KR20090110048A - Transparent conductive thin film, solar cell and the method thereof - Google Patents

Abstract

PURPOSE: A transparent conductive film, a solar battery using the same, and a manufacturing method thereof for improving the efficiency of the solar battery are provided to form a texture of a concave-convex on a transparent conductive layer. CONSTITUTION: A transparent conductive film includes a seed layer, and a conductive film layer. The seed layer is formed to apply the seed of a concave-convex type on a glass substrate and is formed to a first oxide of nano powder type. A second oxide for forming electric conduction layer is formed on the glass substrate in which the seed layer is formed.

Description

Transparent conductive film, solar cell using same and manufacturing method thereof

The present invention relates to a method of manufacturing a transparent conductive film, a solar cell and a transparent conductive film using a transparent conductive film, sputtering that can be relatively inexpensive and mass-produced, in particular, using AZO (Aluminum Zinc Oxide), etc. It is related with the technique which can manufacture a transparent conductive film by the sputtering process.

The present invention, using nano powder such as ATO (Antimony Tin Oxide), can form a concave-convex texture on the transparent conductive film, without additional etching and polishing process, the solar cell due to the trap effect The efficiency can be improved.

In order to reduce our dependence on fossil fuels, research and development are being actively conducted on alternative and clean energy sources, new sources of energy that do not harm the environment and are not depleted.

At one time, although nuclear power was developed as a viable alternative energy, it showed a high contribution, but problems such as instability and serious damages caused by accidents have been raised, and it is gradually decreasing its dependence on it. In terms of how to use solar energy realistically, it is getting more attention.

As one of the methods that can utilize the solar energy, a solar cell (Solar Cell) has emerged.

The solar cell uses a photoelectric conversion element. Such solar cells are divided into silicon based solar cells and thin film type solar cells using compound semiconductors such as Cu, In, Ga, Se, etc. according to the type of power generation layer, which converts the received sunlight into electrical energy. The way prevails.

In general, a solar cell has a PN structure, and when solar light having energy greater than the band-gap energy (Eg) of a PN junction semiconductor is incident, an electron-hole pair (EHP) is generated. The electrons are collected in the n-layer and the p-layers are formed by the electric field formed at the PN junction, so that electromotive force (photovoltage) is generated between the PNs. At this time, if a load is connected to the electrodes at both ends, current flows.

Therefore, in the general solar cell, electrons are excited in the photosensitive part according to the received light, and the excited electrons are moved to the cathode layer to generate electromotive force, and the photosensitive part is configured to supply electricity to the user. It is desirable to use an electrode film having good conductivity that can efficiently transfer the light, and it is required that one side be a transparent shape so as to collect as much light as possible.

That is, the transparent conductive film (or transparent conductive oxide film) that can be used for the solar cell is preferably high in light transmittance and small in electrical resistance in terms of increasing the energy conversion efficiency of the solar cell.

Conventionally, ITO (Indium Tin Oxide) or SnO ₂ is commonly used as a material for transparent conductive films that meet the above conditions. Etc. were used. However, such a material has a problem in that it is combined with hydrogen during the process to reduce the efficiency of the solar cell later.

On the other hand, in order to increase the efficiency of the solar cell, it is necessary to form a bumpy concave-convex pattern on the transparent conductive film. For this purpose, a chemical vapor deposition method (CVD) induces a change in crystal structure. Method was used.

However, such chemical vapor deposition (CVD) is an expensive process, and has a problem that is not suitable for mass production. In addition, when this expensive chemical vapor deposition method is replaced by a sputtering process, an additional additional etching and polishing process is required.

Therefore, it is urgent to develop a transparent conductive film that can be manufactured by omitting additional etching and polishing processes while using a sputtering process that is relatively inexpensive and suitable for mass production, compared to conventional chemical vapor deposition. It is true.

In order to solve the above problems, the present invention implements a texture structure on the surface of a transparent conductive film using nano powder, thereby improving solar cell efficiency due to a light trap effect, as well as an additional process ( It is a technical object of the present invention to provide a transparent conductive film that can be manufactured by a sputtering process that is inexpensive and suitable for mass production without an etching and polishing process, a solar cell using the same, and a method of manufacturing the same.

In addition, the present invention by using an oxide having excellent hydrogen stability compared to the conventional SnO ₂ , a transparent conductive film that can solve the problem of solar cell efficiency degradation due to hydrogen bonding during the process, a solar cell using the same and a method of manufacturing the same Make it a technical challenge.

