivation sub-layer includes an aluminum oxide film layer.

[0038] Further, the silicon oxide film layer is a multi-layer silicon oxide stacked in sequence, the silicon nitride film layer is a multi-layer silicon nitride stacked in sequence, and the silicon oxynitride film layer is a multi-layer silicon oxynitride stacked in sequence.

[0039] The present application also provides a battery assembly, including a plurality of the solar cell wafers described in any one of the above.

[0040] The present application also provides a photovoltaic system, and the photovoltaic system includes the above battery assembly.

[0041] In the solar cell wafer, battery assembly, and photovoltaic system according to the embodiments of the present application, a P-type doping layer and an N-type doping layer are provided on the first surface of the silicon wafer, and the thickness of the passivation film layer on at least part of the region of the N-type doping layer is greater than the thickness of at least part of the region of the passivation film layer on the P-type doping layer. Thus, through the cooperative optimization design of different thicknesses of the passivation film layers on at least part of the region of the N-type doping layer and at least part of the region of the P-type doping layer, and the thickness of the passivation film layer on at least part of the region of the N-type doping layer is thicker, the passivation effects of different doping regions of the solar cell can reach a better matching effect, thereby improving the performance of the solar cell wafer, and at the same time, the material usage can be saved and the cost can be reduced.

[0042] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0043] Figure 1 is a schematic module diagram of the photovoltaic system provided by the embodiment of the present application;

[0044] Figure 2 is a schematic cross-sectional structure diagram of the solar cell wafer provided by the embodiment of the present application;

[0045] Figure 3 is a schematic plan structure diagram of a part of the structure of the solar cell wafer provided by the embodiment of the present application;

[0046] Figure 4 It is a schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application in the middle region;

[0047] Figure 5 It is a schematic structure diagram of a passivation film layer provided by an embodiment of the present application;

[0048] Figure 6 It is another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application in the middle region;

[0049] Figure 7 It is still another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application in the middle region;

[0050] Figure 8 It is yet another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application in the middle region;

[0051] Figure 9 It is yet another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application in the middle region. Detailed implementation manners

[0052] In order to make the objectives, 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. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote 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 accompanying drawings are exemplary only for explaining the present application and cannot be construed as a limitation to the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0053] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", "side", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present application.

[0054] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "several" means two or more, unless otherwise specifically defined.

[0055] In this application, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0056] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure of this application, the components and settings of specific examples are described hereinafter. Of course, they are merely examples and are not intended to limit this application. In addition, this application may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, this application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0057] Please refer to Figure 1 , the photovoltaic system 1000 in the embodiment of this application may include the battery module 200 in the embodiment of this application. The battery module 200 in the embodiment of this application may include several solar cells 100 in the embodiment of this application. Several solar cells 100 may be connected in series by welding tapes to form several battery strings, and each battery string may form the battery module 200 in a series, parallel or series-parallel manner.

[0058] Please combine with Figure 2 , the solar cell 100 in the embodiment of this application may include a silicon wafer 10, a P-type doping layer 20, an N-type doping layer 30 and a passivation film layer 40.

[0059] The silicon wafer 10 has opposite first surface 11 and second surface 12. The P-type doping layer 20 and the N-type doping layer 30 are both disposed on the first surface 11 of the silicon wafer 10. The passivation film layer 40 covers the first surface 11, and the passivation film layer 40 is disposed on both the P-type doping layer 20 and the N-type doping layer 30.

[0060] Among them, as Figure 2 shown, the passivation film layer 40 on at least part of the region of the N-type doping layer 30 has a first thickness D1, and the passivation film layer 40 on at least part of the region of the P-type doping layer 20 has a second thickness D2, and the first thickness D1 is greater than the second thickness D2.

[0061] In the solar cell 100, the battery module 200, and the photovoltaic system 1000 in the embodiments of the present application, a P-type doping layer 20 and an N-type doping layer 30 are provided on the first surface 11 of the silicon wafer 10. The thickness of the passivation film layer 40 on at least part of the N-type doping layer 30 is greater than the thickness of at least part of the passivation film layer 40 on the P-type doping layer 20, that is, the first thickness D1 is greater than the second thickness D2. In this way, through the cooperative optimization design of different thicknesses of the passivation film layer 40 on at least part of the N-type doping layer 30 and at least part of the P-type doping layer 20, and the thickness of the passivation film layer 40 on at least part of the N-type doping layer 30 is thicker, the passivation effects of different doping regions of the solar cell 100 can reach a better matching effect, thereby improving the performance of the solar cell 100. At the same time, the use of materials can be saved and the cost can be reduced.

