Silicon wafer cleaning agent and application thereof
By using silicon wafer cleaning agents containing components such as surfactant, chelating agent, etc., the problems of large consumption and pollution risks of silicon wafer cleaning in the prior art are solved, and efficient cleaning and high-quality velvet making are achieved.
Patent Information
- Application Number
- CN202411477252.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-02-07
AI Technical Summary
The existing silicon wafer cleaning methods consume huge amounts, high alkali and hydrogen peroxide use, and there is a risk of secondary pollution, making it difficult to effectively improve the cleaning efficiency.
Using a silicon wafer cleaning agent including surfactant, chelating agent, sodium phosphate, wetting agent and penetrant, the alkali and peroxide are reduced by a chelating agent in combination of polyaspartic acid, vinyl polymer and phosphine compound. The amount of hydrogen used and improve the cleaning effect.
The use of alkali and hydrogen peroxide is significantly reduced, about 60% and 50% respectively, which improves the cleanliness of the silicon wafer surface and ensures the suede quality and electrical performance after velvet making.
Smart Images
Figure CN119391491A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of solar cells, and in particular relates to a silicon wafer cleaning agent and application thereof. Background Art
[0002] As the reserves of traditional fossil energy decrease, it is imperative to promote the use of green energy. The power generation of photovoltaic solar cells has increased year by year, and crystalline silicon solar cells have made an indispensable contribution. At present, the main task of developing silicon solar cells is to reduce costs and increase efficiency. In the manufacturing process of silicon solar cells, cleaning and texturing are particularly critical. Contamination on the surface of silicon wafers can directly affect the yield and power generation efficiency of the cells. In the production process of silicon wafers, adhesives and auxiliary agents will remain in the process of sticking and fixing. Diamond wire cutting of silicon square rods will produce a damaged layer at the cutting point, and metal particle impurities will be attached. Dust in the air or pollutants such as operator fingerprints will also be absorbed during transportation. These contaminants need to be removed before texturing.
[0003] The cleaning method currently used in industry is a cleaning solution composed of a mixture of alkaline solution, hydrogen peroxide solution and deionized water. This method can effectively remove most of the contamination on the surface of silicon wafers and remove the cutting damage layer, but this method consumes a huge amount of reagents, and the cleaning temperature and time are relatively long, and there is also the risk of secondary contamination.
[0004] Therefore, developing a cleaning agent that improves cleaning efficiency while reducing the amount of alkali and hydrogen peroxide is particularly important for silicon wafer cleaning and texturing processes. Summary of the invention
[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a silicon wafer cleaning agent and application thereof.
[0006] To achieve the above object, the technical solution adopted by the present invention is:
[0007] A silicon wafer cleaning agent comprises the following raw materials in percentage by weight: 0.1-0.5% of a surfactant, 0.2-0.6% of a chelating agent, 0.1-0.6% of sodium phosphate, 0.5-2% of a wetting agent, 0.1-0.5% of a penetrant, and the balance of deionized water;
[0008] The chelating agents include polyaspartic acid, vinyl polymers and phosphine compounds.
[0009] Compared with single polyaspartic acid, vinyl polymer or phosphine compound, the chelating agent of the present invention which combines polyaspartic acid, vinyl polymer and phosphine compound can further reduce the usage of alkali and hydrogen peroxide, and can improve the cleaning effect of silicon wafer before texturing. In addition, the quality of the texturing surface after cleaning is significantly improved.
[0010] As a preferred embodiment of the present invention, the mass ratio of the polyaspartic acid, the vinyl polymer and the phosphine compound is 1:(0.6-0.8):(0.4-0.6).
[0011] The mass ratio of polyaspartic acid, vinyl polymer and phosphine compound is 1:(0.6-0.8):(0.4-0.6), which can significantly reduce the usage of alkali and hydrogen peroxide, and significantly improve the texturing effect and increase the uniformity of the velvet surface. If the usage of the three is not within the above-mentioned limited range, the texturing effect will be significantly reduced and the uniformity of the velvet surface will be reduced.
