KR20150131573A - Solar cell - Google Patents

Abstract

A solar cell according to an embodiment includes: a support substrate; A rear electrode layer disposed on the supporting substrate; A light absorbing layer disposed on the rear electrode layer; A buffer layer disposed on the light absorbing layer; And a front electrode layer disposed on the buffer layer, wherein the front electrode layer comprises: a first front electrode layer disposed on the buffer layer; And a second front electrode layer disposed on the first front electrode layer, and the second front electrode layer is disposed in the plurality of pattern units and the pattern units.

Description

Solar cell {SOLAR CELL}

An embodiment relates to a solar cell.

Recently, as energy resources such as petroleum and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

Solar cells (photovoltaic cells or solar cells) are the core elements of solar power generation that convert sunlight directly into electricity.

For example, if sunlight having an energy larger than band-gap energy of a semiconductor is incident on a solar cell made of a pn junction of semiconductors, an electron-hole pair is generated. The electron- (Photovoltage) occurs between pn as the electrons are collected into the n layer and the holes are collected into the p layer. At this time, when the load is connected to the electrodes at both ends, current flows.

A solar cell receives light by an external sun or the like and converts it into electric energy, and electrons in the solar cell can be moved from the rear electrode layer toward the front electrode layer.

At this time, as the electrons moving from the light absorption layer to the front electrode layer are moved only in one direction, there is a problem that the efficiency of the solar cell is lowered due to the loss of electrons generated in the lower part of the light absorption layer.

Therefore, there is a demand for a solar cell having a new structure that can solve such a problem.

The embodiment attempts to provide a solar cell having improved light-to-electricity conversion efficiency.

A solar cell according to an embodiment includes: a support substrate; A rear electrode layer disposed on the supporting substrate; A light absorbing layer disposed on the rear electrode layer; A buffer layer disposed on the light absorbing layer; And a front electrode layer disposed on the buffer layer, wherein the front electrode layer comprises: a first front electrode layer disposed on the buffer layer; And a second front electrode layer disposed on the first front electrode layer, and the second front electrode layer is disposed in the plurality of pattern units and the pattern units.

In the solar cell according to the embodiments, a groove or a pattern portion is formed on the front electrode layer, and a conductive material such as a metal is disposed in the groove or the pattern portion, whereby the path of the electron can be increased.

In the prior art, although the flow of electrons in the solar cell was shifted from the light absorption layer to the front electrode layer only in one direction, in the solar cell according to the embodiments, the conductive material, such as metal, It is possible to increase the electron movement path inside the solar cell.

Accordingly, the solar cell according to the embodiments can reduce the loss due to the movement of electrons generated in the lower portion of the light absorption layer, thereby improving the overall efficiency of the solar cell.

In addition, in the solar cell according to the embodiments, when the supporting substrate has a flexible material such as plastic, the damage of the metal layer disposed on the front electrode layer can be prevented.

That is, a metal layer is arranged in a lattice pattern by forming a pattern portion or a groove on the front electrode layer and arranging a metal layer in the form of a lattice in the pattern portion or the groove. When such a metal layer is formed in the front electrode layer, It is possible to reduce cracks due to bending of the metal layer and the like even when applied to a flexible solar cell. Therefore, when the solar cell according to the embodiments is applied to a flexible solar cell, the overall reliability of the solar cell can be improved.

1 is a plan view showing a solar cell according to an embodiment.
FIG. 2 is a cross-sectional view showing one end surface of a solar cell according to an embodiment.
3 is an enlarged cross-sectional view of a portion A of FIG. 2 according to the first embodiment.
4 is a top view of the front electrode layer according to the first embodiment.
5 is an enlarged cross-sectional view of part A of FIG. 2 according to the second embodiment.
6 is a top view of the front electrode layer according to the second embodiment.
Fig. 7 is an enlarged cross-sectional view of part A of Fig. 2 according to the third embodiment.
8 is a top view of the front electrode layer according to the third embodiment.
9 is a view showing a solar cell module to which the solar cell according to the embodiment is applied.

