Passivation contact structure, solar cell and photovoltaic module

Abstract

The utility model relates to the technical field of solar cells, in particular to a passivation contact structure, a solar cell and a photovoltaic module. The passivation contact structure comprises a dielectric layer which is a silicon oxynitride layer, and the thickness of the dielectric layer is 1.2 nm to 3 nm; the doping layer is arranged on the dielectric layer, and the thickness of the doping layer ranges from 30 nm to 80 nm; wherein the doped layer comprises a first doped polycrystalline silicon layer, a silicon oxide layer and a second doped polycrystalline silicon layer, the first doped polycrystalline silicon layer, the silicon oxide layer and the second doped polycrystalline silicon layer are sequentially arranged in the direction away from the dielectric layer, the first doped polycrystalline silicon layer and the second doped polycrystalline silicon layer are doped polycrystalline silicon layers doped with doping elements, and the thickness of the silicon oxide layer ranges from 1.5 nm to 3 nm. The passivation contact structure can improve the short-circuit current, optimize the passivation performance and improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a passivation contact structure, a solar cell and a photovoltaic module. Background Art

[0002] Passivated contact solar cells usually include a passivated contact structure, that is, a dielectric layer and a doped polysilicon layer, which uses this structural feature to reduce recombination losses and improve the efficiency of solar cells. However, the efficiency level of passivated contact solar cells has reached a bottleneck stage and is difficult to improve further. Utility Model Content

[0003] The purpose of the embodiments of the present application is to provide a passivation contact structure, a solar cell and a photovoltaic module to solve problems such as the film bursting phenomenon caused by thinning of the doped polysilicon layer, and effectively improve the efficiency of the solar cell.

[0004] To achieve the above objectives, the present application provides the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a passivation contact structure, the passivation contact structure comprising:

[0006] A dielectric layer, wherein the dielectric layer is a silicon oxynitride layer, and the thickness of the dielectric layer is 1.2 nm to 3 nm;

[0007] A doping layer disposed on the dielectric layer, wherein the thickness of the doping layer is 30 nm to 80 nm;

[0008] Among them, the doped layer includes a first doped polysilicon layer, a silicon oxide layer and a second doped polysilicon layer arranged in sequence along a direction away from the dielectric layer, the first doped polysilicon layer and the second doped polysilicon layer are both doped polysilicon layers doped with doping elements, and the thickness of the silicon oxide layer is 1.5nm to 3nm.

[0009] Furthermore, the refractive index of the silicon oxynitride layer is greater than or equal to 1.77 and less than or equal to 2.5.

[0010] Further, the thickness of the first doped polysilicon layer is 6nm-16nm, and the thickness of the second doped polysilicon layer is 24nm-63nm; and / or,

[0011] The sheet resistance of the doped layer is 18Ω·sq -1 ~30Ω·sq -1 .

[0012] Further, the doping concentration of the doping element in the second doped polysilicon layer is higher than the doping concentration of the doping element in the first doped polysilicon layer.

[0013] Furthermore, the second doped polysilicon layer includes a first sublayer disposed close to the silicon oxide layer, and a second sublayer disposed away from the silicon oxide layer, and a doping concentration of the doping element in the second sublayer is higher than a doping concentration of the doping element in the first sublayer.

[0014] Furthermore, the thickness of the first sub-layer is 12 nm to 31 nm, and the thickness of the second sub-layer is 24 nm to 32 nm.

[0015] Furthermore, the doping concentration of the doping element in the second sub-layer is 3×10 21 Pieces / cm 3 ~6×10 21 Pieces / cm 3 .

[0016] In a second aspect, the present application provides a solar cell, comprising a silicon substrate and a passivation contact structure as described in the first aspect, wherein the dielectric layer is disposed close to the silicon substrate, and the doping layer is disposed away from the silicon substrate.

[0017] Furthermore, the silicon substrate has a diffusion layer on one side facing the dielectric layer, and the diffusion layer, the first doped polysilicon layer, and the second doped polysilicon layer have doping elements of the same conductivity type, and the doping concentration of the doping elements in the diffusion layer is lower than the doping concentration of the doping elements in the first doped polysilicon layer.

