Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell, a preparation method thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The solar cell comprises a silicon substrate, a functional layer and an electrode structure, the plurality of contact electrodes are oligomerized in a first direction and a second direction which are perpendicular to each other to form a contact electrode group; at least one contact electrode group is composed of a plurality of parts in the second direction; at least one part in the second direction comprises at least two contact electrodes; in the first direction, the sum of the sizes of all the contact electrodes of at least one part and the intervals between the contact electrodes is M; the total number of the contact electrodes of at least one part is n; in the second direction, the distance between the center of the first contact electrode of the at least one part and the center of the tail contact electrode in the at least one part is Hn; (1 / (2n)) * Hn < = M. Electric connection of the transmission electrode and the contact electrode can be ensured, a process window is enlarged, and enough offset space is provided in the transmission electrode setting process.

Description

Technical Field

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

[0002] As the cost of electricity from solar cells becomes lower and lower, the cost of precious metal materials used in solar cells accounts for an increasingly higher proportion. How to reduce the amount of precious metals used in solar cells is an important direction for improvement.

[0003] In a solar cell, a contact electrode is provided on the surface passivation layer, and a transmission electrode is provided above the contact electrode. The transmission electrode is electrically contacted with the doping layer through the contact electrode, and extremely low-cost metals or other materials can be used as the transmission electrode, which can reduce the use of precious metals. Since the contact electrode has a small electrical contact area with the doping layer, it can effectively avoid the surface carrier recombination caused by large-area metal contact, thereby improving the battery performance.

[0004] However, in the above solar cells, the transmission electrodes are prone to deviation, which may cause part of the transmission electrodes to be unable to be electrically connected to the contact electrodes, thereby affecting the cell performance. Summary of the invention

[0005] The present invention provides a solar cell and a preparation method thereof and a photovoltaic module, aiming to solve the problem that some transmission electrodes in existing solar cells may not be electrically connected to contact electrodes, thereby affecting the performance of the cell.

[0006] A first aspect of the present invention provides a solar cell, comprising: a silicon substrate, a functional layer and an electrode structure;

[0007] The functional layer is located on at least one side of the silicon substrate, and the functional layer includes: a doping layer and a surface passivation layer stacked in sequence, and the doping layer is closer to the silicon substrate;

[0008] The electrode structure comprises: a contact electrode penetrating the surface passivation layer and contacting the doping layer, and a transmission electrode located on the contact electrode; a plurality of contact electrodes gathered in a first direction and a second direction perpendicular to each other, forming a contact electrode group; the transmission electrode is electrically connected to at least one of the contact electrodes in the contact electrode group; the second direction, the extension direction of the contact electrode group and the extension direction of the transmission electrode are parallel; the plane defined by the first direction and the second direction is perpendicular to the thickness direction of the silicon substrate;

[0009] In the second direction, at least one of the contact electrode groups is composed of several parts; in the second direction, at least one of the parts includes at least two contact electrodes; in the first direction, the sum of the sizes of all the contact electrodes of the at least one part and the intervals therebetween is M; the total number of contact electrodes of the at least one part is n; in the second direction, the distance between the center of the first contact electrode of the at least one part and the center of the last contact electrode in the at least one part is Hn; (1 / (2n))×Hn≤M.

[0010] In the present application, at least one contact electrode group in the second direction is composed of several parts, and an association is established between the sum of the sizes M of all contact electrodes and the intervals therebetween of at least one part in the first direction, the total number of contact electrodes of the at least one part, and the distance Hn between the center of the first contact electrode of the at least one part and the center of the last contact electrode of the at least one part in the second direction. With respect to the electrical connection between at least one part and the transmission electrode, the first direction and the second direction can complement each other, which can greatly reduce the problem that the transmission electrode cannot be electrically connected to the contact electrode, improve the current transmission performance, and at the same time increase the process window, and reserve sufficient offset space for the transmission electrode setting process. Even if the transmission electrode cannot form electrical contact with a certain contact electrode, it still does not affect the electrical connection of the deviated area, so that the overall collection and transmission performance is basically still unaffected.

[0011] Optionally, (1 / (2n))×Hn≤M≤2n×Hn.

[0012] Optionally, the width of the contact electrode is W, and a direction of the width of the contact electrode is parallel to the first direction; 20W≥M≥W.

[0013] Optionally, the width of the contact electrode is W, the width of the transmission electrode is D, the direction where the width of the transmission electrode is located and the direction where the width of the contact electrode is located are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is 1, W≥D; all contact electrodes in the contact electrode group are collinear along the second direction;

[0014] The transmission electrodes are distributed in a straight line or a curve, and are electrically connected to each of the contact electrodes in the contact electrode group.

