Solar cells, photovoltaic power generation modules and photovoltaic power generation systems

Abstract

To provide a solar cell, a solar power module, and a solar power generation system.SOLUTION: A solar cell includes a substrate having a first surface and a second surface facing each other along the thickness direction, a first passivation layer provided on the first surface side of the substrate, and a second passivation layer provided on a side of the first passivation layer remote from the substrate, and the first passivation layer and the second passivation layer are made of the same material, the density of the first passivation layer is higher than the density of the second passivation layer, and the average thickness of the first passivation layer is smaller than the average thickness of the second passivation layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to the field of photovoltaic technology, and in particular to solar cells, photovoltaic modules and photovoltaic systems. [Background technology]

[0002] With the development of semiconductor technology, people's requirements for the performance of semiconductor devices are constantly increasing, and passivation is a technology that can significantly improve the performance of devices.

[0003] For example, in solar cells, the photoelectric conversion efficiency of the solar cell can be significantly improved by forming a passivation layer. However, how to improve the passivation effect of the passivation layer is currently an issue to be resolved. Summary of the Invention [Problem to be solved by the invention]

[0004] Based on this, in order to address the above technical challenges, there is a need to provide a solar cell, a solar power generation module, and a solar power generation system that improve the passivation effect of the passivation layer and thereby improve the photoelectric conversion efficiency of the solar cell. [Means for solving the problem]

[0005] A solar cell provided in a first aspect includes a substrate having a first surface and a second surface arranged opposite each other along a thickness direction, a first passivation layer arranged on the first surface side of the substrate, and a second passivation layer arranged on a side of the first passivation layer away from the substrate, wherein the first passivation layer and the second passivation layer are made of the same material, the density of the first passivation layer is higher than the density of the second passivation layer, and the average thickness of the first passivation layer is smaller than the average thickness of the second passivation layer.

[0006] Optionally, the first passivation layer has an average thickness of 0.1-6 nm, and the second passivation layer has an average thickness of 1-30 nm.

[0007] Optionally, the first passivation layer has a greater thickness uniformity than the second passivation layer.

[0008] Optionally, the difference in thickness between different regions of the first passivation layer is less than 0.5 nm, and the difference in thickness between different regions of the second passivation layer is more than 0.5 nm.

[0009] Optionally, the first passivation layer and the second passivation layer also cover the side surface of the substrate, and the coverage area of ​​the first passivation layer on the side surface of the substrate is equal to or less than the coverage area of ​​the second passivation layer on the side surface of the substrate.

[0010] Optionally, the substrate includes a first thickness portion and a second thickness portion sequentially arranged along a direction gradually moving away from the first passivation layer, the first passivation layer covering a side surface corresponding to the first thickness portion, and the second passivation layer covering a side surface corresponding to the first thickness portion and the second thickness portion.

[0011] Alternatively, the thickness (T1) of the first thick portion is ½ to ½ of the thickness (T) of the substrate, and the sum of the thickness of the first thick portion and the thickness (T2) of the second thick portion is ⅔ to ½ of the thickness of the substrate, i.e., ½*T≦T1≦T and ⅔*T≦T1+T2≦T.

[0012] Optionally, the first thick portion has a thickness of 10 to 200 μm, and the sum of the thickness of the first thick portion and the thickness of the second thick portion is 50 to 200 μm.

[0013] In a second aspect, a photovoltaic module is provided, comprising a plurality of solar cells connected in series and / or parallel, at least one of the solar cells being the solar cell according to the first aspect.

[0014] A solar power generation system provided in a third aspect includes the solar power generation module according to the second aspect. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic structural diagram of a solar cell provided in an embodiment of the present application. [Diagram 2] FIG. 2 is a schematic structural diagram of a solar cell provided in another embodiment of the present application. [Diagram 3] 1 is a schematic flow chart of fabricating a first passivation layer by employing the ALD time method provided in the embodiments of the present application. [Figure 4] 1 is a schematic flow chart of fabricating a first passivation layer by employing an ALD spatial method provided in an embodiment of the present application. [Diagram 5] FIG. 5 is a schematic arrangement diagram of a jet head based on FIG. 4 provided in an embodiment of the present application. [Figure 6] FIG. 5 is a schematic arrangement diagram of a jet head based on FIG. 4 provided in another embodiment of the present application. [Figure 7] 1 is a schematic flow chart of fabricating a first passivation layer by employing an ALD spatial method provided in another embodiment of the present application. [Figure 8] FIG. 8 is a schematic arrangement diagram of a jet head based on FIG. 7 provided in an embodiment of the present application. [Figure 9] 1 is a schematic flow chart of fabricating a first passivation layer by employing an ALD spatial method provided in another embodiment of the present application. [Figure 10] FIG. 10 is a schematic arrangement diagram of a jet head based on FIG. 9 provided in an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In order to make the above objects, features and advantages of the present application clearer and easier to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, many specific details are described to provide a complete understanding of the present application. However, the present application can be implemented in many other forms different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific examples disclosed below.

[0017] Unless the context requires otherwise, throughout the specification and claims, the term "comprises" should be interpreted in an open and inclusive sense, i.e., "including but not limited to." In the description herein, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "illustratively," or "some examples" are intended to indicate that the currently described feature, e.g., structure, material, or characteristic, is included in at least one embodiment or example of the present disclosure. Generalized expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, a particular described feature, structure, material, or characteristic may be included in any one or more embodiments or examples in any suitable manner.

[0018] Exemplary embodiments are described herein with reference to cross-sectional and / or plan views that are idealized exemplary views. In the drawings, thicknesses of layers and regions are exaggerated for clarity. As such, variations from the shapes of the drawings due, for example, to manufacturing techniques and / or tolerances are possible. Thus, the exemplary embodiments should not be construed as limited to the shapes of regions shown herein but are intended to include deviations in shapes that result, for example, from manufacturing. For example, an etched region shown as a rectangle typically has curved features. Thus, the regions shown in the figures are schematic in nature and their shapes are not intended to represent the actual shape of a region of a device and are not intended to limit the scope of the exemplary embodiments.

[0019] "A and / or B" includes A only, B only, and a combination of A and B.

