KR101091384B1 - Solar cell and method of fabricating the same - Google Patents

Abstract

A solar cell and a method of manufacturing the same are disclosed. Solar cell is a transparent substrate; A window layer disposed on the transparent substrate; A plurality of light absorbing rods disposed on the window layer and spaced apart from each other; A plurality of back electrodes disposed on the light absorption bars, respectively; And a conductive layer disposed on the back electrodes and facing the window layer.

Description

SOLAR CELL AND METHOD OF FABRICATING THE SAME

An embodiment relates to a solar cell and a manufacturing method thereof.

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.

The embodiment has an improved photoelectric conversion efficiency, and provides a solar cell and a method of manufacturing the same.

Solar cell according to one embodiment comprises a transparent substrate; A window layer disposed on the transparent substrate; A plurality of light absorbing rods disposed on the window layer and spaced apart from each other; A plurality of back electrodes disposed on the light absorption bars, respectively; And a conductive layer disposed on the back electrodes and facing the window layer.

Method for manufacturing a solar cell according to an embodiment comprises the steps of forming a window layer on a transparent substrate; Forming a plurality of light absorbing rods on the window layer; Forming a plurality of back electrodes on the light absorption bars, respectively; And bonding a conductive layer to the back electrodes.

The solar cell according to the embodiment includes a plurality of light absorbing rods. In particular, the light absorbing rods can have a diameter of several hundred nm. Accordingly, the sunlight incident on the solar cell according to the embodiment is scattered inward and absorbed by the light absorbing rods.

That is, the solar cell according to the embodiment efficiently scatters the light incident therein, thereby reducing the amount of light reflected to the outside.

Accordingly, the solar cell according to the embodiment has improved photoelectric conversion efficiency.

In addition, the solar cell according to the embodiment can reduce the amount of incident light is reflected to the outside, so that even if the length of the light absorption bar is small, it can efficiently absorb light.

Therefore, the solar cell according to the embodiment has a thin thickness.

1 is a cross-sectional view showing a solar cell according to an embodiment.
2 is a perspective view illustrating an interior of a solar cell according to an embodiment except for a conductive substrate.
3 to 8 are cross-sectional views illustrating a process of manufacturing a solar cell according to an embodiment.

In the description of the embodiments, it is described that each substrate, layer, region, bar, or electrode is formed on or under the "on" of each substrate, layer, region, bar, or electrode, etc. In the case, “on” and “under” include both being formed “directly” or “indirectly” 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 is a cross-sectional view showing a solar cell according to an embodiment. 2 is a perspective view illustrating an interior of a solar cell according to an embodiment except for a conductive substrate.

1 and 2, a solar cell according to an embodiment includes a transparent substrate 100, a window layer 200, a plurality of high resistance buffers 300, a plurality of buffers 400, and a plurality of light absorptions. The rod 500 includes a plurality of back electrodes 600 and a conductive substrate 700.

The transparent substrate 100 is transparent and is an insulator. The transparent substrate 100 has a plate shape. The transparent substrate 100 may be a glass substrate or a plastic substrate. The transparent substrate 100 may be rigid or flexible. In more detail, the transparent substrate 100 may be a soda lime glass substrate.

The window layer 200 is disposed on the transparent substrate 100. The window layer 200 may be formed on the front surface of the transparent substrate 100. The window layer 200 is a conductive layer. That is, the window layer 200 is a transparent conductive layer.

Examples of the material used as the window layer 200 may include Al doped zinc oxide (AZO) doped with aluminum.

The high resistance buffers 300 are formed on the window layer 200. The high resistance buffers 300 may be deposited on the window layer 200. The high resistance buffers 300 are spaced apart from each other. In more detail, the high resistance buffers 300 may be spaced apart from each other at regular intervals.

The high resistance buffers 300 may have an island shape when viewed in a plan view. In more detail, the high resistance buffers 300 may have a polygonal, circular or elliptical shape when viewed in a plan view.

Examples of the material used as the high resistance buffers 300 include zinc oxide that is not doped with impurities. The bandgap energy of the high resistance buffers 300 may be about 3.1 eV to 3.3 eV.

The buffers 400 are disposed on the high resistance buffers 300, respectively. That is, each buffer 400 is formed by depositing on each of the high resistance buffer 300. The buffers 400 have the same planar shape as the high resistance buffers 300 and cover the high resistance buffers 300, respectively.

The outside of the buffers 400 may coincide with the outside of the high resistance buffers 300.

Examples of the material used as the buffers 400 include cadmium sulfide and the like. The bandgap energy of the buffers 400 may be about 2.0 eV to about 2.5 eV.

