Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the field of photovoltaic technology, and provides a solar cell, a preparation method thereof and a photovoltaic module. The solar cell includes a substrate and an electrode. The electrode comprises an alloy seed layer and a diffusion layer, the alloy seed layer is arranged on the substrate, the diffusion layer is arranged between the alloy seed layer and the substrate, and the material of the diffusion layer comprises a compound composed of elements in the substrate and elements in the alloy seed layer. The alloy seed layer is combined with the substrate through the diffusion layer, and the characteristics of high adhesive force, good contact effect and the like are achieved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell, a method for its fabrication, and a photovoltaic module. Background Technology

[0002] Solar cells use silver paste as an electrode material, but silver is expensive and scarce. Traditional technologies incorporate copper interconnect (THL) processes to reduce silver usage and thus lower production costs. However, copper easily diffuses into the silicon substrate, forming recurring recombination centers and reducing the solar cell's conversion efficiency. Therefore, a seed layer is placed between the copper electrode and the substrate to prevent copper diffusion and protect the silicon wafer. However, in traditional technologies, the adhesion between the seed layer and the silicon substrate is poor, affecting the solar cell's photoelectric conversion efficiency. Summary of the Invention

[0003] Based on this, one embodiment of this application provides a solar cell with strong seed layer adhesion and low contact resistance, a method for preparing the same, and a photovoltaic module.

[0004] In a first aspect, this application provides a solar cell, the solar cell comprising:

[0005] Base;

[0006] An electrode comprising an alloy seed layer and a diffusion layer, the alloy seed layer being disposed on the substrate, the diffusion layer being disposed between the alloy seed layer and the substrate, the material of the diffusion layer comprising a compound composed of elements in the substrate and elements in the alloy seed layer.

[0007] In some embodiments, the diffusion layer is an integral structure with at least one of the alloy seed layer and / or the substrate.

[0008] In some embodiments, the alloy seed layer comprises a metal substrate and a dopant material, wherein the dopant material is different from the material of the metal substrate.

[0009] Optionally, the metal substrate includes at least one of nickel, aluminum, titanium, zinc, and magnesium.

[0010] Optionally, the doping material includes at least one selected from magnesium, nickel, manganese, chromium, zinc, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon.

[0011] Optionally, the mass content of the metal substrate in the material of the alloy seed layer is 60% to 95%.

[0012] In some embodiments, the diffusion layer includes a first diffusion layer and / or a second diffusion layer, wherein the first diffusion layer is fused to the alloy seed layer and the second diffusion layer is fused to the substrate.

[0013] Optionally, the thickness of the first diffusion layer is ≤300nm.

[0014] Optionally, the thickness of the second diffusion layer is ≤300nm.

[0015] In some embodiments, the width of the alloy seed layer is 50 μm to 500 μm.

[0016] In some embodiments, the thickness of the alloy seed layer is 1 μm to 100 μm.

[0017] In some embodiments, the electrode further includes a conductive layer disposed on the surface of the alloy seed layer.

[0018] Optionally, the thickness of the conductive layer is 2μm to 10μm.

[0019] Optionally, the conductive layer may be made of at least one of copper, aluminum, and nickel.

[0020] Optionally, the electrode further includes a protective layer disposed on the surface of the conductive layer away from the alloy seed layer.

[0021] Optionally, the thickness of the protective layer is 5μm to 50μm.

[0022] Optionally, the material of the protective layer includes at least one of tin, lead, and aluminum.

[0023] Secondly, this application provides a method for fabricating a solar cell, the method comprising:

[0024] A substrate is provided, and an alloy material layer is formed on the surface of the substrate;

[0025] The alloy material layer is laser-sintered, and at the laser-sintered location, at least a portion of the alloy material layer diffuses into the substrate and / or at least a portion of the substrate diffuses into the alloy material layer to form a diffusion layer, while another portion of the alloy material layer is shaped to form an alloy seed layer; and,

[0026] An electrode is formed on the surface of the substrate based on the alloy seed layer.

[0027] In some embodiments, the thickness of the alloy material layer is 1 μm to 100 μm.

[0028] In some embodiments, during the laser sintering process, the alloy material layer is heated to 500°C to 1400°C.

