Back contact photovoltaic cells and their manufacturing methods, photovoltaic modules

Abstract

This application relates to the field of photovoltaic cells, providing a back-contact photovoltaic cell and its manufacturing method, as well as a photovoltaic module. The method includes: providing a substrate; forming an intrinsic silicon layer on a first surface of the substrate, the intrinsic silicon layer including a first region, a spacer region, and a second region arranged sequentially; forming a mask layer on the surfaces of the spacer region and the second region; doping the first region with a first element to form a first doped layer, with some of the first element diffusing into the spacer region; removing the mask layer corresponding to the spacer region, forming a barrier layer on the side of the mask layer facing away from the substrate; removing the mask layer corresponding to the second region; doping the second region with a second element to form a second doped layer, with some of the second element diffusing into the spacer region, the spacer region being converted into a contact control portion, the contact control portion being electrically connected to the first doped layer and the second doped layer; and forming a first electrode and a second electrode on the first doped layer and the second doped layer, respectively. This application at least helps to solve the problem of photovoltaic module failure due to hot spot effect.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cells, and in particular to a back-contact photovoltaic cell and its manufacturing method, as well as a photovoltaic module. Background Technology

[0002] IBC (Interdigitated Back Contact) solar cells are solar cells with positive and negative metal electrodes arranged in an interdigitated pattern on the back side of the cell. The PN junction is located on the back of the cell. IBC cells are among the most efficient photovoltaic cells currently available. Using monocrystalline silicon as the substrate, with both the PN junction and metal electrodes located on the back, and no metal electrodes on the front blocking light, they achieve very high short-circuit current and conversion efficiency.

[0003] Photovoltaic modules, composed of multiple cells, are typically installed in open, sunny locations. Over long-term use, they inevitably accumulate obstructions such as birds, dust, and fallen leaves, creating shadows on the solar modules. In large solar module arrays, improper row spacing can also lead to mutual shadows. Due to these localized shadows, the current and voltage of some individual cells within the solar module change. This results in an increase in the product of current and voltage in certain areas of the module, leading to localized temperature increases. Defects in some individual cells can also cause localized heating during operation; this phenomenon is called the "hot spot effect."

[0004] In IBC cells, since the P-type and N-type doped regions are located on the back side of the substrate and are isolated, the hot spot effect can affect the power output of the photovoltaic module and cause safety issues due to localized temperature increases during the process of assembling multiple IBC cells into a string and then encapsulating them into a photovoltaic module. Therefore, how to improve and solve the "hot spot effect" is an urgent problem that engineers need to solve. Summary of the Invention

[0005] This application provides a back-contact photovoltaic cell and its manufacturing method, as well as a photovoltaic module, which at least helps to solve the problem of photovoltaic module failure caused by hot spot effect.

[0006] This application provides a method for manufacturing a back-contact photovoltaic cell, comprising: A substrate is provided, the substrate having opposing first and second surfaces in a second direction; wherein the second direction is the thickness direction of the substrate; An intrinsic silicon layer is formed on the first surface of the substrate, the intrinsic silicon layer comprising a first region, a spacer region, and a second region arranged sequentially along a first direction; the first direction and the second direction intersect. A mask layer is formed on the surface of the interval region and the second region facing away from the substrate; The first region is doped with a first element to form a first doped layer, and a portion of the first element diffuses into the spacer region; Remove the mask layer corresponding to the interval region and form a barrier layer on the side of the interval region away from the substrate; Remove the mask layer corresponding to the second region; The second region is doped with a second element to form a second doped layer, and a portion of the second element diffuses into the spacer region to transform the spacer region into a contact control portion, the contact control portion being electrically connected to the first doped layer and the second doped layer; A first electrode and a second electrode are formed on the first doped layer and the second doped layer, respectively.

[0007] Optionally, the method of forming the barrier layer includes converting a portion of the spacer region into the barrier layer by a thermal oxidation process, or forming the barrier layer on the side surface of the spacer region away from the substrate by a deposition process.

[0008] Optionally, in the step of doping the second region with a second element to form a second doped layer, at least a portion of the second element diffuses through the barrier layer into the spacer region.

