Back contact solar cells and methods of manufacture

Abstract

To provide a back contact solar battery and a manufacturing method of the same.SOLUTION: A solar battery comprises: a silicon substrate that has a front surface and a back surface that are opposite, and has a first doping type; and a first emitter, a first separation region, a second separation region, and a second emitter, that are provided on the back surface of the silicon substrate. The first and second separation regions are provided between the first and second emitters along a first direction. The first emitter has a second doping type. The first separation region and the second emitter are of the first doping type. The first direction closes a thickness direction of the silicon substrate. The solar battery and a manufacturing method solve the problem that a reverse direction electric leakage in the solar battery exceeds a reference value and a hot spot test is in fail, by providing the first and second separation regions between the first and second emitters.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application relates primarily to the field of photovoltaics, and more particularly to back-contact solar cells and methods of manufacture. [Background technology]

[0002] The electrodes of an interdigitated back contact (IBC) battery are located on the back of the battery, which reduces the shielding of the light-receiving surface of the battery and improves the battery's conversion efficiency, making it a major research and development direction for industrialized high-efficiency batteries.Currently, mass production of back contact batteries faces problems such as exceeding the reverse leakage current standard and failing hot spot tests on battery modules.

[0003] Therefore, how to solve the problem of back-contact batteries exceeding the reverse leakage current standard and battery module hot spot test failures is an issue that needs to be resolved urgently. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem to be solved by this application is to provide a back-contact solar cell and a manufacturing method thereof that can solve the problems of exceeding the reverse leakage current standard in back-contact cells and hot spot test failures in battery modules. [Means for solving the problem]

[0005] In order to solve the above technical problems, the present application provides a back-contact solar cell comprising: a silicon substrate having opposing front and back surfaces and of a first doping type; and a first emitter, a first isolation region, a second isolation region, and a second emitter provided on the back surface of the silicon substrate, the first isolation region and the second isolation region being provided between the first emitter and the second emitter along a first direction, the first emitter being of a second doping type, the first isolation region and the second emitter being of a first doping type, and the first direction intersecting a thickness direction of the silicon substrate.

[0006] In one embodiment of the present application, the first emitter, the first isolation region, the second isolation region, and the second emitter are disposed adjacent to each other in sequence on the back surface of the silicon substrate along the first direction.

[0007] In one embodiment of the present application, the first isolation region has a first side and a second side opposing each other along the first direction, the second isolation region has a third side and a fourth side opposing each other along the first direction, the first side being in contact with the first emitter, the second side being in contact with the third side, and the fourth side being in contact with the second emitter.

[0008] In one embodiment of the present application, the second isolation region is of the second doping type or the first doping type.

[0009] In one embodiment of the present application, a first portion of the second isolation region is of the first doping type and a second portion of the second isolation region is of the second doping type.

[0010] In one embodiment of the present application, the first emitter comprises a tunnel oxide layer provided on a back surface of the silicon substrate, and a polysilicon layer provided on a surface of the tunnel oxide layer facing away from the silicon substrate, the polysilicon layer being of a second doping type.

[0011] In one embodiment of the present application, the first separation region has a pyramidal pile profile.

[0012] In one embodiment of the present application, the second isolation region has a flat profile on a surface away from the silicon substrate in a thickness direction.

[0013] In one embodiment of the present application, the semiconductor device further includes a first passivation layer and an anti-reflection layer sequentially disposed on the front surface of the silicon substrate along the thickness direction.

[0014] In one embodiment of the present application, the first passivation layer comprises a chemical passivation layer provided on a front surface of the silicon substrate, and a field passivation layer provided on a surface of the chemical passivation layer facing away from the silicon substrate.

[0015] In order to solve the above technical problems, the present application further provides a method for manufacturing a back-contact solar cell, the method comprising the steps of: providing a silicon substrate having opposing front and back surfaces and of a first doping type; and forming a first emitter, a first isolation region, a second isolation region, and a second emitter on the back surface of the silicon substrate, wherein the first isolation region and the second isolation region are disposed between the first emitter and the second emitter along a first direction, the first emitter being of a second doping type, the first isolation region and the second emitter being of a first doping type, and the first direction intersecting with a thickness direction of the silicon substrate.

