CN111129176A

CN111129176A - Method for producing a solar cell and solar cell

Info

Publication number: CN111129176A
Application number: CN201911325248.4A
Authority: CN
Inventors: 石强; 林纲正; 陈刚
Original assignee: Zhejiang Aiko Solar Energy Technology Co Ltd; Guangdong Aiko Solar Energy Technology Co Ltd; Tianjin Aiko Solar Energy Technology Co Ltd
Current assignee: Zhejiang Aiko Solar Energy Technology Co Ltd; Guangdong Aiko Solar Energy Technology Co Ltd; Tianjin Aiko Solar Energy Technology Co Ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-05-08

Abstract

The present disclosure relates to a method for manufacturing a solar cell and a solar cell. A method for fabricating a solar cell as described herein includes forming a plurality of openings in a plated silicon substrate to expose portions of the silicon substrate. For example, the plurality of openings are formed in a uniformly distributed pattern and a distance between any two of the plurality of openings is not less than 200 micrometers. The method may further include forming an electrode on the plurality of portions. By implementing the embodiment of the present disclosure, aluminum voids may be generated in the process of manufacturing a solar cell, and the bending and aluminum diffusion effects of the solar cell may be reduced.

Description

Method for producing a solar cell and solar cell

Technical Field

The present disclosure relates to the field of semiconductors, and more particularly, to a method for manufacturing a solar cell and a solar cell.

Background

The solar cell has the characteristics of green economy, safety, convenience, high efficiency, environmental protection and the like, and can gradually replace petrochemical energy to become a main configuration of new energy in the future of the world. The flattening of solar cells is a goal that practitioners are constantly pursuing. The conversion efficiency of conventional PERC (passivated emitter and rear cell technology) cells is approaching the theoretical value, and it has become more difficult to improve the conversion efficiency and reduce the production cost technically. Increasing the size of the solar cell silicon wafer is another easy way to reduce the production cost. However, the size of the silicon wafer of the solar cell causes problems such as backside bending, aluminum diffusion, and even aluminum voids, which in turn affects the product quality and energy conversion efficiency of the solar cell. Therefore, it is required to develop a method of manufacturing a solar cell capable of solving the above problems.

Disclosure of Invention

According to an example embodiment of the present disclosure, a manufacturing scheme of a solar cell is provided.

In a first aspect of the present disclosure, a method for fabricating a solar cell is provided. The method includes forming a plurality of openings in a coated silicon substrate to expose portions of the silicon substrate. For example, the plurality of openings are formed in a uniformly distributed pattern and a distance between any two of the plurality of openings is not less than 200 micrometers. The method may further include forming an electrode on the plurality of portions.

In certain embodiments, forming the electrode on the plurality of portions comprises: screen printing the silicon substrate with a paste such that the paste fills the plurality of portions.

In certain embodiments, screen printing the silicon substrate with the paste such that the paste fills the plurality of portions comprises: screen printing the silicon substrate using an aluminum paste to form an aluminum layer on the silicon substrate, wherein the aluminum layer has a weight of 600 to 1100 mg and a thickness of 10 to 20 micrometers.

In certain embodiments, screen printing the silicon substrate using the aluminum paste comprises: screen printing the silicon substrate with the aluminum paste including an inhibitor to reduce a kirkendall diffusion effect of the aluminum paste with the silicon substrate.

In some embodiments, screen printing the silicon substrate using the paste comprises: the silicon substrate was screen printed using an aluminum back field screen having a thickness of 20 to 60 microns.

In some embodiments, forming the plurality of openings on the plated silicon substrate comprises: forming the plurality of openings with the spacing between two adjacent openings being 200-2000 microns on the coated silicon substrate.

In some embodiments, forming the plurality of openings on the plated silicon substrate comprises: forming the plurality of openings in a circular shape on the plated silicon substrate, wherein each opening of the plurality of openings has a diameter of 20 to 40 micrometers.

