KR20130059972A - Solar cell and method of fabricating the same - Google Patents

Abstract

PURPOSE: A solar cell and a method for fabricating the same are provided to prevent moisture and oxygen from penetrating into the solar cell by forming a hydrophobic particle layer on an interface. CONSTITUTION: A back electrode layer(200) is arranged on a support substrate(100). A light absorption layer(300) is arranged on the back electrode layer. A buffer layer(400) is arranged on the light absorption layer. A hydrophobic particle layer(600) is arranged on the buffer layer. A front electrode layer(700) is arranged on the hydrophobic particle layer.

Description

SOLAR CELL AND METHOD OF FABRICATING THE SAME

An embodiment relates to a solar cell 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.

CIGS solar cells must be resistant to moisture (H ₂ O) or oxygen (O ₂ ) from the outside, and solving these reliability problems is one of the important factors in CIGS solar cell performance. When CIGS solar cells are exposed to moisture, cracks or flaking occur in the CIGS film, and the CIGS composition is also changed. In addition, CIGS solar cells exposed to moisture not only increases the reflectivity but also lowers the efficiency.

The embodiment is to provide a solar cell and a manufacturing method thereof having improved reliability and stability, and improved photoelectric conversion efficiency.

A solar cell according to an embodiment includes: a rear electrode layer disposed on a supporting substrate; A light absorbing layer disposed on the rear electrode layer; A buffer layer disposed on the light absorbing layer; A high resistance buffer layer disposed on the buffer layer; A hydrophobic particle layer disposed on the high resistance buffer layer; And a front electrode layer disposed on the hydrophobic particle layer.

A method of manufacturing a solar cell according to an embodiment includes forming a rear electrode layer on a supporting substrate; Forming a light absorbing layer on the back electrode layer; Forming a buffer layer on the light absorbing layer; Forming a high resistance buffer layer on the buffer layer; Forming a hydrophobic particle layer on the high resistance buffer layer; And forming a front electrode layer on the hydrophobic particle layer.

The solar cell according to the embodiment may minimize the penetration of moisture (H ₂ O) or oxygen (O ₂ ) into the solar cell along the interface by providing a hydrophobic particle layer. Accordingly, the solar cell according to the embodiment effectively contributes to securing the stability and reliability of the device by effectively protecting the solar cells from moisture and oxygen. In addition, when water flows down in the hydrophobic particle layer, contaminants also flow along, which has the effect of self-cleaning.

1 to 5 are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment.

In the description of the embodiments, where each substrate, layer, film, or electrode is described as being formed "on" or "under" of each substrate, layer, film, or electrode, etc. , “On” and “under” include both “directly” or “indirectly” 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 method of manufacturing a solar cell according to an embodiment. Hereinafter, a solar cell and a method of manufacturing the same according to an embodiment will be described in detail with reference to FIGS. 1 to 5.

Referring to FIG. 1, the back electrode layer 200 is formed on the support substrate 100. The support 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, the hydrophobic particle layer 600, and the front electrode layer 700. do.

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. In addition, the support substrate 100 may be rigid or flexible. In more detail, the support substrate 100 may be a flexible substrate.

The back electrode layer 200 is disposed on the support substrate 100. The back electrode layer 200 may be formed by physical vapor deposition (PVD) or plating.

The back electrode layer 200 is 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). Among them, in particular, molybdenum (Mo) has a smaller difference between the support substrate 100 and the coefficient of thermal expansion than other elements, and thus it is possible to prevent the occurrence of peeling due to excellent adhesion.

Referring to FIG. 2, the light absorbing layer 300 is disposed on the back electrode layer 200. The light absorption layer 300 includes an 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, 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 300 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 (300) and the method of forming a metal precursor film and forming it by the selenization process are used widely.

When the metal precursor film is formed and selenization is subdivided, a metal precursor film is formed on the back electrode 300 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-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.

Referring to FIG. 3, the buffer layer 400 and the high resistance buffer layer 500 are sequentially disposed on the light absorbing layer 300.

The buffer layer 400 includes cadmium sulfide, ZnS, In _x S _y, and In _x Se _y Zn (O, OH). The buffer layer 400 may be formed by depositing cadmium sulfide on the light absorbing layer 300 by chemical bath deposition (CBD). The high resistance buffer layer 500 may deposit zinc oxide on the buffer layer 400 by a sputtering process. For example, the high resistance buffer layer 500 may be zinc oxide (i-ZnO) that is not doped with impurities.