[0016] In one embodiment of the present application, the first emitter, the first isolation region, the second isolation region, and the second emitter are disposed adjacent to each other in sequence on the back surface of the silicon substrate along the first direction.

[0017] In one embodiment of the present application, the first isolation region has a first side and a second side opposing each other along the first direction, the second isolation region has a third side and a fourth side opposing each other along the first direction, the first side being in contact with the first emitter, the second side being in contact with the third side, and the fourth side being in contact with the second emitter.

[0018] In one embodiment of the present application, the first emitter comprises a tunnel oxide layer provided on a back surface of the silicon substrate, and a polysilicon layer provided on a surface of the tunnel oxide layer facing away from the silicon substrate, the polysilicon layer being of a second doping type.

[0019] In one embodiment of the present application, the first isolation region has a pyramidal pile profile, and a method for forming the pyramidal pile profile includes etching a surface of the first isolation region facing away from the silicon substrate using an alkaline solution.

[0020] In one embodiment of the present application, the second isolation region is of the second doping type or the first doping type.

[0021] In one embodiment of the present application, a first portion of the second isolation region is of the first doping type and a second portion of the second isolation region is of the second doping type.

[0022] In one embodiment of the present application, the second isolation region has a flat profile on a surface away from the silicon substrate in a thickness direction.

[0023] In one embodiment of the present application, the method further comprises sequentially forming a first passivation layer and an anti-reflection layer on the front surface of the silicon substrate along the thickness direction. [Effects of the Invention]

[0024] The back-contact solar cell and manufacturing method of the present application solves the problem of the solar cell's reverse leakage exceeding the standard value and failing the hot spot test by providing a first isolation region and a second isolation region between the first emitter and the second emitter.

[0025] In order to make the above objects, features and advantages of the present application more clearly and comprehensibly understood, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a cross-sectional schematic diagram of a back contact solar cell according to an embodiment of the present application. [Figure 2] 2 is an enlarged schematic view of the dashed rectangular frame of the back contact solar cell in FIG. 1. [Figure 3] 1 is a partial cross-sectional enlarged schematic view of a back contact solar cell according to an embodiment of the present application; [Figure 4] 2 is a partial cross-sectional enlarged schematic view of a back contact solar cell according to another embodiment of the present application; [Figure 5] 1 is an exemplary flow chart of a method for manufacturing a back contact solar cell according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to make the above objects, features and advantages of the present application more clearly and comprehensibly understood, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0028] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application; however, the present application may also be practiced in other ways other than those described herein, and therefore the present application is not limited to the specific embodiments disclosed below.

[0029] As set forth in this application and the claims, unless the context clearly indicates otherwise, terms such as "a," "one," "one," "a kind," and / or "the" do not specifically refer to the singular but may also include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and do not constitute an exclusive list of these steps and elements; a method or apparatus may include other steps or elements.

[0030] It should also be noted that the use of terms such as "first" and "second" to define components is merely to facilitate distinguishing between corresponding components, and that unless otherwise stated, the terms do not have any special meaning and therefore should not be understood as limiting the scope of protection of the present application. Furthermore, although the terms used in the present application are selected from well-known terms, some terms described in the specification of the present application have been selected by the applicant at his / her own discretion, and their detailed meanings will be explained in the relevant parts of the description of this specification. It is also required to understand the present application not only by the actual terms used but also by the meanings contained in each term.

[0031] Flowcharts are used herein to describe operations performed by systems according to embodiments of the present application. It will be understood that the operations described above or below are not necessarily intended to be performed in exact order. In contrast, various steps may be reversed in order or processed simultaneously. Alternatively, other steps may be added to these processes, or one or more steps may be deleted from these processes.

[0032] Next, the solar cell and the manufacturing method of the present invention will be described with reference to specific embodiments.

[0033] 1 is a cross-sectional schematic diagram of a back contact solar cell according to one embodiment of the present application. As shown in FIG. 1, the back contact solar cell 100 includes a silicon substrate 110, a first passivation layer 120, an anti-reflective layer 130, a first emitter 140, a first isolation region 150, a second isolation region 160, and a second emitter 170.

