Solar cell, method for manufacturing the same, photovoltaic module and photovoltaic system

Abstract

The present invention relates to a solar cell, a manufacturing method thereof, a photovoltaic module and a photovoltaic system. The manufacturing method of the solar cell includes: providing a substrate, the substrate including a base and a tunneling oxide layer disposed on one surface of the base; sequentially laminating a first doped amorphous silicon layer, a second intrinsic amorphous silicon layer and a third doped amorphous silicon layer on a surface of the tunneling oxide layer facing away from the base; performing a heat treatment to enable a doping element in the third doped amorphous silicon layer to diffuse into the second intrinsic amorphous silicon layer, and enabling the first doped amorphous silicon layer, the second intrinsic amorphous silicon layer and the third doped amorphous silicon layer to respectively form a first doped polycrystalline silicon layer, a second doped polycrystalline silicon layer and a third doped polycrystalline silicon layer. The solar cell, the manufacturing method thereof, the photovoltaic module and the photovoltaic system of the present invention can improve the conversion efficiency of the solar cell.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a solar cell and a manufacturing method thereof, a photovoltaic module and a photovoltaic system. Background Art

[0002] In the solar cells in the prior art, in order to reduce the recombination rate, extend the minority carrier lifetime, and improve the photoelectric conversion efficiency of the solar cells, the silicon substrate is generally passivated to form a passivation contact structure on the surface of the silicon substrate to reduce the recombination of surface carriers, thereby reducing the impact caused by internal defects of the silicon substrate. Among them, the common passivation contact structure combines the tunneling oxide layer with the heavily doped polysilicon layer, and reduces the interface recombination between the silicon substrate and the doped polysilicon layer through the chemical passivation of the tunneling oxide layer. However, during the formation of the doped polysilicon layer, during high-temperature treatment, hydrogen elements are often released in the form of gas, which destroys the adhesion between the polysilicon layer and the tunneling oxide layer, causing the polysilicon layer to burst, and reducing the passivation effect of the polysilicon layer. Summary of the invention

[0003] Based on this, it is necessary to provide a solar cell and a method for manufacturing the same, a photovoltaic module and a photovoltaic system, which can improve the surface passivation effect of the passivation contact structure, reduce surface recombination, and improve the conversion efficiency of the solar cell.

[0004] A first aspect of an embodiment of the present application provides a method for manufacturing a solar cell, comprising:

[0005] Providing a substrate, the substrate comprising a base and a tunnel oxide layer disposed on a surface of the base;

[0006] A first doped amorphous silicon layer, a second intrinsic amorphous silicon layer and a third doped amorphous silicon layer are sequentially stacked on a surface of the tunnel oxide layer away from the substrate, wherein the first doped amorphous silicon layer is doped with carbon elements and the third doped amorphous silicon layer is doped with P-type or N-type elements;

[0007] Heat treatment is performed to diffuse the doping elements in the third doped amorphous silicon layer into the second intrinsic amorphous silicon layer, and to form the first doped amorphous silicon layer, the second intrinsic amorphous silicon layer and the third doped amorphous silicon layer into a first doped polysilicon layer, a second doped polysilicon layer and a third doped polysilicon layer respectively.

[0008] In one embodiment, the atomic ratio of carbon atoms to silicon atoms in the first doped amorphous silicon layer is 5%-50%.

[0009] In one embodiment, the first doped amorphous silicon layer is further doped with the same P-type or N-type element as that in the third doped amorphous silicon layer.

[0010] In one embodiment, the doping concentration of the P-type or N-type element in the first doped amorphous silicon layer and the third doped amorphous silicon layer is both 1E19 - 1E21 cm -3 .

[0011] In one embodiment, the specific steps of the heat treatment include:

[0012] Perform crystallization treatment on the first doped amorphous silicon layer, the second intrinsic amorphous silicon layer, and the third doped amorphous silicon layer at 700°C - 1000°C.

[0013] In one embodiment, the step of providing a substrate includes:

[0014] Form a tunneling oxide layer on one surface of the substrate.

