An alkali etching additive applied to surface texturing of monocrystalline silicon cell pieces

Abstract

The present application relates to the technical field of alkali etching additive, and particularly relates to an alkali etching additive applied to surface texturing of monocrystalline silicon cell piece. The technical scheme comprises the following raw material compositions: nucleation main agent 3-5%, surface adjusting agent 1-2%, defoaming agent 0.1-0.3%, pH value adjusting agent 0.5-2%, toughness agent 5-8%, and deionized water in remainder. The alkali etching prepared by the present application is uniform in etching, long in service life, reduces the reflectivity of the monocrystalline silicon cell piece, improves the light absorption of the monocrystalline silicon cell piece, ensures the good toughness of the cell surface under the condition of roughness increase, avoids cracks caused by etching, increases the toughness of the cell piece, and guarantees the performance and service life of the cell piece.

Description

Technical Field

[0001] This invention relates to the field of alkaline etching additives, and more particularly to an alkaline etching additive for texturing the surface of monocrystalline silicon solar cells. Background Technology

[0002] With the rapid development of my country's photovoltaic power generation industry, the demand for monocrystalline silicon solar cells is increasing. In the manufacturing process of monocrystalline silicon solar cells, in order to effectively absorb light energy and obtain greater photoelectric conversion efficiency, the surface of monocrystalline silicon is often textured to form an uneven pyramidal textured surface. This significantly reduces light reflection and improves the absorption of light by the silicon wafer. However, due to the anisotropy of monocrystalline silicon, alkaline etching is generally used for monocrystalline silicon solar cells. Traditional alkaline etching suffers from problems such as uneven etching, low lifespan, and excessively high reflectivity. This invention introduces an alkaline etching additive specifically used for texturing the surface of monocrystalline silicon solar cells, which can effectively solve these problems.

[0003] Alkaline etching additives increase the surface roughness of monocrystalline silicon, leading to lattice defects and cracks, which directly affect the performance of solar cells. Therefore, this application proposes an alkaline etching additive for surface texturing of monocrystalline silicon solar cells. Summary of the Invention

[0004] The purpose of this invention is to address the problem in the prior art that may lead to increased surface roughness of monocrystalline silicon, resulting in lattice defects and cracks, by proposing an alkaline etching additive for surface texturing of monocrystalline silicon solar cells.

[0005] The technical solution of this invention: An alkaline etching additive for texturing the surface of monocrystalline silicon solar cells, comprising the following raw materials:

[0006] Nucleation agent 3-5%,

[0007] 1-2% of nap conditioner

[0008] Defoamer 0.1-0.3%,

[0009] pH adjuster 0.5-2%,

[0010] Toughening agent 5-8%,

[0011] Deionized water balance;

[0012] The toughening agent includes ethylene glycol, polyethylene glycol, and calcium propionate.

[0013] Optionally, the toughening agent comprises the following raw materials in parts by weight:

[0014] 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol, and 0.8 parts calcium propionate.

[0015] Optionally, the nucleation agent is dodecylbenzyldimethylammonium chloride.

[0016] Optionally, the suede conditioner is any one of sodium gluconate, EDTA, sodium citrate, and sodium tripolyphosphate.

[0017] Optionally, the defoamer is Dow Corning silicone defoamer 3168.

[0018] Optionally, the pH adjuster is trisodium phosphate.

[0019] Optionally, the toughening agent is prepared by the following method:

[0020] Ethylene glycol and calcium propionate were added to a constant-temperature, sealed ultrasonic reactor and stirred for 30 minutes. Then, polyethylene glycol was added, the ultrasonic reactor was sealed, and the temperature was set to 80°C for 45 minutes to obtain a toughening agent.

[0021] Optionally, the preparation method of the alkaline etching additive includes the following steps:

[0022] Step 1: Dissolve sodium gluconate and pH adjuster in water according to the specified ratio to form a liquid.

[0023] Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃ and the time to 45 minutes to obtain the toughening agent.

[0024] Step 3: At a speed of 30-40 r / min, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent and defoamer 3168 to the above liquid in sequence according to the proportion. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

[0025] Optionally, in step one, a stainless steel mixer is used for mixing, and the mixing speed is 400 rad / min.

[0026] Optional components include the following raw materials:

[0027] nucleation agent 3%,

[0028] 1% suede conditioner

[0029] Defoamer 0.1%,

[0030] pH adjuster 2%,

[0031] 5% toughening agent

[0032] Deionized water balance;

[0033] The toughening agent includes ethylene glycol, polyethylene glycol, and calcium propionate.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] 1. The key point and protection point of this invention is the use of dodecylbenzyldimethylammonium chloride as the nucleation agent. Utilizing its super adsorption capacity, it can be effectively adsorbed on the silicon wafer surface to hinder the reaction between OH- and the silicon wafer, thereby forming textured formation points. As the reaction proceeds, the textured formation points eventually become the apex of the textured pyramid. The alkaline etching solution prepared is uniform and has a long service life. At the same time, it reduces the reflectivity of the monocrystalline silicon solar cell and improves the light absorption of the monocrystalline silicon solar cell.

