KR20120069974A - Photoelectric element and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A photoelectric device and a manufacturing method thereof are provided to reduce an amount of lost charges in a moving process by preventing crystal defects through a photoelectric layer formed on a buffer layer. CONSTITUTION: A first electrode(120) has transmittance and conductivity. The first electrode includes an uneven layer(121) and a buffer layer(122). A photoelectric layer(130) comprises a plurality of semiconductor layers on the first electrode. The photoelectric layer generates electron-hole pairs by absorbing light passing through the substrate and the first electrode. A second electrode(140) has conductivity on the photoelectric layer.

Description

Optoelectronic device and its manufacturing method {PHOTOELECTRIC ELEMENT AND MANUFACTURING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optoelectronic device and a method for manufacturing the same, and more particularly, to an optoelectronic device for converting light energy into electrical energy and a method for manufacturing the same.

The optoelectronic device is a kind of semiconductor device having a p-n junction, and includes a light emitting diode that converts electrical energy into optical energy, a solar cell that absorbs light, and converts the electrical energy into electrical energy. In particular, since solar cells do not cause pollution in generating electrical energy, they are designated as one of the next-generation eco-friendly renewable energy to replace fossil fuels such as coal, oil, and natural gas, which generate carbon dioxide, which is a cause of global warming.

Solar cells are devices that convert light energy into electrical energy using the photoelectric effect. Here, the photoelectric effect is an electron-hole pairs are generated by the light energy absorbed above the bandgap energy, and the photovoltaic power is generated as the electrons and holes move in opposite directions (hereinafter, referred to as photoelectricity). Refers to an effect).

Such solar cells are silicon solar cells, CdTe solar cells (CdTe: Cadmium Telluride, cadmium, telluride compounds), CIGS / CIS solar cells (CIGS: Copper-Indium-Gallum-Selenide, copper) Indium-gallium-selenium compounds, CIS: Copper-Indium-Selenide, and dye-sensitized solar cells.

Among them, CIGS / CIS solar cell is a photoelectric layer formed of copper, indium, gallium, selenium compound / copper, indium, selenium compound, and contains indium, which has increased in price due to the recent shortage of supply. There is a problem that is reduced. CdTe solar cell is a photoelectric layer formed of a cadmium, telluride compound, containing a rare raw material and causing cadmium, there is a problem that is not easy to mass production and has pollution. Dye-sensitized solar cells form a photoelectric layer using a dye (DYE) and an electrolyte (electrolyte) bonded to the nanoscale particle surface. In addition, the silicon solar cell is a photovoltaic layer formed of amorphous silicon (Amorphous Silicon), and can be easily obtained and is based on silicon that is not harmful to humans, and thus has been in the spotlight as the next generation solar cell.

Silicon solar cells may be classified into a first generation including a photoelectric layer formed of crystalline silicon and a second generation including a photoelectric layer formed of amorphous silicon (amorphous-Si) or micro crystalline silicon (micro c-Si). .

First-generation silicon solar cells can absorb light in a wide wavelength range, so the highest photoelectric conversion efficiency (here, "photoelectric conversion efficiency") of the solar cells developed so far is that the light energy incident by the thin film solar cell is electric energy. It means that the ratio is converted to), so it is widely used. However, since the first generation silicon solar cells are manufactured using expensive wafers, the yield is low due to high manufacturing costs.

On the other hand, the thin film solar cell, the second generation solar cell, has a lower manufacturing cost and easier manufacturing process than the first generation solar cell using a substrate made of low-cost glass, metal plate, or plastic instead of expensive wafer, which is suitable for mass production. There is this.

However, since the photoelectric layer of the thin film solar cell is formed in the form of a thin film having a thickness of several μm, the light capture rate (here, “light capture rate” means a rate at which incident light is absorbed in the photoelectric layer) has a disadvantage. In addition, as the photoelectric layer is formed of amorphous silicon, microcrystalline silicon, or the like and includes more crystal defects than crystalline silicon, the amount of electrons and holes lost during transport due to low charge mobility increases. Due to these disadvantages, the conventional thin film solar cell has a problem that it is difficult to improve the photoelectric conversion efficiency.

The present invention is to provide an optoelectronic device and a manufacturing method thereof capable of improving the photoelectric conversion efficiency.