[0018] Furthermore, the solar cell further comprises:

[0019] A passivation layer, disposed on a side of the doped layer away from the dielectric layer;

[0020] an electrode, wherein the electrode penetrates the passivation layer and forms an ohmic contact with the doping layer;

[0021] Wherein, the passivation layer is a silicon nitride layer, and / or the electrode forms an ohmic contact with the doping layer through a laser induced contact processing device.

[0022] In a third aspect, the present application provides a photovoltaic component, wherein the photovoltaic component comprises the passivation contact structure as described in the first aspect.

[0023] Compared with the prior art, the beneficial effects of the embodiments of the present application are:

[0024] The embodiment of the present application provides a passivation contact structure. The solar cell with the passivation contact structure can not only increase the short-circuit current by thinning the thickness of the doped layer, but also improve the film bursting problem caused by the thinning of the doped polysilicon layer by using a silicon oxynitride layer of a specific thickness and a silicon oxide layer of a specific thickness, thereby optimizing the passivation performance and improving the photoelectric conversion efficiency of the solar cell.

[0025] In the passivation contact structure of the embodiment of the present application, the thickness of the doping layer is only 30nm to 80nm, which is thinner than the doping layer with a thickness of more than 100nm. Therefore, the parasitic absorption loss of photogenerated carriers can be reduced and the transmission distance of photogenerated carriers can be shortened by reducing the thickness of the doping layer, thereby increasing the short-circuit current.

[0026] As for the problem of film bursting that is easily caused by the thinning of the doped layer, on the one hand, in the embodiment of the present application, an extremely thin silicon oxide layer of 1.5nm to 3nm is added between the first doped polysilicon layer and the second doped polysilicon layer of the doped layer. The silicon oxide layer at this thickness can serve as a barrier layer for H and doping elements in the doped layer, which can not only prevent the doping elements doped in the second doped polysilicon layer from penetrating the dielectric layer in large quantities and causing the film bursting phenomenon, but also prevent the first doped polysilicon layer and the second doped polysilicon layer from mixing with hydrogen generated in the subsequent processing process, thereby slowing down the film bursting phenomenon caused by the concentrated escape of a large amount of hydrogen, thereby effectively alleviating the problem of easier film bursting due to the thinning of the doped layer.

[0027] On the other hand, the embodiment of the present application also uses a 1.2nm to 3nm silicon oxynitride layer as a dielectric layer, and utilizes the characteristics that the silicon oxynitride layer is less dense than the silicon oxide dielectric layer and is more conducive to the diffusion of doping elements, so that the small amount of doping elements that enter the dielectric layer after being blocked by the silicon oxide layer in the doping layer can more easily reach the interface between the silicon substrate and the dielectric layer in the passivation contact solar cell. In this way, the doping elements that enter the interface of the silicon substrate can promote the formation of a certain degree of concentration gradient structure at the interface, forming a significant energy band bending, thereby alleviating the carrier recombination at the interface and enhancing the passivation performance of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a schematic structural diagram of a passivation contact structure of an embodiment of the present application;

[0030] Figure 2is a schematic structural diagram of another passivation contact structure in an embodiment of the present application;

[0031] Figure 3 It is a schematic diagram of the structure of the solar cell of the embodiment of the present application;

[0032] Figure 4 It is a schematic diagram of the structure of another solar cell according to an embodiment of the present application.

[0033] Reference numerals:

[0034] 1. Passivation contact structure; 11. Dielectric layer; 12. Doping layer; 121. First doped polysilicon layer; 122. Silicon oxide layer; 123. Second doped polysilicon layer; 1231. First sublayer; 1232. Second sublayer; 2. Silicon substrate; 21. Diffusion layer; 3. Passivation layer; 4. Electrode. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0037] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0038] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0040] The technical solution provided in this application will be further described below in conjunction with embodiments and drawings.

[0041] In a passivated contact solar cell, the thickness of the doped polysilicon layer is usually greater than or equal to 100nm. Although the thinner the doped polysilicon layer, the more conducive it is to reducing parasitic absorption, it is more likely to cause film bursting. It can be seen that it is not easy to thin the doped polysilicon layer. It is difficult to further improve the photoelectric conversion efficiency of solar cells by only thinning the doped polysilicon layer.

