Micro-textured surface preparation method of silicon wafer, silicon wafer solar cell and photovoltaic module

Abstract

The embodiment of the invention provides a micro-textured surface preparation method of a silicon wafer, a silicon wafer solar cell and a photovoltaic module. The preparation method of the micro textured surface of the silicon wafer comprises the following steps: providing the silicon wafer with a textured surface; putting the silicon wafer into a hydrogen peroxide solution so as to carry out first treatment on the textured surface of the silicon wafer; putting the silicon wafer after the first treatment into a first alkaline solution so as to etch the textured surface; and taking out the silicon wafer under the condition that the etching time reaches a preset time range to obtain the silicon wafer with the micro textured surface. According to the technical scheme provided by the embodiment of the invention, the silicon wafer after the first treatment is put into the first alkaline solution, and incomplete etching is carried out, so that the silicon wafer with the micro-textured surface is prepared. The step of polishing the textured surface before manufacturing the micro textured surface is avoided, the requirement for the thickness of the silicon wafer is lowered, and the speed of manufacturing the micro textured surface is increased.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a method for preparing a micro-texture surface of a silicon wafer, a silicon crystal solar cell and a photovoltaic module. Background Art

[0002] By preparing a micro-texture surface on the surface of a silicon wafer, the contact resistance inside the battery can be reduced, thereby improving the conversion efficiency of solar cells in many aspects.

[0003] In the prior art, for preparing micro-texture on a single crystal silicon wafer, the surface of the silicon wafer is usually corroded by an alkaline solution, and the silicon wafer is polished to remove the damaged layer on the surface of the silicon wafer; then the silicon wafer is etched or halogenated on the surface of the polished silicon wafer to obtain the micro-texture. This preparation process must be polished, the process is complicated, and the processing efficiency is not high. Summary of the invention

[0004] The embodiments of the present application provide a method for preparing a micro-texture surface of a silicon wafer, a silicon crystalline solar cell, and a photovoltaic module to solve or alleviate one or more technical problems in the prior art.

[0005] As a first aspect of an embodiment of the present application, an embodiment of the present application provides a method for preparing a micro-texture surface of a silicon wafer, comprising: Providing a silicon wafer having a textured surface; placing the silicon wafer in a hydrogen peroxide solution to perform a first treatment on the velvet surface of the silicon wafer; placing the first processed silicon wafer into a first alkaline solution to etch the texture surface; When the etching time reaches a predetermined time range, the silicon wafer is taken out to obtain a silicon wafer with a micro-textured surface.

[0006] In one embodiment, the volume concentration of the hydrogen peroxide solution is 5%-15%, and the temperature is 40°C-60°C.

[0007] In one embodiment, the temperature of the hydrogen peroxide solution is 45°C-55°C.

[0008] In one embodiment, the first alkaline solution includes: a NaOH or KOH solution with a volume concentration of 1%-10%.

[0009] In one embodiment, the method further comprises: placing the silicon wafer having a micro-texture surface into a second alkaline solution to remove residues on the surface of the silicon wafer.

[0010] In one embodiment, the second alkaline solution comprises a KOH or NaOH solution having a volume concentration of 0.6%-10%; In the second alkaline solution, the volume concentration of the KOH or NaOH solution is less than the volume concentration of the KOH or NaOH solution in the first alkaline solution.

[0011] In one embodiment, the first treatment includes: increasing the surface hydrophilicity of the silicon wafer; Accordingly, the preparation method further includes: placing the silicon wafer with a micro-suede surface into a hydrofluoric acid solution to increase the surface hydrophobicity of the silicon wafer; the volume concentration of the hydrofluoric acid solution is 10%-15%, and the temperature is 20°C to 30°C.

