Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention 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, wherein at least one side surface of the cell substrate is provided with a groove structure; the electrode structure is arranged at the groove structure, the electrode structure comprises a conductive metal layer, the conductive metal layer comprises a first sub-part and a second sub-part which are connected, the groove structure is filled with the first sub-part, and the second sub-part is exposed out of the battery substrate; the surface of the second subpart is coated with the anti-oxidation layer, the oxidation resistance of the anti-oxidation layer is higher than that of the conductive metal layer, and the anti-oxidation layer is configured to be prepared by placing the battery substrate containing the conductive metal layer in a reaction solution containing anti-oxidation metal ions; along the thickness direction of the cell substrate, the H1 of the first sub-part and the H2 of the second sub-part satisfy the following conditions: 1 < = H1 < 3 [mu] m, and 5 < = H2 < = 15 [mu] m. The electrode structure on the solar cell is high in stability and good in 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] Embodiments of the present application disclose a solar cell, a preparation method thereof and a photovoltaic module, the electrode structure of the solar cell has high stability and good current collection effect.

[0004] In a first aspect, embodiments of the present application disclose a solar cell, which comprises: a cell substrate, at least one side surface of the cell substrate being provided with a groove structure; an electrode structure, the electrode structure being arranged at the groove structure, the electrode structure comprising: a conductive metal layer, the conductive metal layer comprising a first sub-portion and a second sub-portion connected with each other, the first sub-portion being filled in the groove structure, and the second sub-portion being exposed outside the cell substrate; an anti-oxidation layer, the anti-oxidation layer being coated on the surface of the second sub-portion, 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; 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.

[0005] Further, the H1 and the H2 satisfy (1:15)≤H1:H2<(3:5).

[0006] Further, the second sub-portion comprises: an intermediate sub-portion, the intermediate sub-portion being located on the side surface of the first sub-portion away from the cell substrate, and the position of the intermediate sub-portion corresponding to the range of the position of the first sub-portion; an epitaxial sub-portion, the epitaxial sub-portion being arranged extending outward from the intermediate sub-portion, and the epitaxial sub-portion being in contact with the surface of the cell substrate outside the groove structure.

[0007] Further, along the thickness direction of the battery substrate, the average width of the orthogonal projection of the groove structure is W, and the depth of the groove structure is H3, and the W and the H3 satisfy: H3:W=(1:20)~(3:10).

[0008] Further, the W satisfies: 10μm≤W≤50μm; and the H3 satisfies: 1μm≤H3<3μm.

[0009] Further, along the direction of the electrode structure pointing to the battery substrate, the cross section of the groove structure presents a structure of top wide and bottom narrow.

[0010] Further, the width of the top of the groove structure is W1, and the width of the bottom of the groove structure is W2, and the W1, the W2 satisfy: (6:5)~(9:5).

[0011] Further, the W1 satisfies: 15μm≤W1≤20μm, and the W2 satisfies: 8μm≤W2≤12μm.

[0012] Further, the groove structure comprises a first groove substructure and a second groove substructure, and the battery substrate comprises: a silicon substrate, at least one side surface of the silicon substrate is provided with the first groove substructure; a functional layer, the functional layer is arranged on the silicon substrate, and a surface of the functional layer away from the silicon substrate is provided with the second groove substructure, and the second groove substructure corresponds to the position of the first groove substructure; wherein the first sub part of the conductive metal layer is filled in the second groove substructure, and the second sub part is exposed outside the functional layer.

[0013] Further, on the silicon substrate, the silicon substrate comprises a first region corresponding to the position of the first groove substructure, and a second region outside the first region; wherein the silicon substrate in the first region is provided with a micro-protrusion structure; and the silicon substrate in the second region is provided with a first pyramid structure.

[0014] Further, the micro-protrusion structure is a second pyramid structure; wherein the distance between the top of the second pyramid structure closest to the side wall of the first groove substructure and the side wall is less than 1μm; and / or, the top of the second pyramid structure presents an arc structure.

[0015] 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.

[0016] Further, the L1 and the L2 satisfy (L1-L2) / L1=(1:4)~(7:20).

[0017] Further, the L1 satisfies 1μm≤L1≤3μm, and the L2 satisfies 0.75μm≤L2≤2.2μm.

[0018] Further, a metal material of the conductive metal layer comprises at least one of copper and aluminum; and / or, a thickness of the anti-oxidation layer is 1μm~5μm; and / or, a metal material of the anti-oxidation layer comprises at least one of tin, silver and gold.

[0019] Further, the silicon substrate comprises a light-receiving surface and a back surface arranged oppositely, the first recess sub-structure is arranged on the light-receiving surface and the back surface, the electrode structure comprises a first electrode structure and a second electrode structure, and the functional layer comprises: a first passivation layer arranged on the silicon substrate on the light-receiving surface; a first doped silicon layer arranged on a side surface of the first passivation layer away from the silicon substrate; 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; a second passivation layer arranged on the silicon substrate on the back surface; a second doped silicon layer arranged on a side surface of the second passivation layer away from the silicon substrate; a second transparent conductive layer arranged on a 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; 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.

