CN114823943A - Textured structure, monocrystalline silicon wafer including the same, texturing method and application - Google Patents

Abstract

The present invention relates to the field of monocrystalline silicon cell manufacturing, and in particular to a textured structure. The textured structure includes a single textured structure that is randomly distributed and is an octagonal pyramid structure. Octagonal pyramid. The invention overcomes the defects in the prior art that the specific surface area of the common tetrahedral pyramid structure is small, resulting in short optical path, high reflectivity and poor light trapping effect. The textured structure of the present invention includes a single textured structure in the form of an octagonal pyramid structure. Therefore, on the premise of the same bottom surface area, the surface area of the octagonal pyramid structure can be effectively improved, thereby increasing the optical path and reducing the impact on The reflectivity of light makes the suede structure better for trapping light.

Description

Textured structure, monocrystalline silicon wafer including the same, texturing method and application

technical field

The present invention relates to the field of single crystal silicon cell manufacturing, in particular to a textured structure, a single crystal silicon wafer containing the same, a texture making method and application.

Background technique

The rapid economic growth of all countries in the world and the increasing demand for energy by humans have led to the rapid shortage of non-renewable resources such as oil, natural gas, and coal mines. Environmental pollution and energy shortages have become factors that seriously restrict social development.

Solar energy is a real green energy, because it is inexhaustible and has become an urgent need of human society. An important way to apply solar energy to life is photovoltaic power generation. Silicon wafers are the most important raw materials in the photovoltaic power generation industry. By increasing the absorption of light on the surface of the silicon wafer, not only the efficiency of the crystalline silicon solar cell can be improved, but also the production cost of the crystalline silicon solar cell can be reduced. The chemical texturing technology is used to corrode the surface of the silicon wafer to produce a textured surface with uniform size, good roughness and suitable reflectivity, which can effectively improve the photoelectric conversion efficiency of solar cells. means.

my country's photovoltaic market has also undergone tremendous changes in recent years. Some companies have mastered advanced single crystal production processes and become leaders in the global photovoltaic market. Among them, the texturing additives used in the texturing process play a very important role in the single crystal texturing process. problems, such as uneven suede, raindrops, mottled, etc.

The textured textures obtained by the traditional alkali texturing additives are all pyramid textured textures, including forward pyramids and inverted pyramids, the difference is only in the size and height of the pyramids.

For example, the preparation method of a crystalline silicon surface inverted pyramid textured structure with the application number of CN201910160490.4, firstly forms a layer of alumina particles on the surface of the silicon wafer through pretreatment, and then alkali-processes the pretreated silicon wafer fleece to obtain an inverted pyramid textured structure; the alumina particle layer is mainly composed of dispersed alumina particles. The preparation method of the inverted pyramid textured surface structure on the surface of the crystalline silicon of the invention is suitable for both monocrystalline silicon wafers and polycrystalline silicon wafers, and can form a uniform, fine and dense inverted pyramid textured textured structure on the surface of the silicon wafer.

Application No. CN202110953879.1 A texturing additive for rapid texturing and its application, the texturing additive includes the following components by mass percentage: 0.5% to 10% of nucleating agent, 1% of texturing catalyst ～10%, surfactant 0.01%～0.05%, defoamer 0.05%～0.5%, and the balance is deionized water. When the single-sided corrosion depth of the texturing additive of the invention reaches 1.5um, the complete growth of the normal pyramid can be realized, and the texture size of 2um can be obtained.

Although the cell efficiency of these existing pyramid-shaped suede surfaces can still be maintained at a high level, due to the small specific surface area of the pyramidal structure of the ordinary tetrahedron, its optical path is short, which makes its reflectivity high and trapped in the surface. The light effect is poor.

SUMMARY OF THE INVENTION

The present invention provides a textured structure in order to overcome the defects in the prior art that the specific surface area of the common tetrahedral pyramid structure is small, resulting in a short optical path, high reflectivity and poor light trapping effect. , A single crystal silicon wafer comprising the same, a texturing method and an application to overcome the above-mentioned defects.

