Solar cell and method for manufacturing a solar cell

Abstract

The application provides a solar cell and a preparation method thereof, and relates to the technical field of photovoltaics. The solar cell comprises a silicon substrate with opposite first and second surfaces; a first doped layer and a first passivation layer arranged in sequence on the first surface; a second doped layer and a second passivation layer arranged in sequence on the second surface, the doping type of the first doped layer being opposite to the doping type of the second doped layer; and a first electrode and a second electrode electrically connected with the first doped layer and the second doped layer respectively, wherein (i) the first electrode is located between the first doped layer and the first passivation layer, and a part of the first electrode protrudes from one side surface of the solar cell, and / or (ii) the second electrode is located between the second doped layer and the second passivation layer, and a part of the second electrode protrudes from the other side surface of the solar cell.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the field of photovoltaic technology, and particularly relates to a solar cell and a preparation method of the solar cell. BACKGROUND

[0002] An electrode is one of important components of a solar cell, which is generally formed by a screen printing or electroplating process. The existing electrode and preparation method have the following disadvantages: firstly, the electrode has a large area of light blocking; secondly, the material of the electrode is mostly silver, and the existing electrode has a high consumption of silver; thirdly, the width of the existing electrode is wide, and the electrode is located at the outermost side of the solar cell, resulting in poor aesthetic appearance of the solar cell; and finally, the existing electrode usually needs to be interconnected with an adjacent solar cell through a solder ribbon, and the series welding increases additional processes and material costs. How to solve the above problems is one of hot researches in the field. SUMMARY

[0003] The present application aims to provide a solar cell and a preparation method of the solar cell, which improve the aesthetic appearance of the solar cell, reduce the light blocking of the electrode and the cost of the electrode, and save the solder ribbon and the series welding process.

[0004] The present application provides a solar cell, which comprises: a silicon substrate having opposite first and second surfaces; a first doped layer and a first passivation layer arranged in sequence on the first surface; a second doped layer and a second passivation layer arranged in sequence on the second surface, the doping type of the first doped layer being opposite to the doping type of the second doped layer; and a first electrode and a second electrode electrically connected with the first doped layer and the second doped layer respectively, wherein (i) the first electrode is located between the first doped layer and the first passivation layer, and a part of the first electrode protrudes from one side surface of the solar cell, and / or (ii) the second electrode is located between the second doped layer and the second passivation layer, and a part of the second electrode protrudes from another side surface of the solar cell.

[0005] The application further provides a preparation method of a solar cell, comprising: providing a silicon substrate, the silicon substrate having opposite first and second surfaces; sequentially forming a first doped layer and a first passivation layer on the first surface; sequentially forming a second doped layer and a second passivation layer on the second surface, the first doped layer and the second doped layer being of opposite doping types; forming a first electrode electrically connected to the first doped layer before forming the first passivation layer; and forming a second electrode electrically connected to the second doped layer before forming the second passivation layer, wherein (i) the first electrode is located between the first doped layer and the first passivation layer, and a portion of the first electrode protrudes from one side surface of the solar cell, and / or (ii) the second electrode is located between the second doped layer and the second passivation layer, and a portion of the second electrode protrudes from another side surface of the solar cell.

[0006] The application further provides a solar cell string, comprising: (i) a plurality of the solar cell as described above and / or a plurality of the solar cell prepared by the preparation method of the solar cell as described above; or (ii) at least one of the solar cell as described above and at least one of the solar cell prepared by the preparation method of the solar cell as described above; wherein in two adjacent solar cells, a portion of the first electrode protruding from the side surface of one solar cell is in contact with a portion of the second electrode protruding from the side surface of the other solar cell.

[0007] The technical scheme of the application has the following technical effects:

[0008] (1) The adjacent solar cells are connected in series through the protruding portions, and no solder strip is needed for series connection, thereby saving the solder strip and the series connection process.

