TWI589655B - An additive for crystalline silicon alkaline polishing liquid and use thereof - Google Patents

Description

Additive of crystalline bismuth alkaline polishing liquid and application thereof

This invention relates to additives for crystalline bismuth alkaline polishing fluids and their use.

The suede finish on the surface of the batt is critical to the solar cell, not only can significantly reduce the reflectivity of the plutonium, but also increase the absorption of light by increasing the optical path of the light in the crucible. At present, there are many methods for assisting cashmere, including various kinds of texturing additives, which can ensure that the suede rate reaches 100%, and the texturing process becomes a controllable production link. With the development of the texturing process, the uniformity of the suede is one of the methods to improve the efficiency of the battery. The better the uniformity of the suede, the higher the opening pressure of the cell, and the higher the efficiency. However, it is currently known that the uniformity of the suede after the velvet is not good, such as the size of the pyramid is not uniform, and there is also a phenomenon of regenerating a small pyramid on the pyramid tower shoulder. The ruthenium after the first polishing and the velvet process can realize a uniform pyramid structure, thereby improving the opening pressure and efficiency of the battery. Many companies use high-concentration alkali solution for polishing, and then soften in low-concentration lye, the battery efficiency has been significantly improved. However, this pretreatment often causes an appearance problem because sodium citrate is easily left on the surface during polishing in a solution of high temperature and high alkali concentration, and sodium citrate solidifies before entering the velvet tank. , severely interfere with the subsequent texturing process of the bracts, resulting in tannic acid The area covered by sodium has no pyramidal suede, and it has bright white spots on the surface of the bracts, which seriously affects the appearance and yield of the battery.

The realization of low temperature and low alkali concentration of enamel polishing while avoiding corresponding appearance problems will be an opportunity and challenge for polishing additives.

On the other hand, the current popular PERC battery (passivated emitter rear contact solar cells) process requires a relatively flat back side for alumina passivation. The optimized solution is to use an alkali solution to polish the back surface. Lower density and better passivation. However, the flatness of the back surface formed by the polishing of the alkali solution is not high, and the step surface is excessive, resulting in a decrease in the subsequent passivation effect. How to improve the alkali polishing effect to obtain satisfactory passivation results is of great significance for PERC batteries.

The object of the present invention is to provide an additive for a crystalline bismuth alkaline polishing liquid and an application thereof, which can be excellently polished by adding the additive of the present invention to an alkaline solution during polishing pretreatment before the crepe sheet is subjected to texturing. The effect is that the bract polishing can be achieved at a low alkali concentration, the uniformity of the suede surface is improved, thereby significantly improving the open circuit voltage and the battery efficiency of the battery; and the additive of the invention is also suitable for single-side polishing after the diffusion of the bracts, and can be relatively flat. The uniform back polishing surface is especially suitable for the PERC battery process, which can help improve the passivation effect of the PERC battery.

In order to achieve the above object, the present invention provides an additive for a crystalline bismuth alkaline polishing liquid, which comprises 0.5 to 2% polyethylene glycol, 0.5 to 2% alkyl glycoside, 0.5 to 2% ammonium stearate, and 1 to 3%. Ethylenediamine, 1~5% ammonium sulfate, 2~8% urea and the balance of water.

Preferably, the additive of the crystalline alkaline alkaline polishing liquid is polymerized by 1 to 1.5%. Ethylene glycol, 1~1.5% alkyl glycoside, 0.5~1% ammonium stearate, 1-2% ethylenediamine, 2~4% ammonium sulfate, 3~6% urea and the balance of water .

Preferably, the water is deionized water.

The invention also provides a crystalline bismuth alkaline polishing liquid prepared by the following steps: 1) dissolving sodium hydroxide, potassium hydroxide or tetramethylammonium hydroxide in deionized water to obtain an alkaline solution; The potassium hydroxide has a mass percentage of 1 to 5%; the tetramethylammonium hydroxide has a mass percentage of 2 to 6%; 2) the above additive is added to the alkaline solution in the above step 1) In the middle, a crystalline cerium alkaline polishing liquid is obtained; wherein the mass ratio of the additive to the alkaline solution is 1 to 6:100.

