KR101081143B1

KR101081143B1 - Solar cell and method of fabricating the same

Info

Publication number: KR101081143B1
Application number: KR1020090056760A
Authority: KR
Inventors: 조호건
Original assignee: 엘지이노텍 주식회사
Priority date: 2009-06-25
Filing date: 2009-06-25
Publication date: 2011-11-07
Also published as: KR20100138300A

Abstract

According to an exemplary embodiment, a solar cell includes a plurality of back electrode patterns spaced apart from each other on a substrate, a light absorbing layer pattern having contact patterns and separation patterns formed on the substrate on which the back electrode patterns are disposed, and a light absorbing layer pattern formed on the light absorbing layer. And a front electrode pattern disposed to be spaced apart from the separation pattern, wherein the contact pattern is formed to expose an upper portion of the substrate and the rear electrode pattern, and the front electrode pattern formed in the contact pattern is formed of the substrate and the rear electrode pattern. It includes contact with.

Solar cell

Description

SOLAR CELL 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, 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 addition, as the photoelectric conversion efficiency of solar cells is improved, many solar power generation systems with photovoltaic modules have been installed outside of commercial buildings as well as in residential applications.

In order to improve the performance of such a solar cell, researches for improving the light receiving efficiency are in progress, and the appearance and display function of the solar cell are also important.

The embodiment provides a solar cell and a method of manufacturing the same that can control a transmission region of the solar cell.

A solar cell according to an embodiment includes a plurality of back electrode patterns spaced apart from each other on a substrate, a light absorbing layer pattern having contact patterns and separation patterns formed on the substrate on which the back electrode patterns are disposed, and a light absorbing layer pattern on the light absorbing layer. And a front electrode pattern disposed to be spaced apart from the separation pattern, wherein the contact pattern is formed to expose an upper portion of the substrate and the rear electrode pattern, and the front electrode pattern formed in the contact pattern is formed of the substrate and the rear electrode pattern. It includes contact with.

According to an embodiment of the present invention, a method of manufacturing a solar cell includes forming a plurality of rear electrode patterns spaced apart from each other on a substrate, and forming a light absorbing layer including a contact pattern on the substrate on which the rear electrode patterns are disposed. And forming a front electrode on the light absorbing layer, and then forming a separation pattern to form a front electrode pattern spaced apart from the separation pattern, wherein the contact pattern includes a substrate and a rear electrode pattern. An upper portion of the upper portion is formed to expose the front electrode pattern formed in the contact pattern includes contact with the substrate and the rear electrode pattern.

The solar cell and the method of manufacturing the same according to the embodiment are formed such that the width P2 of the contact pattern overlaps a part of the width P1 of the rear electrode pattern, thereby easily adjusting the transmission region of the solar cell.

That is, the width P1 of the rear electrode pattern is sufficiently wide, and then the width P2 of the contact pattern is adjusted to form as many transmission regions as desired.

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.

6 is a side cross-sectional view illustrating a solar cell according to an embodiment.

The solar cell according to the embodiment includes a back electrode pattern 200, a light absorbing layer 300, and a front electrode 500 formed on the substrate 100.

The back electrode patterns 200 are spaced apart from each other on the substrate 100.

The light absorbing layer 300 includes a contact pattern 310 and a separation pattern 320, and the contact pattern 310 is formed to connect the electrodes of the rear electrode pattern 200 and the front electrode 500. The separation pattern 320 is formed to divide into unit cells.

The front electrode 500 is inserted into the contact pattern 310 to be electrically connected to the back electrode pattern 200, and a part of the front electrode 500 inserted into the contact pattern 310 is formed on the substrate ( 100).

In addition, a portion of the light absorbing layer 300 and a portion of the front electrode 500 are disposed between the rear electrode pattern 200 to be in contact with the substrate 100.

A more detailed description of the solar cell of the present embodiment will be described together with the manufacturing method of the solar cell.

1 to 6 are cross-sectional views illustrating a method of manufacturing a solar cell according to an 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.