[0012] As a preferred embodiment of the present invention, the vinyl polymer is at least one of polyacrylic acid, hydrolyzed polymaleic anhydride, and acrylic acid-ethyl acrylate-itaconic acid copolymer.
[0013] More preferably, the vinyl polymer is polyacrylic acid, which can reduce the usage of alkali and hydrogen peroxide to the greatest extent in the silicon wafer cleaning agent system of the present invention and has the best texturing effect.
[0014] As a preferred embodiment of the present invention, the phosphine compound is at least one of aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, and phosphonobutanetricarboxylic acid.
[0015] As a preferred embodiment of the present invention, the surfactant is at least one of cetearyl alcohol polyoxyethylene ether-10, sorbitan fatty acid esters, polyoxyethylene sorbitan esters, coconut fatty acid diethylamide, coconut acid diethanolamide, sodium lauryl sulfate, dodecyl dimethyl amine oxide and sodium dodecylbenzene sulfonate.
[0016] As a preferred embodiment of the present invention, the wetting agent is polyoxyethylene fatty alcohol ether or polyoxyethylene polyoxypropylene block copolymer.
[0017] The present invention studies the importance of wetting agents in silicon wafer cleaning agents and finds that if the wetting agent is missing, the effect of the mixed cleaning solution obtained by evenly mixing the silicon wafer cleaning agent, alkaline solution, hydrogen peroxide and deionized water on the cleaning of solar cell silicon wafers before texturing is reduced, and the effect of the prepared texturing surface is reduced, but the effect on the amount of alkaline solution and hydrogen peroxide used is not obvious.
[0018] As a preferred embodiment of the present invention, the penetrant is isomeric alcohol ether phosphate or isooctyl alcohol polyoxyethylene ether phosphate.
[0019] The present invention also claims to protect the use of the silicon wafer cleaning agent in cleaning solar cell silicon wafers before texturing, including uniformly mixing the silicon wafer cleaning agent, alkaline solution, hydrogen peroxide and deionized water to obtain a mixed cleaning solution, and then immersing the silicon wafer in the mixed cleaning solution for ultrasonic cleaning.
[0020] As a preferred embodiment of the present invention, the volume ratio of the silicon wafer cleaning agent: alkaline solution: hydrogen peroxide: deionized water is (3-4):1:(2-3):(300-600); the alkaline solution is a sodium hydroxide or potassium hydroxide solution, the alkaline solution is a sodium hydroxide or potassium hydroxide solution with a mass concentration of 25-30%, and the mass concentration of the hydrogen peroxide is 30%.
[0021] As a preferred embodiment of the present invention, the temperature of ultrasonic cleaning is 80° C. and the time is 240 s.
[0022] The present invention also claims to protect the use of the silicon wafer cleaning agent in the texturing of solar cell silicon wafers, including the following steps: completely immersing the silicon wafer cleaned with a mixed cleaning solution consisting of the silicon wafer cleaning agent, alkaline solution, hydrogen peroxide and deionized water in an etching solution for etching, the etching temperature is 40°C, the time is 8 minutes, and after the etching is completed, cleaning and drying; the etching solution is composed of copper nitrate with a concentration of 0.06M, hydrofluoric acid with a concentration of 2M, hydrogen peroxide with a concentration of 1.5M, tetrabutylammonium bromide with a concentration of 10μM, sodium dodecyl sulfate with a concentration of 20μM and the remainder water.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the silicon wafer cleaning agent of the present invention can effectively reduce the amount of alkali and hydrogen peroxide consumed in silicon wafer cleaning, with alkali consumption reduced by about 60% and hydrogen peroxide consumption reduced by about 50%. The silicon wafer cleaning agent of the present invention is used to clean the silicon wafer before texturing, and no impurities such as particles and other organic matter remain on the surface of the cleaned silicon wafer, and the residual rate of metal ions is low, which will not affect the electrical properties and texture quality of the silicon wafer. The velvet surface formed after texturing is more uniform and dense, and the velvet surface quality is better. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 1 and 2 are SEM images of the silicon wafers after cleaning in Example 1 and Comparative Example 1, (a) is the SEM image of the silicon wafer after cleaning in Comparative Example 1, and (b) is the SEM image of the silicon wafer after cleaning in Example 1.
