KR20140040347A - Solar cell and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a solar cell and a method for manufacturing same. A solar cell and a method for manufacturing same according to one embodiment of the present invention include a photoelectric conversion part; an electrode which is connected to the photoelectric conversion part; a ribbon which is electrically connected to the electrode and is formed on the electrode; and a plating layer. According to one embodiment of the present invention, the plating layer surrounds the electrode and the ribbon.

Description

SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to a solar cell and a method for manufacturing the same, and more particularly to a solar cell and a method for manufacturing the improved electrical connection structure.

With the recent depletion of existing energy sources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting attention as a next-generation battery that converts solar energy into electric energy.

Such solar cells form various layers, electrodes, etc. according to design, and neighboring solar cells are electrically connected to each other by a ribbon. At this time, if the connection characteristics of the electrode and the ribbon is not good, the resistance may be increased, the electrical characteristics may be degraded, and in severe cases, the cell may be broken. Accordingly, the characteristics of the solar cell may be lowered and productivity may be lowered.

The present invention aims to provide a solar cell having excellent characteristics and productivity and a manufacturing method thereof.

The solar cell according to the present embodiment includes a photoelectric conversion unit; An electrode connected to the photoelectric conversion unit; A ribbon formed on the electrode and electrically connected to the electrode; And a plating layer formed to surround the electrode and the ribbon.

The method of manufacturing a solar cell according to the present embodiment includes preparing a photoelectric conversion unit; Forming an electrode in the photoelectric conversion unit; Attaching a ribbon electrically connected to the electrode on the electrode; And forming a plating layer by plating to surround the electrode and the ribbon.

According to the present embodiment, by forming a plating layer surrounding both the first electrode and the ribbon, the contact uniformity between the first electrode and the ribbon may be improved, thereby improving the cell density and efficiency of the solar cell. In addition, the reflection of the plating layer may increase the light usage of the solar cell, thereby further improving the efficiency. In addition, since the plating layer improves electrical characteristics, the ribbon may be made of an inexpensive metal instead of an expensive metal, thereby further reducing manufacturing costs.

1 is an exploded perspective view of a solar cell module according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of the solar cell module of FIG. 1.
3 is a partial cross-sectional view illustrating a solar cell of the solar cell module of FIG. 1.
4 is a plan view schematically illustrating a front surface of a solar cell of the solar cell module of FIG. 1.
5 is a photograph after the ribbon is peeled off after the first electrode and the ribbon are attached by a conventional tabbing process.
6A to 6F are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.
7 is an enlarged cross-sectional view of a first electrode, a soldering layer, a ribbon, and a plating layer of a solar cell according to another embodiment of the present invention.
8 is an enlarged cross-sectional view of a first electrode, a ribbon, and a plating layer of a solar cell according to another embodiment of the present invention.
FIG. 9 is a partial plan view illustrating the first electrode of FIG. 8.
10 is an enlarged cross-sectional view of a first electrode, a ribbon, and a plating layer of a solar cell according to a modification of the present invention.
11 is an enlarged cross-sectional view of a first electrode, a ribbon, and a plating layer of a solar cell according to another modification of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it is needless to say that the present invention is not limited to these embodiments and can be modified into various forms.

In the drawings, the same reference numerals are used for the same or similar parts throughout the specification. In the drawings, the thickness, the width, and the like are enlarged or reduced in order to make the description more clear, and the thickness, width, etc. of the present invention are not limited to those shown in the drawings.

Wherever certain parts of the specification are referred to as "comprising ", the description does not exclude other parts and may include other parts, unless specifically stated otherwise. Also, when a portion of a layer, film, region, plate, or the like is referred to as being "on" another portion, it also includes the case where another portion is located in the middle as well as the other portion. When a portion of a layer, film, region, plate, or the like is referred to as being "directly on" another portion, it means that no other portion is located in the middle.

Hereinafter, with reference to the accompanying drawings will be described in more detail a solar cell and a method of manufacturing the same according to the present embodiment.

1 is an exploded perspective view of a solar cell module according to an embodiment of the present invention, Figure 2 is a schematic cross-sectional view of the solar cell module of FIG.

Referring to the drawings, the solar cell module 100 according to an embodiment of the present invention is the solar cell 150, the front substrate 110 and the rear surface of the solar cell 150 located on the front of the solar cell 150 It may include a back sheet 200 positioned on. In addition, the solar cell module 100 may include a first sealant 131 between the solar cell 150 and the front substrate 110 and a second sealant 132 between the solar cell 150 and the rear sheet 200. It may include.

