Solar cell and method of manufacturing the same, photovoltaic module

Abstract

The application relates to the field of solar cells, and discloses a solar cell, a preparation method thereof and a photovoltaic module. The solar cell comprises a cell substrate, at least one side surface of the cell substrate is provided with a groove structure, and an electrode structure is arranged at the groove structure. The electrode structure comprises a conductive metal layer, the conductive metal layer comprises a first subpart and a second subpart connected with each other, the first subpart is filled in the groove structure, and the second subpart is exposed outside the cell substrate. An oxidation-resistant layer is coated on the surface of the second subpart, the oxidation resistance of the oxidation-resistant layer is higher than that of the conductive metal layer, the oxidation-resistant layer is prepared by placing the cell substrate containing the conductive metal layer in a reaction solution containing oxidation-resistant metal ions, and along the thickness direction of the cell substrate, the height H1 of the first subpart and the height H2 of the second subpart satisfy 1 <= H1 < 3 mu m and 5 <= H2 <= 15 mu m. The electrode structure on the solar cell has high stability and good current collection effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell, a preparation method thereof and a photovoltaic module. BACKGROUND

[0002] In the process of preparing the electrode structure of the solar cell, the process of preparing the anti-oxidation layer on the surface of the conductive metal layer by using the reaction solution containing the anti-oxidation metal ions may weaken the bonding ability of the conductive metal layer and the substrate of the solar cell, so that the electrode structure is prone to fall off from the substrate of the solar cell, which is not conducive to improving the structural stability of the electrode structure and affects the current collection effect of the electrode structure. SUMMARY

[0003] The embodiments of the present application disclose a solar cell, a preparation method thereof and a photovoltaic module, and the electrode structure of the solar cell has high stability and good current collection effect.

[0004] In a first aspect, the embodiments of the present application disclose a solar cell, which comprises:

[0005] a cell substrate, at least one side surface of the cell substrate being provided with a groove structure;

[0006] an electrode structure, the electrode structure being arranged at the groove structure, and the electrode structure comprising:

[0007] a conductive metal layer, the conductive metal layer comprising a first sub-part and a second sub-part connected with each other, the first sub-part being filled in the groove structure, and the second sub-part being exposed outside the cell substrate;

[0008] an anti-oxidation layer, the anti-oxidation layer being coated on the surface of the second sub-part, the anti-oxidation layer having higher anti-oxidation property than the conductive metal layer, and the anti-oxidation layer being configured to be prepared by placing the cell substrate containing the conductive metal layer in a reaction solution containing anti-oxidation metal ions;

[0009] wherein, along the thickness direction of the cell substrate, the height of the first sub-part is H1, and the height of the second sub-part is H2, the H1 satisfies 1 μm≤H1<3 μm, and the H2 satisfies 5 μm≤H2≤15 μm.

[0010] Further, the H1 and the H2 satisfy (1:15)≤H1:H2<(3:5).

[0011] Further, the second sub-part comprises:

[0012] An intermediate sub-portion is located on a side surface of the first sub-portion away from the battery base, and a position of the intermediate sub-portion corresponds to a range of a position where the first sub-portion is located.

[0013] An epitaxial sub-portion is arranged outwardly from the intermediate sub-portion, and the epitaxial sub-portion is in contact with the surface of the battery base outside the groove structure.

[0014] Further, along a thickness direction of the battery base, an average width of a projection of the groove structure is W, and a depth of the groove structure is H3, and the W and the H3 satisfy: H3:W=(1:20)~(3:10).

[0015] Further, the W satisfies: 10μm≤W≤50μm; and the H3 satisfies: 1μm≤H3<3μm.

[0016] Further, along a direction of the electrode structure pointing to the battery base, a cross section of the groove structure presents a structure of top wide and bottom narrow.

[0017] Further, a width of the top of the groove structure is W1, and a width of the bottom of the groove structure is W2, and the W1, the W2 satisfy: (6:5)~(9:5).

[0018] Further, the W1 satisfies: 15μm≤W1≤20μm, and the W2 satisfies: 8μm≤W2≤12μm.

[0019] Further, the groove structure comprises a first groove sub-structure and a second groove sub-structure, and the battery base comprises:

[0020] A silicon base, at least one side surface of the silicon base is provided with the first groove sub-structure;

[0021] A functional layer is arranged on the silicon base, and a surface of the functional layer away from the silicon base is provided with the second groove sub-structure, and a position of the second groove sub-structure corresponds to a position of the first groove sub-structure.

[0022] The first sub-portion of the conductive metal layer is filled in the second groove sub-structure, and the second sub-portion is exposed outside the functional layer.

[0023] Further, on the silicon base, the silicon base comprises a first region corresponding to a position of the first groove sub-structure, and a second region outside the first region;

[0024] The silicon base of the first region is provided with a micro-protrusion structure; and the silicon base of the second region is provided with a first pyramid structure.

[0025] Further, the micro-protrusion structure is a second pyramid structure.

[0026] wherein a distance between an apex of the second pyramid structure closest to a sidewall of the first groove sub-structure and the sidewall is less than 1 μm; and / or,

[0027] The apex of the second pyramid structure presents an arc structure.

[0028] Further, the micro-protrusion structure is a second pyramid structure, wherein an average side length of a base of the first pyramid structure is L1, and an average side length of a base of the second pyramid structure is L2, and the L2 is less than the L1.

[0029] Further, the L1 and the L2 satisfy: (L1-L2) / L1=(1:4)~(7:20).

[0030] Further, the L1 satisfies: 1 μm≤L1≤3 μm, and the L2 satisfies: 0.75 μm≤L2≤2.2 μm.

[0031] Further, a metal material of the conductive metal layer comprises at least one of copper and aluminum; and / or,

[0032] A thickness of the anti-oxidation layer is 1 μm~5 μm; and / or,

[0033] A metal material of the anti-oxidation layer comprises at least one of tin, silver and gold.

[0034] Further, the silicon substrate comprises a light-receiving surface and a back light surface arranged oppositely, the first groove sub-structure is arranged on the light-receiving surface and the back light surface, the electrode structure comprises a first electrode structure and a second electrode structure, and the functional layer comprises:

[0035] A first passivation layer arranged on the silicon substrate on the light-receiving surface;

[0036] A first doped silicon layer arranged on a side surface of the first passivation layer away from the silicon substrate;

[0037] A first transparent conductive layer arranged on a side surface of the first doped silicon layer away from the first passivation layer, and the first electrode structure is in ohmic contact with the first transparent conductive layer;

[0038] A second passivation layer arranged on the silicon substrate on the back light surface;

[0039] a second doped silicon layer disposed on a side surface of the second passivation layer away from the silicon substrate;

[0040] a second transparent conductive layer disposed on a side surface of the second doped silicon layer away from the second passivation layer, the second electrode structure being in ohmic contact with the second transparent conductive layer;

[0041] wherein one of the first doped silicon layer and the second doped silicon layer is an N-type doped layer and the other is a P-type doped layer, and one of the first electrode structure and the second electrode structure is a positive electrode and the other is a negative electrode.

[0042] In a second aspect, the embodiments of the present application disclose a preparation method of a solar cell, which comprises the following steps:

[0043] slotting at least one side surface of the cell substrate to form a groove structure on the cell substrate;

[0044] preparing a conductive metal layer on the groove structure, the conductive metal layer comprising a first sub-portion and a second sub-portion connected to each other, the first sub-portion being filled in the groove structure, and the second sub-portion being exposed outside the cell substrate, placing the cell substrate containing the conductive metal layer in a reaction solution containing metal ions to prepare an anti-oxidation layer, and the anti-oxidation layer having a higher anti-oxidation property than the conductive metal layer, to obtain an electrode structure;

[0045] wherein, along the thickness direction of the cell substrate, the height of the first sub-portion is H1, and the height of the second sub-portion is H2, the H1 satisfies 1 μm≤H1<3 μm, and the H2 satisfies 5 μm≤H2≤15 μm.

[0046] Further, in the step of slotting at least one side surface of the cell substrate, the at least one side surface of the cell substrate is slotted by laser processing, wherein the parameters of the laser include: pulse width of 7 ps to 15 ps, ultraviolet light with wavelength of 350 nm to 360 nm, frequency of 50 kHz to 300 kHz, and pulse energy of 3 μJ to 15 μJ.

[0047] Further, the step of obtaining the electrode structure comprises:

[0048] printing paste on the groove structure by screen printing, so that part of the paste is filled in the interior of the groove structure to form the first sub-portion, and the remaining part of the paste is exposed outside the groove structure to form the second sub-portion; and the conductive metal layer is obtained after drying and vacuum curing of the paste;

[0049] light injection;

[0050] placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions to prepare the oxidation-resistant layer.

