Solar cell, solar cell module, and manufacturing method for solar cell

Abstract

Provided in the present application are a solar cell, a solar cell module, and a manufacturing method for a solar cell, so as to guarantee good ohmic contact between a first electrode and a passivation layer, improve the transmission efficiency of carriers, and weaken parasitic absorption of light, thereby ensuring the cell efficiency of TOPCon cells. The solar cell comprises a semiconductor substrate, an ultrathin dielectric layer, a passivation layer, a first electrode and a metal crystal, wherein the semiconductor substrate has a light receiving face and a backlight face which are opposite each other, the ultrathin dielectric layer is located on at least one of the backlight face and the light receiving face of the semiconductor substrate, the passivation layer is located on the ultrathin dielectric layer, the first electrode is located on the passivation layer, and the metal crystal is located in the passivation layer; and the metal crystal comprises a first metal crystal, one end face of the first metal crystal abuts against the ultrathin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

Description

Solar cell, solar cell module and method for manufacturing solar cell

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese application No. 2023113557296 filed on October 18, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a solar cell, a solar cell assembly, and a method for manufacturing a solar cell. Background Art

[0004] A solar cell is a device that utilizes solar energy and directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. Such solar cells include tunnel oxide passivated contact solar cells (TOPCon).

[0005] The doped passivation layer of the TOPCon cell is deposited with a thicker Poly layer, which results in a longer time for carriers to pass through the passivation layer and severe parasitic absorption of light, thereby affecting the cell efficiency of the TOPCon cell.

[0006] Application Contents

[0007] The purpose of the present application is to provide a solar cell, a solar cell module and a method for manufacturing a solar cell, which are used to improve the carrier transmission efficiency and reduce the parasitic absorption of light to ensure the cell efficiency of the TOPCon cell.

[0008] In order to achieve the above-mentioned objectives, in a first aspect, the present application provides a solar cell. The solar cell comprises: a semiconductor substrate, an ultra-thin dielectric layer, a passivation layer (also referred to as a doped semiconductor layer in the art), a first electrode, and a metal crystal. The semiconductor substrate has a light-receiving surface and a backlight surface relative to each other, the ultra-thin dielectric layer is located on at least one of the backlight surface and the light-receiving surface of the semiconductor substrate, the passivation layer is located on the ultra-thin dielectric layer, the first electrode is located on the passivation layer, and the metal crystal is located in the passivation layer. The metal crystal comprises a first metal crystal, one end face of the first metal crystal abuts the ultra-thin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

[0009] Compared to the prior art, the solar cell provided by the present application can improve carrier transfer efficiency, reduce or eliminate the loss of on-state voltage, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer. Furthermore, because one end face of the first metal crystal abuts the ultra-thin dielectric layer and the other end face of the first metal crystal is connected to the first electrode, a metal-ultra-thin dielectric-semiconductor structure is formed. Furthermore, because the first metal crystal is located within the passivation layer, the first metal crystal is in full contact with the passivation layer. Based on this, by controlling the ratio of the first metal crystal, the fill factor can be optimized and the on-state voltage and fill factor can be balanced. Furthermore, under the action of the first metal crystal, the carriers are facilitated to move to the first electrode, accelerating the carrier transfer rate and thereby shortening the time required for the carriers to pass through the passivation layer. In addition, because the first metal crystal does not pass through the ultra-thin dielectric layer into the semiconductor substrate, at this time, not only can the ultra-thin dielectric layer be ensured not to be damaged, but also the function of the ultra-thin dielectric layer can be ensured not to be affected. In other words, good chemical passivation and tunneling effect of the ultra-thin dielectric layer are guaranteed. At the same time, the impact on the opening voltage can also be reduced to avoid damage to the semiconductor substrate, thereby ensuring that the function of the semiconductor substrate is not affected, and further ensuring the performance of the solar cell.

[0010] In summary, the first metal crystal abuts against the ultra-thin dielectric layer without destroying the structure of the ultra-thin dielectric layer, thus ensuring good chemical passivation and tunneling effect of the ultra-thin dielectric layer. The ultra-thin dielectric layer acts as a tunneling transmission layer for majority carriers, which can transmit majority carriers in the semiconductor substrate through the ultra-thin dielectric layer. Next, the first metal crystal takes on the role of quickly transmitting majority carriers through the ultra-thin dielectric layer to the first electrode to ensure a higher fill factor. The majority carrier transmission efficiency with good passivation structure can obtain a smaller contact resistivity and series resistance, thereby ensuring a higher battery efficiency.

[0011] In one implementation, a passivation layer is partially provided on at least one of the backlight surface and the light-receiving surface.

[0012] In one implementation, a ratio of the number of the first metal crystals to the total number of the metal crystals is greater than or equal to 2% and less than or equal to 20%.

[0013] When the above technical solution is adopted, it is possible to avoid the influence of the tunneling-polycrystalline carrier tunneling effect caused by an excessive number of first metal crystals.

[0014] In one implementation, the width of the first metal crystals gradually decreases along a direction from the first electrode to the passivation layer.

[0015] When using the above technical solution, the width of the first metal crystal gradually decreases along the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal recombination at the metal-ultra-thin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases along the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystal and the first electrode, which helps improve the transmission efficiency of majority carriers transported by the first metal crystal to the first electrode.

[0016] In one implementation, the metal crystal further includes a second metal crystal. The second metal crystal is connected to the first electrode and spaced apart from the first metal crystal. The thickness of the second metal crystal is less than that of the passivation layer, and the thickness direction of the second metal crystal and the thickness direction of the passivation layer are both aligned in a direction from the backlight surface to the light-receiving surface.

[0017] When the above technical solution is adopted, it is not only more conducive to the movement of carriers to the first electrode, but also further accelerates the carrier transmission rate, thereby further shortening the time required for the carriers to pass through the passivation layer to ensure the battery efficiency of the TOPCon battery. At the same time, it can also reduce the contact resistance between the first electrode and the passivation layer. Furthermore, since the thickness of the second metal crystal is less than that of the passivation layer, the second metal crystal can be prevented from damaging the ultra-thin dielectric layer and the semiconductor substrate, thereby ensuring the performance of the solar cell.

[0018] In one implementation, the plurality of second metal crystals are distributed at intervals, and / or the ratio of the number of the second metal crystals to the total number of the metal crystals is greater than or equal to 50% and less than or equal to 90%.

[0019] In one implementation, the metal crystal further includes a third metal crystal. The third metal crystal is spaced apart from the first electrode, the ultra-thin dielectric layer, and the second metal crystal.

[0020] In one implementation, a plurality of third metal crystals are discretely distributed within the passivation layer; and / or, along a direction from the passivation layer to the first electrode, the spacing between the third metal crystals and the first electrode is smaller than the spacing between the third metal crystals and the ultra-thin dielectric layer; and / or, the ratio of the number of second metal crystals to the total number of metal crystals is less than or equal to 5%. and / or, the ratio of the average volume of the third metal crystals to the average volume of the second metal crystals is less than or equal to 10%.

[0021] When using the above technical solution, smaller third metal crystals tend to separate from the first electrode body. While the presence of these third metal crystals is undesirable during actual manufacturing, their presence is unavoidable. Therefore, it is necessary to control the average volume and number of the third metal crystals within the above ranges to minimize their impact on solar cell efficiency.

