CN103794660A - Solar cell and manufacturing method thereof - Google Patents

Abstract

The invention provides a solar cell and a manufacturing method thereof. The method comprises the following steps: providing a solar cell substrate; forming a patterned mask layer exposing a part of the solar cell substrate on the solar cell substrate; forming a front electrode on the part of the solar cell substrate exposed by the patterned mask layer; forming a covering layer covering the front electrode; removing the patterned mask layer; and forming a back electrode on the solar cell substrate, wherein the front electrode and the back electrode are respectively formed on two opposite surfaces of the solar cell substrate. The front electrode is formed by forming a seed layer on the exposed part of the solar cell substrate, and then forming a copper layer on the seed layer.

Description

Solar cell and manufacturing method thereof

technical field

The present invention relates to a photoelectric element and its manufacturing method, and in particular to a solar cell and its manufacturing method.

Background technique

Due to the shortage of petrochemical energy, people's awareness of the importance of environmental protection has increased. Therefore, in recent years, people have been actively researching and developing technologies related to alternative energy and renewable energy, hoping to reduce the current human dependence on petrochemical energy and the impact on the environment when using petrochemical energy. the impact. Among the many alternative energy and renewable energy technologies, solar cells have attracted the most attention. The main reason is that solar cells can directly convert solar energy into electrical energy, and no substances such as carbon dioxide or nitrides will be produced during the power generation process, so it will not cause environmental pollution.

In the general solar cell manufacturing process, silver paste is usually coated on the substrate by means of screen printing and then subjected to high-temperature curing treatment to form electrodes. However, a large amount of silver colloid is often consumed in the process of screen printing. Since silver has a high price, the above-mentioned method increases the production cost of the solar cell. In addition, in order to improve the efficiency of solar cells, the silver electrodes formed in the above manner must have finer dimensions. However, during the high temperature curing process, the thin silver electrodes tend to be disconnected or discontinuous. In addition, the silver electrode formed by screen printing usually has a porous structure, which leads to an increase in resistance, thereby affecting the efficiency of the solar cell.

Contents of the invention

The invention provides a solar cell and a manufacturing method thereof.

The invention provides a solar cell with better efficiency and lower production cost.

The invention provides a method for manufacturing a solar cell, which can manufacture a solar cell with better efficiency and lower production cost.

The invention provides a solar cell, which includes a solar cell substrate, a front electrode, a covering layer and a back electrode. The front electrode and the back electrode are respectively arranged on two opposite surfaces of the solar cell substrate. The front electrode includes a seed layer and a copper layer. The seed layer is configured on the solar battery substrate. The copper layer is disposed on the seed layer. The covering layer covers the front electrodes.

According to the solar cell described in the embodiment of the present invention, the material of the seed layer is, for example, metal or metal silicide.

According to the solar cell described in the embodiment of the present invention, the aforementioned metal is, for example, silver, nickel, titanium, palladium or cobalt.

According to the solar cell described in the embodiment of the present invention, the metal silicide mentioned above is, for example, nickel silicide, titanium silicide or cobalt silicide.

According to the solar cell described in the embodiment of the present invention, the thickness of the above-mentioned seed layer is, for example, between 0.05 um and 10 um.

According to the solar cell described in the embodiment of the present invention, the thickness of the copper layer is, for example, between 1 um and 10 um.

According to the solar cell described in the embodiment of the present invention, the material of the above-mentioned covering layer is, for example, nickel, silver or tin.

According to the solar cell described in the embodiment of the present invention, the material of the above-mentioned back electrode is, for example, silver, copper, nickel, aluminum, titanium or chromium.

According to the solar cell described in the embodiment of the present invention, the structure of the above-mentioned back electrode is, for example, the same as that of the front electrode.

The present invention further provides a method for manufacturing a solar cell, which includes the following steps: providing a solar cell substrate; forming a patterned mask layer on the solar cell substrate; and exposing a part of the solar cell substrate by the patterned mask layer. Forming a front electrode on a portion of the solar cell substrate exposed by the patterned mask layer; forming a cover layer covering the front electrode; removing the patterned mask layer; and forming a back electrode on the solar cell substrate, wherein the front electrode and The back electrodes are respectively formed on two opposite surfaces of the solar cell substrate. The method for forming the front electrode is to form a seed layer on the part of the solar cell substrate exposed by the patterned mask layer. Then, a copper layer is formed on the seed layer.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the material of the above-mentioned seed layer is, for example, metal or metal silicide.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the aforementioned metal is, for example, silver, nickel, titanium, palladium or cobalt.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the above-mentioned metal silicide is, for example, nickel silicide, titanium silicide or cobalt silicide.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the thickness of the above-mentioned seed layer is, for example, between 0.05 um and 10 um.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the above-mentioned seed layer is formed by, for example, electroplating, electroless plating, physical vapor deposition or chemical vapor deposition.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the above copper layer is formed by, for example, electroplating, electroless plating, physical vapor deposition or chemical vapor deposition.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the thickness of the above-mentioned copper layer is, for example, between 1 um and 10 um.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the above-mentioned covering layer is formed by, for example, electroplating, electroless plating, physical vapor deposition or chemical vapor deposition.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the above step of removing the patterned mask layer is, for example, performed after the step of forming the covering layer.