[0051] Further, the oxidation-resistant layer is prepared on the conductive metal layer by electroless tin plating at a temperature of 60-80°C for 30-300 s, and the electroless tin plating solution comprises a tin salt, an acid regulator, a reducing agent, and an additive for changing the potential value when the conductive metal layer reacts with the tin salt.

[0052] In the electroless tin plating solution, the tin salt has a mass concentration of 10-20 g / L, the acid regulator has a volume percentage of 5-10%, the reducing agent has a mass concentration of 10-30 g / L, and the additive has a mass concentration of 0.1-1 g / L.

[0053] Further, the tin salt is at least one of stannous chloride, stannous citrate, and stannous tartrate; and / or,

[0054] the acid regulator is sulfuric acid; and / or,

[0055] the reducing agent is sodium hypophosphite; and / or,

[0056] the additive is thiourea.

[0057] Further, after the light injection step and before the step of placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions to prepare the oxidation-resistant layer, the preparation method further comprises cleaning the conductive metal layer.

[0058] Further, the battery substrate comprises a silicon substrate and a functional layer disposed on the silicon substrate, the groove structure comprises a first groove substructure and a second groove substructure, and the step of grooving at least one side surface of the battery substrate comprises:

[0059] grooving at least one side surface of the silicon substrate to form the first groove substructure on the silicon substrate;

[0060] preparing the functional layer on the silicon substrate, the functional layer being provided with a second groove substructure on a surface thereof facing away from the silicon substrate, and the second groove substructure corresponding in position to the first groove substructure;

[0061] wherein the first subpart of the conductive metal layer is filled in the second groove substructure, and the second subpart is exposed outside the functional layer.

[0062] Further, the silicon substrate comprises a first region corresponding to the first recess substructure position, and a second region outside the first region;

[0063] After the step of slotting at least one side surface of the silicon substrate, and before the step of preparing the functional layer on the silicon substrate, the preparation method further comprises: cleaning and texturing the silicon substrate to form first pyramid structures on the silicon substrate in the second region, and to form second pyramid structures on the silicon substrate in the first region, wherein the distance between the tip of the second pyramid structure closest to the sidewall of the first recess substructure and the sidewall is less than 1 μm.

[0064] Further, the silicon substrate comprises a light-receiving surface and a back surface arranged opposite to each other, and the light-receiving surface and the back surface of the silicon substrate are respectively subjected to the slotting treatment to form the first recess substructure on the light-receiving surface and the back surface of the silicon substrate, and the electrode structure comprises a first electrode structure and a second electrode structure;

[0065] The step of preparing the functional layer on the silicon substrate comprises:

[0066] A first passivation layer is prepared on the light-receiving surface of the silicon substrate;

[0067] A second passivation layer is prepared on the back surface of the silicon substrate;

[0068] A first doped silicon layer is prepared on the first passivation layer;

[0069] A second doped silicon layer is prepared on the second passivation layer;

[0070] A first transparent conductive layer is prepared on the first doped silicon layer;

[0071] A second transparent conductive layer is prepared on the second doped silicon layer;

[0072] The first electrode structure is in ohmic contact with the first transparent conductive layer; the second electrode structure is in ohmic contact with the second transparent conductive layer; one of the first doped silicon layer and the second doped silicon layer is an N-type doped layer, and the other is a P-type doped layer; one of the first electrode structure and the second electrode structure is a positive electrode, and the other is a negative electrode.

[0073] In a third aspect, the embodiments of the present application disclose a photovoltaic module, comprising the solar cell of any one of the first aspect, or the solar cell prepared by the preparation method of any one of the second aspect.

[0074] Compared with the prior art, the application has the beneficial effects that the application provides a solar cell and a preparation method thereof and a photovoltaic module, the solar cell has a groove structure on at least one side surface of a cell substrate, and the relationship between H1 and H2 in the conductive metal layer at the groove structure is controlled, so that the electrode structure has high stability and good current collection effect.

[0075] Specifically, the electrode structure of the application includes a conductive metal layer and an oxidation-resistant layer covering the surface of the conductive metal layer, wherein the conductive metal layer includes a first subpart inside the groove structure and a second subpart outside the groove structure, and because the oxidation resistance of the oxidation-resistant layer is higher than that of the conductive metal layer, the oxidation-resistant layer can effectively prevent the oxidation and erosion of the second subpart by the external environment, thereby helping to ensure the structural stability of the second subpart.

[0076] However, because the oxidation-resistant layer is prepared by placing the cell substrate containing the conductive metal layer in a reaction solution containing oxidation-resistant metal ions, this may affect the bonding tightness of the cell substrate and the first subpart, and if the bonding performance of the cell substrate and the first subpart decreases, the conductive metal layer may fall off from the cell substrate, thereby affecting the performance of the electrode structure.

[0077] Therefore, by setting H1 in a specific range, the height of the first subpart filled in the groove structure is appropriate, thereby effectively preventing the reaction solution containing oxidation-resistant metal ions from penetrating downward, avoiding the corrosion of the bottom of the conductive metal layer by the reaction solution, and helping to avoid the falling off of the electrode structure; and it also helps to increase the contact area between the sidewall of the groove structure and the electrode structure, improve the contact tightness between the groove structure and the electrode structure, and further improve the connection stability of the first subpart and the cell substrate; in addition, the specific range of H1 can effectively avoid affecting the performance of the cell substrate, thereby ensuring the performance of the solar cell to a higher degree.

[0078] Furthermore, by setting H2 in a specific range, the oxidation-resistant layer and the second subpart can form an effective cooperation to jointly enhance the protection effect of the second subpart. This is because the appropriate height makes the area of the second subpart exposed outside the groove structure appropriate, which helps to reduce the protection pressure of the oxidation-resistant layer, so that the oxidation-resistant layer can fully play its role, avoiding the problem of local protection failure due to large protection area, and further improving the structural stability of the second subpart under the synergistic effect of the two. In addition, the above structure makes the second subpart have high structural stability, which provides a stable basis for the welding of the solder strip and ensures the effectiveness of the solder strip welding to a higher degree.

[0079] That is, the H1, H2 and the setting mode of the anti-oxidation layer of the present application have higher relevance, and through the cooperation of the three, it helps to ensure the connection stability of the first sub-department and the battery base, and can optimize the protection effect of the anti-oxidation layer on the second sub-department, and improve the stability of the solder strip welding.

[0080] In addition, the synergistic effect between H1 and H2 not only ensures the structural stability of the electrode structure, but also helps to reduce the resistance of the electrode structure. This is because H1 and H2 jointly affect the volume of the electrode structure, and by setting H1 and H2 within the above range, the volume of the electrode structure is appropriate, thereby helping to reduce the resistance of the electrode structure and optimizing the collection effect of the electrode structure on the carriers. BRIEF DESCRIPTION OF DRAWINGS

[0081] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0082] Figure 1 is a structural schematic diagram of a first battery base provided by the embodiments of the present application;

[0083] Figure 2 is a structural schematic diagram of a first solar cell provided by the embodiments of the present application;

[0084] Figure 3 is a structural schematic diagram of a second solar cell provided by the embodiments of the present application;

[0085] Figure 4 is a structural schematic diagram of a second battery base provided by the embodiments of the present application;

[0086] Figure 5 is a structural schematic diagram of a third battery base provided by the embodiments of the present application;

[0087] Figure 6 is a structural schematic diagram of a third solar cell provided by the embodiments of the present application;

[0088] Figure 7 is a structural schematic diagram of a first heterojunction solar cell provided by the embodiments of the present application;

[0089] Figure 8 is a structural schematic diagram of a fourth solar cell provided by the embodiments of the present application;

[0090] Figure 9 is Figure 8 is a partial enlarged view of A-A in FIG. 16;

[0091] Figure 10 is a structural schematic diagram of a second heterojunction solar cell provided by an embodiment of the present application;

[0092] Figure 11 is a structural schematic diagram of a third heterojunction solar cell provided by an embodiment of the present application.

[0093] Icon: 1, cell substrate; 1a, groove structure; 11a, first groove substructure; 12a, second groove substructure; 11, silicon substrate; 111, first pyramid structure; 112, second pyramid structure; 12, functional layer; 121, first passivation layer; 122, first doped silicon layer; 123, first transparent conductive layer; 124, second passivation layer; 125, second doped silicon layer; 126, second transparent conductive layer; 2, electrode structure; 2a, first electrode structure; 2b, second electrode structure; 21, conductive metal layer; 211, first subpart; 212, second subpart; 2121, middle subpart; 2122, epitaxial subpart; 22, oxidation-resistant layer. DETAILED DESCRIPTION

[0094] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0095] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship 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.