[0015] In the second aspect of the embodiments of the present application, a solar cell is provided, and the solar cell is fabricated by using the foregoing method for fabricating a solar cell.

[0016] In one embodiment, the doping concentration of the second doped polysilicon layer is less than that of the third doped polysilicon layer.

[0017] In one embodiment, the thickness of the first doped polysilicon layer is 10 nm - 30 nm; and / or

[0018] The thickness of the second doped polysilicon layer is 5 nm - 20 nm; and / or

[0019] The thickness of the third doped polysilicon layer is 10 nm - 200 nm.

[0020] In the third aspect of the embodiments of the present application, a photovoltaic module is provided, including at least one battery string, and the battery string includes at least two of the foregoing solar cells.

[0021] In the fourth aspect of the embodiments of the present application, a photovoltaic system is provided, including the foregoing photovoltaic module.

[0022] Beneficial effects of the foregoing solar cell, its fabrication method, photovoltaic module, and photovoltaic system:

[0023] Good passivation of the substrate is achieved by forming a tunneling oxide layer and first, second, and third doped polysilicon layers as a passivation contact structure. Among them, the first doped polysilicon layer is also doped with carbon element, and carbon element is not easily combined with hydrogen element. Thus, compared with the case of not doping carbon element, there is less hydrogen element in the first doped polysilicon layer. Therefore, during the high-temperature crystallization treatment process, the overflow of gas is alleviated, making it difficult for the first, second, and third doped polysilicon layers to peel off, reducing the occurrence of film bursting, improving the surface passivation effect of the passivation contact structure, reducing surface recombination, and enhancing the conversion efficiency of the solar cell.

[0024] Meanwhile, when the first doped polysilicon layer is doped with carbon element, the first doped polysilicon layer has good adhesion to the tunneling oxide layer and also has high strength, and is less likely to peel off during the heat treatment process. In addition, by sequentially forming the second doped polysilicon layer and the third doped polysilicon layer on the surface of the first doped polysilicon layer facing away from the substrate, the problem of relatively high resistivity caused by the introduction of carbon element in the first doped polysilicon layer can be improved to a certain extent, reducing the overall resistivity and sheet resistance of the first, second, and third doped polysilicon layers, and improving the lateral transport ability of carriers.

[0025] Moreover, since a second intrinsic amorphous silicon layer is formed between the first doped amorphous silicon layer and the third doped amorphous silicon layer, acting as a diffusion buffer layer, during the heat treatment process, it can avoid the doping elements in the third doped amorphous silicon layer from diffusing into the first doped amorphous silicon layer to a certain extent, so that the concentration and distribution uniformity of the doping elements in the first doped amorphous silicon layer are not affected by other film layers, especially the third doped amorphous silicon layer, and the passivation quality is also improved. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the solar cell provided by the embodiment of the present application;

[0027] Figure 2 It is a schematic flow diagram of the manufacturing method of the solar cell provided by the embodiment of the present application;

[0028] Figure 3 It is a schematic structural diagram of the substrate in the manufacturing method of the solar cell provided by the embodiment of the present application;

[0029] Figure 4 It is a schematic diagram of forming a first doped amorphous silicon layer, a second intrinsic amorphous silicon layer, and a third doped amorphous silicon layer on the substrate in the manufacturing method of the solar cell provided by the embodiment of the present application;

[0030] Figure 5Schematic diagram of a first doped polysilicon layer, a second doped polysilicon layer, and a third doped polysilicon layer formed on a substrate in the method for manufacturing a solar cell provided by an embodiment of the present application.