[0009] Optionally, the material of the barrier layer includes silicon oxide.

[0010] Optionally, the thickness of the barrier layer in the second direction is 2nm to 40nm; And / or, the width of the barrier layer in the first direction is 20μm to 120μm.

[0011] Optionally, after the step of forming the first doped layer, a first doped glass layer is formed on the side of the first doped layer opposite to the substrate; After the step of forming the second doped layer, a second doped glass layer is formed on the side of the second doped layer opposite to the substrate; After the step of forming the second doped glass layer and before the step of forming the first electrode and the second electrode, the first doped glass layer, the second doped glass layer, and the barrier layer are removed.

[0012] Optionally, after the step of forming the second doped glass layer, before the step of removing the first doped glass layer, the second doped glass layer and the barrier layer, and before the step of forming the first electrode and the second electrode, the second surface is texturized.

[0013] Optionally, after texturing the second surface, a first passivation layer and a second passivation layer are sequentially formed on the second surface, the first doped layer, the second doped layer, and the side of the contact control portion facing away from the substrate.

[0014] Optionally, after providing the substrate and before forming the intrinsic silicon layer, a tunneling oxide layer is formed on the first surface.

[0015] This application also provides a back-contact photovoltaic cell, comprising: A substrate having opposing first and second surfaces in a second direction; A first doped layer, a second doped layer, and a contact control unit are sequentially disposed on the first surface along a first direction; A first electrode and a second electrode, wherein the first electrode is at least partially embedded on the surface of the first doped layer opposite to the substrate, and the second electrode is at least partially embedded on the surface of the second doped layer opposite to the substrate. The first doped layer is electrically connected to the second doped layer through the contact control unit.

[0016] This application also provides a photovoltaic module, comprising: A battery string is formed by connecting multiple back-contact photovoltaic cells, which are manufactured by the back-contact photovoltaic cell preparation method described above, or are back-contact photovoltaic cells as described above. An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

[0017] The technical solution provided in this application has at least the following advantages: This application reduces the risk of hot spots by forming a contact control section between a first doped layer and a second doped layer, wherein the contact control section contains a leakage current that electrically connects the first doped layer and the second doped layer. Attached Figure Description

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

[0019] Figure 1 A flowchart illustrating the steps of a method for manufacturing a back-contact photovoltaic cell according to an embodiment of this application is shown. Figure 2 The illustration shows a process flow diagram of the substrate provided in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application; Figure 3 A process flow diagram of forming an intrinsic silicon layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application is shown. Figure 4 A process flow diagram of forming a mask layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application is shown; Figure 5 This paper illustrates a process flow diagram of forming the first doped layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. Figure 6 The diagram illustrates a process flow chart of removing a portion of the mask layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. Figure 7 A process flow diagram of forming a barrier layer in a method for preparing a back-contact photovoltaic cell according to an embodiment of this application is shown; Figure 8 This paper illustrates a process flow diagram of removing the remaining mask layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. Figure 9 This paper illustrates a process flow diagram of forming a second doped layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. Figure 10 The diagram illustrates a process flow chart of a back-contact photovoltaic cell fabrication method provided in this application, including texturing a surface and removing the doped glass layer and barrier layer. Figure 11 The diagram illustrates a process flow chart of forming a first passivation layer and a second passivation layer in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. Figure 12The diagram illustrates the process flow for forming the first electrode and the second electrode in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application.

[0020] Explanation of reference numerals in the attached figures: 100, Substrate; 101, First surface; 102, Second surface; 200, Tunneling oxide layer; 300, Intrinsic silicon layer; 310, First region; 320, Second region; 330, Spacer region; 340, Contact control section; 400, Mask layer; 500, First doped layer; 510, First doped glass layer; 301, Barrier layer; 600, Second doped layer; 610, Second doped glass layer; 710, First passivation layer; 720, Second passivation layer; 810, First electrode; 820, Second electrode. Detailed Implementation

[0021] As is known from the background technology, existing back-contact solar cells and photovoltaic modules have a "hot spot effect," which may affect the power of photovoltaic modules and cause safety issues due to localized temperature increases.