At this time, the solar cell 150 is a photoelectric conversion unit for converting solar energy into electrical energy, an electrode electrically connected to the photoelectric conversion unit, and connected to the electrode and connected to the neighboring solar cell 150 or the outside A ribbon 142. Specific structures of the photoelectric conversion unit and the electrode will be described later in detail with reference to FIG. 3. The solar cell 150 may be electrically connected in series, in parallel, or in series or in parallel by the ribbon 142. Specifically, as shown in FIG. 2, the ribbon 142 may connect an electrode formed on one surface of the solar cell 150 and an electrode formed on the other surface of another neighboring solar cell 150. In this embodiment, the plating layer (reference numeral 40 of FIG. 3) is formed while surrounding the electrode and the ribbon 142 to further improve the characteristics of the solar cell 150, which will be described in more detail later with reference to FIG. 3. do.

The bus ribbon 145 alternately connects both ends of the ribbon 142 of the solar cell 150 in a row connected by the ribbon 142. The bus ribbons 145 may be arranged in the direction intersecting the ends of the solar cells 150 forming one row. The bus ribbon 145 is connected to a junction box (not shown) that collects electricity generated by the solar cell 150 and prevents electricity from flowing backward.

The first sealing material 131 may be located at the front surface of the solar cell 150, and the second sealing material 132 may be located at the rear surface of the solar cell 150. The first sealing member 131 and the second sealing member 132 are bonded by lamination to block moisture or oxygen that may adversely affect the solar cell 150, and each element of the solar cell 150 is chemically bonded. Do it.

The first sealing material 131 and the second sealing material 132 may be made of ethylene vinyl acetate copolymer resin (EVA), polyvinyl butyral, silicon resin, ester resin, olefin resin, or the like. However, the present invention is not limited thereto. Accordingly, the first and second sealing materials 131 and 132 may be formed by a method other than lamination using various other materials.

The front substrate 110 is positioned on the first sealing member 131 to transmit sunlight, and is preferably tempered glass in order to protect the solar cell 150 from an external impact or the like. Further, it is more preferable to use a low-iron-content tempered glass containing a small amount of iron in order to prevent the reflection of sunlight and increase the transmittance of sunlight.

The rear sheet 200 protects the solar cell 150 from the back surface of the solar cell 150, and functions as a waterproof, insulating, and ultraviolet shielding function. The backsheet 200 may be of the TPT (Tedlar / PET / Tedlar) type, but is not limited thereto. In addition, the rear sheet 200 may be made of a material having excellent reflectance so that sunlight incident from the front substrate 110 can be reflected and reused. However, the present invention is not limited thereto, and the rear sheet 200 may be formed of a transparent material from which solar light can enter, thereby realizing a double-sided solar cell module 100.

Hereinafter, a solar cell 150 according to an embodiment of the present invention will be described in more detail. 3 is a partial cross-sectional view showing a solar cell 150 according to an embodiment of the present invention, Figure 4 is a plan view schematically showing the front surface of the solar cell 150 according to an embodiment of the present invention. For reference, FIG. 3 is a cross-sectional view taken along line III-III of FIG. 4.

Referring to FIG. 3, the solar cell 150 according to the present embodiment includes a substrate having a conductivity type (hereinafter referred to as a “semiconductor substrate”) 10 and impurity layers 20 and 30 formed on the semiconductor substrate 10. And electrodes 24 and 34 electrically connected to the impurity layers 20 and 30. The impurity layers 20 and 30 may include an emitter layer 20 and a back front layer 30 and the electrodes 24 and 34 may include a first electrode 24 electrically connected to the emitter layer 20, And a second electrode 34 electrically connected to the rear front layer 30. A ribbon 142 is positioned on the electrodes 24 and 34, and a plating layer 40 is formed to surround the electrodes 24 and 34 and the ribbon 142 and fix them. In addition, the solar cell 150 may further include an anti-reflection film 22, a passivation film 32, and the like, which are insulating films.

At this time, the semiconductor substrate 10 and the impurity layers 20 and 30 constitute a photoelectric conversion unit for converting light into electricity. That is, in the present embodiment, the photoelectric conversion structure of the silicon semiconductor solar cell is applied using the semiconductor substrate 10 and the impurity layers 20 and 30. However, the present invention is not limited thereto, and various structures such as a compound semiconductor or a dye sensitized material can be used as the photoelectric conversion portion. The same is true of the embodiments to be described later.

