Solar cell and photovoltaic module

Abstract

The embodiment of the present disclosure relates to the photovoltaic field, and provides a solar cell and a photovoltaic module, wherein the solar cell comprises: a substrate, the substrate has a first surface and a second surface arranged oppositely, the second surface has first regions and second regions arranged alternately, the second regions are light-trapping structures, and the light-trapping structures comprise a plurality of sub-film layers stacked in sequence; a doped conductive layer, the doped conductive layer is located in the first regions; a passivation layer, the passivation layer covers the surface of the doped conductive layer and the surface of the light-trapping structures; and an electrode, the electrode is electrically connected with the doped conductive layer. The performance of the solar cell can be improved.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and in particular to a solar cell and a photovoltaic module. Background Technology

[0002] Solar cells are semiconductor material components that convert sunlight into electrical energy. They are a key component of solar photovoltaic (PV) power generation systems. In this process, the energy of light is converted into electrical energy, generating direct current (DC). This DC current can be stored in batteries for power supply or converted into alternating current (AC) by an inverter to meet the electricity needs of households or businesses.

[0003] There is a need to propose a new structure for solar cells to improve their conversion efficiency. Utility Model Content

[0004] This disclosure provides a solar cell and a photovoltaic module, which can at least improve the conversion efficiency of the solar cell.

[0005] According to some embodiments of this disclosure, one aspect of this disclosure provides a solar cell, comprising: a substrate having a first surface and a second surface disposed opposite to each other, the second surface having an alternately arranged first region and a second region, the second region being a light-trapping structure, the light-trapping structure comprising multiple layers of sequentially stacked sub-films; a doped conductive layer located in the first region; a passivation layer covering the surface of the doped conductive layer and the surface of the light-trapping structure; and an electrode electrically connected to the doped conductive layer.

[0006] In some embodiments, in the direction from the first surface to the second surface, the area of ​​the sub-film layers of adjacent layers projected onto the substrate surface decreases sequentially.

[0007] In some embodiments, the ratio of the area of ​​the orthographic projection of two adjacent sub-film layers onto the substrate surface is 30% to 70%.

[0008] In some embodiments, at least two of the sub-film layers in the multiple sub-film layers within the light-trapping structure have orthographic projections on the substrate surface that at least partially overlap.

[0009] In some embodiments, the size of the sub-film layer closest to the first surface is 10 μm to 35 μm, and the size of the sub-film layer furthest from the first surface is 3 μm to 20 μm.

[0010] In some embodiments, the subfilm layer has a rectangular shape when projected onto the first surface of the substrate.

[0011] In some embodiments, the number of sub-film layers in a light-trapping structure is 2 to 6.

[0012] In some embodiments, the passivation layer covers the sidewalls and top surface of the subfilm layer.

[0013] In some embodiments, the passivation layer includes: multiple stacked sub-passivation layers, the top surface of the sub-passivation layers being flush with the top surface of the corresponding sub-film layer.

[0014] In some embodiments, a tunneling layer is provided between the doped conductive layer and the substrate.

[0015] In some embodiments, the system further includes a second doped conductive layer located in the first region, which is different from the doped conductive layer.

[0016] According to some embodiments of this disclosure, another aspect of this disclosure also provides a photovoltaic module, including: a battery string, the battery string including: a plurality of solar cells as described above; a solder ribbon, the solder ribbon being electrically connected to at least two solar cells to connect adjacent solar cells in series; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film away from the battery string.

