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

Abstract

This application discloses a solar cell, a solar cell module, and a method for manufacturing a solar cell that ensure the battery efficiency of a TOPCon battery by guaranteeing good ohmic contact between a first electrode and a passivation layer, improving carrier transport efficiency, and reducing parasitic light absorption. The solar cell includes a semiconductor substrate, an ultrathin dielectric layer, a passivation layer, a first electrode, and a metal crystal. The semiconductor substrate has opposing light-receiving and non-light-receiving surfaces, the ultrathin dielectric layer is located on at least one of the non-light-receiving and light-receiving surfaces 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 within the passivation layer. The metal crystal includes a first metal crystal, one end face of the first metal crystal abuts the ultrathin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a piezoelectric transformer, and particularly to a method for manufacturing a solar cell, a solar cell module, and a solar cell.

[0002] (Cross-reference to related applications) This application claims the priority of a Chinese application with application number 2023113557296 filed on October 18, 2023, and incorporates its content herein by reference.

Background Art

[0003] A solar cell is a device that utilizes solar energy and directly converts light energy into electrical energy by means of the photovoltaic effect or the photochemical effect. The above solar cell includes a tunnel oxide passivated contact solar cell (abbreviated as TOPCon).

[0004] In the doped passivation layer of a TOPCon cell, a thick polymer layer is deposited, which results in a long time required for carriers to pass through the passivation layer, a large amount of optical parasitic absorption, and affects the cell efficiency of the TOPCon cell.

Summary of the Invention

[0005] An object of this application is to provide a solar cell, a solar cell module, and a method for manufacturing a solar cell to improve carrier transport efficiency and reduce optical parasitic absorption in order to ensure the cell efficiency of a TOPCon cell.

[0006] To achieve the above objective, the present application provides, in first aspect, a solar cell. The solar cell includes a semiconductor substrate, an ultrathin dielectric layer, a passivation layer (also called a doped semiconductor layer in the art), a first electrode, and a metal crystal. The semiconductor substrate has opposing light-receiving and non-light-receiving surfaces, the ultrathin dielectric layer is located on at least one of the non-light-receiving and light-receiving surfaces 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 within the passivation layer. The metal crystal includes a first metal crystal, one end face of the first metal crystal abuts the ultrathin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

[0007] Compared to conventional technology, the solar cell provided in this application can improve carrier transport efficiency, reduce or eliminate open-circuit voltage loss, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer. Furthermore, since 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, a metal-ultrathin dielectric-semiconductor structure is formed. Also, since the first metal crystal is located within the passivation layer, it can make sufficient contact with the passivation layer. Based on this, by controlling the ratio of the first metal crystal, the curve factor can be optimized and the open-circuit voltage and curve factor can be balanced. In addition, the first metal crystal contributes to the movement of carriers to the first electrode, increasing the carrier transport rate and shortening the time required for carriers to pass through the passivation layer. Furthermore, since the first metal crystal does not pass through the ultrathin dielectric layer and penetrate the semiconductor substrate, it is ensured that the ultrathin dielectric layer is not damaged and that its function is not affected. In other words, it ensures good chemical passivation and tunneling effects in the ultrathin dielectric layer. In addition, it reduces the impact on the open-circuit voltage and avoids damage to the semiconductor substrate, thereby ensuring that the function of the semiconductor substrate is not affected and the performance of the solar cell is maintained.

[0008] In summary, the first metal crystal contacts the ultrathin dielectric layer, and since the structure of the ultrathin dielectric layer is not destroyed, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. The ultrathin dielectric layer acts as a tunnel transport layer for majority carriers, transporting majority carriers in the semiconductor substrate and allowing them to pass through the ultrathin dielectric layer. The first metal crystal then rapidly transports the majority carriers that have passed through the ultrathin dielectric layer to the first electrode, thereby ensuring a higher curve factor. Due to the good majority carrier transport efficiency of the passivation structure, contact resistivity and series resistance can be reduced, thus ensuring higher battery efficiency.

[0009] In one embodiment, a passivation layer is locally provided on at least one of the non-light-receiving surface and the light-receiving surface.

[0010] In one embodiment, the ratio of the number of first metal crystals to the total number of metal crystals is 2% or more and 20% or less.

[0011] By employing the above technical solution, it is possible to avoid the influence on the carrier tunneling effect of the tunnel-polycrystalline structure due to an excessive number of first metal crystals.

[0012] In one embodiment, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer.

[0013] When the above technical solution is adopted, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal composite at the metal-ultrathin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases in the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystal and the first electrode, which contributes to improving the transport efficiency of majority carriers by the first metal crystal to the first electrode.

[0014] In one embodiment, the metal crystal further comprises a second metal crystal. The second metal crystal is connected to the first electrode and is distributed at a distance from the first metal crystal. The thickness of the second metal crystal is smaller than the thickness of the passivation layer, and the thickness direction of both the second metal crystal and the passivation layer coincides with the direction from the non-photosensitive surface to the photosensitive surface.

[0015] By employing the above technical solution, the movement of carriers to the first electrode contributes to a higher carrier transport rate, and the time required for carriers to pass through the passivation layer is further reduced, thereby ensuring the battery efficiency of the TOPCon battery. In addition, the contact resistance between the first electrode and the passivation layer can be reduced. Furthermore, since the thickness of the second metal crystal is smaller than the thickness of the passivation layer, damage to the ultrathin dielectric layer and semiconductor substrate by the second metal crystal can be avoided, thus ensuring the performance of the solar cell.

[0016] In one embodiment, multiple second metal crystals are distributed at intervals, and / or the ratio of the number of second metal crystals to the total number of metal crystals is 50% or more and 90% or less.

[0017] In one embodiment, the metal crystal further comprises a third metal crystal. The third metal crystal is distributed at intervals from the first electrode, the ultrathin dielectric layer, and the second metal crystal.

[0018] In one embodiment, a plurality of third metal crystals are discretely distributed within the passivation layer, and / or the pitch between the third metal crystals and the first electrode in the direction from the passivation layer to the first electrode is smaller than the pitch between the third metal crystals and the ultrathin dielectric layer, and / or the ratio of the number of second metal crystals to the total number of metal crystals is 5% or less, and / or the ratio of the average volume of the third metal crystals to the average volume of the second metal crystals is 10% or less.

[0019] When the above technical solution is adopted, the small third metal crystals tend to detach from the first electrode body, and although these third metal crystals are undesirable in the actual manufacturing process, they are unavoidable during manufacturing. Therefore, in order to reduce the impact of the third metal crystals on solar cell efficiency, it is necessary to control the average volume and number of the third metal crystals within the above range.

[0020] In one embodiment, if the passivation layer is a doped passivation layer, the doped passivation layer includes a first high-concentration doped region and a first low-concentration doped region. The first high-concentration doped region is connected to a first electrode. The first low-concentration doped region is located on one side of the first high-concentration doped region, and the doping concentration of the first high-concentration doped region is higher than that of the first low-concentration doped region.

