KR101573029B1 - Thin film solar cells and methods for fabricating the same - Google Patents

Abstract

The present invention relates to a thin film solar cell and a method of manufacturing the same, and more particularly, to a thin film solar cell and a method of manufacturing the same, which comprises a substrate, a first amorphous semiconductor A first cell including a film, a metal electrode adjacent to the first n-type impurity semiconductor film, and a transparent electrode adjacent to the first p-type impurity semiconductor film. Wherein the hydrogen content of the first amorphous germanium semiconducting film is higher than the hydrogen content of the first n-type impurity semiconductor located on the side opposite to the side from which the light is incident, from the first interface with the first p- And becomes continuously smaller toward the second interface with the semiconductor film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film solar cell,

The present invention relates to a thin film solar cell for converting solar light into electricity, and a method of manufacturing the same.

Solar cells can convert sunlight into electrical energy. Solar cells generate electricity by using virtually infinite sunlight as a source, and have the advantage that harmful substances are not generated when electric power is generated. As a result, it is becoming a popular future eco-friendly energy source that can replace the existing fossil raw materials. However, the photovoltaic energy conversion efficiency of the solar cell is still low, and the use of the solar cell has been limited in practical use. Accordingly, much research has been conducted to improve the photoelectric energy conversion efficiency of the solar cell.

It is an object of the present invention to provide a thin film solar cell with improved light efficiency and a method of manufacturing the same.

Another object of the present invention is to provide a thin film solar cell and a method of manufacturing the same which can reduce the process cost because no additional process or equipment is required.

Still another object of the present invention is to provide a thin film solar cell including an amorphous intrinsic semiconductor film having a large light absorption coefficient and capable of minimizing photo-thermal degradation, and a method of manufacturing the same.

In order to achieve the above object, a thin film solar cell and a manufacturing method thereof according to the present invention are characterized in that a single junction cell or a multiple junction cell including an intrinsic semiconductor film whose characteristics are continuously changed without forming a definite interface is formed. A thin film solar cell and a manufacturing method thereof according to the present invention are characterized in that a solar cell including an intrinsic semiconductor film capable of absorbing sunlight having a visible light wavelength is formed. The thin film solar cell and the manufacturing method thereof according to the present invention are characterized in that a solar cell including an intrinsic semiconductor film having excellent characteristics is formed without any additional process or equipment. The thin film solar cell and the manufacturing method thereof according to the present invention are characterized by including an amorphous intrinsic semiconductor film having a large light absorption coefficient.

A thin film solar cell according to an embodiment of the present invention capable of realizing the above-described features comprises: a substrate; And an amorphous film including an intrinsic semiconductor whose hydrogen content continuously changes on the substrate. The amorphous film includes an incident surface on which light is incident and an opposite surface thereof, and the hydrogen content may continuously decrease from the incident surface to the opposite surface.

In one embodiment of the thin film solar cell, the substrate may include a transparent substrate disposed adjacent to the incident surface. The hydrogen content can be continuously reduced as the distance from the transparent substrate increases.

In one embodiment, the solar cell includes: a p-type semiconductor film disposed on the transparent substrate; An amorphous film disposed on the p-type semiconductor film and having the hydrogen content continuously changing; And an n-type semiconductor film disposed on the amorphous film. The hydrogen content can be continuously reduced from the first interface between the amorphous film and the p-type semiconductor film toward the second interface between the amorphous film and the n-type semiconductor film.

A thin film solar cell according to one embodiment, comprising: a transparent electrode disposed between the transparent substrate and the solar cell; And a metal electrode disposed on the solar cell.

The thin film solar cell of one embodiment may further include a reflective film disposed between the solar cell and the metal electrode.

In one embodiment of the thin film solar cell, the substrate may include an opaque substrate disposed adjacent to the opposite surface instead of the transparent substrate. The hydrogen content can be continuously reduced as the distance from the opaque substrate is reduced.

In one embodiment, the solar cell includes: an n-type semiconductor film disposed on the opaque substrate; An amorphous film disposed on the n-type semiconductor film, the amorphous film having the hydrogen content continuously changing; And a p-type semiconductor film disposed on the amorphous film. The hydrogen content can be continuously reduced from the first interface between the amorphous film and the p-type semiconductor film toward the second interface between the amorphous film and the n-type semiconductor film.

A thin film solar cell according to one embodiment, comprising: a metal electrode disposed between the opaque substrate and the solar cell; And a transparent electrode disposed on the solar cell and through which the light is incident.

In one embodiment, the thin film solar cell may further include a reflective layer between the metal electrode and the solar cell.

In the thin film solar cell of one embodiment, the band gap energy and the light absorption coefficient of the amorphous film can be continuously reduced from the incident surface to the opposite surface.

In the thin film solar cell of one embodiment, the density of the amorphous film may continuously increase from the incident surface to the opposite surface.

In one embodiment of the thin film solar cell, the intrinsic semiconductor may include Si.

In one embodiment, the amorphous film may comprise Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or combinations thereof.

According to another aspect of the present invention, there is provided a thin film solar cell including: a substrate; A first n-type impurity semiconductor film and a first p-type impurity semiconductor film, which are disposed on the substrate and have a hydrogen content continuously changing between the first n-type impurity semiconductor film and the first p- A first cell into which a first amorphous film containing intrinsic silicon is inserted; A metal electrode adjacent to the first n-type impurity semiconductor film; And a transparent electrode adjacent to the first p-type impurity semiconductor film. The hydrogen content of the first amorphous film is higher than that of the first n-type impurity semiconductor film disposed on the side opposite to the side from which the light is incident, from the first interface with the first p- The second interface can be made smaller continuously.