[0012] In one embodiment, the silicon wafer with a velvet surface is a double-sided velvet surface silicon wafer, including a first velvet surface and a second velvet surface; the first velvet surface is a side to be prepared into a micro-velvet surface, and the second velvet surface is a side to retain the velvet surface; The silicon wafer is placed in a hydrogen peroxide solution to perform a first treatment on the textured surface of the silicon wafer, including: Setting a mask for the second velvet surface to protect the second velvet surface; The silicon wafer provided with the mask is placed in a hydrogen peroxide solution to perform a first treatment on the second textured surface of the silicon wafer.

[0013] In one embodiment, a silicon wafer with a textured surface is provided, wherein the silicon wafer is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer.

[0014] As a second aspect of the embodiments of the present application, the embodiments of the present application further provide a silicon crystalline solar cell, comprising a silicon wafer, at least one side of the silicon wafer having a micro-texture surface, and the silicon wafer is prepared by the preparation method of any implementation aspect of the above embodiments.

[0015] As a third aspect of the embodiments of the present application, the embodiments of the present application further provide a photovoltaic module, comprising at least one battery string, wherein the battery string comprises at least two silicon crystalline solar cells as described above.

[0016] The embodiment of the present application adopts the above technical solution, and places the silicon wafer after the first treatment into the first alkaline solution for incomplete etching to obtain a silicon wafer with a micro-texture surface. This avoids the step of polishing the suede surface before making the micro-texture surface, reduces the requirement for the thickness of the silicon wafer, and improves the speed and efficiency of making the micro-texture surface. The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present application will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 A schematic flow chart of a method for preparing a micro-texture surface of a silicon wafer according to an embodiment of the present application is shown.

[0019] Figure 2 Another schematic flow chart of a method for preparing a micro-texture surface of a silicon wafer according to an embodiment of the present application is shown.

[0020] Figure 3 The schematic diagram of the structure of the silicon crystalline solar cell manufactured according to multiple embodiments and comparative examples of the present application is shown.

[0021] Figures 4 to 6 The micro-texture effect diagram of the silicon crystal substrate prepared according to Examples 1 to 3 of the present application is shown.

[0022] Figure 7 The micro-texture effect diagram of the silicon crystal substrate prepared according to Comparative Example 1 of the present application is shown. DETAILED DESCRIPTION

[0023] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present application. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0024] The embodiment of the present application provides a method for preparing a micro-texture surface of a silicon wafer, which is used to prepare a micro-texture surface on a silicon wafer.

[0025] In solar silicon cells, it is often necessary to prepare a velvet surface on the surface of the silicon wafer so that a pyramid structure is formed on the surface of the silicon wafer to produce a light trapping effect, increase the silicon wafer's absorption of sunlight, reduce the light reflectivity of the silicon wafer surface, increase the short-circuit current Isc, and maximize the use of light for conversion into electrical energy.

[0026] In the further development of solar silicon crystalline cells, in order to reduce the optical loss caused by the reflection of light on the backlight side of the silicon wafer, the backlight side of the silicon wafer is set to a polished surface.

[0027] Furthermore, in order to reduce optical loss and lower the contact resistance inside the battery, the backlight side of the silicon wafer is made into a micro-texture surface.

[0028] Figure 1FIG. 1 is a schematic diagram showing a process of preparing a micro-texture surface of a silicon wafer according to an embodiment of the present application. Figure 1 As shown, the preparation method comprises: S210 , providing a silicon wafer having a textured surface.

[0029] The silicon wafer with a velvet surface refers to a silicon wafer obtained by cleaning and velveting the initial silicon wafer. The cleaning and velveting process can remove stains on the surface of the initial silicon wafer and form small and uniform pyramids on the surface of the initial silicon wafer, forming an undulating velvet surface.

[0030] The micro-texture preparation in the embodiment of the present application can be carried out on a silicon wafer on which the texture has been formed.

[0031] If an initial silicon wafer without texturing is provided, the initial silicon wafer can be cleaned and texturing-treated first, and then the micro-texture surface preparation step can be performed.

[0032] The initial silicon wafer may be cleaned and texturized using various technical solutions known to ordinary technicians in the field now and in the future, which will not be described in detail here.

