Silicon wafer texturing agent and application thereof, silicon wafer texturing method and textured silicon wafer

Abstract

The invention relates to the technical field of silicon wafer production, and provides a silicon wafer texturing agent and application thereof, a silicon wafer texturing method and a textured silicon wafer. The silicon wafer texturing agent contains inorganic fluoride salt, weak acid and water, the molar weight of the inorganic fluoride salt is smaller than that of the weak acid, and the weak acid is phosphoric acid and / or monocarboxylic acid. The invention also provides an application of the silicon wafer texturing agent in silicon wafer production and a silicon wafer texturing method. The method comprises the step of contacting a silicon wafer with the silicon wafer texturing agent. According to the silicon wafer texturing agent provided by the invention, the obtained silicon wafer texturing surface is good in uniformity, no obvious color difference exists between crystal grains, the conversion efficiency of a solar cell is improved, the raw material cost is low, the silicon wafer texturing agent is safe and environment-friendly and is easy to prepare, and the texturing process is safe and controllable in operation.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer production, and in particular to a silicon wafer texturing agent and application thereof, a silicon wafer texturing method and a textured silicon wafer. Background Art

[0002] The surface reflectivity of the original silicon wafer reaches more than 30%. In the production of photovoltaic solar cells, the surface of monocrystalline silicon / polycrystalline silicon must first be textured to make the smooth surface into a velvet surface, so that the incident sunlight is reflected and refracted multiple times on the surface of the silicon wafer, changing the direction of the incident light in the silicon, extending the light path of the sunlight, and thus improving the solar silicon wafer's absorption efficiency of infrared light. The texture increases the surface area near the pn junction, so that more photons are absorbed near the pn junction where carriers are more easily generated, thereby improving the absorption efficiency of photogenerated carriers. Therefore, for silicon-based photovoltaic cells, the texture of silicon wafer surface is a key process in the production of solar cells, which can improve the performance and efficiency of solar cells and directly affect the conversion efficiency and yield rate of the final photovoltaic products.

[0003] Compared with monocrystalline silicon, polycrystalline silicon has a significantly lower cost under the condition of slightly lower conversion efficiency, so it has achieved a large number of development and promotion. In general texturing processes, wet chemical etching methods using alkaline solutions are often used to texturize the surface of polycrystalline silicon wafers. The alkaline texturing solution corrodes silicon anisotropically, corroding the (100) crystal plane faster and the (111) crystal plane slower, eventually forming a positive pyramid velvet structure on the surface of the silicon wafer. Since polycrystalline silicon wafers are composed of grains with different crystal orientations, and the crystal orientations of each grain are randomly distributed, the pyramid velvet structure varies according to the size and orientation of the grains. The surface morphology of alkaline texturing silicon wafers is difficult to control, and the reflection and refraction of sunlight cannot be stabilized, affecting the stability of the yield of photovoltaic cells. In addition, alkaline texturing agents use precious metal copper ions, which require additional cleaning processes, resulting in high wastewater treatment costs, and copper metal ions may cause impurity pollution and affect the conversion efficiency of solar cells.

[0004] The acidic solution corrodes silicon is isotropically, and has nothing to do with the orientation and size of silicon grains, but the existing acidic texturing solutions also have many defects. For example, the acidic etching solution for texturing polycrystalline silicon wafers in the design provided by CN1614789A is a mixture of an oxidant and hydrofluoric acid, which contains toxic and corrosive chromium trioxide or potassium chromate, and will produce heavy metal pollution. The residual metal chromium ions will also affect the conversion efficiency of solar silicon wafers; CN102330154A provides an acidic texturing solution for texturing polycrystalline silicon wafers, which uses high-concentration perchlorate and hydrofluoric acid. High-concentration strong acids are highly corrosive, and concentrated hydrofluoric acid is highly volatile, which is dangerous to operate. At the same time, the surface roughness of the corrosive texture is difficult to control.

[0005] Therefore, it is of great significance to study a new type of safe, environmentally friendly and easy-to-operate texturing agent for silicon wafer texturing processing. Summary of the invention

[0006] A technical problem to be solved by the present disclosure is that the morphology formed by the texturing agent for silicon wafers in the prior art is difficult to control, the reflection of sunlight cannot be stabilized, and the production is seriously polluted and costly.

