Gold semi-contact structure and preparation method, solar cell, solar cell string and preparation method, photovoltaic module

Abstract

The present application relates to the field of solar cells, and in particular to a gold semi-contact structure and preparation method, solar cells, solar cell strings and preparation method, and photovoltaic modules. The gold semi-contact structure includes: a doped silicon-based semiconductor layer; a metal electrode, which contacts the doped silicon-based semiconductor layer, and the metal electrode has a metal element; a contact region is provided between the doped silicon-based semiconductor layer and the metal electrode, and the contact region includes a first conductive region and a second conductive region located outside the first conductive region; in the first conductive region, the metal electrode is recessed toward the inside of the doped silicon-based semiconductor layer itself to form a pit island, and the pit island has a silicon-based eutectic, and the silicon-based eutectic is in conductive contact with the doped silicon-based semiconductor layer, and the first conductive region also has a conductive crystal body conductively connected to the silicon-based eutectic; in the second conductive region, there is a conductive aggregate, including a glass phase material and metal conductive particles, and the metal conductive particles and the conductive crystal body have the same type of metal element.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular to a gold semi-contact structure and a preparation method, a solar cell, a solar cell string and a preparation method, and a photovoltaic module. Background Art

[0002] The gold semi-contact structure is a structure formed by the metal electrode in the solar cell contacting the doped silicon-based semiconductor layer. As an important component of the solar cell, the gold semi-contact structure has an important influence on the performance of the solar cell.

[0003] At present, in the gold-semiconductor contact structure of solar cells, the conductive contact performance between metal materials and semiconductor materials is not ideal, which is manifested in that the contact resistance in the conductive contact area is relatively large, making it difficult to substantially improve the electrical performance indicators such as the open circuit voltage and photoelectric conversion efficiency of solar cells. Summary of the invention

[0004] In order to solve the above technical problems, the present application discloses a gold semi-contact structure and preparation method, a solar cell, a solar cell string and preparation method, and a photovoltaic module to reduce the contact resistance of the conductive contact area of ​​the gold semi-contact structure and improve the performance of the solar cell.

[0005] In a first aspect, the present application provides a gold semiconductor contact structure, comprising:

[0006] doping a silicon-based semiconductor layer;

[0007] A metal electrode, the metal electrode is in contact with the doped silicon-based semiconductor layer, and the metal electrode has a metal element;

[0008] There is a contact region between the doped silicon-based semiconductor layer and the metal electrode, and the contact region includes a first conductive region and a second conductive region outside the first conductive region;

[0009] In the first conductive region, the metal electrode is recessed toward the inside of the doped silicon-based semiconductor layer to form a pit island, wherein the pit island has a silicon-based eutectic, the silicon-based eutectic is in conductive contact with the doped silicon-based semiconductor layer, and the first conductive region also has a conductive crystal body conductively connected to the silicon-based eutectic;

[0010] In the second conductive region, there is a conductive aggregate, the conductive aggregate includes a glass phase material and metal conductive particles, and the metal conductive particles have the same type of the metal element as the conductive crystals.

[0011] Furthermore, a portion of the metal conductive particles are located on the surface of the doped silicon-based semiconductor layer, and another portion of the metal conductive particles are distributed in the glass phase material, and the conductive aggregate is in contact with the doped silicon-based semiconductor layer through the metal conductive particles.

[0012] Furthermore, the pit island includes a plurality of holes and pits located outside the holes.

[0013] Furthermore, the distribution density of the holes is 1 / μm 2 ~50 / μm 2 and / or,

[0014] The pores have a diameter of 10 nm to 100 nm.

[0015] Furthermore, the surface of the area surrounded by the pit islands has a higher roughness than that of the second conductive area.

[0016] Furthermore, the surface of the doped silicon-based semiconductor layer has a pyramid velvet structure, and the pit island is located at the top of the pyramid velvet structure or at a position near the top of the pyramid velvet structure.

[0017] Furthermore, the metal electrode includes a silver electrode.

[0018] Optionally, the doped silicon-based semiconductor layer includes one of a doped amorphous silicon layer, a doped polycrystalline silicon layer, a doped microcrystalline silicon layer or a doped crystalline silicon layer, and the doping element includes an N-type doping element or a P-type doping element, the N-type doping element includes at least one of phosphorus, antimony or arsenic, and the P-type doping element includes at least one of boron, indium or gallium.

[0019] Furthermore, the conductive crystal includes a crystalline main chain and a crystalline side chain extending from the crystalline main chain in a growth direction different from that of the crystalline main chain.

[0020] Furthermore, the size of the conductive crystals is 1 nm to 30 nm.

[0021] In a second aspect, the present application provides a method for preparing a gold semi-contact structure, wherein the gold semi-contact structure is the gold semi-contact structure as described in the first aspect, and the method for preparing the gold semi-contact structure comprises the following steps:

[0022] Printing electrode paste on the doped silicon-based semiconductor layer; the electrode paste includes a glass phase material, a metal material and an organic carrier;

[0023] Pre-sintering the electrode slurry at high temperature to form the pit islands on a portion of the surface of the doped silicon-based semiconductor layer, and forming an electrode precursor on the doped silicon-based semiconductor layer; wherein the electrode precursor includes the glass phase material and the metal conductive particles wrapped in the glass phase material;

[0024] The electrode precursor is subjected to laser induced contact treatment to form the metal electrode, and the gold semi-contact structure is formed between the metal electrode and the doped silicon-based semiconductor layer.

[0025] Furthermore, in the step of sintering the electrode slurry, the sintering temperature is 700°C to 850°C.

[0026] Furthermore, a reverse bias voltage of 9V to 15V is applied during the laser induced contact treatment.

[0027] Further, the step of subjecting the electrode precursor to laser induced contact treatment includes applying a reverse bias voltage, and the conditions of the laser induced contact treatment include: a single wavelength spectrum with a wavelength of 500nm to 1200nm, a current density of 1000A / cm 2 ~1400A / cm 2 , the scanning rate is 35m / s~55m / s.

[0028] Furthermore, the method for preparing the gold semi-contact structure further comprises: performing light injection after the step of pre-sintering the electrode slurry at high temperature and before the step of performing laser induced contact treatment on the electrode precursor;

[0029] Alternatively, the method for preparing the gold semi-contact structure further comprises: performing light injection after the step of performing laser induced contact treatment on the electrode precursor.

[0030] Furthermore, the light injection step includes:

[0031] Heating the electrode precursor once, wherein the peak temperature of the heating once is 200° C. to 600° C.;

[0032] The electrode precursor is heated for a second time and irradiated with light, wherein the peak temperature of the second heating is 100°C to 300°C, and the energy density of the light irradiation is 10 kW / m 2 ~100kW / m 2 The wavelength of the light is a continuous spectral band of 500nm to 1200nm.

[0033] In a third aspect, the present application provides a solar cell, wherein the solar cell comprises the gold semi-contact structure as described in the first aspect, or comprises the gold semi-contact structure prepared by the preparation method as described in the second aspect.

[0034] Optionally, the solar cell includes a PERC cell, a HJT cell, a TOPCon cell, an IBC cell or a perovskite-crystalline silicon tandem solar cell.

[0035] In an optional embodiment, the solar cell is a TOPCon cell, and the solar cell comprises:

[0036] Silicon substrate;

[0037] On the light-receiving surface of the silicon substrate, a PN junction region, a first passivation layer, and a first metal electrode are sequentially provided in a direction away from the light-receiving surface, wherein the PN junction region is a first doped silicon-based semiconductor layer;

[0038] On the backlight surface of the silicon substrate, a passivation contact structure, a second passivation layer and a second metal electrode are sequentially arranged in a direction away from the backlight surface, wherein the passivation contact structure comprises a tunneling passivation layer arranged close to the silicon substrate and a doped silicon layer arranged away from the silicon substrate, the doped silicon layer has the same conductivity type as the silicon substrate, and the doped silicon layer is a second doped silicon-based semiconductor layer;

[0039] The first metal electrode penetrates part of the first passivation layer and contacts the first doped silicon-based semiconductor layer, so that the PN junction region and the first metal electrode form the gold semi-contact structure, and / or the second metal electrode penetrates the second passivation layer and contacts the doped silicon layer, so that the doped silicon layer and the second metal electrode form the gold semi-contact structure.

[0040] Further, the first doped silicon-based semiconductor layer is formed by thermally diffusing the doping element into the silicon substrate, or the first doped silicon-based semiconductor layer is a doped polysilicon layer or a doped amorphous silicon layer deposited on the light-receiving surface of the silicon substrate; and / or,

[0041] The first passivation layer is one or more of an aluminum oxide layer, a silicon oxide layer, a silicon oxynitride layer or a silicon nitride layer deposited on the PN junction region; and / or,

[0042] The tunnel passivation layer is at least one of a silicon oxide layer, an amorphous silicon layer, a polysilicon layer, and a silicon carbide layer; and / or,

[0043] The second passivation layer is one or more of a silicon oxide layer, a silicon oxynitride layer or a silicon nitride layer deposited on the second doped silicon-based semiconductor layer.