[0029] In some embodiments, the method of forming the alloy material layer includes:

[0030] After mixing the metal substrate and the dopant material, the alloy material layer is formed on the surface of the substrate.

[0031] Optionally, the metal substrate includes nickel, and the doping material includes at least one of chromium, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon. During the laser sintering process, the alloy material layer is heated to 992°C to 1400°C.

[0032] Optionally, the metal substrate includes aluminum, and the doping material includes at least one of magnesium, manganese, chromium, zinc, iron, nickel, titanium, silicon, boron, and carbon. During the laser sintering process, the alloy material layer is heated to 577°C to 660°C.

[0033] In some embodiments, the preparation method further includes forming a conductive layer on the surface of the alloy seed layer.

[0034] Optionally, the conductive layer may be formed using at least one of electroplating, electroless plating, and physical vapor deposition.

[0035] In some embodiments, the preparation method further includes forming a protective layer on the surface of the conductive layer.

[0036] Alternatively, the protective layer may be formed using at least one of electroplating, electroless plating, and physical vapor deposition.

[0037] Thirdly, this application provides a photovoltaic module, which includes solar cells as described in the first aspect and / or solar cells prepared by the method described in the second aspect.

[0038] Compared with traditional technologies, this application has at least the following beneficial effects:

[0039] The electrode in this application contains an alloy seed layer and a diffusion layer. The diffusion layer is formed by material diffusion between the alloy seed layer and the substrate, thereby effectively improving the bonding force between the alloy seed layer and the substrate. Furthermore, an ohmic contact can be formed between the electrode and the substrate, thereby improving the photoelectric conversion efficiency and performance stability of the solar cell. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this application;

[0041] Figure 2 for Figure 1 A magnified view of a portion of region A in the middle;

[0042] Figure 3This is a schematic flowchart of a method for fabricating a solar cell according to one embodiment of this application. Wherein, 100-substrate; 101-alloy material layer; 200-electrode; 210-alloy seed layer; 220-diffusion layer; 221-first diffusion layer; 222-second diffusion layer; 230-conductive layer; 240-protective layer.

[0043] Figure 4 This is a schematic diagram of the elemental distribution in the diffusion layer of the solar cell prepared in Embodiment 1 of this application.

[0044] Figure 5 This is a schematic flowchart illustrating a method for fabricating a solar cell provided in Comparative Examples 1 and 2 of this application. Wherein, 100a - substrate; 110a - seed layer; 120a - photosensitive ink layer; 130a - copper conductive layer; 140a - tin protective layer. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are only for illustrating the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. In addition, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0047] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0048] In this application, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first aspect," "second aspect," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0049] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0050] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0051] All references to this application are incorporated herein by reference as if each document were individually incorporated herein by reference. Unless they conflict with the purpose and / or technical solution of this application, all cited references are incorporated herein by reference in their entirety and for all purposes. When references are cited in this application, the definitions of relevant technical features, terms, nouns, phrases, etc., are also incorporated herein by reference. Examples and preferred embodiments of the cited technical features may also be incorporated herein by reference, but only to the extent that they enable the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or modifications shall be made adaptably to the description in this application.

[0052] In traditional solar cell electrode fabrication, a nickel seed layer is first formed on the substrate surface using PVD (physical vapor deposition), followed by electroplating to form a copper electrode layer and a tin protective layer. However, the seed layer and substrate are bonded by van der Waals forces, resulting in poor adhesion and affecting the contact between the electrode and substrate. Furthermore, the electrode fabrication method involves PVD seed layer deposition, spraying photosensitive ink, exposure and development to form the desired electrode design pattern, copper electroplating to create grid lines, removal of the photosensitive ink, and tin electroplating for electrode protection, making the process cumbersome.

[0053] The first aspect of this application provides a solar cell, such as... Figure 1 and Figure 2 As shown, the solar cell includes a substrate 100 and an electrode 200.

[0054] The electrode 200 includes an alloy seed layer 210 and a diffusion layer 220. The alloy seed layer 210 is disposed on the substrate 100, and the diffusion layer 220 is disposed between the alloy seed layer 210 and the substrate 100. The material of the diffusion layer 220 includes a compound composed of elements in the substrate 100 and elements in the alloy seed layer 210.