[0007] In order to solve the above technical problems, the first aspect of the embodiment of the present disclosure provides a silicon wafer texturing agent, which contains an inorganic fluoride salt, a weak acid and water, wherein the molar amount of the inorganic fluoride salt is less than the molar amount of the weak acid, and the weak acid is phosphoric acid and / or a monocarboxylic acid.

[0008] In some embodiments, the molar ratio of the inorganic fluoride salt to the weak acid is 1:1.1-5, preferably 1:2-4.

[0009] In some embodiments, the molar concentration of the inorganic fluoride salt in the silicon wafer texturing agent is 0.3-10 mol / L, more preferably 0.5-1 mol / L.

[0010] In some embodiments, the inorganic fluoride salt is selected from at least one of ammonium fluoride, sodium fluoride, potassium fluoride and lithium fluoride; preferably ammonium fluoride and / or sodium fluoride.

[0011] In some embodiments, the monocarboxylic acid is selected from at least one of glycolic acid, propionic acid, isopropionic acid and lactic acid, and more preferably glycolic acid and / or lactic acid.

[0012] In some embodiments, the silicon wafer texturing agent further contains a surfactant.

[0013] In some embodiments, the surfactant contains a silicon-based surfactant, more preferably contains at least one of polymethylsiloxane, a polymethylsiloxane derivative, and an alkylphenol polyoxyethylene ether.

[0014] In some embodiments, the content of the surfactant is 0.05-0.2 wt % based on the total weight of the silicon wafer texturing agent.

[0015] A second aspect of the disclosed embodiments provides the use of the aforementioned silicon wafer texturing agent in silicon wafer production; preferably, the use of the agent in the production of textured silicon wafers.

[0016] A third aspect of the embodiments of the present disclosure provides a method for texturing a silicon wafer, the method comprising: contacting a silicon wafer with the aforementioned silicon wafer texturing agent.

[0017] In some embodiments, the contacting conditions include at least: a temperature of 15-90°C, preferably 18-25°C; and a contacting time of 5-60 min, preferably 15-25 min.

[0018] In some embodiments, the contacting process includes: completely immersing the silicon wafer in the silicon wafer texturing agent.

[0019] In some embodiments, the silicon wafer is a single crystal silicon wafer and / or a multi-crystalline silicon wafer, more preferably a multi-crystalline silicon wafer.

[0020] In some embodiments, the method further comprises: cleaning the contacted silicon wafer with a solvent, cleaning with water, and drying the contacted silicon wafer.

[0021] In some embodiments, the solvent cleaning uses a strong acid solution with a hydrogen ion concentration of 1-4 mol / L, and the water cleaning uses deionized water.

[0022] In some embodiments, the immersion cleaning time of the solvent cleaning is 0.5-2 minutes.

[0023] A fourth aspect of the embodiments of the present disclosure provides a textured silicon wafer produced by the aforementioned method.

[0024] Through the above technical scheme, the silicon wafer texturing agent provided by the present invention not only has good uniformity of the silicon wafer texture, no obvious color difference between grains, and is not affected by the surface polysilicon grain size and grain orientation, but also has low raw material cost, is safe and environmentally friendly, is easy to prepare, and the texturing process operation is safe and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is a surface texture morphology image of a textured silicon wafer prepared in Example 1 of the present disclosure;

[0027] Figure 2 is a surface texture morphology image of a textured silicon wafer prepared in Example 2 of the present disclosure;

[0028] Figure 3 is a surface texture morphology image of a textured silicon wafer prepared in Example 3 of the present disclosure;

[0029] Figure 4 is a surface texture morphology image of a textured silicon wafer prepared in Example 4 of the present disclosure;

[0030] Figure 5 is a surface morphology image of a velvet silicon wafer prepared in Comparative Example 1 of the present disclosure;

[0031] Figure 6This is a surface texture morphology image of the textured silicon wafer prepared in Comparative Example 2 of the present disclosure. DETAILED DESCRIPTION

[0032] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0033] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0034] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0035] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0036] A first aspect of an embodiment of the present disclosure provides a silicon wafer texturing agent, which contains an inorganic fluoride salt, a weak acid and water, wherein the molar amount of the inorganic fluoride salt is less than the molar amount of the weak acid, and the weak acid is phosphoric acid and / or a monocarboxylic acid.