[0015] Optionally, the width of the contact electrode is W, the width of the transmission electrode is D, the direction where the width of the transmission electrode is located and the direction where the width of the contact electrode is located are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is 2, W≥D; the contact electrodes in the contact electrode group are staggered along the second direction;

[0016] The transmission electrodes are distributed in a straight line or a curve, and are electrically connected to a plurality of contact electrodes in the contact electrode group.

[0017] Optionally, the width of the contact electrode is W, the width of the transmission electrode is D, the direction of the width of the transmission electrode and the direction of the width of the contact electrode are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is greater than or equal to 2, W≤D; the contact electrodes in the contact electrode group are arranged in at least two rows along the first direction and are staggered; the transmission electrode is at least partially electrically connected to each contact electrode in the contact electrode group; the direction of the row is parallel to the second direction.

[0018] Optionally, the silicon substrate comprises a first surface and a second surface opposite to each other, and the functional layer comprises doping layers which are spaced apart and have different doping types and are located on the second surface;

[0019] The transmission electrode and the doping layer extend in the same direction.

[0020] Optionally, an interface passivation layer is further included, which is located between the silicon substrate and the doping layer; the doping layer includes doped polysilicon.

[0021] Optionally, the material of the contact electrode is different from that of the transmission electrode; or, the contact electrode and the transmission electrode are formed in different processes.

[0022] Optionally, the material of the contact electrode includes at least one of silver, nickel, and titanium; the material of the transmission electrode includes at least one of aluminum, copper, silver, and tin.

[0023] Optionally, the functional layer further includes: an interface surface passivation layer located between the silicon substrate and the doping layer.

[0024] Optionally, 5um≥M≥400um; and / or,

[0025] In the contact electrode group, a distance between two adjacent contact electrodes in the second direction is Q; 5 μm≤Q≤80 μm.

[0026] Optional, 50um≥D≥250um.

[0027] Optionally, in the transmission electrode, a cross-section parallel to the thickness direction of the silicon substrate and the first direction has a shape of a triangle, a circle, a sector or a rectangle; and / or,

[0028] In the contact electrode, the shape of the cross section parallel to the thickness direction of the silicon substrate and the first direction is quasi-circular, semicircular, or rectangular; and / or,

[0029] The contact electrodes in a contact electrode group are distributed in the form of spaced dots or spaced blocks; and / or,

[0030] The transmission electrodes are distributed in a continuous long strip shape.

[0031] A second aspect of the present invention provides a photovoltaic assembly, comprising: a plurality of any of the aforementioned solar cells.

[0032] Optionally, the transmission electrode is also used to electrically connect contact electrodes of different polarities in adjacent solar cells.

[0033] A third aspect of the present invention provides a method for preparing a solar cell, comprising:

[0034] providing a silicon substrate;

[0035] forming a doping layer and a surface passivation layer stacked in sequence on at least one side of the silicon substrate;

[0036] forming a contact electrode on the surface passivation layer, wherein the doping layer contacts the contact electrode;

[0037] A transmission electrode is formed on the contact electrode.

[0038] Optionally, before forming the contact electrode, the method further includes:

[0039] Using laser to form openings in the surface passivation layer;

[0040] Forming the contact electrode includes forming the contact electrode in the opening of the passivation layer.

[0041] The above-mentioned solar cell and preparation method thereof and photovoltaic module have the same or similar beneficial effects, and will not be described in detail here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0043] Figure 1 and Figure 2 The schematic diagrams of the structures of two solar cells in the embodiments of the present invention are shown;

[0044] Figures 3 to 12 A partial structural schematic diagram of an electrode structure in a solar cell in an embodiment of the present invention is shown;

[0045] Fig.13 A cross-sectional schematic diagram of a contact electrode in a solar cell in an embodiment of the present invention is shown.

[0046] Description of the accompanying drawings:

[0047] 1-silicon substrate, 2-doping layer, 3-surface passivation layer, 41-contact electrode, 42-transmission electrode, 5-front surface passivation and anti-reflection film, 6-interface passivation layer. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The present invention provides a solar cell, which is combined with Figures 1 to 13 Explanation of the present application. The solar cell may include: a silicon substrate 1, a functional layer and an electrode structure. The silicon substrate 1 includes a first side and a second side opposite to each other. Here, one of the first side and the second side is a light-facing side, and the other is a backlight side. During normal operation of the solar cell, the side that mainly receives light is the light-facing side, and the backlight side is opposite to the light-facing side. For example, Figure 1 In the embodiment, the upper and lower sides of the silicon substrate 1 are the first side and the second side respectively. The silicon substrate 1 here can be a P-type silicon substrate, an N-type silicon substrate, or a silicon substrate close to the intrinsic conductivity type. The crystal type of the silicon substrate 1 can be single crystal or polycrystalline.