[0009] (2) Compared with the electrode (for example, the electrode prepared by a screen printing process or the electrode prepared by an electroplating process) in the prior art, the projection width and the pitch of the metal wire are small, which not only improves the appearance, but also reduces the shielding of the incident light by the electrode and reduces the cost of the electrode. BRIEF DESCRIPTION OF DRAWINGS

[0010] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application, illustrate embodiments of the application, and together with the description serve to explain the principle of the application. In the drawings:

[0011] Figure 1 is a top view of a solar cell in an embodiment of the application;

[0012] Figure 2 is a sectional view of the solar cell in FIG. 1 along line A-A;

[0013] Figure 3 is a sectional view of a solar cell in an embodiment of the present application;

[0014] Figure 4 is a scanning electron microscope image of a metal screen in an embodiment of the present application;

[0015] Figure 5 is a sectional view of a solar cell in an embodiment of the present application;

[0016] Figure 6 is a sectional view of a solar cell in an embodiment of the present application;

[0017] Figure 7 is a flowchart of a method for manufacturing a solar cell in an embodiment of the present application;

[0018] Figure 8 is a sectional view of a solar cell intermediate in a step of a method for manufacturing a solar cell in an embodiment of the present application;

[0019] Figure 9 is a schematic view of two solar cells located in the same string and adjacent to each other in an embodiment of the present application.

[0020] Reference signs: silicon substrate 110, first surface 111, second surface 112, first doped layer 120, first passivation layer 130, second passivation layer 150, first electrode 160, first protrusion 161, second electrode 170, second doped layer 140, second protrusion 171, third passivation layer 180, tunneling layer 190, third doped layer 210, first solar cell 220, second solar cell 230. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and for those skilled in the art, the present application can also be applied to other similar scenarios without creative labor on the basis of these drawings. Unless the context clearly indicates otherwise or otherwise stated, the same reference signs in the drawings represent the same structure or operation.

[0022] As shown in the present application, unless the context clearly indicates otherwise or otherwise stated, the words "one", "a", "an", and / or "the" do not specifically refer to the singular, but also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.

[0023] The foregoing is a summary and thus contains only the most basic embodiment. The application can be practiced with the specific embodiments and options described herein, and it can also be practiced without such specific embodiments and options. Furthermore, the foregoing summary should not limit the scope of the application to a single feature or option described herein. Accordingly, no single feature or option is a requisite for a practice of the application. Unless otherwise specifically explained herein, the relative arrangements of parts, sequences of processes, numerical expressions, and values stated in these embodiments are not meant to limit the scope of the present application. Also, it is understood that the dimensions of the various parts shown in the drawings are not drawn to scale. Techniques, methods, and devices known to those of ordinary skill can not be discussed in detail because such can be found in the literature. In all examples shown and discussed herein, any specific value should be interpreted as merely an example, and not a limitation. Thus, other examples of the exemplary embodiments can have different values. It is noted that like numbers and letters refer to like elements throughout the several views of the drawings and no further discussion will be provided for these elements as they are understood to be the same as discussed previously.

[0024] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "up", "down", "left", "right", "lateral", "vertical", "horizontal", and "top", "bottom" are generally based on the orientation or positional relationships shown in the drawings, and are merely for convenience of description and simplification of description, and do not indicate or imply that the devices or components referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the scope of the present application. The orientation terms "inner", "outer" refer to the inner and outer relative to the contour of the components themselves.

[0025] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper", and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the devices described in the drawings. For example, if the devices in the drawings are inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0026] Furthermore, it needs to be explained that the use of the words "first", "second" and the like is merely intended to distinguish corresponding parts for the sake of convenience, and the above words do not have special meanings unless otherwise stated, and therefore should not be understood as limiting the scope of protection of the present application. In addition, although the terms used in the present application are selected from commonly known terms, some terms mentioned in the description of the present application can be selected by the applicant according to his or her judgment, and the detailed meanings thereof are described in the relevant part of the description. In addition, the present application is required to be understood not only by the actual terms used, but also by the meaning implied by each term.

[0027] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in sequence. On the contrary, various steps can be processed in reverse order or simultaneously. Meanwhile, or other operations are added to these processes, or one or more steps of operations are removed from these processes.

[0028] Next, the solar cell and the method for manufacturing a solar cell of the present application will be described through specific embodiments.