[0033] S220, placing the silicon wafer in a hydrogen peroxide solution to perform a first treatment on the textured surface of the silicon wafer.

[0034] Hydrogen peroxide solution is an aqueous solution containing hydrogen peroxide (H2O2).

[0035] Placing the silicon wafer in a hydrogen peroxide solution can increase the hydrophilicity of the silicon wafer surface, that is, increase the hydrophilicity of the suede surface.

[0036] Placing the silicon wafer in a hydrogen peroxide solution can also clean away impurities on the surface of the silicon wafer.

[0037] S230, placing the first processed silicon wafer into a first alkaline solution to etch the texture surface.

[0038] The crystalline silicon wafer will undergo anisotropic reaction in an alkaline solution within a certain concentration range, causing the surface of the silicon wafer to be etched. After the surface of the crystalline silicon wafer is etched, the polished surface can be etched into a velvet surface, or the velvet surface can be etched into a polished surface.

[0039] The first alkaline solution may be any alkaline solution that has an etching effect on the surface of the silicon wafer, such as an inorganic etching solution such as a KOH solution, a NaOH solution, a Na2SiO3 solution or a Na3PO4 solution; or an organic etching solution such as EPW (ethylenediamine, phthalic acid and water) or TMAH (tetramethylammonium hydroxide).

[0040] S240, when the etching time reaches a predetermined time range, taking out the silicon wafer to obtain a silicon wafer with a micro-textured surface.

[0041] The predetermined time range may be set by performing multiple experimental tests on silicon wafers.

[0042] The predetermined time range can be the time to obtain an ideal micro-suede effect based on the test results. Micro-suede can be understood as a state between suede and polished surface. The ideal micro-suede effect can be determined by observing the water hanging effect, that is, by observing the water hanging on the surface of the silicon wafer when the silicon wafer is taken out from the first alkaline solution. If the surface of the silicon wafer is completely polished, it will not hang water droplets; if the surface of the silicon wafer has suede, it will hang water droplets. However, after hanging water on the suede and micro-suede silicon wafer surfaces, the angles at which water droplets fall out will be different. Therefore, through multiple experimental tests, based on the observed water hanging effect, it is determined how long the etching should take to achieve the ideal micro-suede effect.

[0043] Based on the time determined by the test result, the time threshold required for etching to obtain an ideal micro-suede effect, that is, a predetermined time range, is determined.

[0044] In one example, the predetermined time range may be 1 min-4 min.

[0045] In one example, when the predetermined time range is 1 min-4 min, the precise etching time can be determined based on the actual situation. For example, if a sparse micro-texture surface is desired, the etching time can be extended as much as possible, that is, the silicon wafer can be taken out after etching for 3 min, 3.5 min or nearly 4 min.

[0046] In an embodiment of the present application, a silicon wafer with a velvet surface is first placed in a hydrogen peroxide solution for a first treatment. The temperature of the hydrogen peroxide solution can be lower than the temperature of the first alkaline solution. At this temperature, the velvet surface of the silicon wafer is first treated, such as increasing the surface hydrophilicity of the silicon wafer. The silicon wafer after the first treatment is then placed in a first alkaline solution, which is a process of etching the velvet surface to a polished surface, but the etching is incomplete, thereby obtaining a silicon wafer with a micro-velvet surface. This avoids the step of polishing the velvet surface before making the micro-velvet surface, reduces the requirements for the thickness of the silicon wafer, and increases the speed of making the micro-velvet surface. In one embodiment, the volume concentration of the hydrogen peroxide solution is 5%-15%, and the temperature is 40°C-60°C.

[0047] In the embodiment of the present application, the hydrophilicity of the surface of the silicon wafer is increased by placing the silicon wafer in a hydrogen peroxide solution, so that the surface of the silicon wafer can better react with the first alkaline solution.

[0048] In one embodiment, the temperature of the hydrogen peroxide solution is 45°C-55°C.

[0049] The temperature of the hydrogen peroxide solution is relative to the temperature of the alkaline solution used for alkaline etching of silicon wafers.

