Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof. The method comprises the following steps: providing a first donor, a second donor and an acceptor; arranging a first donor relative to the acceptor, and irradiating the surface, far away from the first coating, of the first donor by adopting first laser according to a first preset pattern, so that the conductive material on the first donor is transferred to the first conductive layer to form a second conductive layer; and arranging the second donor relative to the acceptor, and irradiating the surface, far away from the second coating, of the second donor by adopting second laser according to a second preset pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer. According to the method provided by the invention, the conductive layer with both thickness and conductivity can be prepared by adopting the first laser induction and the second laser induction, so that the photoelectric conversion efficiency of the solar cell can be improved, and the method is simple to operate.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for preparing the same. Background Art

[0002] In recent years, with the rapid development of the photovoltaic industry, domestic and foreign markets have put forward higher and higher requirements for the conversion efficiency and product performance of solar cells and photovoltaic modules, which has also prompted industry manufacturers to actively conduct research on new battery, module structure and related processes. Heterojunction (HJT) solar cells have the advantages of low light decay and low temperature coefficient, which can reduce energy consumption while reducing thermal damage to the silicon substrate.

[0003] Heterojunction cells are mainly formed by depositing intrinsic amorphous silicon thin films on both sides of the silicon substrate, and then depositing P-type and N-type amorphous or microcrystalline silicon thin films respectively to form a heterojunction; and after preparing a transparent conductive oxide layer (TCO) on the surface of the amorphous silicon or microcrystalline silicon thin film on both sides of the silicon substrate, a low-temperature silver paste is used for screen printing and solidification on the surface of the conductive layer to form a metal electrode. TCO plays a vital role in the structure of heterojunction cells, so it is required to have excellent optical and good electrical properties. However, the conductive layer material itself has a certain parasitic absorption. If the conductive layer is too thick, it will cause optical absorption loss of the solar cell. In addition, there is a large contact resistance between the current TCO and the electrode, which affects the photoelectric conversion rate of the solar cell. In addition, as the silver consumption in the photovoltaic industry gradually increases, the manufacturing cost of solar cells increases.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The embodiments of the present application provide a solar cell and a method for manufacturing the same to solve or alleviate one or more of the technical problems mentioned above.

[0006] In a first aspect of an embodiment of the present application, a method for preparing a solar cell is provided. The method comprises (1) providing a first donor, a second donor and a receptor, wherein the first donor comprises a support body capable of transmitting laser light and a first coating layer comprising a conductive material, the second donor comprises a support body capable of transmitting laser light and a second coating layer comprising a metal material, and the receptor is a silicon wafer having a first conductive layer; (2) arranging the first donor relative to the receptor, and irradiating the surface of the first donor away from the first coating layer with a first laser according to a first predetermined pattern, so that the conductive material on the first donor is transferred to the first conductive layer to form a second conductive layer; (3) arranging the second donor relative to the receptor, and irradiating the surface of the second donor away from the second coating layer with a second laser according to a second predetermined pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer.

[0007] The method of the present application adopts a laser irradiation induction method to form the second conductive layer and the metal seed layer. The laser irradiation induction makes the interface contact resistance between the first conductive layer and the second conductive layer, and between the second conductive layer and the metal seed layer small, and the second conductive layer is formed on the first conductive layer according to the first predetermined pattern, that is, the second conductive layer exists only in a part of the first conductive layer, which can reduce parasitic absorption, thereby improving the photoelectric conversion efficiency of the solar cell containing the electrode prepared by the method. At the same time, the method is simple to operate and does not require the introduction of other complex process steps.

[0008] Specifically, according to the first predetermined pattern, the first laser pulse is used to transfer the conductive layer material from the first donor to the predetermined area on the first conductive layer to form the second conductive layer. The second conductive layer obtained in this way is uniformly distributed, has a controllable thickness, and has a small interface contact resistance between the second conductive layer and the first conductive layer. The second conductive layer only exists on the predetermined area of ​​the first conductive layer, which can reduce parasitic absorption. Similarly, the second laser pulse transfers the metal material from the second donor to the predetermined area of ​​the second conductive layer, and a metal seed layer with uniform distribution and controllable thickness can be obtained, and the interface contact resistance between the metal seed layer and the second conductive layer is small, and the metal seed layer and the second conductive layer are in close contact, so that the pull-off force between the metal seed layer and the first electrode is also improved.

[0009] The second conductive layer acts as a thickening layer in conjunction with the first conductive layer, which is beneficial to reducing the resistivity between the electrode and the second conductive layer. This is because the second conductive layer is formed on the first conductive layer according to the first predetermined pattern, that is, the second conductive layer exists only in a partial area of ​​the first conductive layer. On the one hand, the purpose of thickening the conductive layer is achieved; on the other hand, such a conductive layer (a combination of the first conductive layer and the second conductive layer) has a low square resistance and a low resistance, which is particularly beneficial for the internal carriers of the solar cell to gather on the electrode.

