Monocrystalline silicon wafer, textured surface preparation method of monocrystalline silicon wafer and solar cell

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a monocrystalline silicon wafer, a textured surface preparation method of the monocrystalline silicon wafer and a solar cell. The monocrystalline silicon wafer comprises two opposite surfaces, wherein at least one of the two surfaces is provided with a suede structure; the suede structure comprises a plurality of pyramid-like structures, and each pyramid-like structure comprises at least one cone top, at least four side edges and at least four side surfaces; squamous texture structures are distributed on part of the side surfaces; the angular texture structures are arranged along part of the side edges and extend from the side edges to the two side faces connected with the side edges. According to the monocrystalline silicon wafer provided by the invention, the plurality of pyramid-like structures are used as the textured structures on at least one surface, so that the sunlight reflectivity can be reduced, and the photoelectric conversion efficiency of a solar cell can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaics, and in particular relates to a single crystal silicon wafer, a method for preparing a textured surface of a single crystal silicon wafer, and a solar cell. Background Art

[0002] In the production process of monocrystalline silicon solar cells, texturing is an essential and important step. Monocrystalline silicon texturing is to texturize the surface of a single silicon wafer. The most commonly used method is alkaline etching, which forms a dense and smooth velvet pyramid structure on the surface of the monocrystalline silicon wafer. However, the smooth velvet pyramid structure has a high reflectivity and cannot fully utilize sunlight, resulting in a low photoelectric conversion efficiency of the solar cell. Summary of the invention

[0003] The present invention provides a single crystal silicon wafer, a method for preparing a textured surface of a single crystal silicon wafer and a solar cell, aiming to solve the problem of high reflectivity of a pyramid structure formed on the surface of the single crystal silicon wafer.

[0004] The present invention provides a single crystal silicon wafer, comprising: two opposite surfaces, at least one of the two surfaces having a velvet structure;

[0005] The velvet structure includes: a plurality of pyramid-like structures, each of which includes at least one pyramid top, at least four side edges and at least four side faces; a portion of the side faces is provided with a scaly texture structure; a plurality of angular texture structures are arranged along a portion of the side edges and extend from the side edges to two side faces connected to the side edges.

[0006] The present invention provides a method for preparing a textured surface of a single crystal silicon wafer, which is used to prepare the single crystal silicon wafer as described above, comprising:

[0007] Using a first texturing liquid to perform etching treatment on at least one surface of the single crystal silicon wafer to form a pyramid structure on the at least one surface to obtain a texturing single crystal silicon wafer;

[0008] The single crystal silicon wafer after the texturing is cleaned with deionized water to obtain a single crystal silicon wafer after the primary cleaning;

[0009] Using a second texturing liquid to perform texturing on the single crystal silicon wafer after the initial cleaning to obtain a single crystal silicon wafer after texturing;

[0010] The first texturing liquid includes a first alkaline solution and a first additive, the volume ratio of the first alkaline solution is 1%-5%, and the volume percentage of the first additive is 0.1%-2%; the second texturing liquid includes at least a second alkaline solution, and the volume ratio of the second alkaline solution is 0.1%-3%.

[0011] In some embodiments, the temperature for the corrosion treatment is 50°C-90°C, and the time for the corrosion treatment is 300s-1200s; the temperature for the suede modification is 20°C-50°C, and the time for the suede modification is 200s-800s.

[0012] In some embodiments, the second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 1%.

[0013] In some embodiments, the first additive comprises: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water;

[0014] The composition of the second additive is the same as that of the first additive.

[0015] In some embodiments, when the volume ratio of the first alkaline solution is 2%-3.5%, the volume percentage of the first additive is 0.5%-1%, and the volume ratio of the second alkaline solution is 0.2%-0.5%.

[0016] In some embodiments, the temperature for the corrosion treatment is 70°C-85°C, the time for the corrosion treatment is 400s-800s, the temperature for the suede modification is 25°C-35°C, and the time for the suede modification is 250s-450s.

[0017] In some embodiments, the second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 0.3%.

