Solar cell and preparation method thereof

Abstract

The invention relates to a solar cell and a preparation method thereof. The preparation method of the solar cell comprises the following steps: providing a substrate; forming a front surface structure layer covering the front surface of the substrate and extending to cover the upper part of the side surface of the substrate; forming a front oxide layer on the surface, deviating from the substrate, of the front structure layer; forming a back surface structure layer covering the back surface of the substrate and extending to cover the lower part of the side surface of the substrate; forming a back oxide layer on the surface, deviating from the substrate, of the back structure layer; removing the front oxide layer, the front structure layer, the back oxide layer and a part of the back structure layer on the side surface of the substrate by adopting a one-step laser process; and removing the residual back surface structure layer on the side surface of the substrate through wet chemistry. According to the invention, the winding-plated film layer can be accurately removed, and the electric leakage and parasitic absorption risks are relieved, so that the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

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

[0002] In the preparation process of a tunnel oxide passivated contact (Tunnel Oxide Passivated Contact solar cell, Topcon for short) solar cell, it is necessary to prepare polycrystalline silicon on the back side of the Topcon cell.

[0003] However, when preparing polysilicon, the front and side of the battery are prone to film wrapping. In the wrapping area, not only will serious optical parasitic absorption and surface recombination occur, but the leakage current of the battery will also increase, causing serious electrical performance losses to the battery's open circuit voltage, short circuit and battery efficiency.

[0004] Therefore, how to accurately remove the film layer that is plated, alleviate the risks of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of solar cells is an urgent problem to be solved. Summary of the invention

[0005] Based on this, the embodiments of the present application provide a solar cell and a method for preparing the same, which can accurately remove the film layer that is plated, alleviate the risks of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of the solar cell.

[0006] In order to achieve the above objectives, in a first aspect, some embodiments of the present application provide a method for preparing a solar cell, comprising the following steps:

[0007] providing a substrate;

[0008] forming a front structural layer covering the front surface of the substrate and extending to cover the upper portion of the side surface of the substrate;

[0009] forming a front oxide layer on a surface of the front structural layer facing away from the substrate;

[0010] forming a back structural layer covering the back side of the substrate and extending to cover the lower part of the side surface of the substrate;

[0011] forming a back oxide layer on the surface of the back structure layer facing away from the substrate;

[0012] A one-step laser process is used to remove the front oxide layer, the front structural layer, the back oxide layer and part of the back structural layer on the side of the substrate;

[0013] Wet chemical removal of the remaining back structure layer on the side of the substrate.

[0014] In some embodiments of the present application, wet chemical removal of the back structure layer remaining on the side of the substrate includes the following steps: using an alkali polishing process to remove the back structure layer remaining on the side of the substrate.

[0015] In some embodiments of the present application, wet chemical removal of the back structure layer remaining on the side of the substrate includes the following steps: using a texturing process to remove the back structure layer remaining on the side of the substrate.

[0016] In some embodiments of the present application, removing the front oxide layer, the front structure layer, the back oxide layer and part of the back structure layer on the side of the substrate by a one-step laser process further includes the following steps:

[0017] A portion of the front oxide layer on the front side of the substrate and a portion of the back oxide layer on the back side of the substrate are removed simultaneously.

[0018] In some embodiments of the present application, wet chemical removal of the back structure layer remaining on the side of the substrate further includes the following steps:

[0019] The remaining front oxide layer on the front side of the substrate, the remaining back oxide layer on the back side of the substrate, part of the front structural layer on the front side of the substrate, and part of the back structural layer on the back side of the substrate are removed simultaneously.

[0020] In some embodiments of the present application, the size of the removed portion of the front structural layer on the front side of the substrate along the first direction is 0.1 μm-500 μm. The size of the removed back structural layer on the back side of the substrate along the first direction is 0.1 μm-500 μm.

[0021] In some embodiments of the present application, the types of lasers used in the one-step laser process include: picosecond laser and nanosecond laser.

[0022] In some embodiments of the present application, the frequency of the laser is: 400KHz-1200KHz. The spot size of the laser is: 80μm-200μm. The energy of the laser is: 1W-10W. The scanning speed of the laser is: 3000m / s-50000m / s.