[0031] Explanation of reference numerals in the drawings:

[0032] 100, solar cell; 110, substrate; 10, base

[0033] 20, tunneling oxide layer; 30, first doped amorphous silicon layer; 40, second intrinsic amorphous silicon layer; 50, third doped amorphous silicon layer; 60, first doped polysilicon layer; 70, second doped polysilicon layer; 80, third doped polysilicon layer; 90, passivation layer; 91, electrode. Detailed implementation manners

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0036] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0037] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present invention, unless otherwise clearly defined or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0040] The following describes the solar cell, its manufacturing method, the photovoltaic module and the photovoltaic system according to the embodiments of the present application with reference to the drawings. It should be noted that in the present application, a TOPCon cell (Tunnel Oxide Passivated Contact) is taken as an example for illustration. The solar cell may also be other types of solar cells. The situation where the solar cell is of other types is similar and will not be elaborated here.

[0041] Figure 1 It is a schematic structural diagram of the solar cell 100 provided for the embodiments of the present application.

[0042] Refer to Figure 1, the solar cell 100 provided by the embodiment of the present application includes a substrate 10, and a tunneling oxide layer 20, a first doped polysilicon layer 60, a second doped polysilicon layer 70, and a third doped polysilicon layer 80 that are sequentially stacked on one surface of the substrate 10. The first doped polysilicon layer 60 is doped with carbon element, and the third doped polysilicon layer 80 is doped with a P-type or N-type element.

[0043] By forming the tunneling oxide layer 20, the first doped polysilicon layer 60, the second doped polysilicon layer 70, and the third doped polysilicon layer 80 as a passivation contact structure, good passivation of the substrate 10 is achieved. Among them, the first doped polysilicon layer 60 is doped with carbon element, and carbon element is not easy to combine with hydrogen element. Thus, compared with the case of not doping carbon element, there is less hydrogen element in the first doped polysilicon layer 60. Therefore, during the high-temperature crystallization treatment process, the overflow of gas is alleviated, so that the first doped polysilicon layer 60, the second doped polysilicon layer 70, and the third doped polysilicon layer 80 are not easily peeled off, reducing the occurrence of film bursting, and can improve the surface passivation effect of the passivation contact structure, reduce surface recombination, and improve the conversion efficiency of the solar cell 100.

[0044] At the same time, when the first doped polysilicon layer 60 is doped with carbon element, the first doped polysilicon layer 60 has good adhesion to the tunneling oxide layer 20 and also has high strength. Therefore, during the heat treatment process, it is less likely to peel off.

[0045] In addition, by sequentially forming the second doped polysilicon layer 70 and the third doped polysilicon layer 80 on the surface of the first doped polysilicon layer 60 facing away from the substrate 10, the problem of relatively high resistivity caused by the introduction of carbon element in the first doped polysilicon layer 60 can be improved to a certain extent, reducing the overall resistivity and sheet resistance of the first doped polysilicon layer 60, the second doped polysilicon layer 70, and the third doped polysilicon layer 80, and improving the lateral transport ability of carriers.

[0046] In the embodiment of the present application, the doping concentration of the second doped polysilicon layer 70 is less than that of the third doped polysilicon layer 80. Since the doping concentration of the second doped polysilicon layer 70 is less than that of the third doped polysilicon layer 80, during the formation process of the solar cell 100, it can block the diffusion of the doping elements in the third doped polysilicon layer 80 into the first doped polysilicon layer 60 to a certain extent, so that the concentration and distribution uniformity of the doping elements in the first doped polysilicon layer 60 are not affected by other film layers, especially the third doped polysilicon layer 80, and the passivation quality is also improved.

[0047] Further, the thickness of the first doped polysilicon layer 60 is 10 nm - 30 nm, preferably 10 nm - 20 nm. By controlling the thickness of the first doped polysilicon layer 60 within the above range, the film bursting can be minimized to the greatest extent, and the conductivity of the passivated contact structure can also be made better.

[0048] Further, the thickness of the second doped polysilicon layer 70 is 5 nm - 20 nm, preferably 5 nm - 10 nm; and / or the thickness of the third doped polysilicon layer 80 is 10 nm - 200 nm, preferably 50 nm - 100 nm.

[0049] With such a setting, when fabricating the electrode, it can be avoided that the metal paste burns through the outermost third doped polysilicon layer 80 and the second doped polysilicon layer 70 and directly contacts the first doped polysilicon layer 60 with a higher resistivity, thereby increasing the contact resistance.

