Preparation method of solar cell and solar cell

Abstract

The invention discloses a preparation method of a solar cell and the solar cell, and the preparation method comprises the steps: firstly providing an N-type silicon substrate, carrying out boron diffusion doping processing on one side of a first surface of the N-type silicon substrate, and carrying out phosphorus diffusion doping processing on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces, deviating from each other, of the N-type silicon substrate, the first surface is a suede surface, the second surface is a polished surface, then a first passive film layer is formed on the first surface, a second passive film layer is formed on the second surface, and finally a main-grid-free process is adopted. And carrying out silk-screen printing and sintering treatment on one side of the first passive film layer and / or one side of the second passive film layer to form a plurality of fine grids, and preparing the solar cell. By means of the method, the effective utilization area of the surface of the solar cell is increased, excessive occupation of the surface area of the solar cell due to arrangement of the main grid is reduced, and the effect that the whole solar cell is high in photoelectric conversion efficiency is achieved.

Description

Technical Field

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

[0002] The update and iteration of photovoltaic cell structure has led to the continuous accumulation of old production capacity, and cost reduction and efficiency improvement have become the key issues of the photovoltaic industry. Compared with P-type crystalline silicon cells, N-type crystalline silicon cells have the advantages of long minority carrier life, no photoinduced degradation, good weak light effect, and small temperature coefficient. They are the hope for crystalline silicon solar cells to break through the theoretical maximum efficiency.

[0003] At present, N-type crystalline silicon cells basically have a main grid, which mainly collects current and assists in component string welding. There are 16 main grids on the front and back sides, and the silver consumption of a single main grid on the front and back sides is about 15.4 mg. However, the more main grids there are, the higher the overall production cost of the N-type crystalline silicon cell will be. In addition, the setting of the main grid on the N-type crystalline silicon cell will also occupy the surface area of ​​the N-type crystalline silicon cell, reduce the effective utilization area of ​​the N-type crystalline silicon cell, and affect the utilization rate of solar energy and the photoelectric conversion efficiency. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a solar cell and a solar cell, which adopts a main grid-free process to increase the effective utilization area of ​​the surface of the solar cell, achieve a higher photoelectric conversion efficiency of the overall solar cell, increase the double-sided passivation and anti-ultraviolet attenuation performance of the N-type silicon substrate, so that the prepared solar cell can effectively take into account both high photoelectric conversion efficiency and high reliability.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a solar cell, comprising:

[0006] Providing an N-type silicon substrate, and performing a boron diffusion doping treatment on one side of a first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping treatment on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface;

[0007] forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface;

[0008] The solar cell is manufactured by adopting a busbar-free process, performing screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form a plurality of fine grids.

[0009] Optionally, the first passivation film layer includes an anti-ultraviolet attenuation film layer and a plurality of first anti-reflection layers; the second passivation film layer includes a second anti-reflection layer;

[0010] Forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface, comprising:

[0011] forming the anti-ultraviolet attenuation film layer on the first surface;

[0012] sequentially forming the first anti-reflection layers on a side of the anti-ultraviolet attenuation film layer away from the first surface;

[0013] The second anti-reflection layer is formed on the second surface.

[0014] Optionally, in a direction from the second surface of the N-type silicon substrate to the first surface, the refractive index of each of the first anti-reflection layers decreases sequentially.

[0015] Optionally, the overall refractive index of the plurality of first anti-reflection layers is in a range of 2.15%-2.3%; and / or the refractive index of the second anti-reflection layer is in a range of 2.2%-2.3%.

[0016] Optionally, in the direction in which the second surface of the N-type silicon substrate points to the first surface, the refractive index range of the first anti-reflection layer closest to the first surface is 2.2%-2.5%, and / or the refractive index range of the first anti-reflection layer farthest from the first surface is 1.9%-2.2%.

[0017] Optionally, the plurality of first anti-reflection layers include a first sub-anti-reflection layer, a second sub-anti-reflection layer, a third sub-anti-reflection layer, a fourth sub-anti-reflection layer and a fifth sub-anti-reflection layer;

[0018] The first anti-reflection layers are sequentially formed on a side of the anti-ultraviolet attenuation film layer away from the first surface, including:

[0019] The first sub-anti-reflection layer, the second sub-anti-reflection layer, the third sub-anti-reflection layer, the fourth sub-anti-reflection layer and the fifth sub-anti-reflection layer are sequentially formed on a side of the anti-ultraviolet attenuation film layer away from the first surface.