[0044] In an optional embodiment, the solar cell is a HJT cell, and the solar cell comprises:

[0045] Silicon substrate;

[0046] A first intrinsic amorphous silicon layer, a first doped silicon-based semiconductor layer, a first transparent conductive layer, and a first metal electrode disposed on the light-receiving surface of the silicon substrate are sequentially disposed on the light-receiving surface of the silicon substrate;

[0047] A second intrinsic amorphous silicon layer, a second doped silicon-based semiconductor layer, a second transparent conductive layer, and a second metal electrode disposed on the backlight surface of the silicon substrate are sequentially disposed on the backlight surface of the silicon substrate;

[0048] The gold semi-contact structure is formed between the first metal electrode and the first doped silicon-based semiconductor layer and the first transparent conductive layer, and / or the gold semi-contact structure is formed between the second metal electrode and the second doped silicon-based semiconductor layer and the second transparent conductive layer.

[0049] Further, the first intrinsic amorphous silicon layer includes one or more layers of an intrinsic amorphous silicon layer, a hydrogenated amorphous silicon layer, and a silicon oxide layer; and / or,

[0050] The first doped silicon-based semiconductor layer is one or more doped silicon layers; and / or,

[0051] The first transparent conductive layer is one or more of an indium tin oxide layer, an aluminum-doped zinc oxide layer, a zinc oxide layer, an indium oxide layer or a tin oxide layer; and / or,

[0052] The second intrinsic amorphous silicon layer includes one or more layers of an intrinsic amorphous silicon layer and a hydrogenated amorphous silicon layer; and / or,

[0053] The second doped silicon-based semiconductor layer is one or more doped silicon layers; and / or,

[0054] The second transparent conductive layer is one or more of an indium tin oxide layer, an aluminum-doped zinc oxide layer, a zinc oxide layer, an indium oxide layer or a tin oxide layer.

[0055] In an optional embodiment, the solar cell is a PERC solar cell, and the solar cell comprises:

[0056] Silicon substrate;

[0057] A first doped silicon-based semiconductor layer and a first passivation layer are sequentially formed on the light-receiving surface of the silicon substrate;

[0058] A first metal electrode penetrates the first passivation layer and forms the gold semi-contact structure with the first doped silicon-based semiconductor layer.

[0059] Further, the first doped silicon-based semiconductor layer is one or more doped silicon layers; and / or,

[0060] The solar cell also includes: a second doped silicon-based semiconductor layer and a back surface field passivation layer arranged in sequence on the backlight side of the silicon substrate, and a second metal electrode is also arranged on the backlight side of the silicon substrate, and the second metal electrode is in ohmic contact with the second doped silicon-based semiconductor layer.

[0061] In an optional embodiment, the solar cell is an IBC solar cell, and the solar cell comprises:

[0062] Silicon substrate;

[0063] A tunnel passivation layer, a first doped silicon-based semiconductor layer, a first passivation layer and a first metal electrode are sequentially arranged in the N-type conductive region of the backlight surface of the silicon substrate;

[0064] The tunnel passivation layer, the second doped silicon-based semiconductor layer, the second passivation layer and the second metal electrode are sequentially arranged in the P-type conductive region of the backlight surface of the silicon substrate; one of the first doped silicon-based semiconductor layer and the second doped silicon-based semiconductor layer has an N-type doping element and the other has a P-type doping element;

[0065] Among them, the first metal electrode penetrates the first passivation layer and contacts the first doped silicon-based semiconductor layer, so that the first metal electrode and the first doped silicon-based semiconductor layer form the gold semi-contact structure, and / or the second metal electrode penetrates the second passivation layer and contacts the second doped silicon-based semiconductor layer, so that the second metal electrode and the second doped silicon-based semiconductor layer form the gold semi-contact structure.

[0066] In a fourth aspect, the present application provides a method for preparing a solar cell string, comprising the following steps:

[0067] Welding a plurality of solar cells as described in the third aspect to form a cell string precursor;

[0068] The solar cell string is obtained by subjecting the cell string precursor to laser induced contact treatment.

[0069] Furthermore, in the step of subjecting the battery string precursor to laser induced contact treatment,

[0070] The reverse bias voltage is 10V to 50V; and / or,

[0071] The wavelength of the laser is 500nm to 1200nm; and / or,

[0072] The energy density of the laser is 10 kW / m 2 ~10000kW / m 2 and / or,

[0073] The scanning rate of the laser is 26 m / s to 65 m / s.

[0074] In a fifth aspect, the present application provides a solar cell string, which is manufactured by the method for manufacturing a solar cell string as described in the fourth aspect.

[0075] In a sixth aspect, the present application provides a photovoltaic module, comprising the solar cell string as described in the fifth aspect.

[0076] Compared with the prior art, this application has at least the following beneficial effects:

[0077] The embodiment of the present application provides a gold-semiconductor contact structure with a new structure, which has a rich variety of conductive structures and excellent conductivity, can effectively improve the contact performance between the metal electrode and the doped silicon-based semiconductor layer, reduce the contact resistance between the two, and improve the carrier transport capacity, so that the open circuit voltage, fill factor and photoelectric conversion efficiency of the solar cell are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0079] Figure 1 It is a schematic diagram of the structure of the first solar cell in the embodiment of the present application;

[0080] Figure 2 yes Figure 1 A magnified schematic diagram of the structure at center A;

[0081] Figure 3 is a schematic structural diagram of the first conductive region in the gold semiconductor contact structure of an embodiment of the present application;

[0082] Figure 4 is a schematic diagram of the structure of a second solar cell in an embodiment of the present application;

[0083] Figure 5 is a schematic diagram of the structure of a third solar cell in the embodiment of the present application;

[0084] Figure 6 is a schematic structural diagram of a fourth solar cell according to an embodiment of the present application;

[0085] Figure 7 This is a SEM image of the contact interface of the gold semi-contact structure in the solar cell of Example 1 of the present application;

[0086] Figure 8 yes Figure 7 A magnified schematic diagram of the central pit island.

[0087] Description of reference numerals:

[0088] 100, silicon substrate; 200, doped silicon-based semiconductor layer; 201, first doped silicon-based semiconductor layer; 202, second doped silicon-based semiconductor layer; 300, metal electrode; 301, first metal electrode; 302, second metal electrode; 400, passivation layer; 401, first passivation layer; 4011, aluminum oxide passivation layer; 4012, anti-reflection layer; 402, second passivation layer; 403, third passivation layer; 500, tunneling passivation layer; 601, first intrinsic amorphous silicon layer; 602, second intrinsic amorphous silicon layer; 701, first transparent conductive layer; 702, second transparent conductive layer; 800, back surface field passivation layer;

[0089] 1. Gold semi-contact structure; 11. First conductive region; 111. Pit island; 111a. Hole; 111b. Pit; 112. Silicon-based eutectic; 113. Conductive crystal; 1131. Crystalline main chain; 1132. Crystalline side chain; 12. Second conductive region; 121. Conductive aggregate; 1211. Glass phase material; 1212. Metallic conductive particles. DETAILED DESCRIPTION

[0090] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0091] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0092] In addition, some of the above terms may be used to express other meanings in addition to indicating a direction or position relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0093] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0094] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0095] The gold-semiconductor contact structure refers to the metal-semiconductor contact structure formed by the metal electrode and the semiconductor layer in the solar cell. Since the carriers need to be transmitted through the gold-semiconductor contact structure, the performance of the gold-semiconductor contact structure has an important influence on the performance indicators such as the photoelectric conversion efficiency of the solar cell.

[0096] In the related art, the contact resistance between the metal electrode and the semiconductor layer of the solar cell is not ideal. Therefore, the present application proposes a new gold-semiconductor contact structure and its preparation method, a solar cell, a solar cell string and its preparation method, and a photovoltaic module to further optimize the contact performance between the metal electrode and the semiconductor layer and reduce the contact resistance between the two.

[0097] Since the gold semi-contact structure of the embodiment of the present application is applied to solar cells (especially in crystalline silicon solar cells), the gold semi-contact structure and its preparation method will be introduced when introducing the solar cell of the embodiment of the present application below, and the gold semi-contact structure and its preparation method will not be described separately.

[0098] In a first aspect, the present application provides a solar cell having a gold semi-contact structure. Figure 1 As shown, Figure 1 Schematic diagram of the structure of the first solar cell of the present application embodiment, the solar cell comprises:

[0099] Silicon substrate 100;

[0100] A doped silicon-based semiconductor layer 200 and a passivation layer 400 are sequentially arranged on the surface of a silicon substrate 100;

[0101] The metal electrode 300 penetrates the passivation layer 400 and comes into physical contact with the doped silicon-based semiconductor layer 200 .