[0050] The functional layer is located on at least one side of the silicon substrate, where one side refers to the light-facing side and / or the backlight side of the silicon substrate. The functional layer may include: a doping layer 2 and a surface passivation layer 3 stacked in sequence, and the doping layer 2 is closer to the silicon substrate 1. For example, the solar cell may include a functional layer located on the first side of the silicon substrate 1 and the second side of the silicon substrate 1. The doping type of the doping layer located on the first side of the silicon substrate 1 is different from the doping type of the doping layer located on the second side of the silicon substrate 1, one of which is N-type doping and the other is P-type doping. The doping layer 2 may be composed of one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. The P-type doping layer is generally doped with group III elements. The N-type doping layer is generally doped with group V elements or group VI elements.

[0051] The functional layer here can realize the functions of current conduction and passivation anti-reflection. The surface passivation layer 3 can be composed of one layer or multiple layers, or can be composed of different materials in different regions. The material of the surface passivation layer 3 can include: one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon.

[0052] Reference Figure 1 and Figure 2 The electrode structure includes: a contact electrode 41 that penetrates the surface passivation layer 3 and contacts the doping layer 2, and a transmission electrode 42 located on the contact electrode 41. The contact electrode 41 and the transmission electrode 42 form an electrical connection, thereby realizing the current collection and conduction from the doping layer 2 to the contact electrode 41 to the transmission electrode 42. The contact electrode 41 and the transmission electrode 42 here can both use metals (such as Ag, Cu, Al, Ni, Au, Zn, Sn, Pb, etc.), metal oxides (various TCOs, such as ITO, AZO, IWO, etc.), metal nitrides (TiN, etc.), metal carbides (TiC, etc.), or metal sulfides, etc., as well as other conductive connection materials (such as graphene, etc.), or various combinations of the above materials. The preferred transmission electrode 42 is made of base metals, such as Al, Cu, etc., and other cheap metals based on aluminum and / or copper.

[0053] It is worth noting that the doping layer 2 is preferably doped polysilicon, such as a tunnel passivation structure. The doped polysilicon has a relatively loose structure. Setting a local contact electrode is beneficial to dispersing the risk of electrode material burning through the doped polysilicon and improving the stability of the solar cell.

[0054] In addition, it is preferred that the material of the contact electrode 41 is different from the material of the transmission electrode 42; for the contact electrode in direct contact with the doped layer 2, metal materials with barrier properties such as nickel (Ni) and titanium (Ti) are selected, which can effectively improve the corrosion and damage of the contact electrode material to the doped layer 2, thereby improving the recombination of carriers, or silver (Ag) with contact advantages is selected. In particular, when the doped layer 2 is doped polysilicon, the doped polysilicon is more easily corroded or damaged, and even burns through the tunneling oxide layer. Selecting materials such as nickel (Ni) and titanium (Ti) is more conducive to the characteristics of the tunneling passivation structure. For the material of the transmission electrode, metal materials with excellent conductive transmission properties such as copper (Cu), aluminum (Al), silver (Ag), and tin (Sn) are preferred to improve the transmission efficiency and reduce the transmission loss. Generally speaking, the above-mentioned contact electrode and the transmission electrode are formed in different processes. First, the contact electrode is formed, and then the transmission electrode is formed on the contact electrode. The specific process for forming the contact electrode and the transmission electrode is not limited.

[0055] It should be noted that the solar cell may contain two of the above electrode structures, or one of the above electrode structures. For example, the above two electrode structures, one of which is located on the first side of the silicon substrate 1, and the other electrode structure is located on the second side of the silicon substrate 1, and one of the two electrode structures is a front electrode structure and the other is a back electrode structure.

[0056] Reference Figures 3 to 12 , the extension direction of the transmission electrode 42 is L1, the first direction L2 is perpendicular to the extension direction L1 of the transmission electrode 42, the extension direction L1 of the transmission electrode 42 is parallel to the second direction, and the second direction can be considered to be the direction indicated by L1. The plane defined by the first direction L2 and the second direction L1 is perpendicular to the thickness direction L3 of the silicon substrate 1.

[0057] Reference Figures 3 to 12 A plurality of contact electrodes 41 gathered in the first direction L2 and the second direction L1 perpendicular to each other form a contact electrode group, such as Figures 3 to 12 The contact electrode group is located at the position where the transmission electrode is set. The transmission electrode 42 is electrically connected to at least one contact electrode 41 in the contact electrode group. Figures 3 to 10 and Fig.12 As shown, the transmission electrode 42 is at least partially electrically connected to all the contact electrodes 41 in the contact electrode group, or it can be Fig.11As shown, the transmission electrode 42 is at least partially electrically connected to some of the contact electrodes 41 in the contact electrode group, and the transmission electrode 42 is separated from at least one contact electrode 41 in the group of contact electrodes, that is, no electrical connection is formed. The extension direction of the contact electrode group is parallel to the extension direction L1 of the transmission electrode 42, and the extension direction of the contact electrode group refers to the direction in which the maximum dimension of the contact electrode group is located.