[0022] Analysis revealed that the "hot spot effect" in current back-contact solar cells and photovoltaic modules is caused by partially shading the back-contact solar cell, which can cause the diode to enter reverse bias. This results in the diode dissipating power instead of generating power and causes the back-contact solar cell to heat up. This degrades system performance, can lead to cell breakdown, and, if hot spots are generated, can pose potential reliability risks.

[0023] This application provides a back-contact photovoltaic cell and its manufacturing method. This application forms a contact control part between a first doped layer and a second doped layer, so that the contact control part has a leakage current that electrically connects the first doped layer and the second doped layer. The leakage characteristics of the contact control part are used to reduce the risk of hot spots.

[0024] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0027] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0028] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0029] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. Furthermore, when describing a component as "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0030] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. The formation or provision of a second component above or on a first component, or on the surface of a first component, or on one side of a first component, may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be present between the first and second components, thereby preventing direct contact between the first and second components. For simplicity and clarity, various components may be drawn at different scales. In the drawings, some layers / components may be omitted for simplicity. Unless otherwise specified, the formation or provision of a second component on the surface of a first component refers to direct contact between the first and second components. The term "component" may refer to a layer, film, region, portion, structure, etc.

[0031] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0033] See Figure 1 , Figure 1 A flowchart illustrating the steps of a method for manufacturing a back-contact photovoltaic cell according to an embodiment of this application is shown. The method for manufacturing a back-contact photovoltaic cell according to an embodiment of this application includes: S10, a substrate 100 is provided, the substrate 100 having a first surface 101 and a second surface 102 opposite to each other in a second direction Y; wherein, the second direction Y is the thickness direction of the substrate; S20, an intrinsic silicon layer 300 is formed on the first surface 101 of the substrate. The intrinsic silicon layer 300 includes a first region 310, a spacer region 330 and a second region 320 arranged sequentially along a first direction X. The first direction X and the second direction Y intersect. S30, a mask layer 400 is formed on the side surface of the interval region 330 and the second region 320 facing away from the substrate; S40, the first region 310 is doped with a first element to form a first doped layer 500, and a portion of the first element diffuses into the spacer region 330; S50, remove the mask layer 400 corresponding to the interval region 330, and form a barrier layer 301 on the side of the interval region 330 away from the substrate; S60, remove the mask layer 400 corresponding to the second region 320; S70, the second region 320 is doped with a second element to form a second doped layer 600, and a portion of the second element diffuses into the spacer region 330 so that the spacer region 330 is converted into a contact control section 340, the contact control section 340 being electrically connected to the first doped layer 500 and the second doped layer 600. S80, a first electrode 810 and a second electrode 820 are formed on the first doped layer 500 and the second doped layer 600, respectively.

[0034] This application forms a contact control section 340 between the first doped layer and the second doped layer, so that the contact control section 340 has a leakage current that electrically connects the first doped layer and the second doped layer. The leakage characteristics of the contact control section 340 are used to reduce the risk of hot spots.

[0035] The embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0036] like Figure 2 As shown, Figure 2 The illustration shows a process flow diagram of a back-contact photovoltaic cell fabrication method according to an embodiment of this application, in which a substrate 100 is provided. In step S10, a substrate 100 is provided. The substrate 100 has intersecting and perpendicular first direction X, second direction Y, and third direction Z, wherein the second direction Y is the thickness direction of the substrate 100. The substrate 100 has a first surface 101 and a second surface 102 opposite to each other in the second direction Y.

[0037] In some embodiments, the substrate 100 may be made of an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be monocrystalline, polycrystalline, amorphous, or microcrystalline (a state simultaneously possessing both monocrystalline and amorphous states is called microcrystalline). For example, silicon may be at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0038] In some embodiments, the substrate 100 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium dihydrogen phosphate, perovskite, cadmium telluride, copper indium selenide, etc. The substrate 100 may also be a sapphire substrate 100, a silicon-on-insulator substrate 100, or a germanium-on-insulator substrate 100.

[0039] In some embodiments, the substrate 100 can be an N-type semiconductor substrate 100 or a P-type semiconductor substrate 100. The N-type semiconductor substrate 100 is doped with an N-type dopant element, which can be any one of group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate 100 is doped with a P-type dopant element, which can be any one of group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0040] Specifically, in this embodiment, the substrate 100 is an N-type semiconductor substrate 100.