[0018] In some embodiments, after obtaining the textured single crystal silicon wafer, the method further comprises:

[0019] The textured single crystal silicon wafer is cleaned with deionized water and a mixed solution in sequence to obtain a second-cleaned single crystal silicon wafer, wherein the mixed solution comprises alkali and hydrogen peroxide;

[0020] The single crystal silicon wafer after the secondary cleaning is subjected to a hydrophobic treatment to obtain a treated single crystal silicon wafer.

[0021] The present invention also provides a solar cell, comprising: the above-mentioned single crystal silicon wafer.

[0022] The single crystal silicon wafer, the method for preparing the texture of a single crystal silicon wafer and the solar cell provided by the present invention use several types of pyramid structures as the texture structure on at least one surface of the single crystal silicon wafer. Since the side surfaces of the several types of pyramid structures are distributed with scaly texture structures or the side edges are distributed with angular texture structures, the reflectivity of sunlight can be reduced, the light absorption can be increased, and the photoelectric conversion efficiency of the solar cell can be finally improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is one of the schematic diagrams of the texture surface obtained by the method for preparing the texture surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0024] Figure 2 This is the second schematic diagram of the textured surface obtained by the method for preparing the textured surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0025] Figure 3 This is the third schematic diagram of the texture surface obtained by the method for preparing the texture surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0026] Figure 4 This is the fourth schematic diagram of the texture surface obtained by the method for preparing the texture surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0027] Figure 5 This is the fifth schematic diagram of the texture surface obtained by the method for preparing the texture surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0028] Figure 6 This is one of the schematic flow diagrams of the method for preparing the textured surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0029] Figure 7 This is a second schematic flow chart of a method for preparing a textured surface of a single crystal silicon wafer provided in an embodiment of the present invention;

[0030] Figure 8 It is a schematic diagram of the suede reflectivity of the solar cell provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] Combine the following Figure 1-Figure 8 The invention describes a single crystal silicon wafer, a method for preparing a textured surface of a single crystal silicon wafer, and a solar cell.

[0033] An embodiment of the present invention provides a single crystal silicon wafer, comprising: two opposite surfaces, at least one of the two surfaces having a velvet structure;

[0034] The velvet structure includes: a plurality of pyramid-like structures, the pyramid-like structures include at least one cone top, at least four side edges and at least four side faces; a scaly texture structure is distributed on some side faces; a plurality of angular texture structures are arranged along some side edges and extend from the side edges to the two side faces connected by the side edges.

[0035] It should be noted that the monocrystalline silicon wafer has two opposite surfaces, including a first surface and a second surface. In the monocrystalline silicon wafer of this embodiment, the first surface and the second surface may have the same or different velvet structures, or the first surface has a velvet structure and the second surface is a polished surface, or the first surface is a polished surface and the second surface has a velvet structure. Either of the two surfaces can be used as the front or back of the solar cell, which is not specifically limited here.

[0036] like Figures 1 to 4 As shown, the velvet structure includes several pyramid-like structures.

[0037] Several different types of pyramid-like structures are described below:

[0038] 1. When there is one apex, the pyramid-like structure includes at least 4 side edges and at least 4 side faces. For example, the pyramid-like structure may have 1 apex, 4 side edges and 4 side faces, or 1 apex, 5 side edges and 5 side faces, or 1 apex, 6 side edges and 6 side faces, etc. In this case, the number of side edges is the same as the number of side faces.

[0039] 2. When there are N apexes, the pyramid-like structure includes 4N side edges and 4N side surfaces, where N is greater than 1 and is a positive integer. This type of pyramid-like structure is a plurality of pyramid-like structures that share a common bottom surface. At this time, the apex heights corresponding to the plurality of pyramid-like structures may be the same or different, and the side edge lengths corresponding to the plurality of pyramid-like structures may be the same or different, which are not specifically limited here. It should be noted that one end of some side edges may overlap at a certain height from the bottom surface and the other ends of the side edges extend to the corresponding apex.

[0040] like Figure 1 and Figure 2 As shown, from the cross section of the pyramid-like structure, it can be seen that the side of the pyramid-like structure has different degrees of concave-convex structures. Angular texture structures are distributed on some side edges and the two side surfaces connected by the side edges, for example, triangular textures of different sizes. The angular texture structure can extend from the side edge to the two side surfaces connected by the side edge, and multiple texture structures are arranged along the side edge. The texture structures can be arranged flat or in layers, which is not specifically limited here.

