Composite electrode and preparation method thereof, solar cell and preparation method thereof, and photovoltaic module

Abstract

The invention provides a composite electrode and a preparation method thereof, a solar cell and a preparation method thereof, and a photovoltaic module. The composite electrode comprises a transparent conductive layer, a metal composite layer and an electroplated metal layer which are sequentially stacked; the metal composite layer comprises a metal simple substance part, and the electroplated metal layer is located on at least part of the surface, away from the transparent conductive layer, of the metal simple substance part; metal elements in the metal composite layer and the metal simple substance part comprise at least one of tin, aluminum and zinc. The composite electrode is high in stability and excellent in photoelectric performance, and when the composite electrode is applied to a solar cell, the photoelectric performance of the solar cell can be improved, and the photoelectric performance of a photovoltaic module is improved.

Description

Technical Field

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

[0002] Heterojunction solar cells (HJT), a new type of solar cell, have become a hot topic in the photovoltaic field this year. Traditional HJT solar cells typically use screen printing to create metal electrodes, which results in high silver paste consumption and high cell costs. Using electroplating to create metal electrodes (such as copper and tin) instead of traditional screen printing is expected to reduce cell costs.

[0003] Currently, the electroplating method for preparing metal electrodes mainly includes the following steps: preparing a seed layer (such as a copper seed layer or a silver seed layer) on the surface of a transparent conductive layer (TCO) by physical vapor deposition (PVD), then pressing a dry film (or spraying a photoresist or ink), exposing, developing, and electroplating copper on the surface of the seed layer away from the TCO layer to form an electroplated metal layer, then removing the mask (or photoresist, ink) using an alkaline solution, and then removing the seed layer using an acidic solution or an alkaline solution to obtain a metal electrode. This metal electrode includes a transparent conductive layer and an electroplated metal layer located on the surface of the transparent conductive layer. However, the adhesion between the electroplated metal layer and the transparent conductive layer is poor, resulting in low stability of the metal electrode, which is not conducive to the photoelectric performance of the metal electrode. Summary of the Invention

[0004] In view of the above-mentioned defects, the present invention provides a composite electrode with high stability, excellent photoelectric performance, and suitable for wide promotion and application.

[0005] The present invention provides a method for preparing a composite electrode, which can prepare the composite electrode and is simple to operate.

[0006] The present invention provides a solar cell comprising the composite electrode and having excellent photoelectric performance.

[0007] The present invention provides a method for preparing a solar cell, which can prepare a solar cell with excellent photoelectric performance.

[0008] The present invention provides a photovoltaic component, comprising the above-mentioned solar cell, and the photovoltaic component has excellent photoelectric performance.

[0009] The present invention provides a composite electrode, which comprises a transparent conductive layer, a metal composite layer and an electroplated metal layer stacked in sequence;

[0010] The metal composite layer includes a metal single substance portion, and the electroplated metal layer is located on at least a portion of the surface of the metal single substance portion away from the transparent conductive layer;

[0011] The metal elements in the metal composite layer and the metal single substance portion include at least one of tin, aluminum, and zinc.

[0012] In the composite electrode as described above, the metal element portion and the transparent conductive layer are connected via a chemical bond.

[0013] The composite electrode as described above, wherein the metal composite layer further comprises a metal oxide portion interconnected with the metal element portion, and the metal oxide portion is located on the surface of the transparent conductive layer;

[0014] The metal element of the metal oxide portion includes at least one of tin, aluminum, and zinc.

[0015] In the composite electrode as described above, the metal composite layer includes a plurality of the metal single-substance portions, the electroplated metal layer includes a plurality of metal portions, and the metal single-substance portions correspond to the metal portions in a one-to-one manner.

[0016] The composite electrode as described above, wherein the area of ​​the first orthographic projection of the metal single substance portion on the transparent conductive layer accounts for 1%-3% of the area of ​​the second orthographic projection of the metal composite layer on the transparent conductive layer; and / or,

[0017] In the metal element portion, the molar content of the metal element accounts for 50% to 80% of the total molar content of the metal elements.

[0018] In the composite electrode as described above, the metal single substance portion has an average particle size of 10 nm to 50 nm.

[0019] In the composite electrode as described above, in the metal element, the number of metal element particles with a particle size of 20 nm to 40 nm accounts for 50% to 80% of the total number of metal element particles.

[0020] The composite electrode as described above, wherein the thickness of the transparent conductive layer is 30 nm to 80 nm; and / or,

[0021] The thickness of the metal composite layer is 30nm-50nm.

[0022] The present invention provides a method for preparing the composite electrode as described above, comprising:

[0023] Disposing a metal oxide layer on one surface of the transparent conductive layer;

[0024] performing a reduction treatment on a portion of the surface of the metal oxide layer away from the transparent conductive layer to obtain a metal composite layer including a metal single substance portion;

[0025] The electroplated metal layer is formed on at least a portion of the surface of the metal element portion away from the transparent conductive layer to obtain the composite electrode.

[0026] The present invention provides a solar cell, comprising the composite electrode as described above; or comprising a composite electrode prepared by the method for preparing the composite electrode as described above.

[0027] The solar cell as described above, wherein the solar cell further comprises a silicon substrate and a selective passivation layer;

[0028] The selective passivation layer is respectively located on two surfaces of the silicon substrate, and the composite electrode is located on a surface of the selective passivation layer away from the silicon substrate.

[0029] The solar cell as described above, further comprises an anti-reflection layer, wherein the anti-reflection layer is located on at least a portion of the surface of the metal oxide portion away from the transparent conductive layer.

