Textured surface preparation method of silicon wafer, alkaline solution, texturing device and related photovoltaic device

Abstract

The embodiment of the invention provides a texturing preparation method of a silicon wafer, an alkaline solution, a texturing device and a related photovoltaic device. The textured surface preparation method of the silicon wafer comprises the following steps: obtaining an alkaline solution, wherein the alkaline solution comprises acetone; the temperature of the alkaline solution is higher than 65 DEG C; putting the silicon wafer into an alkaline solution to etch the silicon wafer so as to prepare a silicon wafer with a textured surface; and the average angle of the pyramid sharp corners in the suede is 100-110 degrees. According to the embodiment of the invention, the silicon wafer is placed in the alkaline solution containing acetone for etching, so that the angle of the pyramid tip of the pyramid on the surface of the obtained silicon wafer is larger, and the pyramid structure is relatively smooth. Therefore, the defect state density of hydrogenated amorphous silicon deposited on the pyramid surface is reduced, the recombination loss of photon-generated carriers is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a method for preparing a textured surface of a silicon wafer, an alkaline solution, a texture-making device, and related photovoltaic devices. Background Art

[0002] In crystalline silicon photovoltaic cells, light absorption can be increased by texturing the surface of the silicon wafer. After texturing the surface of the silicon wafer, a pyramid structure can be formed on the surface of the silicon wafer, and then a layer of hydrogenated amorphous silicon is deposited on the surface of the pyramid structure as a passivation layer to passivate defects on the surface of the silicon wafer.

[0003] The angle of the pyramid tip may be different. When the angle of the pyramid tip is small, the defect state density of the hydrogenated amorphous silicon deposited on the surface of the pyramid will increase, and the photogenerated carriers will combine with the defect states in the hydrogenated amorphous silicon, causing the recombination loss of the photogenerated carriers and reducing the photoelectric conversion efficiency of the solar cell.

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

[0005] The embodiments of the present application provide a method for preparing the texture of a silicon wafer, an alkaline solution, a texture-making device and related photovoltaic devices to solve or alleviate one or more of the technical problems raised above.

[0006] A first aspect of an embodiment of the present application provides a method for preparing a textured surface of a silicon wafer, comprising the following steps:

[0007] Obtaining an alkaline solution, the alkaline solution comprising acetone; the temperature of the alkaline solution is greater than 65° C.;

[0008] The silicon wafer is placed in an alkaline solution to be etched to obtain a silicon wafer with a velvet surface; the average angle of the pyramid tips in the velvet surface is 100° to 110°.

[0009] Optionally, the alkaline solution also includes deionized water and a soluble alkali; the soluble alkali includes at least one of sodium hydroxide and potassium hydroxide; wherein, in the alkaline solution, the volume fraction of acetone is 5% to 15%, the volume fraction of sodium hydroxide and / or potassium hydroxide is 10% to 20%, and the volume fraction of deionized water is 65% to 85%.

[0010] Optionally, the temperature of the alkaline solution is 75°C to 85°C.

[0011] Optionally, placing the silicon wafer in an alkaline solution to etch the silicon wafer includes: placing the silicon wafer in the alkaline solution and stirring the alkaline solution; the silicon wafer is etched in the stirred alkaline solution for 50 minutes to 65 minutes.

[0012] Optionally, the stirring speed of the alkaline solution is 400 rpm / min to 600 rpm / min.

[0013] Optionally, it also includes:

[0014] The alkaline solution is placed in a glass container, and the glass container is placed in a condenser, and the liquid condensed by the condenser flows back into the glass container.

[0015] A second aspect of the embodiment of the present application provides an alkaline solution for preparing velvet, comprising:

[0016] Acetone, the volume fraction of acetone in the alkaline solution is 5% to 15%; soluble alkali, the volume fraction of soluble alkali in the alkaline solution is 10% to 20%; the soluble alkali includes at least one of sodium hydroxide and potassium hydroxide; deionized water, the volume fraction of deionized water in the alkaline solution is 65% to 85%.

