KR101592582B1 - Solar cell and method of fabircating the same - Google Patents

Solar cell and method of fabircating the same Download PDF

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Publication number
KR101592582B1
KR101592582B1 KR1020090100438A KR20090100438A KR101592582B1 KR 101592582 B1 KR101592582 B1 KR 101592582B1 KR 1020090100438 A KR1020090100438 A KR 1020090100438A KR 20090100438 A KR20090100438 A KR 20090100438A KR 101592582 B1 KR101592582 B1 KR 101592582B1
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South Korea
Prior art keywords
layer
window
window layer
hole
rear electrode
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KR1020090100438A
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Korean (ko)
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KR20110043358A (en
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박희선
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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

A solar cell according to an embodiment includes: a rear electrode layer, a light absorbing layer, and a buffer layer stacked on a substrate; A through hole penetrating the light absorption layer and the buffer layer and selectively exposing the rear electrode layer; A first window layer disposed on the buffer layer and having a first conductivity; And a second window layer disposed on the first window layer and having a second conductivity lower than the first conductivity.

Solar cell, electrode layer

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solar cell,

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

As energy demand has increased in recent years, development of solar cells that convert solar energy into electrical energy is underway.

Particularly, a CIGS-based 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 light absorbing layer, a high resistance buffer layer, and an n-type window layer is widely used.

Such a solar cell can affect the efficiency of the entire solar cell by the electrical characteristics of each layer.

Embodiments provide a solar cell having improved efficiency and a method of manufacturing the same.

A solar cell according to an embodiment includes: a rear electrode layer, a light absorbing layer, and a buffer layer stacked on a substrate; A through hole penetrating the light absorption layer and the buffer layer and selectively exposing the rear electrode layer; A first window layer disposed on the buffer layer and having a first conductivity; And a second window layer disposed on the first window layer and having a second conductivity lower than the first conductivity.

A method of fabricating a solar cell according to an embodiment includes sequentially forming a back electrode layer, a light absorbing layer, and a buffer layer on a substrate; Forming a through hole through the light absorption layer and the buffer layer to expose the rear electrode layer; Forming a first window layer having a first conductivity on the buffer layer; And forming a second window layer having a second conductivity lower than the first conductivity on the first window layer.

According to the embodiment, the front electrode of the solar cell may be formed as a double structure in which the first window layer and the second window layer are laminated.

In particular, the lower first window layer may have lower resistance and higher conductivity than the second window layer.

Thus, the contact resistance between the connection wiring extending in the first window layer and the rear electrode layer is reduced, and the current mobility can be improved.

Particularly, since the connection wiring and the rear electrode layer have the ITO-MO junction, resistance due to interfacial corrosion prevention can be reduced.

Thus, the electrical characteristics of the solar cell can be improved.

The ITO layer has a low resistance and a low deterioration due to moisture.

Accordingly, the sheet resistance of the second window layer can be reduced by the first window layer, deterioration due to moisture can be prevented, and the performance of the solar cell can be improved.

In the description of the embodiments, in the case where each substrate, layer, film or electrode is described as being formed "on" or "under" of each substrate, layer, film, , "On" and "under" all include being formed "directly" or "indirectly" through "another element". 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.

Referring to Figs. 1 to 7, a solar cell and a method for manufacturing the same will be described in detail.

Referring to FIG. 1, a rear electrode layer 200 is formed on a substrate 100.

The substrate 100 may be glass, and a ceramic substrate, a metal substrate, a polymer substrate, or the like may be used.

For example, sodalime galss or high strained point soda glass can be used as the glass substrate. As the metal substrate, a substrate including stainless steel or titanium can be used. As the polymer substrate, polyimide may be used.

The substrate 100 may be transparent. The substrate 100 may be rigid or flexible.

The rear electrode layer 200 may be formed of a conductive material such as a metal.

For example, the rear electrode layer 200 may be formed by a sputtering process using molybdenum (Mo) as a target.