Here, the semiconductor substrate 10 may include various semiconductor materials. For example, the semiconductor substrate 10 may include silicon including a second conductivity type impurity. As the silicon, single crystal silicon or polycrystalline silicon may be used, and the second conductivity type impurity may be n-type, for example. That is, the semiconductor substrate 10 may be formed of single crystal or polycrystalline silicon doped with a Group 5 element such as phosphorus (P), arsenic (As), bismuth (Bi), and antimony (Sb)

When the semiconductor substrate 10 having the n-type impurity is used, the emitter layer 20 having the p-type impurity is formed on the entire surface of the semiconductor substrate 10 to form a pn junction. When the pn junction is irradiated with light, electrons generated by the photoelectric effect move toward the rear surface of the semiconductor substrate 10, are collected by the second electrode 34, and the holes move toward the front surface of the semiconductor substrate 10 1 electrode 24, respectively. Thereby, electric energy is generated. Then, the hole having a slower moving speed than the electron moves to the front surface of the semiconductor substrate 10, not the rear surface, so that the conversion efficiency can be improved.

However, the present invention is not limited thereto, and it goes without saying that the semiconductor substrate 10 and the rear front layer 30 may have a p-type and the emitter layer 20 may have an n-type.

Although not shown in the figure, the front and / or rear surface of the semiconductor substrate 10 may be textured to have irregularities in the form of a pyramid or the like. When the surface roughness of the semiconductor substrate 10 is increased by forming concaves and convexes on the front surface of the semiconductor substrate 10 by such texturing, the reflectance of light incident through the front surface of the semiconductor substrate 10 can be reduced. Therefore, the amount of light reaching the pn junction formed at the interface between the semiconductor substrate 10 and the emitter layer 20 can be increased, thereby minimizing the optical loss.

An emitter layer 20 having a first conductivity type impurity may be formed on the front surface of the semiconductor substrate 10. [ In the present embodiment, the emitter layer 20 is a first conductivity type impurity, and a p-type impurity such as boron (B), aluminum (Al), gallium (Ga), or indium (In) as a Group III element can be used.

The antireflection film 22 and the first electrode 24 are formed on the semiconductor substrate 10 and more precisely on the emitter layer 20 formed on the semiconductor substrate 10.

The antireflection film 22 may be formed substantially entirely on the entire surface of the semiconductor substrate 10 except for the portion where the first electrode 24 is formed. The antireflection film 22 reduces the reflectivity of light incident on the front surface of the semiconductor substrate 10 and immobilizes defects existing in the surface or bulk of the emitter layer 20. [

By lowering the reflectance of light incident through the front surface of the semiconductor substrate 10, the amount of light reaching the pn junction formed at the interface between the semiconductor substrate 10 and the emitter layer 20 may be increased. Accordingly, the short circuit current Isc of the solar cell 150 may be increased. The open voltage Voc of the solar cell 150 can be increased by immobilizing defects present in the emitter layer 20 to remove recombination sites of the minority carriers. As described above, the open circuit voltage and the short circuit current of the solar cell 150 may be increased by the anti-reflection film 22 to improve the efficiency of the solar cell 150.

The anti-radiation film 22 may be formed of various materials. For example, the antireflection film 22 may be a single film selected from the group consisting of a silicon nitride film, a silicon nitride film including hydrogen, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, MgF ₂ , ZnS, TiO ₂ and CeO ₂ , Layer structure having a combination of at least two layers. However, the present invention is not limited thereto, and it goes without saying that the anti-reflection film 22 may include various materials. Further, a front passivation film (not shown) may be further provided between the semiconductor substrate 10 and the antireflection film 22 for passivation. Are also within the scope of the present invention.

The first electrode 24 is electrically connected to the emitter layer 20 through an opening formed in the antireflection film 22 or through the antireflection film 22. The first electrode 24 may be formed to have various shapes by various materials.

Referring to FIG. 4, as an example, the first electrode 24 may include a plurality of finger electrodes 24a having a first pitch P1 and arranged in parallel with each other. In addition, the first electrode 24 may include a bus bar electrode 24b formed in a direction crossing the finger electrodes 24a and connecting the finger electrodes 24a. Only one bus electrode 24b may be provided or a plurality of bus electrodes 24b may be provided with a second pitch P2 larger than the first pitch P1 as shown in FIG. At this time, the width W2 of the bus bar electrode 24b may be larger than the width W1 of the finger electrode 24a, but the present invention is not limited thereto and may have the same width. The shape of the first electrode 24 described above is merely an example, and the present invention is not limited thereto.

The finger electrode 24a and the bus bar electrode 24b both may be formed to penetrate through the antireflection film 22 (the passivation film 32 in the case of the second electrode 34, hereinafter the same) have. Alternatively, the finger electrode 24a may pass through the antireflection film 22 and the bus bar electrode 24b may be formed on the antireflection film 22.