[0020] In a second aspect, the embodiments of the present application disclose a preparation method of a solar cell, and the preparation method comprises the following steps: grooving at least one side surface of a battery substrate to form a groove structure on the battery substrate; forming 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 battery substrate, placing the battery substrate containing the conductive metal layer in a reaction solution containing anti-oxidation metal ions to form an anti-oxidation layer, and the anti-oxidation layer having higher anti-oxidation property than the conductive metal layer, thereby obtaining an electrode structure; wherein, along a thickness direction of the battery substrate, a height of the first sub-portion is H1, and a 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.

[0021] Further, in the step of grooving at least one side surface of the battery substrate, the at least one side surface of the battery substrate is grooved by laser processing, wherein 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.

[0022] Further, the step of obtaining the electrode structure comprises: printing a slurry on the groove structure by screen printing, so that part of the slurry is filled in the groove structure to form the first sub-portion, and the rest of the slurry is exposed outside the groove structure to form the second sub-portion; and drying and vacuum curing the slurry to obtain the conductive metal layer; light injection; placing the battery substrate containing the conductive metal layer in a reaction solution containing tin ions to form the anti-oxidation layer.

[0023] Further, the anti-oxidation layer is formed on the conductive metal layer by electroless tin plating, at a temperature of 60 °C to 80 °C and for a time of 30 s to 300 s, and 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; wherein, 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.

[0024] Further, the tin salt is at least one of stannous chloride, stannous citrate, and stannous tartrate; and / or, The acidic regulator is sulfuric acid; and / or, The reducing agent is sodium hypophosphite; and / or, The additive is thiourea.

[0025] Furthermore, 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 anti-oxidation layer, the preparation method further includes: cleaning the conductive metal layer.

[0026] Furthermore, the battery substrate includes a silicon substrate and a functional layer provided on the silicon substrate, the groove structure includes a first groove substructure and a second groove substructure, and the step of grooved at least one side of the surface of the battery substrate includes: Grooving at least one side surface of the silicon substrate to form the first groove substructure on the silicon substrate; The functional layer is prepared on the silicon substrate, wherein a second sub-groove structure is provided on a surface of the functional layer facing away from the silicon substrate, and the second sub-groove structure corresponds to a position of the first sub-groove structure; 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.

[0027] Furthermore, the silicon substrate includes a first region corresponding to the position of the first groove substructure, and a second region outside the first region; After the step of grooving 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 includes: cleaning and texturing the silicon substrate to form a first pyramid structure on the silicon substrate in the second area, and forming a second pyramid structure on the silicon substrate in the first area, wherein the distance between the 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.

[0028] Furthermore, the silicon substrate includes a light-receiving surface and a backlight surface disposed opposite to each other, and the light-receiving surface and the backlight surface of the silicon substrate are grooved respectively to form the first groove substructure on the light-receiving surface and the backlight surface of the silicon substrate, and the electrode structure includes a first electrode structure and a second electrode structure; The step of preparing a functional layer on the silicon substrate comprises: preparing a first passivation layer on the light-receiving surface of the silicon substrate; preparing a second passivation layer on the backlight surface of the silicon substrate; forming a first doped silicon layer 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 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.

[0029] In a third aspect, the embodiments of the present application disclose a photovoltaic module, which comprises 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.

[0030] Compared with the prior art, the present application has the beneficial effects that the present application provides a solar cell, a preparation method thereof, and a photovoltaic module, the solar cell is provided with 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 the electrode structure has good current collection effect.

[0031] Specifically, the electrode structure of the present application comprises a conductive metal layer and an oxidation-resistant layer covering the surface of the conductive metal layer, wherein the conductive metal layer comprises a first subpart located inside the groove structure and a second subpart located outside the groove structure, and therefore, 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.

[0032] 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.

[0033] Therefore, the application sets the H1 in a specific range, so that the height of the first sub part filled in the groove structure is appropriate, and the first sub part effectively blocks the downward penetration of the reaction solution containing metal oxide ions by virtue of the appropriate height, thereby avoiding the corrosion of the bottom of the conductive metal layer by the reaction solution, so as to help avoid the falling off of the electrode structure; and it also helps to increase the contact area between the side wall of the groove structure and the electrode structure, improve the contact tightness of the groove structure and the electrode structure, and further improve the connection stability of the first sub part and the battery substrate; in addition, the specific range of H1 can effectively avoid affecting the performance of the battery substrate, thereby ensuring the performance of the solar cell to a higher degree.

[0034] In addition, by setting the H2 in a specific range, the oxidation-resistant layer and the second sub part can form effective cooperation to jointly enhance the protection effect of the second sub part. This is because the appropriate height makes the area of the second sub part 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, and avoid the problem of local protection failure caused by large protection area, and further improve the structural stability of the second sub part under the synergistic effect of the two. In addition, the above structure makes the second sub part have higher structural stability, so this provides a stable basis for the welding of the solder strip, and ensures the effectiveness of the solder strip welding to a higher degree.