[0010] According to an embodiment of the present application, in the first laser irradiation state, the distance between the first donor and the first conductive layer is 200-500 μm.

[0011] According to an embodiment of the present application, in the second laser irradiation state, the distance between the second donor and the second conductive layer is 100-300 μm.

[0012] According to an embodiment of the present application, the thickness of the first conductive layer is 60-90 nm.

[0013] According to an embodiment of the present application, the thickness of the second conductive layer is 100-200 nm.

[0014] According to an embodiment of the present application, the thickness of the metal seed layer is 30-80 nm.

[0015] According to an embodiment of the present application, the conductive material includes at least one of indium tin oxide and zinc aluminum oxide.

[0016] According to an embodiment of the present application, the metal material includes at least one of nickel, titanium, aluminum, cobalt, and chromium.

[0017] According to an embodiment of the present application, the width of the second conductive layer is M1, the width of the metal seed layer is M2, and 0.1≤M2 / M1≤0.5.

[0018] According to an embodiment of the present application, the wavelengths of the first laser and the second laser are independently 300-450 nm, and the powers are independently 30-80 mJ.

[0019] According to an embodiment of the present application, the method further includes: forming a first electrode on a side of the metal seed layer away from the second conductive layer by laser-assisted electroplating.

[0020] According to an embodiment of the present application, the step of laser-assisted electroplating includes: contacting the metal seed layer with a plating solution, connecting the cathode of the electroplating device to the battery cell obtained by forming the metal seed layer, and contacting the anode with the plating solution; and scanning the metal seed layer with a third laser to form the first electrode on the metal seed layer.

[0021] According to the embodiment of the present application, the wavelength of the third laser is 450-600nm, and the power is 700-900W / cm 2 .

[0022] According to an embodiment of the present application, the scanning speed of the third laser is 15000-25000 mm / s, the scanning frequency is 50-150 KHz, and the time is 40-80 s.

[0023] According to an embodiment of the present application, the thickness of the first electrode is 10-16 μm.

[0024] According to an embodiment of the present application, the method further includes: forming a second electrode on a surface of the first electrode away from the metal seed layer by chemical plating.

[0025] The second aspect of the embodiment of the present application provides a solar cell, which is prepared by the method of the first aspect. The cell has good photoelectric conversion efficiency. This is because the contact between the electrode and the conductive layer in the solar cell of the embodiment of the present application is good, the second conductive layer is formed at a predetermined pattern by laser induction, and then a metal seed layer is formed on the second conductive layer by laser induction, so that the resistance of the contact interface between the conductive layer and the electrode is small, thereby improving the photoelectric conversion efficiency of the solar cell.

[0026] In a third aspect of the embodiments of the present application, a photovoltaic module is provided, wherein the photovoltaic module comprises a plurality of solar cells connected in series and / or in parallel; wherein at least one solar cell is a solar cell of the second aspect of the present application. A plurality of solar cells in series form a cell string, and adjacent heterojunction solar cells can be connected together by string welding.

[0027] In the fourth aspect of the present application, a photovoltaic system is provided, comprising the photovoltaic assembly of the third aspect of the present application. The photovoltaic system also has the advantages of the above photovoltaic assembly, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0029] Figure 1 is a schematic diagram of a process of laser-induced formation of a second conductive layer in some embodiments; Figure 2 is a schematic diagram of a process of forming a first electrode by laser-assisted electroplating in some embodiments; Figure 3 Schematic diagram of solar cell structure according to some embodiments.

[0030] Description of reference numerals: 1: quartz; 2: first coating; 3: receptor; 4: first laser; 5: cathode; 6: battery cell; 7: anode; 8: third laser; 9: electroplating solution; 10: intrinsic amorphous silicon layer; 11: N-type doped silicon film layer; 12: first conductive layer; 13: second conductive layer; 14: metal seed layer; 15: first electrode; 16: second electrode; 17: silicon substrate; 18: P-type doped silicon film layer. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0032] It should be understood that when a layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another layer, it may be directly on, adjacent to, connected to, or coupled to the other layer, or there may be intervening layers. It should be understood that although the terms first, second, third, etc. may be used to describe various layers and / or portions, these layers and / or portions should not be limited by these terms. These terms are merely used to distinguish one layer or portion from another. Therefore, without departing from the teachings of the present disclosure, the first layer or portion discussed below may be represented as the second layer or portion. And when the second layer or portion is discussed, it does not mean that the present disclosure necessarily has the first layer or portion.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a method or product comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, and products.

