Solar cell and cell module

Abstract

The utility model is applicable to the field of photovoltaic technology, and provides a solar cell and a cell assembly, the solar cell comprises a silicon substrate, bubbles with a first preset value are arranged between a first passivation layer and a first doping layer, the first preset value is greater than 0 and less than or equal to 500 / mm < 2 >, and the first doping layer is a second passivation layer. Bubbles with a second preset value are arranged between the first passivation layer and the first doping layer, bubbles with a second preset value are arranged between the second passivation layer and the second doping layer, and the second preset value is larger than 0 and smaller than or equal to 200 / mm < 2 >. The density of bubbles between the second passivation layer and the second doping layer is controlled to be larger than 0 and smaller than or equal to 200 / mm < 2 >, so that the passivation effect of the passivation layer can be improved, the surface recombination rate of the solar cell is reduced, and the solar cell has higher open-circuit voltage and short-circuit current.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic technology, and particularly relates to a solar cell and a battery module. Background Art

[0002] During the manufacturing process of the cell, bubbles are generated between the film layers. For example, hydrogen generated by the decomposition of silane during the growth of the polysilicon layer, and hydrogen generated by the reaction of silane and ammonia during the deposition of the passivation layer. After a large amount of hydrogen accumulates between the polysilicon layer and the passivation film interface, bubbles will be formed. The bubbles are directly related to the passivation effect. How to achieve good passivation by controlling the size, density, etc. of the bubbles has become an urgent problem to be solved. Summary of the Utility Model

[0003] This application provides a solar cell, aiming to improve the passivation effect by controlling the size, density, etc. of the bubbles.

[0004] This application is implemented as follows. A solar cell includes a silicon substrate, the silicon substrate has a first surface and a second surface arranged oppositely, one of the first surface and the second surface has alternately arranged first regions and second regions, or, one of the first surface and the second surface has a first region, and the other of the first surface and the second surface has a second region; a first doping layer disposed on the first region; a first passivation layer formed on a surface of the first doping layer facing away from the silicon substrate; a second doping layer disposed on the second region; a second passivation layer formed on a surface of the second doping layer facing away from the silicon substrate; there are bubbles with a first preset value between the first passivation layer and the first doping layer, the first preset value is greater than 0 and less than or equal to 500 / mm 2 , there are bubbles with a second preset value between the second passivation layer and the second doping layer, the second preset value is greater than 0 and less than or equal to 200 / mm 2 .

[0005] Optionally, the first doping layer is a p-type doping layer, and the second doping layer is an n-type doping layer.

[0006] Optionally, the first preset value is greater than 0 and less than or equal to 30 / mm 2 .

[0007] Optionally, the second preset value is greater than 0 and less than or equal to 10 / mm 2 .

[0008] Optionally, the first preset value is equal to the second preset value.

[0009] Optionally, the first preset value is greater than the second preset value.

[0010] Optionally, the diameter of the bubble is greater than or equal to 50 nm and less than or equal to 15 μm.

[0011] Optionally, the diameter of the bubble is greater than or equal to 200 nm and less than or equal to 5 μm.

[0012] Optionally, the ratio of the total area of the first region to the total area of the second region ranges from greater than or equal to 50% to less than or equal to 120%.

[0013] Optionally, the thickness of the second doping layer is less than the thickness of the first doping layer.

[0014] In this application, by controlling the density of the bubbles between the first passivation layer and the first doping layer to be greater than 0 and less than or equal to 500 / mm 2 , and controlling the density of the bubbles between the second passivation layer and the second doping layer to be greater than 0 and less than or equal to 200 / mm 2 , the passivation effect of the passivation layer can be improved, the surface recombination rate of the solar cell can be reduced, and it can have a higher open-circuit voltage and short-circuit current.

[0015] A battery assembly includes the above-mentioned solar cell. The technical effects of this application are the same as those of the above-mentioned solar cell, and will not be elaborated here. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the back-contact solar cell provided by the present application;

[0017] Figure 2 is a schematic structural diagram of the bifacial solar cell provided by the present application;

[0018] Figure 3 is a parabolic graph of the hydrogen content and the quality of the passivation film layer provided by the present application;

[0019] Figure 4 is an optical microscope image of the bubbles provided by the present application;

[0020] Figure 5 is Figure 4 a partial enlarged view of;

[0021] Figure 6 is a size diagram of the bubbles provided by the present application.

