KR101209074B1 - Solar cell and method for manufacturing the same - Google Patents

Abstract

A solar cell according to an aspect of the present invention has a substrate of a first conductivity type, a second conductivity type opposite to the first conductivity type, and is connected to an emitter portion and an emitter portion to form a pn junction with the substrate, and two layers A plurality of first electrodes having a multilayer structure configured as described above, at least one first collector connected to the plurality of first electrodes, having a single layer structure, and a second electrode connected to the substrate; Include. This improves the efficiency of the solar cell and reduces the manufacturing cost.

Description

SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to a solar cell and a method of manufacturing the same.

A general solar cell includes a substrate and an emitter region made of semiconductors of different conductive types, such as p-type and n-type, and electrodes connected to the substrate and the emitter portion, respectively. At this time, p-n junction is formed in the interface of a board | substrate and an emitter part.

When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductor, and the generated electron-hole pairs are separated into electrons and holes charged by the photovoltaic effect, respectively, and the electrons and holes are n-type. Move toward the semiconductor and the p-type semiconductor, for example toward the emitter portion and the substrate, respectively, and are collected by electrodes connected to the substrate and the emitter portion, connecting the electrodes with wires to obtain power.

The technical problem to be achieved by the present invention is to reduce the manufacturing cost of the solar cell.

Another technical problem to be achieved by the present invention is to improve the efficiency of the solar cell.

A solar cell according to an aspect of the present invention has a substrate of a first conductivity type, a second conductivity type opposite to the first conductivity type, and is connected to an emitter portion and an emitter portion to form a pn junction with the substrate, and two layers A plurality of first electrodes having a multilayer structure configured as described above, at least one first collector connected to the plurality of first electrodes, having a single layer structure, and a second electrode connected to the substrate; Include.

The plurality of first electrodes may include a first electrode layer and a second electrode layer positioned on the first electrode layer, respectively, and the at least one first current collector may be formed of a material different from that of the first electrode layer.

At least one first current collector may be made of the same material as the second electrode layer.

Here, the first electrode layer contains silver (Ag), and the second electrode layer and the first current collector are nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium ( In), titanium (Ti), and combinations thereof.

Alternatively, the first electrode and the first current collector may contain silver (Ag), and the first electrode may be disposed on the first electrode layer and the first electrode layer, and may have a second electrode layer having a different content of the first electrode layer and silver (Ag). The first current collector may have substantially the same content as the second electrode layer and silver (Ag).

In this case, the content of silver (Ag) of the first electrode layer may be greater than the content of silver (Ag) of the second electrode layer and the first current collector.

The height of the first electrode layer may be about 15 μm to 30 μm.

The second electrode layer may have a height of about 10 μm to 35 μm.

The width of the first electrode may be about 30 μm to 80 μm.

According to another aspect of the present invention, there is provided a method of manufacturing an electrode of a solar cell, the method comprising: forming a first electrode layer pattern portion formed in parallel in a first direction by printing a first paste on a first region of a semiconductor substrate; The second paste is printed on the first region of the semiconductor substrate on which the first electrode layer pattern portion is formed, the second electrode layer pattern portion formed directly on the first electrode layer pattern portion, and the first current collector formed in the second direction perpendicular to the first direction. Simultaneously forming a pattern; And forming a second electrode pattern portion in a second region electrically separated from the first region of the semiconductor substrate.

The first paste and the second paste may be made of the same material.

At this time, the first paste and the second paste contain silver (Ag), the content of silver (Ag) of the first paste and the second paste is substantially the same, or the content of silver (Ag) of the first paste is It may be higher than the content of silver (Ag) of the second paste.

Alternatively, the first paste and the second paste may be made of different materials.

The first paste contains silver (Ag), the second paste is nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti) And at least one selected from the group consisting of a combination thereof.

The method may further include forming a second current collector pattern in the second region of the semiconductor substrate.

In the forming of the second electrode pattern portion and the second current collector portion pattern, a pattern substantially the same as the second paste may be screen printed to form a pattern.