Referring back to FIG. 3, a back surface field layer 30 including a second conductivity type impurity is formed on the back side of the semiconductor substrate 10 at a higher doping concentration than the semiconductor substrate 10. In the present embodiment, the rear front layer 30 may be an n-type impurity such as phosphorus (P), arsenic (As), bismuth (Bi), and antimony (Sb) which are Group 5 elements as the second conductive impurities.

In addition, a passivation film 32 and a second electrode 34 may be formed on the rear surface of the semiconductor substrate 10.

The passivation film 32 may be formed substantially on the entire rear surface of the semiconductor substrate 10 except for the portion where the second electrode 34 is formed. This passivation film 32 can pass the defects present on the back surface of the semiconductor substrate 10 to remove recombination sites of minority carriers. As a result, the open voltage of the solar cell 150 may be increased.

The passivation film 32 may be made of a transparent insulating material so that light can be transmitted. Therefore, light may be incident through the back surface of the semiconductor substrate 10 through the passivation film 32, thereby improving efficiency of the solar cell 150. For example, the passivation film 32 may be a single film selected from the group consisting of a silicon nitride film, a silicon nitride film including hydrogen, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, MgF ₂ , ZnS, TiO _2, and CeO ₂ , Layer structure having a combination of at least two layers. However, the present invention is not limited thereto, and it goes without saying that the passivation film 32 may include various materials.

The second electrode 34 is electrically connected to the rear front layer 30 through an opening formed in the passivation film 32 (i.e., through the passivation film 32). The second electrode 34 may be formed to have various shapes by various materials. For example, the width of the second electrode 34 may vary with the width and pitch of the first electrode 24, but the shape may be similar. Accordingly, the description of the first electrode 32 related to FIG. 4 may also be applied to the second electrode 34. However, the present invention is not limited thereto.

A ribbon 142 may be positioned on the electrodes 24 and 34 to be electrically connected to the electrodes 24 and 34 to connect the neighboring solar cells 145. In addition, the plating layer 40 may be formed to surround the electrodes 24 and 34 and the ribbon 142. For simplicity and clarity, hereinafter, the first electrode 24 and the ribbon 142 will be described in detail. The following description may be applied to the second electrode 34 and the ribbon 142 connected thereto.

The first electrode 24 may be formed by various methods using various materials. In one example, the first electrode 24 is formed on the anti-reflection film 22 (passivation film 32 in the case of the second electrode 34, hereinafter the same) containing a paste containing a metal, a binder, a glass frit and the like It may be formed by heat treatment. During heat treatment, a fire-throug phenomenon occurs in which the glass frit penetrates the anti-reflection film 22, so that the first electrode 24 is formed on the rear surface of the emitter layer 20 (in the case of the second electrode 34). The layer 30 may be formed in electrical connection (for example, in a contact state) to the layer 30. For example, the first electrode 24 may be formed by using a paste containing silver (Ag) which is excellent in electrical characteristics and may reduce light loss by reflection.

The ribbon 142 connects the first electrode 24 of one solar cell 150 and the second electrode 34 of another solar cell 150 adjacent thereto to electrically connect the neighboring solar cells 150. Connect. Accordingly, the ribbon 142 is formed to be electrically connected to the first electrode 24 (or the second electrode 34, hereinafter the same).

For example, the ribbon 142 may be connected to the first electrode 24 by a tabbing process using soldering. In order for the electrical connection with the first electrode 24 to have excellent characteristics, the ribbon 142 should have excellent soldering characteristics and electrical conductivity. In one example, the ribbon 142 may include the body portion 142a and the soldering portion 142b surrounding the ribbon 142 to improve both the above-described soldering properties and electrical conductivity.

At this time, the body portion 142a preferably includes a material having high electrical conductivity and low cost as a portion for substantially transmitting current. In one example, the first portion 142a may include copper (Cu), silver (Ag), or the like. In this case, copper and silver may be included together to reduce the material burden and have high electrical characteristics. However, the present invention is not limited thereto. In the present embodiment, since the plating layer 40 can sufficiently improve characteristics such as electrical conductivity, the first portion 142a may include only copper instead of silver. This will be described in more detail later.

The soldering part 142b may include a material that participates in soldering. For example, the soldering part 142b may include tin (Su) or lead (Pb). In this case, tin and lead may be included together to improve soldering properties. However, the present invention is not limited thereto. Therefore, in consideration of environmental pollution, the soldering part 142b may include only tin.

However, the present invention is not limited to the above description, and it is also possible that the ribbon 142 does not include the soldering portion 142b. This will be described later with reference to FIG. 7.

During soldering, a flux may be applied between the ribbon 142 and the first electrode 24 to improve soldering characteristics. The flux is intended to remove the oxide film that interferes with the soldering and is not necessarily included.