[0017] A third aspect of the embodiment of the present application provides a texturing device, which is used in the texturing method of the silicon wafer as described above, comprising:

[0018] A glass container for containing an alkaline solution; the alkaline solution is the alkaline solution for preparing the velvet surface as mentioned above;

[0019] The condenser is provided with a glass vessel placed inside the condenser; the condenser comprises a condensation outlet, and the condensation outlet is arranged toward the opening of the glass vessel.

[0020] Optionally, the texturing device further comprises a magnetic ultrasonic stirrer;

[0021] The magnetic ultrasonic stirrer comprises a magnet and a magnetic ultrasonic release part;

[0022] The magnet is located at the bottom of the glass container and is used to rotate and stir the alkaline solution;

[0023] A glass vessel is placed above the magnetic ultrasonic release part to release the magnetic force to rotate the magnet and release ultrasonic waves to act on the alkaline solution.

[0024] Optionally, the texturing device further comprises a support, which is arranged in the glass container and is used for placing the silicon wafer.

[0025] A fourth aspect of the embodiments of the present application provides a crystalline silicon photovoltaic cell, wherein the crystalline silicon photovoltaic cell comprises a silicon wafer, and the silicon wafer is made into a textured surface by the textured surface preparation method of a silicon wafer as described above.

[0026] Optionally, the pyramids in the fleece satisfy at least one of the following properties:

[0027] (1) The length of the base of the pyramid is 1 μm to 2 μm;

[0028] (2) The height of the pyramid is 0.5 μm to 1 μm;

[0029] (3) The angle between the base of the pyramid and the hypotenuse of the pyramid is 35° to 40°;

[0030] (4) The distance between two adjacent pyramids is 1 μm to 2 μm.

[0031] A fifth aspect of an embodiment of the present application provides a photovoltaic module, which includes a plurality of solar cells connected in series and / or in parallel; wherein at least one solar cell is the crystalline silicon photovoltaic cell as described above.

[0032] The above technical solution adopted in the embodiment of the present application may have the following advantages:

[0033] By placing the silicon wafer in an alkaline solution containing acetone for etching, acetone can reduce the selective etching characteristics of the alkaline solution on the silicon wafer crystal surface, so that the alkaline solution reduces the etching rate of the crystal surface with strong selectivity, and reduces the difference in etching rate between the crystal surface with strong selectivity and the crystal surface with weak selectivity. The resulting pyramid on the surface of the silicon wafer has a larger angle of the top and a relatively smooth pyramid structure. This reduces the defect state density of hydrogenated amorphous silicon deposited on the pyramid surface, reduces the recombination loss of photogenerated carriers, and thus improves the photoelectric conversion efficiency of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 This is a flow chart of a method for preparing a velvet surface of a silicon wafer provided in an embodiment of the present application;

[0036] Figure 2 This is a schematic diagram of the structure of a crystalline silicon photovoltaic cell prepared by the velvet preparation method provided in an embodiment of the present application;

[0037] Figure 3 It is a schematic diagram of the texture structure of a silicon wafer prepared by the texture preparation method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0039] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not mean that the present disclosure necessarily has the first element, component, region, layer or part.

[0040] 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 or an electrical connection; 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, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0043] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0044] like Figure 1 to Figure 3 As shown, the embodiment of the present application provides a method for preparing a textured surface of a silicon wafer, comprising the following steps:

[0045] S210, obtaining an alkaline solution, wherein the alkaline solution includes acetone; and the temperature of the alkaline solution is higher than 65°C.

[0046] S220, placing the silicon wafer 200 in an alkaline solution to etch the silicon wafer 200, so as to obtain a silicon wafer 200 with a velvet surface; the average angle of the pyramid corners 100 in the velvet surface is 100° to 110°.

[0047] In one example, the alkaline solution may further include potassium hydroxide (KOH) or sodium hydroxide (NaOH) solution.