[0022] Description of the Reference Numerals:

[0023] 100, solar cell; 10, silicon substrate; 101, first surface; 102, second surface; 20, first doping layer; 30, second doping layer; 40, first passivation layer; 50, second passivation layer. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, 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 with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and should not 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.

[0025] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It 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 therefore should not be construed as a limitation to the present application.

[0026] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0027] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0028] In the present application, unless otherwise clearly specified and defined, the first feature being "above" or "below" 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" 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 "under" 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.

[0029] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This 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, the present 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 of other materials.

[0030] As Figure 1 and Figure 2 shown, a solar cell 100 includes a silicon substrate 10. The silicon substrate 10 serves as the support and foundation of the cell sheet and has excellent semiconductor properties and mechanical stability. The material of the silicon substrate 10 can be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material can be in single crystal state, polycrystalline state, amorphous state or microcrystalline state (the state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon can be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. Preferably, the silicon substrate 10 is made of n-type single crystal silicon.

[0031] The silicon substrate 10 has a first surface 101 and a second surface 102 which are oppositely arranged. In the embodiments of the present application, the first surface 101 and the second surface 102 can be the light-facing surface and the backlight surface of the silicon substrate 10 respectively. The light-facing surface can be understood as the side facing the sun when the solar cell 100 is installed, and the backlight surface can be understood as the side facing away from the sun when the solar cell 100 is installed. In some embodiments, the solar cell is a bifacial cell, that is, both the first surface 101 and the second surface 102 of the silicon substrate 10 can be used as the light-receiving surfaces and can be used to receive incident light.

[0032] One of the first surface 101 and the second surface 102 has alternately arranged first regions and second regions, or, one of the first surface 101 and the second surface 102 has a first region, and the other of the first surface 101 and the second surface 102 has a second region. Specifically, in a back-contact solar cell, one of the first surface 101 and the second surface 102 has alternately arranged first regions and second regions. That is to say, on these two surfaces, one of them (which may be the first surface 101 or the second surface 102) is divided into alternately arranged first regions and second regions. In a bifacial solar cell, one of the first surface 101 and the second surface 102 has a first region, and the other of the first surface 101 and the second surface 102 has a second region. This regional division is for subsequent different treatments or depositions of different materials on different regions.

[0033] The first doping layer 20 is disposed on the first region, and the second doping layer 30 is disposed on the second region. Doping layers are common techniques in semiconductor processes. By introducing impurities (such as phosphorus, boron, etc.) into the silicon substrate 10, the conductivity of the silicon substrate 10 can be changed. The doping layer can be designed as an n-type or p-type doping according to specific requirements to adjust the conductivity of this region. Doping layers (such as P layers and N layers) mainly function to provide a built-in electric field in the solar cell, and this electric field is the key driving force for the separation of photo-generated electrons and holes. When sunlight irradiates the silicon substrate 10 of the solar cell, photo-generated electron-hole pairs are generated. Under the action of the built-in electric field, electrons and holes move towards the N layer and the P layer respectively, thus realizing the effective separation of photo-generated carriers.

[0034] According to the solar cell provided by the present application, the first doping layer 20 and the second doping layer 30 are doping layers of opposite types, wherein one of the first doping layer 20 and the second doping layer 30 is an n-type doping layer, and the other is a p-type doping layer. In the embodiments of the present application, the first doping layer 20 is a p-type doping layer, and the second doping layer 30 is an n-type doping layer.

[0035] For example, in a solar cell with an n-type single-crystalline silicon as the silicon substrate 10, a p-type doping layer (i.e., the first doping layer 20) and an n-type doping layer (i.e., the second doping layer 30) are provided on its back surface. Among them, the electrode disposed on and connected to the p-type doping layer is used as the positive electrode, and the electrode disposed on and connected to the n-type doping layer is used as the negative electrode.

[0036] In some embodiments, the first passivation layer 40 is formed on the surface of the first doping layer 20 facing away from the silicon substrate 10. The second passivation layer 50 is formed on the surface of the second doping layer 30 facing away from the silicon substrate 10. In the embodiments of the present application, the first passivation layer 40 is a p-type passivation layer, and the second passivation layer 50 is an n-type passivation layer.