[0021] When the above technical solution is adopted, the first high-concentration doped region is connected to the first electrode, thereby ensuring good ohmic contact between the first electrode and the doped passivation layer and increasing the curve factor. Furthermore, since the first low-concentration doped region is not in contact with the first electrode, a non-metallic contact region is formed, and the doping concentration of the first low-concentration doped region is low. Therefore, this contributes to a reduction in Auger recombination in the non-metallic contact region and a reduction in parasitic absorption of ultraviolet light by the doped passivation layer. In addition, in the conventional technology, in order to ensure good ohmic contact between the doped passivation layer and the first electrode, the silver paste printing line for forming the first electrode is usually wide during screen printing, resulting in high unit consumption and high cost. However, in contrast, in this application, the first electrode is connected to the first high-concentration doped region, thereby ensuring good ohmic contact between the first electrode and the doped passivation layer. Therefore, the width of the silver paste printing line for forming the first electrode can be appropriately narrowed, thereby reducing manufacturing costs.

[0022] In one embodiment, the thickness of the doped passivation layer is 50 nm to 200 nm.

[0023] When the above technical solution is adopted, compared to the prior art, the embodiment of this application can improve carrier transport efficiency, reduce or eliminate open-circuit voltage loss, and ensure excellent electrical contact performance between the electrode and the passivation layer without reducing the thickness of the doped passivation layer.

[0024] In one embodiment, the thickness of the ultrathin dielectric layer is 1 nm or more and 2 nm or less. The thickness direction of the ultrathin dielectric layer coincides with the direction from the light-receiving surface to the non-light-receiving surface. And / or, the material of the ultrathin dielectric layer includes one of silicon oxide, hafnium oxide, aluminum oxide, and silicon nitride.

[0025] In a second aspect, the present application further provides a solar cell module comprising two or more solar cells electrically coupled in series with respect to each other, further comprising conductive wires for electrically coupling the two or more solar cells in series, wherein the projection of the conductive wires in the plane in which the passivation layer is located partially overlaps with the projection of a first electrode in the plane in which the passivation layer is located.

[0026] In a third aspect, this application further provides a method for manufacturing a solar cell, which includes the following steps. First, a semiconductor substrate having opposing light-receiving and non-light-receiving surfaces is provided. Next, an ultrathin dielectric layer is formed on at least one of the non-light-receiving and light-receiving surfaces of the semiconductor substrate. Next, a passivation layer is formed on the ultrathin dielectric layer. Next, a first electrode is formed on the passivation layer such that a metal crystal is formed within the passivation layer. The metal crystal includes 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.

[0027] Compared with the prior art, in the method for manufacturing a solar cell provided in the present application, without thinning the passivation layer, the carrier transport efficiency can be improved, the loss of the open-circuit voltage can be reduced or eliminated, and excellent electrical contact performance between the electrode and the passivation layer can be ensured. Further, since 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, a metal-ultrathin dielectric-semiconductor structure is formed. Also, since the first metal crystal is located within the passivation layer, it can be sufficiently contacted with the passivation layer. Based on this, by controlling the ratio of the first metal crystal, the fill factor can be optimized and the balance between the open-circuit voltage and the fill factor can be achieved. Further, the first metal crystal contributes to the movement of carriers to the first electrode, the transport rate of carriers is increased, and the time required for carriers to pass through the passivation layer is shortened. Also, since the first metal crystal does not enter the semiconductor substrate through the ultrathin dielectric layer, in this case, it can be ensured that the ultrathin dielectric layer is not damaged and its function is not affected. That is, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. In addition, by reducing the influence on the open-circuit voltage and avoiding the destruction of the semiconductor substrate, it can be ensured that the function of the semiconductor substrate is not affected and the performance of the solar cell can be ensured.

[0028] Summarizing the above, the first metal crystal abuts against the ultrathin dielectric layer, and since the structure of the ultrathin dielectric layer is not damaged, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. The ultrathin dielectric layer can transport majority carriers in the semiconductor substrate and pass through the ultrathin dielectric layer as a tunneling transport layer for majority carriers. And the first metal crystal plays a role of quickly transporting the majority carriers that have passed through the ultrathin dielectric layer to the first electrode, so that a higher fill factor can be ensured. Due to the good majority carrier transport efficiency of the passivation structure, the contact resistivity and the series resistance can be reduced, so that a higher battery efficiency can be ensured.

[0029] In one embodiment, the ratio of the number of the first metal crystals to the total number of metal crystals is 2% or more and 20% or less.

[0030] When adopting the above technical solution, it is possible to avoid the influence on the carrier tunneling effect of the tunnel-polycrystal due to too many first metal crystals.

[0031] In one embodiment, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer.

[0032] When adopting the above technical solution, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer, reducing the corrosion to the passivation layer and the semiconductor substrate, and reducing the metal composite at the metal-ultrathin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases in the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystal and the first electrode, and contributing to the improvement of the transport efficiency of majority carriers by the first metal crystal to the first electrode.

[0033] In one embodiment, the metal crystal further includes a second metal crystal. The second metal crystal is connected to the first electrode and is distributed at an interval from the first metal crystal. The thickness of the second metal crystal is smaller than the thickness of the passivation layer, and the thickness direction of the second metal crystal and the thickness direction of the passivation layer both coincide with the direction from the non-light-receiving surface to the light-receiving surface.

[0034] When adopting the above technical solution, it contributes to the movement of carriers to the first electrode, further increasing the transport rate of carriers, shortening the time required for carriers to pass through the passivation layer, and ensuring the battery efficiency of the TOPCon battery. In addition, the contact resistance between the first electrode and the passivation layer can also be reduced. Furthermore, since the thickness of the second metal crystal is smaller than the thickness of the passivation layer, damage to the ultrathin dielectric layer and the semiconductor substrate caused by the second metal crystal can be avoided, and the performance of the solar cell can be ensured.

[0035] In one embodiment, multiple second metal crystals are distributed at intervals, and / or the ratio of the number of second metal crystals to the total number of metal crystals is 50% or more and 90% or less.

[0036] In one embodiment, the metal crystal further comprises a third metal crystal. The third metal crystal is distributed at intervals from the first electrode, the ultrathin dielectric layer, and the second metal crystal.

[0037] In one embodiment, a plurality of third metal crystals are discretely distributed within the passivation layer, and / or the pitch between the third metal crystals and the first electrode in the direction from the first electrode to the passivation layer is smaller than the pitch between the third metal crystals and the ultrathin dielectric layer, and / or the ratio of the number of second metal crystals to the total number of metal crystals is 5% or less, and / or the ratio of the average volume of the third metal crystals to the average volume of the second metal crystals is 10% or less.

[0038] When the above technical solution is adopted, the small third metal crystals tend to detach from the first electrode body, and although these third metal crystals are undesirable in the actual manufacturing process, they are unavoidable during manufacturing. Therefore, in order to reduce the impact of the third metal crystals on solar cell efficiency, it is necessary to control the average volume and number of the third metal crystals within the above range.

[0039] In one embodiment, after forming a passivation layer on an ultrathin dielectric layer, the method for manufacturing a solar cell is as follows: The steps include forming a doped passivation layer by performing a dope diffusion treatment on the passivation layer, The steps include forming a second doping source layer on the doped passivation layer by performing a post-diffusion deposition treatment on the doped passivation layer, The process further includes the step of locally treating the second doping source layer with a laser irradiation process to form a first high-concentration doped region within the dope passivation layer, and making the remaining dope passivation layer a first low-concentration doped region. The first high-concentration doped region is connected in correspondence with the first electrode, and the doping concentration of the first high-concentration doped region is higher than that of the first low-concentration doped region.