In some embodiments, forming the plurality of openings on the plated silicon substrate comprises: forming the plurality of openings in the square coated silicon substrate, wherein the silicon substrate has a side length between 125 mm-220 mm.

In a second aspect of the present disclosure, there is provided a solar cell manufactured according to the method set forth in the first aspect of the present disclosure.

It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of various embodiments of the present disclosure will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like or similar reference characters designate like or similar elements, and wherein:

FIG. 1A shows an open film shape and its composed array pattern for a conventional open film process;

FIG. 1B is a schematic cross-sectional view of an aluminum void created by a conventional electrode formation process;

fig. 2 shows a flow diagram of a process for manufacturing a solar cell according to an embodiment of the present disclosure;

FIG. 3A shows the open film shapes of the open film process and the array pattern of its composition according to an embodiment of the present disclosure;

FIG. 3B shows the open film shapes of the open film process and the array pattern of its composition according to an embodiment of the present disclosure;

figure 4A shows a cross-sectional schematic view of a resulting structure in a process for fabricating a solar cell, in accordance with an embodiment of the present disclosure;

figure 4B shows a cross-sectional schematic view of a resulting structure in a process for fabricating a solar cell, in accordance with an embodiment of the present disclosure; and

fig. 4C shows a schematic cross-sectional view of a structure resulting from a process for fabricating a solar cell, in accordance with an embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the disclosure are for illustration purposes only and are not intended to limit the scope of the disclosure.

In describing embodiments of the present disclosure, the terms "include" and its derivatives should be interpreted as being inclusive, i.e., "including but not limited to. The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first," "second," and the like may refer to different or the same object. Other explicit and implicit definitions are also possible below.

In the process of manufacturing a solar cell such as a PERC cell, it is generally necessary to coat the back surface of the semi-finished solar cell with a passivation film having a certain thickness. The conventional film opening process usually uses a laser to form a tight opening on the back surface of the film-coated solar cell for the subsequent formation of an electrode. Fig. 1A shows an open film shape and its constituent array pattern 100 for a conventional open film process. As shown in fig. 1A, the array pattern 100 includes a plurality of openings 120 therein, and the shape of the openings is circular. These circular openings 120 are formed in the back-plane of the solar cell, such as the silicon substrate 110.

The pattern formed by the openings 120 is a relatively compact linear structure due to the small size of the conventional solar cell. As shown in fig. 1A, the opening 120 may form four long dashed lines. It should be understood that the conventional array pattern formed by the openings 120 may also include a plurality of short dashed lines. However, as the size of the solar cell increases, the conventional opening pattern may cause the solar cell to bend during subsequent manufacturing and use, thereby causing the cell to crack and generating assembly soldering debris. In addition, the tighter opening pattern and the subsequent mishandling of the printed aluminum paste also create "aluminum voids".

FIG. 1B is a schematic cross-sectional view of an aluminum void created by a conventional electrode formation process. As shown in fig. 1B, the silicon substrate 130 is plated with the passivation film 110, and the passivation film 110 has therein an opening 120 formed via a laser film opening process. For the above reasons, when printing with aluminum paste, the aluminum paste 140 entering the opening 120 may not reach deep to the bottom of the opening 120, i.e., the aluminum paste 140 does not contact the silicon substrate 130, thereby forming the aluminum void 150. How to avoid the above defects in the manufacturing process of the solar cell is a main problem to be solved by the present disclosure.

To address this problem, the present disclosure provides a solution for manufacturing a solar cell. First, the openings formed in the opening process of the present disclosure have uniformly distributed patterns, and the distance between any two openings is not less than 200 micrometers. Since the openings formed by the opening film are arranged in a lattice, the curling of the back surface of the solar cell can be suppressed to the utmost. Further, by performing screen printing on the opened-film silicon substrate and setting the wet weight of the aluminum paste and the thickness of the aluminum layer formed by printing, the kirkendall diffusion effect (i.e., aluminum diffusion) between the aluminum paste and the silicon substrate and aluminum voids are avoided.