According to the solar cell manufacturing method described in the embodiment of the present invention, the above-mentioned step of removing the patterned mask layer is performed between the step of forming the seed layer and the step of forming the copper layer.

According to the manufacturing method of the solar cell described in the embodiment of the present invention, the method for forming the above-mentioned back electrode is, for example, the same as the method for forming the front electrode.

Based on the above, before forming the electrodes in the present invention, the patterned mask layer is used to define the area where the electrodes will be formed, and then the electrodes are formed in this area. Therefore, compared with the method of coating the electrode material by screen printing, the electrode formed by the present invention can have a thinner width to increase the efficiency of the solar cell, and does not need to be used for curing the electrode material after forming the electrode. heat treatment. In addition, the electrode of the present invention has a copper layer, so the resistance of the electrode can be effectively reduced to improve the efficiency of the solar cell and reduce the production cost of the solar cell.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.

Description of drawings

1A to 1D are schematic cross-sectional views of the manufacturing process of a solar cell according to a first embodiment of the present invention;

2A to 2D are cross-sectional schematic diagrams showing a manufacturing process of a solar cell according to a second embodiment of the present invention.

Explanation of reference signs:

10, 20: solar cells;

100, 200: solar cell substrate;

102, 202: silicon substrate;

102a, 202a: front;

102b, 202b: back;

104: emitter;

106: anti-reflection layer;

108: patterned mask layer;

110: seed layer;

112: copper layer;

114: front electrode;

116, 120: covering layer;

118: back electrode;

204: the first amorphous layer;

206: a first transparent conductive oxide layer;

208: the second amorphous layer;

210: second transparent conductive oxide layer.

Detailed ways

FIG. 1A to FIG. 1D are cross-sectional schematic diagrams showing a manufacturing process of a solar cell according to a first embodiment of the present invention. First, referring to FIG. 1A , a solar cell substrate 100 is provided. In this embodiment, the solar cell substrate 100 includes a silicon substrate 102 and an emitter 104 . The silicon substrate 102 has a front side 102a and a back side 102b. The emitter 104 is disposed on the front surface 102a. In addition, an anti-reflection layer 106 may also be formed on the solar cell substrate 100 , which is located on the emitter 104 . The methods for forming the emitter 104 and the anti-reflection layer 106 are well known to those skilled in the art, and will not be further described here. Additionally, the silicon substrate 102 may have a textured surface (not shown), as is well known to those skilled in the art.

Then, referring to FIG. 1B , a patterned mask layer 108 is formed on the solar cell substrate 100 . The method for forming the patterned mask layer 108 is, for example, to form a mask material layer first, and then pattern the mask material layer by etching or laser cutting. In this embodiment, since the anti-reflection layer 106 is formed on the solar cell substrate 100 , the patterned mask layer 108 is formed on the anti-reflection layer 106 . Next, using the patterned mask layer 108 as a mask, the anti-reflection layer 106 exposed by the patterned mask layer 108 is removed to expose part of the solar cell substrate 100 (ie, part of the emitter 104 is exposed). In the embodiment without forming the anti-reflection layer 106, the patterned mask layer 108 is directly formed on the emitter 104, and there is no above-mentioned step of removing the anti-reflection layer 106 exposed by the patterned mask layer 108. .

Next, referring to FIG. 1C , a seed layer 110 is formed on the emitter 104 exposed by the patterned mask layer 108 . The seed layer 110 is used as a seed layer for subsequent formation of the copper layer. The material of the seed layer 110 is, for example, metal or metal silicide. The aforementioned metals are, for example, silver, nickel, titanium, palladium or cobalt, and the aforementioned metal silicides are, for example, nickel silicide, titanium silicide, or cobalt silicide. The thickness of the seed layer 110 is, for example, between 0.05 um and 10 um. In addition, the seed layer 110 can be a single layer or a multi-layer structure. In this embodiment, a single layer is taken as an example. The formation method of the seed layer 110 is, for example, electroplating, electroless plating (or called electroless plating), physical vapor deposition or chemical vapor deposition. In particular, when the material of the seed layer 110 is metal silicide, its formation method may also be to form a metal material layer on the emitter 104 exposed by the patterned mask layer 108, and then perform a tempering process. , making the metal material layer react with the underlying silicon material to form a metal silicide layer. Afterwards, the patterned mask layer 108 is removed.