[0037] The main function of the passivation layer is to protect the underlying doped layer or silicon substrate 10 from the influence of the external environment, such as oxidation, corrosion, etc. At the same time, the passivation layer can also reduce the recombination rate on the surface of the solar cell. Specifically, the atoms in the passivation layer will fill the unsaturated dangling bonds on the surface of the silicon wafer, reduce the surface state density, and reduce the recombination centers formed by impurity ions in the cell, thereby reducing the loss of photo-generated carriers. Similarly, a second doped layer 30 is provided on the second region, and a second passivation layer 50 is formed on the surface of the second doped layer 30 facing away from the silicon substrate 10. The functions of the second doped layer 30 and the second passivation layer 50 are similar to those of the first doped layer 20 and the first passivation layer 40, but may have different doping concentrations, types, or thicknesses and other parameters due to different regions. Among them, the first passivation layer 40 may include at least one or a combination of an aluminum oxide layer, a silicon oxide layer, a silicon nitride layer, a silicon carbide layer, and a silicon oxynitride layer. For example, in some embodiments, the first passivation layer 40 may include a stacked aluminum oxide layer and a silicon nitride layer, which is not specifically limited herein. The second passivation layer 50 may also include at least one or a combination of an aluminum oxide layer, a silicon oxide layer, a silicon nitride layer, a silicon carbide layer, and a silicon oxynitride layer.

[0038] As Figure 3 shown, for the change curve of the film quality of the cell passivation with the increase of the hydrogen content, there is an optimal passivation window, that is, the position between the two intersection points of the horizontal dotted line and the comprehensive curve, which is located between the vertex of the p-region curve and the vertex of the n-region curve. In this region, it is the inflection point for the generation of visible bubbles with a diameter of more than 2 μm. At this time, the quality of the passivation film layer is the best. When the hydrogen content continues to increase, the bubble content increases, the passivation layer is damaged, and the quality of the passivation film layer becomes poor. On the contrary, if there are no bubbles and the hydrogen content does not reach the vertex of the curve, it may also be due to the poor quality of the passivation film layer resulting in insufficient hydrogen content, and there is also a situation where the quality of the passivation film layer is not good. Therefore, it is necessary to select an appropriate bubble density between the passivation layer and the doped layer to achieve the best passivation film layer quality. Further, the bubble density can be controlled by selecting the temperature, pressure, and atmosphere to obtain a better passivation effect.

[0039] As Figures 4 - 5 shown, in some embodiments, there are bubbles with a first preset value between the first passivation layer 40 and the first doped layer 20, and the first preset value is greater than 0 and less than or equal to 500 / mm 2 , and there are bubbles with a second preset value between the second passivation layer 50 and the second doped layer 30, and the second preset value is greater than 0 and less than or equal to 200 / mm 2 . In the embodiments of the present application, the definition of the bubble is a bubble visible under an optical microscope, and the optical microscope is an optical microscope with a magnification of 50 - 1000 times.

[0040] In the embodiments of the present application, by controlling the first passivation layer 40 and the first doping layer 20 to be 500 / mm 2 , that is, within 1 mm 2 unit area, the number of bubbles is less than 500, that is, it can be determined that the passivation layer of the cell grows well. As an important observation index, the growth of the passivation layer can be intuitively understood, so as to facilitate the rapid and efficient detection of the cell. The present application establishes a corresponding relationship between the bubbles and the passivation effect of the cell, and controls the preset value of the bubbles between the first passivation layer 40 and the first doping layer 20 to be greater than 0 and less than or equal to 500 / mm 2 , and controls the preset value of the bubbles between the second passivation layer 50 and the second doping layer 30 to be greater than 0 and less than or equal to 200 / mm 2 . By controlling the density of the bubbles between the doping layer and the passivation layer interface, the good passivation effect of the cell can be effectively guaranteed.

[0041] Further, the first preset value is greater than 0 and less than or equal to 30 / mm 2 , so as to obtain better passivation film layer quality. Specifically, in such an embodiment, the first preset value can be any value between 10 / mm 2 , 20 / mm 2 , 30 / mm 2 or 1 - 30 / mm 2 , and specific values are not limited here.

[0042] In some embodiments, the second preset value is greater than 0 and less than or equal to 10 / mm 2 , so as to obtain better passivation film layer quality. Specifically, in such an embodiment, the second preset value can be any value between 1 / mm2, 5 / mm 2 , 10 / mm 2 or 1 - 10 / mm 2 , and specific values are not limited here.

[0043] In some embodiments, the first preset value and the second preset value are equal, so as to obtain substantially the same passivation film layer quality for the first passivation layer 40 and the second passivation layer 50, and the cell efficiency is high. The synergistic effect of the first passivation layer 40 and the second passivation layer 50 is better.