[0029] Reference Figure 1 and Figure 2 , Figure 2 is Figure 1 A cross-sectional view of the solar cell in the solar cell along the A-A line. The solar cell includes a silicon substrate 110, a first doped layer 120, a first passivation layer 130, a second doped layer 140, a second passivation layer 150, a first electrode 160, and a second electrode 170. In detail, the silicon substrate 110 has a first surface 111 and a second surface 112 opposite in a first direction D1 (i.e., the thickness direction of the silicon substrate 110), the silicon substrate 110 includes N-type single crystal silicon or P-type single crystal silicon, and the first surface 111 and / or the second surface 112 can have a pyramid texture structure. During operation of the solar cell, the first surface 111 or the second surface 112 faces the sun.

[0030] The first doped layer 120 is disposed on the first surface 111, and the first passivation layer 130 is disposed on the first doped layer 120. The first doped layer 120 has an N-type or P-type doping type, and can include N-type doped silicon or P-type doped silicon. The first passivation layer 130 can include silicon nitride (SiNx) and / or silicon oxynitride (SiOxNy).

[0031] In the first direction D1, the first electrode 160 is located between the first doped layer 120 and the first passivation layer 130, the first electrode 160 is in contact with the first doped layer 120 to form an electrical connection with the first doped layer 120, and a portion of the first electrode 160 is embedded in the first doped layer 120.

[0032] The second doped layer 140 is disposed on the second surface 112, and the second passivation layer 150 is disposed on the second doped layer 140. The second doped layer 140 is of N-type or P-type, and can include N-type doped silicon or P-type doped silicon. The second doped layer 140 is of the opposite type to the first doped layer 120.

[0033] In the first direction D1, the second electrode 170 is between the second doped layer 140 and the second passivation layer 150, and contacts the second doped layer 140 to form an electrical connection therewith. A portion of the second electrode 170 is embedded in the second doped layer 140.

[0034] Reference Figure 1 and Figure 2 In the second direction D2, a portion of the first electrode 160 protrudes from one side of the solar cell. For ease of description, in the drawings, the portion of the first electrode 160 protruding from one side of the solar cell is marked as a first protruding portion 161. Similarly, in the second direction D2, a portion of the second electrode 170 protrudes from the other side of the solar cell. For ease of description, in the drawings, the portion of the second electrode 170 protruding from one side of the solar cell is marked as a second protruding portion 171.

[0035] From Figure 2 the first protruding portion 161 and the second protruding portion 171 are not connected to the electrodes to which they belong, because Figure 2 is a cross-sectional view. In reality, as shown in Figure 1 , the first protruding portion 161 is in contact with the other portion of the first electrode 160 to form an electrical connection, and the second protruding portion 171 is in contact with the other portion of the second electrode 170 to form an electrical connection.

[0036] In Figure 1 and Figure 2 , the solar cell has both the first protruding portion 161 and the second protruding portion 171. Referring to Figure 3 , in an embodiment, the solar cell can have only the first protruding portion 161, and correspondingly, the second electrode 170 is a conventional solar cell electrode, i.e., the second electrode 170 penetrates the second passivation layer 150 in the first direction D1 and is in contact with the second doped layer 140. Similarly, in another embodiment, the solar cell can have only the second protruding portion 171, and correspondingly, the first electrode 160 is a conventional solar cell electrode, i.e., the first electrode 160 penetrates the first passivation layer 130 in the first direction D1 and is in contact with the first doped layer 120.

[0037] In the present application, at least one electrode is disposed between the passivation layer and the doped layer, rather than being exposed at the outermost side of the solar cell, and a portion of the electrode (i.e. the protruding portion) protrudes from the side of the solar cell. Through the above structure, not only the aesthetic appearance of the solar cell can be improved, but also a connection mode is provided, in which the protruding portion is electrically connected to the outside (e.g. the adjacent cell in the cell string).

[0038] Reference Figure 1 In an embodiment, if a portion of the first electrode 160 protrudes from one side of the solar cell, the first electrode 160 comprises a first metal wire mesh, and / or if a portion of the second electrode 170 protrudes from another side of the solar cell, the second electrode 170 comprises a second metal wire mesh. It can be understood that the method for forming the electrode protruding from the side of the solar cell is not limited to the above embodiment. Any method that can achieve the electrode protruding from the side of the solar cell should be considered to fall within the protection scope of the present application, as long as it does not deviate from the inventive concept of the present application.