[0062] Specifically, in the embodiments of the present application, the first surface 11 may be the back surface of the silicon wafer 10, and the second surface 12 may be the front surface of the silicon wafer 10. The solar cell 100 is preferably a back-contact solar cell. Of course, in some embodiments, the solar cell 100 may also be other types of cell wafers that have both a P-type doping layer 20 and an N-type doping layer 30 on the same surface, and specific details are not limited herein.

[0063] The silicon wafer 10 may be a P-type silicon wafer or an N-type silicon wafer, and specific details are not limited herein. The P-type doping layer 20 may be of types such as a P-type doped polysilicon layer and a P-type doped microcrystalline silicon layer. The N-type doping layer 30 may be of types such as an N-type doped polysilicon layer and an N-type doped microcrystalline silicon layer. The P-type doping layer 20 and the N-type doping layer 30 may be prepared by means of diffusion, deposition, etc., and specific details are not limited herein.

[0064] It should be noted that in the present application, the thickness of the passivation film layer 40 on the N-type doping layer 30 refers to the thickness of the passivation film layer 40 on all surfaces of the N-type doping layer 30 covered with the passivation film layer 40. Similarly, the thickness of the passivation film layer 40 on the P-type doping layer 20 refers to the thickness of the passivation film layer 40 on all surfaces of the P-type doping layer 20 covered with the passivation film layer 40.

[0065] In addition, in this article, a certain film layer covering a certain surface or a certain film layer may mean that the film layer is directly stacked on the surface or a certain film layer, or there may be other film layers between the film layer and the surface or the film layer. The coverage only serves to define the specific setting range of the film layer.

[0066] It can be understood that in a back-contact solar cell, there are a plurality of P-type doping layers 20 and a plurality of N-type doping layers 30 on the first surface 11, and the plurality of P-type doping layers 20 and the plurality of N-type doping layers 30 are arranged alternately in sequence. In addition, it is not difficult to understand that in a back-contact solar cell, a tunneling layer (not shown, for example) may usually be provided between the P-type doping layer 20, the N-type doping layer 30, and the silicon wafer 10.

[0067] Please refer to Figure 2 and Figure 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.

[0068] Among them, the passivation film layer 40 on the part of the N-type doping layer 30 located on the middle region 112 has a first thickness D1, and the passivation film layer 40 on the part of the P-type doping layer 20 located on the middle region 112 has a second thickness D2.

[0069] In this way, the passivation effect of the regions corresponding to the N-type doping layer 30 and the P-type doping layer 20 at the position of the middle region 112 can reach a better effect, thereby improving the performance of the solar cell 100.

[0070] Specifically, as Figure 2 shown, in such an embodiment, 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 intersection edge position between the first surface 11 and the side surfaces 13, and the middle region 112 is located at the middle position of the first surface 11. The edge region 111 is located between the middle region 112 and the side surfaces 13.

[0071] As Figure 2 shown, the "edge region 111" refers to the region near the edge where the first surface 11 intersects with the side surfaces 13, and the "middle region 112" refers to the region of the first surface 11 other than the edge region 111.

[0072] As Figure 3 ( Figure 3 the passivation film layer 40 is not shown in Figure 3 shown, in some embodiments, the specific setting manner of the middle region 112 and the edge region 111 can be as shown, in such an embodiment, the edge region 111 can surround the middle region. That is to say, the edge of the first surface 11 has the edge region 111 at the intersection with all the side surfaces 13, and the middle region 112 is located within the edge region 110. That is, the edge region 11 is the region located at each edge position of the first surface 11.

[0073] Of course, in some embodiments, there may be no edge region at the edge where the part of the first surface 11 meets the side surface 13. For example, in a possible embodiment, in a half-cell, after cutting is completed, a cut surface will be formed on the half-cell, and the cut surface is also the side surface 13. In such a case, there is no edge region 110 at the intersection edge of the first surface 11 and the cut surface, while there is an edge region 110 near other intersection edges.