[0044] In other embodiments, since the thicknesses of the first passivation layer 40 and the second passivation layer 50 are different. For example, the thickness of the first passivation layer 40 is greater than that of the second passivation layer 50. The first passivation layer 40 not only has good passivation ability, but also can protect the emitter layer of the first doping region. In this way, the first passivation layer 40 has a lower hydrogen solubility and a poorer hydrogen dissolution ability than the second passivation layer 50, and the first preset value is greater than the second preset value.

[0045] In some embodiments, the materials of the first passivation layer 40 and the second passivation layer 50 independently include at least one of silicon oxynitride, silicon nitride, and silicon oxide.

[0046] As Figure 6 shown, in some embodiments, the diameter of the bubbles is greater than or equal to 50 nm and less than or equal to 15 μm. Preferably, the diameter of the bubbles is greater than or equal to 200 nm and less than or equal to 5 μm. When the scale of the bubbles is within this range, on the one hand, it is easy to observe and convenient to detect. On the other hand, when the scale of the bubbles is within this range, it indicates that the film quality of the passivation layer is good.

[0047] In some embodiments, the thickness of the first doping layer 20 is greater than the thickness of the second doping layer 30. Thus, when the silicon substrate 10 is an N-type silicon substrate 10 and the first doping layer 20 is a P-type doping layer, setting the thickness of the first doping layer 20 to be relatively thick can improve the passivation effect of the first surface 101 and enhance the electrical characteristics of the PN junction, such as increasing the reverse breakdown voltage and reducing the leakage current, thereby improving the electrical performance of the solar cell.

[0048] The ratio of the total area of the first region to the total area of the second region ranges from greater than or equal to 50% to less than or equal to 120%. Further, in such an embodiment, the area ratio of the first region to the second region is more preferably greater than or equal to 50% and less than 100%, and most preferably greater than or equal to 60% and less than 100%. This can ensure the area ratio of the P-type doping layer, balance the passivation contact area, and thus improve the conversion efficiency.

[0049] A battery assembly includes the above-mentioned solar cell. Based on the above-mentioned solar cell, those skilled in the art know that by using multiple such solar cells and / or other corresponding existing accessories, the corresponding battery assembly can be obtained.

[0050] In the description of this specification, the descriptions with reference to the terms "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean 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 descriptions 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 any one or more embodiments or examples in a suitable manner.

[0051] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that, Comprising a silicon substrate having a first surface and a second surface disposed opposite to each other; one of the first surface and the second surface has alternately arranged first regions and second regions, or, one of the first surface and the second surface has a first region, and the other of the first surface and the second surface has a second region; A first doping layer disposed on the first region; A first passivation layer formed on a surface of the first doping layer facing away from the silicon substrate; A second doping layer disposed on the second region; A second passivation layer formed on a surface of the second doping layer facing away from the silicon substrate; There are bubbles of a first preset value between the first passivation layer and the first doping layer, and the first preset value is greater than 0 and less than or equal to 500 / mm 2 There are bubbles of a second preset value between the second passivation layer and the second doping layer, and the second preset value is greater than 0 and less than or equal to 200 / mm 2 .

2. The solar cell according to claim 1, characterized in that, The first doping layer is a p-type doping layer and the second doping layer is an n-type doping layer.

3. The solar cell according to claim 1, characterized in that, The first preset value is greater than 0 and less than or equal to 30 / mm 2 .

4. The solar cell according to claim 1, characterized in that, The second preset value is greater than 0 and less than or equal to 10 / mm 2 .

5. The solar cell according to claim 1, characterized in that, The first preset value is equal to the second preset value.

6. The solar cell according to claim 1, wherein The first preset value is greater than the second preset value.

7. The solar cell according to claim 1, wherein The diameter of the bubble is greater than or equal to 50 nm and less than or equal to 15 μm.

8. The solar cell according to claim 1, characterized in that, The diameter of the bubble is greater than or equal to 200 nm and less than or equal to 5 μm.

9. The solar cell according to claim 1, characterized in that, The range of the ratio of the total area of the first region to the total area of the second region is greater than or equal to 50% and less than or equal to 120%.

10. The solar cell according to claim 1, characterized in that, The thickness of the second doping layer is less than the thickness of the first doping layer.

11. A battery assembly, characterized in that, Comprising the solar cell according to any one of claims 1-10.

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