[0034] Specifically, as shown in FIG. 1 , the silicon substrate 110 has a front surface and a back surface that face each other in a thickness direction D2. Here, the “front surface” refers to the surface of the silicon substrate 110 that receives light during solar cell operation. The first passivation layer 120 is disposed on the front surface of the silicon substrate 110 along the thickness direction D2, and the anti-reflection layer 130 is disposed on the surface of the first passivation layer 120 that faces away from the silicon substrate 110 along the thickness direction D2. The first passivation layer 120 can reduce carrier recombination at the front surface of the silicon substrate 110 and improve the efficiency of the solar cell. The anti-reflection layer 130 can reduce reflection of incident light and enhance the solar cell's absorption of the incident light. In some embodiments, the first passivation layer 120 includes one or more of alumina, silicon oxide, and silicon oxynitride, and the anti-reflection layer 130 includes silicon nitride.

[0035] In one embodiment, the first passivation layer 120 comprises a chemical passivation layer (not shown) and a field passivation layer (not shown). The chemical passivation layer is disposed on the front surface of the silicon substrate 110, the field passivation layer is disposed on the side of the chemical passivation layer facing away from the silicon substrate 110, and the anti-reflection layer 130 is disposed on the side of the field passivation layer facing away from the silicon substrate 110. The chemical passivation layer can saturate defects at the surface of the silicon substrate 110 and reduce the defect concentration, thereby reducing recombination centers in the bandgap and ultimately improving the efficiency of the solar cell. The field passivation layer can create an electrostatic field at the interface through charge accumulation, thereby reducing the minority carrier concentration and improving the efficiency of the solar cell.

[0036] 1, in some embodiments, the front surface of the silicon substrate 110, and the first passivation layer 120 and the anti-reflection layer 130 disposed on the front surface have a pyramidal pile profile. During operation of the solar cell, sunlight enters the silicon substrate 110 from the front side of the silicon substrate 110, and the pyramidal pile profile can trap the light and reduce surface reflection, thereby improving the light utilization efficiency of the solar cell.

[0037] The silicon substrate 110 of the present application is of a first doping type, and the doping type may be P-type, i.e., the silicon substrate 110 may be a P-type silicon substrate. Alternatively, the doping type may be P-type, i.e., the silicon substrate 110 may be an N-type silicon substrate. The present application does not limit the specific doping elements forming the P-type and N-type.

[0038] Continuing with FIG. 1 , first emitter 140, first isolation region 150, second isolation region 160, and second emitter 170 are sequentially and adjacently disposed on the back surface of silicon substrate 110 along a first direction D1 intersecting thickness direction D2. Referring to FIG. 2 , a partially enlarged schematic diagram of the back-contact solar cell of FIG. 1 enclosed within a dashed rectangular frame is shown. First isolation region 150 has first and second sides 151 and 152 opposing each other along first direction D1. Second isolation region 160 has third and fourth sides 161 and 162 opposing each other along first direction D1. First side 151 abuts first emitter 140, second side 152 abuts third side 161, and fourth side 162 abuts second emitter 170. The positional relationship between the first emitter 140, the first isolation region 150, the second isolation region 160, and the second emitter 170 is not limited to the embodiment of Figure 1. For example, in other embodiments, the first isolation region 150 and the second isolation region 160 are arranged between the first emitter 140 and the second emitter 170 so as not to contact each other, or the first isolation region 150 and the second isolation region 160 are arranged so as to contact each other, but the first isolation region 150 does not contact the first emitter 140, and the second isolation region 160 does not contact the second emitter 170. The first emitter 140 is of a second doping type, the first isolation region 150 and the second emitter 170 are of a first doping type, and the second isolation region 160 is of either the second doping type or the first doping type, or alternatively, a first portion of the second isolation region 160 is of the first doping type and a second portion of the second isolation region 160 is of the second doping type. The doping type of the second isolation region 160 is described below. The second doping type and the first doping type are of opposite polarity; i.e., if the first doping type is P-type, the second doping type is N-type, and vice versa.

