KR101081229B1 - Methode of fabricating solar cell - Google Patents

Abstract

Disclosed is a method of manufacturing a solar cell. A method of manufacturing a solar cell includes forming a back electrode layer on a support substrate; Forming a light absorbing layer on the back electrode layer; Forming an active layer including a surfactant on the light absorbing layer; Forming a buffer layer on the active layer; And forming a window layer on the buffer layer.

Surfactant, activator, sodium, buffer, cadmium, ionic

Description

Manufacturing method of solar cell {METHODE OF FABRICATING SOLAR CELL}

The embodiment relates to a method of manufacturing a solar cell.

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.

Embodiments provide a method of manufacturing a solar cell including a buffer layer having improved characteristics.

According to one or more exemplary embodiments, a method of manufacturing a solar cell includes forming a back electrode layer on a support substrate; Forming a light absorbing layer on the back electrode layer; Forming an active layer including a surfactant on the light absorbing layer; Forming a buffer layer on the active layer; And forming a window layer on the buffer layer.

According to one or more exemplary embodiments, a method of manufacturing a solar cell includes forming a back electrode layer on a support substrate; Forming a light absorbing layer on the back electrode layer; Immersing the light absorbing layer in a solution containing a surfactant to form a buffer layer on the light absorbing layer; And forming a window layer on the buffer layer.

In the solar cell manufacturing method according to the embodiment, the active layer or the surfactant may be used to improve the characteristics of the buffer layer. That is, the active layer is formed between the light absorbing layer and the buffer layer, it is possible to suppress the generation of bubbles in the process of forming the buffer layer. In addition, a surfactant may be included in the solution for forming the buffer layer, and the surfactant may suppress generation of bubbles in the process of forming the buffer layer.

In addition, the surfactant included in the solution or active layer may comprise sodium. Therefore, in a subsequent process, sodium contained in the surfactant is diffused into the light absorbing layer, so that the electrical properties of the light absorbing layer can be improved.

Therefore, the manufacturing method of the solar cell according to the embodiment can provide a solar cell of improved performance.

In the description of the embodiments, where each substrate, layer, region, or electrode is described as being formed "on" or "under" of each substrate, layer, region, or electrode, or the like. Thus, "on" and "under" include both "directly" or "indirectly" formed 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 to 5 are cross-sectional views illustrating a process for manufacturing a solar cell according to the embodiment.

Referring to FIG. 1, a metal such as molybdenum is deposited on the support substrate 100 by a sputtering process, and a back electrode layer 200 is formed. The back electrode layer 200 may be formed by two processes having different process conditions.

An additional layer such as a diffusion barrier may be interposed between the support substrate 100 and the back electrode layer 200.

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 (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.

2, the light absorbing layer 300 is formed on the back electrode layer 200.

The light absorbing layer 300 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 300. The method of forming the light absorbing layer 300 and the method of forming the metal precursor film 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.

Subsequently, the metal precursor film is formed of a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) light absorbing layer 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 optical absorption layer 300 can be formed by using only a copper target and an indium target, or by a sputtering process and a selenization process using a copper target and a gallium target.

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 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.

Thereafter, a surfactant is sprayed on the light absorbing layer 300. The surfactant has hydrophilicity and may be, for example, a cationic surfactant or a nonionic surfactant.

Examples of the material used as the surfactant include sodium palmitate (CH ₃ (CH ₂ ) ₁₄ CO ₂ Na), polyoxyethylene (POE), alcohol ethoxylate, fatty acid Toxylate or nonyl phenyl ethoxylate, etc. are mentioned.

The surfactant may be used diluted in water. That is, the surfactant may be diluted in water at a concentration of about 100 ppm to about 10000 ppm and sprayed onto the light absorbing layer 300.

Thereafter, the upper surface of the light absorbing layer 300 is cleaned. In this case, as shown in FIG. 3, the active layer 310, which is a very thin film made of the surfactant, remains on the upper surface of the light absorbing layer 300.

By the active layer 310, the surface characteristics of the upper surface of the light absorbing layer 300 is improved.

As shown in FIG. 4, a buffer layer 400 is formed on the light absorbing layer 300.

The buffer layer 400 may be formed by chemical bath depositon (CBD).

In order to form the buffer layer 400, an aqueous solution in which ions are supersaturated for forming the buffer layer 400 may be manufactured. For example, the aqueous solution is Cd ^{+ 2,} and S ^{2 -} may comprise a supersaturated state.

In more detail, the aqueous solution may include cadmium acetate and thiourea, and may further include a buffer and ammonia.

Thereafter, the light absorbing layer 300 is dipped in the aqueous solution. That is, the light absorbing layer 300 is in direct contact with the aqueous solution, and by the chemical reaction, the buffer layer 400 is formed on the light absorbing layer 300. In this case, the reaction temperature may be about 60 ℃ to about 80 ℃. In addition, the reaction time may be from about 10 minutes to about 15 minutes.

Although not shown in FIG. 4, the active layer 310 may still remain between the buffer layer 400 and the light absorbing layer 300.

Referring to FIG. 5, zinc oxide is deposited on the buffer layer 400 by a sputtering process, and the high resistance buffer layer 500 is formed.

Thereafter, the window layer 600 is formed on the high resistance buffer layer 500. In order to form the window layer 600, a transparent conductive material is stacked on the high resistance buffer layer 500. Examples of the transparent conductive material include aluminum doped zinc oxide and the like.

The buffer layer 400 may be uniformly formed on the hydrophobic part and the rough part of the upper surface of the light absorbing layer 300 by the active layer 310. In addition, bubbles generated in the process of forming the buffer layer 400 may be suppressed.