In order to solve this problem, the present invention is a substrate provided to have a transparency; A first electrode on the substrate, the first electrode including a concave-convex layer having an upper surface patterned in an irregularly arranged concave-convex shape and a buffer layer formed in the form of a plurality of lenses on the concave-convex layer and having permeability and conductivity; A photoelectric layer formed of a plurality of semiconductor layers on the first electrode and absorbing light transmitted through the substrate and the first electrode to generate an electron-hole pair; And a second electrode formed on the photoelectric layer to have conductivity.

In addition, the present invention includes a concave-convex layer having an upper surface patterned in the form of irregular concave-convex and a buffer layer having a plurality of lens forms on the concave-convex layer, and forming a first electrode having permeability and conductivity on the substrate Making; Stacking a plurality of semiconductor layers on the first electrode to form a photoelectric layer absorbing light transmitted through the substrate and the first electrode to generate an electron-hole pair; And forming a conductive second electrode on the photoelectric layer.

According to the present invention, the first electrode disposed between the substrate and the photoelectric layer is formed in a structure including an uneven layer and a buffer layer. Here, the uneven layer is formed of a transparent conductive material on the substrate, and includes an upper surface that is patterned in the form of a sharp uneven irregular shape. The buffer layer is formed of conductive polymers aggregated in the form of a plurality of lenses on the uneven layer.

Here, as the buffer layer is disposed between the uneven layer and the photoelectric layer, the photoelectric layer is formed on the buffer layer in the form of a gentle lens instead of the upper surface of the uneven layer having the sharp uneven shape, and thus the photoelectric layer due to the sharp uneven growth surface. Decision defects can be prevented. As the crystal defects in the photoelectric layer are reduced in this way, the charge mobility of the photoelectric layer may be improved, and thus the amount of charge lost during the movement may be reduced, and thus the photoelectric conversion efficiency may be improved.

As the interface between the uneven layer and the buffer layer and the interface between the buffer layer and the photoelectric layer each have an uneven shape, light may be irregularly refracted or scattered at each interface. Therefore, the light trapping amount of the photoelectric layer can be increased, and the photoelectric conversion efficiency can be improved.

1 is a cross-sectional view showing an optoelectronic device according to an embodiment of the present invention.
FIG. 2 is an image showing an upper surface of the uneven layer shown in FIG. 1.
3 is an image showing crystal defects of a semiconductor material grown on a growth surface including sharp unevenness.
4A illustrates an optical path inside an optoelectronic device according to an embodiment of the present invention.
Figure 4b shows the light path of the comparison group.
5 is a flowchart illustrating a method of manufacturing an optoelectronic device according to an embodiment of the present invention.
6 is a flowchart illustrating a step of forming the first electrode illustrated in FIG. 5.
7A to 7F are process diagrams illustrating a method of manufacturing the optoelectronic devices shown in FIGS. 5 and 6.

Hereinafter, an optoelectronic device and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the photovoltaic device 100 according to an exemplary embodiment of the present invention may include a substrate 110 provided to have transparency, and a first electrode 120 formed to have transparency and conductivity on the substrate 110. And a photoelectric layer 130 and a photoelectric layer formed of a plurality of semiconductor layers on the first electrode 120 and absorbing the light transmitted through the substrate 110 and the first electrode 120 to generate an electron-hole pair. The second electrode 140 is formed on the 130 to have conductivity. (Where “top” or “on” is shown as bottom or bottom in FIG. 1)

The substrate 110 may be made of transparent glass or plastic that transmits light, and may be made of a material having flexibility and transparency, such as a film.

The first electrode 120 is formed of a material having transparency and conductivity so that light LIGHT may be transmitted and become a movement path of holes or electrons generated in the photoelectric layer 130.

In addition, the first electrode 120 includes an uneven layer 121 having an upper surface patterned in an irregularly arranged sharp irregular shape, and a buffer layer 122 formed in the form of a plurality of lenses on the uneven layer 121. This will be described later in detail.

The photoelectric layer 130 is formed on the first electrode 120 as a thin film having a thickness of several μm to 500 μm. The photoelectric layer 130 is a structure in which a p-type semiconductor and an n-type semiconductor are bonded (hereinafter referred to as a "pn junction") or a structure in which an i-type semiconductor is sandwiched between a p-type semiconductor and an n-type semiconductor. It consists of a plurality of semiconductor layers comprising one or more (hereinafter referred to as "pin junction").