According to this characteristic, since it has a two-layer structure which consists of each 1st electrode-electrode 1st electrode layer, and the 2nd electrode layer located on it, it has a thickness higher than the 1st electrode of 1 layer structure. Therefore, the series resistance of the first electrode is reduced, thereby improving the charge transfer efficiency from the emitter portion to the plurality of first electrodes, thereby improving the efficiency of the solar cell. In addition, since the first electrode layer contains silver (Ag), the contact resistance between the emitter portion and the plurality of first electrode layers is lowered, and the efficiency of charge transfer from the emitter portion to the first electrode layer is improved, so that the efficiency of the solar cell is further improved. In addition, since the second electrode layer and the first current collector are formed using a conductive material which is cheaper than the conductive material forming the first electrode layer, the silver (Ag) paste may be reduced in consumption and production cost may be reduced.

1 is a partial perspective view of a solar cell according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the solar cell shown in FIG. 1 taken along line II-II.
3A to 3E are cross-sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.
4A and 4B illustrate a front electrode pattern printed on a substrate using a screen printing method according to one embodiment of the present invention. It is a figure which shows the formed front electrode part pattern, and FIG. 4 (b) is a figure which shows the front electrode part pattern formed by secondary printing.
FIG. 5 is a diagram illustrating a front electrode pattern formed after primary printing using a screen printing method according to an exemplary embodiment of the present invention.
6 is a partial perspective view of a solar cell according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. Also, when a part is formed as "whole" on the other part, it means not only that it is formed on the entire surface (or the front surface) of the other part but also not on the edge part.

Next, a solar cell and a manufacturing method thereof according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

First, a solar cell according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a partial perspective view of a solar cell according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the solar cell shown in FIG.

As shown in FIGS. 1 and 2, the solar cell 1 includes a substrate 110, a plurality of emitters 120 and a plurality of emitters 120 positioned on the light receiving surface of the substrate 110 to which light is incident. At least one first collector 142, first electrode 141, and first collector positioned on the emitter portion 120 in a direction crossing the first electrode 141 and the plurality of first electrodes 141. An anti-reflection film 130 is disposed on the emitter unit 120 where all of the parts 142 are not disposed, and a second electrode 151 is disposed on the opposite side of the light receiving surface and connected to the substrate 110.

The substrate 110 is a semiconductor substrate made of silicon of a first conductivity type, for example, a p-type conductivity type. In this case, the silicon may be monocrystalline silicon, polycrystalline silicon, or amorphous silicon. When the substrate 110 has a p-type conductivity type, it contains impurities of trivalent elements such as boron (B), gallium (Ga), indium (In), and the like.

In alternative embodiments, the substrate 110 may have a textured surface. When the surface of the substrate 110 is formed as a texturing surface, the light reflectance at the light receiving surface of the substrate 110 is reduced, and incident and reflection operations are performed at the texturing surface, so that light is trapped inside the solar cell, thereby increasing light absorption. do. Therefore, the efficiency of the solar cell 1 is improved. In addition, the reflection loss of light incident on the substrate 110 is reduced, so that the amount of light incident on the substrate 110 is further increased.

The emitter portion 120 is a region doped with an impurity having a second conductivity type, for example, an n-type conductivity type, which is opposite to the conductivity type of the substrate 110. To form a junction.

When the emitter unit 120 has an n-type conductivity type, the emitter unit 120 may be doped with impurities of a pentavalent element such as phosphorus (P), arsenic (As), antimony (Sb), etc. on the substrate 110. Can be formed.

Accordingly, when electrons in the substrate 110 receive energy by light incident on the substrate 110, electrons are excited to generate electrons and holes, and the electrons move toward the n-type semiconductor and the holes move toward the p-type semiconductor. do. Therefore, when the substrate 110 is p-type and the emitter portion 120 is n-type, holes move toward the substrate 110 and electrons move toward the emitter portion 120.