[0102] That is, the metal electrode 300 and the doped silicon-based semiconductor layer 200 in physical contact form a gold semi-contact structure 1 , where physical contact refers to direct contact between the structure of the metal electrode 300 and the structure of the doped silicon-based semiconductor layer 200 .

[0103] The doped silicon-based semiconductor layer 200 may be disposed on the light-receiving surface and / or the backlight surface of the silicon substrate 100, and correspondingly, the gold semi-contact structure 1 may also be disposed on the light-receiving surface and / or the backlight surface of the silicon substrate 100. Figure 1 As shown, the doped silicon-based semiconductor layer 200 includes a first doped silicon-based semiconductor layer 201 disposed on the light-receiving surface of the silicon substrate 100 and a second doped silicon-based semiconductor layer 202 disposed on the backlight surface of the silicon substrate 100; the passivation layer 400 includes a first passivation layer 401 disposed on the side of the first doped silicon-based semiconductor layer 201 away from the silicon substrate 100, and a second passivation layer 402 disposed on the side of the second doped silicon-based semiconductor layer 202 away from the silicon substrate 100; the metal electrode 300 includes a first metal electrode 301 in contact with the first doped silicon-based semiconductor layer 201, and a second metal electrode 302 in contact with the second doped silicon-based semiconductor layer 202. The first doped silicon-based semiconductor layer 201 is in contact with the first metal electrode 301 to form a gold semi-contact structure 1 located on the light-receiving surface of the silicon substrate 100. The second doped silicon-based semiconductor layer 202 is in contact with the second metal electrode 302 to form a gold semi-contact structure 1 located on the backlight surface of the silicon substrate 100.

[0104] The following takes the gold semi-contact structure 1 located on the light-receiving surface of the silicon substrate 100 as an example to further illustrate the gold semi-contact structure 1 of the embodiment of the present application.

[0105] Combination Figure 2 and Figure 3 As shown, Figure 2 yes Figure 1 The enlarged schematic diagram of the structure at A in the figure is also the structural schematic diagram of the metal semi-contact structure of the embodiment of the present application. Figure 3 It is a schematic structural diagram of the first conductive region in the gold semiconductor contact structure of an embodiment of the present application.

[0106] In the gold semi-contact structure 1, the first doped silicon-based semiconductor layer 201 has doping elements, and the first metal electrode 301 has metal elements. There is a contact region between the first doped silicon-based semiconductor layer 201 and the first metal electrode 301, and the contact region includes a first conductive region 11 and a second conductive region 12 outside the first conductive region 11.

[0107] In the first conductive region 11, the first metal electrode 301 in contact with the first doped silicon-based semiconductor layer 201 is recessed toward the first doped silicon-based semiconductor layer 201 (ie, Figure 2The upper surface of the first doped silicon-based semiconductor layer 201 is recessed downwards), forming Figure 7 The pit island 111 is shown in FIG.

[0108] There is a silicon-based eutectic 112 in the pit island 111, specifically, there are a plurality of silicon-based eutectics 112 in at least part of the pits in the pit island 111, and these silicon-based eutectics 112 are in conductive contact with the first doped silicon-based semiconductor layer 201. There is also a conductive crystal 113 conductively connected to the silicon-based eutectic 112 in the first conductive region 11. The silicon-based eutectic 112 includes a eutectic formed by the eutectic crystals of silicon and metal elements; the conductive crystal 113 extends from the silicon-based eutectic 112 toward the first metal electrode 301 (i.e. Figure 2 The conductive crystal 113 is formed by extending upward from the silicon-based eutectic 112, and the conductive crystal 113 includes a crystal formed by crystallization of a metal element.

[0109] The second conductive region 12 has a conductive aggregate 121, which includes a glass phase material 1211 and metal conductive particles 1212 distributed in the glass phase material 1211. The metal conductive particles 1212, the silicon-based eutectic 112, and the conductive crystal 113 all have the same metal element.

[0110] Compared with the gold semi-contact structure of the related art, the gold semi-contact structure 1 of the embodiment of the present application includes a conductive crystal 113 with higher conductivity, and a silicon-based eutectic 112 for improving the conductivity of semiconductor silicon materials, so that the conductivity of the hole or electron output conductive structure of the solar cell is significantly improved, thereby effectively improving the contact performance between the metal electrode 300 and the doped silicon-based semiconductor layer 200 by optimizing the conductive structure. It can be seen that by performing the above-mentioned improvement and optimization on the gold semi-contact structure 1, the contact performance between the doped silicon-based semiconductor layer 200 and the metal electrode 300 can be improved, the contact resistance can be reduced, and the carrier transport capacity can be improved, thereby effectively improving the open circuit voltage and photoelectric conversion efficiency of the solar cell.

[0111] The first conductive region 11 includes a silicon-based eutectic 112 and a conductive crystal 113 in conductive contact with the silicon-based eutectic 112. The silicon-based eutectic 112 exists in the doped silicon-based semiconductor layer 200 corresponding to the pit island 111. The silicon-based eutectic 112 includes a eutectic formed by metal elements and silicon elements, so that the silicon-based eutectic 112 is in conductive contact with the doped silicon-based semiconductor layer 200. This silicon-based eutectic 112 is a semiconductor silicon material doped with metal atoms with high conductivity, which can significantly improve the conductivity of the semiconductor silicon material, that is, the photogenerated carrier transport capacity of the silicon-based eutectic 112 is greatly improved, which has the effect of reducing the contact resistance between the metal electrode 300 and the doped silicon-based semiconductor layer 200.

[0112] At the same time, the conductive crystal 113 is formed epitaxially from the silicon-based eutectic 112 toward the metal electrode 300. The conductive crystal 113 includes a crystal formed by crystallization of a metal element, so that the conductive crystal 113 is in conductive contact with the silicon-based eutectic 112. Compared with the structure in which the metal conductive particles 1212 are in contact with the semiconductor material, the conductive crystal 113 formed after the crystallization of the metal element has the characteristics of higher purity and higher conductivity, thereby reducing the series resistance of the solar cell and improving the photoelectric conversion efficiency.

[0113] It can be seen that in the first conductive region 11 of the embodiment of the present application, through the conductive contact between the doped silicon-based semiconductor layer 200 and the silicon-based eutectic 112, and the conductive contact between the silicon-based eutectic 112 and the conductive crystal 113, a first carrier transport path for photogenerated carriers in the contact region of the gold semi-contact structure 1 is formed: silicon substrate 100, doped silicon-based semiconductor layer 200, silicon-based eutectic 112 and conductive crystal 113.

[0114] Furthermore, in the conductive aggregate 121 , a portion of the metal conductive particles 1212 are located on the surface of the doped silicon-based semiconductor layer 200 , and another portion of the metal conductive particles 1212 are distributed in the glass phase material 1211 . The conductive aggregate 121 is in conductive contact with the doped silicon-based semiconductor layer 200 through the metal conductive particles 1212 .

[0115] It can be seen that in the second conductive region 12 of the present application embodiment, through the conductive contact between the doped silicon-based semiconductor layer 200 and the conductive aggregate 121, a second carrier transport path for photogenerated carriers in the contact interface region of the gold-semiconductor contact structure 1 is formed: the silicon substrate 100, the doped silicon-based semiconductor layer 200 and the conductive aggregate 121. After the photogenerated carriers generated in the silicon substrate 100 are transported to the doped silicon-based semiconductor layer 200, they can also be transported through the metal conductive particles 1212 that are in direct contact with the doped silicon-based semiconductor layer 200, wherein the conductive aggregate 121 contains a glass phase material 1211 with a relatively high resistivity, so the conductive performance of the second carrier transport path is weaker than that of the first carrier transport path.

[0116] The pit island 111 is further described below.

[0117] like Figure 7As shown, the pit island 111 includes a plurality of adjacent or connected holes 111a, and a plurality of pits 111b of varying depths extend from the periphery of the holes 111a. In the direction away from the holes 111a, the depression depth of the pits 111b gradually becomes shallower, forming a peripheral boundary of the pit island 111. When the boundary interval between two adjacent holes 111a in the pit island 111 does not exceed 200nm, the adjacent holes 111a belong to one pit island 111, wherein the boundary interval between two adjacent holes 111a is defined as the shortest connecting line distance between the boundaries of the two adjacent holes 111a.

[0118] Furthermore, the distribution density of the holes 111a is 1 / μm 2 ~50 / μm 2 The pore size of the hole 111a is 10nm~100nm.

