KR20130030906A

KR20130030906A - Solar cell

Info

Publication number: KR20130030906A
Application number: KR1020110094489A
Authority: KR
Inventors: 성명석
Original assignee: 엘지이노텍 주식회사
Priority date: 2011-09-20
Filing date: 2011-09-20
Publication date: 2013-03-28

Abstract

According to an embodiment, a solar cell includes a support substrate including a recess; And a light absorbing layer, a buffer layer, and a front electrode layer positioned on the support substrate, and including a heat radiating portion positioned in the concave portion.

Description

Solar cell {SOLAR CELL}

The present disclosure relates to a solar cell.

A manufacturing method of a solar cell for solar power generation is as follows. First, a substrate is provided, a back electrode layer is formed on the substrate, and patterned by a laser to form a plurality of back electrodes.

Thereafter, a light absorbing layer, a buffer layer, and a high resistance buffer layer are sequentially formed on the back electrodes. A method of forming a light absorbing layer of copper-indium-gallium-selenide (Cu (In, Ga) Se2; CIGS) while simultaneously evaporating copper, indium, gallium, and selenium to form the light absorbing layer; The method of forming a metal precursor film and forming it by a selenization process is widely used. The energy band gap of the light absorbing layer is about 1 to 1.8 eV.

Thereafter, a buffer layer containing cadmium sulfide (CdS) is formed on the light absorbing layer by a sputtering process. The energy bandgap of the buffer layer is about 2.2 to 2.4 eV. Thereafter, a high resistance buffer layer including zinc oxide (ZnO) is formed on the buffer layer by a sputtering process. The energy bandgap of the high resistance buffer layer is about 3.1 to 3.3 eV.

Thereafter, a groove pattern may be formed in the light absorbing layer, the buffer layer, and the high resistance buffer layer.

Thereafter, a transparent conductive material is stacked on the high resistance buffer layer, and the groove pattern is filled with the transparent conductive material. Accordingly, a transparent electrode layer is formed on the high resistance buffer layer, and connection wirings are formed inside the groove pattern, respectively. Examples of the material used for the transparent electrode layer and the connection wiring include aluminum doped zinc oxide and the like. The energy band gap of the transparent electrode layer is about 3.1 to 3.3 eV.

Thereafter, a groove pattern is formed in the transparent electrode layer, and a plurality of solar cells may be formed. The transparent electrodes and the high resistance buffers correspond to respective cells. The transparent electrodes and the high resistance buffers may be arranged in a stripe form or a matrix form.

The transparent electrodes and the back electrodes are misaligned with each other, and the transparent electrodes and the back electrodes are electrically connected to each other by the connection wirings. Accordingly, a plurality of solar cells can be electrically connected in series with each other.

As such, in order to convert sunlight into electrical energy, various types of photovoltaic devices may be manufactured and used. Such a photovoltaic device is disclosed in Patent Publication No. 10-2008-0088744 and the like.

Embodiments provide a solar cell having improved photoelectric conversion efficiency.

The solar cell according to the embodiment includes a recess in the back of the support substrate. Due to the concave portion, the cross-sectional area of the rear surface of the support substrate is increased, so that heat dissipation may occur effectively in the central portion, and heat condensation of the central portion may be prevented. Therefore, the loss of generated electric power by heat can be prevented, and the efficiency reduction phenomenon by the extreme surface temperature rise by sunlight can be prevented.

In addition, due to the concave portion, the rigidity of the support substrate may be increased to prevent bending and sagging due to gravity in the large-area thin film solar cell. Therefore, a highly efficient solar cell can be provided.

On the other hand, in the solar cell according to the embodiment, the heat radiating portion is located in the concave portion. The heat dissipation part may include a metal or a metal oxide having high heat conductivity, so that heat of the support substrate may be quickly dissipated.

1 is a cross-sectional view illustrating a solar cell according to a first embodiment.
2 is a plan view of a support substrate included in a solar cell according to the first embodiment.
3 is a plan view of a support substrate included in a solar cell according to a second embodiment.
4 is a plan view of a support substrate included in a solar cell according to a third embodiment.

In the description of embodiments, each layer, region, pattern, or structure may be “on” or “under” the substrate, each layer, region, pad, or pattern. Substrate formed in ”includes all formed directly or through another layer. Criteria for the top / bottom or bottom / bottom of each layer will be 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.

First, the solar cell according to the first embodiment will be described in detail with reference to FIGS. 1 and 2. 1 is a cross-sectional view illustrating a solar cell according to a first embodiment. 2 is a plan view of a support substrate included in a solar cell according to the first embodiment.

Referring to FIG. 1, a solar cell includes a support substrate 100 including a recess 120, a heat dissipation unit 140, a back electrode layer 200, a light absorbing layer 300, a buffer layer 400, and a high resistance buffer layer ( 500 and the front electrode layer 600.

