CN111593412B

CN111593412B - Additive for chain type texture surface making of monocrystalline silicon piece and application thereof

Info

Publication number: CN111593412B
Application number: CN202010448014.5A
Authority: CN
Inventors: 周树伟; 张丽娟; 陈培良; 贺婷婷
Original assignee: Changzhou Shichuang Energy Co Ltd
Current assignee: Changzhou Shichuang Energy Co Ltd
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2021-03-30
Anticipated expiration: 2040-05-25
Also published as: CN111593412A

Abstract

The invention discloses an additive for chain type texture surface making of monocrystalline silicon wafers, which comprises the following components in percentage by mass: 0.2 to 2.0 percent of polyethyleneimine, 0.5 to 10 percent of fucosan, 0.1 to 0.5 percent of polyacrylamide, 0.1 to 2.0 percent of polyether amine and the balance of water. The additive is added into the texturing solution for the chain-type texturing of the monocrystalline silicon wafer, so that the texturing time of the chain-type texturing can be shortened to 3min, the productivity can be improved, the reflectivity of a texturing sheet can be kept at 11% -12%, the reflectivity of the texturing sheet is basically equivalent to that of a texturing sheet obtained by groove-type texturing, and the silicon wafer has better conversion efficiency.

Description

Additive for chain type texture surface making of monocrystalline silicon piece and application thereof

Technical Field

The invention relates to the field of photovoltaics, in particular to an additive for chain type texture surface making of monocrystalline silicon wafers and application thereof.

Background

Solar energy is the cleanest energy on earth, and people always hope to be directly utilized to the maximum extent. Solar cells, a device for collecting solar energy and directly converting the solar energy into electric energy, have been invented by people and are gradually becoming the leading role of new energy industries. Among them, crystalline silicon solar cells are currently used for large-scale industrial production due to their excellent overall performance. In recent years, due to the rapid development of monocrystalline silicon rod pulling and slicing technologies in the industry, the production cost of monocrystalline silicon slices is rapidly reduced, and monocrystalline silicon batteries gradually compress the market share of polycrystalline silicon batteries and become a favorite of the market.

As the first process of the production of the monocrystalline silicon solar cell, the texturing is a very important step. Texturing is to form a 'textured' structure on the surface of a silicon wafer through alkali etching or mechanical etching and the like, the 'textured' structure can reduce the reflection of sunlight and improve the light absorption rate, so that the photoelectric conversion efficiency of a solar cell is improved, and due to too high cost of other etching modes, alkali etching is the mainstream texturing mode at present. It was found by testing that a cell sheet that was not textured will reflect at least 30% or more of the incoming sunlight. Therefore, it is an important research direction to reduce the light reflectance of silicon wafers by texturing. According to the reaction mechanism of silicon and alkali, the light trapping structure is difficult to form on the surface of the monocrystalline silicon wafer by simple alkali etching without adding any additive, and the additive becomes an important legal instrument for controlling the light trapping structure.

In industrial production, a common alkali texturing mode is groove type, and in the method, because a silicon wafer is completely immersed in texturing liquid, the texturing effect is good, and the reflectivity of a texturing sheet is basically 11% -12%. However, in the groove type texturing process, the silicon wafer is vertically arranged in the texturing liquid, so that the uniformity is a problem, and the silicon wafer is difficult to independently pick out when the problems of texturing dirt, color difference and the like occur. Under the condition, the chain type texturing mode is very advantageous, firstly, the silicon wafer is horizontally placed in the chain type texturing process, the texturing liquid can be uniformly spread on the surface, the texturing uniformity is good, secondly, the texturing process is controllable, when the texturing problem occurs, the wafer with the problem can be singly picked out, and the rework rate is reduced. However, the biggest limitation condition of the chain type texturing is that the silicon wafers are all horizontally placed, the length of a texturing machine table needs to be lengthened, and the occupied area is large. Therefore, the texturing time is reduced, the texturing of the monocrystalline silicon wafer is completed in a faster time, but the texturing time is shortened, the texturing effect is weakened, and the reflectivity of the silicon wafer is obviously increased, so that a monocrystalline silicon chain-type texturing additive capable of preparing the low-reflectivity silicon wafer is needed to make up for the problem.

Disclosure of Invention

The invention aims to provide an additive for chain type texture surface making of a monocrystalline silicon piece, which is added into texture surface making liquid for chain type texture surface making of the monocrystalline silicon piece, can shorten texture surface making time and can obtain a texture surface making piece with low reflectivity.