[0096] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned part of the terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. Those of ordinary skill in the art can understand the specific meaning of these terms in the present application according to the specific situation.

[0097] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and configurations can be the same or different), and are not intended to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise stated, the meaning of "a plurality" is two or more.

[0098] The technical solutions provided by the present application will be further described below in combination with embodiments and drawings.

[0099] In order to lead the photo-generated carriers out to the external circuit to generate current, an electrode structure is usually provided in a solar cell. The electrode structure in the conventional technology is usually prepared by using conductive silver paste as raw material and through the process of screen printing, but the cost of conductive silver paste is extremely high. In order to reduce cost and increase efficiency, a metal with lower cost such as copper can be used as electrode material to prepare a conductive metal layer on a solar cell semi-finished product, but the oxidation resistance of copper and other electrode materials is poor, which is easy to react with oxygen, thereby leading to the decrease of the stability of the electrode structure and the increase of the contact resistance, so that the photoelectric conversion performance of the solar cell is poor.

[0100] Although the conductive metal layer can be placed in a reaction solution containing anti-oxidation metal ions to react, so as to prepare an anti-oxidation layer on the conductive metal layer, and the anti-oxidation performance of the anti-oxidation layer is used to improve the structural stability of the conductive metal layer. However, this method of preparing the anti-oxidation layer has etching effect on the reaction solution containing the anti-oxidation metal ions, so that the reaction solution etches the connection between the conductive metal layer and the battery base, thereby leading to the falling off of the conductive metal layer from the battery base and the damage of the performance of the electrode structure.

[0101] Based on the above problems, the embodiments of the present application provide a solar cell and a preparation method thereof and a photovoltaic module, and the solar cell can effectively ensure high stability of the electrode structure and good current collection effect.

[0102] The embodiments of the present application disclose a solar cell, as shown in Figures 1 to 7 The solar cell comprises:

[0103] A battery base 1, at least one side surface of the battery base 1 is provided with a groove structure 1a;

[0104] An electrode structure 2, the electrode structure 2 is arranged at the groove structure 1a, and the electrode structure 2 comprises:

[0105] A conductive metal layer 21, the conductive metal layer 21 comprises a first sub-portion 211 and a second sub-portion 212 connected with each other, the first sub-portion 211 is filled in the groove structure 1a, and the second sub-portion 212 is exposed outside the battery base 1;

[0106] The anti-oxidation layer 22 is coated on the surface of the second sub-portion 212, the anti-oxidation property of the anti-oxidation layer 22 is higher than that of the conductive metal layer 21, and the anti-oxidation layer 22 is configured to be prepared by placing the battery substrate 1 containing the conductive metal layer 21 in a reaction solution containing anti-oxidation metal ions;

[0107] In the thickness direction (see Y direction in FIG. 1) of the battery substrate 1, the height of the first sub-portion 211 is H1, and the height of the second sub-portion 212 is H2, H1 satisfies 1 μm≤H1<3 μm, and H2 satisfies 5 μm≤H2≤15 μm. Figure 2

[0108] The battery substrate 1 represents a semi-finished product that has been prepared with other functional film layers but lacks the electrode structure 2, that is, the battery substrate 1 includes the silicon substrate 11 and the functional layer 12 arranged on the silicon substrate 11, and the groove structure 1a can be arranged on the silicon substrate 11 or on the functional layer 12. When the groove structure 1a is arranged on the silicon substrate 11, due to the form retention property, the functional layer 12 will form a recess structure at the corresponding position of the groove structure 1a, and the recess structure has the same characteristics as the groove structure 1a. Alternatively, the battery substrate 1 can be a semi-finished product of a passivated contact solar cell, a semi-finished product of a heterojunction solar cell, or a semi-finished product of a back contact solar cell.

[0109] In addition, the anti-oxidation property of the anti-oxidation layer 22 is higher than that of the conductive metal layer 21, that is, the stability of the anti-oxidation metal ions in the anti-oxidation layer 22 is relatively high, and the anti-oxidation metal ions are difficult to react with oxygen in the air and the like, while the stability of the metal ions in the conductive metal layer 21 is relatively low, and the metal ions in the conductive metal layer 21 are extremely easy to react with oxidizing substances in the air and the like. Alternatively, when the metal ions in the conductive metal layer 21 include at least one of copper ions and aluminum ions, the anti-oxidation metal ions include at least one of tin ions, silver ions, and gold ions. The present application does not limit the types of the anti-oxidation metal ions and the metal ions in the conductive metal layer 21, as long as the anti-oxidation property of the anti-oxidation layer 22 is higher than that of the conductive metal layer 21, so that the anti-oxidation layer 22 can protect the conductive metal layer 21 and prevent the conductive metal layer 21 from being exposed and oxidized.

[0110] The preparation method of the anti-oxidation layer 22 includes a chemical method or an electroplating method, and when the two methods are used, a reaction solution containing anti-oxidation metal ions is used. For example, when the anti-oxidation metal ions are tin ions, when chemical tin plating or electroplating tin is used, the chemical solution in the chemical tin plating and the electroplating solution in the electroplating tin both contain tin ions. The present application does not limit the specific preparation method of the anti-oxidation layer 22, as long as the effect of the present application can be achieved.

[0111] ​The electrode structure 2 of the present application comprises the conductive metal layer 21 and the oxidation-resistant layer 22 covering the surface of the conductive metal layer 21, wherein the conductive metal layer 21 comprises the first sub-part 211 inside the groove structure 1a and the second sub-part 212 outside the groove structure 1a, and the oxidation-resistant layer 22 can effectively prevent the oxidation and erosion of the second sub-part 212 by the external environment due to the higher oxidation resistance of the oxidation-resistant layer 22 than the conductive metal layer 21, thereby helping to ensure the structural stability of the second sub-part 212.

[0112] However, the applicant finds that the oxidation-resistant layer 22 is prepared by placing the battery substrate 1 containing the conductive metal layer 21 in a reaction solution containing oxidation-resistant metal ions, which may affect the tightness of the combination of the battery substrate 1 and the first sub-part 211.

[0113] Therefore, the present application sets the H1 in a specific value range to make the height of the first sub-part 211 filled inside the groove structure 1a appropriate, and then block the downward penetration of the reaction solution containing oxidation-resistant metal ions due to the appropriate height, avoid the corrosion of the bottom of the conductive metal layer 21 by the reaction solution, thereby helping to avoid the falling off of the electrode structure 2; and also help to increase the contact area of the side wall of the groove structure 1a and the electrode structure 2, further improve the contact tightness of the groove structure 1a and the electrode structure 2, and optimize the structural stability of the first sub-part 211; in addition, the H1 in a specific value range can also avoid affecting the performance of the battery substrate 1 itself, thereby helping to improve the performance of the solar cell to a higher degree.

[0114] In addition, by setting the H2 in a specific range, the oxidation-resistant layer 22 and the second sub-part 212 can form an effective cooperation to jointly strengthen the protection effect of the second sub-part 212, because the appropriate height makes the area of the second sub-part 212 exposed outside the groove structure 1a appropriate, helps to reduce the protection pressure of the oxidation-resistant layer 22, so that the oxidation-resistant layer 22 can fully play its role, avoid the problem of local protection failure caused by large protection area, and then under the synergistic effect of the two, the structural stability of the second sub-part 212 is improved to a higher degree. In addition, the above structure makes the second sub-part 212 have higher structural stability, which provides a stable basis for the welding of the solder strip and ensures the effectiveness of the solder strip welding to a higher degree.

[0115] In addition, the synergy between H1 and H2 not only ensures the structural stability of the electrode structure 2, but also helps to reduce the resistance of the electrode structure 2. This is because H1 and H2 jointly affect the volume of the electrode structure 2, and by setting H1 and H2 within the above range, the volume of the electrode structure 2 is appropriate, thereby helping to reduce the resistance of the electrode structure 2 and optimizing the collection effect of the electrode structure 2 on the charge carriers. For example, H1 is 1 μm, 1.5 μm, 2 μm, 2.5 μm, 2.9 μm, etc.; H2 is 5 μm, 7 μm, 9 μm, 11 μm, 15 μm, etc.

[0116] In summary, the synergy of H1, H2 and the oxidation-resistant layer 22 jointly solves the corrosion protection of the first sub-part 211 and the bonding strength of the battery base 1, the environmental resistance and welding reliability of the second sub-part 212, and further helps to improve the structural stability of the electrode structure 2 and improve the transmission capacity of the electrode structure 2 to the charge carriers.

