KR101274433B1 - Silicon thin film solar cell manufacturing method and the Silicon thin film solar cell manufactured using the method - Google Patents

Abstract

The present invention relates to a method for manufacturing a silicon thin film solar cell and a silicon thin film solar cell manufactured by the same, the technical problem to be solved is to form a magnesium oxide film between the transparent substrate and the electrode layer, reducing the reflectance between the transparent substrate and the electrode layer At the same time, the diffusion transmittance is increased, thereby increasing the efficiency by reducing the reflectance of the silicon thin film solar cell.

Description

Silicon thin film solar cell manufacturing method and the Silicon thin film solar cell manufactured using the method

The present invention relates to a method for manufacturing a silicon thin film solar cell and a silicon thin film solar cell manufactured through the same.

Solar cells are a key component of photovoltaic power generation that converts sunlight directly into electricity, and its application range is gradually spreading. Among such solar cells, silicon thin film solar cells that can significantly lower the manufacturing cost by depositing and using silicon, which is a light absorption layer, on a transparent substrate such as glass in a thin film form have attracted attention.

Silicon thin film solar cells are the first to be developed and introduced into amorphous silicon (amorphous, a-Si: H) solar cells, and microcrystalline silicon (μc-Si: H) solar cells to improve light absorption efficiency. Batteries and the like. In addition, a silicon thin film solar cell having a tandem structure (a-Si: H / μc-Si: H) formed by stacking two solar cells having different band gaps is used.

The silicon thin film solar cell has been optimized for the characteristics of the silicon thin film itself, and research on improving efficiency in other directions has been actively conducted. Among them, the most important technology for improving the efficiency of silicon thin film solar cells is light trapping, which minimizes the loss of light due to reflection before the incident light is absorbed by the silicon to produce electricity. There is a high interest in the development of silicon thin film solar cells.

The present invention is to overcome the above-mentioned problems, the object of the present invention is to form a magnesium oxide film between the transparent substrate and the electrode layer, reducing the reflectance between the transparent substrate and the electrode layer and at the same time increases the diffusion transmittance, The present invention provides a method for manufacturing a silicon thin film solar cell which can increase efficiency by reducing the reflectance of a silicon thin film solar cell, and a silicon thin film solar cell manufactured through the same.

In order to achieve the above object, a method of manufacturing a silicon thin film solar cell according to the present invention, and a silicon thin film solar cell manufactured through the same, include a magnesium oxide film forming step of forming a magnesium oxide film on a transparent substrate, and Forming a first electrode layer by laminating a first electrode layer, forming a first antireflection film on the first electrode layer, and forming a silicon layer on the first antireflection film And forming a second electrode layer formed by stacking a second electrode layer on the silicon layer.

In the magnesium oxide film forming step, the magnesium oxide film may be formed to a thickness of 20 to 80 nm on the upper surface of the transparent substrate.

In the forming of the magnesium oxide film, the magnesium oxide film may be deposited on the transparent substrate by using an RF magnetron sputter.

The first electrode layer formed in the first electrode layer forming step may be zinc oxide (AZO) doped with aluminum as a transparent electrode layer.

In the first electrode layer forming step, the first electrode layer may be formed on the magnesium oxide film by using a DC magnetron sputter having a thickness of 1 to 1.2 μm.

In the forming of the first electrode layer, after forming the first electrode layer, the top surface of the first electrode layer may be etched with a wet etching solution to form irregularities.

The wet etching solution may be an aqueous hydrogen chloride solution.

The first anti-reflection film may be titanium dioxide (NTO) doped with niobium.

Prior to the forming of the silicon layer, the protective film forming step of forming a protective film for protecting the first anti-reflection film on the first anti-reflection film may be further included.

The passivation layer may be zinc oxide (AZO) doped with aluminum.

The silicon layer may be pin crystalline silicon.

The method may further include a second anti-reflection film forming step of forming a second anti-reflection film on the silicon layer formed in the silicon layer forming step before the second electrode layer forming step.

The second anti-reflection film formed in the step of forming the second anti-reflection film may be a multilayer thin film in which zinc oxide (AZO) doped with aluminum and silver are sequentially stacked.

The second electrode layer formed in the second electrode layer forming step may be aluminum.

The method for manufacturing a silicon thin film solar cell according to the present invention and the silicon thin film solar cell manufactured through the same form a magnesium oxide film between the transparent substrate and the electrode layer, thereby reducing the reflectance between the transparent substrate and the electrode layer and increasing the diffusion transmittance. Therefore, the efficiency can be increased by reducing the reflectance of the silicon thin film solar cell.