[0119] The pit islands 111 are concentrated in a small area on the surface of the doped silicon-based semiconductor layer 200, and the surface of the area surrounded by the pit islands 111 has a higher roughness than the second conductive area 12. The above roughness can represent the degree of ablation of the passivation film layer corresponding to the doped silicon-based semiconductor layer 200, wherein the greater the roughness, the more serious the degree of ablation of the passivation film layer. Figure 7 and Figure 8 Taking the pit island 111 as an example, the roughness is higher at the hole 111a in the middle, indicating a higher degree of ablation of the passivation film layer, and even a more obvious corrosion of the doped silicon-based semiconductor layer; the pit 111b formed on the periphery of the hole 111a is also rougher than the surface of the second conductive region 12, and specifically, the surface of the doped silicon-based semiconductor layer is also corroded to a lesser extent. The silicon-based eutectic 112 exists in the pit island 111, so that the silicon-based eutectic 112 in the gold semi-contact structure 1 is distributed more and more densely. The silicon-based eutectic 112 and the conductive crystal 113 distributed in the pit island 111 are conducive to further reducing the contact resistance between the metal electrode 300 and the doped silicon-based semiconductor layer 200.

[0120] In addition, the surface of the doped silicon-based semiconductor layer 200 has a pyramid velvet structure, and the pit islands 111 are located at the top and / or near the top of the pyramid velvet structure, for example, at the side of the pyramid near the top.

[0121] The following takes the first metal electrode and the first doped silicon-based semiconductor layer as an example to further illustrate the metal electrode and the doped silicon-based semiconductor layer.

[0122] The first metal electrode 301 has a metal element, which means that the first metal electrode 301 has a material corresponding to the metal element as a main component. For example, when the first metal electrode 301 is a silver electrode, the main component of the first metal electrode 301 is the silver element. Preferably, the metal electrode 300 is a silver electrode. More preferably, the content of metal aluminum impurities in the silver electrode is less than 0.1wt%.

[0123] The first doped silicon-based semiconductor layer 201 has doping elements, which means that the main component of the first doped silicon-based semiconductor layer 201 is silicon, and a small amount of other doping elements are doped therein to enhance the transport capacity of the first doped silicon-based semiconductor layer 201 for electron carriers or hole carriers; for example, when the first doped silicon-based semiconductor layer 201 is a PN junction region, the main component of the first doped silicon-based semiconductor layer 201 is a silicon-based doped film layer with P-type doping or N-type doping. The PN junction region can be a diffused silicon layer formed by diffusing and doping doping elements of different types from the silicon substrate 100 into the silicon substrate 100, or a crystalline silicon layer doped with doping elements formed on the silicon substrate 100 by a deposition method (for example, an LPCVD deposition method or a PECVD deposition method). The doping elements include N-type doping elements or P-type doping elements, the N-type doping elements include at least one of phosphorus, antimony or arsenic, and the P-type doping elements include at least one of boron, indium or gallium. Exemplarily, the doping element is, for example, phosphorus or boron, which means that when the main component is a silicon layer, a certain concentration of the doping element can be added.

[0124] It should be noted that the contact area between the first doped silicon-based semiconductor layer 201 and the conductive crystal 113 corresponding to the pit island does not include a passivation layer, while the partial contact area between the first doped silicon-based semiconductor layer 201 and the conductive aggregate 121 corresponding to the second conductive area 12 includes a passivation layer.

[0125] Optionally, the first doped silicon-based semiconductor layer 201 is a doped silicon layer. The doped silicon layer includes at least one of a doped amorphous silicon layer, a doped polycrystalline silicon layer, a doped microcrystalline silicon layer or a doped crystalline silicon layer. When the first doped silicon-based semiconductor layer 201 includes a doped crystalline silicon layer, the doped crystalline silicon layer may be prepared by thermally diffusing the doping elements on crystalline silicon. For example, in a passivated contact solar cell, the first doped silicon-based semiconductor layer 201 may be a doped silicon layer, such as a doped amorphous silicon layer or a PN junction region (the PN junction region may be a diffused silicon layer formed on the silicon substrate 100 by high-temperature diffusion). Exemplarily, the silicon substrate 100 is an N-type silicon substrate 100, the first metal electrode 301 is a silver electrode, and the first doped silicon-based semiconductor layer 201 is a PN junction region formed by boron diffusion into the N-type silicon substrate 100. The above-mentioned gold semi-contact structure 1 is a contact structure formed by a silver electrode and a PN junction. In the conductive structure at the contact interface, the silicon-based eutectic 112 is a eutectic structure formed by silver atoms and silicon atoms, the conductive crystals 113 are crystals formed by the crystallization of silver atoms, that is, silver element in crystal form, and the conductive aggregate 121 includes a glass phase material 1211 and silver conductive particles, and the silver conductive particles are silver nanoparticles.

[0126] The conductive crystal 113 is further described below.

[0127] Further integration Figure 3 As shown, in the gold semi-contact structure 1 of the embodiment of the present application, the conductive crystal 113 includes a crystalline main chain 1131 and a crystalline side chain 1132 extending from the crystalline main chain 1131 in a growth direction different from the crystalline main chain 1131. In the embodiment of the present application, the crystalline main chain 1131 and the side chains growing laterally from the crystalline main chain 1131 make the conductive crystal 113 present a dendrite structure as a whole.

[0128] In addition, the size of the conductive crystals is 1 nm to 30 nm.

[0129] The preparation method of the above-mentioned gold semi-contact structure is further introduced below.

[0130] The method for preparing the gold semi-contact structure comprises the following steps:

[0131] Printing electrode paste on the first doped silicon-based semiconductor layer; the electrode paste includes glass phase material, metal conductive particles and organic carrier;

[0132] Pre-sintering the electrode slurry at high temperature to form pit islands on a portion of the surface of the first doped silicon-based semiconductor layer, and forming an electrode precursor on the first doped silicon-based semiconductor layer; wherein the electrode precursor includes a glass phase material and metal conductive particles wrapped in the glass phase material, and the sintering temperature is greater than or equal to the peak sintering temperature of the electrode slurry;

[0133] The electrode precursor is subjected to laser induced contact treatment to form a first metal electrode, and the above-mentioned gold-semiconductor contact structure is formed between the first metal electrode and the first doped silicon-based semiconductor layer.

[0134] The peak sintering temperature of the electrode slurry refers to the sintering temperature range in which the glass phase material in the electrode slurry can ablate the passivation film layer and make the metal conductive particles in the electrode slurry have a lower resistivity (less than 1.5mΩ·cm) after sintering. This sintering temperature range is usually defined by those skilled in the art as the peak sintering temperature of the electrode slurry. In addition, at this peak sintering temperature, the organic carrier in the electrode slurry has been basically decomposed or volatilized, so the electrode precursor formed after sintering mainly includes glass phase material and metal conductive particles wrapped in the glass phase material.

[0135] On this basis, the preparation method of the embodiment of the present application further performs laser induced contact treatment on the electrode precursor (a reverse bias voltage is applied during this process). On the one hand, the reverse bias voltage is used to further enhance the built-in electric field of the solar cell at the contact interface between the first doped silicon-based semiconductor layer and the electrode precursor. On the other hand, a large number of photogenerated carriers (i.e., electron-hole pairs) are generated through the laser induced contact treatment. Through the combined effect of these two aspects, the electron carriers and the hole carriers are separated by the electric field, and one of the charge carriers is rapidly transported to the first doped silicon-based semiconductor layer under the acceleration of the electric field (for example, when the first doped silicon-based semiconductor layer is exposed to the sun, the charge carriers are transported to the first doped silicon-based semiconductor layer under the acceleration of the electric field). When the conductor layer has a pyramid-shaped velvet structure, carriers are more easily transported to the top of the pyramid and the position near the top of the pyramid), and these carriers will generate a lot of heat when passing through the glass phase material with a larger resistivity; since the carriers are transported along the path with the highest conductivity, and the passivation layer at the top of the pyramid and the vicinity of the top of the pyramid is more easily bombarded by the deposited atoms in the process of forming the passivation layer, the passivation layer at the top of the pyramid and the vicinity of the top of the pyramid is thinner, and has a high conductivity that is more conducive to carrier transport than the non-top position in the pyramid structure. Therefore, pit islands usually appear at the top of the pyramid and the vicinity of the top of the pyramid in the area covered by the electrode grid lines of the solar cell.

[0136] In summary, in the preparation method of the gold semi-contact structure of the embodiment of the present application, by high-temperature pre-sintering of a specific electrode slurry and cooperating with laser induced contact treatment, a gold semi-contact structure with the aforementioned structural characteristics can be formed, and will not cause large-area corrosion to the passivation layer covering the surface of the doped silicon-based semiconductor layer, thereby making the gold semi-contact structure have an excellent surface passivation effect.

[0137] Furthermore, in the step of high-temperature pre-sintering the electrode slurry, the high-temperature (peak) sintering temperature is 700° C. to 850° C. Compared with the high-temperature pre-sintering operation in the related art, the embodiment of the present application adopts this high-temperature pre-sintering condition, but does not cause large-area corrosion on the surface of the doped silicon-based semiconductor layer.