[0117] In addition, the thickness of the oxidation-resistant layer 22 is 1 μm to 5 μm. When the thickness of the oxidation-resistant layer 22 is within the above range, it is more helpful to improve the protection performance of the oxidation-resistant layer 22, thereby improving the stability of the electrode structure 2 to a higher degree. For example, the thickness of the oxidation-resistant layer 22 is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0118] Further, H1 and H2 satisfy (1:15)≤H1:H2<(3:5), preferably (7:20)≤H1:H2<(3:5). When H1 and H2 are within the above range, especially within the preferred range, there is a higher matching between H1 and H2, which is more helpful to improve the structural stability of the electrode structure 2 and improve the collection capacity of the electrode structure 2 to the charge carriers. For example, H1:H2 is 1:15, 1:5, 7:20, 1:2, 23:50, etc.

[0119] In an alternative embodiment, referring back to Figure 2 The position of the second sub-part 212 corresponds to the position of the first sub-part 211, i.e. along the thickness direction of the battery base 1, the orthographic projection of the second sub-part 212 is located within the orthographic projection of the first sub-part 211. In another alternative embodiment, as Figure 3As shown, the second sub-part 212 comprises: a middle sub-part 2121, which is located on the side surface of the battery substrate 1 away from the first sub-part 211, and the position of the middle sub-part 2121 corresponds to the range of the position where the first sub-part 211 is located; and an extension sub-part 2122, which is arranged outwardly from the middle sub-part 2121, and the extension sub-part 2122 is in contact with the surface of the battery substrate 1 outside the groove structure 1a. In this embodiment, since the second sub-part 212 comprises the extension sub-part 2122 and the middle sub-part 2121, this arrangement helps to better avoid the reaction solution from flowing in from the edge gap between the middle sub-part 2121 and the groove structure 1a, thereby helping to further improve the bonding effect of the battery substrate 1 and the electrode structure 2; and also helps to reduce the difficulty of processing and improve the effectiveness of processing.

[0120] Further, referring back to Figure 1 , along the thickness direction of the battery substrate 1, the average width of the orthogonal projection of the groove structure 1a is W; the depth of the groove structure 1a is H3, and W and H3 satisfy: H3:W=(1:20)~(3:10).

[0121] The average width of the groove structure 1a refers to the average value of the corresponding widths at different height positions of the top to the bottom of the groove structure 1a along the thickness direction of the battery substrate 1. The average width can be obtained by scanning electron microscopy and graphic processing software. For example, first, the picture of the groove structure 1a is obtained by scanning electron microscopy, and then the widths of the top, middle and bottom of the groove structure 1a are measured and averaged by graphic processing software, and the obtained value is the average width of the groove structure 1a.

[0122] In the scheme of the present application, since the side surface and the bottom of the electrode structure 2 are connected together with the battery substrate 1, in order to improve the contact area of the electrode structure 2 and the battery substrate 1, in addition to increasing the width of the electrode structure 2 itself, the side surface contact area of the electrode structure 2 and the groove structure 1a can also be increased. In order to reduce the shading of the electrode structure 2 to sunlight, the width of the electrode structure 2 can be reduced, and the contact area of the electrode structure 2 and the side surface of the groove structure 1a can be further increased to realize the stability of the connection with the battery substrate 1, that is, W and H3 are within the above ratio range, which can not only improve the stability of the contact between the electrode structure 2 and the battery substrate 1, but also help to reduce the blocking effect of the electrode structure 2 to sunlight and improve the utilization rate of sunlight. Exemplarily, H3:W=1:20, 1:16, 1:12, 1:9, 1:6, 3:10, etc.

[0123] Wherein, W satisfies: 10 μm≤W≤50 μm; H3 satisfies: 1 μm≤H3<3 μm. When W and H3 are in the above range, it is more helpful to reduce the shading of the electrode structure 2 to the sunlight while improving the stability of the electrode structure 2, thereby improving the absorption utilization rate of the sunlight. Exemplarily, W is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm; H3 is 1 μm, 1.4 μm, 1.8 μm, 2.2 μm, 2.9 μm, etc.

[0124] Further, as shown in Figure 4 and Figure 5 , in the direction of the electrode structure 2 pointing to the cell substrate 1 (see Y1 direction in Figure 4 ), the cross section of the groove structure 1a presents a top wide bottom narrow structure.

[0125] The top wide bottom narrow shape includes a trapezoidal structure or a special-shaped structure, refer back to Figure 4 , the cross section of the groove structure 1a presents a trapezoidal structure; the groove structure 1a is a special-shaped structure, which means that the connecting line between the top and the bottom can be connected by multiple line segments or composed of line segments and curves, refer back to Figure 5 , for example, Figure 5 , the connecting line between the top and the bottom of the special-shaped structure in

[0126] Wherein, the top wide bottom narrow structure is more helpful to improve the contact area of the electrode structure 2 and the cell substrate 1, thereby helping to improve the structural stability of the electrode structure 2 to a higher degree.

[0127] On the one hand, since the groove structure 1a presents a top wide bottom narrow structure, the electrode structure 2 presents a top wide bottom narrow structure, and the wider top helps to ensure the effect of the top of the electrode structure 2 contacting the solder strip to a higher degree, and the narrower bottom ensures the effective volume of the cell substrate 1, thereby helping to ensure the effect of the cell substrate 1 to a higher degree; on the other hand, since the top of the groove structure 1a is wide and the bottom is narrow, the side of the groove structure 1a presents a structure arranged obliquely, thereby helping to further increase the contact area of the electrode structure 2 and the side of the groove structure 1a in the solar cell semi-finished product, thereby increasing the overall contact effect to a higher degree.

[0128] Further, refer back to Figure 4The width of the top of the groove structure 1a is W1, and the width of the bottom of the groove structure 1a is W2, and W1, W2 satisfy: W1:W2=(6:5)~(9:5). When the ratio of the width of the top of the groove structure 1a and the bottom is within the above range, it is not only helpful to further ensure the contact effect of the top of the electrode structure 2 with the solder strip, but also to further ensure the effective volume of the battery substrate 1, improve the contact area of the electrode structure 2 with the side of the groove structure 1a, and thus further improve the performance of the electrode structure 2. For example, W1:W2 is 6:5, 7:5, 17:10, 8:5, 9:5, etc.

[0129] Further, W1 satisfies: 15μm≤W1≤20μm, and W2 satisfies: 8μm≤W2≤12μm. When the width of the top of the groove structure 1a and the bottom is within the above range, it is not only helpful to ensure the contact effect of the top of the electrode structure 2 with the solder strip, but also to ensure the effective volume of the battery substrate 1, improve the contact area of the electrode structure 2 with the side of the groove structure 1a, and thus further improve the performance of the electrode structure 2. For example, W1 is 15μm, 16μm, 17μm, 18μm, 20μm, etc.; and W2 is 8μm, 9μm, 10μm, 11μm, 12μm, etc.

[0130] In an optional embodiment, as shown in Figure 6 the battery substrate 1 comprises: a silicon substrate 11 and a functional layer 12 arranged on the surface of the silicon substrate 11, wherein the groove structure 1a is arranged on the functional layer 12. For example, as shown in Figure 7 when the solar cell is a heterojunction solar cell, the functional layer 12 of the light-receiving surface of the silicon substrate 11 comprises a first passivation layer 121, a first doped silicon layer 122, and a first transparent conductive layer 123, the functional layer 12 of the back surface of the silicon substrate 11 comprises a second passivation layer 124, a second doped silicon layer 125, and a second transparent conductive layer 126, and the groove structure 1a is arranged on the first transparent conductive layer 123 and the second transparent conductive layer 126, which is helpful to reduce the transmission distance of the carriers from the first transparent conductive layer 123 to the first electrode structure 2a and the transmission distance of the carriers from the second transparent conductive layer 126 to the second electrode structure 2b, thereby helping to improve the collection effect of the electrode structure 2 on the carriers to a higher degree.

[0131] In another optional embodiment, as shown in Figure 8 the groove structure 1a comprises a first groove sub-structure 11a and a second groove sub-structure 12a, and the battery substrate 1 comprises:

[0132] a silicon substrate 11, at least one side surface of the silicon substrate 11 is provided with the first groove sub-structure 11a;

[0133] The functional layer 12 is arranged on the silicon substrate 11, and the functional layer 12 is provided with a second recess substructure 12a on a surface thereof away from the silicon substrate 11, the second recess substructure 12a corresponding to the position of the first recess substructure 11a;

[0134] The first subpart 211 of the conductive metal layer 21 is filled in the second recess substructure 12a, and the second subpart 212 is exposed outside the functional layer 12.