[0034] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each 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 range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0035] The inventors found that controlling the thickness of the conductive layer can reduce parasitic absorption of light, but reducing the thickness of the conductive layer will cause its conductivity to decrease and increase the contact resistance between the electrode and the conductive layer; in addition, as the silver consumption in the photovoltaic industry gradually increases, the manufacturing cost of solar cells increases.

[0036] In the first aspect of the embodiments of the present application, a method for preparing a solar cell is proposed. The method comprises: (1) providing a first donor, a second donor and a receptor, wherein the first donor comprises a support body capable of transmitting laser light and a first coating layer comprising a conductive material, the second donor comprises a support body capable of transmitting laser light and a second coating layer comprising a metal material, and the receptor is a silicon wafer having a first conductive layer; (2) arranging the first donor relative to the receptor, and irradiating the surface of the first donor away from the first coating layer with a first laser according to a first predetermined pattern, so that the conductive material on the first donor is transferred to the first conductive layer to form a second conductive layer; (3) arranging the second donor relative to the receptor, and irradiating the surface of the second donor away from the second coating layer with a second laser according to a second predetermined pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer.

[0037] The method of the embodiment of the present application adopts a laser irradiation induction method to form the second conductive layer and the metal seed layer. The laser irradiation induction makes the interface contact resistance between the first conductive layer and the second conductive layer, and between the second conductive layer and the metal seed layer small, and the second conductive layer is formed on the first conductive layer according to the first predetermined pattern, that is, the second conductive layer exists only in a part of the first conductive layer, which can reduce parasitic absorption, thereby improving the photoelectric conversion efficiency of the solar cell containing the electrode prepared by the method. At the same time, the method is simple to operate and does not require the introduction of other complex process steps.

[0038] Specifically, according to the first predetermined pattern, the first laser pulse is used to transfer the conductive layer material from the first donor to the predetermined area on the first conductive layer to form the second conductive layer. The second conductive layer obtained in this way is uniformly distributed, has a controllable thickness, and has a small interface contact resistance between the second conductive layer and the first conductive layer. The second conductive layer only exists on the predetermined area of ​​the first conductive layer, which can reduce parasitic absorption. Similarly, the second laser pulse transfers the metal material from the second donor to the predetermined area of ​​the second conductive layer, and a metal seed layer with uniform distribution and controllable thickness can be obtained, and the interface contact resistance between the metal seed layer and the second conductive layer is small, and the metal seed layer and the second conductive layer are in close contact, so that the pull-off force between the metal seed layer and the first electrode is also improved.

[0039] The second conductive layer interacts with the first conductive layer as a thickening layer, which is beneficial to reducing the resistivity between the electrode and the conductive layer. This is because the second conductive layer is formed on the first conductive layer according to the first predetermined pattern, that is, the second conductive layer exists only in a part of the first conductive layer, thereby achieving the purpose of thickening the conductive layer. Moreover, such a conductive layer (a combination of the first conductive layer and the second conductive layer) has a low square resistance and a low resistance, which is particularly beneficial for the internal carriers of the solar cell to gather on the electrode.

[0040] According to the present application, in step (1), a first donor, a second donor and a receptor are provided, wherein the first donor comprises a support body capable of transmitting laser light and a first coating layer comprising a conductive material, the second donor comprises a support body capable of transmitting laser light and a second coating layer comprising a metal material, and the receptor is a silicon wafer having a first conductive layer.

[0041] In some embodiments, in step (1), the support body comprises quartz, or other transparent materials.

[0042] In some embodiments, in step (1), the conductive material includes at least one of indium tin oxide and zinc aluminum oxide.

[0043] In some embodiments, in step (1), the metal material includes at least one of nickel, titanium, aluminum, cobalt, and chromium.

[0044] In some embodiments, in step (1), the thickness of the first conductive layer is 60-90 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, etc. Thus, the photoelectric conversion efficiency of the solar cell is further improved.

[0045] In some embodiments, in step (1), the receptor is a silicon wafer having a first conductive layer. The receptor structure further includes an intrinsic amorphous silicon layer, a doped silicon film layer, and a first conductive layer. The intrinsic amorphous silicon layer is disposed on two opposite sides of the silicon substrate; the doped silicon film layer is located on a side of the intrinsic amorphous silicon layer away from the silicon substrate; and the first conductive layer is located on a side of the doped silicon film layer away from the intrinsic amorphous silicon layer.

[0046] According to an embodiment of the present application, in step (2), the first donor is arranged relative to the receptor, and the surface of the first donor away from the first coating layer is irradiated with a first laser according to a first predetermined pattern, so that the conductive material on the first donor is transferred to the first conductive layer to form a second conductive layer. In this step, the conductive material is transferred to the first conductive layer by laser irradiation according to the first predetermined pattern to form a second conductive layer in a partial area of ​​the first conductive layer.