Unlike the present embodiment, the substrate 110 may be of an n-type conductivity type, or may be made of a semiconductor material other than silicon. When the substrate 110 has an n-type conductivity type, the substrate 110 may contain impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb).

Since the emitter part 120 forms a p-n junction with the substrate 110, when the substrate 110 has an n-type conductivity type, the emitter part 120 has a p-type conductivity type. In this case, the separated electrons move toward the substrate 110 and the separated holes move toward the emitter part 120. When the emitter section 120 has a p-type conductivity type, the emitter section 120 is formed by doping an impurity of a trivalent element such as boron (B), gallium (Ga), indium (In) .

The anti-reflection film 130 disposed on the emitter portion 120 of the substrate 110 may be formed of silicon nitride (SiNx), silicon oxide (SiOx), or the like. The anti-reflection film 130 reduces the reflectivity of light incident on the solar cell 1 and increases the selectivity of a specific wavelength region to increase the efficiency of the solar cell 1.

In FIG. 1 and FIG. 2, the anti-reflection film 130 is formed of a single film, but may be formed of a multilayer film such as a double film or a triple film, and the anti-reflection film 130 may be omitted as necessary.

Each of the plurality of first electrodes 141 is positioned on the first electrode layer 141a and the first electrode layer 141a made of a conductive material connected to the emitter unit 120, and is formed of a different conductive material from the first electrode layer 141a. The second electrode layer 141b is provided. In this case, the planar shape of the first electrode layer 141a and the second electrode layer 141b disposed thereon are substantially the same.

Accordingly, charges (eg, electrons) moved toward the emitter unit 120 are mainly collected by the plurality of first electrode layers 141a, and at least some of the collected charges are connected to the plurality of second electrode layers 141a. It moves to 2 electrode layers 141b.

In the present embodiment, the first electrode layer 141a contains silver (Ag) having good conductivity, and the second electrode layer 141b includes nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), At least one selected from the group consisting of zinc (Zn), indium (In), titanium (Ti), gold (Au), and combinations thereof is a main component.

Therefore, the contact resistance between the emitter portion 120 and the plurality of first electrode layers 141a of the substrate 110 is lowered, so that the charge transfer efficiency from the emitter portion 120 to the first electrode layer 141a is improved.

In addition, since each first electrode 141 according to the present exemplary embodiment has a two-layer structure including a first electrode layer 141a and a second electrode layer 141b positioned thereon, the first electrode 141 has a thickness higher than that of the first electrode having a single layer structure. Has Therefore, the series resistance of the solar cell 1 is reduced, thereby improving the charge transfer efficiency from the emitter portion 120 to the plurality of first electrodes 141, thereby reducing the current loss.

Unlike the present embodiment in which the first electrode layer 141a is separated from the first current collector 142 region, as shown in FIG. 6, the first electrode layer 141a is located in the first current collector 142 region. It can be formed without being separated from each other.

In the solar cell 1 according to the present embodiment, the first electrode 141 may have a line width W1 of 30 μm to 100 μm. In addition, the thickness T1 of the first electrode layer 141a may be about 15 μm to 30 μm, and the thickness T2 of the second electrode layer 141b may be about 40 μm to 50 μm.

Here, when the line width W1 of the first electrode 141 is smaller than about 30 μm, disconnection of the first electrode 141 may occur.

In addition, when the line width W1 of the first electrode 141 exceeds about 100 μm, the light receiving area may be reduced, which may lower the efficiency of the solar cell 1.

The at least one first current collector 142 positioned on the emitter unit 120 is called a bus bar and extends in a direction crossing the plurality of first electrodes 141.

As shown in FIGS. 1 and 2, the first current collector 142 is connected to the first and second electrode layers 141a and 141b.

The first current collector 142 is made of a different material from the first electrode layer 141a, and is partially connected to the plurality of first electrode layers 141a through the side surface of the first current collector 142, and the first electrode layer. It is made of the same material as the second electrode layer 141b positioned on 141a. In this case, the thickness of the first current collector 142 illustrated in FIGS. 1 and 2 is substantially the same as the thickness of the first electrode 141, but the thickness of the first current collector 142 and the first electrode 141 are the same. The thickness of may be formed differently. When the thickness is different, a portion where the first electrode 141 and the first current collector 142 meet may be inclined.