[0041] like Figure 3 As shown, Figure 3 The diagram shows a process flow chart of forming an intrinsic silicon layer 300 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S20, an intrinsic silicon layer 300 is formed on one side surface of the substrate 100. The intrinsic silicon layer 300 has a first region 310, a spacer region 330 and a second region 320 arranged sequentially along a first direction X.

[0042] It should be noted that in this embodiment, the number of the first region 310, the interval region 330 and the second region 320 is a single one; in other embodiments, the number of the first region 310, the interval region 330 and the second region 320 is multiple, and the multiple first regions 310 and the multiple second regions 320 are arranged alternately along the first direction X, with an interval region 330 between adjacent first regions 310 and second regions 320.

[0043] In this application, the first region 310 and the second region 320 corresponding to the first doped layer 500 and the second doped layer 600 of the back contact photovoltaic cell are formed simultaneously in one step. Compared with the prior art, where the first region 310 and the second region 320 corresponding to the first doped layer 500 and the second doped layer 600 need to be formed separately in two steps, the technology of forming the intrinsic silicon layer 300 in one step in this application simplifies the product structure, simplifies the production process, and greatly reduces the production cost.

[0044] In some embodiments, the intrinsic silicon layer 300 is made of amorphous silicon.

[0045] In some embodiments, a tunneling oxide layer 200 is formed on the first surface 101 prior to the step of forming the intrinsic silicon layer 300.

[0046] In some embodiments, the material of the tunneling oxide layer 200 is silicon oxide (SiOx).

[0047] In some embodiments, in the second direction Y, the thickness of the tunneling oxide layer 200 is 1.1 nm to 1.8 nm, and the thickness of the intrinsic silicon layer 300 is 100 nm to 300 nm.

[0048] Specifically, the methods for forming the tunnel oxide layer 200 and the intrinsic silicon layer 300 include low-pressure chemical vapor deposition (LPCVD).

[0049] It should be understood that the tunneling oxide layer 200 can form band bending on the surface of the substrate 100. The tunneling oxide layer 200 causes an asymmetric shift in the energy band on the surface of the substrate 100, making the potential barrier for majority carriers (also known as majority carriers) lower than that for minority carriers (also known as minority carriers). Therefore, majority carriers can more easily tunnel through the tunneling oxide layer 200, while minority carriers have difficulty passing through the tunneling oxide layer 200, thereby achieving selective transport of carriers and improving the photoelectric conversion efficiency of the back contact photovoltaic cell of this application.

[0050] like Figure 4 As shown, Figure 4 The diagram shows a process flow chart of forming a mask layer 400 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S30, the mask layer 400 is formed on the side surface of the spacer region 330 and the second region 320 facing away from the substrate 100.

[0051] In some embodiments, the method of forming the mask layer 400 includes: patterning the entire layer of mask material using a laser processing process to form a patterned mask layer 400. Alternatively, a mask having a cutout pattern corresponding to the mask layer 400 is placed over the surface of the intrinsic silicon layer 300, and the patterned mask layer 400 is deposited within the cutouts of the mask.

[0052] In some embodiments, the material of the mask layer 400 includes at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0053] Reference Figure 5 As shown, Figure 5 This illustration shows a process flow diagram of forming a first doped layer 500 in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. In step S40, a first element is doped into the first region 310 to form the first doped layer 500. In addition to doping the first element into the first region 310, some of the first element diffuses into the spacer region 330 during the doping process.

[0054] It should be noted that, due to the doping process, side doping will occur. In addition to the first element being doped into the first region 310, the edge of the spacer region 330 near the first region 310 will be doped with the first element.

[0055] In some embodiments, after the step of forming the first doped layer 500, a first doped glass layer 510 is formed on the side surface of the first doped layer 500 facing away from the substrate 100.

[0056] Furthermore, after forming the first doped layer 500, the first doped layer 500 is subjected to crystallization treatment. The method for crystallizing the first doped layer 500 is a high-temperature annealing process.