[0050] The temperature of the hydrogen peroxide solution is 45°C-55°C, for example, 50°C, which can better improve the hydrophilicity of the silicon wafer surface, or take a shorter time to obtain the same hydrophilic effect compared to an environment with a higher temperature.

[0051] The time for the silicon wafer to be subjected to the first treatment in the hydrogen peroxide solution may be 1 min to 3 min.

[0052] In one example, the time for the silicon wafer to be subjected to the first treatment in the hydrogen peroxide solution may be longer than 1 minute or longer than a specified time.

[0053] In the embodiment of the present application, by first placing the silicon wafer in a hydrogen peroxide solution for complete hydrophilic treatment and then etching, a better etching effect can be obtained, and since there is no initial polishing step, the surface of the silicon wafer can more conveniently obtain a micro-suede structure that partially retains the suede.

[0054] In one embodiment, the first alkaline solution includes: a NaOH or KOH solution with a volume concentration of 1%-10%.

[0055] The first alkaline solution is used to etch the surface of the silicon wafer, and its volume concentration needs to reach a concentration that can be etched. NaOH or KOH solution is an exemplary solution used for alkaline washing.

[0056] The volume concentration of the NaOH or KOH solution can be 4%-10%, for example, 4%, 4.5%, 4.9%, 5%, 5.6%, 6%, 7%, 8%, 9% or 10%. By using a first alkaline solution with a higher volume concentration, the etching speed can be increased to improve the preparation efficiency of the micro-texture surface.

[0057] In one example, the first alkaline solution may further include additives, such as isopropyl alcohol, (NH4)2S2O4, N2H4·H2O, etc., to optimize the etching effect. The volume concentration of the additive may be 1% to 10%. In actual application, it may be set according to the situation.

[0058] In one example, the temperature of the first alkaline solution is 50-70° C., such as 60° C., 65° C. or 70° C. In order to achieve the effect of etching the texture of the silicon wafer, the temperature of the first alkaline solution is relatively high, such as higher than that of the hydrogen peroxide solution.

[0059] In one embodiment, Figure 2As shown, the preparation method also includes: S250, placing the silicon wafer with the micro-texture surface into a second alkaline solution to remove residues on the surface of the silicon wafer.

[0060] Since the silicon wafer is currently in a hydrophilic state, alkaline water is used to clean the surface of the silicon wafer to remove the residues on the surface of the silicon wafer, including residual additives or residual metal ions.

[0061] In one embodiment, the second alkaline solution comprises a KOH or NaOH solution with a volume concentration of 0.6%-10%; in the second alkaline solution, the volume concentration of the KOH or NaOH solution is less than the volume concentration of the KOH or NaOH solution in the first alkaline solution.

[0062] Since the second alkaline solution does not need to produce an etching effect, its volume concentration can be relatively small.

[0063] The volume concentration of the NaOH or KOH solution can be 0.6%-3%, for example, 0.6%, 1.5%, 1.9%, 2%, 2.6%, 2.8% or 3%. By using the second alkaline solution with a lower volume concentration, the effect of cleaning the residue on the surface of the silicon wafer can be achieved without damaging the surface of the silicon wafer.

[0064] In the second alkaline solution, the volume concentration of KOH or NaOH solution is less than that of KOH or NaOH solution in the first alkaline solution, so as to prevent the second alkaline solution from further etching the surface of the silicon wafer and affecting the required micro-texture structure.

[0065] The temperature of the second alkaline solution may be 55° C.-70° C., for example, 55° C., 58° C. or 65° C. The temperature of the second alkaline solution may be lower than the temperature of the first alkaline solution.

[0066] In one embodiment, the first treatment includes: increasing the surface hydrophilicity of the silicon wafer; accordingly, Figure 2 As shown, the preparation method also includes: S260, placing the silicon wafer with a micro-suede surface into a hydrofluoric acid solution to increase the surface hydrophobicity of the silicon wafer; the volume concentration of the hydrofluoric acid solution is 10%-15%, and the temperature is 20°C to 30°C.