[0055] The electrode 200 of this application contains an alloy seed layer 210 and a diffusion layer 220. The diffusion layer 220 is formed by material diffusion between the alloy seed layer 210 and the substrate 100, thereby effectively improving the bonding force between the alloy seed layer 210 and the substrate 100. Furthermore, an ohmic contact can be formed between the electrode 200 and the substrate 100, thereby improving the photoelectric conversion efficiency and performance stability of the solar cell.

[0056] In some embodiments, the diffusion layer 220 is integrally formed with at least one of the alloy seed layer 210 and / or the substrate 100. It is understood that in this application, the diffusion layer 220 may be fused integrally with the alloy seed layer 210 or with the substrate 100, or it may be partially fused with both the alloy seed layer 210 and the substrate 100 simultaneously. Further, the diffusion layer 220 may be formed by interdiffusion between the materials of the alloy seed layer 210 and the substrate 100. Additionally, a eutectic reaction may occur between the materials of the alloy seed layer 210 and the substrate 100 in the diffusion layer 220. Taking a silicon substrate as an example, the diffusion layer 220 may contain metal silicides, and the metal elements in the metal silicides may be one or more metal elements from the alloy seed layer 210.

[0057] In some embodiments, the alloy seed layer 210 is made of a metal substrate and a dopant material, wherein the dopant material is different from the metal substrate material. It is understood that the dopant material in this application can be selected based on the material of the metal substrate; for example, the introduction of a dopant material can lower the melting point of the alloy seed layer 210, improve its mechanical properties, improve its corrosion resistance, or improve its oxidation resistance.

[0058] Optionally, the metal substrate includes at least one of nickel, aluminum, titanium, zinc, and magnesium.

[0059] Optionally, the doping material includes at least one of magnesium, nickel, manganese, chromium, zinc, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon.

[0060] In some embodiments, the metal substrate contained in the alloy seed layer 210 includes nickel, and the doping material includes at least one selected from chromium, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon. Optionally, the material of the alloy seed layer 210 is a nickel-based alloy, which, by mass percentage, includes: 5%~15% chromium, 1%~5% iron, 2%~5% silicon, 1%~5% boron, 0.5%~1% carbon, and the remainder being pure nickel. This application selects a nickel-based alloy as the material for the alloy seed layer 210, which has a lower melting point than pure nickel (992℃~1400℃). During the sintering process to form the alloy seed layer 210, it can interdiffuse with the silicon substrate and undergo a eutectic reaction, forming a good ohmic contact, and the adhesion between the alloy seed layer 210 and the substrate 100 is strong.

[0061] In some embodiments, the metal substrate contained in the alloy seed layer 210 includes aluminum, and the dopant material includes at least one selected from magnesium, manganese, chromium, zinc, iron, nickel, titanium, silicon, boron, and carbon. Optionally, the material of the alloy seed layer 210 is an aluminum-based alloy, which, by mass percentage, includes: 2%~6% magnesium, 0.1%~0.5% chromium, 0.05%~0.2% manganese, 0.1%~0.3% zinc, 0%~0.7% iron, 0%~0.5% silicon, 0%~0.2% titanium, and the remainder being pure aluminum. This application selects an aluminum-based alloy as the material for the alloy seed layer 210. The melting point of the aluminum-based alloy is 577℃~660℃. During the sintering process to form the alloy seed layer 210, it can interdiffuse with the silicon substrate and undergo a eutectic reaction, forming a good ohmic contact, and the adhesion between the alloy seed layer 210 and the substrate 100 is strong. Moreover, the introduction of elements such as chromium and molybdenum can improve the mechanical properties, corrosion resistance, and oxidation resistance of the alloy seed layer 210.

[0062] Optionally, the mass content of the metal substrate in the alloy seed layer 210 is 60% to 95%, for example, it can be 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%.

[0063] In some embodiments, such as Figure 2 As shown, the diffusion layer 220 includes a first diffusion layer 221 and / or a second diffusion layer 222. The first diffusion layer 221 is fused with the alloy seed layer 210, and the second diffusion layer 222 is fused with the substrate 100.

[0064] Optionally, the thickness of the first diffusion layer 221 is ≤300nm, for example, it can be 10nm, 30nm, 60nm, 90nm, 120nm, 150nm, 180nm, 210nm, 240nm, 270nm or 300nm.