In a preferred embodiment, the sodium hydroxide and potassium hydroxide have a mass percentage of 2 to 3%; and the tetramethylammonium hydroxide has a mass percentage of 3 to 5%.

In another preferred embodiment, the sodium hydroxide and potassium hydroxide have a mass percentage of 1 to 1.5%; and the tetramethylammonium hydroxide has a mass percentage of 2 to 2.5%.

Preferably, the quality ratio of the additive to the alkaline solution is 2 to 4:100.

The invention also provides a crystallization enamel polishing method, wherein a single crystal or polycrystalline ruthenium sheet is immersed in the above polishing liquid for polishing, the temperature is controlled at 60 to 80 degrees Celsius, and the time is controlled at 0.5 to 5 minutes.

The invention has the advantages and advantageous effects of providing an additive of a crystalline bismuth alkaline polishing liquid and an application thereof, and adding the additive of the invention to an alkaline solution during surface polishing of the enamel sheet, thereby achieving an excellent polishing effect The polishing can be achieved at a low alkali concentration, and the additive of the invention can be applied to the process of first polishing and then velvet, which can improve the polishing effect of the enamel sheet, reduce the cost, shorten the reaction time, and reduce the battery. The chip fragmentation rate increases the productivity of the cell while improving the photoelectric conversion efficiency of the cell.

The ammonium stearate and ammonium sulfate in the additive can obtain a stable uniform pyramid structure under the small weight loss of the bracts; the choice of adding ethylenediamine and urea to the polishing system can make the fleece of the subsequent fleece Face size and reflectivity are controllable to meet different needs.

By using the additive of the invention, the polishing reaction speed can be accelerated, and the polishing can be achieved at a low alkali concentration, and the alkali consumption is reduced by 15-30%. The additive of the invention has wide application range, and can be applied to polishing of single crystal enamel sheet and polishing of polycrystalline enamel sheet. The additive of the invention is more suitable for the process of first polishing and then velveting. After the first polishing and the velvet process, the suede surface is relatively uniform with respect to the only suede, and the pyramid has no superimposed state, thereby improving the opening pressure and lifting. The battery efficiency is 0.2% or more, and the weight loss can be controlled at 0.5-0.7 g (156 single crystal ruthenium), which is equivalent to the conventional alkali velvet process. Of course, the additive of the present invention can also be applied to the process of first-stage velvet back polishing, and the crepe sheet can obtain a uniform flat suede after back polishing.

1 is a micrograph of a surface polishing surface of a conventional back-polished cymbal; FIG. 2 is a micrograph of the surface polished surface of the cymbal obtained in Example 1; FIG. 3 is a scanning electron micrograph of a conventional velvet surface; A scanning electron micrograph of the velvet surface obtained by polishing in Example 2 was obtained.

The specific embodiments of the present invention are further described below in conjunction with the drawings and embodiments. The following examples are only intended to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of the present invention.

The technical solution specifically implemented by the present invention is:

Example 1

First polishing and then velvet, wherein the polishing process takes the following steps: 1) preparing an additive for the crystalline bismuth alkaline polishing solution: using deionized water as a solvent, 2 g of polyethylene glycol (PEG), 2 g of alkyl glycoside (Alkyl) Polygylcosides), 2 grams of Ammonium stearate, 3 grams of ethylenediamine (Ethylenediamine), 5 grams of ammonium sulfate (Ammonium sulfate), 8 grams of urea (Urea) dissolved in deionized water to make 100 Gram additives; 2) preparation of alkaline solution: 50 grams of sodium hydroxide dissolved in deionized water to obtain 1000 grams of alkaline solution; 3) 60 grams of additive in 1000 grams of alkaline solution; 4) single crystal enamel It is immersed in a polishing solution for polishing, the temperature is controlled at 80 degrees Celsius, and the time is controlled at 5 minutes.

