KR101283302B1 - Solar cell apparatus and method of fabricating the same - Google Patents

Solar cell apparatus and method of fabricating the same Download PDF

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Publication number
KR101283302B1
KR101283302B1 KR1020110030877A KR20110030877A KR101283302B1 KR 101283302 B1 KR101283302 B1 KR 101283302B1 KR 1020110030877 A KR1020110030877 A KR 1020110030877A KR 20110030877 A KR20110030877 A KR 20110030877A KR 101283302 B1 KR101283302 B1 KR 101283302B1
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South Korea
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layer
back electrode
electrode layer
light absorbing
holes
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KR1020110030877A
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Korean (ko)
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KR20120113127A (en
Inventor
김경암
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엘지이노텍 주식회사
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Abstract

According to an embodiment, a solar cell includes a support substrate; A back electrode layer formed on the support substrate and having irregularities formed on a portion of an upper surface thereof; A light absorbing layer on the back electrode layer; A buffer layer on the light absorbing layer; And a window layer on the buffer layer.

Description

SOLAR CELL AND MANUFACTURING METHOD THEREOF {SOLAR CELL APPARATUS AND METHOD OF FABRICATING THE SAME}

An embodiment relates to a solar cell and a manufacturing method thereof.

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

In particular, a CIGS solar cell which is a pn heterojunction device 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 transparent electrode layer, and the like is widely used.

In addition, various studies are underway to increase the efficiency of such solar cells.

Embodiments provide a solar cell and a method of manufacturing the same having improved reliability by reducing contact resistance between a window layer and a back electrode layer.

According to an embodiment, a solar cell includes a support substrate; A back electrode layer formed on the support substrate and having irregularities formed on a portion of an upper surface thereof; A light absorbing layer on the back electrode layer; A buffer layer on the light absorbing layer; And a window layer on the buffer layer.

A solar cell manufacturing method according to an embodiment includes forming a back electrode layer on a supporting substrate; Forming a light absorbing layer on the back electrode layer; Forming a buffer layer on the light absorbing layer; And forming a through groove by etching a portion of the light absorbing layer and the buffer layer to expose a portion of the back electrode layer. Forming irregularities on the exposed top surface of the back electrode layer; And forming a window layer to fill the buffer layer upper surface and the through groove.

According to the embodiment, irregularities are formed on the upper surface of the back electrode layer exposed by the through grooves that divide the light absorbing layer into a plurality of light absorbing portions. The area of the back electrode layer exposed by the unevenness increases, and accordingly, the area of the window layer in contact with the unevenness of the back electrode layer also increases.

Increasing the contact area as described above can reduce the contact resistance of the window layer and the back electrode layer, it can be improved efficiency.

1 is a plan view showing a solar cell according to an embodiment.
FIG. 2 is a cross-sectional view illustrating a cross section taken along AA ′ in FIG. 1.
FIG. 3 is an enlarged cross-sectional view of region B in FIG. 2.
4 to 9 are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment.

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 the sake of explanation and does not mean the size actually applied.

1 is a plan view illustrating a solar cell according to an embodiment. FIG. 2 is a cross-sectional view illustrating a cross section taken along a line A-A 'in FIG. 1, and FIG. 3 is an enlarged cross-sectional view of region B in FIG. 2.

1 to 3, a solar cell according to an embodiment includes a back electrode layer 200, a light absorbing layer 300, a buffer layer 400, and a window layer 500 on which a support substrate 100 and an unevenness 210 are formed. It includes.

The support substrate 100 has a plate shape and supports the back electrode layer 200, the light absorbing layer 300, the buffer layer 400, and the window layer 500.

The support substrate 100 may be an insulator. The support substrate 100 may be a glass substrate, a plastic substrate, or a metal substrate. In more detail, the support substrate 100 may be a soda lime glass substrate. The supporting substrate 100 may be transparent. The support substrate 100 may be rigid or flexible.

The back electrode layer 200 is disposed on the support substrate 100. The back electrode layer 200 is a conductive layer. Examples of the material used for the back electrode layer 200 include a metal such as molybdenum.

In addition, the back electrode layer 200 may include two or more layers. In this case, each of the layers may be formed of the same metal, or may be formed of different metals.