[0020] Optionally, the material of the first sub-anti-reflection layer includes silicon nitride; and / or, the material of the second sub-anti-reflection layer includes silicon nitride; and / or, the material of the third sub-anti-reflection layer includes silicon nitride; and / or, the material of the fourth sub-anti-reflection layer includes silicon oxynitride; and / or, the material of the fifth sub-anti-reflection layer includes silicon nitride; and / or, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide; and / or, the material of the second anti-reflection layer includes silicon nitride.

[0021] Optionally, the thickness of the anti-ultraviolet attenuation film layer is in the range of 6-10 nm.

[0022] Optionally, after performing boron diffusion doping on one side of the first surface of the N-type silicon substrate, the method further includes:

[0023] Performing oxidation degradation treatment on the N-type silicon substrate after the boron diffusion doping treatment;

[0024] And / or, after performing phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate, the method further comprises:

[0025] The N-type silicon substrate after the phosphorus diffusion doping treatment is subjected to oxidation degradation treatment.

[0026] Optionally, before performing phosphorus diffusion doping on one side of the second surface of the N-type silicon substrate, the method further includes:

[0027] A tunneling oxide layer and a polysilicon layer are sequentially formed on the second surface.

[0028] In a second aspect, an embodiment of the present invention further provides a solar cell, which is prepared by using the method for preparing a solar cell as described in any one of the first aspects.

[0029] An embodiment of the present invention provides a method for preparing a solar cell and a solar cell. The preparation method first provides an N-type silicon substrate, and performs a boron diffusion doping treatment on one side of a first surface of the N-type silicon substrate, and performs a phosphorus diffusion doping treatment on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface, and then a first passivation film layer is formed on the first surface, and a second passivation film layer is formed on the second surface, and finally a main-grid-free process is adopted to perform screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form multiple fine grids to obtain a solar cell. By utilizing the above method, a plurality of fine grids are formed on both sides of an N-type silicon substrate by adopting a main grid-free process, thereby increasing the effective utilization area of ​​the surface of the solar cell, reducing the excessive occupation of the surface area of ​​the solar cell due to the setting of the main grid, achieving the effect of higher photoelectric conversion efficiency of the overall solar cell, and effectively reducing the total consumption of silver required for the formation of the electrode structure on the surface of the N-type silicon substrate, thereby reducing the overall cost and optimizing the cost of the solar cell, thus achieving the effect of reducing cost and increasing efficiency, and improving the overall cost performance of the solar cell finally prepared, and forming a passivation film layer on both sides of the N-type silicon substrate, thereby effectively increasing the passivation and anti-ultraviolet attenuation performance of both sides of the N-type silicon substrate, so that the prepared solar cell can effectively take into account both high photoelectric conversion efficiency and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 is a schematic flow chart of a method for preparing a solar cell provided by an embodiment of the present invention;

[0032] Figure 2 It is a schematic flow chart of another method for preparing a solar cell provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0034] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", "right" and the like described in the embodiments of the present invention are described at the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not represent any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0035] The term “including” and its variations used in the present invention are open inclusions, that is, “including but not limited to.” The term “based on” means “based at least in part on.” The term “one embodiment” means “at least one embodiment.”

[0036] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or interdependence.

[0037] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0038] Figure 1 The present invention provides a schematic flow diagram of a method for preparing a solar cell. The method for preparing a solar cell can be applied to the preparation process of the surface electrode structure of a solar cell. The method for preparing a solar cell can be used to prepare a solar cell. Figure 1 As shown, the preparation method comprises:

[0039] S110, providing an N-type silicon substrate, and performing a boron diffusion doping treatment on one side of a first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping treatment on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface.

[0040] Specifically, an N-type silicon substrate is provided, and the N-type silicon substrate includes a first surface and a second surface that are separated from each other. Exemplarily, the first surface can be understood as the front side of the N-type silicon substrate, and the second surface can be understood as the back side of the N-type silicon substrate. Exemplarily, the first surface and the second surface of the N-type silicon substrate can be rectangular in shape, the long side length of the rectangle can be 183.75 mm, and the short side length of the rectangle can be 182.2 mm.

