KR20110013009A - Photovoltaic device including plural back contact metal layers and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A thin film solar cell having a plurality of rear electrodes and a method of manufacture thereof are provided to improve the photovoltaic conversion efficiency and the device quality property by forming the rear electrode layer minimizing the contact resistance between the light absorption layer and the rear electrode. CONSTITUTION: A transparent conduction layer(102) is formed on a transparent substrate(100). A light absorption layer(106) is formed on the transparent conduction layer. A first rear electrode(108) and a second rear electrode(110) are formed on the light absorption layer. A rear contact electrode(112) is formed on the second rear electrode layer.

Description

Thin film solar cell having a plurality of back electrode layers and a method of manufacturing the same {Photovoltaic device including plural back contact metal layers and Manufacturing method

The present invention relates to a thin film solar cell and a manufacturing method thereof, and more particularly, to a solar cell having a structure in which a plurality of contact electrode layers are inserted between a light absorption layer and a metal back electrode in order to reduce contact resistance with a rear electrode in a CdTe thin film solar cell; The manufacturing method is related.

Recently, due to global environmental problems and resource depletion, interest in alternative energy of environment is increasing. In addition, following the entry into force of the climate treaty to prevent global warming, Korea has also been required to prepare government-level countermeasures to resolve air pollution and reduce carbon dioxide gas in accordance with the Post-Kyoto Protocol.

In this situation, solar power is a technology that attracts much attention from people.

Sunlight is the richest, pollution-free clean energy source on the planet, with a total of about 120,000 terawatts (120 × 1015 W) of solar energy delivered to the earth. That's about 10,000 times the total energy used by humans on Earth, and developing technologies that make use of this solar energy would be a viable solution to the country's immediate energy and environmental problems.

Solar cells that use electricity to generate electricity are generally manufactured using silicon. Currently, bulk silicon solar cells based on wafers cannot be actively utilized due to high manufacturing cost and installation cost.

In order to solve such a cost problem, researches on thin-film solar cells that can be produced at low cost have been actively conducted, and various attempts to manufacture high efficiency solar cell modules have been proposed and studied.

Currently, solar cells using CdTe among various thin-film solar cells have attracted attention as they increase their market share. However, the efficiency of CdTe solar cell mass production module is currently about 10%, there are a number of issues that need to be resolved to increase the efficiency of CdTe solar cell for market share improvement.

An object of the present invention is to increase the photoelectric conversion efficiency of a thin film solar cell by reducing the contact resistance between each stacked thin film of the thin film solar cell.

Another object of the present invention is to provide a thin film solar cell having a high doping concentration of a charge carrier and preventing deterioration, thereby stabilizing quality characteristics of the device.

On the other hand, by providing a method for easily forming a back electrode layer to reduce the contact resistance of the thin film solar field is to improve the mass production of high efficiency thin film solar cell and to reduce the process cost economically in terms of production cost.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

A thin film solar cell according to an embodiment of the present invention for achieving the above object is a transparent substrate, a transparent conductive layer formed on the transparent substrate, a light absorption layer formed on the transparent conductive layer and made of a semiconductor, and the light absorption A back electrode is formed on the layer, and a plurality of layers formed between the light absorption layer and the back electrode, and each layer includes a back electrode layer made of different metal compounds.

The transparent substrate may be used as long as the substrate of the transparent material so that light can pass through well. In particular, a glass substrate, a transparent polymer film, or a plastic film may be used. Inexpensive sodalime glass can be used as the glass substrate, resulting in reduced manufacturing costs.

The transparent conductive layer includes one formed of a transparent conductive oxide (TCO) thin film for the transmission of sunlight incident from the transparent substrate side. Also, in some cases, Fluoride doped tin oxide (FTO), Indium tin oxide (ITO), Aluminum doped zinc oxide (AZO), Indium zinc oxide (IZO), Zinc oxide (ZnO), CdO, SnO ₂ (Tin oxide), In ₂ O ₃ , CdSnO ₄ or TO (tin oxide) may be used as the transparent conductive layer, but is not necessarily limited thereto.

