Solar cell and photovoltaic module

Abstract

The present disclosure is applicable to the technical field of photovoltaics. Provided are a solar cell and a photovoltaic module. The solar cell comprises a silicon substrate, wherein there are bubbles having a first preset value between a first passivation layer and a first doped layer, and there are bubbles having a second preset value between a second passivation layer and a second doped layer. The present disclosure can reduce the surface recombination velocity of a solar cell, such that the solar cell has higher open-circuit voltage and short-circuit current.

Description

Solar cell and cell assembly

[0001] The present disclosure claims priority to the Chinese patent application No. 202411260355.4, filed on September 6, 2024, and entitled "Solar cell and cell assembly", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure belongs to the technical field of photovoltaics, and in particular relates to a solar cell and a cell assembly. BACKGROUND

[0003] During the manufacturing process of the cell piece, bubbles are generated between the interfaces of 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. A large amount of hydrogen gathered between the interface of the polysilicon layer and the passivation film will form bubbles, and the bubbles are directly related to the passivation effect. How to achieve good passivation by controlling the size, density, etc. of the bubbles becomes a problem to be solved.

[0004] SUMMARY

[0005] The present disclosure provides a solar cell, which aims to improve the passivation effect by controlling the size, density, etc. of the bubbles.

[0006] The present disclosure is achieved in this way. A solar cell includes a silicon substrate having opposite first and second faces, one of the first and second faces having first and second regions arranged alternately, or one of the first and second faces having the first region and the other of the first and second faces having the second region; a first doped layer located on the first region; a first passivation layer located on a side surface of the first doped layer away from the silicon substrate; a second doped layer located on the second region; a second passivation layer located on a side surface of the second doped layer away from the silicon substrate; the first passivation layer and the first doped layer have bubbles with a first preset value, the first preset value being greater than 0 and less than or equal to 500 / mm 2 ; the second passivation layer and the second doped layer have bubbles with a second preset value, the second preset value being greater than 0 and less than or equal to 200 / mm 2 .

[0007] Optionally, the first doped layer is a p-type doped layer, and the second doped layer is an n-type doped layer.

[0008] Optionally, the first preset value is greater than 0 and less than or equal to 30 / mm 2 .

[0009] Optionally, the second preset value is greater than 0 and less than or equal to 10 / mm 2 .

[0010] Optionally, the first preset value is equal to the second preset value.

[0011] Optionally, the first preset value is greater than the second preset value.

[0012] Optionally, the diameter of the bubble is greater than or equal to 50 nm and less than or equal to 15 μm.

[0013] Optionally, the diameter of the bubble is greater than or equal to 200 nm and less than or equal to 5 μm.

[0014] Optionally, 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%.

[0015] Optionally, the thickness of the second doped layer is less than the thickness of the first doped layer.

[0016] The present disclosure controls the density of the bubble between the first passivation layer and the first doped layer to be greater than 0 and less than or equal to 500 / mm 2 controls the density of the bubble between the second passivation layer and the second doped layer to be greater than 0 and less 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.

[0017] A battery assembly comprising the above-mentioned solar cell, the technical effects of the present disclosure are the same as those of the above-mentioned solar cell, which will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 is a structural schematic diagram of a back contact solar cell provided by the present application;

[0019] Fig. 2 is a structural schematic diagram of a bifacial solar cell provided by the present application;

[0020] Fig. 3 is a parabolic curve diagram of hydrogen content and passivation film quality provided by the present application;

[0021] Fig. 4 is an optical microscope diagram of a bubble provided by the present application;

[0022] Fig. 5 is a partial enlarged view of Fig. 4;

[0023] Fig. 6 is a size diagram of a bubble provided by the present application.

[0024] BRIEF DESCRIPTION OF DRAWINGS: 100, solar cell; 10, silicon substrate; 101, first surface; 102, second surface; 20, first doped layer; 30, second doped layer; 40, first passivation layer; 50, second passivation layer. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, and are only used to explain the present disclosure, and cannot be understood as limitations to the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure, and are not used to limit the present disclosure.