[0041] like Figure 3As shown, from the cross-section of the pyramid-like structure, it can be seen that the pyramid-like structure has multiple cone tops and shares a tower base, and the heights of the cone tops are also different. From the irregular inclined edges in the pyramid-like structure, it can be seen that the side surface is a non-smooth structure, that is, there are protruding structures and concave structures.

[0042] like Figure 4 As shown, from the top view of the pyramid-like structure, it can be seen that the inclined surfaces of the pyramid-like structure are all non-smooth. Some sides are distributed with scaly texture structures, some scaly textures present various irregular shapes, and some scaly textures present flake-like arrangements, which have a certain sense of hierarchy as a whole.

[0043] Optionally, the shape of the scale-like texture may be circular or elliptical, may be a polygon such as a triangle, a quadrilateral or a hexagon, or may be an irregular polygon, which is not specifically limited here.

[0044] Optionally, the arrangement of the scale texture can be overlapping, tiling or staggered. Overlapping means that the scale texture is stacked layer by layer, tiling means that the scale texture is closely arranged but not overlapped to form a flat surface, and staggered means that the scale texture is staggered at a specific angle and order.

[0045] Some side edges have angular texture structures, which extend from the side edges to both sides. Figure 4 The texture structure on the middle side edge appears as right angles arranged in sequence.

[0046] like Figure 5 As shown, from the top view of the pyramid-like structure, it can be seen that the side surfaces of the pyramid-like structure are all non-smooth in shape. Similarly, scaly texture structures are distributed on some side surfaces, and angular texture structures are arranged on some side edges. Figure 5 The texture structure of the pyramid-like surface is relative to Figure 4 It will be less, mainly because the texturing reaction process is different, among which the difference in reaction time, temperature or concentration of reaction solution leads to certain difference in texture structure.

[0047] The single crystal silicon wafer provided in the embodiment of the present invention uses several types of pyramid structures as the velvet structure on at least one surface. Since the sides of the several types of pyramid structures are distributed with scaly texture structures or the side edges are distributed with angular texture structures, the reflectivity of sunlight can be reduced and the light absorption can be increased, and ultimately the photoelectric conversion efficiency of the solar cell can be improved.

[0048] Figure 6 This is one of the flow diagrams of the method for preparing the textured surface of a single crystal silicon wafer provided in an embodiment of the present invention.

[0049] Reference Figure 6 The method for preparing the textured surface of a single crystal silicon wafer provided by the present invention comprises:

[0050] Step 110: using a first texturing liquid to perform etching treatment on at least one surface of the single crystal silicon wafer to form a pyramid structure on at least one surface to obtain a texturing single crystal silicon wafer;

[0051] The first texturing solution includes a first alkaline solution and a first additive. The volume ratio of the first alkaline solution is 1%-5%, and the volume percentage of the first additive is 0.1%-2%.

[0052] In this step, the first texturing liquid is prepared according to the volume ratio of 1%-5% of the first alkaline solution and the volume percentage of 0.1%-2% of the first additive. That is, the ratio of the total volume of the first alkaline solution to the total volume of the first texturing liquid should be in the range of 1%-5%, and the percentage of the volume of the first additive to the total volume of the first texturing liquid should be in the range of 0.1%-2%.

[0053] Then the single crystal silicon wafer is placed in the first texturing solution for preliminary alkali texturing to obtain the texturized single crystal silicon wafer. The initial textured surface of the single crystal silicon wafer after texturing is a dense and smooth pyramid structure.

[0054] The first texturing solution at least includes a first alkaline solution, and the first alkaline solution includes but is not limited to one or more strong alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH).

[0055] In some embodiments, the first additive comprises: a surfactant, a natural polysaccharide compound, a dispersant, an emulsifier, a nucleating agent, a chelating agent, a naphthalenesulfonate formaldehyde condensate, an inorganic base, a silicon reaction catalyst and water.

[0056] It is understandable that different types of the first additive will result in the first alkaline solution having specific reaction rates to different crystal planes of the single crystal silicon wafer. The type of the first additive can be selected according to demand and is not specifically limited here.

[0057] In some embodiments, the temperature for the etching treatment is 50° C.-90° C., and the time for the etching treatment is 300 s-1200 s.