[0135] In this embodiment, since the first recess substructure 11a is directly formed on the silicon substrate 11, and based on the characteristics of the profile, when the functional layer 12 is deposited on the first recess substructure 11a, the second recess substructure 12a corresponding to the position of the first recess substructure 11a is also formed on the functional layer 12, so the characteristics of the second recess substructure 12a are the same as those of the first recess substructure 11a.

[0136] In addition, the depth of the first recess substructure 11a arranged on the silicon substrate 11 will affect the thickness of the silicon substrate 11, so the present application controls H1 to ensure the thickness of the silicon substrate 11 and ensure the light absorption effect of the silicon substrate 11; in addition, when the first recess substructure 11a is arranged on the silicon substrate 11, since other functional film layers have not been deposited at this time, it is also helpful to avoid damage to other film layers when the first recess substructure 11a is formed, thereby reducing the recombination of carriers to a higher degree.

[0137] Further, as shown in Figure 9 , the silicon substrate 11 includes a first region corresponding to the position of the first recess substructure 11a, and a second region outside the first region;

[0138] The silicon substrate 11 in the first region has a micro-bump structure; and the silicon substrate 11 in the second region is provided with a first pyramid structure 111.

[0139] In an optional embodiment, the micro-bump structure is a second pyramid structure 112; and the distance between the tip of the second pyramid structure 112 closest to the sidewall of the first recess substructure 11a and the sidewall is less than 1 μm.

[0140] Referring back to Figure 9 , the second pyramid structure 112 closest to the sidewall refers to the second pyramid structure 112 having the smallest distance from the sidewall of the first recess substructure 11a, and the distance between the tip of the second pyramid structure 112 and the sidewall is W3.

[0141] When the interval is smaller, it means that the second pyramid structure 112 has higher adhesion with the groove wall, and the number of the second pyramid structure 112 in the groove structure 1a is relatively more, so that the roughness of the interface is more suitable, and it is more helpful to improve the combination tightness of the silicon substrate 11 and the electrode structure 2. Exemplarily, the interval is 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 0.9 μm, etc.

[0142] In addition, referring back to Figure 9 , the tip of the second pyramid structure 112 is in an arc structure. When the tip of the second pyramid structure 112 is in an arc structure, the stress concentration phenomenon at the tip can be effectively avoided, so that the coverage of the functional layer 12 at the tip is more dense and uniform, which helps to ensure the effect of the functional layer 12, and further helps to further improve the performance of the solar cell.

[0143] Further, the micro-protrusion structure is the second pyramid structure 112, wherein the average side length of the base of the first pyramid structure 111 is L1, and the average side length of the base of the second pyramid structure 112 is L2, and L2 is less than L1.

[0144] The average side length of the base of the pyramid structure refers to measuring the side length of the base, and then averaging the measured data. The measurement method can be in the form of a scanning electron microscope combined with a graphics processing software. Specifically, first, the scanning electron microscope is used to shoot to obtain a topographic diagram of the pyramid structure, and then the graphics processing software is used to measure the side length of the base.

[0145] Since the average side length of the base of the second pyramid structure 112 is smaller than that of the first pyramid structure 111, the existence of the second pyramid structure 112 helps to provide a more suitable roughness, thereby helping to improve the contact effect of the electrode structure 2 and the second groove sub-structure 12a to a higher degree.

[0146] Preferably, when L1, L2 satisfy: (L1-L2) / L1=(1:4)~(7:20), at this time, it is more helpful to improve the contact effect of the electrode structure 2 and the first groove sub-structure 11a. Exemplarily, (L1-L2) / L1 is 1:4, 11:40, 6:20, 13:40, 7:20, etc.

[0147] Further, L1 satisfies: 1 pm≤L1≤3 pm, and L2 satisfies: 0.75 pm≤L2≤2.2 pm. When L1 and L2 are within the above ranges, it indicates that the silicon substrate 11 of the first region corresponding to the first pyramid structure 111 has a higher light absorption effect, which helps to improve the utilization rate of light; and the electrode structure 2 of the first region corresponding to the second pyramid structure 112 has a higher contact effect with the first groove sub-structure 11a, thereby helping to further improve the collection capability of the electrode structure 2 for carriers and the structural stability of the electrode structure 2. Exemplarily, L1 is 1 pm, 1.5 pm, 2 pm, 2.5 pm, 3 pm, etc.; and L2 is 0.75 pm, 1 pm, 1.5 pm, 2 pm, 2.2 pm, etc.

[0148] In an alternative embodiment, as shown in FIG. 1C, the first groove sub-structure 11a is arranged on one side surface of the solar cell, i.e., the first groove sub-structure 11a is arranged only on the back surface of the solar cell or only on the light-receiving surface of the solar cell. Figure 10

[0149] In another alternative embodiment, as shown in FIG. 1D, the silicon substrate 11 includes a light-receiving surface and a back surface arranged oppositely, and the first groove sub-structure 11a is arranged on both the light-receiving surface and the back surface. The electrode structure 2 includes a first electrode structure 2a and a second electrode structure 2b, and the functional layer 12 includes: Figure 11

[0150] The first passivation layer 121 is arranged on the silicon substrate 11 on the light-receiving surface;

[0151] The first doped silicon layer 122 is arranged on the side surface of the first passivation layer 121 away from the silicon substrate 11;

[0152] The first transparent conductive layer 123 is arranged on the side surface of the first doped silicon layer 122 away from the first passivation layer 121, and the first electrode structure 2a is in ohmic contact with the first transparent conductive layer 123;

[0153] The second passivation layer 124 is arranged on the silicon substrate 11 on the back surface;

[0154] The second doped silicon layer 125 is arranged on the side surface of the second passivation layer 124 away from the silicon substrate 11;

[0155] The second transparent conductive layer 126 is arranged on the side surface of the second doped silicon layer 125 away from the second passivation layer 124, and the second electrode structure 2b is in ohmic contact with the second transparent conductive layer 126;

[0156] ​​The one of the first doped silicon layer 122 and the second doped silicon layer 125 is an N-type doped layer, and the other is a P-type doped layer. One of the first electrode structure 2a and the second electrode structure 2b is a positive electrode, and the other is a negative electrode.

[0157] In the above embodiment, since the light-receiving surface and the back surface of the silicon substrate 11 are both provided with the first recess sub-structure 11a, the functional layer 12 is correspondingly provided with the second recess sub-structure 12a, thereby helping to improve the contact area of the first electrode structure 2a and the first transparent conductive layer 123, the contact area of the second electrode structure 2b and the second transparent conductive layer 126, and effectively ensure the carrier collection capability and structural stability of the first electrode structure 2a and the second electrode structure 2b.

[0158] The defect state density of the first doped silicon layer 122 is less than 10 10 cm -2 ·eV -1 , and the defect state density of the second doped silicon layer 125 is less than 10 10 cm -2 ·eV -1 . When the defect state densities of the first doped silicon layer 122 and the second doped silicon layer 125 are within the above ranges, the recombination of carriers is reduced, and the transmission capability of the carriers is improved.

[0159] In addition, in the first recess sub-structure 11a on the back surface, the ratio of the area of the second transparent conductive layer 126 to the area of the first recess sub-structure 11a is greater than 85%; and in the first recess sub-structure 11a on the light-receiving surface, the ratio of the area of the first transparent conductive layer 123 to the area of the first recess sub-structure 11a is greater than 85%. The transparent conductive layer of the present application has a high coverage rate in the recess structure 1a, which is more helpful to improve the transmission performance of the carriers and the performance of the solar cell.

[0160] The present application provides a preparation method of a solar cell, which comprises the following steps:

[0161] Grooving is performed on at least one side surface of the cell substrate to form a recess structure on the cell substrate;

[0162] A conductive metal layer is prepared on the recess structure, the conductive metal layer comprises a first sub-part and a second sub-part connected to each other, the first sub-part is filled in the recess structure, and the second sub-part is exposed outside the cell substrate. The cell substrate containing the conductive metal layer is placed in a reaction solution containing anti-oxidation metal ions to prepare an anti-oxidation layer, and the anti-oxidation property of the anti-oxidation layer is higher than that of the conductive metal layer, thereby obtaining an electrode structure;

[0163] The height of the first sub-part is H1 and the height of the second sub-part is H2 in the thickness direction of the battery substrate, H1 satisfies 1 pm < H1 < 3 pm, and H2 satisfies 5 pm < H2 < 15 pm.