[0074] Please refer to Figure 2 , in some embodiments, the passivation film layer 40 on the part of the N-type doping layer 30 located on the edge region 111 has a third thickness D3, and the passivation film layer 40 on the part of the P-type doping layer 20 located 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.

[0075] In this way, setting the thickness of the passivation film layer on the doping layer in the edge region 111 to be thicker can improve the passivation effect of the edge region 111, reduce edge recombination, and further improve the efficiency of the solar cell 100.

[0076] Furthermore, in such an embodiment, the third thickness D3 may be greater than the fourth thickness D4. In this way, through the cooperative optimization design of different thicknesses of the passivation film layer 40 on the N-type doping layer 30 and the P-type doping layer 20 in the edge region 111, and the thickness of the passivation film layer 40 on the N-type doping layer 30 being thicker, the passivation effect of the edge region 11 can reach the optimal matching effect.

[0077] In some embodiments, the passivation film layer 40 covering the intermediate region 112 is an integral continuous structure.

[0078] In this way, this part of the passivation film layer 40 can be directly prepared in one step by the PECVD process. During the preparation process, different thicknesses in different regions can be achieved by controlling the conductivity of different regions.

[0079] Specifically, in this article, the "integral continuous structure" means that the materials and structures of the passivation film layer 40 on each part are the same, and the passivation film layer 40 on each part is a whole continuous film layer prepared by one process, only with different thicknesses in different regions. In the following text, if the same description appears, it can be understood by referring to this.

[0080] It can be understood that in the solar cell 100, it also has metal electrodes. The metal electrodes penetrate through the passivation film layer 40 and contact the doping layer. That is to say, in the subsequent manufacturing process, when the metal electrodes are made, the passivation film layer 40 at the corresponding positions of the metal electrodes will be removed or ablated. Specifically, in the back-contact solar cell, it has a P-type electrode and an N-type electrode (not shown in the figure). The P-type electrode penetrates through the passivation film layer 40 and contacts the P-type doping layer 20, and the N-type electrode penetrates through the passivation layer 20 and contacts the N-type doping layer 13.

[0081] Please refer to Figure 5 , in some embodiments, the part of the passivation film layer 40 located in the middle region 112 may include a first-type passivation sub-layer 41 and a second-type passivation sub-layer 42 arranged in a stacked manner. 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;

[0082] Among them, the thickness of the part of the first-type passivation sub-layer 41 located on the N-type doping layer 30 is greater than the thickness of the part of the first-type passivation sub-layer 41 located on the P-type doping layer 20.

[0083] In this way, on the one hand, the passivation film layer 40 on the middle region 112 adopts a structure of different types of passivation sub-layers, which can improve the passivation effect. On the other hand, by setting the thickness of the first-type passivation sub-layer 41 located on the N-type doping layer 30 to be greater than its thickness located on the P-type doping layer 20, the thickness of the passivation film layer 40 on the middle region 112 located on the N-type doping layer 30 can be made greater than the thickness on the P-type doping layer 20.

[0084] Furthermore, in such an embodiment, the thickness of the part of the second-type passivation sub-layer 42 located on the N-type doping layer 30 is equal to the thickness of the part of the second-type passivation sub-layer 42 located on the P-type doping layer 20.

[0085] 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.

[0086] Specifically, in the embodiments of the present application, the first-type passivation sub-layer 41 may 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 may include an aluminum oxide film layer. As Figure 4 shown,

[0087] As Figure 5As shown, in some embodiments, the passivation film layer 40 on the intermediate region 112 may 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 doping layer 20 and the N-type doping layer 30 may be substantially the same. The thickness of the silicon oxide film layer 401 on the N-type doping layer 30 may be greater than the thickness of the silicon oxide film layer 401 on the P-type doping layer 20. The thickness of the silicon nitride film layer 403 on the N-type doping layer 30 may be greater than the thickness of the silicon nitride film layer 403 on the P-type doping layer 20.

[0088] Of course, in some embodiments, the passivation film layer 40 on the intermediate region 112 may 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 doping layer 20 and the N-type doping layer 30 may be substantially the same. The thickness of the silicon nitride film layer 403 on the N-type doping layer 30 may be greater than the thickness of the silicon nitride film layer 403 on the P-type doping layer 20.

[0089] In addition, it should be noted that, in some embodiments, the silicon nitride film layer 403 may be a single-layer film structure or a multi-layer film structure composed of multiple silicon nitride layers with different refractive indices, and specific details are not limited herein.

