KR20100109311A - Solar cell and method of fabricating the same - Google Patents

Abstract

PURPOSE: A solar cell and a method of fabricating the same is provided to simplify a process by reducing the interval between adjacent cells. CONSTITUTION: A solar battery and a manufacturing method thereof includes a back side electrode pattern(200), a light absorption layer pattern(300), a front electrode pattern(600), and a resist pattern. The back side electrode patterns are formed on the substrate and are separated from each other. The light absorption layer pattern has a partition pattern dividing a contact pattern and a unit cell. The front electrode pattern are arranged on the light absorption layer and are spaced by the partition pattern. The protective pattern is arranged inside the partition pattern and is arranged on the back side electrode.

Description

SOLAR CELL AND METHOD OF FABRICATING THE SAME

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

Recently, as the demand for energy increases, development of solar cells for converting solar energy into electrical energy is in progress.

In particular, CIGS-based solar cells, which are pn heterojunction devices having a substrate structure including a glass substrate, a metal back electrode layer, a p-type CIGS-based light absorbing layer, a high resistance buffer layer, an n-type window layer, and the like, are widely used.

In order to form such a solar cell, a mechanical patterning process may be performed. When the mechanical patterning process is performed, precise patterning is difficult, and defects may occur when patterning.

The embodiment provides a solar cell and a method of manufacturing the same that each cell is efficiently connected by precise patterning, the light absorbing layer has a large planar area, and the efficiency can be increased.

The solar cell according to the embodiment includes a plurality of back electrode patterns spaced apart from each other on a substrate; A light absorption layer pattern having a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; A front electrode pattern disposed on the light absorbing layer and spaced apart from the separation pattern; And a protection pattern disposed in the separation pattern formed on the light absorbing layer, and disposed on the back electrode pattern, wherein the front electrode pattern is inserted into the contact pattern and electrically connected to the back electrode pattern. do.

A method of manufacturing a solar cell according to an embodiment includes forming a plurality of back electrode patterns spaced apart from each other on a substrate and a protection pattern disposed on the back electrode patterns; Forming a light absorbing layer including a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; And forming a front electrode pattern disposed on the light absorbing layer and spaced apart from the separation pattern, wherein the front electrode pattern is inserted into the contact pattern and electrically connected to the rear electrode pattern. The protective pattern is disposed inside the separation pattern formed in the light absorbing layer pattern, and is disposed on the back electrode pattern.

In the solar cell and the method of manufacturing the same according to the embodiment, the protective pattern is disposed on the rear electrode pattern, and thus, the lower rear electrode pattern may be prevented from being damaged during the laser patterning process for distinguishing each cell.

In addition, even after the separation pattern is formed, the back electrode pattern is not exposed to the outside due to the protection pattern, thereby preventing oxidation of the back electrode pattern and protecting the back electrode pattern from impurities.

In addition, since each cell is separated using a laser, the distance between adjacent cells can be reduced, the process can be simplified, and the area of the region where external light is incident can be increased.

In addition, it is possible to reduce the damage caused by mechanical stress, thereby improving the efficiency of the solar cell.

In the description of the embodiments, where each substrate, layer, film, or electrode is described as being formed "on" or "under" of each substrate, layer, film, or electrode, etc. , "On" and "under" include both "directly" or "indirectly" formed through other components. In addition, the upper or lower reference of each component is described with reference to the drawings. The size of each component in the drawings may be exaggerated for description, and does not mean a size that is actually applied.

1 to 7 are cross-sectional views illustrating a method of manufacturing the solar cell according to the first embodiment.

First, as shown in FIG. 1, the back electrode 201 is formed on the substrate 100.

The substrate 100 may be glass, and a ceramic substrate such as alumina, stainless steel, a titanium substrate, or a polymer substrate may also be used.

Soda lime glass may be used as the glass substrate, and polyimide may be used as the polymer substrate.

In addition, the substrate 100 may be rigid or flexible.

The back electrode 201 may be formed of a conductor such as metal.

For example, the back electrode 201 may be formed by a sputtering process using a molybdenum (Mo) target.

This is because of high electrical conductivity of molybdenum (Mo), ohmic bonding with the light absorbing layer, and high temperature stability under Se atmosphere.

In addition, although not shown in the drawing, the back electrode 201 may be formed of at least one layer.

When the back electrode 201 is formed of a plurality of layers, the layers constituting the back electrode 201 may be formed of different materials.

As shown in FIG. 2, a plurality of protective patterns 10 are formed on the back electrode 201.