First through holes TH1 are formed in the back electrode layer 200. The first through holes TH1 are open regions that expose the top surface of the support substrate 100. The first through holes TH1 may have a shape extending in one direction when viewed in a plan view.

The width of the first through holes TH1 may be about 40 μm to 100 μm.

The back electrode layer 200 is divided into a plurality of back electrodes by the first through holes TH1. That is, the back electrodes are defined by the first through holes TH1.

The back electrodes are spaced apart from each other by the first through holes TH1. The back electrodes are arranged in a stripe shape.

Alternatively, the back electrodes may be arranged in a matrix form. At this time, the first through grooves TH1 may be formed in a lattice form when viewed from a plane.

The light absorbing layer 300 is disposed on the back electrode layer 200. In addition, the material included in the light absorbing layer 300 is filled in the first through holes TH1.

The light absorbing layer 300 includes a group I-III-VI compound. For example, the light absorbing layer 300 is copper-indium-gallium-selenide-based (Cu (In, Ga) Se 2; CIGS-based) crystal structure, a copper-indium-selenide-based or copper-gallium-selenide Crystal structure.

The energy band gap of the light absorption layer 300 may be about 1 eV to 1.8 eV.

In addition, the light absorbing layer 300 defines a plurality of light absorbing portions by the second through holes TH2. That is, the light absorbing layer 300 is divided into the light absorbing portions by the second through holes TH2.

A portion of the upper surface of the back electrode layer 200 is exposed by the second through holes TH2. An upper surface of the exposed back electrode layer 200 forms an unevenness 210. The irregularities 210 may be formed at a height of less than half of the back electrode layer 200.

The irregularities 210 may be formed in the shape of a cross section, such as a rectangle, a triangle.

The buffer layer 400 is disposed on the light absorbing layer 300. The solar cell of the present invention forms a pn junction between the light absorbing layer 300 of the CIGS or CIGSS compound thin film of the p-type semiconductor and the window layer 500 thin film of the n-type semiconductor. However, since the two materials have a large difference in lattice constant and band gap energy, a buffer layer having a band gap in between the two materials is required to form a good junction.

The buffer layer 400 includes cadmium sulfide (CdS), and an energy band gap of the buffer layer 400 is about 2.2 eV to 2.4 eV.

Second through holes TH2 are formed in the light absorbing layer 300 and the buffer layer 400. The second through holes TH2 are open regions exposing the top surface of the back electrode layer 200.

The second through grooves TH2 are formed adjacent to the first through grooves TH1. That is, a part of the second through grooves TH2 is formed on the side of the first through grooves TH1 when viewed in plan.

The width of the second through holes TH2 may be about 40 μm to about 100 μm.

The window layer 500 is disposed on the buffer layer 400. The window layer 500 is transparent and a conductive layer. In addition, the resistance of the window layer 500 is higher than the resistance of the back electrode layer 200. For example, the resistance of the window layer 500 may be about 10 to 200 times greater than the resistance of the back electrode layer 200.

 The window layer 500 may include an oxide. For example, the window layer 500 may include zinc oxide, indium tin oxide (ITO), or indium zinc oxide (IZO).

In addition, the oxide may include conductive impurities such as aluminum (Al), alumina (Al 2 O 3 ), magnesium (Mg), or gallium (Ga). In more detail, the window layer 500 may include aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO), or the like.

The connection part 550 is disposed inside the second through holes TH2. The connection part 550 extends downward from the window layer 500 and is connected to the back electrode layer 200. For example, the connection part 550 extends from the window of the first cell and is connected to the back electrode of the second cell. The connection part 550 may be in contact with the back electrode layer 200 in a shape corresponding to the unevenness 210.

Thus, the connection unit 550 connects adjacent cells to each other. In more detail, the connection part 550 connects a window and a back electrode included in the cells C1, C2 ... adjacent to each other to allow current to flow. If the width of the second through holes TH2 is widened, current may be smoothly flowed, but this causes a problem of reducing the volume of the light absorbing layer 300.

Therefore, the convex and convex 210 is formed to smooth the current flow and minimize the volume reduction of the light absorbing layer 300.