[0090] In addition, in some embodiments, in the solar cell 100, the silicon oxide film layer may be multiple layers of silicon oxide stacked in sequence, the silicon nitride film layer may be multiple layers of silicon nitride stacked in sequence, and the silicon oxynitride film layer may be multiple layers of silicon oxynitride stacked in sequence. That is to say, in some possible embodiments, the silicon oxide film layer, the silicon nitride film layer, and the silicon oxynitride film layer may all be multi-layer structures.

[0091] 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.

[0092] In this way, the thickness of the passivation film layer 40 on the N-type doping layer 30 in the intermediate region 112 is relatively large, which can improve the passivation effect of the corresponding region of the N-type doping layer 30, so that the passivation effects of the regions corresponding to the P-type doping layer 20 and the N-type doping layer 30 reach a better matching effect, and further improve the performance of the solar cell 100.

[0093] Specifically, in such embodiments, the ratio of the first thickness D1 to the second thickness D2 may 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, and specific details are not limited herein.

[0094] In some embodiments, the ratio of the first thickness D1 to the second thickness D2 is preferably 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 and the second thickness D2 within this preferred range can achieve the optimal matching effect of the passivation effect in the corresponding regions of the P-type doping layer 20 and the N-type doping layer 30 while keeping the cost relatively low.

[0095] Specifically, in such an embodiment, 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 between 1.025 - 1.6.

[0096] In some embodiments, the difference between the first thickness D1 and the second thickness D2 can be 2 nm - 50 nm. Thus, by reasonably designing the thickness difference between the two, the passivation effect in the corresponding regions of the P-type doping layer 20 and the N-type doping layer 30 can reach a better matching effect, thereby improving the performance of the solar cell 100.

[0097] In such an embodiment, the difference between the first thickness D1 and the second thickness D2 is preferably 5 nm - 30 nm. 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 within this preferred range can achieve the optimal matching effect of the passivation effect in the corresponding regions of the P-type doping layer 20 and the N-type doping layer 30 while keeping the cost relatively low.

[0098] Specifically, in such an embodiment, the difference between the first thickness D1 and the second thickness D2 is preferably 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm or any value between 5 nm - 30 nm.

[0099] In some embodiments, the first thickness D1 can be 52 nm - 250 nm, and the second thickness D2 can be 50 nm - 200 nm. Thus, setting the first thickness D1 and the second thickness D2 within the above ranges can enable the passivation film layer 40 to achieve a good passivation effect and have a low cost.

[0100] In such an embodiment, the first thickness D1 is preferably 55 nm - 230 nm, and the second thickness D2 can be 50 nm - 200 nm. 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 within this preferred range, the passivation effect of the corresponding regions of the P-type doping layer 20 and the N-type doping layer 30 can reach the optimal matching effect, and at the same time, the cost can also be relatively low.

[0101] 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 difference between the first thickness D1 and the second thickness D2 is preferably 5 nm - 30 nm, and the ratio of the first thickness D1 to the second thickness D2 is preferably 1.025 - 1.6. This can make the passivation effect of the corresponding regions of the P-type doping layer 20 and the N-type doping layer 30 reach the optimal matching effect, and at the same time, the cost is relatively low.

[0102] Please refer to Figure 4 , in some embodiments, the solar cell 100 is a back-contact solar cell. In such a case, on the intermediate region 112, there is a spacer region 120 between adjacent P-type doping layer 20 and N-type doping layer 30, and the passivation film layer 40 also covers the spacer region 120. The portion of the passivation film layer 40 located at the spacer region 120 has a fifth thickness D5. Among them, the first thickness D1 is greater than the second thickness D2, and the second thickness D2 is greater than the fifth thickness D5.

[0103] In this way, by reasonably optimizing the thickness of the passivation film layer 40 on the N-type doping layer 30, P-type doping layer 20, and the spacer region 120 between them on the intermediate region 112, the passivation effects of the corresponding regions of the three can reach a good matching effect, and the electrical performance of the solar cell 100 can be improved under the condition of relatively low cost.

[0104] In such an embodiment, on the intermediate region 112, the passivation film layer 40 on the P-type doping layer 20, the passivation film layer 40 on the N-type doping layer 30, and the passivation film layer 40 at the spacer region 120 are an integrally continuous structure. In this way, it can be directly prepared in one step by the PECVD process. During the preparation process, different thicknesses of different regions can be achieved by controlling the conductivity of different regions.