[0025] Figure 2 1 and 2 are SEM images of the silicon wafers after cleaning in Comparative Example 1, Comparative Example 2 and Example 2, (a) is the SEM image of the silicon wafer after cleaning in Comparative Example 1, (b) is the SEM image of the silicon wafer after cleaning in Comparative Example 2, and (c) is the SEM image of the silicon wafer after cleaning in Example 2.
[0026] Figure 3 It is the consumption of alkali and hydrogen peroxide consumed in the cleaning process of Example 1 and Comparative Examples 1-2.
[0027] Figure 4These are SEM images of the silicon wafer surface after texturing of Example 1, Comparative Example 1 and Comparative Example 2, (a) is the SEM image of Comparative Example 1 after inverted pyramid texturing, (b) is the SEM image of Comparative Example 2 after inverted pyramid texturing, and (c) is the SEM image of Example 1 after inverted pyramid texturing.
[0028] Figure 5 This is a graph of the light reflectivity of silicon wafers after texturing in Example 1, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION
[0029] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.
[0030] Example 1
[0031] The silicon wafer cleaning agent is used in the cleaning before and during the texturing of solar cell silicon wafers, specifically including:
[0032] Step 1: Prepare silicon wafer cleaning agent: according to the mass percentage, add 0.3% sodium dodecyl sulfate, 0.4% chelating agent (prepared by polyaspartic acid, polyacrylic acid, phosphonic acid butane tricarboxylic acid in a mass ratio of 1:0.8:0.5), 0.5% sodium phosphate, 1% polyoxyethylene fatty alcohol ether, and 0.4% isomeric alcohol ether phosphate to the remaining deionized water, mix well to obtain the silicon wafer cleaning agent.
[0033] Step 2: Prepare a mixed cleaning solution: prepare silicon wafer cleaning agent: alkaline solution: hydrogen peroxide: deionized water in a volume ratio of 4:1:3:300, wherein the alkaline solution is a sodium hydroxide solution with a mass concentration of 30%, and the mass concentration of hydrogen peroxide is 30%.
[0034] Step 3: Cleaning the silicon wafer: completely immerse the raw silicon wafer cut from the silicon square rod in the mixed cleaning solution, perform constant temperature ultrasonic cleaning at 80°C for 240s, rinse with deionized water, and blow dry with nitrogen to obtain the cleaned silicon wafer.
[0035] Step 4: Texturing: Use copper-assisted chemical etching to prepare an inverted pyramid texture structure on the cleaned silicon wafer. The etching solution consists of 0.06M copper nitrate, 2M hydrofluoric acid, 1.5M hydrogen peroxide, 10μM tetrabutylammonium bromide and 20μM sodium dodecyl sulfate. The silicon wafer is completely immersed in the etching solution, the reaction temperature is set to 40°C, the reaction time is 8min, and after the reaction is completed, it is cleaned and blown dry.
[0036] Example 2
[0037] The silicon wafer cleaning agent is used in the cleaning before and during the texturing of solar cell silicon wafers, specifically including:
[0038] Step 1: Prepare a silicon wafer cleaning agent: according to the mass percentage, add 0.5% of coconut fatty acid diethylamide, 0.6% of a chelating agent (prepared with polyaspartic acid, hydrolyzed polymaleic anhydride, and hydroxyethylidene diphosphonic acid in a mass ratio of 1:0.6:0.4), 0.1% of sodium phosphate, 0.5% of a polyoxyethylene polyoxypropylene block copolymer, and 0.1% of isooctyl alcohol polyoxyethylene ether phosphate (AEP) to the remaining amount of deionized water, and mix well to obtain a silicon wafer cleaning agent.
[0039] Step 2: Prepare a mixed cleaning solution: prepare silicon wafer cleaning agent: alkaline solution: hydrogen peroxide: deionized water in a volume ratio of 3:1:2:400, wherein the alkaline solution is a sodium hydroxide solution with a mass concentration of 25%, and the mass concentration of hydrogen peroxide is 30%.