As described above, the first electrode 141 has a double film structure composed of the first electrode layer 141a and the second electrode layer 141b, and the first current collector 142 has the same material as the second electrode layer 141b. Since the film has a single film structure, the thickness of the second electrode layer 141b of the first electrode 141 is thinner than that of the first bus bar 142.

However, in an alternative embodiment, the thickness of the first electrode 141 and the first current collector 142 may be different from each other, in which case the thickness of the second electrode layer 141b is the first bus bar 142. It may be thicker or equal to the thickness of.

Although the first electrode layers 141a of the plurality of first electrodes 141 are spaced apart from each other and extend in a direction crossing the first current collector 142, the first electrodes 141 and the plurality of first electrodes 141 are directly on the emitter unit 120. Since the first current collectors 142 extending in the crossing direction are positioned, the plurality of first electrode layers 141a are not positioned on the emitter unit 120 where the first current collectors 142 are located.

As such, since the first current collector 142 is connected to some of the plurality of first electrodes 141 and the emitter unit 120, charges transferred from the emitter unit 120 and the plurality of first electrodes 141, for example, For example, the former is output to an external device. In this case, electric charges delivered to the first current collector 142 may be transmitted through the first electrode layer 141a as well as the second electrode layer 141b. As described above, since the second electrode layer 141b and the first current collector 142 are made of a conductive material that is cheaper than silver (Ag), the manufacturing cost of the solar cell 1 is reduced. .

Alternatively, as described above, as illustrated in FIG. 6, the first electrode layer 141a may be formed to be connected to the first current collector 142 without being separated. In this case, unlike the present exemplary embodiment, the plurality of first electrode layers 141a may be positioned on the emitter unit 120 where the first current collector 142 is located. In other words, a portion of the first current collector 142 located at a portion where the first current collector 142 and the emitter unit 120 contact each other, that is, the first current collector disposed on an extension line of the first electrode layer 141a. Some regions are made of silver (Ag), which is the same material as the first electrode layer 141a, and the remaining regions of the first current collector 142 are nickel (Ni), copper (Cu), aluminum (Al), At least one selected from the group consisting of tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au), and combinations thereof.

In this case, since a part of the first current collector 142 of the portion in contact with the emitter unit 120 is formed of a highly conductive material, the contact resistance between the silicon substrate 110 and the first current collector 142 is lowered. The loss of current moving from the first electrode 141 to the first current collector 142 is reduced, thereby improving the photoelectric conversion characteristics.

On the other hand, the first electrode 141 according to another embodiment of the present invention is the same conductive material forming the main components of the first electrode layer 141a, the second electrode layer 141b and the first current collector 142.

In this case, the content of the conductive material constituting the main components of the first electrode layer 141a, the second electrode layer 141b, and the first current collector 142 may all be the same. Alternatively, the first electrode layer 141a The content of the conductive material and the content of the conductive material of the second electrode layer 141b and the first current collector 142 may be different.

For example, the content of silver (Ag) of the second electrode layer 141b and the first current collector 142 may be greater than that of the silver (Ag) of the first electrode layer 141a. For example, the content of silver (Ag) in the first electrode layer 141a is about 80 to 90 wt%, and the content of silver (Ag) in the second electrode layer 141b and the first current collector 142 is about 70% by weight. To 75 wt%.

The solar cell 1 further includes a back surface field (BSF) 171 formed between the second electrode 151 and the substrate 110. The back surface field part 171 is a region in which impurities of the same conductivity type as the substrate 110 are doped at a higher concentration than the substrate 110, for example, a p + region. The back field 171 serves as a potential barrier for the substrate 110. Therefore, since the electrons and holes are recombined and extinct at the rear side of the substrate 110, the efficiency of the solar cell 1 is improved.