[0022] In one implementation, when the passivation layer is a doped passivation layer, the doped passivation layer includes: a first heavily doped region and a first lightly doped region. The first heavily doped region is connected to the first electrode. The first lightly doped region is located on one side of the first heavily doped region, and the doping concentration of the first heavily doped region is greater than the doping concentration of the first lightly doped region.

[0023] When the above technical solution is adopted, since the first heavily doped region is connected to the corresponding first electrode, it is possible to ensure that there is good ohmic contact between the first electrode and the doped passivation layer, so as to improve the fill factor. Furthermore, since the first shallowly doped region is not in contact with the first electrode, a non-metallic contact area is formed, and the doping concentration of the first shallowly doped region is low. Therefore, it is beneficial to reduce the Auger recombination of the non-metallic contact area and reduce the parasitic absorption of ultraviolet light by the doped passivation layer. In addition, compared with the prior art, in order to ensure good ohmic contact between the doped passivation layer and the first electrode, under normal circumstances, the silver paste printing line width used to form the first electrode during screen printing is wider, resulting in higher unit consumption and high cost. However, in the present application, by connecting the first electrode to the first heavily doped region, it is ensured that there is good ohmic contact between the first electrode and the doped passivation layer. Therefore, the silver paste printing line width used to form the first electrode can be appropriately narrowed to reduce the production cost.

[0024] In one implementation, the thickness of the doped passivation layer is greater than or equal to 50 nm and less than or equal to 200 nm.

[0025] When adopting the above-mentioned technical solution, compared with the existing technology, in the implementation method of the present application, the carrier transfer efficiency can be improved, the loss of the opening voltage can be reduced or eliminated, and excellent electrical contact performance between the electrode and the passivation layer can be ensured without reducing the thickness of the doped passivation layer.

[0026] In one implementation, the thickness of the ultra-thin dielectric layer is greater than or equal to 1 nm and less than or equal to 2 nm. The thickness of the ultra-thin dielectric layer is aligned with the direction from the light-receiving surface to the backlight surface. And / or, the material of the ultra-thin dielectric layer includes one of silicon oxide, hafnium oxide, aluminum oxide, and silicon nitride.

[0027] In a second aspect, the present application also provides a solar cell assembly, which includes two or more solar cells as described above, wherein the two or more solar cells are electrically connected in series, and the solar cell assembly also includes a conductive wire, which is used to electrically connect the two or more solar cells in series, and the projection of the conductive wire in the plane where the passivation layer is located partially overlaps with the projection of the first electrode in the plane where the passivation layer is located.

[0028] In a third aspect, the present application further provides a method for manufacturing a solar cell. The method for manufacturing a solar cell comprises:

[0029] First, a semiconductor substrate is provided, having a light-receiving surface and a backlight surface facing each other. Next, an ultrathin dielectric layer is formed on at least one of the backlight surface and the light-receiving surface of the semiconductor substrate. Next, a passivation layer is formed on the ultrathin dielectric layer. Next, a first electrode is formed thereon. Metal crystals are formed within the passivation layer. The metal crystals include a first metal crystal, one end face of which abuts the ultrathin dielectric layer, and the other end face of which is connected to the first electrode.

[0030] Compared to the prior art, the solar cell manufacturing method provided in this application can improve carrier transfer efficiency, reduce or eliminate the loss of on-state voltage, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer. Furthermore, because one end face of the first metal crystal abuts the ultra-thin dielectric layer and the other end face of the first metal crystal is connected to the first electrode, a metal-ultra-thin dielectric-semiconductor structure is formed. Furthermore, because the first metal crystal is located within the passivation layer, the first metal crystal and the passivation layer are in full contact. Based on this, by controlling the ratio of the first metal crystals, the fill factor can be optimized, balancing the on-state voltage and fill factor. Furthermore, the action of the first metal crystal facilitates the migration of carriers to the first electrode, accelerating the carrier transfer rate and thereby shortening the time required for carriers to pass through the passivation layer. In addition, because the first metal crystal does not pass through the ultra-thin dielectric layer into the semiconductor substrate, not only is the ultra-thin dielectric layer protected from damage, but the functionality of the ultra-thin dielectric layer is also unaffected. In other words, good chemical passivation and tunneling effects of the ultra-thin dielectric layer are guaranteed. At the same time, the impact on the opening voltage can also be reduced to avoid damage to the semiconductor substrate, thereby ensuring that the function of the semiconductor substrate is not affected, and further ensuring the performance of the solar cell.

[0031] In summary, the first metal crystals abut the ultra-thin dielectric layer without destroying the structure of the ultra-thin dielectric layer, thus ensuring good chemical passivation and tunneling effect of the ultra-thin dielectric layer. The ultra-thin dielectric layer acts as a tunneling transport layer for majority carriers, transporting majority carriers in the semiconductor substrate through the ultra-thin dielectric layer. Subsequently, the first metal crystals take on the role of rapidly transporting majority carriers through the ultra-thin dielectric layer to the first electrode, ensuring a higher fill factor. The well-passivated structure's efficient majority carrier transport results in lower contact resistivity and series resistance, thereby ensuring higher battery efficiency.

[0032] In one implementation, a ratio of the number of the first metal crystals to the total number of the metal crystals is greater than or equal to 2% and less than or equal to 20%.

[0033] When the above technical solution is adopted, it is possible to avoid the influence of the tunneling-polycrystalline carrier tunneling effect caused by an excessive number of first metal crystals.

[0034] In one implementation, the width of the first metal crystals gradually decreases along a direction from the first electrode to the passivation layer.

[0035] When using the above technical solution, the width of the first metal crystal gradually decreases along the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal recombination at the metal-ultra-thin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases along the direction from the first electrode to the passivation layer, increasing the contact area between the first metal crystal and the first electrode, which helps improve the transmission efficiency of majority carriers transported by the first metal crystal to the first electrode.

[0036] In one implementation, the metal crystal further includes a second metal crystal. The second metal crystal is connected to the first electrode and spaced apart from the first metal crystal. The thickness of the second metal crystal is less than that of the passivation layer, and the thickness direction of the second metal crystal and the thickness direction of the passivation layer are both aligned in a direction from the backlight surface to the light-receiving surface.

[0037] When the above technical solution is adopted, it is not only more conducive to the movement of carriers to the first electrode, but also further accelerates the carrier transmission rate, thereby further shortening the time required for the carriers to pass through the passivation layer to ensure the battery efficiency of the TOPCon battery. At the same time, it can also reduce the contact resistance between the first electrode and the passivation layer. Furthermore, since the thickness of the second metal crystal is less than that of the passivation layer, the second metal crystal can be prevented from damaging the ultra-thin dielectric layer and the semiconductor substrate, thereby ensuring the performance of the solar cell.

[0038] In one implementation, the plurality of second metal crystals are distributed at intervals, and / or the ratio of the number of the second metal crystals to the total number of the metal crystals is greater than or equal to 50% and less than or equal to 90%.

[0039] In one implementation, the metal crystal further includes a third metal crystal. The third metal crystal is spaced apart from the first electrode, the ultra-thin dielectric layer, and the second metal crystal.

[0040] In one implementation, a plurality of third metal crystals are discretely distributed within the passivation layer; and / or, along a direction from the first electrode toward the passivation layer, the spacing between the third metal crystals and the first electrode is smaller than the spacing between the third metal crystals and the ultra-thin dielectric layer; and / or, the ratio of the number of second metal crystals to the total number of metal crystals is less than or equal to 5%. and / or, the ratio of the average volume of the third metal crystals to the average volume of the second metal crystals is less than or equal to 10%.

