KR101081222B1

KR101081222B1 - Solar cell aparatus

Info

Publication number: KR101081222B1
Application number: KR1020090054612A
Authority: KR
Inventors: 임진우
Original assignee: 엘지이노텍 주식회사
Priority date: 2009-06-18
Filing date: 2009-06-18
Publication date: 2011-11-07
Also published as: KR20100136314A

Abstract

A photovoltaic device is disclosed. The solar cell apparatus includes a substrate; A first electrode layer disposed on the substrate; A light absorbing layer disposed on the first electrode layer and having a groove formed therein; A window layer disposed on the light absorbing layer; A second electrode corresponding to the groove and disposed on the window layer; And a third electrode extending from the second electrode. The solar cell apparatus reduces the overall resistance and improves the efficiency by the second electrode and the third electrode.

PV system, grid, electrodes, window, CIGS

Description

Solar Power Plant {SOLAR CELL APARATUS}

Embodiments relate to a photovoltaic device.

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 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.

The electrical properties of each layer of these solar cells can affect the efficiency of the overall solar cell.

Embodiments provide a photovoltaic device having improved efficiency.

Photovoltaic device according to one embodiment includes a substrate; A first electrode layer disposed on the substrate; A light absorbing layer disposed on the first electrode layer and having a groove formed therein; A window layer disposed on the light absorbing layer; A second electrode corresponding to the groove and disposed on the window layer; And a third electrode extending from the second electrode.

Photovoltaic device according to one embodiment includes a substrate; And a cell disposed on the substrate, the cell comprising an active region for converting sunlight into electrical energy and an inactive region adjacent to the active region, wherein the cell is disposed on the substrate. 1 electrode; A light absorbing part disposed on the first electrode; A window disposed on the light absorbing portion; And a second electrode in direct contact with an upper surface of the window and disposed in the inactive region.

The solar cell apparatus according to the embodiment includes not only the window layer but also a second electrode and a third electrode. That is, the second electrode and the third electrode may directly contact the window layer, thereby assisting the electrical characteristics of the window layer.

That is, the solar cell apparatus according to the embodiment may improve the overall electrical characteristics by the second electrode and the third electrode, and may have improved efficiency.

In addition, since the second electrode and the third electrode can compensate for the electrical properties of the window layer, the window layer can have improved optical properties while having low electrical properties.

That is, the photovoltaic device according to the embodiment has a window layer having a high light transmittance, and more light can be incident on the light absorbing layer. At this time, according to the embodiment, the electrical characteristics of the solar cell apparatus are not reduced, but may be further improved.

In addition, the second electrode and the third electrode may be formed of a material having a very low specific resistance. That is, the second electrode and the third electrode have a low specific resistance, but may be made of silver, aluminum, copper, or the like, which is an opaque material.

At this time, since the second electrode and the third electrode have a very narrow planar area with respect to the planar area of the entire cell, the influence of the second electrode and the third electrode on the incident rate is insignificant. On the other hand, as described above, since the second electrode and the third electrode have a very low specific resistance, the electrical characteristics can be effectively improved.

In addition, since the second electrode is disposed in the inactive region, even if the second electrode is opaque, it does not affect the photoelectric conversion efficiency.

Therefore, the solar cell apparatus according to the embodiment has a high incident rate, improved electrical characteristics, and improved photoelectric conversion efficiency.

In the description of the embodiments, each substrate, film, electrode, groove, or layer is described as being formed "on" or "under" of each substrate, electrode, film, groove, or layer. In the case, “on” and “under” include both being formed “directly” or “indirectly” 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 photovoltaic device according to an embodiment. FIG. 2 is an enlarged view of portion A of FIG. 1. FIG. 3 is a cross-sectional view taken along the line BB ′ in FIG. 2.

1 to 3, the photovoltaic device includes a support substrate 100, a back electrode layer 200, a light absorbing layer 310, a buffer layer 320, a high resistance buffer layer 330, a window layer 400, The connection part 500 and the grid electrode 600 are included.

The support substrate 100 has a plate shape, and the back electrode layer 200, the light absorbing layer 310, the buffer layer 320, the high resistance buffer layer 330, the window layer 400, and the connection portion ( 500 and the grid electrode 600.

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.

A first through hole TH1 is formed in the back electrode layer 200. The first through hole TH1 is an open area that exposes an upper surface of the support substrate 100. The first through hole TH1 may have a shape extending in one direction when viewed in a plan view.

The back electrode layer 200 is divided into a plurality of back electrodes 210 by the first through groove TH1. That is, the back electrodes 210 are defined by the first through groove TH1.

The back electrodes 210 are spaced apart from each other by the first through hole TH1. The back electrodes 210 are arranged in a stripe shape.