[0105] 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, that is, 1 < D2 / D5 ≤ 2.

[0106] In this way, by designing the thicknesses of the fifth thickness D5, the second thickness D2, and the first thickness D1 to gradually increase and in accordance with the above ratios, the passivation effect of the entire solar cell 100 can achieve a relatively optimal matching effect, thereby improving the performance of the solar cell 100 while keeping the cost relatively low.

[0107] Specifically, in such an embodiment, the ratio of the second thickness D2 to the fifth thickness D5 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. Specifically, there is no limitation here.

[0108] In some embodiments, in a back-contact solar cell, the ratio of the second thickness D2 to the fifth thickness D5 is 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 within this preferred range, the passivation effect of the regions corresponding to the P-type doping layer 20, the N-type doping layer 30, and the spacer 120 can achieve an optimal matching effect, while keeping the cost relatively low.

[0109] Specifically, in such an embodiment, the preferred ratio of the second thickness D2 to the fifth thickness D5 can be, for example, 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 - 1.8.

[0110] In some embodiments, the difference between the second thickness D2 and the fifth thickness D5 can be 2 nm - 50 nm. 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 a relatively optimal matching effect, thereby improving the performance of the solar cell 100.

[0111] In such an embodiment, the difference between the second thickness D2 and the fifth thickness D5 is preferably 20 nm - 40 nm. Through repeated research and verification by the inventors of the present application, it is found that in a back-contact solar cell, by setting the difference between the second thickness D2 and the fifth thickness D5 within this preferred range, the passivation effect of the regions corresponding to the P-type doping layer 20, the N-type doping layer 30, and the spacer 120 can achieve an optimal matching effect, thereby improving the performance of the solar cell 100 while keeping the cost relatively low.

[0112] Specifically, in such an embodiment, the difference between the second thickness D2 and the fifth thickness D5 is preferably 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.

[0113] In some embodiments, the second thickness D2 may be 50 nm - 200 nm, and the fifth thickness D5 may be 48 nm - 150 nm. In this way, setting the second thickness D2 and the fifth thickness D5 within the above ranges enables the passivation film layer 40 to achieve a good passivation effect and relatively low cost.

[0114] In such an embodiment, the second thickness D2 may be 50 nm - 200 nm, and the fifth thickness D5 may preferably be 30 nm - 160 nm. Specifically, through repeated research and verification by the inventors of the present application, it is found that setting the sizes of the second thickness D2 and the fifth thickness D5 within this preferred range can make the passivation effects of the regions corresponding to the P-type doping layer 20, the N-type doping layer 30, and the spacer region 120 achieve an optimal matching effect, while the cost is also relatively low.

[0115] 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. This can make the passivation effects of the regions corresponding to the P-type doping layer 20, the N-type doping layer 30, and the spacer region 120 in the intermediate region 112 achieve an optimal matching effect, improve the performance of the solar cell 100, and the cost is also relatively low.

[0116] In some embodiments, the resistivity of the silicon wafer 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.

[0117] In this way, when the silicon wafer 10 is a high-resistance silicon wafer 10 with a resistivity greater than 20 ohm·cm, setting the difference between the second thickness D2 and the fifth thickness D5 within this range can ensure the passivation effect of the spacer region 120 while enabling the passivation effect of the region corresponding to the P-type doping layer 20 to reach a better state.

[0118] Please refer to Figure 6, in some embodiments, the spacer 120 is a groove 121 formed on the back surface 12 (that is, a groove 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 isolated by the groove 121). The passivation film layer 40 covers the side surface 1211 and the bottom surface 1222 of the groove 121, and the thickness of at least a part of the passivation film layer 40 located on the side surface 1211 of the groove 121 is greater than the thickness of the passivation film layer 40 located on the bottom surface 1212 of the groove 121).

[0119] In this way, the passivation matching effect at the groove 121 can be improved, thereby improving the overall passivation performance and enhancing the performance of the solar cell 100.

