WO2021238496A1

WO2021238496A1 - Monocrystalline silicon wafer texturing additive and use thereof

Info

Publication number: WO2021238496A1
Application number: PCT/CN2021/087700
Authority: WO
Inventors: 周树伟; 张丽娟; 陈培良
Original assignee: 常州时创能源股份有限公司
Priority date: 2020-05-25
Filing date: 2021-04-16
Publication date: 2021-12-02
Also published as: CN111501105B; CN111501105A

Abstract

Disclosed is a monocrystalline silicon wafer texturing additive, the mass percentage of each component thereof being: 0.25%-5% of a hydrolyzed polyacrylonitrile ammonium salt, 0.25%-5% of a hydrolyzed polyacrylonitrile sodium salt, 0.1%-2% of S-triazine, 0.5%-5% of glycolic acid, 1%-5% of sodium lactate, 0.5%-5% of dipotassium glycyrrhizinate, and the balance of water. Adding the additive of the present invention to a texturing liquid of a monocrystalline silicon wafer can shorten a texturing time to 5 min, and greatly improve productivity, and a textured wafer with a textured face having an irregular polygonal pyramid structure and a reflectivity as low as 8% can be obtained, and same can improve the light absorption of the silicon wafer and thus improve the conversion efficiency of the silicon wafer.

Description

A monocrystalline silicon wafer texturing additive and its application

Technical field

The invention relates to the field of photovoltaics, in particular to a single crystal silicon wafer texturing additive and its application.

Background technique

In recent years, monocrystalline silicon solar cells account for an increasing proportion of crystalline silicon solar cells. Major monocrystalline silicon solar cell manufacturers are also constantly expanding. In the fierce competition, various manufacturers are committed to improving the efficiency of solar cells in order to maintain their strong competitiveness in the industry.

In the production process of monocrystalline silicon solar cells, texturing is an essential and important step. Monocrystalline silicon texturing is to texture the surface of monocrystalline silicon wafers. The most commonly used method is alkaline etching to form dense pyramid-like structures on the surface of monocrystalline silicon wafers to reduce the reflectance of the silicon wafers to light. Thereby, the absorption rate of the silicon wafer to sunlight is improved, and the photoelectric conversion efficiency is improved.

At present, the texturing reaction time of the monocrystalline silicon texturing sheet is 7 to 15 minutes, and the formed texturing structure is a relatively common pyramid structure similar to a pyramid. This structure is too regular and deflects the reflection of sunlight. Less, resulting in high reflectivity, which is basically between 11% and 12%.

Technical solutions

The purpose of the present invention is to provide a monocrystalline silicon wafer texturing additive and its application. Adding the additive of the invention to the monocrystalline silicon wafer texturing liquid can shorten the texturing time and obtain low reflectivity texturing. piece.

In order to achieve the above objective, the present invention provides a monocrystalline silicon wafer texturing additive, the mass percentage of each component is: hydrolyzed polyacrylonitrile ammonium salt 0.25%~5%, hydrolyzed polyacrylonitrile sodium salt 0.25%~ 5%, serotriazine 0.1% to 2%, glycolic acid 0.5% to 5%, sodium lactate 1% to 5%, dipotassium glycyrrhizinate 0.5% to 5%, the balance is water.

Preferably, the content of the hydrolyzed polyacrylonitrile ammonium salt is the same as the content of the hydrolyzed polyacrylonitrile sodium salt.

Preferably, the water is deionized water.

The present invention also provides a single crystal silicon wafer texturing liquid, which contains an alkali solution and the above texturing additive, the mass ratio of the texturing additive to the alkali solution is 0.2-2.5:100, and the alkali solution is an aqueous solution of inorganic alkali.

Preferably, the alkaline solution is 0.5 to 2.0 wt% sodium hydroxide or potassium hydroxide aqueous solution.

The invention also provides a single crystal silicon wafer texturing method, which uses the above-mentioned texturing liquid to perform surface texturing on the single crystal silicon wafer.

Preferably, in the above-mentioned single crystal silicon wafer texturing method, the specific steps include:

1) Preparation of texturing additives: the mass percentage of 0.25% to 5% of hydrolyzed polyacrylonitrile ammonium salt, 0.25% to 5% of hydrolyzed polyacrylonitrile sodium salt, 0.1% to 2% s-triazine, 0.5 %～5% glycolic acid, 1%～5% sodium lactate, 0.5%～5% dipotassium glycyrrhizinate are added to the balance of water, mixed evenly to form a texturing additive;

2) Prepare the texturing liquid: add the texturing additive made in step 1) to the alkali solution and mix it evenly to form a texturing liquid; the mass ratio of the texturing additive to the alkali solution is 0.2～2.5:100; the alkali solution is Aqueous solution of inorganic base;

3) Immerse the monocrystalline silicon wafer in the texturing liquid prepared in step 2) for surface texturing, the texturing temperature is 75-85°C, and the texturing time is 5-6 minutes.