[0035] That is, the setting mode of H1, H2 and the oxidation-resistant layer of the application has higher relevance, and through the cooperation of the three, it can not only ensure the connection stability of the first sub part and the battery substrate, but also optimize the protection effect of the oxidation-resistant layer on the second sub part, and improve the stability of the solder strip welding.

[0036] In addition, the synergistic effect between H1 and H2 can not only guarantee the structural stability of the electrode structure, but also help 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 in the above range, the volume of the electrode structure is appropriate, thereby helping to reduce the resistance of the electrode structure and optimize the collection effect of the electrode structure on the carriers. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the 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 application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Figure 1 is a structural schematic diagram of a first battery substrate provided by the embodiment of the application; Figure 2is a structural schematic diagram of a first solar cell provided by an embodiment of the present application; Figure 3 is a structural schematic diagram of a second solar cell provided by an embodiment of the present application; Figure 4 is a structural schematic diagram of a second cell substrate provided by an embodiment of the present application; Figure 5 is a structural schematic diagram of a third cell substrate provided by an embodiment of the present application; Figure 6 is a structural schematic diagram of a third solar cell provided by an embodiment of the present application; Figure 7 is a structural schematic diagram of a first heterojunction solar cell provided by an embodiment of the present application; Figure 8 is a structural schematic diagram of a fourth solar cell provided by an embodiment of the present application; Figure 9 is Figure 8 is a partial enlarged view of A-A in FIG. 1; Figure 10 is a structural schematic diagram of a second heterojunction solar cell provided by an embodiment of the present application; Figure 11 is a structural schematic diagram of a third heterojunction solar cell provided by an embodiment of the present application.

[0039] Figure legend: 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

[0040] 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 skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "transverse", "longitudinal", and the like indicate the orientation or positional relationship based on 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 intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0042] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned partial 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. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific situation.

[0043] In addition, the terms "first", "second", and the like are mainly used to distinguish different devices, elements or components (the specific types and structures 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 "multiple" is two or more.

[0044] The technical solutions provided by the present application will be further described below in conjunction with the embodiments and the drawings.

[0045] 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, the increase of the contact resistance, and the poor photoelectric conversion performance of the solar cell.

[0046] 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.

[0047] 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.

[0048] The embodiments of the present application disclose a solar cell, such as Figures 1 to 7 As shown in the drawings, the solar cell comprises: a cell substrate 1, at least one side surface of the cell substrate 1 is provided with a groove structure 1a; an electrode structure 2, the electrode structure 2 is arranged at the groove structure 1a, and the electrode structure 2 comprises: a conductive metal layer 21, the conductive metal layer 21 comprises a first sub-part 211 and a second sub-part 212 connected with each other, the first sub-part 211 is filled in the groove structure 1a, and the second sub-part 212 is exposed outside the cell substrate 1; an oxidation-resistant layer 22, the oxidation-resistant layer 22 is coated on a surface of the second sub-part 212, the oxidation resistance of the oxidation-resistant layer 22 is higher than that of the conductive metal layer 21, and the oxidation-resistant layer 22 is configured to be prepared by placing the cell substrate 1 containing the conductive metal layer 21 in a reaction solution containing oxidation-resistant metal ions; wherein, along a thickness direction (see Figure 2 Y direction in the drawings) of the cell substrate 1, a height of the first sub-part 211 is H1, and a height of the second sub-part 212 is H2, H1 satisfies 1 μm≤H1<3 μm, and H2 satisfies 5 μm≤H2≤15 μm.

[0049] The cell substrate 1 represents a semi-finished product which has been prepared with other functional film layers but lacks the electrode structure 2, that is, the cell substrate 1 comprises a silicon substrate 11 and a 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 profile retention characteristic, 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 cell 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.

[0050] In addition, the oxidation resistance of the oxidation-resistant layer 22 is higher than that of the conductive metal layer 21, that is, the stability of oxidation-resistant metal ions in the oxidation-resistant layer 22 is relatively high, and the oxidation-resistant metal ions are difficult to react with oxygen in the air and the like, while the stability of metal ions in the conductive metal layer 21 is relatively low, and the metal ions 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 comprise at least one of copper ions and aluminum ions, the oxidation-resistant metal ions comprise at least one of tin ions, silver ions and gold ions. The present application does not limit the types of the oxidation-resistant metal ions and the metal ions in the conductive metal layer 21, as long as the oxidation resistance of the oxidation-resistant layer 22 is higher than that of the conductive metal layer 21, so that the oxidation-resistant layer 22 can protect the conductive metal layer 21 and prevent the conductive metal layer 21 from being exposed and oxidized.

[0051] The preparation method of the anti-oxidation layer 22 includes a chemical method or an electroplating method, and when the two methods are used, the reaction solution containing the anti-oxidation metal ions is used. For example, when the anti-oxidation metal ions are tin ions, the chemical solution in the chemical tin plating and the electroplating solution in the electroplated tin contain the 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.