For example, photoelectric layer 130 may be formed of a single pin junction (also referred to as a "single structure"), a stack of two pin junctions (also referred to as a "tandem structure"), or three Pin junctions may be formed in a stacked form (also referred to as a "triple structure"). Here, at least one p-i-n junction may be formed to absorb light of different wavelength ranges. In this case, as the number of p-i-n junctions constituting the photoelectric layer 130 increases, the wavelength region of light absorbed by the photoelectric layer 130 may be widened, thereby contributing to the improvement of the photoelectric conversion efficiency.

The photoelectric layer 130 is formed of at least one of amorphous silicon (a-Si: amorphous silicon), amorphous silicon-germanium (a-Si: Ge), and micro crystalline silicon (uc-Si: micro crystalline silicon). For example, in the tandem photoelectric layer 130, one of the two pin junctions is formed of amorphous silicon (a-Si) sensitive to light in the wavelength region of 400 nm to 600 nm, and the other is 700 nm-. It may be formed of microcrystalline silicon (uc-Si) sensitive to light in the 800 nm wavelength region.

Although not shown in detail in FIG. 1, at least a portion of the plurality of semiconductor layers constituting the photoelectric layer 130 is transferred to the uneven shape of the upper surface of the buffer layer 122 of the first electrode 120, thereby providing a buffer layer 122. It may have an upper surface that is patterned in a gentle concave-convex shape.

The second electrode 140 is formed to have conductivity. That is, like the first electrode 120, the second electrode 140 may be formed of a transparent conductive material, or may be formed of a metal having conductivity and reflectivity.

When the second electrode 140 is formed of a transparent conductive material like the first electrode 120, although not shown in detail in FIG. 1, the optoelectronic device 100 may be formed of a reflective metal on the second electrode 140. A reflection layer (not shown) may be further included. Alternatively, due to the difference in refractive index between the photoelectric layer 130 and the second electrode 140, light transmitted through the photoelectric layer 130 may be reflected back to the photoelectric layer 130.

As such, a difference in refractive index between the second electrode 140 or the reflective layer (not shown) or the photoelectric layer 130 and the second electrode 140 formed to be reflective on the second electrode 140 is formed to be reflective. As a result, the light passing through the photoelectric layer 130 is reflected and is incident on the photoelectric layer 130 again, so that the light trapping ratio of the photoelectric layer 130 may be increased, thereby improving the photoelectric conversion efficiency. Can be.

Next, the first electrode 120 according to the embodiment of the present invention will be described in more detail.

As mentioned above, the first electrode 120 includes an uneven layer 121 and a buffer layer 122.

As shown in FIG. 2, the uneven layer 121 has a top surface in which a plurality of irregularities having a non-uniform size and pointed shape are patterned in an irregular arrangement or overlapping form. In addition, the uneven layer 121 is a metal oxide of any one of SnO ₂ , ZnO, In ₂ O ₃ and TiO ₂ and the metal oxide is doped with at least one impurity of F, Sn, Al, Fe, Ga and Nb It is selected as a material and has conductivity and permeability.

In addition, in order to minimize the decrease in transmittance of light by the uneven layer 121, the uneven layer 121 may be formed to have a higher refractive index than the substrate 110.

The buffer layer 122 is formed on the uneven layer 121 in the form of a plurality of lenses. In this case, the plurality of lens shapes mean a hemispherical shape or a sphere shape that is convex in the upper direction of the uneven layer 121. In addition, the plurality of lens shapes may be arranged regularly, or may be arranged to overlap each other.

The buffer layer 122 is selected as a conductive polymer material of any one of polyacetylene, polyaniline, polypyrrole, polythiophene, and poly sulfur nitride. It has permeability. In this case, the buffer layer 122 is formed by heating the conductive polymer material applied in a liquid state to agglomerate into a plurality of lens shapes. Alternatively, the buffer layer 122 may be formed by patterning a conductive polymer material applied by using an exposure process using a mask in the form of a plurality of lenses.

In addition, in order to minimize the decrease in transmittance of light by the buffer layer 122, the buffer layer 122 may be formed to have a refractive index higher than that of the uneven layer 121 and lower than that of the photoelectric layer 130.