[0017] The technical solution provided in this disclosure has at least the following advantages: when forming the light-trapping structure, the light-trapping structure is composed of multiple stacked sub-film layers to increase the surface area of ​​the light-trapping structure, thereby further improving the light-trapping structure's ability to scatter light and reflecting the light transmitted through the substrate back to the substrate as much as possible for re-absorption, thereby reducing light reflection damage and improving the performance of the solar cell. Attached Figure Description

[0018] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the surface structure of a solar cell provided in an embodiment of the present disclosure;

[0020] Figure 2 This is an enlarged schematic diagram of the surface structure of a solar cell provided in an embodiment of the present disclosure;

[0021] Figure 3 A cross-sectional view of a solar cell provided in an embodiment of this disclosure;

[0022] Figure 4 A cross-sectional view of a solar cell provided for another embodiment of this disclosure;

[0023] Figure 5 A partial perspective view of a photovoltaic module provided in an embodiment of this disclosure;

[0024] Figure 6 This is a cross-sectional view of a photovoltaic module provided in one embodiment of the present disclosure. Detailed Implementation

[0025] As can be seen from the background technology, although current solar cells have light-trapping structures, the current light-trapping structures are pyramid-shaped. Although the pyramid shape can also reflect light, the reflection loss caused by the pyramid shape is also relatively large. Therefore, it is necessary to propose a textured structure to reduce reflection loss while reflecting light.

[0026] In this embodiment of the present disclosure, when forming the light-trapping structure, the light-trapping structure is configured to consist of multiple stacked sub-film layers to increase the surface area of ​​the light-trapping structure, thereby further improving the light-trapping structure's ability to scatter light and reflecting the light transmitted through the substrate back to the substrate as much as possible for re-absorption, thereby reducing light reflection damage and improving the performance of the solar cell.

[0027] In the description of the embodiments of this disclosure, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0031] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0032] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0033] In the accompanying drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0034] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly" on the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Additionally, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0035] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0036] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0037] refer to Figures 1 to 3 , Figure 1 This is an enlarged schematic diagram of a substrate surface provided in an embodiment of the present disclosure. Figure 2 This is an enlarged schematic diagram of a velvet structure provided in an embodiment of the present disclosure. Figure 3 This is a cross-sectional view of a solar cell provided in one embodiment of the present disclosure.

[0038] In some embodiments, the solar cell may further include: a substrate 100 having a first surface 110 and a second surface 120 disposed opposite to each other, the second surface 120 having an alternately arranged first region 130 and a second region 140, and at least one light-trapping structure 150 provided on the second region 140, the light-trapping structure 150 including multiple layers of sub-film layers 160 stacked sequentially.

[0039] The solar cell may include a doped conductive layer 102, which is located in the first region 130.

[0040] The solar cell may include a passivation layer 103, which covers the surface of the doped conductive layer 102 and the surface of the light-trapping structure 150.

[0041] A solar cell may include an electrode 105, which is electrically connected to a doped conductive layer 102.

[0042] In this embodiment of the present disclosure, when forming the light trapping structure 150, the light trapping structure 150 is configured to be composed of multiple stacked sub-film layers 160 to increase the surface area of ​​the light trapping structure 150, thereby further improving the light scattering ability of the light trapping structure 150 and reflecting the light transmitted through the substrate 100 back to the substrate 100 as much as possible for re-absorption, thereby reducing light reflection damage and improving the performance of the solar cell.

[0043] It is understandable that solar cells can be BC (Back Contact) cells, TOPCon (Tunnel Oxide Passivated Contact) cells, tandem cells containing BC cells, or tandem cells containing TOPCon cells, etc., which will form a local light trapping structure 150. The following explanation will take TOPCon cells as an example.

[0044] The substrate 100 can be made of an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material can be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon can be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. Taking a silicon wafer as an example, a silicon wafer with a resistivity of 0.3 Ω·cm to 7 Ω·cm can be selected, and a silicon wafer with a resistivity of 0.5 Ω·cm to 2 Ω·cm can be further selected. The resistivity of the silicon wafer can be adjusted by doping it.

[0045] In some embodiments, the solar cell is a single-sided cell, in which case the first surface 110 of the substrate 100 can serve as a light-receiving surface to receive incident light, and the second surface 120 serves as a backlighting surface. In some embodiments, the solar cell is a bi-sided cell, in which case both the first surface 110 and the second surface 120 of the substrate 100 can serve as light-receiving surfaces and can both be used to receive incident light. It is understood that the backlighting surface referred to in the embodiments of this disclosure can also receive incident light, but the degree of reception of incident light is weaker than that of the light-receiving surface, and therefore it is defined as a backlighting surface.