[0057] It should be noted that the first doped glass layer 510 has a dense structure. During the crystallization process of the first doped layer 500, the first element can be prevented from escaping from the first doped layer 500 due to high temperature, thus ensuring the doping concentration of the first doped layer 500 and improving the photoelectric conversion efficiency of the back contact photovoltaic cell of this application.

[0058] In some embodiments, the first doped glass layer 510 is made of boron-containing silicon oxide (borosilicate glass, BSG).

[0059] In some embodiments, the thickness of the first doped glass layer 510 in the second direction Y is 20 nm to 140 nm.

[0060] In some embodiments, the doping concentration of the first element in the first doped layer 500 is 1E+19cm-3 to 9E+19cm-3.

[0061] Reference Figure 6 As shown, Figure 6 The diagram shows a process flow chart of removing part of the mask layer 400 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S50, the mask layer 400 corresponding to the spacer region 330 is removed so that the spacer region 330 is exposed.

[0062] In some embodiments, the method for removing a portion of the mask layer 400 includes laser etching or chemical mechanical polishing (CMP).

[0063] Reference Figure 7 As shown, Figure 7 This diagram illustrates a process flow chart of forming a barrier layer 301 in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. In step S50, the barrier layer 301 is formed on the side of the spacer region 330 facing away from the substrate 100, i.e., the barrier layer 301 covers the surface of the spacer region 330. The barrier layer 301 prevents the second element from being directly doped into the spacer region 330 during the subsequent doping of the second region 320, which would result in an excessively high concentration of the second element in the spacer region 330. This, in turn, would lead to an excessively large current in the contact control section 340 formed in the spacer region 330, causing a significant reduction in the photoelectric conversion efficiency of the back-contact photovoltaic cell.

[0064] In some embodiments, the method of forming the barrier layer 301 includes converting a portion of the spacer region 330 into the barrier layer 301 by a thermal oxidation process, or forming the barrier layer 301 on the side surface of the spacer region 330 facing away from the substrate 100 by a deposition process.

[0065] In some embodiments, the thickness of the barrier layer 301 in the second direction Y is 2nm to 40nm.

[0066] In some embodiments, the width of the barrier layer 301 in the first direction X is 20 μm to 120 μm.

[0067] Reference Figure 8 As shown, Figure 8 The diagram shows a process flow chart of removing the remaining mask layer 400 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S60, the remaining mask layer 400 is removed, that is, the mask layer 400 corresponding to the second region 320 is removed so that the second region 320 is exposed.

[0068] Reference Figure 9 As shown, Figure 9The diagram shows a process flow chart of forming a second doped layer 600 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S70, a second element is doped into the exposed second region 320 to form the second doped layer 600.

[0069] In some embodiments, the exposed second region 320 and the spacer region 330 covered by the barrier layer 301 are simultaneously subjected to a doping process of a second element.

[0070] In this process, the second element is directly injected or diffused into the exposed second region 320 to form a high-concentration second doped layer 600. Simultaneously, the second element penetrates the barrier layer 301 along the second direction Y to enter the spacer region 330. Due to the blocking effect of the barrier layer 301, the concentration of the second element entering the spacer region 330 is lower than the concentration of the second doped layer 600. At this time, the spacer region 330 transforms into a contact control section 340. In this embodiment, by adjusting the thickness of the barrier layer 301 formed in step S50, the proportion of the second element penetrating the barrier layer can be adjusted, thereby controlling the net doping concentration within the spacer region 330 and ultimately achieving precise control of the leakage current between PN junctions. The presence of the barrier layer 301 means that the doping distribution within the spacer region 330 no longer solely depends on the mask edge morphology caused by photolithography precision or etching deviation, but primarily on the thickness of the barrier layer 301. This makes the carrier concentration and resistivity within the contact control section 340 highly controllable, thereby enabling the formation of a stable and uniform leakage channel.

[0071] It should be noted that during the process of the second element penetrating the barrier layer 301 into the spacer region 330, the barrier layer 301 does not act as a completely insulating mask, but rather as a doping concentration attenuation layer. It allows a certain proportion of the second element to pass through and enter the underlying silicon substrate, but significantly reduces the surface concentration and junction depth of the second element. Therefore, a lightly doped region with a doping concentration significantly lower than that of the second doped layer 600 is formed within the spacer region 330, and this lightly doped region is transformed into the contact control section 340.