[0041] When using the above technical solution, smaller third metal crystals tend to separate from the first electrode body. While the presence of these third metal crystals is undesirable during actual manufacturing, their presence is unavoidable. Therefore, it is necessary to control the average volume and number of the third metal crystals within the above ranges to minimize their impact on solar cell efficiency.

[0042] In one implementation, after forming the passivation layer on the ultra-thin dielectric layer, the method for manufacturing a solar cell further includes:

[0043] performing a doping diffusion process on the passivation layer to form a doped passivation layer;

[0044] performing a post-diffusion deposition process on the doped passivation layer to form a second doping source layer on the doped passivation layer;

[0045] The second doping source layer is subjected to regional processing by a laser irradiation process to form a first heavily doped region in the doped passivation layer; the remaining doped passivation layer is the first lightly doped region;

[0046] The first heavily doped region is correspondingly connected to the first electrode; and the doping concentration of the first heavily doped region is greater than the doping concentration of the first lightly doped region.

[0047] With this technical solution, since the first heavily doped region is connected to the first electrode, good ohmic contact is ensured between the first electrode and the doped passivation layer, thereby improving the fill factor. Furthermore, since the first lightly doped region does not contact the first electrode, a non-metallic contact region is formed, and the doping concentration of the first lightly doped region is relatively low. This helps reduce Auger recombination in the non-metallic contact region and parasitic absorption of ultraviolet light by the doped passivation layer.

[0048] In one implementation, the diffusion temperature in the doping diffusion process is greater than or equal to 800° C. and less than or equal to 830° C. The diffusion temperature in the post-diffusion deposition process is greater than or equal to 820° C. and less than or equal to 850° C.

[0049] In one implementation, the ultra-thin dielectric layer has a thickness greater than or equal to 1 nm and less than or equal to 2 nm. The thickness of the ultra-thin dielectric layer is aligned with the direction from the light-receiving surface to the backlight surface. Furthermore, the ultra-thin dielectric layer is made of one of silicon oxide, hafnium oxide, aluminum oxide, and silicon nitride. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0051] FIG1 is a structural schematic diagram of a solar cell according to an embodiment of the present application;

[0052] FIG2 is an enlarged schematic diagram of a portion of the structure of FIG1 in an embodiment of the present application;

[0053] FIG3 is a second structural diagram of a solar cell in an embodiment of the present application.

[0054] Reference numerals:

[0055] 1-semiconductor substrate, S1-light-receiving surface, S2-backlight surface,

[0056] 2-ultra-thin dielectric layer, 3-passivation layer, 30-doped passivation layer,

[0057] 4-first electrode, 5-metal crystal, 50-first metal crystal,

[0058] 51 - second metal crystal, 52 - third metal crystal, 60 - second shallowly doped region,

[0059] 61 - second heavily doped region, 62 - first lightly doped region, 63 - first heavily doped region,

[0060] 64-emitter, 70-first passivation / anti-reflection stacked structure,

[0061] 71-second passivation / anti-reflection stacked structure, 80-second aluminum oxide passivation layer,

[0062] 81-second SiNx anti-reflection passivation layer, 82-first aluminum oxide passivation layer,

[0063] 83 - first SiNx anti-reflection passivation layer, 9 - second electrode. DETAILED DESCRIPTION

[0064] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0065] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0066] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0067] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0068] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0069] In the existing TOPCon battery technology, among the many factors that affect the improvement of its battery efficiency, an important factor is the strong light parasitic absorption of the battery doped passivation layer. Specifically, because the doped passivation layer of the TOPCon battery is deposited with a thicker Poly layer, it takes a long time for the carriers to pass through the passivation layer, and the light parasitic absorption is serious. Furthermore, the phosphorus atom doping concentration of the Poly layer of the N-type TOPCon battery is about 3 to 6*E20 and is uniformly doped. The Poly layer doped with high concentrations of phosphorus atoms will produce strong free carrier absorption for light in the long wavelength band (i.e., the wavelength range of 800nm ​​to 1200nm), affecting the battery efficiency. In addition, in the TOPCon battery structure, the electrodes are generally sintered and formed using a silver-containing paste. Poor contact between the electrode and the Poly layer will reduce the fill factor.

[0070] Currently, most research aims to improve cell efficiency by reducing the thickness of the poly layer, shortening the time it takes for carriers to pass through the doped poly layer, or by reducing the poly concentration to reduce parasitic light absorption. However, experiments have shown that while thinning the poly layer can reduce the parasitic effect of ultraviolet light and increase photocurrent, it also results in significant voltage loss. Furthermore, reducing the phosphorus doping concentration in the poly layer weakens the field passivation effect and deteriorates contact performance, leading to a sharp drop in fill factor.

[0071] In order to solve the above technical problems, in a first aspect, an embodiment of the present application provides a solar cell.

[0072] 1 and 2 , the solar cell includes: a semiconductor substrate 1, an ultra-thin dielectric layer 2, a passivation layer 3, a first electrode 4, and a metal crystal 5. The semiconductor substrate 1 has a light-receiving surface S1 and a backlight surface S2 facing each other. The ultra-thin dielectric layer 2 is located on at least one of the backlight surface S2 and the light-receiving surface S1 of the semiconductor substrate 1. The passivation layer 3 is located on the ultra-thin dielectric layer 2. The first electrode 4 is located on the passivation layer 3. The metal crystal 5 is located within the passivation layer 3. The metal crystal 5 includes a first metal crystal 50, wherein one end face of the first metal crystal 50 abuts against the ultra-thin dielectric layer 2, and the other end face of the first metal crystal 50 is connected to the first electrode 4. It should be noted that although in the embodiment shown in the present application, the passivation layer 3 is only shown as being provided on the ultra-thin dielectric layer 2 at the backlight surface S2, it should be understood that the corresponding ultra-thin dielectric layer 2 and passivation layer 3 can also be provided on the light-receiving surface S1 of the semiconductor substrate 1.

[0073] The semiconductor substrate may be a silicon substrate, which is a single crystal silicon substrate in this embodiment and may be a polycrystalline silicon substrate in other embodiments.

[0074] Optionally, a passivation layer 3 may be partially provided on at least one of the backlight surface S2 and the light-receiving surface S1. For example, the passivation layer 3 may be partially provided on the backlight surface S2. Of course, the passivation layer 3 may also be partially provided on the light-receiving surface S1, or the passivation layer 3 may be partially provided on both the backlight surface S2 and the light-receiving surface S1. Optionally, the passivation layer 3 is provided on the ultra-thin dielectric layer 2.

[0075] As a possible implementation, the first electrode is made of a metal paste, for example, primarily silver paste, which is sintered. Specifically, the metal paste is first printed onto a designated location using methods such as screen printing or laser transfer, and then sintered to form an excellent contact between the electrode metal material and the passivation layer.

[0076] In the actual production process, the silver paste consists of silver metal, glass frit, and other additives and solvents. After printing the first electrode pattern, it is dried to remove some organic components, and then sintered at a temperature greater than or equal to 700°C and less than or equal to 800°C, preferably 740°C. After sintering, the majority of the silver electrode material is distributed on the surface of the passivation layer, forming the first electrode.

[0077] The material of the metal crystal can be selected according to actual conditions. For example, the material of the metal crystal can be the same as that of the first electrode, such as silver.