[0037] During the research process, the inventors of the present disclosure unexpectedly discovered that when a specific weak acid and an inorganic fluoride salt are mixed with water in a process in which the molar amount of the inorganic fluoride salt is less than the molar amount of the weak acid, the hydrogen ions in the weak acid and the fluoride ions in the fluoride salt form hydrofluoric acid in situ, and the in situ hydrofluoric acid is used to corrode the silicon surface to form silicon fluoride and water. The silicon fluoride further combines with the weak acid salt ions formed by the weak acid and the inorganic fluoride salt to form aromatic fluorine silicon salt. When the corrosion reaches saturation, an aromatic fluorine silicon salt pebble-like passivation layer is formed on the surface of the silicon wafer. When the texturing silicon wafer is removed from the texturing liquid and rinsed, the passivation layer dissolves, leaving behind the hills and valleys forming the textured silicon wafer surface, thereby achieving a uniform velvet surface on the silicon wafer surface with a relatively low-cost texturing agent, and at the same time, the texturing process is simple, and the operation is safe and controllable.

[0038] The texturing liquid formed based on this not only has good uniformity of the texture of the silicon wafer and no obvious color difference between the grains, and is not affected by the surface polysilicon grain size and grain orientation, but also has low raw material costs, does not contain metal ions such as copper / chromium, and has less impact on the environment; compared with the direct use of strong acid corrosion and texturing such as hydrofluoric acid, it uses weak acid with lower acidity, has less corrosiveness and volatility, and is simple and safe to operate.

[0039] In some embodiments, the molar ratio of the inorganic fluoride salt to the weak acid is 1:1.1-5, specifically 1:1.1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or any ratio between the above two values; preferably 1:2-4. The inventors have found that under this preferred embodiment, it is beneficial to improve the uniformity of the texture of the silicon wafer and the texture making effect is better.

[0040] In some embodiments, the molar concentration of the inorganic fluoride salt in the silicon wafer texturing agent is 0.3-10 mol / L, specifically 0.3 mol / L, 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L, 10 mol / L, or any value between the above two values; more preferably 0.5-1 mol / L. The inventors have found that under this preferred embodiment, it is beneficial to improve the uniformity of the silicon wafer texture surface, and the texturing process is safer.

[0041] In some embodiments, the inorganic fluoride salt is selected from at least one of ammonium fluoride, sodium fluoride, potassium fluoride and lithium fluoride, preferably ammonium fluoride and / or sodium fluoride. The inventors have found that under this preferred embodiment, it is beneficial to further improve the uniformity of the silicon wafer texture and the texture making efficiency.

[0042] In some embodiments, the monocarboxylic acid may be an aliphatic monocarboxylic acid without other substituents, or an aliphatic monocarboxylic acid containing a hydroxyl substituent. Preferably, the monocarboxylic acid is an aliphatic monocarboxylic acid containing a hydroxyl substituent. Exemplarily, the monocarboxylic acid is selected from at least one of glycolic acid, propionic acid, isopropionic acid and lactic acid, and more preferably glycolic acid and / or lactic acid. The inventors have found that under this preferred embodiment, it is beneficial to further improve the uniformity of the silicon wafer velvet surface and the velvet production efficiency.

[0043] In some embodiments, the silicon wafer texturing agent further contains a surfactant. Preferably, the surfactant contains but is not limited to a silicon-based surfactant, and more preferably contains at least one of polymethylsiloxane, polymethylsiloxane derivatives and alkylphenol polyoxyethylene ether. The alkylphenol polyoxyethylene ether can be a conventional alkylphenol polyoxyethylene ether compound, such as octylphenol polyoxyethylene ether or nonylphenol polyoxyethylene ether. The inventors have found that under this preferred embodiment, it is beneficial to further improve the uniformity of the silicon wafer texture and the texturing efficiency.

[0044] In some embodiments, based on the total weight of the silicon wafer texturing agent, the content of the surfactant is 0.05-0.2 weight%, specifically 0.05 weight%, 0.1 weight%, 0.15 weight%, 0.2 weight%, or any value between the above two values.