[0048] When the alkaline solution contains only potassium hydroxide or sodium hydroxide solution, the silicon wafer 200 can also be textured. Specifically, the surface of the silicon wafer 200 has different types of crystal planes, and the alkaline solution has the characteristic of selective etching. The alkaline solution has a higher etching rate for crystal planes with strong selectivity and a lower etching rate for crystal planes with weak selectivity. The different etching rates cause the crystal planes with strong selectivity on the surface of the silicon wafer 200 to be preferentially dissolved, thereby forming a number of pyramid-shaped / conical structures. Therefore, the surface of the silicon wafer 200 can be textured by an alkaline solution.

[0049] In one example, when the silicon wafer 200 is subjected to texturing treatment using a sodium hydroxide solution, the silicon wafer 200 may react with the sodium hydroxide solution to generate sodium silicate and hydrogen.

[0050] In the embodiment of the present application, the alkaline solution includes acetone, and acetone can change the selective etching characteristics of the alkaline solution, so that the etching rate of the alkaline solution on the crystal plane with strong selectivity is reduced, and the difference in etching rate between the crystal plane with strong selectivity and the crystal plane with weak selectivity is reduced, so that the edges and corners of the formed pyramid are relatively less obvious, that is, the angle of the pyramid tip 100 is relatively increased.

[0051] Since acetone has a lower surface tension, it can change the selective etching characteristics of the alkaline solution and reduce the etching rate of the alkaline solution on the crystal surface with strong selectivity.

[0052] In one example, adding acetone with low surface tension to a sodium hydroxide solution can reduce the surface tension of the sodium hydroxide solution. As the surface tension of the sodium hydroxide solution decreases, the interaction force between the solvent molecules weakens, and the sodium silicate generated by the reaction between the silicon wafer 200 and the sodium hydroxide solution cannot be fully dissolved in the sodium hydroxide solution, resulting in a low solubility of the sodium silicate. The solubility of sodium silicate is reduced, and the undissolved sodium silicate solid will adhere to the silicon wafer 200 to form a passivation layer, which hinders the direct contact between the sodium hydroxide solution and the silicon wafer 200, thereby reducing the etching rate of the crystal plane with strong selectivity in the silicon wafer 200.

[0053] During the etching process of this embodiment, the silicon wafer 200 is placed in an alkaline solution, and the temperature of the alkaline solution is higher than 65° C. When the temperature is lower than 65° C., the chemical reaction rate between the alkaline solution and the silicon wafer 200 is slow, the etching rate is low, and it is difficult to form the desired textured structure.

[0054] Since the alkaline solution includes acetone, the etching rate of the crystal plane with strong selectivity is reduced, and the difference in etching rate between the crystal plane with strong selectivity and the crystal plane with weak selectivity is reduced, making the edges and corners of the formed pyramid relatively less obvious. Therefore, the average angle of the pyramid tip 100 finally formed is 100°~110°.

[0055] If the alkaline solution does not contain acetone, the difference in etching rate between the crystal plane with strong selectivity and the crystal plane with weak selectivity is relatively large, so that the edges and corners of the formed pyramid are relatively obvious, and the pyramid tip angle 100 degrees formed by etching is small, and the shape is more prominent. The height difference between the tip of this prominent pyramid and the bottom of the pyramid is too large, and the pyramid as a whole is not smooth enough. When hydrogenated amorphous silicon is deposited on the surface of the silicon wafer 200 to form a passivation layer, defective hydrogenated amorphous silicon is more likely to be formed in uneven places such as the tip of the pyramid. Defective hydrogenated amorphous silicon is easy to combine with photogenerated carriers, which increases the recombination loss at the interface between the crystalline silicon layer and the passivation layer, and reduces the photoelectric conversion efficiency of the solar cell.

[0056] In this embodiment, by placing the silicon wafer 200 in an alkaline solution containing acetone for etching, the angle of the pyramid tip 100 on the surface of the silicon wafer 200 is made larger, and the pyramid structure is relatively smooth, thereby reducing the defect state density of hydrogenated amorphous silicon deposited on the pyramid surface, reducing the recombination loss of photogenerated carriers, and thus improving the photoelectric conversion efficiency of the solar cell.