[0164] Further, in the step of slotting at least one side surface of the battery substrate, the at least one side surface of the battery substrate is slotted by laser processing, and parameters of the laser include: a pulse width of 7 ps to 15 ps, ultraviolet light with a wavelength of 350 nm to 360 nm, a frequency of 50 kHz to 300 kHz, and a pulse energy of 3 mJ to 15 mJ.

[0165] The preparation method can effectively ensure the slotting effect, reduce laser damage, and reduce the degree of carrier recombination.

[0166] Further, the step of preparing the electrode structure comprises:

[0167] The slurry is printed on the groove structure by screen printing, so that part of the slurry is filled in the interior of the groove structure to form the first sub-part, and the remaining part of the slurry is exposed outside the groove structure to form the second sub-part; and the conductive metal layer is prepared after drying and vacuum curing of the slurry.

[0168] Light injection;

[0169] The battery substrate containing the conductive metal layer is placed in a reaction solution containing tin ions to prepare the oxidation-resistant layer.

[0170] In the present application, the oxidation-resistant layer is prepared after light injection, which helps to improve the binding tightness of the oxidation-resistant layer and the conductive metal layer, thereby helping to ensure the protection performance of the oxidation-resistant layer to a higher degree. Specifically, after light injection of the conductive metal layer, more active sites can be exposed, which can be combined with tin ions in the form of covalent bond or ionic bond, thereby helping to improve the binding tightness of the oxidation-resistant layer and the conductive metal layer to a higher degree, and improve the protection effect of the oxidation-resistant layer.

[0171] Further, the oxidation-resistant layer is prepared on the conductive metal layer by electroless tin plating, the temperature is 60°C to 80°C, the time is 30 s to 300 s, the electroless tin plating solution comprises a tin salt, an acid adjuster, a reducing agent, and an additive, and the additive is used to change the potential value when the conductive metal layer reacts with the tin salt.

[0172] In the electroless tin plating solution, the mass concentration of the tin salt is 10 g / L to 20 g / L, the volume percentage of the acid adjuster is 5% to 10%, the mass concentration of the reducing agent is 10 g / L to 30 g / L, and the mass concentration of the additive is 0.1 g / L to 1 g / L.

[0173] In addition, the additive capable of changing the reaction potential is used to facilitate the displacement reaction of tin ions with the conductive metal layer to generate tin. By controlling the mass concentration, time and temperature of the tin salt, the acid regulator, the reducing agent and the additive in the above-mentioned electroless tin plating solution within the above-mentioned ranges, the reaction can be effectively ensured to be sufficient, and the thickness of the prepared anti-oxidation layer is more uniform, the compactness is higher, and the corrosion resistance is higher.

[0174] The tin salt is at least one of tin chloride, stannous citrate and stannous tartrate; the acid regulator is sulfuric acid; the reducing agent is sodium hypophosphite; and the additive is thiourea.

[0175] Further, after the step of photo-injection, before the step of placing the battery substrate containing the conductive metal layer in the reaction solution containing tin ions to prepare the anti-oxidation layer, the preparation method further comprises: cleaning the conductive metal layer.

[0176] The conductive metal layer is cleaned before the preparation of the anti-oxidation layer, thereby facilitating the removal of impurities on the conductive metal layer and ensuring the tightness of the combination of the conductive metal layer and the anti-oxidation layer.

[0177] Further, the battery substrate comprises a silicon substrate and a functional layer arranged on the silicon substrate, the groove structure comprises a first groove sub-structure and a second groove sub-structure, and the step of grooving at least one side surface of the battery substrate comprises:

[0178] The at least one side surface of the silicon substrate is grooved to form the first groove sub-structure on the silicon substrate.

[0179] The functional layer is prepared on the silicon substrate, and the surface of the functional layer away from the silicon substrate is provided with the second groove sub-structure corresponding to the position of the first groove sub-structure.

[0180] The first sub-part of the conductive metal layer is filled in the second groove sub-structure, and the second sub-part is exposed outside the functional layer.

[0181] Further, the silicon substrate comprises a first region corresponding to the position of the first groove sub-structure and a second region outside the first region.

[0182] After the step of grooving at least one side surface of the silicon substrate, before the step of preparing the functional layer on the silicon substrate, the preparation method further comprises: cleaning and texturing the silicon substrate to form a first pyramid structure on the silicon substrate in the second region and a second pyramid structure on the silicon substrate in the first region, wherein the distance between the tip of the second pyramid structure closest to the sidewall of the first groove sub-structure and the sidewall is less than 1 μm.

[0183] Furthermore, the silicon substrate includes a light-receiving surface and a back-lighting surface disposed opposite to each other. The light-receiving surface and the back-lighting surface of the silicon substrate are respectively grooved to form a first groove substructure on the light-receiving surface and the back-lighting surface of the silicon substrate. The electrode structure includes a first electrode structure and a second electrode structure.

[0184] The steps for fabricating a functional layer on a silicon substrate include:

[0185] A first passivation layer is prepared on the light-receiving surface of a silicon substrate;

[0186] A second passivation layer is fabricated on the back surface of a silicon substrate;

[0187] A first doped silicon layer is prepared on the first passivation layer;

[0188] A second doped silicon layer is prepared on the second passivation layer;

[0189] A first transparent conductive layer is fabricated on the first doped silicon layer;

[0190] A second transparent conductive layer is fabricated on the second doped silicon layer;

[0191] The first electrode structure is in ohmic contact with the first transparent conductive layer; the second electrode structure is in ohmic contact with the second transparent conductive layer; one of the first doped silicon layer and the other of the second doped silicon layer is an N-type doped layer and the other is a P-type doped layer; one of the first electrode structure and the other of the second electrode structure is a positive electrode and the other is a negative electrode.

[0192] This application also discloses a photovoltaic module, which includes: the solar cell described above, or a solar cell prepared by the above-described preparation method.

[0193] The technical solution of this application will be further explained below with reference to more specific embodiments and experimental test results.

[0194] Example 1:

[0195] This application provides a method for fabricating a heterojunction solar cell.

[0196] S1 prepares a battery substrate, wherein the battery substrate includes a silicon substrate and a functional layer disposed on the silicon substrate:

[0197] S1.1 Laser grooving is performed on the light-receiving surface and the back-light-receiving surface of the N-type silicon substrate to form a first groove substructure. The pulse width is 10 ps, ​​the wavelength is 355 nm, the frequency is 150 kHz, the pulse energy is 9 μJ, and W is 20 μm. The cross-section of the first groove substructure is a trapezoidal structure with a wide top and a narrow bottom. W1 is 16 μm, W2 is 10 μm, H3 is 2.8 μm, and W is 18 μm.

[0198] S1.2 cleaning and texturing the silicon substrate to form first pyramid structures on the silicon substrate in the second region and second pyramid structures on the silicon substrate in the first region, wherein the distance between the tip of the second pyramid structure closest to the sidewall of the first groove substructure and the sidewall is less than 1 pm, the tip of the second pyramid structure presents an arc-shaped structure, L1 is 2.5 pm, and L2 is 1.75 pm.

[0199] S1.3 preparing a functional layer, and the functional layer has second groove substructures corresponding to the positions of the first groove substructures, and the shapes of the second groove substructures are the same as the shapes of the first groove substructures:

[0200] S1.3.1 preparing a first passivation layer with a thickness of 6 nm on the back light surface of the silicon substrate by the PECVD method; and preparing a second passivation layer with a thickness of 5 nm on the light receiving surface of the silicon substrate by the PECVD method.

[0201] S1.3.2 depositing a second doped silicon layer with a thickness of 35 nm on the first passivation layer by the PECVD method, the second doped silicon layer being a P-type doped silicon layer; and depositing a second doped silicon layer with a thickness of 20 nm on the second passivation layer by the PECVD method, the second doped silicon layer being an N-type doped silicon layer.

[0202] S1.3.3 preparing a first transparent conductive layer on the first doped silicon layer by the PVD method; and preparing a second transparent conductive layer on the second doped silicon layer to obtain the functional layer.

[0203] S2 preparing an electrode structure:

[0204] S2.1 printing copper paste on the second groove substructures of the second transparent conductive layer on the back light surface and on the second groove substructures of the first transparent conductive layer on the light receiving surface by screen printing, so that part of the paste is filled in the interior of the second groove substructures to form a first subpart, and the remaining part of the paste is exposed outside the second groove substructures to form a second subpart; and drying and vacuum curing the paste to obtain a conductive metal layer, wherein the second subpart includes an intermediate subpart and an epitaxial subpart, H1 is 2.8 pm, and H2 is 8 pm.

