Technology for production of metallic nanolayers on silver electric contacts of silicon solar cells using chemical method

FIELD: material engineering.

SUBSTANCE: method of application of metallic nanolayers in chemical method involves the technology of chemical sedimentation of metals, in particular of copper (Cu) at the speed 1 μm/min with the solution temperature 50 to 60°C. As the basic copper-containing reagent for applying metallic nanolayers on silver electric contacts of silicon solar cells the inorganic copper salts are used. Technical result of the invention is the thickening of frontal electric contact of solar cell by sedimentation of metals, in particular copper, with good electric conductivity, in order to compensate or improve its increased electric conductivity.

EFFECT: increased effectiveness of solar cell operation during transformation of high-density radiation and decreased self-cost of its manufacturing.

4 cl, 4 dwg

 

The invention relates to the coating of metal nanolayers by a chemical process, in particular on the silver electrical contacts of silicon solar cells.

The closest analogue of the present invention is an invention relating to a method of coating by chemical means for coating the product is suitable for forming a conductive film on the end faces of the metal or semiconductor (EN 2225460).

The disadvantage of this invention is the lack of selective deposition of metal from the chemical solution on the specific metal product.

The proposed method of applying metallic nanolayers chemical method consists in the use of technology chemical precipitation of metals, in particular copper (Cu), with a speed of 1 μm/min when the temperature of the solution from 50 to 60°C.

As the original copper-containing reagent for applying metallic nanolayers on silver electrical contacts of silicon solar cells used inorganic salts of copper.

The object of the invention is used, a solar cell based on crystalline silicon Si<P>/SiNx(70 nm)/Si<B> aluminum contact on the back plate and the front silver contact. Figure 1 shows the position of the desired silver contacts n the front surface of the silicon wafer.

On the exposed side of the silicon wafer has a front electrical contact of silver in the form of a lattice, which is made porous due to technical and economic requirements. The width of the individual strips is 120 μm, a height of 30 μm.

The efficiency of a solar cell can be increased by reducing the width of the contact strips to 50 μm and to increase its conductivity by filling the pores of the silver and the increase in thickness due to the cheap metal. Thus there is a need to improve the front contacts in current industrial standard technologies for the manufacturing of solar cells.

According to the existing technology manufacturing silver contact is made by applying silver paste on the surface of a silicon plate by punching through the metal mask. The height of the contact strips is 30 μm, the width of 120-140 microns. Next, the paste is dried with hot air for 1 minute Then the plate goes on the conveyor belt furnace annealing.

The burn paste in antirefleksionnoe SiN layer ARC is produced at temperatures 840-980°C. At the same time there is combustion of the organic components of the original paste and the formation of porous structure of the silver strips (2, 3). The deposition of copper on the silver should occur after the stage of annealing.

Technical the cue the invention - seal front electrical contact of the solar cell deposition of metal, in particular copper (Cu), good electrical conductivity to its high electrical resistance was compensated or superior.

It is proposed to fill the pores of the silver electrical contact with the metal particles and build up on its surface a layer of dense metal with a thickness of 5 microns.

Method of applying metal nanolayers on silver electrical contacts of silicon solar cells by chemical means according to the invention can be made as follows:

(1) industrial solar cell consisting of polycrystalline plates of a thickness exceeding 100 μm, immersed in a glass cuvette with a volume of 1 liter in solutions of inorganic salts of copper at 60°C;

(2) as chemical solutions are used, the following inorganic salts of copper:

- copper sulfate CuSO45H2O brand CHP;

the copper nitrate Cu(NO3)25H2O brand CHP;

- copper chloride CuCl25H2O brand CHP;

(3) coating silver electrical contact with the copper in the solution of nitrate of copper appears after 1 minute after immersion in it industrial solar cell. The coating thickness depends on the concentration of the solution. The most prominent color of the coating can be the concentration of salt 2.0 g of salt Cu/100 ml H 2O.

(4) the deposition of metal (Cu) occurs only on the silver pin stripes, this prevents the deposition of metal on the surface of the antireflective layer of a silicon wafer, its reverse side and edges (figure 4).

The use of this technology allows to ensure the implementation of the nanoparticles of metal (Cu) in the micropores front electric silver contact silicon solar cells, which in turn reduces the electrical resistance of the front contact on the serial solar cells.

In addition, the application of this technology provides the following features:

- high stability of the solutions on the chemical composition, the ease of dosing and correction of concentrations, low technological maintenance costs baths deposition;

- no increase in width of the contact strips over 50%;

- no reduction of the contact resistance and adhesion of the contact;

- no harmful to human health cyanide solutions and organic solvents.

The use of cheap reagents for the deposition of metal, giving the opportunity to reduce the cost of manufactured industrial solar cells, meets the following conditions:

- temperature deposition of metal does not exceed 50-60°C;

the deposition rate of the metal with the hat 1 μm/min;

the deposition can be made from aqueous solutions

Scientific and technical aspects of the developed method consists in minimizing the impact of working solutions on the environment and their compatibility with existing manufacturing technology industrial solar cells.

1. Method of applying metal nanolayers chemical method, characterized in that for the deposition of metal on the surface of the silver contact industrial solar cell as chemical solutions used inorganic salts of copper.

2. The method according to claim 1, characterized in that the temperature of deposition of the metal (copper) from the chemical solution of inorganic salts of copper is in the range from 50 to 60°C.

3. The method according to claim 1, characterized in that the deposition rate of the metal (copper) from the chemical solution of inorganic salts of copper is 1 μm/min

4. The method according to claim 1, characterized in that the deposition of metal (copper) from the chemical solution of inorganic salts of copper occurs only on the silver contact strips industrial solar cell, this prevents the deposition of metal on the surface of the antireflective layer of a silicon wafer, its reverse side and edges.



 

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1 ex, 1 tbl

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2 tbl, 7 ex

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