[0040] When the above technical solution is adopted, the first high-concentration doped region is connected to the first electrode, thus ensuring good ohmic contact between the first electrode and the doped passivation layer and increasing the curve factor. Furthermore, since the first low-concentration doped region is not in contact with the first electrode, a non-metallic contact region is formed, and the doping concentration of the first low-concentration doped region is low. Therefore, this contributes to a reduction in Auger recombination in the non-metallic contact region and a reduction in parasitic absorption of ultraviolet light by the doped passivation layer.

[0041] In one embodiment, the diffusion temperature in the doping diffusion treatment is 800°C to 830°C. In the post-diffusion deposition treatment, the diffusion temperature is 820°C to 850°C.

[0042] In one embodiment, the thickness of the ultrathin dielectric layer is 1 nm or more and 2 nm or less. The thickness direction of the ultrathin dielectric layer coincides with the direction from the light-receiving surface to the non-light-receiving surface. And / or the material of the ultrathin dielectric layer includes one of silicon oxide, hafnium oxide, aluminum oxide, and silicon nitride. [Brief explanation of the drawing]

[0043] The accompanying drawings described herein are provided for further understanding of this application and constitute part of this application. The schematic embodiments and descriptions herein are for illustrative purposes only and do not constitute an unreasonable limitation of this application. [Figure 1] This is the first schematic diagram of the structure of a solar cell in an embodiment of this application. [Figure 2] This is an enlarged schematic diagram of a part of the structure shown in Figure 1 in the embodiment of this application. [Figure 3] This is the second schematic diagram of the structure of a solar cell in the embodiment of this application. [Modes for carrying out the invention]

[0044] To further clarify the technical problem, technical solution, and beneficial effects that this application aims to solve, the application will be described in more detail below with reference to the drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit this application.

[0045] It should be explained that when an element is described as being "fixed" or "attached" to another element, it may be directly located on top of the other element or indirectly located on top of that other element. When an element is described as being "connected" to another element, it may be directly connected to that other element or indirectly connected to that other element.

[0046] Furthermore, the terms "first" and "second" are merely descriptive and should not be understood as indicating or suggesting relative importance, or implicitly specifying the number of technical features described. Thus, features designated as "first" and "second" may explicitly or implicitly include one or more such features. In the description of this application, "multiple" means two or more unless specifically and clearly defined. "How many" means one or more unless specifically and clearly defined.

[0047] In the description of this application, it should be understood that the directions or positional relationships indicated by terms such as "up," "down," "front," "back," "left," and "right" are directions or positional relationships based on the drawings and are merely for the purpose of facilitating and simplifying the description of this application. They do not indicate or suggest that the shown devices or elements have a specific direction, or that they must be configured and operated in a specific direction, and therefore should not be understood as limiting this application.

[0048] In the description of this application, unless otherwise explicitly stated or limited, the terms “attachment,” “joining,” and “connection” should be understood broadly, for example, whether they are fixed connections, detachable connections, or integral connections. They may also be mechanical or electrical connections. They may be direct connections, indirect connections via intermediate members, internal communication between two elements, or interactions between two elements. Those skilled in the art will understand the specific meaning of these terms in this application depending on the specific circumstances.

[0049] In conventional TOPCon battery technology, strong photoparasitic absorption in the battery-doped passivation layer is one of the many factors that affect the improvement of battery efficiency. Specifically, the doped passivation layer of TOPCon batteries has a thick polymer layer deposited on it, which increases the time required for carriers to pass through the passivation layer, resulting in a large amount of photoparasitic absorption. Furthermore, the phosphorus atom doping concentration of the polymer layer in N-type TOPCon batteries is about 3-6*E20, and a uniformly doped polymer layer with a high concentration of phosphorus atoms exhibits a strong free carrier absorption phenomenon for light in the long wavelength range (i.e., the wavelength range of 800nm ​​to 1200nm), affecting battery efficiency. In addition, in the TOPCon battery structure, electrodes are generally formed by sintering using silver-containing paste, and poor contact between the electrodes and the polymer layer reduces the curve factor.

[0050] Currently, much research focuses on improving battery efficiency by reducing the thickness of the polymer layer to shorten the time required for carriers to pass through the doped polymer layer, or by doping the polymer at low concentrations to weaken photoparasitic absorption. However, while reducing the thickness of the polymer layer can reduce the ultraviolet photoparasitic effect and increase the photocurrent, experiments have shown that it significantly increases open-circuit voltage loss. Furthermore, a decrease in the phosphorus doping concentration in the polymer leads to a decrease in the electric field passivation effect and a deterioration in contact performance, resulting in a sharp decrease in the curve factor.

[0051] In order to solve the above technical problems, in the first aspect, embodiments of this application provide a solar cell.

[0052] Referring to Figures 1 and 2, the solar cell includes a semiconductor substrate 1, an ultrathin dielectric layer 2, a passivation layer 3, a first electrode 4, and a metal crystal 5. The semiconductor substrate 1 has opposing light-receiving surfaces S1 and non-light-receiving surfaces S2, the ultrathin dielectric layer 2 is located on at least one of the non-light-receiving surface S2 and light-receiving surface S1 of the semiconductor substrate 1, the passivation layer 3 is located on the ultrathin dielectric layer 2, the first electrode 4 is located on the passivation layer 3, and the metal crystal 5 is located within the passivation layer 3. The metal crystal 5 includes a first metal crystal 50, one end face of the first metal crystal 50 is in contact with the ultrathin dielectric layer 2, and the other end face of the first metal crystal 50 is connected to the first electrode 4. In the embodiments described in this application, the passivation layer 3 is shown only as being provided on the ultrathin dielectric layer 2 of the non-light-receiving surface S2. However, of course, an ultrathin dielectric layer 2 and a passivation layer 3 corresponding to the light-receiving surface S1 of the semiconductor substrate 1 may also be provided.

[0053] The semiconductor substrate may be a silicon substrate; in this embodiment, it is a single-crystal silicon substrate, but in other embodiments, it may be a polycrystalline silicon substrate.

[0054] Selectively, the passivation layer 3 may be locally provided on at least one of the non-light-receiving surface S2 and the light-receiving surface S1. For example, the passivation layer 3 may be locally provided on the non-light-receiving surface S2. Naturally, the passivation layer 3 may be locally provided on the light-receiving surface S1, or it may be locally provided on both the non-light-receiving surface S2 and the light-receiving surface S1. Selectively, the passivation layer 3 is provided on an ultrathin dielectric layer 2.

[0055] In possible embodiments, the first electrode is manufactured from a metal paste, for example, by sintering primarily using silver paste. Specifically, the metal paste is first printed to a specific position by means of screen printing, laser transfer, etc., and then sintering is performed to form good contact between the electrode metal material and the passivation layer.

[0056] In the actual manufacturing process, the silver paste contains silver metal components, glass frit, and other additives and solvents. After printing the first electrode pattern, some of the organic components are removed by baking, and then sintering is performed at a sintering temperature of 700°C to 800°C, preferably 740°C. After sintering, most of the silver electrode material is distributed on the surface of the passivation layer to form the first electrode.