In the present invention, the light absorption layer may be composed of a group II-VI compound semiconductor composed of group II elements and group VI elements on the periodic table, or a group III-V compound semiconductor composed of group III elements and group V elements.

In particular, all of the II-VI compound semiconductor layers have a direct transition energy band structure and have a very large light absorption coefficient in the wavelength region below the absorption edge. As a component of the solar cell, an absorbing layer that sufficiently absorbs light is required to generate a carrier. When the II-VI compound semiconductor is used as the light absorbing layer material, the thickness of the semiconductor is reduced, thereby reducing the material cost and exess minority. The diffusion length of the carrier is also shortened, and thus, the demand for quality of the semiconductor is alleviated, thereby making it easier to manufacture.

The light absorption layer is ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgO, MgS, MgSe, MgTe, HgO, HgS, HgSe, HgTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs GaSb, InN, InP, InAs, InSb, TlN, TlP, TlAs, TlSb, and mixtures thereof.

In particular, in order to manufacture a photovoltaic cell with high photoelectric conversion efficiency, the energy bandgap of the light absorption layer material is suitable around 1.4 eV in the matching relationship with the solar spectrum, and the diffusion length of the electron is longer than that of the hole. Type semiconductors are advantageous. CdTe and CdSe are materials close to 1.4 eV in energy bandgap. However, CdTe is the most suitable material for the light absorption layer of group II-VI compound semiconductors because only CdTe exhibits conduction at both sides of p and n.

In the present invention, the metal compound is zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), selenium (Se), tantalum ( One or more metal elements selected from Ta), vanadium (V), and antimony (Sb) may be included, but is not necessarily limited thereto.

In the present invention, the back electrode layer may play a role of reducing contact resistance between the light absorption layer and the rear electrode, and by selecting and depositing a material having a good long wavelength transmittance, the light absorption in the light absorption layer is increased to increase the photoelectric conversion efficiency. The improvement can be maximized.

In addition, as an embodiment of the present invention, the back electrode layer may be in contact with the light absorbing layer, at least one first back electrode layer made of a metal compound having a small contact barrier with the light absorbing layer, and in contact with the back electrode. The carrier concentration may include at least one second back electrode layer made of a metal compound having a higher concentration than the first back electrode layer.

However, as an example, the back electrode layer may have two or more separate layers made of different metal compounds.

The rear electrode layer of the plurality of layers may be arranged such that the contact barrier with the light absorbing layer has a smaller contact barrier, and the layer contacting the rear electrode of the solar cell has a higher charge carrier concentration to the metal electrode. In the present invention, the thickness of the plurality of back electrode layers may be in the range of 10 nm to 500 nm, respectively.

As an embodiment of the present invention, the metal compound of the second back electrode layer may include copper-doped zinc telluride (ZnTe: Cu), copper telluride (Cu _x Te), copper sulfide (Cu _x S), and antimony tellurium. Compound (Sb ₂ Te ₃ ), and the like.

In the second back electrode layer, the charge transporter may be copper (Cu) or nitrogen (N) doped in the second back electrode layer, but is not limited thereto. The electron-hole charges separated from the light absorption layer may be If the material can function to be mailed to the second back electrode layer may be doped.

The doping concentration of the charge carriers such as copper (Cu) or nitrogen (N) should be higher in the second back electrode layer in contact with the back electrode than in the first back electrode layer.

Preferably, the charge carrier concentration of the second back electrode layer has a higher concentration gradient (inclination) toward the contact surface with the back electrode even in the second back electrode layer.

In addition, the first back electrode layer may not be doped with a separate dopant as a charge carrier. That is, the first back electrode layer may not be doped with copper (Cu) or nitrogen (N), or even if doped, the doping concentration of copper (Cu) or nitrogen (N) from the contact surface with the light absorbing layer is low to high. Have a concentration gradient.

However, as described above, the charge carrier concentration of copper (Cu) or nitrogen (N) doped in the first back electrode layer is lower than the doping concentration of the second back electrode layer.