Alternatively, the back electrodes 210 may be arranged in a matrix form. In this case, the first through hole TH1 may be formed in a lattice form when viewed in a plan view.

The light absorbing layer 310 is disposed on the back electrode layer 200. In addition, the material included in the light absorbing layer 310 is filled in the first through hole (TH1).

The light absorbing layer 310 includes a group I-III-VI compound. For example, the light absorbing layer 310 may be formed of a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) crystal structure, copper-indium-selenide-based, or copper-gallium-selenide It may have a system crystal structure.

The energy band gap of the light absorbing layer 310 may be about 1 eV to 1.8 eV.

The buffer layer 320 is disposed on the light absorbing layer 310. The buffer layer 320 includes cadmium sulfide (CdS), and the energy band gap of the buffer layer 320 is about 2.2 eV to 2.4 eV.

The high resistance buffer layer 330 is disposed on the buffer layer 320. The high resistance buffer layer 330 includes zinc oxide (i-ZnO) that is not doped with impurities. The energy band gap of the high resistance buffer layer 330 is about 3.1 eV to 3.3 eV.

A second through hole TH2 is formed in the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330. The second through hole TH2 penetrates the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330. In addition, the second through hole TH2 is an open area exposing the top surface of the back electrode layer 200.

In addition, the light absorbing layer 310 defines a plurality of light absorbing portions 311 by the second through hole TH2. That is, the light absorbing layer 310 is divided into the light absorbing portions 311 by the second through hole TH2.

Similarly, the buffer layer 320 is defined as a plurality of buffers 321 by the second through hole TH2, and the high resistance buffer layer 330 is defined by the second through groove TH2. High resistance buffers 331.

The window layer 400 is disposed on the high resistance buffer layer 330. The window layer 400 is transparent and is a conductive layer. In addition, the resistance of the window layer 400 is higher than the resistance of the back electrode layer 200. For example, the resistance of the window layer 400 may be about 10 to 200 times greater than the resistance of the back electrode layer 200. Examples of the material used as the window layer 400 may include Al doped ZnO (AZO) doped with aluminum.

A third through hole TH3 is formed in the window layer 400. The third through hole TH3 is an open area that exposes the top surface of the back electrode layer 200.

The window layer 400 is divided into a plurality of windows 410 by the third through hole TH3. That is, the windows 410 are defined by the third through hole TH3.

The windows 410 have a shape corresponding to the back electrodes 210. That is, the windows 410 are arranged in a stripe shape. Alternatively, the windows 410 may be arranged in a matrix form.

In addition, a plurality of cells C1, C2... Are defined by the third through hole TH3. That is, the photovoltaic device according to the embodiment is divided into the cells C1, C2... By the third through hole TH3.

The first through hole TH1, the second through hole TH2, and the third through hole TH3 have a shape extending in a first direction. Accordingly, the cells C1, C2... Also have a shape extending in the first direction.

The connection part 500 extends downward from the window layer 400 and directly contacts the back electrode layer 200. For example, the connection part 500 extends downward from a window of a specific cell and is connected to the back electrode of an adjacent cell.

Accordingly, the connection part 500 connects the window and the back electrode included in the cells C1, C2 ... adjacent to each other.

The connection part 500 is integrally formed with the windows 410. That is, the material used as the connection part 500 is the same as the material used as the window layer 400.

In addition, the connection part 500 is in contact with side and top surfaces of the back electrodes 210. The connection part 500 penetrates through the light absorbing layer 310 and is connected to the back electrode layer 200. That is, the connection part 500 is disposed inside the first through hole TH1 and TH2.

The grid electrode 600 is disposed on the window layer 400. In more detail, the grid electrode 600 is in direct contact with the upper surface of the window layer 400. The grid electrode 600 is opaque and is a conductor. The grid electrode 600 may be made of a material having a very low specific resistance.

For example, the material forming the grid electrode 600 may be a metal having a much lower specific resistance than the material forming the window layer 400. Examples of the material used for the grid electrode 600 include copper, aluminum, silver and alloys thereof.

The grid electrode 600 includes a first grid electrode 610 and a second grid electrode 620.

The first grid electrode 610 is disposed on the window layer 400. The first grid electrode 610 is in direct contact with the upper surface of the window layer 400. The first grid electrode 610 extends in the first direction.

The first grid electrode 610 is disposed adjacent to the third through hole TH3 and corresponding to the second through hole TH2 and / or the first through hole TH1. That is, the first grid electrode 610 is disposed on the second through hole TH2 and / or the first through hole TH1.

In addition, the first grid electrode 610 extends along the second through hole TH2 and / or the first through hole TH1. Similarly, the first grid electrode 610 corresponds to the connection part 500 and extends along the connection part 500.