[0039] Figure 2 is an enlarged schematic diagram of a portion of the back-contact solar cell within the dashed rectangular frame in Figure 1. As shown in Figure 2, the first emitter 140 includes a tunnel oxide layer 141 and a polysilicon layer 142. The tunnel oxide layer 141 is disposed on the back surface of the silicon substrate 110, and the polysilicon layer 142 is disposed on the surface of the tunnel oxide layer 141 facing away from the silicon substrate 110. The polysilicon layer 142 has a second doping type, that is, the doping type of the polysilicon layer 142 is opposite in polarity to the doping type of the silicon substrate 110.

[0040] In some embodiments, the tunnel oxide layer 141 has a thickness of 1 to 20 nm, and the polysilicon layer 142 has a thickness of 20 to 1000 nm. The tunnel oxide layer 141 can be silica. The tunnel oxide layer 141 and the polysilicon layer 142 can achieve selective collection of carriers, i.e., majority carriers easily pass through the tunnel oxide layer 141, while minority carriers have difficulty passing through the tunnel oxide layer 141.

[0041] Next, the doping types of the first and second isolation regions of the present application will be described. As shown in FIGS. 2, 3, and 4, unless otherwise specified, the same symbols have the same meanings in FIGS. 2, 3, and 4. In FIG. 2, the first isolation region 150 is of a first doping type, and all of the second isolation regions 160 are of a second doping type. As shown in FIG. 3, the first isolation region 150 and the second isolation region 160 are adjacent to each other along the first direction D1. Unlike FIG. 2, a first portion of the second isolation region 160 (designated 161 in FIG. 3) is of the first doping type, and a second portion of the second isolation region 160 (designated 162 in FIG. 3) is of the second doping type. Note that the relative positional relationship between the first portion 161 and the second portion 162 is not limited to that shown in FIG. 3. For example, the second portion 162 may be located to the left of the first portion 161, and the proportion (volume ratio or mass ratio) of the first portion 161 in the second separation region 160 and the proportion (volume ratio or mass ratio) of the second portion 162 in the second separation region 160 are not limited to those shown in FIG. 3 . In other words, if the proportion of the first portion 161 in the second separation region 160 is x, x may be any value greater than 0% and less than 100%, and the proportion of the second portion 162 may be 100%-x. Due to objective reasons such as the manufacturing process, the second separation region 160 may include a portion that is neither the first doping type nor the second doping type. In such a case, the proportion of the second portion 162 is less than 100%-x. Referring to FIG. 4 , what differs from FIGS. 2 and 3 is that the entire second separation region 160 in FIG. 4 is the first doping type. To more clearly understand the first and second isolation regions in the back contact solar cell of the present application, the formation process of the first and second isolation regions and the position and composition of the first and second isolation regions will be described here.

[0042] As shown in FIG. 2, the tunnel oxide layer 141 and the polysilicon layer 142 cover a portion of the back surface of the silicon substrate 110. The tunnel oxide layer 141 and the polysilicon layer 142 that partially cover the back surface of the silicon substrate 110 are formed as follows: A tunnel oxide layer 141 that covers the entire back surface of the silicon substrate 110 is formed on the back surface of the silicon substrate 110. Next, a polysilicon layer 142 that covers the entire tunnel oxide layer 141 is formed on the surface of the tunnel oxide layer 141. Next, an etching process is used to remove unnecessary tunnel oxide layer 141 and polysilicon layer 142, leaving the tunnel oxide layer 141 and polysilicon layer 142 corresponding to the first emitter 140. When the polysilicon layer 142 in the second isolation region 160 is left as shown in FIG. 1, the entire second isolation region 160 is of the second doping type as shown in FIG. 2. 3, when a portion of the polysilicon layer 142 in the second isolation region 160 is left, a first portion 161 in the second isolation region 160 is of the first doping type, and a second portion 162 in the second isolation region 160 is of the second doping type, as shown in Fig. 3. When the entire polysilicon layer 142 in the second isolation region 160 is removed, the entire second isolation region 160 is of the first doping type, as shown in Fig. 4. Note that the above-described embodiments are merely exemplary cases for forming the first isolation region and the second isolation region, and the method for forming the first isolation region and the second isolation region in the present application is not limited to the above-described embodiments.