In the above-described embodiment, the ribbon 142 and the first electrode 24 are bonded to each other by a tabbing process using soldering, but the present invention is not limited thereto. Therefore, the conductive film (not shown) may be positioned between the first electrode 24 and the ribbon 142, and then the first electrode 24 and the ribbon 142 may be connected by thermal compression. In the conductive film (not shown), conductive particles formed of gold, silver, nickel, copper, etc. having excellent conductivity may be dispersed in a film formed of an epoxy resin, an acrylic resin, a polyimide resin, a polycarbonate resin, or the like. When the conductive film is pressed while applying heat, the conductive particles may be exposed to the outside of the film, and the first electrode 24 and the ribbon 142 may be electrically connected by the exposed conductive particles. As described above, when the plurality of solar cells 150 are connected and modularized by a conductive film (not shown), the process temperature may be lowered, and the warpage of the solar cells 150 may be prevented.

In addition, the plating layer 40 may be formed while surrounding the first electrode 24 and the ribbon 142. More specifically, the plating layer 40 is formed on the surface of the first electrode 24 and the ribbon 142 (more specifically, the top and side surfaces of the ribbon 142 and the side of the first electrode 24). It is formed while filling between the first electrode 24 and the ribbon 142. Accordingly, the adhesion characteristics of the first electrode 24 and the ribbon 142 may be improved and resistance may be reduced. Accordingly, it is possible to prevent cell breakage and to improve electrical characteristics.

In this case, the plating layer 40 may be made of a material having a lower resistance characteristic than the first electrode 24 or the ribbon 142, thereby improving electrical characteristics. In addition, the plating layer 40 may use a material having a higher reflectance than that of the first electrode 24 or the ribbon 142 so that light of the first electrode 24 may be easily reflected. The light reflected from the first electrode 24 may be totally reflected from the front substrate (reference numeral 110 of FIG. 1) to be directed toward the solar cell 150. As a result, the light usage of the solar cell 150 is increased to improve the short circuit current Isc, thereby improving the efficiency of the solar cell 150.

For example, the plating layer 40 may be, for example, a silver plating layer including silver (Ag). Then, the electrical characteristics and reflectivity of the silver may be improved to improve the contact characteristics and electrical characteristics of the first electrode 24 and the ribbon 142 and to reflect light to improve the efficiency of the solar cell 150. However, the present invention is not limited thereto, and the plating layer 40 may include various other metals. In one example, the plating layer 40 is nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) and their It may consist of a single layer or a plurality of layers comprising an alloy. For example, the plating layer 40 may include a first plating layer in which copper having a low material cost is plated, and a second plating layer in which silver is plated to prevent oxidation of copper and having excellent reflectance. The plating layer 40 may have various materials and various laminated structures.

The plating layer 40 may have a thickness of 0.01 ~ 3㎛. If the thickness of the plating layer 40 is less than 0.01 μm, it may be difficult to expect the effect of improving the characteristics by the plating layer 40. The characteristic improvement effect by the plating layer 40 may not be increased even if the thickness is increased by being saturated at a predetermined thickness. In consideration of this, the plating layer 40 may be formed to a thickness of 3 μm or less to prevent an unnecessary material cost increase.

The plating layer 40 may have a higher density than the first electrode 24 and may have a lower resistivity than the first electrode 24. This is because the first electrode 24 is formed by a printing method and the like, and has a relatively low density and relatively high resistance, whereas the plating layer 40 is formed by plating and has a relatively high density and relatively low resistance. For example, when both the plating layer 40 and the first electrode 24 are made of silver, when the pure specific resistance of silver is 1.00, the specific resistance of the plating layer 40 is about 1.05 to 1.30 and the specific resistance of the first electrode 24 is 3.00 ~ 4.00 level. The morphology characteristic of the scanning electron microscope (SEM) or the optical microscope shows whether the plating layer 40 is formed by plating.

However, the thickness, density, and resistance of the plating layer 40 may vary depending on the size of the solar cell 150, the material of the first electrode 24, the ribbon 142, and the like. Therefore, the thickness, density, resistance, and the like of the plating layer 40 are not limited to the above-described numerical values and may have various values.

As described above, according to the present exemplary embodiment, after the first electrode 24 and the ribbon 142 are connected to each other, a plating layer 40 covering all of them is formed to improve contact uniformity between the first electrode 24 and the ribbon 142. As a result, the solar cell 150 may be improved in density and efficiency, and cell breakage may be prevented. In addition, the light use of the solar cell 150 may be increased by reflection by the plating layer 40, thereby further improving efficiency. In addition, since the plating layer 40 improves electrical characteristics, the ribbon 142 may be made of an inexpensive metal instead of an expensive metal, thereby further reducing manufacturing costs.