[0058] In the second direction L1, at least one contact electrode group is composed of several parts, where the several parts may be one or more, and there is no specific limitation on this. Fig.12 , at least one portion in the second direction L1 includes at least two contact electrodes 41, then the total number n of contact electrodes 41 in at least one portion is greater than or equal to 2, where n is a natural number greater than or equal to 2. There is no limitation on the division method of the portion in at least one contact electrode group. For example, the total number n of contact electrodes 41 in at least one portion can be: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. For another example, Fig.12 , that is, the first contact electrode and the second contact electrode in the contact electrode group from top to bottom are divided into a part, and the total number n of contact electrodes 41 in the part is 2.

[0059] Reference Figures 3 to 11 , in the first direction L2, the sum of the sizes of all contact electrodes 41 and the intervals therebetween of at least one portion is M. Specifically, the width of the contact electrode 41 is W, and the direction where the width W of the contact electrode 41 is located is parallel to the first direction L2. Fig.12 In the first direction, the distance between the geometric center of the first contact electrode 41 and the geometric center of the last contact electrode 41 of the contact electrode group in the first direction L2 is Wn, and the aforementioned M=W+Wn. The at least one part here can be one part or multiple parts, which is not limited.

[0060] Reference Fig.12 , in the second direction L1, the distance between the center of the first contact electrode of the at least one part and the center of the last contact electrode of the at least one part is Hn, where the first contact electrode and the last contact electrode specifically refer to: the first contact electrodes at the opposite ends of the at least one part in the second direction. Then, for the same at least one part, (1 / (2n))×Hn≤M. For example, Fig.12In the embodiment, the first contact electrode and the second contact electrode in the contact electrode group from top to bottom are divided into a part, and the total number n of contact electrodes 41 in the part is 2. The distance between the center of the first contact electrode and the center of the last contact electrode in the part is Hn, and 2n is equal to 4, (1 / 4)×Hn≤M.

[0061] It should be noted that, in the case of multiple parts, Hn, M, and n here are all parameters for the same multiple parts. In the case of one part, Hn, M, and n here are all parameters for the same part.

[0062] In the present application, at least one contact electrode group in the second direction is composed of several parts, and an association is established between the sum of the sizes M of all contact electrodes of the at least one part and the intervals therebetween in the first direction, the total number n of contact electrodes of the at least one part, and the distance Hn between the center of the first contact electrode of the at least one part and the center of the last contact electrode of the at least one part in the second direction. With respect to the electrical connection between the at least one part and the transmission electrode, the first direction and the second direction can complement each other, and the problem that the transmission electrode cannot be electrically connected to the contact electrode can be reduced to a great extent, thereby improving the current transmission performance and increasing the process window. Sufficient offset space is reserved for the transmission electrode setting process, and even if the transmission electrode cannot form electrical contact with a certain contact electrode, it still does not affect the electrical connection of the deviated area, so that the overall collection and transmission performance is basically still unaffected. Specifically, when the contact electrodes of at least one part are arranged relatively closely in the first direction, that is, when M is relatively small, Hn can be relatively large. In this way, even if a certain contact electrode cannot be connected to the transmission electrode, since the contact electrodes are arranged relatively closely, it can be ensured that other contact electrodes can be connected to the transmission electrode; when the contact electrodes of at least one part are arranged relatively sparsely in the first direction, that is, when M is relatively large, Hn needs to be relatively small. By shortening the distance between adjacent contact electrodes in the second direction, the effective contact area between the transmission electrode and the contact electrode is controlled to ensure that current collection and transmission are not affected.

[0063] Furthermore, (1 / (2n))×Hn≤M≤2n×Hn. For example, for the above Fig.12 The part referred to is (1 / 4)×Hn≤M≤4×Hn, and M can be (1 / 4)×Hn, (1 / 3)×Hn, (1 / 2)×Hn, Hn, 1.2×Hn, 1.5×Hn, 1.8×Hn, 2×Hn, 2.5×Hn, 3×Hn, (1 / 4)×Hn, 3.5×Hn, 3.7×Hn, 4×Hn. Therefore, (1 / 2n)×Hn≤M≤2n×Hn is controlled, which can not only reduce the offset effect but also ensure the current collection and transmission performance.

[0064] For example, M can be (1 / (2n))×Hn, (3 / (2n))×Hn, (5 / (2n))×Hn, ((n-3) / (2n))×Hn, ((n-1) / (2n))×Hn, (1 / (2))×Hn, ((n+1) / (2n))×Hn, ((n+3) / (2n))×Hn, ((2n-1) / (2n))×Hn, Hn, 2Hn, (2n-4)Hn, (2n-1)Hn, 2n×Hn.