[0067] Since the current silicon wafer surface still has strong hydrophilicity, it is necessary to change its hydrophilicity so that the silicon wafer can transfer electrons / holes with other mold layers. Therefore, the silicon wafer with a micro-suede surface is placed in a hydrofluoric acid solution to increase the surface hydrophobicity of the silicon wafer.

[0068] In the embodiment of the present application, the hydrofluoric acid solution can also be replaced by various technical solutions for increasing the surface hydrophobicity of silicon wafers known to ordinary technicians in this field now and in the future.

[0069] In one embodiment, the preparation method further includes: S270, washing the silicon wafer with the micro-texture surface in ion water, and drying the washed silicon wafer.

[0070] Through the processing in step S270, the silicon wafer with a micro-texture surface can be used for the preparation of solar silicon crystal cells.

[0071] In one embodiment, the silicon wafer with a velvet surface is a double-sided velvet surface silicon wafer, including a first velvet surface and a second velvet surface; the first velvet surface is the side to be prepared into a micro-velvet surface, and the second velvet surface is the side to retain the velvet surface.

[0072] Step S220 includes: Setting a mask for the second velvet surface to protect the second velvet surface; The silicon wafer provided with the mask is placed in a hydrogen peroxide solution to perform a first treatment on the second textured surface of the silicon wafer.

[0073] In solar silicon cells, one side of the silicon wafer is velvet, and the other side is a micro-velvet structure. The velvet surface can increase the silicon wafer's absorption of sunlight, reduce the light reflectivity of the silicon wafer surface, increase the short-circuit current Isc, and maximize the use of light to convert into electrical energy. The micro-velvet surface can further reduce optical losses, while reducing the contact resistance inside the battery and improving the photoelectric conversion efficiency.

[0074] In order to realize single-sided texturing of a silicon wafer, a mask is set to perform the micro-texture preparation method of any implementation mode of the above-mentioned embodiment only on the side where the micro-texture surface is to be prepared.

[0075] In one embodiment, a silicon wafer with a textured surface is provided, wherein the silicon wafer is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer. The silicon wafer is a single crystal silicon wafer, which can be an N-type single crystal silicon wafer or a P-type single crystal silicon wafer.

[0076] The embodiment of the present application further provides a silicon crystalline solar cell, comprising a silicon wafer, at least one side of the silicon wafer having a micro-texture surface, and the silicon wafer is manufactured by the manufacturing method of any of the above-mentioned embodiments.

[0077] Silicon crystalline solar cells refer to solar cells that use silicon as the base material.

[0078] The following specific examples are provided to further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0079] The silicon wafers prepared in the following multiple examples or comparative examples were used as silicon substrates to prepare silicon crystalline solar cells, and multiple relevant parameters of the prepared silicon crystalline solar cells were tested. Figure 3 As shown, the specific structure of the silicon crystal solar cell is: the front glass 1, the front EVA film layer 2, the silicon crystal substrate 3, the back EVA film layer 4, the back glass 5 are stacked in sequence, and the electrode lead 8 is led out from the back of the silicon crystal substrate 3, and the first water-blocking material 6 and the second water-blocking material 7 are used to prevent water vapor from penetrating.

[0080] The silicon crystal substrate 3 is manufactured by using the following multiple embodiments or comparative examples.

[0081] [Example 1] The specific preparation process of silicon crystal substrate is as follows: S210, providing a silicon wafer with a textured surface. The silicon wafer is an N-type single crystal silicon wafer.

[0082] S220, placing the silicon wafer in a hydrogen peroxide solution to perform a first treatment on the textured surface of the silicon wafer.

[0083] Before placing the silicon wafer in the hydrogen peroxide solution, a mask is set for one of the velvet surfaces (the second velvet surface) of the silicon wafer to protect the second velvet surface. The volume concentration of the hydrogen peroxide solution is 8%; the temperature is 55°C.

[0084] S230, placing the first processed silicon wafer into a first alkaline solution to etch the texture surface.