[0050] In addition, a passivation layer 90 is further provided on the surface of the third doped polysilicon layer 80 facing away from the substrate 10, and an electrode 91 is further provided on the passivation layer. The electrode 91 is in ohmic contact with the third doped polysilicon layer 80.

[0051] The passivation layer 90 can adopt a single-layer or multi-layer structure, and the material of the passivation layer 90 can be alumina, silicon oxide, silicon nitride or silicon oxynitride. The passivation layer 90 can include, for example, at least one antireflection layer. Thus, the passivation layer 90 serves both the passivation and antireflection functions.

[0052] In addition, although not shown, the solar cell 100 further includes a first passivation layer, a doped conductive layer, and a first electrode.

[0053] The doped conductive layer and the first passivation layer are sequentially stacked on the surface of the substrate away from the tunneling oxide layer 20.

[0054] In actual situations, the solar cell 100 can include an N-type cell and a P-type cell. The substrate of the N-type cell is doped with an N-type element, and the doped conductive layer is doped with a P-type element. The substrate of the P-type cell is doped with a P-type element, and the doped conductive layer is doped with an N-type element. The doped conductive layer is used to form a PN junction with the substrate. In the embodiments of the present application, taking the substrate 10 as an N-type substrate as an example for illustration, at this time, the doped conductive layer can be P-type doping, for example, a doped conductive layer doped with boron element (also referred to as a P+ type emitter).

[0055] The first passivation layer is stacked on the doped conductive layer. The first passivation layer plays a surface passivation role and an antireflection role in the solar cell 100, can chemically passivate the dangling bonds on the surface of the substrate 10 well, and has an antireflection effect on the front surface of the solar cell 100.

[0056] The first passivation layer can adopt a single-layer structure or a multi-layer structure, and the material of the first passivation layer can be at least one of alumina, silicon oxide, silicon nitride, or silicon oxynitride. Additionally, the first electrode is disposed on the first passivation layer and is in ohmic contact with the doped conductive layer.

[0057] Figure 2 It is a schematic flow chart of the manufacturing method of the solar cell provided by the embodiment of the present application.

[0058] The second aspect of the embodiment of the present application provides a manufacturing method of a solar cell, and this method can manufacture the solar cell 100 as described in the previous embodiments.

[0059] Refer to Figure 2 , the manufacturing method of the solar cell of the embodiment of the present application includes:

[0060] S10. Provide a substrate, and the substrate includes a base and a tunneling oxide layer provided on one surface of the base.

[0061] S20. Sequentially stack and form a first doped amorphous silicon layer, a second intrinsic amorphous silicon layer, and a third doped amorphous silicon layer on the surface of the tunneling oxide layer facing away from the base. The first doped amorphous silicon layer is doped with carbon element, and the third doped amorphous silicon layer is doped with a P-type or N-type element.

[0062] S30. Perform a heat treatment to enable the doping element in the third doped amorphous silicon layer to diffuse into the second intrinsic amorphous silicon layer, and to form a first doped polycrystalline silicon layer, a second doped polycrystalline silicon layer, and a third doped polycrystalline silicon layer from the first doped amorphous silicon layer, the second intrinsic amorphous silicon layer, and the third doped amorphous silicon layer respectively.

[0063] By forming the tunneling oxide layer 20 and the first doped polycrystalline silicon layer 60, the second doped polycrystalline silicon layer 70, and the third doped polycrystalline silicon layer 80 as a passivation contact structure, good passivation of the base is achieved. Among them, the first doped polycrystalline silicon layer 60 is also doped with carbon element, and carbon element and hydrogen element are not easily combined. Thus, compared with the case of not doping carbon element, there is less hydrogen element in the first doped polycrystalline silicon layer 60. Therefore, during the high-temperature crystallization treatment process, the overflow of gas is alleviated, making it difficult for the first doped polycrystalline silicon layer 60, the second doped polycrystalline silicon layer 70, and the third doped polycrystalline silicon layer 80 to peel off, reducing the occurrence of film bursting, improving the surface passivation effect of the passivation contact structure, reducing surface recombination, and enhancing the conversion efficiency of the solar cell 100.