[0078] As a possible implementation, the solar cell can be a tunneling oxide passivation contact solar cell. The following description uses a tunneling oxide passivation contact solar cell as an example. It should be understood that the following description is for illustrative purposes only and is not intended to be limiting. Referring to Figures 1 and 2, compared to the prior art, the solar cell provided by the embodiments of the present application can improve carrier transfer efficiency, reduce or eliminate the loss of turn-on voltage, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer 3. Furthermore, because one end face of the first metal crystal 50 abuts the ultra-thin dielectric layer 2 and the other end face of the first metal crystal 50 connects to the first electrode 4, a metal-ultra-thin dielectric-semiconductor structure is formed. Furthermore, because the first metal crystal 50 is located within the passivation layer 3, the first metal crystal 50 is in full contact with the passivation layer 3. Based on this, by controlling the ratio of the first metal crystal 50, the fill factor can be optimized, balancing the turn-on voltage and fill factor. Furthermore, the first metal crystal 50 facilitates the movement of carriers to the first electrode 4, accelerating the carrier transfer rate and thereby shortening the time required for the carriers to pass through the passivation layer 3. Based on this, the carrier transfer efficiency can be improved and the light parasitic absorption can be weakened to ensure the cell efficiency of the TOPCon cell.

[0079] Furthermore, since the first metal crystals 50 do not pass through the ultra-thin dielectric layer 2 into the semiconductor substrate 1, this not only ensures that the ultra-thin dielectric layer 2 is not damaged, thereby ensuring that its functionality is not affected. This ensures good chemical passivation and tunneling effects in the ultra-thin dielectric layer. It also reduces the impact on the opening voltage, preventing damage to the semiconductor substrate 1, ensuring that its functionality is not affected, and thus ensuring the performance of the solar cell.

[0080] In summary, the first metal crystals abut the ultra-thin dielectric layer without destroying the structure of the ultra-thin dielectric layer, thus ensuring good chemical passivation and tunneling effect of the ultra-thin dielectric layer. The ultra-thin dielectric layer acts as a tunneling transport layer for majority carriers, transporting majority carriers in the semiconductor substrate through the ultra-thin dielectric layer. Subsequently, the first metal crystals take on the role of rapidly transporting majority carriers through the ultra-thin dielectric layer to the first electrode, ensuring a higher fill factor. The well-passivated structure's efficient majority carrier transport results in lower contact resistivity and series resistance, thereby ensuring higher battery efficiency.

[0081] As a possible implementation method, the structure of the passivation layer can be polycrystalline, amorphous or microcrystalline, etc. In the embodiment of the present application, the structure of the passivation layer is a polycrystalline structure, and the crystallization rate is above 98%. In addition, when the passivation layer is a polycrystalline silicon passivation layer, the thickness of the polycrystalline silicon passivation layer is greater than or equal to 45nm and less than or equal to 200nm, and the thickness direction of the polycrystalline silicon passivation layer is consistent with the direction from the backlight surface to the light receiving surface. For example, the thickness can be 45nm, 50nm, 80nm, 100nm, 120nm, 150nm or 200nm, etc.

[0082] As a possible implementation, the thickness of the ultra-thin dielectric layer 2 is greater than or equal to 1 nm and less than or equal to 2 nm. The thickness of the ultra-thin dielectric layer 2 is aligned with the direction from the light-receiving surface S1 to the backlight surface S2. For example, the thickness is 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, 1.85 nm, or 2 nm. Furthermore, the material of the ultra-thin dielectric layer 2 includes silicon oxide, hafnium oxide, aluminum oxide, or silicon nitride.

[0083] In the embodiment of the present application, the ultra-thin dielectric layer is a tunneling oxide layer.

[0084] As a possible implementation, referring to FIG2 , the ratio of the number of first metal crystals 50 to the total number of metal crystals 5 is greater than or equal to 2% and less than or equal to 20%. For example, the ratio can be 2%, 5%, 8%, 12%, 15%, 17%, 18%, or 20%. In this case, the carrier tunneling effect of the tunneling-to-polycrystalline structure can be prevented from being affected by an excessive number of first metal crystals.

[0085] Referring to Figures 1 and 2 , the first metal crystal 50 did not burn through the ultra-thin dielectric layer 2 and into the semiconductor substrate 1. This may be because the silver paste contains a considerable amount of metallic silver and an oxide glass frit component (e.g., lead oxide). After the glass frit component corrodes the passivation / anti-reflection layer, the metallic silver and the glass frit enter the passivation layer 3. Subsequently, as sintering continues, the metallic silver and its attached oxide enter the interface of the tunneling layer. Given that the ultra-thin dielectric layer 2 is only a few nanometers in size and the silicon substrate is a dense single crystal structure, the metallic silver cannot further penetrate the tunneling layer into the silicon substrate. Alternatively, the accompanying silver oxide may undergo an oxidation reaction with the interface of the silicon substrate, forming a silicon oxide layer between the silver crystal and the silicon substrate.

[0086] As a possible implementation, referring to FIG. 2 , the width of the first metal crystal 50 gradually decreases along the direction from the first electrode 4 to the passivation layer 3 .

[0087] When using the above technical solution, the width of the first metal crystals gradually decreases along the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal recombination at the metal-ultra-thin dielectric layer interface. Furthermore, the width of the first metal crystals gradually increases along the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystals and the first electrode, which helps improve the efficiency of the first metal crystals in transporting majority carriers from the light-receiving surface to the backlight surface to the first electrode.

[0088] Exemplarily, along the direction from the first electrode 4 to the passivation layer 3 , the first metal crystals 50 are approximately trapezoidal in shape.

[0089] As an optional implementation, one end face of the first metal crystal 50 abuts against the ultra-thin dielectric layer 2 , and the other end face of the first metal crystal 50 penetrates into the first electrode 4 . The specific depth can be set according to actual conditions.

[0090] As a possible implementation, referring to FIG2 , the metal crystal 5 further includes a second metal crystal 51. The second metal crystal 51 is connected to the first electrode 4 and is spaced apart from the first metal crystal 50. The thickness of the second metal crystal 51 is less than the thickness of the passivation layer 3, and the thickness direction of the second metal crystal 51 and the thickness direction of the passivation layer 3 are both consistent with the direction from the backlight surface S2 to the light-receiving surface S1. It should be understood that one end face of the second metal crystal 51 may also penetrate into the first electrode 4, wherein the size of the second metal crystal 51 penetrating into the first electrode 4 and the thickness of the second metal crystal 51 are set according to actual conditions and are not specifically limited here.

[0091] This not only facilitates carrier migration to the first electrode 4, further accelerating the carrier transmission rate, but also further shortens the time required for carriers to pass through the passivation layer 3, thereby ensuring the cell efficiency of the TOPCon cell. Simultaneously, it also reduces the contact resistance between the first electrode 4 and the passivation layer 3. Furthermore, because the thickness of the second metal crystals 51 is less than that of the passivation layer 3, the second metal crystals 51 are prevented from damaging the ultra-thin dielectric layer 2 and the semiconductor substrate 1, thereby ensuring the performance of the solar cell.

[0092] In one alternative embodiment, referring to FIG2 , the plurality of second metal crystals 51 are spaced apart. Furthermore, the ratio of the number of second metal crystals 51 to the total number of metal crystals is greater than or equal to 50% and less than or equal to 90%. For example, the ratio can be 50%, 58%, 62%, 75%, 82%, or 90%.