In another embodiment of the thin film solar cell, the substrate may include a transparent substrate. The transparent electrode, the first p-type semiconductor film, the first amorphous film, the first n-type semiconductor film, and the metal electrode may be sequentially stacked on the transparent substrate. Light may be incident on the transparent substrate.

A second intrinsic semiconductor film having a hydrogen content continuously changing with the second p-type semiconductor film between the first cell and the metal electrode, and a second intrinsic semiconductor film having a hydrogen content continuously changing with the second p- And at least one second cell sequentially stacked on the n-type semiconductor film. The second intrinsic semiconductor film may include at least one of an amorphous film and a crystalline film including intrinsic silicon. The hydrogen content of the second intrinsic semiconductor film can be continuously reduced as the distance from the transparent substrate increases.

In another embodiment, the thin film solar cell may further include a rear reflective film disposed between the metal electrode and the first cell.

In another embodiment of the thin film solar cell, the substrate may comprise an opaque substrate. The metal electrode, the first n-type semiconductor film, the first amorphous film, the first p-type semiconductor film, and the transparent electrode may be sequentially stacked on the opaque substrate. Light may be incident on the transparent electrode.

In the thin film solar cell of another embodiment, a second n-type semiconductor film, a second intrinsic semiconductor film having a hydrogen content continuously changing, and a second p-type semiconductor film are formed between the first cell and the transparent electrode, And at least one second cell sequentially stacked on the first p-type semiconductor film. The second intrinsic semiconductor film may include at least one of an amorphous film and a crystalline film including intrinsic silicon. The hydrogen content of the second intrinsic semiconductor film can be made smaller continuously as the distance from the opaque substrate is reduced.

In another embodiment, the thin film solar cell may further include a rear reflective film disposed between the metal electrode and the first cell.

In the thin film solar cell of another embodiment, the first amorphous film may be made of the silicon. Alternatively, the first amorphous film may include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or combinations thereof.

A method of fabricating a thin film solar cell according to an embodiment of the present invention capable of realizing the above features comprises: providing a substrate; A cell including an amorphous film including a p-type semiconductor film and an n-type semiconductor film, and an intrinsic semiconductor having a continuously changing hydrogen content disposed between the p-type semiconductor film and the n-type semiconductor film is formed on the substrate and; Forming a transparent electrode adjacent to the p-type semiconductor film; And forming a metal electrode adjacent to the n-type semiconductor film. The amorphous film includes an incident surface on which light is incident and an opposite surface thereof, and the hydrogen content may continuously decrease from the incident surface to the opposite surface.

In one embodiment, the amorphous film may comprise Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or combinations thereof.

In one embodiment, the substrate may comprise a transparent substrate disposed adjacent to the incident surface. In this case, forming the cell may include: forming the p-type semiconductor film on the transparent substrate; Providing a reactive gas in which a semiconductor source gas is diluted with hydrogen on the p-type semiconductor film, wherein the dilution ratio of the hydrogen is gradually increased to form the amorphous film; And forming the n-type semiconductor film on the amorphous film.

In one embodiment of the method, the substrate may comprise an opaque substrate disposed adjacent to the opposite surface. In this case, forming the cell may include: forming the n-type semiconductor film on the opaque substrate; Providing a reaction gas in which a semiconductor source gas is diluted with hydrogen on the n-type semiconductor film, wherein the dilution ratio of the hydrogen is gradually reduced to form the amorphous film; And forming the p-type semiconductor film on the amorphous film.

According to the present invention, the characteristic of the intrinsic semiconductor film is continuously changed without abrupt fluctuation, whereby an excellent optical efficiency can be obtained. In addition, it is possible to form an intrinsic semiconductor film having continuous characteristics without additional process or equipment, thereby reducing the process cost. In addition, by forming the intrinsic semiconductor film into an amorphous film, the light absorption coefficient can be increased as compared with the crystalline intrinsic semiconductor film, thereby improving the light efficiency of the solar cell.

FIG. 1A is a cross-sectional view illustrating a thin film solar cell according to an embodiment of the present invention. FIG.
FIG. 1B is a flow chart illustrating a method of manufacturing a thin film solar cell according to an embodiment of the present invention. FIG.
1C is a cross-sectional view of a cell of a thin film solar cell according to an embodiment of the present invention.
1D is a cross-sectional view illustrating an operation principle of a thin film solar cell according to an embodiment of the present invention.
Figures 1E through 1G are cross-sectional views illustrating thin film solar cells according to other embodiments of the present invention.
FIG. 2A is a cross-sectional view of a thin film solar cell according to a modified embodiment of the present invention. FIG.
FIG. 2B is a flowchart illustrating a method of manufacturing a thin film solar cell according to a modified embodiment of the present invention. FIG.
2C is a cross-sectional view illustrating a cell of a thin film solar cell according to a modified embodiment of the present invention.
FIG. 2d is a cross-sectional view illustrating the principle of operation of a thin film solar cell according to a modified embodiment of the present invention; FIG.
Figures 2e through 2g are cross-sectional views illustrating thin film solar cells according to further embodiments of the present invention.

