Preparation method of photovoltaic crystalline silicon polishing agent

Abstract

The invention discloses a preparation method of a photovoltaic crystalline silicon polishing agent, which comprises the following steps: step 1, adding a surfactant into an organic solvent for fully dissolving to prepare a mixed solution for later use; and step 2, adding basic alkali liquor and deionized water into the mixed solution in the step 1, and uniformly stirring until all components in the solution are uniform. The photovoltaic crystalline silicon polishing agent has the beneficial effects that the brightening agent and the additive with a protective effect are fully fused into the basic alkali liquor, so that the polishing efficiency of the photovoltaic crystalline silicon polishing agent on the photovoltaic crystalline silicon is improved when the photovoltaic crystalline silicon polishing agent is used, meanwhile, the smoothness of the back surface of the photovoltaic crystalline silicon is ensured, the reflection efficiency of the photovoltaic crystalline silicon on penetrating light is improved, and the service life of the photovoltaic crystalline silicon is prolonged. In addition, the photovoltaic crystalline silicon polishing agent can effectively reduce the concentration of alkali liquor in the polishing process of photovoltaic crystalline silicon, the polishing process is controllable, the problem of emission caused by organic alkali liquor can be effectively avoided, and the photovoltaic crystalline silicon polishing process is more environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic crystalline silicon polishing, and in particular to a method for preparing a photovoltaic crystalline silicon polishing agent. Background Art

[0002] Clean energy such as wind energy, hydropower, geothermal energy, solar energy, and nuclear energy are the future development direction of the energy industry. Solar energy is the main form of clean energy, the safest and most environmentally friendly of all new energy types, with a large available energy reserve and a very broad development prospect. The technical routes for the use of solar energy mainly include photovoltaic and solar thermal, among which photovoltaic solar energy has the fastest development.

[0003] The core equipment in photovoltaic solar modules is the solar panel, which is made of monocrystalline silicon and can convert light energy into electrical energy. Conventional monocrystalline silicon solar cells use chemical methods to texture the surface of the velvet to increase the surface area and reduce the reflectivity due to the need to trap light. However, the existence of the velvet also has a negative impact. The deep concave position of the velvet will have poor contact with the metal. Therefore, everyone considers polishing the back surface of the silicon wafer to make the back surface of the silicon wafer smoother or even achieve a mirror effect. After back polishing, the back of the silicon wafer is flat, which can enhance the reflection of the transmitted light and reduce the transmittance; on the other hand, it can make the aluminum paste more fully contact with the silicon wafer surface and improve the passivation effect.

[0004] At present, the following three methods are mainly used in the industrial polishing production of crystalline silicon solar cells: 1. Tetramethylammonium hydroxide polishing. The silicon wafers prepared by this method have a higher reflectivity, but the cost of the liquid and the tail liquid treatment is high, and the pollution to the environment is also serious; 2. Nitric acid and hydrofluoric acid polishing. This method has low liquid cost, poor polishing effect, and serious pollution to the environment; 3. Inorganic alkali polishing, using high concentrations of potassium hydroxide and sodium hydroxide for polishing. This method has low liquid cost, good polishing effect, and less impact on the environment, but its process is unstable and the reaction process is difficult to control. At the same time, the alkali will corrode the silicon oxide on the front of the silicon wafer, thereby destroying the front PN junction and causing battery failure. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a photovoltaic crystalline silicon polishing agent in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A method for preparing a photovoltaic crystalline silicon polishing agent comprises the following steps:

[0008] Step 1: Add the surfactant into the organic solvent and fully dissolve it to prepare a mixed solution for use;

[0009] Step 2: Add the basic alkali solution and deionized water to the mixed solution in step 1, and stir evenly until the components in the solution are uniform;

[0010] Step 3: Add the brightener and additives to the mixed solution in step 2 under stirring conditions, and disperse them for 3-5 minutes under ultrasonic action to obtain the photovoltaic crystalline silicon polishing agent.