[0023] In some embodiments of the present application, the front structural layer includes: a boron-doped substrate layer, a boron-containing silicon compound layer and / or a silicon oxide layer. The back structural layer includes: a phosphorus-doped substrate layer, a phosphorus-containing silicon compound layer and / or a silicon oxide layer.

[0024] In a second aspect, some embodiments of the present application further provide a solar cell, which is prepared using the method for preparing a solar cell described in the aforementioned embodiment.

[0025] The solar cell and the method for preparing the same provided by the present application may have / at least have the following advantages:

[0026] In an embodiment of the present application, a one-step laser process is used to remove the front oxide layer, the front structural layer, the back oxide layer and part of the back structural layer on the side of the substrate. Then the back structural layer remaining on the side of the substrate is removed by wet chemistry. In this way, the embodiment of the present application accurately destroys the oxide layer and part of the structural layer on the side of the battery by utilizing the short wavelength and concentrated energy of the laser, that is, the part of the film layer coated by the silicon wafer is controllably destroyed by a one-step laser process. In this way, in combination with the wet chemical steps of subsequent battery preparation, the embodiment of the present application can achieve accurate and damage-free removal of the film layer coated, alleviate the risks of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of the solar cell. In addition, the preparation method of the embodiment of the present application is simple and highly repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of a process for preparing a solar cell provided in some embodiments of the present application;

[0029] Figure 2 A schematic flow chart of step S100 in a method for preparing a solar cell provided in some embodiments of the present application;

[0030] Figure 3 A schematic diagram of a cross-sectional structure of a structure obtained in step S200 in a method for preparing a solar cell provided in some embodiments of the present application;

[0031] Figure 4 A schematic flow chart of step S300 in a method for preparing a solar cell provided in some embodiments of the present application;

[0032] Figure 5 A schematic diagram of a cross-sectional structure of a structure obtained after a back structural material layer is formed in a method for preparing a solar cell provided in some embodiments of the present application;

[0033] Figure 6 A schematic diagram of a cross-sectional structure of a structure obtained after a back oxide material layer is formed in a method for preparing a solar cell provided in some embodiments of the present application;

[0034] Figure 7 A schematic flow chart of step S500 in a method for preparing a solar cell provided in some embodiments of the present application;

[0035] Figure 8A schematic flow chart of step S600 in a method for preparing a solar cell provided in some embodiments of the present application;

[0036] Fig. 9 A schematic flow chart of step S700 in a method for preparing a solar cell provided in some embodiments of the present application; and, Fig. 9 It is also a schematic diagram of a cross-sectional structure of a solar cell provided in some embodiments of the present application.

[0037] Description of reference numerals:

[0038] 1-substrate; 21-front structural layer; 220-back structural material layer; 22-back structural layer; 31-front oxide layer; 320-back oxide material layer; 32-back oxide layer. DETAILED DESCRIPTION

[0039] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] It should be understood that although the terms first and second can be used to describe various elements, components, regions, layers, collector structures and / or parts, these elements, components, regions, layers, collector structures and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, collector structure or part from another element, component, region, layer, collector structure or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer, collector structure or part discussed below can be represented as a second element, component, region, layer or part; for example, the first collector structure can be referred to as the second collector structure, and similarly, the second collector structure can be referred to as the first collector structure; the first collector structure and the second collector structure are different collector structures. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below other elements" or "below" or "below" will be oriented as "on" other elements or features. Thus, the exemplary terms "below" and "beneath" can encompass both an orientation of above and below. Furthermore, the device can be included in alternative orientations (eg, rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

[0042] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that when the terms "consisting of" and / or "comprising" are used in this specification, the presence of the features, integers, steps, operations, elements and / or parts can be determined, but the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups is not excluded. At the same time, when used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0043] As used herein, a "deposition" process includes, but is not limited to, physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD).

[0044] Embodiments of the invention are described herein with reference to cross-sectional views that are schematic representations of idealized embodiments (and intermediate structures) of the present application, such that variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are anticipated. Thus, embodiments of the present application should not be limited to the specific shapes of the regions shown herein, but rather include deviations in shapes due to, for example, manufacturing techniques. The regions shown in the figures are schematic in nature, and their shapes do not represent the actual shapes of the regions of the device, and do not limit the scope of the present application.