[0065] The width of the transmission electrode 42 is D, and the direction of the width D of the transmission electrode 42 is parallel to the first direction L2. In the present application, the relative size between the sum of the sizes M of all contact electrodes and the intervals therebetween of at least one part and the width D of the transmission electrode 42 is not limited. For example, M≥D, or M≤D.

[0066] It should be noted that, refer to Figures 8 to 9 In the first direction L2, when the contact electrode group contains only one contact electrode 41, the M corresponding to each part of the contact electrode group is the width of one contact electrode 41. Figures 3 to 7 , Figures 10 to 12 In the first direction L2, when the contact electrode group contains a plurality of contact electrodes 41, M corresponding to a portion of the group of contact electrodes is the sum of the widths of all contact electrodes 41 in the portion and the intervals therebetween. That is, in the first direction L2, when the contact electrode group contains a plurality of contact electrodes 41, M corresponding to each portion of the group of contact electrodes is the sum of the distances between the outermost endpoint of the first contact electrode of the portion and the outermost endpoint of the last contact electrode of the portion in the first direction L2.

[0067] Optional, see Fig.12 , the width of the contact electrode 41 is W, and the direction of the width W of the contact electrode 41 is parallel to the first direction L2; 20W≥M≥W, and an association relationship is established between M corresponding to at least one part and the width W of the contact electrode 41. On the one hand, the interval between the adjacent contact electrodes 41 in the first direction L2 in the at least one part is not too large, thereby ensuring effective contact between the transmission electrode and the contact electrode, and the interval between the adjacent contact electrodes 41 in the first direction L2 in the at least one part is not too small, thereby reducing the use of precious metals and reducing costs. Here, a good balance is achieved between effective current conduction and reduced cost of the contact electrode.

[0068] For example, M can be W, 3W, 2W, 4W, 5W, 6W, 7W, 8W, 9W, 10W, 11W, 12W, 13W, 14W, 15W, 16W, 17W, 18W, 19W, 20W.

[0069] Optionally, 5um≥M≥400um, where M is within this value range. On the one hand, the interval between adjacent contact electrodes 41 in the first direction L2 in the at least one portion is not too large, thereby ensuring effective contact between the transmission electrode and the contact electrode. Also, the interval between adjacent contact electrodes 41 in the first direction L2 in the at least one portion is not too small, thereby reducing the use of precious metals and lowering costs. Here, a good balance is achieved between effective current conduction and reduced cost of contact electrodes.

[0070] For example, M can be 5um, 10um, 30um, 50um, 80um, 100um, 150um, 200um, 250um, 300um, 350um, 400um, or 220um.

[0071] The width of the transmission electrode 42 is D, optionally, 50um≥D≥250um, and the range of D balances the shading effect and the current transmission performance, which can not only ensure a good current conduction effect but also reduce shading.

[0072] For example, D can be 50um, 80um, 100um, 120um, 150um, 180um, 200um, 230um, 250um, or 220um.

[0073] Furthermore, 80um≥D≥150um, the range of D further balances the shading effect and current transmission performance, which can not only ensure a good current conduction effect but also reduce shading. For example, D can be 80um, 90um, 100um, 110um, 130um, 140um, 150um, 125um, 115um.

[0074] Optional, see Figure 7 In the contact electrode group, the distance between two adjacent contact electrodes 41 in the second direction L1 is Q; 5μm≤Q≤80μm. On the one hand, a more reliable and effective current collection effect can be guaranteed in the second direction L1. On the other hand, the interval between the adjacent contact electrodes 41 in the contact electrode group in the second direction L1 is not too large, ensuring effective contact between the transmission electrode and the contact electrode, and the interval between the adjacent contact electrodes 41 in the contact electrode group in the second direction L1 is not too small, which can reduce the amount of precious metals and reduce costs. It is here that a good balance is achieved between effective current conduction and reduced contact electrode costs. Furthermore, 10μm≤Q≤30μm, a better balance is achieved between effective current collection and reduced contact electrode costs.

[0075] For example, Q can be 5um, 10um, 12um, 15um, 18um, 20um, 24um, 25um, 28um, 30um, 35um, 40um, 45um, 50um, 55um, 60um, 65um, 70um, 75um, 80um.

[0076] Optional, see Fig.13 In the contact electrode 41, the cross-section parallel to the first direction L2 and the thickness direction of the silicon substrate is quasi-circular, semi-circular, or rectangular. The contact electrode 41 of the above shape is easy to set and has a good current conduction effect. The quasi-circular shape here can include: a circle and an ellipse. The rectangle here can include a rectangle with chamfered corners, etc.