The second electrode 151 located at the rear side of the substrate 110 collects charges, for example, holes, moving toward the substrate 110.

The second electrode 151 is made of at least one conductive material. The conductive material may be at least one selected from the group consisting of Ni, Cu, Ag, Al, Sn, Zn, In, Ti, Au, And combinations thereof, but may be made of other conductive materials.

The solar cell 1 according to the present exemplary embodiment further includes at least one second current collector 152 positioned on the rear surface of the substrate 110 and connected to the rear electrode 151.

In the present embodiment, the at least one second current collector 152 is directly positioned on the rear side of the substrate and connected to the adjacent rear electrode 151. That is, it is formed so as not to overlap with the second electrode 151. However, the present invention is not limited thereto, and may be partially overlapped with the second electrode 151, and may be connected to the lower rear electrode 151 under the rear electrode 151 positioned on the rear of the substrate 110. have.

In the present embodiment, the second current collector 152 is substantially positioned at a position corresponding to the first current collector 142 about the substrate 110, and thus, in the same direction as the first current collector 142. 1 is a perspective view of a portion of the solar cell, but only one second current collector 152 is illustrated, but is not limited thereto and may have a plurality of second current collectors 152. .

Similar to the first current collector 142, the second current collector 152 is connected to the rear electrode 151 to collect charges transferred from the second electrode 151, for example, holes, and then, a conductive tape or the like. Output to an external device through.

The conductive material constituting the second current collector 152 includes nickel (Ni), copper (Cu), silver (Ag), aluminum (Al), tin (Sn), zinc (Zn), indium (In), and titanium ( At least one selected from the group consisting of Ti), gold (Au), and combinations thereof, but may be made of another conductive metal material.

Next, a method of manufacturing the solar cell 1 according to an embodiment of the present invention will be described with reference to FIGS. 3A to 3E and FIGS. 4A and 4B.

3A to 3E are cross-sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

4A and 4B illustrate a front electrode pattern printed on a substrate using a screen printing method according to one embodiment of the present invention. It is a figure which shows the formed front electrode part pattern, and FIG. 4 (b) is a figure which shows the front electrode part pattern formed by secondary printing.

First, as shown in (a) of FIG. 3, a material containing impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb), etc., for example, in the p-type substrate 110 , POCl ₃ or H ₃ PO ₄ is heat-treated at high temperature to diffuse impurities of the pentavalent element to the substrate 110 to n-type emitter portion 120 on the entire surface of the substrate 110, that is, the front, back and side To form.

Unlike the present embodiment, when the conductivity type of the substrate 110 is n-type, a material containing an impurity of trivalent element, for example, B ₂ H ₆ is heat-treated at a high temperature to form a p-type on the entire surface of the substrate 110. Emitter portion of can be formed. Next, an etching process is performed to etch an oxide containing phosphorous (PSG) or an oxide containing boron (boron silicate glass, BSG) generated as n-type impurities or p-type impurities are diffused into the substrate 110. Remove through.

Next, as shown in FIG. 3B, an anti-reflection film 130 made of silicon nitride (SiNx) is formed on the entire surface of the substrate 110 using various film formation methods such as plasma enhanced chemical vapor deposition (PECVD). Form.

The refractive index of the anti-reflection film 130 may have a refractive index between the refractive index 1 of air and the refractive index (eg, about 3.5) of the silicon substrate 110, for example, a refractive index of about 1.9 to 2.3. Thus, since the refractive index change from the air to the substrate 110 is sequentially performed, the anti-reflection effect of the anti-reflection film 130 is improved.

Next, as shown in FIG. 3C, the paste containing silver (Ag) is printed on the first region of the semiconductor substrate by screen printing, followed by drying at about 120 ° C. to 200 ° C. to form the first front electrode. The subpattern 40a is formed. In this case, the shape of the first front electrode portion pattern 40a extends in parallel in the first direction as shown in FIG. 4A, and is formed with the width of the first current collector portion empty. In the present embodiment, the shape of the first front electrode pattern 40a is the same as the shape of the first electrode layer pattern 41a. Here, the first electrode 141 (front electrode) is formed in the first region of the semiconductor substrate.

