CN105679845A - Method for reducing cost of crystalline silicon solar cell and improving efficiency - Google Patents

Abstract

The invention discloses a method for reducing the cost of a crystalline silicon solar cell and improving the efficiency. The method is a technology for preparing a front grid line electrode by a copper plating method and replacing a noble metal silver of a traditional grid line with a metal copper, so that the target of reducing the cost is achieved. Meanwhile, fabrication of a fine grid line is not restricted by a screen printing technique, so that the width of the fine grid line can be reduced; the light shading area of the front surface is reduced; the current is improved; and the efficiency of the cell is improved.

Description

A method to reduce the cost of crystalline silicon solar cells and improve the efficiency

technical field

The invention relates to a method for reducing the cost of crystalline silicon solar cells and improving efficiency, and belongs to the technical field of solar photovoltaics.

Background technique

Facing the global energy crisis, solar photovoltaic power generation technology has become a new development hotspot in the semiconductor industry. The manufacturing of crystalline silicon solar cells is divided into processes such as texturing/cleaning, diffusion, etching/post-cleaning, PECVD coating, screen printing, sintering, testing and sorting. The traditional screen printing process requires expensive silver paste as the conductive material on the front, and high temperature treatment is required after printing to make the paste burn through the anti-reflection silicon nitride film on the front.

Screen printing technology is currently the most popular technology for collecting current to form cells in the crystalline silicon solar cell industry. The principle is to use silver paste as the front conductive material, and high temperature treatment makes the silver paste burn through the front silicon nitride anti-reflection layer, so that the silver paste contacts the silicon substrate to form an ohmic contact and collect current. However, due to technical reasons, the screen printing technology can only print the thin grid lines for collecting current to a width of about 40um. Considering the need to fully collect current, the number of thin grid lines is large (about 100), which will result in a large shading area; at the same time, the thermal expansion coefficients of the silicon substrate and the back field (the main component is aluminum) are different, and the sintering at high temperature Sometimes it will lead to the warping of the battery, which will easily cause the breakage of the battery sheet and the crack of the substrate, reduce the product performance and increase the production cost. On the other hand, expensive metal silver needs to be used when collecting the positive current, resulting in high production costs of crystalline silicon cells (the cost of silver paste accounts for about half of the production cost of crystalline silicon cells).

Contents of the invention

The purpose of the present invention is to provide a method for reducing the cost of crystalline silicon solar cells and improving efficiency. The method is to thermally cover a layer of protective film on the surface of the reflective film, prepare a grid pattern on the film to replace the screen printing technology, and then use The method of electroplating copper to prepare the front grid line electrode uses a low-cost metal copper with abundant earth reserves as a technology to replace the traditional grid line precious metal silver to achieve the purpose of reducing costs; at the same time, the prepared grid line pattern is not affected by screen printing. Technical constraints can reduce the width of fine grid lines, reduce the shading area of the front, increase the current, and then improve the efficiency of the battery.

A method for reducing the cost of crystalline silicon solar cells and improving efficiency, comprising the following steps:

A silicon nitride film with anti-reflection effect is deposited on the front of the crystalline silicon solar cell to be processed, and an aluminum back field and a back electrode are printed on the back;

(1) Cover the protective film:

A layer of protective film is thermally covered on the surface deposited with silicon nitride anti-reflection film, and the front grid line pattern is obtained on the protective film according to the requirements of the front grid line pattern;

(2) Prepare the grid pattern on the protective film:

Etch the area without protective film protection, remove the silicon nitride anti-reflection film in this area, expose the Si substrate in this area, and obtain the front grid line circuit pattern, wherein the protective film has anti-corrosion components, and the silicon nitride anti-reflection film in the area is etched. During the process of siliconization, it can block the etching solution and protect the silicon nitride film under the area covered by the protective film from being corroded;

(3) Preparation of conductive grid lines:

Contact the front of the product obtained in the previous step with the palladium chloride activation solution at room temperature to form a series of activation points on the surface of the exposed Si substrate. Use hydrochloric acid and hydrofluoric acid to control the pH value of the activation solution at 2~3, and the activation time For 20~60s, contact the nickel plating solution frontally at room temperature, deposit a layer of nickel barrier layer on the substrate, use hydrochloric acid to control the pH value of the nickel plating solution at 3.5~4.5, the time is 120~180s, the thickness is 2~4um, Under the guidance of electricity, contact the copper plating solution at room temperature to form a conductive copper layer on the barrier layer. Use sulfuric acid to control the pH value of the copper plating solution at 3~4, the time is 20~30min, and the thickness is 20~30um;

(4) Remove the protective film:

Use a film remover to remove the protective film;

(5) Deposition of anti-oxidation protective layer:

Contact the nickel plating solution frontally at room temperature, and deposit an oxidation protection layer on the surface of the conductive copper layer for 60-100s with a thickness of 1-2um or deposit a silver layer as a protective layer under the guidance of light and electricity for 50~80s, the thickness is 0.5~1.5um.

A method for reducing the cost of crystalline silicon solar cells and improving efficiency, comprising the following steps:

A silicon nitride film with anti-reflection effect is deposited on the front of the crystalline silicon solar cell to be processed, and an aluminum back field and a back electrode are printed on the back;

(1) Cover the protective film:

Spray 70°C black paraffin on the surface of the silicon nitride film by thermal spraying, and use a high-frequency laser to make grooves on the surface of the paraffin. The groove pattern is the required front grid line pattern, and the width of the groove can be determined by the diameter of the laser beam. to adjust;

(2) Prepare the grid pattern on the protective film:

The front of the battery is exposed to a hydrofluoric acid etching solution with a volume concentration of 10-30%, and the silicon nitride film at the groove is removed to expose the silicon substrate under the film, and the front grid line pattern is obtained. After the process is completed, take it out and clean it;

(3) Preparation of conductive grid lines:

Contact the front of the product obtained in the previous step with the palladium chloride activation solution at room temperature to form a series of activation points on the surface of the bare silicon substrate. Use hydrochloric acid and hydrofluoric acid to control the pH value of the activation solution at 2~3, and the activation time For 20~60s, contact the nickel plating solution frontally at room temperature, deposit a layer of nickel barrier layer on the substrate, use hydrochloric acid to control the pH value of the nickel plating solution at 3.5~4.5, the time is 120~180s, the thickness is 2~4um, Under the guidance of electricity, the front side contacts the copper plating solution at room temperature to form a conductive copper layer on the barrier layer. Use sulfuric acid to control the pH value of the copper plating solution at 3~4, the time is 20~30min, and the thickness is 20~30um. After the process is completed, take it out for cleaning;

(4) Remove the protective film:

Use chloroform to remove the protective film, and take it out for cleaning after the process is completed;

(5) Deposition of anti-oxidation protective layer:

At room temperature, the front of the battery is exposed to the nickel plating solution, and an oxidation protective layer is deposited on the surface of the conductive copper layer for 60-100s with a thickness of 1-2um or a silver layer is deposited as a protective layer under the guidance of light and electricity. It takes 50~80s, and the thickness is 0.5~1.5um. After the process is completed, take it out for cleaning and drying.

A method for reducing the cost of crystalline silicon solar cells and improving efficiency, comprising the following steps:

A silicon nitride film with anti-reflection effect is deposited on the front of the crystalline silicon solar cell to be processed, and an aluminum back field and a back electrode are printed on the back;

(1) Cover the protective film:

Attach a layer of dry film on the surface of the deposited silicon nitride anti-reflection film using a roller lamination process. The lamination temperature is 120°C and the speed is 3.5~4m/min, and it is placed in an exposure machine with ultraviolet rays or shorter wavelengths. , the surface of the laminated film is facing the light source, and the pattern on the film on which the front grid line pattern has been made is transferred to the dry film by pattern transfer technology;

Among them, the dry film is the AP3810 dry film purchased at Guangzhou Changxing Dry Film Co., Ltd.;

(2) Prepare the grid pattern on the protective film:

When developing, use 30°C and 0.5~2% Na ₂ CO ₃ solution to spray on the surface of the exposed battery. After washing, a dry film with a clear grid circuit pattern structure is formed on the surface of the battery, and the process is completed. Take out and clean;

(3) Preparation of conductive grid lines:

Contact the front of the product obtained in the previous step with the palladium chloride activation solution at room temperature to form a series of activation points on the surface of the bare silicon substrate. Use hydrochloric acid and hydrofluoric acid to control the pH value of the activation solution at 2~3, and the activation time For 20~60s, contact the nickel plating solution frontally at room temperature, deposit a layer of nickel barrier layer on the substrate, use hydrochloric acid to control the pH value of the nickel plating solution at 3.5~4.5, the time is 120~180s, the thickness is 2~4um, Under the guidance of electricity, the front side contacts the copper plating solution at room temperature to form a conductive copper layer on the barrier layer. Use sulfuric acid to control the pH value of the copper plating solution at 3~4, the time is 20~30min, and the thickness is 20~30um. After the process is completed, take it out for cleaning;

(4) Remove the protective film:

Remove the protective film with a film remover, and take it out for cleaning after the process is completed;

Among them, the film removal solution is the AP38 series film removal solution purchased at Guangzhou Changxing Dry Film Co., Ltd.;

(5) Deposition of anti-oxidation protective layer:

Contact the nickel plating solution frontally at room temperature, and deposit an oxidation protection layer on the surface of the conductive copper layer for 60-100s with a thickness of 1-2um or deposit a silver layer as a protective layer under the guidance of light and electricity for 50~80s, the thickness is 0.5~1.5um, after the process is completed, take it out for cleaning and drying.

The advantages of the present invention are:

1. Cover a layer of paraffin or dry film on the surface deposited with silicon nitride anti-reflection film, use a high-frequency laser to groove the surface of the paraffin to form a grid line pattern, or use pattern transfer technology to make the front grid line pattern on the film The patterns are transferred to the dry film. The width of the grid lines made by these two methods can reach about 20 microns, which is far lower than the grid line width of 40 microns produced by the screen printing technology. The present invention reduces the width of the fine grid lines. , reduce the shading area of the front, increase the current, and then improve the efficiency of the battery.

2. Use a metal copper with low cost and abundant reserves in the earth as a technology to replace the traditional grid line precious metal silver to achieve the purpose of reducing costs.

Description of drawings

The present invention will be further described in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is a schematic cross-sectional view of a semi-finished product deposited with a silicon nitride anti-reflection film;

Fig. 2 is the schematic sectional view of the sample covered with protective film;

Fig. 3 is a schematic cross-sectional view after displaying the front grid pattern on the protective film;

FIG. 4 is a schematic cross-sectional view of the front gate line pattern obtained after removing the silicon nitride film in the non-protected area;

Figure 5 is a schematic cross-sectional view after depositing activation points on the substrate;

Fig. 6 is the cross-sectional schematic diagram after depositing nickel;

Figure 7 is a schematic cross-sectional view after depositing copper;

Figure 8 is a schematic cross-sectional view after removing the protective film;

FIG. 9 is a schematic cross-sectional view after depositing an anti-oxidation protective layer.

Reference signs: A is a silicon nitride antireflection film; B is a silicon substrate; C is an aluminum back field; D is a back electrode; E is a protective film; F is a gate line on the protective film; G is silicon nitride after etching H is the palladium activation point; J is the nickel protective layer; K is the conductive copper layer; L is the anti-oxidation protective layer.

detailed description

In order for those skilled in the art to better understand the patent solution of the present invention, and to make the above-mentioned purpose, features, and advantages of the present invention more obvious and understandable, the following will be further described in detail in conjunction with examples.

Example 1:

A method for reducing the cost of crystalline silicon solar cells and improving efficiency, comprising the following steps:

As shown in Figure 1, a silicon nitride film with an anti-reflection effect is deposited on the front of the crystalline silicon solar cell to be processed, and an aluminum back field and a back electrode are printed on the back;

(1) Cover the protective film:

Spray black paraffin wax at 70°C on the surface of the silicon nitride film by thermal spraying to form the structure shown in Figure 2, and use a high-frequency laser to make grooves on the paraffin surface to form the structural pattern shown in Figure 3. In this embodiment, the diameter of the laser beam 20um, the groove pattern is the required front grid line pattern, and the width of the groove can be adjusted by the diameter of the laser beam;