[0026] In the description of the present disclosure, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present disclosure.

[0027] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0028] In the description of the present disclosure, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0029] In the present disclosure, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0030] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present disclosure. For the purpose of simplicity, the elements and settings of particular examples in the following description are set forth by way of illustrations. Of course, they are merely examples and are not intended to limit the present disclosure. Furthermore, the disclosure can refer to a number of different examples herein, and the disclosure can refer to these examples in different ways. This is for the purpose of simplicity and clarity in the description of the disclosure. In no way is the disclosure limited to the examples described herein. Additionally, the disclosure provides examples of various specific processes and materials, but one of ordinary skill in the art can recognize that other processes can be used and / or other materials can be employed.

[0031] As shown in FIG. 1 and FIG. 2, a solar cell 100 includes a silicon substrate 10, which serves as a support and foundation for the cell, 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 single-crystalline, polycrystalline, amorphous, or microcrystalline (a state that has both single-crystalline and amorphous states, referred to as microcrystalline), for example, silicon can be at least one of single-crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. Preferably, the silicon substrate 10 is made of n-type single-crystalline silicon.

[0032] The silicon substrate 10 has a first face 101 and a second face 102, in the embodiments of the present disclosure, the first face 101 and the second face 102 can be the light-receiving face and the back face of the silicon substrate 10, respectively. The light-receiving face can be understood as the face that faces the sun when the solar cell 100 is installed, and the back face can be understood as the face that faces 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 face 101 and the second face 102 of the silicon substrate 10 can serve as light-receiving faces and can be used to receive incident light.

[0033] One of the first face 101 and the second face 102 has first regions and second regions arranged alternately, or one of the first face 101 and the second face 102 has first regions, and the other of the first face 101 and the second face 102 has second regions. Specifically, in a back-contact solar cell, one of the first face 101 and the second face 102 has first regions and second regions arranged alternately, that is, one of the first face 101 and the second face 102 (may be the first face 101 or the second face 102) is divided into first regions and second regions arranged alternately. In a bifacial solar cell, one of the first face 101 and the second face 102 has first regions, and the other of the first face 101 and the second face 102 has second regions. This division of regions is for subsequent different processing or deposition of different materials on different regions.

[0034] The first doped layer 20 is located on the first region, and the second doped layer 30 is located on the second region. The doped layer is a common technology 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 doped layer can be designed as N-type or P-type doping according to specific requirements to adjust the conductivity of the region. The main function of the doped layer (such as P layer and N layer) in the solar cell is to provide a built-in electric field, which is the key driving force for the separation of photo-generated electrons and holes. When sunlight shines on the silicon substrate 10 of the solar cell, photo-generated electron-hole pairs are generated. Under the action of the built-in electric field, the electrons and holes move to the N layer and the P layer respectively, thereby realizing the effective separation of photo-generated carriers.

[0035] According to the solar cell provided by the present disclosure, the first doped layer 20 and the second doped layer 30 are opposite types of doped layers, wherein one of the first doped layer 20 and the second doped layer 30 is an n-type doped layer, and the other is a p-type doped layer. In the embodiment of the present disclosure, the first doped layer 20 is a p-type doped layer, and the second doped layer 30 is an n-type doped layer.

[0036] For example, in a solar cell with n-type monocrystalline silicon as the silicon substrate 10, a p-type doped layer (i.e., the first doped layer 20) and an n-type doped layer (i.e., the second doped layer 30) are arranged on the back surface thereof. The electrode arranged on the p-type doped layer and connected to the p-type doped layer serves as a positive electrode, and the electrode arranged on the n-type doped layer and connected to the n-type doped layer serves as a negative electrode.

