JP2012175112A - Thin film solar cell and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film solar cell improved in light efficiency and a method of manufacturing the thin film solar cell.SOLUTION: In a first cell of a thin film solar cell, a first amorphous intrinsic semiconductor film 133 with a continuously graded hydrogen content is inserted between a first n-type impurity semiconductor film 135 and a first p-type impurity semiconductor film 131. The hydrogen content of the first amorphous intrinsic semiconductor film 133 decreases in a continuous manner from a first interface 133a with the first p-type impurity semiconductor film 131 arranged on a light incident side toward a second interface 133b with the first n-type impurity semiconductor film 135 arranged on a side opposite to the light incident side.

Description

  The present invention relates to a thin-film solar cell that converts sunlight into electricity and a method for manufacturing the same.

  Solar cells can convert sunlight into electrical energy. Solar cells have the advantage that they generate power using sunlight, which is virtually infinite, as a source, and no harmful substances are generated when the power is generated. This has attracted attention as a representative future environmental energy source that can replace the current fossil fuel. However, since the photoelectric energy conversion efficiency of the solar cell is also low, the use is limited in putting the solar cell into practical use. Therefore, much research has been conducted to improve the photoelectric energy conversion efficiency of solar cells.

Korean Patent Publication No. 10-2011-064059

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

  Another object of the present invention is to provide a thin-film solar cell that does not require additional processes and equipment and can reduce process costs, and a method for manufacturing the same.

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

  In order to achieve the above object, a thin film solar cell and a method of manufacturing the same according to the present invention form a single-junction cell or a multi-junction cell including an intrinsic semiconductor film whose characteristics are continuously changed without forming an obvious interface. Features. Another feature of the thin-film solar cell and the method for manufacturing the same according to the present invention is that a solar cell including an intrinsic semiconductor film capable of absorbing sunlight having a visible light wavelength is formed. Another feature of the thin film solar cell and the method for manufacturing the same according to the present invention is to form a solar cell including an intrinsic semiconductor film having excellent characteristics without additional steps or equipment. Another feature of the thin-film solar cell and the method of manufacturing the same according to the present invention is that it includes an amorphous intrinsic semiconductor film having a large light absorption coefficient.

  A thin-film solar cell according to an embodiment of the present invention that can implement the above features, a solar cell having a substrate, and an amorphous film including an intrinsic semiconductor, the hydrogen content continuously disposed on the substrate, Can be included. 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 the thin film solar cell according to an embodiment, 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, and the continuously changing hydrogen-containing material disposed on the p-type semiconductor film. The amorphous film having an amount and an n-type semiconductor film disposed on the amorphous film can be included. The hydrogen content can be continuously reduced from the first interface between the amorphous film and the p-type semiconductor film to the second interface between the amorphous film and the n-type semiconductor film. .

  The thin film solar cell according to an embodiment may further include 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 battery according to an embodiment may further include a reflective film disposed between the solar battery cell and the metal electrode.

  In one embodiment, the substrate may include an opaque substrate disposed adjacent to the opposite surface instead of a transparent substrate. The hydrogen content can continuously decrease as the distance from the opaque substrate decreases.

  In one embodiment, the solar cell includes an n-type semiconductor film disposed on the opaque substrate and the continuously changing hydrogen-containing material disposed on the p-type semiconductor film. The amorphous film having an amount and a p-type semiconductor film disposed on the amorphous film can be included. The hydrogen content can be continuously reduced from the first interface between the amorphous film and the p-type semiconductor film to the second interface between the amorphous film and the n-type semiconductor film. .

  In the thin film solar cell according to one embodiment, a metal electrode disposed between the opaque substrate and the solar cell, and a transparent electrode disposed on the solar cell and incident with the light. Can be included.

  The thin film solar cell according to an embodiment may further include a reflective film between the metal electrode and the solar cell.

  In the thin film solar cell according to an embodiment, the band gap energy and the light absorption coefficient of the amorphous film may continuously decrease from the incident surface to the opposite surface.

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

  In the thin film solar cell according to an embodiment, the intrinsic semiconductor may include Si.

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

  A thin-film solar cell according to another embodiment of the present invention that can implement the above features includes a substrate, a first n-type impurity semiconductor film and a first p-type impurity semiconductor film disposed on the substrate, A first amorphous film including an intrinsic semiconductor having a continuously changing hydrogen content between one n-type impurity semiconductor film and the first p-type impurity semiconductor film; A cell, 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 can be included. The hydrogen content of the first amorphous film is opposite to the light incident from the first interface with the first p-type impurity semiconductor film disposed on the light incident side. The closer to the second interface with the first n-type impurity semiconductor film that is arranged, the smaller the distance can be.