[0041] The first surface of the N-type silicon substrate is a velvet surface. Exemplarily, the first surface of the N-type silicon substrate can be subjected to a velvet treatment so that the first surface of the N-type silicon substrate is a velvet surface. Exemplarily, the velvet surface is a pyramid structure when tested under a microscope. Optionally, the reflectivity of the velvet surface of the first surface ranges from 8% to 9%. Exemplarily, the reflectivity of the velvet surface of the first surface can be 8.95%. The velvet treatment can remove organic dirt and metal impurities on the surface of the N-type silicon substrate, remove the mechanical damage layer generated by the wire cutting process of the N-type silicon substrate, reduce the recombination center, and form an undulating velvet surface, so as to utilize the light trapping effect, increase the absorption rate of the N-type silicon substrate to sunlight, reduce the reflectivity, and increase the surface area of ​​the N-type silicon substrate, thereby also increasing the PN junction area formed on the surface. Exemplarily, the velvet treatment can use a mixed solution of 28L of concentrated potassium hydroxide (KOH) solution, 10L of velvet additive, and 480L of pure water. The velvet treatment time can be 300s, and the velvet treatment temperature can be 75°C.

[0042] After the first surface of the N-type silicon substrate is textured, a boron diffusion doping treatment may be performed on one side of the first surface of the N-type silicon substrate to form a PN junction on the first surface of the N-type silicon substrate. The junction formation process is to generate semiconductor layers of different conductivity types on a piece of semiconductor substrate material. For example, the square resistance after the boron diffusion doping treatment is 280Ω / sq, and the junction depth of ECV (electrochemical differential capacitance voltage) is 0.785μm.

[0043] After the first surface of the N-type silicon substrate is subjected to boron diffusion doping treatment, the second surface of the N-type silicon substrate can be subjected to chain pickling and alkali polishing treatment to ensure that the second surface of the N-type silicon substrate is a polished surface, so that the N-type silicon substrate forms a polished surface with high reflectivity, thereby improving the flatness of the battery surface, and increasing the reflection of long-wave light to promote the secondary absorption of light, increase the short-circuit current and reduce the leakage current. Exemplarily, the chain pickling treatment can use a mixed solution of 1.2% hydrochloric acid (HCl) solution and 1.2% hydrofluoric acid (HF) solution. Exemplarily, the alkali polishing treatment can use a mixed solution of 22L concentrated potassium hydroxide (KOH) solution, 10L additive (BP56), and 470L pure water, the alkali polishing treatment time can be 295s, and the alkali polishing treatment temperature can be 68°C.

[0044] After the first surface side of the N-type silicon substrate is subjected to boron diffusion doping treatment, the second surface side of the N-type silicon substrate can be further subjected to phosphorus diffusion doping treatment to form a PN junction on the second surface of the N-type silicon substrate. The junction making process is to generate semiconductor layers with different conductivity types on a piece of semiconductor substrate material. Exemplarily, the square resistance after the boron diffusion doping treatment is 42Ω / sq, and the junction depth of the ECV is 1.08μm. It can be understood that this embodiment only describes the example of first performing boron diffusion doping treatment on the first surface side of the N-type silicon substrate, and then performing phosphorus diffusion doping treatment on the second surface side of the N-type silicon substrate. In fact, the second surface side of the N-type silicon substrate can also be subjected to phosphorus diffusion doping treatment, and then the first surface side of the N-type silicon substrate can be subjected to boron diffusion doping treatment, and the first surface side of the N-type silicon substrate can be subjected to boron diffusion doping treatment and the second surface side of the N-type silicon substrate can be subjected to phosphorus diffusion doping treatment at the same time, without specific limitation.

[0045] In addition, after the second surface side of the N-type silicon substrate is subjected to phosphorus diffusion doping treatment, the second surface of the N-type silicon substrate can be subjected to chain pickling and etching treatment to ensure that the second surface of the N-type silicon substrate is clean and free of impurities. Exemplarily, the chain pickling treatment can use a mixed solution of 1.2% hydrochloric acid (HCl) solution and 1.0% hydrofluoric acid (HF) solution. The etching treatment can use a mixed solution of 26L concentrated potassium hydroxide (KOH) solution, 8L additive (BP62), and 460L pure water, the etching treatment time can be 285s, and the etching treatment temperature can be 62°C.

[0046] S120 , forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface.

[0047] Specifically, a passivation film layer can be formed on the first surface and the second surface of the N-type silicon substrate by using processes such as atomic layer deposition (ALD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and coating. It can be understood that the first passivation film layer and the second passivation film layer have passivation and anti-ultraviolet attenuation properties, which can effectively prevent the entire solar cell from being affected by ultraviolet and infrared, and further ensure the operational reliability of the entire solar cell.