[0040] Step 3: Cleaning the silicon wafer: completely immerse the raw silicon wafer cut from the silicon square rod in the mixed cleaning solution, perform constant temperature ultrasonic cleaning at 80°C for 240s, rinse with deionized water, and blow dry with nitrogen to obtain the cleaned silicon wafer.
[0041] Step 4: Texturing: Use copper-assisted chemical etching to prepare an inverted pyramid texture structure on the cleaned silicon wafer. The etching solution consists of 0.06M copper nitrate, 2M hydrofluoric acid, 1.5M hydrogen peroxide, 10μM tetrabutylammonium bromide and 20μM sodium dodecyl sulfate. The silicon wafer is completely immersed in the etching solution, the reaction temperature is set to 40°C, the reaction time is 8min, and after the reaction is completed, it is cleaned and blown dry.
[0042] Example 3
[0043] The silicon wafer cleaning agent is used in the cleaning before and during the texturing of solar cell silicon wafers, specifically including:
[0044] Step 1: prepare silicon wafer cleaning agent: according to the mass percentage, add 0.1% of dehydrated sorbitan fatty acid ester, 0.2% of chelating agent (prepared by polyaspartic acid, acrylic acid-ethyl acrylate-itaconic acid copolymer, aminotrimethylene phosphonic acid in a mass ratio of 1:0.7:0.5), 0.6% of sodium phosphate, 2% of polyoxyethylene fatty alcohol ether, and 0.5% of isomeric alcohol ether phosphate to the remaining deionized water, mix well to obtain the silicon wafer cleaning agent.
[0045] Step 2: Prepare a mixed cleaning solution: prepare silicon wafer cleaning agent: alkaline solution: hydrogen peroxide: deionized water in a volume ratio of 3:1:2:600, wherein the alkaline solution is a sodium hydroxide solution with a mass concentration of 30%, and the mass concentration of hydrogen peroxide is 30%.
[0046] Step 3: Cleaning the silicon wafer: completely immerse the raw silicon wafer cut from the silicon square rod in the mixed cleaning solution, perform constant temperature ultrasonic cleaning at 80°C for 240s, rinse with deionized water, and blow dry with nitrogen to obtain the cleaned silicon wafer.
[0047] Step 4: Texturing: Use copper-assisted chemical etching to prepare an inverted pyramid texture structure on the cleaned silicon wafer. The etching solution consists of 0.06M copper nitrate, 2M hydrofluoric acid, 1.5M hydrogen peroxide, 10μM tetrabutylammonium bromide and 20μM sodium dodecyl sulfate. The silicon wafer is completely immersed in the etching solution, the reaction temperature is set to 40℃, the reaction time is 8min, and after the reaction is completed, it is cleaned and blown dry.
[0048] Comparative Example 1
[0049] The traditional cleaning agent is used in the cleaning before and during the texturing of solar cell silicon wafers, including:
[0050] Step 1: Prepare cleaning solution: prepare alkaline solution: hydrogen peroxide: deionized water in a volume ratio of 5:12:600, wherein the alkaline solution is a sodium hydroxide solution with a mass concentration of 30%, and the mass concentration of hydrogen peroxide is 30%.
[0051] Step 2: Cleaning the silicon wafer: completely immerse the raw silicon wafer cut from the silicon square rod in the cleaning solution, perform constant temperature ultrasonic cleaning at 80°C for 240s, rinse with deionized water, and blow dry with nitrogen to obtain the cleaned silicon wafer.
[0052] Step 3: Texturing: Use copper-assisted chemical etching to prepare an inverted pyramid texture structure on the cleaned silicon wafer. The etching solution consists of 0.06M copper nitrate, 2M hydrofluoric acid, 1.5M hydrogen peroxide, 10μM tetrabutylammonium bromide and 20μM sodium dodecyl sulfate. The silicon wafer is completely immersed in the etching solution, the reaction temperature is set to 40°C, the reaction time is 8min, and after the reaction is completed, it is cleaned and blown dry.
[0053] Comparative Example 2
[0054] The only difference between the use of the silicon wafer cleaning agent in the cleaning before and during texturing of solar cell silicon wafers in this comparative example and Example 1 is that the chelating agent is polyaspartic acid.