[0030] The solar cell as described above is characterized in that the anti-reflection layer comprises at least one of silicon oxide, silicon nitride, magnesium fluoride and lithium fluoride; and / or,

[0031] The thickness of the anti-reflection layer is 60nm-200nm.

[0032] The present invention provides a method for preparing the solar cell as described above, comprising:

[0033] Performing texturing treatment on the silicon wafer to obtain a texturing silicon wafer;

[0034] Disposing selective passivation layers on both surfaces of the texturing silicon wafer;

[0035] The composite electrodes as described above are respectively arranged on the surface of the selective passivation layer away from the textured silicon wafer.

[0036] The present invention provides a photovoltaic assembly, which includes the solar cell described above; or includes a solar cell prepared by the method for preparing a solar cell described above.

[0037] In the composite electrode of the present invention, the metal single substance portion and the electroplated metal layer have excellent adhesion, which can improve the stability of the composite electrode. In addition, the metal single substance portion has excellent conductivity, which is beneficial to improving the photoelectric conversion efficiency of the composite electrode.

[0038] The preparation method of the composite electrode of the present invention can prepare the composite electrode mentioned above, and the preparation method is simple to operate and suitable for wide promotion and application.

[0039] The solar cell of the present invention includes the composite electrode, so the solar cell has excellent stability and excellent photoelectric conversion efficiency, and is suitable for wide promotion and application.

[0040] The method for preparing a solar cell of the present invention can prepare a solar cell with excellent photoelectric performance. The method is simple to operate and low in cost, and can broaden the application of solar cells.

[0041] The present invention provides a photovoltaic module, comprising the above-mentioned solar cell. The photovoltaic module has excellent photoelectric performance and stability and is suitable for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the structure of the composite electrode in some embodiments of the present invention;

[0043] Figure 2 This is a schematic structural diagram of a solar cell in a first embodiment of the present invention;

[0044] Figure 3 This is a schematic structural diagram of a solar cell in a second embodiment of the present invention;

[0045] Figure 4 A schematic structural diagram of a solar cell in a third embodiment of the present invention;

[0046] Figure 5 The figure is a flow chart of the preparation of solar cells in some embodiments of the present invention.

[0047] Description of reference numerals:

[0048] 1: Composite electrode;

[0049] 11: transparent conductive layer;

[0050] 12: Metal composite layer;

[0051] 13: electroplated metal layer;

[0052] 14: anti-reflection layer;

[0053] 15: silicon substrate;

[0054] 16: selective passivation layer;

[0055] 121: Metal element part;

[0056] 122: Metal oxide section;

[0057] 131: Metal Department;

[0058] 161: passivation contact layer;

[0059] 162: N-type doped layer;

[0060] 163: P-type doped layer. DETAILED DESCRIPTION

[0061] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0062] Existing metal electrodes include a transparent conductive layer and an electroplated metal layer located on the surface of the transparent conductive layer. However, the poor adhesion between the electroplated metal layer and the transparent conductive layer results in poor stability of the metal electrode, limiting its applications. In view of this, the present invention improves the stability of the metal electrode by optimizing the adhesion between the metal electrode layers, thereby broadening its applications.

[0063] In the present invention, the first direction may be the length direction of the composite electrode or the width direction of the composite electrode. The second direction intersects with the first direction and may be perpendicular to each other. The second direction may be the thickness direction of the composite electrode.

[0064] Figure 1 Schematic diagram of the structure of the composite electrode in some embodiments of the present invention. Figure 1 As shown, the first aspect of the present invention provides a composite electrode, comprising a transparent conductive layer 11, a metal composite layer 12 and an electroplated metal layer 13 stacked in sequence;

[0065] The metal composite layer 12 includes a metal single substance portion 121 , and the electroplated metal layer 13 is located on at least a portion of the surface of the metal single substance portion 121 away from the transparent conductive layer 11 ;

[0066] The metal elements in the metal composite layer 12 and the metal element portion 121 include at least one of tin, aluminum, and zinc.

[0067] In the present invention, the metal element portion 121 refers to the portion of the metal composite layer 12 that includes metal element particles. The present invention does not particularly limit the shape of the metal element portion 121, as long as the electroplated metal layer 13 can be provided on the surface of the metal element portion 121 away from the transparent conductive layer 11. In the second direction of the composite electrode 1, the size of the metal element portion 121 can be equal everywhere, or the size of the metal element portion 121 can be unequal. For example, the width of the metal element portion 121 in the first direction tends to decrease along the direction from the metal composite layer 12 to the transparent conductive layer 11; the cross-section of the metal element portion 121 parallel to the second direction (the cross-section parallel to the second direction) is arc-shaped.

[0068] The electroplated metal layer 13 of the present invention may be located on the entire surface of the metal element portion 121 , or may be located on a portion of the surface of the metal element portion 121 .

[0069] In the present invention, the metal elements in the metal composite layer 12 and the metal element portion 121 may be the same or different. Furthermore, the metal elements in the metal composite layer 12 and the metal element portion 121 are the same. For example, the metal element in the metal composite layer 12 includes tin, and the metal composite layer 12 may be a tin composite layer. The metal element in the metal element portion 121 includes tin, and the metal element portion 121 may be a single tin portion.

[0070] The presence of metal particles in the metal element portion 121 can increase the roughness of the metal element portion 121, thereby enabling a closer connection between the electroplated metal layer 13 and the metal composite layer 12, improving the stability of the composite electrode 1, and further improving the photoelectric performance of the composite electrode 1. Furthermore, the metal particles have excellent electrical conductivity, which can further improve the photoelectric conversion efficiency of the composite electrode 1.