That is, the doping concentration of copper (Cu) or nitrogen (N) in the first back electrode layer is a concentration gradient of high concentration at low concentration in a range of 0wt% to 10wt% from the contact surface with the light absorbing layer to the contact surface with the second back electrode layer. It can have

In an embodiment of the present invention, the transparent conductive layer and the light absorbing layer may further include a window layer made of a II-VI compound semiconductor or a III-V compound semiconductor, and in particular, the window layer may include cadmium sulfide ( CdS).

In one embodiment of the present invention, a buffer layer made of any one material selected from CuS _1-x O _x , ZnS _1-x O _x , and Zn ₂ SnO ₄ is added between the transparent conductive layer and the window layer. It may further include.

In the present invention, the back electrode may be formed of a conductive metal electrode and is not particularly limited, but Ag, Al, ZnO / Ag, ZnO / Al, or the like may be used.

According to an aspect of the present invention, there is provided a method of manufacturing a thin film solar cell, the method comprising sequentially forming a transparent conductive layer, a window layer, and a light absorbing layer on a transparent substrate, and using different metal compounds on the light absorbing layer. And forming a back electrode layer of at least two layers, and forming a back electrode on the back electrode layer.

The metal compound is zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), selenium (Se), tantalum (Ta), One or more metal elements selected from vanadium (V) and antimony (Sb) may be included, but is not necessarily limited thereto.

The forming of the bottom electrode layer according to an embodiment of the present invention may include forming a first back electrode layer made of zinc telluride (ZnTe) on the light absorption layer, and doping copper on the first back electrode layer. Forming a second back electrode layer made of at least one of zinc telluride (ZnTe: Cu), copper telluride (Cu _x Te), copper sulfide (Cu _x S), and antimony tellurium compound (Sb ₂ Te ₃ ) It can be made to the step.

The first back electrode layer does not dope copper (Cu) or nitrogen (N), or increases the doping concentration of copper (Cu) or nitrogen (N) from low concentration to high concentration from the contact surface with the light absorbing layer. Or nitrogen (N).

Copper (Cu) or nitrogen (N) will function as a charge carrier in the first back electrode layer, which may be lower or undoped than the second back electrode layer as described above.

If doped, the range may be doped to have a low concentration gradient at low concentrations in the range of 0 wt% to 10 wt%.

The doping method of the charge transporter can be sufficiently applied as long as it is a conventionally known technique.

Forming the back electrode layer according to an embodiment of the present invention, zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten ( At least one metal element selected from W), selenium (Se), tantalum (Ta), vanadium (V), and antimony (Sb) at the same time or at the same time and then heat-treated, or zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), selenium (Se), tantalum (Ta), vanadium (V), It may be formed by forming a metal alloy source including at least one or more of antimony (Sb) by depositing it.

In one embodiment of the present invention, the back electrode layer, evaporation (sputtering), sputtering (sputtering), ion plating (ion plating), ion beam evaporation (ion beam evaporation), vacuum deposition, electrodeposition (electrodeposition), Screen Printing, Close-spaced Sublimation (CSS), Organometallic Chemical Vapor Deposition (MOCVD), Physical Vapor Deposition (PVD), Plasma Chemical Vapor Deposition (PECVD), CBD (Chemical Bath Deposition), VTD Method It may be laminated by a method such as (Vapor transport deposition).

In the method of manufacturing a thin film solar cell of the present invention, the window layer and the light absorbing layer may be made of a II-VI compound semiconductor or a III-V compound semiconductor. Preferably, the window layer may be a CdS layer, and the light absorption layer May be a CdTe layer.

The window layer and the light absorption layer may be laminated by a known method, and the lamination method is not particularly limited, but the sputtering method, chemical vapor deposition, organic metal chemical vapor deposition (MOCVD), and close sublimation Close-spaced sublimation (CSS), Spray pyrolysis, Chemical spraying, Screeen printing, CBD (Chemical bath deposition), VTD (Vapor transport deposition) , And electrodeposition may be used.