In order to achieve the aim, the invention provides an additive for chain type texture surface making of monocrystalline silicon slices, which comprises the following components in percentage by mass: 0.2 to 2.0 percent of polyethyleneimine, 0.5 to 10 percent of fucosan, 0.1 to 0.5 percent of polyacrylamide, 0.1 to 2.0 percent of polyether amine and the balance of water.

Preferably, the polyethyleneimine is selected from one or more of polyethyleneimine with a molecular weight of 600, polyethyleneimine with a molecular weight of 1800, polyethyleneimine with a molecular weight of 1000, and polyethyleneimine with a molecular weight of 7000.

Preferably, the polyacrylamide is one or more selected from anionic polyacrylamide with the molecular weight of 800 ten thousand, anionic polyacrylamide with the molecular weight of 1000 ten thousand and anionic polyacrylamide with the molecular weight of 1200 ten thousand.

Preferably, the polyether amine is one or two of polyether amine D230 and polyether amine D400.

Preferably, the water is deionized water.

The invention also provides a monocrystalline silicon piece chain type texturing solution which contains the alkali solution and the additive, wherein the mass ratio of the additive to the alkali solution is 0.5-2.5: 100, and the alkali solution is an inorganic alkali aqueous solution.

Preferably, the alkali solution is 2-5 wt% of sodium hydroxide or potassium hydroxide aqueous solution.

The invention also provides a chain type texture surface making method of the monocrystalline silicon slice, which utilizes the texture surface making liquid to carry out chain type texture surface making on the monocrystalline silicon slice.

Preferably, the chain-type texture surface making method for the monocrystalline silicon wafer comprises the following specific steps:

1) preparing an additive: adding 0.2-2.0% of polyethyleneimine, 0.5-10% of fucosan, 0.1-0.5% of polyacrylamide and 0.1-2.0% of polyetheramine into the balance of water, and mixing uniformly to prepare an additive;

2) preparing a texturing solution: adding the texturing additive prepared in the step 1) into an alkaline solution, and uniformly mixing to prepare a texturing solution; the mass ratio of the texturing additive to the aqueous alkali is 0.5-2.5: 100; the alkali solution is an inorganic alkali aqueous solution;

3) putting the monocrystalline silicon wafer flatly into a chain type texturing device, and performing chain type texturing on the monocrystalline silicon wafer by using the texturing liquid prepared in the step 2), wherein the texturing temperature is 85-95 ℃, and the texturing time is 3-5 min.

Preferably, in the step 3), the texturing temperature is 90-95 ℃, and the texturing time is 3-3.5 min.

The invention has the advantages and beneficial effects that: the additive is added into the texturing solution for the chain-type texturing of the monocrystalline silicon wafer, so that the texturing time of the chain-type texturing can be shortened to 3min, the productivity can be improved, the reflectivity of a texturing sheet can be kept at 11% -12%, the reflectivity of the texturing sheet is basically equivalent to that of a texturing sheet obtained by groove-type texturing, and the silicon wafer has better conversion efficiency.

Compared with the groove type texturing method, the reaction temperature of the chain type texturing is higher, so that great limitation is brought to the selection of the additive formula, and the most important performance is that the components of the additive need good thermal stability, and strong adsorbability is needed. In the formula of the low-reflectivity chain type single crystal texturing additive provided by the invention, all components have good thermal stability, and the texturing can be stably completed at the heating temperature of 95 ℃ for chain type texturing through laboratory verification. The polyethyleneimine and the fucosan are used as main velvet outlet agents in a matched mode, so that the velvet outlet performance is good, the polyacrylamide is used as a velvet surface optimizing agent, so that the velvet outlet is more uniform, the sheet inside is more uniform in appearance, and the polyether amine is used as a defoaming agent, so that the influence of bubbles in the reaction process can be effectively eliminated, and the velvet making appearance is more complete.