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

The molybdenum thin film as the rear electrode layer 200 should have a low resistivity as an electrode and should have excellent adhesiveness to the substrate 100 to prevent peeling due to a difference in thermal expansion coefficient.

For example, the rear electrode layer 200 may be formed to a thickness of 1000 nm ± 100.

Meanwhile, the material for forming the rear electrode layer 200 is not limited thereto, and may be formed of molybdenum (Mo) doped with sodium (Na) ions.

Although not shown in the drawing, the rear electrode layer 200 may be formed of at least one layer. When the rear electrode layer 200 is formed of a plurality of layers, the layers constituting the rear electrode layer 200 may be formed of different materials.

A first through hole P1 may be formed in the rear electrode layer 200 and a plurality of the rear electrode layer 200 may be patterned.

The first through hole P1 may selectively expose an upper surface of the substrate 100. [

For example, the first through hole P1 may be patterned by a mechanical device or a laser device. The width of the first through hole P1 may be 80 占 퐉 占 20.

The rear electrode layer 200 may be arranged in a stripe form or a matrix form by the first through hole P1 and may correspond to each cell.

Meanwhile, the rear electrode layer 200 is not limited to the above-described embodiment, but may be formed in various shapes.

Referring to FIG. 2, a light absorption layer 300 is formed on the rear electrode layer 200 including the first through hole P1.

The light absorption layer 300 includes a compound of the formula Ib-IIIb-VIb.

More specifically, the light absorption layer 300 includes a copper-indium-gallium-selenide (Cu (In, Ga) Se 2 , CIGS) compound.

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

For example, a CIG-based metal precursor (not shown) may be formed on the rear electrode layer 200 and the first through hole P1 using a copper target, an indium target, and a gallium target to form the light absorption layer 300. [ ) Film is formed.

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

The light absorption layer 300 may be formed by co-evaporation of copper, indium, gallium, selenide (Cu, In, Ga, Se).

For example, the light absorption layer 300 may be formed to a thickness of about 2000 +/- 500 nm.

The light absorption layer 300 receives external light and converts it into electric energy. The photoabsorption layer 300 generates a photoelectromotive force by a photoelectric effect.

Referring to FIG. 3, a buffer layer 400 and a high-resistance buffer layer 500 are formed on the light absorption layer 300.

The buffer layer 400 may be formed of at least one layer on the light absorption layer 300. The buffer layer 400 may be formed of cadmium sulfide (CdS) by chemical bath deposition (CBD).

For example, the buffer layer 400 may be formed to a thickness of about 50 ± 10 nm.

At this time, the buffer layer 400 is an n-type semiconductor layer and the light absorption layer 300 is a p-type semiconductor layer. Accordingly, the light absorption layer 300 and the buffer layer 400 form a pn junction.

The high resistance buffer layer 500 may have a transparent electrode layer formed on the buffer layer.

For example, the high-resistance buffer layer 500 may be formed of any one of ITO, ZnO, and i-ZnO.

The high resistance buffer layer 500 may be formed of a zinc oxide layer by performing a sputtering process using zinc oxide (ZnO) as a target.

For example, the high resistance buffer layer 500 may be formed to a thickness of about 50 ± 10 nm.

The buffer layer 400 and the high-resistance buffer layer 500 are disposed between the light absorption layer 300 and a 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 absorption layer 300 and the front electrode, the buffer layer 400 and the high resistance buffer layer 500 having the bandgap between the two materials are inserted, Junctions can be formed.

In this embodiment, two buffer layers 400 and 500 are formed on the light absorbing layer 300. However, the present invention is not limited to this, and the buffer layer may be formed as a single layer.

Referring to FIG. 4, a second through hole P2 is formed through the high resistance buffer layer 500, the buffer layer 400, and the light absorbing layer 300. Referring to FIG.

The second through hole P2 may selectively expose the rear electrode layer 200. [

The second through hole P2 may be formed adjacent to the first through hole P1.

The second through hole P2 may be formed through a mechanical scribing process using a tip.