[0042] The reason why the thinner the doped polysilicon layer is, the easier it is to cause film explosion is because the film explosion phenomenon of the doped polysilicon layer is mainly affected by the following two aspects: the first aspect is that the doping elements in the doped polysilicon layer pass through the dielectric layer more and cause film explosion. When the thickness of the doped polysilicon layer becomes thinner, more doping elements will pass through the dielectric layer, which will make the film explosion phenomenon serious. The second aspect is closely related to the large amount of hydrogen escape. The doped polysilicon layer is usually deposited by plasma enhanced chemical vapor deposition (PECVD) equipment, which makes a large amount of hydrogen enter the doped amorphous silicon layer. In the subsequent process of crystallization annealing to transform the doped amorphous silicon layer into a doped polysilicon layer, these hydrogens gather and store in the doped polysilicon layer in the form of hydrogen. After the temperature of the subsequent processing steps rises to a certain level, these hydrogens will escape in large quantities, resulting in the occurrence of film explosion. The thinner the thickness of the doped polysilicon layer, the easier it is for hydrogen to escape, and the more serious the film phenomenon.

[0043] Based on an in-depth analysis of the above-mentioned problems, the embodiments of the present application provide a passivation contact structure, a solar cell and a photovoltaic module. By improving the passivation contact structure, while thinning the doped polysilicon layer, the impact of the film bursting phenomenon is effectively improved, the passivation performance of the solar cell is optimized, and the photoelectric conversion efficiency of the solar cell is further improved.

[0044] In a first aspect, the present application embodiment provides a passivation contact structure 1, combined with Figure 1 As shown, Figure 1It is a schematic diagram of the structure of the passivation contact structure 1 of the embodiment of the present application. The passivation contact structure 1 includes a dielectric layer 11 and a doping layer 12 arranged on the dielectric layer 11. Among them, the dielectric layer 11 is a silicon oxynitride layer 122, and the thickness of the dielectric layer 11 is 1.2nm~3nm; the doping layer 12 includes a first doped polysilicon layer 121, a silicon oxide layer 122 and a second doped polysilicon layer 123 arranged in sequence along the direction away from the dielectric layer 11, the first doped polysilicon layer 121 and the second doped polysilicon layer 123 are both doped polysilicon layers doped with doping elements, the total thickness of the doping layer 12 is 30nm~80nm, and the thickness of the silicon oxide layer 122 is 1.5nm~3nm.

[0045] The dielectric layer 11 acts as a barrier for electrons and holes, and can be combined with the doped layer 12 to prevent minority carriers from passing through. The dielectric layer 11 can also have a pinhole channel effect, allowing the carriers in the solar cell to move freely, and selective passage of majority carriers is generated by heavily doped polysilicon, which is beneficial to reduce the recombination loss of minority carriers. The thickness of the dielectric layer 11 is 1.2nm to 3nm, including any point value within the thickness range, for example, the thickness of the dielectric layer 11 is 1.2nm, 1.4nm, 1.5nm, 1.8nm, 2nm, 2.2nm, 2.5nm, 2.8nm or 3nm.

[0046] Wherein, the first doped polysilicon layer 121 and the second doped polysilicon layer 123 are doped with doping elements, so that the first doped polysilicon layer 121 and the second doped polysilicon layer 123 have better carrier transport capabilities. The doping element can be an N-type doping element or a P-type doping element. Exemplarily, the N-type doping element can be a fifth main group element such as phosphorus, arsenic, antimony or bismuth, and the P-type doping element can be a third main group element such as boron, gallium, indium or thallium. The thickness of the doped layer 12 is 30nm to 80nm, including any point value within the thickness range, for example, the thickness of the doped layer 12 is 30nm, 40nm, 45nm, 50nm, 55nm, 60nm, 70nm or 80nm. The thickness of the silicon oxide layer 122 is 1.5nm to 3nm, including any point value within the thickness range, for example, the thickness of the silicon oxide layer 122 is 1.5nm, 1.8nm, 2nm, 2.2nm, 2.5nm, 2.8nm or 3nm.

[0047] The embodiment of the present application improves both the dielectric layer 11 and the doped layer 12 of the passivation contact structure 1, uses a silicon oxynitride layer 122 instead of a silicon oxide layer 122 as the dielectric layer 11, and sets an ultra-thin silicon oxide layer 122 of a specific thickness between two doped polysilicon layers. By jointly improving the above-mentioned film layer structure, the thickness of the doped polysilicon layer can be reduced, and the film bursting phenomenon can be improved on the basis of thinning, and the passivation performance can be optimized, thereby achieving the effect of improving the short-circuit current, open-circuit voltage and fill factor, thereby promoting the effective improvement of the photoelectric conversion efficiency of solar cells.