The polyethyleneimine has polar group amino and hydrophobic group vinyl structures, can be combined with different substances, has high adhesiveness and adsorptivity, has good activity of amino in a molecular chain, and can act with different groups, so that the polyethyleneimine can be combined with Si-H bonds on the surface of a silicon wafer to form a stable nucleation center. Fucosan is used as a polysaccharide, the molecule contains a large amount of hydroxyl, so that the fucosan has good hydrophilicity, and-OH can be combined with Si-H bonds to form a hydrogen bond effect, so that the fucosan molecule has adsorbability, a large amount of binding points are arranged on the surface of a silicon wafer and are used as nucleation centers, the fucosan and polyethyleneimine are compounded together to achieve good down-producing performance, and the nucleation points grow up to form a pyramid suede along with the extension of reaction time. In the texturing process, due to high temperature and quick reaction, a large amount of heat is released along with the reaction, the texturing uniformity of the texturing agent is greatly tested, the polyacrylamide has high molecular weight, long molecular chains of the polyacrylamide are wound and adsorbed with the texturing agent and are uniformly distributed on the surface of a silicon wafer, the uniformity of the texturing surface can be obviously improved, and the appearance uniformity is macroscopically embodied without color difference. The polyether amine is a polymer with a polyether structure as a main chain and an amino group as a terminal active functional group, has low surface tension and strong adsorbability, is favorable for removing bubbles in a system, and ensures that the surface of a silicon wafer after texture etching has no bubble marks and has uniform appearance.

Drawings

FIG. 1 shows the textured topography of the silicon wafer obtained in example 1.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

Example 1

1 part by mass of polyethyleneimine 1800, 5 parts by mass of fucosan, 0.2 part by mass of polyacrylamide (molecular weight 800 ten thousand), 0.5 part by mass of polyetheramine D230 and 93.3 parts by mass of deionized water are mixed and stirred uniformly to prepare an additive solution; then sequentially adding an additive, potassium hydroxide and deionized water according to the mass ratio of 1:4:100, and uniformly stirring to prepare a texturing solution; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and the prepared texture surface making liquid is adopted to carry out chain type texture surface making on the monocrystalline silicon piece, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3.5 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.24.

The texture of the texturing sheet obtained in example 1 is shown in figure 1, the size of texturing pyramids is small, the texturing density is high, and the pyramids are lapped with each other to form a slightly twisted shape, so that the reflectivity is low.

Example 2

1 part by mass of polyethyleneimine 1800, 10 parts by mass of fucosan, 0.2 part by mass of polyacrylamide (molecular weight 800 ten thousand), 0.5 part by mass of polyetheramine D230 and 88.3 parts by mass of deionized water are mixed and stirred uniformly to prepare an additive solution; then sequentially adding an additive, potassium hydroxide and deionized water according to the mass ratio of 1:4:100, and uniformly stirring to prepare a texturing solution; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and the prepared texture surface making liquid is adopted to carry out chain type texture surface making on the monocrystalline silicon piece, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3.5 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.63.

Example 3

Mixing and stirring 0.5 part by mass of polyethyleneimine 1800, 0.5 part by mass of polyethyleneimine 70000, 5 parts by mass of fucosan, 0.2 part by mass of polyacrylamide (with a molecular weight of 800 ten thousand), 0.5 part by mass of polyetheramine D230 and 93.3 parts by mass of deionized water uniformly to prepare an additive solution; then sequentially adding an additive, potassium hydroxide and deionized water according to the mass ratio of 1:4:100, and uniformly stirring to prepare a texturing solution; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and the prepared texture surface making liquid is adopted to carry out chain type texture surface making on the monocrystalline silicon piece, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3.5 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.30.

Example 4

1 part by mass of polyethyleneimine 10000, 5 parts by mass of fucosan, 0.2 part by mass of polyacrylamide (molecular weight 1000 ten thousand), 0.5 part by mass of polyetheramine D400 and 93.3 parts by mass of deionized water are mixed and stirred uniformly to prepare an additive solution; then sequentially adding an additive, potassium hydroxide and deionized water according to the mass ratio of 1:4:100, and uniformly stirring to prepare a texturing solution; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and the prepared texture surface making liquid is adopted to carry out chain type texture surface making on the monocrystalline silicon piece, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3.5 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.18.

Example 5

1 part by mass of polyethyleneimine 1800, 5 parts by mass of fucosan, 0.2 part by mass of polyacrylamide (molecular weight 800 ten thousand), 0.5 part by mass of polyetheramine D230 and 93.3 parts by mass of deionized water are mixed and stirred uniformly to prepare an additive solution; then sequentially adding an additive, potassium hydroxide and deionized water according to the mass ratio of 1:4:100, and uniformly stirring to prepare a texturing solution; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and chain type texture surface making is carried out on the monocrystalline silicon piece by adopting the prepared texture surface making liquid, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.85.