The protective pattern 10 may be formed by forming a protective film on the back electrode 201 and then performing a patterning process on the protective film.

The passivation layer may be formed by going through any one of a sputtering process, a thermal deposition process, a spray process, and a spin coating process.

The patterning process for forming the protective pattern 10 may be a wet or dry etching process using a photolithography process.

The protective pattern 10 may be formed of an insulating material or a polymer compound that does not react with the rear electrode 201 and the light absorbing layer to be formed later.

For example, the protective pattern 10 may be any one of SiO _x (x = 2 ~ 4), SiN _x (x = 4), polymer compound PMMA (polymethyl methacrylate), polyimide, and polypropylene. Can be formed.

In this case, the protection pattern 10 may be disposed between each cell so as to separate each cell.

That is, considering the positions of the light absorbing layer and the front electrode to be formed later, it is formed to be disposed between each cell.

Subsequently, as shown in FIG. 3, a patterning process is performed on the back electrode 201 to form a back electrode pattern 200.

The back electrode pattern 200 may be formed to expose the substrate 100 between the protection patterns 10.

In addition, the back electrode pattern 200 may be arranged in a stripe form or a matrix form and may correspond to each cell.

However, the back electrode pattern 200 is not limited to the above form and may be formed in various forms.

As shown in FIG. 4, the light absorbing layer 300, the first buffer layer 400, and the second buffer layer 500 are formed on the back electrode 201.

The light absorbing layer 300 includes an Ib-IIIb-VIb-based compound.

In more detail, the light absorbing layer 300 includes a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ , CIGS-based) compound.

Alternatively, the light absorbing layer 300 may include a copper-indium selenide-based (CuInSe ₂ , CIS-based) compound or a copper-gallium-selenide-based (CuGaSe ₂ , CIS-based) compound.

For example, in order to form the light absorbing layer 300, a CIG-based metal precursor film is formed on the back electrode 130 using a copper target, an indium target, and a gallium target.

Subsequently, the metal precursor film is reacted with selenium (Se) by a selenization process to form a CIGS-based light absorbing layer 300.

In addition, during the process of forming the metal precursor film and the selenization process, an alkali component included in the substrate 100 may pass through the back electrode pattern 200, and the metal precursor film and the light absorbing layer ( 300).

An alkali component may improve grain size and improve crystallinity of the light absorbing layer 300.

The light absorbing layer 300 receives external light and converts the light into electrical energy. The light absorbing layer 300 generates photo electromotive force by the photoelectric effect.

The first buffer layer 400 may be formed by stacking cadmium sulfide (CdS) on the light absorbing layer 300.

In this case, the first buffer layer 400 is an n-type semiconductor layer, and the light absorbing layer 300 is a p-type semiconductor layer. Thus, the light absorbing layer 300 and the first buffer layer 400 form a pn junction.

In addition, the second buffer layer 500 may be formed of a transparent electrode layer including any one of ITO, ZnO, and i-ZnO.

The first buffer layer 400 and the second buffer layer 500 are disposed between the light absorbing layer 300 and the front electrode to be formed later.

That is, since the difference between the lattice constant and the energy band gap is large between the light absorbing layer 300 and the front electrode, the first buffer layer 400 and the second buffer layer 500 having a band gap in between the two materials are inserted. Can form a favorable joint.

In the present embodiment, two buffer layers are formed on the light absorbing layer 300, but the present invention is not limited thereto, and the buffer layer may be formed of only one layer.

Subsequently, as shown in FIG. 5, a contact pattern 310 penetrating the light absorbing layer 300, the first buffer layer 400, and the second buffer layer 500 is formed.

The contact pattern 310 may be formed by irradiating a laser, and a portion of the back electrode pattern 200 is exposed.

In this case, the second buffer layer 500 may be processed by using a laser having a wavelength different from that of the light absorbing layer 300 and the first buffer layer 400, or the intensity according to the degree of concentration of the laser through the lens. It can also proceed by adjusting).

Since the second buffer layer 500 has a high energy band gap, a laser having a relatively high output power is used, and the first buffer layer 400 and the light absorbing layer 300 have a relatively low energy band gap. The contact pattern 310 may be formed using a laser of low power.

As illustrated in FIG. 6, a transparent conductive material is stacked on the second buffer layer 500 to form the front electrode 600 and the connection wiring 700.

When the transparent conductive material is stacked on the second buffer layer 500, the transparent conductive material may also be inserted into the contact pattern 310 to form the connection wiring 700.

The back electrode pattern 200 and the front electrode 600 are electrically connected by the connection wiring 700.