[0048] First, the thickness of the doped polysilicon layer is reduced in the embodiment of the present application, and the thickness of the doped layer 12 is only 30nm to 80nm, and the thickness of the silicon oxide layer 122 is 1.5nm to 3nm, indicating that the thickness of the doped polysilicon layer in the doped layer 12 is close to 30nm to 80nm. Such a thickness of the doped polysilicon layer can effectively reduce the parasitic absorption of carriers and shorten the transmission distance of carriers, which is conducive to improving the short-circuit current of the solar cell with the passivation contact structure 1.

[0049] Secondly, in order to solve the serious problem of film bursting caused by the thinning of the doped layer 12, the embodiment of the present application adopts an ultra-thin silicon oxynitride dielectric layer 11 and adds an ultra-thin silicon oxide layer 122 between the doped layer 12, and utilizes the combined effect of the silicon oxynitride layer 122 and the silicon oxide layer 122 to solve the above problem. Among them, the silicon oxide layer 122 added between the first doped polysilicon layer 121 and the second doped polysilicon layer 123 has a thickness controlled at 1.5nm to 3nm, which can effectively reduce the content of doping elements entering the interior (i.e., entering the first doped polysilicon layer 121, the dielectric layer 11, and the surface of the silicon substrate 2 of the solar cell) from the side of the second doped polysilicon layer 123 to avoid excessive doping elements directly penetrating the dielectric layer 11 and causing film explosion, and can also serve as a barrier layer to avoid the first doped polysilicon layer 121 and the second doped polysilicon layer 123 from mixing and escaping in large quantities after the temperature is increased in the subsequent process, thereby improving the problem of serious film explosion caused by thinning of the doped layer 12 from two aspects.

[0050] On this basis, and precisely because the silicon oxide layer 122 has a strong blocking effect on doping elements, if the dielectric layer 11 also uses the silicon oxide layer 122, it will again have a strong blocking effect on a small amount of doping elements that are blocked by the silicon oxide layer 122 in the doping layer 12 and then diffuse from the first doped polysilicon layer 121 into the dielectric layer 11. This will make it more difficult for the doping elements, which are originally only a small amount, to pass through the dielectric layer 11 to reach the surface of the silicon substrate 2 of the solar cell, affecting the passivation effect at the interface of the silicon substrate 2. Therefore, the present application uses a silicon nitride oxide layer 122 with a thickness of 1.2nm to 3nm as the dielectric layer 11 to replace the commonly used silicon oxide dielectric layer 11, based on the addition of a silicon oxide layer 122 in the doping layer 12. The silicon nitride oxide layer 122 has a lower density than the silicon oxide layer 122 and the diffusion speed of the doping elements therein is faster than that in the silicon oxide layer 122, so that a small amount of doping elements can be smoothly diffused to the surface of the silicon substrate 2 through the dielectric layer 11, instead of being almost blocked by silicon oxide and unable to reach the surface of the silicon substrate 2. In this way, a small amount of doping elements entering the interface of the silicon substrate 2 can promote the formation of a certain degree of concentration gradient structure at the interface, forming a significant energy band bending, thereby alleviating carrier recombination at the interface, enhancing the passivation performance of the solar cell, improving the open circuit voltage and fill factor of the solar cell, and promoting the effective improvement of the photoelectric conversion efficiency of the solar cell.

[0051] It is understandable that the dielectric layer 11 and the doping layer 12 in the embodiment of the present application can be film layers deposited by low pressure chemical vapor deposition (LPCVD) equipment or PECVD equipment. It is preferably deposited by PECVD equipment. Although hydrogen elements are easily introduced into the first doped polysilicon layer 121 and the second doped polysilicon layer 123 in the doping layer 12 deposited by the PECVD equipment, since the present application uses a silicon oxynitride layer 122 as the dielectric layer 11, and a silicon oxide layer 122 is provided between the first doped polysilicon layer 121 and the second doped polysilicon layer 123, it is able to solve the problem of film explosion generated during the subsequent crystallization annealing process. It can be seen that the technical solution of the embodiment of the present application is particularly suitable for solving the problem of film explosion caused by the deposition of the dielectric layer 11 and the doping layer 12 by the PECVD equipment.