[0072] It should be noted that in actual manufacturing, for applications with no or little shading, the thickness of the barrier layer 301 can be increased to enhance the blocking effect on the second element, reduce the doping concentration in the spacer region, thereby reducing leakage current and power loss during normal operation. For high-risk areas with a large amount of shading, the thickness of the barrier layer 301 can be reduced to increase the penetration of the second element and moderately increase the leakage current to enhance the conduction capability of the bypass diode and prevent hot spot effects from damaging the component.

[0073] The contact control unit 340 realizes the shunting of opposite polarities, thereby forming a bypass diode, which can effectively balance and improve the local current and voltage of the back contact photovoltaic cell itself due to the "hot spot effect". This can improve and compensate for the problems caused by the "hot spot effect", and avoid problems in the battery string or photovoltaic module composed of multiple back contact photovoltaic cells. It can also effectively avoid the power reduction caused by the partial shading of the back contact photovoltaic cells.

[0074] In some embodiments, after the step of forming the second doped layer 600, a second doped glass layer 610 is formed on the side surface of the second doped layer 600 facing away from the substrate 100.

[0075] In some embodiments, the method of forming the second doped layer 600 includes an ion implantation process or a thermal diffusion process.

[0076] Furthermore, after forming the second doped layer 600, the second doped layer 600 is subjected to crystallization treatment. The method for crystallizing the second doped layer 600 is a high-temperature annealing process.

[0077] In some embodiments, the second doped glass layer 610 is made of phosphorus-containing silicon oxide (phosphorus silicon glass, PSG). Similar to the first doped glass layer 510, the second doped glass layer 610 has a dense structure, which prevents the second element from escaping from the second doped layer 600 due to high temperature during the crystallization process, thus ensuring the doping concentration of the second doped layer 600 and improving the photoelectric conversion efficiency of the back contact photovoltaic cell of this application.

[0078] In some embodiments, the thickness of the second doped glass layer 610 in the second direction Y is 20 nm to 140 nm. The doping concentration of the second element in the second doped layer 600 is 1E+20 cm⁻³ to 9E+21 cm⁻³.

[0079] like Figure 10 As shown, Figure 10 The diagram illustrates a process flow chart of a back-contact photovoltaic cell fabrication method according to an embodiment of this application, including surface texturing and removal of the doped glass layer and barrier layer 301. The fabrication method of the back-contact photovoltaic cell according to this embodiment further includes: Step S71: The second surface 102 of the substrate 100 is texturized to form a texturized surface.

[0080] Step S72: After texturing, the barrier layer 301, the first doped glass layer 510, and the second doped glass layer 610 covering the contact control section 340 are removed.

[0081] Before removing the barrier layer 301, the first doped glass layer 510, and the second doped glass layer 610, the second surface 102 is texturized. During the texturizing process, the barrier layer 301, the first doped glass layer 510, and the second doped glass layer 610 respectively protect the contact control unit 340, the first doped layer 500, and the second doped layer 600, preventing the texturizing solution from damaging the contact control unit 340, the first doped layer 500, or the second doped layer 600.

[0082] In some embodiments, the method for removing the barrier layer 301, the first doped glass layer 510, and the second doped glass layer 610 includes chemical mechanical polishing (CMP).

[0083] like Figure 11 As shown, Figure 11 The diagram illustrates a process flow chart of forming a first passivation layer 710 and a second passivation layer 720 in a method for fabricating a back-contact photovoltaic cell according to an embodiment of this application. The method for fabricating a back-contact photovoltaic cell according to this embodiment further includes: In step S73, a first passivation layer 710 and a second passivation layer 720 are sequentially formed on the surfaces of the second surface 102, the first doped layer 500, the contact control portion 340, and the second doped layer 600. The first passivation layer 710 and the second passivation layer 720 effectively reduce the carrier recombination rate on the surface of the first doped layer 500 or the second doped layer 600 through chemical passivation and field-effect passivation mechanisms, significantly improving minority carrier lifetime and thus enhancing the photoelectric conversion efficiency of the photovoltaic cell.