[0039] In combination Figure 1 and Figure 4 as shown, wherein, Figure 4 is a scanning electron microscope image of the metal wire mesh, which can be woven by metal wires, for example, woven by metal wires including silver wires, a plurality of metal wires are arranged at intervals along the second direction D2 and the third direction D3, and gaps S exist between the metal wires. Referring to Figure 2 , the cross section of the metal wire can be rectangular, triangular, and in other embodiments, can also be circular. Compared with the electrode prepared by the screen printing process, the uniformity of the line width of the metal wire mesh and the uniformity of the spacing are better, so that the current mismatch caused by the non-uniform resistance of different regions of the electrode can be avoided.

[0040] In an embodiment, the width of the projection of the metal wire on the silicon substrate in the first direction D1 is 20 nm to 100 nm, for example, the width is 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm; the spacing between adjacent metal wires in the second direction D2 is 20 μm to 100 μm, for example, the spacing is 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm; the spacing between adjacent metal wires in the third direction D3 is 20 μm to 100 μm, for example, the spacing is 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm. Compared with electrodes in the related art (for example, electrodes prepared by a screen printing process, electrodes prepared by an electroplating process), the projection width and spacing of the metal wire of the present application are both small, so that not only the material cost of preparing the electrode is reduced, but also the aesthetic appearance is improved.

[0041] Returning to Figure 1 and Figure 2 In an embodiment, the width (dimension in the second direction D2) of the first protrusion 161 is 500 μm to 1000 μm, for example, the width is 500 μm, 600 μm, 700 μm, 800 μm, 900 μm or 1000 μm; the thickness (dimension in the first direction D1) is 20 nm to 100 nm, for example, the thickness is 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm; the length (dimension in the third direction D3) is 100 mm to 150 mm, for example, the length is 100 mm, 110 mm, 120 mm, 130 mm, 140 mm or 150 mm. The width of the second protrusion 171 is 500 μm to 1000 μm, for example, the width is 500 μm, 600 μm, 700 μm, 800 μm, 900 μm or 1000 μm; the thickness is 20 nm to 100 nm, for example, the thickness is 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm; the length is 100 mm to 150 mm, for example, the length is 100 mm, 110 mm, 120 mm, 130 mm, 140 mm or 150 mm. The above dimensions can be adjusted according to the size of the battery piece.

[0042] Referring to Figure 5In an embodiment, the solar cell further comprises a third passivation layer 180 between the first doped layer 120 and the first passivation layer 130, the third passivation layer 180 can comprise aluminum oxide (Al2O3), the thickness of the third passivation layer 180 comprising aluminum oxide can be 4nm-5nm, the aluminum oxide can be formed using an atomic layer deposition process (ALD). The thickness of the third passivation layer 180 is less than the thickness of the first metal wire mesh in the first electrode 160, one side of the first metal wire mesh is in contact with the first doped layer 120, and the other side penetrates the third passivation layer 180 and is in contact with the first passivation layer 130.

[0043] With reference to the foregoing Figure 5 In an embodiment, the solar cell further comprises a tunneling layer 190 between the second surface 112 and the second doped layer 140, the tunneling layer 190 can comprise silicon oxide (SiOx), and the second doped layer 140 comprises polysilicon.

[0044] With reference to the foregoing Figure 6 In an embodiment, the solar cell further comprises a tunneling layer 190 between the second surface 112 and the second doped layer 140, and a third doped layer 210 between the second doped layer 140 and the second passivation layer 150, the third doped layer 210 has the same doping type as the second doped layer 140, the doping concentration of the third doped layer 210 can be greater than the doping concentration of the second doped layer 140, and the third doped layer 210 can comprise polysilicon. The second electrode 170 is in contact with the second doped layer 140 and the third doped layer 210, and a part of the second electrode 170 is embedded in the third doped layer 210.