[0138] Furthermore, in the step of laser-induced contact treatment of the electrode precursor, the voltage of the reverse bias voltage applied is 9V to 15V. For the carriers generated by the laser-induced contact treatment, the level of heat generated when passing through the contact interface between the first doped silicon-based semiconductor layer and the electrode precursor is closely related to the above-mentioned reverse bias voltage range. When the reverse bias voltage is within the above-mentioned range, it is beneficial to generate a higher heat of 1500K to 8000K when the carriers pass through the contact interface, and use this higher heat to decompose the glass phase material at the corresponding position, promote the appropriate expansion of the pit island, and provide space for more silicon-based eutectics to continue to grow. At the same time, the area where the metal electrode is located in the pit island will also generate pits due to the decomposition of the glass phase material, providing space for the growth of conductive crystals. Under the above-mentioned reverse bias voltage conditions, the glass phase material at the pit will be completely decomposed or mostly decomposed. When the reverse bias voltage is at a relatively small voltage value in the above range, the glass phase material at the pit will be mostly decomposed, with a small amount remaining, conductive crystals will still grow in the pit, and the volume proportion of the glass phase material will be reduced, so the cooperation between the pit and the conductive structure can still improve the carrier transport capacity of the first conductive region. Exemplarily, the reverse bias voltage is 9V, 10V, 11V, 12V, 13V, 14V or 15V.

[0139] Preferably, in the step of laser-induced contact treatment of the electrode precursor, the voltage of the reverse bias voltage applied is 11 V. Under the above preferred reverse bias voltage conditions, a high temperature of 1000K to 8000K can be generated at the contact interface. In addition to decomposing the glass phase material so that only conductive crystals or most of the conductive crystals are present in the pits, this instantaneous high temperature can also melt the metal conductive particles at the contact interface, so that the semiconductor atoms in the molten state and the metal atoms undergo mutual melting and diffusion to form a semiconductor silicon layer doped with metal atoms, thereby improving the carrier transport capacity of the silicon-based eutectic.

[0140] Further, in the step of applying a reverse bias voltage to the electrode precursor and performing a laser induced contact treatment, the conditions of the laser induced contact treatment include: a single wavelength spectrum with a wavelength of 500nm to 1200nm, a current density of 1000A / cm 2 ~1400A / cm 2 , the scanning rate is 35m / s~55m / s.

[0141] For the above-mentioned laser induced contact treatment conditions, a single wavelength laser is used to excite the photogenerated carriers of the first doped silicon-based semiconductor layer 201. Exemplarily, the wavelength of the injected laser in the laser induced contact treatment is 532nm, 635nm, 650nm, 808nm, 980nm or 1064nm. When the semiconductor element of the first doped silicon-based semiconductor layer 201 is silicon and laser is used for laser induced contact treatment, lasers with wavelengths of 1064nm and 808nm are preferably used.

[0142] Preferably, the method for preparing the gold semi-contact structure further comprises the step of performing light injection.

[0143] In one embodiment, light injection is performed after the step of pre-sintering the electrode slurry at high temperature and before the step of subjecting the electrode precursor to laser induced contact treatment. In another embodiment, light injection is performed after the step of subjecting the electrode precursor to laser induced contact treatment.

[0144] The light injection process is mainly to improve the passivation performance. The light injection annealing furnace process steps: the first step is to increase the temperature to activate the H atoms in the silicon nitride passivation film; the second step is to control the valence state of the H atoms through light irradiation, so that they combine with the recombination center (defect) in the P+ emitter and the N-type substrate to form a non-recombination center. Finally, a good passivation effect is achieved to achieve the purpose of improving the open circuit voltage and fill factor.

[0145] In addition, compared with the practice of light injection after the laser induced contact treatment step, the practice of pre-sintering the electrode slurry at high temperature, then light injection, and then laser induced contact treatment of the electrode precursor is more conducive to optimizing the performance of solar cells. This is because the light injection operation also has a certain amount of heat. When light injection is performed before the laser induced contact treatment of the electrode precursor, it can passivate the grain boundaries and defect states.

[0146] Furthermore, the light injection process adjusts the Fermi level change by temperature and light intensity, controls the total amount of hydrogen and the valence state to improve the passivation performance. The light injection step includes: heating the electrode precursor once, the peak temperature of the first heating is 200℃~600℃; heating the electrode precursor twice and irradiating with light, the peak temperature of the second heating is 100℃~300℃, and the energy density of the light is 10kW / m 2 ~100kW / m 2, the wavelength of the light is a continuous spectral band of 500nm to 1200nm. The light injection step controls the heating conditions and the light conditions within the above range, which can not only achieve a good passivation effect, but also avoid the situation where the glass phase material corrodes the first doped silicon-based semiconductor layer due to excessive heating temperature. It should be noted that in the light injection step of the embodiment of the present application, a continuous spectral band with a wavelength of 500nm to 1200nm is injected, which is different from the single-wavelength laser used in the laser induced contact treatment step.

[0147] The other structural film layers of the solar cell of the embodiment of the present application are further described below.

[0148] See back Figure 1 In the solar cell of the embodiment of the present application, the silicon substrate 100 has an N-type conductivity type or a P-type conductivity type, for example, the silicon substrate 100 is an N-type silicon wafer. The light-receiving surface of the silicon substrate 100 has a velvet structure, for example, a pyramid-shaped velvet structure. The velvet structure is provided to reduce the reflectivity of the surface of the silicon substrate 100 and increase the refraction and scattering of light inside the silicon substrate 100.

[0149] On the light-receiving surface of the silicon substrate 100, the first doped silicon-based semiconductor layer 201 may be a diffusion layer formed by diffusing N-type doping elements or P-type doping elements into the silicon substrate 100, or may be a doped polysilicon layer or a doped amorphous silicon layer formed on the light-receiving surface of the silicon substrate 100 by deposition. For example, the first doped silicon-based semiconductor layer 201 of the silicon substrate may be a boron diffusion layer, so that a PN junction is formed between the N-type silicon wafer and the first doped silicon-based semiconductor layer 201, and when the silicon substrate 100 has a velvet structure, it means that the surface of the first doped silicon-based semiconductor layer 201 also has the same velvet structure.

[0150] A first passivation layer 401 is also provided on the side of the first doped silicon-based semiconductor layer 201 facing away from the silicon substrate 100. The first passivation layer 401 includes one or a composite layer of aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride. Figure 1 In the solar cell shown, the first passivation layer 401 includes an aluminum oxide passivation layer 4011 disposed near the first doped silicon-based semiconductor layer 201 and an anti-reflection layer 4012 with an anti-reflection function disposed away from the first doped silicon-based semiconductor layer 201. The first metal electrode 301 sequentially penetrates the anti-reflection layer 4012 and the aluminum oxide passivation layer 4011 and contacts the first doped silicon-based semiconductor layer 201.

[0151] The above is an introduction to the structural film layer of the light-receiving surface of the solar cell. It is understandable that, according to the structural characteristics of different types of solar cells, film layers with other structural characteristics can also be set on the light-receiving surface and the backlight surface of the solar cell. For example, when the film layer on the backlight surface has a second metal electrode 302 and a second doped silicon-based semiconductor layer 202 in contact, the aforementioned gold semi-contact structure 1 can also be used. In addition, the method for forming the structural film layer can also adopt the conventional practices of the prior art. For example, a silicon substrate 100 with a velvet structure is obtained by texturing, and a first doped silicon-based semiconductor layer 201 with a PN junction is obtained by doping with doping elements by thermal diffusion doping, and a first passivation layer 401 is obtained by ALD or PECVD process, and so on. In addition, the embodiments of the present application can also adopt conventional practices such as polishing and cleaning according to the formation of the winding coating layer, borosilicate glass layer or phosphorus silicon glass layer in the process of forming each structural film layer, and the present application does not limit this.

[0152] by Figure 1 The solar cell shown is a TOPCON solar cell as an example. Along the direction away from the silicon substrate 100, a tunneling passivation layer 500, a second doped silicon-based semiconductor layer 202, a second passivation layer 402 and a patterned second metal electrode 302 are sequentially provided on the backlight surface of the silicon substrate 100. The second metal electrode 302 penetrates the second passivation layer 402 and contacts the second doped silicon-based semiconductor layer 202.

[0153] Among them, the material of the tunneling passivation layer 500 may include a variety of dielectric materials, such as at least one of silicon oxide, amorphous silicon, polycrystalline silicon, and silicon carbide. Specifically, the tunneling passivation layer 500 may be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation properties, can minimize the recombination loss of minority carriers on the surface of the semiconductor substrate, and is a film with excellent durability for subsequent high-temperature processes. The tunneling passivation layer 500 can also have a pinhole channel effect, allowing the carriers in the solar cell to move freely, and through the heavily doped polycrystalline silicon to produce selective passage of majority carriers, it is beneficial to reduce the recombination loss of minority carriers. Among them, the second doped silicon-based semiconductor layer 202 is a phosphorus-doped polycrystalline silicon layer, and the second passivation layer 402 is a passivation layer, and its material can be selected from any one material or any combination of materials of silicon oxide, aluminum oxide, silicon carbide, silicon nitride or silicon oxynitride layer.