[0043] In one embodiment, as shown in FIG. 2, the first isolation region 150 has a pyramidal pile profile. In this embodiment, the pyramidal pile profile of the first isolation region 150 and the pyramidal pile profile on the front surface of the silicon substrate 110 are formed in the same pile process step. Therefore, the separation process steps for forming the first isolation region and the second isolation region may be merged with the pile process step, simplifying the process. Also, as shown in FIG. 2, the pyramidal pile profile of the first isolation region 150 has protrusions of different sizes due to the pile process step itself. In another embodiment, the second isolation region 160 has a flat profile on the surface away from the silicon substrate 110 along the thickness direction D2. This flat profile can be achieved by chemical mechanical polishing (CMP).

[0044] Returning to FIG. 1 , in one embodiment, the solar cell 100 further includes a second passivation layer 180. As shown in FIG. 2 , the second passivation layer 180 is provided on the surfaces of the first emitter 140, the first isolation region 150, and the second isolation region 160 that face away from the silicon substrate 110. In some embodiments, the second passivation layer is one or more of silicon nitride, alumina, titanium oxide, silicon oxide, and silicon nitride. In FIG. 1 , for the second passivation layer 180 formed on the surface of the first isolation region 150 that faces away from the silicon substrate 110, because the first isolation region 150 has a pyramidal pile profile, the second passivation layer 180 deposited on the first isolation region 150 also has a pyramidal pile profile.

[0045] 1 and 2, one side of the second isolation region 160 in the first direction D1 is adjacent to the first isolation region 150, and the other side is adjacent to the second emitter 170. The second emitter 170 is in contact with the silicon substrate 110 and has the same doping type as the silicon substrate 110, that is, the first doping type. In some embodiments, the doping concentration of the second emitter 170 is greater than the doping concentration of the silicon substrate 110.

[0046] Based on the above description of the first emitter, the first isolation region, the second isolation region, and the second emitter, the functions of the first isolation region and the second isolation region will now be described.

[0047] As shown in Figure 2, as described above, a polysilicon layer 142 is formed on the back surface of the silicon substrate 110 to form the first emitter 140. If the polysilicon layer 142 formed on the back surface of the silicon substrate 110 is not removed, the polysilicon layer 142 will be present in the dashed-line frames A and B in Figure 2. As a result, the polysilicon layer 142 between the first emitter 140 and the second emitter 170 will communicate with each other. This will cause the reverse leakage current in the solar cell to exceed the reference value, and the solar cell module comprising that solar cell will fail the hot spot test.

[0048] 1 , in one embodiment, the solar cell 100 further includes a first electrode 190 and a second electrode 210. One end of the first electrode 190 contacts the polysilicon layer 142 in the first emitter 140 via the second passivation layer 180, and one end of the second electrode 210 contacts the second emitter 170 via the second passivation layer 180. The other end of the first electrode 190 and the other end of the second electrode 210 may be connected to an external device.

[0049] The solar cell in the above-described embodiment of the present application solves the problems of the solar cell exceeding the reverse leakage current standard and failing the hot spot test by providing a first isolation region and a second isolation region between the first emitter and the second emitter.

[0050] Another aspect of the present application provides a method for manufacturing a back contact solar cell. Reference is made to an exemplary flowchart of a method for manufacturing a back contact solar cell according to an embodiment of the present application shown in Figure 5. The manufacturing method in this embodiment includes the following steps:

[0051] Step S310: Provide a silicon substrate having an opposing front and back surfaces and of a first doping type.

[0052] Step S320: Form a first emitter, a first isolation region, a second isolation region, and a second emitter on the back surface of the silicon substrate, where the first isolation region and the second isolation region are disposed between the first emitter and the second emitter in a first direction, the first emitter is of a second doping type, the first isolation region and the second emitter are of a first doping type, and the first direction intersects with the thickness direction of the silicon substrate.

[0053] The above-mentioned steps S310 and S320 will be specifically described below with reference to FIGS.

[0054] In step S310, a silicon substrate 110 having a first doping type is provided. Preferably, the silicon substrate 110 is single-crystal silicon. The silicon substrate 110 has a front surface and a back surface opposite each other along a thickness direction D2.