The area of the back electrode layer 200 exposed by the unevenness 210 is increased, thereby increasing the area of the connection portion 550 in contact with the unevenness 210 of the back electrode layer 200.

As described above, when the contact area is increased, the contact resistance between the window layer 500 and the back electrode layer 200 may be reduced, thereby improving efficiency.

The connection part 550 is integrally formed with the window layer 500. That is, the material used as the connection part 550 is the same as the material used as the window layer 500.

Third through holes TH3 are formed in the light absorbing layer 300, the buffer layer 400, and the window layer 500. The third through holes TH3 are open regions exposing the top surface of the back electrode layer 200. For example, the width of the third through holes TH3 may be about 80 μm to about 200 μm.

The third through grooves TH3 are formed at positions adjacent to the second through grooves TH2. More specifically, the third through-holes TH3 are disposed beside the second through-holes TH2. That is, when viewed in plan, the third through grooves TH3 are arranged next to the second through grooves TH2.

The buffer layer 400 is divided into a plurality of buffers by the third through holes TH3.

In addition, the window layer 500 is divided into a plurality of windows by the third through holes TH3. That is, the windows are defined by the third through holes TH3.

The windows have a shape corresponding to the back electrodes. That is, the windows are arranged in a stripe shape. Alternatively, the windows may be arranged in a matrix form.

In addition, a plurality of cells C1, C2... Are defined by the third through holes TH3. In more detail, the cells C1, C2... Are defined by the second through holes TH2 and the third through holes TH3. That is, the solar cell according to the embodiment is divided into the cells C1, C2... By the second through holes TH2 and the third through holes TH3.

4 to 9 are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment. For a description of the present manufacturing method, refer to the description of the solar cell described above.

Referring to FIG. 4, the back electrode layer 200 is formed on the support substrate 100, and the back electrode layer 200 is patterned to form first through holes TH1. Accordingly, a plurality of back electrodes are formed on the support substrate 100. The back electrode layer 200 is patterned by a laser.

The first through holes TH1 expose the top surface of the support substrate 100.

In addition, an additional layer, such as a diffusion barrier, may be interposed between the support substrate 100 and the back electrode layer 200, wherein the first through holes TH1 expose the top surface of the additional layer. .

Referring to FIG. 5, a light absorbing layer 300 is formed on the back electrode layer 200. The light absorption layer 300 may be formed by a sputtering process or an evaporation process.

For example, a copper-indium-gallium-selenide (Cu (In, Ga) Se 2 ; CIGS system) is formed while simultaneously evaporating copper, indium, gallium, and selenium to form the light absorption layer 300. A method of forming a light absorbing layer 300 of a metal precursor film and a method of forming a metal precursor film by a selenization process are widely used.

After the metal precursor film is formed and then subjected to selenization, a metal precursor film is formed on the back electrode 200 by a sputtering process using a copper target, an indium target, and a gallium target.

Then, the metal precursor film is formed with a light absorbing layer 300 of copper-indium-gallium-selenide (Cu (In, Ga) Se 2, CIGS system) by a selenization process.

Alternatively, the copper target, the indium target, the sputtering process using the gallium target, and the selenization process may be performed simultaneously.

Alternatively, the CIS-based or CIG-based optical absorption layer 300 can be formed by using only a copper target and an indium target, or by a sputtering process and a selenization process using a copper target and a gallium target.

Next, the buffer layer 400 is formed on the light absorbing layer 300. The buffer layer 400 may be formed by, for example, a physical vapor deposition (PVD) or a metal-organic chemical vapor deposition (MOCVD) method.

Referring to FIG. 6, portions of the light absorbing layer 300 and the buffer layer 400 are removed to form second through holes TH2.

The second through grooves TH2 may be formed by a mechanical device such as a tip or a laser device.

In this case, the width of the second through holes TH2 may be about 40 μm to about 150 μm. In addition, the second through holes TH2 are formed to expose a portion of the top surface of the back electrode layer 200.

Referring to FIG. 7, irregularities 210 are formed on an upper surface of the back electrode layer 200 exposed by the second through holes TH2.

The unevenness 210 may be formed by using dry etching, wet etching, or a needle. The irregularities 210 may be formed to less than half the thickness of the back electrode layer 200.