Accordingly, even if the thickness of the buffer layer 400 becomes thin, defects such as pin-holes and the like may be reduced. That is, as the thickness of the buffer layer 400 becomes thin, the amount of cadmium used can be reduced, and manufacturing cost and environmental treatment cost can be reduced.

In addition, as the surfactant, a material containing sodium such as sodium palmitate may be used. In this case, sodium included in the active layer 310 may further improve the characteristics of the light absorbing layer 300.

Therefore, the manufacturing method of the solar cell according to the embodiment can provide a solar cell of improved performance.

By the method for manufacturing a solar cell according to the present embodiment, the manufactured solar cell can be detected even if the amount of the surfactant is small. In particular, since the surfactant includes carbon and / or hydrogen, etc., by the solar cell manufacturing method according to the present embodiment, carbon and / or hydrogen may be detected in the manufactured solar cell. In particular, elements included in the surfactant may be detected in the light absorbing layer 300 and / or the buffer layer 400.

6 and 7 are cross-sectional views illustrating a method of manufacturing a solar cell according to another embodiment. In the present embodiments, with reference to the above-described embodiments, the aqueous solution will be further described. The foregoing description of the photovoltaic device may be essentially combined with the description of the photovoltaic device according to the present embodiment, except for the changed part.

Referring to FIG. 6, as in the above-described embodiment, the back electrode layer 200 and the light absorbing layer 300 are sequentially formed on the support substrate 100.

Referring to FIG. 7, a buffer layer 400 is formed on the light absorbing layer 300. In this case, the active layer 310 of the previous embodiment is not formed on the upper surface of the light absorbing layer 300.

In order to form the buffer layer 400, an aqueous solution for forming the buffer layer 400 is manufactured. The aqueous solution further includes a surfactant as well as ions for forming the buffer layer 400. The surfactant may be included at a concentration of about 100 ppm to about 1000 ppm.

That is, the aqueous solution is not only cadmium acetate, thiourea, buffer and ammonia, but also sodium palmitate (CH ₃ (CH ₂ ) ₁₄ CO ₂ Na), polyoxyethylene POE), alcohol ethoxylate, fatty acid ethoxylate or nonylphenyl ethoxylate, and the like.

Thereafter, the light absorbing layer 300 is dipped in the aqueous solution, so that the buffer layer 400 is formed on the light absorbing layer 300.

Since the surfactant is included in the aqueous solution, the buffer layer 400 may be uniformly formed in the hydrophobic part and the rough part of the upper surface of the light absorbing layer 300. In addition, bubbles generated in the process of forming the buffer layer 400 may be suppressed.

Accordingly, even if the thickness of the buffer layer 400 becomes thin, defects such as pin-holes and the like may be reduced. That is, as the thickness of the buffer layer 400 becomes thin, the amount of cadmium used can be reduced, and manufacturing cost and environmental treatment cost can be reduced.

In addition, as the surfactant, a material containing sodium such as sodium palmitate may be used. In this case, sodium included in the active layer 310 may further improve the characteristics of the light absorbing layer 300.

In addition, since the surfactant is included and used in the aqueous solution, a step and a washing step for spraying the surfactant are not required.

Therefore, the manufacturing method of the solar cell according to the present embodiment can easily produce a solar cell.

In addition, 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.

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 to 5 are cross-sectional views illustrating a process for manufacturing a solar cell according to the embodiment.

6 and 7 are cross-sectional views illustrating a method of manufacturing a solar cell according to another embodiment.

Claims (10)

Forming a back electrode layer on the support substrate; Forming a light absorbing layer on the back electrode layer; After the light absorbing layer is formed, forming an active layer including a surfactant on the light absorbing layer; Forming a buffer layer on the active layer; And Forming a window layer on the buffer layer manufacturing method of a solar cell. The method of claim 1, wherein the surfactant comprises sodium. The method of claim 1, wherein the surfactant is sodium palmitate (CH ₃ (CH ₂ ) ₁₄ CO ₂ Na), polyoxyethylene (POE), alcohol ethoxylate (alcohol ethoxylate), fatty acid Method for producing a solar cell comprising ethoxylate or nonyl phenyl ethoxylate. Forming a back electrode layer on the support substrate; Forming a light absorbing layer on the back electrode layer; Forming an active layer including a surfactant on the light absorbing layer; Forming a buffer layer on the active layer; And Forming a window layer on the buffer layer, Forming the active layer includes spraying a surface active layer on the light absorbing layer, Forming the buffer layer is a method of manufacturing a solar cell comprising the step of dipping the light absorbing layer formed with the active layer in a solution containing cadmium. Forming a back electrode layer on the support substrate; Forming a light absorbing layer on the back electrode layer; Dipping the light absorbing layer into a solution containing a surfactant to form a buffer layer on the light absorbing layer; And The method of manufacturing a solar cell comprising the step of forming a window layer on the buffer layer. The method of claim 5, wherein the surfactant is sodium palmitate (CH ₃ (CH ₂ ) ₁₄ CO ₂ Na), polyoxyethylene (POE), alcohol ethoxylate (alcohol ethoxylate), fatty acid Manufacturing method of solar cell containing ethoxylate or nonyl phenyl ethoxylate The method of claim 5, wherein the surfactant comprises sodium. The method of claim 5, wherein the solution comprises cadmium. Support substrate; A back electrode layer disposed on the support substrate; A light absorbing layer disposed on the back electrode layer; A buffer layer disposed on the light absorbing layer; A window layer disposed on the buffer layer; And A solar cell interposed between an upper surface of the light absorbing layer and a lower surface of the buffer layer, the solar cell including an active layer containing a surfactant. The solar cell of claim 9, wherein the surfactant comprises sodium palmitate (CH ₃ (CH ₂ ) ₁₄ CO ₂ Na).

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