[0055] In step S320, a first emitter 140, a first isolation region 150, a second isolation region 160, and a second emitter 170 are formed on the back surface of the silicon substrate 110, and the first isolation region 150 and the second isolation region 160 are arranged between the first emitter 140 and the second emitter 170 along a first direction D1, and the first direction D1 intersects with the thickness direction D2 of the silicon substrate.

[0056] As shown in FIG. 2, in one embodiment, a first side 151 of the first isolation region 150 is in contact with the first emitter 140, a second side 152 of the first isolation region 150 is in contact with a third side 161 of the second isolation region 160, and a fourth side 162 of the second isolation region 160 is in contact with the second emitter 170.

[0057] Furthermore, the first emitter 140 is of the second doping type, the first isolation region 150 and the second emitter 170 are of the first doping type, and the second isolation region 160 is of the second doping type or the first doping type, or the second isolation region 160 of the first portion is of the first doping type and the second isolation region 160 of the second portion is of the second doping type.

[0058] In one embodiment, the first emitter 140 includes a tunnel oxide layer 141 and a polysilicon layer 142. As shown in FIG. 2, the tunnel oxide layer 141 is disposed on the back surface of the silicon substrate 110, and the polysilicon layer 142 is disposed on the surface of the tunnel oxide layer 141 facing away from the silicon substrate 110. Here, the polysilicon layer 142 is of a second doping type, and the tunnel oxide layer 141 has a thickness of 1 to 20 nm, while the polysilicon layer has a thickness of 20 to 1000 nm. The tunnel oxide layer 141 may be silica. The tunnel oxide layer 141 and the polysilicon layer 142 can achieve selective collection of carriers, i.e., majority carriers easily pass through the tunnel oxide layer 141, while minority carriers have a hard time passing through the tunnel oxide layer 141.

[0059] 1, a first passivation layer 120 and an anti-reflective layer 130 are sequentially formed on the surface of a silicon substrate 110 along a thickness direction D2. The first passivation layer 120 and the anti-reflective layer 130 are formed by chemical vapor deposition (CVD) and / or physical vapor deposition (PVD). In some embodiments, the first passivation layer 120 comprises a chemical passivation layer and a field passivation layer, and when forming the first passivation layer 120, the chemical passivation layer is first formed on the front surface of the silicon substrate 110, and then the field passivation layer is formed on the surface of the chemical passivation layer that faces away from the silicon substrate 110.

[0060] In one embodiment, the first isolation region 150 has a pyramidal pile profile. Forming the pyramidal pile profile comprises etching the surface of the first isolation region 150 away from the silicon substrate 110 using an alkaline solution. In one embodiment, the pyramidal pile profile of the first isolation region 150 and the pyramidal pile profile on the front surface of the silicon substrate 110 are formed in the same pile fabrication step, thereby simplifying the process. In another embodiment, the second isolation region 160 has a flat profile on the surface away from the silicon substrate 110 along the thickness direction D2. This flat profile can be achieved by chemical mechanical polishing (CMP).

[0061] For further details of the method for manufacturing a back contact solar cell of the present application, please refer to the description of the back contact solar cell above, and a detailed description will not be given here. The manufacturing method of the present application solves the problems of the solar cell exceeding the reverse leakage current standard and failing the hot spot test by providing a first isolation region and a second isolation region between the first emitter and the second emitter.

[0062] Although the basic concepts have been described above, it will be apparent to those skilled in the art that the above disclosure is merely illustrative and not limiting of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to the present application. Such modifications, improvements, and amendments are proposed herein and therefore fall within the spirit and scope of the exemplary embodiments of the present application.

[0063] At the same time, the present application uses specific terms to describe embodiments of the present application. For example, "one embodiment," "one embodiment," and / or "some embodiments" refer to features, configurations, or characteristics associated with at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment," "one embodiment," or "one alternative embodiment" mentioned more than once in different places in this specification do not necessarily refer to the same embodiment. Furthermore, some features, configurations, or characteristics in one or more embodiments of the present application may be combined as appropriate.