In addition, according to an embodiment of the present invention, between the step of forming the transparent conductive layer and the window layer, made of any one material selected from CuS _1-x O _x , ZnS _1-x O _x , Zn ₂ SnO ₄ A further step of forming a buffer layer may be added.

According to the present invention, a thin film solar cell, in particular, a CdTe thin film solar cell, in which the photoelectric conversion efficiency and device quality characteristics of the thin film solar cell are improved by proposing a structure in which a back electrode layer is inserted to minimize the contact resistance between the light absorption layer and the rear electrode. Can provide.

According to the present invention, by proposing a solar cell structure that can be stabilized in quality reliability without deterioration in a thin film solar cell, there is an effect of manufacturing and supplying a mass-productable and economical thin film solar cell in the solar cell market.

In addition, according to the present invention, as a low-cost, high-efficiency thin-film solar cell is produced, the renewable energy field is expanded, thereby reducing the emission of pollutants that accelerate global warming, such as carbon dioxide, and thus may be helpful for environmental protection.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view illustrating a contact barrier generated when a light absorbing layer contacts a back electrode.

1 illustrates a problem with the efficiency of a conventional thin film solar cell, and as shown in FIG. 1, the CdTe light absorbing layer and the work function of the light absorbing layer of the thin film solar cell, in particular, the CdTe solar cell are large. There is a problem that the large contact resistance with the metal electrode should be reduced.

Therefore, it is necessary to reduce such a contact barrier in improving the photoelectric conversion efficiency of the thin film solar cell with high efficiency.

The thin film solar cell of the present invention proposes a structure and a material for improving the contact resistance between the CdTe light absorbing layer and the metal electrode, and shows a sectional view of the thin film solar cell according to the exemplary embodiment of the present invention.

The thin film solar cell according to the exemplary embodiment of the present invention shown in FIG. 2 may be a CdTe solar cell in which a light absorption layer is formed of a CdTe layer.

Referring to FIG. 2, the thin film solar cell according to the exemplary embodiment of the present invention is manufactured to have a superstrate structure in which light is incident through the transparent substrate 100. The transparent substrate 100 is preferably a glass substrate, but is not limited thereto.

In addition, a transparent conductive layer 102 (TCO) is formed on the transparent glass substrate 100 to function as a transparent electrode having good transmittance.

Next, the window layer 104 used as the n-type layer of the CdTe solar cell is formed, and mainly CdS is generally used.

Thereafter, the light absorption layer 106 is deposited on the window layer 104, and in particular, CdTe is deposited on the order of several μm.

At least two back electrode layers are deposited on the light absorption layer 106 to reduce contact resistance.

Conventional thin film solar cells use a layer doped with Cu to ZnTe to reduce the contact resistance, but this material has a small contact barrier with CdTe, but has a disadvantage in that the contact resistance with a metal electrode is increased due to the low charge carrier concentration. . In order to solve this disadvantage, increasing the concentration of the carrier by increasing the doping concentration of Cu, since the excess Cu diffuses into the CdTe layer, rather, the efficiency is lowered, there is also a limit to increasing the amount of doping. Accordingly, a multi-layered structure of the back electrode layer according to the exemplary embodiment of the present invention is required so that the charge carrier concentration is increased for tunneling with the metal electrode while the contact barrier with the CdTe is small.

The embodiment of FIG. 2 proposes two layers of back electrode layers, but is not necessarily limited thereto, and may be manufactured by inserting triple or quadruple back electrode layers according to a use purpose.

In the exemplary embodiment of FIG. 2, the first back electrode layer 108 and the second back electrode layer 110 are formed on the light absorption layer 106.

The first back electrode layer 108 is a layer in direct contact with the light absorption layer 106 and may deposit a material having a small contact resistance with the CdTe layer. In one embodiment, a material such as ZnTe may be stacked, and in some cases, a small amount of doping element may be included in consideration of the characteristics of ZnTe. The doping element is not particularly limited but may be an element such as copper (Cu) or nitrogen (N).