[0045] The silicon wafer texturing agent provided by the present disclosure can be obtained by mixing the above-mentioned raw material components, for example, the inorganic fluoride salt, weak acid, water and optional surfactant can be directly mixed to obtain the obtained product; the inorganic fluoride salt and weak acid can also be mixed with water to form corresponding solutions, and then mixed with each other or with the optional surfactant to obtain the obtained product. The mixing process can use, but is not limited to, one of a mixer and a sizing machine.

[0046] A second aspect of the disclosed embodiments provides the use of the aforementioned silicon wafer texturing agent in silicon wafer production; preferably, the use of the agent in the production of textured silicon wafers.

[0047] A third aspect of the embodiments of the present disclosure provides a method for texturing a silicon wafer, the method comprising: contacting a silicon wafer with the aforementioned silicon wafer texturing agent.

[0048] Based on the above-mentioned texturing liquid, the method for texturing a silicon wafer provided by the present disclosure not only obtains a silicon wafer with good texture uniformity and no obvious color difference between grains, but also the texturing process operation is safe and controllable.

[0049] In some embodiments, the contact conditions include at least: a temperature of 15-90° C., specifically 15° C., 30° C., 45° C., 60° C., 75° C., 90° C., or any value between the above two values, preferably 18-25° C.; a time of 5-60 min, specifically 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or any value between the above two values, preferably 15-25 min. The contact temperature is advantageously within the range of 18-25° C., which can reduce the vapor pressure and produce fewer vapor-related defects on the silicon wafer.

[0050] In some embodiments, the contacting process includes: completely immersing the silicon wafer in the silicon wafer texturing agent.

[0051] In some embodiments, the silicon wafer is a single crystal silicon wafer and / or a multi-crystalline silicon wafer, more preferably a multi-crystalline silicon wafer.

[0052] In some embodiments, the method further comprises: cleaning the contacted silicon wafer with a solvent, cleaning with water and drying the contacted silicon wafer. The inventors have found that this preferred embodiment is conducive to improving the efficiency of dissolving the passivation layer after texturing.

[0053] In some embodiments, the solvent cleaning uses a solvent that can dissolve aromatic fluorine silicon salts; preferably, the solvent cleaning uses a strong acid solution with a hydrogen ion concentration of 1-4 mol / L, and the water cleaning uses deionized water. The strong acid can be sulfuric acid and / or nitric acid.

[0054] In some embodiments, the immersion cleaning time of the solvent cleaning is 0.5-2 min, specifically 0.5 min, 1 min, 1.5 min, 2 min, or any value between the above two values.

[0055] In the present disclosure, the drying process may be natural air drying or other methods suitable for drying silicon wafers may be used.

[0056] A fourth aspect of the embodiments of the present disclosure provides a textured silicon wafer produced by the aforementioned method.

[0057] The textured silicon wafer provided by the present invention has regular cylindrical protrusions or fish-scale protrusions formed on its surface.

[0058] The present invention will be described in detail below through examples.

[0059] In the following examples, photovoltaic multicrystalline silicon wafers were provided by Xinjiang Blue Crystal New Material Technology Co., Ltd. with a product size of 6 inches × 6 inches; polymethylsiloxane was purchased from Dow Corning Corporation of the United States with a product model of PMX-200; unless otherwise specified, the remaining raw materials and reagents were conventional commercial products; and the various solutions were corresponding aqueous solutions.

[0060] Example 1

[0061] 3 mol / L phosphoric acid solution and 1 mol / L sodium fluoride solution are mixed in a volume ratio of 1:1, and 0.1% (weight percentage of the total amount of the texturing agent) of polymethylsiloxane is added to obtain a texturing agent;

[0062] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 20°C and the treatment time is 20 minutes. The silicon wafer after texturing is immersed in a 2 mol / L sulfuric acid solution for cleaning for 1 minute, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0063] Example 2

[0064] 3 mol / L phosphoric acid solution and 1 mol / L ammonium fluoride solution were mixed in a volume ratio of 1:1, and 0.2% (weight percentage of the total amount of the texturing agent) of octylphenol polyoxyethylene ether (CAS No. 9036-19-5, purchased from Nantong Huzhuo Chemical Co., Ltd., product model OP-9) was added to obtain a texturing agent;

