KR101072116B1

KR101072116B1 - Solar cell and method of fabircating the same

Info

Publication number: KR101072116B1
Application number: KR1020090093622A
Authority: KR
Inventors: 박지홍
Original assignee: 엘지이노텍 주식회사
Priority date: 2009-09-30
Filing date: 2009-09-30
Publication date: 2011-10-10
Also published as: KR20110035787A

Abstract

A solar cell according to an embodiment includes a first cell unit and a second cell unit formed on a substrate; A first bus bar electrically connected to the first cell unit; A second bus bar electrically connected to the second cell unit; A first connection electrode electrically connecting the first cell unit and the second cell unit; A first diode disposed between the first bus bar and the first connection electrode; And a second diode disposed between the second bus bar and the first connection electrode.

A method of manufacturing a solar cell according to an embodiment includes forming a first cell unit and a second cell unit on a substrate; Forming a first bus bar electrically connected to the first cell unit and a second bus bar electrically connected to the second cell unit; Forming a first connection electrode electrically connecting the first cell unit and the second cell unit; And forming a first diode between the first bus bar and the first connection electrode, and forming a second diode between the second bus bar and the first connection electrode.

Solar cell, diode, connection electrode

Description

SOLAR CELL AND METHOD OF FABIRCATING THE SAME}

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

Recently, as energy demand increases, development of a solar cell converting solar energy into electrical energy is in progress.

In particular, CIGS-based solar cells that 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 such a solar cell, a plurality of cells are formed in one panel, and the cells are connected in series.

If a failure occurs in any one of these cells, the panel is not used and is discarded.

In addition, when a shadow is caused by an external object on the solar cell panel or foreign matter such as impurities occurs on the solar cell panel, a cell in which the shadow or foreign matter is generated increases in load and causes overheating.

The embodiment provides a solar cell and a method of manufacturing the same that can be used as a solar cell without deterioration even if a defective cell is generated or a shadow is generated on the solar cell panel.

In the method of manufacturing a solar cell according to the embodiment, after forming a plurality of cell units on a substrate, each cell unit is connected in series with a connection electrode, and a diode is formed between the busbar and the connection electrode and between each connection electrode. .

Therefore, when any one of the shadows of the cell unit is formed or foreign matter is formed on the cell unit, the charge is formed to be diverted to the diode, so that no deterioration occurs even if a defective cell is generated or a shadow is generated on the solar cell panel. Solar cells can be used.

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.

14 is a plan view illustrating a solar cell according to an embodiment.

As shown in FIG. 14, the solar cell according to the embodiment includes a first cell area A11, a second cell area A22, a third cell area A33, a fourth cell area A44, and a fifth cell area. (A55), the sixth cell region (A66) is included.

Each cell area in which N cells are formed is formed in each area.

A first bus bar 810 is formed in the first cell area A11, and a second bus bar 820 is formed in the sixth cell area A66.

The first cell area A11, the second cell area A22, the third cell area A33, the fourth cell area A44, the fifth cell area A55, and the sixth cell area A66. The first connection electrode 710, the second connection electrode 720, the third connection electrode 730, the fourth connection electrode 740, and the fifth connection electrode 750 are formed to connect the two to each other.

The first connection electrode 710 connects the first cell area A11 and the second cell area A22 in series, and the second connection electrode 720 connects the second cell area A22 and the third cell. The cell region A33 is connected in series.

In addition, the third connection electrode 730 connects the third cell area A33 and the fourth cell area A44 in series, and the fourth connection electrode 740 is connected to the fourth cell area A44 and the third cell area A44. The fifth cell region A55 is connected in series, and the fifth connection electrode 750 connects the fifth cell region A55 and the sixth cell region A66 in series.

Therefore, the first cell area A11, the second cell area A22, the third cell area A33, the fourth cell area A44, the fifth cell area A55, and the sixth cell area A66. Are all connected in series by the connection electrodes 710, 720, 730, 740, and 750.

In addition, a first diode D1 is disposed between the first bus bar 810 and the second connection electrode 720, and a second between the second connection electrode 720 and the fourth connection electrode 740. The diode D2 is disposed, and the third diode D3 is disposed between the fourth connection electrode 740 and the second bus bar 820.

When the first, second, and third diodes D1, D2, and D3 have a shadow on one of the cell regions, or a foreign substance is formed on the solar cell panel, charges may be diverted to the diode. So that it is formed.

Hereinafter, the solar cell will be described in more detail according to the manufacturing process of the solar cell.

1 to 16 are cross-sectional views and plan views illustrating a method of manufacturing the solar cell according to the embodiment.