[0047] In an embodiment of the present application, the first predetermined pattern is designed according to the position of the electrode in the solar cell to design the position of the second conductive layer, and then the first laser is irradiated according to the predetermined first predetermined pattern to transfer the conductive material on the first donor to the first conductive layer.

[0048] In the embodiment of the present application, the first donor is arranged relative to the receptor, that is, the positions of the first donor and the receptor are arranged according to the purpose of forming the second conductive layer on the first conductive layer by laser induction.

[0049] In the embodiment of the present application, the second conductive layer is formed in a predetermined area of ​​the first conductive layer, and the predetermined area is a pattern design (first predetermined pattern) based on the electrode position of the solar cell. Therefore, the second conductive layer only thickens a part of the first conductive layer. The conductive layer with such a structure can improve the contact between the subsequent electrode and the conductive layer, and reduce the resistivity between the electrode and the conductive layer.

[0050] In some embodiments, in step (2), the thickness of the second conductive layer is 100-200 nm, such as 100 nm, 140 nm, 150 nm, 160 nm, 200 nm, etc. The second conductive layer can be formed as a thickened conductive layer on the basis of the first conductive layer to improve the electrical performance of the conductive layer and reduce parasitic absorption.

[0051] In some embodiments, in step (2), under the first laser irradiation state, the distance between the first donor and the first conductive layer is 200-500 μm, such as 200 μm, 250 μm, 300 μm, 360 μm, 400 μm, 500 μm, etc. Thus, it is possible to avoid as much as possible that the distance is too short, the kinetic energy of the material sputtered by the laser from the first donor is too large, causing damage to the first conductive layer, and to avoid as much as possible that the distance is too far, the kinetic energy is insufficient, and it is difficult to make the conductive layer material of the first donor adhere to the surface of the first conductive layer.

[0052] In some embodiments, reference Figure 1 The step of forming the second conductive layer includes: turning on the first laser source, placing the first donor and the receptor perpendicular to the direction of gravity, and using the first laser 4 to irradiate the surface of the quartz 1 away from the first coating 2, and making the side of the first donor with the first coating 2 close to the receptor 3, the first laser source irradiates according to a predetermined pattern, and sputters the conductive material to the first conductive layer to form the second conductive layer.

[0053] Optionally, the wavelength of the first laser is 300-450 nm, such as 300 nm, 340 nm, 390 nm, 410 nm, 450 nm, etc. Thus, the first laser in this wavelength range can penetrate the support body and induce the material of the first coating to be transferred to the first conductive layer.

[0054] Optionally, the power is 30-50 mJ, such as 30 mJ, 33 mJ, 38 mJ, 41 mJ, 45 mJ, 50 mJ, etc. Thus, the first laser in this power range can penetrate the support body and induce the first coating material to be transferred to the first conductive layer.

[0055] Optionally, the first laser may be an ultraviolet picosecond laser.

[0056] According to an embodiment of the present application, in step (3), the second donor is arranged relative to the receptor, and the surface of the second donor away from the second coating is irradiated with a second laser according to a second predetermined pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer. In this step, a second donor having a metal material is arranged above the second conductive layer, and the metal material is transferred to the second conductive layer by a laser according to a predetermined pattern. That is, the second laser scans the second donor according to a predetermined pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer.

[0057] In the embodiment of the present application, the second predetermined pattern is designed according to the position of the electrode in the solar cell, and then the second laser is irradiated according to the predetermined second predetermined pattern to induce the transfer of the material on the second donor to the second conductive layer. The metal seed layer obtained in this way has good contact with the second conductive layer and has a low interface resistance, which can improve the contact between the subsequent electrode and the second conductive layer and reduce the resistivity of the solar cell. In addition, no mask is required in the process of forming the metal seed layer, and the operation is simple.

[0058] In some embodiments, in step (3), during the process of forming the metal seed layer, it is only necessary to replace the first donor with a second donor, and use a second laser to irradiate the surface of the second donor away from the second coating so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer.

[0059] In some embodiments, in step (3), the thickness of the metal seed layer is 30-80 nm, such as 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, etc. Thus, a suitable opening can be obtained to facilitate the formation of the second conductive layer and improve the adhesion of the metal seed layer to the second conductive layer.

[0060] In some embodiments, in step (3), the width of the second conductive layer is M1, the width of the metal seed layer is M2, and 0.1≤M2 / M1≤0.5. The width of the second conductive layer is greater than the width of the metal seed layer, and in the process of forming the metal seed layer, the metal seed layer can be prevented from being formed on the first conductive layer, causing electrode failure.