[0071] Furthermore, the chemical bond between the metal element portion 121 and the transparent conductive layer 11 of the present invention can improve the adhesion between the metal composite layer 12 and the transparent conductive layer 11, thereby improving the adhesion between the layers of the composite electrode 1, and thereby improving the photoelectric performance of the composite electrode. In some embodiments, XPS can be used to obtain an energy spectrum of the metal elements in the metal element portion 121. Based on the energy spectrum of the metal elements, the bonding mode between the metal elements in the metal element portion 121 and the transparent conductive layer 11 can be determined.

[0072] Furthermore, in the first direction, the metal composite layer 12 further includes a metal oxide portion 122 interconnected with the metal single substance portion 121, and the metal oxide portion 122 is located on the surface of the transparent conductive layer 11; the metal element of the metal oxide portion 122 includes at least one of tin, aluminum and zinc.

[0073] In the present invention, the metal element in the metal oxide portion 122 may be the same as or different from the metal element in the metal element portion 121. Further, the metal element in the metal oxide portion 122 is the same as the metal element in the metal element portion 121. For example, the metal element in the metal oxide portion 122 includes tin, the metal oxide portion 122 may be a tin oxide portion, the metal element in the metal element portion 121 includes tin, and the metal element in the metal element portion 121 may be a single tin portion; the metal element in the metal oxide portion 122 includes aluminum and zinc, the metal oxide portion 122 may be an aluminum-doped zinc oxide portion (AZO portion), the metal element in the metal element portion 121 includes aluminum and zinc, and the metal element in the metal element portion 121 may be an aluminum-zinc single portion.

[0074] In the present invention, the metal composite layer 12 includes a metal element portion 121 and a metal oxide portion 122 connected to each other in a first direction, wherein the metal oxide portion 122 is connected to the surface of the transparent conductive layer 11, the metal element portion 121 is connected to the surface of the transparent conductive layer 11 through a chemical bond, and the electroplated metal layer 13 is located on at least a portion of the surface of the metal element portion 121 away from the transparent conductive layer 11.

[0075] The present invention does not impose any particular limitation on the shape of the metal oxide portion 122 . In the thickness direction of the composite electrode 1 , the size of the metal oxide portion 122 may be uniform throughout, or the size of the metal oxide portion 122 may be unequal.

[0076] In the art, the transparent conductive layer 11 is typically formed of rare metals (for example, the transparent conductive layer 11 is an indium oxide layer, where indium is a rare element), and rare metals are expensive. Metal oxides (for example, tin oxide, AZO) have excellent light transmittance. When the metal composite layer 12 also includes a metal oxide portion 122 interconnected with the metal element portion 121, the light transmittance of the composite electrode 1 can be improved (for example, to a transmittance greater than 85%). The metal oxide portion 122 can also replace part of the transparent conductive layer 11, reducing the thickness of the transparent conductive layer 11, thereby reducing the amount of rare metals used and saving costs. At the same time, the high conductivity of the metal element portion 121 and the electroplated metal layer 13 can compensate for the resistance loss of the metal oxide portion 122 in lateral transmission, ensuring that the composite electrode 1 has excellent conductivity, thereby ensuring the photoelectric performance of the composite electrode 1.

[0077] In some embodiments of the present invention, the metal composite layer 12 includes a plurality of metal single-element portions 121 , and the electroplated metal layer 13 includes a plurality of metal portions 131 . The metal single-element portions 121 correspond to the metal portions 131 in a one-to-one manner.

[0078] For example, one metal portion 121 corresponds to one metal portion 131 . For any metal portion 121 , the projection of the metal portion 121 on the transparent conductive layer 11 and the projection of the corresponding metal portion 131 on the transparent conductive layer 11 at least partially overlap.

[0079] Correspondingly, one metal portion 131 corresponds to one metal element portion 121 . For any metal portion 131 , the projection of the metal portion 131 on the transparent conductive layer 11 and the projection of the corresponding metal element portion 121 on the transparent conductive layer 11 at least partially overlap.

[0080] In the present invention, the area of ​​the metal element portion 121 can be selected according to actual needs. In some embodiments of the present invention, the area of ​​the first orthographic projection of the metal element portion 121 on the transparent conductive layer 11 accounts for 1%-3% of the area of ​​the second orthographic projection of the metal composite layer 12 on the transparent conductive layer 11.

[0081] In the present invention, the first orthographic projection refers to the projection formed on the surface of the transparent conductive layer 11 when the incident light irradiates the metal single substance portion 121 in a direction perpendicular to the transparent conductive layer 11; the second orthographic projection refers to the projection formed on the surface of the transparent conductive layer 11 when the incident light irradiates the metal composite layer 12 in a direction perpendicular to the transparent conductive layer 11.

[0082] When the area of ​​the first orthographic projection and the area of ​​the second orthographic projection meet the above limitations, the conductivity of the composite electrode 1 can be improved while ensuring the light transmittance of the composite electrode 1, thereby improving the photoelectric performance of the composite electrode 1.

[0083] In the metal element portion 121 of the present invention, at least some of the metal elements exist in the form of a metal element, and some of the metal elements exist in other forms, such as oxides. When the molar content of the metal element in the metal element portion 121 accounts for 50%-80% of the total molar content of the metal elements, the metal element portion 121 can ensure excellent adhesion to the electroplated metal layer 13, and the conductivity of the metal element portion 121 can be ensured, thereby improving the stability and photoelectric performance of the composite electrode 1. For example, in the elemental tin portion, the molar content of elemental tin accounts for 50%-80% of the total molar content of the tin element.