The second back electrode layer 110 is a layer in contact with the back electrode 112, and may deposit a material having a high concentration of charge carriers to reduce resistance with the metal electrode. In one embodiment, a material such as Cu ₂ Te may be stacked, but is not limited thereto. Zinc telluride (ZnTe: Cu), copper sulfide (Cu _x S), and antimony tellurium compound (Sb ₂ Te ₃ ) may be used. The materials may be stacked.

For example, the amount of each element may be selected and deposited in consideration of the influence of the charge carrier concentration and the diffusion of the doped elements in the deposition process of the second back electrode layer 110. That is, in the case of depositing a material such as Cu ₂ Te as the second back electrode layer, the amount of Cu and Te may be selected and deposited in consideration of the effect of diffusion of copper (Cu), which is a doped element.

The thicknesses of the first back electrode layer 108 and the second back electrode layer 110 may be deposited from several tens of nm to several hundred nm, and preferably, from 10 nm to 500 nm. What is necessary is just to determine the thickness according to each vapor deposition condition and a characteristic.

As described above, the back electrode layer may be deposited as a triple, quadruple, or more layers. According to an embodiment of the present invention, each back electrode layer may have different contact resistances between the light absorbing layer and the rear electrode due to different metal compounds. It can be deposited to improve the.

In the embodiment of FIG. 2, a back electrode 112 is deposited on the second back electrode layer 110. The back electrode refers to a conductive metal electrode layer, wherein the metal electrode layer is deposited by selecting a suitable metal such as Au, Al, Ti, and the like.

Although not shown in FIG. 2, a buffer layer made of a material such as CuS _1-x O _x , ZnS _1-x O _x , Zn ₂ SnO _4, or the like, is disposed between the transparent electrode layer 102 and the window layer 104. This may be further included. The buffer layer can reduce the thickness of the window layer, prevent leakage current, and increase light transmittance to a short wavelength region.

3 shows an energy band gap of a structure of a thin film solar cell according to an embodiment of the present invention as described above.

The material of the film layer shown in the graph of FIG. 3 is CdTe, ZnTe, Cu ₂ Te, and a metal, respectively, which constitutes a light absorption layer, a first back electrode layer, a second back electrode layer, and a back electrode.

According to Figure 3 can be seen the energy bandgap level when the ZnTe and Cu ₂ Te material layer is inserted as the back metal layer between the CdTe layer and the metal layer. That is, it can be seen that the contact barrier is lowered at the interface between the CdTe layer and the first back electrode layer, while the contact barrier is lowered due to the higher charge carrier density at the interface between the second back electrode layer and the metal metal electrode.

The back electrode layer deposited as a plurality of layers has a property of reducing contact resistance, and in order to reduce contact resistance with a metal electrode when the first back electrode layer contacting CdTe does not contain Cu as a doping element. Since Cu does not need to be used, deterioration due to Cu can be reduced, and the reduction in safety efficiency is markedly reduced.

4 to 6 are simplified views of a method of forming a back electrode layer of a thin film solar cell according to an embodiment of the present invention.

In the method proposed in FIGS. 4 to 6, after the transparent electrode 102, the window layer 104, and the light absorption layer 106 are all deposited on the transparent substrate 100, the back electrode layer may be formed of a plurality of layers. Only the method of time is shown.

Referring to FIG. 4, as one method, an appropriate heat treatment is performed after depositing each element (in the drawing, each constituent element of the metal compound constituting the back electrode layer as A and B) on the substrate on which the light absorption layer is deposited. It shows forming a back electrode layer made of a metal compound. After the heat treatment, the AB compound thin film layer is formed as the metal compound constituting the back electrode layer.

FIG. 5 is a method of forming a back electrode layer according to another embodiment, wherein each element of the metal compound constituting the back electrode layer, that is, A and B, is simultaneously deposited on a substrate on which the light absorption layer is deposited, and then heat-treated to form an AB compound alloy layer. It is shown.

In addition, FIG. 6 is a method of forming a back electrode layer according to another embodiment, and after manufacturing each alloying element of the metal compound, that is, A and B in the manufacturing step of the raw material source gas during deposition, to produce an alloy source gas It is a process of depositing by supplying an absorption layer on the deposited substrate.