Beneficial effect

The advantages and beneficial effects of the present invention are: providing a monocrystalline silicon wafer texturing additive and its application. Adding the additive of the present invention to the monocrystalline silicon wafer texturing liquid can shorten the texturing time to 5 minutes, which can greatly Increasing production capacity can also obtain a textured sheet with an irregular polygonal pyramid structure and a reflectivity as low as 8%, which can increase the light absorption of the silicon wafer, thereby increasing the conversion efficiency of the silicon wafer.

The suede structure produced by the additive of the present invention is an irregular polygonal pyramid structure (the number of side edges/sides of the polygonal pyramid is greater than 4, that is, the polygonal pyramid is at least a pentagonal pyramid), and has many light reflecting surfaces, so the reflectivity is very high. Low.

In the formulation of the texturing additive of the present invention, the hydrolyzed polyacrylonitrile ammonium salt and the hydrolyzed polyacrylonitrile sodium salt have good flocking properties and certain defoaming properties, and serve as the base flocking material; s-triazine and glycolic acid can adjust The effect of suede can be adjusted by controlling its dosage to achieve changes in suede morphology and microstructure on the pyramid, thereby achieving the effect of reducing reflectivity; sodium lactate and dipotassium glycyrrhizinate are used to supplement the suede and have perfect suede and The function of adjusting the appearance of the velvet.

Hydrolyzed polyacrylonitrile ammonium salt and hydrolyzed polyacrylonitrile sodium salt. It is an anionic polymer obtained from polyacrylonitrile waste through alkaline hydrolysis. The molecular chain contains strong polarities such as -CONH2, -COO- and -CN. The group forms a strong hydrogen bond with the Si-H bond on the surface of the silicon wafer, which can be well adsorbed on the surface of the silicon wafer, and due to the appropriate length of the molecular chain, it will not adsorb other substances due to the excessively long molecular chain. Obvious interference effect, so it has good flocking performance, combined with s-triazine and glycolic acid, which have the effect of suede adjustment, (compare Figure 1 and Figure 2 can be seen) the suede morphology of the pyramid has undergone major changes. First of all, the morphology of the spire is obviously different. Due to the entanglement and adsorption of the molecular chains of the hydrolyzed polyacrylonitrile ammonium salt and the hydrolyzed polyacrylonitrile sodium salt, the reaction products cannot be quickly removed from the surface of the silicon wafer, and form at the spire. In addition to the irregular structure, this structure increases the secondary reflection or even the third reflection process of light, which can significantly reduce the reflectivity; in addition, the formed pyramid is not a conventional quadrangular pyramid structure, but a twisted multi-pyramid structure. It is considered that the polypyramid structure is the intermediate state during the formation of the pyramid, but usually the intermediate state exists for a short time, and there will not be a large number of intermediate states before the texturing is completed. The sexual stability is very good, the time window is wide, and the presence of the suede regulator makes the intermediate state stay longer, thus forming a polypyramid shape with all the intermediate states (the number of side edges/sides of the polygonal pyramid) More than 4, that is, the polygonal pyramid is at least a pentagonal pyramid). Compared with the conventional quadrangular pyramid structure, the polygonal pyramid has more light reflectivity surfaces. No matter the light path is irradiated from any direction, more reflective surfaces will make the light have more The second reflection and third reflection process, thereby further improving the light absorption of the silicon wafer and reducing the reflectivity.

Description of the drawings

Figure 1 is a suede morphology of Example 2 of the present invention;

Figure 2 is the suede morphology of the comparative example.

Embodiments of the present invention

The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

Example 1

0.5 parts by mass of hydrolyzed polyacrylonitrile ammonium salt, 5 parts by mass of sodium salt of hydrolyzed polyacrylonitrile, 1 part by mass of serotonin, 2 parts by mass of glycolic acid, 2 parts by mass of sodium lactate, 2 parts by mass of dipotassium glycyrrhizinate, deionized water 87.5 parts by mass are mixed and stirred to form an additive solution; then the additives, sodium hydroxide and deionized water are added to the texturing tank in a mass ratio of 0.8:1:100, and the mixture is stirred to form a texturing solution; Silicon wafer texturing, texturing temperature 80℃, reaction time 6min.

Example 2

2.5 parts by mass of hydrolyzed polyacrylonitrile ammonium salt, 2.5 parts by mass of hydrolyzed polyacrylonitrile sodium salt, 1 part by mass of serotonin, 2 parts by mass of glycolic acid, 4 parts by mass of sodium lactate, 4 parts by mass of dipotassium glycyrrhizinate, deionized water 84 parts by mass are mixed and stirred to form an additive solution; then the additives, sodium hydroxide and deionized water are added to the texturing tank according to the mass ratio of 0.8:1:100, and the mixture is stirred to form a texturing solution; Silicon wafer texturing, texturing temperature 80℃, reaction time 6min.

Example 3

5 parts by mass of hydrolyzed polyacrylonitrile ammonium salt, 0.5 parts by mass of sodium salt of hydrolyzed polyacrylonitrile, 1 part by mass of s-triazine, 2 parts by mass of glycolic acid, 5 parts by mass of sodium lactate, 5 parts by mass of dipotassium glycyrrhizinate, deionized water 81.5 parts by mass are mixed and stirred to form an additive solution; then the additives, sodium hydroxide and deionized water are added to the texturing tank in a mass ratio of 0.8:1:100, and the mixture is stirred to form a texturing solution; Silicon wafer texturing, texturing temperature 80℃, reaction time 6min.