[0020] In this specification, the words "for example," "such as," "exemplary," "give an example," etc. are for explanatory purposes and mean that different technical solutions before and after are related in their inclusive scope, but should not be understood as limiting the former technical solution, and should not be understood as limiting the scope of protection of this specification. In this specification, unless otherwise indicated, A (such as B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0021] In this specification, "optionally", "optional", and "optional" refer to something that may or may not exist, that is, to one of the two parallel solutions of "existence" and "non-existence". In one technical solution, unless otherwise specified and unless there is a contradiction or mutual constraint, if there are multiple "options", each "option" is independent of the other.

[0022] In this specification, the terms "optionally contain" and "optionally include" mean "contain or not contain." "Optionally, component X" means that component X is present or not present, or that component X is contained or not contained.

[0023] In this specification, the terms "first", "second", etc., in "first embodiment", "second embodiment", etc., are for descriptive purposes only and should not be understood as indicating or implying relative importance or number, nor should they be understood as implying the importance or number of the technical features indicated.

[0024] It should be noted that when an element is referred to as being "fixed" or "mounted" on another element, it may be directly on the other element, or intermediate elements may be present. When an element is referred to as being "connected" to another element, it may be directly connected to the other element, or intermediate elements may co-exist. As used herein, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions are for illustrative purposes only and do not represent the only embodiment.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used herein in the description of this application are for the purpose of describing specific examples only and are not intended to be limiting of this application.

[0026] In this specification, technical features described in an open format include both closed technical solutions consisting of the listed features and open technical solutions including the listed features.

[0027] In this specification, unless otherwise stated, with respect to a numerical interval (i.e., a numerical range), the distribution of selected numerical values ​​within the numerical interval is considered to be continuous and to include the two numerical endpoints (i.e., the minimum and maximum) of the numerical interval, as well as each numerical value between the two numerical endpoints. Unless otherwise stated, when a numerical interval refers only to integers within the numerical interval, it includes the integers at the two endpoints of the numerical range, as well as each integer between the two endpoints, and is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe a feature or characteristic, the numerical ranges may be combined. In other words, unless otherwise stated, a numerical range disclosed herein should be understood to include any and all subranges contained therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, etc. The "numerical interval" is allowed to broadly include numerical interval types such as percentage intervals, ratio intervals, etc.

[0028] Solar cells are semiconductor devices that convert light into electrical energy using the photoelectric effect. Solar cell technology has undergone a transformation from traditional aluminum back surface field (BSF) cells to passive emitter and rear cell (PERC) cells and then to selective emitter (PERC+SE) cells. Compared with traditional BSF cells, PERC+SE cell technology adds a laser SE secondary diffusion process and a rear passivation process after the traditional diffusion process. The rear passivation layer thin film produced by the rear passivation process is the main improvement structure of PERC solar cells compared to traditional cells, and its principle is that the rear surface of the substrate is coated with a passivation layer thin film to passivate the surface, improve the long-wave response, reduce the surface recombination velocity, and thereby improve the photoelectric conversion efficiency of the solar cell.

[0029] Of course, in addition to the above-mentioned batteries, currently, batteries with high photoelectric conversion performance are also provided with a passivation layer to reduce the interface state density between the substrate and the metal contact region, block the transition of minority carriers to the metal contact region, and thereby reduce the recombination probability of electrons and holes, improving the passivation effect.

[0030] Here, the solar cell with high photoelectric conversion performance may be, for example, an N-type Topcon (Tunnel Oxide Passivated Contact) cell or a P-type IBC (Interdigitated Back Contact) cell.

[0031] An N-type Topcon cell is a Topcon solar cell with an N-type silicon substrate, and a P-type IBC cell is an IBC solar cell with a P-type silicon substrate.

[0032] Take the solar cell as an example, the two surfaces of the substrate of the N-type TOPCON cell can both receive incident light. The substrate can be doped with N-type ions, which can be either phosphorus, arsenic or antimony ions. A tunnel layer and a doped polysilicon layer are formed on the rear surface of the substrate, and the tunnel layer can form a passivation contact layer together with the doped polysilicon layer, and the tunnel layer is used to achieve the interface passivation of the rear surface of the substrate and to reduce the interface state density between the substrate and the doped polysilicon layer, so that the concentration of majority carriers is much higher than that of minority carriers, reducing the recombination probability of electron-holes, and at the same time increasing the resistivity to form the selective contact of majority carriers.

[0033] Here, the material of the tunnel layer may be a dielectric material, for example, may include at least one of silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polysilicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. The tunnel layer can bond with the dangling bonds on the back surface of the substrate, thereby suppressing carrier recombination on the front surface of the solar cell, and improving the photoelectric conversion efficiency of the solar cell.

[0034] Here, since the tunnel layer has a function similar to that of the passivation layer, the tunnel layer may include the passivation layer.

[0035] In some embodiments, the N-type TOPCON cell further includes a backside passivation layer on the side of the doped polysilicon layer away from the tunnel layer, which can reduce the concentration of minority carriers at the backside of the substrate, thereby reducing the surface recombination rate and improving the photovoltaic conversion efficiency.

[0036] In some embodiments, the backside passivation layer material may include one or more of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, or silicon oxycarbonitride.

[0037] Here, since the rear surface passivation layer has the same function as the above-mentioned passivation layer, the rear surface passivation layer may include the above-mentioned passivation layer.

[0038] In some embodiments, the front side of the substrate of the N-type TOPCON cell has an emitter, which may be a P-type doped layer, i.e., the substrate is doped with P-type ions, and the emitter and the substrate form a PN junction. A front passivation layer may be provided on the side of the emitter away from the substrate. The material of the front passivation layer may include one or more of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, or silicon oxycarbonitride. The front passivation layer, like the back passivation layer, can reduce the concentration of minority carriers on the front side of the substrate, thereby reducing the recombination rate at the surface and improving the photoelectric conversion efficiency.

[0039] Here, since the front passivation layer has the same function as the above-mentioned passivation layer, the front passivation layer may include the above-mentioned passivation layer.

[0040] The above-mentioned passivation layer can effectively improve the photoelectric conversion efficiency of the solar cell, but the passivation effect of the passivation layer is related to the material of the passivation layer, the manufacturing process, etc., and how to control the manufacturing process to improve the passivation effect of the passivation layer and improve the manufacturing efficiency is currently a problem to be solved.