[0084] In some embodiments, XPS may be used to obtain the ratio of the molar content of the metal element to the total molar content of the metal elements in the metal element portion 121 .

[0085] In some embodiments, the metal element may be a nanometal. The inventors have also discovered that when the average particle size of the metal element in the metal element portion 121 is between 10 nm and 50 nm, the composite electrode 1 can have better conductivity and stronger adhesion between the layers of the composite electrode 1, thereby improving the photoelectric performance of the composite electrode 1.

[0086] Furthermore, within the metal element, particles with a particle size of 20 nm to 40 nm account for 50% to 80% of the total number of metal particles. This means that the majority of the metal particles have a particle size of 20 nm to 40 nm, indicating that the metal particles have an appropriate and uniform particle size. This can further improve the conductivity of the composite electrode 1 and the adhesion between the layers of the composite electrode 1, thereby enhancing the photoelectric performance of the composite electrode 1.

[0087] In some embodiments, TEM can be used to obtain the particle size of the metal element and the ratio of the number of metal element particles with a particle size of 20-40 nm to the total number of metal element particles.

[0088] In some embodiments of the present invention, the thickness of the transparent conductive layer 11 is 30 nm to 80 nm; and / or,

[0089] When the thickness of the metal composite layer 12 is 30nm-50nm, the thickness of the transparent conductive layer 11 can be reduced while ensuring the photoelectric performance of the composite electrode 1, thereby reducing the amount of rare metals used (for example, the amount of rare metals used can be reduced by more than 50%) and saving production costs.

[0090] The second aspect of the present invention provides a method for preparing the composite electrode of the first aspect, comprising:

[0091] A metal oxide layer is provided on one surface of the transparent conductive layer 11;

[0092] Performing a reduction treatment on a portion of the surface of the metal oxide layer away from the transparent conductive layer 11 to obtain a metal composite layer 12 including a metal single substance portion 121;

[0093] Electroplating is performed on at least a portion of the surface of the metal element portion 121 away from the transparent conductive layer 11 to obtain a composite electrode 1 including an electroplated metal layer 13 .

[0094] The preparation method of the composite electrode 1 may specifically include: providing a metal oxide layer on one surface of the transparent conductive layer 11; then performing a reduction treatment on a portion of the surface of the metal oxide layer away from the transparent conductive layer 11, so that a portion of the metal oxide layer is reduced to a metal element, thereby forming a metal element portion 121 including a metal element; then performing an electroplating treatment on at least a portion of the surface of the metal element portion 121 away from the transparent conductive layer 11, thereby forming an electroplated metal layer 13 (Cu grid lines with extremely narrow line width) on at least a portion of the surface of the metal element portion 121 away from the transparent conductive layer 11, thereby obtaining the composite electrode 1.

[0095] In existing methods for preparing metal electrodes, a seed layer is formed on the surface of the transparent conductive layer 11 using PVD. This results in high PVD equipment costs. Furthermore, the resulting seed layer suffers from poor interfacial adhesion to the TCO layer. During the process of removing the mask (or photoresist, ink) and the seed layer, the resulting electroplated metal layer 13 easily falls off, reducing the yield of the metal electrode. Furthermore, the TCO layer is susceptible to corrosion from the photoresist and / or chemical solutions (acidic and / or alkaline solutions), affecting the photoelectric conversion efficiency of the metal electrode. Compared to existing methods, the method for preparing the composite electrode 1 of the present invention does not require PVD to form a seed layer, reducing equipment and material costs. In some embodiments, the metal element portion 121 is obtained by reducing the metal oxide, and the metal element portion 121 is chemically bonded to the transparent conductive layer 11, thereby improving the adhesion between the metal element portion 121 and the transparent conductive layer 11 (for example, in the existing metal electrode, the adhesion between the seed layer and the transparent conductive layer 11 is 5-8 MPa, and the adhesion between the metal element portion 121 and the transparent conductive layer 11 of the present invention can reach 20 MPa), thereby ensuring the stability of the composite electrode 1; at the same time, the preparation method of the present invention does not require photolithography or masking steps, which can avoid damage to the transparent conductive layer 11 caused by photolithography and masking, thereby improving the yield and photoelectric performance of the composite electrode 1.

[0096] It is worth mentioning that in the preparation method of the present invention, electroplating treatment is performed on at least a portion of the surface of the metal element portion 121 away from the transparent conductive layer 11 to form an electroplated metal layer 13. The formed electroplated metal layer 13 can be a Cu grid line with an extremely narrow line width, which not only increases the conductivity of the composite electrode 1, but also has a low Cu cost, which can reduce costs and increase efficiency.

[0097] The present invention does not impose any particular limitation on the reduction treatment, as long as the metal oxide can be reduced to a metal element. In some embodiments, the reduction treatment may be at least one of a laser-assisted thermal reduction treatment and a chemical reduction treatment. The chemical reduction treatment may include treating tin oxide with H2 and / or an acidic solution. For example, a photosensitive material and a mask may be provided on the surface of the metal oxide layer away from the transparent conductive layer 11, and a portion of the photosensitive material on the surface of the metal oxide layer exposed by the mask is irradiated with UV light. The photosensitive material in the irradiated area is removed with a weak alkaline solution, and then the metal oxide in the area is reduced using laser-assisted thermal treatment combined with an H2 atmosphere to form a metal element portion 121; then, electroplating is performed on the surface of the metal element portion 121 away from the transparent conductive layer 11 to form an electroplated metal layer 13; and the remaining photosensitive material in other areas is removed. The photosensitive material is mainly a UV-sensitive material, which will denature after UV irradiation, resulting in a difference in corrosion resistance to alkaline solutions from the non-irradiated area.