  In the thin film solar cell according to another embodiment, 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.

  In a thin film solar cell according to another embodiment, between the first cell and the metal electrode, a second p-type semiconductor film, and a second intrinsic semiconductor film having a continuously changing hydrogen content, It may further include at least one second cell in which a second n-type semiconductor film is sequentially stacked on the first n-type semiconductor film. The second intrinsic semiconductor film may include at least one of an amorphous film containing intrinsic silicon and a crystalline film. The hydrogen content of the second intrinsic semiconductor film can continuously decrease as the distance from the transparent substrate increases.

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

  In a thin film solar cell according to another embodiment, the substrate may include 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 a thin film solar cell according to another embodiment, a second n-type semiconductor film and a second intrinsic semiconductor film having a continuously changing hydrogen content between the first cell and the metal electrode, It may further include at least one second cell in which a second p-type semiconductor film is sequentially stacked on the metal electrode. The second intrinsic semiconductor film may include at least one of an intrinsic amorphous film, an intrinsic microcrystalline silicon film, and a crystalline film. The hydrogen content of the second intrinsic semiconductor film may continuously decrease as the distance from the opaque substrate decreases.

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

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

  A method of manufacturing a thin-film solar cell according to an embodiment of the present invention that can implement the above-described features provides a substrate, and a p-type semiconductor film, an n-type semiconductor film, and the p-type semiconductor film and the n on the substrate. Forming a cell including an amorphous film including an intrinsic semiconductor having a continuously changing hydrogen content disposed between the p-type semiconductor film and forming a transparent electrode adjacent to the p-type semiconductor film; Forming a metal electrode adjacent to the shaped 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 include Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof.

  In one embodiment, the substrate may include a transparent substrate disposed adjacent to the incident surface. In this case, forming the cell provides a reaction gas in which the p-type semiconductor film is formed on the transparent substrate, and a semiconductor source gas is diluted with hydrogen on the p-type semiconductor film, The method may include forming the amorphous film while gradually increasing the dilution ratio of hydrogen, and forming the n-type semiconductor film on the amorphous film.

  In one embodiment, the substrate can include an opaque substrate disposed adjacent to the opposite surface. In this case, forming the cell includes forming the n-type semiconductor film on the opaque substrate, providing a reaction gas obtained by diluting a semiconductor source gas with hydrogen on the n-type semiconductor film, and The method may include forming the amorphous film while gradually reducing the hydrogen dilution ratio, and forming the p-type semiconductor film on the amorphous film.

  According to the present invention, it is possible to obtain excellent light efficiency by continuously changing the characteristics of the intrinsic semiconductor film without abrupt changes. Further, since an intrinsic semiconductor film having continuous characteristics can be formed without additional processes and equipment, there is an effect that process costs can be reduced. Further, by forming the intrinsic semiconductor film as an amorphous film, the light absorption coefficient can be increased as compared with the crystalline intrinsic semiconductor film, and thus the light efficiency of the solar cell can be improved.

It is sectional drawing which showed the thin film solar cell by one Embodiment of this invention. It is a flowchart which shows the manufacturing method of the thin film solar cell by one Embodiment of this invention. It is sectional drawing which showed the cell of the thin film solar cell by one Embodiment of this invention. It is sectional drawing explaining the operation principle of the thin film solar cell by one Embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention. It is sectional drawing which showed the thin film solar cell by the deformation | transformation embodiment of this invention. It is a flowchart which shows the manufacturing method of the thin film solar cell by the deformation | transformation embodiment of this invention. It is sectional drawing which showed the cell of the thin film solar cell by the deformation | transformation embodiment of this invention. It is sectional drawing explaining the operation | movement principle of the thin film solar cell by the deformation | transformation embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention. It is sectional drawing which showed the thin film solar cell by other embodiment of this invention.

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

  Advantages of the present invention compared to the prior art may become apparent through the detailed description and appended claims with reference to the accompanying drawings. In particular, the invention is claimed explicitly in the claims. However, the invention can best be understood by referring to the following detailed description in conjunction with the accompanying drawings. In the drawings, like reference numerals designate like elements throughout the various views.