[0055] Comparative Example 3
[0056] The only difference between the use of the silicon wafer cleaning agent in the cleaning before and during texturing of solar cell silicon wafers in this comparative example and Example 1 is that the chelating agent is phosphonobutanetricarboxylic acid.
[0057] Comparative Example 4
[0058] The only difference between the use of the silicon wafer cleaning agent in the cleaning before and during texturing of solar cell silicon wafers in this comparative example and Example 1 is that the chelating agent is polyacrylic acid.
[0059] Comparative Example 5
[0060] The only difference between the use of the silicon wafer cleaning agent in the cleaning before and during texturing of solar cell silicon wafers described in this comparative example and Example 1 is that the chelating agent is prepared from polyaspartic acid and phosphonic acid butane tricarboxylic acid in a mass ratio of 1:0.5.
[0061] Comparative Example 6
[0062] The only difference between the use of the silicon wafer cleaning agent in the cleaning before and during texturing of solar cell silicon wafers described in this comparative example and Example 1 is that the chelating agent is prepared from polyaspartic acid and polyacrylic acid in a mass ratio of 1:0.8.
[0063] Effect example
[0064] 1. Observe the cleaning effect of the silicon wafer surface after cleaning by SEM.
[0065] according to Figure 1 It can be seen that compared with Comparative Example 1, the silicon wafer cleaned with the mixed cleaning solution prepared in Example 1 has substantially no contamination residue, and line marks and pits are significantly reduced, and the cleaning effect is better.
[0066] according to Figure 2 It can be seen that compared with Comparative Example 1, the silicon wafer cleaned with the mixed cleaning solution prepared in Comparative Example 2 has almost no contamination residue, but serious line marks and pits. After cleaning in Example 2, the line marks and pits are basically removed, and the cleaning effect is the best.
[0067] The cleaning effect of Example 3 is similar to that of Examples 1 and 2.
[0068] The cleaning effects of Comparative Examples 3-6 are similar to those of Comparative Example 2, with only slight differences.
[0069] 2. Explore the consumption of sodium hydroxide and hydrogen peroxide used in cleaning silicon wafers by the silicon wafer cleaning agents described in Examples 1-3 and Comparative Examples 1-6, as shown in Tables 1 and Figure 2 shown.
[0070] Prepare silicon wafer samples of the same type and degree of contamination to ensure consistency of the experiment. During the cleaning process of the silicon wafer, collect the cleaning solution after use. Dilute the cleaning solution appropriately to ensure the appropriate concentration during titration. Add an appropriate amount of cleaning solution to a beaker, add a few drops of indicator, and slowly add the standard acid solution with a burette, stirring while adding, until the indicator changes color (the color change marks the completion of the reaction).
[0071] Record the volume (V) of the standard acid solution used. Calculate the consumed sodium hydroxide (NaOH) and hydrogen peroxide (H 2 O 2 ) amount. Calculate the amount of NaOH and H based on the titrated volume and concentration 2 O 2 consumption.
[0072] Table 1
[0073] Sodium hydroxide consumption (ml) Hydrogen peroxide consumption (ml) Example 1 0.67 2.51 Example 2 0.71 2.74 Example 3 0.63 2.70 Comparative Example 1 1.65 4.83 Comparative Example 2 1.04 3.43 Comparative Example 3 0.96 3.20 Comparative Example 4 1.00 3.65 Comparative Example 5 0.86 3.11 Comparative Example 6 0.79 3.27
[0074] According to Table 1, compared with Comparative Examples 1-6, the silicon wafer cleaning agent prepared in Examples 1-3 can significantly reduce the consumption of sodium hydroxide and hydrogen peroxide, indicating that the synergistic effect of polyaspartic acid, vinyl polymer and phosphine compounds can reduce the consumption of alkali and hydrogen peroxide.
[0075] 3. Explore the texturing effect of cleaning silicon wafers with the silicon wafer cleaning agents described in Examples 1-3 and Comparative Examples 1-6.
[0076] The present invention illustrates the texturing effect by SEM and light reflectivity. Figure 5 And as shown in Table 2.