[0205] S2.2 light injection;

[0206] S2.3 preparing an oxidation-resistant tin layer by chemical tin plating, and placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions, wherein the reaction temperature is 70°C, the time is 200 s, the chemical tin plating solution includes tin chloride with a mass concentration of 15 g / L, sulfuric acid with a volume percentage of 8%, sodium hypophosphite with a mass concentration of 15 g / L, and thiourea with a mass concentration of 0.7 g / L.

[0207] Example Two:

[0208] The difference between this embodiment and embodiment one is that H1 of this embodiment is 1 μm and H2 is 15 μm.

[0209] Embodiment three:

[0210] The difference between this embodiment and embodiment one is that H1 of this embodiment is 2.9 μm and H2 is 5 μm.

[0211] Embodiment four:

[0212] The difference between this embodiment and embodiment one is that W1:W2 is 6:5.

[0213] Embodiment five:

[0214] The difference between this embodiment and embodiment one is that the cross section of the first groove substructure presents a rectangular structure in the direction pointing to the battery substrate along the electrode structure, i.e. W1:W2 is 1:1.

[0215] Embodiment six:

[0216] The difference between this embodiment and embodiment one is that the tip of the second pyramid structure is a sharp cone structure.

[0217] Embodiment seven:

[0218] The difference between this embodiment and embodiment one is that the distance between the tip of the second pyramid structure closest to the sidewall of the first groove substructure and the sidewall is greater than 1.5 μm.

[0219] Embodiment eight:

[0220] The difference between this embodiment and embodiment one is that the average side length of the base of the first pyramid structure L1 is equal to the average side length of the base of the second pyramid structure L2.

[0221] Embodiment nine:

[0222] The difference between this embodiment and embodiment one is that the groove structure of this embodiment is only provided on the transparent conductive layer.

[0223] Comparative example one:

[0224] The difference between this comparative example and embodiment one is that no groove structure is provided on the battery substrate in this comparative example, i.e. the battery substrate is a planar structure and the electrode structure is provided on the planar structure.

[0225] Comparative example two:

[0226] The difference between this comparative example and embodiment one is that H1 of this comparative example is 3 μm.

[0227] Comparative example three:

[0228] The difference between the present comparative example and Example 1 is that H2 of the present comparative example is 3 μm.

[0229] Comparative Example Four

[0230] The difference between the present comparative example and Example 1 is that H2 of the present comparative example is 17 μm.

[0231] Performance test

[0232] The solar cells prepared in Examples 1-9 and Comparative Examples 1-4 were subjected to the following relevant tests:

[0233] The solar cells provided in the present application were subjected to performance tests such as open-circuit voltage, short-circuit current and fill factor using a tester with a model of GIV-60 from Zhongsen Electric Energy Technology Co., Ltd. The silicon wafer of the tested solar cell was 210 mm x 105 mm in size, and the calibrated light intensity was 1000 ± 5 W / m². The experimental test results are shown in Table 1, which is the performance test results of the solar cell.

[0234] Table 1 Performance test results of the solar cell

[0235]

[0236] As can be seen from the data of Example 1 and Comparative Example 1, the photoelectric conversion efficiency of the solar cell of Example 1 is better than that of Comparative Example 1. It can be seen that the first groove substructure provided on the silicon substrate can avoid etching of the bottom of the electrode structure by the reaction solution, thereby ensuring the tightness of the connection between the electrode structure and the transparent conductive layer. However, the solar cell of Comparative Example 1 does not have a groove structure, so when the anti-oxidation layer is prepared, the reaction solution will corrode the bottom of the electrode structure, thereby causing the bonding performance between the electrode structure and the transparent conductive layer to decrease, and causing the electrode structure to be more easily detached from the transparent conductive layer.

[0237] As can be seen from the data of Examples 1-3 and Comparative Examples 2-4, the photoelectric conversion efficiency of Examples 1-3 is better than that of Comparative Examples 2-4. It can be seen that when H1 and H2 satisfy the range of 1≤H1<3 μm and 5≤H2≤15 μm, there is a high matching between H1 and H2, and under the synergistic effect of both, the connection stability between the first subpart and the transparent conductive layer is ensured, and the protection effect of the anti-oxidation layer on the second subpart is optimized, thereby helping to optimize the performance of the solar cell.

[0238] Among them, analyzing the data of example one to example three can know that the photoelectric conversion efficiency of example one and example three is better than that of example two. It can be seen that H1 and H2 in example one and example three have higher matching, and higher matching is more helpful to improve the structural stability of the electrode structure and improve the collection ability of the electrode structure to the carriers.

[0239] Analyzing the data of example one, example four and example five can know that the photoelectric conversion efficiency of example one and example four is better than that of example five. It can be seen that the ratio of W1 and W2 in example one and example four is more appropriate, and the more appropriate ratio can further ensure the effective volume of the battery substrate and is more helpful to improve the side contact area of the electrode structure and the groove structure, thereby further improving the performance of the electrode structure.

[0240] Analyzing the data of example one and example six can know that the photoelectric conversion efficiency of example one is better than that of example six. It can be seen that when the tower top of the second pyramid structure is an arc structure, the stress concentration phenomenon at the tower top can be effectively avoided, the denseness of the functional layer at the tower top is higher, the uniformity is higher, which is more helpful to ensure the effect of the functional layer, and further helps to improve the performance of the solar cell.

[0241] Analyzing the data of example one and example seven can know that the photoelectric conversion efficiency of example one is better than that of example seven. It can be seen that when the distance between the tower top of the second pyramid structure closest to the side wall of the first groove substructure and the side wall is less than 1 μm, the number of the second pyramid structure in the first groove substructure is relatively more, which is more helpful to improve the combination tightness of the transparent conductive layer and the electrode structure.

[0242] Analyzing the data of example one and example eight can know that the photoelectric conversion efficiency of example one is better than that of example eight. It can be seen that when L2 is less than L1, the second pyramid structure can provide a more appropriate roughness at this time, thereby helping to improve the contact effect of the electrode structure and the transparent conductive layer to a higher degree.

[0243] Analyzing the data of example nine can know that the photoelectric conversion efficiency of example nine reaches 25.36%. It can be seen that when the groove structure is arranged on the transparent conductive layer, it can also better play the effect of protecting the bottom of the electrode structure from corrosion.

[0244] The above has introduced the solar cell and the preparation method thereof and the photovoltaic module disclosed in the embodiments of the present application in detail, the principles and implementation manners of the present application are described by applying specific examples in the present text, and the above example description is only for helping to understand the solar cell and the preparation method thereof and the photovoltaic module: at the same time, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manner and application range will be changed, and on the basis of the above, the content of the specification should not be understood as the limitation of the present application.

Claims

1. A solar cell, characterized in that, The solar cell includes: A battery substrate, wherein at least one side surface of the battery substrate is provided with a groove structure; An electrode structure, wherein the electrode structure is disposed at the groove structure, the electrode structure comprising: A conductive metal layer, the conductive metal layer comprising a first sub-part and a second sub-part connected to each other, the first sub-part filling the groove structure, and the second sub-part exposing the outside of the battery substrate; An antioxidant layer is coated on the surface of the second sub-part. The antioxidant layer has higher antioxidant properties than the conductive metal layer. The antioxidant layer is configured to be prepared by placing the battery substrate containing the conductive metal layer in a reaction solution containing antioxidant metal ions. Wherein, along the thickness direction of the battery substrate, the height of the first sub-part is H1, and the height of the second sub-part is H2, wherein H1 satisfies: 1μm≤H1<3μm; and H2 satisfies: 5μm≤H2≤9μm.

2. The solar cell according to claim 1, characterized in that, H1 and H2 satisfy: (1:15) ≤ H1:H2 < (3:5).

3. The solar cell according to claim 1, characterized in that, The second sub-part includes: An intermediate sub-part is located on the side surface of the first sub-part facing away from the battery substrate, and the position of the intermediate sub-part corresponds to the range of the position of the first sub-part. An epitaxial sub-part extends outward from the intermediate sub-part and contacts the surface of the battery substrate located outside the groove structure.

4. The solar cell according to claim 1, characterized in that, Along the thickness direction of the battery substrate, the average width of the orthographic projection of the groove structure is W, and the depth of the groove structure is H3. W and H3 satisfy: H3:W = (1:20) ~ (3:10).

5. The solar cell according to claim 4, characterized in that, The W satisfies: 10μm≤W≤50μm; the H3 satisfies: 1μm≤H3<3μm.

6. The solar cell according to claim 1, characterized in that, Along the direction from the electrode structure to the battery substrate, the cross-section of the groove structure is wide at the top and narrow at the bottom.

7. The solar cell according to claim 6, characterized in that, The width of the top of the groove structure is W1, and the width of the bottom of the groove structure is W2. W1 and W2 satisfy: W1:W2 = (6:5) ~ (9:5).