In order to realize the object of the present invention, the present invention is realized through the following technical solutions:

The first object of the present invention is to provide a suede structure,

The textured structure comprises a single textured structure that is randomly distributed and is an octagonal pyramid structure;

The bottom surface of the single flocking structure is octagonal, and the part above the bottom surface is octagonal.

The textured structure in the present invention includes a single textured structure in the form of an octagonal pyramid structure. Therefore, on the premise of the same bottom surface area, the surface area of the octagonal pyramid structure can be effectively improved, thereby increasing the optical path and reducing the impact on The reflectivity of light makes the suede structure better for trapping light.

Moreover, compared with the normal pyramid textured surface of the traditional quadrangular pyramid structure, the textured surface structure is flatter, so in the subsequent passivation stage, the contact between the silicon wafer and the slurry is better.

In addition, in terms of electrical properties, the single-textured structure of the octagonal pyramid structure also increases the short-circuit current and fill factor, thereby improving the conversion efficiency of the solar cell.

Preferably, the side length of the bottom surface of the single-textured structure is 0.3-1 μm;

The height of the single textured structure is 0.7-1.0 μm;

The included angle of the top of each side edge of the single flocking structure is 45°-60°.

Preferably, the specific surface area of the textured structure is greater than or equal to 1.5.

The second object of the present invention is to provide a single crystal silicon wafer,

The above-mentioned textured structure is distributed on the surface of the single crystal silicon wafer.

Preferably, the distribution density of the single textured structure in the textured structure on the surface of the single crystal silicon wafer is 10 ⁴ -10 ⁶ pieces/mm².

The third object of the present invention is to provide a single crystal silicon wafer texturing method,

Include the following steps:

(1) Prepare the lye solution, then add the texturing additive to the lye solution, and stir evenly to obtain the texturing solution;

(2) placing the silicon wafer in a texturing solution for texturing to obtain a texturing silicon wafer having the textured surface structure described in the above item;

The texturing additives, calculated by weight percentage, include: 1-5 wt % of alkyl sulfonate, 0.15-1 wt % of polyacrylamide, 0.5-5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

The inventor of the present invention discovered by chance in daily experiments that when the above-mentioned texturing additive is added to the texturing liquid, the surface of the silicon wafer can be induced to form a single textured structure with an octagonal pyramid structure during the texturing process.

The reason is speculated that the texturing additive in the present invention contains a variety of different surfactants at the same time, and these surfactants can induce different crystal planes of the silicon crystals, so that the different crystal planes of the silicon crystals are in the texturing process during the texturing process. When corroded by sodium hydroxide, its corrosion effect can show anisotropy, so that a textured surface with a uniform and stable structure of octagonal pyramid structure is formed after the texturing is completed.

Compared with the traditional tetrahedral regular pyramid structure, the textured surface of the octagonal pyramid structure formed by the texturing additive in the present invention effectively increases the surface area of the octagonal pyramid textured structure, thereby increasing the optical path and reducing the reflectivity for light, so that the The suede structure has better trapping effect for light. And compared with the traditional positive pyramid texture, the texture structure is flatter, so in the subsequent passivation stage, the contact between the silicon wafer and the slurry is better. In addition, in terms of electrical properties, the octagonal suede structure also increases the short-circuit current and fill factor, thereby improving the conversion efficiency of solar cells.

In addition, the textured surface of the inverted pyramid structure in the prior art often requires the participation of metal ions during the texturing process. After the texturing is completed, a part of the residual metal ions will enter the interior of the inverted pyramid structure, which is difficult to clean, and these residues After the metal ions enter the silicon crystal, they will form a recombination center with the crystalline silicon, thereby affecting the cell efficiency. However, since the present invention does not require the participation of metal ions in the texturing process, the above-mentioned defects can be effectively avoided.

In addition, the inventors of the present invention found that the content of each component in the above-mentioned texturing additive has a significant influence on the final texturing effect. When the content of alkyl sulfonate is less than 1%, although it can form a single textured structure with an octagonal pyramid structure, it cannot cover the entire surface of the silicon wafer, and there will still exist between the single textured structures of the octagonal pyramid structure. More voids make its performance unable to meet practical application requirements. When the content of alkyl sulfonate is greater than 5%, it will cause the disappearance of the octagonal suede structure, and instead become an ordinary tetrahedral pyramid structure.