[0098] In some embodiments, before the reduction treatment, a protective layer may be provided on the surface of the metal oxide layer away from the transparent conductive layer 11. Hydrofluoric acid is then used to partially remove the protective layer to expose the metal oxide layer. The exposed metal oxide layer is then subjected to a reduction treatment to form a metal single-element portion 121 including a metal single element, thereby obtaining a metal composite layer 12 including the metal single-element portion 121. The protective layer may include silicon oxide and / or silicon nitride.

[0099] Figure 2 This is a schematic structural diagram of a solar cell in a first embodiment of the present invention; Figure 3 This is a schematic structural diagram of a solar cell in a second embodiment of the present invention; Figure 4 FIG. 1 is a schematic diagram of the structure of a solar cell in the third embodiment of the present invention. Figure 2-4 As shown, the third aspect of the present invention provides a solar cell, comprising the composite electrode of the first aspect; or, comprising a composite electrode prepared by the method for preparing the composite electrode of the second aspect.

[0100] Since the solar cell of the present invention comprises the composite electrode of the first aspect or the composite electrode prepared by the preparation method of the composite electrode of the second aspect, the solar cell has excellent photoelectric performance and is suitable for wide promotion and application.

[0101] like Figure 2-4 As shown, in some embodiments of the present invention, the solar cell includes a silicon substrate 15 and a selective passivation layer 16;

[0102] The selective passivation layer 16 is located on two surfaces of the silicon substrate 15 , and the composite electrode is located on the surface of the selective passivation layer 16 away from the silicon substrate 15 .

[0103] That is, the solar cell of the present invention includes the composite electrode 1, the selective passivation layer 16, the silicon substrate 15, the selective passivation layer 16 and the composite electrode 1 in sequence in the stacking direction.

[0104] The selective passivation layer 16 of the present invention may be a selective passivation layer 16 commonly used in the art. For example, the selective passivation layer 16 may include an electron-selective passivation layer and a hole-selective passivation layer. The electron-selective passivation layer may include a stacked N-type doped layer 162 and a passivation contact layer 161. The N-type doped layer 162 may include an N-type amorphous silicon doped layer, an N-type microcrystalline silicon doped layer, or an N-type polycrystalline silicon doped layer. The hole-selective passivation layer may include a stacked P-type doped layer 163 and a passivation contact layer 161. The P-type doped layer 163 may include a P-type amorphous silicon doped layer, a P-type microcrystalline silicon doped layer, or a P-type polycrystalline silicon doped layer. The passivation contact layer 161 may include an intrinsic amorphous silicon layer or a tunneling oxide layer. The tunneling oxide layer may include SiO2.

[0105] In some embodiments, the electron selective passivation layer and the hole selective passivation layer may be located on two surfaces of the silicon substrate 15, respectively, and the passivation contact layer 161 is disposed close to the silicon substrate 15. Figure 4 As shown, the solar cell includes, in the stacking direction, a composite electrode 1, an N-type doped layer 162, a passivation contact layer 161, a silicon substrate 15, a passivation contact layer 161, a P-type doped layer 163 and a composite electrode 1.

[0106] In some embodiments of the present invention, the solar cell further includes an anti-reflection layer 14 . The anti-reflection layer 14 is located on at least a portion of the surface of the metal oxide portion 122 away from the transparent conductive layer 11 .

[0107] The metal element portion 121 extends out of the anti-reflection layer 14 , that is, is not covered by the anti-reflection layer 14 . Every two adjacent metal portions 131 are separated by the anti-reflection layer 14 .

[0108] In the present invention, the anti-reflection layer 14 can reduce light reflection and improve photoelectric efficiency, and can also protect the metal oxide portion 122 to prevent damage to the metal oxide portion 122, thereby ensuring the photoelectric performance of the solar cell.

[0109] The anti-reflection layer 14 of the present invention may be a commonly used anti-reflection layer 14 in the art. In some embodiments of the present invention, the anti-reflection layer 14 may include at least one of silicon oxide, silicon nitride, magnesium fluoride, and lithium fluoride.

[0110] Furthermore, the thickness of the anti-reflection layer 14 is 60 nm-200 nm.

[0111] Figure 5 The following is a flow chart of the preparation of solar cells in some embodiments of the present invention. Figure 5 As shown, the fourth aspect of the present invention provides a method for preparing the solar cell of the third aspect, comprising:

[0112] Performing texturing treatment on the silicon wafer to obtain a texturing silicon wafer;

[0113] A selective passivation layer 16 is provided on both surfaces of the textured silicon wafer;

[0114] The composite electrodes 1 of the first aspect are respectively arranged on the surface of the selective passivation layer 16 away from the textured silicon wafer.

[0115] Specifically, the silicon wafer is textured so that the two surfaces of the silicon wafer are textured respectively, thereby obtaining a textured silicon wafer; then, a selective passivation layer 16 is respectively provided on the two surfaces of the textured silicon wafer; then, a transparent conductive layer 11 is respectively provided on the surfaces of the two selective passivation layers 16 away from the textured silicon wafer, and a metal oxide layer is respectively provided on the surfaces of the two transparent conductive layers 11 away from the textured silicon wafer; a reduction treatment is performed on a portion of the surface of the metal oxide layer away from the transparent conductive layer 11 to obtain a metal composite layer 12 including a metal element portion 121; and an electroplating treatment is performed on the metal element portion 121 to form an electroplated metal layer 13, thereby obtaining a solar cell.