[0057] In an optional embodiment, the pyramids in the velvet surface satisfy at least one of the following properties:

[0058] (1) The length of the base of the pyramid is 1 μm to 2 μm;

[0059] (2) The height of the pyramid is 0.5 μm to 1 μm;

[0060] (3) The angle between the base of the pyramid and the hypotenuse of the pyramid is 35° to 40°;

[0061] (4) The distance between two adjacent pyramids is 1 μm to 2 μm.

[0062] Since the pyramid tip angle 100 of the silicon wafer 200 surface etched by the alkaline solution containing acetone is larger, the length of the base of the pyramid is relatively increased, and the height of the pyramid and the angle between the base of the pyramid and the hypotenuse of the pyramid are relatively reduced. As a result, the pyramid structure is relatively smoother, which can reduce the defect state density of hydrogenated amorphous silicon deposited on the pyramid surface.

[0063] In an optional embodiment, the alkaline solution also includes deionized water and a soluble alkali; the soluble alkali includes at least one of sodium hydroxide and potassium hydroxide; wherein, in the alkaline solution, the volume fraction of acetone is 5% to 15%, the volume fraction of sodium hydroxide and / or potassium hydroxide is 10% to 20%, and the volume fraction of deionized water is 65% to 85%.

[0064] Illustratively, the volume fraction of acetone in the alkaline solution may be 5%, 7%, 9%, 12% or 15%.

[0065] In one example, 1000 mL of deionized water may be taken, 0.4 g of sodium hydroxide may be added to the deionized water and stirred to dissolve, and then 5% acetone may be added to the sodium hydroxide solution, and 50 mL of acetone may be added to mix to obtain an alkaline solution.

[0066] If the acetone content in the alkaline solution is too low, the selective etching characteristics of the sodium hydroxide solution / potassium hydroxide solution cannot be effectively suppressed, and the pyramids on the surface of the etched silicon wafer 200 are too prominent. Conversely, if the acetone content in the alkaline solution is too high, it may produce unnecessary reaction byproducts, resulting in a decrease in the chemical stability of the solution and affecting the etching effect.

[0067] In this embodiment, by limiting the volume fraction of acetone in the alkaline solution within a suitable range, less excess products are generated during the etching process, making the etching reaction relatively stable, and the pyramid structure on the surface of the etched silicon wafer 200 is relatively smooth.

[0068] In an optional embodiment, the temperature of the alkaline solution during the texturing reaction is preferably 75° C. to 85° C. Exemplarily, the temperature of the alkaline solution may be 75° C., 78° C., 80° C., 83° C. or 85° C.

[0069] In one example, the temperature of the alkaline solution can be controlled between 75° C. and 85° C. by a constant temperature water bath or a constant temperature heater.

[0070] If the alkaline solution temperature is too high, the etching rate will be faster, the roughness of the velvet surface will increase, and it will be difficult to obtain an ideal velvet surface structure. If the alkaline solution temperature is too low, the chemical reaction rate in the solution will decrease, the etching time will be extended, and the production efficiency will be affected.

[0071] In an optional embodiment, placing the silicon wafer 200 in an alkaline solution to etch the silicon wafer 200 includes: placing the silicon wafer 200 in the alkaline solution and stirring the alkaline solution; the silicon wafer 200 is etched in the stirred alkaline solution for 50 minutes to 65 minutes.

[0072] In one example, before placing the silicon wafer 200 in an alkaline solution for etching, the silicon wafer 200 may be rinsed with deionized water, and then dried in a nitrogen gas flow or in a sterile environment.

[0073] In one example, after the silicon wafer 200 is placed and the etching reaction begins, stirring can be performed to make the reaction more complete. A magnetic stirrer or an ultrasonic stirrer can be used to stir the alkaline solution. A magnetic stirrer can rotate and stir the magnet placed in the alkaline solution by applying magnetic force; an ultrasonic stirrer can stir the molecules in the solution by applying ultrasonic waves.

[0074] In addition, mechanical stirring can also be used to achieve stirring through a stirring rod. The specific stirring method can be selected according to the actual production environment and is not limited here.