[0058] In actual implementation, temperature is an important factor affecting the rate of chemical reactions. In the alkali texturing process, increasing the temperature can accelerate the reaction between the alkali and the silicon wafer and shorten the reaction time. However, too high a temperature may cause the reaction to be too violent, difficult to control, or even damage the surface of the silicon wafer. Therefore, it is necessary to select a suitable temperature to ensure the stability of the texture quality while ensuring the reaction rate.

[0059] Time determines the depth of surface corrosion of the single crystal silicon wafer and the degree of formation of the velvet structure. If the time is too short, sufficient velvet structure may not be formed, affecting the optoelectronic performance. If the time is too long, it may cause excessive corrosion on the surface of the silicon wafer, reducing its mechanical strength and optoelectronic performance.

[0060] Therefore, it is necessary to accurately control the reaction time according to the volume ratio of the first alkaline solution, the volume percentage of the first additive, the temperature and other conditions to obtain an ideal velvet structure.

[0061] In actual implementation, the temperature of the corrosion treatment in step 110 can be set to 50° C.-90° C., and the time of the corrosion treatment can be set to 300 s-1200 s.

[0062] In the embodiment of the present invention, a long reaction time helps the first alkaline solution to etch a special shape on the surface of the pyramid.

[0063] Step 120: Use deionized water to clean the texturized single crystal silicon wafer to obtain a single crystal silicon wafer after initial cleaning.

[0064] In this step, the texturing process may leave chemical solution residues on the surface of the single crystal silicon wafer. Therefore, using deionized water for cleaning can help remove these residues, because deionized water has a lower ion content and can effectively reduce ion contamination.

[0065] Step 130, using a second texturing liquid to perform texturing on the single crystal silicon wafer after the initial cleaning to obtain a single crystal silicon wafer after texturing;

[0066] The second texturing solution at least includes a second alkaline solution, and the volume ratio of the second alkaline solution is 0.1%-3%.

[0067] In this step, the second texturing liquid is prepared according to the second alkaline solution with a volume ratio of 0.1%-3%, that is, the ratio of the total volume of the second alkaline solution to the total volume of the entire second texturing liquid should be in the range of 0.1%-3%.

[0068] The second texturing solution at least includes a second alkaline solution, and the second alkaline solution includes but is not limited to one or more strong alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH).

[0069] Then the single crystal silicon wafer after the initial cleaning is placed in the second texturing solution for etching again to perform texturing modification and obtain a single crystal silicon wafer after texturing modification. The surface of the single crystal silicon wafer after texturing modification forms a pyramid texturing structure with uneven slopes.

[0070] In some embodiments, the second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 1%.

[0071] It is understandable that appropriate additives can optimize the uniformity and microstructure of the suede surface and improve the photoelectric performance. Therefore, the second additive may not be added during the suede surface modification, or the second additive may be added, that is, the volume percentage of the second additive is within the range of 0%-1%, which can be selected according to actual needs and is not specifically limited here.

[0072] The main components of the second additive include but are not limited to: surfactants, natural polysaccharide compounds, dispersants, emulsifiers, nucleating agents, chelating agents, naphthalenesulfonate formaldehyde condensates, inorganic bases, silicon reaction catalysts and water.

[0073] The composition of the second additive may be the same as or different from the composition of the first additive.

[0074] In some embodiments, the temperature for performing suede modification is 20° C.-50° C., and the time for performing suede modification is 200 s-800 s.

[0075] In actual implementation, the texture of the pyramid structure on the surface of the single crystal silicon wafer after the initial cleaning is modified. When the volume ratio of the second alkaline solution is 0.1%-3%, the temperature during the texture modification can be set to 20°C-50°C, and the time during the texture modification can be set to 200s-800s.

[0076] It should be noted that the uneven slope formed on the surface of the single crystal silicon wafer after velvet modification refers to the pyramid slope having concave and convex parts, that is, it is in a non-smooth state.

[0077] Figure 7 This is the second schematic flow chart of the method for preparing the textured surface of a single crystal silicon wafer provided in an embodiment of the present invention.