[0045] Solar cells, also known as solar chips or photovoltaic cells, can instantly output voltage and generate current in a circuit as long as they are illuminated by light that meets certain illumination conditions. In physics, this process is called solar photovoltaic, or PV for short. The main principle of solar cells is the photovoltaic effect or the photochemical effect, through which it can directly convert light energy into electrical energy.

[0046] In the preparation process of a tunnel oxide passivated contact (Tunnel Oxide Passivated Contact solar cell, Topcon for short) solar cell, it is necessary to prepare polycrystalline silicon on the back side of the Topcon cell.

[0047] However, when preparing polysilicon, the front and side of the battery are prone to film wrapping. In the wrapping area, not only will serious optical parasitic absorption and surface recombination occur, but the leakage current of the battery will also increase, causing serious electrical performance losses to the battery's open circuit voltage, short circuit and battery efficiency.

[0048] There are many methods for preparing polysilicon on the back of Topcon cells. The most common one at this stage is the low pressure chemical vapor deposition (LPCVD) process. However, the LPCVD equipment for preparing polysilicon will produce film layer wrapping. In the wrapping area, not only will serious optical parasitic absorption and surface recombination occur, but also the leakage current of the cell will be increased, causing serious electrical performance losses to the open circuit voltage, short circuit and cell efficiency of the cell.

[0049] At present, a solution to the above problem is to perform a laser treatment process on the area between the screen-printed border line on the front of the silicon wafer and the silicon wafer border after the back passivation film step and before the front passivation film step to eliminate the film layer around the edge. However, this method has the following problems: First, the high energy of the laser will cause some of the doped elements in the coating layer and the emitter layer to be further pushed into the silicon substrate, so that no matter how deep the groove is, there will still be some doped elements under the groove, so that the leakage channel still exists. Second, at present, directly destroying all film layers with laser will cause irreversible damage to the silicon substrate, and lattice defects will form on the silicon wafer under high temperature conditions, which will affect the efficiency of the solar cell. Third, using laser to directly destroy the film layer on the front of the silicon wafer can improve part of it, but there is still a coating area on the side of the cell.

[0050] Another solution is to use a de-coating reagent containing an alkali and the additive, and use a wet chemical method to de-coat silicon solar cells coated with polycrystalline silicon or amorphous silicon. However, this method uses additional additives to perform wet chemical treatment on the cell, which will introduce difficult-to-remove impurities on the surface of the silicon wafer, seriously affecting the performance of the cell. Therefore, how to accurately remove the coated film layer, alleviate the risk of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of solar cells is an urgent problem to be solved.

[0051] Based on this, the present application provides a solar cell and a method for preparing the same, which can accurately remove the film layer that is plated around, alleviate the risks of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of the solar cell.

[0052] See also Figure 1 The present application provides a method for preparing a solar cell, comprising steps S100 to S200.

[0053] S100 , providing a substrate.

[0054] S200 , forming a front structural layer that covers the front surface of the substrate and extends to cover the upper portion of the side surface of the substrate.

[0055] S300, forming a front oxide layer on a surface of the front structural layer facing away from the substrate.

[0056] S400 , forming a backside structural layer that covers the backside of the substrate and extends to cover the lower portion of the side surface of the substrate.

[0057] S500, forming a back oxide layer on a surface of the back structure layer facing away from the substrate.

[0058] S600 uses a one-step laser process to remove the front oxide layer, front structural layer, back oxide layer and part of the back structural layer on the side of the substrate.

[0059] S700, wet chemical removal of the back structure layer remaining on the side of the substrate.

[0060] In an embodiment of the present application, a one-step laser process is used to remove the front oxide layer, the front structural layer, the back oxide layer and part of the back structural layer on the side of the substrate. Then the back structural layer remaining on the side of the substrate is removed by wet chemistry. In this way, the embodiment of the present application accurately destroys the oxide layer and part of the structural layer on the side of the battery by utilizing the short wavelength and concentrated energy of the laser, that is, the part of the film layer coated by the silicon wafer is controllably destroyed by a one-step laser process. In this way, in combination with the wet chemical steps of subsequent battery preparation, the embodiment of the present application can achieve accurate and damage-free removal of the film layer coated, alleviate the risks of leakage and parasitic absorption, and thus improve the photoelectric conversion efficiency of the solar cell. In addition, the preparation method of the embodiment of the present application is simple and highly repeatable.