[0057] The material of the metal crystal may be selected according to actual requirements. For example, the material of the metal crystal may be the same as that of the first electrode, for example, silver.

[0058] In possible embodiments, the solar cell may be a tunnel oxide passivation contact solar cell. The following description will use a tunnel oxide passivation contact solar cell as an example, but it should be understood that the following description is for illustrative purposes only and not a specific limitation. Referring to Figures 1 and 2, compared to the prior art, the solar cell provided in the embodiment of this application can improve carrier transport efficiency, reduce or eliminate open-circuit voltage loss, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer 3. Furthermore, since one end face of the first metal crystal 50 abuts against the ultrathin dielectric layer 2 and the other end face of the first metal crystal 50 is connected to the first electrode 4, a metal-ultrathin dielectric-semiconductor structure is formed. Also, since the first metal crystal 50 is located within the passivation layer 3, the first metal crystal 50 can make sufficient contact with the passivation layer 3. Based on this, by controlling the ratio of the first metal crystal 50, the curve factor can be optimized and the open-circuit voltage and curve factor can be balanced. Furthermore, the first metal crystal 50 contributes to the movement of carriers to the first electrode 4, increasing the carrier transport rate and shortening the time required for carriers to pass through the passivation layer. Based on this, carrier transport efficiency can be improved, photoparasitic absorption can be reduced, and the battery efficiency of the TOPCon battery can be ensured.

[0059] Furthermore, since the first metal crystal 50 does not penetrate the semiconductor substrate 1 through the ultrathin dielectric layer 2, in this case, it is ensured that the ultrathin dielectric layer 2 is not destroyed and that its function is not affected. That is, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. In addition, the influence on the open-circuit voltage is also reduced, and by avoiding the destruction of the semiconductor substrate 1, it is ensured that the function of the semiconductor substrate 1 is not affected and the performance of the solar cell is ensured.

[0060] In summary, the first metal crystal contacts the ultrathin dielectric layer, and since the structure of the ultrathin dielectric layer is not destroyed, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. The ultrathin dielectric layer acts as a tunnel transport layer for majority carriers, transporting majority carriers in the semiconductor substrate and allowing them to pass through the ultrathin dielectric layer. The first metal crystal then rapidly transports the majority carriers that have passed through the ultrathin dielectric layer to the first electrode, thereby ensuring a higher curve factor. Due to the good majority carrier transport efficiency of the passivation structure, contact resistivity and series resistance can be reduced, thus ensuring higher battery efficiency.

[0061] In possible embodiments, the structure of the passivation layer may be polycrystalline, amorphous, or microcrystalline. In the embodiments of this application, the structure of the passivation layer is polycrystalline with a crystallinity of 98% or more. Furthermore, when the passivation layer is a polycrystalline silicon passivation layer, the thickness of the polycrystalline silicon passivation layer is 45 nm to 200 nm, and the thickness direction of the polycrystalline silicon passivation layer coincides with the direction from the non-photosensitive surface to the photosensitive surface. For example, the thickness may be 45 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, or 200 nm.

[0062] In possible embodiments, the thickness of the ultrathin dielectric layer 2 is 1 nm or more and 2 nm or less. The thickness direction of the ultrathin dielectric layer 2 coincides with the direction from the light-receiving surface S1 to the non-light-receiving surface S2. For example, it may be 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, 1.85 nm, or 2 nm. And / or, the material of the ultrathin dielectric layer 2 includes one of silicon oxide, hafnium oxide, aluminum oxide, or silicon nitride.

[0063] In the embodiments of this application, the ultrathin dielectric layer is a tunnel oxide layer.

[0064] As a possible embodiment, referring to Figure 2, the ratio of the number of first metal crystals 50 to the total number of metal crystals 5 is 2% or more and 20% or less, for example, 2%, 5%, 8%, 12%, 15%, 17%, 18%, or 20%. In this case, the effect on the carrier tunneling effect of the tunnel-polycrystalline material due to an excessive number of first metal crystals can be avoided.

[0065] Referring to Figures 1 and 2, the following reasons can be considered for why the first metal crystal 50 does not burn through the ultrathin dielectric layer 2 and penetrate into the semiconductor substrate 1. The silver paste contains a large amount of metallic silver and oxide glass frit components (e.g., lead oxide), and when the glass frit components corrode the passivation / anti-reflective layer, the metallic silver and glass frit penetrate into the passivation layer 3. Subsequently, as sintering progresses, the metallic silver and the oxides attached to it penetrate into the interface of the tunnel layer. However, because the thickness of the ultrathin dielectric layer 2 is only a few nanometers and the silicon substrate has a dense single-crystal structure, the metallic silver cannot pass further through the tunnel layer and penetrate into the silicon substrate. Alternatively, it is possible that the oxides associated with the silver undergo an oxidation reaction with the interface of the silicon substrate, forming a silicon oxide layer between the silver crystal and the silicon substrate.

[0066] As a possible embodiment, referring to Figure 2, the width of the first metal crystal 50 gradually decreases in the direction from the first electrode 4 to the passivation layer 3.

[0067] When the above technical solution is adopted, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal composites at the metal-ultrathin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases in the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystal and the first electrode, which contributes to improving the transport efficiency of majority carriers transported to the first electrode by the first metal crystal along the light-receiving surface to the non-light-receiving surface.

[0068] For example, in the direction from the first electrode 4 to the passivation layer 3, the first metal crystal 50 is approximately trapezoidal.

[0069] In a selective embodiment, one end face of the first metal crystal 50 abuts against the ultrathin dielectric layer 2, and the other end face of the first metal crystal 50 penetrates into the first electrode 4, with the specific penetration depth being set according to actual requirements.

[0070] As a possible embodiment, referring to Figure 2, 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 distributed at a distance 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 both the second metal crystal 51 and the passivation layer 3 coincides with the direction from the non-photosensitive surface S2 to the photosensitive surface S1. One end face of the second metal crystal 51 may penetrate into the first electrode 4. The penetration depth of the second metal crystal 51 into the first electrode 4 and the thickness of the second metal crystal 51 are set according to actual requirements and are not specifically limited here.

[0071] In this case, the movement of carriers to the first electrode 4 contributes to a higher carrier transport rate, reducing the time required for carriers to pass through the passivation layer 3 and ensuring the battery efficiency of the TOPCon battery. In addition, it is also possible to reduce the contact resistance between the first electrode 4 and the passivation layer 3. Furthermore, since the thickness of the second metal crystal 51 is smaller than the thickness of the passivation layer 3, damage to the ultrathin dielectric layer 2 and semiconductor substrate 1 by the second metal crystal 51 can be avoided, ensuring the performance of the solar cell.

[0072] In a selective embodiment, referring to Figure 2, the multiple second metal crystals 51 are distributed at intervals. And / or, the ratio of the number of second metal crystals 51 to the total number of metal crystals is 50% or more and 90% or less. For example, the ratio may be 50%, 58%, 62%, 75%, 82%, or 90%.