[0093] When the above technical solution is adopted, it is not only more conducive to the movement of carriers to the first electrode, but also further accelerates the carrier transmission rate, thereby further shortening the time required for the carriers to pass through the passivation layer to ensure the battery efficiency of the TOPCon battery. At the same time, it can also reduce the contact resistance between the first electrode and the passivation layer. Furthermore, since the thickness of the second metal crystal is less than that of the passivation layer, the second metal crystal can be prevented from damaging the ultra-thin dielectric layer and the semiconductor substrate, thereby ensuring the performance of the solar cell.

[0094] In one optional embodiment, as shown in FIG2 , the metal crystal 5 further includes a third metal crystal 52. The third metal crystal 52 is spaced apart from the first electrode 4, the ultra-thin dielectric layer 2, and the second metal crystal 51. That is, the third metal crystal 52 is neither connected to the first electrode 4 nor to the ultra-thin dielectric layer 2.

[0095] This facilitates carrier migration to the first electrode 4, further accelerating the carrier transmission rate and further shortening the time required for the carriers to pass through the passivation layer 3, thereby ensuring the cell efficiency of the TOPCon cell. Furthermore, since the third metal crystals 52 are spaced apart from the ultra-thin dielectric layer 2, the third metal crystals 52 are prevented from damaging the ultra-thin dielectric layer 2 and the semiconductor substrate 1, thereby ensuring the performance of the solar cell.

[0096] In one optional embodiment, referring to FIG. 2 , a plurality of third metal crystals 52 are discretely distributed within the passivation layer 3. Furthermore, along the direction from the first electrode 4 toward the passivation layer 3, the spacing between the third metal crystals 52 and the first electrode 4 is smaller than the spacing between the third metal crystals 52 and the ultra-thin dielectric layer 2. In the embodiment of the present application, the spacing between the third metal crystals 52 and the first electrode 4 is less than half the thickness of the passivation layer 3. Furthermore, the ratio of the number of second metal crystals 51 to the total number of metal crystals is less than or equal to 5%.

[0097] In an alternative embodiment, referring to FIG2 , since smaller metal crystals are easier to separate from the main body of the first electrode 4 but are more difficult to grow and extend deeper into the passivation layer 3, the ratio of the average volume of the third metal crystals 52 to the average volume of the second metal crystals 51 is less than or equal to 10%.

[0098] When using the above technical solution, smaller third metal crystals 52 are prone to detaching from the main body of the first electrode 4. While the presence of such third metal crystals is undesirable during actual manufacturing, their presence is unavoidable. Therefore, it is necessary to control the average volume and number of the third metal crystals within the above ranges to minimize their impact on solar cell efficiency.

[0099] In combination with the above description, the first metal crystal 50 is the largest in size compared to the second metal crystal 51 and the third metal crystal 52. Furthermore, the first metal crystal 50, the second metal crystal 51 and the third metal crystal 52 are all distributed at intervals.

[0100] As a possible implementation, referring to FIG1 , the light-receiving surface S1 of the solar cell has an emitter 64, which is obtained by having a doping type opposite to that of the semiconductor substrate 1. The emitter 64 can have a single doping region or a selective emitter structure, that is, it includes both a second shallowly doped region 60 and a second heavily doped region 61 in contact with the second electrode 9. The doping concentration of the second heavily doped region 61 is greater than the doping concentration of the second shallowly doped region 60.

[0101] As a possible implementation, a first passivation / anti-reflection stacked structure 70 is formed on the passivation layer 3 in a direction away from the semiconductor substrate, and the first electrode 4 is connected to the passivation layer 3 through the first passivation / anti-reflection stacked structure 70. Optionally, as shown in FIG1 , a second passivation / anti-reflection stacked structure 71 is further formed at the light-receiving surface S1 of the semiconductor substrate 1, and the second electrode 9 is connected to the second heavily doped region 61 through the second passivation / anti-reflection stacked structure 71.

[0102] As a possible implementation, referring to FIG3 , when the passivation layer is a doped passivation layer 30, the doped passivation layer 30 includes a first heavily doped region 63 and a first lightly doped region 62. The first heavily doped region 63 is connected to the first electrode 4. The first lightly doped region 62 is located on one side of the first heavily doped region 63, and the doping concentration of the first heavily doped region 63 is greater than the doping concentration of the first lightly doped region 62.

[0103] Because the first heavily doped region 63 is connected to the first electrode 4, good ohmic contact is ensured between the first electrode 4 and the doped passivation layer 30, thereby improving the fill factor. Furthermore, because the first lightly doped region 62 does not contact the first electrode 4, a non-metallic contact region is formed, and the doping concentration of the first lightly doped region 62 is relatively low. This helps reduce Auger recombination in the non-metallic contact region and reduces parasitic absorption of ultraviolet light by the doped passivation layer.

[0104] For example, in the actual manufacturing process, the passivation layer 3 is diffused with low concentration phosphorus (for example, the doping concentration is 1 to 3E+20) to form a doped passivation layer 30. Then, local laser doping is performed in the metallized area by a laser device to form a first heavily doped area 63. The area outside the laser doping is a non-metallized area, that is, the first shallowly doped area 62. At this time, the problem caused by the uniform doping of the Poly layer in the prior art is solved. Since the passivation layer is doped with low concentration phosphorus atoms in the embodiment of the present application, the strong free carrier absorption phenomenon of the doped passivation layer 30 in the prior art for light in the long wavelength band (that is, the wavelength range of 800nm ​​to 1200nm) is solved, thereby improving the battery efficiency. Furthermore, compared with the prior art where the field passivation effect is weakened and the contact performance is deteriorated due to only reducing the phosphorus doping concentration of the Poly layer, a first heavily doped area and a first shallowly doped area are formed in the embodiment of the present application. The high doping concentration in the first heavily doped region enhances the field passivation effect of the first heavily doped region, and provides good contact between the doped passivation layer and the first electrode, ensuring that the fill factor does not decrease. The light parasitic absorption in the first lightly doped region is weakened, resulting in a significant current gain.

[0105] In addition, compared to the prior art, in order to ensure good ohmic contact between the doped passivation layer and the first electrode, the silver paste printing line width used to form the first electrode 4 during screen printing is usually wide, resulting in high unit consumption and high cost. However, in the embodiment of the present application, by connecting the first electrode 4 to the first heavily doped region 63, good ohmic contact is ensured between the first electrode 4 and the doped passivation layer 30. Therefore, the silver paste printing line width used to form the first electrode 4 can be appropriately narrowed to reduce production costs.

[0106] Furthermore, in the embodiment of the present application, a first heavily doped region and a first lightly doped region are formed. The first heavily doped region has a high doping concentration, ensuring good contact between the doped passivation layer and the first electrode, thereby allowing for a narrower screen printing line width. The first lightly doped region has a low doping concentration, resulting in relatively weak parasitic absorption of light, which reduces current loss, thereby improving battery efficiency and reducing metal paste consumption.

[0107] In one optional embodiment, the thickness of the doped passivation layer is greater than or equal to 50 nm and less than or equal to 200 nm. For example, the thickness of the doped passivation layer can be 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, or 200 nm. Compared to the prior art, the solar cell provided by the present application can improve the carrier transfer efficiency, reduce or eliminate the loss of the opening voltage, and ensure excellent electrical contact performance between the electrode and the passivation layer without reducing the thickness of the doped passivation layer.