When the content of polyacrylamide is lower than 0.15%, the surface of the silicon wafer cannot be velvet, and if it is higher than 1%, the suede surface is too small, which is not conducive to improving the light trapping effect of the silicon wafer.

When the alkylphenol polyoxyethylene ether content is lower than 0.5%, it will also cause the problem that the surface of the silicon wafer cannot be velvet, and when the alkylphenol polyoxyethylene ether content is higher than 0.5%, it will cause the suede to appear dirty. pollution situation.

Preferably, the alkyl carbon number of the alkyl sulfonate is 12 or more.

The inventors of the present invention found that the carbon chain length in the alkyl sulfonate has a significant effect on the overall texturing effect. The inventor's experiments found that when the number of carbon atoms in the alkyl sulfonate is less than 12, the critical micelle concentration of the alkyl sulfonate will be higher, resulting in a decrease in its decontamination ability, so corrosion during the texturing process will occur. The generated product cannot be quickly removed, which delays the reaction between the alkali and the silicon wafer, resulting in poor induction effect on the silicon wafer and unable to form a complete octagonal suede structure. In the present invention, after the alkyl sulfonate with the alkyl carbon number of 12 or more is selected, its decontamination ability is greatly improved, so the by-products generated during the texturing process can be quickly wrapped by the alkyl sulfonate to be separated from the silicon wafer surface, so that the reaction between the silicon wafer and the alkali can be more rapid, which is beneficial to induce the formation of an octagonal suede structure on the surface of the silicon wafer.

Preferably, the alkyl sulfonate is sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, sodium tridecyl sulfonate, sodium hexadecyl sulfonate, n-octadecyl sulfonate A combination of one or more of the sodium salts.

Preferably, the polyacrylamide is a nonionic polyacrylamide.

Preferably, the molecular weight of the polyacrylamide is 5-10 million.

The inventors of the present invention found in experiments that the molecular weight of polyacrylamide has a great influence on the finally formed suede, wherein when the molecular weight of polyacrylamide is less than 5 million, it has a great influence on the sodium silicate produced in the texturing process. The adsorption and sedimentation effect of the ion is poor, which is not conducive to the reaction between the final lye and the silicon wafer. However, when the molecular weight of polyacrylamide is greater than 10 million, the viscosity of the overall texturing solution will be high, and the hydrogen on the surface of the silicon wafer cannot be removed in time during the texturing process, resulting in more defects in the silicon wafer after texturing. many. Therefore, when the molecular weight of polyacrylamide is selected to be 5-10 million, the alkali in the texturing solution can quickly react with the silicon wafer, and at the same time, the hydrogen formed in the reaction process can be quickly discharged, preventing the silicon wafer from being damaged. Defects such as raindrops and mottles are formed on the surface.

Preferably, the added mass of the texturing additive in the step (1) accounts for 0.2-0.5% of the entire texturing solution.

Preferably, in the step (2), the texturing temperature is 70-90° C., and the texturing time is 5-10 minutes.

The fourth object of the present invention is to provide the application of the textured structure or the single crystal silicon wafer in a solar cell.

Therefore, the present invention has the following beneficial effects:

(1) Compared with the traditional pyramid structure, the single textured textured structure of the octagonal pyramid structure prepared by the present invention has a larger specific surface area, thereby increasing the optical path and reducing the reflectivity for light, so that the textured surface has a larger specific surface area. The structure is better for trapping light.

(2) Compared with the normal pyramid textured surface of the traditional quadrangular pyramid structure, the textured surface structure is flatter, so in the subsequent passivation stage, the contact between the silicon wafer and the slurry is better.

(3) In terms of electrical properties, the single-textured structure of the octagonal pyramid structure also increases the short-circuit current and fill factor, thereby improving the conversion efficiency of solar cells.