[0073] By employing the above technical solution, the movement of carriers to the first electrode contributes to a higher carrier transport rate, and the time required for carriers to pass through the passivation layer is further reduced, thereby ensuring the battery efficiency of the TOPCon battery. In addition, the contact resistance between the first electrode and the passivation layer can be reduced. Furthermore, since the thickness of the second metal crystal is smaller than the thickness of the passivation layer, damage to the ultrathin dielectric layer and semiconductor substrate by the second metal crystal can be avoided, thus ensuring the performance of the solar cell.

[0074] In a selective embodiment, referring to Figure 2, the metal crystal 5 further includes a third metal crystal 52. The third metal crystal 52 is distributed at intervals from the first electrode 4, the ultrathin dielectric layer 2, and the second metal crystal 51. That is, the third metal crystal 52 is not connected to the first electrode 4, nor to the ultrathin dielectric layer 2.

[0075] In this case, the movement of carriers to the first electrode 4 contributes to a higher carrier transport rate, shortening the time required for carriers to pass through the passivation layer 3 and ensuring the battery efficiency of the TOPCon battery. Furthermore, since the third metal crystal 52 is distributed at a distance from the ultrathin dielectric layer 2, damage to the ultrathin dielectric layer 2 and the semiconductor substrate 1 by the third metal crystal 52 is avoided, ensuring the performance of the solar cell.

[0076] In a selective embodiment, referring to Figure 2, the multiple third metal crystals 52 are discretely distributed within the passivation layer 3. And / or, in the direction from the first electrode 4 to the passivation layer 3, the pitch between the third metal crystals 52 and the first electrode 4 is smaller than the pitch between the third metal crystals 52 and the ultrathin dielectric layer 2. In the embodiments of this application, the pitch between the third metal crystals 52 and the first electrode 4 is less than half the thickness of the passivation layer 3. And / or, the ratio of the number of second metal crystals 51 to the total number of metal crystals is 5% or less.

[0077] In a selective embodiment, as shown in Figure 2, smaller metal crystals tend to detach easily from the first electrode 4 body, but they grow deep into the passivation layer 3 and are difficult to stretch. Therefore, the ratio of the average volume of the third metal crystal 52 to the average volume of the second metal crystal 51 is 10% or less.

[0078] When the above technical solution is adopted, the small third metal crystal 52 is easily detached from the first electrode 4 body, and although the third metal crystal is undesirable in the actual manufacturing process, it is unavoidable during manufacturing. Therefore, in order to reduce the impact of the third metal crystal on the solar cell efficiency, it is necessary to control the average volume and number of the third metal crystal within the above range.

[0079] As explained above, 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.

[0080] Referring to Figure 1, a possible embodiment is shown in which the solar cell has an emitter 64 on the light-receiving surface S1 obtained by a doping type opposite to that of the semiconductor substrate 1. The emitter 64 may have a single doped region or it may have a selective emitter structure, i.e., it may simultaneously include a second low-concentration doped region 60 and a second high-concentration doped region 61 in contact with the second electrode 9. The doping concentration of the second high-concentration doped region 61 is higher than the doping concentration of the second low-concentration doped region 60.

[0081] In a possible embodiment, a first passivation / anti-reflective laminated structure 70 is formed on the passivation layer 3 in the direction away from the semiconductor substrate, and the first electrode 4 is connected to the passivation layer 3 via the first passivation / anti-reflective laminated structure 70. Optionally, as shown in Figure 1, a second passivation / anti-reflective laminated structure 71 is further formed on the light-receiving surface S1 of the semiconductor substrate 1, and the second electrode 9 is connected to the second high-concentration doped region 61 via the second passivation / anti-reflective laminated structure 71.

[0082] In a possible embodiment, referring to Figure 3, if the passivation layer is a doped passivation layer 30, the doped passivation layer 30 includes a first high-concentration doped region 63 and a first low-concentration doped region 62. The first high-concentration doped region 63 is connected to the first electrode 4. The first low-concentration doped region 62 is located on one side of the first high-concentration doped region 63, and the doping concentration of the first high-concentration doped region 63 is higher than the doping concentration of the first low-concentration doped region 62.

[0083] Since the first high-concentration doped region 63 is connected to the first electrode 4, good ohmic contact between the first electrode 4 and the doped passivation layer 30 can be ensured, thereby increasing the curve factor. Furthermore, since the first low-concentration doped region 62 is not in contact with the first electrode 4, a non-metallic contact region is formed, and the doping concentration of the first low-concentration doped region 62 is low. Therefore, this contributes to a reduction in Auger recombination in the non-metallic contact region and a reduction in parasitic absorption of ultraviolet light by the doped passivation layer.

[0084] Exemplary, in the actual manufacturing process, a doped passivation layer 30 is formed by performing low-concentration phosphorus diffusion (e.g., dope concentration 1-3E+20) on the passivation layer 3. Next, a first high-concentration doped region 63 is formed by performing localized laser doping on the metallized region using a laser device. The region other than the laser-doped region is a non-metallized region, i.e., a first low-concentration doped region 62. In this way, the problems caused by the uniform doping of the polymer layer in the prior art are solved. In the embodiment of this application, since a passivation layer with low-concentration phosphorus atom doping is employed, the problem of strong free carrier absorption phenomena occurring in the long-wavelength range (i.e., wavelength range of 800 nm to 1200 nm) in the doped passivation layer 30 in the prior art is solved, and battery efficiency is improved. Furthermore, in the prior art, reducing only the phosphorus dope concentration of the polymer layer leads to a decrease in the electric field passivation effect and deterioration of contact performance, whereas in the embodiment of this application, a first high-concentration doped region and a first low-concentration doped region are formed. In the first high-concentration doped region, the doping concentration is high, the electric field passivation effect is strong, and good contact between the doped passivation layer and the first electrode is ensured, preventing a decrease in the curve factor. In the first low-concentration doped region, photoparasitic absorption is reduced, and the current gain becomes significant.

[0085] In conventional technology, in order to ensure good ohmic contact between the doped passivation layer and the first electrode, the silver paste printing line for forming the first electrode 4 is usually wide during screen printing, resulting in high unit consumption and high costs. However, in the embodiment of this application, the first electrode 4 is connected to the first high-concentration doped region 63, thereby ensuring good ohmic contact between the first electrode 4 and the doped passivation layer 30. As a result, the width of the silver paste printing line for forming the first electrode can be appropriately narrowed, thereby reducing manufacturing costs.

[0086] In the embodiments of this application, a first high-concentration doped region and a first low-concentration doped region are formed. The doping concentration of the first high-concentration doped region is high, and the width of the screen printing lines can be appropriately narrowed to ensure good contact between the doped passivation layer and the first electrode. The doping concentration of the first low-concentration doped region is low, and parasitic light absorption is relatively weak, thus reducing current loss and contributing to improved battery efficiency and lower metal pail consumption per unit.

[0087] In a selective embodiment, the thickness of the doped passivation layer is 50 nm or more and 200 nm or less. For example, the thickness of the doped passivation layer may 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 in this application can improve carrier transport efficiency, reduce or eliminate open-circuit voltage loss, and ensure excellent electrical contact performance between the electrodes and the passivation layer without thinning the passivation layer.

[0088] As a possible embodiment, referring to Figure 3, the width of the first high-concentration doped region 63 is greater than the width of the first electrode 4. In the embodiment of this application, the width of the first high-concentration doped region 63 is slightly greater than the width of the first electrode 4. In this case, it facilitates subsequent screen alignment and printing and ensures the quality of the solar cell.