On the other hand, conventionally, only the solder is connected between the first electrode and the ribbon. Accordingly, the electrical connection characteristics of the first electrode and the ribbon are greatly influenced by the soldering process. In general, the soldering process is difficult to be uniform throughout. Therefore, the first electrode and the ribbon are not uniformly connected at the portion where soldering does not sufficiently occur, so that the electrical connection characteristics of the first electrode and the ribbon are degraded. As a result, the problem of deterioration of the integrity and deterioration of efficiency may occur, and in severe cases, the cell may be broken.

As an example, the photograph after peeling the ribbon after attaching the first electrode and the ribbon by a conventional tabbing process is shown in FIG. 5. Referring to Figure 5, it can be seen that the contact by soldering is formed unevenly. For example, in this case, after soldering, the density decreased by 4% or more and the efficiency decreased by 1.4% or more. That is, in the related art, it can be seen that soldering between the first electrode and the ribbon does not occur uniformly, so that electrical characteristics and the like may be degraded.

Hereinafter, a method of manufacturing a solar cell according to an embodiment of the present invention will be described in detail with reference to FIGS. 6A to 6F. The detailed description will be omitted for the parts already described, and the parts not described in detail will be described in detail.

6A to 6F are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

First, as shown in FIG. 6A, a semiconductor substrate 10 having a second conductivity type impurity is prepared. At this time, although not shown in the drawing, the front surface and / or the rear surface of the semiconductor substrate 10 may have irregularities by texturing. Texturing can be either wet or dry texturing. The wet texturing can be performed by immersing the semiconductor substrate 10 in the texturing solution, and has a short process time. In dry texturing, the surface of the semiconductor substrate 10 is cut by using a diamond grill or a laser, so that irregularities can be formed uniformly, but the processing time is long and damage to the semiconductor substrate 10 may occur. Or texturing may be formed only on one of the front surface and the rear surface of the semiconductor substrate 10 by reactive ion etching (RIE) or the like. As described above, the semiconductor substrate 10 can be textured in various ways in the present invention.

Subsequently, as shown in FIG. 6B, the emitter layer 20 and the backside electric field layer 30, which are impurity layers, are formed on the semiconductor substrate 10. More detailed description is as follows. The emitter layer 20 and the back field layer 30 may be formed by a method such as a thermal diffusion method, an ion implantation method, or the like. However, the present invention is not limited thereto, and various modifications are possible. For example, the back surface field layer 30 may be formed by diffusion when forming the second electrode 34.

Subsequently, as shown in FIG. 6C, the antireflection film 22 and the passivation film 32 are formed on the front and rear surfaces of the semiconductor substrate 10, respectively. The antireflection film 22 and the passivation film 32 may be formed by various methods such as a vacuum evaporation method, a chemical vapor deposition method, a spin coating method, a screen printing method or a spray coating method.

Subsequently, as shown in FIG. 6D, the first electrode 24 contacting the emitter layer 20 is formed on the front surface of the semiconductor substrate 10, and the rear electric field layer 30 is formed on the rear surface of the semiconductor substrate 10. A second electrode 34 is formed in contact with the first portion 30a of the.

The first and second electrode forming pastes are applied on the antireflection film 22 and the passivation film 32 by screen printing or the like, and then fire-fired or laser firing contact or the like is described above. It is also possible to form the first and second electrodes 24, 34 of one shape. In this case, it is not necessary to carry out the step of forming the opening separately.

However, the present invention is not limited thereto. Therefore, an opening may be formed in the antireflection film 22 and the first electrode 24 may be formed in the opening by various methods such as a plating method and a vapor deposition method. Then, an opening is formed in the passivation film 32, and the second electrode 34 can be formed in this opening by various methods such as a plating method and a vapor deposition method.

Subsequently, as shown in FIG. 6E, the ribbon 142 is connected to the first electrode 24 and the second electrode 34, respectively. As described above, as described above, various processes such as a solar process using soldering and a process using a conductive film may be used.

Subsequently, as shown in FIG. 6F, the plating layer 40 is formed to surround the first electrode 24 and the ribbon 142, and the plating layer 40 is formed to surround the second electrode 34 and the ribbon 142. To form.

More specifically, the plating layer surrounding the first and second electrodes 24 and 34 and the ribbon 142 using a plating method such as electrolytic plating, electroless plating, and light-induced plating (LIP) ( 40). Here, according to the light induction plating, plating may be performed in a state where light is irradiated, thereby improving plating characteristics and sufficiently expanding the plating thickness.

As described above, in the present exemplary embodiment, various characteristics of the solar cell 150 may be improved by a simple process of forming the plating layer 40 surrounding the first and second electrodes 24 and 34 and the ribbon 142.