[0061] In some embodiments, in step (3), under the second laser irradiation state, the distance between the second donor and the second conductive layer is 100-300 μm, such as 100 μm, 140 μm, 190 μm, 200 μm, 250 μm, 300 μm, etc. Thus, it is possible to avoid as much as possible that the distance is too short, the kinetic energy of the material sputtered by the laser from the second donor is too large, causing damage to the second conductive layer, and to avoid as much as possible that the distance is too long, the kinetic energy is insufficient, and it is difficult to make the metal material of the second donor adhere to the surface of the second conductive layer.

[0062] Preferably, in the second laser irradiation state, the distance between the second donor and the second conductive layer is 200 μm.

[0063] In some embodiments, the step of forming a metal seed layer includes: turning on a second laser source, and using the second laser source to irradiate the surface of the quartz plate away from the metal material layer, and making the side of the second donor having the metal material layer close to the second conductive layer and the side surface away from the first conductive layer, allowing the first laser source to scan according to a predetermined pattern, and sputtering the metal material to transfer to the second conductive layer to form a metal seed layer.

[0064] Optionally, the wavelength of the second laser source is 300-450 nm, such as 300 nm, 340 nm, 390 nm, 410 nm, 450 nm, etc. Thus, the second laser penetrates the support body to induce the transfer of the second coating material to the second conductive layer.

[0065] Optionally, the power of the second laser source is 30-50 mJ, such as 30 mJ, 33 mJ, 38 mJ, 41 mJ, 45 mJ, 50 mJ, etc. Thus, the second laser penetrates the support body to induce transfer of the second coating material to the second conductive layer.

[0066] In some embodiments, the method for preparing an electrode further comprises step (4), forming a first electrode on a side of the metal seed layer away from the second conductive layer by laser-assisted electroplating.

[0067] In some embodiments, in step (4), the laser-assisted electroplating step includes: contacting the metal seed layer with the electroplating solution, connecting the cathode of the electroplating device to the battery cell obtained by forming the metal seed layer, and contacting the anode with the electroplating solution; scanning the metal seed layer with a third laser to form the first electrode on the metal seed layer. Scanning the metal seed layer with the third laser will activate the irradiated area, making it easier to form a plated metal during the electroplating process, and the operation is simple and does not require a mask. In addition, during the electroplating process, the metal seed layer is covered with the electroplating solution instead of being placed in the electroplating solution. In this way, during the electroplating process, a small amount of electroplating solution causes electroplating to occur almost only in the area scanned by the laser, and the first electrode will not be formed in other areas.

[0068] In some embodiments, reference Figure 2 The steps of laser-assisted electroplating include: contacting the metal seed layer with the electroplating solution, that is, covering the surface of the metal seed layer with the electroplating solution 9, and connecting the cathode 5 of the electroplating device with the battery cell 6 obtained by forming the metal seed layer, and contacting the anode 7 with the electroplating solution 9; using a third laser 8 to scan the metal seed layer according to a predetermined pattern to form the first electrode at the predetermined pattern.

[0069] In some embodiments, the electroplating solution is a copper electroplating solution.

[0070] In some embodiments, the wavelength of the third laser is 450-600 nm, such as 450 nm, 500 nm, 550 nm, 600 nm, etc. Power 700-900 W / cm 2 , for example 700W / cm 2 、750W / cm 2 , 800W / cm 2 、850W / cm 2 , 900W / cm 2 wait.

[0071] In some embodiments, the scanning speed is 15000-25000 mm / s, for example 15000 mm / s, 20000 mm / s, 21000 mm / s, 25000 mm / s, etc., the frequency is 50-150 KHz, for example 50 KHz, 100 KHz, 150 KHz, etc., and the time is 40-80s, for example 40s, 50s, 70s, 80s, etc.

[0072] In some embodiments, the laser can be divided into multiple beams, each with a diameter of 3-8 μm and a power of 700-900 W / cm 2 This causes the electrodes of the solar cell to be irradiated with laser light and causes the laser to perform scanning motion to promote the electroplating process.

[0073] In some embodiments, the thickness of the first electrode is 10-16 μm, such as 10 μm, 12 μm, 14 μm, 16 μm, etc.

[0074] In some embodiments, the width of the first electrode is M3, and 0.9≤M3 / M2≤2.

[0075] In some embodiments, the method further comprises: forming a second electrode by chemical plating on a surface of the first electrode away from the metal seed layer, so that the second electrode can protect the first electrode to reduce the risk of oxidation or corrosion of the first electrode.

[0076] Furthermore, the electroless plating solution includes a silver plating solution, and the electroless plating time is 20-50s.

[0077] In some embodiments, the thickness of the second electrode is 0.5-2 μm, such as 0.5 μm, 1 μm, 2 μm, etc.

[0078] In some embodiments, the first electrode may be copper and the second electrode may be silver, which can greatly reduce the cost of the electrodes.