The light absorbing rods 500 are disposed on the buffers 400, respectively. Each light absorbing rod 500 may be deposited and formed on each buffer 400. The light absorbing rods 500 may have a rod shape, that is, a pillar shape.

Unlike the drawing, the light absorbing rods 500 may have a dot shape. That is, the light absorbing rods 500 may have a very large diameter compared to the height.

The light absorbing rods 500 have a shape extending upward. That is, the light absorbing rods 500 have a shape extending from the window layer 200 to the conductive substrate 700. That is, the light absorbing rods 500 have a shape extending from the buffers 400 to the window layer 200.

The planar shape of the light absorbing rods 500 may be the same as the planar shape of the buffers 400. In addition, when viewed in plan, the outer edges of the light absorbing rods 500 may coincide with the outer sides of the buffers 400.

The light absorption bars 500 include a group I-III-VI compound. For example, the light absorbing rods 500 may include a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ ; CIGS-based) crystal structure, a copper-indium-selenide-based, or copper-gallium- It may have a selenide-based crystal structure.

The light absorption bars 500 may have an energy band gap of about 1 eV to 1.8 eV.

The back electrodes 600 are disposed on the light absorption bars 500, respectively. That is, each back electrode 600 is deposited on the top surface of each light absorbing bar 500. The back electrodes 600 are made of a conductor. Examples of the material used for the back electrodes 600 include molybdenum and the like.

When viewed in plan view, the back electrodes 600 may have the same shape as the light absorbing bars 500. For example, when viewed in a plan view, the outside of the back electrodes 600 may coincide with the outside of the light absorbing bars 500.

The conductive substrate 700 is disposed on the back electrodes 600. The conductive substrate 700 is disposed on the window layer 200. The conductive substrate 700 faces the window layer 200. The conductive substrate 700 is spaced apart from the window layer 200.

The conductive substrate 700 is a conductor and may have a plate shape. The conductive substrate 700 may be a copper substrate or a molybdenum substrate.

Instead of the conductive substrate 700, a substrate including a support substrate which is an insulator and a conductive layer deposited on a lower surface of the support substrate may be used. The conductive substrate 700 may be referred to as a conductive layer.

The high resistance buffers 300, the buffers 400, the light absorbing rods 500, and the back electrodes 600 constitute a plurality of pillar structures 10. That is, the pillar structures 10 have a columnar shape, protrude from the window layer 200, and extend to the conductive substrate 700. The pillar structures 10 contact the upper surface of the window layer 200 and the lower surface of the conductive substrate 700.

In this case, the pillar structures 10 may have a substantially dot shape. That is, the height of the pillar structures 10 may be very smaller than the diameter of the pillar structures 10.

The pillar structures 10 are interposed between the window layer 200 and the conductive substrate 700 and are connected to the window layer 200 and the conductive substrate 700. That is, the light absorbing bars 500 are interposed between the window layer 200 and the conductive substrate 700.

In addition, the light absorption bars 500 are connected to the window layer 200 through the high resistance buffers 300 and the buffers 400. That is, the window layer 200 connects the light absorption bars 500 to each other.

Similarly, the light absorbing rods 500 are connected to the conductive substrate 700 through the back electrodes 600. That is, the conductive substrate 700 connects the light absorbing rods 500 to each other and the back electrodes 600 to each other.

The pillar structures 10 may have a diameter of about 100 nm to about 300 nm. In addition, the pillar structure may have a height of about 1900 nm to about 5200 nm.

The sunlight incident on the solar cell according to the embodiment is scattered by the pillar structures 10, more specifically, the light absorbing rods 500 and the back electrodes 600. That is, the sunlight incident on the solar cell according to the embodiment is scattered therein and is absorbed by the light absorbing rods 500.

That is, the solar cell according to the exemplary embodiment efficiently scatters the incident light by the pillar structures 10, thereby reducing the amount of reflected light. That is, the scattered sunlight may be incident on the light absorbing bars 500 through the side of the light absorbing bars 500, that is, the outer circumferential surface thereof.

Accordingly, the solar cell according to the embodiment increases the amount of light incident on the light absorbing rods 500 and has an improved photoelectric conversion efficiency.

In addition, the solar cell according to the embodiment may reduce the amount of incident light is reflected to the outside, so that even if the height of the light absorbing rods 500 is small, it can efficiently absorb light.

Therefore, the solar cell according to the embodiment has a thin thickness.

3 to 8 are cross-sectional views illustrating a process of manufacturing a solar cell according to an embodiment. This manufacturing method will be described with reference to the solar cell described above. In the description of the present manufacturing method, the foregoing description of the solar cell can be essentially combined.