Description of drawings

Fig. 1 is an electron micrograph of the textured structure of the octagonal pyramid on the surface of a single crystal textured silicon wafer.

FIG. 2 is an enlarged view of the single-textured structure of the octagonal pyramid structure.

Figure 3 is a picture of the textured surface formed when the content of alkyl sulfonate is less than 1%.

Figure 4 is a picture of the textured texture formed when the content of alkyl sulfonate is greater than 5%.

Figure 5 is a picture of the textured structure formed when the content of polyacrylamide is less than 0.15%.

Figure 6 is a picture of the textured texture formed when the content of polyacrylamide is higher than 1%.

Figure 7 is a picture of the textured texture formed when the content of alkylphenol ethoxylate is less than 0.5%.

Figure 8 is a picture of the textured texture formed when the content of alkylphenol ethoxylate is higher than 5%.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention referred to in the following description are generally only some embodiments of the present invention, not all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Example 1

A texturing additive comprises 1 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 2

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 3

A texturing additive comprises 3 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 4

A texturing additive comprises 5 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 5

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.15 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 6

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.8 wt % of nonionic polyacrylamide with a molecular weight of 5 to 10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 7

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 1 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 8

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 0.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 9

A texturing additive, comprising 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5 to 10 million, 2.5 wt % of alkylphenol polyoxyethylene ether, and the remainder being water.

Example 10

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 4 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 11

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 12

A texturing additive, 2 wt % of sodium dodecyl benzene sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5 to 10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water .

Example 13

A texturing additive comprises 2 wt % of sodium cetyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Example 14

A texturing additive, 2 wt % of sodium n-octadecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5 to 10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water .

Comparative Example 1

A texturing additive comprises 0.5 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 2

A texturing additive comprises 8 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 3

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.1 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 4

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 1.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 5

A texturing additive, comprising 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5 to 10 million, 0.3 wt % of alkylphenol polyoxyethylene ether, and the balance of water.

Comparative Example 6

A texturing additive, comprising 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 5.5 wt % of alkylphenol polyoxyethylene ether, and the balance of water.

Comparative Example 7

A texturing additive comprises 2 wt % of sodium n-octane sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 8

A texturing additive comprises 2 wt % of sodium 1-decane sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 5-10 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 9

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 2 to 4 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

Comparative Example 10

A texturing additive comprises 2 wt % of sodium dodecyl sulfonate, 0.5 wt % of nonionic polyacrylamide with a molecular weight of 10-15 million, 1.5 wt % of alkylphenol polyoxyethylene ether, and the balance is water.

The formulas of the texturing additives prepared in Examples 1 to 14 and Comparative Examples 1 to 10 are summarized in Table 1 below.

Table 1

According to the formulas in Examples 1-14 and Comparative Examples 1-10, each component was weighed in turn, stirred in a 60°C water bath for 3 hours; then left to stand until the foam completely disappeared, and finally filtered with a filter element with a pore size of 10 μm to obtain a fleece additives.

The preparation of the texturing liquid and the texturing method are as follows:

0.93 wt % NaOH and 0.4 wt % texturing additives were added during texturing of single crystal silicon wafers to form a texturing solution, which was stirred evenly and reacted at 80°C for 7 min to obtain single crystal texturing silicon wafers.

(In this application document, 0.4 wt % is selected as the reference addition measurement in the selection, but after the experiment of the inventor, the addition amount of the texturing additive is in the range of 0.2~0.5wt%, and the texturing temperature is in the range of 70~90℃. , can form an octagonal suede structure on the surface of the silicon wafer).

By adding the texturing additives in Examples 1 to 14 of the present invention, all of them can form a textured structure of an octagonal pyramid on the surface of the single-crystal texturing silicon wafer. The single-crystal texturing prepared by the texturing additives in Example 2 The electron micrograph of the surface of the silicon wafer is shown in Fig. 1, and Fig. 2 is an enlarged view of the textured structure of the octagonal pyramid.

It can be seen from Figures 1 and 2 that the textured textured structure of the octagonal pyramid structure prepared by the present invention is stable and can be closely and evenly distributed on the surface of the silicon wafer. The height is in the range of 0.7-1.0 μm, and the angle between the tops of each side of the single-textured structure is 45°-60°.