[0089] When the passivation layer is a doped passivation layer 30, the semiconductor substrate 1 may be made of N-type crystalline silicon. A second aluminum oxide passivation layer 80 and a second SiNx anti-reflective passivation layer 81 are formed sequentially on the light-receiving surface S1 of the semiconductor substrate 1, and the semiconductor substrate 1 has a selective emitter on the light-receiving surface S1, and the selective emitter includes a second low-concentration doped region 60 and a second high-concentration doped region 61 that is in contact with the second electrode 9. The second electrode 9 is connected to the second high-concentration doped region 61 via the second SiNx anti-reflective passivation layer 81 and the second aluminum oxide passivation layer 80. A first aluminum oxide passivation layer 82 and a first SiNx anti-reflective passivation layer 83 are formed sequentially on the doped passivation layer 30, and the first electrode 4 is connected to the first high-concentration doped region 63 via the first SiNx anti-reflective passivation layer 83 and the first aluminum oxide passivation layer 82.

[0090] The passivation / anti-reflective laminated structure has the following functions: It can improve photoelectric conversion efficiency by reducing light reflection from the surface of the solar cell, allowing more light rays to enter and be absorbed inside the solar cell. It prevents erosion of the solar cell surface by the external environment, extending the lifespan of the solar cell. It can improve the photoelectric conversion efficiency of the solar cell by reducing recombination losses in the transport process of photogenerated carriers inside the solar cell and increasing carrier collection efficiency. Furthermore, it can protect the surface of the solar cell and prevent the impact of surface defects on solar cell performance.

[0091] In a second aspect, embodiments of the present application further provide a solar cell module comprising two or more solar cells electrically coupled in series with respect to a conductive wire for electrically coupling two or more solar cells in series, wherein the projection of the conductive wire in the plane in which the passivation layer is located partially overlaps with the projection of a first electrode in the plane in which the passivation layer is located.

[0092] When the above technical solution is adopted, the conductive wire can be directly electrically coupled to the first electrode, so the connection point between the conductive wire and the first electrode becomes relatively small, and welding stress is reduced. Furthermore, because the electrical contact performance between the first electrode and the passivation layer is good, even if the welding contact surface between the conductive wire and the first electrode is small, sufficient electrical connection between the conductive wire and the solar cell can be guaranteed, and the battery efficiency of the TOPCon battery can be guaranteed.

[0093] Optionally, a weld point structure may be provided on the first electrode, and the conductive wire is electrically connected to the weld point structure by welding, and the width of the weld point structure is greater than the width of the first electrode in a direction perpendicular to the extension direction of the first electrode.

[0094] In a third aspect, embodiments of this application further provide a method for manufacturing a solar cell. The method for manufacturing a solar cell includes the following steps.

[0095] Referring to Figures 1 to 3, we first provide a semiconductor substrate 1 having opposing light-receiving surfaces S1 and non-light-receiving surfaces S2. A description of the semiconductor substrate will be provided in the first section, and will not be specifically limited here.

[0096] Next, the semiconductor substrate 1 is subjected to a texturing process.

[0097] As an example, a bi-sided texturing process is performed on an N-type primitive silicon wafer using alkali and additives.

[0098] Next, a boron diffusion treatment is performed on the textured semiconductor substrate 1.

[0099] As an example, a boron diffusion layer and a BSG (borosilicate glass) layer are formed on the light-receiving surface S1 of the semiconductor substrate 1.

[0100] Next, the boron diffusion layer and the BSG layer are subjected to localized laser doping.

[0101] Next, the structure after laser doping is subjected to high-temperature oxidation treatment.

[0102] After the above processing, a second high-concentration doped region 61 (corresponding to the laser-doped region) is formed on one side of the light-receiving surface S1 of the semiconductor substrate 1, and the remaining boron diffusion layer is designated as a second low-concentration doped region 60.

[0103] Next, after removing the boron diffusion layer and BSG layer that have spread around to the non-light-receiving surface S2 and sides of the semiconductor substrate 1, the non-light-receiving surface S2 of the semiconductor substrate 1 is polished with an NaOH or KOH alkaline solution.

[0104] Next, an ultrathin dielectric layer 2 is formed on at least one of the non-light-receiving surface S2 and the light-receiving surface S1 of the semiconductor substrate 1.

[0105] In one embodiment, the thickness of the ultrathin dielectric layer 2 is 1 nm or more and 2 nm or less. The thickness direction of the ultrathin dielectric layer 2 coincides with the direction from the light-receiving surface S1 to the non-light-receiving surface S2. For example, the thickness of the ultrathin dielectric layer 2 may be 1 nm, 1.4 nm, 1.6 nm, 1.9 nm, or 2 nm. And / or, the material of the ultrathin dielectric layer 2 includes one of silicon oxide, hafnium oxide, aluminum oxide, or silicon nitride.

[0106] Next, a passivation layer 3 is formed on the ultrathin dielectric layer 2.

[0107] In a possible embodiment, after forming a passivation layer 3 on an ultrathin dielectric layer 2, the method for manufacturing a solar cell further includes the following steps.

[0108] A doped passivation layer 30 is formed by performing a doping diffusion treatment on the passivation layer 3.

[0109] For example, phosphorus is doped into the passivation layer 3 using a low-pressure diffusion furnace, and in the doping diffusion process, the diffusion temperature is between 800°C and 830°C, for example, 800°C, 805°C, 810°C, 815°C, or 830°C. The PN junction formation temperature is between 850°C and 900°C, for example, 850°C, 860°C, 880°C, 890°C, or 900°C.

[0110] Next, a second doping source layer is formed on the doped passivation layer 30 by performing a post-diffusion deposition treatment on the doped passivation layer 30.

[0111] In one embodiment, a PSG (phosphorosilicate glass) layer is formed on the doped passivation layer 30. In the post-diffusion deposition treatment, the diffusion temperature is 820°C or higher and 850°C or lower, for example, 820°C, 825°C, 830°C, 840°C, or 850°C.

[0112] Next, the second doping source layer is locally treated by a laser irradiation process to form a first high-concentration doped region 63 within the doped passivation layer 30. The remaining doped passivation layer 30 is designated as the first low-concentration doped region 62.

[0113] For example, phosphorus atoms in the phosphorus-rich PSG layer are incorporated into the doped passivation layer 30 using a laser, forming a first high-concentration doped region within the doped passivation layer 30.

[0114] The first high-concentration doped region 63 is connected to the first electrode 4, and the doping concentration of the first high-concentration doped region 63 is higher than the doping concentration of the first low-concentration doped region 62.

[0115] When the above technical solution is adopted, the first high-concentration doped region 63 is connected in correspondence with the first electrode 4, thereby ensuring good ohmic contact between the first electrode 4 and the doped passivation layer 30 and increasing the curve factor. Furthermore, since the first low-concentration doped region 62 is not in contact with the first electrode 4, a non-metallic contact region is formed, and the doping concentration of the first low-concentration doped region 62 is low. Therefore, this contributes to a reduction in Auger recombination in the non-metallic contact region and a reduction in parasitic absorption of ultraviolet light by the doped passivation layer.