(2) Prepare the grid pattern on the protective film:

The front of the battery is exposed to hydrofluoric acid etching solution with a volume concentration of 10-30%, and the silicon nitride film at the groove is removed to expose the silicon substrate under the film, and the front grid line pattern is obtained. After the process is completed, it is taken out and cleaned, forming Figure 4 The structural graph shown;

(3) Preparation of conductive grid lines:

Contact the front of the product obtained in the previous step with the palladium chloride activation solution at room temperature to form a series of activation points on the surface of the bare silicon substrate. Use hydrochloric acid and hydrofluoric acid to control the pH value of the activation solution at 2~3, and the activation time 20~60s to form Figure 5. At room temperature, the front side contacts the nickel plating solution, deposits a layer of nickel barrier layer on the substrate, uses hydrochloric acid to control the pH value of the nickel plating solution at 3.5~4.5, the time is 120~180s, and the thickness is 2~4um, forming Figure 6, under the guidance of electricity, the front side contacts the copper plating solution at room temperature, forming a conductive copper layer on the barrier layer, using sulfuric acid to control the pH value of the copper plating solution at 3~4, and the time is 20~ 30min, the thickness is 20~30um, after the process is completed, take it out and clean it, forming Figure 7;

(4) Remove the protective film:

Use chloroform to remove the protective film, take it out and clean it after the process is completed, and form Figure 8;

(5) Deposition of anti-oxidation protective layer:

At room temperature, the front of the battery is exposed to the nickel plating solution, and an oxidation protective layer is deposited on the surface of the conductive copper layer for 60-100s with a thickness of 1-2um or a silver layer is deposited as a protective layer under the guidance of light and electricity. It takes 50~80s and the thickness is 0.5~1.5um. After the process is completed, it is taken out, cleaned and dried, forming Figure 9.

Example 2:

A method for reducing the cost of crystalline silicon solar cells and improving efficiency, comprising the following steps:

As shown in Figure 1, a silicon nitride film with an anti-reflection effect is deposited on the front of the crystalline silicon solar cell to be processed, and an aluminum back field and a back electrode are printed on the back;

(1) Cover the protective film:

Apply a layer of dry film on the surface of the deposited silicon nitride anti-reflection film using a roller lamination process. The lamination temperature is 120°C and the speed is 3.5~4m/min to form Figure 2, and put in ultraviolet rays or shorter wavelengths. In the exposure machine, the laminated film face is facing the light source, and the pattern on the film that has made the front grid line pattern is transferred to the dry film by pattern transfer technology, forming Figure 3;

Among them, the dry film is the AP3810 dry film purchased at Guangzhou Changxing Dry Film Co., Ltd.;

(2) Prepare the grid pattern on the protective film:

When developing, use 30 ℃, Na ₂ CO ₃ solution with a mass fraction of 0.5~2% is sprayed on the surface of the exposed battery. After washing, a dry film with a clear grid line circuit pattern structure is formed on the surface of the battery. The line width is 23um. After the process is completed, take it out and clean it, forming Figure 4;

(3) Preparation of conductive grid lines:

Contact the front of the product obtained in the previous step with the palladium chloride activation solution at room temperature to form a series of activation points on the surface of the bare silicon substrate. Use hydrochloric acid and hydrofluoric acid to control the pH value of the activation solution at 2~3, and the activation time 20~60s to form Figure 5. At room temperature, the front side contacts the nickel plating solution, deposits a layer of nickel barrier layer on the substrate, uses hydrochloric acid to control the pH value of the nickel plating solution at 3.5~4.5, the time is 120~180s, and the thickness is 2~4um, forming Figure 6, under the guidance of electricity, the front side contacts the copper plating solution at room temperature, forming a conductive copper layer on the barrier layer, using sulfuric acid to control the pH value of the copper plating solution at 3~4, and the time is 20~ 30min, the thickness is 20~30um, after the process is completed, take it out and clean it, forming Figure 7;

(4) Remove the protective film:

Remove the protective film with the film remover, take it out and clean it after the process is completed, and form Figure 8;

Among them, the film removal solution is the AP38 series film removal solution purchased at Guangzhou Changxing Dry Film Co., Ltd.;

(5) Deposition of anti-oxidation protective layer:

Contact the nickel plating solution frontally at room temperature, and deposit an oxidation protection layer on the surface of the conductive copper layer for 60-100s with a thickness of 1-2um or deposit a silver layer as a protective layer under the guidance of light and electricity for 50~80s, the thickness is 0.5~1.5um, after the process is completed, it is taken out, cleaned and dried, forming Figure 9.