In the description of the embodiments, it is to be understood that each layer (film), area, pattern or structure may be referred to as being "on" or "under / under" Quot; includes all that is formed directly or through another layer. The criteria for top / bottom or bottom / bottom of each layer are described with reference to the drawings.

The thickness or the size of each layer (film), region, pattern or structure in the drawings may be modified for clarity and convenience of explanation, and thus does not entirely reflect the actual size.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 8, a solar cell according to an embodiment may include a support substrate 100, a rear electrode layer 2000, a light absorption layer 300, a buffer layer 400, and a front electrode layer 500.

The supporting substrate 100 has a plate shape and can support the rear electrode layer 200, the light absorbing layer 300, the buffer layer 400, and the front electrode 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. More specifically, the support substrate 100 may be a soda lime glass substrate. Alternatively, a ceramic substrate such as alumina, stainless steel, a flexible polymer, or the like may be used as the support substrate 100. The supporting substrate 100 may be transparent. The support substrate 100 may be rigid or flexible.

The back electrode layer 200 may be disposed on the supporting substrate 100. The rear electrode layer 200 may be a conductive layer. The rear electrode layer 200 may be formed of any one of molybdenum (Mo), gold (Au), aluminum (Al), chromium (Cr), tungsten (W), and copper (Cu). Of these, molybdenum has a smaller difference in thermal expansion coefficient than the support substrate 100 in comparison with other elements, so that it is possible to prevent peeling phenomenon from occurring due to its excellent adhesiveness.

In addition, the rear electrode layer 200 may include two or more layers. At this time, the respective layers may be formed of the same metal or may be formed of different metals.

The rear electrode layer 200 may have first through holes TH1 passing through the rear electrode layer 200. Referring to FIG. The first through holes (TH1) may be open regions that expose the upper surface of the support substrate (100). The first through grooves TH1 may have a shape extending in a first direction when viewed from a plane.

The width of the first through-holes TH1 may be about 80 占 퐉 to about 200 占 퐉.

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

The rear electrodes may be spaced from each other by the first through holes TH1. The rear electrodes may be arranged in a stripe form.

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

The light absorption layer 300 may be disposed on the rear electrode layer 200. In addition, the material contained in the light absorption layer 300 may be filled in the first through holes TH1.

The light absorption layer 300 may include an I-III-VI group 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.

The buffer layer 400 may be disposed on the light absorption layer 300. The buffer layer 400 may be in direct contact with the light absorbing layer 300.

A high resistance buffer layer (not shown) may be further disposed on the buffer layer 400. The high-resistance buffer layer may include zinc oxide (i-ZnO) that is not doped with impurities. The energy band gap of the high resistance buffer layer may be about 3.1 eV to 3.3 eV.

Second through holes (TH2) may be formed on the buffer layer (400). The second through holes (TH2) may be an open region that exposes one surface of the rear electrode layer (200). The second through grooves TH2 may have a shape extending in one direction when viewed in a plan view.

The buffer layer 400 may be defined as a plurality of buffer layers by the second through holes TH2. That is, the buffer layer 400 may be divided into the buffer layers by the second through-holes TH2.

The front electrode layer 500 may be disposed on the buffer layer 400. The front electrode layer 500 may be a transparent conductive layer. In addition, the resistance of the front electrode layer 500 may be higher than the resistance of the rear electrode layer 500.

The front electrode layer 500 may include an oxide. Examples of the material used for the front electrode layer 500 include Al doped ZnC (indium zinc oxide), indium zinc oxide (IZO), indium tin oxide (ITO) And the like.

The front electrode layer 500 may include connecting portions 600 positioned inside the second through holes TH2 and connected to the rear electrode layer 200. [

3 and 4 are cross-sectional and top views of the solar cell according to the first embodiment.

Referring to FIGS. 3 and 4, a predetermined pattern P may be formed on the front electrode layer 500. In detail, a pattern portion P having a depressed shape may be formed on the front electrode layer 500. The depressed pattern part P may be formed in a gird shape.