[0061] In some embodiments, step S600 uses a one-step laser process to remove the front oxide layer, front structural layer, back oxide layer and part of the back structural layer on the side of the substrate, and also includes the following steps: simultaneously removing part of the front oxide layer on the front side of the substrate and part of the back oxide layer on the back side of the substrate.

[0062] In some embodiments, the laser types used in the one-step laser process include: picosecond laser and nanosecond laser.

[0063] In some embodiments, the frequency of the laser is 400KHz-1200KHz, the spot size of the laser is 80μm-200μm, the energy of the laser is 1W-10W, and the scanning speed of the laser is 3000m / s-50000m / s.

[0064] In some embodiments, step S700 of wet chemically removing the remaining back structure layer on the side of the substrate also includes the following steps: simultaneously removing the remaining front oxide layer on the front side of the substrate, the remaining back oxide layer on the back side of the substrate, part of the front structure layer on the front side of the substrate, and part of the back structure layer on the back side of the substrate.

[0065] In some embodiments, the size of the removed portion of the front structural layer on the front side of the substrate along the first direction is 0.1 μm-500 μm. The size of the removed back structural layer on the back side of the substrate along the first direction is 0.1 μm-500 μm.

[0066] In some embodiments, step S700 of wet chemically removing the back structure layer remaining on the side of the substrate includes the following steps: removing the back structure layer remaining on the side of the substrate by using an alkali polishing process.

[0067] In some other embodiments, step S700 of wet chemically removing the back structure layer remaining on the side of the substrate includes the following steps: using a texturing process to remove the back structure layer remaining on the side of the substrate.

[0068] In some embodiments, the front structural layer includes: a boron-doped substrate layer, a boron-containing silicon compound layer and / or a silicon oxide layer. The back structural layer includes: a phosphorus-doped substrate layer, a phosphorus-containing silicon compound layer and / or a silicon oxide layer.

[0069] It should be noted that in the above embodiments, the execution of each step in the method is not strictly restricted in order, and these steps may not necessarily be executed in the order described, but may be executed in other ways. Moreover, at least a part of any step may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but may be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps. The method is limited to being able to achieve the preparation of the corresponding solar cell.

[0070] In order to more clearly illustrate the method for preparing the solar cell provided in the above embodiment, Figure 2~Figure 9 The preparation method is described in detail.

[0071] In step S100, refer to Figure 1 S100 and Figure 2 , providing a substrate 1.

[0072] In some embodiments, the substrate 1 has a first surface and a second surface disposed opposite to each other, the first surface of the substrate 1 may be the front surface and the second surface may be the back surface, or the first surface of the substrate 1 may be the back surface and the second surface may be the front surface.

[0073] Further, for example, the battery is a single-sided battery, the front side of the substrate 1 can be used as a light-receiving side for receiving incident light, and the back side is used as a backlight side.

[0074] In some embodiments, the substrate 1 includes a silicon wafer. In some examples, the substrate 1 is an N-type silicon wafer.

[0075] In some examples, providing the substrate 1 includes: providing a silicon wafer; polishing the surface of the silicon wafer and removing a cutting damage layer; and texturing the surface of the silicon wafer to improve light absorption.

[0076] In step S200, refer to Figure 1 S200 and Figure 3 , forming a front structure layer 21 covering the front surface of the substrate 1 and extending to cover the upper part of the side surface of the substrate 1.

[0077] In some examples, a “back-to-back” diffusion process may be used to form a front structural layer 21 that covers the front surface of the substrate 1 and extends to cover the upper portion of the side surface of the substrate 1 to prepare a PN junction.

[0078] For example, the textured substrate 1 is placed in a diffusion furnace for boron diffusion to form a front structure layer 21 on the front side of the substrate 1 .

[0079] Here, it should be particularly noted that when the substrate 1 is subjected to boron diffusion in the diffusion furnace, a boron diffusion layer is also formed on the back side of the substrate 1 . After the boron diffusion, the boron diffusion layer on the back side of the substrate 1 is removed by a polishing process or the like.

[0080] Illustratively, the boron source used for the boron diffusion is boron trichloride.

[0081] In some embodiments, the front structural layer includes: a boron-doped substrate layer, a boron-containing silicon compound layer and / or a silicon oxide layer.