[0052] Further, the refractive index of the silicon oxynitride layer 122 is greater than or equal to 1.77 and less than or equal to 2.5. Exemplarily, the refractive index of the silicon oxynitride layer 122 is 1.77, 1.8, 1.82, 1.85, 1.88, 1.9, 2.02.1, 2.2, 2.3 or 2.5; it should be noted that, since the deposition thickness of the silicon oxynitride layer 122 on the entire surface of the silicon substrate 2 is difficult to be exactly the same, when the refractive index is n, the thickness of the silicon oxynitride layer 122 is n-0.5≤n≤n+0.5. The silicon oxynitride layer 122 with a refractive index greater than or equal to 1.77 has a high silicon content and belongs to a silicon-rich layer structure, having a structure similar to that of a hydrogenated amorphous silicon layer, and thus also has a high hydrogen content; however, when the silicon content in the silicon oxynitride layer 122 is as high as its corresponding refractive index equals to 2.5, the high silicon content in the silicon oxynitride layer 122 may greatly weaken the blocking effect of the silicon oxynitride layer 122 on the doped elements, and also reduce the interface passivation effect of the silicon oxynitride layer 122 on the silicon substrate 2. Therefore, when the refractive index of the silicon oxynitride layer 122 is set to be greater than or equal to 1.77 and less than or equal to 2.5, it is beneficial to enhance the interface passivation performance on the silicon substrate 2, and at the same time, a small amount of doped elements can diffuse through the silicon oxynitride layer 122 and form a certain degree of concentration gradient structure in the inner layer of the silicon substrate 2, forming a significant energy band bending, thereby alleviating the carrier recombination at the interface and improving the photoelectric conversion efficiency of the solar cell.

[0053] The doping layer 12 is further introduced below.

[0054] In the doping layer 12, the thickness of the first doped polysilicon layer 121 is 6nm to 16nm, and the thickness of the second doped polysilicon layer 123 is 24nm to 63nm. Controlling the thickness of the first doped polysilicon layer 121 and the second doped polysilicon layer 123 in the doping layer 12 within the above range can ensure that the doped polysilicon layer fully absorbs sunlight and meet the requirements of thinning to improve the photoelectric conversion efficiency. In addition, the thickness of the second doped polysilicon layer 123 is set thicker, which can better meet the requirements of subsequent electrode 4 slurry sintering and reduce the risk of electrode 4 slurry burning through the doping layer 12. Among them, the thickness of the first doped polysilicon layer 121 is 6nm to 16nm, including any point value within the thickness range, for example, the thickness of the first doped polysilicon layer 121 is 6nm, 8nm, 10nm, 12nm, 14nm or 16nm. Among them, the thickness of the second doped polysilicon layer 123 is 24nm~63nm, including any point value within this thickness range, for example, the thickness of the second doped polysilicon layer 123 is 24nm, 25nm, 28nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm or 63nm.

[0055] Furthermore, the sheet resistance of the doped layer 12 is 18Ω·sq-1 ~30Ω·sq -1 When the doping layer 12 is within the square resistance range, it has a better doping concentration of the doping element, which is beneficial to improve the carrier transmission capability of the doping layer 12 and reduce the contact resistance of the doping layer 12 when it contacts the metal electrode 4 later. Among them, the square resistance of the doping layer 12 is 18Ω·sq -1 ~30Ω·sq -1 Including any point value within the range of the square resistance, for example, the square resistance of the doped layer 12 is 18Ω·sq -1 , 20Ω·sq -1 , 22Ω·sq -1 , 24Ω·sq -1 , 25Ω·sq -1 , 28Ω·sq -1 or 30 sq. -1 .

[0056] Furthermore, the doping concentration of the doping element in the second doped polysilicon layer 123 is higher than the doping concentration of the doping element in the first doped polysilicon layer 121. Since the second doped polysilicon layer 123 located on the outside is in direct contact with the metal electrode 4 of the solar cell, the doping concentration of the doping element in this layer is higher, which is more conducive to reducing the contact resistance when the silicon in the second doped polysilicon layer 123 contacts the metal electrode 4, and is also conducive to improving the passivation effect of the contact position between the second doped polysilicon layer 123 and the metal electrode 4, and promoting the improvement of indicators such as the open circuit voltage and filling performance of the solar cell. In addition, the first doped polysilicon layer 121 located on the inside is closer to the dielectric layer 11 (that is, closer to the silicon substrate 2 of the solar cell), so the doping concentration of the doping element in this layer is lower, which is more conducive to controlling the amount of the doping element that passes through the dielectric layer 11 and diffuses to the surface of the silicon substrate 2.