[0065] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 18°C ​​and the treatment time is 25 minutes. The silicon wafer after texturing is immersed in a sulfuric acid solution with a concentration of 1 mol / L for cleaning for 2 minutes, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0066] Example 3

[0067] 2.4 mol / L lactic acid solution and 0.6 mol / L sodium fluoride solution were mixed in a volume ratio of 1:1, and 0.05% (weight percentage of the total amount of the texturing agent) of nonylphenol polyoxyethylene ether (CAS No. 127087-87-0, purchased from Jinan Quanxing New Materials Co., Ltd., product model NP10) was added to obtain a texturing agent;

[0068] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 25°C and the treatment time is 15 minutes. The silicon wafer after texturing is immersed in a nitric acid solution with a concentration of 4 mol / L for cleaning for 0.5 minutes, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0069] Example 4

[0070] 1 mol / L lactic acid solution, 1 mol / L phosphoric acid solution and 1 mol / L ammonium fluoride solution were mixed in a volume ratio of 1:1, and 0.05% (weight percentage of the total amount of the texturing agent) of nonylphenol polyoxyethylene ether (CAS No. 127087-87-0, purchased from Jinan Quanxing New Materials Co., Ltd., product model NP10) was added to obtain a texturing agent;

[0071] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 25°C and the treatment time is 15 minutes. The silicon wafer after texturing is immersed in a 4 mol / L nitric acid solution for cleaning for 1 minute, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0072] Example 5

[0073] The texturing agent and the textured silicon wafer were prepared according to the components and methods of Example 1, except that the concentration of the phosphoric acid solution was replaced with 1.1 mol / L.

[0074] Example 6

[0075] The texturing agent and the textured silicon wafer were prepared according to the components and methods of Example 1, except that the concentration of the phosphoric acid solution was replaced with 5 mol / L.

[0076] Example 7

[0077] The texturing agent and the textured silicon wafer were prepared according to the components and methods of Example 1, except that the concentration of the phosphoric acid solution was replaced with 15 mol / L, and the concentration of the sodium fluoride solution was replaced with 5 mol / L.

[0078] Example 8

[0079] The texturing agent and the textured silicon wafer were prepared according to the components and method of Example 1, except that the sodium fluoride solution was replaced by a lithium fluoride solution of equimolar concentration.

[0080] Example 9

[0081] The texturing agent and the textured silicon wafer were prepared according to the components and methods of Example 1, except that the 3 mol / L phosphoric acid solution was replaced by an equimolar concentration of n-propionic acid solution.

[0082] Example 10

[0083] The texturing agent and the textured silicon wafer were prepared according to the components and methods of Example 1, except that the silicon wafer after the texturing treatment was washed with deionized water and then dried to obtain the textured silicon wafer.

[0084] Comparative Example 1

[0085] The photovoltaic multicrystalline silicon wafer is immersed in deionized water for surface texturing. The texturing treatment temperature is 20° C. and the treatment time is 20 minutes.

[0086] Comparative Example 2

[0087] The photovoltaic multicrystalline silicon wafer was immersed in a 3 mol / L lactic acid solution for surface texturing. The texturing treatment temperature was 20°C and the treatment time was 20 minutes.

[0088] Comparative Example 3

[0089] 3 mol / L sodium perchlorate solution and 1 mol / L hydrofluoric acid solution are mixed in a volume ratio of 1:1, and 0.1% (weight percentage of the total amount of the texturing agent) of polymethylsiloxane is added to obtain a texturing agent;

[0090] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 20°C and the treatment time is 20 minutes. The silicon wafer after texturing is immersed in a 2 mol / L sulfuric acid solution for cleaning for 1 minute, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0091] Comparative Example 4

[0092] A 0.01 mol / L K2Cr2O7 solution is mixed with a 10 mol / L hydrofluoric acid solution, and 0.1% (by weight of the total amount of the texturing agent) of polymethylsiloxane is added to obtain a texturing agent;

[0093] The photovoltaic multicrystalline silicon wafer is immersed in a texturing agent for surface texturing. The texturing treatment temperature is 20°C and the treatment time is 20 minutes. The silicon wafer after texturing is immersed in a 2 mol / L sulfuric acid solution for cleaning for 1 minute, then taken out, cleaned with deionized water and dried to obtain a velvet silicon wafer.