For example, the width of the second through-hole P2 may be 80 占 퐉 20 and the gap between the second through-hole P2 and the first through-hole P1 may be 80 占 퐉 20.

Referring to FIG. 5, a transparent conductive material is laminated on the high-resistance buffer layer 500, and a first window layer 600 is formed.

When the first window layer 600 is formed, the transparent conductive material may be inserted into the second through hole P2 to form the connection wiring 700. [

The first window layer 600 may be formed of indium tin oxide (ITO).

The first window layer 600 may be formed through a sputtering process.

For example, the first window layer 600 may have a thickness of about 10 to 200 nm.

Also, the second window layer 800 may have a sheet resistance of about 0.1 to 0.2? / ?, and a transmittance of 80 to 95%.

When the first window layer 600 is formed, the transparent conductive material may be formed in the second through hole P2 and the connection wiring 700 may be formed.

Since the connection wiring 700 can be formed of an ITO material, contact resistance with the rear electrode layer 200 can be improved.

This is because ITO, which is a material forming the first window layer 600, has a high conductivity.

Referring to FIG. 6, a second window layer 800 is formed by laminating a transparent conductive material on the first window layer 600.

The second window layer 800 is formed of zinc oxide doped with aluminum (Al) or alumina (Al 2 O 3 ) through a sputtering process.

For example, the second window layer 800 may have a thickness of 800 nm ± 100, and may have a sheet resistance of about 0.2 to 0.5 Ω / □ and a transmittance of 80 to 95%.

The second window layer 800 is an n-type window layer that forms a pn junction with the light absorbing layer 300. The second window layer 800 functions as a transparent electrode on the entire surface of the solar cell. Therefore, zinc oxide (ZnO) .

Therefore, by doping the zinc oxide with aluminum or alumina, an electrode having a low resistance value can be formed.

In particular, since the second window layer 800 is formed on the first window layer 600, the interface characteristics can be improved.

The zinc oxide thin film, which is the second window layer 800, may be formed by a method of depositing using a ZnO target by an RF sputtering method, a reactive sputtering method using a Zn target, and an organic metal chemical vapor deposition method.

As described above, the front electrode of the solar cell is formed in a double structure in which the first window layer 600 and the second window layer 800 are stacked, and the electrical characteristics of the solar cell can be improved.

ITO, which is the first window layer 600, may have lower resistance and higher conductivity than the second window layer 800, which is an aluminum-doped zinc oxide layer.

For example, the first window layer 600 may have a first conductivity and the second window layer 800 may have a second conductivity lower than the first conductivity.

Accordingly, the contact resistance between the connection wiring 700 extending from the first window layer 600 and the rear electrode layer 200 can be reduced, and the current mobility can be improved.

Further, since the Mo-ITO junction is formed by the connection wiring 700, the resistance due to the prevention of interfacial corrosion can be reduced, and the electrical characteristics of the solar cell can be improved.

The ITO layer has a low resistance and a low deterioration due to moisture.

Accordingly, the sheet resistance of the second window layer 800 can be reduced by the first window layer 600, deterioration due to moisture can be prevented, and the performance of the solar cell can be improved.

Also, the second window layer 800 may be formed to have a small thickness by the first window layer 600 having a high conductivity.

That is, as the thickness of the second window layer 800 decreases, the incident rate of sunlight can be improved.

Referring to FIG. 7, a third through hole P3 is formed through the first and second window layers 600 and 800, the high resistance buffer layer 500, the buffer layer 400, and the light absorbing layer 300.

The third through hole (P3) may selectively expose the rear electrode layer (200).

The third through hole P3 may be formed adjacent to the second through hole P2.

For example, the width of the third through-hole P3 may be 80 占 퐉 20 and the gap between the third through-hole P3 and the second through-hole P2 may be 80 占 퐉 20.

The third through hole P3 may be formed by a laser or a mechanical method such as a tip.