A micrograph of the polished surface of the back-polished bracts is shown in Fig. 1. It can be seen that the size of the polished face is not uniform after the back throwing, and the polished surface is not flat. Fig. 2 is a photomicrograph showing the polished surface of the ruthenium surface obtained in the present embodiment. It can be seen from Fig. 2 that the surface of the ruthenium sheet has a uniform and smooth square structure with a size of about 20 to 30 μm (micrometer).

Example 2

First polishing and then texturing, wherein the polishing process takes the following steps: 1) preparing an additive for the crystalline bismuth alkaline polishing liquid: Dissolve 0.5 g of polyethylene glycol, 0.5 g of alkyl glycoside, 0.5 g of ammonium stearate, 1 g of ethylenediamine, 1 g of ammonium sulfate, and 2 g of urea in deionized water using deionized water as solvent. , 100 grams of additives are prepared; 2) alkaline solution is prepared: 20 grams of tetramethylammonium hydroxide is dissolved in deionized water to obtain 1000 grams of alkaline solution; 3) 10 grams of additive is added to 1000 grams of alkaline solution; 4) The single crystal crucible is immersed in a polishing liquid for polishing, the temperature is controlled at 60 degrees Celsius, and the time is controlled at 0.5 minutes.

A scanning electron micrograph of a conventional velvet surface is shown in Fig. 3. Fig. 4 shows a scanning electron micrograph of the velvet surface after polishing in this embodiment. From Fig. 4, a polishing-texturing process can be seen. The suede obtained afterwards has a more uniform fleece-like suede, and the pyramid has no superimposed state.

Example 3

The first step is to polish the back, wherein the polishing process takes the following steps: 1) preparing an additive for the crystalline bismuth alkaline polishing solution: using deionized water as a solvent, 1.5 g of polyethylene glycol, 1.5 g of alkyl glycoside, 1 g of stearin Ammonium acid, 2 grams of ethylenediamine, 4 grams of ammonium sulfate, 6 grams of urea dissolved in deionized water to make 100 grams of additives; 2) Preparation of alkaline solution: 30 grams of potassium hydroxide dissolved in deionized water , obtaining 1000 grams of alkaline solution; 3) adding 40 grams of additive to 1000 grams of alkaline solution; 4) The polycrystalline silicon flakes are immersed in a polishing liquid for polishing, the temperature is controlled at 70 degrees Celsius, and the time is controlled at 2.5 minutes.

Example 4

On the basis of Example 1, the sodium hydroxide was changed to 10 g, and the polyethylene glycol was 1 g.

Example 5

On the basis of Example 1, the sodium hydroxide was changed to 12 g, and the alkyl glycoside was 1 g.

Example 6

On the basis of Example 1, sodium hydroxide was changed to 15 g, and ammonium stearate was 0.7 g.

Example 7

On the basis of Example 1, the sodium hydroxide was changed to 18 g, and the ethylenediamine was 1.5 g.

Example 8

On the basis of Example 1, the sodium hydroxide was changed to 20 g and the ammonium sulfate was 1.4 g.

Example 9

On the basis of Example 1, the sodium hydroxide was changed to 25 g, and the urea was 2.5 g.

Example 10

On the basis of Example 1, sodium hydroxide was changed to 30 g, and 15 g of an additive was added to 1000 g of an alkaline solution.

Example 11

On the basis of Example 1, the sodium hydroxide was changed to 40 g, and the polyethylene glycol was 1.8 g.

Example 12

On the basis of Example 2, tetramethylammonium hydroxide was changed to 23 g, and polyethylene glycol was 0.7 g.

Example 13

On the basis of Example 2, tetramethylammonium hydroxide was changed to 25 g, and alkyl glycoside was 0.6 g.

Example 14

On the basis of Example 2, tetramethylammonium hydroxide was changed to 27 g, and ammonium stearate was 1.5 g.

Example 15

On the basis of Example 2, tetramethylammonium hydroxide was changed to 30 g, and ethylenediamine was 2.5 g.

Example 16

On the basis of Example 2, 40 g of tetramethylammonium hydroxide was changed, and ammonium sulfate was 2 g.

Example 17

On the basis of Example 2, 50 g of tetramethylammonium hydroxide was changed, and urea was 3 g.