[0094] Test Example 1

[0095] The surface morphology of the velvet silicon wafers obtained in Examples 1 to 4 and Comparative Examples 1 to 2 was observed using an atomic force microscope (AFM). Figures 1 to 6 .

[0096] from Figure 1 and Figure 2 It can be seen that in Example 1 and Example 2, phosphoric acid solution is used as the weak acid, and the obtained silicon wafer velvet surface has a regular fish-scale undulating texture, and the diagonal length of the fish-scale protrusions is 1-5 μm.

[0097] from Figure 3 and Figure 4 It can be seen that in Example 1 and Example 2, the weak acid used was lactic acid solution, and the obtained silicon wafer velvet surface had a regular cylindrical undulating texture, and the diameter of the cylindrical protrusions was 1-3 μm.

[0098] from Figure 5 and Figure 6 It can be seen that the silicon wafer surface after being treated in Comparative Example 1 has no obvious texture, and the surface roughness is much lower than that of Examples 1 to 4. Comparative Example 2 uses only a weak acid solution for texturing and cannot obtain a continuous and regular velvet surface, and the surface roughness rate is higher than that of Comparative Example 1.

[0099] Therefore, the texturing agent prepared in the embodiments provided in the present disclosure has low raw material cost, is safe and environmentally friendly, and is easy to prepare; the processed polycrystalline silicon wafer has good texture uniformity, no obvious color difference between grains, is not affected by the surface polycrystalline silicon grain size and grain orientation, and the texture size is small and uniform.

[0100] Test Example 2

[0101] The reflectivity of the velvet silicon wafers obtained in Examples 1 to 10 and Comparative Examples 1 to 4 was tested using a Shimadzu UV-1900i ultraviolet-visible-near-infrared spectrometer; the velvet silicon wafers obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were made into solar cells using the same process conditions and procedures. The specific process of making the solar cells is as follows: a PN junction is prepared on the surface of the velvet silicon wafer by a POCl3 liquid diffusion source thermal diffusion method, and the diffusion temperature is adjusted to 830°C and the time is 300 min; the diffused polycrystalline silicon wafer is placed in an etching tank, and the etching is directed to the velvet silicon wafer. A mixed etching solution of 360 g / L HNO3 and 45 g / L HF is added into the tank, the etching temperature is adjusted to 7°C, and the etched polycrystalline silicon wafers are alkali washed, acid washed, washed with water and dried before unloading; silicon nitride is deposited on the front surface of the etched polycrystalline silicon wafer by PECVD for coating, and the coating thickness is controlled at 79 nm, and the coating refractive index is controlled at 2.10; the back electrode, back electric field and front electrode are printed in sequence on the coated polycrystalline silicon wafer, and the auxiliary grid line of the front electrode should be parallel to the diamond wire cutting mark to obtain a battery cell.

[0102] The electrical properties of the cells were tested using the SS-X50 solar simulator from Enlighten Technology, including the open-circuit voltage, short-circuit current and photoelectric conversion efficiency (PCE). The data are shown in Table 1. The open-circuit voltage refers to the voltage at which the cell is not connected to a load (i.e., open circuit) under standard test conditions (temperature 25°C, AM1.5 spectrum conditions, irradiance 1000W / m 2 ) terminal voltage. The short-circuit current refers to the short-circuit current under standard test conditions (temperature 25°C, AM1.5 spectrum conditions, irradiance 1000W / m 2 ) is the output current when the cell is short-circuited. Photovoltaic conversion efficiency (PCE) is the primary indicator for measuring solar cell performance, which directly reflects the ability of the cell to convert light energy into electrical energy; Test conditions: Under standard test conditions (temperature 25°C, AM1.5 spectrum conditions, irradiance 1000W / m 2 ) under the test conditions; Test method: By applying different voltages and measuring the corresponding current, the current-voltage (IV) curve is obtained, and key parameters such as open circuit voltage (Voc), short circuit current density (Jsc) and maximum power point (MPP) are read from the curve to calculate the PCE value of the battery cell.