[0048] S130, using a busbar-free process, performing screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form a plurality of fine grids, thereby manufacturing a solar cell.

[0049] Specifically, screen printing is one of the core processes in the manufacturing process of solar cells, and is mainly used for electrode formation of solar cells. This process uses the basic principle that the mesh holes of the graphic part of the screen are transparent to the slurry, while the mesh holes of the non-graphic part are not transparent to the slurry for printing. During the printing process, the slurry is accurately squeezed onto the N-type silicon substrate through the mesh holes of the screen, and the slurry is evenly distributed on the surface of the solar cell in the form of a wire to form the required electrode pattern. Generally, the slurry for screen printing may include but is not limited to silver paste. The pattern formed by screen printing includes metal grid lines. High-temperature sintering is used to treat the electrode material screen-printed on the surface of the cell at high temperature, dry the slurry on the N-type silicon substrate, burn out the organic components of the slurry, and the slurry can corrode through the passivation film layer and connect to the PN junction, so that the metal grid line forms a good ohmic contact with the N-type silicon substrate, so as to achieve the purpose of collecting and conducting current. It should be noted that the present embodiment adopts a busbar-free process to form multiple fine grids (without forming a busbar) on both sides of the N-type silicon substrate, thereby increasing the effective utilization area of ​​the surface of the solar cell, reducing the excessive occupation of the surface area of ​​the solar cell due to the setting of the busbar, and achieving a higher photoelectric conversion efficiency of the overall solar cell. Exemplarily, the screen-printed paste corresponding to the busbar-free process can be an aluminum-free silver paste.

[0050] Furthermore, the solar cell after the screen printing process is sintered at a temperature of 748°C and then subjected to a light injection process. For example, the temperature of the light injection process may be 538°C and the light intensity may be 5500W / m 2The laser induced process after light injection can induce silver-silicon interdiffusion, thereby significantly reducing contact resistance, increasing the fill factor of the battery, and effectively improving the efficiency of the battery cell. For example, the laser power of the laser induced process can be 16W, and the reverse voltage applied to the battery terminal can be 15V.

[0051] It should also be noted that the solar cell prepared in this embodiment has been subjected to relevant experiments, and it can be concluded that the open circuit voltage value of the solar cell in the IV (current-voltage characteristic curve) test is 0.7418V, the short circuit current value is 14.016A, the filling is 85.55%, and the photoelectric conversion efficiency is as high as 26.706%. After that, the solar cell is subjected to UV (ultraviolet light) test in a UV box with UV irradiance of 170W / m 2 , UVB accounts for 5.6% and the cumulative irradiance is 60kW / m 2 After that, the UV60 on-voltage attenuation value of the photoelectric conversion efficiency of the solar cell is 1.58%, which is much lower than the UV60 on-voltage attenuation value of 4.28% of the comparison group (N-type crystalline silicon cells containing main grid, etc.).

[0052] The technical solution in the embodiment of the present invention is that the preparation method first provides an N-type silicon substrate, and performs boron diffusion doping treatment on one side of the first surface of the N-type silicon substrate, and performs phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface, and then a first passivation film layer is formed on the first surface, and a second passivation film layer is formed on the second surface, and finally a main-grid-free process is adopted to perform screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form multiple fine grids to obtain a solar cell. By utilizing the above method, a plurality of fine grids are formed on both sides of an N-type silicon substrate by adopting a main grid-free process, thereby increasing the effective utilization area of ​​the surface of the solar cell, reducing the excessive occupation of the surface area of ​​the solar cell due to the setting of the main grid, achieving the effect of higher photoelectric conversion efficiency of the overall solar cell, and effectively reducing the total consumption of silver required for the formation of the electrode structure on the surface of the N-type silicon substrate, thereby reducing the overall cost and optimizing the cost of the solar cell, thus achieving the effect of reducing cost and increasing efficiency, and improving the overall cost performance of the solar cell finally prepared, and forming a passivation film layer on both sides of the N-type silicon substrate, thereby effectively increasing the passivation and anti-ultraviolet attenuation performance of both sides of the N-type silicon substrate, so that the prepared solar cell can effectively take into account both high photoelectric conversion efficiency and high reliability.