Comparative example 1

Sequentially adding an additive for making the wool (product model: TS51, produced by Yongzhou Shishao energy resources Co., Ltd.) according to the mass ratio of 1:4:100, and uniformly stirring to prepare a wool making liquid; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and chain type texture surface making is carried out on the monocrystalline silicon piece by adopting the prepared texture surface making liquid, wherein the texture surface making temperature is 90 ℃, and the reaction time is 7 min. The average reflectivity of the flocked sheet after the flocking was completed was measured to be 11.76.

Comparative example 2

Sequentially adding an additive for making the wool (product model: TS51, produced by Yongzhou Shishao energy resources Co., Ltd.) according to the mass ratio of 1:4:100, and uniformly stirring to prepare a wool making liquid; the monocrystalline silicon piece is flatly placed and input into a chain type texture surface making device, and chain type texture surface making is carried out on the monocrystalline silicon piece by adopting the prepared texture surface making liquid, wherein the texture surface making temperature is 90 ℃, and the reaction time is 3 min. The average reflectivity of the flocked sheet was measured to be 14.52 after the flocking was completed.

In the above embodiments and the reflectivity test of the texturing sheet obtained in each proportion, the reflectivity test instrument adopts an NXT Helios-rc reflectivity test instrument, and the average value of the reflectivity obtained by respectively testing the front and back surfaces of the silicon wafer is used as the average reflectivity.

Comparing comparative example 1 with comparative example 2, it is understood that simply shortening the texturing time increases the average reflectance of the textured sheet.

Comparing the average reflectivity of the flocking sheets obtained in each example and each proportion, the additive of the invention can greatly shorten the flocking time of chain type flocking on the premise of controlling the reflectivity of the flocking sheet below 12%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The additive for chain type texture surface making of the monocrystalline silicon piece is characterized by comprising the following components in percentage by mass: 0.2 to 2.0 percent of polyethyleneimine, 0.5 to 10 percent of fucosan, 0.1 to 0.5 percent of polyacrylamide, 0.1 to 2.0 percent of polyether amine and the balance of water.

2. The additive for chain type texture surface making of the monocrystalline silicon wafer according to claim 1, wherein the polyethyleneimine is one or more selected from the group consisting of polyethyleneimine with a molecular weight of 600, polyethyleneimine with a molecular weight of 1800, polyethyleneimine with a molecular weight of 1000, and polyethyleneimine with a molecular weight of 7000.

3. The additive for chain type texture surface making of the monocrystalline silicon piece according to claim 1, wherein the polyacrylamide is one or more selected from anionic polyacrylamide with molecular weight of 800 ten thousand, anionic polyacrylamide with molecular weight of 1000 ten thousand and anionic polyacrylamide with molecular weight of 1200 ten thousand.

4. The additive for chain-type texture etching of the monocrystalline silicon wafer according to claim 1, wherein the polyether amine is one or both of polyether amine D230 and polyether amine D400.

5. The additive for chain-type texture etching of a monocrystalline silicon wafer according to claim 1, wherein the water is deionized water.

6. The chain type texturing solution for monocrystalline silicon wafer texturing is characterized by comprising an alkali solution and the additive as defined in any one of claims 1 to 5, wherein the mass ratio of the additive to the alkali solution is 0.5-2.5: 100, and the alkali solution is an inorganic alkali aqueous solution.

7. The chain type texture surface making solution for the monocrystalline silicon piece according to claim 6, wherein the alkali solution is 2-5 wt% of sodium hydroxide or potassium hydroxide aqueous solution.

8. A method for chain-type texturing of a single-crystal silicon wafer, characterized in that the texturing liquid of claim 6 or 7 is used to perform chain-type texturing of the single-crystal silicon wafer.

9. The chain type texture surface making method of the monocrystalline silicon piece according to claim 8, which comprises the following specific steps:

2) preparing a texturing solution: adding the additive prepared in the step 1) into an alkali solution, and uniformly mixing to prepare a texturing solution; the mass ratio of the additive to the alkali solution is 0.5-2.5: 100; the alkali solution is an inorganic alkali aqueous solution;

10. The chain type texture surface making method for the monocrystalline silicon piece according to claim 9, wherein in the step 3), the texture surface making temperature is 90-95 ℃, and the texture surface making time is 3-3.5 min.