[0041] Based on the above technical problems, in a first aspect, some embodiments of the present application provide a solar cell 10, and as shown in Fig. 1, the solar cell 10 includes a substrate 1 and a passivation layer 2 provided on the substrate 1. Here, the substrate 1 has a first surface 11 and a second surface 12 provided opposite to each other along a thickness direction thereof, and the passivation layer 2 includes a first passivation layer 21 provided on the first surface 11 side of the substrate 1, and a second passivation layer 22 provided on the side of the first passivation layer 21 away from the substrate 1.

[0042] Here, the first surface 11 and the second surface 12 may be the front and back surfaces of the substrate 1, respectively, and when the first surface 11 is the front surface of the substrate 1, the first passivation layer 21 and the second passivation layer 22 are provided on the front surface of the substrate 1, and when the first surface 11 is the back surface of the substrate, the first passivation layer 21 and the second passivation layer 22 are provided on the back surface of the substrate 1.

[0043] Of course, the above is merely an example, and the passivation layer 2 may be provided on the front and back surfaces of the substrate 1, in which case the front passivation layer and the back passivation layer both include the first passivation layer 21 and the second passivation layer 22.

[0044] Here, the case where the passivation layer 2 is provided on the front surface of the substrate 1 is taken as an example, that is, the first surface 11 is the front surface of the substrate 1 .

[0045] In some embodiments, the substrate 1 may be a silicon substrate, and the material of the silicon substrate may include at least one of monocrystalline silicon, polysilicon, amorphous silicon, and microcrystalline silicon.

[0046] In some embodiments, the first passivation layer 21 and the second passivation layer 22 are made of the same material. Illustratively, the first passivation layer 21 and the second passivation layer 22 are made of aluminum oxide, which not only prevents unwanted premature recombination of electrons and holes, but also serves as a mirror to reflect sunlight back into the active part of the solar cell and convert it into electrical energy, thereby further improving the photoelectric conversion efficiency of the solar cell.

[0047] Of course, the materials of the first passivation layer 21 and the second passivation layer 22 can also include one or more of the other materials included in the front passivation layer listed above, such as silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, and silicon oxycarbonitride.

[0048] In some embodiments, the density of the first passivation layer 21 is higher than the density of the second passivation layer 22 , and the average thickness of the first passivation layer 21 is smaller than the average thickness of the second passivation layer 22 .

[0049] Here, it should be understood by those skilled in the art that the first passivation layer 21 and the second passivation layer 22 may not have a discontinuous structure, but may be continuous thin films to achieve passivation. Meanwhile, thin films manufactured using various manufacturing processes disclosed in the related art may not have the same thickness at different positions, so in order to explain the difference in thickness between the first passivation layer 21 and the second passivation layer 22, the thickness of the entire thin film is represented here by an average thickness. The average thickness here can be understood as the average value of the thickness at different positions of the same thin film.

[0050] Compactness is also called atomic packing fraction or space packing fraction and is the percentage of the volume of a unit cell that is occupied by the atoms themselves, i.e., the ratio of the volume of the atoms per unit cell to the volume of the unit cell.

[0051] The fact that the density of the first passivation layer 21 is higher than the density of the second passivation layer 22 means that the atomic filling rate of the material contained in the first passivation layer is higher than the atomic filling rate of the material contained in the second passivation layer 22.

[0052] Illustratively, the atomic filling rate of the material contained in the first passivation layer 21 is greater than the atomic filling rate of the material contained in the second passivation layer 22 .

[0053] As an example, if the material contained in the first passivation layer 21 and the material contained in the second passivation layer 22 are both aluminum oxide, the atomic filling rate of the aluminum oxide in the first passivation layer 21 is greater than the atomic filling rate of the aluminum oxide in the second passivation layer 22.

[0054] The density of the thin film can be controlled by the manufacturing process of the thin film, and for example, the first passivation layer 21 can be manufactured by atomic layer deposition, and the second passivation layer 22 can be manufactured by plasma enhanced chemical vapor deposition. Alternatively, the first passivation layer 21 and the second passivation layer 22 can both be manufactured by atomic layer deposition or plasma enhanced chemical vapor deposition, and in this case, the deposition rate of the first passivation layer 21 is smaller than the deposition rate of the second passivation layer 22.

[0055] Atomic Layer Deposition (ALD) is a method by which materials can be plated layer by layer in the form of monoatomic films onto the surface of a substrate. During the plating process, two or more chemical vapor precursors react sequentially on the surface of the substrate to produce a solid thin film.

[0056] Plasma Enhanced Chemical Vapor Deposition (PECVD) is a deposition method that uses a discharge phenomenon to ionize atoms corresponding to a target material, and then forms a chemical reaction deposit on a substrate 1.

[0057] It can be understood that atomic layer deposition is limited by the reaction mechanism that can only form one layer of atoms at a time, so the rate of atomic layer deposition is small, the production capacity of atomic layer deposition is low, and the coverage on the surface of the substrate is improved. Plasma enhanced chemical vapor deposition does not need to deposit precursors sequentially, which can greatly improve the production efficiency, but the uniformity of the film formed by plasma enhanced chemical vapor deposition is poor, and the flat surface is thickly coated and the rough surface is thinly coated. In addition, the density of the film formed by plasma enhanced chemical vapor deposition is low, and the ionization process causes impact damage to the passivation surface.