[0065] Optionally, the thickness of the second diffusion layer 222 is ≤300nm, for example, it can be 10nm, 30nm, 60nm, 90nm, 120nm, 150nm, 180nm, 210nm, 240nm, 270nm or 300nm.

[0066] In some embodiments, the width of the alloy seed layer 210 is 50μm to 500μm, for example, it can be 50μm, 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm or 500μm.

[0067] In some embodiments, the thickness of the alloy seed layer 210 is 1μm to 100μm, for example, it can be 1μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm.

[0068] In some embodiments, such as Figure 2 As shown, electrode 200 also includes a conductive layer 230 disposed on the surface of alloy seed layer 210.

[0069] Optionally, the thickness of the conductive layer 230 is 2μm to 10μm, for example, it can be 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0070] Optionally, the conductive layer 230 may be made of at least one of copper, aluminum, and nickel.

[0071] In some embodiments, such as Figure 2 As shown, the electrode also includes a protective layer 240 disposed on the surface of the conductive layer 230 away from the alloy seed layer 210.

[0072] Optionally, the thickness of the protective layer 240 is 5μm to 50μm, for example, it can be 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm.

[0073] Optionally, the material of the protective layer 240 includes at least one of tin, lead, and aluminum.

[0074] In some embodiments, the substrate 100 may be an N-type silicon substrate or a P-type silicon substrate.

[0075] In some embodiments, the solar cell may be a TOPcon cell, a PERC cell, an HJT cell, or a BC cell.

[0076] In some embodiments, the solar cell is a BC cell, wherein the substrate 100 includes a light-facing surface and a back-lighting surface disposed opposite to each other along its thickness direction. The back-lighting surface of the substrate 100 is divided into a P-region and an N-region, and electrodes 200 are formed in the P-region and the N-region respectively. The electrodes 200 include a diffusion layer 220, an alloy seed layer 210, an electrode layer, and a protective layer 240 stacked sequentially. Optionally, a transparent anti-reflective layer may also be included on the front side of the substrate 100. A passivation layer is also included on the back side of the substrate 100.

[0077] The second aspect of this application provides a method for fabricating a solar cell, such as... Figure 3 As shown, the methods for fabricating solar cells include:

[0078] A substrate 100 is provided, and an alloy material layer 101 is formed on the surface of the substrate 100;

[0079] The alloy material layer 101 is laser-sintered, and at the laser-sintered location, at least a portion of the alloy material layer 101 diffuses into the substrate 100 and / or at least a portion of the material from the substrate 100 diffuses into the alloy material layer 101 to form a diffusion layer 220, while another portion of the alloy material layer 101 is shaped to form an alloy seed layer 210; and,

[0080] An electrode 200 is formed on the surface of the substrate 100 based on the alloy seed layer 210.

[0081] This application utilizes laser sintering to sinter an alloy material layer 101 disposed on a substrate 100 to form an alloy seed layer 210. During the laser sintering process, the alloy material layer 101 melts, and element diffusion occurs between the alloy material layer 101 and the substrate 100 to form a diffusion layer 220. After the alloy material layer 101 cools, the alloy seed layer 210 is formed. Due to the eutectic reaction of elements during diffusion, not only is the adhesion between the alloy seed layer 210 and the substrate 100 improved, but the conductivity is also good, reducing the contact resistance of the electrode 200. Furthermore, compared with the PVD deposition method for forming the seed layer, the laser sintering method of this application is simpler, requires no additional mask structure, has higher preparation efficiency, and the microstructure of the alloy seed layer 210 formed by laser sintering is denser, providing better protection against copper diffusion and further improving the adhesion between the electrode 200 and the substrate 100.

[0082] It is understandable that the alloy material layer can be an amorphous layered structure composed of alloy powder.

[0083] It is understandable that laser sintering can sinter a portion of the alloy material layer 101. Compared with ordinary high-temperature sintering, it does not require the substrate 100 to be completely placed in the sintering furnace for sintering, and it can reduce the damage to the substrate 100 caused by high-temperature sintering.

[0084] In some embodiments, laser sintering is performed according to the pattern of the grid lines of electrode 200 to form a patterned alloy seed layer 210. It is understood that laser sintering can be performed by moving a laser beam along a preset patterned trajectory. Further, after laser sintering is completed, the alloy material layer 101 in the un-laser-sintered areas is removed. The next process can then proceed.