Hereinafter, a thin film solar cell according to the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the present invention and its advantages over the prior art will become apparent from the detailed description and claims that follow. In particular, the invention is well pointed out and distinctly claimed in the claims. The invention, however, may best be understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. Like reference numerals in the drawings denote like elements throughout the various views.

≪ Example 1 >

1A is a cross-sectional view illustrating a thin film solar cell according to an embodiment of the present invention. 1B is a flowchart illustrating a method of manufacturing a thin film solar cell according to an embodiment of the present invention. 1C is a cross-sectional view illustrating a cell of a thin film solar cell according to an embodiment of the present invention.

1A, a thin film solar cell 100 includes a transparent electrode 120, a pinned cell or a solar cell 130, and a metal electrode 170 on a transparent substrate 110 in the form of a thin film But may be a superstrate structure of a single junction stacked in sequence. For example, the cell 130 having a pin diode structure may include a p-type semiconductor film 131, an intrinsic semiconductor film 133, and an n-type semiconductor film 135 which are sequentially stacked on the transparent electrode 120. In another example, the cell 130 may include an n-type semiconductor film 135, an intrinsic semiconductor film 133, and a p-type semiconductor film 131 which are sequentially stacked on the transparent electrode 120. a rear reflective film 160 may be further provided between the pin cell 130 and the metal electrode 170. The solar light may be incident on the transparent substrate 110.

Referring to FIG. 1B, a transparent substrate 110 may be provided (S110), and a transparent electrode 120 may be formed as a front electrode on the provided transparent substrate 110 (S120). The transparent substrate 110 may be made of a transparent material capable of transmitting light, for example, glass, plastic, or resin. The transparent electrode 120 may be formed of a transparent conductive oxide such as ZnO, ITO, SnOx, for example, Al, Ga, or In, to which solar light incident through the transparent substrate 110 is transmitted. , A ZnO film to which B is added, a SnO film to which F is added, or the like can be formed by sputtering or metalorganic chemical vapor deposition (MOCVD).

The p-type semiconductor film 131 can be formed on the transparent electrode 120 (S131). The p-type semiconductor film 131 can be formed by a physical vapor deposition (PVD) method, a chemical vapor deposition (CVD) method or the like using a p-type semiconductor doped with a Group 3B element such as boron (B) . Physical vapor deposition can proceed in a hydrogen atmosphere. The chemical vapor deposition process may include plasma chemical vapor deposition (PECVD), hot-wall CVD, hot-wire CVD, atmospheric pressure chemical vapor deposition (APCVD) have. Unless otherwise stated, the term " deposition or deposition process "

The semiconductor constituting the p-type semiconductor film 131 may include Si. The p-type semiconductor film 131 may include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof in addition to Si. For example, the p-type semiconductor film 131 can be formed by depositing p-Si by plasma enhanced chemical vapor deposition (PECVD) using SiH ₄ and H ₂ gas and a p-type dopant such as B ₂ H ₆ . The p-type semiconductor film 131 may be amorphous, monocrystalline, polycrystalline, or microcrystalline (or nanocrystalline). As used herein, the term " semiconductor film " refers not only to a " semiconductor-made film "

the intrinsic semiconductor film 133 can be formed as a light absorbing layer on the p-type semiconductor film 131 (S133). The intrinsic semiconductor film 133 may include Si. The intrinsic semiconductor film 133 can be formed by depositing SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof in addition to Si. The intrinsic semiconductor film 133 may be amorphous, monocrystalline, polycrystalline, microcrystalline (or nanocrystalline), or a combination thereof. According to this embodiment, the intrinsic semiconductor film 133 may include an amorphous silicon film in which no crystalline or microcrystalline is formed at all.

The characteristic of the intrinsic semiconductor film 133 may be formed to be continuously changed along the thickness direction of the intrinsic semiconductor film 133 without being uniform. For example, the p-type semiconductor film 133 is formed by plasma chemical vapor deposition (PECVD) in which H ₂ is added to a Si source gas such as SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiH ₃ Cl, SiHCl ₃ , The intrinsic semiconductor film 133 can be formed. At this time, the intrinsic semiconductor film 133 can be formed by gradually increasing the hydrogen content, for example, [H ₂ ] / [SiH ₄ ]. [SiH ₄ ] can be replaced with [SiH ₄ ], [Si ₂ H ₆ ], [SiH ₂ Cl ₂ ], [SiH ₃ Cl], or [SiHCl ₃ ]. According to the present embodiment, as an example not limiting thereto, the embodiment can be approximately 1 to 20 days.

1C, the first interface 133a of the p-type semiconductor film 131 and the intrinsic semiconductor film 133 extends from the incident surface where sunlight is incident to the opposite surface, that is, (R) can be increased from the first interface 133 to the second interface 133b of the n-type semiconductor film 135 and the intrinsic semiconductor film 133. Accordingly, the radius R can be continuously increased as the distance from the transparent substrate 110 on which sunlight is incident becomes larger and / or the distance from the metal electrode 170 becomes smaller. When the intrinsic semiconductor film 133 is formed while gradually increasing the silicon oxide film R, the content of hydrogen contained in the intrinsic semiconductor film 133 is gradually increased from the first interface 133a to the second interface 133b . ≪ / RTI >

If the intrinsic semiconductor film 133 is formed under the above-described conditions, hydrogen is contained in i-Si, and the hydrogen bonds with defects of the intrinsic semiconductor film 133 to remove defects, so that the electron-hole pairs do not disappear And can contribute to generating electricity. In addition, since the hydrogen content in the intrinsic semiconductor film 133 continuously changes, there is no interface different from the case where the films having different hydrogen contents are stacked, so that the possibility of the carrier being trapped at the interface can be remarkably reduced.