The method for manufacturing a solar cell silicon wafer will be described in detail below with reference to the accompanying drawings and a plurality of corresponding embodiments.

Fig. 2 shows a flow diagram of a process 200 for manufacturing a solar cell according to an embodiment of the present disclosure. A process 200 for fabricating a solar cell according to an embodiment of the present disclosure is now described in detail with reference to fig. 3A-3B and 4A-4C. For ease of understanding, specific data mentioned in the following description are exemplary and are not intended to limit the scope of the present disclosure.

At 210, a plurality of openings 120 may be formed in the coated silicon substrate 110 to expose portions of the silicon substrate 110. In some embodiments, the plurality of openings 120 are formed in a uniformly distributed pattern, and a distance between any two openings of the plurality of openings 120 is not less than 200 microns. As an example, as shown in fig. 3A, the plurality of openings 120 are formed in a square array on the silicon substrate 110, and the distance between each two openings in the longitudinal and lateral directions of the surface of the silicon substrate 110 is not less than 200 μm. Preferably, as shown in fig. 3B, the plurality of openings 120 are formed in a regular triangular array (or referred to as a honeycomb array) on the silicon substrate 110, and the distance between each two openings is not less than 200 μm. In this way, the openings are uniformly distributed and the distance is increased, so that the manufacturing requirement of a large-size solar cell silicon wafer can be met, and the curvature of the solar cell is reduced. For example, it is possible to reduce the bending from 2mm to 0.8mm, as determined experimentally.

In some embodiments, a plurality of openings 120 with a spacing of 200 to 2000 microns between two adjacent openings may be formed on the coated silicon substrate 110. In this way, a sufficient number of electrodes can be formed while minimizing the solar cell curvature.

In some embodiments, a plurality of openings 120 having a circular shape may be formed on the coated silicon substrate 110. By way of example, each opening of the plurality of openings 120 is 20 microns to 40 microns in diameter. Alternatively or additionally, the shape of the plurality of openings 120 may also be square, regular triangle, regular hexagon, or other polygon.

In some embodiments, a plurality of openings 120 may be formed in the coated square silicon substrate 110. In some embodiments, the silicon substrate 110 has a side length between 125 millimeters and 220 millimeters. In this way, the aperture arrangement described above can accommodate both smaller solar cells of 125 mm to 180 mm and larger solar cells of 180 mm to 220 mm.

It should be understood that the above-described opening process 210 may be implemented using a laser. Here, the frequency of the laser may be set to 10kH to 1500kH, the laser power of the laser may be set to 1W to 30W, and the engraving speed of the laser may be set to 5m/s to 50 m/s.

At 220, electrodes are formed on portions that may be exposed on the silicon substrate 110 via the plurality of openings 120. In some embodiments, forming the electrodes actually means screen-printing the silicon substrate 110 with paste so that the paste fills the plurality of portions.

Fig. 4A-4C respectively show cross-sectional schematic views of a plurality of structures resulting from a process 200 for fabricating a solar cell, in accordance with an embodiment of the present disclosure. As shown in fig. 4A, the silicon substrate 110 may include a silicon layer 410 and a plating layer 420. As described above in 210 of process 200, a plurality of openings 120 may be formed in the coated silicon substrate 110. That is, as shown in fig. 4B, the silicon substrate 110 may be opened using a technique such as laser to form a plurality of openings 120. Next, the silicon substrate 110 may be screen printed with a paste such that the paste fills the portions as described above at 220 of process 200. That is, as shown in fig. 4C, the paste 430 may be printed on the plating layer 420 of the opened silicon substrate 110. The paste 430 covers the entire coating layer 420 and extends downward through the opening 120 to contact the silicon layer 410.