[0052] The electrode structure 2 of the present application includes the conductive metal layer 21 and the anti-oxidation layer 22 covering the surface of the conductive metal layer 21, wherein the conductive metal layer 21 includes the first sub-part 211 located inside the groove structure 1a and the second sub-part 212 located outside the groove structure 1a, and therefore, since the anti-oxidation property of the anti-oxidation layer 22 is higher than that of the conductive metal layer 21, the anti-oxidation layer 22 can effectively prevent the oxidation and erosion of the second sub-part 212 by the external environment, thereby helping to ensure the structural stability of the second sub-part 212.

[0053] However, the applicant finds that the anti-oxidation layer 22 is prepared by placing the battery substrate 1 containing the conductive metal layer 21 in the reaction solution containing the anti-oxidation metal ions, and therefore, this may affect the bonding tightness of the battery substrate 1 and the first sub-part 211.

[0054] Therefore, the present application sets the H1 in a specific value range, so that the height of the first sub-part 211 filled inside the groove structure 1a is appropriate, and then, due to the appropriate height, the downward penetration of the reaction solution containing the anti-oxidation metal ions is prevented, and the corrosion of the bottom of the conductive metal layer 21 by the reaction solution is avoided, thereby helping to avoid the falling off of the electrode structure 2; and also, it helps to increase the contact area of the side wall of the groove structure 1a and the electrode structure 2, further improves the contact tightness of the groove structure 1a and the electrode structure 2, and optimizes the structural stability of the first sub-part 211; in addition, the H1 in the 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.

[0055] In addition, by setting the H2 in a specific range, the anti-oxidation 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, which helps to reduce the protection pressure of the anti-oxidation layer 22, so that the anti-oxidation layer 22 can fully play its role, and the problem of local protection failure caused by a large protection area is avoided, 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, and therefore, this provides a stable basis for the soldering of the solder strip, and the effectiveness of the soldering of the solder strip is ensured to a higher degree.

[0056] 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.

[0057] In summary, the synergy of H1, H2 and the oxidation-resistant layer 22 jointly solves the problems of corrosion protection of the first sub-part 211 and the bonding strength of the battery base 1, and the problems of environmental resistance and welding reliability of the second sub-part 212, thereby helping to improve the structural stability of the electrode structure 2 and improve the transmission capacity of the electrode structure 2 to the charge carriers.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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).

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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

[0067] 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.

[0068] 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 makes the effective volume of the cell substrate 1 be guaranteed, 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.

[0069] 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, W1, W2 satisfy: W1:W2=(6:5)~(9:5). When the ratio of the width of the top and the bottom of the groove structure 1a 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 surface 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.

[0070] Further, W1 satisfies: 15μm≤W1≤20μm, and W2 satisfies: 8μm≤W2≤12μm. When the width of the top and the bottom of the groove structure 1a 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 surface 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.

[0071] 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 helps 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.

[0072] In another optional embodiment, as shown in Figure 8 the groove structure 1a comprises a first groove substructure 11a and a second groove substructure 12a, and the battery substrate 1 comprises: a silicon substrate 11, at least one side surface of the silicon substrate 11 is provided with the first groove substructure 11a; The functional layer 12 is provided on the silicon substrate 11. A second groove substructure 12a is provided on the surface of the functional layer 12 facing away from the silicon substrate 11. The second groove substructure 12a corresponds to the position of the first groove substructure 11a. The first sub-portion 211 of the conductive metal layer 21 is filled in the second groove sub-structure 12 a , and the second sub-portion 212 is exposed outside the functional layer 12 .

[0073] In this embodiment, since the first groove substructure 11a is formed directly on the silicon substrate 11, and based on the conformal characteristics, when the functional layer 12 is deposited on the first groove substructure 11a, a second groove substructure 12a corresponding to the position of the first groove substructure 11a is also formed on the functional layer 12, so the characteristics of the second groove substructure 12a are the same as those of the first groove substructure 11a.

[0074] In addition, the depth of the first groove substructure 11a set on the silicon substrate 11 will affect the thickness of the silicon substrate 11. Therefore, the present application ensures the thickness of the silicon substrate 11 and the light absorption effect of the silicon substrate 11 by controlling H1; in addition, when the first groove substructure 11a is set on the silicon substrate 11, since other functional film layers have not yet been deposited, it also helps to avoid damage to other film layers when forming the first groove substructure 11a, thereby reducing the recombination of carriers to a greater extent.

[0075] Furthermore, if Figure 9 As shown, on the silicon substrate 11, the silicon substrate 11 includes a first area corresponding to the position of the first groove substructure 11a, and a second area outside the first area; There is a micro-protrusion structure on the silicon substrate 11 in the first region; and a first pyramid structure 111 is provided on the silicon substrate 11 in the second region.

[0076] In an optional embodiment, the micro-protrusion structure is a second pyramid structure 112 ; wherein the distance between the top of the second pyramid structure 112 closest to the sidewall of the first groove substructure 11 a and the sidewall is less than 1 μm.