When the first front electrode portion pattern 40a is formed of silver (Ag) paste, contact resistance between the silicon substrate 110 and the first current collector 142 is reduced to improve photoelectric conversion characteristics.

Alternatively, as shown in FIG. 5, it is also possible to primary print the first front electrode portion pattern 40a so as to continue without breaking in the first current collector region. In this case, since a part of the first current collector 142 is formed of a material having high conductivity, the contact resistance between the silicon substrate 110 and the first current collector 142 is lowered, and the first electrode 141 is connected to the first current collector 142. The loss of current moving to the whole 142 is reduced, so that the photoelectric conversion characteristics are improved.

Then, as shown in FIG. 3D, the first front electrode portion pattern 40a prints a paste containing a material different from the first front electrode portion pattern 40a, that is, aluminum (Al). Printed on the first region of the semiconductor substrate, that is, on the first front electrode portion pattern 40a and on the anti-reflection film 130 where the first front electrode portion pattern 40a is not located, and then dried at about 120 ° C to 200 ° C. The second front electrode part pattern 40b is formed.

The paste for the second front electrode pattern 40b includes nickel (Ni), copper (Cu), silver (Ag), tin (Sn), zinc (Zn), indium (In), and titanium (Ti) instead of aluminum (Al). ), Gold (Au), and combinations thereof.

In this case, a portion of the second front electrode portion pattern 40b, that is, a portion of the first current collector portion pattern portion 42, directly positioned on the anti-reflection film 130 may extend in a direction crossing the first front electrode portion pattern 40a. have. As such, the second front electrode pattern 40b printed on the substrate 110 is as shown in FIG. 4B.

As described above, the second front electrode portion pattern 40b includes a first portion positioned on the first front electrode portion pattern 40a and a second portion directly positioned on the anti-reflection film 130.

The first portion of the second front electrode portion pattern 40b forms the first electrode pattern portion 41 together with the first front electrode portion pattern 40a positioned below the second front electrode portion pattern 40b, and the second front electrode portion pattern 40b. The second portion of) forms the first current collector pattern 42. Thereby, the front electrode part pattern 40 provided with the 1st electrode pattern part 41 and the 1st collector part pattern 42 is completed.

 In FIG. 3D, the thickness of the first current collector pattern part 42 is substantially the same as the thickness of the first electrode pattern part 41, but may be different from each other.

Since the front electrode pattern 40 is printed twice, the first electrode 141 having a higher thickness than the one-time printing can be formed, and the second electrode layer is made of a conductive material that is cheaper than silver (Ag). Since the pattern portion 41b and the first current collector portion pattern portion 42 are formed, the amount of the silver (Ag) paste is reduced and the production cost is reduced.

However, in an alternative embodiment, the conductive materials that make up the main component of the paste forming the first electrode layer pattern portion 41a and the second electrode layer pattern portion 41b are formed identically.

In this case, the content of the conductive material constituting the main component of each paste forming the first electrode pattern portion 40 may be the same, and the content and the content of the conductive material constituting the main component in the paste for the first electrode layer pattern portion 41a may be the same. In the paste for the second electrode layer pattern portion 41b and the first current collector portion pattern portion 42, the content of the conductive material as a main component, that is, the first front electrode portion pattern 40a and the second front electrode portion pattern 40b The content of the conductive material which is the main component of each paste may be different.

For example, when the content of the conductive material which is a main component of each paste of the first front electrode pattern 40a and the second front electrode pattern 40b is different from each other, the silver on the anti-reflection film 130 may have a total weight of silver ( Ag) A first paste having a relatively high content of powder is printed to form a first front electrode portion pattern 40a, and a second paste having a lower content of silver (Ag) powder relative to the total weight of the first paste is prepared. The second front electrode part pattern 40b may be formed by printing on the front electrode part pattern 40a and a portion of the exposed anti-reflection film 130. At this time, the first paste is a silver (Ag) paste containing about 80 to 90% by weight of the silver powder, and the second paste is about 70 to 75% by weight of the silver powder. It may be a silver (Ag) paste containing.