Other characteristics of the intrinsic semiconductor film 133 can be continuously changed in accordance with the continuous change of the ruthenium ratio R. [ For example, hydrogen dilutes the Si source gas, so that the density and crystallinity of the intrinsic semiconductor film 133 can be changed. If the SiH 2 (R) is large, the deposition of i-Si occurs more slowly and the regular arrangement becomes larger, thereby increasing the density or increasing the crystallinity. Therefore, if the silicon nitride (R) is large, an intrinsic semiconductor film 133 of microcrystalline, crystalline or high density amorphous can be formed. According to this embodiment, the amorphous intrinsic semiconductor film 133 before the formation of the microcrystalline can be formed even if the crystallinity and the density of the film become large due to the hydrogen absorption ratio (R). The density of the amorphous intrinsic semiconductor film 133 may increase from the first interface 133a to the second interface 133b. The amorphous intrinsic semiconductor film 133 may have a relatively larger light absorption coefficient than that of the crystalline intrinsic semiconductor film and thus the light conversion efficiency may be increased. If the silicon nitride (R) ratio is small, on the other hand, the intrinsic semiconductor film 133 having a large amorphousness and a low density can be formed.

The band gap energy of the intrinsic semiconductor film 133 can be reduced as the ratio R is increased. On the contrary, the bandgap energy of the intrinsic semiconductor film 133 may become larger as the channel R becomes smaller. The hydrogen content in the thin film may become smaller as the hydrogen dilution ratio becomes larger, which may result in a smaller band gap. FIG. 1C shows the above result and shows that the characteristic value becomes larger toward the arrow direction. For example, the density D and the crystallinity C of the intrinsic semiconductor film 133 may become larger and the band gap energy B and the light absorption coefficient A may become smaller as the hydrogen absorption ratio R becomes larger. The intrinsic semiconductor film 133 can change the wavelength region of the sunlight that can be absorbed according to the band gap energy value thereof. Therefore, the intrinsic semiconductor film 133 can have a large wavelength band of sunlight (e.g., visible light) that can be absorbed because its band value energy is continuously changed.

when the intrinsic semiconductor film 133 is formed by depositing i-Si on the thin film on which the solar light is incident, like the p-type semiconductor film 131, the light efficiency (For example, about 9%), a high optical efficiency (for example, about 9.8%) can be obtained by gradually changing the characteristics of the intrinsic semiconductor film 133 when the intensity of the light is gradually increased as in the present embodiment . This optical efficiency is obtained by stacking the p-Si film 131, the intrinsic amorphous Si film 133 in which the hydrogen content continuously changes, and the n-Si film 135, The hydrogen content in the i-Si film 133 adjacent to the first interface 133a with the film 133 is lower than the hydrogen content in the i-Si film 133 adjacent to the second interface 133b between the i-Si film 133 and the n-Si film 135 Si amorphous silicon thin film solar cell 100 manufactured so that the hydrogen content in the i-Si film 133 is large. Here, the direction in which the hydrogen content changes may be very important. The hydrogen content in the i-Si film 133 adjacent to the first interface 133a between the p-Si film 131 and the i-Si film 133 is larger than the hydrogen content in the i-Si film 133 and the n- When the hydrogen content in the i-Si film 133 adjacent to the second interface 133b with the second interlayer insulating film 135 is made small, a light conversion efficiency of only about 5.8% can be obtained.

Referring again to FIGS. 1A and 1B, the n-type semiconductor film 135 can be formed on the intrinsic semiconductor film 133 (S135). The n-type semiconductor film 135 can be formed by depositing an n-type semiconductor doped with a Group 5B element such as phosphorus (P) in a Group IV element. The semiconductor constituting the n-type semiconductor film 135 may include Si. The n-type semiconductor film 135 may include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof in addition to Si. For example, the n-type semiconductor film 135 can be formed by depositing n-Si by plasma enhanced chemical vapor deposition (PECVD) using SiH ₄ and H ₂ gas and n-type dopant (e.g., PH ₃ ). The n-type semiconductor film 135 may be amorphous, monocrystalline, polycrystalline, or microcrystalline (or nanocrystalline). Thus, the cell 130 having the pin diode structure can be formed by sequentially stacking the p-type semiconductor film 131, the intrinsic semiconductor film 133, and the n-type semiconductor film 135 on the transparent electrode 120.

the rear reflective film 160 may be formed on the n-type semiconductor film 135 (S160). The rear reflective film 160 can be formed to improve the efficiency of the solar cell 100 by reducing the reflection loss of the sunlight and maximizing the light trapping effect. The rear reflective film 160 may be formed by sputter deposition, chemical vapor deposition, or E-beam evaporation using, for example, a material similar to or similar to the oxide transparent electrode 120, such as ZnO or ZnO / Can be formed.

A metal electrode 170 may be formed as a rear electrode on the rear reflective film 160 (S170). The metal electrode 170 may be made of a transparent or opaque material in a single-layer or multi-layer structure. For example, the metal electrode 170 can be formed by depositing Al, Ag, Cu, ZnO / Ag, ZnO / Al, or Ni / Al. The thin film solar cell 100 of FIG. 1A can be formed through the series of processes described above.

≪ Operation Principle of Embodiment 1 >

1D is a cross-sectional view illustrating an operation principle of a thin film solar cell according to an embodiment of the present invention.