[0036] 2. This invention involves adding ethylene glycol and calcium propionate to a constant-temperature, sealed ultrasonic reactor and stirring to mix them. Then, polyethylene glycol is added, and the ultrasonic reactor is sealed. This process yields a toughening agent incorporated into an alkaline etching additive, which ensures that the silicon wafer surface maintains good toughness even with increased roughness, preventing crack formation. This increases the toughness of the solar cell and guarantees its performance and lifespan.

[0037] In summary, the alkaline etching solution prepared by this invention provides uniform etching and a long service life. At the same time, it reduces the reflectivity of monocrystalline silicon solar cells and improves their light absorption. This ensures that the surface of the cell maintains good toughness even with increased roughness, preventing etching from causing cracks, increasing the toughness of the solar cells, and guaranteeing their performance and service life. Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0039] The reaction equation between silicon wafers and alkaline solution is Si + 2NaOH + H₂O = Na₂SiO₃ + 2H₂↑. Experimental analysis reveals that this reaction can be described in five steps: ① the reactants diffuse to the silicon wafer surface; ② the silicon wafer surface adsorbs reacting and non-reacting ions; ③ a surface reaction occurs; ④ the reaction products desorb; and ⑤ the reaction products diffuse from the silicon surface into the solution. From this process, it is clear that the more ions adsorbed on the silicon wafer surface, the more it hinders the reaction between OH⁻ and silicon. This leads to the formation of textured, velvety surfaces—the apex of a pyramid—where non-reacting ions are adsorbed. Therefore, step ② is the key step in the texturing of the monocrystalline silicon surface. Dodecylbenzyldimethylammonium chloride has a strong adsorption capacity, effectively adsorbing onto the silicon wafer surface to inhibit the reaction between OH- and the silicon wafer, and forming textured spots. The complexing agent, as a textured surface conditioner, has a strong complexing ability, which can effectively capture the ions generated in the reaction, accelerate the desorption of reaction products, and give the silicon wafer surface a large and uniform pyramid texture. The defoamer can effectively remove the hydrogen bubbles generated in the reaction from the silicon wafer surface, effectively solving the problem of floating or jumping wafers caused by the adsorption of hydrogen on the silicon wafer. The pH adjuster can keep the entire alkaline etching solution within a relatively stable pH range, extending the service life of the solution.

[0040] Example 1

[0041] Alkaline etching additives consist of the following raw materials:

[0042] Nucleation agent 3, the nucleation agent is dodecylbenzyldimethylammonium chloride;

[0043] 1% of a nap conditioner, wherein the nap conditioner is sodium gluconate;

[0044] 0.1% defoamer, wherein the defoamer is Dow Corning silicone defoamer 3168;

[0045] pH adjuster 0.5%, wherein the pH adjuster is trisodium phosphate;

[0046] 5% toughening agent;

[0047] Deionized water balance;

[0048] The toughening agent comprises ethylene glycol, polyethylene glycol and calcium propionate, and the toughening agent comprises the following raw materials in parts by weight: 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol and 0.8 parts calcium propionate.

[0049] The preparation method of alkaline etching additives includes the following steps:

[0050] Step 1: Dissolve sodium gluconate and pH adjuster in water according to the specified ratio to form a liquid.

[0051] Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Use a stainless steel stirrer to stir at a speed of 400 rad / min. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃, and the time to 45 minutes to obtain the toughening agent.

[0052] Step 3: At a speed of 30 r / min, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent and defoamer 3168 to the above liquid in sequence according to the proportion. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

[0053] Example 2

[0054] Alkaline etching additives consist of the following raw materials:

[0055] Nucleation agent 3, the nucleation agent is dodecylbenzyldimethylammonium chloride;

[0056] 1% of a nap conditioner, wherein the nap conditioner is EDTA;

[0057] 0.1% defoamer, wherein the defoamer is Dow Corning silicone defoamer 3168;

[0058] pH adjuster 0.5%, wherein the pH adjuster is trisodium phosphate;

[0059] 5% toughening agent;

[0060] Deionized water balance;

[0061] The toughening agent comprises ethylene glycol, polyethylene glycol and calcium propionate, and the toughening agent comprises the following raw materials in parts by weight: 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol and 0.8 parts calcium propionate.

[0062] The preparation method of alkaline etching additives includes the following steps:

[0063] Step 1: Add EDTA and pH adjuster to water according to the specified ratio and stir to dissolve them into a liquid.