[0085] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 6%; and the temperature is 65°C.

[0086] The first alkaline solution also includes an isopropyl alcohol additive solution to optimize the etching effect. The volume concentration of the isopropyl alcohol additive solution is 3%.

[0087] S240, after etching in the first alkaline solution for 3 minutes, taking out the silicon wafer to obtain a silicon wafer with a micro-textured surface.

[0088] S250, placing the silicon wafer obtained in step S240 into a second alkaline solution to remove residues on the surface of the silicon wafer for 3 minutes.

[0089] The second alkaline solution has a volume concentration of 1.4% NaOH solution and a temperature of 60°C.

[0090] S260, placing the silicon wafer treated in step S250 into a hydrofluoric acid solution to increase the surface hydrophobicity of the silicon wafer; the volume concentration of the hydrofluoric acid solution is 13%, and the temperature is room temperature (26°C).

[0091] S270, taking out the mask from the silicon wafer processed in step S260, putting the silicon wafer with one side of the velvet surface and the other side of the micro-velvet surface into ionized water for cleaning, and drying the cleaned silicon wafer to obtain a silicon crystal substrate.

[0092] [Example 2] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 9%; the temperature is 48°C.

[0093] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 4.5%, and the temperature is 65°C.

[0094] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 5%. Etching in the first alkaline solution for 2 minutes.

[0095] The second alkaline solution has a volume concentration of 3% NaOH solution and a temperature of 65° C. The volume concentration of the hydrofluoric acid solution is 15%.

[0096] [Example 3] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of hydrogen peroxide solution is 6%; the temperature is 51°C.

[0097] The first alkaline solution is a KOH solution; the volume concentration of the KOH solution is 1%, and the temperature is 68°C.

[0098] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 6%. Etching in the first alkaline solution is 3.5 minutes.

[0099] The volume concentration of the second alkaline solution is 0.6% NaOH solution, and the temperature is 58° C. The volume concentration of the hydrofluoric acid solution is 12%.

[0100] [Example 4] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 15%; the temperature is 53°C.

[0101] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 9% and the temperature is 55°C.

[0102] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 8%. Etching in the first alkaline solution for 4 minutes.

[0103] The volume concentration of the second alkaline solution is 2% KOH solution, and the temperature is 58° C. The volume concentration of the hydrofluoric acid solution is 11%.

[0104] [Example 5] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 10%; the temperature is 55°C.

[0105] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 5.6%, and the temperature is 58°C.

[0106] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 7%. Etching in the first alkaline solution for 1 minute.

[0107] The second alkaline solution has a volume concentration of 3.3% NaOH solution and a temperature of 55° C. The volume concentration of the hydrofluoric acid solution is 15%.

[0108] [Example 6] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of hydrogen peroxide solution is 5%; the temperature is 45°C.

[0109] The first alkaline solution is a KOH solution; the volume concentration of the KOH solution is 8%, and the temperature is 67°C.

[0110] The first alkaline solution also includes an isopropyl alcohol additive to optimize the etching effect. The volume concentration of the isopropyl alcohol additive solution is 3%.

[0111] The second alkaline solution has a volume concentration of 1.4% NaOH solution and a temperature of 59°C.

[0112] [Example 7] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 9%; the temperature is 52°C.

[0113] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 6%, and the temperature is 70°C.

[0114] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 5%. Etching in the first alkaline solution is 3.5 minutes.

[0115] The second alkaline solution has a volume concentration of 3% KOH solution and a temperature of 50° C. The volume concentration of the hydrofluoric acid solution is 15%.

[0116] [Example 8] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 16%; the temperature is 45°C.

[0117] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 7%, and the temperature is 60°C.

[0118] The first alkaline solution also includes an isopropyl alcohol additive to optimize the etching effect. Without the additive, etching in the first alkaline solution was performed for 4 minutes.

[0119] The volume concentration of the second alkaline solution is 1.5% NaOH solution, and the temperature is 65° C. The volume concentration of the hydrofluoric acid solution is 12%.