[0078] Reference Figure 7 After obtaining the single crystal silicon after suede modification, the method further comprises:

[0079] Step 140, using deionized water and a mixed solution to clean the textured single crystal silicon wafer in sequence to obtain a second-cleaned single crystal silicon wafer, wherein the components of the mixed solution are alkali and hydrogen peroxide;

[0080] In this step, the textured monocrystalline silicon wafer is sequentially cleaned with deionized water and a mixed solution to further remove chemical solution residues. The alkali in the mixed solution can remove particulate impurities, metal ions and silicon powder residues on the surface of the monocrystalline silicon wafer, and the hydrogen peroxide can remove organic residues on the surface of the monocrystalline silicon wafer.

[0081] Optionally, in this step, deionized water is used for cleaning first. Deionized water is water produced by ion exchange, reverse osmosis and other processes, and has very low conductivity and contains almost no ions and other impurities, so it can effectively remove impurities such as soluble salts and metal ions on the surface of the single crystal silicon wafer.

[0082] Then, a mixed solution is used for cleaning, and the components of the mixed solution are alkali and hydrogen peroxide. Alkali (such as sodium hydroxide or potassium hydroxide) can react with grease and organic matter on the surface of the single crystal silicon wafer, converting them into soluble substances; hydrogen peroxide has strong oxidizing properties, which can further oxidize and decompose these organic matter, and at the same time work synergistically with the alkali to improve the cleaning effect. In addition, hydrogen peroxide can also react with metal ions on the surface of the single crystal silicon wafer to generate insoluble hydroxide precipitates, thereby removing metal ion contamination.

[0083] Step 150 , performing hydrophobic treatment on the single crystal silicon wafer after the secondary cleaning to obtain a treated single crystal silicon wafer.

[0084] After the secondary cleaning, the surface of the single crystal silicon wafer obtained after the secondary cleaning is relatively clean, which provides a good foundation for the subsequent hydrophobic treatment.

[0085] The single crystal silicon wafer after the secondary cleaning is first cleaned with ozone and hydrofluoric acid (HF) again to obtain the treated single crystal silicon wafer. Ozone is mainly used to remove organic pollutants on the surface of silicon wafers. Hydrofluoric acid is usually used to remove the natural oxide layer or the oxide layer remaining after chemical mechanical polishing. Ozone cleaning and hydrofluoric acid cleaning themselves do not directly form a hydrophobic surface, but they provide the necessary surface conditions for subsequent hydrophobic treatment.

[0086] It should be noted that the hydrophobic treatment of single-crystal silicon wafers refers to changing the properties of the silicon wafer surface by physical or chemical methods to make it have the ability to repel water molecules. This can usually be achieved through the following methods: deposition of hydrophobic films, chemical modification or nanostructure construction.

[0087] The single-crystal silicon wafer that has been hydrophobicized will form a hydrophobic surface, which will have excellent waterproof, anti-fouling and self-cleaning properties, making it easier to prepare for subsequent production processes.

[0088] The embodiment of the present invention uses a first alkaline solution to etch a single crystal silicon wafer to prepare a smooth pyramid structure, and then uses a second alkaline solution to perform a secondary etching, so that the smooth pyramid structure is velvet-modified and its surface becomes an uneven slope.

[0089] The embodiment of the present invention also uses different cleaning processes to clean the single crystal silicon wafers obtained in each step. Different cleaning processes result in different surface states of the formed silicon wafers. Therefore, the alkaline solution has a specific reaction rate to different crystal faces of the single crystal silicon wafer.

[0090] The method for preparing the texture of a single crystal silicon wafer provided in an embodiment of the present invention performs a primary cleaning on the textured single crystal silicon wafer to obtain a primary cleaned single crystal silicon wafer, then performs a secondary texture modification and a secondary cleaning, and then performs a hydrophobic treatment to obtain a treated single crystal silicon wafer, so that the surface of the treated single crystal silicon wafer presents a modified pyramid structure, which can reduce the reflectivity of sunlight, increase light absorption, and improve the utilization rate of sunlight, thereby improving the photoelectric conversion efficiency of solar cells.

[0091] In some embodiments, when the volume ratio of the first alkaline solution is 2%-3.5%, the volume percentage of the first additive is 0.5%-1%, and the volume ratio of the second alkaline solution is 0.2%-0.5%.