In the first grid electrode 610, an area in which solar light is not converted into electrical energy is disposed in the inactive area NAR.

The first through hole TH1, the second through hole TH2, and the third through hole TH3 are dead zones that do not perform a function of converting sunlight into electrical energy. That is, the area from the first through hole TH1 to the third through hole TH3 is an inactive region NAR.

The inactive region NAR has a shape extending in the first direction when viewed in plan.

The width W1 of the first grid electrode 610 may be about 0.01 mm to about 0.5 mm, and the thickness T1 of the first grid electrode 610 may be about 0.03 mm to about 1 mm.

1 to 3, the side surface of the first grid electrode 610 may be disposed on the same plane as the side surface of the window 410. That is, the side surface of the first grid electrode 610 may be disposed on the same plane as the inner surface of the third through hole TH3.

The second grid electrode 620 extends from the first grid electrode 610. In more detail, the second grid electrode 620 extends in a second direction crossing the first direction. For example, the first grid electrode 610 and the second grid electrode 620 may be perpendicular to each other.

A plurality of second grid electrodes 620 may extend from one first grid electrode 610. In this case, an interval D of each second grid electrode 620 may be about 5 mm to about 100 mm.

The second grid electrode 620 is disposed on the window layer 400 and directly contacts the window layer 400. The width W2 of the second grid electrode 620 may be about 0.01 mm to about 0.5 mm, and the thickness T2 of the second grid electrode 620 may be about 0.03 mm to about 1 mm.

The second grid electrode 620 is disposed in the active region AR. In addition, current flows in the cells C1, C2... In the second direction, and the second grid electrode 620 may extend in the direction in which the current flows.

The first grid electrode 610 and the second grid electrode 620 may be integrally formed.

Photovoltaic device according to the embodiment includes a plurality of cells (C1, C2 ...) disposed on the support substrate 100. Each cell C1, C2... Includes a back electrode 210, a light absorbing portion 311, a buffer 321, a high resistance buffer 331, a window 410, and a grid electrode 600. .

The back electrode 210 is disposed on the support substrate 100, and the light absorbing part 311 is disposed on the back electrode 210. The buffer 321 is disposed on the light absorbing part 311, and the high resistance buffer 331 is disposed on the buffer 321. The window 410 is disposed on the high resistance buffer 331.

The grid electrode 600 is disposed on the window 410 and directly contacts the top surface of the window 410.

In particular, the first grid electrode 610 is disposed in one outer region of the window 410, and the second grid electrode 620 extends to the outer outer region of the window 410. In this case, the plurality of second grid electrodes 620 may extend from one first grid electrode 610.

The grid electrode 600 may directly contact the window layer 400 to assist electrical characteristics of the window layer 400. That is, the solar cell apparatus according to the embodiment may improve the overall electrical characteristics by the grid electrode 600, it may have an improved efficiency.

In particular, since the grid electrode 600 compensates for the electrical characteristics of the window layer 400, the window layer 400 may have an improved optical characteristic even though the window layer 400 has a low electrical characteristic.

That is, as the thickness of the window layer 400 becomes thin, the photovoltaic device according to the embodiment has a high light transmittance. However, as the thickness of the window layer 400 becomes thinner, the resistance of the window layer 400 may increase. In this case, the grid electrode 600 compensates for the resistance characteristics of the window layer 400, so that the resistance of the window layer 400 and the grid electrode 600 as a whole becomes low.

Therefore, the solar cell apparatus according to the embodiment can realize a high light transmittance without deteriorating the electrical characteristics.

That is, the solar cell apparatus according to the embodiment can inject more light into the light absorbing layer. At this time, according to the embodiment, the electrical characteristics of the solar cell apparatus are not reduced, but may be further improved.

In addition, even though the grid electrode 600 is opaque, since the grid electrode 600 has a very small planar area with respect to the planar area of the entire cell, the effect of the grid electrode 600 on the incident rate of sunlight is minimal. However, as described above, since the material forming the grid electrode 600 has a very low specific resistance, the grid electrode 600 may effectively improve electrical characteristics.

In addition, the grid electrode 600 has a high electron collecting ability, and improves the photocurrent density of the photovoltaic device according to the embodiment.

In addition, since the first grid electrode 610 is disposed in the inactive region NAR, even if the first grid electrode 610 is opaque, it does not affect the photoelectric conversion efficiency.

4 to 7 are cross-sectional views illustrating a method of manufacturing the solar cell apparatus according to the embodiment. For a description of the present manufacturing method, refer to the description of the photovoltaic device 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 a first through hole TH1. Accordingly, a plurality of back electrodes 210 are formed on the substrate. The back electrode layer 200 is patterned by a laser.