On the other hand, when using the upper surface of the concave-convex layer 121 having a sharp concave-convex shape as the growth surface of the semiconductor material for forming the photoelectric layer 130, that is, if the semiconductor material is grown directly on the concave-convex layer 121, Due to the sharp concave-convex shape of the layer 121, the growth direction of the semiconductor material is oblique to the substrate 110, and the growth direction is changed for each region. Accordingly, as shown in FIG. 3, the semiconductor material grown on the growth surface of the sharp unevenness includes many crystal defects. In particular, in the case of micro-crystalline silicon (uc-Si) is grown in a direction perpendicular to the growth surface, when the growth surface is a sharp concave-convex shape, such as the concave-convex layer 121, the micro crystalline silicon is perpendicular to the slope of the concave-convex Growing in one direction causes many crystal defects.

These crystal defects lower the charge mobility (here, "charge mobility" means the speed at which holes or electrons move), so that a large amount of electrons and holes generated in the photovoltaic layer 130 in different directions It is lost while transported to the outside through the electrodes (120, 140). That is, the crystal defects cause the charges generated in the photoelectric layer 130 to be lost, thereby degrading the photoelectric conversion efficiency.

However, according to the exemplary embodiment of the present invention, the photoelectric layer 130 is formed on the buffer layer 122 having a form in which a plurality of gentle lenticulars are arranged rather than the top surface of the uneven layer 121. Accordingly, since the photoelectric layer 130 is formed of a semiconductor material grown on the upper surface of the buffer layer 122 that does not include a sharp region, crystal defects generated in the photoelectric layer 130 may be reduced. Therefore, deterioration in electrical characteristics of the photoelectric layer due to crystal defects can be minimized, and the photoelectric conversion efficiency can be improved.

In addition, according to the embodiment of the present invention, as the first electrode 120 has a laminated structure of the uneven layer 121 and the buffer layer 122 having different uneven shapes, the light is refracted at the interface between each layer or Scattered.

That is, as shown in Figure 4a, according to an embodiment of the present invention, the light (LIGHT) transmitted through the substrate 110 is irregular first on the upper surface of the uneven layer 121 is patterned in the form of a sharp irregularities arranged irregularly After being refracted or scattered, irregularly refracted or scattered in the buffer layer 122 having a plurality of lens shapes. As a result, an effect of increasing the area where light is incident on the photoelectric layer 130 may be generated, thereby increasing an opportunity for the photoelectric layer 130 to capture light.

In contrast, as shown in FIG. 4B, in the case of the comparative group 10 including the first electrode 12 formed only of a transparent conductive material having an upper surface patterned in the shape of a sharp convex and concave, the light transmitted through the substrate 11. (LIGHT) is refracted or scattered only at an interface between the upper surface of the first electrode 12 having a sharp uneven shape and the photoelectric layer 13.

As described above, according to the exemplary embodiment of the present invention, the light LIGHT is refracted or scattered by two times by the uneven layer 121 and the buffer layer 122 until the light is incident on the photoelectric layer 120. Therefore, according to the exemplary embodiment of the present invention, the light scattering rate (corresponding to Haze) of the first electrode 120 is higher than that of the first electrode 12 of the comparison group 10, so that the photoelectric layer 130 captures light. The opportunity to increase can be increased higher than that of the comparison group 10, whereby the photoelectric conversion efficiency can be improved.

Next, a method of manufacturing an optoelectronic device according to an embodiment of the present invention will be described.

As shown in FIG. 5, in the method of manufacturing an optoelectronic device according to an embodiment of the present invention, forming a first electrode including an uneven layer and a buffer layer on a substrate (S100), and forming a photoelectric layer on the first electrode. Forming a second electrode on the photoelectric layer (S110);

And, as shown in Figure 6, the step of forming the first electrode (S100) is a step of forming a first material layer by laminating a transparent conductive material on a substrate (S101), irregular top surface of the first material layer Forming a concave-convex layer by patterning the concave-convex concave-convex shape (S102), laminating a conductive polymer material on the concave-convex layer to form a second material layer (S103), and forming the second material layer in the form of a plurality of lenses. Patterning to form a buffer layer (S104).

As shown in FIG. 7A, a substrate 110 having transparency is provided, and a first conductive layer 121m is formed by stacking a transparent conductive material on the substrate 110. Here, the first material layer 121m may be a metal oxide of any one of SnO ₂ , ZnO, In ₂ O _3, and TiO ₂ and at least one of F, Sn, Al, Fe, Ga, and Nb in the metal oxide. Is selected as the doped material. In addition, the first material layer 121m may be formed by a vacuum deposition method.

As shown in FIG. 7B, the upper surface of the first material layer 121m is patterned in the form of pointed irregularities irregularly arranged to form the uneven layer 121. In this case, the pattern of the first material layer 121m may be performed by a wet etching process having anisotropic etching characteristics.