[0046] In some embodiments, a texturing process can be performed on the first surface 110 of the substrate 100 to form a textured surface, thereby enhancing the absorption and utilization efficiency of the first surface 110 of the substrate 100 for incident light. In some embodiments, the textured surface can be a pyramid textured surface. As a common textured surface, pyramid textured surface not only reduces the reflectivity of the substrate 100 surface but also forms light traps, enhancing the absorption effect of the substrate 100 for incident light and improving the photoelectric conversion efficiency of the solar cell.

[0047] In some embodiments, in the direction from the first surface 110 to the second surface 120, the areas of the orthographic projections of adjacent sub-film layers 160 onto the surface of the substrate 100 decrease sequentially. In other words, in the direction away from the substrate 100, the size of the stacked sub-film layers 160 gradually decreases, and the size of the lower sub-film layer 160 is larger than that of the upper sub-film layer 160. On the one hand, the larger size of the lower sub-film layer 160 can facilitate the support of the upper sub-film layer 160, thereby improving the reliability of the solar cell. On the other hand, during the formation of the light-trapping structure 150, the etching effect of the lower layer will decrease as the etching reagent is consumed.

[0048] In some embodiments, in the direction from the first surface 110 to the second surface 120, the ratio of the area of ​​the orthographic projection of two adjacent sub-film layers 160 onto the surface of the substrate 100 is 30% to 70%, for example, 30%, 40%, 50%, 60% or 70%. In other words, the ratio of the area of ​​the sub-film layer 160 relatively close to the first surface 110 to the area of ​​the sub-film layer 160 relatively far from the first surface 110 projected onto the surface of the substrate 100 is 30% to 70%. It can be understood that the larger the area ratio, the greater the difference in size between the lower sub-film layer 160 and the upper sub-film layer 160. However, the smaller the difference in size between the lower sub-film layer 160 and the upper sub-film layer 160, the worse the ability of the upper sub-film layer 160 to increase the surface area of ​​the light-trapping structure 150. The greater the difference in size between the lower sub-film layer 160 and the upper sub-film layer 160, the more the upper sub-film layer 160 is etched, which will lead to more etching of the substrate 100 and a decrease in the ability of the substrate 100 to form photogenerated carriers.

[0049] In some embodiments, at least two sub-film layers 160 in the light-trapping structure 150 have orthographic projections onto the surface of the substrate 100 that at least partially overlap. For example, the light-trapping structure 150 includes three sub-film layers 160, and the sequentially stacked sub-film layers 160 are a first sub-film layer 160, a second sub-film layer 160, and a third sub-film layer 160. The orthographic projection of the second sub-film layer 160 onto the surface of the substrate 100 may partially overlap with the orthographic projection of the first sub-film layer 160 onto the surface of the substrate 100. Alternatively, the second sub-film layer 160 may have a partial orthographic projection onto the substrate 100. The orthographic projection of the surface 0 is located within the first sub-film layer 160. The orthographic projection of the third sub-film layer 160 on the surface of the substrate 100 may partially coincide with the orthographic projection of the first sub-film layer 160 on the surface of the substrate 100, or the orthographic projection of the third sub-film layer 160 on the surface of the substrate 100 may be located within the first sub-film layer 160. The orthographic projection of the third sub-film layer 160 on the surface of the substrate 100 may partially coincide with the orthographic projection of the second sub-film layer 160 on the surface of the substrate 100, or the orthographic projection of the third sub-film layer 160 on the surface of the substrate 100 may be located within the second sub-film layer 160.

[0050] In other words, different sub-membrane layers 160 can be misaligned or aligned with each other.

[0051] The misalignment between the sub-film layers 160 can further increase the surface area of ​​the light-trapping structure 150. The misaligned sub-film layers 160 will expose part of the bottom surface of the upper sub-film layer 160, thereby further increasing the surface area of ​​the light-trapping structure 150.

[0052] The "at least two layers" mentioned above can refer to two adjacent sub-membrane layers 160, or to any two sub-membrane layers 160.