The light absorption layer 300, the buffer layer 400, the high resistance buffer layer 500 and the first and second window layers 800 can be separated by the cells C1 and C2 by the third through holes P3. have.

The light absorption layer 300, the buffer layer 400, the high resistance buffer layer 500 and the first and second window layers 600 and 800 are arranged in a stripe form or a matrix form by the third through hole P3 . The third through-hole P3 is not limited to the above-described embodiment, but may be formed in various forms.

At this time, the cells C 1 and C 2 may be connected to each other by the connection wiring 700. That is, the connection wiring 700 can physically and electrically connect the first and second window layers 600 and 800 with the rear electrode layer 200 of adjacent cells.

As described above, the window layer serving as the front electrode of the solar cell is formed in a double structure, and the electrical characteristics of the solar cell can be improved.

Particularly, since the window layer located at the lower portion has a high conductivity, the bonding property with the rear electrode layer can be improved.

Thus, the electrical characteristics of the solar cell can be improved.

Therefore, the electrical characteristics of the solar cell can be improved.

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 variations 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.

1 to 7 are views showing a manufacturing process of a solar cell according to an embodiment.

Claims (7)

A back electrode layer, a light absorbing layer and a buffer layer stacked on a substrate; A through hole penetrating the light absorption layer and the buffer layer and selectively exposing the rear electrode layer; A connection wiring inserted into the through hole; A first window layer disposed on the buffer layer and having a first conductivity; And And a second window layer disposed on the first window layer and having a second conductivity lower than the first conductivity, The connection wiring and the first window layer are integrally formed, The connection wiring extends in the first window layer and is directly connected to the rear electrode layer through the through hole, The connection wiring and the first window layer are transparent conductive materials, Wherein the connection wiring and the first window layer have lower resistances than the second window layer. delete The method according to claim 1, Wherein the first window layer is formed of indium tin oxide (ITO), and the second window layer is formed of zinc oxide doped with aluminum (Al) or alumina (Al 2 O 3 ). The method according to claim 1, Wherein the first window layer and the second window layer have a thickness of 1: 2 to 5. Forming a rear electrode layer on the substrate; Forming a first through-hole on the rear electrode layer so that an upper surface of the substrate is selectively exposed; Sequentially forming a light absorption layer, a buffer layer, and a high-resistance buffer layer on the rear electrode layer including the first through-hole; Forming a second through hole through the light absorbing layer, the buffer layer, and the high resistance buffer layer so that the rear electrode layer is selectively exposed; Forming a first window layer having a first conductivity on the high-resistance buffer layer; Forming a connection wiring by forming the first window layer in the second through hole when the first window layer is formed; And Forming a second window layer having a second conductivity lower than the first conductivity on the first window layer, Forming a third through hole through the light absorption layer, the buffer layer, the high resistance buffer layer, the first window layer, and the second window layer so that the rear electrode layer is selectively exposed; . delete 6. The method of claim 5, Wherein the first window layer is formed of indium tin oxide (ITO), and the second window layer is formed of zinc oxide doped with aluminum (Al) or alumina (Al 2 O 3 ) .
KR1020090100438A 2009-10-21 2009-10-21 Solar cell and method of fabircating the same KR101592582B1 (en)

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KR101091361B1 (en) 2010-07-30 2011-12-07 엘지이노텍 주식회사 Solar cell apparatus and method of fabricating the same
KR101338845B1 (en) * 2011-11-29 2013-12-09 엘지이노텍 주식회사 Solar cell module and method of fabricating the same
KR101326970B1 (en) * 2011-11-29 2013-11-13 엘지이노텍 주식회사 Solaa cell and solaa cell module using the same

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Publication number Priority date Publication date Assignee Title
JP2005191167A (en) * 2003-12-25 2005-07-14 Showa Shell Sekiyu Kk Integrated thin film solar cell and its manufacturing method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005191167A (en) * 2003-12-25 2005-07-14 Showa Shell Sekiyu Kk Integrated thin film solar cell and its manufacturing method

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