[0075] The etching time of the silicon wafer 200 is 50 minutes to 65 minutes. For example, the etching time can be 50 minutes, 55 minutes, 60 minutes or 65 minutes. If the etching time is too long, excessive etching may damage the surface of the silicon wafer 200 and fail to obtain the expected velvet surface; if the etching time is too short, the reaction time is insufficient and the expected etching depth may not be achieved, affecting the optical performance of the silicon wafer 200.

[0076] In this embodiment, stirring the alkaline solution during the etching process helps to improve the reaction efficiency, ensure that the reaction substances in the solution are evenly distributed, and make the etching more uniform; etching is performed within a limited time range. On the one hand, the silicon wafer 200 will not over-react, ensuring the structural integrity of the silicon wafer 200, and on the other hand, the etching reaction can be fully carried out to ensure the formation of a uniform and effective velvet structure, thereby improving the optical performance of the silicon wafer 200. In an optional embodiment, the stirring speed of the alkaline solution is 400rpm / min to 600rpm / min. Exemplarily, the stirring speed can be 400rpm / min, 450rpm / min, 500rpm / min, 550rpm / min or 600rpm / min.

[0077] In one example, a magnetic stirrer with a digital display and a speed adjustment function may be used to control the stirring speed within a range of 400 rpm / min to 600 rpm / min.

[0078] If the stirring speed is too high, a large number of bubbles will be generated in the solution, and these bubbles may stay on the surface of the silicon wafer 200, thereby affecting the uniformity of etching and the quality of the velvet surface; if the stirring speed is too low, it may cause uneven distribution of the reaction substances in the solution, affecting the uniformity of etching and resulting in a lower reaction rate.

[0079] In this embodiment, by controlling the stirring speed of the alkaline solution within a certain range, the reaction substances in the solution are evenly distributed, the surface of the etched silicon wafer 200 is more uniform, and the reaction efficiency of the etching process is improved.

[0080] In an optional embodiment, the method for preparing the textured surface of the silicon wafer 200 further includes placing the alkaline solution in a glass container, and placing the glass container in a condenser, so that the liquid condensed by the condenser flows back into the glass container.

[0081] Glassware is corrosion-resistant and its transparency allows the operator to clearly observe the internal reaction, so it can be used as a container for alkaline solutions.

[0082] In one example, the bottom of the glassware can be flat or rounded.

[0083] In one example, the condenser may be a tubular or spiral sealed container with a cooling system such as a cold water or coolant circulation system disposed therein.

[0084] In this embodiment, by placing the glassware containing the alkaline solution inside the condenser, the acetone gas volatilized during the reaction can be condensed into liquid through the condenser and refluxed into the alkaline solution. Such a texturing device can effectively reduce acetone loss, maintain the stability of the composition and concentration of the alkaline solution, ensure the continuity and consistency of the etching reaction, improve the texturing effect and save experimental costs.

[0085] The present application embodiment may also provide an alkaline solution for preparing velvet, the solution comprising:

[0086] Acetone, the volume fraction of acetone in the alkaline solution is 5% to 15%;

[0087] Soluble alkali, the volume fraction of the soluble alkali in the alkaline solution is 10% to 20%; the soluble alkali includes at least one of sodium hydroxide and potassium hydroxide;

[0088] Deionized water, wherein the volume fraction of deionized water in the alkaline solution is 65% to 85%.

[0089] Illustratively, the volume fraction of acetone in the alkaline solution may be 5%, 7%, 9%, 12% or 15%.

[0090] In this embodiment, an alkaline solution containing acetone is used to prepare the velvet surface of the silicon wafer 200. Acetone can reduce the selective etching characteristics of the alkaline solution on the crystal surface of the silicon wafer 200, so that the etching rate of the alkaline solution on the crystal surface with strong selectivity is reduced, and the difference in etching rate between the crystal surface with strong selectivity and the crystal surface with weak selectivity is reduced, and the pyramid structure is relatively smooth. Thereby reducing the defect state density of hydrogenated amorphous silicon deposited on the pyramid surface, reducing the recombination loss of photogenerated carriers, and thus improving the photoelectric conversion efficiency of the solar cell.