According to the spirit of the present invention for achieving the above technical problem, a seed layer in which the nano-powder-type first oxide is dispersed and formed to act as a seed (Seed) of the irregular shape on the glass substrate; And a conductive film layer formed by depositing a second oxide for forming a conductive film on a glass substrate having the seed layer formed thereon.

Preferably, the first oxide may be selected from the group consisting of Antimony Tin Oxide (ATO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O _3, and Sb ₂ O ₃ .

The first oxide is preferably a nano powder having a size of 1 ~ 80nm.

Preferably, the second oxide may be selected from the group consisting of aluminum zinc oxide (AZO), indium tin oxide (ITO), SnO ₂ , In ₂ O _3, and Sb ₂ O ₃ .

Further, according to still another aspect of the present invention, it is possible to provide a solar cell using the above transparent conductive film.

According to still another aspect of the present invention, a) forming a functional layer on the glass substrate for anti-reflection (AR) and metal ion penetration prevention; b) dispersing a nano powder type first oxide on the glass substrate to form a seed layer; And c) depositing a second oxide on the glass substrate on which the seed layer is formed to form a conductive film layer.

Preferably, the step a) comprises: a-1) depositing SiO ₂ on the glass substrate to a thickness of 10 to 100 nm by a sputtering process to form a first functional layer; And a-2) depositing TiO ₂ on the first functional layer to a thickness of 10 to 100 nm by a sputtering process to form a second functional layer.

Preferably, the step b) is 1-1 80nm size selected from the group consisting of b-1) Aluminum Zinc Oxide (AZO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ Preparing a first oxide solution by dissolving the first powder of the nanooxide in a solvent; b-2) coating the first oxide solution on the glass substrate; And b-3) dispersing and forming only the first oxide on the glass substrate through heat treatment.

And c) step c-1) depositing a second oxide selected from the group consisting of aluminum zinc oxide (AZO), indium tin oxide (ITO), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ by a sputtering process. Forming step: may include.

The present invention provides an uneven seed on a glass substrate using nano powder such as antimony tin oxide (ATO), thereby inducing a light trap effect by only a sputtering process without additional etching and polishing processes. It is possible to implement the surface concave-convex shape for, through the cheaper and simpler process than the conventional, there is a technical effect that can produce a high efficiency solar cell.

In addition, the present invention is the problem of the solar cell efficiency is reduced due to the conventional hydrogen bond of SnO ₂ by fabricating a transparent conductive film using an oxide such as excellent hydrogen stability AZO (Aluminum Zinc Oxide) as compared with the conventional SnO ₂ There is a technical effect that can be solved.

Such, the sputtering process in the present invention is inexpensive compared to the conventional chemical vapor deposition (CVD) and suitable for mass production, it also provides an advantageous effect to improve the product competitiveness.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In the drawings, FIG. 1 is a flowchart illustrating an embodiment of a method of manufacturing a transparent conductive film according to the present invention, and FIG. 2 is a diagram illustrating an embodiment of a method of manufacturing a transparent conductive film according to the present invention. 3 is a flowchart illustrating a lower embodiment included in the seed layer forming step S220 in the embodiment of FIG. 2, and FIG. 4 is a seed layer forming step (in the embodiment shown in FIG. 2). S220) and the shape after the conductive film layer deposition step (S240) are photographed by scanning electron microscope (SEM), respectively, and FIG. 5 is a wavelength (λ, unit nm) -light transmittance (%) of the transparent conductive film according to the present invention. Relationship graph.

A preferred embodiment of the transparent conductive film according to the present invention, a solar cell using the same will be described with reference to FIG.

The transparent conductive film used for the solar cell has an uneven shape, that is, a texture is formed on the surface for the purpose of increasing the light efficiency. This is because the texture on the surface induces a light trap effect of the transparent conductive film.

In this embodiment, in order to implement such a texture, a seed layer having a seed layer dispersed on a glass substrate and a conductive layer formed on the glass substrate on which the seed layer is formed are deposited.

The seed layer refers to a first oxide dispersed on a transparent glass substrate, and the first oxide acts as a seed having a concave-convex shape (under the concept of 'seed') in the glass substrate.

The first oxide may be selected from the group consisting of Antimony Tin Oxide (ATO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O _3, and Sb ₂ O _{3. In} this embodiment, ATO nano powder is used. And the first oxide may have a size of 1 ~ 80nm.

Meanwhile, a conductive film layer is deposited on the glass substrate on which the seed layer is formed.