[0053] It should be noted that the upper layer here refers to the sub-film layer 160 that is further away from the first surface 110, and the lower layer refers to the sub-film layer 160 that is closer to the first surface 110.

[0054] In some embodiments, the size of the sub-film layer 160 closest to the first surface 110 is 10μm to 35μm, for example, 10μm, 15μm, 20μm, 25μm, 30μm or 35μm, etc., and the size of the sub-film layer 160 furthest from the first surface 110 is 3μm to 20μm, for example, 3μm, 5μm, 8μm, 15μm, 17μm or 20μm, etc.

[0055] The larger the size of the sub-film layer 160, the larger the relative surface area of ​​the light-trapping structure 150 will be. For the lower sub-film layer 160, it is necessary to control the size of the sub-film layer 160 closest to the first surface 110 to avoid excessive etching of the substrate 100, thereby improving the reliability of the formed solar cell. For the upper sub-film layer 160, it is necessary to control the size of the sub-film layer 160 furthest from the first surface 110 to avoid completely etching the sub-film layer 160 furthest from the first surface 110, thereby avoiding the loss of surface area of ​​the light-trapping structure 150.

[0056] It should be noted that the size here refers to any one of the length, width or diagonal length of the orthographic projection pattern of the sub-film layer 160 on the first surface 110. Taking the orthographic projection pattern of the sub-film layer 160 on the first surface 110 as a regular quadrilateral as an example, the size of the sub-film layer 160 is any one of the length, width or diagonal length of the regular quadrilateral. In practical applications, the orthographic projection pattern of the sub-film layer 160 on the first surface 110 can also be an irregular polygon. In this case, the length, width, or diagonal length of the orthographic projection pattern of the sub-film layer 160 on the first surface 110 is not absolute, but is artificially defined to characterize the size of the sub-film layer 160. For example, the orthographic projection pattern of the sub-film layer 160 on the first surface 110 is an irregular quadrilateral. In this case, the length of the sub-film layer 160 can be defined as the side length of the longest side of the irregular quadrilateral, the width of the sub-film layer 160 can be defined as the side length of the shortest side of the irregular quadrilateral, and the diagonal length of the sub-film layer 160 can be defined as the length of the longest diagonal of the irregular quadrilateral. It is understood that the above is only an exemplary illustration, and in practice, it can be flexibly defined according to actual needs. In addition, the orthographic projection pattern of the sub-film layer 160 on the first surface 110 can be an irregular quadrilateral, or other irregular polygons, circles, or irregular shapes that are approximately circular. In this case, the size of the sub-film layer 160 is selected from multiple regions of different specific areas in the sub-film layer 160. These specific areas can be flexibly defined according to actual needs, and then the average value of the length, width, diagonal, or diameter of the multiple regions of different specific areas is calculated.

[0057] In some embodiments, the shape of the subfilm layer 160 projected onto the first surface 110 of the substrate 100 is a rectangular portion. Here, the rectangular portion can refer to a regular rectangular shape, or a shape similar to a rectangle, for example, a rectangle in its entirety but with some curved edges, or a polygon with a rectangular body, such as a rectangle with missing corners or protrusions extending beyond the rectangle.

[0058] In some embodiments, the number of sub-film layers in a light-trapping structure is 2 to 6, for example, 2, 3, 4, 5, or 6 layers. It is understood that the more sub-film layers in a light-trapping structure, the larger the relative surface area of ​​the structure, and the stronger its ability to improve the performance of the solar cell. Similarly, the more sub-film layers, the thicker the etched substrate, which can cause some damage. Therefore, setting the number of sub-film layers in the light-trapping structure to 2 to 6 layers considers improving the performance of the solar cell while avoiding affecting its reliability.

[0059] In some embodiments, a tunneling layer 101 is further disposed between the substrate 100 and the doped conductive layer 102. The material of the tunneling layer 101 may be silicon oxide, and the thickness may be 0.5 nm to 3 nm, or more specifically 1.5 nm to 2.5 nm. If the thickness of the tunneling layer 101 is too thick, it will affect the tunneling effect of the charge carriers, while if the thickness of the tunneling layer 101 is too thin, it may affect the passivation effect of the tunneling layer 101 on the substrate 100.