In the above-described embodiment, the impurity layer emitter layer 20 and the backside electric field layer 30 are formed, and then the antireflection film 22 and the passivation film 32 are formed, followed by the first and second electrodes 24. , 34) is illustrated. However, the present invention is not limited thereto. Accordingly, the order of forming the emitter layer 20, the back surface field layer 30, the antireflection film 22, the passivation film 32, the first electrode 24, and the second electrode 34 may be variously modified. .

Hereinafter, with reference to the accompanying drawings will be described in detail other embodiments of the present invention. Parts that are the same as or similar to the above-described embodiment will be omitted in detail and only different parts will be described in detail. And the same reference numerals are used for the same or similar parts.

7 is an enlarged cross-sectional view of the first electrode, the soldering layer, the ribbon, and the plating layer of the solar cell according to the embodiment of the present invention. In FIG. 7, only a portion corresponding to the enlarged portion of FIG. 3 is illustrated, and other portions are the same as or similar to those of the embodiment of FIG. 3. And the description below is also applicable to the second electrode and the ribbon connected thereto.

Referring to FIG. 7, in this embodiment, a soldering layer 26 is formed on the first electrode 24, the ribbon 142 is positioned on the soldering layer 26, and then soldered to the first electrode 24. And ribbon 142 were connected. The soldering layer 26 may include a material capable of inducing soldering, for example, tin, lead, or the like.

As such, when the soldering layer 26 is formed on the first electrode 24, the ribbon 142 should have only the main body portion 142a without the soldering portion (refer to reference numeral 142b of FIG. 3) for soldering. That is, it is possible to use a ribbon 142 made of a metal (for example, copper) that has excellent electrical properties and can reduce the material cost, thereby reducing the cost of the ribbon 142. At this time, in order to further improve the electrical conductivity, the ribbon 142 may include copper and silver together.

This structure forms the first electrode 24 and then the soldering layer 26, and after performing a tabbing process for connecting the ribbon 142 on the soldering layer 26, the plating layer 40 is formed. It can be implemented by doing. The soldering layer 26 may be formed by various methods. For example, the soldering layer 26 may be formed by a plating method using the first electrode 24 as a seed. The soldering layer 26 may be formed to be thinner than the plating layer 40, but the present invention is not limited thereto. It may be variously modified in consideration of soldering characteristics. Since the processes other than the process of forming the soldering layer 26 are similar to the process demonstrated with reference to FIGS. 6A-6F, detailed description is abbreviate | omitted.

8 is an enlarged cross-sectional view illustrating a first electrode, a ribbon, and a plating layer of a solar cell according to an exemplary embodiment of the present invention, and FIG. 9 is a partial plan view of the first electrode of FIG. 8. In FIG. 8, only a portion corresponding to the enlarged portion of FIG. 3 is illustrated, and other portions are the same as or similar to those of the embodiment of FIG. 3. 9 is an enlarged view of a portion corresponding to the enlarged portion of FIG. 4. And the description below is also applicable to the second electrode and the ribbon connected thereto.

8 and 9, in the present exemplary embodiment, the first electrode 24 includes a first electrode layer 241 and a second electrode layer 242 covering the first electrode layer 241. Here, the first electrode layer 241 may be an electrode layer formed by a printing method using a paste, and the second electrode layer 242 may be an electrode layer formed by plating.

In this case, the first and second electrode layers 241 and 242 constituting the finger electrodes (the electrodes extending left and right in FIG. 9) are formed in parallel with the first pitch P1.

In the present exemplary embodiment, the first electrode layer 241 constituting the busbar electrode includes a plurality of electrode parts EP having a relatively small width. In this case, the plurality of electrode parts EP are formed to cross each other to have an opening. The second electrode layer 242 is formed while covering the first electrode layer 241 at the portion where the first electrode layer 241 is formed. The second electrode layer 242 constituting the busbar electrode is integrally formed to cover the plurality of electrode parts EP while filling the opening.

In the present embodiment, the first electrode layer 241 constituting the busbar electrode is divided into a plurality of electrode parts EP, thereby reducing the thickness by reducing the line width. In addition, it is possible to prevent the problem that the paste is unevenly applied when using the printing method. Therefore, the amount of material used to form the first electrode layer 241 can be reduced, thereby reducing the manufacturing cost. The second electrode layer 242 may be formed to cover the first electrode layer 241 by plating using the first electrode layer 241 as a seed layer, thereby improving electrical characteristics.

At this time, the first electrode layer 241 is formed using a printing method that can simplify the manufacturing process, the second electrode layer 242 is a plating method (for example, electrolytic plating, electroless plating which can improve electrical characteristics) , Light induction plating, or the like). Thereby, the 1st electrode 24 of the outstanding characteristic can be formed by a simple process.