The method of manufacturing the back electrode layer may be manufactured by various methods because various elements exist in the form of an alloy, and may be formed by various known methods without necessarily being limited to the above-described methods.

The deposition method of the back electrode layer may be manufactured by selecting an appropriate deposition method in consideration of its characteristics and ease of manufacture.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and such changes or modifications are within the scope of the present invention. In addition, the materials of each component described herein can be readily selected and substituted for various materials known to those skilled in the art. Those skilled in the art will also appreciate that some of the components described herein can be omitted without degrading performance or adding components to improve performance. In addition, those skilled in the art may change the order of the method steps described herein depending on the process environment or equipment. Therefore, the scope of the present invention should be determined by the appended claims and equivalents thereof, not by the embodiments described.

1 is a view illustrating a contact barrier generated when a light absorbing layer contacts a back electrode.

Figure 2 is a cross-sectional view showing the configuration of a thin film solar cell according to an embodiment of the present invention.

3 is a view showing an energy band gap of a structure of a thin film solar cell according to an embodiment of the present invention.

4 to 5 are simplified views of a method of forming a back electrode layer of a thin film solar cell according to an embodiment of the present invention.

{Description of major symbols in the drawing}

100: transparent substrate 102: transparent conductive layer

104: window layer 106: light absorption layer

108: first back electrode layer 110: second back electrode layer

112: rear electrode

Claims (25)