[0064] At the same time, when the first doped polycrystalline silicon layer 60 is doped with carbon element, the first doped polycrystalline silicon layer 60 has good adhesion to the tunneling oxide layer 20 and also has high strength, and is less likely to peel off during the heat treatment process.

[0065] In addition, by sequentially forming a second doped polysilicon layer 70 and a third doped polysilicon layer 80 on the surface of the first doped polysilicon layer 60 facing away from the substrate 10, the problem that the resistivity of the entire passivation contact structure is relatively high due to the introduction of carbon elements in the first doped polysilicon layer 60 can be improved to a certain extent, the resistivity and sheet resistance of the first doped polysilicon layer 60, the second doped polysilicon layer 70, and the third doped polysilicon layer 80 as a whole are reduced, and the lateral transport ability of carriers is improved.

[0066] Moreover, since a second intrinsic amorphous silicon layer 40 is formed between the first doped amorphous silicon layer 30 and the third doped amorphous silicon layer 50, which acts as a diffusion buffer layer, during the heat treatment process, it can avoid the doping elements in the third doped amorphous silicon layer 50 from diffusing into the first doped amorphous silicon layer 30 to a certain extent, so that the concentration and distribution uniformity of the doping elements in the first doped amorphous silicon layer 30 are not affected by other film layers, especially the third doped amorphous silicon layer 50, and the passivation quality is also improved.

[0067] In the embodiment of the present application, the atomic ratio of carbon atoms to silicon atoms contained in the first doped amorphous silicon layer 30 is 5% - 50%, that is, 5:100 - 50:100, preferably 5% - 8%, that is, 5:100 - 8:100.

[0068] With such a setting, the first doped amorphous silicon layer 30 can effectively prevent film bursting and does not have a high resistivity.

[0069] The first doped amorphous silicon layer 30 may be doped only with carbon elements, or may be doped with P-type or N-type elements while doping with carbon elements.

[0070] For example, the first doped amorphous silicon layer 30 is further doped with the same type of P-type or N-type elements as those in the third doped amorphous silicon layer 50.

[0071] In the embodiment of the present application, the doping concentration of the P-type or N-type elements in the first doped amorphous silicon layer 30 and the third doped amorphous silicon layer 50 is both 1E19 - 1E21 cm -3 .

[0072] Here, the doping elements in the first doped amorphous silicon layer 30 and the third doped amorphous silicon layer 50 may be nitrogen, phosphorus, arsenic that provide electrons, or boron, aluminum, gallium that provide holes.

[0073] In the embodiment of the present application, in step S30, the specific steps of the heat treatment include:

[0074] Performing crystallization treatment on the first doped amorphous silicon layer 30, the second intrinsic amorphous silicon layer 40, and the third doped amorphous silicon layer 50 at 700°C - 1000°C, and the temperature is preferably 840°C - 890°C.

[0075] When the temperature of the heat treatment is in the range of 700°C - 1000°C, the doping elements in the third doped amorphous silicon layer 50 can be avoided from entering the first doped amorphous silicon layer 30 as much as possible.

[0076] In the embodiment of the present application, in step S10, the step of providing a substrate 110 includes:

[0077] Form a tunneling oxide layer 20 on one surface of the substrate.

[0078] The thickness of the tunneling oxide layer 20 can be less than 3 nm. For example, it can be 1.5 nm. Through the above settings of the first doped polysilicon layer 60, the second doped polysilicon layer 70, and the third doped polysilicon layer 80, the thickness of the tunneling oxide layer 20 can be made thinner.