[0053] Optionally, after performing boron diffusion doping treatment on one side of the first surface of the N-type silicon substrate, the method further includes: performing oxidation degradation treatment on the N-type silicon substrate after the boron diffusion doping treatment; and / or, after performing phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate, the method further includes: performing oxidation degradation treatment on the N-type silicon substrate after the phosphorus diffusion doping treatment.

[0054] Specifically, the oxidation degradation treatment can play a role in high-temperature promotion, redistributing the diffused boron or phosphorus, making the boron diffusion on the first surface of the N-type silicon substrate more uniform, and the phosphorus diffusion on the second surface of the N-type silicon substrate more uniform, which is similar to making an oxide layer, playing a protective role. For example, the square resistance after oxidation degradation treatment is 220Ω / sq, and the junction depth of ECV is 0.88μm.

[0055] Optionally, before performing phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate, the method further includes: sequentially forming a tunneling oxide layer and a polysilicon layer on the second surface.

[0056] Specifically, the tunneling oxide layer and the polysilicon layer are used to allow the majority carriers (electrons) to pass smoothly through the tunneling effect, while preventing the recombination of minority carriers (holes), so as to achieve selective collection of carriers, reduce surface recombination, and increase the open circuit voltage and fill factor of the battery, thereby improving the photoelectric conversion efficiency of the overall solar cell. The composite layer of the tunneling oxide layer and the polysilicon layer together forms a passivation contact structure, which can effectively reduce the surface recombination and metal contact recombination of the overall solar cell. In other words, depositing an ultra-thin tunneling oxide layer on the second surface of the N-type silicon substrate can provide good interface passivation and provide different carrier tunneling barriers. Depositing a polysilicon layer on the tunneling oxide layer can increase the migration rate of electrons while suppressing the migration rate of holes. In addition, the polysilicon layer contacts the subsequent metal electrode and acts as an electron transmission bridge. For example, low pressure chemical vapor deposition (LPCVD) technology can be used to first prepare an ultra-thin silicon dioxide layer on the second surface of the N-type silicon substrate as the above-mentioned tunneling oxide layer, and then deposit a polycrystalline silicon thin layer on the ultra-thin silicon dioxide layer to form a polycrystalline silicon layer that meets the passivation effect.

[0057] Figure 2 1 is a flow chart of another method for preparing a solar cell provided by an embodiment of the present invention. This embodiment is optimized on the basis of the above embodiment. Optionally, the first passivation film layer includes an anti-ultraviolet attenuation film layer and a plurality of first anti-reflection layers; the second passivation film layer includes a second anti-reflection layer;

[0058] Forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface, comprising:

[0059] forming an anti-ultraviolet attenuation film layer on the first surface;

[0060] Forming first anti-reflection layers in sequence on a side of the anti-ultraviolet attenuation film layer away from the first surface;

[0061] A second anti-reflection layer is formed on the second surface.

[0062] For details not yet provided in this embodiment, please refer to the above embodiments. Figure 2 As shown, the preparation method comprises:

[0063] S210, providing an N-type silicon substrate, and performing a boron diffusion doping treatment on one side of a first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping treatment on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface.

[0064] S220, forming an anti-ultraviolet attenuation film layer on the first surface.

[0065] Specifically, the first passivation film layer includes an anti-ultraviolet attenuation film layer and a plurality of first anti-reflection layers. Exemplarily, an anti-ultraviolet attenuation film layer can be formed on the first surface of the N-type silicon substrate by using atomic layer deposition (ALD) technology and a water process. Exemplarily, the temperature of the ALD process can be 200-300°C and the deposition time can be 8-10min. The deposition can be cyclically deposited 20 times under the conditions of a TMA flow rate of 1500sccm, an oxygen flow rate of 1800sccm, and a temperature of 278°C, and the deposition time can be 6min. Optionally, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide. It should be noted that the water process uses water vapor to react with trimethylaluminum to prepare a dense aluminum oxide layer, and effectively increases the thickness of aluminum oxide. Optionally, the thickness of the anti-ultraviolet attenuation film layer ranges from 6-10nm. Exemplarily, the thickness of the anti-ultraviolet attenuation film layer can be 8nm, which can effectively play the role of anti-ultraviolet attenuation and passivation of the front side of the N-type silicon substrate. It can be understood that, in this embodiment, by reasonably increasing the thickness of the anti-ultraviolet attenuation film layer, the anti-ultraviolet capability of the entire solar cell is effectively increased.