[0077] Optionally, in the transmission electrode 42, the shape of the cross section parallel to the thickness direction L3 and the first direction L2 of the silicon substrate 1 is one of a triangle, a circle, a quasi-circular, a fan or a rectangle. The transmission electrode of the above shape is easy to prepare, and has a smaller current collection effect and a smaller shading effect.

[0078] Optionally, each contact electrode 41 in the contact electrode group is distributed in the form of spaced points or spaced blocks, that is, each contact electrode 41 in the contact electrode group is in local contact, which can effectively avoid surface carrier recombination caused by large-area metal contact, thereby improving battery performance and reducing the use of precious metals.

[0079] Optionally, the transmission electrodes 42 are distributed in a continuous long strip shape, with less light shielding and better current collection effect.

[0080] Optionally, the silicon substrate 1 includes a first surface and a second surface opposite to each other, one of the first surface and the second surface is a light-facing surface and the other is a backlight surface. The aforementioned functional layer includes doping layers with different doping types and spaced apart on the second surface. The second surface may be the backlight surface of the silicon substrate 1. The spacing here can avoid short circuits in the solar cell. The doping layers with different doping types refer to N-type doping layers and P-type doping layers. Figure 1 and Figure 2 That is, the solar cell is a back-contact solar cell, in which the transmission electrode 42 and the doping layer have the same extension direction. Specifically, the doping layers of the two doping types in the back-contact solar cell are both located on the backlight side of the silicon substrate, and all electrode structures are also located on the backlight side of the silicon substrate. The setting of the contact electrodes and the transmission electrodes of the two polarities must not only consider the alignment of the transmission electrodes and the contact electrodes, but also the short circuit, which makes the setting difficult. Through the optimized design of the present application, the electrical connection effect between the transmission electrode and the contact electrode in the back-contact solar cell is better, the current collection effect is good, and the short circuit risk is low.

[0081] It should be noted that the solar cell can also be a double-sided solar cell with electrodes on both surfaces, and the cell type is not limited. The doping layer and the back doping layer here can be polycrystalline silicon material, amorphous silicon material, microcrystalline silicon material, etc., and there is no specific limitation on this.

[0082] Optional, see Figure 8 and Fig. 9 The number of contact electrodes 41 of the contact electrode group in the first direction L2 is 1, the width of the contact electrode 41 is W, and the width of the contact electrode is parallel to the first direction L2. The width of the transmission electrode 42 is D, and the width of the transmission electrode 42 is the line width of the contact electrode 41, W≥D. Figure 8 The transmission electrodes 42 are arranged in a straight line, or Fig. 9 In the embodiment, the transmission electrode 42 is distributed in a curved shape, all the contact electrodes 41 in the contact electrode group are distributed in a collinear manner along the second direction L1, the number of the contact electrodes 41 in the contact electrode group in the first direction L2 is small, and all the contact electrodes 41 in the contact electrode group are distributed in a collinear manner along the second direction L1, the transmission electrode 42 is electrically connected to each contact electrode 41 in the contact electrode group, a good electrical connection effect can be achieved through fewer contact electrodes, and the shape of the transmission electrode 42 is more flexible. In addition, due to the large width of the contact electrode 41, the process window is increased, the current transmission performance is improved, and sufficient offset space is reserved for the transmission electrode welding or bonding process.

[0083] Optional, see Fig.10 and Fig.11 , the width of the contact electrode 41 is W, and the width of the contact electrode is parallel to the first direction L2. The number of contact electrodes 41 in the contact electrode group in the first direction L2 is 2, W ≥ D; the contact electrodes 41 in the contact electrode group are staggered along the second direction L1. The transmission electrode 42 is distributed in a straight line or a curve, and is electrically connected to multiple contact electrodes 41 in the contact electrode group, which increases the process window, improves the current transmission performance, and reserves sufficient offset space for the transmission electrode welding or bonding process, refer to Fig.11 Even if the transmission electrode 42 cannot form electrical contact with a certain contact electrode 41, the overall collection and transmission performance is still not affected.

[0084] Optional, see Figures 3 to 7 and Fig.12, the width of the contact electrode 41 is W, and the width of the contact electrode 41 is parallel to the first direction L2. The number of contact electrodes 41 in the contact electrode group in the first direction L2 is greater than or equal to 2, W≤D; the contact electrodes 41 in the contact electrode group are arranged in at least two rows along the first direction L2, and are staggered; the transmission electrode 42 is at least partially electrically connected to each contact electrode in the contact electrode group, and the direction of the row here is parallel to the second direction L1, which increases the process window. The width of the transmission electrode 42 is relatively wide, which can cover the contact electrode 41 to the greatest extent, not only leaving enough offset space for the welding or bonding process of the transmission electrode, but also increasing the effective contact area of ​​the electrode. At the same time, while ensuring the same transmission performance, the use of two or more rows can reduce the passivation layer film opening area, improve the passivation effect, and increase the battery opening voltage.