[0079] Figure 3 It is a schematic structural diagram of the substrate in the manufacturing method of the solar cell provided by the embodiment of the present application; Figure 4 It is a schematic diagram of forming a first doped amorphous silicon layer, a second intrinsic amorphous silicon layer, and a third doped amorphous silicon layer on the substrate in the manufacturing method of the solar cell provided by the embodiment of the present application; Figure 5 It is a schematic diagram of the first doped polysilicon layer, the second doped polysilicon layer, and the third doped polysilicon layer formed on the substrate in the manufacturing method of the solar cell provided by the embodiment of the present application.

[0080] The following combines Figure 1 , Figure 3 , Figure 4 , Figure 5 to illustrate the manufacturing method of the solar cell of the embodiment of the present application.

[0081] The method includes:

[0082] Step 1: Refer to Figure 3 , clean the substrate 10, and prepare a layer of silicon dioxide with a thickness less than 3 nm as the tunneling oxide layer 20 on one surface in the thickness direction of the substrate 10. The preparation method is thermal oxidation, and the thickness of the silicon dioxide is preferably 1.5 mm

[0083] Step 2: Refer to Figure 4 , use chemical vapor deposition (PECVD) to prepare a first doped amorphous silicon layer 30 on the surface of the tunneling oxide layer 20, with a thickness preferably of 10 - 30 nm, the atomic ratio of carbon atoms to silicon atoms being 5 - 50%, the doping elements being carbon, and nitrogen, phosphorus, arsenic that provide electrons or boron, aluminum, gallium that provide holes, and its doping concentration being 1E19 - 1E21 cm -3 . When the doping element is an n-type element, the reaction gases are silane, phosphine, hydrogen, and methane. When the doping element is a p-type element, the reaction gases are silane, borane, hydrogen, and methane.

[0084] Step 3: Continue to refer to Figure 4 , and form a second intrinsic amorphous silicon layer 40 on the first doped amorphous silicon layer 30 by plasma enhanced chemical vapor deposition (PECVD). The reaction gases are silane, hydrogen, and methane, and the thickness is preferably 5 - 20 nm.

[0085] Step 4: Refer to Figure 4 , and deposit a third doped amorphous silicon layer 50 on the surface of the second intrinsic amorphous silicon layer 40 by plasma enhanced chemical vapor deposition (PECVD). The doping atoms are nitrogen, phosphorus, arsenic that provide electrons or boron, aluminum, gallium that provide holes, and the doping concentration is 1E19 - 1E21 cm -3 , and the thickness is preferably 10 - 200 nm. When the doping element is an N-type doping element, the reaction gases are silane, phosphine, hydrogen, and methane. When the doping element is a P-type doping element, the reaction gases are silane, borane, hydrogen, and methane.

[0086] Step 5: Refer to Figure 5 , and perform crystallization treatment at 700 - 1000 °C to enable the doping elements in the third doped amorphous silicon layer to diffuse into the second intrinsic amorphous silicon layer, and to form a first doped polycrystalline silicon layer 60, a second doped polycrystalline silicon layer 70, and a third doped polycrystalline silicon layer 80 from the first doped amorphous silicon layer 30, the second intrinsic amorphous silicon layer 40, and the third doped amorphous silicon layer 50 respectively.

[0087] Step 6: Deposit a passivation layer 90 of a single layer or stack of alumina, silicon nitride, or silicon oxide on the third polycrystalline silicon doped layer 80 by plasma enhanced chemical vapor deposition (PECVD) or atomic layer deposition (ALD), thereby forming a passivated contact structure and forming an electrode 91, thus obtaining Figure 1 the solar cell shown.

[0088] Denote the solar cell generated through the above steps as A, and denote the solar cell with a passivated contact structure composed of a tunneling oxide layer and a polycrystalline silicon doped conductive layer as B.

[0089] Perform cell performance tests on solar cell A and solar cell B, and record the test results in Table 1. Among them, Voc is the open-circuit voltage; FF is the fill factor; Eta is the conversion efficiency; Isc is the short-circuit current.