[0085] In some embodiments, the thickness of the alloy material layer 101 is 1μm to 100μm, for example, it can be 1μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm.

[0086] In some embodiments, during laser sintering, the alloy material layer 101 is heated to 500°C to 1400°C, for example, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, or 1400°C. It is understood that this application uses laser sintering to melt the alloy material layer 101 during the laser sintering process and rapidly cool it to form an alloy seed layer 210. Therefore, the laser sintering temperature can be selected based on the composition of the selected alloy material.

[0087] In some embodiments, the method of forming the alloy material layer 101 includes:

[0088] After mixing the metal substrate and the dopant material, an alloy material layer 101 is formed on the surface of the substrate 100. Optionally, the alloy material layer 101 is formed on the surface of the substrate 100 by screen printing the mixed powder of the metal substrate and the dopant material.

[0089] In some embodiments, the metal substrate comprises nickel, and the dopant material comprises at least one selected from chromium, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon. Optionally, the alloy material is a nickel-based alloy, comprising, by mass percentage: 5%–15% chromium, 1%–5% iron, 2%–5% silicon, 1%–5% boron, 0.5%–1% carbon, with the remainder being pure nickel. During laser sintering, the alloy material layer 101 is heated to 992°C–1400°C.

[0090] The laser sintering temperature selected in this application allows for good diffusion of nickel and silicon substrate during laser sintering, resulting in a eutectic reaction and the formation of a Ni-Si alloy diffusion layer 220. This not only improves the adhesion between the alloy seed layer 210 and the substrate 100 but also reduces the contact resistance of the electrode 200. However, if only nickel is used as the seed layer material, its melting point reaches 1455℃, which is higher than the melting point of the silicon substrate (1414℃). If the seed layer is formed by laser sintering, it can easily damage the silicon substrate.

[0091] Optionally, the metal substrate includes aluminum, and the doped material includes at least one selected from magnesium, manganese, chromium, zinc, iron, nickel, titanium, silicon, boron, and carbon. Optionally, the alloy material layer 101 is made of an aluminum-based alloy, comprising, by mass percentage: 2%~6% magnesium, 0.1%~0.5% chromium, 0.05%~0.2% manganese, 0.1%~0.3% zinc, 0%~0.7% iron, 0%~0.5% silicon, 0%~0.2% titanium, and the remainder being pure aluminum. During laser sintering, the alloy material layer 101 is heated to 577℃~660℃.

[0092] The aluminum-based alloy and laser sintering temperature selected in this application can achieve good diffusion effect and form Al-Si alloy during laser sintering, so that there is good ohmic contact between the alloy seed layer 210 and the substrate 100, and the adhesion between the alloy seed layer 210 and the substrate 100 is strong.

[0093] Understandably, after the alloy seed layer 210 is formed by laser sintering, the portion of the alloy material layer 101 that has not undergone laser sintering can be removed to allow for subsequent processing of the substrate 100. For example, the alloy material layer 101 can be removed by rinsing to retain the alloy seed layer 210.

[0094] In some embodiments, the preparation method further includes forming a conductive layer 230 on the surface of the alloy seed layer 210.

[0095] Optionally, the conductive layer 230 is formed by at least one of electroplating, electroless plating and physical vapor deposition.

[0096] Alternatively, a conductive layer 230 may be formed on the surface of the alloy seed layer 210 by electroplating, including the following steps:

[0097] The substrate 100 with the alloy seed layer 210 is placed in an electroplating tank. The positive electrode is connected to the first electroplating solution, and the negative electrode is connected to the alloy seed layer 210 on the substrate 100. A conductive layer 230 is formed by electroplating on the surface of the alloy seed layer 210. After electroplating is completed, the substrate is removed and cleaned.

[0098] The first electroplating solution can be at least one of copper chloride and copper sulfate. The electroplating current density can be 1 mA / cm² to 10 mA / cm², the temperature can be 20℃ to 30℃, the pH can be 0.5 to 2.0, and the time can be 10 min to 30 min. The thickness of the conductive layer 230 can be 2 μm to 10 μm.