1 is a flowchart illustrating a method of manufacturing a silicon thin film solar cell according to an embodiment of the present invention.
2A to 2H are cross-sectional views illustrating respective steps of the method of manufacturing the silicon thin film solar cell of FIG. 1.
3 is an XRD structure analysis waveform diagram of a silicon thin film solar cell manufactured by FIG. 1 and a comparative group.
4 is a surface analysis result diagram of a silicon thin film solar cell manufactured by FIG. 1 and a first electrode layer after wet etching of a comparative group.
FIG. 5 is a result of analyzing optical characteristics of the silicon thin film solar cell manufactured by FIG. 1 and the first electrode layer after the wet etching of the comparative group.
6 is a graph illustrating reflectance measurement results of a silicon thin film solar cell manufactured by FIG. 1 and a first comparison group and a second comparison group.
7 is a result waveform of the EQE of the silicon thin film solar cell manufactured by FIG. 1 and the first and second comparison groups.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. Here, parts having similar configurations and operations throughout the specification are denoted by the same reference numerals.

1, a flowchart illustrating a method of manufacturing a silicon thin film solar cell according to an embodiment of the present invention is shown.

As shown in FIG. 1, the method of manufacturing a silicon thin film solar cell includes a substrate preparation step (S1), a magnesium oxide film forming step (S2), a first electrode layer forming step (S3), a first antireflection film forming step (S4), A protective film forming step (S5), a silicon layer forming step (S6), a second anti-reflective film forming step (S7) and a second electrode layer forming step (S8). Such a method of manufacturing the silicon thin film solar cell will be described in detail with reference to FIGS. 2A to 2H.

First, in the substrate preparation step S1, the flat transparent substrate 110 is cleaned and prepared. The transparent substrate 110 is a glass substrate and has a refractive index of about 1.5.

In the magnesium oxide film forming step S2 illustrated in FIG. 2A, a magnesium oxide film 120 (MgO) is formed on the transparent substrate 110. The magnesium oxide film 120 may be deposited on the upper surface of the transparent substrate 110 by using an RF magnetron sputter. At this time, the magnesium oxide film 120 may be deposited to a thickness of 20nm to 80nm. The magnesium oxide film 120 has a refractive index of about 1.65 to about 1.8. The magnesium oxide film 120 is formed to prevent incident light from being reflected to the outside and light loss.

As shown in FIG. 2B, in the first electrode layer forming step S3, the first electrode layer 130a is stacked on the magnesium oxide film 120. The first electrode layer 130a is made of zinc oxide (hereinafter referred to as "AZO", Al-doped ZnO) doped with aluminum as the transparent electrode layer. The first electrode layer 130 made of AZO has a refractive index of about 1.9 to about 2.0. In addition, the first electrode layer 130a may be deposited on the upper surface of the magnesium oxide film 120 using a DC magnetron sputter. At this time, the first electrode layer 130a may be deposited to a thickness of 1 to 1.2㎛.

In the first electrode layer forming step S3, as illustrated in FIG. 2C, the upper surface of the first electrode layer 130a, which is AZO, stacked on the magnesium oxide film 120 is etched by a wet etching solution for about 1 to 2 minutes. The unevenness 131 is formed to form the first electrode layer 130. In this case, the wet etching solution may be hydrogen chloride (HCl), and an aqueous hydrogen chloride solution diluted to 0.5% to facilitate the formation of unevenness. As such, the magnesium oxide film 120 and the first electrode layer 130 are sequentially stacked on the transparent substrate 110, and the refractive index gradually increases from the transparent substrate 110 to which the light of the solar cell is incident to the inside. Due to the relaxation of the gradient of the refractive index change, the reflectance of light can be reduced as compared with the absence of the magnesium oxide film. The first electrode layer 130 is stacked on the magnesium oxide film 120 to reduce light reflection, which will be described with reference to FIGS. 3 to 5.

Referring to FIG. 3, the magnesium oxide film 120 and the magnesium oxide film on the transparent substrate 110 when the magnesium oxide film 120 and the first electrode layer 130 are sequentially stacked on the transparent substrate 110. The X-ray diffraction (XRD) structure analysis waveform of the comparison group (b) when only the first electrode layer 130 is stacked without the 120 is shown. As shown in FIG. 3, the (002) peak of the present invention group (a) is smaller than that of the comparison group (b) in the XRD structure analysis waveform. That is, in the present invention group (a), the magnesium oxide film 120 is interposed so that the crystallinity of the first electrode layer 130 is weaker than that of the comparison group (b). The crystalline weakening of the first electrode layer 130 is etched by the etching solution of the first electrode layer 130, thereby affecting the formation of unevenness.