The supporting substrate 100 has a plate shape and supports the rear electrode layer 200, the light absorbing layer 300, the buffer layer 400, the high resistance buffer layer 500, and the front electrode layer 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 support substrate 100 may include a recess 120. At least one concave portion 120 may be provided on the support substrate 100.

The support substrate 100 includes a first surface 100a (hereinafter referred to as "top surface 100a") and a second surface 100b (hereinafter referred to as "back surface 100b") opposite to each other. The light absorbing layer 300, the buffer layer 400, and the front electrode layer 600 may be disposed on the upper surface 100a, and the concave portion 120 and the heat radiating portion 140 may be provided on the rear surface 100b. .

Specifically, referring to FIG. 2, a plurality of recesses 120 may be located on the rear surface 100b of the support substrate 100. The recess 120 may include a first recess 121 and a second recess 122. The first concave portion 121 and the second concave portion 122 may be located at different positions on the support substrate 100. Specifically, the first concave portion 121 extends in the first direction of the support substrate 100, and the second concave portion 122 crosses the first direction of the support substrate 100. Can extend in a direction. Therefore, as shown in FIG. 2, the recess 120 may have a checkered pattern.

The support substrate 100 may include a central portion CA and an outer portion EA surrounding the central portion CA, and the concave portion 120 may include the central portion CA and the outer portion EA. It can be located at In this case, the concave portion 120 positioned in the central portion CA may have different widths from the concave portion 120 positioned in the outer portion EA. Specifically, the width of the concave portion 120 positioned in the central portion CA may be wider than the width of the concave portion 120 positioned in the outer portion EA.

Due to the concave portion 120, the cross-sectional area of the back surface 100b of the support substrate 100 increases, and heat emission may effectively occur in the central portion CA, and heat concentration of the central portion CA may be prevented. . Therefore, the loss of generated electric power by heat can be prevented, and the efficiency reduction phenomenon by the extreme surface temperature rise by sunlight can be prevented.

In addition, the rigidity of the support substrate 100 is increased due to the concave portion 120 to prevent bending and sagging due to gravity in the large-area thin film solar cell. Therefore, a highly efficient solar cell can be provided.

The area of the recess 120 may be 10% to 20% of the area of the support substrate 100.

The depth of the recess 120 may be 20% to 80% of the thickness of the support substrate 100. When the depth of the recess 120 is less than 20% of the thickness of the support substrate 100, the effect of heat dissipation may be weak. In addition, when the depth of the recess 120 exceeds 80% of the thickness of the support substrate 100, the physical strength of the support substrate 100 may be weakened.

Subsequently, the heat radiating part 140 may be located in the recess 120. The heat dissipation unit 140 may include a first heat dissipation unit 141 and a second heat dissipation unit 142. In detail, the heat dissipation unit 140 may include a first heat dissipation unit 141 filled in the recess 120 and a second heat dissipation unit 142 exposed on the support substrate 100.

The heat dissipation unit 140 may include a metal. The heat dissipation unit 140 may include at least one material selected from the group consisting of a metal including copper, aluminum, silver, nickel, and chromium and an oxide including the same. Since the heat dissipation unit 140 includes a metal or metal oxide having high heat conductivity, heat of the support substrate 100 may be quickly released.

The heat radiating unit 140 may be formed by inserting a paste including the metal and the metal oxide into the recess 120 or coating the paste on the back surface 100b of the support substrate 100. In particular, the paste containing copper or aluminum is ductile and can be easily inserted into the recess 120.

The thickness t of the second heat dissipation part 142 may be 20% to 40% of the depth of the recess 120.

Since the heat dissipation unit 140 is positioned on the rear surface 100b of the support substrate 100, heat dissipation of the support substrate 100 may be faster to reduce heat concentration.

The back electrode layer 200 is disposed on the top surface 100a of the support substrate 100. The back electrode layer 200 is a conductive layer. Examples of the material used as the back electrode layer 200 may include a metal such as molybdenum (Mo).

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.

The light absorbing layer 300 is disposed on the back electrode layer 200. The light absorbing layer 300 includes a group I-III-VI compound. For example, the light absorbing layer 300 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-based. It may have a 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 is disposed on the light absorbing layer 300. The buffer layer 400 is in direct contact with the light absorbing layer 300. The buffer layer 400 includes cadmium sulfide. The energy band gap of the buffer layer 400 may be about 1.9 eV to about 2.3 eV.

The high resistance buffer layer 500 is disposed on the buffer layer 400. The high resistance buffer layer 500 includes zinc oxide (i-ZnO) that is not doped with impurities. The energy band gap of the high resistance buffer layer 500 may be about 3.1 eV to 3.3 eV.

The front electrode layer 600 is disposed on the light absorbing layer 300. In more detail, the front electrode layer 600 is disposed on the high resistance buffer layer 500.