Referring to FIG. 4, the hydrophobic particle layer 600 is disposed on the high resistance buffer layer 500. The hydrophobic particle layer 600 may be formed of a plurality of hydrophobic particles 610. In addition, each of the hydrophobic particles 610 may be formed of an oxide particle 611 and a hydrophobic layer 612 surrounding the oxide particle. That is, the hydrophobic particles 610 may have a core-shell structure composed of an oxide particle 611 and a hydrophobic film 612.

The thickness of the hydrophobic particle layer 600 may be about 1 nm to about 10 nm, and more specifically, the thickness of the hydrophobic particle layer 600 may be about 5 nm to about 10 nm, but is not limited thereto. In addition, the average diameter of the hydrophobic particles 610 may be 1 nm to 10 nm, and more specifically, the average diameter of the hydrophobic particles 610 may be about 5 nm to about 10 nm, but is not limited thereto. It is not. In addition, although only a single layer of hydrophobic particle layer 600 is disclosed in FIG. 4, the embodiment is not limited thereto. That is, multiple layers of hydrophobic particles may also be included in the examples herein.

The oxide particles 611 may be formed of the same material as the high resistance buffer layer 500. In more detail, the oxide particles 611 may be formed of the same material as the high resistance buffer layer 500. For example, each of the oxide particles 611 and the buffer layer 500 may be formed of zinc oxide (i-ZnO) that is not doped with impurities.

The hydrophobic film 612 surrounds the oxide particle 611. In addition, the hydrophobic layer 612 may include a silane compound represented by Formula 1 below.

[Formula 1]

R ₁ -Si (X) ₃

In Formula 1, R ₁ and X are each independently a hydrogen atom; A halogen atom; A hydroxy group; A substituted or unsubstituted C1-C20 alkyl group; Substituted or unsubstituted C2-C20 alkenyl group; Substituted or unsubstituted C2-C20 alkynyl group; Substituted or unsubstituted C6-C20 aryl group; A substituted or unsubstituted C6-C20 arylalkyl group; Substituted or unsubstituted C1-C20 alkoxy group; It may include a substituted or unsubstituted C6-C20 aryloxy group. In more detail, R ₁ is a substituted or unsubstituted C1-C20 alkyl group; Substituted or unsubstituted C2-C20 alkenyl group; Substituted or unsubstituted C2-C20 alkynyl group; Substituted or unsubstituted C6-C20 aryl group; A substituted or unsubstituted C6-C20 arylalkyl group; Substituted or unsubstituted C1-C20 alkoxy group; It may be a substituted or unsubstituted C6-C20 aryloxy group, X may be a halogen atom, for example, chlorine (Cl), but is not limited thereto.

In one embodiment, the hydrophobic layer 612 may be octadecyltrichlorosilane (OTS), octadecyltriethoxysilane, phenyloxyundecyltrimethoxysilane, or (heptadecafluoro-1,1, 2,2-tetrahydrodecyl) triethoxysilane. In more detail, the hydrophobic layer 612 may be formed of octadecyltrichlorosilane (OTS), but is not limited thereto.

The hydrophobic particle layer 600 may be manufactured by various methods. In one embodiment, the hydrophobic particle layer 600 is prepared a mixed solvent comprising a hydrophobic material and an organic solvent, dispersing oxide particles 611 in the mixed solvent, and applying the mixed solvent on the high resistance buffer layer It may be prepared by coating a hydrophobic film 612 on the oxide particles by heat treatment, but is not limited thereto.

More specifically, the hydrophobic material may be used without particular limitation as long as it is a material represented by the above-mentioned formula (1). For example, octadecyltrichlorosilane may be used as the hydrophobic material, but is not limited thereto. In addition, the solvent used herein may be a solvent capable of dissolving the hydrophobic material, for example, an aliphatic hydrocarbon solvent, an aromatic hydrocarbon solvent, a ketone solvent, an ether solvent, an acetate solvent, an alcohol solvent, an amide solvent, At least one selected from the group consisting of silicone solvents and mixtures of the above solvents may be used. For example, toluene may be used as the solvent. Thereby, an octadecyl trichlorosilane-toluene mixed solution can be manufactured.

Thereafter, the oxide particles 611 are dispersed in the mixed solution and stirred using an ultrasonic cleaner. Thereafter, a mixed solution including the oxide particles 611 is applied to the high resistance buffer layer 500. At this time, the mixed solution may be applied by a wet coating method selected from the group consisting of immersion method, spray method, spin coating method, and printing method. Subsequently, the mixed solution may be heat-treated to selectively evaporate the solvent, thereby coating the hydrophobic film 612 on the oxide particles 611. The heat treatment process may be performed at about 100 ℃ to about 200 ℃.