[0045] Another aspect of the present application also provides a method for manufacturing a solar cell (hereinafter referred to as the manufacturing method), with reference to the foregoing Figure 7 、 Figure 8 and Figure 2 In an embodiment, the manufacturing method comprises the following steps S110-S150:

[0046] Step S110: providing a silicon substrate 110, the silicon substrate 110 has opposite first and second surfaces 111 and 112;

[0047] Step S120: sequentially forming a first doped layer 120 and a first passivation layer 130 on the first surface 111;

[0048] Step S130: sequentially forming a second doped layer 140 and a second passivation layer 150 on the second surface 112, the doping type of the first doped layer 120 is opposite to that of the second doped layer 140;

[0049] Step S140: forming a first electrode 160 electrically connected to the first doped layer 120 before forming the first passivation layer 130;

[0050] Step S150: forming a second electrode 170 electrically connected with the second doped layer 140 before forming the second passivation layer 150, wherein (i) the first electrode 160 is located between the first doped layer 120 and the first passivation layer 130, and a part of the first electrode 160 protrudes from one side of the solar cell, and / or (ii) the second electrode 170 is located between the second doped layer 140 and the second passivation layer 150, and a part of the second electrode 170 protrudes from another side of the solar cell.

[0051] Next, the steps S110-S150 are described in detail.

[0052] Reference Figure 8 and Figure 2 In step S110, the silicon substrate 110 has a first surface 111 and a second surface 112 opposite in the first direction D1. In step S120, the first doped layer 120 and the first passivation layer 130 are formed in sequence on the first surface 111. In step S130, the second doped layer 140 and the second passivation layer 150 are formed in sequence on the second surface 112, and the doping type of the first doped layer 120 is opposite to that of the second doped layer 140. The above-mentioned film layers can be formed by using the process methods in the prior art, which is not the focus of the present application, and will not be described here.

[0053] In step S140, the first electrode 160 is formed on the first doped layer 120 before forming the first passivation layer 130, and the first electrode 160 is electrically connected with the first doped layer 120.

[0054] In step S150, the second electrode 170 is formed on the second doped layer 140 before forming the second passivation layer 150, and the second electrode 170 is electrically connected with the second doped layer 140.

[0055] In step S150, the second electrode 170 is formed on the second doped layer 140 before forming the second passivation layer 150, and the second electrode 170 is electrically connected with the second doped layer 140.

[0056] In an embodiment, the method of forming the first electrode 160 includes laying a first metal wire mesh on the first doped layer 120, and / or the method of forming the second electrode 170 includes laying a second metal wire mesh on the second doped layer 140. The first metal wire mesh and the second metal wire mesh can be metal wire meshes woven by metal wires sold on the market,

[0057] Reference Figure 1 andFigure 5 In one embodiment, after the first metal wire is laid, a third passivation layer 180 is formed in the apertures S of the first metal wire, for example, aluminum oxide is deposited in the apertures S as the third passivation layer 180 using an ALD process. The thickness of the third passivation layer 180 is less than the thickness of the first metal wire, so that the first metal wire penetrates through the third passivation layer 180. After the third passivation layer 180 is formed, the first passivation layer 130 is formed.

[0058] With continued reference to Figure 1 and Figure 5 In another embodiment, before the first metal wire is laid, a third passivation layer 180 is formed on the first doped layer 120; then, the first metal wire is laid on the third passivation layer 180, the thickness of the third passivation layer 180 is less than the thickness of the first metal wire; then, the solar cell intermediate with the first metal wire laid thereon is subjected to a heat treatment, so that the first metal wire burns through the third passivation layer 180 and contacts the first doped layer 120, so that the first metal wire forms an electrical connection with the first doped layer 120.

[0059] With reference to Figure 5 In one embodiment, before the second doped layer 140 is formed, a tunneling layer 190 is formed on the second surface 112, and the second doped layer 140 is formed on the tunneling layer 190, the second doped layer 140 includes polysilicon.

[0060] With reference to Figure 6 In one embodiment, after the second metal wire is laid, a third doped layer 210 is formed on the second metal wire, the thickness of the third doped layer 210 is greater than the thickness of the second metal wire, so that the third doped layer 210 covers the second metal wire, the doping type of the third doped layer 210 is the same as the doping type of the second doped layer 140, and the third doped layer 210 includes polysilicon.

[0061] In one embodiment, the method of forming the first electrode 160 includes forming an electrode structure having a grid structure using a nanoimprint lithography process or a light-driven electrochemical deposition process; and / or, the method of forming the second electrode 170 includes forming an electrode structure having a grid structure using a nanoimprint lithography process or a light-driven electrochemical deposition process.

[0062] Except as specifically noted, the foregoing description of the solar cell applies equally to the method of manufacture, which will not be repeated.