The depressed pattern portion P may be formed by etching the front electrode layer to a predetermined depth. That is, the depressed pattern portion P may be formed in a groove shape so that the side surface and the bottom surface of the pattern portion P are all the front electrode layer material, without passing through the front electrode layer.

A conductive material 700 may be inserted into the pattern portion of the depressed shape. In detail, a metallic material may be inserted into the pattern portion of the depressed shape. More specifically, a metal such as aluminum may be inserted into the pattern portion of the depressed shape.

The conductive material may be inserted at a height substantially equal to the height of the pattern portion. That is, the height of the top surface of the conductive material inserted into the pattern unit P and the top surface of the front electrode layer 500 may be substantially the same plane.

Accordingly, the conductive material may be inserted into the pattern portion P and be in contact with the front electrode layer in the pattern portion P. That is, the conductive material may be disposed in contact with the lower surface and both sides of the pattern portion P in the pattern portion P.

3 and 4, the pattern portions P are formed in the shape of an embossed relief pattern. However, the present invention is not limited to the pattern portions P, It may be disposed on the pattern portion P and arranged in a lattice shape.

5 and 6 are cross-sectional and top views of the solar cell according to the second embodiment. In the description of the solar cell according to the second embodiment, description of the same description as the first embodiment described above will be omitted, and the same reference numerals are assigned to the same configurations.

Referring to FIGS. 5 and 6, the front electrode layer 500 may include a first front electrode layer 510 and a second front electrode layer. In detail, the front electrode layer 500 may include a first front electrode layer 510 disposed on the buffer layer 400 and a second front electrode layer 520 disposed on the first front electrode layer 510 .

The first front electrode layer 510 and the second front electrode layer 520 may include the same or different materials. The first front electrode layer 510 and the second front electrode layer 520 may be formed of Al doped ZnC (AZO), indium zinc oxide (IZO), or indium tin oxide tin oxide (ITO), and the like.

The first front electrode layer 510 and the second front electrode layer 520 may be integrally formed.

A predetermined pattern portion P may be formed on the second front electrode layer 520. In detail, a plurality of pattern units may be formed on the second front electrode layer 520.

The pattern portions P may be formed in a recessed shape on the second front electrode layer 520. The pattern unit P may be formed by partially or entirely etching the second front electrode layer. Accordingly, one surface of the first front electrode layer 510 or one surface of the second front electrode layer 520 may be exposed by the depressed pattern portions P. That is, when a part of the second front electrode layer 520 is etched, one side of the second front electrode layer 520 may be exposed, and if the entirety of the second front electrode layer 520 is etched, One side of the electrode layer 510 may be exposed.

The pattern portions P may be formed in a lattice shape. That is, the lattice pattern of the engraved pattern may be formed on the second front electrode layer 520.

A conductive material 700 may be inserted into the pattern unit P. In detail, a conductive material 700 such as a metal may be inserted into the pattern portion P. For example, the conductive material may include a metal such as aluminum (Al).

The conductive material 700 may be inserted into the pattern portion P and arranged in the same shape as the pattern portion, that is, in a lattice pattern.

The conductive material 700 may be in contact with at least one front electrode layer of the first front electrode layer 510 and the second front electrode layer 520. That is, when a part of the second front electrode layer 520 is etched, one surface of the second front electrode layer 520 is exposed, and the conductive material may contact one surface of the second front electrode layer 520. When the entirety of the second front electrode layer 520 is etched, one surface of the first front electrode layer 510 is exposed, a bottom surface of the conductive material contacts the first front electrode layer 510, And may contact the second front electrode layer 520.

5 and 6, the pattern portions P are formed concentrically, but the present invention is not limited thereto. The pattern portion P may be formed in a lattice shape of a relief, It may be disposed on the pattern portion P and arranged in a lattice shape.

7 and 8 are cross-sectional and top views of the solar cell according to the third embodiment. In the description of the solar cell according to the third embodiment, description of the same description as the first and second embodiments described above will be omitted, and the same reference numerals are assigned to the same components.