[0077] Among them, see Figure 9 The second pyramid structure 112 closest to the side wall is the second pyramid structure 112 with the smallest distance from the side wall of the first groove substructure 11a, and the distance between the top of the second pyramid structure 112 and the side wall is W3.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] Further, L1 satisfies: 1 μm≤L1≤3 μm, and L2 satisfies: 0.75 μm≤L2≤2.2 μm. 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 to the carriers and the structural stability of the electrode structure 2. Exemplarily, L1 is 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc.; and L2 is 0.75 μm, 1 μm, 1.5 μm, 2 μm, 2.2 μm, etc.

[0085] 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

[0086] 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 a first passivation layer 121 arranged on the silicon substrate 11 on the light-receiving surface; a first doped silicon layer 122 arranged on a side surface of the first passivation layer 121 away from the silicon substrate 11; a first transparent conductive layer 123 arranged on a 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; a second passivation layer 124 arranged on the silicon substrate 11 on the back surface; a second doped silicon layer 125 arranged on a side surface of the second passivation layer 124 away from the silicon substrate 11; a second transparent conductive layer 126 arranged on a 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; wherein 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, and one of the first electrode structure 2a and the second electrode structure 2b is a positive electrode, and the other is a negative electrode.

[0087] ​​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 substructure 11a, the functional layer 12 will correspondingly have the second recess substructure 12a, thereby helping to increase the contact area of the first electrode structure 2a with the first transparent conductive layer 123, the contact area of the second electrode structure 2b with 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.

[0088] 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, it helps to reduce the recombination of carriers and improve the transmission capability of carriers.

[0089] In addition, in the first recess substructure 11a on the back surface, the ratio of the area of the second transparent conductive layer 126 to the area of the first recess substructure 11a is greater than 85%; and in the first recess substructure 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 substructure 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 carriers and the performance of the solar cell.

[0090] The present application provides a preparation method of a solar cell, which comprises the following steps: Grooving at least one side surface of the cell substrate to form a recess structure on the cell substrate; Preparation of a conductive metal layer on the recess structure, the conductive metal layer comprising a first subpart and a second subpart connected to each other, the first subpart being filled in the recess structure, and the second subpart being exposed outside the cell substrate, placing the cell substrate containing the conductive metal layer in a reaction solution containing anti-oxidation metal ions to prepare an anti-oxidation layer, and the anti-oxidation layer has a higher anti-oxidation property than the conductive metal layer, thereby obtaining an electrode structure; Wherein, along the thickness direction of the cell substrate, the height of the first subpart is H1, and the height of the second subpart is H2, H1 satisfies: 1 μm≤H1<3 μm; and H2 satisfies: 5 μm≤H2≤15 μm.

[0091] 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, wherein 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 muJ to 15 muJ.

[0092] By using the preparation method, the slotting effect can be effectively ensured, laser damage is reduced, and the recombination degree of carriers is reduced.

[0093] Further, the step of preparing the electrode structure comprises: By screen printing, the slurry is printed on the groove structure, so that part of the slurry is filled in the interior of the groove structure to form a first sub-part, and the remaining part of the slurry is exposed outside the groove structure to form a second sub-part; and the conductive metal layer is prepared after drying and vacuum curing of the slurry. Light injection; The battery substrate containing the conductive metal layer is placed in a reaction solution containing tin ions to prepare an oxidation-resistant layer.

[0094] In the present application, the preparation of the oxidation-resistant layer after light injection 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.

[0095] Further, the oxidation-resistant layer is prepared on the conductive metal layer by electroless tin plating, at a temperature of 60 DEG C to 80 DEG C and for a time of 30 s to 300 s, and 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. 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.

[0096] In addition, the additive capable of changing the reaction potential helps to promote the displacement reaction of tin ions with the conductive metal layer to generate tin. By controlling the mass concentrations of the tin salt, the acid adjuster, the reducing agent, and the additive in the electroless tin plating solution, the time, and the temperature within the above ranges, the reactivity can be effectively ensured, and the thickness uniformity, the compactness, and the corrosion resistance of the prepared oxidation-resistant layer can be improved.

[0097] 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.

[0098] Further, the method further comprises cleaning the conductive metal layer before the step of placing the battery substrate containing the conductive metal layer in the reaction solution containing tin ions to prepare the oxidation-resistant layer.

[0099] Cleaning the conductive metal layer before preparing the oxidation-resistant layer helps remove impurities on the conductive metal layer and ensures that the conductive metal layer is tightly combined with the oxidation-resistant layer.

[0100] Further, 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 grooving at least one side surface of the battery substrate includes: grooving at least one side surface of the silicon substrate to form the first groove substructure on the silicon substrate; preparing the functional layer on the silicon substrate, the functional layer being provided with the 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; 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.

[0101] Further, the silicon substrate includes a first region corresponding in position to the first groove substructure and a second region outside the first region; Further, the method further comprises, after the step of grooving at least one side surface of the silicon substrate and before the step of preparing the functional layer on the silicon substrate, 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 a distance between a tip of a second pyramid structure closest to a side wall of the first groove substructure and the side wall is less than 1 μm.