Referring to FIG. 1D, solar light may be incident on the transparent substrate 110. The incident sunlight is absorbed by the intrinsic semiconductor film 133 to form an electron-hole pair. The intrinsic semiconductor film 133 can be depleted by the p-type semiconductor film 131 and the n-type semiconductor film 135, so that an electric field can be generated inside the intrinsic semiconductor film 133. Electrons e ^- and holes h ⁺ generated in the intrinsic semiconductor film 133 can be drifted to the n-type semiconductor film 135 and the p-type semiconductor film 131 by an internal electric field, respectively. As a result, holes (h ⁺ ) are accumulated in the p-type semiconductor film 131 and electrons (e ^- ) are accumulated in the n-type semiconductor film 135, so that the p-type semiconductor film 131 and the n- The photovoltaic power can be generated. A current can flow when the load 180 is connected between the transparent electrode 120 capable of collecting the holes h ⁺ and the metal electrode 170 capable of collecting electrons e ^- .

≪ Modifications of Embodiment 1 >

1E to 1G are cross-sectional views illustrating thin film solar cells according to other embodiments of the present invention.

Referring to FIG. 1E, the thin film solar cell 102 may include a transparent electrode 120 having a texturing surface. If the surface of the transparent electrode 120 is textured, the reflection of incident sunlight can be reduced, and the light absorption rate can be increased. The texturing may be performed during or after the deposition of the transparent electrode 120. In addition, at least one of the cell 130, the rear reflective film 160, and the metal electrode 170 may have a textured surface.

Referring to FIG. 1F, the thin film solar cell 104 may be a superstrate structure of a double junction. For example, the thin film solar cell 104 may further include a second cell 140 of p-i-n structure on the first cell 130 of the p-i-n structure. The first cell 130 may have substantially the same structure as the cell 130 of FIG. 1A.

The second cell 140 sequentially deposits a second p-type semiconductor film 141, a second intrinsic semiconductor film 143 and a second n-type semiconductor film 145 on the first n-type semiconductor film 135 . The second p-type semiconductor film 141 can be formed to be substantially the same as or similar to the first p-type semiconductor film 131 and the second n-type semiconductor film 145 to the first n-type semiconductor film 135 have. The second intrinsic semiconductor film 143 may be an amorphous film formed by using substantially the same water solubility as the first intrinsic semiconductor film 133.

As another example, the second intrinsic semiconductor film 143 may be formed using an amorphous film in the same manner as the first intrinsic semiconductor film 133, but using different healing ratios. For example, the hydrogen dilution ratio of the first intrinsic semiconductor film 133 may be 1 to 10, and the second intrinsic semiconductor film 133 may have a hydrogen absorption ratio of 10 to 20, or vice versa. As the hydrogen dilution ratio is different, one of the first and second intrinsic semiconductor films 143 and 153 may be a low-density amorphous film and a high-density amorphous film. Soo-hee can grow bigger along the direction of sunlight. The figures herein are merely exemplary and are not intended to limit the invention in any way.

As another example, either the first intrinsic semiconductor film 133 or the second intrinsic semiconductor film 143 may be an amorphous film and the other may be a crystalline film (e.g., a microcrystalline film, a single crystal film, or a polycrystalline film). As another example, either the first intrinsic semiconductor film 133 or the second intrinsic semiconductor film 143 may be an amorphous film and the other may be a mixed film of a crystalline film and an amorphous film.

Referring to FIG. 1G, the thin film solar cell 106 may be a super-straight structure of a triple junction. For example, the thin film solar cell 106 may further include a second cell 140 of a p-i-n structure and a third cell 150 of a p-i-n structure on a first cell 130 of a p-i-n structure. The first cell 130 may have substantially the same structure as the cell 130 of FIG. 1A.

The second cell 140 sequentially deposits a second p-type semiconductor film 141, a second intrinsic semiconductor film 143 and a second n-type semiconductor film 145 on the first n-type semiconductor film 135 . The second p-type semiconductor film 141 can be formed to be substantially the same as or similar to the first p-type semiconductor film 131 and the second n-type semiconductor film 145 to the first n-type semiconductor film 135 have.

The third cell 150 sequentially deposits a third p-type semiconductor film 151, a third intrinsic semiconductor film 153 and a third n-type semiconductor film 155 on the second n-type semiconductor film 145 . The third cell 150 may be substantially the same or similar to the first cell 130 and / or the second cell 140. The third p-type semiconductor film 151 is formed of the first p-type semiconductor film 131 and / or the second p-type semiconductor film 141 and the third n-type semiconductor film 155 is formed of the first n-type semiconductor film 135 and / or the second n-type semiconductor film 145. The second n- The third tincture semiconductor film 153 may be formed to be substantially the same as or similar to the first intrinsic semiconductor film 133 and / or the second intrinsic semiconductor film 143.

As another example, the tertiary semiconducting semiconductor film 153 can be formed using an amorphous film similar to the first intrinsic semiconductor film 133 and / or the second intrinsic semiconductor film 143, have. For example, the first and second intrinsic semiconductor films 133 and 133 may be formed to a thickness of 1 to 7 (or 15 to 20), a second intrinsic semiconductor film 133 may have a healing ratio of 7 to 15, ) May be from 15 to 20 (or from 1 to 7). As another example, the hydrogenation ratio of any one of the first and third intrinsic semiconductor films 133 and 153 is 7 to 15 and the other hydrogenation ratio is 15 to 20, and the second intrinsic semiconductor film 133) may be from 1 to 7. As another example, the hydrogenation ratio of any one of the first and third intrinsic semiconductor films 133 and 153 is 1 to 7 and the other hydrogenation ratio is 7 to 15, (133) may be between 15 and 20 days. Soo-hee can grow bigger along the direction of sunlight.