Referring to FIGS. 7 and 8, the front electrode layer 500 may include a first front electrode layer 510 and a second front electrode layer. In detail, the front electrode layer 500 may include a first front electrode layer 510 disposed on the buffer layer 400 and a second front electrode layer 520 disposed on the first front electrode layer 510 .

The protrusions 521 may be formed on the second front electrode layer 520. The protrusions 521 may be formed integrally with the second front electrode layer 520. That is, the protrusions 521 and the second front electrode layer 520 may be formed of the same material.

The protrusions 521 may be formed in a checkerboard shape. In detail, the protrusions 521 may be formed in a rectangular shape spaced apart from each other. The protrusions may form a depression H on the second front electrode layer 520. That is, a groove H formed between the protrusions may be formed on the second front electrode layer 520.

A metal layer 700 may be disposed between the protrusions. That is, the metal layer 700 may be disposed in the groove. Accordingly, the metal layer 700 may be disposed between the protrusions to have a lattice shape.

7 and 8, the front electrode layer is divided into the first front electrode layer and the second front electrode layer. However, the present invention is not limited thereto, and a protrusion may be formed on the front electrode layer, and a metal layer may be formed between the protrusions. It is of course possible to arrange them in a lattice shape.

Further, it is needless to say that protrusions are not formed, a rectangular groove is formed, lattice-shaped protrusions are formed, and metal layers are arranged in a lattice form on the protrusions.

In the solar cell according to the embodiments, a groove or a pattern portion is formed on the front electrode layer, and a conductive material such as a metal is disposed in the groove or the pattern portion, whereby the path of the electron can be increased.

In the prior art, although the flow of electrons in the solar cell was shifted from the light absorption layer to the front electrode layer only in one direction, in the solar cell according to the embodiments, the conductive material, such as metal, It is possible to increase the electron movement path inside the solar cell.

Accordingly, the solar cell according to the embodiments can reduce the loss due to the movement of electrons generated in the lower portion of the light absorption layer, thereby improving the overall efficiency of the solar cell.

In addition, in the solar cell according to the embodiments, when the supporting substrate has a flexible material such as plastic, the damage of the metal layer disposed on the front electrode layer can be prevented.

That is, a metal layer is arranged in a lattice pattern by forming a pattern portion or a groove on the front electrode layer and arranging a metal layer in the form of a lattice in the pattern portion or the groove. When such a metal layer is formed in the front electrode layer, It is possible to reduce cracks due to bending of the metal layer and the like even when applied to a flexible solar cell. Therefore, when the solar cell according to the embodiments is applied to a flexible solar cell, the overall reliability of the solar cell can be improved.

Third through holes (TH3) may be formed in the front electrode layer (500). The third through holes TH3 may pass through the rear electrode layer 200, the light absorbing layer 300, the buffer layer 400, and the front electrode layer 500. [ Accordingly, one surface of the rear electrode layer 200 may be exposed by the third through holes TH3.

The third through grooves TH3 may be formed at positions adjacent to the second through grooves TH2. More specifically, the third through grooves TH3 may be disposed beside the second through grooves TH2. That is, when viewed in plan, the third through grooves TH3 may be arranged next to the second through grooves TH2. The third through grooves TH3 may have a shape extending in the first direction.

The front electrode layer 500 may be divided into a plurality of front electrodes by the third through holes TH3. That is, the front electrodes may be defined by the third through holes TH3.

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

In addition, a plurality of solar cells C1, C2, ... can be defined by the third through holes TH3. More specifically, the solar cells (C1, C2, ...) can be defined by the second through grooves (TH2) and the third through grooves (TH3). That is, the solar cell according to the embodiment can be divided into the solar cells (C1, C2, ...) by the second through grooves TH2 and the third through grooves TH3. The solar cells C1, C2, ... may be connected to each other in a second direction intersecting with the first direction. That is, current can flow in the second direction through the solar cells C1, C2, ....