[0057] See also Figure 2 As shown, Figure 2 1 is another schematic diagram of the structure of the passivation contact structure 1 according to an embodiment of the present application, in which the second doped polysilicon layer 123 is provided in two layers. Figure 2 As shown, the second doped polysilicon layer 123 includes a first sublayer 1231 disposed close to the silicon oxide layer 122 and a second sublayer 1232 disposed away from the silicon oxide layer 122 , and the doping concentration of the doping element in the second sublayer 1232 is higher than the doping concentration of the doping element in the first sublayer 1231 .

[0058] The second doped polysilicon layer 123 is set as a second sublayer 1232 and a first sublayer 1231 with decreasing doping concentration, so that more film layers can be used to better form a decreasing gradient of doping element concentration from the outside to the inside. This setting can further optimize the contact performance between the doped polysilicon layer and the metal electrode 4, including reducing the contact resistance between silicon and the metal electrode 4, and optimizing the passivation performance of the contact position between the doped polysilicon layer and the metal electrode 4. It can be understood that in the embodiment of the present application, when the second doped polysilicon layer 123 is a multi-layer setting, it is not limited to two sublayers, and three, four or more sublayers can be set, and the doping concentration of the doping elements in these sublayers is set to decrease from the side away from the silicon oxide layer 122 to the side close to the silicon oxide layer 122.

[0059] It should be noted that the first sublayer 1231 and the second sublayer 1232 are arranged adjacent to each other, but the silicon oxide layer 122 is not arranged between the first sublayer 1231 and the second sublayer 1232. This allows the doping elements to form a smoother doping gradient between the first sublayer 1231 and the second sublayer 1232, which is beneficial to improving the performance of the solar cell.

[0060] Furthermore, the thickness of the first sublayer 1231 is 12 nm to 31 nm, and the thickness of the second sublayer 1232 is 24 nm to 32 nm. In addition, the doping concentration of the doping element in the second sublayer 1232 is 3×10 21 Pieces / cm 3 ~6×10 21 Pieces / cm 3 It can be seen that the second doped polysilicon layer can meet the requirements of thinning the thickness of the doped polysilicon layer and the requirements of a smooth doping gradient by setting multiple sublayers, and can also ensure that the doping elements in the outermost second sublayer have a higher doping concentration. In other words, ensuring that a thinner second doped polysilicon layer can still ensure a higher surface doping concentration level is beneficial to improving the photoelectric conversion efficiency of solar cells.

[0061] By controlling the thickness and doping concentration of the first sublayer 1231 and the second sublayer 1232 within the above range, it is possible to better improve the contact performance between the doping layer 12 and the metal electrode 4 while satisfying the overall thickness reduction of the doping layer 12, improve the passivation effect of the metal contact position, and reduce the contact resistance between the metal electrode 4 and silicon, thereby promoting the improvement of the opening voltage and filling performance of the solar cell.

[0062] In the second aspect, an embodiment of the present application provides a solar cell, comprising: a silicon substrate 2 and a passivation contact structure 1 arranged close to it, wherein the passivation contact structure 1 is the passivation contact structure 1 described in the first aspect above, wherein the dielectric layer 11 is arranged close to the silicon substrate 2, and the doping layer 12 is arranged away from the silicon substrate 2.

[0063] The solar cell of the embodiment of the present application is provided with the passivation contact structure 1 of the first aspect mentioned above, so that it can not only reduce parasitic absorption, but also optimize the passivation performance, and also improve the film bursting phenomenon, thereby achieving the effect of increasing the short-circuit current, open-circuit voltage and fill factor, and effectively improving the photoelectric conversion efficiency of the solar cell.