The hydrophobic particle layer 600 manufactured by the above-mentioned method may have a contact angle with water of about 90 ° to about 150 °, but is not limited thereto.

As described above, in the solar cell according to the embodiment, the hydrophobic particle layer 600 is formed on the high resistance buffer layer 500, so that external moisture or water droplets do not penetrate into the hydrophobic particle layer 600, and the hydrophobic particle layer 600 is formed. Flow along the surface of the Therefore, it is possible to minimize the penetration of moisture (H ₂ O) or oxygen (O ₂ ) into the solar cell through the interface. In addition, when water flows down from the hydrophobic particle layer 600, contaminants may also flow together to have a self-cleaning effect, and solar cell efficiency may be improved.

Referring to FIG. 5, the front electrode layer 700 is disposed on the hydrophobic particle layer 600. The front electrode layer 700 may be formed of a transparent conductive material. In addition, the front electrode layer 700 may have characteristics of an n-type semiconductor. In this case, the front electrode layer 700 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 700 may be formed of, for example, aluminum doped zinc oxide (AZO).

The front electrode layer 700 may be manufactured by stacking a transparent conductive material on the hydrophobic particle layer 600. Examples of the transparent conductive material include zinc oxide doped with aluminum or boron. The process for forming the front electrode layer 700 may be performed at room temperature to about 300 ℃. For example, the front electrode layer 700 may be manufactured by sputtering or chemical vapor deposition. In more detail, in order to form the front electrode layer 700 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.

Features, structures, effects, and the like described in the above 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 each embodiment 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 (12)

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;
A high resistance buffer layer disposed on the buffer layer;
A hydrophobic particle layer disposed on the high resistance buffer layer; And
A solar cell comprising a front electrode layer disposed on the hydrophobic particle layer.
The method of claim 1,
The hydrophobic particle layer includes a plurality of hydrophobic particles,
Each of the hydrophobic particles comprises an oxide particle and a hydrophobic film surrounding the oxide particle.
3. The method of claim 2,
The hydrophobic film is a solar cell comprising a silane compound represented by the following formula (1):
[Formula 1]
R ₁ -Si (X) ₃
Each independently represent a hydrogen atom; a halogen atom; a hydroxy group; a substituted or unsubstituted C1-C20 alkyl group; a substituted or unsubstituted C2-C20 alkenyl group; a substituted or unsubstituted C2-C20 alkynyl group Substituted or unsubstituted C6-C20 aryl group substituted or unsubstituted C6-C20 arylalkyl group substituted or unsubstituted C1-C20 alkoxy group; substituted or unsubstituted C6-C20 aryloxy group do).
3. The method of claim 2,
The hydrophobic film may be octadecyltrichlorosilane (OTS), octadecyltriethoxysilane, phenyloxyundecyltrimethoxysilane, or (heptadecafluoro-1,1,2,2-tetrahydrodecyl) tree Solar cell formed of ethoxysilane.
The method of claim 1,
The oxide particles are formed of the same material as the high resistance buffer layer.
The method of claim 5, wherein
Each of the oxide particles and the high resistance buffer layer includes zinc oxide (i-ZnO) that is not doped with impurities.
3. The method of claim 2,
The average diameter of the hydrophobic particles is 1 nm to 10 nm solar cell.
The method of claim 1,
The thickness of the hydrophobic particle layer is 1 nm to 10 nm solar cell.
The method of claim 1,
The hydrophobic particle layer is a solar cell comprising a contact angle to the water 90 ° to 150 °.
Forming a back electrode layer on the support substrate;
Forming a light absorbing layer on the back electrode layer;
Forming a buffer layer on the light absorbing layer;
Forming a high resistance buffer layer on the buffer layer;
Forming a hydrophobic particle layer on the high resistance buffer layer; And
A method of manufacturing a solar cell comprising forming a front electrode layer on the hydrophobic particle layer.
11. The method of claim 10,
Forming the hydrophobic particle layer,
Preparing a mixed solvent comprising a hydrophobic material and an organic solvent,
Oxide particles are dispersed in the mixed solvent,
Coating the mixed solvent on the high resistance buffer layer, and heat treatment to coat a hydrophobic film on the oxide particles.
The method of claim 11,
The mixed solvent is a solar cell manufacturing method is applied by a wet coating method selected from the group consisting of a deposition method, a spray method, a spin coating method, and a printing method.

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