[0066] S230, forming first anti-reflection layers in sequence on a side of the anti-ultraviolet attenuation film layer away from the first surface.

[0067] Specifically, a coating process and a high refractive index process can be used to sequentially form each first anti-reflection layer on the side of the anti-ultraviolet attenuation film layer away from the first surface. Each first anti-reflection layer can further improve the passivation and anti-ultraviolet attenuation performance of the overall solar cell, and can also reduce the reflection of sunlight, increase the absorption of sunlight, and improve the photoelectric conversion efficiency of the overall solar cell. At the same time, it reduces surface recombination, increases the mobility of carriers, and improves the overall performance of the overall solar cell. Optionally, the overall refractive index range of the multiple first anti-reflection layers is 2.15%-2.3%. This embodiment effectively increases the anti-ultraviolet ability of the overall solar cell by reasonably increasing the overall refractive index of the multiple first anti-reflection layers. In addition, this embodiment does not make specific requirements and special limitations on the refractive index, thickness, number, etc. of each first anti-reflection layer, and can be designed according to actual needs.

[0068] In a specific embodiment, optionally, in the direction from the second surface of the N-type silicon substrate to the first surface, the refractive index of each first anti-reflection layer decreases in sequence. Further, in the direction from the second surface of the N-type silicon substrate to the first surface, the refractive index of the first anti-reflection layer closest to the first surface is in the range of 2.2%-2.5%, and / or the refractive index of the first anti-reflection layer farthest from the first surface is in the range of 1.9%-2.2%.

[0069] In other words, the refractive index value of the first anti-reflection layer closest to the first surface is the largest, and the refractive index value of the first anti-reflection layer farthest from the first surface is the smallest. Specifically, by reasonably designing the anti-reflection layer with a gradient refractive index, the anti-ultraviolet ability of the overall solar cell can be further improved, the reflection of sunlight can be reduced, the absorption of sunlight can be increased, and the photoelectric conversion efficiency of the overall solar cell can be improved.

[0070] In a specific embodiment, optionally, the plurality of first anti-reflection layers include a first sub-anti-reflection layer, a second sub-anti-reflection layer, a third sub-anti-reflection layer, a fourth sub-anti-reflection layer, and a fifth sub-anti-reflection layer; each first anti-reflection layer is sequentially formed on the side of the anti-ultraviolet attenuation film layer away from the first surface, including: sequentially forming the first sub-anti-reflection layer, the second sub-anti-reflection layer, the third sub-anti-reflection layer, the fourth sub-anti-reflection layer, and the fifth sub-anti-reflection layer on the side of the anti-ultraviolet attenuation film layer away from the first surface. Optionally, the material of the first sub-anti-reflection layer includes silicon nitride; and / or, the material of the second sub-anti-reflection layer includes silicon nitride; and / or, the material of the third sub-anti-reflection layer includes silicon nitride; and / or, the material of the fourth sub-anti-reflection layer includes silicon oxynitride; and / or, the material of the fifth sub-anti-reflection layer includes silicon nitride; and / or, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide; and / or, the material of the second anti-reflection layer includes silicon nitride.

[0071] Specifically, on the side of the anti-ultraviolet attenuation film layer away from the first surface, three silicon nitride layers with gradually decreasing refractive index are first formed in sequence, and then a silicon nitride oxide layer is formed, and finally a silicon nitride layer with the smallest refractive index is formed on the side of the silicon nitride oxide layer away from the first surface. In this way, on the side of the anti-ultraviolet attenuation film layer away from the first surface, both the refractive index change of the film layer and the material of the film layer are designed, which can further improve the utilization rate of sunlight and the absorption amount of sunlight of the subsequently prepared solar cell, and improve the photoelectric conversion efficiency of the subsequently prepared solar cell.

[0072] S240, forming a second anti-reflection layer on the second surface.

[0073] Specifically, the second passivation film layer includes a second anti-reflection layer. A second anti-reflection layer can be formed on the second surface of the N-type silicon substrate by using a coating process and a high refractive index process. The second anti-reflection layer can further enhance the passivation and anti-ultraviolet attenuation performance of the overall solar cell. Optionally, the material of the second anti-reflection layer includes silicon nitride. Optionally, the refractive index of the second anti-reflection layer ranges from 2.2% to 2.3%. This embodiment effectively increases the anti-ultraviolet capability of the overall solar cell by reasonably increasing the refractive index of the second anti-reflection layer.