[0092] It can be understood that when the volume ratio of the first alkaline solution is within a more precise range of 2%-3.5%, the volume percentage of the first additive and the volume ratio of the second alkaline solution can be adjusted accordingly. Therefore, the volume percentage of the first additive can be adjusted to 0.5%-1%, and the volume ratio of the second alkaline solution can be adjusted to 0.2%-0.5%.

[0093] In some embodiments, the temperature for the corrosion treatment is 70° C.-85° C., the time for the corrosion treatment is 400s-800s, the temperature for the suede modification is 25° C.-35° C., and the time for the suede modification is 250s-450s.

[0094] It can be understood that when the volume ratio of the first alkaline solution is within a more precise range of 2%-3.5% and the volume ratio of the second alkaline solution is within a more precise range of 0.2%-0.5%, the temperature and time of the corrosion treatment, as well as the temperature and time of the suede modification can be adjusted accordingly. Therefore, the temperature of the corrosion treatment can be adjusted to 70℃-85℃, the time of the corrosion treatment can be adjusted to 400s-800s, the temperature of the suede modification can be adjusted to 25℃-35℃, and the time of the suede modification can be adjusted to 250s-450s.

[0095] In some embodiments, the second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 0.3%.

[0096] It is understandable that the second additive may or may not be added during suede modification. When the volume ratio of the second alkaline solution is within a more precise range of 0.2%-0.5%, the volume percentage of the second additive may be controlled within the range of 0%-0.3%, which can be selected according to actual needs and is not specifically limited here.

[0097] The components of the second additive may include, but are not limited to, surfactants, natural polysaccharide compounds, dispersants, emulsifiers, nucleating agents, chelating agents, naphthalenesulfonate formaldehyde condensates, inorganic bases, silicon reaction catalysts, water, etc. The components of the second additive may be the same as or different from those of the first additive.

[0098] It is understandable that different types of the second additive will result in the second alkaline solution having specific reaction rates to different crystal faces of the single crystal silicon wafer. The type of the second additive can be selected according to demand and is not specifically limited here.

[0099] The method for preparing the textured surface of a single crystal silicon wafer provided by the present invention is generally described below through several specific embodiments.

[0100] Example 1

[0101] Step 1: Perform preliminary alkaline texturing on the single crystal silicon wafer to form a pyramid structure on the surface of the single crystal silicon wafer. The reaction solution components include: one or more alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH), and the volume ratio of the alkaline solution is 1%-5%.

[0102] The reaction solution also includes additive A, the volume percentage of additive A is 0.1%-2%, the reaction temperature is 50° C.-90° C., and the reaction time is 300s-1200s.

[0103] Additive A comprises: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water.

[0104] Step 2: The texturized single crystal silicon wafer obtained in step 1 is washed with deionized water to remove the chemical solution residue.

[0105] Step 3, placing the single crystal silicon wafer obtained in step 2 after the initial cleaning in a secondary reaction solution for velvet modification, wherein the secondary reaction solution comprises one or more alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH), and the volume ratio of the alkaline solution is 0.1%-3%.

[0106] The secondary reaction solution also includes additive B, the volume percentage of additive B is 0%-1%, the reaction temperature is 20° C.-50° C., and the reaction time is 200s-800s.

[0107] Additive B includes: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water.

[0108] Step 4: The single crystal silicon wafer after the velvet modification in step 3 is cleaned with deionized water, a mixture of alkali and hydrogen peroxide, etc. to remove the chemical solution residue on the surface.

[0109] Step 5: The structure prepared in step 4 is subjected to ozone cleaning and hydrofluoric acid (HF) cleaning to form a hydrophobic surface for facilitating subsequent production processes.

[0110] Compared with the prior art, the method for preparing the textured surface of a single crystal silicon wafer provided in the embodiment of the present invention reduces the reflectivity and increases the light absorption by changing the textured surface structure of the front side of the single crystal silicon wafer.

[0111] Example 2

[0112] Step 1: Perform preliminary alkali texturing on the single crystal silicon wafer to form a pyramid structure on the surface of the single crystal silicon wafer. The reaction solution components include: one or more alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH), and the volume ratio of the alkaline solution is 2%-3.5%.