The conductive layer refers to a second oxide deposited on the glass substrate on which the seed layer is formed.

The second oxide is selected from the group consisting of aluminum zinc oxide (AZO), indium tin oxide (ITO), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ through various embodiments according to the spirit of the present invention. In this embodiment, AZO oxide is used.

The AZO oxide is very excellent in hydrogen stability compared to ITO or SnO ₂ which is generally used in the manufacture of a transparent conductive film, it is possible to prevent the problem that the performance is reduced by reacting with hydrogen during the manufacturing process.

Referring to FIG. 1, a preferred embodiment of the present invention described above will be schematically described in terms of process planning. First, as shown in (a) and (b), SiO ₂ and TiO ₂ are formed on a glass substrate. Each is deposited to a thickness of 10 to 100 nm. Such SiO ₂ and TiO ₂ may be referred to as functional layers (individually, SiO ₂ is referred to as a first functional layer and TiO ₂ is referred to as a second functional layer), which may be referred to as anti-reflection (AR) and Metal ion permeation prevention (e.g., prevention of Na component penetration of the glass substrate).

The seed layer may be formed on the functional layer, and as shown in (c), the first oxide solution (eg, ATO solution) dissolved in the solvent is applied by spin coating, and then (d) and Likewise, it is formed by applying a heat treatment. Through this heat treatment, the solvent is removed, and only the first oxide (eg, ATO powder) is dispersed on the glass substrate, thereby providing an uneven texture.

On the glass substrate on which the seed layer is formed, as shown in (e), a second oxide (for example, AZO) is deposited to form a conductive film layer, and the first oxide, which is previously dispersed, is formed as a seed having an uneven shape. ), A transparent conductive film having an uneven pattern texture formed on the surface thereof can be formed. It is obvious that the solar cell using such a transparent conductive film also falls within the scope of the present invention.

Next, a method of manufacturing a transparent conductive film according to the spirit of the present invention will be described with reference to FIGS. 2 to 5 in parallel.

First, a functional layer for anti-reflection (AR) and metal ion penetration prevention is formed on the glass substrate (S200). Here, the functional layer is formed on the upper surface of the glass substrate, and has functions such as antireflection and prevention of penetration of Na component of the glass substrate. In the step S200 according to the preferred embodiment, SiO ₂ is deposited on the functional layer. The first functional layer formed is divided into a second functional layer in which TiO ₂ is deposited.

Each of the first functional layer and the second functional layer may be formed to a thickness of 10 to 100 nm, and the deposition method uses sputtering.

In addition, the seed layer is formed by dispersing the nanopowder-type first oxide on the glass substrate having the functional layer formed thereon (S220). This step (S220) may include a lower implementation step (S300, S320, S340) according to the flowchart shown in FIG.

In order to form the seed layer, the first oxide is dissolved in a solvent to prepare a first oxide solution (S300).

Here, the first oxide may be selected from the group consisting of ATO (Intimony Tin Oxide), ITO (Indium Tin Oxide), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ , having a size of 1 ~ 80nm Nano powder form is good.

In this step (S300) to dissolve the nano-powder-type first oxide in a solvent to prepare a liquid first oxide solution, in this embodiment, an ATO solution is prepared using ATO powder having a size of about 80nm.

Then, the prepared first oxide solution is coated on the glass substrate (S320).

The step S320 is a step of coating the prepared first oxide solution on a glass substrate. In this embodiment, the ATO solution prepared as the first oxide solution is coated by using a spin coating method.

Thereafter, an appropriate heat treatment is applied. The solvent is removed from the first oxide solution coated by the heat treatment, and only the first oxide is dispersed and formed on the glass substrate (S340).

The first oxide dispersed on the glass substrate by the lower step S300, S320, and S340 forms a seed layer.

Referring to FIG. 2 again, a preferred embodiment of the method for manufacturing a transparent conductive film according to the spirit of the present invention will be described. An uneven texture is formed on the glass substrate by the seed layer forming step S220.

FIG. 4A is a photograph taken by a scanning electron microscope (SEM) of an example in which the seed layer is formed by the present step (S220). Referring to a specific embodiment, Figure 4 (a) is a spin coating of the ATO 2wt% solution, and then heated to 80 ℃, to disperse the ATO powder, it is seen that the ATO powder is dispersed evenly formed on the glass substrate. Can be.

The seed layer thus formed serves as a seed during deposition of the conductive layer to be described later, thereby implementing a texture for inducing light traps.