[0074] S250, using a busbar-free process, performing screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form a plurality of fine grids, thereby manufacturing a solar cell.

[0075] Based on the same inventive concept, an embodiment of the present invention further provides a solar cell. The solar cell is prepared by a method for preparing a solar cell provided in any one of the embodiments of the present invention. Therefore, the solar cell has functional modules and beneficial effects corresponding to the method for preparing a solar cell.

[0076] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: Providing an N-type silicon substrate, and performing a boron diffusion doping treatment on one side of a first surface of the N-type silicon substrate, and performing a phosphorus diffusion doping treatment on one side of a second surface of the N-type silicon substrate; wherein the first surface and the second surface are two surfaces of the N-type silicon substrate that are opposite to each other, and the first surface is a velvet surface, and the second surface is a polished surface; forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface; The solar cell is manufactured by adopting a busbar-free process, performing screen printing and sintering treatment on one side of the first passivation film layer and / or one side of the second passivation film layer to form a plurality of fine grids.

2. The preparation method according to claim 1, characterized in that: The first passivation film layer includes an anti-ultraviolet attenuation film layer and a plurality of first anti-reflection layers; the second passivation film layer includes a second anti-reflection layer; Forming a first passivation film layer on the first surface, and forming a second passivation film layer on the second surface, comprising: forming the anti-ultraviolet attenuation film layer on the first surface; sequentially forming the first anti-reflection layers on a side of the anti-ultraviolet attenuation film layer away from the first surface; The second anti-reflection layer is formed on the second surface.

3. The preparation method according to claim 2, characterized in that: In a direction from the second surface of the N-type silicon substrate to the first surface, the refractive index of each of the first anti-reflection layers decreases sequentially.

4. The preparation method according to claim 3, characterized in that: The overall refractive index of the first anti-reflection layers is in a range of 2.15% to 2.3%; and / or the refractive index of the second anti-reflection layers is in a range of 2.2% to 2.3%.

5. The preparation method according to claim 3, characterized in that: In the direction from the second surface of the N-type silicon substrate to the first surface, the refractive index range of the first anti-reflection layer closest to the first surface is 2.2%-2.5%, and / or the refractive index range of the first anti-reflection layer farthest from the first surface is 1.9%-2.2%.

6. The preparation method according to claim 2, characterized in that: The plurality of first anti-reflection layers include a first sub-anti-reflection layer, a second sub-anti-reflection layer, a third sub-anti-reflection layer, a fourth sub-anti-reflection layer and a fifth sub-anti-reflection layer; The first anti-reflection layers are sequentially formed on a side of the anti-ultraviolet attenuation film layer away from the first surface, including: The first sub-anti-reflection layer, the second sub-anti-reflection layer, the third sub-anti-reflection layer, the fourth sub-anti-reflection layer and the fifth sub-anti-reflection layer are sequentially formed on a side of the anti-ultraviolet attenuation film layer away from the first surface.

7. The preparation method according to claim 6, characterized in that: The material of the first sub-anti-reflection layer includes silicon nitride; and / or, the material of the second sub-anti-reflection layer includes silicon nitride; and / or, the material of the third sub-anti-reflection layer includes silicon nitride; and / or, the material of the fourth sub-anti-reflection layer includes silicon oxynitride; and / or, the material of the fifth sub-anti-reflection layer includes silicon nitride; and / or, the material of the anti-ultraviolet attenuation film layer includes aluminum oxide; and / or, the material of the second anti-reflection layer includes silicon nitride.

8. The preparation method according to claim 2, characterized in that: The thickness of the anti-ultraviolet attenuation film layer is in the range of 6-10 nm.

9. The preparation method according to claim 1, characterized in that: After performing boron diffusion doping on one side of the first surface of the N-type silicon substrate, the method further includes: Performing oxidation degradation treatment on the N-type silicon substrate after the boron diffusion doping treatment; And / or, after performing phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate, the method further comprises: The N-type silicon substrate after the phosphorus diffusion doping treatment is subjected to oxidation degradation treatment.

10. The preparation method according to claim 1, characterized in that: Before performing phosphorus diffusion doping treatment on one side of the second surface of the N-type silicon substrate, the method further includes: A tunneling oxide layer and a polysilicon layer are sequentially formed on the second surface.

11. 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 10.

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