KR101327099B1 - Solar cell module and method of fabricating the same - Google Patents

Abstract

The embodiment provides a solar cell module and a method of manufacturing the same. The solar cell module according to the embodiment includes a rear electrode layer disposed on a backsheet; A light absorbing layer disposed on the rear electrode layer; A front electrode layer disposed on the light absorbing layer; And a cover glass disposed on the front electrode layer.

Description

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

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

A solar cell can be defined as a device that converts light energy into electric energy by using a photovoltaic effect that generates electrons when light is applied to a p-n junction diode. The solar cell can be classified into a silicon solar cell, a compound semiconductor solar cell represented by group I-III-VI or III-V, a dye-sensitized solar cell, and an organic solar cell, depending on materials used as a junction diode.

CIGS (CuInGaSe) solar cell, which is one of the I-III-VI family chalcopyrite compound semiconductors, has excellent light absorption, high photoelectric conversion efficiency even at a thin thickness, and excellent electro- It is emerging as an alternative solar cell.

The CIGS thin film solar cell is manufactured by sequentially forming a substrate including a sodium, a back electrode layer, a light absorbing layer, and a front electrode layer. Substrates for manufacturing CIGS thin film solar cells generally include glass substrates, metal substrates such as aluminum, or polymer substrates. Among these, even in the case of the most stable glass substrate at a high temperature, there is a problem that deformation occurs, such as glass bending, above the softening point. On the other hand, the light efficiency of CIGS thin film solar cell increases with higher process temperature. Therefore, when raising the process temperature in order to increase the light efficiency of the CIGS thin film solar cell, there is a problem that the phenomenon that the glass substrate is more severely generated.

In addition, the light efficiency of the CIGS thin film solar cell increases as the temperature uniformity of the substrate increases. This is particularly a problem when manufacturing a CIGS thin film solar cell on a large area glass substrate. The temperature uniformity of the large area glass substrates used in the prior art is poor in temperature uniformity between about 2% and about 5%.

The embodiment is prepared by a high temperature process, to provide a substrate (substrateless) solar cell and a method of manufacturing the same.

The solar cell module according to the embodiment includes a rear electrode layer disposed on a backsheet; A light absorbing layer disposed on the rear electrode layer; A front electrode layer disposed on the light absorbing layer; And a cover glass disposed on the front electrode layer.

Method for manufacturing a solar cell module according to the embodiment comprises the steps of forming a sacrificial layer on the carbon structure; Forming a solar cell on the sacrificial layer; Separating the solar cell from the carbon structure by removing the sacrificial layer; And arranging the separated solar cell and the cover glass on a back sheet to form a solar cell module.

The solar cell module according to the embodiment forms a solar cell on a carbon structure that can withstand high temperature processes. As a result, the light absorbing layer may be deposited at a high process temperature of about 700 ° C. or higher. In addition, the carbon structure has better thermal conductivity than the conventional glass substrate, and thus can improve temperature uniformity. Therefore, the efficiency of the solar cell module according to the embodiment can be improved.

In addition, the method for manufacturing a solar cell module according to the embodiment transfers a solar cell formed on a carbon structure onto a backsheet. Accordingly, the solar cell module in which the manufacturing process is completed has a structure that does not include a substrate. Therefore, the manufacturing method of the solar cell module according to the embodiment can reduce the thickness and weight of the substrate, thereby reducing the production and manufacturing costs, and can reduce the installation cost.

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

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.

1 to 6 are cross-sectional views illustrating a method of manufacturing the solar cell module according to the embodiment. Hereinafter, a solar cell module and a manufacturing method thereof according to an embodiment will be described in detail with reference to FIGS. 1 to 6.

Referring to FIG. 1, the sacrificial layer 200 is formed on the carbon structure 100. The carbon structure 100 may include graphene or graphite. As used herein, the term "grapheme" refers to a graphene in which a plurality of carbon atoms are covalently linked to each other to form a polycyclic aromatic molecule, forming a layer or sheet form. The carbon atoms form a 6-membered ring as the basic repeating unit, but may further include a 5-membered ring and / or a 7-membered ring. Thus, the graphene appears as a single layer of covalently bonded carbon atoms (usually sp ² bonds). The graphene may have a variety of structures, such a structure may vary depending on the content of 5-membered and / or 7-membered rings that may be included in the graphene.

In addition, as used herein, the term “graphite” may mean that a plurality of graphenes are stacked on each other, and have two or more layered structures, but is not limited thereto.