[0058] Therefore, in the embodiments of the present application, atomic layer deposition and plasma enhanced chemical vapor deposition can be adopted to form the first passivation layer 21 and the second passivation layer 22, respectively; alternatively, the first passivation layer 21 and the second passivation layer 22 can be manufactured by the same method, and the manufacturing speed of the first passivation layer 21 can be controlled to be slower than the manufacturing speed of the second passivation layer 22, thereby forming the first passivation layer 21 with high density and the second passivation layer 22 with low density. In this way, on the one hand, by adjusting the manufacturing process and manufacturing speed of the first passivation layer 21, for example, atomic layer deposition can be adopted, and atomic layer deposition can realize precise control of the thickness of the film layer on the order of nanometers based on the self-stopping surface-limited reaction between the volatile precursor molecules and the matrix, so that the first passivation layer 21 with uniform thickness, denseness, no cracks, and good shape retention effect can be generated, thereby ensuring the film formation quality of the first passivation layer 21 and the passivation effect of the first passivation layer 21 on the surface of the substrate 1. On the other hand, the thickness of the first passivation layer 21 can be reduced, the thickness of the second passivation layer 22 can be largely controlled, and a manufacturing method with a high manufacturing speed can be adopted to manufacture the second passivation layer 22, for example, plasma-enhanced chemical vapor deposition can be adopted to rapidly form the second passivation layer 22, and when the thickness of the passivation layer 2 is constant, the manufacturing efficiency of the passivation layer 2 can be improved as much as possible. In this way, the passivation effect of the passivation layer 2 can be effectively improved while improving the manufacturing efficiency, thereby effectively balancing the relationship between the passivation effect and the manufacturing efficiency and improving the passivation effect.

[0059] In addition, the second passivation layer 22 can also protect the first passivation layer 21, thereby effectively reducing problems such as insufficient strength and susceptibility to damage due to the first passivation layer 21 being too thin, making the passivation layer 2 have sufficient reliability.

[0060] In addition, by controlling the materials of the first passivation layer 21 and the second passivation layer 22 to be the same, when manufacturing other film layers in the solar cell, it is only necessary to consider the material properties of the first passivation layer 21 and the second passivation layer 22, and there is no need to consider the effects of the manufacturing process at different positions of the other film layers.

[0061] In some embodiments, for example, the materials of the first passivation layer 21 and the second passivation layer 22 both contain aluminum oxide, the aluminum oxide in the first passivation layer 21 is represented by AIOx, where the value of x is 1.45-1.55, and the aluminum oxide of the second passivation layer 22 is represented by AIOx, where the value of x is 0.5-2, and the value of x is different in different regions of the second passivation layer 22.

[0062] In these examples, the material uniformity of the first passivation layer 21 is good, but the material uniformity of the second passivation layer 22 is poor. This proves that the material uniformity can be adjusted by further controlling the manufacturing process and manufacturing speed. In this way, the first passivation layer 21 can have a good passivation effect, but the passivation effect of the second passivation layer 22 is poor, but the manufacturing efficiency of the passivation layer 2 can be effectively improved.

[0063] In some embodiments, the proportion of trivalent aluminum ions in the aluminum oxide of the first passivation layer 21 is relatively high, greater than 85%.

[0064] In some embodiments, the first passivation layer 21 has an average thickness of 0.1-6 nm, and the second passivation layer 22 has an average thickness of 1-30 nm.

[0065] In these embodiments, by controlling the average thickness of the first passivation layer 21 and the second passivation layer 22 within the above range, it is possible to maximize the passivation effect while simultaneously achieving manufacturing efficiency, thereby maximizing the photoelectric conversion efficiency.

[0066] Here, the average thickness of the first passivation layer 21 being 0.1 to 6 nm means that the average thickness of the first passivation layer 21 is any value between 0.1 and 6 nm, and for example, the average thickness of the first passivation layer 21 is 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, or 6 nm.

[0067] The average thickness of the second passivation layer 22 being 1 to 30 nm means that the average thickness of the second passivation layer 22 is any value between 1 and 30 nm, and for example, the average thickness of the second passivation layer 22 is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm or 30 nm.

[0068] Here, since the average thickness of the first passivation layer 21 is smaller than the average thickness of the second passivation layer 22, it is understood that when the average thickness of the second passivation layer 22 is 1 nm, the average thickness of the first passivation layer 21 is any value between 0.1 nm or more and less than 1 nm, and when the average thickness of the first passivation layer 21 is 6 nm, the average thickness of the second passivation layer 22 is any value between 6 nm and 30 nm or less.

[0069] In some embodiments, the first passivation layer 21 and the second passivation layer 22 have a thickness appropriate for improving the photoelectric conversion efficiency of the solar cell. In this case, for example, the total thickness of the first passivation layer 21 and the second passivation layer 22 is 25 nm, the thickness of the first passivation layer 21 may be any value between 0.1 and 6 nm, the thickness of the second passivation layer 22 may be any value between 19 and 24.9 nm, and the sum of the thicknesses of the first passivation layer 21 and the second passivation layer 22 is 25 nm.

[0070] In some embodiments, the thickness uniformity of the first passivation layer 21 is better than the thickness uniformity of the second passivation layer 22 .

[0071] In these embodiments, the uniformity of the first passivation layer 21 is better than that of the second passivation layer 22, so the surface of the first passivation layer 21 is flatter and has good coverage on the surface of the substrate 1, while the surface of the second passivation layer 22 has relatively large undulations and poor coverage on the surface of the substrate 1, so the first passivation layer 21 has a better passivation effect on the second passivation layer 22.

[0072] In some embodiments, the difference in thickness between different regions of the first passivation layer 21 is less than 0.5 nm, and the difference in thickness between different regions of the second passivation layer 22 is greater than 0.5 nm.

[0073] In these embodiments, the uniformity of the first passivation layer 21 is superior to that of the second passivation layer 22. Although the average thickness of the first passivation layer 21 is smaller than that of the second passivation layer 22, the thickness uniformity of the first passivation layer 21 is good and the thickness uniformity of the second passivation layer 22 is poor, so that the thickness of the first passivation layer 21 at a certain position may be greater than the thickness of the second passivation layer 22 at a certain position.

[0074] In some embodiments, as shown in FIG. 2, the first passivation layer 21 and the second passivation layer 22 cover the side surface of the substrate 1, and the coverage area of ​​the first passivation layer 21 on the side surface of the substrate 1 is equal to or less than the coverage area of ​​the second passivation layer 22 on the side surface of the substrate 1.

[0075] In these embodiments, by controlling the coverage area of ​​the first passivation layer 21 on the side surface of the substrate 1 to be equal to or less than the coverage area of ​​the second passivation layer 22 on the side surface of the substrate 1, the peripheral plating of the first passivation layer 21 can be reduced, thus avoiding subsequent peripheral plating of the passivation layer 2 on the second surface of the substrate 1, thereby facilitating subsequent removal of the peripheral plating on the second surface and reducing poor contact between the metal electrode and the substrate 1.