[0102] Further, the silicon substrate includes a light-receiving surface and a back surface disposed opposite to each other, the light-receiving surface and the back surface of the silicon substrate are respectively grooved to form the first groove substructure on the light-receiving surface and the back surface of the silicon substrate, and the electrode structure includes a first electrode structure and a second electrode structure. The step of preparing the functional layer on the silicon substrate includes: preparing a first passivation layer on the light-receiving surface of the silicon substrate; preparing a second passivation layer on the back surface of the silicon substrate; preparing a first doped silicon layer on the first passivation layer; preparing a second doped silicon layer 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; The first electrode structure is in ohmic contact with the first transparent conductive layer, and 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.

[0103] The application further discloses a photovoltaic module, which comprises the solar cell or the solar cell prepared by the preparation method.

[0104] The technical solutions of the application will be further explained in combination with more specific embodiments and experimental test results.

[0105] Embodiment one: The application provides a preparation method of a heterojunction solar cell.

[0106] S1. preparing a cell substrate, wherein the cell substrate comprises a silicon substrate and a functional layer arranged on the silicon substrate; S1.1 performing laser slotting treatment on a light-receiving surface and a back surface of the N-type silicon substrate to form a first groove substructure, wherein the pulse width is 10 ps, the wavelength of the ultraviolet light is 355 nm, the frequency is 150 kHz, the pulse energy is 9 μJ, 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.

[0107] S1.2 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 substructure and the sidewall is less than 1 μm, the tip of the second pyramid structure presents an arc structure, L1 is 2.5 μm, and L2 is 1.75 μm.

[0108] S1.3 preparing the functional layer, and the functional layer has a second groove substructure corresponding to the position of the first groove substructure, and the shape of the second groove substructure is the same as that of the first groove substructure: S1.3.1 preparing a first passivation layer with a thickness of 6 nm on the back 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; S1.3.2 Depositing a second doped silicon layer with a thickness of 35 nm on the first passivation layer by PECVD, the second doped silicon layer being a P-type doped silicon layer; Depositing a second doped silicon layer with a thickness of 20 nm on the second passivation layer by PECVD, the second doped silicon layer being an N-type doped silicon layer.

[0109] S1.3.3 Preparing a first transparent conductive layer on the first doped silicon layer by PVD; Preparing a second transparent conductive layer on the second doped silicon layer, to obtain a functional layer.

[0110] S2 Preparing an electrode structure: S2.1 Printing copper paste on the second recessed substructure of the second transparent conductive layer of the back light surface and the second recessed substructure of the first transparent conductive layer of the light receiving surface respectively by screen printing, so that part of the paste is filled in the interior of the second recessed substructure to form a first subpart, and the remaining paste is exposed outside the second recessed substructure to form a second subpart; After drying and vacuum curing of the paste, a conductive metal layer is obtained, wherein the second subpart includes an intermediate subpart and an epitaxial subpart, H1 is 2.8 μm, and H2 is 8 μm; S2.2 Light injection; 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, and 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.

[0111] Example Two: The difference between this example and Example One is that H1 is 1 μm and H2 is 15 μm in this example.

[0112] Example Three: The difference between this example and Example One is that H1 is 2.9 μm and H2 is 5 μm in this example.

[0113] Example Four: The difference between this example and Example One is that W1:W2 is 6:5.

[0114] Example Five: The difference between this example and Example One is that the cross section of the first recessed substructure presents a rectangular structure in the direction of the electrode structure pointing to the battery substrate, i.e., W1:W2 is 1:1.

[0115] Example Six: The difference between this example and Example One is that the tip of the second pyramid structure is a sharp cone structure.

[0116] Example Seven The difference between this example and Example 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.

[0117] Example Eight The difference between this example and Example 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.

[0118] Example Nine The difference between this example and Example One is that the groove structure of this example is only provided on the transparent conductive layer.

[0119] Comparative Example One The difference between this comparative example and Example One is that the battery substrate of this comparative example is not provided with a groove structure, i.e. the battery substrate is a planar structure, and the electrode structure is provided on the planar structure.

[0120] Comparative Example Two The difference between this comparative example and Example One is that H1 of this comparative example is 3 μm.

[0121] Comparative Example Three The difference between this comparative example and Example One is that H2 of this comparative example is 3 μm.

[0122] Comparative Example Four The difference between this comparative example and Example One is that H2 of this comparative example is 17 μm.

[0123] Performance Test The solar cells prepared in Examples One to Nine and Comparative Examples One to Four were subjected to the following relevant tests: The solar cell provided in this application was subjected to performance tests in terms of open circuit voltage, short circuit current and fill factor using a test machine with a model of GIV-60 and a manufacturer of 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.

[0124] Table 1 Performance test results of the solar cell

[0125] From the data of the example one and the comparative example one, it can be seen that the photoelectric conversion efficiency of the solar cell of the example one is better than that of the comparative example one. It can be seen that the first groove substructure arranged on the silicon substrate can avoid the etching of the reaction solution to the bottom of the electrode structure, and ensure the connection tightness of the electrode structure and the transparent conductive layer. The comparative example one does not have the 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 of the electrode structure and the transparent conductive layer to decrease, and causing the electrode structure to be more easily separated from the transparent conductive layer.