[0084] In some embodiments, the material of the first passivation layer 710 includes at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0085] In some embodiments, the material of the second passivation layer 720 includes at least one of silicon oxide, aluminum oxide, silicon nitride, or silicon oxynitride.

[0086] like Figure 12 As shown, Figure 12 The diagram shows a process flow chart of forming a first electrode 810 and a second electrode 820 in a method for preparing a back contact photovoltaic cell according to an embodiment of this application. In step S80, the first electrode 810 and the second electrode 820 are formed at corresponding positions of the first doped layer 500 and the second doped layer 600, respectively, to obtain a back contact photovoltaic cell.

[0087] The first electrode 810 passes through the second passivation layer 720 and the first passivation layer 710 in sequence and is at least partially embedded in the surface of the first doped layer 500 facing away from the substrate 100, so that the first electrode 810 is electrically connected to the first doped layer 500; the second electrode 820 passes through the second passivation layer 720 and the first passivation layer 710 in sequence and is at least partially embedded in the surface of the second doped layer 600 facing away from the substrate 100, so that the second electrode 820 is electrically connected to the second doped layer 600.

[0088] Accordingly, another embodiment of this application also provides a back-contact photovoltaic cell, which can be obtained by the manufacturing method of the back-contact photovoltaic cell provided in the above embodiments. The back-contact photovoltaic cell provided in another embodiment of this application will be described in detail below with reference to the accompanying drawings. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments; detailed descriptions will not be repeated below.

[0089] like Figure 12 As shown, the back-contact photovoltaic cell includes: a substrate 100 having a first surface 101 and a second surface 102 opposite to each other in a second direction Y; a first doped layer 500, a second doped layer 600, and a contact control unit 340, wherein the first doped layer 500, the contact control unit 340, and the second doped layer 600 are sequentially disposed on the first surface 101 along a first direction X; a first electrode 810 and a second electrode 820, wherein the first electrode 810 is at least partially embedded on the side surface of the first doped layer 500 opposite to the substrate 100, and the second electrode 820 is at least partially embedded on the side surface of the second doped layer 600 opposite to the substrate 100; wherein the first doped layer 500 is electrically connected to the second doped layer 600 through the contact control unit 340.

[0090] A first passivation layer 710 and a second passivation layer 720 are sequentially wrapped around the surfaces of the substrate 100, the first doped layer 500, the contact control part 340, and the second doped layer 600, as well as the two side surfaces shown in the figure. The back contact photovoltaic cell also includes a first electrode 810 and a second electrode 820. The first electrode 810 passes through the second passivation layer 720 and the first passivation layer 710 sequentially along the thickness direction of the substrate 100 and is then embedded in the surface of the first doped layer 500 on the side facing away from the substrate 100. The second electrode 820 passes through the second passivation layer 720 and the first passivation layer 710 sequentially along the thickness direction of the substrate 100 and is then embedded in the surface of the second doped layer 600 on the side facing away from the substrate 100.

[0091] Accordingly, another embodiment of this application also provides a photovoltaic module, which includes a battery string, an encapsulating film, and a cover plate. The battery string is formed by a plurality of back-contact photovoltaic cells, wherein the back-contact photovoltaic cells are manufactured by the method described above for preparing back-contact photovoltaic cells, or as described above; the encapsulating film covers the surface of the photovoltaic cells; the cover plate is located on the surface of the encapsulating film away from the photovoltaic cells. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments, which will not be elaborated upon below.

[0092] The encapsulating film can be made of ethylene. Organic encapsulation films such as vinyl acetate copolymer films, polyvinyl octene co-elastomer films, or polyvinyl butyral films.

[0093] The cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with light transmission function. In some embodiments, the surface of the cover plate facing the adhesive film can be an uneven surface, thereby increasing the utilization rate of incident light.