[0113] The reaction solution also includes additive A, the volume percentage of additive A is 0.5%-1%, the reaction temperature is 70° C.-85° C., and the reaction time is 400s-800s.

[0114] Additive A comprises: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water.

[0115] Step 2: The texturized single crystal silicon wafer obtained in step 1 is washed with deionized water to remove the chemical solution residue.

[0116] Step 3, placing the single crystal silicon wafer obtained in step 2 after the initial cleaning in a secondary reaction solution for velvet modification, wherein the secondary reaction solution comprises one or more alkaline solutions such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH) or tetramethylhydroxylamine (TMAH), and the volume ratio of the alkaline solution is 0.2%-0.5%.

[0117] The secondary reaction solution also includes additive B, the volume percentage of additive B is 0%-0.3%, the reaction temperature is 25° C.-35° C., and the reaction time is 250s-450s.

[0118] Additive B includes: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water.

[0119] Step 4: The single crystal silicon wafer after the velvet modification in step 3 is cleaned with deionized water, a mixture of alkali and hydrogen peroxide, etc. to remove the chemical solution residue on the surface.

[0120] Step 5: The structure prepared in step 4 is subjected to ozone cleaning and hydrofluoric acid (HF) cleaning to form a hydrophobic surface for facilitating subsequent production processes.

[0121] Compared with the prior art, the method for preparing the textured surface of a single crystal silicon wafer provided in the embodiment of the present invention can reduce the reflectivity of sunlight and increase light absorption by changing the textured surface structure of the single crystal silicon wafer.

[0122] It can be understood that the single crystal silicon wafer provided in the embodiment of the present invention is manufactured by the method for preparing the textured surface of a single crystal silicon wafer in any of the above embodiments.

[0123] It should be noted that the above embodiment has already described the method for preparing the textured surface of a single crystal silicon wafer accordingly, and the single crystal silicon wafer prepared by the method for preparing the textured surface of a single crystal silicon wafer will not be described in detail here.

[0124] The single crystal silicon wafer provided in the embodiment of the present invention can reduce the sunlight reflectivity and increase the light absorption by changing the velvet structure of the front side of the single crystal silicon wafer.

[0125] An embodiment of the present invention further provides a solar cell, comprising the single crystal silicon wafer in any of the above embodiments.

[0126] It should be noted that the above embodiment has already described the method for preparing the textured surface of a single crystal silicon wafer, and the solar cell composed of the single crystal silicon wafer prepared by the above method will not be described in detail here.

[0127] The solar cell provided by the embodiment of the present invention can reduce the sunlight reflectivity, increase light absorption, and improve the photoelectric conversion efficiency of the back side of the solar cell by changing the velvet structure of the front side of the double-sided solar cell.

[0128] The present invention further provides a photovoltaic assembly, comprising the solar cell in any one of the above embodiments.

[0129] It should be noted that the above embodiment has already described the method for preparing the textured surface of a single crystal silicon wafer, and the photovoltaic module composed of the above solar cells will not be described in detail here.

[0130] Table 1

[0131] Group Eta / % Voc / V Isc / mA*cm-2 FF / % Example 25.29 0.732 39.91 84.37 Comparative Example 24.13 0.749 38.07 85.34

[0132] As shown in Table 1, Eta refers to photoelectric conversion efficiency, Voc refers to open circuit voltage, Isc refers to short circuit current, and FF refers to conversion factor. It can be concluded that the photoelectric conversion efficiency, open circuit voltage, short circuit current and conversion factor of the solar cell of the embodiment of the present invention are higher than the corresponding parameters of the solar cell of the comparative example, especially the short circuit current of the embodiment of the present invention is much larger than the short circuit current of the comparative example.

[0133] like Figure 8 As shown, the solid line is a schematic diagram of the reflectivity (%) of the front suede surface of the solar cell of the comparative example, and the dotted line is a schematic diagram of the reflectivity (%) of the front suede surface of the solar cell of the embodiment of the present invention.

[0134] It should be noted that Figure 8 The middle horizontal axis is reflectivity (%), and the horizontal axis is the wavelength of light (nm).

[0135] In the embodiment of the present invention, the velvet structure of at least one surface of the solar cell is a special pyramid structure, that is, Figures 1 to 5 The suede structure of the solar cell in the comparative example is a common pyramid structure, that is, a smooth pyramid structure.