Next, as shown in (e) of FIG. 3, a second region electrically separated from the first region on which the front electrode pattern 40 is printed by using the screen printing method, in this embodiment, the substrate 110. The back electrode paste containing aluminum (Al) is applied to the corresponding portion on the back side and dried to form the back electrode pattern portion 51. Here, the second electrode 151 (back electrode) is formed in the second region of the semiconductor substrate.

The paste for the back electrode is nickel (Ni), copper (Cu), silver (Ag), tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) and At least one selected from the group consisting of a combination thereof.

Next, using a screen printing method, a paste for a rear electrode current collector containing aluminum (Al) is applied to a second region, and in the present embodiment, a corresponding portion of the rear surface of the substrate 110, followed by drying, to form a rear electrode current collector pattern. (52, 2nd collector part pattern) is formed.

In the present exemplary embodiment, the at least one second current collector pattern 52 is directly positioned on the rear surface of the substrate and connected to the adjacent rear electrode pattern portion 51. That is, it is formed so as not to overlap with the second electrode pattern portion 51. However, the present invention is not limited thereto, and may be formed to partially overlap the rear electrode pattern portion 51, and may be disposed under the rear electrode pattern pattern 51 disposed on the rear surface of the substrate 110 to form a lower rear electrode pattern portion ( 51).

In the present embodiment, the second current collector pattern 52 is formed at a position corresponding to the first current collector pattern 42 substantially about the substrate 110. That is, although the first current collector pattern 42 extends in the same direction, the present invention is not limited thereto. Although only one second current collector pattern 52 is illustrated in FIG. 3E, the present invention is not limited thereto, and a plurality of second current collector patterns 52 may be formed.

The paste for the rear electrode collector is nickel (Ni), copper (Cu), silver (Ag), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti) instead of aluminum (Al). It may include at least one selected from the group consisting of gold (Au) and combinations thereof, or may be made of other conductive metal materials.

The order of forming the front electrode pattern 40 and the back electrode pattern 50 can be changed. In addition, in forming the back electrode part pattern 50, the order of forming the back electrode pattern part 51 and the back electrode current collector part 52 may be changed.

Thereafter, the substrate 110 including the front electrode part pattern 40 and the rear electrode pattern 50 is fired at a temperature of about 750 ° C. to about 800 ° C., thereby forming a plurality of first electrodes 141. At least one first current collector 142, a rear electrode 151, a rear electrode current collector 152, and a rear electric field unit 171 are formed.

That is, when the heat treatment is performed, the front electrode portion pattern 40 penetrates through the lower portion of the anti-reflection film 130 due to lead (Pb) contained in the glass frit of the front electrode portion pattern 40, thereby, The front electrode part 140 including a plurality of first electrodes 141 and at least one first current collecting part 142 in contact with the rotor part 120 is completed. In this case, the first electrode pattern part 41 of the front electrode part pattern 40 becomes a plurality of front electrodes, that is, the first electrode 141, and the first current collecting part pattern part 42 is at least one first. It becomes the collector 142.

In addition, the back electrode pattern part 51 and the back electrode current collector pattern 52 may be the second electrode 151 and the second current collector 152 respectively connected to the substrate 110 by a heat treatment process. Aluminum (Al), which is a content of the 151 and the second current collector 152, is diffused toward the substrate 110 in contact with the rear electrode 151, and is mainly disposed on the rear surface of the substrate 110 in contact with the rear electrode 151. The rear electric field unit 171 is formed. At this time, aluminum (A1) is diffused to extend beyond the emitter portion 120 positioned on the rear surface of the substrate 110 to form the rear electric field portion 171.