Comparative example:

Method for making crystalline silicon solar cells by traditional screen printing technology:

Texturing/cleaning→diffusion→etching/post-cleaning→PECVD coating→back electrode printing→back electric field printing→front electrode printing→high temperature sintering→test sorting.

Comparative Results:

It can be seen from the results in the above table that compared with the general traditional screen printing technology, the solar cell produced by a method of reducing the cost of crystalline silicon solar cells and improving the efficiency of the present invention not only reduces the production cost, but also improves the cell efficiency to a certain extent. .

Claims (4)

1. a reduction crystal silicon solar batteries cost puies forward high efficiency method, it is characterised in that: comprise the following steps:

(1) covered with protective film; (2) on protecting film, grid line figure is prepared; (3) preparation conduction grid line; (4) protecting film is removed; (5) deposition oxidation resistant protective layer.

2. a reduction crystal silicon solar batteries cost puies forward high efficiency method, it is characterised in that: comprise the following steps:

At the silicon nitride film needing crystal silicon solar batteries front to be processed deposition to have antireflective effect, back up has aluminum back surface field and back electrode;

(1) covered with protective film:

The surface heat having silicon nitride anti-reflecting film in deposition covers layer protecting film, the requirement according to front gate line figure, obtains front gate line figure on protecting film;

(2) on protecting film, grid line figure is prepared:

The region of unprotect film protection is corroded, the silicon nitride anti-reflecting film in this region is removed, the Si matrix making this region is exposed out, obtain front gate line circuitous pattern, wherein, protecting film has corrosion resistant component, can stop corrosive liquid in the process of corroding silicon nitride, protects the silicon nitride film under protected film overlay area not to be corroded;

(3) preparation conduction grid line:

The Palladous chloride. activation solution of the front face room temperature of product that will obtain in back, a series of activation point is formed at exposed Si matrix surface, hydrochloric acid and Fluohydric acid. is used to control 2 ~ 3 by the pH value of activation solution, activationary time is 20 ~ 60s, front face nickel-plating liquid under room temperature, on one layer of nickel barrier layer of substrate deposit, hydrochloric acid is used to control 3.5 ~ 4.5 by the pH value of nickel-plating liquid, time is 120 ~ 180s, thickness is 2 ~ 4um, under the guiding of electricity, front face copper plating bath under room temperature, form conductive copper layer over the barrier layer, sulphuric acid is used to control 3 ~ 4 by the pH value of copper plating bath, time is 20 ~ 30min, thickness is 20 ~ 30um,

(4) protecting film is removed:

Striping liquid is used to be removed by protecting film;

(5) deposition oxidation resistant protective layer:

Front face nickel-plating liquid under room temperature, deposits one layer of oxide protective layer on conductive copper layer surface, and the time is 60 ~ 100s, and thickness is 1 ~ 2um or deposits one layer of silver layer as protective layer under light with the guiding of electricity, and the time is 50 ~ 80s, and thickness is 0.5 ~ 1.5um.

3. a kind of crystal silicon solar batteries cost that reduces as claimed in claim 1 puies forward high efficiency method, it is characterised in that: comprise the following steps:

At the silicon nitride film needing crystal silicon solar batteries front to be processed deposition to have antireflective effect, back up has aluminum back surface field and back electrode;

(1) covered with protective film:

By the thermal spraying mode black paraffin silicon nitride film surface spraying 70 DEG C, using HF laser to slot in paraffin surface, Grooving patterns is the front gate line figure of needs, and the width of fluting can be regulated by the diameter of laser beam;

(2) on protecting film, grid line figure is prepared:

Battery front side contacting volume concentration is the Fluohydric acid. corrosive liquid of 10 ~ 30%, is removed by the silicon nitride film at fluting place, exposes the silicon substrate under film, obtains front gate line figure, and technique is taken out after completing and cleaned;

(3) preparation conduction grid line:

The Palladous chloride. activation solution of the front face room temperature of product that will obtain in back, a series of activation point is formed on exposed silicon substrate surface, hydrochloric acid and Fluohydric acid. is used to control 2 ~ 3 by the pH value of activation solution, activationary time is 20 ~ 60s, front face nickel-plating liquid under room temperature, on one layer of nickel barrier layer of substrate deposit, hydrochloric acid is used to control 3.5 ~ 4.5 by the pH value of nickel-plating liquid, time is 120 ~ 180s, thickness is 2 ~ 4um, under the guiding of electricity, front face copper plating bath under room temperature, form conductive copper layer over the barrier layer, sulphuric acid is used to control 3 ~ 4 by the pH value of copper plating bath, time is 20 ~ 30min, thickness is 20 ~ 30um, technique is taken out after completing and is cleaned,

(4) protecting film is removed:

Using chloroform to be removed by protecting film, technique is taken out after completing and is cleaned;

(5) deposition oxidation resistant protective layer:

Battery front side contact nickel-plating liquid under room temperature, deposits one layer of oxide protective layer on conductive copper layer surface, and the time is 60 ~ 100s; thickness is 1 ~ 2um or deposits one layer of silver layer as protective layer under light with the guiding of electricity; time is 50 ~ 80s, and thickness is 0.5 ~ 1.5um, and technique takes out cleaning, drying after completing.

4. a kind of crystal silicon solar batteries cost that reduces as claimed in claim 1 puies forward high efficiency method, it is characterised in that: comprise the following steps:

At the silicon nitride film needing crystal silicon solar batteries front to be processed deposition to have antireflective effect, back up has aluminum back surface field and back electrode;

(1) covered with protective film:

The surface of silicon nitride anti-reflecting film is had to use roller bearing press mold technique to attach one layer of dry film in deposition, press mold temperature is 120 DEG C, speed is 3.5 ~ 4m/min, put in ultraviolet or shorter wavelengths of exposure machine, pattern on the film making front gate line figure just to light source, is transferred on dry film by press mold face by Graphic transitions technology;

Wherein dry film is the AP3810 dry film bought in Changxing, Guangzhou dry film company limited;

(2) on protecting film, grid line figure is prepared:

During development, using 30 DEG C, mass fraction is the Na of 0.5 ~ 2%₂CO₃Spray solution battery surface after exposure, after washing, battery surface is the formation of the dry film with grid line circuitous pattern structure clearly, and technique is taken out after completing and cleaned;

(3) preparation conduction grid line:

The Palladous chloride. activation solution of the front face room temperature of product that will obtain in back, a series of activation point is formed on exposed silicon substrate surface, hydrochloric acid and Fluohydric acid. is used to control 2 ~ 3 by the pH value of activation solution, activationary time is 20 ~ 60s, front face nickel-plating liquid under room temperature, on one layer of nickel barrier layer of substrate deposit, hydrochloric acid is used to control 3.5 ~ 4.5 by the pH value of nickel-plating liquid, time is 120 ~ 180s, thickness is 2 ~ 4um, under the guiding of electricity, front face copper plating bath under room temperature, form conductive copper layer over the barrier layer, sulphuric acid is used to control 3 ~ 4 by the pH value of copper plating bath, time is 20 ~ 30min, thickness is 20 ~ 30um, technique is taken out after completing and is cleaned,

(4) protecting film is removed:

Using striping liquid to be removed by protecting film, technique is taken out after completing and is cleaned;

Wherein striping liquid is the AP38 series striping liquid bought in Changxing, Guangzhou dry film company limited;

(5) deposition oxidation resistant protective layer:

Front face nickel-plating liquid under room temperature, deposits one layer of oxide protective layer on conductive copper layer surface, and the time is 60 ~ 100s; thickness is 1 ~ 2um or deposits one layer of silver layer as protective layer under light with the guiding of electricity; time is 50 ~ 80s, and thickness is 0.5 ~ 1.5um, and technique takes out cleaning, drying after completing.