[0108] As a possible implementation, referring to FIG3 , the width of the first heavily doped region 63 is greater than the width of the first electrode 4. In the embodiment of the present application, the width of the first heavily doped region 63 is slightly greater than the width of the first electrode 4. This facilitates subsequent screen alignment and printing to ensure the quality of the solar cell.

[0109] When the passivation layer is a doped passivation layer 30, the semiconductor substrate 1 can be an N-type crystalline silicon substrate. A second aluminum oxide passivation layer 80 and a second SiNx anti-reflection passivation layer 81 are sequentially formed on the light-receiving surface S1 of the semiconductor substrate 1. The light-receiving surface S1 of the semiconductor substrate 1 has a selective emitter, which includes a second lightly doped region 60 and a second heavily doped region 61 in contact with the second electrode 9. The second electrode 9 is connected to the second heavily doped region 61 through the second SiNx anti-reflection passivation layer 81 and the second aluminum oxide passivation layer 80. A first aluminum oxide passivation layer 82 and a first SiNx anti-reflection passivation layer 83 are sequentially formed on the doped passivation layer 30. The first electrode 4 is connected to the first heavily doped region 63 through the first SiNx anti-reflection passivation layer 83 and the first aluminum oxide passivation layer 82.

[0110] It should be noted that the passivation / anti-reflection stack structure has the following functions: it can reduce the reflection of light on the surface of the solar cell, allowing more light to enter the interior of the solar cell and be absorbed, thereby improving the photoelectric conversion efficiency; prevent the external environment from eroding the surface of the solar cell, and extend the service life of the solar cell; it can reduce the recombination loss of photogenerated carriers inside the solar cell during the transmission process, improve the carrier collection efficiency, and thus improve the photoelectric conversion efficiency of the battery; it can also protect the surface of the solar cell to prevent surface defects from affecting the performance of the solar cell.

[0111] In a second aspect, embodiments of the present application further provide a solar cell assembly. The solar cell manufacturing method includes two or more of the aforementioned solar cells, wherein the two or more solar cells are electrically connected in series, and the solar cell assembly further includes a conductive wire for electrically connecting the two or more solar cells in series, wherein a projection of the conductive wire within the plane of the passivation layer partially overlaps a projection of the first electrode within the plane of the passivation layer.

[0112] When adopting the above technical solution, the conductive wire can be directly electrically connected to the first electrode, so that the connection point between the conductive wire and the first electrode is relatively small, reducing the welding stress; at the same time, due to the good electrical contact performance of the first electrode and the passivation layer, even if the welding contact area between the conductive wire and the first electrode is small, it can still ensure sufficient electrical connection between the conductive wire and the solar cell, thereby ensuring the battery efficiency of the TOPCon battery.

[0113] Optionally, a solder joint structure may be provided on the first electrode, and the conductive line is electrically connected to the solder joint structure by welding, wherein the width of the solder joint structure is greater than the width of the first electrode in a direction perpendicular to the extension direction of the first electrode.

[0114] In a third aspect, the present invention also provides a method for manufacturing a solar cell. The method for manufacturing a solar cell includes:

[0115] 1 to 3 , first, a semiconductor substrate 1 is provided. The semiconductor substrate 1 has a light-receiving surface S1 and a backlight surface S2 opposite to each other. The description of the semiconductor substrate is referred to the first aspect and is not specifically limited here.

[0116] Next, the semiconductor substrate 1 is subjected to a texturing process.

[0117] Exemplarily, an alkali and an additive are used to perform double-sided texturing on an N-type original silicon wafer.

[0118] Next, the semiconductor substrate 1 after texturing is subjected to boron diffusion treatment.

[0119] Exemplarily, a boron diffusion layer and a BSG (borosilicate glass) layer are formed on the light-receiving surface S1 of the semiconductor substrate 1 .

[0120] Next, the boron diffusion layer and the BSG layer are locally doped with laser.

[0121] Next, the laser doped structure is subjected to a high-temperature oxidation treatment.

[0122] After the above treatment, a second heavily doped region 61 (corresponding to the region treated with laser doping) is formed on the light-receiving surface S1 of the semiconductor substrate 1 , and the remaining boron diffusion layer is a second lightly doped region 60 .

[0123] Next, the backlight surface S2 of the semiconductor substrate 1 and the boron diffusion layer and BSG layer that extend around the side are removed, and then the backlight surface S2 of the semiconductor substrate 1 is polished using a NaOH or KOH alkaline solution.

[0124] Next, an ultra-thin dielectric layer 2 is formed on at least one of the backlight surface S2 and the light-receiving surface S1 of the semiconductor substrate 1 .

[0125] In one implementation, the thickness of the ultra-thin dielectric layer 2 is greater than or equal to 1 nm and less than or equal to 2 nm. The thickness of the ultra-thin dielectric layer 2 is aligned with the direction from the light-receiving surface S1 to the backlight surface S2. For example, the thickness of the ultra-thin dielectric layer 2 is 1 nm, 1.4 nm, 1.6 nm, 1.9 nm, or 2 nm. Furthermore, the material of the ultra-thin dielectric layer 2 includes silicon oxide, hafnium oxide, aluminum oxide, or silicon nitride.

[0126] Next, a passivation layer 3 is formed on the ultra-thin dielectric layer 2 .

[0127] As a possible implementation, after forming the passivation layer 3 on the ultra-thin dielectric layer 2, the method for manufacturing a solar cell further includes:

[0128] Performing a doping diffusion process on the passivation layer 3 to form a doped passivation layer 30;

[0129] Exemplarily, a low-pressure diffusion furnace is used to dope the passivation layer 3 with phosphorus. During the doping diffusion process, the diffusion temperature is greater than or equal to 800° C. and less than or equal to 830° C., for example, 800° C., 805° C., 810° C., 815° C., or 830° C. The push-to-junction temperature is greater than or equal to 850° C. and less than or equal to 900° C., for example, 850° C., 860° C., 880° C., 890° C., or 900° C.

[0130] Next, a post-diffusion deposition process is performed on the doped passivation layer 30 to form a second doping source layer on the doped passivation layer 30 ;

[0131] In one implementation, a PSG (phosphorosilicate glass) layer is formed on the doped passivation layer 30. The diffusion temperature during the post-diffusion deposition process is greater than or equal to 820° C. and less than or equal to 850° C., for example, 820° C., 825° C., 830° C., 840° C., or 850° C.

[0132] Next, the second doping source layer is regionally processed by laser irradiation to form a first heavily doped region 63 in the doped passivation layer 30; the remaining doped passivation layer 30 is the first lightly doped region 62;

[0133] Exemplarily, a laser is used to propel phosphorus atoms in the phosphorus-rich PSG layer into the doped passivation layer 30 , thereby forming a first heavily doped region in the doped passivation layer 30 .

[0134] The first heavily doped region 63 is correspondingly connected to the first electrode 4 ; the doping concentration of the first heavily doped region 63 is greater than the doping concentration of the first lightly doped region 62 .

[0135] When using the above technical solution, since the first heavily doped region 63 is connected to the first electrode 4, good ohmic contact is ensured between the first electrode 4 and the doped passivation layer 30, thereby improving the fill factor. Furthermore, since the first lightly doped region 62 does not contact the first electrode 4, a non-metallic contact region is formed, and the doping concentration of the first lightly doped region 62 is relatively low. Therefore, Auger recombination in the non-metallic contact region is reduced, and the parasitic absorption of ultraviolet light by the doped passivation layer is reduced.