[0094] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for preparing a back-contact photovoltaic cell, characterized in that, include: A substrate (100) is provided, the substrate (100) having opposing first surfaces (101) and second surfaces (102) in a second direction; wherein the second direction is the thickness direction of the substrate; An intrinsic silicon layer (300) is formed on the first surface (101) of the substrate. The intrinsic silicon layer (300) includes a first region (310), a spacer region (330), and a second region (320) arranged sequentially along a first direction. The first direction and the second direction intersect. A mask layer (400) is formed on the side surface of the spacer region (330) and the second region (320) facing away from the substrate. The first region (310) is doped with a first element to form a first doped layer (500), and a portion of the first element diffuses into the spacer region (330); Remove the mask layer (400) corresponding to the spacer region (330) and form a barrier layer (301) on the side of the spacer region (330) away from the substrate. Remove the mask layer (400) corresponding to the second region (320); The second region (320) is doped with a second element to form a second doped layer (600), and a portion of the second element diffuses into the spacer region (330) to transform the spacer region (330) into a contact control section (340), which is electrically connected to the first doped layer (500) and the second doped layer (600). A first electrode (810) and a second electrode (820) are formed on the first doped layer (500) and the second doped layer (600), respectively.

2. The method for preparing a back-contact photovoltaic cell according to claim 1, characterized in that, The method of forming the barrier layer (301) includes converting a portion of the spacer region (330) into the barrier layer (301) by a thermal oxidation process, or forming the barrier layer (301) on the side surface of the spacer region (330) opposite to the substrate (100) by a deposition process.

3. The method for preparing a back-contact photovoltaic cell according to claim 1, characterized in that, In the step of doping the second region (320) with a second element to form a second doped layer (600), at least a portion of the second element diffuses through the barrier layer (301) into the spacer region (330) along the second direction.

4. The method for preparing a back-contact photovoltaic cell according to claim 1 or 3, characterized in that, The thickness of the barrier layer (301) in the second direction is 2nm~40nm; And / or, the width of the barrier layer (301) in the first direction is 20 μm to 120 μm; And / or, the material of the barrier layer (301) includes silicon oxide.

5. The method for preparing a back-contact photovoltaic cell according to claim 1, characterized in that, After the step of forming the first doped layer (500), a first doped glass layer (510) is formed on the side of the first doped layer (500) facing away from the substrate (100). After the step of forming the second doped layer (600), a second doped glass layer (610) is formed on the side of the second doped layer (600) away from the substrate (100). After the step of forming the second doped glass layer (610) and before the step of forming the first electrode (810) and the second electrode (820), the first doped glass layer (510), the second doped glass layer (610) and the barrier layer (301) are removed.

6. The method for preparing a back-contact photovoltaic cell according to claim 5, characterized in that, After the step of forming the second doped glass layer (610), before the step of removing the first doped glass layer (510), the second doped glass layer (610) and the barrier layer (301), and before the step of forming the first electrode (810) and the second electrode (820), the second surface (102) is texturized.

7. The method for preparing a back-contact photovoltaic cell according to claim 6, characterized in that, After texturing the second surface (102), a first passivation layer (710) and a second passivation layer (720) are sequentially formed on the second surface (102), the first doped layer (500), the second doped layer (600), and the side of the contact control portion (340) facing away from the substrate.

8. The method for preparing a back-contact photovoltaic cell according to claim 6, characterized in that, After the step of providing the substrate and before the step of forming the intrinsic silicon layer (300), a tunneling oxide layer (200) is formed on the first surface (101).

9. A back-contact photovoltaic cell, characterized in that, include: A substrate (100) having opposing first surfaces (101) and second surfaces (102) in a second direction; A first doped layer (500), a second doped layer (600), and a contact control unit (340) are sequentially disposed on the first surface (101) along a first direction. A first electrode (810) and a second electrode (820), wherein the first electrode (810) is at least partially embedded on the side surface of the first doped layer (500) away from the substrate (100), and the second electrode (820) is at least partially embedded on the side surface of the second doped layer (600) away from the substrate (100). The first doped layer (500) is electrically connected to the second doped layer (600) through the contact control unit (340).

10. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back-contact photovoltaic cells, wherein the back-contact photovoltaic cells are manufactured by the method for preparing a back-contact photovoltaic cell according to any one of claims 1 to 8, or as described in claim 9; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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