In this case, in the above-described embodiment, the second electrode layer 242 is separately formed, but the second electrode layer 242 may not be provided in the present embodiment. That is, as shown in FIG. 10, the ribbon 142 may be attached onto the first electrode 24 made of the first electrode layer 241 without the second electrode layer (reference numeral 242 of FIG. 9). Accordingly, the soldering part 142b of the ribbon 142 may be formed while filling the space between the first electrode layer 241 in a tabbing process. The plating layer 40 is formed while surrounding the first electrode 24 and the ribbon 142. As such, since the first electrode 24 and the ribbon 142 are connected to each other by the soldering part 142b of the ribbon 142 and the plating layer 40, the second electrode layer 242 is not provided separately. You don't have to.

In the above-described embodiment, the first electrode layer 241 of the first electrode 24 has a plurality of electrode parts EP divided according to the design. However, the present invention is not limited thereto. That is, as shown in FIG. 11, when forming the first electrode layer 241 using a printing method or the like, an electrode portion DP other than the electrode portion EP formed by design may be formed. In other words, when the paste is applied, a portion of the electrode part DP may be formed while remaining in the outer portion. The second electrode layer 242 may be formed to cover the plurality of electrode portions EP and DP while filling the plurality of electrode portions EP and DP to further improve electrical characteristics. Alternatively, as shown in FIG. 12, the first electrode layer 241 may be filled by the soldering portion 142b of the ribbon 142 without having the second electrode layer (reference numeral 242 in FIG. 11).

Features, structures, effects and the like according to the above-described embodiments are included in at least one embodiment of the present invention, and the present invention is not limited to only one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

100: solar module
124: ribbon
150: solar cell
24: first electrode
34: Second electrode
40: plating layer

Claims (18)

Photoelectric conversion unit;
An electrode connected to the photoelectric conversion unit;
A ribbon formed on the electrode and electrically connected to the electrode; And
Plating layer formed while surrounding the electrode and the ribbon
≪ / RTI > The method of claim 1,
The plating layer is formed to surround the top and side of the ribbon, and the side of the electrode together. The method of claim 1,
The plating layer is a solar cell of less resistance than the ribbon or the electrode. The method of claim 1,
The plating layer is a solar cell having a greater reflectance than the ribbon or the electrode. The method of claim 1,
The plating layer is silver (Ag), nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) and their A solar cell comprising at least one material selected from the group consisting of alloys. 6. The method of claim 5,
The solar cell containing the plating layer. The method of claim 1,
The thickness of the plating layer is a solar cell of 0.01 ~ 3㎛. The method of claim 1,
The ribbon comprises at least one material selected from the group consisting of tin, lead, copper, silver. The method of claim 1,
The ribbon includes a main body portion located therein and a soldering portion formed to surround the first portion,
The solar cell is formed in contact with the electrode and the ribbon. 10. The method of claim 9,
The first portion comprises at least one of copper and silver,
And the second portion comprises at least one of tin and lead. The method of claim 1,
Forming a soldering layer between the electrode and the ribbon to cover the electrode;
The solar cell is formed in contact with the soldering layer and the ribbon. 12. The method of claim 11,
The electrode comprises at least one of copper and silver,
And the soldering layer comprises at least one of tin and lead. The method of claim 1,
The photoelectric conversion unit includes a substrate having a conductivity type and an impurity layer formed on the substrate and having a conductivity type different from that of the substrate,
Further comprising an insulating film formed on one surface of the substrate,
And the electrode is electrically connected to the substrate or the impurity layer through the insulating layer. The method of claim 1,
The electrode includes a plurality of finger electrodes arranged in parallel to each other, and a bus bar electrode for electrically connecting the plurality of finger electrodes,
The ribbon is located on the busbar electrode. 15. The method of claim 14,
The bus bar electrode includes a first electrode layer including a plurality of electrode parts formed to have an opening located therein, and a second electrode layer covering the first electrode layer while filling the opening. 15. The method of claim 14,
The busbar electrode may include a first electrode layer including a plurality of electrode parts formed such that an opening is located therein,
And a portion of the ribbon covers the first electrode layer while filling the opening. Preparing a photoelectric conversion unit;
Forming an electrode in the photoelectric conversion unit;
Attaching a ribbon electrically connected to the electrode on the electrode; And
Forming a plating layer by plating to surround the electrode and the ribbon
Wherein the method comprises the steps of: 18. The method of claim 17,
In the forming of the plating layer, a method of manufacturing a solar cell using at least one of electrolytic plating, electroless plating, and wilderness plating.

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