The front electrode 600 is formed of zinc oxide doped with aluminum or alumina by a sputtering process on the second buffer layer 500.

The front electrode 600 is a window layer forming a pn junction with the light absorbing layer 300. Since the front electrode 600 functions as a transparent electrode on the front of the solar cell, zinc oxide (ZnO) having high light transmittance and good electrical conductivity is provided. Is formed.

In this case, an electrode having a low resistance value may be formed by doping the zinc oxide with aluminum or alumina.

The zinc oxide thin film as the front electrode 600 may be formed by a method of depositing using a ZnO target by RF sputtering, reactive sputtering using a Zn target, and an organometallic chemical vapor deposition method.

In addition, a double structure in which an indium tin oxide (ITO) thin film having excellent electro-optical properties is laminated on a zinc oxide thin film may be formed.

Subsequently, as illustrated in FIG. 7A, a separation pattern 320 penetrating the light absorbing layer 300, the first buffer layer 400, and the second buffer layer 500 is formed.

The separation pattern 320 may be formed by irradiating a laser, and the upper surface of the protective pattern 10 may be exposed.

The laser for forming the separation pattern 320 has a wavelength of 532 ~ 1064 nm, and may have a power of 5 ~ 20 W.

The first buffer layer 400, the second buffer layer 500, and the front electrode 600 may be separated by the separation pattern 320, and may be separated by the protection pattern 10 and the separation pattern 320. The cells C1 and C2 may be separated from each other.

In this case, when the protective pattern 10 is disposed on the back electrode pattern 200 and patterned by a laser, the lower back electrode pattern 200 may be prevented from being damaged.

In addition, even after the separation pattern 320 is formed, the rear electrode pattern 200 is not exposed to the outside due to the protective pattern 10, thereby preventing oxidation of the rear electrode pattern 200 and preventing the rear electrode from impurities. The pattern 200 may be protected.

In the present embodiment, the width of the separation pattern 320 and the width of the protection pattern 10 are the same, but the present invention is not limited thereto. The width of the separation pattern 320 is greater than the width of the protection pattern 10. It may be narrowly formed.

That is, as shown in FIG. 7B, the separation pattern 320 may be formed to have a width of a pattern capable of separating the cells C1 and C2, and the protection pattern 10 may be formed in the separation pattern 320. It can be formed wider than the width of).

In addition, the first buffer layer 400, the second buffer layer 500, and the light absorbing layer 300 may be arranged in a stripe form or a matrix form by the separation pattern 320.

The separation pattern 300 is not limited to the above form and may be formed in various forms.

Cells C1 and C2 including the back electrode pattern 200, the light absorbing layer 300, the first buffer layer 400, the second buffer layer 500, and the front electrode 600 by the separation pattern 320. Is formed.

In this case, each of the cells C1 and C2 may be connected to each other by the connection wiring 700. That is, the connection wiring 700 electrically connects the back electrode pattern 200 of the second cell C2 and the front electrode 600 of the first cell C1 adjacent to the second cell C2. do.

8 to 11 are cross-sectional views illustrating a method of manufacturing the solar cell according to the second embodiment.

In the second embodiment, the same reference numerals are assigned to components that are configured and operated in the same manner as the first embodiment, and detailed description thereof will be omitted.

First, as shown in FIG. 8, the back electrode 201 is formed on the substrate 100.

The substrate 100 may be glass, and a ceramic substrate such as alumina, stainless steel, a titanium substrate, or a polymer substrate may also be used.

The back electrode 201 may be formed of a conductor such as metal.

In addition, although not shown in the drawing, the back electrode 201 may be formed of at least one layer.

Subsequently, as shown in FIG. 9, a patterning process is performed on the back electrode 201 to form a back electrode pattern 200.

The back electrode pattern 200 may be formed to expose the substrate 100.

In addition, the back electrode pattern 200 may be arranged in a stripe form or a matrix form and may correspond to each cell.

10, the passivation layer 5 is formed on the substrate 100 on which the back electrode pattern 200 is formed.

The passivation layer 5 may be formed by going through any one of a sputtering process, a thermal deposition process, a spray process, and a spin coating process.

The passivation layer 5 may be formed of an insulating material or a polymer compound that does not react with the back electrode 201 and the light absorbing layer to be formed later.

For example, the passivation layer 5 is formed of any one of SiO _x (x = 2-4), SiN _x (x = 4), a polymer compound polymethyl methacrylate (PMMA), polyimide, and polypropylene. Can be.

Subsequently, as shown in FIG. 11, a plurality of protective patterns 10 are formed on the back electrode pattern 200.