<Embodiment 1>
FIG. 1A is a cross-sectional view illustrating a thin film solar cell according to an embodiment of the present invention. FIG. 1B is a flowchart illustrating a method for manufacturing a thin-film solar cell according to an embodiment of the present invention. FIG. 1C is a cross-sectional view showing a conceptual diagram of a cell of a thin-film solar battery according to an embodiment of the present invention.

  Referring to FIG. 1A, a thin-film solar battery 100 includes a transparent electrode 120, a p-i-n cell or a solar battery cell 130, and a metal electrode 170, which are sequentially stacked in a thin film form on a transparent substrate 110. It may be a single junction superstrate structure. As an 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 that are sequentially stacked on the transparent electrode 120. As 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 that 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. Sunlight can be incident on the transparent substrate 110.

  Referring to FIG. 1B together with FIG. 1A, a transparent substrate 110 is provided (S110), and a transparent electrode 120 may be formed on the provided transparent substrate 110 as a front electrode (S120). The transparent substrate 110 may be made of a transparent material that can transmit light, for example, glass, plastic, or resin. The transparent electrode 120 is a transparent conductive oxide, for example, ZnO, ITO, SnOx (x <2) to which metal ions are added to transmit sunlight incident through the transparent substrate 110, for example, Al. A ZnO film to which Ga, In, and B are added, a SnO film to which F is added, and the like can be formed by sputtering, metal organic chemical vapor deposition (MOCVD), or the like.

  A p-type semiconductor film 131 can be formed on the transparent electrode 120 (S131). The p-type semiconductor film 131 is a p-type semiconductor doped with a Group 4 element, for example, a Group 3B element such as boron B, using physical vapor deposition (PVD) or chemical vapor deposition (CVD). Can be formed. Physical vapor deposition can proceed in a hydrogen atmosphere. Chemical vapor deposition methods include plasma enhanced chemical vapor deposition (PECVD), hot wall chemical vapor deposition (hot-wall CVD), hot wire chemical vapor deposition (hot-wire CVD), and atmospheric pressure chemical vapor deposition. Law (APCVD) and the like. In the present specification, unless otherwise specified, the term “deposition or deposition process” refers to the various deposition methods.

The semiconductor constituting the p-type semiconductor film 131 can include Si. In addition to Si, the p-type semiconductor film 131 can include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof. As an example, the p-type semiconductor film 131 may 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 (eg, B ₂ H ₆ ). . The p-type semiconductor film 131 may be amorphous, single crystalline, polycrystalline, or fine crystalline (or nanocrystalline). In this specification, “semiconductor film” means not only “a film made of a semiconductor” but also “a film containing a semiconductor”.

  An intrinsic semiconductor film 133 can be formed as a light absorption layer on the p-type semiconductor film 131 (S133). The intrinsic semiconductor film 133 can include Si. The intrinsic semiconductor film 133 can be formed by vapor-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, single crystalline, polycrystalline, microcrystalline (or nanocrystalline), or a combination thereof. According to the present embodiment, the intrinsic semiconductor film 133 can include an amorphous silicon film in which no crystalline or fine crystalline is formed.

The characteristics of the intrinsic semiconductor film 133 are not uniform and can be formed so as to be continuously changed along the thickness direction of the intrinsic semiconductor film 133. For example, a p-type semiconductor by plasma enhanced 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 , or a combination thereof. An intrinsic semiconductor film 133 can be formed by evaporating i-Si on the film 131. At this time, the intrinsic semiconductor film 133 can be formed by gradually increasing the hydrogen dilution ratio, for example, [H ₂ ] / [SiH ₄ ]. The intrinsic semiconductor film 133 may be amorphous. [SiH ₄ ] can be replaced with [SiH ₄ ], [Si ₂ H ₆ ], [SiH ₂ Cl ₂ ], [SiH ₃ Cl], [SiHCl ₃ ], or the like. According to this embodiment, as an example that is not limited to this embodiment, the hydrogen dilution ratio may be approximately 1 to 20.

  According to the present embodiment, as illustrated in FIG. 1C, the first interface 133 a between the p-type semiconductor film 131 and the intrinsic semiconductor film 133 increases from the incident surface on which sunlight is incident to the opposite surface. The hydrogen dilution ratio R can increase from the second interface 133b between the n-type semiconductor film 135 and the intrinsic semiconductor film 133 to the second interface 133b. Accordingly, the hydrogen dilution ratio R can be continuously increased as the distance from the transparent substrate 110 on which sunlight is incident is increased and / or as the distance from the metal electrode 170 is decreased. If the intrinsic semiconductor film 133 is formed while gradually increasing the hydrogen dilution ratio R, the content of hydrogen contained in the intrinsic semiconductor film 133 decreases continuously as it goes from the first interface 133a to the second interface 133b. Can be.