[0120] [Example 9] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: The volume concentration of the hydrogen peroxide solution is 15%; the temperature is 48°C.

[0121] The first alkaline solution is a KOH solution; the volume concentration of the KOH solution is 10%, and the temperature is 65°C.

[0122] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 7%. Etching in the first alkaline solution for 1 minute.

[0123] The second alkaline solution has a volume concentration of 3% NaOH solution and a temperature of 58° C. The volume concentration of the hydrofluoric acid solution is 11%.

[0124] [Example 10] A silicon crystal substrate was prepared by referring to the preparation method of Example 1, except that: Silicon wafer tail P-type single crystal silicon wafer.

[0125] The volume concentration of hydrogen peroxide solution is 10%; the temperature is 51°C.

[0126] The first alkaline solution is a NaOH solution; the volume concentration of the NaOH solution is 5%, and the temperature is 50°C.

[0127] The first alkaline solution also includes an isopropanol additive to optimize the etching effect. The volume concentration of the isopropanol additive solution is 7%. Etching in the first alkaline solution for 4 minutes.

[0128] The volume concentration of the second alkaline solution is 0.7% KOH solution, and the temperature is 58° C. The volume concentration of the hydrofluoric acid solution is 10%.

[0129] [Comparative Example 1] The specific preparation process of silicon crystal substrate is as follows: D1, providing a silicon wafer with a velvet surface. The silicon wafer is an N-type single crystal silicon wafer.

[0130] D2, a mask is set for one of the velvet surfaces (second velvet surface) of the silicon wafer to protect the second velvet surface. The silicon wafer is placed in a mixed solution of hydrogen peroxide and alkali to perform initial polishing on the velvet surface of the silicon wafer.

[0131] In the mixed solution, the volume concentration of hydrogen peroxide solution is 12%; the alkali is NaOH solution with a volume concentration of 6%; the temperature is 68° C. The silicon wafer is placed in the mixed solution for 3 minutes.

[0132] D3, placing the silicon wafer after the first treatment into a first alkaline solution to etch the texture surface.

[0133] The first alkaline solution is a NaOH solution with a volume concentration of 8% and a temperature of 69° C. The first alkaline solution also includes an isopropanol additive with a volume concentration of 11%.

[0134] D4, etching in the first alkaline solution to achieve a polishing effect. Take out the silicon wafer to obtain a polished silicon wafer. The etching time of the silicon wafer in the first alkaline solution is 4 minutes.

[0135] D5, placing the polished silicon wafer in step D4 into a second alkaline solution to etch the polished surface to obtain a silicon wafer with a micro-texture surface. The second alkaline solution has a volume concentration of 9% KOH solution and a temperature of 58° C. The etching time is 4 minutes.

[0136] D6, placing the silicon wafer obtained in step D5 into a third alkaline solution to remove residues on the surface of the silicon wafer. The third alkaline solution is a 4% NaOH solution at a temperature of 55°C.

[0137] D7, placing the silicon wafer obtained in step D6 into a hydrofluoric acid solution having a volume concentration of 10% and a temperature of room temperature.

[0138] D8, washing the silicon wafer obtained in step D7 in ionized water, and drying the washed silicon wafer.

[0139] The silicon wafers prepared in the above examples and comparative examples were used as silicon crystal substrates to prepare Figure 3 The silicon crystalline solar cells shown are used to obtain the silicon crystalline solar cells corresponding to Examples 1-10 and Comparative Example 1 of the present application.

[0140] The following is a performance test of the silicon crystalline solar cells provided in Examples 1-10 of the present application and Comparative Example 1, so as to obtain the open circuit voltage Voc, short circuit current density Jsc, fill factor FF, and photoelectric conversion efficiency PCE of the corresponding battery devices. The test results are shown in Table 1.