The solar cell according to the embodiment forms a solar cell on the carbon structure 100 having a stable property at a high temperature, not a glass substrate used in the prior art. Accordingly, the solar cell may be manufactured under a higher process temperature on the carbon structure 100, and thus, the efficiency of the solar cell module manufactured may be improved.

The sacrificial layer 200 may be used without particular limitation as long as it is a photoresist (PR) material commonly used in the art. For example, the sacrificial layer 200 may be formed using a negative photoresist material such as polyisoprene or azide, or a positive photoresist material such as phenol-formaldehyde.

In one embodiment, the sacrificial layer 200 may be coated on the carbon structure 100 by spin coating or the like, and then manufactured through an exposure process.

Referring to FIG. 2, the solar cell 300 is formed on the sacrificial layer 200. In more detail, the solar cell 300 includes a back electrode layer 10, a light absorbing layer 20, a buffer layer 30, a high resistance buffer layer 40, and a front electrode layer 50 sequentially formed on the sacrificial layer 200. ) May be included. The solar cell 300 according to the embodiment is formed on the carbon structure 100 and does not require a separate substrate (substrateless).

The back electrode layer 10 is formed on the sacrificial layer 200. The back electrode layer 10 may be formed by physical vapor deposition (PVD) or plating.

The back electrode layer 10 is a conductive layer. The back electrode layer 10 may be formed of any one of molybdenum (Mo), gold (Au), aluminum (Al), chromium (Cr), tungsten (W), and copper (Cu). Among them, in particular, molybdenum (Mo) has a smaller difference between the glass substrate 100 and the coefficient of thermal expansion than other elements, and thus, excellent adhesion can be prevented from occurring.

The light absorbing layer 20 is formed on the back electrode layer 10. The light absorbing layer 20 includes an I-III-VI compound. For example, the light absorbing layer 20 may be formed of a copper-indium-gallium-selenide-based (Cu (In, Ga) (Se, S) ₂ ; CIGSS-based) crystal structure, copper-indium-selenide-based, or copper- It may have a gallium-selenide-based crystal structure.

The light absorbing layer 20 may be, for example, copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) while simultaneously evaporating copper, indium, gallium, and selenium. The method of forming (20) and the method of forming a metal precursor film and forming it by the selenization process are used widely.

After the metal precursor film is formed and then subjected to selenization, 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 (Cu (In, Ga) Se ₂ ; CIGS-based) light absorbing layer 20 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 20 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.

The process of manufacturing the light absorbing layer 20 is performed under a very high process temperature. For example, the process of manufacturing the light absorbing layer 20 may be performed under a temperature atmosphere of about 550 ℃ to about 800 ℃. In more detail, the light absorbing layer 20 may be manufactured under a temperature atmosphere of about 700 ° C. to about 800 ° C., but is not limited thereto.

Conventionally, in order to prevent the deformation of the glass substrate occurring at a temperature above the softening point, the light absorbing layer may be manufactured only at a temperature of about 300 ° C. to about 500 ° C., which in turn leads to a decrease in efficiency of the solar cell module. Meanwhile, the solar cell module according to the embodiment performs a process on a carbon structure that can withstand even higher temperature conditions than a glass substrate, and thus can produce a light absorbing layer under higher temperature conditions. Therefore, the efficiency of the solar cell module according to the embodiment can be improved.

In addition, the carbon structure 100 according to the embodiment is very excellent in thermal properties such as thermal conductivity. Accordingly, the carbon structure 100 layer may be heated to a uniform temperature regardless of the position of the layer. That is, the temperature of the inner region of the carbon structure layer 100 and the temperature of the peripheral region of the layer may be substantially uniform. Accordingly, the temperature uniformity of the carbon structure according to the embodiment can be reduced to about 1% or less, which results in efficiency improvement.

The buffer layer 30 is disposed on the light absorbing layer 20. The buffer layer 30 includes cadmium sulfide, ZnS, InXSY, InXSeYZn (O, OH), and the like. The buffer layer 30 may be formed by depositing cadmium sulfide on the light absorbing layer 20 by chemical bath deposition (CBD). The high resistance buffer layer 40 is disposed on the buffer layer 30. The high resistance buffer layer 40 includes zinc oxide (i-ZnO) that is not doped with impurities. The high resistance buffer layer 40 may be formed by depositing zinc oxide on the buffer layer 30 by a sputtering process or the like.

The front electrode layer 50 is formed on the high resistance buffer layer 40. The front electrode layer 600 may have the characteristics of an n-type semiconductor. That is, the front electrode layer 600 may form an n-type semiconductor layer together with the buffer layer 400 to form a pn junction with the light absorbing layer 300, which is a p-type semiconductor layer. The front electrode layer 500 may be formed of, for example, aluminum doped zinc oxide (AZO).