8. The solar cell according to claim 7, characterized in that, The W1 satisfies: 15μm≤W1≤20μm, and the W2 satisfies: 8μm≤W2≤12μm.

9. The solar cell according to claim 1, characterized in that, The groove structure includes a first groove substructure and a second groove substructure, and the battery substrate includes: A silicon substrate, wherein at least one side surface of the silicon substrate is provided with the first groove substructure; A functional layer is disposed on the silicon substrate, and a second groove substructure is provided on the surface of the functional layer opposite to the silicon substrate, the second groove substructure corresponding to the position of the first groove structure; The first sub-part of the conductive metal layer is filled within the second groove sub-structure, while the second sub-part is exposed outside the functional layer.

10. The solar cell according to claim 9, characterized in that, On the silicon substrate, the silicon substrate includes a first region corresponding to the location of the first groove substructure, and a second region located outside the first region; The silicon substrate in the first region has a micro-protrusion structure; the silicon substrate in the second region has a first pyramid structure.

11. The solar cell according to claim 10, characterized in that, The micro-protrusion structure is a second pyramid structure; Wherein, the distance between the apex of the second pyramid structure, which is closest to the sidewall of the first groove substructure, and the sidewall is less than 1 μm; and / or, The apex of the second pyramid structure is curved.

12. The solar cell according to claim 10, characterized in that, The micro-protrusion structure is a second pyramid structure, wherein the average side length of the base of the first pyramid structure is L1, and the average side length of the base of the second pyramid structure is L2, wherein L2 is smaller than L1.

13. The solar cell according to claim 12, characterized in that, The L1 and L2 satisfy: (L1-L2) / L1=(1:4)~(7:20).

14. The solar cell according to claim 13, characterized in that, The L1 satisfies: 1μm≤L1≤3μm, and the L2 satisfies: 0.75μm≤L2≤2.2μm.

15. The solar cell according to claim 1, characterized in that, The conductive metal layer is made of at least one of copper and aluminum; and / or, The thickness of the antioxidant layer is 1μm~5μm; and / or, The metal material of the antioxidant layer includes at least one of tin, silver, and gold.

16. The solar cell according to any one of claims 9 to 14, characterized in that, The silicon substrate includes a light-receiving surface and a back-lighting surface disposed opposite to each other. The first groove substructure is provided on both the light-receiving surface and the back-lighting surface. The electrode structure includes a first electrode structure and a second electrode structure. The functional layer includes: A first passivation layer is disposed on the silicon substrate on the light-receiving surface; A first doped silicon layer is disposed on the side surface of the first passivation layer opposite to the silicon substrate; A first transparent conductive layer is disposed on the side surface of the first doped silicon layer away from the first passivation layer, and the first electrode structure is in ohmic contact with the first transparent conductive layer. A second passivation layer is disposed on the silicon substrate on the backlight surface; The second doped silicon layer is disposed on the side surface of the second passivation layer opposite to the silicon substrate; The second transparent conductive layer is disposed on the side surface of the second doped silicon layer away from the second passivation layer, and the second electrode structure is in ohmic contact with the second transparent conductive layer. In this configuration, one of the first doped silicon layer and the second doped silicon layer is an N-type doped layer and the other is a P-type doped layer; one of the first electrode structure and the other of the second electrode structure is a positive electrode and the other is a negative electrode.

17. A method for preparing a solar cell, characterized in that, The method for preparing the solar cell includes the following steps: A groove is made on at least one surface of the battery substrate to form a groove structure on the battery substrate; A conductive metal layer is prepared on the groove structure. The conductive metal layer includes a first sub-part and a second sub-part connected to each other. The first sub-part is filled in the groove structure, and the second sub-part is exposed outside the battery substrate. The battery substrate containing the conductive metal layer is placed in a reaction solution containing antioxidant metal ions to prepare an antioxidant layer. The antioxidant layer has higher antioxidant properties than the conductive metal layer, thus obtaining an electrode structure. Wherein, along the thickness direction of the battery substrate, the height of the first sub-part is H1, and the height of the second sub-part is H2, wherein H1 satisfies: 1μm≤H1<3μm; and H2 satisfies: 5μm≤H2≤9μm.

18. The preparation method according to claim 17, characterized in that, In the step of grooving at least one side surface of the battery substrate, the grooving is performed using a laser. The laser parameters include: ultraviolet light with a pulse width of 7 ps to 15 ps, a wavelength of 350 nm to 360 nm, a frequency of 50 kHz to 300 kHz, and a pulse energy of 3 μJ to 15 μJ.

19. The preparation method according to claim 18, characterized in that, The steps for obtaining the electrode structure include: A paste is printed onto the groove structure using screen printing, such that a portion of the paste fills the interior of the groove structure to form the first sub-part, while the remaining portion of the paste is exposed on the exterior of the groove structure to form the second sub-part; the conductive metal layer is obtained by drying and vacuum curing the paste. Light injection; The antioxidant layer is prepared by placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions.

20. The preparation method according to claim 19, characterized in that, The antioxidant layer is prepared on the conductive metal layer by chemical tin plating at a temperature of 60℃~80℃ for 30 s~300 s. The chemical tin plating solution includes tin salt, acid regulator, reducing agent and additive, and the additive is used to change the potential value when the conductive metal layer reacts with the tin salt. In the chemical tin plating solution, the tin salt has a mass concentration of 10 g / L to 20 g / L, the acidity regulator has a volume percentage of 5% to 10%, the reducing agent has a mass concentration of 10 g / L to 30 g / L, and the additive has a mass concentration of 0.1 g / L to 1 g / L.

21. The preparation method according to claim 20, characterized in that, The tin salt is at least one selected from stannous chloride, stannous citrate, and stannous tartrate; and / or... The acid regulator is sulfuric acid; and / or, The reducing agent is sodium hypophosphite; and / or, The additive is thiourea.

22. The preparation method according to claim 19, characterized in that, After the light injection step and before the step of placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions to prepare the antioxidant layer, the preparation method further includes: cleaning the conductive metal layer.

23. The preparation method according to any one of claims 17 to 22, characterized in that, The battery substrate includes a silicon substrate and a functional layer disposed on the silicon substrate, the groove structure includes a first groove substructure and a second groove substructure, and the step of creating a groove on at least one surface of the battery substrate includes: A groove is made on at least one surface of the silicon substrate to form the first groove substructure on the silicon substrate; The functional layer is fabricated on the silicon substrate, and a second sub-groove structure is provided on the surface of the functional layer opposite to the silicon substrate, the second sub-groove structure corresponding to the position of the first sub-groove structure; The first sub-part of the conductive metal layer is filled within the second groove sub-structure, while the second sub-part is exposed outside the functional layer.

24. The preparation method according to claim 23, characterized in that, The silicon substrate includes a first region corresponding to the position of the first groove substructure, and a second region located outside the first region; After the step of slotting at least one side surface on the silicon substrate and before the step of preparing the functional layer on the silicon substrate, the preparation method further includes: cleaning and texturing the silicon substrate to form a first pyramid structure on the silicon substrate in the second region, and forming a second pyramid structure on the silicon substrate in the first region, wherein the distance between the apex of the second pyramid structure, which is closest to the sidewall of the first groove substructure, and the sidewall is less than 1 μm.

25. The preparation method according to claim 23, characterized in that, The silicon substrate includes a light-receiving surface and a back-lighting surface disposed opposite to each other. The light-receiving surface and the back-lighting surface of the silicon substrate are respectively grooved to form the first groove substructure on the light-receiving surface and the back-lighting surface of the silicon substrate. The electrode structure includes a first electrode structure and a second electrode structure. The step of fabricating the functional layer on the silicon substrate includes: A first passivation layer is prepared on the light-receiving surface of the silicon substrate; A second passivation layer is prepared on the back surface of the silicon substrate; A first doped silicon layer is prepared on the first passivation layer; A second doped silicon layer is prepared on the second passivation layer; A first transparent conductive layer is prepared on the first doped silicon layer; A second transparent conductive layer is prepared on the second doped silicon layer; Wherein, the first electrode structure is in ohmic contact with the first transparent conductive layer; the second electrode structure is in ohmic contact with the second transparent conductive layer; one of the first doped silicon layer and the other of the second doped silicon layer is an N-type doped layer and the other is a P-type doped layer; one of the first electrode structure and the other of the second electrode structure is a positive electrode and the other is a negative electrode.

26. A photovoltaic module, characterized in that, The photovoltaic module includes: a solar cell according to any one of claims 1 to 16, or a solar cell prepared by the preparation method according to any one of claims 17 to 25.

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