[0085] Optional, see Figure 1 In the solar cell, the functional layer may further include: an interface passivation layer 6, located between the silicon substrate 1 and the doping layer 2, which may enhance the passivation effect between the silicon substrate 1 and the doping layer 2. The interface passivation layer may be composed of one or more layers, or may be composed of different materials in different regions. The material of the interface passivation layer may include: one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon.

[0086] The present application also provides a method for preparing a solar cell, which can be used to prepare any of the aforementioned solar cells. The solar cell can include the following steps.

[0087] Step 101, providing a silicon substrate.

[0088] Step 102: forming a doping layer and a surface passivation layer stacked in sequence on at least one side of the silicon substrate.

[0089] The doping layer and the surface passivation layer may be prepared by deposition or the like, and the specific formation method is not limited.

[0090] Step 103: forming a contact electrode on the surface passivation layer, wherein the doping layer contacts the contact electrode.

[0091] Step 104: forming a transmission electrode on the contact electrode.

[0092] Optionally, before step 103, the method may further include: using a laser to form an opening in the surface passivation layer; forming the contact electrode includes: forming the contact electrode in the opening of the passivation layer, and the laser opening method is simple and easy.

[0093] The following is a further explanation of a method for preparing the solar cell provided in the present application, a. Surface treatment of silicon wafers, such as texturing of silicon wafers to form a pyramid texturing structure to obtain a silicon substrate, and then a combination of diffusion, laser drilling, ion implantation and annealing, masking, etching and other techniques are used to produce a first doped layer and a second doped layer arranged alternately on the backlight surface of the silicon substrate, one of which is an N-type doped layer and the other is a P-type doped layer.

[0094] b. Complete the surface passivation step.

[0095] A surface passivation layer and / or an anti-reflection film are formed on the light-facing surface and the backlight surface of the structure formed in a. The surface passivation and anti-reflection film 5 on the front side can be composed of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon. The surface passivation layer on the back side is composed of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, silicon carbide, and amorphous silicon.

[0096] The structure of the surface passivation layer can be a single layer or a multi-layer structure. For example, an aluminum oxide passivation layer is first prepared by ALD (atomic layer deposition) method, and then a silicon nitride layer or a multi-layer structure is formed thereon by PECVD.

[0097] The material of the surface passivation layer is as described above and will not be repeated here. The preparation method may be ALD, various CVD (such as PECVD, APCVD, LPCVD, MOCVD, etc.), various PVD (evaporation, sputtering), etc.

[0098] c. Perform a surface passivation layer window opening process step, such as using a laser or other process to remove part of the surface passivation layer on the back.

[0099] d. Forming an electrode structure.

[0100] A first electrode structure is made on the first doping layer, and a second electrode structure is made on the second doping layer. For example, the contact electrode can be coated on the surface passivation layer on the back side using electrode slurry, and then sintered so that the electrode slurry passes through the surface passivation layer and forms contact with the doping layer. However, it is preferred to use the aforementioned c laser windowing and then use ALD, various CVD, PVD, chemical plating, electroplating and other methods to form the contact electrode. In the process of forming the contact electrode, various steps such as patterning mask, annealing, sintering, plasticity, transfer and the like can be performed.

[0101] e. Forming the transmission electrode.

[0102] The transmission electrode can be formed after the contact electrode is completed, or it can be formed at the same time as the contact electrode. When the two are formed at the same time, the transmission electrode and the contact electrode use the same material, such as Al or Ag. When the two are formed successively, the transmission electrode and the contact electrode can be fixedly connected by welding (soldering) or bonding (conductive adhesive bonding). The transmission electrode is preferably made of base metal, such as Al, Cu, etc., and other cheap metals based on aluminum and / or copper.

[0103] The present application also provides a photovoltaic module, which may include any of the aforementioned solar cells. The photovoltaic module may also include a packaging film located outside the solar cell, etc. The photovoltaic module can expand the application scenarios of the solar cell.

[0104] Optionally, in a photovoltaic module, the transmission electrode is also used to electrically connect contact electrodes of different polarities in adjacent solar cells. There is no need to separately provide an interconnector for electrically connecting contact electrodes of different polarities in adjacent solar cells, and the process is simple.

[0105] It should be noted that the transmission electrode here may have certain conductive interconnection properties such as welding properties, etc. For example, the transmission electrode may be a welding wire, etc.