[0060] The tunneling layer 101 can be deposited directly on the second surface 120 by PECVD (plasma chemical vapor deposition).

[0061] The material of the doped conductive layer 102 can be phosphorus-doped polycrystalline silicon, and the surface doping concentration of the doped conductive layer 102 is 2E20cm⁻¹. -3 ~3E21cm -3 Further, it could be 5E20cm -3 ~2E21cm -3 A polycrystalline silicon layer can be formed on the surface of the tunneling layer 101 by PECVD, and then a doped conductive layer 102 can be formed by phosphorus doping.

[0062] After forming the doped conductive layer 102, a mask is formed on the surface of the first region 130, and the doped conductive layer 102 located in the second region 140 is etched by laser irradiation and wet etching to form a doped conductive layer 102 located only in the first region 130.

[0063] Laser irradiation can be performed using green picosecond or violet picosecond lasers, with laser power ranging from 5W to 120W, and further from 10W to 50W; frequency ranging from 100kHz to 1000kHz, and further from 300kHz to 600kHz; scanning rate ranging from 10000mm / s to 100000mm / s, and further from 10000mm / s to 60000mm / s; and laser spot overlap rate ranging from 0% to 80%, and further from 0% to 20%.

[0064] During the formation of the doped conductive layer 102, a glass layer is formed. The glass layer can be removed by etching. The etching reagent can be hydrofluoric acid with a concentration of 10% to 30%.

[0065] During the formation of the doped conductive layer 102 on the second surface 120, a wrap-around plating is also formed on the sidewall of the substrate 100 and the first surface 110. The wrap-around plating can be removed by alkaline etching, and the mask and the doped conductive layer 102 on the first region 130 can be removed.

[0066] Simultaneously, at least one light-trapping structure 150 can be formed in the second region 140 using alkaline etching. The alkaline etching can be performed using a mixed solution of sodium hydroxide or potassium hydroxide, TMAH (tetramethylammonium hydroxide) and pure water. The process temperature of alkaline etching can be 50℃~90℃, and further can be 60℃~80℃, and the time can be 100s~500s, and further can be 200s~300s.

[0067] It is understandable that after laser irradiation, the second region 140 of the substrate 100 has more atomic steps and crystal defects, making it more susceptible to corrosion in alkaline solutions. The change in crystal structure results in the formation of at least one light-trapping structure 150 during the corrosion process. The crystal structure of the laser region can be adjusted by increasing the laser power or the laser overlap rate. Alternatively, the temperature of the tank machine can be increased to generate the light-trapping structure 150 rapidly under high-temperature conditions. Different process conditions can achieve sub-film layers 160 of different sizes.

[0068] The passivation layer 103 can be formed directly by ALD (atomic layer deposition).

[0069] In some embodiments, the thickness of the passivation layer 103 is 2nm to 7nm, for example, 2nm, 3nm, 4nm, 5nm, 6nm, or 7nm. If the thickness of the passivation layer 103 is too thin, it will affect the passivation effect; if it is too thick, the uniformity of the passivation layer 103 may be difficult to control. Therefore, the thickness of the passivation layer 103 is set to 2nm to 7nm to consider the passivation effect while avoiding negative impacts from the passivation layer 103.

[0070] In some embodiments, the passivation layer 103 covers the sidewalls and top surface of the subfilm layer 160. In other words, the passivation layer 103 is used to passivate the exposed surface of the light trapping structure 150, thereby further improving the passivation effect of the passivation layer 103 on the substrate 100.

[0071] In some embodiments, the passivation layer 103 includes: multiple stacked sub-passivation layers, the top surface of the sub-passivation layer being flush with the top surface of the corresponding sub-film layer 160. In other words, one sub-passivation layer corresponds to one sub-film layer 160. By depositing layer by layer, the reliability of the passivation layer 103 covering the light trapping structure 150 can be improved while the density of the passivation layer 103 itself can be improved, thereby further improving the reliability of the formed solar cell.