[0116] Next, the phosphorus diffusion layer and PSG layer that have spread around the light-receiving surface S1 and side surfaces of the semiconductor substrate 1 are removed, and the doped passivation layer 30 plated around the light-receiving surface S1, the BSG layer on the light-receiving surface S1, and the PSG layer on the non-light-receiving surface S2 are removed.

[0117] Next, a first aluminum oxide passivation layer 82 is formed on the doped passivation layer 30, and a second aluminum oxide passivation layer 80 is formed on the light-receiving surface S1 of the semiconductor substrate 1.

[0118] Next, a first SiNx anti-reflective passivation layer 83 is formed on the first aluminum oxide passivation layer 82, and a second SiNx anti-reflective passivation layer 81 is formed on the second aluminum oxide passivation layer 80.

[0119] Next, the first electrode 4 and the second electrode 9 are formed.

[0120] The first electrode 4, located on the non-photoreceiving surface S2, is connected to the first high-concentration doped region 63 via a first SiNx anti-reflective passivation layer 83 and a first aluminum oxide passivation layer 82. The second electrode 9, located on the photoreceiving surface S1, is connected to the second high-concentration doped region 61 via a second SiNx anti-reflective passivation layer 81 and a second aluminum oxide passivation layer 80.

[0121] A metal crystal is formed within the passivation layer 3, and the metal crystal includes a first metal crystal 50, with one end face of the first metal crystal 50 in contact with the ultrathin dielectric layer 2, and the other end face of the first metal crystal 50 connected to the first electrode 4.

[0122] Compared to conventional technology, the solar cell manufacturing method provided in the embodiment of this application can improve carrier transport efficiency, reduce or eliminate open-circuit voltage loss, and ensure excellent electrical contact performance between the electrode and the passivation layer without thinning the passivation layer 3. Furthermore, since one end face of the first metal crystal 50 abuts against the ultrathin dielectric layer 2 and the other end face of the first metal crystal 50 is connected to the first electrode 4, a metal-ultrathin dielectric-semiconductor structure is formed. Also, since the first metal crystal 50 is located within the passivation layer 3, the first metal crystal 50 can make sufficient contact with the passivation layer 3. Based on this, by controlling the ratio of the first metal crystal 50, the curve factor can be optimized and the open-circuit voltage and curve factor can be balanced. In addition, the action of the first metal crystal 50 contributes to the movement of carriers to the first electrode 4, increasing the carrier transport rate and shortening the time required for carriers to pass through the passivation layer 3. Furthermore, since the first metal crystal 50 does not penetrate the semiconductor substrate 1 through the ultrathin dielectric layer 2, this ensures that the ultrathin dielectric layer 2 is not damaged and does not affect the function of the ultrathin dielectric layer 2. In other words, it guarantees good chemical passivation and tunneling effect of the ultrathin dielectric layer. In addition, it also reduces the impact on the open-circuit voltage and avoids damage to the semiconductor substrate 1, thereby ensuring that the function of the semiconductor substrate 1 is not affected and ensuring the performance of the solar cell.

[0123] In summary, the first metal crystal contacts the ultrathin dielectric layer, and since the structure of the ultrathin dielectric layer is not destroyed, good chemical passivation and tunneling effect of the ultrathin dielectric layer are guaranteed. The ultrathin dielectric layer acts as a tunnel transport layer for majority carriers, transporting majority carriers in the semiconductor substrate and allowing them to pass through the ultrathin dielectric layer. The first metal crystal then rapidly transports the majority carriers that have passed through the ultrathin dielectric layer to the first electrode, thereby ensuring a higher curve factor. Due to the good majority carrier transport efficiency of the passivation structure, contact resistivity and series resistance can be reduced, thus ensuring higher battery efficiency.

[0124] In possible embodiments, the ratio of the number of first metal crystals to the total number of metal crystals is 2% or more and 20% or less, for example, 2%, 5%, 8%, 12%, 15%, 17%, 18%, or 20%. In this case, it is possible to avoid the effect of too many first metal crystals on the carrier tunneling effect of the tunnel-polycrystalline structure.

[0125] As a possible embodiment, referring to Figure 2, the width of the first metal crystal 50 gradually decreases in the direction from the first electrode 4 to the passivation layer 3.

[0126] When the above technical solution is adopted, the width of the first metal crystal gradually decreases in the direction from the first electrode to the passivation layer, reducing corrosion of the passivation layer and the semiconductor substrate, and reducing metal composites at the metal-ultrathin dielectric layer interface. Furthermore, the width of the first metal crystal gradually increases in the direction from the passivation layer to the first electrode, increasing the contact area between the first metal crystal and the first electrode, which contributes to improving the transport efficiency of majority carriers transported to the first electrode by the first metal crystal along the light-receiving surface to the non-light-receiving surface.

[0127] For example, in the direction from the first electrode 4 to the passivation layer 3, the first metal crystal 50 is approximately trapezoidal.

[0128] In a selective embodiment, one end face of the first metal crystal 50 abuts against the ultrathin dielectric layer 2, and the other end face of the first metal crystal 50 penetrates into the first electrode 4, with the specific penetration depth being set according to actual requirements.

[0129] As a possible embodiment, referring to Figure 2, 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 distributed at a distance 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 both the second metal crystal 51 and the passivation layer 3 coincides with the direction from the non-photosensitive surface S2 to the photosensitive surface S1. One end face of the second metal crystal 51 may penetrate into the first electrode 4. The penetration depth of the second metal crystal 51 into the first electrode 4 and the thickness of the second metal crystal 51 are set according to actual requirements and are not specifically limited here.

[0130] In this case, the movement of carriers to the first electrode 4 contributes to a higher carrier transport rate, reducing the time required for carriers to pass through the passivation layer 3 and ensuring the battery efficiency of the TOPCon battery. In addition, it is also possible to reduce the contact resistance between the first electrode 4 and the passivation layer 3. Furthermore, since the thickness of the second metal crystal 51 is smaller than the thickness of the passivation layer 3, damage to the ultrathin dielectric layer 2 and semiconductor substrate 1 by the second metal crystal 51 can be avoided, ensuring the performance of the solar cell.

[0131] In a selective embodiment, multiple secondary metal crystals are distributed at intervals. And / or, the ratio of the number of secondary metal crystals to the total number of metal crystals is 50% or more and not exceeding 90%, and may be, for example, 50%, 58%, 62%, 75%, 82%, or 90%.

[0132] By employing the above technical solution, the movement of carriers to the first electrode contributes to a higher carrier transport rate, and the time required for carriers to pass through the passivation layer is further reduced, thereby ensuring the battery efficiency of the TOPCon battery. In addition, the contact resistance between the first electrode and the passivation layer can be reduced. Furthermore, since the thickness of the second metal crystal is smaller than the thickness of the passivation layer, damage to the ultrathin dielectric layer and semiconductor substrate by the second metal crystal can be avoided, thus ensuring the performance of the solar cell.

[0133] In a selective embodiment, referring to Figure 2, the metal crystal 5 further includes a third metal crystal 52. The third metal crystal 52 is distributed at intervals from the first electrode 4, the ultrathin dielectric layer 2, and the second metal crystal 51. That is, the third metal crystal 52 is not connected to the first electrode 4, nor to the ultrathin dielectric layer 2.