[0082] By way of example, the material of the boron-doped substrate layer includes boron-doped silicon. The material of the boron-silicon compound layer includes borosilicate glass (BSG). The material of the silicon oxide layer includes silicon dioxide.

[0083] In step S300, refer to Figure 1 S300 and Figure 4 A front oxide layer 31 is formed on the surface of the front structure layer 21 facing away from the substrate 1 .

[0084] In some embodiments, the material of the front oxide layer 31 includes silicon dioxide.

[0085] In some examples, a deposition process may be used to form a front oxide layer 31 on a surface of the front structure layer 21 facing away from the substrate 1 .

[0086] In step S400, refer to Figure 1 S400 and Figure 5~Figure 7 , forming a back structure layer 22 that covers the back side of the substrate 1 and extends to cover the lower part of the side of the substrate 1.

[0087] In some embodiments, the back structure layer 22 includes: a phosphorus-doped substrate layer, a phosphorus-containing silicon compound layer and / or a silicon oxide layer.

[0088] By way of example, the material of the phosphorus-doped substrate layer includes phosphorus-doped silicon. The material of the phosphorus-silicon compound layer includes phosphorus-silicate glass (PSG). The material of the silicon oxide layer includes silicon dioxide.

[0089] For some examples, see Figure 5 , forming a back structure layer 22 covering the back side of the substrate 1 and extending to cover the lower side of the substrate 1 includes: forming a back structure material layer 220 (ie preparing a tunnel passivation structure) by "back-to-back" diffusion.

[0090] In some examples, a diffusion furnace tube may be used to perform phosphorus diffusion annealing to form the back structural material layer 220. Due to the wrap-around effect, a certain thickness of PSG will also be formed on the surface of the front and side wrap-around polysilicon layers, but the thickness of the front PSG is much smaller than that of the back PSG, and the front side is uniformly covered by the wrap-around polysilicon layer, which acts as a front mask and effectively blocks the phosphorus element from entering the front BSG during the phosphorus diffusion annealing process.

[0091] In step S500, refer to Figure 1 S500 and Figure 6 , Figure 7 A back oxide layer 32 is formed on the surface of the back structure layer 22 facing away from the substrate 1 .

[0092] In some embodiments, the material of the back oxide layer 32 includes silicon dioxide.

[0093] For some examples, see Figure 6 A deposition process may be used to form a back oxide material layer 320 on the surface of the back oxide layer 32 facing away from the substrate 1 .

[0094] For some examples, see Figure 7 A positive etching process may be used to remove the back oxide material layer 320 and the back structural material layer 220 on the front surface and part of the side surface to form the back structural layer 22 and the back oxide layer 32 .

[0095] In step S600, refer to Figure 1 S600 and Figure 8 A one-step laser process is used to remove the front oxide layer 31 , the front structure layer 21 , the back oxide layer 32 and part of the back structure layer 22 on the side of the substrate 1 .

[0096] In some embodiments, step S600 uses a one-step laser process to remove the front oxide layer, the front structural layer, the back oxide layer and part of the back structural layer on the side of the substrate, and also includes the following steps: synchronously removing part of the front oxide layer 31 on the front side of the substrate 1 and part of the back oxide layer 32 on the back side of the substrate 1.

[0097] In the embodiment of the present application, a one-step laser process is used to perform surround laser treatment on the battery precursor, which can accurately destroy its side oxide layer and part of the structural layer.

[0098] In some embodiments, the laser types used in the one-step laser process include: picosecond laser and nanosecond laser.

[0099] In some embodiments, the frequency of the laser is: 400KHz-1200KHz. For example, the frequency of the laser can be: 400KHz-500KHz, 500KHz-600KHz, 600KHz-700KHz, 700KHz-800KHz, 800KHz-900KHz, 900KHz-1000KHz, 1000KHz-1100KHz or 1100KHz-1200KHz, etc. For example, the frequency of the laser can be: 400KHz, 450KHz, 500KHz, 550KHz, 600KHz, 650KHz, 700KHz, 750KHz, 800KHz, 850KHz, 900KHz, 950KHz, 1000KHz, 1150KHz or 1200KHz, etc.