As described above, unlike the present embodiment, the second current collector 152 may be formed under the second electrode 151 to be connected to the lower portion of the second electrode 151.

Then, edge isolation is performed to remove at least a portion of the emitter portion 120 formed on the side or edge portion of the substrate 110 using a laser beam or the like (not shown). The solar cell 1 is completed by electrically separating the emitter portion 120 formed on the front surface and the emitter portion 120 formed on the rear surface of the substrate 110 (FIGS. 1 and 2).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

1: solar cell
40: front electrode portion pattern 40a: first front electrode portion pattern
40b: second front electrode pattern portion 41: front electrode pattern portion
41a: first electrode layer pattern portion 41b: second electrode layer pattern portion
42: first current collector portion pattern portion 50: rear electrode portion pattern
51: rear electrode pattern portion 52: rear electrode collector portion pattern
110: substrate 120 emitter part
130: antireflection film 140: first electrode portion, front electrode portion
141: first electrode and front electrode 141a: first electrode layer and first front electrode layer
141b: second electrode layer and second front electrode layer 142: first current collector and front electrode current collector
151: second electrode, rear electrode 152: second current collector
171: rear electric field

Claims (18)

A substrate of a first conductivity type,
An emitter portion having a second conductivity type opposite to the first conductivity type and forming a pn junction with the substrate,
A plurality of first electrodes connected to the emitter part and having a two-layer structure consisting of two layers of a first electrode layer positioned directly above the emitter part and a second electrode layer positioned on the first electrode layer;
At least one first current collector connected to the plurality of first electrodes and having a single layer structure, and
A second electrode connected to the substrate,
The at least one first current collector includes the same material as the second electrode layer,
The first electrode layer has a different composition from the second electrode layer and the first current collector.
delete delete In claim 1,
The first electrode layer is a solar cell containing silver (Ag). In claim 1,
The second electrode layer and the first current collector are nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) and Solar cell comprising at least one selected from the group consisting of a combination thereof. In claim 1,
The first electrode layer, the second electrode layer and the first current collector contain silver (Ag),
The content of silver (Ag) of the first electrode layer and the second electrode layer is different from each other,
The solar cell of the first current collector and the second electrode layer have substantially the same content. The method of claim 6,
The content of silver (Ag) of the first electrode layer is larger than the content of silver (Ag) of the second electrode layer and the first current collector. The method according to any one of claims 4 to 6,
The first electrode layer is a solar cell having a height of 15㎛ 30㎛. The method according to any one of claims 4 to 6,
The second electrode layer is a solar cell having a height of 10㎛ to 35㎛. In claim 1,
The first electrode has a width of 30㎛ to 80㎛. Printing a first paste on a first region of the semiconductor substrate to form a first electrode layer pattern portion formed in parallel in a first direction;
The second electrode layer pattern portion and the first electrode formed on the first electrode layer pattern portion by printing a second paste having a composition different from the first paste in the first region of the semiconductor substrate on which the first electrode layer pattern portion is formed. Simultaneously forming a first current collector pattern formed in a second direction perpendicular to the direction; And
Forming a second electrode pattern portion in a second region electrically separated from the first region of the semiconductor substrate. 12. The method of claim 11,
The first paste and the second paste of the solar cell electrode manufacturing method of the same material. delete The method of claim 12,
The first paste and the second paste contain silver (Ag),
A method of manufacturing an electrode of a solar cell, wherein the content of silver (Ag) in the first paste is greater than the content of silver (Ag) in the second paste. In paragraph 11
And the first paste and the second paste are made of different materials. 16. The method of claim 15,
The first paste contains silver (Ag),
The second paste is at least one selected from the group consisting of nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti), and combinations thereof. Electrode manufacturing method of a solar cell comprising a. 12. The method of claim 11,
And forming a second current collector pattern in the second region of the semiconductor substrate. The method of claim 17,
The second electrode pattern portion and the second current collector pattern forming step
A method of manufacturing an electrode of a solar cell, wherein the paste is substantially printed with the same paste as the second paste to form a pattern.

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