[0103] Table 1

[0104] serial number Reflectivity(%) Opening voltage / V Short circuit current / A PCE / % Example 1 17.6 0.647 9.207 19.3 Example 2 18.1 0.648 9.119 19.2 Example 3 17.5 0.648 9.188 19.3 Example 4 18.8 0.646 9.067 18.9 Example 5 19.3 0.646 9.006 18.7 Example 6 19.6 0.645 8.998 18.3 Example 7 19.1 0.645 9.002 18.6 Example 8 21.1 0.642 8.828 18.1 Example 9 22.2 0.642 8.907 18.2 Example 10 23.3 0.641 8.627 17.6 Comparative Example 1 31.1 0.623 8.403 15.2 Comparative Example 2 30.3 0.624 8.459 15.4 Comparative Example 3 22.5 0.644 8.804 18.3 Comparative Example 4 24.3 0.643 8.928 18.1

[0105] The reflectivity of silicon wafers after texturing with the silicon wafer texturing agent provided by the present invention is significantly lower than that of silicon wafers after texturing with conventional texturing agents. After being made into battery cells, various electrical performance parameters are significantly improved. In addition, the raw material cost is low, it is safe and environmentally friendly, easy to prepare, and the texturing process operation is safe and controllable.

[0106] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0107] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A silicon wafer texturing agent, characterized in that: The silicon wafer texturing agent contains an inorganic fluoride salt, a weak acid and water, wherein the molar amount of the inorganic fluoride salt is less than the molar amount of the weak acid, and the weak acid is phosphoric acid and / or monocarboxylic acid.

2. The silicon wafer texturing agent according to claim 1, characterized in that: The molar ratio of the inorganic fluoride salt to the weak acid is 1:1.1-5, preferably 1:2-4; Preferably, the molar concentration of the inorganic fluoride salt in the silicon wafer texturing agent is 0.3-10 mol / L, more preferably 0.5-1 mol / L.

3. The silicon wafer texturing agent according to claim 1, characterized in that: The inorganic fluoride salt is selected from at least one of ammonium fluoride, sodium fluoride, potassium fluoride and lithium fluoride; preferably ammonium fluoride and / or sodium fluoride; Preferably, the monocarboxylic acid is selected from at least one of glycolic acid, propionic acid, isopropionic acid and lactic acid, and more preferably glycolic acid and / or lactic acid.

4. The silicon wafer texturing agent according to any one of claims 1 to 3, characterized in that: The silicon wafer texturing agent also contains a surfactant; Preferably, the surfactant contains a silicon-based surfactant, more preferably contains at least one of polymethylsiloxane, polymethylsiloxane derivatives and alkylphenol polyoxyethylene ether; Preferably, based on the total weight of the silicon wafer texturing agent, the content of the surfactant is 0.05-0.2 weight %.

5. Use of the silicon wafer texturing agent according to any one of claims 1 to 4 in silicon wafer production; preferably in the production of textured silicon wafers.

6. A method for texturing a silicon wafer, characterized in that: The method comprises: contacting a silicon wafer with the silicon wafer texturing agent described in any one of claims 1 to 4.

7. The method according to claim 6, characterized in that The contacting conditions at least include: a temperature of 15-90°C, preferably 18-25°C; and a time of 5-60 min, preferably 15-25 min.

8. The method according to claim 6 or 7, characterized in that: The contacting process includes: completely immersing the silicon wafer in the silicon wafer texturing agent; Preferably, the silicon wafer is a single crystal silicon wafer and / or a multi-crystalline silicon wafer, more preferably a multi-crystalline silicon wafer.

9. The method according to claim 6 or 7, characterized in that: The method further comprises: cleaning the silicon wafer after the contacting with a solvent, cleaning with water and drying the silicon wafer; Preferably, the solvent cleaning uses a strong acid solution with a hydrogen ion concentration of 1-4 mol / L, and the water cleaning uses deionized water; Preferably, the immersion cleaning time of the solvent cleaning is 0.5-2 min.

10. A textured silicon wafer obtained by the method according to any one of claims 6 to 9.

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