[0116] The method for preparing a solar cell of the present invention can prepare the solar cell of the third aspect. The method is simple to operate, low in cost, and suitable for wide promotion and application.

[0117] In some embodiments, potassium hydroxide can be used for texturing. Alternatively, one surface of the textured silicon wafer can be polished to make one surface of the textured silicon wafer a polished surface (one surface of the textured silicon wafer is a textured surface and the other surface is a polished surface), and then a selective passivation layer 16 is provided on both surfaces of the textured silicon wafer.

[0118] In some embodiments, PECVD may be used to form the selective passivation layer 16. An electron selective passivation layer may be formed on one surface of the textured silicon wafer, and a hole selective passivation layer may be formed on the other surface of the textured silicon wafer.

[0119] The fifth aspect of the present invention provides a photovoltaic module, including the solar cell of the third aspect or the solar cell prepared by the preparation method of the solar cell of the fourth aspect. The photovoltaic module has excellent photoelectric performance and is suitable for wide promotion and application.

[0120] The solution of the present invention will be further described below with reference to specific embodiments.

[0121] Example 1

[0122] The solar cell of this embodiment includes, in the stacking direction, an electroplated metal layer 13, a tin composite layer, a transparent conductive layer 11 (indium oxide layer), an N-type microcrystalline silicon doped layer, an intrinsic amorphous silicon layer, a silicon substrate 15, an intrinsic amorphous silicon layer, a P-type microcrystalline silicon doped layer, a tin composite layer, a transparent conductive layer 11 (indium oxide layer), and an electroplated metal layer 13.

[0123] In the longitudinal direction of the solar cell, the tin composite layer includes a tin oxide portion and a single tin portion that are connected to each other, and the electroplated metal layer 13 is connected to a portion of the surface of the single tin portion away from the transparent conductive layer 11;

[0124] The thickness of the transparent conductive layer 11 is 55 nm, the thickness of the tin composite layer is 40 nm, and the total thickness of the transparent conductive layer 11 and the tin composite layer is 95 nm. Specific parameters of the solar cell are shown in Table 1.

[0125] The solar cell of this embodiment is prepared by a method comprising the following steps:

[0126] 1) A double-sided texturing treatment was performed on a raw silicon wafer using a 1.5 wt% KOH aqueous solution, so that both surfaces of the raw silicon wafer had a textured surface. Subsequently, a protective layer was deposited on one surface, and then the wafer was placed in a 1.5 wt% KOH aqueous solution to remove the textured structure of the other surface, leaving the other surface smooth. The protective layer was then removed to obtain a textured silicon wafer with a textured surface of 2 μm on one surface and a smooth surface on the other surface, and a tower base of 6 μm on the polished surface.

[0127] 2) forming an intrinsic amorphous silicon layer with a thickness of 3 nm on both surfaces of the texturing silicon wafer by PECVD, then forming an N-type microcrystalline silicon doped layer with a thickness of 15 nm on a surface of one intrinsic amorphous silicon layer away from the silicon substrate 15, using PH3 as the doping gas, and a volume flow ratio of PH3, SiH4, and H2 of 3:100:1000, and a reaction time of 100 s, and forming a P-type microcrystalline silicon doped layer with a thickness of 18 nm on a surface of the other intrinsic amorphous silicon layer away from the silicon substrate 15, using B2H6 as the doping gas, and a volume flow ratio of B2H6, SiH4, and H2 of 5:100:1000, and a reaction time of 150 s;

[0128] 3) Using PVD method, an indium oxide layer (ITO) and a tin oxide layer are formed on the surface of the N-type microcrystalline silicon doped layer away from the textured silicon wafer, and an indium oxide layer (ITO) and a tin oxide layer are formed on the surface of the P-type microcrystalline silicon doped layer away from the textured silicon wafer; a photosensitive material (photosensitive ink) mask is set on the surface of the tin oxide layer away from the transparent conductive layer 11, and a portion of the photosensitive material on the surface of the tin oxide layer exposed by the mask is irradiated with UV, and a weak alkaline solution (1wt% Na2CO3 aqueous solution) is used to remove the light in the irradiated area. Sensitive material (the irradiated area accounts for 1.85% of the entire mask area), and then laser assisted heating combined with H2 atmosphere is used to electrochemically reduce the SnO in this area to make this part of the area into a single tin part (SnO2 as the cathode, Pt electrode as the anode, electrolyte is 20wt% KHCO3, and the time is 60s); then electroplating is performed on the surface of the single tin part away from the transparent conductive layer 11 to form an electroplated metal layer 13; and then the remaining photosensitive material in other areas is removed to form a tin composite layer including a tin oxide part and a single tin part.

[0129] Example 2

[0130] The solar cell of this embodiment has a substantially identical structure to that of the solar cell of embodiment 1, except that a tunnel oxide layer is used to replace the intrinsic amorphous silicon layer.

[0131] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 1, except that:

[0132] In step 2), tunnel oxide layers are formed on both surfaces of the textured silicon wafer using LPCVD;

[0133] The temperature is 575° C., the process gases are nitrogen and oxygen, the volume percentage of oxygen in the process gas is 15%, the process time is 800 s, and the pressure is 400 Pa.