In some embodiments, the silicon substrate 110 may be screen printed using an aluminum paste to form an aluminum layer on the silicon substrate 110. By way of example, the weight of the aluminum layer (which may be referred to herein as the wet weight) may be 600 mg to 1100 mg. Preferably, the weight of the aluminum layer on the silicon substrate 110 may be 900 mg. Further, as an example, the thickness of the aluminum layer may be 10 to 20 micrometers. By reducing the thickness of the aluminum layer, the solar cell curvature can be further minimized.

In some embodiments, the silicon substrate 110 may be screen printed with an aluminum paste containing an inhibitor to reduce the kirkendall diffusion effect of the aluminum paste with the silicon substrate 110. That is, during subsequent sintering or the like, a difference in diffusion rate between the aluminum paste and the silicon substrate 110 may occur due to a change in temperature, resulting in a possibility of aluminum diffusion. By using a suitable aluminum paste and limiting the thickness and wet weight of the aluminum layer, the likelihood of aluminum diffusion and aluminum voids is minimized. For example, aluminum diffusion can be limited to within 30 microns experimentally.

In some embodiments, the silicon substrate 110 may be screen printed using an aluminum back field screen having a thickness of 20 to 60 microns. The mesh number of the aluminum back field screen plate for screen printing can be set to be 280-480 meshes, the thickness of the screen can be set to be 15-40 um, and the thickness of the film can be set to be 5-20 um.

In this way, a manufacturing method suitable for a large-sized solar cell is obtained, so that the production cost of the solar cell can be reduced on the premise of ensuring the energy conversion efficiency. In addition, the curvature of the large-size solar cell is minimized due to the application of the uniformly arranged lattice film opening process. In addition, due to the optimized printing process, the generation of aluminum holes is basically avoided and the aluminum diffusion is reduced. Furthermore, the solar cell manufacturing scheme of the present disclosure is also applicable to smaller-sized solar cell manufacturing.

In summary, the features and advantages of the present disclosure have been illustrated in detail by a discussion of several embodiments above.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for manufacturing a solar cell comprising:

A plurality of openings are formed on the coated silicon substrate to expose portions of the silicon substrate, wherein the plurality of openings are formed in a uniformly distributed pattern and any two of the plurality of openings are opened the distance between them is not less than 200 microns; and

Electrodes are formed on the plurality of portions.

2. The method of claim 1, wherein forming the electrodes on the plurality of portions comprises:

The silicon substrate is screen printed with a paste such that the paste fills the portions.

3. The method of claim 2, wherein screen printing the silicon substrate using the paste such that the paste fills the plurality of portions comprises:

The silicon substrate is screen-printed using an aluminum paste to form an aluminum layer on the silicon substrate, wherein the aluminum layer has a weight of 600 mg to 1100 mg, and the aluminum layer has a thickness of 10 microns to 20 microns.

4. The method of claim 3, wherein screen printing the silicon substrate using the aluminum paste comprises:

The silicon substrate is screen printed using the aluminum paste containing an inhibitor to reduce Kirkendall diffusion effects of the aluminum paste and the silicon substrate.

5. The method of claim 3, wherein screen printing the silicon substrate with the paste comprises: screen printing the silicon substrate with an aluminum back field screen having a thickness of 20 to 60 microns screen printing.

6. The method of claim 1, wherein forming the plurality of openings on the plated silicon substrate comprises:

The plurality of openings with a spacing between two adjacent openings of 200 micrometers to 2000 micrometers are formed on the plated silicon substrate.

7. The method of claim 1, wherein forming the plurality of openings on the plated silicon substrate comprises:

The plurality of openings having a circular shape are formed on the plated silicon substrate, wherein each opening of the plurality of openings has a diameter of 20 to 40 microns.

8. The method of claim 1, wherein forming the plurality of openings on the plated silicon substrate comprises:

The plurality of openings are formed on a plated square of the silicon substrate, wherein the side length of the silicon substrate is between 125 mm and 220 mm.

9. A solar cell manufactured according to the method of any one of claims 1 to 8.