Comparing Examples 1 to 4 with Comparative Examples 1 to 2, we found that the addition amount of alkyl sulfonate has an important influence on the formation of the octagonal pyramid textured structure. When the content of alkyl sulfonate is less than 1%, although the texture of the octagonal pyramid structure can be formed, it cannot cover the entire surface of the silicon wafer (as shown in Figure 3), and there will still be suede between the octagonal pyramid textured structure. There are many voids, which makes its performance unable to meet practical application requirements. However, when the content of alkyl sulfonate is greater than 5%, the octagonal suede structure will disappear, and instead it will become an ordinary tetrahedral pyramid structure (as shown in Figure 4).

Comparing Examples 2, 5-7 with Comparative Examples 3-4, we found that the addition amount of polyacrylamide also has an important influence on the formation of the octagonal pyramid textured structure. When the content of polyacrylamide is lower than 0.15%, the surface of the silicon wafer cannot be velvet (as shown in Figure 5), and if the content of polyacrylamide is higher than 1%, the velvet surface will be too small (as shown in Figure 6), which is not conducive to improvement. The improvement of the light trapping effect on the surface of the silicon wafer.

Comparing Examples 2, 8-11 with Comparative Examples 5-6, we found that the addition amount of alkylphenol polyoxyethylene ether also has an important influence on the formation of the octagonal pyramid textured structure. When the content of alkylphenol polyoxyethylene ether is lower than 0.5%, it will also cause the problem that the surface of the silicon wafer cannot be lint (as shown in Figure 7), and when the content of alkylphenol polyoxyethylene ether is higher than 5%, the This will cause the suede to become dirty (as shown in Figure 8).

Comparing Examples 2, 12-14 with Comparative Examples 7-8, we found that the length of the carbon chain in the alkyl sulfonate also has an important influence on the formation of the octagonal pyramid suede structure. When the carbon length is less than 12, it will also lead to the failure to form a complete octagonal pyramid structure, and only a common tetrahedral pyramid structure can be formed.

We also found that the molecular weight of polyacrylamide also has an important effect on the formation of the octagonal pyramid textured structure. When the molecular weight of polyacrylamide is less than 5 million, its adsorption and sedimentation effect on the sodium silicate produced in the texturing process is poor, which is not conducive to the reaction between the final lye and the silicon wafer. However, when the molecular weight of polyacrylamide is greater than 10 million, the viscosity of the overall texturing solution will be high, and the hydrogen on the surface of the silicon wafer cannot be removed in time during the texturing process, resulting in more defects in the silicon wafer after texturing. many. Therefore, when the molecular weight of polyacrylamide is selected to be 5-10 million, the alkali in the texturing solution can quickly react with the silicon wafer, and at the same time, the hydrogen formed in the reaction process can be quickly discharged, preventing the silicon wafer from being damaged. Defects such as raindrops and mottles are formed on the surface.

Finally, with the texturing additive in Example 2 of the present invention and several ordinary pyramid textured additives that can generate the same size and height on the market at the same temperature, water, NaOH dosage, additive dosage, and reaction time, the texturing experiment was carried out, Then, randomly select 5 points on the microscope to test the specific surface area and take the average value. At the same time, the reflectivity of the silicon wafers obtained after texturing was also tested.

in:

Additive ① The formula is as follows: sodium cellulose sulfonate 0.01%, sodium carboxymethyl cellulose 0.1%, tannic acid 0.01%, hyperbranched polyacrylamide 0.05%, potassium hydroxide 1%, and the balance is water.

The formulation of additive ② is as follows: 0.1% sodium lignosulfonate, 0.01% glycerol polyether, 0.3% hydroxyethyl-β-cyclodextrin, 0.5% 1,4-bis(2-hydroxyethyl)piperidine oxazine, the balance being water.

The formula of additive ③ is as follows: 1% polyethylene glycol-600, 0.1% sodium benzoate, 1% citric acid, 1% hydrolyzed polymaleic anhydride, 0.1% g sodium acetate, and the balance is water.