[0100] In some embodiments, the spot size of the laser is 80 μm-200 μm. For example, the spot size of the laser can be 80 μm-90 μm, 90 μm-100 μm, 100 μm-110 μm, 110 μm-120 μm, 120 μm-130 μm, 130 μm-140 μm, 140 μm-150 μm, 150 μm-160 μm, 160 μm-170 μm, 170 μm-180 μm, 180 μm-190 μm, or 190 μm-200 μm, etc. For example, the spot size of the laser can be: 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm or 200μm, etc.

[0101] In some embodiments, the energy of the laser is 1 W to 10 W. For example, the energy of the laser can be 1 W to 2 W, 2 W to 4 W, 4 W to 6 W, 6 W to 8 W, or 8 W to 10 W, etc. For example, the energy of the laser can be 1 W, 1.5 W, 2 W, 3 W, 4 W, 5 W, 6 W, 7 W, 8 W, 9 W, or 10 W.

[0102] In some embodiments, the scanning speed of the laser is: 3000m / s-50000m / s. By way of example, the scanning speed of the laser can be: 3000m / s-7000m / s, 7000m / s-11000m / s, 11000m / s-15000m / s, 15000m / s-19000m / s, 19000m / s-23000m / s, 23000m / s-27000m / s, 27000m / s-31000m / s, 31000m / s-35000m / s, 35000m / s-39000m / s, 39000m / s-43000m / s, 43000m / s-47000m / s, 47000m / s-50000m / s and so on. For example, the scanning speed of the laser can be: 3000m / s, 5000m / s, 7000m / s, 9000m / s, 11000m / s, 13000m / s, 15000m / s, 17000m / s, 19000m / s, 21000m / s, 23000m / s, 25000m / s, 27000m / s, 29000m / s, 31000m / s, 33000m / s, 35000m / s, 37000m / s, 39000m / s, 41000m / s, 43000m / s, 45000m / s, 47000m / s or 50000m / s, etc.

[0103] In step S700, refer to Figure 1 S700 and Fig. 9 The wet chemical removal of the back structure layer 22 remaining on the side of the substrate 1 also includes the following steps: synchronously removing the front oxide layer 31 remaining on the front side of the substrate 1, the back oxide layer 32 remaining on the back side of the substrate 1, part of the front structure layer 21 on the front side of the substrate 1, and part of the back structure layer 22 on the back side of the substrate 1.

[0104] In some embodiments, please refer to Fig. 9, the size d1 of the removed portion of the front structural layer 21 on the front side of the substrate 1 along the first direction (for example, the X direction) is: 0.1μm-500μm. For example, the size d1 can be: 0.1μm~5μm, 5μm~50μm, 50μm~100μm, 100μm~150μm, 150μm~200μm, 200μm~250μm, 250μm~300μm, 300μm~350μm, 350μm~400μm, 400μm~450μm or 450μm~500μm, etc. For example, the size d1 can be: 0.1μm, 2μm, 5μm, 25μm, 50μm, 75μm, 100μm, 125μm, 150μm, 175μm, 200μm, 225μm, 250μm, 275μm, 300μm, 325μm, 350μm, 375μm, 400μm, 425μm, 450μm, 475μm or 500μm, etc.

[0105] In some embodiments, the size d2 of the removed back structure layer 22 on the back side of the substrate 1 along the first direction (e.g., X direction) is: 0.1 μm-500 μm. For example, the size d2 may be: 0.1 μm-5 μm, 5 μm-50 μm, 50 μm-100 μm, 100 μm-150 μm, 150 μm-200 μm, 200 μm-250 μm, 250 μm-300 μm, 300 μm-350 μm, 350 μm-400 μm, 400 μm-450 μm, or 450 μm-500 μm, etc. For example, dimension d2 may be 0.1 μm, 2 μm, 5 μm, 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, 300 μm, 325 μm, 350 μm, 375 μm, 400 μm, 425 μm, 450 μm, 475 μm or 500 μm, etc.

[0106] In some embodiments, step S700 of wet chemically removing the back structure layer 22 remaining on the side of the substrate 1 includes the following steps: removing the back structure layer 22 remaining on the side of the substrate 1 by using an alkali polishing process.