Subsequently, as shown in FIG. 2, 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.

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

At this time, by adjusting the width (P1) between the back electrode pattern 200, it is possible to adjust the transmission region of the solar cell.

As shown in FIG. 3, the light absorbing layer 300 and the 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. It can be formed as.

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.

Next, as shown in FIG. 4, a contact pattern 310 penetrating the light absorbing layer 300 and the buffer layer 400 is formed.

The contact pattern 310 may be formed by irradiating a laser or by a mechanical method, and a portion of the back electrode pattern 200 and the substrate 100 are exposed.

That is, the width P1 of the back electrode pattern 200 and the width P2 of the contact pattern 310 may overlap each other to expose the substrate 100.

In this case, the width P1 of the back electrode pattern 200 and the width P2 of the contact pattern 310 may overlap each other, thereby reducing a dead area other than the cell area.

One back electrode pattern 200 may be exposed on the contact pattern 310.

In addition, the width P2 of the contact pattern 310 may be adjusted to control the transmission region of the solar cell.

In this case, the width P2 of the contact pattern 310 is formed to overlap a part of the width P1 of the back electrode pattern 200, thereby easily adjusting the transmission region of the solar cell.

That is, the width P1 of the back electrode pattern 200 may be sufficiently wide, and then the width P2 of the contact pattern 310 may be adjusted to form as many transmission regions as desired.

As shown in FIG. 5, the 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.

In this case, the connection wiring 700 may be formed to contact the substrate 100, and a part of the connection wiring 700 and a part of the light absorbing layer 300 are interposed between the back electrode pattern 200. Is formed.

That is, a portion of the connection wiring 700 and a portion of the light absorbing layer 300 are formed between the back electrode pattern 200 on the substrate 100 to contact the substrate 100.

The front electrode 500 is formed of zinc oxide doped with aluminum or alumina by a sputtering process on the buffer layer 400.

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.

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 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 thin oxide (ITO) thin film having excellent electro-optic properties is laminated on a zinc oxide thin film may be formed.

Subsequently, as illustrated in FIG. 6, 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 irradiating a laser.

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

In addition, the buffer layer 400 and the light absorbing layer 300 may be arranged in the form of a stripe or a matrix 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 buffer layer 400, and the front electrode 500 are formed by the separation pattern 320.

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 500 of the first cell C1 adjacent to the second cell C2. do.

The solar cell and the method of manufacturing the same according to the embodiments described above are formed such that the width P2 of the contact pattern overlaps a part of the width P1 of the rear electrode pattern, thereby easily adjusting the transmission region 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.

Claims

A plurality of back electrode patterns spaced apart from each other on the substrate;

A light absorbing layer pattern having contact patterns and separation patterns formed on the substrate on which the rear electrode patterns are disposed;

A front electrode pattern disposed on the light absorbing layer and spaced apart from the separation pattern;

The contact pattern is formed to expose the upper portion of the substrate and the back electrode pattern, the front electrode pattern formed in the contact pattern is in contact with the substrate and the back electrode pattern.

The method of claim 1,

The light absorbing layer pattern and the front electrode pattern is disposed between the rear electrode pattern, the solar cell comprising contacting the substrate.

3. The method of claim 2,

The front electrode pattern extends to contact the adjacent front electrode pattern.

Forming a plurality of back electrode patterns spaced apart from each other on the substrate;

Forming a light absorbing layer including a contact pattern on the substrate on which the back electrode pattern is disposed; And

After forming the front electrode on the light absorbing layer, and forming a separation pattern, to form a front electrode pattern spaced apart by the separation pattern,

The contact pattern is formed so that the upper portion of the substrate and the back electrode pattern is exposed, the front electrode pattern formed in the contact pattern is in contact with the substrate and the back electrode pattern manufacturing method of a solar cell.

The method of claim 4, wherein

The light absorbing layer pattern and the front electrode pattern is disposed between the rear electrode pattern, the solar cell manufacturing method comprising contacting the substrate.

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