That is, the solar cell panel 10 includes the support substrate 100 and the solar cells C1, C2,. The solar cells C1, C2, ... are disposed on the support substrate 100 and are spaced apart from each other. In addition, the solar cells C1, C2, ... may be connected in series with each other by the connection portions 600.

The connection portions 600 may be inserted into the second through-holes TH2. The connection portions 600 may extend downward from the front electrode layer 500 and may be connected to the rear electrode layer 200. For example, the connection portions 600 may extend from the front electrode of the first cell C1 and may be connected to the rear electrode of the second cell C2.

Accordingly, the connection portions 600 can connect adjacent solar cells. More specifically, the connection portions 600 may connect the front electrode and the rear electrode included in the adjacent solar cells, respectively.

The connection part 600 may be formed integrally with the front electrode layer 600. That is, the material used for the connection part 600 may be the same as the material used for the front electrode layer 500.

Hereinafter, a solar cell module to which the solar cell according to the embodiments is applied will be described with reference to FIG.

9, a solar cell module according to an embodiment includes a solar cell 1000, a plurality of frames 4000 that house the solar cell 1000, a protection layer (not shown) disposed on the solar cell 1000, (2000), and an upper substrate (3000) disposed on the protective layer (2000).

The protective layer 2000 is integrated with the solar cell 1000 by a lamination process while being disposed on the top of the solar cell 1000 to prevent corrosion due to moisture penetration and protect the solar cell 1000 from impact do. The protective layer 2000 may be made of a material such as ethylene vinyl acetate (EVA).

The upper substrate 3000 positioned on the protective layer 2000 is made of tempered glass having high transmittance and excellent breakage-preventing function. At this time, the tempered glass may be a low iron tempered glass having a low iron content.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in 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 clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (13)

A support substrate;
A rear electrode layer disposed on the supporting substrate;
A light absorbing layer disposed on the rear electrode layer;
A buffer layer disposed on the light absorbing layer; And
And a front electrode layer disposed on the buffer layer,
Wherein the front electrode layer comprises:
A first front electrode layer disposed on the buffer layer; And
And a second front electrode layer disposed on the first front electrode layer,
Wherein the second front electrode layer comprises a plurality of pattern units and a conductive material disposed in the pattern units. The method according to claim 1,
Wherein the pattern portion includes a grid shape. The method according to claim 1,
The supporting substrate is a flexible solar cell. The method according to claim 1,
Wherein the pattern unit exposes one surface of the first front electrode layer or the second front electrode layer. 5. The method of claim 4,
Wherein the conductive material is disposed in contact with one surface of at least one front electrode layer of the first front electrode layer and the second front electrode layer. The method according to claim 1,
Wherein the first front electrode layer and the second front electrode layer are integrally formed. A support substrate;
A rear electrode layer disposed on the supporting substrate;
A light absorbing layer disposed on the rear electrode layer;
A buffer layer disposed on the light absorbing layer; And
And a front electrode layer disposed on the buffer layer,
A first front electrode layer disposed on the buffer layer; And
And a second front electrode layer disposed on the first front electrode layer,
Wherein the second front electrode layer is formed of
A plurality of protrusions and a metal layer disposed between the protrusions. 8. The method of claim 7,
Wherein the metal layer is disposed in a grid shape. 8. The method of claim 7,
Wherein the first front electrode layer and the second front electrode layer are integrally formed,
Wherein the metal layer is disposed in contact with one surface of the first front electrode layer. 8. The method of claim 7,
Wherein the supporting substrate comprises plastic. A support substrate;
A rear electrode layer disposed on the supporting substrate;
A light absorbing layer disposed on the rear electrode layer;
A buffer layer disposed on the light absorbing layer; And
And a front electrode layer disposed on the buffer layer,
A pattern portion having a depressed shape is formed on the front electrode layer,
Wherein the pattern portion is filled with a conductive material. 12. The method of claim 11,
Wherein the pattern portion is formed in a lattice shape. 12. The method of claim 11,
Wherein the support substrate comprises plastic,
Wherein the conductive material comprises a metallic material.

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