The front electrode layer 600 is disposed on the high-resistance buffer layer 500. The front electrode layer 600 is transparent. Examples of the material used as the front electrode layer 600 include aluminum doped ZnO (AZO), indium zinc oxide (IZO), indium tin oxide (ITO), and the like. Can be.

The front electrode layer 600 may have a thickness of about 500 nm to about 1.5 μm. In addition, when the front electrode layer 600 is formed of zinc oxide doped with aluminum, aluminum may be doped at a ratio of about 2.5 wt% to about 3.5 wt%. The front electrode layer 600 is a conductive layer.

Hereinafter, a solar cell according to a second embodiment will be described with reference to FIG. 3. Detailed descriptions of parts identical or similar to those of the first embodiment will be omitted for clarity and simplicity.

3 is a plan view of the support substrate 100 included in the solar cell according to the second embodiment.

Referring to FIG. 3, a recess 120 may be provided on the rear surface 100b of the support substrate 100 included in the solar cell according to the second embodiment.

The recess 120 may include a first recess 121 and a second recess 122, and the first recess 121 and the second recess 122 may be spaced apart from each other. Can be.

For example, the first concave portion 121 and the second concave portion 122 may extend along each side of the support substrate 100. Specifically, as shown in FIG. 3, the recess 120 may be positioned in a circle on the support substrate 100. That is, the first concave portion 121 is positioned in a circle at the central portion CA of the support substrate 100, and the second concave portion 122 is disposed at the outer portion EA of the support substrate 100. Can be placed in a circle. In this case, the width of the first recess 121 may be greater than the width of the second recess 122. Through this, heat dissipation in the central portion CA may occur efficiently.

Although not shown in the drawings, the heat radiating portion may be further located on the rear surface 100b of the concave portion 120 and the support substrate 100.

Hereinafter, a solar cell according to a fourth embodiment will be described with reference to FIG. 4. 4 is a plan view of the support substrate 100 included in the solar cell according to the third embodiment.

Referring to FIG. 4, the support substrate 100 included in the solar cell according to the third embodiment includes a recess 120. The support substrate 100 includes a central portion CA and an outer portion EA surrounding the central portion CA, and the recess 120 is radial from the central portion CA to the outer portion EA. It can be extended to. Accordingly, the recesses 120 may be concentrated in the central portion CA, and the recesses 120 may be dispersed toward the outer portion EA. Through this, heat dissipation in the central portion CA may occur efficiently.

However, the embodiment is not limited thereto, and the concave portion 120 may be formed in various patterns for heat dissipation of the support substrate 100.

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. In addition, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to 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. 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

A support substrate including a recess; And
It includes a light absorbing layer, a buffer layer and a front electrode layer located on the support substrate,
Solar cell comprising a heat dissipation unit located in the recess.

The method of claim 1,
The heat dissipation unit includes a solar cell.

The method of claim 1,
The heat dissipation unit includes at least one material selected from the group consisting of a metal including copper, aluminum, silver, nickel and chromium and an oxide comprising the same.

The method of claim 1,
The heat dissipation unit includes a first heat dissipation unit filled in the recess and a second heat dissipation unit exposed on the support substrate.

5. The method of claim 4,
The second heat dissipation unit has a thickness of 20% to 40% of the depth of the recess.

The method of claim 1,
The support substrate includes a first surface and a second surface opposite to each other, the light absorbing layer, the buffer layer and the front electrode layer is located on the first surface, the second surface is provided with the recess and the heat dissipation portion battery.

The method of claim 1,
At least one recess is provided with a solar cell.

The method of claim 1,
The recess includes a first recess and a second recess, wherein the first recess and the second recess are positioned at different positions on the support substrate.

9. The method of claim 8,
The first recess extends in the first direction of the support substrate,
The second concave portion extends in a second direction crossing the first direction of the support substrate.

9. The method of claim 8,
The first recess and the second recess is spaced apart from the solar cell.

9. The method of claim 8,
The first recess and the second recess is a solar cell extending along each side of the support substrate.

The method of claim 1,
The support substrate includes a central portion and an outer portion surrounding the central portion,
The recess is located in the central portion and the outer portion solar cell.

The method of claim 12,
The concave portion extends radially from the center portion to the outer portion.

The method of claim 12,
The concave portion includes the first concave portion positioned in the center portion and the second concave portion positioned in the outer portion, wherein the first concave portion and the second concave portion have different depths.

The solar cell of claim 1, wherein a depth of the recess is 20% to 80% of a thickness of the support substrate.

15. The method of claim 14,
The first recess and the second recess is a solar cell having a different width.

15. The method of claim 14,
The first recessed portion has a larger width than the second recessed portion.

The method of claim 1,
An area of the recess is 10% to 20% of the area of the support substrate.