[0120] Specifically, in such an embodiment, at the doped layers on both sides of the groove 121, the P-type doped layer 20 usually forms a P-type inner diffusion layer (not shown in the figure) in the silicon wafer 10, and the N-type doped layer 30 forms an N-type inner diffusion layer (not shown in the figure) in the silicon wafer 10. On the side surface 1211 of the groove 121, the P-type inner diffusion layer and the N-type inner diffusion layer are exposed. Therefore, in order to improve the passivation effect at the groove 121, the thickness of the passivation film layer 40 on the P-type inner diffusion layer and the N-type inner diffusion layer exposed from the groove 121 can be set to be relatively thick, thereby enhancing the electrical performance of the solar cell 100.

[0121] More specifically, the thickness of the passivation film layer 40 located on the N-type inner diffusion layer at the groove 121 may be substantially the same as or slightly less than the first thickness D1, and the thickness of the passivation film layer 40 located on the P-type inner diffusion layer is substantially the same as or slightly less than the second thickness D2.

[0122] Please refer to Figure 7 , in some embodiments, the N-type doped layer 30 may have a first extension portion 31 that extends above the groove 121 and is suspended above the groove 121. The end portion of the first extension portion 31 and the surface 311 of the first extension portion 31 facing the groove 121 both have a passivation film layer 40, wherein the thickness of the passivation film layer 40 located on the surface 311 of the first extension portion 31 facing the groove 121 is greater than the thickness of the passivation film layer 40 located on the bottom surface 1212 of the groove 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.

[0123] In addition, please refer to Figure 8, in some embodiments, the P-type doped layer 20 may have a second extension portion 21 extending above the trench 121 and suspended above the trench 121. The end portion of the second extension portion 21 and the surface 211 of the second extension portion 21 facing the trench 121 are both provided with a passivation film layer 40. Among them, the thickness of the passivation film layer 40 located 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 located 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.

[0124] Please refer to Figure 9 , in some embodiments, the spacer 120 may also be a boss 122 located between adjacent P-type doped layers 20 and N-type doped layers 30. The top surface 1221 of the boss 122 is higher than the tops of the P-type doped layer 20 and the N-type doped layer 30. The top surface 1221 and the side surface 1222 of the boss 122 are both provided with a passivation film layer 40. The thickness of the passivation film layer 40 located on the top surface 1221 of the boss 122 is greater than the thickness of the passivation film layer 40 located on the side surface 1222 of the boss 122.

[0125] In this way, when doping is performed on the top of the boss 122, setting the passivation film layer 40 on the top to be thicker can improve the passivation effect. It can be understood that the side surface 1222 of the boss 122 refers to the side wall surface of the protruding portion of the boss 122 protruding from the P-type doped layer 20 and the N-type doped layer 30.

[0126] In the description of this specification, the description with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" 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 this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0127] In addition, the above are only the preferred embodiments of the present application and are not used to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: include: A silicon wafer having a first surface and a second surface opposite to each other; A P-type doped layer and an N-type doped layer are disposed on the first surface of the silicon wafer; and A passivation film layer is provided, wherein the passivation film layer is covered on both 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, and the first thickness is greater than the second thickness.

2. The solar cell according to claim 1, characterized in that: 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; The passivation film layer on the portion of the N-type doped layer located on the middle region has the first thickness, and the passivation film layer on the portion of the P-type doped layer located on the middle region has the second thickness.

3. The solar cell according to claim 2, characterized in that: The passivation film layer on the portion of the N-type doped layer located on the edge area has a third thickness, and the passivation film layer on the portion of the P-type doped layer located on the edge area has a fourth thickness, the third thickness is greater than the first thickness, and the fourth thickness is greater than the second thickness.

4. The solar cell according to claim 3, characterized in that: The third thickness is greater than the fourth thickness.

5. The solar cell according to claim 2, characterized in that: The passivation film layer covering the middle area is an integrated continuous structure.

6. The solar cell according to any one of claims 1 to 5, characterized in that: A ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 2.

7. The solar cell according to claim 6, characterized in that: The ratio of the first thickness to the second thickness is 1.025-1.

6.

8. The solar cell according to any one of claims 1 to 5, characterized in that: The difference between the first thickness and the second thickness is 2nm-50nm.

9. The solar cell according to claim 8, characterized in that: The difference between the first thickness and the second thickness is 5nm-30nm.

10. The solar cell according to any one of claims 1 to 5, characterized in that: The first thickness is 52nm-250nm, and the second thickness is 50nm-200nm.

11. The solar cell according to claim 10, characterized in that: The first thickness is 55nm-230nm, and the second thickness is 50nm-200nm.