[0126] From the data of the example one to the example three and the comparative example two to the comparative example four, it can be seen that the photoelectric conversion efficiency of the example one to the example three is better than that of the comparative example two to the comparative example four. It can be seen that when H1 and H2 satisfy the range of 1≤H1<3μm and 5≤H2≤15μm, the matching between H1 and H2 is higher, and under the synergistic effect of the two, the connection stability of the first subpart and the transparent conductive layer can be ensured, and the protection effect of the anti-oxidation layer on the second subpart can be optimized, thereby helping to optimize the performance of the solar cell.

[0127] From the data of the example one to the example three, it can be seen that the photoelectric conversion efficiency of the example one and the example three is better than that of the example two. It can be seen that H1 and H2 in the example one and the example three have a higher matching, and the higher matching is more helpful to improve the structural stability of the electrode structure and improve the collection capacity of the electrode structure to the carriers.

[0128] From the data of the example one, the example four and the example five, it can be seen that the photoelectric conversion efficiency of the example one and the example four is better than that of the example five. It can be seen that the ratio of W1 and W2 of the example one and the example four is more appropriate, and the more appropriate ratio can further ensure the effective volume of the cell 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.

[0129] From the data of the example one and the example six, it can be seen that the photoelectric conversion efficiency of the example one is better than that of the example six. It can be seen that when the tower tip of the second pyramid structure is an arc structure, the stress concentration phenomenon at the tower tip can be effectively avoided, the coverage of the functional layer at the tower tip is more dense and uniform, and the effect of the functional layer can be ensured, thereby further improving the performance of the solar cell.

[0130] From the data of the example one and the example seven, it can be seen that the photoelectric conversion efficiency of the example one is better than that of the example seven. It can be seen that when the distance between the tower tip of the second pyramid structure closest to the side wall of the first groove substructure and the side wall is less than 1μm, the number of the second pyramid structures in the first groove substructure is relatively more, and the combination tightness of the transparent conductive layer and the electrode structure can be more improved.

[0131] From the data of Example 1 and Example 8, it can be seen that the photoelectric conversion efficiency of Example 1 is better than that of Example 8. It can be seen that when L2 is less than L1, the second pyramid structure can provide more suitable roughness, thereby helping to improve the contact effect of the electrode structure and the transparent conductive layer to a higher degree.

[0132] From the data of Example 9, it can be seen that the photoelectric conversion efficiency of Example 9 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.

[0133] The above has introduced in detail the solar cell and the preparation method thereof and the photovoltaic module disclosed by the embodiments of the present application, the principles and implementation manners of the present application are described by applying specific examples, the above embodiment is only used to help understand the solar cell and the preparation method thereof and the photovoltaic module: at the same time, for the general skilled 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 comprises: A battery substrate, wherein at least one side surface of the battery substrate is provided with a groove structure; An electrode structure, the electrode structure being provided at the groove structure, the electrode structure comprising: a conductive metal layer, 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 battery substrate; an anti-oxidation layer coated on a surface of the second sub-section, the anti-oxidation layer having higher oxidation resistance than the conductive metal layer, and the anti-oxidation layer being prepared by placing the battery substrate containing the conductive metal layer in a reaction solution containing anti-oxidation metal ions; Wherein, along the thickness direction of the battery substrate, the height of the first sub-portion is H1, the height of the second sub-portion is H2, and H1 satisfies: 1 μm≤H1<3 μm; and H2 satisfies: 5 μm≤H2≤15 μm.

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

3. The solar cell according to claim 1, wherein The second subsection includes: an intermediate subsection, the intermediate subsection being located on a surface of the first subsection facing away from the battery substrate, and the position of the intermediate subsection being within a range corresponding to the position of the first subsection; The extension sub-portion is extended outward from the middle sub-portion, and the extension sub-portion is in contact with the surface of the battery substrate outside the groove structure.

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

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

6. The solar cell according to claim 1, wherein Along the direction from the electrode structure to the battery substrate, the cross section of the groove structure presents a structure that 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: 15 μm ≤ W1 ≤ 20 μm, and the W2 satisfies: 8 μm ≤ W2 ≤ 12 μm.

9. The solar cell according to claim 1, wherein The groove structure includes a first groove substructure and a second groove substructure, and the battery substrate includes: a silicon substrate, wherein the first groove substructure is provided on at least one surface of the silicon substrate; a functional layer, the functional layer being disposed on the silicon substrate, the second groove substructure being disposed on a surface of the functional layer facing away from the silicon substrate, the second groove substructure corresponding to a position of the first groove substructure; 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.

10. The solar cell according to claim 9, characterized in that On the silicon substrate, the silicon substrate includes a first area corresponding to the position of the first groove substructure, and a second area outside the first area; Wherein, a micro-protrusion structure is provided on the silicon substrate in the first region; and a first pyramid structure is provided on the silicon substrate in the second region.

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 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; and / or, The top of the second pyramid structure is an arc-shaped structure.

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, and L2 is smaller than L1.