  When the intrinsic semiconductor film 133 is formed under the above-described conditions, hydrogen is contained in i-Si, and the hydrogen combines with defects in the intrinsic semiconductor film 133 to remove the defects. Since it is not extinguished, it can contribute to generating electricity. In addition, since the hydrogen content in the intrinsic semiconductor film 133 changes continuously, there is no interface unlike the case where films having different hydrogen contents are stacked, and carriers may be trapped and consumed at the interface. Can be significantly reduced.

  As the hydrogen dilution ratio R changes continuously, other characteristics of the intrinsic semiconductor film 133 can be changed continuously. For example, since hydrogen dilutes a Si source gas, the density of the intrinsic semiconductor film 133 can be changed. If the hydrogen dilution ratio R is large, the deposition of i-Si occurs more slowly, and the regular arrangement increases accordingly, the density increases, or the crystallinity increases. Therefore, if the hydrogen dilution ratio R is large, a fine crystalline, crystalline, or high-density amorphous intrinsic semiconductor film 133 can be formed. According to this embodiment, even if the hydrogen dilution ratio R is increased and the crystallinity and density of the film are increased, the amorphous intrinsic semiconductor film 133 at the stage before the formation of the fine crystalline can be formed. The density of the amorphous intrinsic semiconductor film 133 can increase as it goes from the first interface 133a to the second interface 133b. Since the amorphous intrinsic semiconductor film 133 has a relatively large light absorption coefficient compared to the crystalline intrinsic semiconductor film, the light conversion efficiency can be increased. Even if the light absorption layer is amorphous, light-induced degradation can be reduced by increasing the hydrogen dilution ratio. On the contrary, if the hydrogen dilution ratio R is small, the amorphousness becomes large, and the intrinsic semiconductor film 133 with a low density can be formed.

  The higher the hydrogen dilution ratio R, the smaller the band gap energy of the intrinsic semiconductor film 133 can be. On the contrary, the band gap energy of the intrinsic semiconductor film 133 can increase as the hydrogen dilution ratio R decreases. Although the hydrogen content in the thin film decreases as the hydrogen dilution ratio increases, the band gap can be reduced accordingly. FIG. 1C shows the result, and shows that the characteristic value increases as the direction of the arrow increases. For example, as the hydrogen dilution ratio R increases, the density D of the intrinsic semiconductor film 133 increases, and the band gap energy B and the light absorption coefficient A can decrease. Intrinsic semiconductor film 133 changes the wavelength range of sunlight that can be absorbed according to its band gap energy value. Accordingly, since the band gap energy of the intrinsic semiconductor film 133 changes continuously, the wavelength band of sunlight (eg, visible light) that can be absorbed can be increased. Even if the intrinsic semiconductor film 133 remains in an amorphous state, the bandgap energy may have a value between about 2.0 eV and about 1.5 eV by increasing the hydrogen dilution ratio.

  When the intrinsic semiconductor film 133 is formed by depositing i-Si on a thin film on which sunlight is incident, such as the p-type semiconductor film 131, when the hydrogen dilution ratio is fixed as in a general method. When the hydrogen dilution ratio is gradually increased as in the present embodiment as compared with the obtainable light efficiency (eg, approximately 9%), the characteristics of the intrinsic semiconductor film 133 are changed continuously or gradually. High light efficiency (eg, approximately 9.8%) can be obtained. This light efficiency is obtained by laminating a p-Si film 131, an intrinsic amorphous Si film 133 whose hydrogen content changes continuously, and an n-Si film 135, and p-Si film 131 and i-Si film 133 The hydrogen content in the i-Si film 133 adjacent to the first interface 133a is equal to 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. It is a value obtained from the single-junction amorphous Si thin film solar cell 100 manufactured to be larger than the amount. Here, the direction in which the hydrogen content changes can be very important. For example, the hydrogen content in the i-Si film 133 adjacent to the first interface 133 a between the p-Si film 131 and the i-Si film 133 is a second value between the i-Si film 133 and the n-Si film 135. When manufactured so as to be smaller than the hydrogen content in the i-Si film 133 adjacent to the interface 133b, a light conversion efficiency of only about 5.8% can be obtained.