Referring to FIG. 4, the magnesium oxide film 120 and the magnesium oxide film on the transparent substrate 110 in the case of sequentially stacking the magnesium oxide film 120 and the first electrode layer 130 on the transparent substrate 110. The surface analysis result after wet etching of the comparison group (b) when only the first electrode layer 130 is stacked without (120) is shown. As shown in FIG. 4, in the present invention group (a), the uneven structure formed on the surface of the first electrode layer 130 after wet etching is better formed than that of the comparison group (b). The uneven structure of the present invention group (a) is better generated because the crystallinity of the first electrode layer 130 formed on the magnesium oxide film 120 is weaker than that of the comparison group (b). In addition, the present invention group (a) can be seen that the size of the groove formed by the unevenness of the first electrode layer 130 is larger than the comparison group (b), which is more advantageous to scatter light to short wavelength and long wavelength It becomes a structure.

Referring to FIG. 5, the magnesium oxide film 120 and the first electrode layer 130 are sequentially stacked on the transparent substrate 110 and on the present invention group a and the transparent substrate 110 after wet etching. The result of analyzing the optical characteristics of the first electrode layer 130 of the comparison group (b), which is the case after lamination with only the first electrode layer 130 without the magnesium oxide film 120 and wet etching, is shown. The optical characteristics may include basic transmittances T_a and Tb incident through the first electrode layer 130 in the direction of the transparent substrate 110, and diffusion transmittances, which are ratios of components of light diffused and spread in the first electrode layer 130. DT_a, DT_b). The optical properties of the present invention group (a) are obtained when the thickness of the magnesium oxide film 120 is 25 nm. As shown in FIG. 5, the basic transmittance (T_a) of the present invention group (a) is similar to the basic transmittance (T_b) of the comparison group (b), but the diffusion transmittance (DT_a) of the present invention group (a) is compared Compared to the diffusion transmittance DT_b of the group (b), it was increased in the entire wavelength band. As described above, the diffusion transmittance DT_a of the present invention group (a) has a concave-convex structure during wet etching, as shown in FIG. Since it can scatter large, it will increase compared with the diffusion transmittance DT_b of the comparative group (b).

As shown in FIG. 2D, the first anti-reflection film forming step S4 forms the first anti-reflection film 140 on the first electrode layer 130. The first anti-reflection film 140 is made of titanium dioxide doped with niobium (hereinafter referred to as "NTO", Nb-doped TiO ₂ ). The first anti-reflection film 140 may be deposited to a thickness of 30 to 50 nm on the upper surface of the first electrode layer 130. In this case, the first antireflection film 140 is formed to have irregularities by the irregularities formed in the first electrode layer 130. The first anti-reflection film 140 is formed to minimize light reflection between the first electrode layer 130 and the silicon layer 160 to be described below.

As shown in FIG. 2E, in the protective film forming step S5, a protective film 150 is formed on the first anti-reflection film 140 to protect the first anti-reflection film 140. The passivation layer 150 may be formed of AZO by depositing a thickness of 8 nm to 12 nm on the first antireflection layer 140. The protective film 150 may be formed on the upper surface of the first anti-reflection film 140 in order to prevent the NTO, which is the first anti-reflection film 140, from being etched by hydrogen plasma during silicon deposition. Is formed.

As illustrated in FIG. 2F, the silicon layer 160 is formed on the top surface of the passivation layer 150 in the step S6. When the silicon layer 160 forms a plurality of amorphous silicon layers (p layer, i layer, n layer), a metal layer is interposed between the p layer and the i layer, and crystallized into a plurality of polycrystalline silicon layers through heat treatment. It may be formed, but the present invention is not limited thereto. The silicon layer 160 is a plurality of polycrystalline silicon layers in which p layers, i layers, and n layers are sequentially arranged, and may be microcrystalline silicon (μc-Si: H) having a pin structure. The silicon layer 160 may be formed to a thickness of 1.5 μm, but is not limited thereto.

As shown in FIG. 2G, in the second anti-reflection film forming step S7, the second anti-reflection film 170 is formed on the silicon layer 160. The second anti-reflection film 170 may be formed of a multilayer thin film in which AZO and silver (Ag) are sequentially stacked. The second antireflection film 170 is formed to minimize light reflection between the silicon layer 160 and the second electrode layer 180 to be described below.

As shown in FIG. 2H, in the second electrode layer forming step S8, the second electrode layer 180 is formed on the second anti-reflection film 170. The second electrode layer 180 may be made of aluminum (Al). As such, the magnesium oxide film 120, the first electrode layer 130, the first antireflection film 140, the protective film 150, the silicon layer 160, the second antireflection film 170, and the like are disposed on the transparent substrate 110. The silicon thin film solar cell 100 may be manufactured by sequentially forming the second electrode layer 180.