[0099] In some embodiments, the preparation method further includes forming a protective layer 240 on the surface of the conductive layer 230.

[0100] Optionally, the protective layer 240 is formed by at least one of electroplating, electroless plating and physical vapor deposition.

[0101] Alternatively, a conductive layer 230 may be formed on the surface of the alloy seed layer 210 by electroplating, including the following steps:

[0102] A substrate 100 having an alloy seed layer 210 and a conductive layer 230 is placed in an electroplating tank. The positive electrode is connected to the second electroplating solution, and the negative electrode is connected to the conductive layer 230 on the substrate 100. A protective layer 240 is formed by electroplating on the surface of the conductive layer 230. After electroplating is completed, the substrate is removed and cleaned.

[0103] The second electroplating solution can be at least one of tin chloride and tin sulfate. The electroplating current density can be 1 mA / cm² to 10 mA / cm², the temperature can be 20℃ to 30℃, the pH can be 2 to 5, and the time can be 10 min to 30 min. The thickness of the conductive layer 230 can be 5 μm to 50 μm.

[0104] Exemplarily, a method for fabricating the above-mentioned solar cell is provided, and for example... Figure 3 As shown, it includes the following steps:

[0105] A substrate 100 is provided, and alloy powder is screen-printed onto the surface of the substrate 100 to form an alloy material layer 101.

[0106] The alloy material layer 101 is laser sintered. At the laser sintering location, the alloy material layer 101 melts and cools to form an alloy seed layer 210. During the laser sintering process, the material of the substrate 100 and the material of the alloy material layer 101 diffuse to form a diffusion layer 220 between the alloy seed layer 210 and the substrate 100. The portion of the alloy material layer 101 that has not been laser sintered is washed away, and a patterned alloy seed layer 210 is obtained on the substrate 100.

[0107] A substrate 100 having an alloy seed layer 210 is placed in a first electroplating tank, and a conductive layer 230 is formed by electroplating on the surface of the alloy seed layer 210.

[0108] A substrate 100 having an alloy seed layer 210 and a conductive layer 230 is placed in a second electroplating tank, and a protective layer 240 is formed by electroplating on the surface of the conductive layer 230.

[0109] A third aspect of this application provides a photovoltaic module, which includes a solar cell as described in the first aspect and / or a solar cell prepared by the method described in the second aspect.

[0110] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0111] In the following embodiments, the substrate 100 is a battery cell with electrodes to be processed. Specifically, the battery cell is a 182-type PBC.

[0112] Example 1

[0113] like Figure 3 As shown, a substrate 100 is provided, and an alloy material layer 101 with a thickness of 30 μm is formed on the surface of the substrate 100 by applying alloy powder. The alloy powder is a Ni-based alloy, comprising: 10% chromium, 3% iron, 3% silicon, 3% boron, 0.5% carbon, and the remainder being pure nickel, by mass percentage.

[0114] The alloy material layer 101 on the substrate 100 is laser-sintered according to the pattern of the electrode 200 at a temperature of 1050℃~1100℃. After cooling, the laser-sintered portion of the alloy material layer 101 forms an alloy seed layer 210 with a thickness of 200nm. The material of the alloy seed layer 210 is a Ni-based alloy. During the laser sintering process, the material of the alloy seed layer 210 and the material of the substrate 100 diffuse into each other to form a diffusion layer 220. The elements in the diffusion layer are dispersed as follows: Figure 4 As shown;

[0115] The substrate 100 after laser sintering is rinsed to remove the alloy material layer 101 of the un-laser sintered portion, and a patterned alloy seed layer 210 is formed on the substrate 100. The width of the alloy seed layer 210 is 100 μm.

[0116] The substrate 100 with the alloy seed layer 210 is placed into a first electroplating tank filled with copper sulfate solution. The positive electrode of the first electroplating tank is connected to the copper sulfate solution, and the negative electrode is connected to the alloy seed layer 210. The electroplating current density is 5 mA / cm², the temperature is 25°C, the pH is 1, and the electroplating time is 20 min. A copper conductive layer 230 with a thickness of 6 μm is formed on the alloy seed layer 210.