After that, referring to FIG. 1D , a copper layer 112 is formed on the seed layer 110 . The copper layer 112 is formed by, for example, electroplating, electroless plating, physical vapor deposition or chemical vapor deposition. The thickness of the copper layer 112 is, for example, between 1 um and 10 um. In this embodiment, the copper layer 112 and the seed layer 110 constitute the front electrode 114 in the solar cell. In addition, the copper layer 112 is the main part of the front electrode 110, so that the front electrode 110 can have lower resistance, that is, better conductivity, and thus can effectively improve the efficiency of the solar cell. In addition, since copper has a lower price (compared to silver), the front electrode 114 with the copper layer 110 as the main part also reduces the production cost of the solar cell. Furthermore, before forming the front electrode 114, the patterned mask layer is used to define the area where the front electrode 114 will be formed. Therefore, compared with the method of applying electrode materials by screen printing, the formed front electrode 114 can have The thinner width increases the efficiency of the solar cell, and does not require high temperature treatment for curing the electrode material after forming the front electrode 114 .

Please continue to refer to FIG. 1D , forming a cover layer 116 covering the front electrode 114 . The material of the cover layer 116 is, for example, nickel, silver or tin. The forming method of the covering layer 116 is, for example, electroplating, electroless plating, physical vapor deposition or chemical vapor deposition. The covering layer 116 is used to prevent the copper layer 112 from being oxidized due to contact with the external environment. In addition, during the process of connecting a plurality of solar cells to form a solar cell module, the covering layer 116 can increase the adhesion between the front electrode 114 and the bus bar used to connect the plurality of front electrodes 114 . Then, a back electrode 118 is formed on the back surface 102 b of the silicon substrate 102 to complete the fabrication of the solar cell 10 . The back electrode 118 may have a back electrode structure well known to those skilled in the art. Alternatively, the back electrode may have the same structure and a similar formation method as the front electrode 114 . For example, a patterned mask layer, a seed layer and a copper layer may be sequentially formed on the back surface 102b to form the back electrode. After forming the back electrode, a cover layer covering the back electrode is formed.

In particular, in this embodiment, the step of removing the patterned mask layer 108 is performed between the step of forming the seed layer 110 and the step of forming the copper layer 112 . However, the present invention is not limited thereto. In other embodiments, the patterned mask layer 108 may also be removed after the covering layer 116 is formed.

In addition, in this embodiment, the front electrode 114 is formed first, and then the back electrode 118 is formed. However, the present invention is not limited thereto. According to actual needs, the back electrode 118 can also be formed first, and then the front electrode 114 can be formed.

2A to 2D are cross-sectional schematic diagrams showing a manufacturing process of a solar cell according to a second embodiment of the present invention. In this embodiment, the same elements as those of the first embodiment will be denoted by the same reference numerals. First, referring to FIG. 2A , a solar cell substrate 200 is provided. In this embodiment, the solar cell substrate 200 includes a silicon substrate 202, a first amorphous layer (amorphous layer) 204, a first transparent conductive oxide layer 206, a second amorphous layer 208 and a second transparent conductive oxide layer 210 . The silicon substrate 202 has a front side 202a and a back side 202b. The first amorphous layer 204 is disposed on the front surface 202a. The first transparent conductive oxide layer 206 is disposed on the first amorphous layer 204 . The second amorphous layer 208 is disposed on the back surface 202b. The second transparent conductive oxide layer 210 is disposed on the second amorphous layer 208 . The methods for forming the first amorphous layer 204 , the first transparent conductive oxide layer 206 , the second amorphous layer 208 and the second transparent conductive oxide layer 210 are well known to those skilled in the art and will not be further described herein. Additionally, silicon substrate 202 may have a textured surface (not shown), as is well known to those skilled in the art.

Then, referring to FIG. 2B , a patterned mask layer 108 is formed on the first transparent conductive oxide layer 206 and the second transparent conductive oxide layer 210 respectively.

Next, referring to FIG. 2C , a seed layer 110 is formed on the first transparent conductive oxide layer 206 and the second transparent conductive oxide layer 210 exposed by the patterned mask layer 108 . The seed layer 110 is used as a seed layer for subsequent formation of the copper layer. In addition, the seed layer 110 can be a single layer or a multi-layer structure. In this embodiment, a single layer is taken as an example.