Subsequently, as illustrated in FIG. 7C, the conductive polymer material is stacked on the uneven layer 121 to form the second material layer 122m. Here, the second material layer 122m may be conductive of any one of polyacetylene, polyaniline, polypyrrole, polythiophene, and poly sulfur nitride. It is selected as a polymeric material.

The second material layer 122m may be formed by applying a liquid conductive polymer material. In this case, the coating of the conductive polymer material may be performed by any one of spin coating, slit coating, ink jet printing, and in panel printing.

Next, as shown in FIG. 7D, as the buffer layer 122 is formed by patterning the second material layer 122m in the form of a plurality of lenses, the first electrode 120 is formed. In this case, the pattern of the second material layer 122m may be performed by an exposure process using the mask 200.

Alternatively, although not separately illustrated, the pattern of the second material layer 122m may be performed by agglomerating a liquid conductive polymer material through heating.

Subsequently, as illustrated in FIG. 7E, a plurality of semiconductor layers are stacked on the first electrode 120 to form a photoelectric layer 130 (S110), and as illustrated in FIG. 7F, the photoelectric layer 130. A second electrode 140 having conductivity is formed on the substrate. (S120)

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes may be made without departing from the technical spirit of the present invention.

100: photoelectric device 110: substrate
120: first electrode 121: uneven layer
122: buffer layer 130: photoelectric layer
140: second electrode 200: mask

Claims (11)

A substrate provided to have transparency;
A first electrode on the substrate, the first electrode including a concave-convex layer having an upper surface patterned in an irregularly arranged concave-convex shape and a buffer layer formed in the form of a plurality of lenses on the concave-convex layer and having permeability and conductivity;
A photoelectric layer formed of a plurality of semiconductor layers on the first electrode and absorbing light transmitted through the substrate and the first electrode to generate an electron-hole pair; And
And a second electrode formed to have conductivity on the photoelectric layer. The method of claim 1, wherein the uneven layer is at least one of F, Sn, Al, Fe, Ga and Nb in the metal oxide of any one of SnO ₂ , ZnO, In ₂ O ₃ and TiO ₂ and the metal oxide Optoelectronic device selected as the doped material. The method of claim 1, wherein the buffer layer is selected as a conductive polymer of any one of polyacetylene, polyaniline, polypyrrole, polythiophene and poly sulfur nitride. Photoelectric device. The photoelectric device of claim 1, wherein the uneven layer has a higher refractive index than the substrate, and the buffer layer has a higher refractive index than the uneven layer. The photoelectric device of claim 1, wherein the photoelectric layer is formed of at least one of amorphous silicon (a-Si), amorphous silicon-germanium (a-Si: Ge), and micro-crystal silicon (micro c-Si). Forming a first electrode having a permeability and a conductive layer having a plurality of lens shapes on the concave-convex layer having an upper surface patterned in an irregularly arranged sharp concave-convex shape, and having permeability and conductivity on the substrate;
Stacking a plurality of semiconductor layers on the first electrode to form a photoelectric layer absorbing light transmitted through the substrate and the first electrode to generate an electron-hole pair; And
Forming a conductive second electrode on the photoelectric layer. The method of claim 6,
Forming the first electrode,
Stacking a transparent conductive material on the substrate to form a first material layer;
Patterning the upper surface of the first material layer in the form of pointed irregularities irregularly arranged to form the irregularities layer;
Stacking a conductive polymer material on the uneven layer to form a second material layer; And
Patterning the second material layer in the form of a plurality of lenses to form the buffer layer. The method of claim 7, wherein in the forming of the buffer layer, heat is applied to the second material layer to aggregate the conductive polymer material into the plurality of lens shapes. The method of claim 7, wherein the forming of the buffer layer is performed by an exposure process using a mask. The method of claim 7, wherein in the forming of the first material layer, the first material layer is formed of any one of metal oxides of SnO ₂ , ZnO, In ₂ O ₃ and TiO ₂ and the metal oxides of F, Sn, A method for manufacturing an optoelectronic device, wherein at least one of Al, Fe, Ga, and Nb is doped. 8. The method of claim 7, wherein in forming the second material layer, the second material layer comprises polyacetylene, polyaniline, polypyrrole, polythiophene and polysulfurnitride. A method of manufacturing an optoelectronic device selected from any one of conductive polymer materials of (poly sulfur nitride).

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