As another example, at least one of the first to third intrinsic semiconductor films 133, 143, and 153 may be an amorphous film and the remaining may be a crystalline film. As another example, at least one of the first to third intrinsic semiconductor films 133, 143, and 153 may be an amorphous film and the remaining film may be a mixed film of a crystalline film and an amorphous film.

≪ Example 2 >

2A is a cross-sectional view illustrating a thin film solar cell according to a modified embodiment of the present invention. 2B is a flowchart illustrating a method of manufacturing a thin film solar cell according to a modified embodiment of the present invention. 2C is a cross-sectional view illustrating a cell of a thin film solar cell according to a modified embodiment of the present invention.

2A, a thin film solar cell 200 includes a transparent electrode 210, a metal electrode 270, a nip structure cell 230, and a transparent electrode 220, which are sequentially stacked in the form of a thin film on a non-transparent substrate 210 Or may be a substrate structure of a single junction. For example, the cell 230 may include an n-type semiconductor film 235, an intrinsic semiconductor film 233, and a p-type semiconductor film 231 which are sequentially stacked on the metal electrode 270. As another example, the cell 230 may include a p-type semiconductor film 231, an intrinsic semiconductor film 233, and an n-type semiconductor film 235 which are sequentially stacked on the metal electrode 270. The rear reflective film 260 may be disposed between the metal electrode 270 and the cell 230. The solar light may be incident on the transparent electrode 220.

Referring to FIG. 2B, the opaque substrate 210 may be provided (S210), and the metal electrode 270 may be formed on the opaque substrate 210 as a back electrode (S270). The metal electrode 270 may be made of a transparent or opaque material such as Al, Ag, Cu, ZnO / Ag, ZnO / Al, Ni /

The rear reflective film 260 may be formed on the metal electrode 270 (S260). According to the present embodiment, since the sunlight is incident on the transparent electrode 220, the opaque substrate 210 such as a metal substrate may be used. As another example, instead of the opaque substrate 210, a transparent substrate may be employed as shown in FIG. 1A. The rear reflective layer 260 may be formed of the same or similar material as the oxide transparent electrode 120, for example, ZnO or ZnO / Ag.

An intrinsic semiconductor film 233 is formed on the n-type semiconductor film 235 (S233), and an intrinsic semiconductor film 233 is formed on the intrinsic semiconductor film 233 (S233) A p-type semiconductor film 231 may be formed on the substrate 230 (S231) to form a cell 230 having a nip structure. The formation of the n-type semiconductor film 235 and the p-type semiconductor film 231 may be substantially the same as or similar to the formation of the n-type semiconductor film 135 and the p-type semiconductor film 131 in Fig. For example, at least one of the n-type semiconductor film 235 and the p-type semiconductor film 231 may be an amorphous semiconductor film including Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, A microcrystalline film, a single crystal film, or a polycrystalline film.

The intrinsic semiconductor film 233 may be formed of an amorphous film having substantially the same or similar characteristics to those of the intrinsic semiconductor film 133 of FIG. For example, it can be formed such that the hydrogen dilution ratio gradually increases along the direction in which the sunlight is incident (that is, the farther from the surface on which sunlight is incident). According to this embodiment, H ₂ is added to a Si source gas such as SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiH ₃ Cl, SiHCl _3, and the like, and the n-type semiconductor film 235 I-Si is deposited on the intrinsic semiconductor film 233 to form the intrinsic semiconductor film 233. The intrinsic semiconductor film 233 may include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof in addition to Si. According to this embodiment, the intrinsic semiconductor film 233 can be formed by progressively reducing the helix ratio. As shown in FIG. 2C, in the intrinsic semiconductor film 233, the hydrogen content R increases along the direction in which sunlight is incident, and the hydrogen content can be lowered. That is, the hydrogen content R can be continuously increased from the first interface 233a to the second interface 233b without forming a definite interface, and the hydrogen content can be continuously reduced. For example, the hydrotherapy (R) may be from 1 to 20 as an example, not limiting to the present invention. As described above, the radius R may continuously increase as the distance from the transparent electrode 220 on which the sunlight is incident and / or the distance from the opaque substrate 210 becomes smaller. In the intrinsic semiconductor film 233 the band gap energy B of the intrinsic semiconductor film 233 from the first interface 233a to the second interface 233b and the light absorption The coefficient A gradually decreases, and the density D and the crystallinity C can gradually increase.

Referring again to FIGS. 2A and 2B, a transparent electrode 220 may be formed as a front electrode on the p-type semiconductor film 231 (S220). The transparent electrode 220 is formed of a transparent conductive oxide (TCO) such as ZnO, ITO, SnOx or the like to which metal ions are added to transmit incident solar light, a ZnO film added with Al, Ga, In, A SnO 2 film or the like may be formed by sputtering or metal organic chemical vapor deposition (MOCVD). The thin film solar cell 200 of FIG. 2A may be formed through the series of processes described above.

≪ Operation Principle of Embodiment 2 >

FIG. 2D is a cross-sectional view illustrating a principle of operation of a thin film solar cell according to a modified embodiment of the present invention.