After that, referring to FIG. 2D , a copper layer 112 is formed on the seed layer 110 . In this embodiment, the copper layer 112 and the seed layer 110 adjacent to the front surface 202a form the front electrode 114 in the solar cell, and the copper layer 112 and the seed layer 110 adjacent to the back surface 202b form the back electrode 118 in the solar cell. Since the copper layer 112 is the main part of the front electrode 110 and the back electrode 118 , the front electrode 110 and the back electrode 118 can have lower resistance, that is, have better conductivity, thus effectively improving the efficiency of the solar cell. In addition, since copper has a lower price (compared with silver), the front electrode 114 and the back electrode 118 with the copper layer 110 as the main part also reduce the production cost of the solar cell. Moreover, before forming the front electrode 114 and the back electrode 118, the area where the front electrode 114 and the back electrode 118 will be formed is defined by a patterned mask layer, so compared with the method of coating electrode materials by screen printing, The formed front electrode 114 and back electrode 118 can have a thinner width to increase the efficiency of the solar cell, and no high temperature treatment for curing the electrode material is required after the formation of the front electrode 114 and the back electrode 118 .

Please continue to refer to FIG. 2D , forming the covering layer 116 covering the front electrode 114 and the covering layer 120 covering the back electrode 118 to complete the fabrication of the solar cell 20 . The material, formation method and function of the covering layer 120 are the same as those of the covering layer 116 , and will not be further described here.

In this embodiment, the back electrode 118 and the front electrode 114 have the same structure and formation method, and both are formed in the same process steps. However, the present invention is not limited thereto. In other embodiments, the back electrode 118 may also have a back electrode structure known to those skilled in the art. In addition, according to actual needs, the front electrode 114 can also be formed first, and then the back electrode 118 ; or the back electrode 118 can be formed first, and then the front electrode 114 can be formed.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (21)

1. A solar cell, characterized in that, comprising: Solar cell substrate; The front electrode is configured on the solar cell substrate, and the front electrode includes: a seed layer configured on the solar cell substrate; and a copper layer configured on the seed layer; a cover layer covering the front electrode; and The back electrode is arranged on the solar cell substrate, wherein the front electrode and the back electrode are respectively arranged on two opposite surfaces of the solar cell substrate. 2. The solar cell according to claim 1, wherein the material of the seed layer comprises metal or metal silicide. 3. The solar cell of claim 2, wherein the metal comprises silver, nickel, titanium, palladium or cobalt. 4. The solar cell according to claim 2, wherein the metal silicide comprises nickel silicide, titanium silicide or cobalt silicide. 5 . The solar cell according to claim 1 , wherein the thickness of the seed layer is between 0.05 um and 10 um. 6 . The solar cell according to claim 1 , wherein the thickness of the copper layer is between 1 um and 10 um. 7. The solar cell according to claim 1, wherein the material of the covering layer comprises nickel, silver or tin. 8. The solar cell according to claim 1, wherein the material of the back electrode comprises silver, copper, nickel, aluminum, titanium or chromium. 9. The solar cell according to claim 1, wherein the structure of the back electrode is the same as that of the front electrode. 10. A method for manufacturing a solar cell, comprising: Provide solar cell substrates; forming a patterned mask layer on the solar cell substrate, the patterned mask layer exposing part of the solar cell substrate; Forming a front electrode on the part of the solar cell substrate exposed by the patterned mask layer, the method for forming the front electrode includes: forming a seed layer on the portion of the solar cell substrate exposed by the patterned mask layer; and forming a copper layer on the seed layer; forming a cover layer covering the front electrode; removing the patterned mask layer; and A back electrode is formed on the solar cell substrate, wherein the front electrode and the back electrode are respectively formed on two opposite surfaces of the solar cell substrate. 11. The method for manufacturing a solar cell according to claim 10, wherein the material of the seed layer comprises metal or metal silicide. 12. The method for manufacturing a solar cell according to claim 11, wherein the metal comprises silver, nickel, palladium, titanium or cobalt. 13. The method for manufacturing a solar cell according to claim 11, wherein the metal silicide comprises nickel silicide, titanium silicide or cobalt silicide. 14 . The method for manufacturing a solar cell according to claim 10 , wherein the thickness of the seed layer is between 0.05 um and 10 um. 15. The method for manufacturing a solar cell according to claim 10, wherein the method for forming the seed layer comprises electroplating, electroless plating, physical vapor deposition or chemical vapor deposition. 16 . The method for manufacturing a solar cell according to claim 10 , wherein the method for forming the copper layer comprises electroplating, electroless plating, physical vapor deposition or chemical vapor deposition. 17 . The method for manufacturing a solar cell according to claim 10 , wherein the thickness of the copper layer is between 1 um and 10 um. 18 . The method for manufacturing a solar cell according to claim 10 , wherein the method for forming the covering layer includes electroplating, electroless plating, physical vapor deposition or chemical vapor deposition. 19. The method of manufacturing a solar cell according to claim 10, wherein the step of removing the patterned mask layer is performed after the step of forming the covering layer. 20 . The method of manufacturing a solar cell according to claim 10 , wherein the step of removing the patterned mask layer is performed between the step of forming the seed layer and the step of forming the copper layer. 21 . 21 . The method for fabricating a solar cell according to claim 10 , wherein the method for forming the back electrode is the same as the method for forming the front electrode.

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