[0117] The substrate 100, which has a copper conductive layer 230 and an alloy seed layer 210, is placed into a second electroplating tank filled with a tin sulfate solution. The positive electrode of the second electroplating tank is connected to the tin sulfate solution, and the negative electrode is connected to the conductive layer 230. The electroplating current density is 5 mA / cm², the temperature is 25°C, the pH is 3.5, and the electroplating time is 20 min. A tin protective layer 240 with a thickness of 20 μm is formed on the copper conductive layer 230.

[0118] Example 2

[0119] The solar cell was prepared according to the method of Example 1, except that the alloy material layer 101 was made of an aluminum-based alloy, which, by mass percentage, comprised: 4% magnesium, 0.3% chromium, 0.1% manganese, 0.2% zinc, 0.3% iron, 0.3% silicon, 0.1% titanium, and the remainder being pure aluminum. Furthermore, the laser sintering temperature was 590°C to 640°C.

[0120] Comparative Example 1

[0121] The solar cell was prepared according to the method of Example 1, except that a seed layer of nickel material was formed by PVD deposition. The seed layer was prepared by the following method:

[0122] like Figure 5 As shown, a seed layer 110a is formed on the surface of the substrate 100a by PVD deposition.

[0123] A photosensitive ink layer 120a is sprayed onto the seed layer 110a, and an electrode pattern is formed by exposing the seed layer 110a on the photosensitive ink layer 120a through exposure and development.

[0124] After electroplating a conductive layer 130a on the seed layer 110a, the photosensitive ink layer 120a and the seed layer 110a not covered by the conductive layer 130a are removed by cleaning with a developer and solvent.

[0125] A protective layer 140a is formed by electroplating on the conductive layer 130a.

[0126] Comparative Example 2

[0127] Solar cells were prepared according to the method of Comparative Example 1, except that the material of the seed layer 110a was replaced with aluminum.

[0128] The solar cells prepared in the above embodiments and comparative examples were subjected to performance testing. The testing methods included:

[0129] The electrical performance of the solar cells was tested online using a Halm machine, and the welding tensile strength was tested using a horizontal tensile tester. The tensile tester applied a tensile force to the welding strip at a speed of 300 mm / min until the welding strip was peeled off from the solar cell. The peak tensile force at this point was recorded as the welding tensile force. The test results are shown in Table 1.

[0130] Table 1

[0131]

[0132] Where Eta is the battery efficiency, Isc is the short-circuit current, Voc is the open-circuit voltage, and FF is the fill factor.

[0133] As can be seen from the above examples and comparative examples:

[0134] The electrode 200 of this application contains an alloy seed layer 210 and a diffusion layer 220. The diffusion layer 220 is formed by material diffusion between the alloy seed layer 210 and the substrate 100, thereby effectively improving the bonding force between the alloy seed layer 210 and the substrate 100. Furthermore, an ohmic contact can be formed between the electrode 200 and the substrate 100, thereby improving the photoelectric conversion efficiency and performance stability of the solar cell.

[0135] In summary, this application employs an alloy seed layer 210, which can be a nickel-based alloy or an aluminum-based alloy. Furthermore, other elements can be doped into the alloy seed layer 210. This lowers the melting point of the alloy material, allowing for laser sintering of the alloy powder to form the alloy seed at a lower temperature, thus improving the processing performance of the alloy seed layer 210. Additionally, the doping material can enhance the mechanical properties, corrosion resistance, and oxidation resistance of the alloy seed layer 210. The electrode 200 in this application, through the alloy seed layer 210 and the diffusion layer 220, not only improves the adhesion between the seed layer and the substrate 100 but also enhances the contact effect between them, resulting in low contact resistance. Moreover, the dense structure of the alloy seed layer 210 effectively prevents the influence of copper diffusion on the substrate 100. Furthermore, this application allows for rapid sintering of a patterned alloy seed layer 210 by adjusting the laser path or by pre-setting a laser irradiation pattern. Compared to PVD deposition for seed layer formation, this method is simpler and more efficient.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, The solar cell includes: Substrate (100); The electrode (200) includes an alloy seed layer (210) and a diffusion layer (220). The alloy seed layer (210) is disposed on the substrate (100), and the diffusion layer (220) is disposed between the alloy seed layer (210) and the substrate (100). The material of the diffusion layer (220) comprises a compound composed of elements in the substrate (100) and elements in the alloy seed layer (210).