[0136] Next, the light-receiving surface S1 of the semiconductor substrate 1 and the phosphorus diffusion layer and PSG layer formed on the side surfaces are removed, and then the doped passivation layer 30 formed on the light-receiving surface S1 and the BSG layer on the light-receiving surface S1 and the PSG layer on the backlight surface S2 are removed;

[0137] Next, a first aluminum oxide passivation layer 82 is formed on the doped passivation layer 30 ; a second aluminum oxide passivation layer 80 is formed on the light-receiving surface S1 of the semiconductor substrate 1 ;

[0138] Next, a first SiNx anti-reflection passivation layer 83 is formed on the first aluminum oxide passivation layer 82; and a second SiNx anti-reflection passivation layer 81 is formed on the second aluminum oxide passivation layer 80;

[0139] Next, the first electrode 4 and the second electrode 9 are formed.

[0140] The first electrode 4 on the backlight surface S2 is connected to the first heavily doped region 63 through the first SiNx anti-reflection passivation layer 83 and the first aluminum oxide passivation layer 82. The second electrode 9 on the light-receiving surface S1 is connected to the second heavily doped region 61 through the second SiNx anti-reflection passivation layer 81 and the second aluminum oxide passivation layer 80.

[0141] Metal crystals are formed in the passivation layer 3 , wherein the metal crystals include a first metal crystal 50 . One end surface of the first metal crystal 50 abuts against the ultra-thin dielectric layer 2 , and the other end surface of the first metal crystal 50 is connected to the first electrode 4 .

[0142] Compared to the prior art, the solar cell manufacturing method provided in the embodiments of the present application can improve carrier transfer efficiency, reduce or eliminate the loss of on-state voltage, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer 3. Furthermore, because one end face of the first metal crystal 50 abuts the ultra-thin dielectric layer 2 and the other end face of the first metal crystal 50 is connected to the first electrode 4, a metal-ultra-thin dielectric-semiconductor structure is formed. Furthermore, because the first metal crystal 50 is located within the passivation layer 3, the first metal crystal 50 is in full contact with the passivation layer 3. Based on this, by controlling the ratio of the first metal crystal 50, the fill factor can be optimized and the on-state voltage and fill factor can be balanced. Furthermore, under the action of the first metal crystal 50, the carriers are facilitated to move to the first electrode 4, accelerating the carrier transfer rate and thereby shortening the time required for the carriers to pass through the passivation layer 3. In addition, because the first metal crystal 50 does not pass through the ultra-thin dielectric layer 2 into the semiconductor substrate 1, at this time, not only can the ultra-thin dielectric layer 2 be ensured not to be damaged, but the function of the ultra-thin dielectric layer 2 can also be ensured not to be affected. That is, it ensures good chemical passivation and tunneling effect of the ultra-thin dielectric layer. At the same time, it can also reduce the impact on the opening voltage to avoid damage to the semiconductor substrate 1, thereby ensuring that the function of the semiconductor substrate 1 is not affected and further ensuring the performance of the solar cell.

[0143] In summary, the first metal crystal abuts against the ultra-thin dielectric layer without destroying the structure of the ultra-thin dielectric layer, thus ensuring good chemical passivation and tunneling effect of the ultra-thin dielectric layer. The ultra-thin dielectric layer acts as a tunneling transmission layer for majority carriers, and can transmit majority carriers in the semiconductor substrate through the ultra-thin dielectric layer. Next, the first metal crystal takes on the role of quickly transmitting majority carriers through the ultra-thin dielectric layer to the first electrode to ensure a higher fill factor. The good majority carrier transmission efficiency of the backlight passivation structure can obtain a smaller contact resistivity and series resistance, thereby ensuring a higher battery efficiency.

[0144] As a possible implementation, the ratio of the number of first metal crystals to the total number of metal crystals is greater than or equal to 2% and less than or equal to 20%. For example, the ratio can be 2%, 5%, 8%, 12%, 15%, 17%, 18%, or 20%. In this case, the excessive number of first metal crystals can be prevented from affecting the carrier tunneling effect of the tunneling-to-polycrystalline structure.

[0145] As a possible implementation, referring to FIG. 2 , the width of the first metal crystal 50 gradually decreases along the direction from the first electrode 4 to the passivation layer 3 .

[0146] When using the above technical solution, the width of the first metal crystals gradually decreases along the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal recombination at the metal-ultra-thin dielectric layer interface. Furthermore, the width of the first metal crystals gradually increases along the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystals and the first electrode, which helps improve the efficiency of the first metal crystals in transporting majority carriers from the light-receiving surface to the backlight surface to the first electrode.

[0147] Exemplarily, along the direction from the first electrode 4 to the passivation layer 3 , the first metal crystals 50 are approximately trapezoidal in shape.

[0148] In an optional manner, one end surface of the first metal crystal 50 abuts against the ultra-thin dielectric layer 2 , and the other end surface of the first metal crystal 50 penetrates into the first electrode 4 . The specific depth can be set according to actual conditions.

[0149] As a possible implementation, referring to FIG2 , the metal crystal 5 further includes a second metal crystal 51. The second metal crystal 51 is connected to the first electrode 4 and is spaced apart from the first metal crystal 50. The thickness of the second metal crystal 51 is less than the thickness of the passivation layer 3, and the thickness direction of the second metal crystal 51 and the thickness direction of the passivation layer 3 are both consistent with the direction from the backlight surface S2 to the light-receiving surface S1. It should be understood that one end face of the second metal crystal 51 may also penetrate into the first electrode 4, wherein the size of the second metal crystal 51 penetrating into the first electrode 4 and the thickness of the second metal crystal 51 are set according to actual conditions and are not specifically limited here.

[0150] This not only facilitates carrier migration to the first electrode 4, further accelerating the carrier transmission rate, but also further shortens the time required for carriers to pass through the passivation layer 3, thereby ensuring the cell efficiency of the TOPCon cell. Simultaneously, it also reduces the contact resistance between the first electrode 4 and the passivation layer 3. Furthermore, because the thickness of the second metal crystals 51 is less than that of the passivation layer 3, the second metal crystals 51 are prevented from damaging the ultra-thin dielectric layer 2 and the semiconductor substrate 1, thereby ensuring the performance of the solar cell.

[0151] In one embodiment, the plurality of second metal crystals are spaced apart. Furthermore, the ratio of the number of second metal crystals to the total number of metal crystals is greater than or equal to 50% and less than or equal to 90%. For example, the ratio may be 50%, 58%, 62%, 75%, 82%, or 90%.

[0152] When the above technical solution is adopted, it is not only more conducive to the movement of carriers to the first electrode, but also further accelerates the carrier transmission rate, thereby further shortening the time required for the carriers to pass through the passivation layer to ensure the battery efficiency of the TOPCon battery. At the same time, it can also reduce the contact resistance between the first electrode and the passivation layer. Furthermore, since the thickness of the second metal crystal is less than that of the passivation layer, the second metal crystal can be prevented from damaging the ultra-thin dielectric layer and the semiconductor substrate, thereby ensuring the performance of the solar cell.

[0153] In one optional embodiment, as shown in FIG2 , the metal crystal 5 further includes a third metal crystal 52. The third metal crystal 52 is spaced apart from the first electrode 4, the ultra-thin dielectric layer 2, and the second metal crystal 51. That is, the third metal crystal 52 is neither connected to the first electrode 4 nor to the ultra-thin dielectric layer 2.