[0076] In some embodiments, the substrate 1 includes a first thickness portion 1a and a second thickness portion 1b sequentially provided along a direction gradually moving away from the first passivation layer 21, the first passivation layer 21 covering a side surface corresponding to the first thickness portion 1a, and the second passivation layer 22 covering a side surface corresponding to the first thickness portion 1a and the second thickness portion 1b. In some embodiments, the first passivation layer 21 covers only a side surface corresponding to the first thickness portion 1a, and does not cover a side surface corresponding to the second thickness portion 1b.

[0077] In these embodiments, by forming a first passivation layer 21 and a second passivation layer 22 on the side of the substrate 1, the carrier recombination rate on the side of the solar cell can be further reduced, thereby further improving the photoelectric conversion efficiency of the solar cell.

[0078] In some embodiments, the thickness of the first thick portion 1a is greater than 1 / 2 the thickness of the substrate 1 and less than the thickness of the substrate 1, and the sum of the thicknesses of the first thick portion 1a and the second thick portion 1b is greater than 2 / 3 the thickness of the substrate 1 and less than the thickness of the substrate 1.

[0079] In these embodiments, the first passivation layer 21 has less peripheral plating around the edges and less side surface coverage, and the second passivation layer 22 has more peripheral plating around the edges and more side surface coverage.

[0080] In some embodiments, by controlling the peripheral plating of the first passivation layer 21, some or all of the side surface area may be covered only by the second passivation layer 22.

[0081] In some embodiments, the second passivation layer 22 is also plated around the periphery of the second side 12 of the substrate 1 .

[0082] In some embodiments, since the thickness of the substrate 1 is 80 to 200 μm, the thickness of the first thick portion 1a is 10 to 200 μm, and the sum of the thicknesses of the first thick portion 1a and the second thick portion 1b may be 50 to 200 μm.

[0083] In these embodiments, the coverage area of ​​the second passivation layer 22 is greater than or equal to the coverage area of ​​the first passivation layer 21, so that the area of ​​the side covered by the second passivation layer 22 (corresponding to the sum of the thicknesses of the first thick portion 1a and the second thick portion 1b) is greater than or equal to the area of ​​the side covered by the first passivation layer 21 (corresponding to the thickness of the first thick portion 1a). In this case, when the thickness of the first thick portion 1a corresponding to the side covered by the first passivation layer 21 is 200 μm, the sum of the thicknesses of the first thick portions 1a corresponding to the side covered by the second passivation layer 22 is also 200 μm, and plating can be performed around the second surface of the substrate 1.

[0084] Here, by controlling the manufacturing process, the coverage area of ​​the first passivation layer 21 on the side surface of the substrate 1 can be controlled, and thus the peripheral plating of the first passivation layer 21 can be reduced.

[0085] Here, the manufacturing methods of the first passivation layer 21 and the second passivation layer 22 may be different, for example, the first passivation layer 21 may be manufactured by adopting atomic layer deposition, and the second passivation layer 22 may be manufactured by adopting plasma enhanced chemical vapor deposition. Alternatively, the manufacturing methods of the first passivation layer 21 and the second passivation layer 22 may be the same, for example, the first passivation layer 21 and the second passivation layer 22 may both be manufactured by adopting atomic layer deposition, in which case the manufacturing speed of the first passivation layer 21 is smaller than the manufacturing speed of the second passivation layer 22.

[0086] Here, in order to control the side coverage area of ​​the first passivation layer 21 and / or the second passivation layer 22 and reduce peripheral plating, an ALD time method or an ALD space method can be adopted for manufacturing.

[0087] For example, when the first passivation layer 21 is manufactured by adopting an ALD time process or an ALD space process, a plurality of jet heads may be provided in the reaction chamber of the atomic layer deposition, and different jet heads are used to deliver different gaseous substances to the reaction chamber. The reaction chamber has a corresponding plurality of jet regions, and a plurality of jet heads are arranged in one-to-one correspondence with the plurality of jet regions.

[0088] Exemplary transportable gaseous substances include, but are not limited to, each precursor source (eg, the first precursor source and the second precursor source) and an inert gas.

[0089] In some embodiments, the jet head may be connected to the top wall of the reaction chamber, and the substrate 1 may be placed on the bottom wall of the reaction chamber, so that the gaseous substance is jetted perpendicularly to the first surface of the substrate 1, and the first precursor source and the second precursor source may be uniformly adsorbed on the first surface of the substrate 1 and react with each other. Illustratively, the material of the first passivation layer 21 is aluminum oxide, and the first precursor source may be an aluminum source, for example, the aluminum source is trimethylaluminum (TMA), and the second precursor source may be an oxygen source, for example, the oxygen source may include at least one of water and ozone.

[0090] Here, as shown in FIG. 3, the manufacturing method of the ALD time process may include step 101 of introducing a first precursor source into a reaction chamber in which the substrate 1 is located, step 102 of discharging the first precursor source from the reaction chamber and introducing a second precursor source after a first predetermined time has elapsed, step 103 of discharging the second precursor source from the reaction chamber after a second predetermined time has elapsed, and step 104 of repeatedly performing the above steps 101 to 103 until the thickness of the first passivation layer 21 reaches a target thickness.

[0091] Here, in step 101, after the first precursor source is introduced, the first precursor source is adsorbed on the substrate 1 under the protection of the inert gas and forms an aluminum film on the substrate 1, and the first precursor source in the reaction chamber is discharged after a first predetermined time, the first predetermined time being the time from when the jet head jets the first precursor source to when the aluminum film covers the entire surface of the first surface of the substrate 1, at which time, if the second precursor source is introduced, the reaction between the remaining first precursor source and the introduced second precursor can be effectively suppressed, so that the unnecessary reaction product can be effectively suppressed from adhering to the second surface of the substrate 1, affecting the reaction on the first surface of the substrate 1 or causing the film formation on the first surface of the substrate 1 to become non-uniform. The first predetermined time may be related to at least one of the area of ​​the first surface of the substrate 1, the volume of the reaction chamber, the jet flow rate and / or jet pressure of the first precursor source, and the distance between the jet head and the substrate 1, etc., to control the deposition time of the aluminum film.