[0037] In some embodiments, the first passivation layer 40 is located on the side surface of the first doped layer 20 away from the silicon substrate 10. The second passivation layer 50 is located on the side surface of the second doped layer 30 away from the silicon substrate 10. In the embodiment of the present disclosure, the first passivation layer 40 is a p-type passivation layer, and the second passivation layer 50 is an n-type passivation layer.

[0038] The main role of the passivation layer is to protect the underlying doped layer or silicon substrate 10 from the external environment, such as oxidation, corrosion, etc. At the same time, the passivation layer can also reduce the recombination rate of 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, reduce the recombination centers formed by impurity ions in the cell, and thus reduce 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 side surface thereof away from the silicon substrate 10. The second doped layer 30 and the second passivation layer 50 have similar effects as the first doped layer 20 and the first passivation layer 40, but may have different doping concentrations, types or thicknesses due to the difference in regions. Among them, the first passivation layer 40 can include at least one of an aluminum oxide layer, a silicon oxide layer, a silicon nitride layer, a silicon carbide layer, a silicon oxynitride layer, or a combination of multiple thereof, for example, in some embodiments, the first passivation layer 40 can include an aluminum oxide layer and a silicon nitride layer stacked in sequence, which is not particularly limited here. The second passivation layer 50 can also include at least one of an aluminum oxide layer, a silicon oxide layer, a silicon nitride layer, a silicon carbide layer, a silicon oxynitride layer, or a combination of multiple thereof.

[0039] As shown in FIG. 3, the curve of the quality of the passivation film of the cell wafer with the increase of the hydrogen content, there is an optimal passivation window, that is, the position between the two points where the horizontal dotted line and the comprehensive curve intersect, between the p region curve vertex and the n region curve vertex. In this range, the inflection point of the visible bubble with a diameter of 2 um or more is generated, at this time, the quality of the passivation film is optimal, when the hydrogen content continues to increase, the bubble content increases, the passivation layer is damaged, and the quality of the passivation film is poor, on the contrary, if there is no bubble, the hydrogen content does not reach the curve vertex, it may also be that the quality of the passivation film is poor, resulting in insufficient hydrogen content, and the quality of the passivation film is also poor, so it is necessary to select the appropriate bubble density between the passivation layer and the doped layer to achieve the optimal quality of the passivation film. Further, the bubble density can be controlled by selecting the temperature, pressure and atmosphere to obtain better passivation effect.

[0040] As shown in FIG. 4-5, in some embodiments, the first passivation layer 40 and the first doped layer 20 have a first preset value of bubbles therebetween, the first preset value is greater than 0 and less than or equal to 500 / mm 2 , the second passivation layer 50 and the second doped layer 30 have a second preset value of bubbles therebetween, the second preset value is greater than 0 and less than or equal to 200 / mm 2 In the embodiments of the present disclosure, the definition of the bubble is the bubble visible under the optical microscope, and the optical microscope is an optical microscope with a magnification of 50-1000 times.

[0041] In the embodiments of the present disclosure, the first passivation layer 40 and the first doped layer 20 are controlled at 500 / mm 2That is, in 1mm 2 If the number of bubbles per unit area is less than 500, the passivation layer of the solar cell can be considered to have grown well. This serves as an important observation indicator, providing a direct understanding of the passivation layer's growth and facilitating rapid and efficient testing of the solar cell. This disclosure establishes a correlation between bubbles and the passivation effect of the solar cell, and controls the preset value of bubbles between the first passivation layer 40 and the first doped layer 20 to be greater than 0 and less than or equal to 500 / mm². 2 The preset value of bubbles between the second passivation layer 50 and the second doped layer 30 is controlled to be greater than 0 and less than or equal to 200 / mm. 2 By controlling the density of bubbles at the interface between the doped layer and the passivation layer, a good passivation effect on the solar cell can be effectively guaranteed.