Example 4

2.5 parts by mass of hydrolyzed polyacrylonitrile ammonium salt, 2.5 parts by mass of hydrolyzed polyacrylonitrile sodium salt, 1 part by mass of serotonin, 2 parts by mass of glycolic acid, 4 parts by mass of sodium lactate, 4 parts by mass of dipotassium glycyrrhizinate, deionized water 84 parts by mass are mixed and stirred to form an additive solution; then the additives, sodium hydroxide and deionized water are added to the texturing tank according to the mass ratio of 0.8:1:100, and the mixture is stirred to form a texturing solution; Silicon wafer texturing, texturing temperature 80℃, reaction time 5min.

Example 5

2.5 parts by mass of hydrolyzed polyacrylonitrile ammonium salt, 2.5 parts by mass of sodium salt of hydrolyzed polyacrylonitrile, 1.5 parts by mass of s-triazine, 3 parts by mass of glycolic acid, 4 parts by mass of sodium lactate, 4 parts by mass of dipotassium glycyrrhizinate, deionized water 82.5 parts by mass are mixed and stirred to form an additive solution; then the additives, sodium hydroxide and deionized water are added to the texturing tank in a mass ratio of 0.8:1:100, and the mixture is stirred to form a texturing solution; Silicon wafer texturing, texturing temperature 80℃, reaction time 6min.

Comparison

Add texturing additives (produced by Changzhou Shichuang Energy Co., Ltd., product model: TS50), sodium hydroxide and deionized water according to the mass ratio of 0.8:1:100 in the texturing tank, and mix them evenly to prepare the system. Fluff liquid; then put silicon wafers into texturing, the texturing temperature is 80℃, and the reaction time is 7min.

The reflectance test of the texturing sheet obtained in the above embodiments and the comparative example is carried out. The reflectance tester adopts the NXT Helios-rc reflectance tester, and the reflectance measured on the front and back of the silicon wafer is averaged as the average reflectance. , The test results are shown in the following table:

Comparing the test results, it can be seen that the additive of the present invention has an obvious anti-reflection effect and can greatly reduce the reflectivity of the texturing sheet.

In addition, the inventors have found through research that under the condition that the content of other components of the additive remains unchanged, as the ratio of the hydrolyzed polyacrylonitrile ammonium salt and the hydrolyzed polyacrylonitrile sodium salt changes, the reflectance first decreases and then increases. When the ratio is 1:1, it reaches the lowest value, so the additive of the present invention is preferably the content of the hydrolyzed polyacrylonitrile ammonium salt and the content of the hydrolyzed polyacrylonitrile sodium salt.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims

A monocrystalline silicon wafer texturing additive, characterized in that the mass percentage of each component is: hydrolyzed polyacrylonitrile ammonium salt 0.25% to 5%, hydrolyzed polyacrylonitrile sodium salt 0.25% to 5%, both Triazine 0.1%~2%, glycolic acid 0.5%~5%, sodium lactate 1%~5%, dipotassium glycyrrhizinate 0.5%~5%, the balance is water.
The monocrystalline silicon wafer texturing additive according to claim 1, wherein the content of the hydrolyzed polyacrylonitrile ammonium salt is the same as the content of the hydrolyzed polyacrylonitrile sodium salt.
The monocrystalline silicon wafer texturing additive according to claim 1 or 2, wherein the water is deionized water.
The monocrystalline silicon wafer texturing liquid is characterized in that it contains an alkali solution and the texturing additive according to any one of claims 1 to 3, and the mass ratio of the texturing additive to the alkali solution is 0.2 to 2.5:100. The solution is an aqueous solution of an inorganic base.
The single crystal silicon wafer texturing liquid according to claim 4, wherein the alkaline solution is 0.5 to 2.0 wt% sodium hydroxide or potassium hydroxide aqueous solution.
The single crystal silicon wafer texturing method is characterized in that the surface of the single crystal silicon wafer is texturized by using the texturing liquid according to claim 4 or 5.
The method for making monocrystalline silicon wafer texturing according to claim 6, wherein the specific steps include:

1) Preparation of texturing additives: the mass percentage of 0.25% to 5% of hydrolyzed polyacrylonitrile ammonium salt, 0.25% to 5% of hydrolyzed polyacrylonitrile sodium salt, 0.1% to 2% s-triazine, 0.5 %～5% glycolic acid, 1%～5% sodium lactate, 0.5%～5% dipotassium glycyrrhizinate are added to the balance of water, mixed evenly to form a texturing additive;

2) Prepare the texturing liquid: add the texturing additive made in step 1) to the alkali solution and mix it evenly to form a texturing liquid; the mass ratio of the texturing additive to the alkali solution is 0.2～2.5:100; the alkali solution is Aqueous solution of inorganic base;

3) Immerse the monocrystalline silicon wafer in the texturing liquid prepared in step 2) for surface texturing, the texturing temperature is 75-85°C, and the texturing time is 5-6 minutes.