[0063] Another aspect of the present application provides a solar cell string comprising: (i) a plurality of the solar cell as described above, and / or a plurality of the solar cell prepared by the method as described above; or (ii) at least one of the solar cell as described above, and at least one of the solar cell prepared by the method as described above.

[0064] Reference is made to Figure 9 The first solar cell 220 and the second solar cell 230 are located in the same string of the solar cell string, and are adjacent. The first protrusion 161 in the first solar cell 220 directly contacts the second protrusion 171 in the second solar cell 230 or is connected by a conductive material to form an electrical connection, thereby making the two adjacent solar cells in series, so as to replace the conventional solder ribbon string welding, which saves the solder ribbon and the string welding process. The two can be contacted by applying an external force to the first protrusion 161 and / or the second protrusion 171 towards each other, or an electrical connection is formed between the two by filling a conductive material (such as conductive glue) between the two.

[0065] The present application uses certain terms to describe the embodiments of the present application. As used in the description of the application and the appended claims, the terms "an embodiment", "one embodiment", and / or "some embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the present application. The appearances of the phrase that an "embodiment", "one embodiment”, and / or "some embodiments” in various places in the specification are not necessarily all referring to the same embodiment, nor are the various embodiments necessarily mutually exclusive, unless the context clearly requires so. Moreover, certain features, structures, or characteristics of an embodiment or embodiments of the present application can be combined in any suitable manner.

[0066] It should be noted that, in the description of the embodiments of the present application, in order to simplify the expression of the present application and help the understanding of one or more embodiments of the present application, sometimes various features are combined into one embodiment, figure or description thereof. However, this method of disclosure does not mean that the features required by the present application are more than the features mentioned. In fact, the features of the embodiment are less than all the features of the single embodiment disclosed above.

[0067] In some embodiments, numbers that describe amounts, dimensions, and so forth, are used in the description of the embodiments. It should be understood that such numbers are used only to facilitate description of certain embodiments, and thus the application can be practiced without such specific numbers. At the very least, it is believed that these numbers are closer to their starting points then to their ending points in the measurements of their ambient values. If any numerical characteristic in the specification or claims is described using a word or words that indicate a relationship by "about" or "almost," that numerical characteristic shall be understood to be variable in order to be within the meaning of those words. For example, if a numerical characteristic is described as "about 10," that numerical characteristic can vary from a low value of 9 to a high value of 11.

Claims

1. A solar cell, characterized by, The solar cell comprises: a silicon substrate having opposite first and second surfaces; a first doped layer and a first passivation layer sequentially disposed on the first surface; a second doped layer and a second passivation layer sequentially disposed on the second surface, the doping type of the first doped layer being opposite to that of the second doped layer; a first electrode and a second electrode electrically connected with the first doped layer and the second doped layer respectively, wherein (i) the first electrode is located between the first doped layer and the first passivation layer, the first electrode has a first protruding portion protruding from one side surface of the solar cell, the first passivation layer covers a portion of the first electrode other than the first protruding portion, and the first electrode comprises a first metal wire mesh, the width of the projection of the metal wire in the first metal wire mesh on the silicon substrate being 20 nm to 100 nm, and / or (ii) the second electrode is located between the second doped layer and the second passivation layer, the second electrode has a second protruding portion protruding from the other side surface of the solar cell, the second passivation layer covers a portion of the second electrode other than the second protruding portion, and the second electrode comprises a second metal wire mesh, the width of the projection of the metal wire in the second metal wire mesh on the silicon substrate being 20 nm to 100 nm.

2. The solar cell of claim 1, wherein, The metal wire in the metal wire mesh comprises silver wire.

3. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof. The metal wires are sequentially and spacedly arranged in two directions intersecting with each other, and the spacing between adjacent metal wires is 20 μm to 100 μm.

4. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof. Further comprising a third passivation layer located between the first doped layer and the first passivation layer, wherein the first electrode is in contact with the first doped layer and penetrates through the third passivation layer and is in contact with the first passivation layer.

5. The solar cell of claim 4, wherein the first and second doped regions are formed by implanting dopants into the first and second surfaces of the substrate. The third passivation layer comprises aluminum oxide.

6. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof. Further comprising a tunneling layer located between the second surface and the second doped layer, and the second doped layer comprises polysilicon.

7. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof. Further comprising a tunneling layer located between the second surface and the second doped layer, and a third doped layer located between the second doped layer and the second passivation layer, the doping type of the third doped layer being the same as that of the second doped layer, wherein the second electrode is located between the second doped layer and the third doped layer.

8. The solar cell of claim 1, wherein, The width of the portion of the first electrode protruding from one side surface of the solar cell is 500 μm to 1000 μm, the thickness is 20 nm to 100 nm, and the length is 100 mm to 150 mm, and / or the width of the portion of the second electrode protruding from one side surface of the solar cell is 500 μm to 1000 μm, the thickness is 20 nm to 100 nm, and the length is 100 mm to 150 mm.

9. A method for producing a solar cell, characterized by, The solar cell comprises: a silicon substrate having opposite first and second surfaces; a first doped layer and a first passivation layer sequentially disposed on the first surface; a second doped layer and a second passivation layer sequentially disposed on the second surface, the doping type of the first doped layer being opposite to that of the second doped layer; Before forming the first passivation layer, a first electrode is formed in electrical connection with the first doped layer, the method of forming the first electrode comprising: laying a first metal mesh on the first doped layer, the width of the projection of the metal wires in the first metal mesh on the silicon substrate being 20 nm ~ 100 nm; and Before forming the second passivation layer, a second electrode is formed in electrical connection with the second doped layer, the method of forming the second electrode comprising: laying a second metal mesh on the second doped layer, the width of the projection of the metal wires in the second metal mesh on the silicon substrate being 20 nm ~ 100 nm, wherein (i) the first electrode is located between the first doped layer and the first passivation layer, and the first electrode has a first protruding portion protruding from one side surface of the solar cell, the first passivation layer covering the part of the first electrode other than the first protruding portion, and / or (ii) the second electrode is located between the second doped layer and the second passivation layer, and the second electrode has a second protruding portion protruding from the other side surface of the solar cell, the second passivation layer covering the part of the second electrode other than the second protruding portion.

10. The method of claim 9, wherein After laying the first metal mesh, a third passivation layer is formed in the apertures of the first metal mesh, the thickness of the third passivation layer being less than the thickness of the first metal mesh; After forming the third passivation layer, the first passivation layer is formed.

11. The method of producing a solar cell according to claim 10, wherein The third passivation layer comprises aluminum oxide, and the aluminum oxide is formed using a chemical vapor deposition process.

12. The method of claim 9, wherein: Before laying the first metal mesh, a third passivation layer is formed on the first doped layer; The first metal mesh is laid on the third passivation layer, the thickness of the third passivation layer being less than the thickness of the first metal mesh; The solar cell intermediate body with the first metal mesh laid thereon is subjected to heat treatment, so that the first metal mesh burns through the third passivation layer and comes into contact with the first doped layer.

13. The method of producing a solar cell according to claim 9, wherein Before forming the second doped layer, a tunneling layer is formed on the second surface, and the second doped layer is formed on the tunneling layer, wherein the second doped layer comprises polysilicon.

14. The method of producing a solar cell according to claim 13, wherein After forming the second electrode, a third doped layer is formed between the second doped layer and the second passivation layer and in contact with the second electrode, wherein the doping type of the third doped layer is the same as the doping type of the second doped layer, and the third doped layer comprises polysilicon.

15. The method of producing a solar cell according to claim 9, wherein The method of forming the first electrode comprises forming the first electrode using a nanoimprint lithography process or a light-driven electrochemical deposition process, and / or the method of forming the second electrode comprises forming the second electrode using a nanoimprint lithography process or a light-driven electrochemical deposition process.

16. A string of solar cells, characterized by The method comprises: (i) a plurality of the solar cell according to any one of claims 1 to 8, and / or a plurality of the solar cell produced by the production method of the solar cell according to any one of claims 9 to 15; or (ii) at least one of the solar cell according to any one of claims 1 to 8, and at least one of the solar cell produced by the production method of the solar cell according to any one of claims 9 to 15; wherein, in the adjacent two solar cells, the portion of the first electrode in one solar cell protruding from the side surface is electrically connected to the portion of the second electrode in the other solar cell protruding from the side surface.

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