Referring to FIGS. 1A and 1B again, 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 vapor-depositing an n-type semiconductor in which a Group 4 element is doped with a Group 5B element such as phosphorus P. The semiconductor constituting the n-type semiconductor film 135 can include Si. In addition to Si, the p-type semiconductor film 131 can include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof. As an example, the n-type semiconductor film 135 is formed by depositing n-Si by plasma enhanced chemical vapor deposition (PECVD) using a gas of SiH ₄ and H ₂ and an n-type dopant precursor gas (eg, PH ₃ ). Can be formed. The n-type semiconductor film 135 may be amorphous, monocrystalline, polycrystalline, microcrystalline (or nanocrystalline), or a mixed structure of amorphous and nanocrystalline. As described above, the p-type diode structure cell 130 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.

  A rear reflective film 160 can be formed on the n-type semiconductor film 135 (S160). The rear reflective film 160 may be formed to reduce the reflection loss of sunlight, maximize the light trapping effect, and improve the efficiency of the solar cell 100. For example, the rear reflective film 160 is formed by sputtering or chemical deposition of a material (for example, a film containing ZnO, Zn: Al, ZnO: Ga, ZnO: B, and ZnO) that is the same as or similar to the oxide transparent electrode 120 listed above. It can be formed using a vapor deposition process or an electron beam evaporation method (E-beam evaporation).

  A metal electrode 170 may be formed on the rear reflective film 160 as a rear electrode (S170). The metal electrode 170 may be formed of a transparent or opaque material with a single film or multiple film structure. As an example, the metal electrode 170 can be formed by evaporating Al, Ag, Cu, ZnO / Ag, ZnO / Al, Ni / Al, or the like. Through the series of processes, the thin film solar cell 100 of FIG. 1A can be formed.

<Operation Principle of First Embodiment>
FIG. 1D is a cross-sectional view illustrating the operating principle of a thin film solar cell according to an embodiment of the present invention.

  Referring to FIG. 1D, sunlight may be incident on the transparent substrate 110. Incident sunlight is absorbed by the intrinsic semiconductor film 133 to generate a plurality of electrons and a plurality of holes. Since the intrinsic semiconductor film 133 can be depleted by the p-type semiconductor film 131 and the n-type semiconductor film 135, an electric field (electric field) can be generated therein. 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 the internal electric field. 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, thereby forming the p-type semiconductor film 131 and the n-type semiconductor film 135. In the meantime, photovoltaic can be generated. If a load 180 is connected between the transparent electrode 120 that can collect holes (h +) and the metal electrode 170 that can collect electrons (e−), a current can flow.

<Modification 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 textured surface. If the surface of the transparent electrode 120 is textured, reflection of incident sunlight can be reduced, and the light absorption rate can be increased. Texturing is made by an etching process when the transparent electrode 120 is deposited or after deposition. In addition, at least one of the cell 130, the rear reflective film 160, and the metal electrode 170 may have a texturing surface.

  Referring to FIG. 1F, the thin film solar cell 104 may have a double junction super straight structure. As an example, the thin film solar cell 104 may further include a second cell 140 having a pin structure on the first cell 130 having a pin structure. The first cell 130 may be substantially the same structure as the cell 130 of FIG. 1A.

  The second cell 140 can be formed by sequentially depositing 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 may be substantially the same as or similar to the first p-type semiconductor film 131 and the second n-type semiconductor film 145 may be formed in the same manner as the first n-type semiconductor film 135. . The second intrinsic semiconductor film 143 may be substantially the same as the first intrinsic semiconductor film 133, or may be an amorphous film that is formed using the substantially same hydrogen dilution ratio.

  As another example, the second intrinsic semiconductor film 143 is formed of an amorphous film similarly to the first intrinsic semiconductor film 133, but can be formed using different hydrogen dilution ratios. For example, the hydrogen dilution ratio of the first intrinsic semiconductor film 143 may be 1 to 10, and the hydrogen dilution ratio of the second intrinsic semiconductor film 143 may be 10 to 20, or vice versa. Since the hydrogen dilution ratios are different from each other in the deposition process, one of the first intrinsic semiconductor film 133 and the second intrinsic semiconductor film 143 is a low-density amorphous film, The other can be a dense amorphous film. The hydrogen dilution ratio can increase as it goes along the direction in which sunlight is incident. The value of the hydrogen dilution ratio here is merely an example, but is not intended to limit the present invention.

  As another example, one of the first intrinsic semiconductor film 133 and the second intrinsic semiconductor film 143 is an amorphous film, and the other is a crystalline film (eg, a fine crystalline material). Film, single crystal film, polycrystalline film). As another example, one of the first intrinsic semiconductor film 133 and the second intrinsic semiconductor film 143 is an amorphous film, and the other is a crystalline film and an amorphous film. It may be a mixed film.