[0091] In the alkaline solution for preparing the velvet provided in the above embodiment, the alkaline solution for etching the silicon wafer 200 contains acetone, and acetone is a volatile organic solvent. Therefore, in view of the volatile nature of acetone, the etching process of the silicon wafer 200 in the embodiment of the present application needs to be carried out in a special velvet making device. The following will introduce a velvet making device provided in another embodiment of the present application, which includes:

[0092] A glass container, used to hold an alkaline solution for preparing velvet provided in the above embodiment;

[0093] Condenser, glassware is placed inside the condenser;

[0094] The condenser comprises a condensation outlet, and the condensation outlet is arranged toward the opening of the glass vessel.

[0095] In one example, the condenser may be a tubular or spiral sealed container with a cooling system such as a cold water or coolant circulation system disposed therein.

[0096] In one example, the condensation outlet may be located at the top or the side of the condenser to collect substances evaporated from the alkaline solution, such as acetone.

[0097] In one example, the glassware may be a beaker, with an opening facing upward.

[0098] The condensation outlet is arranged toward the opening of the glass vessel, so that the volatile substances collected by the condensation outlet flow back into the glass vessel.

[0099] In this embodiment, by placing the glass container containing the alkaline solution inside the condenser, the acetone gas volatilized during the reaction can be condensed into liquid through the condenser and refluxed into the alkaline solution through the condensation outlet. Such a texturing device can effectively reduce acetone loss, maintain the stability of the composition and concentration of the alkaline solution, ensure the continuity and consistency of the etching reaction, improve the texturing effect and save experimental costs.

[0100] In an optional embodiment, the texturing device further comprises a magnetic ultrasonic agitator;

[0101] The magnetic ultrasonic stirrer comprises a magnet and a magnetic ultrasonic release part;

[0102] The magnet is located at the bottom of the glass container and is used to rotate and stir the alkaline solution;

[0103] A glass vessel is placed above the magnetic ultrasonic release part to release the magnetic force to rotate the magnet and release ultrasonic waves to act on the alkaline solution.

[0104] The glassware is used as a container of the alkaline solution and is placed above the magnetic ultrasonic release part and in direct contact with the magnetic ultrasonic release part. The magnetic ultrasonic release part can release magnetic force and ultrasonic waves.

[0105] The magnet is located at the bottom of the glass container. Through the magnetic force released by the magnetic ultrasonic release part, the magnet can rotate freely in the solution to achieve stirring.

[0106] While the magnetic stirring is in progress, the release of ultrasonic waves acts on the alkaline solution, increasing the collision frequency of molecules in the solution through sound wave oscillations, accelerating the chemical reaction process, and further improving the etching efficiency.

[0107] In this embodiment, by providing a magnetic ultrasonic stirrer in the texturing device, the reactants in the alkaline solution can be effectively mixed and stirred evenly, thereby increasing the contact frequency between the reactants in the solution, thereby improving the efficiency and speed of the etching process.

[0108] In an optional embodiment, the texturing device further includes a bracket, which is disposed in a glass container and is used to place the silicon wafer 200 .

[0109] In one example, the material of the bracket may be polytetrafluoroethylene, or other materials that do not react with the alkaline solution.

[0110] In one example, the support may be disposed on the side wall or the bottom of the glass container, and the silicon wafer 200 may be vertically placed on the support to keep the silicon wafer 200 stable during the etching process.

[0111] In this embodiment, a support is provided in the glass container to fix the silicon wafer 200 so that the surface of the silicon wafer 200 can be fully in contact with the alkaline solution, thereby preventing the silicon wafer 200 from floating or being difficult to maintain stability, which makes the etching difficult to control, and achieving uniform etching.

[0112] The following will conduct performance tests on a method for preparing a textured surface of a silicon wafer 200, a structure of a crystalline silicon photovoltaic cell, and related comparative examples provided in an embodiment of the present application.

[0113] [Example 1]

[0114] The specific structure of the battery includes a silicon wafer, which is prepared by a method for preparing a velvet surface of a silicon wafer provided in an embodiment of the present application, and the average angle of the pyramid apex in the velvet surface of the silicon wafer is 100°.