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

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

15. The solar cell according to claim 1, wherein The metal material of the conductive metal layer includes at least one of copper and aluminum; and / or, The thickness of the anti-oxidation layer is 1 μm to 5 μm; and / or, The metal material of the anti-oxidation 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 backlight surface disposed opposite to each other, each of the light-receiving surface and the backlight surface is provided with the first groove substructure, the electrode structure includes a first electrode structure and a second electrode structure, and the functional layer includes: a first passivation layer, the first passivation layer being disposed on the silicon substrate on the light-receiving surface; a first doped silicon layer, the first doped silicon layer being disposed on a surface of the first passivation layer facing away from the silicon substrate; a first transparent conductive layer, wherein the first transparent conductive layer is disposed on a surface of the first doped silicon layer facing 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, the second passivation layer being disposed on the silicon substrate on the backlight surface; a second doped silicon layer, the second doped silicon layer being disposed on a surface of the second passivation layer facing away from the silicon substrate; a second transparent conductive layer, the second transparent conductive layer being disposed on a surface of the second doped silicon layer facing away from the second passivation layer, the second electrode structure being in ohmic contact with the second transparent conductive layer; Among them, 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.

17. A method for preparing a solar cell, characterized in that: The preparation method of the solar cell comprises the following steps: Grooving at least one side of the battery substrate to form a groove structure on the battery substrate; A conductive metal layer is prepared on the groove structure, wherein the conductive metal layer includes a first sub-portion and a second sub-portion connected to each other, wherein the first sub-portion is filled in the groove structure and the second sub-portion is exposed outside the battery substrate, and the battery substrate containing the conductive metal layer is placed in a reaction solution containing antioxidant metal ions to prepare an antioxidant layer, wherein the antioxidant layer has higher antioxidant properties than the conductive metal layer, thereby preparing an electrode structure; Wherein, along the thickness direction of the battery substrate, the height of the first sub-portion is H1, the height of the second sub-portion is H2, and H1 satisfies: 1 μm≤H1<3 μm; and H2 satisfies: 5 μm≤H2≤15 μm.

18. The preparation method according to claim 17, characterized in that: In the step of grooving at least one side of the surface of the battery substrate, the grooves are formed on at least one side of the surface of the battery substrate using laser processing, wherein the laser parameters 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 μJ to 15 μJ.

19. The preparation method according to claim 18, characterized in that The steps of preparing the electrode structure include: Printing slurry on the groove structure by screen printing, so that part of the slurry fills the interior of the groove structure to form the first sub-portion, and the remaining part of the slurry is exposed outside the groove structure to form the second sub-portion; drying the slurry and vacuum curing it to obtain the conductive metal layer; Light injection; The battery substrate containing the conductive metal layer is placed in a reaction solution containing tin ions to prepare the anti-oxidation layer.

20. The preparation method according to claim 19, characterized in that The anti-oxidation layer is prepared on the conductive metal layer by a chemical tin plating method at a temperature of 60°C to 80°C for 30 seconds to 300 seconds. The chemical tin plating solution includes a tin salt, an acidic regulator, 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. In the chemical tin plating solution, the mass concentration of the tin salt is 10 g / L~20 g / L, the volume percentage of the acidic regulator is 5%~10%, the mass concentration of the reducing agent is 10 g / L~30 g / L, and the mass concentration of the additive is 0.1 g / L~1 g / L.

21. The preparation method according to claim 20, characterized in that The tin salt is at least one of tin chloride, stannous citrate, and stannous tartrate; and / or, The acidic 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 anti-oxidation 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 groove-forming at least one side of the surface of the battery substrate includes: Grooving at least one side surface of the silicon substrate to form the first groove substructure on the silicon substrate; The functional layer is prepared on the silicon substrate, wherein a second sub-groove structure is provided on a surface of the functional layer facing away from the silicon substrate, and the second sub-groove structure corresponds to a position of the first sub-groove structure; 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.

24. The preparation method according to claim 23, characterized in that The silicon substrate includes a first area corresponding to the position of the first groove substructure, and a second area outside the first area; After the step of grooving 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 includes: cleaning and texturing the silicon substrate to form a first pyramid structure on the silicon substrate in the second area, and forming a second pyramid structure on the silicon substrate in the first area, wherein the distance between the 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.

25. The preparation method according to claim 23, characterized in that The silicon substrate includes a light-receiving surface and a backlight surface disposed opposite to each other, and the light-receiving surface and the backlight surface of the silicon substrate are grooved to form the first groove substructure on the light-receiving surface and the backlight surface of the silicon substrate, and the electrode structure includes a first electrode structure and a second electrode structure; The step of preparing a functional layer on the silicon substrate comprises: preparing a first passivation layer on the light-receiving surface of the silicon substrate; preparing a second passivation layer on the backlight surface of the silicon substrate; forming a first doped silicon layer on the first passivation layer; forming a second doped silicon layer on the second passivation layer; forming a first transparent conductive layer on the first doped silicon layer; forming a second transparent conductive layer on the second doped silicon layer; Among them, 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, and one of the first electrode structure and 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 comprises: the solar cell according to any one of claims 1 to 16, or the solar cell prepared by the preparation method according to any one of claims 17 to 25.

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