[0154] This facilitates carrier migration to the first electrode 4, further accelerating the carrier transmission rate and further shortening the time required for the carriers to pass through the passivation layer 3, thereby ensuring the cell efficiency of the TOPCon cell. Furthermore, since the third metal crystals 52 are spaced apart from the ultra-thin dielectric layer 2, the third metal crystals 52 are prevented from damaging the ultra-thin dielectric layer 2 and the semiconductor substrate 1, thereby ensuring the performance of the solar cell.

[0155] In one optional embodiment, referring to FIG2 , a plurality of third metal crystals 52 are discretely distributed within the passivation layer 3. Furthermore, along the direction from the first electrode 4 toward the passivation layer 3, the spacing between the third metal crystals 52 and the first electrode 4 is smaller than the spacing between the third metal crystals 52 and the ultra-thin dielectric layer 2. In the embodiment of the present application, the spacing between the third metal crystals 52 and the first electrode 4 is less than half the thickness of the passivation layer 3. Furthermore, the ratio of the number of second metal crystals 51 to the total number of metal crystals is less than or equal to 5%.

[0156] In an alternative embodiment, referring to FIG2 , since smaller metal crystals are easier to separate from the main body of the first electrode 4 but are more difficult to grow and extend deeper into the passivation layer 3, the ratio of the average volume of the third metal crystals 52 to the average volume of the second metal crystals 51 is less than or equal to 10%.

[0157] When using the above technical solution, smaller third metal crystals 52 are prone to detaching from the main body of the first electrode 4. While the presence of such third metal crystals is undesirable during actual manufacturing, their presence is unavoidable. Therefore, it is necessary to control the average volume and number of the third metal crystals within the above ranges to minimize their impact on solar cell efficiency.

[0158] In combination with the above description, the first metal crystal 50 is the largest in size compared to the second metal crystal 51 and the third metal crystal 52. Furthermore, the first metal crystal 50, the second metal crystal 51 and the third metal crystal 52 are all distributed at intervals.

[0159] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0160] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A solar cell, wherein: include: A semiconductor substrate having a light-receiving surface and a backlight surface opposite to each other; An ultra-thin dielectric layer is located on at least one of the backlight surface and the light-receiving surface of the semiconductor substrate; A passivation layer, located on the ultra-thin dielectric layer; A first electrode, located on the passivation layer; Metal crystals located in the passivation layer; The metal crystal includes a first metal crystal, one end surface of the first metal crystal is in contact with the ultra-thin dielectric layer, and the other end surface of the first metal crystal is connected to the first electrode.

2. The solar cell according to claim 1, wherein: The passivation layer is partially disposed on at least one of the backlight surface and the light-receiving surface.

3. The solar cell according to claim 1, wherein: A ratio of the number of the first metal crystals to the total number of the metal crystals is greater than or equal to 2% and less than or equal to 20%.

4. The solar cell according to claim 1, wherein: Along the direction from the first electrode to the passivation layer, the width of the first metal crystal gradually decreases.

5. The solar cell according to claim 1, wherein: The metal crystal further comprises: A second metal crystal is connected to the first electrode and is spaced apart from the first metal crystal; the thickness of the second metal crystal is less than the thickness of the passivation layer, and the thickness direction of the second metal crystal and the thickness direction of the passivation layer are both consistent with the direction from the backlight surface to the light-receiving surface.

6. The solar cell according to claim 5, wherein: A plurality of the second metal crystals are distributed at intervals; and / or, A ratio of the number of the second metal crystals to the total number of the metal crystals is greater than or equal to 50% and less than or equal to 90%.

7. The solar cell according to claim 5, wherein: The metal crystal further comprises: The third metal crystal is distributed spaced apart from the first electrode, the ultra-thin dielectric layer and the second metal crystal.

8. The solar cell according to claim 7, wherein: A plurality of the third metal crystals are discretely distributed in the passivation layer; and / or, Along the direction from the first electrode to the passivation layer, the distance between the third metal crystal and the first electrode is smaller than the distance between the third metal crystal and the ultra-thin dielectric layer; and / or, The ratio of the number of the second metal crystals to the total number of the metal crystals is less than or equal to 5%; and / or, A ratio of an average volume of the third metal crystals to an average volume of the second metal crystals is less than or equal to 10%.

9. The solar cell according to any one of claims 1 to 8, wherein: When the passivation layer is a doped passivation layer, the doped passivation layer comprises: A first heavily doped region, connected to the first electrode correspondingly; The first lightly doped region is located at one side of the first heavily doped region; the doping concentration of the first heavily doped region is greater than the doping concentration of the first lightly doped region.

10. The solar cell according to claim 9, wherein: The thickness of the doped passivation layer is greater than or equal to 50 nm and less than or equal to 200 nm.

11. The solar cell according to claim 1, wherein: The thickness of the ultra-thin dielectric layer is greater than or equal to 1 nm and less than or equal to 2 nm; the thickness direction of the ultra-thin dielectric layer is consistent with the direction from the light-receiving surface to the backlight surface; and / or, The material of the ultra-thin dielectric layer includes one of silicon oxide, hafnium oxide, aluminum oxide and silicon nitride.

12. A solar cell assembly comprising two or more solar cells according to any one of claims 1 to 11, wherein: Two or more of the solar cells are electrically connected in series, and the solar cell assembly also includes a conductive wire, which is used to electrically connect the two or more solar cells in series, and the projection of the conductive wire in the plane where the passivation layer is located partially overlaps with the projection of the first electrode in the plane where the passivation layer is located.

13. A method for manufacturing a solar cell, wherein: include: Providing a semiconductor substrate; The semiconductor substrate has a light-receiving surface and a light-receiving surface opposite to each other; forming an ultra-thin dielectric layer on at least one of the backlight surface and the light-receiving surface of the semiconductor substrate; forming a passivation layer on the ultra-thin dielectric layer; A first electrode is formed on the passivation layer; metal crystals are formed in the passivation layer; The metal crystal includes a first metal crystal, one end face of the first metal crystal is in contact with the ultra-thin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

14. The method for manufacturing a solar cell according to claim 13, wherein: A ratio of the number of the first metal crystals to the total number of the metal crystals is greater than or equal to 2% and less than or equal to 20%.

15. The method for manufacturing a solar cell according to claim 14, wherein: Along the direction from the first electrode to the passivation layer, the width of the first metal crystal gradually decreases.

16. The method for manufacturing a solar cell according to claim 13, wherein: After forming a passivation layer on the ultra-thin dielectric layer, the method for manufacturing a solar cell further includes: Performing a doping diffusion process on the passivation layer to form a doped passivation layer; Performing a post-diffusion deposition process on the doped passivation layer to form a second doping source layer on the doped passivation layer; The second doping source layer is subjected to regional processing by laser irradiation process to form a first heavily doped region in the doped passivation layer; the remaining doped passivation layer is a first lightly doped region; The first heavily doped region is connected to the first electrode correspondingly; and the doping concentration of the first heavily doped region is greater than the doping concentration of the first lightly doped region.

17. The method for manufacturing a solar cell according to claim 16, wherein: The diffusion temperature in the doping diffusion process is greater than or equal to 800° C. and less than or equal to 830° C.; The diffusion temperature in the post-diffusion deposition process is greater than or equal to 820° C. and less than or equal to 850° C.

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