[0077] Table 2
[0078]
[0079]
[0080] according to Figure 4 It can be seen that the depth of the inverted pyramid morphology after the silicon wafer in Comparative Example 1, which was not cleaned with the silicon wafer cleaning agent described in the present invention, was uneven, and the size gradient was quite different. In Comparative Example 2, only polyaspartic acid was used as a chelating agent, and the depth of the inverted pyramid was relatively consistent but the size distribution was uneven. In Example 1, the inverted pyramid after the silicon wafer cleaned with the silicon wafer cleaning agent described in the present invention was dense and uniform, which effectively improved the quality of the velvet surface.
[0081] According to Table 2, the texturing effect of cleaning silicon wafers with the silicon wafer cleaning agents described in Examples 1-3 is better than that of Comparative Examples 1-6.
[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.
Claims
1. A silicon wafer cleaning agent, characterized in that: The method comprises the following raw materials in percentage by weight: 0.1-0.5% of a surfactant, 0.2-0.6% of a chelating agent, 0.1-0.6% of sodium phosphate, 0.5-2% of a wetting agent, 0.1-0.5% of a penetrant and the balance of deionized water; The chelating agents include polyaspartic acid, vinyl polymers and phosphine compounds.
2. The silicon wafer cleaning agent according to claim 1, characterized in that: The mass ratio of the polyaspartic acid, the vinyl polymer and the phosphine compound is 1:(0.6-0.8):(0.4-0.6).
3. The silicon wafer cleaning agent according to claim 1, characterized in that: The vinyl polymer is at least one of polyacrylic acid, hydrolyzed polymaleic anhydride, and acrylic acid-ethyl acrylate-itaconic acid copolymer.
4. The silicon wafer cleaning agent according to claim 1, characterized in that: The phosphine compound is at least one of aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, and phosphonobutanetricarboxylic acid.
5. The silicon wafer cleaning agent according to claim 1, characterized in that: The surfactant is at least one of cetearyl alcohol polyoxyethylene ether-10, sorbitan fatty acid ester, polyoxyethylene sorbitan ester, coconut fatty acid diethylamide, coconut acid diethanolamide, sodium lauryl sulfate, dodecyl dimethyl amine oxide and sodium dodecylbenzene sulfonate.
6. The silicon wafer cleaning agent according to claim 1, characterized in that: The wetting agent is polyoxyethylene fatty alcohol ether or polyoxyethylene polyoxypropylene block copolymer.
7. The silicon wafer cleaning agent according to claim 1, characterized in that: The penetrant is isomeric alcohol ether phosphate or isooctyl alcohol polyoxyethylene ether phosphate.
8. Application of a silicon wafer cleaning agent in cleaning solar cell silicon wafers before texturing, characterized in that: The method comprises uniformly mixing the silicon wafer cleaning agent according to any one of claims 1 to 7, an alkaline solution, hydrogen peroxide and deionized water to obtain a mixed cleaning solution, and then immersing the silicon wafer in the mixed cleaning solution for ultrasonic cleaning.
9. The use of the silicon wafer cleaning agent as claimed in claim 8 in cleaning solar cell silicon wafers before texturing, characterized in that: The volume ratio of the silicon wafer cleaning agent: alkaline solution: hydrogen peroxide: deionized water is (3-4):1:(2-3):(300-600); the alkaline solution is a sodium hydroxide or potassium hydroxide solution with a mass concentration of 25-30%, and the mass concentration of the hydrogen peroxide is 30%; the temperature of ultrasonic cleaning is 80°C and the time is 240s.
10. Application of a silicon wafer cleaning agent in texturing of solar cell silicon wafers, characterized in that: include: Completely immerse the silicon wafer cleaned with the mixed cleaning solution consisting of the silicon wafer cleaning agent according to any one of claims 1 to 7, an alkaline solution, hydrogen peroxide and deionized water in an etching solution for etching, and clean and dry the silicon wafer after the etching is completed; The etching solution consists of 0.06M copper nitrate, 2M hydrofluoric acid, 1.5M hydrogen peroxide, 10μM tetrabutylammonium bromide, 20μM sodium dodecyl sulfate and the balance water.