12. The solar cell according to claim 2, characterized in that: In the middle region, there is a spacing region between the adjacent P-type doped layer and the N-type doped layer, the passivation film layer also covers the spacing region, the portion of the passivation film layer located at the spacing region has a fifth thickness, and the second thickness is greater than the fifth thickness.

13. The solar cell according to claim 12, characterized in that: In the middle region, the passivation film layer on the P-type doping layer, the passivation film layer on the N-type doping layer, and the passivation film layer at the spacing region are an integrated continuous structure.

14. The solar cell according to claim 12, characterized in that: A ratio of the second thickness to the fifth thickness is greater than 1 and less than or equal to 2.

15. The solar cell according to claim 14, characterized in that: The ratio of the second thickness to the fifth thickness is 1.1-1.

8.

16. The solar cell according to claim 12, characterized in that: The difference between the second thickness and the fifth thickness is 2nm-50nm.

17. The solar cell according to claim 16, characterized in that: The difference between the second thickness and the fifth thickness is 20nm-40nm.

18. The solar cell according to claim 12, characterized in that: The second thickness is 50nm-200nm, and the fifth thickness is 48nm-150nm.

19. The solar cell according to claim 18, characterized in that: The second thickness is 50nm-200nm, and the fifth thickness is 30nm-160nm.

20. The solar cell according to claim 12, characterized in that: The resistivity of the silicon wafer is greater than 20 ohm.cm, and the difference between the second thickness and the fifth thickness is 10 nm-60 nm.

21. The solar cell according to claim 12, characterized in that: The spacer area is a groove formed on the first surface, the passivation film layer covers the side and bottom of the groove, and the thickness of at least part of the passivation film layer on the side of the groove is greater than the thickness of the passivation film layer on the bottom of the groove.

22. The solar cell according to claim 21, characterized in that: The N-type doped layer has a first extension portion extending above the trench and suspended above the trench, and the end of the first extension portion and the surface of the first extension portion facing the trench both have the passivation film layer, wherein the thickness of the passivation film layer located on the surface of the first extension portion facing the trench is greater than the thickness of the passivation film layer located on the bottom surface of the trench; and / or The P-type doped layer has a second extension portion extending above the groove and suspended above the groove, and the end of the second extension portion and the surface of the second extension portion facing the groove both have the passivation film layer, wherein the thickness of the passivation film layer located on the surface of the second extension portion facing the groove is greater than the thickness of the passivation film layer located on the bottom surface of the groove.

23. The solar cell according to claim 12, characterized in that: The spacer region is a boss located between the adjacent P-type doped layer and the N-type doped layer, the top surface of the boss is higher than the top of the P-type doped layer and the N-type doped layer, the top surface and side surfaces of the boss both have the passivation film layer, and the thickness of the passivation film layer located on the top surface of the boss is greater than the thickness of the passivation film layer located on the side surfaces of the boss.

24. The solar cell according to claim 2, characterized in that: The portion of the passivation film layer located in the middle region includes a first type passivation sublayer and a second type passivation sublayer stacked, and the thickness of the passivation film layer located in the middle region is the sum of the thickness of the first type passivation sublayer and the second type passivation sublayer; The thickness of a portion of the first type passivation sublayer located on the N-type doping layer is greater than the thickness of a portion of the first type passivation sublayer located on the P-type doping layer.

25. The solar cell according to claim 24, characterized in that: The thickness of a portion of the second type passivation sublayer located on the N-type doping layer is equal to the thickness of a portion of the second type passivation sublayer located on the P-type doping layer.

26. The solar cell according to claim 25, characterized in that: The first type of passivation sublayer is prepared by using a PECVD process or a thermal growth process, and the second type of passivation sublayer is prepared by using an atomic deposition process.

27. The solar cell according to any one of claims 24 to 26, characterized in that: The first type passivation sublayer includes 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 sublayer includes an aluminum oxide film layer.

28. The solar cell according to claim 27, characterized in that: The silicon oxide film layer is a plurality of silicon oxide layers stacked in sequence, the silicon nitride film layer is a plurality of silicon nitride layers stacked in sequence, and the silicon oxynitride film layer is a plurality of silicon oxynitride layers stacked in sequence.

29. A battery assembly, characterized in that: The invention comprises the solar cell sheets as described in any one of claims 1 to 28.

30. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 29.

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