[0072] In some embodiments, the solar cell may further include an antireflection layer 104, which may be one or more stacked films of silicon nitride, silicon oxynitride, and silicon oxide. The thickness of the antireflection layer 104 may be 60 nm to 130 nm, and the antireflection layer 104 may be formed by PECVD.

[0073] The material of electrode 105 may include silver-coated copper, silver paste or other conductive materials, and electrode 105 may be formed by screen printing.

[0074] The solar cell may further include: an emitter 106, which covers the first surface 110 of the substrate 100. The doping type of the emitter 106 is opposite to that of the substrate 100, and forms a PN junction with the substrate 100. The solar cell may further include: a second passivation layer 107, which covers the surface of the emitter 106 away from the substrate 100, and provides good passivation for the first surface 110 of the substrate 100, reducing the defect state density of the first surface 110 of the substrate 100 and effectively suppressing carrier recombination on the first surface 110 of the substrate 100.

[0075] In some embodiments, the doping concentration of the emitter 106 is 3E18cm⁻¹. -3 ~3E19cm -3 The sheet resistance is 40Ω / sq to 300Ω / sq, and the further sheet resistance is 150Ω / sq to 250Ω / sq.

[0076] The second passivation layer 107 can also play a good role in reducing reflection, reducing the reflection of incident light by the first surface 110 of the substrate 100, and improving the utilization rate of incident light by the substrate 100.

[0077] The second passivation layer 107 can be formed in the same process step as the passivation layer 103. When the anti-reflection layer 104 is formed, the anti-reflection layer 104 is also formed on the first surface 110.

[0078] The solar cell may also include a second electrode 108, which is electrically connected to the emitter 106.

[0079] In this embodiment of the present disclosure, when forming the light trapping structure 150, the light trapping structure 150 is configured to be composed of multiple stacked sub-film layers 160 to increase the surface area of ​​the light trapping structure 150, thereby further improving the light scattering ability of the light trapping structure 150 and reflecting the light transmitted through the substrate 100 back to the substrate 100 as much as possible for re-absorption, thereby reducing light reflection damage and improving the performance of the solar cell.

[0080] Another embodiment of this disclosure also provides a solar cell, which is a back contact cell. The following will describe a solar cell provided by an embodiment of this disclosure with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those described above can be referred to the above embodiments, and will not be repeated hereafter.

[0081] refer to Figure 4 , Figure 4 This is a cross-sectional structural diagram of a solar cell provided in another embodiment of the present disclosure.

[0082] In some embodiments, the solar cell may further include: a substrate 100 having a first surface 110 and a second surface 120 disposed opposite to each other, the second surface 120 having an alternately arranged first region 130 and a second region 140, and at least one light-trapping structure 150 provided on the second region 140, the light-trapping structure 150 including multiple layers of sub-film layers 160 stacked sequentially.

[0083] The solar cell may include a doped conductive layer 102, which is located in the first region 130.

[0084] The solar cell may include a passivation layer 103, which covers the surface of the doped conductive layer 102 and the surface of the light-trapping structure 150.

[0085] A solar cell may include an electrode 105, which is electrically connected to a doped conductive layer 102.

[0086] In some embodiments, the solar cell may further include a second doped conductive layer 109, which is located in a first region 130 different from the doped conductive layer 102. In other words, the doped conductive layer 102 and the second doped conductive layer 109 are alternately located on the surface of the first region 130 for collecting different charge carriers.

[0087] In some embodiments, the doping types of the doped conductive layer 102 and the second doped conductive layer 109 are different.

[0088] In some embodiments, the solar cell may further include a tunneling layer 101, an antireflection layer 104, and a second electrode 108.

[0089] It should be noted that the substrate 100, the first surface 110, the second surface 120, the first region 130, the second region 140, the light trapping structure 150, the sub-film layer 160, the tunneling layer 101, the doped conductive layer 102, the passivation layer 103, the antireflection layer 104, and the electrode 105 can be referred to in the above embodiments, and will not be described again in this embodiment.