[0079] The second aspect of the embodiment of the present application provides a solar cell, which is prepared by the method of the first aspect. The cell has good photoelectric conversion efficiency, which is because the contact between the electrode and the conductive layer in the solar cell of the embodiment of the present application is good, the second conductive layer is formed at a predetermined pattern by laser induction, and then a metal seed layer is formed on the second conductive layer by laser induction, so that the resistance of the contact interface between the conductive layer and the electrode is small, thereby improving the photoelectric conversion efficiency of the solar cell.

[0080] In some embodiments, reference Figure 3 The solar cell includes: a silicon substrate 17, an intrinsic amorphous silicon layer 10, an N-type doped silicon film layer 11, a first conductive layer 12, a second conductive layer 13, a metal seed layer 14, a first electrode 15, a second electrode 16, and a P-type doped silicon film layer 18. The intrinsic amorphous silicon layer 10 is located on two opposite sides of the silicon substrate 17; the N-type doped silicon film layer 11 is located on a side surface of the intrinsic amorphous silicon layer 10 away from the silicon substrate 17; a first conductive layer 12 is located on a side surface of the N-type doped silicon film layer 11 away from the silicon substrate 17; a second conductive layer 13 is located on a side surface of the first conductive layer 12 away from the silicon substrate 17; a metal seed layer 14 is located on a side surface of the second conductive layer 13 away from the silicon substrate 17; a first electrode 15 is located on a side surface of the metal seed layer 14 away from the silicon substrate 17; and a second electrode 16 is located on a side surface of the first electrode 15 away from the silicon substrate 17. ; The P-type doped silicon film layer 18 is located on a side surface of another intrinsic amorphous silicon layer 10 away from the silicon substrate 17; another first conductive layer 12 is located on a side surface of the P-type doped silicon film layer 18 away from the silicon substrate 17; another second conductive layer 13 is located on a side surface of the first conductive layer 12 away from the P-type doped silicon film layer 18; another metal seed layer 14 is located on a side surface of the second conductive layer 13 away from the P-type doped silicon film layer 18; another first electrode 15 is located on a side surface of the metal seed layer 14 away from the P-type doped silicon film layer 18; another second electrode 16 is located on a side surface of the first electrode 15 away from the P-type doped silicon film layer 18.

[0081] In some embodiments, the method for preparing the solar cell includes: S1: Texturing and cleaning The N-type silicon wafer with a thickness of 100-150μm is textured and cleaned to form a uniform "positive pyramid" texture surface on the two opposite surfaces of the silicon wafer, and the texture surface height is 1μm-2μm.

[0082] S2: Forming an intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer A PECVD plasma deposition device is used to deposit a first intrinsic amorphous silicon film layer with a thickness of 3nm-6nm on the front side of the silicon wafer after texturing and cleaning, and a second intrinsic amorphous silicon film layer with a thickness of 3nm-9nm is deposited on the back side of the silicon wafer.

[0083] S3: Forming an N-type doped silicon film layer and a P-type doped silicon film layer A PECVD plasma deposition device is used to deposit a 5nm-10nm thick phosphorus-doped amorphous silicon layer (N-type doped silicon film layer) on the surface of the first intrinsic amorphous silicon film layer, and a 5nm-15nm boron-doped amorphous silicon layer (P-type doped silicon film layer) is deposited on the surface of the second intrinsic amorphous silicon film layer.

[0084] S4: Forming the first conductive layer An ITO conductive film (first conductive layer) with a thickness of about 70nm-110nm is deposited on the surface of the N-type amorphous silicon layer using PVD magnetron sputtering equipment, and an ITO conductive film (first conductive layer) with a thickness of about 70nm-110nm is deposited on the surface of the P-type amorphous silicon layer.

[0085] S5: Forming a second conductive layer, a metal seed layer, a first electrode, and a second electrode The second conductive layer, the metal seed layer, the first electrode and the second electrode are formed by the method described in the first aspect above.

[0086] In a third aspect of the embodiments of the present application, a photovoltaic module is provided, wherein the photovoltaic module comprises a plurality of solar cells connected in series and / or in parallel; wherein at least one solar cell is a solar cell of the second aspect of the embodiments of the present application. The plurality of solar cells in series form a cell string, and adjacent heterojunction solar cells can be connected together by string welding.

[0087] In the fourth aspect of the present application, a photovoltaic system is provided, comprising the photovoltaic assembly of the third aspect of the present application. The photovoltaic system also has the advantages of the above photovoltaic assembly, which will not be described in detail here.

[0088] The above-mentioned photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it is understandable that the application scenarios of photovoltaic systems are not limited to this, that is to say, photovoltaic systems can be used in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0089] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0090] Example 1 An N-type silicon wafer (210 mm long and 105 mm wide) with a thickness of 150 μm was textured and cleaned to form a uniform "positive pyramid" texture surface on the two opposite surfaces of the silicon wafer with a texture height of 2 μm.