[0092] In steps 102 and 103, when the second precursor source is introduced into the reaction chamber, the second precursor source reacts with the aluminum film adsorbed on the first surface of the substrate 1 to generate a corresponding product, and when the first precursor source in the reaction chamber is completely consumed, a first passivation layer 21 is formed. The second predetermined time is the time from when the jet head ejects the second precursor source to when the oxygen atoms in the second precursor source reach the substrate 1 and cover the entire surface of the first surface of the substrate 1. Since the unreacted first precursor source has already been discharged before the second precursor source is introduced, the deposition of an atomic layer on the remaining area other than the first surface of the substrate 1 after the second precursor source is introduced can be reduced, and the "temporal" separation between the first precursor source and the second precursor source can be realized, and a large proportion of the first precursor source and the second precursor source can react on the first surface of the substrate 1, thereby reducing peripheral plating.

[0093] The second predetermined time may be related to at least one of the area of ​​the first surface of the substrate 1, the volume of the reaction chamber, the jet flow rate and / or the jet pressure of the first precursor source, and the distance between the jet head and the substrate 1, etc., to control the deposition time of the oxygen atoms.

[0094] In some embodiments, as shown in FIG. 4 , the ALD spatial manufacturing method may include step 201 of controlling the movement of the substrate 1 to sequentially pass through a first jet region where a first precursor source is introduced, a second jet region where an isolation gas is introduced, and a third jet region where a second precursor source is introduced, and step 202 of repeatedly performing step 201 until the thickness of the first passivation layer 21 reaches a target thickness.

[0095] Here, as shown in FIG. 5, the substrate 1 is placed on a hot plate, and the substrate 1 is moved within the reaction chamber by moving the hot plate, and the first precursor source is ejected from the first jet head, the second precursor source is ejected from the third jet head, and the isolation gas is ejected from the second jet head.

[0096] The isolation gas is a gas that does not react with either the first precursor source or the second precursor source, and as shown in Fig. 5, the first, second and third jet heads are sequentially arranged along the moving direction of the substrate 1 and linearly arranged on the upper wall of the reaction chamber, and the substrate 1 is placed on a hot plate, and the movement of the hot plate is controlled to pass through each jet area of ​​the substrate 1 in sequence, thereby facilitating the first, second and third jet heads to jet gaseous substances corresponding to the first surface of the substrate 1. Meanwhile, isolating the first and second precursor sources with the isolation gas can prevent the first and second precursor sources from reacting with each other before reaching the substrate, and can also prevent the first and second precursor sources from reaching other areas of the substrate other than the first surface, thereby reducing peripheral plating.

[0097] In some embodiments, the isolation gas may illustratively be nitrogen (N2) or other inert gas.

[0098] In some embodiments, the jet flow rate and / or jet pressure of each jet head can be determined according to the moving speed of the substrate 1 to ensure the deposition effect of the first passivation layer 21 .

[0099] It can be understood that the atomic layer deposition effect is related to the adsorption effect of the first precursor source, the adsorption and reaction effect of the second precursor source, and the isolation effect of the isolation gas, etc. Therefore, according to the requirements of the atomic layer deposition effect, the moving speed of the substrate 1, the jetting flow rate and / or jetting pressure of each jet head and the control logic of each jet head can be appropriately adjusted.

[0100] In some examples, each jet head can continuously introduce a corresponding gaseous substance into the reaction chamber, simplifying the control logic of the jet heads and optimizing the adsorption effect of the first precursor, the reaction effect of the second precursor, and the isolation effect of the isolation gas.

[0101] In another example, each jet head may start delivering its corresponding gaseous substance into the reaction chamber only immediately before the substrate 1 enters the corresponding jet region, to reduce the usage of each material.

[0102] In yet another example, the jet head corresponding to each precursor source can be controlled to start introducing the corresponding precursor source into the reaction chamber only immediately before the substrate 1 enters the corresponding jet region, and the jet head of the isolation gas can be controlled to continuously deliver the isolation gas into the reaction chamber, thereby reducing the usage of the precursor source while maintaining the isolation effect and reaction effect.

[0103] Although the above describes the case where only one set of jet heads is provided in the reaction chamber, in some other embodiments, multiple sets of jet heads may be provided in the reaction chamber, and each set of jet heads includes a first jet head, a second jet head and a third jet head arranged sequentially along the movement direction of the substrate.

[0104] 6, two sets of jet heads are provided in the reaction chamber, each set including a first jet head, a second jet head and a third jet head provided in sequence along the substrate movement direction. By controlling the linear movement of the substrate 1, the substrate 1 can pass through each jet region in sequence, which enables multiple atomic layer depositions to be performed consecutively, and the manufacturing efficiency of the first passivation layer 21 can be further improved.

[0105] In addition, when one set of jet heads is provided in the reaction chamber as shown in Fig. 5, after one cycle of reaction is completed, all gas in the reaction chamber is discharged, and the substrate 1 is moved back to the first jet region, and the above steps are repeated. The volume of the reaction chamber required in this embodiment is small, which is suitable for a manufacturing scene with a small production volume, but when multiple sets of jet heads are included as shown in Fig. 6, a reaction chamber with a large volume is required, which is suitable for a manufacturing scene with a larger production volume.

[0106] Compared with the case where the ALD time method is used to manufacture the first passivation layer 21, the ALD spatial method can realize "spatial" isolation by controlling the movement of the substrate 1 to pass through the first jet area, the second jet area, and the third jet area in sequence, thereby eliminating the process of evacuating the reaction chamber, and greatly shortening the time required to manufacture the first passivation layer 21.

[0107] In this process, by providing a second jet area to "spatially" isolate the first precursor source and the second precursor source, and reasonably setting the width of the second jet area and the jet flow rate and / or jet pressure of the isolation gas, the first precursor source and the second precursor source can be effectively isolated, and a large proportion of the first precursor source and the second precursor source can both cause atomic layer deposition on the first surface side of the substrate 1, thereby reducing peripheral plating.

[0108] In some other embodiments, as shown in FIG. 7 , a manufacturing method for the ALD spatial method may include step 301 of controlling the movement of the substrate 1 to sequentially pass through a first jet region where a first precursor source is introduced, an exhaust region for exhausting gaseous substances in the exhaust region from the reaction chamber, and a third jet region where a second precursor source is introduced, and step 302 of repeatedly performing step 301 until the thickness of the first passivation layer 21 reaches a target thickness.