[0011] Furthermore, the photovoltaic crystalline silicon polishing agent is composed of raw materials in the following percentages: 20-40% basic alkali solution, 3-5% additives, 0.3-0.5% brightener, 1-2% organic solvent, 0.2-1% surfactant, and the rest is deionized water.

[0012] Furthermore, the additive is prepared by mixing polyacrylamide, sodium benzoate and hydroxyethyl starch in a ratio of 1:1:1. The additive can protect the surface of silicon photovoltaic crystalline silicon during the polishing process, and plays a key role in protecting the front PN junction of the silicon wafer from being damaged. The polyacrylamide in the additive has an adsorption effect on the surface of silicon oxide, inhibits the reaction of silicon oxide with inorganic bases, and protects the silicon surface diffusion layer.

[0013] Furthermore, the brightener is a water-based silicone brightener, and the organic solvent is isopropyl alcohol. The brightener can effectively increase the brightness of the surface of the photovoltaic crystalline silicon after polishing, and improve the reflectivity of the photovoltaic crystalline silicon to the penetrating light. The organic solvent composed of isopropyl alcohol can utilize the difference in affinity of isopropyl alcohol to the silicon substrate and water to improve the difficulty of removing the polishing liquid, thereby making the polished silicon wafer easier to clean.

[0014] Furthermore, the surfactant is an amphoteric surfactant, which is composed of one or more of chloroacetic acid, betaine, methyl acrylate, and alkylaminopropionate. The surfactant can effectively increase the solubility of the brightener and organic solvent in the basic alkali solution to ensure the uniformity of the overall composition of the polishing agent.

[0015] Furthermore, the photovoltaic crystalline silicon polishing agent is composed of raw materials in the following percentages: 25-35% basic alkali solution, 3.5-4.5% additives, 0.3.5-0.45% brightener, 1.2-1.8% organic solvent, 0.4-0.8% surfactant, and the rest is deionized water.

[0016] Furthermore, the photovoltaic crystalline silicon polishing agent is preferably composed of raw materials in the following percentages: 30% basic alkali solution, 4% additives, 0.42% brightener, 1.5% organic solvent, 0.6% surfactant, and the rest is deionized water.

[0017] The beneficial effects of the present invention are:

[0018] The present invention fully integrates the brightener and the additive with protective effect into the basic alkali solution, so that the polishing efficiency of the photovoltaic crystalline silicon when the photovoltaic crystalline silicon polishing agent is used is improved, and at the same time the smoothness of the back of the photovoltaic crystalline silicon is ensured, so that the reflection efficiency of the photovoltaic crystalline silicon to the penetrating light is improved. In addition, the photovoltaic crystalline silicon polishing agent can also effectively reduce the alkali solution concentration of the photovoltaic crystalline silicon during the polishing process, and the polishing process is controllable, which can effectively avoid the emission problem caused by the organic alkali solution, making the photovoltaic crystalline silicon polishing process more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a flow chart of a method for preparing a photovoltaic crystalline silicon polishing agent. DETAILED DESCRIPTION

[0020] A method for preparing a photovoltaic crystalline silicon polishing agent comprises the following steps:

[0021] Step 1: Add the surfactant into the organic solvent and fully dissolve it to prepare a mixed solution for use;

[0022] Step 2: Add the basic alkali solution and deionized water to the mixed solution in step 1, and stir evenly until the components in the solution are uniform;

[0023] Step 3: Add the brightener and additives to the mixed solution in step 2 under stirring conditions, and disperse them for 3-5 minutes under ultrasonic action to obtain the photovoltaic crystalline silicon polishing agent.

[0024] In this embodiment, the photovoltaic crystalline silicon polishing agent is composed of raw materials with the following percentages: 20-40% basic alkali solution, 3-5% additives, 0.3-0.5% brightener, 1-2% organic solvent, 0.2-1% surfactant, and the rest is deionized water.