Transparent substrate; A transparent conductive layer formed on the transparent substrate; A light absorption layer formed on the transparent conductive layer and formed of a semiconductor; And A back electrode formed on the light absorption layer, A thin film solar cell, comprising: a plurality of layers formed between the light absorbing layer and the back electrode, wherein each layer comprises a back electrode layer made of a different metal compound. The method of claim 1, The metal compound is zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), selenium (Se), tantalum (Ta), Thin film solar cell comprising any one or more metal elements selected from vanadium (V), antimony (Sb). The method of claim 1, The back electrode layer, At least one first back electrode layer made of a metal compound in contact with the light absorption layer and having a small contact barrier with the light absorption layer; And And at least one second back electrode layer made of a metal compound in contact with the back electrode and having a charge carrier concentration higher than that of the first back electrode layer. The method according to claim 1 or 3, The light absorption layer is a thin film solar cell, characterized in that consisting of a II-VI compound semiconductor or a III-V compound semiconductor. The method according to claim 1 or 3, The light absorption layer is ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgO, MgS, MgSe, MgTe, HgO, HgS, HgSe, HgTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs Thin film solar cell, characterized in that selected from the group consisting of GaSb, InN, InP, InAs, InSb, TlN, TlP, TlAs, TlSb, and mixtures thereof. The method of claim 3, wherein The thin film solar cell of claim 1, wherein the metal compound of the first back electrode layer is zinc telluride (ZnTe). The method of claim 3, wherein The metal compound of the second back electrode layer is copper doped zinc telluride (ZnTe: Cu), copper telluride (Cu _x Te), copper sulfide (Cu _x S), and antimony tellurium compound (Sb ₂ Te ₃ ) Thin film solar cell, characterized in that any one or more materials selected from. The method of claim 3, wherein The charge transporter is a thin film solar cell, characterized in that the copper (Cu) or nitrogen (N) doped to the second back electrode layer. The method of claim 3, wherein The charge carrier concentration of the second back electrode layer is a thin film solar cell, characterized in that it has a high concentration concentration gradient toward the contact surface with the back electrode. The method of claim 3, wherein The first back electrode layer is characterized in that the copper (Cu) or nitrogen (N) is not doped or the doping concentration of copper (Cu) or nitrogen (N) from the contact surface with the light absorbing layer has a concentration gradient from low concentration to high concentration Thin film solar cell. The method of claim 3, wherein The doping concentration of copper (Cu) or nitrogen (N) of the first back electrode layer is a concentration gradient of low concentration to high concentration in the range of 0wt% to 10wt% from the contact surface with the light absorbing layer to the contact surface with the second back electrode layer. Thin film solar cell characterized by having. The method of claim 1, The thickness of the plurality of back electrode layer is a thin film solar cell, characterized in that each of 10nm to 500nm. The method of claim 1, The thin film solar cell further comprises a window layer made of a II-VI compound semiconductor or a III-V compound semiconductor between the transparent conductive layer and the light absorption layer. The method of claim 13, The compound semiconductor is a thin film solar cell, characterized in that the cadmium sulfide (CdS). The method of claim 13, Between the transparent conductive layer and the window layer further comprises a buffer layer (buffer layer) made of any one material selected from CuS _1-x O _x , ZnS _1-x O _x , Zn ₂ SnO ₄ Thin film solar cell. The method of claim 1, The transparent conductive layer is Fluoride doped tin oxide (FTO), Indium tin oxide (ITO), Aluminum doped zinc oxide (AZO), Indium zinc oxide (IZO), Zinc oxide (ZnO), CdO, SnO ₂ (Tin oxide), In ₂ O ₃ , CdSnO ₄ A thin film solar cell comprising any one or more materials selected from the group consisting of. Sequentially forming a transparent conductive layer, a window layer, and a light absorbing layer on the transparent substrate; Forming at least two or more back electrode layers made of different metal compounds on the light absorption layer; And A method for manufacturing a thin film solar cell comprising forming a back electrode on the back electrode layer. The method of claim 17, The metal compound is zinc (Zn), tellurium (Te), copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tungsten (W), selenium (Se), tantalum (Ta), Method of manufacturing a thin film solar cell comprising any one or more metal elements selected from vanadium (V), antimony (Sb). The method of claim 17, Forming the back electrode layer, Forming a first back electrode layer made of zinc telluride (ZnTe) on the light absorption layer; And Any one of zinc telluride (ZnTe: Cu), copper telluride (Cu _x Te), copper sulfide (Cu _x S), and antimony tellurium compound (Sb ₂ Te ₃ ) doped with copper on the first back electrode layer A method of manufacturing a thin film solar cell, comprising the step of forming a second back electrode layer made of the above material. The method of claim 19, The first back electrode layer does not dope copper (Cu) or nitrogen (N), or increases the doping concentration of copper (Cu) or nitrogen (N) from low concentration to high concentration from the contact surface with the light absorbing layer. Or doping with nitrogen (N). The method of claim 20, Doping concentration of the copper (Cu) or nitrogen (N) of the first back electrode layer is a manufacturing method of a thin film solar cell, characterized in that 0wt% to 10wt%. The method of claim 17, Forming the back electrode layer, Zinc (Zn), Tellurium (Te), Copper (Cu), Molybdenum (Mo), Nickel (Ni), Titanium (Ti), Tungsten (W), Selenium (Se), Tantalum (Ta), Vanadium (V) At least one metal element selected from antimony (Sb) is deposited at the same time or at the same time, followed by heat treatment, or Zinc (Zn), Tellurium (Te), Copper (Cu), Molybdenum (Mo), Nickel (Ni), Titanium (Ti), Tungsten (W), Selenium (Se), Tantalum (Ta), Vanadium (V) , Forming a metal alloy source comprising at least one or more of antimony (Sb) by depositing it to form a method of manufacturing a thin film solar cell. The method of claim 17, The back electrode layer may include evaporation, sputtering, ion plating, ion beam evaporation, vacuum deposition, electrodeposition, screen printing, and close sublimation. -spaced sublimation (CSS), organometallic chemical vapor deposition (MOCVD), physical vapor deposition (PVD), plasma chemical vapor deposition (PECVD), CBD (chemical bath deposition), VTD (Vapor transport deposition) Method for producing a thin film solar cell, characterized in that formed by the method. The method of claim 17, The window layer and the light absorbing layer is a method of manufacturing a thin film solar cell, characterized in that consisting of a II-VI compound semiconductor or a III-V compound semiconductor. The method of claim 17, The window layer is made of CdS, the light absorption layer is a manufacturing method of a thin film solar cell, characterized in that made of CdTe.

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