[0134] Example 3

[0135] The solar cell of this embodiment has a substantially similar structure to that of the solar cell of embodiment 1, except that it further includes an anti-reflection layer 14, which is a silicon oxide-silicon nitride composite layer.

[0136] The anti-reflection layer 14 is located on the surface of the tin oxide portion away from the transparent conductive layer 11;

[0137] The thickness of the transparent conductive layer 11 is 55 nm, the thickness of the tin composite layer is 40 nm, the total thickness of the transparent conductive layer 11 and the tin composite layer is 95 nm, the thickness of the anti-reflection layer 14 is 95 nm, and the mass ratio of silicon nitride to silicon oxide in the anti-reflection layer is 3:7.

[0138] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 1, except that:

[0139] In step 3), an anti-reflection layer 14 is provided on the surface of the tin oxide layer away from the transparent conductive layer 11 by PECVD. The process gases are nitrous oxide and silane (SiH4), the volume ratio of nitrous oxide to silane is 6:1, the time is 85s, and the RF power is 1400W.

[0140] Example 4

[0141] The solar cell of this embodiment has substantially the same structure as that of the solar cell of embodiment 3, with the differences shown in Table 1.

[0142] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 3, except that;

[0143] In step 4), the proportion of the irradiated area to the entire mask area is 3.2%.

[0144] Example 5

[0145] The structure of the solar cell of this embodiment is basically the same as that of the solar cell of embodiment 3, and the differences are shown in Table 1.

[0146] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 3, except that:

[0147] In step 4), during the electrochemical reduction treatment, the electrolyte is 5 wt% KHCO3.

[0148] Example 6

[0149] The structure of the solar cell of this embodiment is basically the same as that of the solar cell of embodiment 3, and the differences are shown in Table 1.

[0150] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 3, except that:

[0151] In step 4), the proportion of the irradiated area to the entire mask area is 1.98%;

[0152] In the electrochemical reduction treatment, the electrolyte was 30 wt% KHCO3 and the time was 80 s.

[0153] Example 7

[0154] The structure of the solar cell of this embodiment is basically the same as that of the solar cell of embodiment 3, and the differences are shown in Table 1.

[0155] The method for preparing the solar cell of this embodiment is basically the same as that of embodiment 3, except that:

[0156] In step 4), the proportion of the irradiated area to the entire mask area is 1.75%;

[0157] In the electrochemical reduction treatment, the electrolyte was 15 wt% KHCO 3 and the time was 50 s.

[0158] Comparative Example

[0159] The solar cell of this comparative example includes, in the stacking direction, a printed metal layer, a transparent conductive layer, an intrinsic amorphous silicon layer, an N-type microcrystalline silicon doped layer, a silicon substrate, a P-type microcrystalline silicon doped layer, an intrinsic amorphous silicon layer, a transparent conductive layer and a printed metal layer.

[0160] The solar cell of this comparative example is prepared by a method comprising the following steps:

[0161] 1) Using a 1.5 wt% KOH aqueous solution to perform a double-sided texturing treatment on the original silicon wafer, so that both surfaces of the original silicon wafer are textured;

[0162] 2) forming an intrinsic amorphous silicon layer with a thickness of 3 nm on both surfaces of the texturing silicon wafer by PECVD, then forming an N-type microcrystalline silicon doped layer with a thickness of 15 nm on a surface of one intrinsic amorphous silicon layer away from the silicon substrate 15, using PH3 as the doping gas, and a volume flow ratio of PH3, SiH4, and H2 of 3:100:1000, and a reaction time of 100 s, and forming a P-type microcrystalline silicon doped layer with a thickness of 18 nm on a surface of the other intrinsic amorphous silicon layer away from the silicon substrate 15, using B2H6 as the doping gas, and a volume flow ratio of B2H6, SiH4, and H2 of 5:100:1000, and a reaction time of 150 s;

[0163] 3) forming an indium oxide layer (ITO) on the surface of the N-type microcrystalline silicon doped layer away from the textured silicon wafer by PVD, and forming an indium oxide layer (ITO) on the surface of the P-type microcrystalline silicon doped layer away from the textured silicon wafer by PVD, wherein the thickness of the ITO layer is 80 nm;

[0164] 4) A metal electrode is formed on the side of the ITO layer away from the silicon wafer by screen printing, and the metal electrode is a silver-copper paste.

[0165] Performance Testing

[0166] The photovoltaic conversion efficiency (Eff), short-circuit current (Isc), open-circuit voltage (Voc), and fill factor (FF) of the solar cells in the examples and comparative examples were tested in accordance with IEC 60904-1 Photovoltaic Devices - Part 1 Photovoltaic Current-Voltage Characteristics Test Method. The results are shown in Table 2.

[0167] Table 1

[0168] A N Average particle size of elemental tin / nm B Transparent conductive layer thickness / nm Thickness of metal composite layer / nm Example 1 1.85％ 75％ 40 70％ 55 40 Example 2 1.85％ 75％ 40 70％ 55 40 Example 3 1.85％ 75％ 40 70％ 55 40 Example 4 3.2％ 75％ 40 70％ 55 40 Example 5 1.85％ 40％ 10 40％ 55 40 Example 6 1.98％ 80％ 60 90％ 55 45 Example 7 1.75％ 50％ 30 45％ 60 40 Comparative Example 1 2％ / / / 80 /

[0169] A is the ratio of the area of ​​the first orthographic projection to the area of ​​the second orthographic projection; N is the ratio of the molar content of elemental tin to the total molar content of tin element; B is the ratio of the number of elemental tin particles with a particle size of 20nm-40nm in elemental tin to the total number of elemental tin particles.