[0107] In some examples, the alkali polishing process can use alkali polishing additives, potassium hydroxide, sodium hydroxide solution, hydrogen peroxide and other solutions to remove the back structure layer 22 remaining on the side of the substrate 1, and the alkali polishing process is followed by post-cleaning, wherein the post-cleaning solutions are hydrogen peroxide and potassium hydroxide.

[0108] In some other embodiments, step S700 of wet chemically removing the back structure layer remaining on the side of the substrate includes the following steps: using a texturing process to remove the back structure layer 22 remaining on the side of the substrate 1.

[0109] In some examples, the texturing process can use texturing additives, potassium hydroxide, sodium hydroxide solution, hydrogen peroxide and other solutions to remove the back structure layer 22 remaining on the side of the substrate 1, and post-cleaning is performed after the texturing process, wherein the post-cleaning solutions are hydrogen peroxide and potassium hydroxide.

[0110] In some embodiments, after wet chemically removing the back structure layer remaining on the side of the substrate in step S700, the process further includes: depositing a passivation film on the front and back sides of the substrate 1; forming a front electrode and a back electrode using a screen printing process; and performing a sintering process and a photo-annealing process.

[0111] Please continue reading Fig. 9 Some embodiments of the present application also provide a solar cell, which is prepared using the solar cell preparation method described in the aforementioned embodiment.

[0112] In the embodiment of the present application, the solar cell adopts the above structure. The technical effect that can be achieved by the solar cell is the same as the technical effect that can be achieved by the preparation method of the solar cell in the aforementioned embodiment, and will not be described in detail here.

[0113] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features of the above-described 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.

[0114] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: providing a substrate; forming a front structural layer covering the front surface of the substrate and extending to cover the upper part of the side surface of the substrate; forming a front oxide layer on a surface of the front structural layer facing away from the substrate; forming a back structural layer covering the back side of the substrate and extending to cover the lower part of the side surface of the substrate; forming a back oxide layer on a surface of the back structural layer facing away from the substrate; Using a one-step laser process to remove the front oxide layer, the front structural layer, the back oxide layer and part of the back structural layer on the side of the substrate; The back structure layer remaining on the side of the substrate is removed by wet chemical method.

2. The method for preparing a solar cell according to claim 1, characterized in that: The wet chemical removal of the back structure layer remaining on the side of the substrate includes: removing the back structure layer remaining on the side of the substrate by an alkali polishing process.

3. The method for preparing a solar cell according to claim 1, wherein: The wet chemical removal of the back structure layer remaining on the side of the substrate includes: using a texturing process to remove the back structure layer remaining on the side of the substrate.

4. The method for preparing a solar cell according to claim 1, wherein: The step of removing the front oxide layer, the front structure layer, the back oxide layer and part of the back structure layer on the side of the substrate by a one-step laser process further comprises: A portion of the front oxide layer on the front side of the substrate and a portion of the back oxide layer on the back side of the substrate are removed simultaneously.

5. The method for preparing a solar cell according to claim 1, wherein: The wet chemical removal of the back structure layer remaining on the side of the substrate further comprises: The front oxide layer remaining on the front side of the substrate, the back oxide layer remaining on the back side of the substrate, part of the front structural layer on the front side of the substrate, and part of the back structural layer on the back side of the substrate are removed simultaneously.

6. The method for preparing a solar cell according to claim 5, characterized in that: The size of the removed portion of the front structural layer on the front side of the substrate along the first direction is 0.1 μm-500 μm; the size of the removed portion of the back structural layer on the back side of the substrate along the first direction is 0.1 μm-500 μm.

7. The method for preparing a solar cell according to claim 1, characterized in that: The types of lasers used in the one-step laser process include: picosecond lasers and nanosecond lasers.

8. The method for preparing a solar cell according to claim 7, characterized in that: The frequency of the laser is: 400KHz-1200KHz; the spot size of the laser is: 80μm-200μm; the energy of the laser is: 1W-10W; the scanning speed of the laser is: 3000m / s-50000m / s.

9. The method for preparing a solar cell according to claim 1, wherein: The front structural layer comprises: a boron-doped substrate layer, a boron-containing silicon compound layer and / or a silicon oxide layer; The back structure layer includes: a phosphorus-doped substrate layer, a phosphorus-containing silicon compound layer and / or a silicon oxide layer.

10. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to any one of claims 1 to 9.

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