Referring to FIG. 2D, solar light may be incident on the transparent electrode 220. The incident sunlight can be absorbed by the intrinsic semiconductor film 233 and an electron-hole pair can be generated. The electrons e ^- are drifted and accumulated in the n-type semiconductor film 235 by the internal electric field of the intrinsic semiconductor film 233 and the holes h ⁺ are drifted and accumulated in the p-type semiconductor film 231. Photovoltage can be generated between the p-type semiconductor film 231 and the n-type semiconductor film 235. When the load 280 is connected between the transparent electrode 220 and the metal electrode 270 A current can flow.

≪ Modifications of Embodiment 2 >

2E through 2G are cross-sectional views illustrating thin film solar cells according to still another embodiment of the present invention.

Referring to FIG. 2E, the thin film solar cell 202 includes a textured structure. At least one of the transparent electrode 220, the cell 230, the rear reflective film 260, and the metal electrode 270 may have a textured surface.

Referring to FIG. 2F, the thin film solar cell 204 may be a substrate structure of a double junction. For example, the thin film solar cell 204 may further include a second cell 240 of n-i-p structure on the first cell 230 of the n-i-p structure. The first cell 230 may be substantially the same or similar to the cell 230 of FIG. 2A. The second cell 240 is formed by sequentially depositing a second n-type semiconductor film 245, a second intrinsic semiconductor film 243 and a second p-type semiconductor film 241 on the first p-type semiconductor film 231 . The second p-type semiconductor film 241 may be formed of the first p-type semiconductor film 231 and the second n-type semiconductor film 245 may be formed substantially the same or similar to the first n-type semiconductor film 235 have.

The second intrinsic semiconductor film 243 may be formed to be substantially the same or similar to or different from the first intrinsic semiconductor film 233. For example, the hydrogen absorption ratio of the amorphous second intrinsic semiconductor film 233 and the hydrogen absorption ratio of the amorphous second intrinsic semiconductor film 243 may be the same, or one of them may be larger than the other. In another example, one of the first intrinsic semiconductor film 233 and the second intrinsic semiconductor film 243 is an amorphous film and the other is a crystalline film (e.g., a microcrystalline film, a monocrystalline film, a polycrystalline film) It may be a mixed film of a film and an amorphous film.

Referring to FIG. 2G, the thin film solar cell 206 may be a substrate structure of a triple junction. For example, the thin film solar cell 206 may further include a second cell 240 of n-i-p structure and a third cell 250 of n-i-p structure on the first cell 230 of the n-i-p structure. The third cell 250 sequentially deposits a third n-type semiconductor film 255, a third intrinsic semiconductor film 253 and a third p-type semiconductor film 251 on the second p-type semiconductor film 241 . The third cell 250 may be substantially the same or similar to the first cell 230 and / or the second cell 240.

The conductivity of the first to third intrinsic semiconductor films 233, 243, and 253 may be the same or different from each other. For example, the first to third intrinsic semiconductor films 233, 243, and 253 may be amorphous films in which the hydrogen dilution ratio is increased or decreased in the order of stacking. As another example, the first to third intrinsic semiconductor films 233, 243, and 253 may be amorphous films that increase in hydrogen dilution ratio in the order of lamination, decrease or decrease, and then increase.

As another example, at least one of the first to third intrinsic semiconductor films 233, 243, and 253 may be an amorphous film and the other may be a crystalline film or a mixed film of a crystalline film and an amorphous film.

It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention. The appended claims should be construed to include other embodiments.

100, 102, 104, 106, 200, 202, 204, 206: Thin film solar cell
110, 210: substrate
120, 220: transparent electrode
130, 140, 150, 230, 240, 250:
131, 141, 151, 231, 241, 251: p-type semiconductor films
133, 143, 153, 233, 243, 253: intrinsic semiconductor film
135, 145, 155, 235, 235, and 255: an n-type semiconductor film
160, 260: rear reflection film
170, 270: metal electrode
180, 280: Load

Claims (24)