[0064] Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Use a stainless steel stirrer to stir at a speed of 400 rad / min. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃, and the time to 45 minutes to obtain the toughening agent.

[0065] Step 3: At a speed of 30 r / min, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent and defoamer 3168 to the above liquid in sequence according to the proportion. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

[0066] Example 3

[0067] Alkaline etching additives consist of the following raw materials:

[0068] Nucleation agent 3, the nucleation agent is dodecylbenzyldimethylammonium chloride;

[0069] 1% of a nap conditioner, wherein the nap conditioner is sodium tripolyphosphate;

[0070] 0.1% defoamer, wherein the defoamer is Dow Corning silicone defoamer 3168;

[0071] pH adjuster 0.5%, wherein the pH adjuster is trisodium phosphate;

[0072] 5% toughening agent;

[0073] Deionized water balance;

[0074] The toughening agent comprises ethylene glycol, polyethylene glycol and calcium propionate, and the toughening agent comprises the following raw materials in parts by weight: 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol and 0.8 parts calcium propionate.

[0075] The preparation method of alkaline etching additives includes the following steps:

[0076] Step 1: Add sodium tripolyphosphate and pH adjuster to water according to the specified ratio and stir to dissolve them into a liquid.

[0077] Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Use a stainless steel stirrer to stir at a speed of 400 rad / min. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃, and the time to 45 minutes to obtain the toughening agent.

[0078] Step 3: At a speed of 40 rpm, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent, and defoamer 3168 to the above liquid in the specified proportions. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

[0079] Example 4

[0080] Alkaline etching additives consist of the following raw materials:

[0081] Nucleation agent 3, the nucleation agent is dodecylbenzyldimethylammonium chloride;

[0082] 1% of a nap conditioner, wherein the nap conditioner is sodium citrate;

[0083] 0.1% defoamer, wherein the defoamer is Dow Corning silicone defoamer 3168;

[0084] pH adjuster 0.5%, wherein the pH adjuster is trisodium phosphate;

[0085] 6% toughening agent;

[0086] Deionized water balance;

[0087] The toughening agent comprises ethylene glycol, polyethylene glycol and calcium propionate, and the toughening agent comprises the following raw materials in parts by weight: 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol and 0.8 parts calcium propionate.

[0088] The preparation method of alkaline etching additives includes the following steps:

[0089] Step 1: Dissolve sodium citrate and pH adjuster in water according to the specified ratio.

[0090] Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Use a stainless steel stirrer to stir at a speed of 400 rad / min. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃, and the time to 45 minutes to obtain the toughening agent.

[0091] Step 3: At a speed of 40 r / min, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent and defoamer 3168 to the above liquid in sequence according to the proportion. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

[0092] Example 5

[0093] The only difference between this embodiment and Example 4 is that the only difference between this embodiment and Comparative Example 1 is that the suede conditioner is sodium gluconate with a content of 2%.

[0094] Example 6

[0095] The only difference between this embodiment and Embodiment 5 is that the suede conditioner is EDTA.

[0096] Example 7

[0097] The only difference between this embodiment and Embodiment 6 is that the suede conditioner is sodium tripolyphosphate and the toughening agent content is 7%.

[0098] Example 8

[0099] The only difference between this embodiment and Embodiment 7 is that the suede conditioner is sodium citrate.

[0100] Example 9

[0101] The only difference between this embodiment and Embodiment 8 is that the suede conditioner is 1% EDTA and 1% sodium gluconate.

[0102] Example 10

[0103] The only difference between this embodiment and Embodiment 9 is that the suede conditioner is 1% sodium tripolyphosphate and 1% sodium gluconate, and the toughening agent accounts for 8%.

[0104] Example 11

[0105] The only difference between this embodiment and Embodiment 10 is that the suede conditioner is 1% sodium citrate and 1% sodium gluconate.

[0106] Comparative Example 1

[0107] Alkaline etching additives consist of the following raw materials:

[0108] CMC 3%

[0109] Polyvinylpyrrolidone 0.1%

[0110] 2% trisodium phosphate

[0111] 1% sodium gluconate

[0112] Sodium dodecyl sulfate 0.01%

[0113] Deionized water balance

[0114] Comparative Example 2

[0115] Alkaline etching additives consist of the following raw materials:

[0116] 5% polyethylene glycol

[0117] Sodium acetate 0.3%

[0118] 2% trisodium phosphate

[0119] 1% sodium gluconate

[0120] Sodium dodecyl sulfate 0.01%

[0121] Deionized water balance

[0122] Table 1. Preparation of Additives: Prepare the corresponding additive solutions (%) according to the proportions in the table below.