[0042] Furthermore, the first preset value is greater than 0 and less than or equal to 30 / mm. 2 This results in a better passivation film quality. Specifically, in such an embodiment, the first preset value can be 10 / mm. 2 20 / mm 2 30 / mm 2 Or 1-30 / mm 2 Any value between these two values ​​is used, and no specific restrictions are imposed here.

[0043] In some embodiments, the second preset value is greater than 0 and less than or equal to 10 / mm. 2 This results in a better passivation film quality. Specifically, in such an embodiment, the second preset value can be 1 / mm² or 5 / mm². 2 10 / mm 2 Or 1-10 / mm 2 Any value between these two values ​​is used, and no specific restrictions are imposed here.

[0044] In some embodiments, the first preset value and the second preset value are equal, thereby obtaining approximately the same passivation film quality for the first passivation layer 40 and the second passivation layer 50, resulting in high cell efficiency. The synergistic effect of the first passivation layer 40 and the second passivation layer 50 is also better.

[0045] In some 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 the thickness of the second passivation layer 50, the first passivation layer 40 not only has better passivation capability, but also can protect the emitter layer of the first doped region. Thus, the hydrogen solubility of the first passivation layer 40 is lower than that of the second passivation layer 50, and its hydrogen dissolution capability is poor. The first preset value is greater than the second preset value.

[0046] In some embodiments, the material of the first passivation layer 40 and the material of the second passivation layer 50 each independently comprises at least one of silicon oxynitride, silicon nitride and silicon oxide.

[0047] As shown in FIG. 6, in some embodiments, the diameter of the bubble is greater than or equal to 50 nm and less than or equal to 15 μιη. Preferably, the diameter of the bubble is greater than or equal to 200 nm and less than or equal to 5 μιη. The size of the bubble in this range, on the one hand, is easy to observe and convenient to detect, on the other hand, the size of the bubble in this range indicates that the film layer quality of the passivation layer is good.

[0048] In some embodiments, the thickness of the first doped layer 20 is greater than the thickness of the second doped layer 30. In this way, when the silicon substrate 10 is an N-type silicon substrate 10 and the first doped layer 20 is a P-type doped layer, setting the thickness of the first doped layer 20 to be thicker 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, reducing the leakage current, and the like, thereby improving the electrical performance of the cell piece.

[0049] 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%, and in such embodiments, 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%, which is enough to ensure that the area ratio of the P-type doped layer is balanced to improve the conversion efficiency.

[0050] A battery assembly comprising the above-mentioned solar cell, on the basis of the above-mentioned solar cell, a person skilled in the art knows that a corresponding battery assembly can be obtained by using a plurality of the solar cell and / or other corresponding existing accessories.

[0051] In the description of the present specification, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The above only describes the preferred embodiments of the present disclosure and does not limit the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A solar cell, wherein, The solar cell comprises a silicon substrate having opposite first and second surfaces; one of the first and second surfaces has first and second regions arranged alternately, or one of the first and second surfaces has the first region and the other of the first and second surfaces has the second region; a first doped layer on the first region; a first passivation layer on a side surface of the first doped layer away from the silicon substrate; a second doped layer on the second region; a second passivation layer on a side surface of the second doped layer away from the silicon substrate; The first passivation layer and the first doped layer have bubbles with a first preset value, the first preset value being greater than 0 and less than or equal to 500 / mm 2 The second passivation layer and the second doped layer have bubbles with a second preset value, the second preset value being greater than 0 and less than or equal to 200 / mm 2 .

2. The solar cell of claim 1, wherein, the first doped layer is a p-type doped layer and the second doped layer is an n-type doped layer.

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

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

5. The solar cell of claim 1, wherein, The first preset value is equal to the second preset value.

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

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

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

9. The solar cell of claim 1, wherein, 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 of claim 1, wherein, The thickness of the second doped layer is less than the thickness of the first doped layer.

11. A battery assembly, wherein, The solar cell comprises the solar cell of any one of claims 1-10.

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