[0109] As shown in FIG. 8, the substrate 1 is placed on a hot plate, and the substrate 1 is moved in the reaction chamber by moving the hot plate, a first precursor source is sprayed by a first jet head, a second precursor source is sprayed by a third jet head, and an exhaust region is provided between the first jet head and the second jet head to exhaust the gaseous substances in the exhaust region from the reaction chamber.

[0110] By providing an exhaust area, the first precursor source and the second precursor source can be discharged from the reaction chamber in a timely manner when they diffuse into the exhaust area, thereby suppressing the reaction between the first precursor source and the second precursor source, and reducing peripheral plating. By providing the above-mentioned isolation gas, the first precursor source and the second precursor source can be isolated by the isolation gas, and by providing an exhaust area, the excess first precursor source and the second precursor source can be discharged to the outside by the exhaust area, and the excess first precursor source and the second precursor source can be discharged from the reaction chamber in a timely manner, which also contributes to reducing the reaction of the first precursor source and the second precursor source before they reach the substrate, and can suppress the excess first precursor source and the second precursor source from reaching the region other than the first surface of the substrate, thereby reducing peripheral plating.

[0111] In some embodiments, as shown in FIG. 8, an exhaust line may be provided in the exhaust region, and the exhaust line can be connected to a vacuum pump to realize suction to the gas material in the exhaust region, so that the excess first precursor source and the second precursor source diffused in the exhaust region can be discharged from the reaction chamber in a timely manner.

[0112] In these embodiments, the exhaust area provides "spatial" isolation, and the exhaust process of the reaction chamber can be omitted, and the time required for manufacturing the first passivation layer can be greatly reduced. At the same time, the exhaust area is provided to isolate the first precursor source from the second precursor source, and the width of the exhaust area is reasonably set to effectively isolate the first precursor source from colliding with the second precursor source, so that a large proportion of the reaction between the first precursor source and the second precursor source occurs on the first surface side of the substrate 1, thereby reducing peripheral plating.

[0113] Of course, in some embodiments, two sets of jet heads arranged sequentially along the moving direction of the substrate 1 may be provided in the reaction chamber, one set of jet heads may include a first jet head, a third jet head, and a second jet head provided between the first jet head and the third jet head, the second jet head being used to jet the isolation gas, and the other set of jet heads may include a first jet head, a third jet head, and an exhaust region provided between the first jet head and the third jet head. By controlling the movement of the substrate 1 to pass through the first jet region of the first precursor source, the exhaust region, the second jet region of the isolation gas, and the third jet region of the second precursor source in sequence, it is also possible to realize spatially isolated depositions, and it is also possible to realize continuous multiple depositions.

[0114] In still other embodiments, as shown in FIG. 9 , the ALD spatial manufacturing method may include step 401 of controlling the movement of the substrate 1 to sequentially pass through a first jet region to which a first precursor source is introduced and a third jet region to which a second precursor source is introduced, with a first distance d between the first jet region and the third jet region, and step 402 of repeatedly performing step 401 until the thickness of the first passivation layer 21 reaches a target thickness.

[0115] As shown in FIG. 10 , the substrate 1 is placed on a hot plate, and the substrate 1 is moved in the reaction chamber by moving the hot plate, and the first precursor source is jetted by the first jet head, and the second precursor source is jetted by the third jet head, and the first spacing d can increase the distance between the first jet area and the third jet area, thereby effectively inhibiting the first precursor source and the second precursor source from reacting in the remaining area other than the first surface of the substrate 1, and thereby reducing peripheral plating.

[0116] In some embodiments, the first distance d may be determined as a function of the ejection flow rates and / or ejection pressures of the first and second precursor sources.

[0117] Specifically, the purpose of providing the first interval d is to reduce the reaction between the first precursor source and the second precursor source in the remaining region other than the first surface of the substrate 1, so that the larger the jet flow rate or jet pressure of the first precursor source and the second precursor source, the more likely the two precursor sources are to react due to the action of the air flow. Therefore, the setting of the first interval d has a positive correlation with the jet flow rate and jet pressure of the first precursor source and the second precursor source, that is, the larger the jet flow rate and / or jet pressure of the first precursor source and the second precursor source, the greater the first interval d needs to be set to improve the "spatial" isolation effect.

[0118] In these embodiments, by providing a first distance d between the first and third jet regions, a large proportion of the first and second precursor sources can be reacted on the first side of the substrate 1 without the need for additional devices or loading of isolating gas, thereby achieving the goal of reducing peripheral plating. That is, there is no need to provide a jet region where any other gas is introduced between the first and third jet regions.

[0119] In some embodiments, the second passivation layer can be fabricated using plasma enhanced chemical vapor deposition.

[0120] In these embodiments, plasma enhanced chemical vapor deposition is used to fabricate the second passivation layer, and there is no need to consider peripheral plating of the second passivation layer, which can improve manufacturing efficiency.

[0121] In some other embodiments, the second passivation layer can be fabricated by alternating plasma-enhanced chemical vapor deposition and ALD spatial techniques.

[0122] In these embodiments, the peripheral plating of the second passivation layer can be moderately reduced while improving manufacturing efficiency, and the film density of the second passivation layer can be improved to a certain extent to further improve the passivation effect.

[0123] In some embodiments, the hydrogen content of the first passivation layer 21 is smaller than the hydrogen content of the second passivation layer 22. Here, the hydrogen content of the passivation layer 2 is related to the corresponding manufacturing process. Specifically, taking the material of the first passivation layer 21 and the second passivation layer 22 as an example, the plasma enhanced chemical vapor deposition method is adopted to manufacture the second passivation layer 22, and the hydrogen content in the second passivation layer 22 can be controlled to be high, for example, by controlling the introduction amount of trimethylaluminum and the saturation degree of reaction. Meanwhile, the atomic layer deposition "time" method is adopted to manufacture the first passivation layer 21, and the hydrogen content in the first passivation layer 21 can be controlled to be low, for example, by controlling the introduction amount of trimethylaluminum and the saturation degree of reaction. The lower the hydrogen atom content in the passivation layer, the higher the passivation effect. Therefore, when the production efficiency of the above passivation layer 2 is high, the second passivation layer 22 can be produced by alternately adopting plasma enhanced chemical vapor deposition and ALD spatial method, so that the passivation effect of the second passivation layer 22 can be further improved, thereby further improving the passivation effect of the passivation layer 2.