Referring to FIG. 8, a window layer 500 is formed on the window layer 400 and inside the second through holes TH2. That is, the window layer 500 is formed by depositing a transparent conductive material on the buffer layer 400 and inside the second through holes TH2.

In this case, the transparent conductive material is filled in the second through holes TH2, and the window layer 500 directly contacts the back electrode layer 200.

In this case, the window layer 500 may be formed by depositing the transparent conductive material in an oxygen-free atmosphere. In more detail, the window layer 500 may be formed by depositing zinc oxide doped with aluminum in an inert gas atmosphere containing no oxygen.

9, a portion of the light absorbing layer 300, the buffer layer 400, and the window layer 500 is removed to form third through holes TH3. Accordingly, the window layer 500 is patterned to define a plurality of windows and a plurality of cells C1, C2... The width of the third through holes TH3 may be about 80 μm to about 200 μm.

As described above, the area of the back electrode layer 200 exposed by the unevenness 210 is increased by the method of manufacturing the solar cell according to the embodiment. Accordingly, an area in which the connection part 550 is in contact with the unevenness 210 of the back electrode layer 200 may also increase, thereby reducing contact resistance between the window layer 500 and the back electrode layer 200, thereby improving efficiency. Can be.

In addition, the features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in each embodiment may be combined or modified with respect to 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.

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, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (9)

Support substrate;
A back electrode layer formed on the support substrate and having irregularities formed on a portion of an upper surface thereof;
A light absorbing layer on the back electrode layer;
A buffer layer on the light absorbing layer; And
A window layer on the buffer layer;
The back electrode layer is in contact with the window layer in the region where the irregularities are formed.
delete The method of claim 1,
The window layer is in contact with the back electrode layer in a shape corresponding to the irregularities. The method of claim 1,
The unevenness is a solar cell cross section is formed in a rectangle. The method of claim 1,
The uneven solar cell is formed so that the width is narrowed toward the top. The method of claim 1,
The unevenness is formed in less than half of the thickness of the back electrode layer. Forming a back electrode layer on the support substrate;
Forming a light absorbing layer on the back electrode layer;
Forming a buffer layer on the light absorbing layer; And
Forming a through groove by etching a portion of the light absorbing layer and the buffer layer so that a portion of the back electrode layer is exposed;
Forming irregularities on the exposed top surface of the back electrode layer;
And forming a window layer to fill the buffer layer upper surface and the through groove. The method of claim 7, wherein
The unevenness is a solar cell manufacturing method is formed by at least one method of dry etching, wet etching or needle (Needle). The method of claim 7, wherein
A solar cell manufacturing method for forming a cross section of the irregularities have a rectangular shape.
KR1020110030877A 2011-04-04 2011-04-04 Solar cell apparatus and method of fabricating the same KR101283302B1 (en)

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KR101428469B1 (en) * 2013-04-03 2014-08-13 한국에너지기술연구원 Fabrication Method for CIGS Solar Cell having Double Texturing Electrode Layer.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002319686A (en) 2001-04-23 2002-10-31 Matsushita Electric Ind Co Ltd Method of manufacturing integrated thin film solar battery
JP2007311578A (en) 2006-05-19 2007-11-29 Matsushita Electric Ind Co Ltd Integrated thin film solar battery and manufacturing method thereof
KR20090014450A (en) * 2007-08-06 2009-02-11 주성엔지니어링(주) The method for manufacturing thin film type solar cell, and thin film type solar cell made by the method
KR20100009249A (en) * 2008-07-18 2010-01-27 삼성전자주식회사 Solar cell and fabrication method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002319686A (en) 2001-04-23 2002-10-31 Matsushita Electric Ind Co Ltd Method of manufacturing integrated thin film solar battery
JP2007311578A (en) 2006-05-19 2007-11-29 Matsushita Electric Ind Co Ltd Integrated thin film solar battery and manufacturing method thereof
KR20090014450A (en) * 2007-08-06 2009-02-11 주성엔지니어링(주) The method for manufacturing thin film type solar cell, and thin film type solar cell made by the method
KR20100009249A (en) * 2008-07-18 2010-01-27 삼성전자주식회사 Solar cell and fabrication method thereof

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