  Referring to FIG. 1G, the thin film solar cell 106 may have a triple junction super straight structure. For example, the thin film solar cell 106 further includes a second cell 140 having a pin structure and a third cell 150 having a pin structure on the first cell 130 having a pin structure. Can be included. The first cell 130 may be substantially the same structure as the cell 130 of FIG. 1A.

  The second cell 140 can be formed by sequentially depositing 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 may be substantially the same as or similar to the first p-type semiconductor film 131 and the second n-type semiconductor film 145 may be formed in the same manner as the first n-type semiconductor film 135. .

  The third cell 150 can be formed by sequentially depositing 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 as or similar to the first cell 130 and / or the second cell 140. The third p-type semiconductor film 151 is 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 the first n-type semiconductor film 135 and / or The second n-type semiconductor film 145 may be substantially the same as or similar to the second n-type semiconductor film 145. The third intrinsic semiconductor film 153 can 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 third intrinsic semiconductor film 153 is formed of an amorphous film similarly to the first intrinsic semiconductor film 133 and / or the second intrinsic semiconductor film 143, and uses different hydrogen dilution ratios. Can be formed. For example, the hydrogen dilution ratio of the first intrinsic semiconductor film 133 is 1 to 7, the hydrogen dilution ratio of the second intrinsic semiconductor film 143 is 7 to 15, and the hydrogen dilution ratio of the third intrinsic semiconductor film 153 is 15 to 20. It can be. As another example, one of the first intrinsic semiconductor film 133 and the third intrinsic semiconductor film 153 has a hydrogen dilution ratio of 7 to 15, and the other one has a hydrogen dilution ratio of 15 to 20. The hydrogen dilution ratio of the second intrinsic semiconductor film 143 may be 1 to 7. As another example, one of the first intrinsic semiconductor film 133 and the third intrinsic semiconductor film 153 has a hydrogen dilution ratio of 1 to 7, and the other one of the hydrogen dilution ratios is 7 to 15. The hydrogen dilution ratio of the second intrinsic semiconductor film 133 may be 15-20. As another example, at least one of the first to third intrinsic semiconductor films 133, 143, and 153 may be formed under process conditions having continuously different hydrogen dilution ratios. The hydrogen dilution ratio can increase as it goes along the direction in which sunlight is incident.

  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 is an amorphous film, and the remaining is a mixed film of a crystalline film and an amorphous film. possible.

<Embodiment 2>
FIG. 2A is a cross-sectional view illustrating a thin film solar cell according to a modified embodiment of the present invention. FIG. 2B is a flowchart showing a method for 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 battery according to a modified embodiment of the present invention.

  Referring to FIG. 2A, a thin film solar cell 200 is a single junction in which a metal electrode 270, a nip structure cell 230, and a transparent electrode 220 are sequentially stacked on an opaque substrate 210 in a thin film form. It can be a single junction substrate structure. As an example, the cell 230 may include an n-type semiconductor film 235, an intrinsic semiconductor film 233, and a p-type semiconductor film 231 that 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 that 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. Sunlight can be incident on the transparent electrode 220.

  Referring to FIG. 2B together with FIG. 2A, an opaque substrate 210 may be provided (S210), and a metal electrode 270 may be formed on the opaque substrate 210 as a rear electrode (S270). The metal electrode 270 may be formed of a transparent or opaque material such as Al, Ag, Cu, ZnO / Ag, ZnO / Al, or Ni / Al in a single film or multiple film structure.

  The rear reflective film 260 can be formed on the metal electrode 270 (S260). According to the present embodiment, since sunlight is incident on the transparent electrode 220, the use of an opaque substrate 210 such as a metal substrate is prevented. As another example, a transparent substrate as shown in FIG. 1A can be adopted instead of the opaque substrate 210. The rear reflective film 260 can be formed of the same or similar material as the oxide transparent electrode 120 listed above, for example, a film containing Zn: Al, ZnO: Ga, ZnO: B, and ZnO.

  An n-type semiconductor film 235 is formed on the metal electrode 270 (S235), an intrinsic semiconductor film 233 is formed on the n-type semiconductor film 235 (S233), and a p-type semiconductor film 231 is formed on the intrinsic semiconductor film 233. (S231), a cell 230 having an nip structure can be formed. 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 of FIG. 1A. . For example, at least one of the n-type semiconductor film 235 and the p-type semiconductor film 231 is amorphous including Si, SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof. It may be a crystalline film, a fine crystalline film, a single crystalline film, a polycrystalline film, or an amorphous film-nanocrystalline mixed film.