Referring to FIG. 6, a first comparative group in which the reflectance x of the silicon thin film solar cell 100 of the present invention and the magnesium oxide film 120 are not formed in the silicon thin film solar cell 100 of the present invention. Reflectance y of the second comparative group when the magnesium oxide film 120 and the first antireflection film 140 are not formed in the structure of the silicon thin film solar cell 100 of the present invention. The measurement result waveform is shown. As shown in FIG. 6, in the case of the reflectance y of the first comparison group, the reflectance is reduced compared to the reflectance z of the second comparison group. In the case of the reflectance x of the silicon thin film solar cell 100 of the present invention, the reflectance y of the first comparative group is significantly reduced compared to the reflectance z of the second comparative group. That is, the silicon thin film solar cell 100 may apply the magnesium oxide film 120 to reduce the reflectance between the transparent substrate 110 and the first electrode layer 130 and increase the diffusion transmittance. Can be reduced.

 Referring to FIG. 7, the external quantum efficiency X (hereinafter referred to as “EQE”, External quantum efficiency) of the silicon thin film solar cell 100 of the present invention, and the magnesium oxide film in the silicon thin film solar cell 100 of the present invention ( 120 is not formed, the EQE (Y) of the first comparison group, and when the magnesium oxide film 120 and the first antireflection film 140 is not formed in the silicon thin film solar cell 100 of the present invention The resulting waveform of EQE (Z) in the second comparison group is shown. As shown in Figure 7, it was measured higher than the EQE (Y) of the first comparison group and the EQE (Z) of the second comparison group of the silicon thin film solar cell 100 of the present invention. That is, it can be seen from the EQE result of FIG. 7 that the efficiency of the silicon thin film solar cell 100 of the present invention is the largest. The cell efficiency of the silicon thin film solar cell 100 of the present invention calculated through such EQE is compared with the cell efficiency of the solar cell when the magnesium oxide film 120 and the first antireflection film 140 are not formed. It can be seen that the increase.

What has been described above is just one embodiment for carrying out the method of manufacturing a silicon thin film solar cell according to the present invention and the silicon thin film solar cell produced by the same, the present invention is not limited to the above embodiment, As claimed in the claims, any person having ordinary skill in the art without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

100; Silicon thin film solar cell
110; Transparent substrate 120; Magnesium oxide membrane
130; A first electrode layer 140; Antireflection film
150; A protective film 160; Silicon layer
170; Second antireflection film 180; Second electrode layer

Claims (15)

A magnesium oxide film forming step of forming a magnesium oxide film on the transparent substrate;
Forming a first electrode layer by laminating a first electrode layer on the magnesium oxide film;
Forming a first anti-reflection film on the first electrode layer;
Forming a silicon layer on the first anti-reflection film; And
And forming a second electrode layer by laminating a second electrode layer on the silicon layer. The method according to claim 1,
In the magnesium oxide film forming step
The magnesium oxide film is formed on the upper surface of the transparent substrate with a thickness of 20 to 80 nm, the manufacturing method of the silicon thin film solar cell. The method according to claim 2,
In the magnesium oxide film forming step
And depositing the magnesium oxide film on the transparent substrate by using an RF magnetron sputter. The method according to claim 1,
The first electrode layer formed in the first electrode layer forming step is a method of manufacturing a silicon thin film solar cell, characterized in that the aluminum oxide doped zinc oxide (AZO) as a transparent electrode layer. The method of claim 4,
In the first electrode layer forming step
The first electrode layer is formed on the upper surface of the magnesium oxide film with a thickness of 1 to 1.2 ㎛ using a DC magnetron sputter, the manufacturing method of a silicon thin film solar cell. The method according to claim 1,
In the first electrode layer forming step
And after forming the first electrode layer, the upper surface of the first electrode layer is etched by a wet etchant to form irregularities. The method of claim 6,
The wet etching solution is a method of manufacturing a silicon thin film solar cell, characterized in that the aqueous solution of hydrogen chloride. The method according to claim 1,
The first anti-reflection film is a method of manufacturing a silicon thin film solar cell, characterized in that the niobium doped titanium dioxide (NTO). The method according to claim 1,
Before forming the silicon layer
And a protective film forming step of forming a protective film for protecting the first anti-reflective film on the first anti-reflective film. The method according to claim 9,
The protective film is a method of manufacturing a silicon thin film solar cell, characterized in that the aluminum oxide doped zinc oxide (AZO). The method according to claim 1,
The silicon layer is a manufacturing method of a silicon thin film solar cell, characterized in that the pin structure of the fine crystal silicon. The method according to claim 1,
Before forming the second electrode layer
And a second anti-reflection film forming step of forming a second anti-reflection film on the silicon layer formed in the silicon layer forming step. The method of claim 12,
The second anti-reflection film formed in the step of forming the second anti-reflection film is a method for manufacturing a silicon thin film solar cell, characterized in that the zinc oxide (AZO) doped with aluminum and a multilayer thin film in which silver is sequentially stacked. The method according to claim 1,
The method of manufacturing a silicon thin film solar cell, wherein the second electrode layer formed in the second electrode layer forming step is aluminum. A silicon thin film solar cell manufactured by the method of manufacturing a silicon thin film solar cell according to any one of claims 1 to 14.

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