[0025] In this embodiment, the additive is prepared by mixing polyacrylamide, sodium benzoate, and hydroxyethyl starch in a ratio of 1:1:1. The additive can protect the surface of silicon photovoltaic crystalline silicon during the polishing process, and plays a key role in protecting the front PN junction of the silicon wafer from being damaged. The polyacrylamide in the additive has an adsorption effect on the surface of silicon oxide, inhibits the reaction of silicon oxide with inorganic bases, and protects the silicon surface diffusion layer.

[0026] In this embodiment, the brightener is a water-based silicone brightener, and the organic solvent is isopropyl alcohol. The brightener can effectively increase the brightness of the surface of photovoltaic crystalline silicon after polishing, and improve the reflectivity of photovoltaic crystalline silicon to penetrating light. The organic solvent composed of isopropyl alcohol can utilize the difference in affinity of isopropyl alcohol to the silicon substrate and water to improve the difficulty of removing the polishing liquid, thereby making the polished silicon wafer easier to clean.

[0027] In this embodiment, the surfactant is an amphoteric surfactant, which is composed of one or more of chloroacetic acid, betaine, methyl acrylate, and alkylaminopropionate. The surfactant can effectively increase the solubility of the brightener and organic solvent in the basic alkali solution to ensure the uniformity of the overall composition of the polishing agent.

[0028] In this embodiment, the photovoltaic crystalline silicon polishing agent is composed of raw materials with the following percentages: basic alkali solution 25-35%, additives 3.5-4.5%, brightener 0.3.5-0.45%, organic solvent 1.2-1.8%, surfactant 0.4-0.8%, and the rest is deionized water.

[0029] In this embodiment, the photovoltaic crystalline silicon polishing agent is preferably composed of raw materials with the following percentages: 30% basic alkali solution, 4% additives, 0.42% brightener, 1.5% organic solvent, 0.6% surfactant, and the rest is deionized water.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a photovoltaic crystalline silicon polishing agent, characterized in that: It includes the following steps: Step 1: Add the surfactant into the organic solvent and fully dissolve it to prepare a mixed solution for use; Step 2: Add the basic alkali solution and deionized water to the mixed solution in step 1, and stir evenly until the components in the solution are uniform; Step 3: Add the brightener and additives to the mixed solution in step 2 under stirring conditions, and disperse them for 3-5 minutes under ultrasonic action to obtain the photovoltaic crystalline silicon polishing agent.

2. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 1, characterized in that: The photovoltaic crystalline silicon polishing agent is composed of raw materials with the following percentage contents: 20-40% of basic alkali solution, 3-5% of additives, 0.3-0.5% of brightener, 1-2% of organic solvent, 0.2-1% of surfactant, and the rest of deionized water.

3. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 2, characterized in that: The additive is prepared by mixing polyacrylamide, sodium benzoate and hydroxyethyl starch in a ratio of 1:1:

1.

4. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 2, characterized in that: The brightener is a water-based organosilicon brightener, and the organic solvent is isopropyl alcohol.

5. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 2, characterized in that: The surfactant is an amphoteric surfactant, and the surfactant is composed of one or more of chloroacetic acid, betaine, methyl acrylate, and alkylaminopropionate.

6. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 2, characterized in that: The photovoltaic crystalline silicon polishing agent is composed of raw materials with the following percentage contents: 25-35% of basic alkali solution, 3.5-4.5% of additives, 0.3.5-0.45% of brightener, 1.2-1.8% of organic solvent, 0.4-0.8% of surfactant, and the rest of deionized water.

7. The method for preparing a photovoltaic crystalline silicon polishing agent according to claim 2, characterized in that: The photovoltaic crystalline silicon polishing agent is preferably composed of raw materials in the following percentages: 30% basic alkali solution, 4% additives, 0.42% brightener, 1.5% organic solvent, 0.6% surfactant, and the rest is deionized water.

Images