The intrinsic semiconductor film 233 can be formed to be substantially the same as the intrinsic semiconductor film 133 of FIG. 1A, or similarly, an amorphous film whose characteristics are continuously changed along its thickness direction. For example, it can be formed such that the hydrogen dilution ratio gradually increases as it goes along the direction in which sunlight is incident (that is, the distance from the surface on which sunlight is incident). According to the present embodiment, H ₂ is added to a Si precursor source gas such as SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiH ₃ Cl, SiHCl _3, etc., and plasma enhanced chemical vapor deposition (PECVD). The intrinsic semiconductor film 233 can be formed by evaporating i-Si on the n-type semiconductor film 235. The intrinsic semiconductor film 233 can include SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof in addition to Si. According to the present embodiment, the intrinsic semiconductor film 233 can be formed by gradually reducing the hydrogen dilution ratio. As shown in FIG. 2C, in the intrinsic semiconductor film 233, the hydrogen dilution ratio R increases and the hydrogen content decreases as it goes along the direction in which sunlight is incident. That is, the hydrogen dilution ratio R increases continuously from the first interface 233a to the second interface 233b without the formation of an obvious interface, and the hydrogen content can decrease continuously. For example, the hydrogen dilution ratio R may be 1 to 20 as an example that does not limit the present invention. Thus, the hydrogen dilution ratio R can be continuously increased as the distance from the transparent electrode 220 to which sunlight is incident is increased and / or as the distance from the opaque substrate 210 is decreased. In the intrinsic semiconductor film 233, the band gap energy B and the light absorption coefficient A of the intrinsic semiconductor film 233 gradually increase from the first interface 233a to the second interface 233b in addition to the gradual change of the hydrogen dilution ratio R. The density D can gradually increase.

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

<Operation Principle of Embodiment 2>
FIG. 2D is a cross-sectional view illustrating the operating principle of a thin film solar cell according to a modified embodiment of the present invention.

  Referring to FIG. 2D, sunlight may be incident on the transparent electrode 220. Incident sunlight can be absorbed by the intrinsic semiconductor film 233 to generate a plurality of electrons and a plurality of holes. Electrons (e−) can be drifted and accumulated in the n-type semiconductor film 235 and holes (h +) can be drifted and accumulated in the p-type semiconductor film 231 by the internal electric field of the intrinsic semiconductor film 233. Accordingly, a photovoltaic voltage can be generated between the p-type semiconductor film 231 and the n-type semiconductor film 235, so that if a load 280 is connected between the transparent electrode 220 and the metal electrode 27, the current Can flow.

<Modification of Embodiment 2>
2E to 2G are cross-sectional views illustrating thin film solar cells according to other embodiments of the present invention.

  Referring to FIG. 2E, the thin film solar cell 202 can include a textured structure. As an example, at least one of the transparent electrode 220, the cell 230, the rear reflective film 260, and the metal electrode 270 may have a texturing surface.

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

  The second intrinsic semiconductor film 243 can be formed substantially the same as, similar to, or different from the first intrinsic semiconductor film 233. As an example, the hydrogen dilution ratio of the amorphous second intrinsic semiconductor film 233 and the hydrogen dilution ratio of the amorphous second intrinsic semiconductor film 243 are the same, or one of them is the other. It can be larger than that. As 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 (eg, a fine crystalline material). Film, monocrystalline film, polycrystalline film), or a mixed film of a crystalline film and an amorphous film.

  Referring to FIG. 2G, the thin film solar cell 206 may have a triple junction substrate structure. For example, the thin film solar cell 206 includes a second cell 240 having an nip structure and a third cell having an nip structure between a first cell 230 having an nip structure and a metal electrode 270. 250 can be further included. The third cell 250 can be formed by sequentially depositing a third n-type semiconductor film 255, a third intrinsic semiconductor film 253, and a third p-type semiconductor film 251 on the metal electrode 270. The third cell 250 may be substantially the same as or similar to the first cell 230 and / or the second cell 240.