The first through hole TH1 exposes an upper surface of the support substrate 100 and has a width of about 10 μm to 100 μm.

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 hole TH1 exposes an upper surface of the additional layer.

Referring to FIG. 5, the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330 are sequentially formed on the back electrode layer 200.

The light absorbing layer 310 may be formed by a sputtering process or an evaporation method.

For example, copper, indium, gallium, selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) while evaporating copper, indium, gallium, and selenium simultaneously or separately to form the light absorbing layer 310. The method of forming the light absorbing layer 310 and the method of forming the metal precursor film and then forming it by the selenization process are widely used.

When the metal precursor film is formed and selenization is subdivided, 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.

Thereafter, the metal precursor film is formed of a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) light absorbing layer 310 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 light absorbing layer 310 may be formed by a sputtering process and a selenization process using only a copper target and an indium target, or using a copper target and a gallium target.

Thereafter, cadmium sulfide is deposited on the light absorbing layer 310 by a sputtering process, and the buffer layer 320 is formed.

Thereafter, zinc oxide is deposited on the buffer layer 320 by a sputtering process, and the high resistance buffer layer 330 is formed.

Thereafter, a portion of the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330 is removed to form a second through hole TH2. The second through hole TH2 penetrates the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330.

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

For example, the light absorbing layer 310, the buffer layer 320, and the high resistance buffer layer 330 may be patterned by a tip having a width of about 40 μm to about 180 μm. In addition, the second through hole TH2 may be formed by a laser having a wavelength of about 200 to 600 nm.

Referring to FIG. 6, a window layer 400 is formed on the high resistance buffer layer 330. In this case, a material forming the window layer 400 is filled in the first through hole TH1 and the second through hole TH2.

In order to form the window layer 400, a transparent conductive material is stacked on the high resistance buffer layer 330. The transparent conductive material is filled in the entire second through hole TH2. Examples of the transparent conductive material include aluminum doped zinc oxide and the like.

Thereafter, a portion of the window layer 400 is removed to form a third through hole TH3. That is, the window layer 400 is patterned to define a plurality of windows 410 and a plurality of cells C1, C2...

Referring to FIG. 7, a grid electrode 600 is formed on the window layer 400.

In order to form the grid electrode 600, a paste including conductive particles is printed on the window layer 400. The conductive particles may be, for example, copper particles, silver particles, or aluminum particles.

In addition, the paste may be printed by silkscreen printing.

Alternatively, the grid electrode 600 may be formed by a vacuum deposition process.

For example, a mask is disposed on the window layer 400. Thereafter, a conductive material may be selectively deposited on the window layer 400 by the mask to form the grid electrode 600.

In this case, the conductive material may be deposited by a sputtering process or an evaporation method.

As described above, the manufacturing method of the solar cell apparatus according to the embodiment may provide the solar cell apparatus having the improved photoelectric conversion efficiency by the grid electrode 600.

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 is a plan view illustrating a photovoltaic device according to an embodiment.

FIG. 2 is an enlarged view of portion A of FIG. 1.

FIG. 3 is a cross-sectional view taken along the line BB ′ in FIG. 2.

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

Claims

Board;

A first electrode layer disposed on the substrate;

A light absorbing layer disposed on the first electrode layer and having a groove formed therein;

A window layer disposed on the light absorbing layer;

A second electrode corresponding to the groove and disposed on the window layer; And

A third electrode extending from the second electrode,

The groove extends in the first direction,

The second electrode extends in the first direction,

The third electrode extends in a second direction crossing the first direction.

delete

The solar cell apparatus of claim 1, wherein the third electrode has a width of 0.01 mm to 0.5 mm.

The solar cell apparatus of claim 1, wherein the second electrode and the third electrode are in direct contact with the window layer.

The solar cell apparatus of claim 1, wherein the second electrode and the third electrode comprise copper, aluminum, or silver.

The method of claim 1, further comprising a connection portion extending from the window layer, disposed inside the groove, and connected to the first electrode layer.

The second electrode corresponds to the connection unit.

Board; And

A cell disposed on the substrate,

The cell includes an active region for converting sunlight into electrical energy and an inactive region adjacent to the active region,

The cell is

A first electrode disposed on the substrate;

A light absorbing part disposed on the first electrode;

A window disposed on the light absorbing portion; And

And a second electrode in direct contact with an upper surface of the window and disposed in the inactive region.

The photovoltaic device of claim 7, comprising a plurality of third electrodes extending from the second electrode and disposed in the active region.

The solar cell apparatus of claim 8, wherein the third electrodes are disposed in parallel with each other, and the spacing between the third electrodes is 5 mm to 100 mm.