[0124] In some embodiments, the negative charge density of the first passivation layer 21 is greater than the negative charge density of the second passivation layer 22. Specifically, the higher the negative charge density at the interface between the passivation layer and the substrate 1, the better the field passivation properties will be, since the higher the ability of the passivation layer to shield minority carriers on the P-type silicon surface.

[0125] In these embodiments, by setting the negative charge density of the first passivation layer 21 to be greater than the negative charge density of the second passivation layer 22, the passivation effect of the first passivation layer 21 closer to the substrate 1 is greater than the passivation effect of the second passivation layer 22 farther from the substrate 1, and the photoelectric conversion efficiency of the solar cell can be more effectively improved.

[0126] Although the steps in the flowcharts according to the above embodiments are shown sequentially as indicated by the arrows, it should be understood that the steps are not necessarily performed sequentially in the order indicated by the arrows. Unless expressly specified herein, there is no strict order restriction on the execution of the steps, and they may be performed in another order. Furthermore, at least some of the steps in the flowcharts according to the above embodiments may include multiple steps or multiple stages that are not necessarily completed at the same time, but may be performed at different times, and the order of execution of these steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least some of the steps or stages in other steps.

[0127] In a second aspect, some embodiments of the present application provide a photovoltaic module comprising a plurality of solar cells connected in series and / or parallel, at least one solar cell being the solar cell according to the first aspect.

[0128] In some embodiments, the photovoltaic module may further include an encapsulation layer for covering a surface of the plurality of solar cells connected in series and / or parallel, and a cover plate for covering a surface of the encapsulation layer remote from the solar cells. The solar cells are electrically connected in a whole or multiple sheet form.

[0129] In some embodiments, the solar cells may be electrically connected by a conductive tape, and an encapsulation layer covers the surfaces of the solar cells and the conductive tape to encapsulate the solar cells.

[0130] In some embodiments, the sealing layer may be an organic sealing film, such as an ethylene-vinyl acetate copolymer film, a polyethylene octene co-elastomer film, or a polyethylene terephthalate film.

[0131] In some other embodiments, the cover plate may be a cover plate with a light-transmitting function, such as a glass cover plate, a plastic cover plate, and so on.

[0132] An embodiment of the present application further provides a photovoltaic power generation system including the photovoltaic power generation module according to the second aspect.

[0133] It should be understood that the solar power generation system can be applied to solar power plants such as ground power plants, rooftop power plants, and water power plants, and can be applied to equipment or devices that generate electricity using sunlight, such as user solar power sources, solar street lights, solar cars, solar buildings, etc. Of course, it should be understood that the application scenarios of the solar power generation system are not limited to these.

[0134] That is, it can be applied to any field where photovoltaic power generation is required. Taking a photovoltaic power generation system network as an example, the photovoltaic power generation system includes a photovoltaic power generation array, a busbar box and an inverter, the photovoltaic power generation array can be a combination of an array of a plurality of photovoltaic power generation modules, for example, a plurality of photovoltaic power generation modules can constitute a plurality of photovoltaic power generation arrays, the photovoltaic power generation array is connected to the busbar box, the busbar box collects the current generated by the photovoltaic power generation array, the collected current is converted into AC current required by the commercial power grid through an inverter, and then connected to the commercial power grid to realize solar power supply.

[0135] The technical features of the above embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as no contradiction occurs in the combination of these technical features, they should be considered to be within the scope of the present specification.

[0136] The above examples merely show some embodiments of the present invention, and the description is more specific and detailed, but it should not be understood as limiting the scope of the claims. It should be noted that those skilled in the art may make some modifications and improvements without departing from the concept of the present invention, which are within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be subject to the scope of the attached claims.

Claims

1. a substrate having a first surface and a second surface opposed to each other along a thickness direction; a first passivation layer provided on a first surface side of the substrate; a second passivation layer disposed on a side of the first passivation layer away from the substrate; The material composition of the first passivation layer and the second passivation layer is the same; The first passivation layer has a higher density than the second passivation layer, and the first passivation layer has a smaller average thickness than the second passivation layer; the first passivation layer and the second passivation layer cover the side surface of the substrate, and the coverage area of ​​the first passivation layer on the side surface of the substrate is equal to or smaller than the coverage area of ​​the second passivation layer on the side surface of the substrate; the substrate includes a first thickness portion and a second thickness portion sequentially provided along a direction gradually moving away from the first passivation layer; A solar cell, characterized in that the first passivation layer covers a side surface corresponding to the first thickness portion, and the second passivation layer covers side surfaces corresponding to the first thickness portion and the second thickness portion.

2. 2. The solar cell according to claim 1, wherein the first passivation layer has an average thickness of 0.1 to 6 nm, and the second passivation layer has an average thickness of 1 to 30 nm.

3. 2. The solar cell according to claim 1, wherein the first passivation layer has a thickness uniformity superior to that of the second passivation layer.

4. 4. The solar cell of claim 3, wherein the difference in thickness between different regions of the first passivation layer is less than 0.5 nm, and the difference in thickness between different regions of the second passivation layer is more than 0.5 nm.

5. 2. The solar cell according to claim 1, wherein a thickness of the first thick portion is greater than or equal to ½ of a thickness of the substrate and less than or equal to the thickness of the substrate, and a sum of a thickness of the first thick portion and a thickness of the second thick portion is greater than or equal to ⅔ of a thickness of the substrate and less than or equal to the thickness of the substrate.

6. 6. The solar cell according to claim 5, wherein the first thick portion has a thickness of 10 to 200 μm, and the sum of the thickness of the first thick portion and the thickness of the second thick portion is 50 to 200 μm.

7. A solar cell array includes a plurality of solar cells connected in series and / or parallel; A photovoltaic module, wherein at least one of the solar cells is a solar cell according to any one of claims 1 to 6.

8. A photovoltaic power generation system comprising the photovoltaic power generation module according to claim 7.

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