Finally, a second oxide for forming a conductive film is deposited on the glass substrate on which the seed layer is formed to form a conductive film layer (S240).

The second oxide in the step (S240) may be selected from the group consisting of AZO (Aluminum Zinc Oxide), ITO (Indium Tin Oxide), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ , this embodiment Uses AZO oxide. As a method of forming a conductive film on the glass substrate on which the seed layer is formed using the second oxide, all of the well-known deposition methods are generally available. However, it is preferable to use a sputtering deposition method which is relatively inexpensive and easy to mass production. good.

FIG. 4B is a photograph taken by the scanning electron microscope (SEM) of the embodiment in which the conductive film layer is formed by this step (S240). Referring to FIG. 4B, a conductive film is deposited using AZO (ZnO: Al ₂ O ₃ = 98: 2), and irregularities having a size of 1 to 60 nm are formed evenly. It can be seen that the shape is advantageous for the trap (in general, the optimum texture size for light efficiency is known to be about 60 nm).

5 is a relation graph of wavelength (λ, unit nm)-light transmittance (%) of the transparent conductive film according to the present invention.

As shown in FIG. 5, the transparent conductive film prepared according to the present embodiment has a high light transmittance of 90% or more at a wavelength λ of 560 nm.

In addition, it can be seen that the transparent conductive film prepared according to the present embodiment provides a high light transmittance of 70% or more at a wavelength λ of 400 to 800 nm.

Although the present invention has been described with reference to the embodiments shown in the accompanying drawings, it is merely an example, and those skilled in the art will understand that various modifications or equivalent other embodiments are possible therefrom. will be.

Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a flowchart illustrating an embodiment of a method for manufacturing a transparent conductive film according to the present invention.

2 is a flowchart illustrating an embodiment of a method for manufacturing a transparent conductive film according to the present invention.

FIG. 3 is a flowchart illustrating a lower embodiment included in the seed layer forming step S220 in the embodiment of FIG. 2.

4 is a photograph taken by the scanning electron microscope (SEM) of the shape after the seed layer forming step (S220) and the conductive film layer deposition step (S240) in the embodiment shown in FIG.

5 is a relation graph of the wavelength (λ, unit nm)-light transmittance (%) of the transparent conductive film according to the present invention.

Claims (9)

A seed layer in which nano powder-type first oxides are dispersed and formed to act as a seed having a concave-convex shape on a glass substrate; And And a conductive film layer formed by depositing a second oxide for forming a conductive film on the glass substrate on which the seed layer is formed. Transparent conductive film. The method of claim 1, The first oxide is, Characterized in that it is selected from the group consisting of ATO (Antimony Tin Oxide), ITO (Indium Tin Oxide), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ , Transparent conductive film. The method of claim 1, The first oxide is, Characterized in that the nano-powder having a size of 1 ~ 80nm, Transparent conductive film. The method of claim 1, The second oxide, Aluminum Zinc Oxide (AZO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O ₃ And Sb ₂ O _{3 It} characterized in that it is selected from the group consisting of Transparent conductive film. The transparent conductive film in any one of Claims 1-4 is used, Solar cells. a) forming a functional layer on the glass substrate for anti-reflection (AR) and metal ion penetration prevention; b) dispersing a nano powder type first oxide on the glass substrate to form a seed layer; And and c) depositing a second oxide on the glass substrate on which the seed layer is formed to form a conductive film layer. Transparent conductive film manufacturing method. The method of claim 6, Step a) is a-1) forming a first functional layer by depositing SiO ₂ to a thickness of 10 to 100 nm by a sputtering process on the glass substrate; and a-2) forming a second functional layer on the first functional layer by depositing TiO ₂ to a thickness of 10 to 100 nm by a sputtering process; Transparent conductive film manufacturing method. The method of claim 6, B), b-1) Solvent the nano-oxide-type first oxide of 1 ~ 80nm size selected from the group consisting of Antimony Tin Oxide (ATO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ Dissolving to prepare a first oxide solution; b-2) coating the first oxide solution on the glass substrate; And and b-3) dispersing and leaving only the first oxide on the glass substrate through heat treatment. Transparent conductive film manufacturing method. The method of claim 6, C), c-1) depositing and forming a second oxide selected from the group consisting of Aluminum Zinc Oxide (AZO), Indium Tin Oxide (ITO), SnO ₂ , In ₂ O ₃ and Sb ₂ O ₃ by a sputtering process, comprising: Characterized in that, Transparent conductive film manufacturing method.

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