Claims [1] And
And a photovoltaic cell having an amorphous film provided between the p-type semiconductor film and the n-type semiconductor film disposed on the substrate and including an intrinsic semiconductor in which a hydrogen content continuously changes,
Wherein the amorphous film is a single film including an incident surface on which light is incident and a surface opposite to the incident surface, the hydrogen content continuously decreases from the incident surface to the opposite surface, and the amorphous film is continuously formed from the incident surface to the opposite surface, Thin film solar cell having the same hydrogen concentration along the thickness direction. The method according to claim 1,
Wherein the substrate includes a transparent substrate disposed adjacent to the incident surface,
Wherein the hydrogen content is continuously reduced as the distance from the transparent substrate increases. 3. The method of claim 2,
The solar cell includes:
The p-type semiconductor film, the amorphous film, and the n-type semiconductor film sequentially stacked on the transparent substrate,
Wherein the hydrogen content is continuously reduced from the first interface between the amorphous film and the p-type semiconductor film toward the second interface between the amorphous film and the n-type semiconductor film. The method of claim 3,
A transparent electrode disposed between the transparent substrate and the solar cell; And
A metal electrode disposed on the solar cell;
Further thin film solar cells. 5. The method of claim 4,
And a reflective film disposed between the solar cell and the metal electrode. The method according to claim 1,
The substrate comprising an opaque substrate disposed adjacent to the opposite surface,
Wherein the hydrogen content decreases continuously as the distance from the opaque substrate decreases. The method according to claim 6,
The solar cell includes:
The n-type semiconductor film, the amorphous film, and the p-type semiconductor film sequentially stacked on the opaque substrate;
Wherein the hydrogen content is continuously reduced from the first interface between the amorphous film and the p-type semiconductor film toward the second interface between the amorphous film and the n-type semiconductor film. 8. The method of claim 7,
A metal electrode disposed between the opaque substrate and the solar cell; And
A transparent electrode disposed on the solar cell and through which the light is incident;
Further thin film solar cells. 9. The method of claim 8,
Wherein the thin film solar cell further comprises a reflective film between the metal electrode and the solar cell. The method according to claim 1,
Wherein the band gap energy and the light absorption coefficient of the amorphous film are continuously decreased from the incident surface to the opposite surface, and the density of the amorphous film continuously increases from the incident surface to the opposite surface. The method according to claim 1,
Wherein the intrinsic semiconductor includes Si. The method according to claim 1,
Wherein the amorphous film comprises Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC or a combination thereof. Board;
The first n-type impurity semiconductor film and the first p-type impurity semiconductor film, which are disposed on the substrate, and an intrinsic property having a hydrogen content continuously changing between the first n-type impurity semiconductor film and the first p- A first cell into which a first amorphous film containing silicon is inserted;
A metal electrode adjacent to the first n-type impurity semiconductor film; And
And a transparent electrode adjacent to the first p-type impurity semiconductor film,
Wherein the first amorphous film is a single film,
The hydrogen content of the first amorphous film is higher than that of the first n-type impurity semiconductor film disposed on the side opposite to the side from which the light is incident, from the first interface with the first p- And does not have the same hydrogen concentration along the thickness direction of the first amorphous film from the first interface toward the second interface. 14. The method of claim 13,
Wherein the substrate comprises a transparent substrate,
The transparent electrode, the first p-type semiconductor film, the first amorphous film, the first n-type semiconductor film, and the metal electrode are sequentially stacked on the transparent substrate,
And the light is incident on the transparent substrate. 15. The method of claim 14,
Between the first cell and the metal electrode,
Type semiconductor film, a second intrinsic semiconductor film having a continuously variable hydrogen content, and a second cell in which a second n-type semiconductor film is sequentially stacked on the first n-type semiconductor film,
Wherein the second intrinsic semiconductor film is a single film including any one of an amorphous film and a crystalline film including intrinsic silicon,
And the hydrogen content of the second intrinsic semiconductor film is continuously reduced as the distance from the transparent substrate increases, and does not have the same hydrogen concentration along the thickness direction of the second intrinsic semiconductor film. 15. The method of claim 14,
And a rear reflective film disposed between the metal electrode and the first cell. 14. The method of claim 13,
Wherein the substrate comprises an opaque substrate,
Wherein the metal electrode, the first n-type semiconductor film, the first amorphous film, the first p-type semiconductor film, and the transparent electrode are sequentially stacked on the opaque substrate,
And the light is incident on the transparent electrode. 18. The method of claim 17,
Between the first cell and the transparent electrode,
A second n-type semiconductor film, a second intrinsic semiconductor film having a continuously changing hydrogen content, and a second cell in which a second p-type semiconductor film is sequentially stacked on the first p-type semiconductor film ,
Wherein the second intrinsic semiconductor film is a single film including any one of an amorphous film and a crystalline film including intrinsic silicon,
Wherein the hydrogen content of the second intrinsic semiconductor film is continuously reduced as the distance from the opaque substrate is reduced, and does not have the same hydrogen concentration along the thickness direction of the second intrinsic semiconductor film. 18. The method of claim 17,
And a rear reflective film disposed between the metal electrode and the first cell. 14. The method of claim 13,
Wherein the first amorphous film comprises:
Silicon; or
A thin film solar cell comprising SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC or combinations thereof. Providing a substrate;
A cell including an amorphous film including a p-type semiconductor film and an n-type semiconductor film, and an intrinsic semiconductor having a continuously changing hydrogen content disposed between the p-type semiconductor film and the n-type semiconductor film is formed on the substrate and;
Forming a transparent electrode adjacent to the p-type semiconductor film; And
And forming a metal electrode adjacent to the n-type semiconductor film,
Wherein the amorphous film is a single film including an incident surface on which light is incident and a surface opposite to the incident surface, the hydrogen content continuously decreases from the incident surface to the opposite surface, and the thickness of the amorphous film Wherein the thin film solar cell has no hydrogen concentration in the same direction. 22. The method of claim 21,
Wherein the amorphous film comprises Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC or a combination thereof. 23. The method of claim 22,
The substrate includes a transparent substrate disposed adjacent to the incident surface,
The cells are formed by:
Forming the p-type semiconductor film on the transparent substrate;
Providing a reactive gas in which a semiconductor source gas is diluted with hydrogen on the p-type semiconductor film, wherein the dilution ratio of the hydrogen is gradually increased to form the amorphous film; And
And forming the n-type semiconductor film on the amorphous film. 23. The method of claim 22,
Wherein the substrate comprises an opaque substrate disposed adjacent to the opposite surface,
The cells are formed by:
Forming the n-type semiconductor film on the opaque substrate;
Providing a reaction gas in which a semiconductor source gas is diluted with hydrogen on the n-type semiconductor film, wherein the dilution ratio of the hydrogen is gradually reduced to form the amorphous film; And
And forming the p-type semiconductor film on the amorphous film.

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