[0154] Combination Figure 4 As shown, Figure 4 1 is a schematic diagram of the structure of the second solar cell of the embodiment of the present application, the solar cell is a HJT solar cell, and the solar cell includes:

[0155] Silicon substrate 100;

[0156] A first intrinsic amorphous silicon layer 601, a first doped silicon-based semiconductor layer 201, and a first transparent conductive layer 701 are sequentially arranged on the light-receiving surface of the silicon substrate 100;

[0157] A gold semi-contact structure 1 is formed between the first metal electrode 301 , the first doped silicon-based semiconductor layer 201 , and the first transparent conductive layer 701 .

[0158] The silicon substrate 100 has an N-type conductivity type or a P-type conductivity type, for example, the silicon substrate 100 is an N-type crystalline silicon layer. The light-receiving surface of the silicon substrate 100 has a velvet structure, for example, a pyramid-shaped velvet structure. The first intrinsic amorphous silicon layer 601 is one or more layers of superimposed intrinsic amorphous silicon layers and / or hydrogenated amorphous silicon layers. The first doped silicon-based semiconductor layer 201 is an N-type doped silicon layer or a P-type doped silicon layer, the doped silicon layer can be one or more layers, and the doped silicon layer can be a doped amorphous silicon layer or a doped microcrystalline silicon layer. The first transparent conductive layer 701 is one or more of an indium tin oxide layer, an aluminum-doped zinc oxide layer, a zinc oxide layer, an indium oxide layer or a tin oxide layer.

[0159] In an optional embodiment, the silicon substrate 100 is an N-type crystalline silicon layer, the first doped silicon-based semiconductor layer 201 is a P-type doped microcrystalline silicon layer or an N-type doped microcrystalline silicon layer, the first transparent conductive layer 701 is an indium tin oxide layer, and the first metal electrode 301 is a silver electrode.

[0160] When preparing the gold semi-contact structure 1, the laser-induced contact treatment instantly generates a local heat concentration point, and a large amount of heat instantly melts the doped microcrystalline silicon layer, the first transparent conductive layer 701 and the metallic silver particles in the electrode slurry, so that part of the silver atoms diffuse into the first transparent conductive layer 701 and the P-type doped microcrystalline silicon film in turn, and in the subsequent cooling process, a gold semi-contact structure 1 doped with silicon, indium tin oxide and silver atoms is formed.

[0161] It can be understood that the backlight surface of the silicon substrate 100 can have a structural film layer symmetrical to the light-receiving surface, that is, a second intrinsic amorphous silicon layer 602, a second doped silicon-based semiconductor layer 202 and a second transparent conductive layer 702 are sequentially arranged on the backlight surface of the silicon substrate 100, and a second metal electrode 302 is formed on the backlight surface, and a gold semi-contact structure 1 is formed between the second metal electrode 302, the second doped silicon-based semiconductor layer 202 and the second transparent conductive layer 702.

[0162] Combination Figure 5 As shown, Figure 5 1 is a schematic diagram of the structure of a third solar cell in an embodiment of the present application, wherein the solar cell is a PERC solar cell, and the solar cell comprises:

[0163] Silicon substrate 100;

[0164] A first doped silicon-based semiconductor layer 201 and a first passivation layer 401 are sequentially formed on the light-receiving surface of the silicon substrate 100;

[0165] A first metal electrode 301 penetrates the first passivation layer 401 and forms an ohmic contact with the first doped silicon-based semiconductor layer 201;

[0166] A gold semi-contact structure 1 is formed between the first metal electrode 301 and the first doped silicon-based semiconductor layer 201 .

[0167] Wherein, the silicon substrate 100 has an N-type conductivity type or a P-type conductivity type, for example, the silicon substrate 100 is a P-type silicon substrate 100. The light-receiving surface of the silicon substrate 100 has a velvet structure, for example, a pyramid-shaped velvet structure. The setting of the velvet structure is conducive to reducing the reflectivity of the surface of the silicon substrate 100 and increasing the refraction and scattering of light inside the silicon substrate 100. Wherein, the first doped silicon-based semiconductor layer 201 is an N-type doped silicon layer or a P-type doped silicon layer, and the doped silicon layer can be one layer or multiple layers. In an optional embodiment, the silicon substrate 100 is a P-type crystalline silicon layer, the first doped silicon-based semiconductor layer 201 is an N-type doped crystalline silicon layer, and the metal electrode 300 is a silver electrode.

[0168] It can be understood that the backlight surface of the silicon substrate 100 may have other structural film layers corresponding to the structural characteristics of the PERC cell, for example: a back surface field passivation layer 800 with negative charge properties is provided on the backlight surface of the silicon substrate 100, and the second metal electrode 302 on the backlight surface is provided on the side of the back surface field passivation layer 800 away from the silicon substrate 100, and the second metal electrode 302 is in ohmic contact with the second doped silicon-based semiconductor layer 202.

[0169] Combination Figure 6 As shown, Figure 6 : is a schematic diagram of the structure of the fourth solar cell of the embodiment of the present application, the solar cell is an IBC solar cell, and the solar cell includes:

[0170] Silicon substrate 100;

[0171] A tunneling passivation layer 500, a first doped silicon-based semiconductor layer 201 and a first passivation layer 401 are sequentially arranged in an N-type conductive region on a backlight surface of a silicon substrate 100, and a tunneling passivation layer 500, a second doped silicon-based semiconductor layer 202 and a second passivation layer 402 are sequentially arranged in a P-type conductive region on a backlight surface of the silicon substrate 100, wherein the first doped silicon-based semiconductor layer 201 has an N-type doping element, and the second doped silicon-based semiconductor layer 202 has a P-type doping element;

[0172] The first metal electrode 301 penetrates the first passivation layer 401 of the N-type conductive region and makes ohmic contact with the first doped silicon-based semiconductor layer 201, so that the first metal electrode 301 and the first doped silicon-based semiconductor layer 201 form a first metal-semiconductor contact structure 1;

[0173] The second metal electrode 302 penetrates the second passivation layer 402 of the P-type conductive region and makes ohmic contact with the second doped silicon-based semiconductor layer 202 , so that the second metal electrode 302 and the second doped silicon-based semiconductor layer 202 form a second metal-semiconductor contact structure 1 .

[0174] The silicon substrate 100 has an N-type conductivity type or a P-type conductivity type, for example, the silicon substrate 100 is an N-type silicon substrate 100. The light-receiving surface of the silicon substrate 100 has a velvet structure, for example, a pyramid-shaped velvet structure. The velvet structure is provided to reduce the reflectivity of the surface of the silicon substrate 100 and increase the light trapping effect inside the silicon substrate 100. In addition, other structural film layers can be provided on the light-receiving surface of the silicon substrate 100 according to actual needs. For example, a third passivation layer 403 is provided on the light-receiving surface of the silicon substrate 100.

[0175] The embodiment of the present application also provides a fifth solar cell (not shown in the figure), which is a perovskite-crystalline silicon tandem solar cell, wherein the perovskite cell serves as the top cell, any one of the above-mentioned first to fourth solar cells, and only requires that a gold semi-contact structure consisting of a first conductive region having a conductive crystal and a silicon-based eutectic, and a second conductive region having a conductive aggregate be set on the backlight surface of the crystalline silicon bottom cell.

[0176] In a second aspect, an embodiment of the present application provides a method for preparing a solar cell string, comprising the following steps:

[0177] Welding a plurality of solar cells as described in the second aspect to form a cell string precursor;

[0178] The solar cell string is obtained by subjecting the cell string precursor to laser induced contact treatment.

[0179] When the present application welded solar cells with the aforementioned gold semi-contact structure, it was found that the performance of several solar cells in the embodiments of the present application was more significantly reduced after welding. After analysis and research, it was found that this was mainly because the conductive structures such as silicon-based eutectics and conductive crystals in the gold semi-contact structure that promote the improvement of contact performance are more likely to break, melt, etc. during the welding process of the solar cell string, which in turn reduces the conductivity of the solar cell. Therefore, after welding the solar cell string, the present application performs a laser-induced contact treatment operation on the formed cell string precursor again. Through this operation, the broken and melted silicon-based eutectics and conductive crystals are repaired, the carrier transport path is restored, and the contact performance of the gold semi-contact structure is ensured to be good, alleviating the problem of attenuation of photoelectric conversion efficiency caused by the solar cells being welded into solar cell strings.

[0180] Further, in the step of subjecting the battery string precursor to laser induced contact treatment,

[0181] The reverse bias voltage is 10V to 50V; and / or,

[0182] The wavelength of the laser is 500nm to 1200nm; and / or,

[0183] The energy density of the laser is 10kW / m 2 ~10000kW / m 2 and / or,

[0184] The scanning rate of the laser is 26m / s~65m / s.