[0141] Table 1 Performance test results of silicon crystalline solar cells of Examples 1-10 and Comparative Example 1

[0142] It can be seen from the data in Table 1 that the short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of the corresponding cell devices of the silicon crystalline solar cells of Examples 1-10 of the present application are not much different from those of the silicon crystalline solar cell of Comparative 1. On this basis, the time for preparing the silicon crystalline substrate with a micro-texture surface in Examples 1-10 of the present application is shorter, thereby improving the preparation efficiency.

[0143] In addition, the present application also provides schematic diagrams of the micro-texture effects of the silicon crystal substrates prepared in Examples 1 to 3 and Comparative Example 1. Figures 4 to 6 As shown, the micro-texture effect of the silicon crystal substrate provided in Comparative Example 1 is shown in FIG. Figure 7 As shown. Figures 4 to 7 By comparison, it can be seen that the micro-fleece prepared by the method for preparing the micro-fleece provided in the embodiment of the present application has at least equivalent effect to the micro-fleece prepared in Comparative Example 1 (existing method).

[0144] The embodiment of the present application further provides a photovoltaic assembly, comprising at least one battery string, wherein the battery string is formed by welding the silicon crystalline solar cells according to any of the above embodiments in series.

[0145] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0146] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0147] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0148] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0149] The disclosure above provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numerals and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0150] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a micro-texture surface of a silicon wafer, characterized in that: include: Providing a silicon wafer having a textured surface; placing the silicon wafer in a hydrogen peroxide solution to perform a first treatment on the velvet surface of the silicon wafer; placing the silicon wafer after the first treatment into a first alkaline solution to etch the texture surface; When the etching time reaches a predetermined time range, the silicon wafer is taken out to obtain a silicon wafer with a micro-texture surface.

2. The preparation method according to claim 1, characterized in that: The volume concentration of the hydrogen peroxide solution is 5%-15%, and the temperature is 40°C-60°C.

3. The preparation method according to claim 2, characterized in that: The temperature of the hydrogen peroxide solution is 45°C-55°C.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The first alkaline solution includes: a NaOH or KOH solution with a volume concentration of 1%-10%.

5. The preparation method according to claim 4, characterized in that: Also includes: The silicon wafer with the micro-texture surface is placed in a second alkaline solution to remove residues on the surface of the silicon wafer.

6. The preparation method according to claim 5, characterized in that: The second alkaline solution comprises a KOH or NaOH solution with a volume concentration of 0.6%-10%; In the second alkaline solution, the volume concentration of the KOH or NaOH solution is less than the volume concentration of the KOH or NaOH solution in the first alkaline solution.

7. The preparation method according to any one of claims 1 to 3, characterized in that: The first treatment includes: increasing the surface hydrophilicity of the silicon wafer; Correspondingly, the preparation method further includes: placing the silicon wafer with a micro-texture surface into a hydrofluoric acid solution to increase the surface hydrophobicity of the silicon wafer; the volume concentration of the hydrofluoric acid solution is 10%-15%, and the temperature is 20°C to 30°C.

8. The preparation method according to claim 1, characterized in that: The silicon wafer with a velvet surface is a double-sided velvet surface silicon wafer, including a first velvet surface and a second velvet surface; the first velvet surface is the side to be prepared into a micro-velvet surface, and the second velvet surface is the side to retain the velvet surface; The step of placing the silicon wafer in a hydrogen peroxide solution to perform a first treatment on the velvet surface of the silicon wafer comprises: Setting a mask for the second velvet surface to protect the second velvet surface; The silicon wafer provided with the mask is placed in a hydrogen peroxide solution to perform a first treatment on the second textured surface of the silicon wafer.

9. The preparation method according to claim 1, characterized in that: In the silicon wafer with a textured surface, the silicon wafer is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer.

10. A silicon crystalline solar cell, characterized in that: It comprises a silicon wafer, at least one side of which has a micro-suede surface, and the silicon wafer is prepared by the preparation method according to any one of claims 1 to 9.

11. A photovoltaic module, characterized in that: The invention comprises at least one battery string, wherein the battery string comprises at least two silicon crystalline solar cells as claimed in claim 10.

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