The front electrode layer 50 may be manufactured by sputtering or chemical vapor deposition. More specifically, in order to form the front electrode layer 50 by the sputtering, a method of depositing using a ZnO target and a reactive sputtering using a Zn target may be used as the RF sputtering method.

Referring to FIG. 3, the sacrificial layer 200 is removed to separate the solar cell 300 and the carbon structure 100 manufactured by the aforementioned process. For example, the sacrificial layer 200 may be removed by a wet cleaning process. When the sacrificial layer 200 is a positive photoresist material, the sacrificial layer 200 may be removed using a sodium hydroxide solution or the like as a developer. When the sacrificial layer 200 is a negative photoresist material, the sacrificial layer 200 may be removed using a xylene solution or the like as a developer.

Meanwhile, in the method of manufacturing a solar cell module according to the embodiment, a part of the sacrificial layer 200 may not be removed in the separation process and may remain on the lower side of the back electrode layer 10, but is limited thereto. It is not.

4 to 6, the solar cell 300 separated as described above is transferred onto a back sheet 400. In more detail, before the separated solar cell 300 is transferred onto the backsheet 400, the back EVA layer 510 may be further disposed on the backsheet 400.

After transferring the solar cell 300 on the backsheet 400, the front EVA layer (ethylene vinyl acetate, 520) and the cover glass 600 are sequentially disposed on the solar cell 300. Then, by performing a lamination (lamination) process, the solar cell module according to the embodiment can be manufactured. In the lamination process, a predetermined pressure and heat may be applied to the backsheet 400 to the cover glass 600. The back EVA layer 510 improves adhesion between the backsheet 400 and the solar cell 300, and the front EVA layer 520 adheres between the solar cell 300 and the cover glass 600. Can improve.

The cover glass 600 is transparent and protects the solar cell 300 from external physical impact and / or foreign matter. The cover glass 600 may include tempered glass. In this case, the tempered glass may be a low iron tempered glass having a low iron content.

The solar cell module manufactured by the above-mentioned method does not include a substrate. That is, the solar cell 300 according to the embodiment is formed in direct contact with the back sheet 400. Accordingly, the manufacturing method of the solar cell module according to the embodiment can reduce the production manufacturing cost. In addition, the manufactured solar cell module is reduced in thickness and weight as much as the substrate, there is an effect that can also reduce the installation cost.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention and are not necessarily limited to only one embodiment. Furthermore, 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 taken by way of illustration, It can be seen that various modifications 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.

Claims (10)

A back electrode layer disposed on the backsheet;
A light absorbing layer disposed on the rear electrode layer;
A front electrode layer disposed on the light absorbing layer; And
A cover glass disposed on the front electrode layer,
Forming a sacrificial layer on a carbon structure, forming the back electrode layer on the sacrificial layer, forming the light absorbing layer on the back electrode layer, forming the front electrode layer on the light absorbing layer, and forming the sacrificial layer. Removing the rear electrode layer from the carbon structure, arranging the rear electrode layer on the back sheet, and forming the cover glass on the front electrode layer.
delete The method of claim 1,
A rear EVA layer disposed between the backsheet and the rear electrode layer; And
The solar cell module further comprises a front EVA layer disposed between the front electrode layer and the cover glass.
The method of claim 1,
The solar cell module does not include a support substrate.
Forming a sacrificial layer on the carbon structure;
Forming a solar cell on the sacrificial layer;
Separating the solar cell from the carbon structure by removing the sacrificial layer; And
On the back sheet (Back sheet), comprising the step of placing the separated solar cell and the cover glass to form a solar cell module,
Forming the solar cell,
Forming a back electrode layer on the sacrificial layer;
Forming a light absorbing layer on the back electrode layer; And
A method of manufacturing a solar cell module comprising forming a front electrode layer on the light absorbing layer.
The method of claim 5, wherein
The carbon structure is a method of manufacturing a solar cell module comprising graphite (graphite) or graphene (graphene).
delete The method of claim 5, wherein
The light absorbing layer is a manufacturing method of a solar cell module is manufactured in a temperature atmosphere of 550 ℃ to 800 ℃.
The method of claim 5, wherein
The separating of the solar cell may include removing the sacrificial layer by performing a wet cleaning process.
The method of claim 5, wherein
Forming the solar cell module,
Forming a back EVA layer on the back sheet;
Transferring the separated solar cells on the back EVA layer,
Forming a front EVA layer on the solar cell,
Forming and laminating the cover glass on the front EVA layer manufacturing method of a solar cell module.

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