[0106] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0107] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A solar cell, characterized in that: include: Silicon substrate, functional layers and electrode structures; The functional layer is located on at least one side of the silicon substrate, and the functional layer includes: a doping layer and a surface passivation layer stacked in sequence, and the doping layer is closer to the silicon substrate; The electrode structure comprises: a contact electrode penetrating the surface passivation layer and contacting the doping layer, and a transmission electrode located on the contact electrode; a plurality of contact electrodes gathered in a first direction and a second direction perpendicular to each other, forming a contact electrode group; the transmission electrode is electrically connected to at least one of the contact electrodes in the contact electrode group; the second direction, the extension direction of the contact electrode group and the extension direction of the transmission electrode are parallel; the plane defined by the first direction and the second direction is perpendicular to the thickness direction of the silicon substrate; In the second direction, at least one of the contact electrode groups is composed of several parts; in the second direction, at least one of the parts includes at least two contact electrodes; in the first direction, the sum of the sizes of all the contact electrodes of the at least one part and the intervals therebetween is M; the total number of contact electrodes of the at least one part is n; in the second direction, the distance between the center of the first contact electrode of the at least one part and the center of the last contact electrode of the at least one part is Hn; (1 / (2n))×Hn≤M.

2. The solar cell according to claim 1, characterized in that (1 / (2n))×Hn≤M≤2n×Hn.

3. The solar cell according to claim 1, characterized in that The width of the contact electrode is W, and the direction of the width of the contact electrode is parallel to the first direction; 20W≥M≥W.

4. The solar cell according to claim 1, characterized in that The width of the contact electrode is W, the width of the transmission electrode is D, the direction where the width of the transmission electrode is located and the direction where the width of the contact electrode is located are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is 1, W≥D; all contact electrodes in the contact electrode group are collinear along the second direction; The transmission electrodes are distributed in a straight line or a curve, and are electrically connected to each of the contact electrodes in the contact electrode group.

5. The solar cell according to claim 1, characterized in that: The width of the contact electrode is W, the width of the transmission electrode is D, and the direction of the width of the transmission electrode and the direction of the width of the contact electrode are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is 2, W≥D; the contact electrodes in the contact electrode group are staggered along the second direction; The transmission electrodes are distributed in a straight line or a curve, and are electrically connected to a plurality of contact electrodes in the contact electrode group.

6. The solar cell according to claim 1, characterized in that The width of the contact electrode is W, the width of the transmission electrode is D, the direction of the width of the transmission electrode and the direction of the width of the contact electrode are both parallel to the first direction; the number of contact electrodes in the contact electrode group in the first direction is greater than or equal to 2, W≤D; the contact electrodes in the contact electrode group are arranged in at least two rows along the first direction and are staggered; the transmission electrode is at least partially electrically connected to each contact electrode in the contact electrode group; the direction of the row is parallel to the second direction.

7. The solar cell according to claim 1, characterized in that The silicon substrate comprises a first surface and a second surface opposite to each other, and the functional layer comprises doping layers which are spaced apart and have different doping types and are located on the second surface; The transmission electrode and the doping layer extend in the same direction.

8. The solar cell according to claim 1, characterized in that It also includes an interface passivation layer located between the silicon substrate and the doping layer; the doping layer includes doped polysilicon.

9. The solar cell according to claim 1 or 8, characterized in that: The material of the contact electrode is different from that of the transmission electrode; or the contact electrode and the transmission electrode are formed in different processes.

10. The solar cell according to claim 9, characterized in that: The material of the contact electrode includes at least one of silver, nickel, and titanium; the material of the transmission electrode includes at least one of aluminum, copper, silver, and tin.

11. The solar cell according to any one of claims 1 to 8, characterized in that: The functional layer further includes: an interface surface passivation layer located between the silicon substrate and the doping layer.

12. The solar cell according to any one of claims 1 to 8, characterized in that: 5um≥M≥400um; and / or, In the contact electrode group, a distance between two adjacent contact electrodes in the second direction is Q; 5 μm≤Q≤80 μm.

13. The solar cell according to any one of claims 4 to 6, characterized in that: 50um≥D≥250um.

14. A photovoltaic module, characterized in that: include: A solar cell as claimed in any one of claims 1 to 13.

15. The photovoltaic module according to claim 14, characterized in that: The transmission electrode is also used to electrically connect contact electrodes of different polarities in adjacent solar cells.

16. A method for preparing a solar cell, characterized in that: include: providing a silicon substrate; forming a doping layer and a surface passivation layer stacked in sequence on at least one side of the silicon substrate; forming a contact electrode on the surface passivation layer, wherein the doping layer contacts the contact electrode; A transmission electrode is formed on the contact electrode.

17. The method for preparing a solar cell according to claim 16, characterized in that: Before forming the contact electrode, the method further includes: Using laser to form openings in the surface passivation layer; Forming the contact electrode includes forming the contact electrode in the opening of the passivation layer.

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