[0115] Wherein, in the alkaline solution, the volume fraction of the acetone is 5%.

[0116] The temperature of the alkaline solution was 75°C.

[0117] The silicon wafer is etched in the stirred alkaline solution for 50 minutes.

[0118] The stirring speed of the alkaline solution is 400 rpm / min.

[0119] [Example 2]

[0120] The difference from Example 1 is that, in the alkaline solution, the volume fraction of acetone is 10%.

[0121] [Example 3]

[0122] The difference from Example 1 is that, in the alkaline solution, the volume fraction of acetone is 15%.

[0123] [Example 4]

[0124] The difference from Example 1 is that the temperature of the alkaline solution is 85°C.

[0125] [Example 5]

[0126] The difference from Example 1 is that the etching time of the silicon wafer in the stirred alkaline solution is 65 minutes.

[0127] [Example 6]

[0128] The difference from Example 1 is that the stirring speed of the alkaline solution is 600 rpm / min.

[0129] [Example 7]

[0130] Referring to the crystalline silicon photovoltaic cell of Example 1, the only difference is that the average angle of the pyramid apex in the velvet surface of the silicon wafer of Example 7 is 105°.

[0131] [Example 8]

[0132] Referring to the crystalline silicon photovoltaic cell of Example 1, the only difference is that the average angle of the pyramid tips in the velvet surface of the silicon wafer of Example 8 is 110°.

[0133] [Comparative Example 1]

[0134] The specific structure of the battery includes a silicon wafer. The texturing agent used in the texturing preparation method of the silicon wafer does not contain acetone. The average angle of the pyramid tips in the texturing of the silicon wafer is 70 degrees.

[0135] It should be noted that the average angle value of the pyramid tip angle in the velvet surface of the silicon wafer in Examples 1 to 8 and Comparative Example 1 is obtained by observation and measurement through SEM (Scanning Electron Microscope).

[0136] The following is a performance test of the crystalline silicon photovoltaic cells provided in Examples 1 to 8 of the present application and Comparative Example 1, so as to obtain the open circuit voltage Voc, short circuit current Isc, fill factor FF, and photoelectric conversion efficiency PCE of the corresponding cell devices. The test results are shown in Table 1.

[0137] Table 1 Performance test results of crystalline silicon photovoltaic cells of Examples 1 to 8 and Comparative Example 1

[0138] Voc(V) Isc(A) FF(%) PCE(%) Example 1 0.7352 16.010 86.02 26.67 Example 2 0.7354 16.005 85.94 26.65 Example 3 0.7356 16.004 85.92 26.68 Example 4 0.7358 16.001 85.88 26.54 Example 5 0.7359 16.001 85.87 26.62 Example 6 0.7360 16.001 85.85 26.58 Example 7 0.7362 16.002 85.88 26.56 Example 8 0.7385 16.001 85.32 26.50 Comparative Example 1 0.7321 16.005 86.10 26.62

[0139] It can be seen from the data in Table 1 that, compared with Comparative Example 1, the open circuit voltage Voc of the crystalline silicon photovoltaic cells of Examples 1 to 8 of the present application is significantly improved.

[0140] The embodiment of the present application may also provide a photovoltaic module, wherein the photovoltaic module includes a plurality of solar cells connected in series and / or in parallel; wherein at least one solar cell is a crystalline silicon photovoltaic cell as described above. The plurality of solar cells in series form a cell string, and adjacent crystalline silicon photovoltaic cells may be connected together by string welding.

[0141] The embodiment of the present application can provide a photovoltaic system, including the photovoltaic components in any of the above embodiments. The advantages of the above photovoltaic components are also possessed by the photovoltaic system, which will not be repeated here. The above photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components may form multiple photovoltaic arrays. The photovoltaic array is connected to a junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0142] It should be noted 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", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0143] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0144] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0145] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a velvet surface of a silicon wafer, It is characterized in that The following steps are involved: Obtaining an alkaline solution, wherein the alkaline solution comprises acetone; the temperature of the alkaline solution is higher than 65° C.; The silicon wafer is placed in the alkaline solution to etch the silicon wafer to obtain a silicon wafer with a velvet surface; the average angle of the pyramid apex in the velvet surface is 100° to 110°.