[0091] A PECVD plasma deposition device is used to deposit a first intrinsic amorphous silicon film layer with a thickness of 6 nm on the front side of the silicon wafer after texturing and cleaning, and a second intrinsic amorphous silicon film layer with a thickness of 9 nm is deposited on the back side of the silicon wafer.

[0092] A PECVD plasma deposition device is used to deposit a 10 nm thick phosphorus-doped amorphous silicon layer (N-type doped silicon film layer) on the surface of the first intrinsic amorphous silicon film layer, and a 5 nm thick boron-doped amorphous silicon layer (N-type doped silicon film layer) is deposited on the surface of the second intrinsic amorphous silicon film layer.

[0093] An ITO conductive film (first conductive layer) with a thickness of about 80 nm is deposited on the surface of the N-type amorphous silicon layer using a PVD magnetron sputtering device, and an ITO conductive film (first conductive layer) with a thickness of about 80 nm is deposited on the surface of the P-type amorphous silicon layer.

[0094] A 500nm thick AZO (aluminum zinc oxide) film was prepared on the surface of a 0.5 mm thick (230 mm long, 200 mm wide) quartz plate using magnetron sputtering as the first donor for LIFT (laser-induced forward transfer). The AZO film material was sputtered onto the surface of the first conductive layer from the back of the donor using an ultraviolet picosecond laser (wavelength 355nm, power 40mJ) according to a pre-designed electrode pattern. The distance between the first donor and the first conductive layer was 300μm). The width of the second conductive layer was 50μm and the thickness was 150nm.

[0095] A 100nm thick Ni film was prepared on the surface of a 0.5mm thick (230mm long, 200mm wide) quartz plate by magnetron sputtering to serve as the second donor for LIFT (laser-induced forward transfer). A UV picosecond laser (wavelength 355nm, power 60 mJ) was used to sputter the Ni film material onto the surface of the second conductive layer (the distance between the second donor and the second conductive layer was 200μm) from the back of the donor according to the pre-designed electrode pattern. The nickel seed layer had a width of 10μm and a thickness of 50nm.

[0096] The cell with the copper seed layer formed is placed on the cathode contact of the laser-assisted electroplating, and the electroplating copper solution is dripped onto the copper seed layer on the cell, ensuring that the plating solution covers the copper seed layer and does not overflow. At this time, the anode contact is immersed in the copper electroplating solution. The current density of the electroplated copper is 2A / dm 2 The laser above the cell uses a green picosecond laser (wavelength 532nm), and a beam splitter is used to split a single beam into multiple beams, each with a spot diameter of 6μm and an irradiation power of 800W / cm 2 . Ensure that each grid line (where the electrode is formed) in the cell is irradiated by laser, and each beam scans back and forth along the grid line direction, with a movement rate of 20000mm / s and a frequency of 100KHz. The laser-assisted electroplating lasts for 60s, and the copper electrode layer is 13μm thick and 16μm wide.

[0097] After the copper seed layer is formed, the copper plating solution on the cell is rinsed clean and then immersed in a chemical silver plating solution for 30 seconds. Finally, silver with a thickness of about 1 μm is deposited on the surface of the copper electrode. The cell is taken out and dried to obtain a solar cell.

[0098] Example 2 A solar cell was prepared in the same manner as in Example 1, except that the thickness of the first conductive layer was 80 nm, and the thickness of the second conductive layer was 100 nm.

[0099] Example 3 A solar cell was prepared in the manner of Example 1, except that the thickness of the first conductive layer was 80 nm, and the thickness of the second conductive layer was 200 nm.

[0100] Example 4 and Example 5 A solar cell was prepared in the same manner as in Example 1, except that the distances between the first donor and the first conductive layer were 200 μm and 500 μm, respectively. The distances between the second donor and the second conductive layer are 100 μm and 300 μm respectively.

[0101] Examples 6 and 7 Solar cells were prepared in the same manner as in Example 1, except that the thicknesses of the nickel seed layer were 30 nm and 80 nm, respectively.

[0102] Examples 8 and 9 Solar cells were prepared in the same manner as in Example 1, except that the widths of the nickel seed layer were 5 μm and 25 μm, respectively.

[0103] Comparative Example 1 A solar cell is prepared in the manner of Example 1, except that, in the process of forming the second conductive layer, the width and length of the second conductive layer are the same as the first conductive layer, that is, the second conductive layer completely covers the first conductive layer in a direction perpendicular to the thickness of the second conductive layer, and the second conductive layer is obtained by depositing on the first conductive layer using a PEVCD device.