Referring to FIG. 3, aluminum doped zinc oxide is deposited by a sputtering process on the transparent substrate 100. Accordingly, the window layer 200 is formed on the transparent substrate 100.

Thereafter, a resin composition is coated and cured on the window layer 200 to form a first preliminary mask layer 811. Thereafter, a photocurable or thermosetting resin composition is coated on the first preliminary mask layer 811 to form a second preliminary mask layer 821.

Referring to FIG. 4, pressure is applied to the second preliminary mask layer 821 by a mold 20 having a plurality of protrusions 21 disposed on a lower surface thereof, and the second preliminary mask layer 821 is patterned. do. In this case, the patterned second preliminary mask layer 821 is cured by light and / or heat, and a second mask 820 is formed on the first preliminary mask layer 811.

Referring to FIG. 5, the first preliminary mask layer 811 is etched using the second mask 820 as an etching mask. In this case, the first preliminary mask layer 811 is etched by a reactive ion etching (RIE) process.

Accordingly, a mask pattern 800 including the first mask 810 and the second mask 820 is formed on the window layer 200. The mask pattern 800 includes a plurality of through holes 830 for forming a pillar structure.

Referring to FIG. 6, using the mask pattern 800 as a deposition mask, a zinc oxide not doped with impurities is deposited on the window layer 200 by a sputtering process. That is, zinc oxide, which is not doped with impurities, is filled inside the through holes 830. Accordingly, high resistance buffers 300 are formed in the through holes 830, respectively.

Thereafter, cadmium sulfide is deposited on the high resistance buffers 300 inside the through holes 830 by a sputtering process or a chemical solution growth method. Accordingly, buffers 400 are formed on the high resistance buffers 300, respectively.

Subsequently, a copper-indium-gallium-selenide compound is deposited on the buffers 400 inside the through holes 830 by a sputtering process or an evaporation method. Accordingly, a plurality of light absorbing rods 500 are formed in the through holes 830 on the buffers 400.

Thereafter, molybdenum is deposited on the light absorbing rods 500 inside the through holes 830 by a sputtering process. Accordingly, a plurality of back electrodes 600 are formed inside the through holes 830 on the light absorbing rods 500.

Referring to FIG. 7, the mask pattern 800 is removed by a reactive ion etching process or a wet etching process, and the pillar structures 10 are completed on the window layer 200.

Referring to FIG. 8, a conductive substrate 700 is bonded to the back electrodes 600. In this case, the conductive substrate 700 and the back electrodes 600 may be heat treated at a temperature of about 200 ° C. to about 1000 ° C., and may be bonded to each other.

As such, the method of manufacturing a solar cell according to the embodiment can easily provide a solar cell having pillar structures of several hundred nm by a nanoimprinting process.

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.

Claims (10)

Transparent substrate;
A window layer disposed on the transparent substrate;
A plurality of light absorbing rods disposed on the window layer and spaced apart from each other;
A plurality of back electrodes disposed on the light absorption bars, respectively; And
Disposed on the back electrodes, the conductive layer facing the window layer;
The solar cell is transparent between the light absorbing rods. Transparent substrate;
A window layer disposed on the transparent substrate;
A plurality of light absorbing rods disposed on the window layer and spaced apart from each other;
A plurality of back electrodes disposed on the light absorption bars, respectively; And
Disposed on the back electrodes, the conductive layer facing the window layer;
The light absorbing rods have a columnar shape,
Solar light is incident on the side of the light absorbing rods. The solar cell of claim 1, further comprising a plurality of buffers interposed between the window layer and the light absorption bars. The solar cell of claim 3, further comprising a plurality of high resistance buffers interposed between the window layer and the buffers. The solar cell of claim 1, wherein the light absorbing rods have a diameter of about 100 nm to about 300 nm. The method of claim 1, wherein the light absorbing rods are connected to each other by the window layer,
The back electrodes are connected to each other by the conductive layer. The solar cell of claim 1, wherein the light absorption bars extend from the window layer toward the conductive layer. Forming a window layer on the transparent substrate;
Forming a plurality of light absorbing rods on the window layer;
Forming a plurality of back electrodes on the light absorption bars, respectively; And
Bonding a conductive layer to the back electrodes;
The method of manufacturing a solar cell is transparent between the light absorption bar. The method of claim 8, wherein forming the light absorbing rods
Forming a mask on the window layer, the mask including a plurality of through grooves exposing the top surface of the window layer; And
And forming the light absorption bars in the through grooves, respectively. The method of claim 9, wherein in the forming of the back electrodes,
And forming the back electrodes on the light absorption bars, respectively, in the through grooves.

Images