[0170] Table 2

[0171] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Isc / % 39.9 40.1 40.2 39.64 40.2 40.1 40.2 39.81 Voc / % 752 749 752.5 752.1 752.1 752 752 752 FF / % 85.8 85.8 85.8 86.1 85.6 85.7 85.5 85.5 Eff / % 25.74 25.76 25.95 25.66 25.88 25.84 25.84 25.6

[0172] As shown in Table 2, the solar cells of the embodiment have better photoelectric performance than those of the comparative example.

[0173] Furthermore, it can be seen from Examples 1 and 3 that when the solar cell further includes an anti-reflection layer, the open circuit voltage, short circuit current, and photoelectric conversion efficiency of the solar cell can be improved while the fill factor remains unchanged.

[0174] It can be seen from Example 4 and Example 3 that by selecting the area of ​​the metal element portion in the composite electrode, the open circuit voltage, short circuit current, photoelectric conversion efficiency and fill factor of the solar cell can be improved;

[0175] It can be seen from Example 5 and Example 3 that by selecting the molar content of the metal element in the metal element portion of the composite electrode, the open circuit voltage, fill factor and photoelectric conversion efficiency of the solar cell can be improved;

[0176] It can be seen from Example 6 and Example 3 that by selecting the average particle size of the metal element in the metal element portion of the composite electrode, the open circuit voltage, short circuit current, photoelectric conversion efficiency and fill factor of the solar cell can be improved;

[0177] It can be seen from Example 7 and Example 3 that the open circuit voltage, fill factor and photoelectric conversion efficiency of the solar cell can be improved by selecting the particle size distribution of the metal element in the metal element portion of the composite electrode.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite electrode, characterized in that: It includes a transparent conductive layer, a metal composite layer and an electroplated metal layer stacked in sequence; The metal composite layer includes a metal single substance portion, and the electroplated metal layer is located on at least a portion of the surface of the metal single substance portion away from the transparent conductive layer; The metal elements in the metal composite layer and the metal single substance portion include at least one of tin, aluminum, and zinc.

2. The composite electrode according to claim 1, characterized in that The metal single substance portion and the transparent conductive layer are connected via a chemical bond.

3. The composite electrode according to claim 1 or 2, characterized in that The metal composite layer further includes a metal oxide portion interconnected with the metal single substance portion, and the metal oxide portion is located on the surface of the transparent conductive layer; The metal element of the metal oxide portion includes at least one of tin, aluminum, and zinc.

4. The composite electrode according to any one of claims 1 to 3, characterized in that: The metal composite layer includes a plurality of the metal single-substance parts, and the electroplated metal layer includes a plurality of metal parts, and the metal single-substance parts correspond to the metal parts one by one.

5. The composite electrode according to any one of claims 1 to 4, characterized in that: The area of ​​the first orthographic projection of the metal single substance portion on the transparent conductive layer accounts for 1%-3% of the area of ​​the second orthographic projection of the metal composite layer on the transparent conductive layer; and / or, In the metal element portion, the molar content of the metal element accounts for 50% to 80% of the total molar content of the metal elements.

6. The composite electrode according to any one of claims 1 to 5, characterized in that: The metal single substance portion has an average particle size of 10 nm to 50 nm.

7. The composite electrode according to claim 6, characterized in that In the metal element, the number of metal element particles with a particle size of 20 nm to 40 nm accounts for 50% to 80% of the total number of metal element particles.

8. The composite electrode according to any one of claims 1 to 7, characterized in that: The thickness of the transparent conductive layer is 30nm-80nm; and / or, The thickness of the metal composite layer is 30nm-50nm.

9. A method for preparing the composite electrode according to any one of claims 1 to 8, characterized in that: include: Disposing a metal oxide layer on one surface of the transparent conductive layer; performing a reduction treatment on a portion of the surface of the metal oxide layer away from the transparent conductive layer to obtain a metal composite layer including a metal single substance portion; The electroplated metal layer is formed on at least a portion of the surface of the metal element portion away from the transparent conductive layer to obtain the composite electrode.

10. A solar cell, characterized in that: A composite electrode comprising the composite electrode according to any one of claims 1 to 8; or a composite electrode prepared by the method for preparing the composite electrode according to claim 9.

11. The solar cell according to claim 10, characterized in that The solar cell further comprises a silicon substrate and a selective passivation layer; The selective passivation layer is respectively located on two surfaces of the silicon substrate, and the composite electrode is located on a surface of the selective passivation layer away from the silicon substrate.

12. The solar cell according to claim 11, characterized in that The invention also includes an anti-reflection layer, which is located on at least a portion of the surface of the metal oxide portion away from the transparent conductive layer.

13. The solar cell according to claim 12, wherein: The anti-reflection layer includes at least one of silicon oxide, silicon nitride, magnesium fluoride and lithium fluoride; and / or, The thickness of the anti-reflection layer is 60-200 nm.

14. A method for preparing a solar cell according to any one of claims 10 to 13, characterized in that: include: Performing texturing treatment on the silicon wafer to obtain a texturing silicon wafer; Disposing selective passivation layers on both surfaces of the texturing silicon wafer; The composite electrode according to any one of claims 1 to 9 is respectively arranged on the surface of the selective passivation layer away from the textured silicon wafer.

15. A photovoltaic module, characterized in that: A solar cell comprising the solar cell according to any one of claims 10 to 13; or a solar cell prepared from the solar cell according to claim 14.

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