2. The solar cell as described in claim 1, characterized in that, The diffusion layer (220) is an integral structure with at least one of the alloy seed layer (210) and / or the substrate (100).

3. The solar cell as described in claim 1, characterized in that, The alloy seed layer (210) is made of a metal substrate and a doped material, wherein the doped material is different from the material of the metal substrate. Optionally, the metal substrate includes at least one of nickel, aluminum, titanium, zinc, and magnesium; Optionally, the doping material includes at least one selected from magnesium, nickel, manganese, chromium, zinc, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron, and carbon. Optionally, the mass content of the metal substrate in the material of the alloy seed layer (210) is 60% to 95%.

4. The solar cell as described in claim 1, characterized in that, The diffusion layer (220) includes a first diffusion layer (221) and / or a second diffusion layer (222), wherein the first diffusion layer (221) is fused with the alloy seed layer (210) and the second diffusion layer (222) is fused with the substrate (100); Optionally, the thickness of the first diffusion layer (221) is ≤300nm; Optionally, the thickness of the second diffusion layer (222) is ≤300nm.

5. The solar cell as described in claim 1, characterized in that, The alloy seed layer (210) satisfies at least one of the following conditions: (1) The width of the alloy seed layer (210) is 50μm~500μm; (2) The thickness of the alloy seed layer (210) is 1μm~100μm.

6. The solar cell according to any one of claims 1-5, characterized in that, The electrode (200) further includes a conductive layer (230) disposed on the surface of the alloy seed layer (210). Optionally, the thickness of the conductive layer (230) is 2μm to 10μm; Optionally, the conductive layer (230) may be made of at least one of copper, aluminum and nickel.

7. The solar cell as described in claim 6, characterized in that, The electrode (200) further includes a protective layer (240) disposed on the surface of the conductive layer (230) away from the alloy seed layer (210). Optionally, the thickness of the protective layer (240) is 5μm to 50μm; Optionally, the material of the protective layer (240) includes at least one of tin, lead and aluminum.

8. A method for preparing a solar cell, characterized in that, The method for preparing the solar cell includes: A substrate (100) is provided, and an alloy material layer (101) is formed on the surface of the substrate (100). The alloy material layer (101) is laser sintered, and at the laser sintering location, at least a portion of the alloy material in the alloy material layer (101) diffuses into the substrate (100) and / or at least a portion of the material in the substrate (100) diffuses into the alloy material layer (101) to form a diffusion layer (220), and another portion of the alloy material layer (101) is shaped to form an alloy seed layer (210); and, An electrode (200) is formed on the surface of the substrate (100) based on the alloy seed layer (210).

9. The method for preparing a solar cell as described in claim 8, characterized in that, The method for preparing the solar cell satisfies at least one of the following conditions: (1) The thickness of the alloy material layer (101) is 1μm~100μm; (2) During the laser sintering process, the alloy material layer (101) is heated to 500℃~1400℃.

10. The method for preparing a solar cell as described in claim 8, characterized in that, The method for forming the alloy material layer (101) includes: After mixing the metal substrate and the doped material, the alloy material layer (101) is formed on the surface of the substrate (100). Optionally, the metal substrate includes nickel, and the doping material includes at least one of chromium, molybdenum, aluminum, zirconium, iron, titanium, silicon, boron and carbon. During the laser sintering process, the alloy material layer (101) is heated to 992°C~1400°C. Optionally, the metal substrate includes aluminum, and the doping material includes at least one of magnesium, manganese, chromium, zinc, iron, nickel, titanium, silicon, boron and carbon. During the laser sintering process, the alloy material layer (101) is heated to 577°C to 660°C.

11. The method for preparing a solar cell according to any one of claims 8-10, characterized in that, The preparation method further includes: forming a conductive layer (230) on the surface of the alloy seed layer (210); Optionally, the conductive layer (230) is formed by at least one of electroplating, electroless plating and physical vapor deposition. Optionally, the preparation method further includes forming a protective layer (240) on the surface of the conductive layer (230). Optionally, the protective layer (240) may be formed by at least one of electroplating, electroless plating and physical vapor deposition.

12. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell according to any one of claims 1-7 and / or the solar cell prepared by the method according to any one of claims 8-11.

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