2. The method for preparing a velvet surface of a silicon wafer according to claim 1, It is characterized in that The alkaline solution also includes deionized water and a soluble alkali; the soluble alkali includes at least one of sodium hydroxide and potassium hydroxide; wherein, in the alkaline solution, the volume fraction of the acetone is 5% to 15%, the volume fraction of the sodium hydroxide and / or the potassium hydroxide is 10% to 20%, and the volume fraction of the deionized water is 65% to 85%.

3. The method for preparing a velvet surface of a silicon wafer according to claim 1, It is characterized in that The temperature of the alkaline solution is 75°C to 85°C.

4. The method for preparing a velvet surface of a silicon wafer according to claim 1, It is characterized in that Placing the silicon wafer in the alkaline solution to etch the silicon wafer comprises: placing the silicon wafer in the alkaline solution and stirring the alkaline solution; the etching time of the silicon wafer in the stirred alkaline solution is 50 minutes to 65 minutes.

5. The method for preparing a textured surface of a silicon wafer according to claim 4, It is characterized in that The stirring speed of the alkaline solution is 400 rpm / min to 600 rpm / min.

6. The method for preparing a textured surface of a silicon wafer according to any one of claims 1 to 5, It is characterized in that The method comprises: The alkaline solution is placed in a glass container, and the glass container is placed in a condenser, and the liquid condensed by the condenser flows back into the glass container.

7. An alkaline solution for preparing suede, It is characterized in that include: Acetone, wherein the volume fraction of the acetone in the alkaline solution is 5% to 15%; A soluble alkali, wherein the volume fraction of the soluble alkali in the alkaline solution is 10% to 20%; the soluble alkali comprises at least one of sodium hydroxide and potassium hydroxide; Deionized water, wherein the volume fraction of the deionized water in the alkaline solution is 65% to 85%.

8. A texturing device, used to implement the texturing method for a silicon wafer according to any one of claims 1 to 6, It is characterized in that include: Glassware for holding alkaline solutions; The alkaline solution is the alkaline solution for preparing suede according to claim 7; A condenser, wherein the glass vessel is placed in the condenser; the condenser comprises a condensation outlet, and the condensation outlet is arranged toward the opening of the glass vessel.

9. The texturing device according to claim 8, It is characterized in that The texturing device also includes a magnetic ultrasonic stirrer; The magnetic ultrasonic agitator comprises a magnet and a magnetic ultrasonic release part; Wherein, the magnet is located at the bottom of the glass container and is used to rotate and stir the alkaline solution; The glass vessel is placed above the magnetic ultrasonic release part, which is used to release the magnetic force to rotate the magnet and release ultrasonic waves to act on the alkaline solution.

10. The texturing device according to claim 8, It is characterized in that The texturing device further comprises a support, which is arranged in the glass container and is used for placing the silicon wafer.

11. A crystalline silicon photovoltaic cell, It is characterized in that The crystalline silicon photovoltaic cell comprises a silicon wafer, and the texture of the silicon wafer is prepared by the texture preparation method of a silicon wafer according to any one of claims 1 to 6.

12. The crystalline silicon photovoltaic cell according to claim 11, It is characterized in that The pyramids in the velvet surface satisfy at least one of the following properties: (1) The length of the base of the pyramid is 1 μm to 2 μm; (2) The height of the pyramid is 0.5 μm to 1 μm; (3) The angle between the base of the pyramid and the hypotenuse of the pyramid is 35° to 40°; (4) The distance between two adjacent pyramids is 1 μm to 2 μm.

13. A photovoltaic module, It is characterized in that The photovoltaic module comprises a plurality of solar cells connected in series and / or in parallel; wherein at least one solar cell is the crystalline silicon photovoltaic cell according to any one of claims 11 to 12.

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