[0104] Test Case The heterojunction solar cells of the above embodiments and comparative examples were subjected to the following performance tests, and the test results are shown in Table 1: Photoelectric conversion efficiency, short-circuit current, open-circuit voltage, and fill factor testing: The specific testing method is to place the battery under a light source of 100 mW / cm 2 The results are obtained by connecting a source meter using the four-wire method under AM 1.5G simulated sunlight at 25°C.

[0105] Table 1

[0106] The data in the above table can illustrate that the laser induced process of the present application for obtaining the second conductive layer by comparison with Examples 1-3 is beneficial to reducing the resistance between the electrode and the second conductive layer, thereby improving the photoelectric conversion efficiency of the solar cell. This shows that the second conductive layer formed by the method of the present application has a positive effect on improving the photoelectric conversion efficiency. This is because the second conductive layer better balances the fill factor of the battery (dominated by the contact resistance between the electrode and the solar cell) and the short-circuit current (dominated by the parasitic absorption brought by the second conductive layer).

[0107] The corresponding photoelectric conversion data of Examples 4 and 5 show that when the distance between the donor and the acceptor is too close, the sputtered material damages the solar cell substrate, induces passivation degradation, and reduces the open circuit voltage. When the distance is too far, the adhesion between the sputtered material and the acceptor is weakened, which is manifested as an increase in contact resistance and a decrease in fill factor (FF).

[0108] Examples 6-9 reflect the influence of the thickness and width of the nickel seed layer on the photovoltaic conversion efficiency of the cell. The thicker the thickness, the lower the contact resistance between the electrode and the solar cell substrate, but it may cause deeper thermal damage, resulting in a decrease in open circuit voltage. The wider the width, on the one hand, reduces the contact resistance, and on the other hand, increases the shading area, resulting in a decrease in short-circuit current (Isc).

[0109] It should be noted that the "some embodiments", "other embodiments", "embodiments", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure or characteristic is described in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0110] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0111] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a solar cell, characterized in that: include: Providing a first donor, a second donor and a receptor, wherein the first donor comprises a support body capable of transmitting laser light and a first coating layer comprising a conductive material, the second donor comprises a support body capable of transmitting laser light and a second coating layer comprising a metal material, and the receptor is a silicon wafer having a first conductive layer; Arranging the first donor relative to the receptor and irradiating the surface of the first donor away from the first coating layer with a first laser according to a first predetermined pattern so that the conductive material on the first donor is transferred to the first conductive layer to form a second conductive layer; The second donor is arranged relative to the receptor, and a second laser is used to irradiate the surface of the second donor away from the second coating layer according to a second predetermined pattern, so that the metal material on the second donor is transferred to the second conductive layer to form a metal seed layer.

2. The preparation method according to claim 1, characterized in that: In the first laser irradiation state, the distance between the first donor and the first conductive layer is 200-500 μm; And / or, in the second laser irradiation state, the distance between the second donor and the second conductive layer is 100-300 μm.

3. The preparation method according to claim 1, characterized in that: The thickness of the first conductive layer is 60-90 nm; And / or, the thickness of the second conductive layer is 100-200 nm; And / or, the thickness of the metal seed layer is 30-80 nm.

4. The preparation method according to claim 1, characterized in that: The conductive material includes at least one of indium tin oxide and zinc aluminum oxide; And / or, the metal material includes at least one of nickel, titanium, aluminum, cobalt, and chromium.

5. The preparation method according to claim 1, characterized in that: The width of the second conductive layer is M1, the width of the metal seed layer is M2, and 0.1≤M2 / M1≤0.

5.

6. The preparation method according to claim 1, characterized in that: The wavelengths of the first laser and the second laser are independently 300-450 nm, and the powers are independently 30-80 mJ.

7. The preparation method according to claim 1, characterized in that: The method further includes: forming a first electrode on a side of the metal seed layer away from the second conductive layer by laser assisted electroplating.

8. The preparation method according to claim 7, characterized in that: The method of forming the first electrode by laser-assisted electroplating comprises: The metal seed layer is contacted with an electroplating solution, and the cathode of the electroplating device is connected to the battery cell obtained by forming the metal seed layer, and the anode is contacted with the electroplating solution; The metal seed layer is scanned by a third laser to form the first electrode on the metal seed layer.

9. The preparation method according to claim 8, characterized in that: The wavelength of the third laser is 450-600nm, and the power is 700-900W / cm 2 ; And / or, the speed of the third laser scanning is 15000-25000 mm / s, the frequency is 50-150 KHz, and the time is 40-80 s.

10. The preparation method according to claim 7, characterized in that: The thickness of the first electrode is 10-16 μm.

11. The preparation method according to claim 7, characterized in that: Also includes: A second electrode is formed on a surface of the first electrode away from the metal seed layer by chemical plating.

12. A solar cell, characterized in that: Obtained by the preparation method according to any one of claims 1 to 11.

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