  The hydrogen dilution ratios of the first to third intrinsic semiconductor films 233, 243, and 253 may be the same or different from each other. As an example, the first to third intrinsic semiconductor films 233, 243, and 253 may be amorphous films in which the hydrogen dilution ratio increases or decreases in the stacking order. As another example, the first to third intrinsic semiconductor films 233, 243, and 253 may be an amorphous film that is decreased after the hydrogen dilution ratio is increased or increased after the decrease. . As another example, at least one of the first to third intrinsic semiconductor films 233, 243, and 253 may be formed under process conditions with continuously different hydrogen dilution ratios.

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

  The foregoing detailed description is not intended to limit the invention to the disclosed embodiments, but may be used in various other combinations, modifications, and environments without departing from the spirit of the invention. it can. The appended claims should be parsed as including other implementations.

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 ... Cells 131, 141, 151, 231, 241, 251 ... p-type semiconductor films 133, 143, 153, 233, 243, 253 ... intrinsic semiconductor films 135, 145, 155, 235, 235, 255 ... n-type semiconductor film 160, 260... rear reflective film 170, 270... metal electrode 180, 280.

Claims (9)

A substrate,
Between the first n-type impurity semiconductor film, the first p-type impurity semiconductor film, and the first n-type impurity semiconductor film and the first p-type impurity semiconductor film disposed on the substrate. A first amorphous film including an intrinsic semiconductor having a hydrogen content that continuously changes, and a first cell in which is inserted,
A metal electrode adjacent to the first n-type impurity semiconductor film;
A transparent electrode adjacent to the first p-type impurity semiconductor film,
The hydrogen content of the first amorphous film is opposite to the light incident from the first interface with the first p-type impurity semiconductor film disposed on the light incident side. The thin film solar cell which becomes continuously smaller as it goes to the second interface with the first n-type impurity semiconductor film disposed on the opposite side. The substrate includes 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,
The thin film solar cell according to claim 1, wherein light is incident on the transparent substrate. Between the first cell and the metal electrode,
A second p-type semiconductor film, a second intrinsic semiconductor film having a continuously changing hydrogen content, and a second n-type semiconductor film are sequentially stacked on the first n-type semiconductor film. Further comprising at least one second cell;
The second intrinsic semiconductor film includes at least one of an amorphous film containing intrinsic silicon and a crystalline film,
The thin film solar cell according to claim 2, wherein the hydrogen content of the second intrinsic semiconductor film continuously decreases as the distance from the transparent substrate increases. The substrate includes 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 are sequentially stacked on the opaque substrate,
The thin film solar cell according to claim 1, wherein light is incident on the transparent electrode. Between the first cell and the metal electrode,
A second cell in which a second n-type semiconductor film, a second intrinsic semiconductor film having a continuously changing hydrogen content, and a second p-type semiconductor film are sequentially stacked on the metal electrode. At least one further,
The second intrinsic semiconductor film includes at least one of an intrinsic amorphous film, an intrinsic microcrystalline silicon film, and an intrinsic crystalline film;
The thin film solar cell according to claim 4, wherein the hydrogen content of the second intrinsic semiconductor film continuously decreases as the distance from the opaque substrate decreases. The first amorphous film includes:
The thin film solar cell according to claim 1, which is made of silicon or includes SiGe, SiC, SiO, SiN, SiON, SiCN, SiGeO, SiGeN, SiGeC, or a combination thereof. Providing the substrate,
On the substrate, a p-type semiconductor film, an n-type semiconductor film, and a non-intrinsic semiconductor having a continuously changing hydrogen content disposed between the p-type semiconductor film and the n-type semiconductor film are included. Forming a cell containing a crystalline film,
Forming a transparent electrode adjacent to the p-type semiconductor film;
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 decreases continuously from the incident surface toward the opposite surface. The substrate includes a transparent substrate disposed adjacent to the incident surface;
Forming the cell comprises:
Forming the p-type semiconductor film on the transparent substrate;
Providing a reaction gas obtained by diluting a semiconductor source gas with hydrogen on the p-type semiconductor film, and forming the amorphous film while gradually increasing the dilution ratio of the hydrogen;
The method of manufacturing a thin film solar cell according to claim 7, comprising forming the n-type semiconductor film on the amorphous film. The substrate includes an opaque substrate disposed adjacent to the opposite surface;
Forming the cell comprises:
Forming the n-type semiconductor film on the opaque substrate;
Providing a reaction gas obtained by diluting a semiconductor source gas with hydrogen on the n-type semiconductor film, and forming the amorphous film while gradually reducing the dilution ratio of the hydrogen;
The method for manufacturing a thin-film solar cell according to claim 7, comprising forming the p-type semiconductor film on the amorphous film.

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