[0090] Another embodiment of this disclosure also provides a photovoltaic module, which may include a plurality of solar cells as described in the above embodiments. The following will describe a photovoltaic module provided in an embodiment of this disclosure with reference to the accompanying drawings. It should be noted that the same or corresponding parts as described above can be referred to the above embodiments, and will not be repeated hereafter.

[0091] refer to Figure 5 and Figure 6 ,in, Figure 5 This is a partial three-dimensional schematic diagram of a photovoltaic module provided in an embodiment of the present disclosure. Figure 6 for Figure 5 A partial cross-sectional schematic diagram along the first section direction BB1.

[0092] The photovoltaic module includes: a battery string, which includes: a plurality of solar cells 40 as described above; a solder ribbon 43 electrically connected to at least two solar cells 40 to connect adjacent solar cells 40 in series; an encapsulating film 41 for covering the surface of the battery string; and a cover plate 42 for covering the surface of the encapsulating film 41 away from the battery string.

[0093] In some embodiments, the encapsulating film 41 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the first or second sides of the solar cell, and the second encapsulating layer covers the other of the first or second side of the solar cell. Specifically, at least one of the first or second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene elastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first or second encapsulating layer can also be an EP film, an EPE film, or a PVP film. Here, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film + POE film + EVA film; and PVP film refers to a co-extruded film formed by stacking POE film + EVA film + POE film. Co-extruded films can be prepared by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0094] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module will no longer have the concept of a first encapsulation layer and a second encapsulation layer. That is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0095] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulating film 41 can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0096] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the embodiments of this disclosure. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the embodiments of this disclosure; therefore, the scope of protection of the embodiments of this disclosure should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other. The second surface has a first region and a second region arranged alternately. At least one light-trapping structure is provided on the second region. The light-trapping structure includes multiple layers of sub-films stacked sequentially. A doped conductive layer is located in the first region; A passivation layer that covers the surface of the doped conductive layer and the surface of the light-trapping structure; An electrode, which is electrically connected to the doped conductive layer.

2. The solar cell according to claim 1, characterized in that, In the direction from the first surface to the second surface, the area of ​​the sub-film layers projected onto the substrate surface of adjacent layers decreases sequentially.

3. The solar cell according to claim 2, characterized in that, In the direction from the first surface to the second surface, the ratio of the area of ​​the orthographic projection of two adjacent sub-film layers onto the substrate surface is 30% to 70%.

4. The solar cell according to claim 1, characterized in that, At least two of the sub-film layers in the light-trapping structure have orthographic projections on the substrate surface that at least partially overlap.

5. The solar cell according to claim 1, characterized in that, The size of the sub-film layer closest to the first surface is 10 μm to 35 μm, and the size of the sub-film layer furthest from the first surface is 3 μm to 20 μm.

6. The solar cell according to claim 1, characterized in that, The sub-film layer has a rectangular shape when projected onto the first surface of the substrate.

7. The solar cell according to any one of claims 1 to 6, characterized in that, The number of sub-film layers in the light-trapping structure is 2 to 6.

8. The solar cell according to claim 1, characterized in that, The passivation layer covers the sidewalls and top surface of the sub-film layer.

9. The solar cell according to claim 1, characterized in that, The passivation layer includes: multiple stacked sub-passivation layers, the top surface of which is flush with the top surface of the corresponding sub-film layer.

10. The solar cell according to claim 1, characterized in that, A tunneling layer is provided between the doped conductive layer and the substrate.

11. The solar cell according to claim 1, characterized in that, Also includes: A second doped conductive layer is located in the first region, which is different from the doped conductive layer.

12. A photovoltaic module, characterized in that, include: Battery string, the battery string comprising: a plurality of solar cells as described in any one of claims 1 to 11; solder strips, The solder strip is electrically connected to at least two solar cells to connect adjacent solar cells in series. An encapsulating film, the encapsulating film being used to cover the surface of the battery string; A cover plate for covering the surface of the encapsulating film away from the battery string.

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