[0123]

[0124] Table 2. Raw material ratios (%) for Comparative Examples 1-2

[0125]

[0126] ② Pre-cleaning treatment: Mix sodium hydroxide, hydrogen peroxide, and deionized water in a mass ratio of 0.2:2:100 until homogeneous, then pour the mixture into a pre-cleaning tank. Raise the temperature of the solution in the tank to 60℃, then place the prepared silicon wafers into the pre-cleaning tank. The pre-cleaning time is 2 minutes. After pre-cleaning, remove the silicon wafers, rinse them with deionized water, and dry them.

[0127] ③ Etching: Add an appropriate amount of deionized water to the etching tank. Pour the prepared texturing additive solution into the tank at a ratio of 0.5% and raise the temperature to maintain the temperature of the additive solution at 80℃. Then, add 45% sodium hydroxide solution at a ratio of 3%. After mixing evenly, raise the temperature to 85℃, and then place the pre-cleaned silicon wafer into the tank. The etching time is 8 minutes. After completion, remove the silicon wafer, rinse it with deionized water, and dry it. Observe the textured surface appearance using a scanning electron microscope. Measure the width and height of the pyramid using an Olympus 3D microscope. Measure the reflectivity using a reflectometer and observe the surface for cracks. The specific test results are as follows:

[0128] Table 3. Detection results of Examples 1-11 and Comparative Examples 1-2

[0129]

[0130] As can be seen from the table above, Examples 1-11 exhibit superior performance in terms of appearance, and their reflectivity is also lower than that of Comparative Examples 1-2. Furthermore, with the addition of the specially formulated toughening agent of this invention, the silicon wafer surface maintains good toughness despite increased roughness, preventing crack formation and ensuring the performance of the solar cell.

[0131] The key point and protection of this invention lies in using dodecylbenzyldimethylammonium chloride as the nucleation agent, utilizing its super adsorption capacity to effectively adsorb onto the silicon wafer surface and inhibit OH groups. - The reaction with the silicon wafer forms textured dots, which eventually become the apex of the textured pyramid as the reaction proceeds. The adsorption etching principle of this invention is the most fundamental difference between it and other texturing additives.

[0132] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. An alkaline etching additive for texturing the surface of monocrystalline silicon solar cells, characterized in that, It consists of the following raw materials: Nucleation agent 3-5%, 1-2% of nap conditioner Defoamer 0.1-0.3%, pH adjuster 0.5-2%, Toughening agent 5-8%, Deionized water balance; The toughening agent includes ethylene glycol, polyethylene glycol, and calcium propionate; The toughening agent comprises the following raw materials in parts by weight: 1.2 parts ethylene glycol, 0.9 parts polyethylene glycol, and 0.8 parts calcium propionate; The nucleation agent is dodecylbenzyldimethylammonium chloride; The suede conditioner is any one of sodium gluconate, EDTA, sodium citrate, and sodium tripolyphosphate; The defoamer is Dow Corning silicone defoamer 3168; The pH adjuster is trisodium phosphate.

2. The alkaline etching additive for surface texturing of monocrystalline silicon solar cells according to claim 1, characterized in that, The toughening agent is prepared by the following method: Ethylene glycol and calcium propionate were added to a constant-temperature, sealed ultrasonic reactor and stirred for 30 minutes. Then, polyethylene glycol was added, the ultrasonic reactor was sealed, and the temperature was set to 80°C for 45 minutes to obtain a toughening agent.

3. The alkaline etching additive for surface texturing of monocrystalline silicon solar cells according to claim 1, characterized in that, The preparation method of the alkaline etching additive includes the following steps: Step 1: Dissolve sodium gluconate and pH adjuster in water according to the specified ratio to form a liquid. Step 2: Add ethylene glycol and calcium propionate to a constant temperature sealed ultrasonic reactor and stir for 30 minutes. Then add polyethylene glycol, seal the ultrasonic reactor, set the temperature to 80℃ and the time to 45 minutes to obtain the toughening agent. Step 3: At a speed of 30-40 r / min, slowly add dodecyl benzyl dimethyl ammonium chloride, toughening agent and defoamer 3168 to the above liquid in sequence according to the proportion. After the addition is complete, continue stirring for 30 minutes to obtain the finished product.

4. The alkaline etching additive for surface texturing of monocrystalline silicon solar cells according to claim 3, characterized in that, In step one, a stainless steel mixer is used for stirring at a speed of 400 rad / min.

5. The alkaline etching additive for surface texturing of monocrystalline silicon solar cells according to claim 1, characterized in that, Including raw material composition: nucleation agent 3%, 1% flocking conditioner Defoamer 0.1%, pH adjuster 2%, 5% toughening agent Deionized water balance; The toughening agent includes ethylene glycol, polyethylene glycol, and calcium propionate.

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