First, as shown in FIG. 1, the first area A1, the second area A2, the third area A3, the fourth area A4, the fifth area A5, and the sixth area A6. Prepare a substrate 100 comprising a).

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.

Cells in which N cells are formed in the first area A1, the second area A2, the third area A3, the fourth area A4, the fifth area A5, and the sixth area A6, respectively. Areas will be formed.

2 to 13 illustrate cross-sectional views of O 'and' I 'of FIG. 1.

The first area A1, the third area A3, and the fifth area A5 are formed in the same shape, and the second area A2, the fourth area A4, and the sixth area A6 are formed. Since they are formed in the same shape as each other, only cross-sectional views of the first area A1 and the second area A2 are presented.

2 and 3, the back electrode pattern 200 is formed on the substrate 100.

The back electrode pattern 200 may be formed by forming a back electrode film on the substrate 100 and then patterning the photolithography process.

Alternatively, after the mask is disposed on the substrate 100, the back electrode pattern 200 may be formed only in each region.

The back electrode pattern 200 may be formed of a conductor such as metal.

For example, the back electrode pattern 200 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, the back electrode pattern 200 may be formed of at least one layer.

When the back electrode pattern 200 is formed of a plurality of layers, the layers constituting the back electrode pattern 200 may be formed of different materials.

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.

4 and 5, a light absorbing layer 300 and a buffer layer 400 are formed on the back electrode pattern 200.

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, to form the light absorbing layer 300, a CIG-based metal precursor film is formed on the back electrode pattern 200 using a copper target, an indium target, and a gallium target.

Thereafter, 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.

In addition, the light absorbing layer 300 may form copper, indium, gallium, selenide (Cu, In, Ga, Se) by co-evaporation.

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 buffer layer 400 is formed of at least one layer, and any one or a stack of cadmium sulfide (CdS), ITO, ZnO, and i-ZnO on the substrate 100 on which the light absorbing layer 300 is formed. Can be formed.

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

The buffer layer 400 is 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, a good junction may be formed by inserting the buffer layer 400 having a band gap between the two materials.

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

6 and 7, the contact pattern 310 penetrating the light absorbing layer 300 and the buffer layer 400 is formed.

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

8 and 9, a transparent conductive material is stacked on the buffer layer 400 to form the front electrode 500 and the connection wiring 700.

When the transparent conductive material is stacked on the buffer layer 400, 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 500 are electrically connected to each other by the connection wiring 700.

The front electrode 500 is formed of zinc oxide doped with aluminum by performing a sputtering process on the substrate 100.

The front electrode 500 is a window layer forming a pn junction with the light absorbing layer 300. Since the front electrode 500 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.

At this time, the aluminum oxide may be doped with aluminum to form an electrode having a low resistance value.

The zinc oxide thin film which is the front electrode 500 may be formed by a method of depositing using a ZnO target by RF sputtering, reactive sputtering using a Zn target, and organometallic chemical vapor deposition.

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.

Next, as shown in FIGS. 10 and 11, a separation pattern 320 penetrating the light absorbing layer 300, the buffer layer 400, and the front electrode 500 is formed.

The separation pattern 320 may be formed by a mechanical method, and a portion of the back electrode pattern 200 is exposed.

The buffer layer 400 and the front electrode 500 may be separated by the separation pattern 320, and each cell may be separated from each other by the separation pattern 320.

The front electrode 500 buffer layer 400 and the light absorbing layer 300 may be arranged in a stripe shape or a matrix shape by the separation pattern 320.

The separation pattern 320 is not limited to the above form and may be formed in various forms.

12 and 13, a first bus bar 810, a first connection electrode 710, and a second connection electrode 720 are formed to be connected to the back electrode pattern 200.

The first bus bar 810, the first connection electrode 710, and the second connection electrode 720 are the front electrode 500, the buffer layer 400, and the light absorbing layer 300 formed at the end of the substrate 100. A portion of) may be removed to expose the back electrode pattern 200 and then formed.

In the present embodiment, the rear electrode pattern 200 is connected to the first bus bar 810, the first connection electrode 710, and the second connection electrode 720, but the present invention is not limited thereto. The first bus bar 810, the first connection electrode 710, and the second connection electrode 720 may be formed on ().

12 and 13, the structure of the solar cell formed in the first region A1 and the structure of the solar cell formed in the second region A2 may be symmetrically formed. .

That is, the solar cell structure formed in the first region A1 may connect the first bus bar 810 to a positive electrode and connect the first connection electrode 710 to a negative electrode. The solar cell structure formed in the second area A2 may connect the first connection electrode 710 to a positive electrode and the second connection electrode 720 to a negative electrode. Form into a structure.