[0185] In a third aspect, an embodiment of the present application provides a solar cell string, which is manufactured by the manufacturing method described in the second aspect.

[0186] In a fourth aspect, an embodiment of the present application provides a photovoltaic module, which includes the solar cell as described in the first aspect. The photovoltaic module is formed by connecting and packaging a plurality of the above solar cells in series and / or in parallel.

[0187] The present application is further described below in conjunction with more specific embodiments. In addition, the sodium hydroxide and TS40 additives, electrode slurry, etc. used in the following embodiments can all be purchased commercially. For example, the electrode slurry uses a commercially available DK-93T model of silver electrode slurry, and the Al content in the electrode slurry accounts for 0.05wt% to 0.10wt%, and the oxygen content accounts for 1.0wt% to 5.0wt%. Among them, the element content ratio in the silver electrode slurry can be tested by an energy dispersive spectrometer (EDS).

[0188] Example 1

[0189] This embodiment provides a solar cell with a gold semi-contact structure, and the preparation method thereof is as follows:

[0190] (1) Texturing: In a tank-type device, sodium hydroxide and TS40 additives with a volume ratio of 7:1 are used, the temperature is maintained at 80°C, and the time is 7 minutes to quickly texturize the silicon substrate, and the thinning amount is controlled to be 5μm silicon substrate;

[0191] (2) Boron diffusion: The textured silicon substrate is placed in a boron diffusion furnace and BCl3 is introduced at 850°C-1050°C for boron diffusion to form a boron diffusion layer;

[0192] (3) Alkali polishing: Use chain HF equipment to remove the borosilicate glass on the backlight surface of the silicon substrate due to boron expansion, and then use a slot-type alkali polishing machine to remove the PN junction on the backlight surface and edge of the silicon substrate;

[0193] (4) Preparation of tunnel passivation layer: using a tubular PECVD device to deposit a silicon oxide tunnel passivation layer on the backlit surface of the silicon substrate;

[0194] (5) Preparing a phosphorus-doped amorphous silicon layer: depositing a phosphorus-doped polysilicon layer on the tunnel passivation layer using a tubular PECVD device;

[0195] (6) Annealing: Annealing is carried out in a tubular annealing furnace;

[0196] (7) RCA cleaning: First, the phosphorus-doped polysilicon layer and its mask layer that are plated on the light-receiving surface are removed by chain equipment using hydrofluoric acid with a mass concentration of 5%, and then the film is transferred to a tank-type alkaline polishing machine to remove the coating on the light-receiving surface.

[0197] (8) Depositing a passivation layer: using an ALD device to deposit an aluminum oxide layer as a first passivation layer on the boron diffusion layer, and then using a PECVD device to deposit a silicon oxynitride layer as an anti-reflection layer on the aluminum oxide layer; using a PECVD device to deposit a silicon oxynitride layer as a second passivation layer on the phosphorus-doped polysilicon layer; wherein the first passivation layer, the anti-reflection layer, and the second passivation layer can all be understood as passivation layers disposed on the doped silicon-based semiconductor layer;

[0198] (9) Fabrication of gold semiconductor contact structure:

[0199] (9.1) screen printing electrode paste on the anti-reflection layer and the second passivation layer respectively;

[0200] (9.2) High temperature pre-sintering electrode slurry: Pre-sintering the electrode slurry at a sintering temperature of 800°C to form an electrode precursor;

[0201] (9.3) Light injection: The electrode precursor is heated at a peak temperature of 500°C in the first heating and at a peak temperature of 200°C in the second heating, and the energy density of the light is 50 kW / m 2 Next, a continuous spectrum band with a wavelength of 500nm to 1200nm is used for light injection;

[0202] (9.4) Applying a reverse bias voltage to the electrode precursor after light injection and performing laser induced contact treatment: Applying a reverse bias voltage to the electrode precursor and performing laser irradiation, so that the electrode precursor located on the light-receiving surface and / or the backlight surface is transformed into a first metal electrode and a second metal electrode, and the first metal electrode penetrates the anti-reflection layer and the first passivation layer and contacts with the boron diffusion layer to form a first gold semi-contact structure, and the second metal electrode penetrates the second passivation layer and contacts with the phosphorus-doped polysilicon layer to form a second gold semi-contact structure; wherein the reverse bias voltage is 15V, and the laser induced contact treatment conditions include: the laser wavelength is 1064nm, the current density is 1200A / cm 2 , the scanning rate is 40m / s.

[0203] The gold semi-contact structure in the solar cell of this embodiment was photographed by scanning electron microscope, and the following was obtained: Figure 7 SEM images shown.

[0204] Example 2

[0205] The difference between this embodiment and the first embodiment is that in the step of manufacturing the gold semi-contact structure, after the electrode paste is pre-sintered at high temperature, laser induced contact treatment is performed, and then light injection is performed.

[0206] Example 3

[0207] The difference between this embodiment and the first embodiment is that in the step of manufacturing the gold semi-contact structure, light injection is not performed.

[0208] Example 4

[0209] This embodiment provides a solar cell string, and the preparation method thereof comprises the following steps:

[0210] Six solar cells of Example 1 are welded in series to form a solar cell string precursor;

[0211] The solar cell string precursor is subjected to laser induced contact treatment to form a solar cell string; wherein the reverse bias voltage is 50V, and the laser induced contact treatment conditions include: the laser wavelength is 1064nm, the light energy density is 5000kW / m 2 , the scanning rate is 50m / s.

[0212] Performance test description:

[0213] Scanning Electron Microscope (SEM) test:

[0214] Using chemical etching methods, nitric acid is first used to corrode the blocky silver of the outermost metal electrode of the solar cell, exposing the glass phase material component used to burn through the passivation layer. Then hydrofluoric acid is used to corrode the glass phase material component layer, exposing the pit island located at the contact interface in the gold semi-contact structure. The corresponding SEM image is obtained by photographing it with a scanning electron microscope.

[0215] The above is a detailed introduction to the technical solutions disclosed in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core inventions of the embodiments of the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A gold semiconductor contact structure, characterized in that: include: doping a silicon-based semiconductor layer; A metal electrode, the metal electrode is in contact with the doped silicon-based semiconductor layer, and the metal electrode has a metal element; There is a contact region between the doped silicon-based semiconductor layer and the metal electrode, and the contact region includes a first conductive region and a second conductive region outside the first conductive region; In the first conductive region, the metal electrode is recessed toward the inside of the doped silicon-based semiconductor layer to form a pit island, wherein the pit island has a silicon-based eutectic, the silicon-based eutectic is in conductive contact with the doped silicon-based semiconductor layer, and the first conductive region also has a conductive crystal body conductively connected to the silicon-based eutectic, the silicon-based eutectic includes a eutectic formed by the co-crystallization of silicon element and the metal element; In the second conductive region, there is a conductive aggregate, the conductive aggregate includes a glass phase material and metal conductive particles, and the metal conductive particles have the same type of the metal element as the conductive crystals.

2. The gold semiconductor contact structure according to claim 1, characterized in that: A portion of the metal conductive particles are located on the surface of the doped silicon-based semiconductor layer, and another portion of the metal conductive particles are distributed in the glass phase material. The conductive aggregate is in contact with the doped silicon-based semiconductor layer through the metal conductive particles.

3. The gold semiconductor contact structure according to claim 1, characterized in that: The pit island includes a plurality of holes and pits located outside the holes.

4. The gold semiconductor contact structure according to claim 3, characterized in that: The distribution density of the holes is 1 / μm 2 ~50 / μm 2 and / or, The pores have a diameter of 10 nm to 100 nm.

5. The gold semiconductor contact structure according to claim 1, characterized in that: The surface of the area surrounded by the pit islands has a higher roughness than that of the second conductive area.

6. The gold semiconductor contact structure according to claim 1, characterized in that: The surface of the doped silicon-based semiconductor layer has a pyramid velvet structure, and the pit island is located at the top of the pyramid velvet structure or near the top of the pyramid velvet structure.

7. The gold semiconductor contact structure according to any one of claims 1 to 6, characterized in that: The metal material in the metal electrode includes a silver material; and / or, The doped silicon-based semiconductor layer includes one of a doped amorphous silicon layer, a doped polycrystalline silicon layer, a doped microcrystalline silicon layer or a doped crystalline silicon layer.

8. The gold semiconductor contact structure according to any one of claims 1 to 6, characterized in that: The conductive crystal includes a main crystal chain and side crystal chains extending from the main crystal chain in a direction different from the growth direction of the main crystal chain.

9. The gold semiconductor contact structure according to any one of claims 1 to 6, characterized in that: The size of the conductive crystal is 1 nm~30 nm.