[0064] In some embodiments, numbers describing the number of components or attributes are used; however, it should be understood that the numbers describing such embodiments are, in some instances, modified using the modifiers "about," "approximately," or "approximately." Unless otherwise specified, "about," "approximately," or "approximately" means that the numerical value can vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations, and these approximations may vary depending on the characteristics required for particular embodiments. In some embodiments, the numerical parameters should be calculated using a given number of significant digits and ordinary methods of conserving digits. In some embodiments, the numerical fields and parameters used to determine the breadth of their ranges are approximations; however, in certain embodiments, such numerical values ​​are set as precisely as possible within the limits of their possible values. [Explanation of symbols]

[0065] 110 Silicon substrate 120 First passivation layer 130 Anti-reflection layer 140 First Emitter 141 Tunnel oxide layer 142 Polysilicon layer 150 1st separation area 160 2nd separation area 170 Second Emitter 180 Second passivation layer 190 1st electrode 210 2nd electrode

Claims

1. a silicon substrate having opposing front and back surfaces, the silicon substrate being of a first doping type; a first emitter, a first isolation region, a second isolation region, and a second emitter, which are provided adjacent to each other in sequence on a back surface of the silicon substrate along a first direction; the front surface of the silicon substrate has a pyramidal pile profile; the first emitter comprises a tunnel oxide layer and a polysilicon layer; a surface of the first isolation region facing away from the silicon substrate has a pyramidal pile profile; a surface of the second isolation region that faces away from the silicon substrate has a flat profile; the first isolation region and the second isolation region are provided between the first emitter and the second emitter along the first direction, the first emitter is of a second doping type; the first isolation region and the second emitter are of a first doping type; the second isolation region is of the second doping type; the first isolation region has a first side and a second side opposing each other along the first direction; the second isolation region has a third side and a fourth side facing each other along the first direction, the first side abuts the first emitter, the second side abuts the third side, and the fourth side abuts the second emitter; The back-contact solar cell, wherein the first direction intersects with a thickness direction of the silicon substrate.

2. the tunnel oxide layer is disposed on the back surface of the silicon substrate; the polysilicon layer is provided on a surface of the tunnel oxide layer away from the silicon substrate; 2. The solar cell of claim 1, wherein the polysilicon layer is of a second doping type.

3. The solar cell of claim 1 , further comprising a first passivation layer and an anti-reflection layer sequentially disposed on the front surface of the silicon substrate along the thickness direction.

4. The first passivation layer comprises: a chemical passivation layer on the front side of the silicon substrate; 4. The solar cell according to claim 3, further comprising: a field passivation layer provided on a surface of the chemical passivation layer that faces away from the silicon substrate.

5. providing a silicon substrate having opposing front and back surfaces and being of a first doping type; forming a first emitter, a first isolation region, a second isolation region, and a second emitter adjacent to each other in sequence on the back surface of the silicon substrate along a first direction; the front surface of the silicon substrate has a pyramidal pile profile; the first emitter comprises a tunnel oxide layer and a polysilicon layer; a surface of the first isolation region away from the silicon substrate has a pyramid pile profile, and the pyramid pile profile of the first isolation region and the pyramid pile profile on the front surface of the silicon substrate are formed in the same pile manufacturing process; a surface of the second isolation region that faces away from the silicon substrate has a flat profile; the first isolation region and the second isolation region are provided between the first emitter and the second emitter along the first direction, the first emitter is of a second doping type; the first isolation region and the second emitter are of a first doping type; the second isolation region is of the second doping type; the first isolation region has a first side and a second side opposing each other along the first direction; the second isolation region has a third side and a fourth side facing each other along the first direction, the first side abuts the first emitter, the second side abuts the third side, and the fourth side abuts the second emitter; The method for manufacturing a back contact solar cell, wherein the first direction intersects with a thickness direction of the silicon substrate.

6. the tunnel oxide layer is disposed on the back surface of the silicon substrate; the polysilicon layer is provided on a surface of the tunnel oxide layer away from the silicon substrate; 6. The method of claim 5, wherein the polysilicon layer is of a second doping type.

7. 6. The method of claim 5, wherein forming the pyramidal pile profile of the first isolation region comprises etching a surface of the first isolation region facing away from the silicon substrate using an alkaline solution.

8. The method of claim 5, further comprising sequentially forming a first passivation layer and an anti-reflection layer on the front surface of the silicon substrate along the thickness direction.

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