In this case, the back electrode pattern 200 formed in the first region A1 and the back electrode pattern 200 formed in the second region A2 are connected to the first connection electrode 710 to be connected in series. Can be connected.

As shown in FIG. 14, the cell for each region thus formed is a first cell region A11 in the first region A1, a second cell region A22 and a second region in the second region A2. In the third region A3, the third cell region A33, in the fourth region A4, the fourth cell region A44, in the fifth region A5, the fifth cell region A55, and the sixth region A6. Sixth cell area A66 is formed in each.

That is, each cell region in which N cells are formed is formed in each region.

The first connection electrode 710 connects the first cell area A11 and the second cell area A22 in series, and the second connection electrode 720 is connected to the second cell area A22 and the second cell area A22. The three cell areas A33 are connected in series.

That is, as shown in FIG. 15, when the shadow or the failure occurs in the third cell area A33, the resistance increases in the shadowed cell or the defective cell.

Therefore, in this case, charge is transferred from the second bus bar 820 through the sixth cell region A66, the fifth cell region A55, and the second diode D2 to the second cell region A22. ), And moves to the first cell area A11 through the first bus bar 810.

Also, when the shadow or the defect occurs in the fourth cell region A44, the above operation is performed.

When a shadow or a defect occurs in any one of the third cell area A33 and the fourth cell area A44, the current flow may be as described above.

Accordingly, the first cell area A11 and the second cell area A22 are the first cell unit CU1, the third cell area A33, and the fourth cell area A44 are the second cell unit CU2. ), The fifth cell region A55 and the sixth cell region A66 may be considered to be bundled into the third cell unit CU3.

That is, when the shadow or defect occurs in the first cell unit CU1, current flows through the first diode D1, and when the shadow or defect occurs in the second cell unit CU2, When a current flows through the second diode D2, and a shadow or a defect occurs in the third cell unit CU3, the current flows through the third diode D3.

The first, second, and third diodes D1, D2, and D3 may be disposed in a junction box 800 disposed on the rear surface of the substrate 100.

In order to arrange the first, second, and third diodes D1, D2, and D3 in the junction box 800, the first bus bar 810, the second connection electrode 720, and the fourth connection electrode are provided. 740 and the second bus bar 820 may be extended.

That is, as shown in FIG. 16, the first bus bar 810, the second connection electrode 720, the fourth connection electrode 740, and the second bus bar 820 toward the rear surface of the substrate 100. After the extension, the first, second, and third diodes D1, D2, and D3 are formed in the junction box 800.

In this case, the first bus bar 810 may be connected to (+), and the second bus bar 820 may be connected to a negative output terminal.

In the method of manufacturing a solar cell according to the embodiment described above, after forming a plurality of cell units on a substrate, each cell unit is connected in series with a connection electrode, and a diode is connected between the busbar and the connection electrode and between each connection electrode. To form.

Although the above description has been made based on the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains may not have been exemplified above without departing from the essential characteristics of the present embodiments. 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.

Claims

A first cell unit and a second cell unit formed on the substrate;

A first bus bar electrically connected to the first cell unit;

A second bus bar electrically connected to the second cell unit;

A first connection electrode electrically connecting the first cell unit and the second cell unit;

A first diode disposed between the first bus bar and the first connection electrode; And

A second diode disposed between the second bus bar and the first connection electrode,

The first cell unit and the second cell unit includes at least two or more cell regions in which a plurality of cells are formed, and the at least two cell regions are disposed in series with each other.

The method of claim 1,

The first diode and the second diode solar cell comprising a disposed in the junction box.

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The method of claim 1,

The at least two cell regions formed in the first cell unit are electrically connected by a second connection electrode,

And at least two cell regions formed in the second cell unit are electrically connected by a third connection electrode.

Forming a first cell unit and a second cell unit on the substrate;

Forming a first bus bar electrically connected to the first cell unit and a second bus bar electrically connected to the second cell unit;

Forming a first connection electrode electrically connecting the first cell unit and the second cell unit; And

Forming a first diode between the first bus bar and the first connection electrode, and forming a second diode between the second bus bar and the first connection electrode;

The first cell unit and the second cell unit is a method of manufacturing a solar cell comprising at least two or more cell regions in which a plurality of cells are formed, the at least two cell regions are arranged in series with each other.

The method of claim 5,

The first diode and the second diode manufacturing method of a solar cell comprising the disposed in the junction box.

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The method of claim 5,