[0064] Among them, the conductivity type of the silicon substrate 2 can be either N-type or P-type, which is not limited in the present application. The silicon substrate 2 has a light-receiving surface and a backlight surface, and the passivation contact structure 1 can be arranged on the light-receiving surface of the silicon substrate 2, can be arranged on the backlight surface of the silicon substrate 2, or can be arranged on both the light-receiving surface and the backlight surface of the silicon substrate 2, which is not limited in the present application. For example, in an optional embodiment, the silicon substrate 2 is an N-type silicon substrate 2, the passivation contact structure 1 is located on the backlight surface of the N-type silicon substrate 2, and the doped polysilicon layer in the passivation contact structure 1 has a different conductivity type from the N-type silicon substrate 2. Specifically, the passivation contact structure 1 includes a dielectric layer 11, a P-type first doped polysilicon layer 121, a silicon oxide layer 122, and a P-type second doped polysilicon layer 123 that are sequentially away from the silicon substrate 2. In another optional embodiment, the silicon substrate 2 is an N-type silicon substrate 2, and the passivation contact structure 1 is located on the light-receiving surface of the N-type silicon substrate 2, including a dielectric layer 11, an N-type first doped polysilicon layer 121, a silicon oxide layer 122 and an N-type second doped polysilicon layer 123 that are sequentially away from the silicon substrate 2.

[0065] The following description will be made by taking the arrangement of the above-mentioned passivation contact structure 1 on the backlight surface of a solar cell as an example.

[0066] Further integration Figure 3 As shown, Figure 3 Schematic diagram of the structure of the solar cell of the present application. The solar cell specifically comprises:

[0067] Silicon substrate 2;

[0068] A passivation contact structure 1 and a passivation layer 3 are sequentially arranged on the backlight surface of a silicon substrate 2; wherein the dielectric layer 11 of the passivation contact structure 1 is arranged close to the silicon substrate 2, and the doping layer 12 of the passivation contact structure 1 is arranged away from the silicon substrate 2;

[0069] The electrode 4 penetrates through the passivation layer 3 and makes ohmic contact with the doping layer 12 .

[0070] A diffusion layer 21 is provided on a side of the silicon substrate 2 facing the dielectric layer 11 , and the diffusion layer 21 and the first doped polysilicon layer 121 and the second doped polysilicon layer 123 have doping elements of the same conductivity type.

[0071] The diffusion layer 21 is formed by diffusing the doping elements in the doping layer 12 to the surface of the silicon substrate 2 through the dielectric layer 11, and thus has the same conductive elements as the first doped polysilicon layer and the second doped polysilicon layer 123. In addition, the doping concentration of the doping elements in the diffusion layer 21 is lower than the doping concentration of the doping elements in the first doped polysilicon layer 121.

[0072] During the diffusion of the doping elements in the first doped polysilicon layer 121 to the silicon oxynitride layer 122, although most of the doping elements are blocked by the silicon oxynitride layer 122, a small amount of doping elements can still reach the surface of the silicon substrate 2 to form a diffusion layer 21 because of the faster diffusion speed in the silicon oxynitride layer 122 than the silicon oxide layer 122 and the lower density of silicon oxynitride. These small amounts of doping elements diffuse into the silicon substrate 2 through the silicon oxynitride layer 122, which can reduce the recombination at the interface between the silicon substrate 2 and the silicon oxynitride layer 122 and improve the passivation effect.

[0073] As another optional implementation, see further Figure 4 As shown, Figure 4 The second doped polysilicon layer 123 includes a first sublayer 1231 disposed close to the silicon oxide layer 122 and a second sublayer 1232 disposed away from the silicon oxide layer 122, and the doping concentration of the doping element in the second sublayer 1232 is higher than the doping concentration of the doping element in the first sublayer 1231.

[0074] The passivation layer 3 is disposed on the side of the doped layer 12 away from the silicon substrate 2 to play a corresponding passivation role. The passivation layer 3 is preferably a silicon nitride layer deposited by a PECVD device.

[0075] Among them, the electrode 4 is a metal electrode 4, and a silver electrode 4, an aluminum electrode 4 or a silver-aluminum electrode 4 can be selected, and the present application does not impose any restrictions on this. Taking the electrode 4 as a silver electrode 4 as an example, the electrode 4 is in ohmic contact with the doping layer 12 through a laser induced contact processing device. Specifically, the silver electrode 4 slurry is printed onto the passivation layer 3 and processed by a laser induced contact processing (Laser Induced Firing, LIF) device so that the silver electrode 4 penetrates the passivation layer 3 and forms an ohmic contact with the doping layer 12. After being processed by the laser induced contact processing equipment, the ohmic contact between the passivation layer 3 and the doping layer 12 can be effectively improved, the contact resistance between silicon and metallic silver can be reduced, and the short-circuit current and open-circuit voltage can be further improved.