[0136] Depend on Figure 8 It can also be seen that the reflectivity of the front velvet surface of the solar cell of the embodiment of the present invention is lower than that of the comparative example, and has a more excellent light absorption effect.

[0137] The photovoltaic module provided by the embodiment of the present invention can reduce the sunlight reflectivity, increase light absorption, and improve the photoelectric conversion efficiency of the back of the solar cell by changing the front velvet structure of the double-sided solar cell, thereby greatly improving the overall efficiency of the photovoltaic module.

[0138] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementation methods in the above embodiments to obtain technical solutions of multiple implementation methods.

[0139] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A single crystal silicon wafer, characterized in that: include: Two opposite surfaces, at least one of the two surfaces having a suede structure; The velvet structure includes: a plurality of pyramid-like structures, wherein the pyramid-like structures include at least one pyramid top, at least four side edges and at least four side surfaces; A scale-like texture structure is distributed on part of the side surfaces; a plurality of angular texture structures are arranged along part of the side edges and extend from the side edges to the two side surfaces connected by the side edges.

2. A method for preparing a textured surface of a single crystal silicon wafer, characterized in that: For making the single crystal silicon wafer according to claim 1, the method comprises: Using a first texturing liquid to perform etching treatment on at least one surface of the single crystal silicon wafer to form a pyramid structure on the at least one surface to obtain a texturing single crystal silicon wafer; The single crystal silicon wafer after the texturing is cleaned with deionized water to obtain a single crystal silicon wafer after the primary cleaning; Using a second texturing liquid to perform texturing on the single crystal silicon wafer after the initial cleaning to obtain a single crystal silicon wafer after texturing; The first texturing liquid includes a first alkaline solution and a first additive, the volume ratio of the first alkaline solution is 1%-5%, and the volume percentage of the first additive is 0.1%-2%; the second texturing liquid includes at least a second alkaline solution, and the volume ratio of the second alkaline solution is 0.1%-3%.

3. The method for preparing a textured surface of a single crystal silicon wafer according to claim 2, characterized in that: The temperature for the corrosion treatment is 50°C-90°C, and the time for the corrosion treatment is 300s-1200s; the temperature for the suede modification is 20°C-50°C, and the time for the suede modification is 200s-800s.

4. The method for preparing a textured surface of a single crystal silicon wafer according to claim 3, characterized in that: The second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 1%.

5. The method for preparing a textured surface of a single crystal silicon wafer according to claim 4, characterized in that: The components of the first additive include: surfactant, natural polysaccharide compound, dispersant, emulsifier, nucleating agent, chelating agent, naphthalenesulfonate formaldehyde condensate, inorganic base, silicon reaction catalyst and water; The composition of the second additive is the same as that of the first additive.

6. The method for preparing a textured surface of a single crystal silicon wafer according to claim 2, characterized in that: When the volume ratio of the first alkaline solution is 2%-3.5%, the volume percentage of the first additive is 0.5%-1%, and the volume ratio of the second alkaline solution is 0.2%-0.5%.

7. The method for preparing a textured surface of a single crystal silicon wafer according to claim 6, characterized in that: The temperature for the corrosion treatment is 70°C-85°C, the time for the corrosion treatment is 400s-800s, the temperature for the suede modification is 25°C-35°C, and the time for the suede modification is 250s-450s.

8. The method for preparing a textured surface of a single crystal silicon wafer according to claim 7, characterized in that: The second texturing liquid further includes a second additive, and the volume percentage of the second additive is greater than 0% and less than or equal to 0.3%.

9. The method for preparing a textured surface of a single crystal silicon wafer according to any one of claims 2 to 8, characterized in that: After obtaining the textured single crystal silicon wafer, the method further comprises: The textured single crystal silicon wafer is cleaned with deionized water and a mixed solution in sequence to obtain a second-cleaned single crystal silicon wafer, wherein the mixed solution comprises alkali and hydrogen peroxide; The single crystal silicon wafer after the secondary cleaning is subjected to a hydrophobic treatment to obtain a treated single crystal silicon wafer.

10. A solar cell, characterized in that: Comprising the single crystal silicon wafer as claimed in claim 1.

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