The protective pattern 10 may be formed by performing a wet or dry etching process using a photolithography process on the protective film 5 formed on the back electrode pattern 200.

In this case, the protection pattern 10 may be disposed between each cell so as to separate each cell.

That is, considering the positions of the light absorbing layer and the front electrode to be formed later, it is formed to be disposed between each cell.

In addition, since the process of forming the light absorbing layer 300 and the front electrode 600 on the protective pattern 10 is the same as the method shown in Figures 4 to 7 of the first embodiment, the subsequent steps will be omitted. .

In the solar cell and the method of manufacturing the same according to the embodiments described above, the protective pattern is disposed on the rear electrode pattern, thereby preventing the lower rear electrode pattern from being damaged during the laser patterning process for distinguishing each cell. .

In addition, even after the separation pattern is formed, the back electrode pattern is not exposed to the outside due to the protection pattern, thereby preventing oxidation of the back electrode pattern and protecting the back electrode pattern from impurities.

In addition, since each cell is separated using a laser, the distance between adjacent cells can be reduced, the process can be simplified, and the area of the region where external light is incident can be increased.

In addition, it is possible to reduce the damage caused by mechanical stress, thereby improving the efficiency of the solar cell.

Although described above with reference to the embodiment is only an example and is not intended to limit the invention, those of ordinary skill in the art to which the present invention does not exemplify the above within the scope not departing from the essential characteristics of this embodiment It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 to 7 are cross-sectional views illustrating a method of manufacturing the solar cell according to the first embodiment.

8 to 11 are cross-sectional views illustrating a method of manufacturing the solar cell according to the second embodiment.

Claims (13)

A plurality of back electrode patterns spaced apart from each other on the substrate; A light absorption layer pattern having a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; A front electrode pattern disposed on the light absorbing layer and spaced apart from the separation pattern; And Is disposed inside the separation pattern formed in the light absorbing layer, and includes a protective pattern disposed on the back electrode pattern, And the front electrode pattern is inserted into the contact pattern and electrically connected to the back electrode pattern. The method of claim 1, The protective pattern is a solar cell formed of any one of SiO _x (x = 2 ~ 4), SiN _x (x = 4), a polymer compound polymethyl methacrylate (PMMA), polyimide, polypropylene. The method of claim 1, The protective pattern is a solar cell formed lower than the height of the light absorption layer pattern. The method of claim 1, The exposed upper surface of the protective pattern is disposed on the same horizontal plane as the rear electrode pattern, or higher than the upper surface of the rear electrode pattern. The method of claim 1, The width of the separation pattern is a solar cell comprising the same or smaller than the width of the protective pattern. Forming a plurality of back electrode patterns spaced apart from each other on a substrate and a protection pattern disposed on the back electrode patterns; Forming a light absorbing layer including a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; And Forming a front electrode pattern disposed on the light absorbing layer and spaced apart from the separation pattern; The front electrode pattern is inserted into the contact pattern and electrically connected to the back electrode pattern, The protective pattern is disposed in the separation pattern formed in the light absorbing layer pattern, the method of manufacturing a solar cell disposed on the back electrode pattern. The method of claim 6, Forming the back electrode pattern and the protective pattern on the substrate, Forming a back electrode on the substrate; Forming a protective film on the back electrode; Patterning the passivation layer to form a passivation pattern on the back electrode; And And forming a back electrode pattern by patterning the back electrode having the protection pattern formed thereon. The method of claim 6, Forming the back electrode pattern and the protective pattern on the substrate, Forming a back electrode on the substrate; Patterning the back electrode to form a back electrode pattern; Forming a protective film on the back electrode pattern; And Patterning the passivation layer to form a passivation pattern on the back electrode pattern. The method of claim 6, The separation pattern is a method of manufacturing a solar cell is formed by irradiating a laser (laser) on the back electrode. The method of claim 9, The laser for forming the separation pattern has a wavelength of 532 ~ 1064 nm, the manufacturing method of a solar cell comprising a laser having a power of 5 ~ 20W. The method of claim 6, The protective pattern is a method of manufacturing a solar cell formed of any one of SiO _x (x = 2 ~ 4), SiN _x (x = 4), polymer compound PMMA (polymethyl methacrylate), polyimide, polypropylene . The method of claim 6, The protective pattern is a method of manufacturing a solar cell lower than the height of the light absorption layer pattern. The method of claim 6, The width of the separation pattern is a solar cell manufacturing method comprising the same or smaller than the width of the protective pattern.

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