[0134] In this case, the movement of carriers to the first electrode 4 contributes to a higher carrier transport rate, shortening the time required for carriers to pass through the passivation layer 3 and ensuring the battery efficiency of the TOPCon battery. Furthermore, since the third metal crystal 52 is distributed at a distance from the ultrathin dielectric layer 2, damage to the ultrathin dielectric layer 2 and the semiconductor substrate 1 by the third metal crystal 52 is avoided, ensuring the performance of the solar cell.

[0135] In a selective embodiment, referring to Figure 2, the multiple third metal crystals 52 are discretely distributed within the passivation layer 3. And / or, in the direction from the first electrode 4 to the passivation layer 3, the pitch between the third metal crystals 52 and the first electrode 4 is smaller than the pitch between the third metal crystals 52 and the ultrathin dielectric layer 2. In the embodiments of this application, the pitch between the third metal crystals 52 and the first electrode 4 is less than half the thickness of the passivation layer 3. And / or, the ratio of the number of second metal crystals 51 to the total number of metal crystals is 5% or less.

[0136] In a selective embodiment, as shown in Figure 2, smaller metal crystals tend to detach easily from the first electrode 4 body, but they grow deep into the passivation layer 3 and are difficult to stretch. Therefore, the ratio of the average volume of the third metal crystal 52 to the average volume of the second metal crystal 51 is 10% or less.

[0137] When the above technical solution is adopted, the small third metal crystal 52 is easily detached from the first electrode 4 body, and although the third metal crystal is undesirable in the actual manufacturing process, it is unavoidable during manufacturing. Therefore, in order to reduce the impact of the third metal crystal on the solar cell efficiency, it is necessary to control the average volume and number of the third metal crystal within the above range.

[0138] As explained above, 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.

[0139] In the description of the embodiments above, specific features, structures, materials, or properties can be appropriately combined in any one or more embodiments or examples.

[0140] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any modifications or substitutions that a person skilled in the art could easily conceive within the scope of the art disclosed in this application should also be included within 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. [Explanation of Symbols]

[0141] 1. Semiconductor substrate S1 Photosensitive surface S2 Non-light receiving surface 2. Ultrathin dielectric layer 3. Passivation Layer 30 Doped Passivation Layer 4 1st electrode 5 Metallic Crystals 50 First Metallic Crystal 51 Second Metallic Crystal 52 Third Metallic Crystals 60 Second Low-Concentration Doping Zone 61 Second High-Concentration Doped Area 62. First Low-Concentration Doping Region 63. First High-Concentration Doped Area 64 Emitter 70. First Passivation / Anti-Reflective Laminated Structure 71 Second Passivation / Anti-Reflective Laminated Structure 80. Aluminum oxide passivation layer 81 Second SiNx anti-reflective passivation layer 82. Aluminum Oxide Passivation Layer 83. First SiNx anti-reflective passivation layer 9 Second electrode

Claims

1. A semiconductor substrate having opposing light-receiving and non-light-receiving surfaces, An ultrathin dielectric layer located on at least one of the non-light-receiving surface and the light-receiving surface of the semiconductor substrate, A passivation layer located on the aforementioned ultrathin dielectric layer, The first electrode located on the passivation layer, The metal crystal located within the passivation layer, Includes, A solar cell in which the metal crystal includes a first metal crystal, one end face of the first metal crystal is in contact with the ultrathin dielectric layer, and the other end face of the first metal crystal is connected to the first electrode.

2. The solar cell according to claim 1, wherein the passivation layer is locally provided on at least one of the non-light-receiving surface and the light-receiving surface.

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

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

5. The aforementioned metal crystal is The solar cell according to claim 1, further comprising a second metal crystal connected to the first electrode and distributed at a distance from the first metal crystal, wherein the thickness of the second metal crystal is less than the thickness of the passivation layer, and both the thickness direction of the second metal crystal and the thickness direction of the passivation layer coincide with the direction from the non-light-receiving surface to the light-receiving surface.

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

7. The aforementioned metal crystal is The solar cell according to claim 5, further comprising a third metal crystal distributed at intervals from the first electrode, the ultrathin dielectric layer, and the second metal crystal.

8. The plurality of the third metal crystals are discretely distributed within the passivation layer, and / or In the direction from the first electrode to the passivation layer, the pitch between the third metal crystal and the first electrode is smaller than the pitch between the third metal crystal and the ultrathin dielectric layer, and / or The ratio of the number of the second metal crystals to the total number of the metal crystals is 5% or less, and / or The solar cell according to claim 7, wherein the ratio of the average volume of the third metal crystal to the average volume of the second metal crystal is 10% or less.

9. If the passivation layer is a doped passivation layer, the doped passivation layer is A first high-concentration doped region connected to the first electrode, A solar cell according to any one of claims 1 to 8, comprising: a first low-concentration doped region located on one side of the first high-concentration doped region, wherein the doping concentration of the first high-concentration doped region is higher than the doping concentration of the first low-concentration doped region.

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

11. The thickness of the ultrathin dielectric layer is 1 nm or more and 2 nm or less, the thickness direction of the ultrathin dielectric layer coincides with the direction from the light-receiving surface to the non-light-receiving surface, and / or The solar cell according to claim 1, wherein the material of the ultrathin dielectric layer includes one of silicon oxide, hafnium oxide, aluminum oxide, and silicon nitride.

12. A solar cell module comprising two or more solar cells according to any one of claims 1 to 11, electrically coupled in series with each other, further comprising a conductive wire for electrically coupling the two or more solar cells in series, wherein the projection of the conductive wire in the plane in which the passivation layer is located partially overlaps with the projection of the first electrode in the plane in which the passivation layer is located.

13. The steps include providing a semiconductor substrate having opposing light-receiving and non-light-receiving surfaces, The steps include forming an ultrathin dielectric layer on at least one of the non-light-receiving surface and the light-receiving surface of the semiconductor substrate, The steps include forming a passivation layer on the ultrathin dielectric layer, The steps include forming a first electrode on the passivation layer such that a metal crystal is formed within the passivation layer, Includes, A method for manufacturing a solar cell, wherein the metal crystal includes a first metal crystal, one end face of the first metal crystal is in contact with the ultrathin 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 the ratio of the number of first metal crystals to the total number of metal crystals is 2% or more and 20% or less.

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

16. After the step of forming a passivation layer on the ultrathin dielectric layer, The steps include forming a doped passivation layer by performing a dope diffusion treatment on the passivation layer, The steps include forming a second doping source layer on the doped passivation layer by performing a post-diffusion deposition treatment on the doped passivation layer, The process further includes the step of locally treating the second doping source layer with a laser irradiation process to form a first high-concentration doped region within the dope passivation layer, and making the remaining dope passivation layer a first low-concentration doped region. A method for manufacturing a solar cell according to claim 13, wherein the first high-concentration doped region is connected to the first electrode, and the doping concentration of the first high-concentration doped region is higher than the doping concentration of the first low-concentration doped region.

17. In the doping diffusion treatment described above, the diffusion temperature is 800°C or higher and 830°C or lower. In the aforementioned post-diffusion deposition treatment, the diffusion temperature is 820°C or higher and 850°C or lower. A method for manufacturing a solar cell according to claim 16.

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