Example 18

On the basis of Example 2, the change of tetramethylammonium hydroxide was 55 grams at 1000. 20 grams of the additive was added to the gram alkaline solution.

Example 19

On the basis of Example 2, the amount of tetramethylammonium hydroxide was changed to 60 g, and the alkyl glycoside was 1.7 g.

Example 20

On the basis of Example 3, potassium hydroxide was changed to 10 g, and polyethylene glycol was 1.3 g.

Example 21

On the basis of Example 3, potassium hydroxide was changed to 13 g, and alkyl glycoside was 1.4 g.

Example 22

On the basis of Example 3, potassium hydroxide was changed to 15 g, and ammonium sulfate was 2.5 g.

Example 23

On the basis of Example 3, potassium hydroxide was changed to 17 g, and urea was 4 g.

Example 24

On the basis of Example 3, potassium hydroxide was changed to 20 g, and 30 g of an additive was added to 1000 g of an alkaline solution.

Example 25

On the basis of Example 3, potassium hydroxide was changed to 25 g and ammonium sulfate was 4.5 g.

Example 26

On the basis of Example 3, potassium hydroxide was changed to 40 g, and urea was 7 g.

Example 27

On the basis of Example 3, 50 parts of potassium hydroxide was changed, and 50 g of an additive was added to 1000 g of an alkaline solution.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make several improvements and retouchings without departing from the technical principles of the present invention. It should also be considered as the scope of protection of the present invention.

Claims (8)

An additive for a crystalline bismuth alkaline polishing liquid characterized by being 0.5 to 2% polyethylene glycol, 0.5 to 2% alkyl glycoside, 0.5 to 2% ammonium stearate, and 1 to 3% by mass. Ethylenediamine, 1~5% ammonium sulfate, 2~8% urea and the balance of water. An additive for a crystalline cerium-base polishing liquid according to claim 1, which is characterized in that it is composed of 1 to 1.5% polyethylene glycol, 1 to 1.5% alkyl glycoside, 0.5 to 1% by mass. Ammonium stearate, 1~2% ethylenediamine, 2~4% ammonium sulfate, 3~6% urea and the balance of water. An additive for a crystalline cerium-base polishing liquid according to claim 1 or 2, wherein the water is deionized water. A crystalline bismuth alkaline polishing liquid characterized by being prepared by the following steps on the basis of mass: 1) dissolving sodium hydroxide, potassium hydroxide or tetramethylammonium hydroxide in deionized water to obtain an alkaline solution; The sodium hydroxide and the potassium hydroxide have a mass percentage of 1 to 5%; the tetramethylammonium hydroxide has a mass percentage of 2 to 6%; 2) the patent application range is 1 to 3 Adding the additive of the crystalline cerium alkaline polishing liquid according to any one of the steps to the alkaline solution in the step 1) to obtain a crystalline cerium alkaline polishing liquid; wherein the crystallization alkaline alkaline polishing liquid additive and the The quality ratio of the alkaline solution is 1 to 6:100. The crystalline cerium-base polishing liquid according to claim 4, wherein the sodium hydroxide and the potassium hydroxide have a mass percentage of 2 to 3% based on the mass; the tetramethyl group. The mass percentage of ammonium hydroxide is 3 to 5%. The crystalline bismuth alkaline polishing liquid according to claim 4, which is characterized in that The mass percentage of the sodium hydroxide and the potassium hydroxide is 1 to 1.5% based on the mass; and the mass percentage of the tetramethylammonium hydroxide is 2 to 2.5%. The crystalline bismuth-based polishing liquid according to any one of claims 4 to 6, wherein the quality ratio of the additive of the crystalline cerium alkaline polishing liquid to the alkaline solution is based on mass. It is 2~4:100. A method for polishing a crystallization ruthenium, characterized in that a single crystal or a polycrystalline ruthenium sheet is immersed in a crystallization alkaline kiln polishing liquid according to any one of claims 4 to 7, and the temperature is controlled at 60 ° C. ~80 degrees, time control is 0.5~5 minutes.