10. A method for preparing a gold semi-contact structure, characterized in that: The gold semi-contact structure is the gold semi-contact structure according to any one of claims 1 to 9, and the preparation method of the gold semi-contact structure comprises the following steps: Printing electrode paste on the doped silicon-based semiconductor layer; the electrode paste comprises the glass phase material, the metal material and the organic carrier; Pre-sintering the electrode slurry at high temperature to form the pit islands on a portion of the surface of the doped silicon-based semiconductor layer, and forming an electrode precursor on the doped silicon-based semiconductor layer; wherein the electrode precursor includes the glass phase material and the metal conductive particles wrapped in the glass phase material; The electrode precursor is subjected to laser induced contact treatment to form the metal electrode, and the gold semi-contact structure is formed between the metal electrode and the doped silicon-based semiconductor layer.

11. The method for preparing a gold semi-contact structure according to claim 10, characterized in that: In the step of pre-sintering the electrode slurry at high temperature, the high temperature sintering temperature is 700°C to 850°C.

12. The method for preparing a gold semi-contact structure according to claim 10, characterized in that: During the laser induced contact treatment, a reverse bias voltage of 9 V to 15 V is applied.

13. The method for preparing a gold semi-contact structure according to claim 10, characterized in that: The conditions of the laser induced contact treatment include: a single wavelength spectrum with a wavelength of 500 nm to 1200 nm, a current density of 1000 A / cm 2 ~1400A / cm 2 , the scanning rate is 35m / s~55m / s.

14. The method for preparing a gold semi-contact structure according to claim 10, characterized in that: The method for preparing the gold semi-contact structure further comprises: performing light injection after the step of pre-sintering the electrode slurry at high temperature and before the step of performing laser induced contact treatment on the electrode precursor; Alternatively, the method for preparing the gold semi-contact structure further comprises: performing light injection after the step of performing laser induced contact treatment on the electrode precursor.

15. The method for preparing a gold semi-contact structure according to claim 14, characterized in that: The light injection step comprises: Heating the electrode precursor once, wherein the peak temperature of the heating once is 200° C. to 600° C.; The electrode precursor is heated for a second time and irradiated with light, wherein the peak temperature of the second heating is 100°C to 350°C, and the energy density of the light irradiation is 10 kW / m 2 ~100 kW / m 2 The wavelength of the light is a continuous spectral band of 500 nm to 1200 nm.

16. A solar cell, characterized in that: The solar cell comprises the gold semi-contact structure as claimed in any one of claims 1 to 9, or comprises the gold semi-contact structure prepared by the method for preparing the gold semi-contact structure as claimed in any one of claims 10 to 15.

17. The solar cell according to claim 16, characterized in that: The solar cell includes a PERC cell, a HJT cell, a TOPCon cell, an IBC cell or a perovskite-crystalline silicon tandem solar cell.

18. The solar cell according to claim 17, characterized in that: The solar cell is a TOPCon cell, and the solar cell comprises: Silicon substrate; On the light-receiving surface of the silicon substrate, a PN junction region, a first passivation layer, and a first metal electrode are sequentially provided in a direction away from the light-receiving surface, wherein the PN junction region is a first doped silicon-based semiconductor layer; On the backlight surface of the silicon substrate, a passivation contact structure, a second passivation layer and a second metal electrode are sequentially arranged in a direction away from the backlight surface, wherein the passivation contact structure comprises a tunneling passivation layer arranged close to the silicon substrate and a doped silicon layer arranged away from the silicon substrate, the doped silicon layer has the same conductivity type as the silicon substrate, and the doped silicon layer is a second doped silicon-based semiconductor layer; The first metal electrode penetrates part of the first passivation layer and contacts the first doped silicon-based semiconductor layer, so that the PN junction region and the first metal electrode form the gold semi-contact structure, and / or the second metal electrode penetrates the second passivation layer and contacts the doped silicon layer, so that the doped silicon layer and the second metal electrode form the gold semi-contact structure.

19. The solar cell according to claim 18, characterized in that: The first doped silicon-based semiconductor layer is formed by thermal diffusion of doping elements into the silicon substrate, or the first doped silicon-based semiconductor layer is a doped polysilicon layer or a doped amorphous silicon layer deposited on the light-receiving surface of the silicon substrate; and / or, The first passivation layer is one or more of an aluminum oxide layer, a silicon oxide layer, a silicon oxynitride layer or a silicon nitride layer deposited on the PN junction region; and / or, The tunnel passivation layer is at least one of a silicon oxide layer, an amorphous silicon layer, a polysilicon layer, and a silicon carbide layer; and / or, The second passivation layer is one or more of a silicon oxide layer, a silicon oxynitride layer or a silicon nitride layer deposited on the second doped silicon-based semiconductor layer.

20. The solar cell according to claim 17, characterized in that: The solar cell is a HJT cell, and the solar cell comprises: Silicon substrate; A first intrinsic amorphous silicon layer, a first doped silicon-based semiconductor layer, a first transparent conductive layer, and a first metal electrode disposed on the light-receiving surface of the silicon substrate are sequentially disposed on the light-receiving surface of the silicon substrate; A second intrinsic amorphous silicon layer, a second doped silicon-based semiconductor layer, a second transparent conductive layer, and a second metal electrode disposed on the backlight surface of the silicon substrate are sequentially disposed on the backlight surface of the silicon substrate; The gold semi-contact structure is formed between the first metal electrode and the first doped silicon-based semiconductor layer and the first transparent conductive layer, and / or the gold semi-contact structure is formed between the second metal electrode and the second doped silicon-based semiconductor layer and the second transparent conductive layer.

21. The solar cell according to claim 20, characterized in that: The first intrinsic amorphous silicon layer includes one or more layers of an intrinsic amorphous silicon layer, a hydrogenated amorphous silicon layer, and a silicon oxide layer; and / or, The first doped silicon-based semiconductor layer is one or more doped silicon layers; and / or, The first transparent conductive layer is one or more of an indium tin oxide layer, an aluminum-doped zinc oxide layer, a zinc oxide layer, an indium oxide layer or a tin oxide layer; and / or, The second intrinsic amorphous silicon layer includes one or more layers of an intrinsic amorphous silicon layer and a hydrogenated amorphous silicon layer; and / or, The second doped silicon-based semiconductor layer is one or more doped silicon layers; and / or, The second transparent conductive layer is one or more of an indium tin oxide layer, an aluminum-doped zinc oxide layer, a zinc oxide layer, an indium oxide layer or a tin oxide layer.

22. The solar cell according to claim 17, characterized in that: The solar cell is a PERC solar cell, and the solar cell comprises: Silicon substrate; A first doped silicon-based semiconductor layer and a first passivation layer are sequentially formed on the light-receiving surface of the silicon substrate; A first metal electrode penetrates the first passivation layer and forms the gold semi-contact structure with the first doped silicon-based semiconductor layer.

23. The solar cell according to claim 22, characterized in that: The solar cell also includes: a second doped silicon-based semiconductor layer and a back surface field passivation layer arranged in sequence on the backlight side of the silicon substrate, and a second metal electrode is also arranged on the backlight side of the silicon substrate, and the second metal electrode is in ohmic contact with the second doped silicon-based semiconductor layer.

24. The solar cell according to claim 17, characterized in that: The solar cell is an IBC solar cell, and the solar cell comprises: Silicon substrate; A tunnel passivation layer, a first doped silicon-based semiconductor layer, a first passivation layer and a first metal electrode are sequentially arranged in the N-type conductive region of the backlight surface of the silicon substrate; The tunnel passivation layer, the second doped silicon-based semiconductor layer, the second passivation layer and the second metal electrode are sequentially arranged in the P-type conductive region of the backlight surface of the silicon substrate; one of the first doped silicon-based semiconductor layer and the second doped silicon-based semiconductor layer has an N-type doping element and the other has a P-type doping element; Among them, the first metal electrode penetrates the first passivation layer and contacts the first doped silicon-based semiconductor layer, so that the first metal electrode and the first doped silicon-based semiconductor layer form the gold semi-contact structure, and / or the second metal electrode penetrates the second passivation layer and contacts the second doped silicon-based semiconductor layer, so that the second metal electrode and the second doped silicon-based semiconductor layer form the gold semi-contact structure.

25. A method for preparing a solar cell string, characterized in that: The following steps are involved: Welding a plurality of solar cells according to any one of claims 16 to 24 to form a cell string precursor; The solar cell string is obtained by subjecting the cell string precursor to laser induced contact treatment.

26. The method for preparing a solar cell string according to claim 25, characterized in that: In the step of subjecting the battery string precursor to laser induced contact treatment, The voltage of the applied reverse bias voltage is 10 V to 50 V; and / or, The wavelength of the laser is 500 nm to 1200 nm; and / or, The energy density of the laser is 10 kW / m 2 ~10000 kW / m 2 and / or, The scanning rate of the laser is 26 m / s~65 m / s.

27. A solar cell string, characterized in that: The solar cell string is manufactured by the method for manufacturing a solar cell string according to claim 25 or 26, and the solar cell string comprises the solar cells connected in series and / or in parallel.

28. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell string according to claim 25 or 26, or the photovoltaic module comprises the solar cell string according to claim 27.

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