[0090] Table 1: Performance test results of solar cell A and solar cell B

[0091] As can be seen from the above experimental results, compared with solar cell B, the open-circuit voltage of solar cell A prepared by the method of the embodiment of the present application is increased by 0.002V, the fill factor is increased by about 0.45%, the cell conversion efficiency is increased by about 0.15%, and the short-circuit current is increased by 0.02A. Therefore, it can be known that the efficiency of solar cell A fabricated by the method of this embodiment is relatively high.

[0092] In the third aspect of the embodiment of the present application, a photovoltaic module (not shown) is provided, which includes at least one battery string. The battery string includes at least two solar cells 100 as described above, and the solar cells 100 can be connected together by string soldering.

[0093] In the fourth aspect of the embodiment of the present application, a photovoltaic system (not shown) is provided, which includes the above-mentioned photovoltaic module.

[0094] The photovoltaic system can be applied in photovoltaic power stations, such as ground power stations, rooftop power stations, water surface power stations, etc., and can also be applied to devices or apparatuses that use solar energy for power generation, such as user solar power supplies, solar street lamps, solar cars, solar buildings, and so on. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this. That is to say, the photovoltaic system can be applied in all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a busbar box, and an inverter. The photovoltaic array can be an array combination of multiple photovoltaic modules. For example, multiple photovoltaic modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the busbar box, and the busbar box can collect the current generated by the photovoltaic array. After the collected current flows through the inverter and is converted into alternating current required by the commercial power grid, it is connected to the commercial power grid to achieve solar power supply.

[0095] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0096] The above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A method for manufacturing a solar cell, characterized in that: include: Providing a substrate, the substrate comprising a base and a tunneling oxide layer disposed on a surface of the base; A first doped amorphous silicon layer, a second intrinsic amorphous silicon layer and a third doped amorphous silicon layer are sequentially stacked on a surface of the tunnel oxide layer away from the substrate, wherein the first doped amorphous silicon layer is doped with carbon elements, and the third doped amorphous silicon layer is doped with P-type or N-type elements; Performing a heat treatment so that the doping element in the third doped amorphous silicon layer diffuses into the second intrinsic amorphous silicon layer, and the first doped amorphous silicon layer, the second intrinsic amorphous silicon layer and the third doped amorphous silicon layer form a first doped polysilicon layer, a second doped polysilicon layer and a third doped polysilicon layer respectively; The first doped amorphous silicon layer is also doped with the same P-type or N-type element as that in the third doped amorphous silicon layer.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: The atomic ratio of carbon atoms to silicon atoms contained in the first doped amorphous silicon layer is 5%-50%.

3. The method for manufacturing a solar cell according to claim 1, characterized in that: The doping concentration of the P-type or N-type element in the first doped amorphous silicon layer and the third doped amorphous silicon layer is 1E19-1E21cm -3 .

4. The method for manufacturing a solar cell according to claim 1, characterized in that: The specific steps of the heat treatment include: The first doped amorphous silicon layer, the second intrinsic amorphous silicon layer and the third doped amorphous silicon layer are subjected to a crystallization treatment at 700° C.-1000° C.

5. The method for manufacturing a solar cell according to claim 1, characterized in that: The step of providing a substrate comprises: A tunnel oxide layer is formed on one surface of the substrate.

6. A solar cell, characterized in that: The solar cell is manufactured by the method for manufacturing a solar cell according to any one of claims 1 to 5.

7. The solar cell according to claim 6, characterized in that: The doping concentration of the second doped polysilicon layer is less than the doping concentration of the third doped polysilicon layer.

8. The solar cell according to claim 6, characterized in that: The thickness of the first doped polysilicon layer is 10nm-30nm; and / or The thickness of the second doped polysilicon layer is 5nm-20nm; and / or The thickness of the third doped polysilicon layer is 10nm-200nm.

9. A photovoltaic module, characterized in that: The method comprises at least one battery string, wherein the battery string comprises at least two solar cells according to any one of claims 6 to 8.

10. A photovoltaic system, characterized in that: Comprising the photovoltaic module as claimed in claim 9.

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