The formula of additive ④ is as follows: 5% hydrolyzed polyacrylonitrile sodium salt, 2% choline, 0.02% sodium lauryl sulfate, 0.15% toluenediamine polyether polyol with a viscosity of 12000mPa•s, and the balance is water.

Additive ⑤ The formula is as follows: sodium lignosulfonate 0.05%, sodium polynaphthalene formaldehyde sulfonate 0.0001%, polyethylene glycol 1.3%, diethylene glycol butyl ether 3.5%, potassium perfluorohexyl sulfonate 1.5%, the balance is water.

Add 10L of water, 93g of NaOH, 40g of additives to the reaction tank, put in a single-crystal silicon wafer when the water temperature rises to 80°C, and react for 7 minutes. Reflectance test, the test results are shown in Table 2 below.

Table 2

product name Example 2 Additive ① Additive ② Additives ③ Additives④ Additives⑤ Pyramid size/μm 1.64 1.6 1.59 1.68 1.7 1.65 Pyramid height/μm 0.89 0.86 0.85 0.9 0.92 0.88 specific surface area 1.52 1.28 1.3 1.35 1.37 1.33 Reflectivity/% 9.56 9.73 9.85 9.97 9.65 10.12

Wherein: the specific surface area is defined as follows: surface area after texturing (μm ² )/surface area before texturing (μm ² ).

It can be seen from the data in the above table that the suede structure of the octagonal pyramid structure prepared by the present invention has a significantly increased specific surface area when the size is close, so that the optical path after the light is irradiated on the surface of the silicon wafer is significantly increased, thereby The reflectivity for light is reduced, so that the suede structure has better trapping effect for light.

Claims (10)

1. a suede structure, is characterized in that, It contains a random distribution of single textured structures in an octagonal pyramid structure; The bottom surface of the single flocking structure is octagonal, and the part above the bottom surface is octagonal. 2. A kind of suede structure according to claim 1, is characterized in that, The side length of the bottom surface of the single-textured structure is 0.3-1 μm; The height of the single textured structure is 0.7-1.0 μm; The included angle of the top of each side edge of the single flocking structure is 45°-60°. 3. a kind of suede structure according to claim 1 or 2, is characterized in that, The specific surface area of the textured structure is greater than or equal to 1.5. 4. A single crystal silicon wafer, characterized in that, The textured structure according to any one of claims 1 to 3 is distributed on the surface of the single crystal silicon wafer. 5. A kind of monocrystalline silicon wafer according to claim 4, is characterized in that, The distribution density of the single textured structure in the textured structure on the surface of the single crystal silicon wafer is 10 ⁴ -10 ⁶ /mm². 6. A single crystal silicon wafer texturing method, characterized in that, Include the following steps: (1) Prepare the lye solution, then add the texturing additive to the lye solution, and stir evenly to obtain the texturing solution; (2) placing the silicon wafer in a texturing solution for texturing to obtain a texturing silicon wafer having the textured structure according to any one of claims 1 to 3; The texturing additives are calculated by weight percentage and include: 1-5 wt % of alkyl sulfonate, 0.15-1 wt % of polyacrylamide, 0.5-5 wt % of alkylphenol polyoxyethylene ether, and the balance is water. 7 . The method for texturing a single crystal silicon wafer according to claim 6 , wherein, The added mass of the texturing additive in the step (1) accounts for 0.2-0.5% of the whole texturing solution. 8. The method for texturing a single crystal silicon wafer according to claim 6 or 7, wherein, Among the texturing additives: The alkyl carbon number of the alkyl sulfonate is greater than or equal to 12; The polyacrylamide is non-ionic polyacrylamide, and its molecular weight is 5-10 million. 9 . The method for texturing a single crystal silicon wafer according to claim 6 , wherein, In the step (2), the texturing temperature is 70-90° C., and the texturing time is 5-10 minutes. 10 . The application of the textured structure according to any one of claims 1 to 3 or the monocrystalline silicon wafer according to claim 4 or 5 in solar cells. 11 .

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