[0076] It should be noted that the solar cell of the present application may also include other functional film structures. For example, the solar cell of the present application may also include a PN junction disposed on the light-receiving surface of the silicon substrate 2, a passivation layer 3 disposed on the side of the PN junction away from the silicon substrate 2, and an electrode 4 for ohmic contact with the PN junction. The above-mentioned structural components may be conventionally arranged, and the present application does not limit them.

[0077] In a third aspect, an embodiment of the present application provides a photovoltaic module, which includes the passivation contact structure as described in the first aspect.

[0078] The above is a detailed introduction to a passivation contact structure, solar cell and photovoltaic module disclosed in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the embodiments of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the embodiments of the present application. At the same time, for general technicians in this field, according to the ideas of the embodiments of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the embodiments of the present application.

Claims

1. A passivation contact structure, characterized in that: The passivation contact structure comprises: A dielectric layer, wherein the dielectric layer is a silicon oxynitride layer, and the thickness of the dielectric layer is 1.2 nm to 3 nm; A doping layer disposed on the dielectric layer, wherein the thickness of the doping layer is 30 nm to 80 nm; Among them, the doped layer includes a first doped polysilicon layer, a silicon oxide layer and a second doped polysilicon layer arranged in sequence along a direction away from the dielectric layer, the first doped polysilicon layer and the second doped polysilicon layer are both doped polysilicon layers doped with doping elements, and the thickness of the silicon oxide layer is 1.5nm to 3nm.

2. The passivation contact structure according to claim 1, characterized in that: The refractive index of the silicon oxynitride layer is greater than or equal to 1.77 and less than or equal to 2.

5.

3. The passivation contact structure according to claim 1, characterized in that: The thickness of the first doped polysilicon layer is 6 nm to 16 nm, and the thickness of the second doped polysilicon layer is 24 nm to 63 nm; and / or, The sheet resistance of the doped layer is 18Ω·sq -1 ~30Ω·sq -1 .

4. The passivation contact structure according to claim 1, characterized in that: The doping concentration of the doping element in the second doped polysilicon layer is higher than the doping concentration of the doping element in the first doped polysilicon layer.

5. The passivation contact structure according to any one of claims 1 to 4, characterized in that: The second doped polysilicon layer includes a first sublayer disposed close to the silicon oxide layer and a second sublayer disposed away from the silicon oxide layer, and a doping concentration of the doping element in the second sublayer is higher than a doping concentration of the doping element in the first sublayer.

6. The passivation contact structure according to claim 5, characterized in that: The thickness of the first sublayer is 12 nm to 31 nm, and the thickness of the second sublayer is 24 nm to 32 nm; and / or, The doping concentration of the doping element in the second sublayer is 3×10 21 Pieces / cm 3 ~6×10 21 Pieces / cm 3 .

7. A solar cell, characterized in that: The solar cell comprises a silicon substrate and a passivation contact structure as claimed in any one of claims 1 to 6, wherein the dielectric layer is arranged close to the silicon substrate, and the doping layer is arranged away from the silicon substrate.

8. The solar cell according to claim 7, characterized in that: The silicon substrate has a diffusion layer on one side facing the dielectric layer. The diffusion layer, the first doped polysilicon layer, and the second doped polysilicon layer all have doping elements of the same conductivity type. The doping concentration of the doping element in the diffusion layer is lower than the doping concentration of the doping element in the first doped polysilicon layer.

9. The solar cell according to any one of claims 7 or 8, characterized in that: The solar cell also includes: A passivation layer, disposed on a side of the doped layer away from the dielectric layer; an electrode, wherein the electrode penetrates the passivation layer and forms an ohmic contact with the doping layer; Wherein, the passivation layer is a silicon nitride layer, and / or the electrode forms an ohmic contact with the doping layer through a laser induced contact processing device.

10. A photovoltaic module, characterized in that: The photovoltaic module comprises the passivation contact structure according to any one of claims 1 to 6.

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