KR20140120387A - Silver paste composition and electrode using the same - Google Patents

Abstract

The present invention relates to a silver paste composition and an electrode using the same, wherein the silver paste composition includes silver powder; a glass frit comprising 50-80 wt% of PbO, 5-15 wt% of B_2O_3, 0.1-10 wt% of SiO_2, 2-10 wt% of Al_2O_3, and 5-20 wt% of at least one type between ZnO and MgO; and an organic vehicle, thereby preventing the penetration of an emitter layer by the organic frit during over-firing and improving the efficiency of a solar cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a silver paste composition,

The present invention relates to a silver paste composition capable of preventing a silver electrode from penetrating through an emitter in a firing process and increasing the efficiency of a solar cell, and an electrode using the silver paste composition.

Solar cells, which are rapidly spreading in recent years, are next-generation energy sources, and are electronic devices that convert solar energy, which is clean energy, directly to electricity.

1, the p-type solar cell element has an n-type diffusion layer 20, a silicon nitride film 30, and an electrode on the front side of the p-type silicon wafer substrate 10, that is, 40 are formed. A p + layer (back field field 51) and an n + layer 52 are formed on the rear surface of the substrate 10 and a silver electrode 61 and an aluminum electrode 62 are formed as a back electrode. The n-type solar cell element is a p-type solar cell except that the p-type diffusion layer 20, the n + layer 51 on the back side of the substrate 10 and the p + layer 52 on the light receiving side are formed. And has the same structure as the solar cell element.

The rear surface of the electrode 61 is formed on a part of the rear surface side of the substrate 10 as an electrode for interconnecting solar cells by a copper ribbon or the like because it is impossible to solder the aluminum electrode 62, To 6 mm wide in the form of a bus bar.

Silver electrodes on the front and rear surfaces are formed by applying a silver paste composition containing silver powder, glass frit and an organic vehicle onto a silicon substrate by screen printing or the like, drying and baking. The silver paste composition must be capable of firing silver powder at a firing process condition of, for example, 600 to 950 DEG C for about 10 to 30 seconds for a short time.

However, when over-firing occurs, there is a disadvantage that the emitter layer (n + layer or p + layer) in contact with the silver paste composition is penetrated or the efficiency of the solar cell is lowered.

It is an object of the present invention to provide a silver paste composition capable of preventing penetration of an emitter layer when over firing occurs.

Another object of the present invention is to provide a silver paste composition capable of improving the efficiency of a solar cell.

It is still another object of the present invention to provide an electrode formed from the silver paste composition.

It is another object of the present invention to provide a solar cell element having the electrode.

1. Silver powder; 50 to 80 wt% of PbO, 5 to 15 wt% of B ₂ O ₃ , 0.1 to 10 wt% of SiO ₂ , ₂ to 10 wt% of Al ₂ O ₃ , and 5 to 20 wt% of at least one of ZnO and MgO Glass frit; And an organic vehicle.

2. The silver paste composition according to 1 above, wherein the glass frit further comprises 0.1 to 10% by weight of at least one member selected from the group consisting of CaO, SrO and BaO.

3. The silver paste composition according to 1 above, wherein the glass frit further comprises 0.1 to 20% by weight of at least one selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O.

4. The silver paste composition of claim 1, wherein the silver powder comprises a second silver powder having an average particle size that can be filled between the first silver powder and the first silver powder.

5. The silver paste composition according to 1 above, wherein the organic vehicle is a mixture of 1 to 25% by weight of a polymer resin and 75 to 99% by weight of an organic solvent.

6. The electrode of any of claims 1 to 5, wherein the electrode is formed from a paste composition.

7. A solar cell element comprising the above six electrodes.

The silver paste composition according to the present invention can prevent the penetration of the emitter layer by the organic frit during over-baking and can improve the efficiency of the solar cell because of the excellent contact property with the emitter layer.

In addition, the silver paste composition of the present invention is excellent in soldering characteristics with a ribbon when manufacturing a solar cell module, thereby reducing the defective rate and improving the productivity and the reliability of the product.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing a sectional view of a solar cell element. FIG.

The present invention relates to silver powder; 50 to 80 wt% of PbO, 5 to 15 wt% of B ₂ O ₃ , 0.1 to 10 wt% of SiO ₂ , ₂ to 10 wt% of Al ₂ O ₃ , and 5 to 20 wt% of at least one of ZnO and MgO Glass frit; And an organic vehicle to prevent the penetration of the emitter layer by the organic frit during over-baking and to improve the efficiency of the solar cell, and an electrode using the silver paste composition.

Hereinafter, the present invention will be described in detail.

The silver paste compositions of the present invention include silver powder, organic frit, and organic vehicle.

<Silver powder>

Silver powder is a conductive metal powder used for forming electrodes. The silver powder to be used in the present invention may be silver powder used in the art without any particular limitation.

In one aspect of the present invention, it may be a mixture of two powders having different average particle sizes (D ₅₀ ). Preferably, the second silver powder may have a mean particle size that can be filled between the first silver powder and the pores of the first silver powder. When the second powder is filled between the pores of the first powder, the pores of the silver electrode after firing are reduced to reduce the sheet resistance, thereby improving the efficiency of the solar cell.

Specific examples of the case where silver powder having two different average particle diameters (D ₅₀ ) are used include 60 to 95% by weight of a first powder having D ₅₀ = 0.5 to 5 μm and a powder having a D _{50 of} 10 to 500 nm 2 powder and 5 to 40% by weight of the powder.

The shape of the silver powder is not particularly limited, and examples thereof include a spherical shape, a non-spherical shape, and a plate shape. Of these, a plate-like type is preferable in that the porosity is lowered so that electricity can flow efficiently and the resistance can be lowered. In another aspect of the present invention, in the case of using powders having two different average particle sizes, it is preferable that the first powder has a spherical shape on the side having the void filled with the second powder.

The silver powder is preferably included in an amount of 60 to 90% by weight based on 100% by weight of the total amount of the silver paste composition. When the content is less than 60% by weight, the silver paste layer printed after firing becomes thin, the back wiring resistance may increase, and the soldering characteristics may be deteriorated. When the content exceeds 90% by weight, the printing thickness becomes too thick, which may lead to warping of the silicon wafer substrate.

<Glass Frit >

The glass frit is a component that imparts adhesion between the silver wiring layer and the silicon wafer substrate. In the present invention, PbO-Bi ₂ O ₃ -SiO ₂ -Al ₂ O ₃ -ZnO / MgO glass frit is used. Preferably, the glass frit according to the invention comprises 50 to 80% by weight of PbO, 5 to 15% by weight of B ₂ O ₃ , 0.1 to 10% by weight of SiO ₂ , ₂ to 10% by weight of Al ₂ O ₃ , At least one kind and 5 to 20% by weight.

The glass frit of the present invention is a PbO-based glass frit which is easy to control the melting point, has a low thermal expansion coefficient, and is excellent in soldering characteristics with a ribbon when a solar cell module is manufactured. In particular, the glass frit of the present invention contains 5 to 20% by weight of at least one of ZnO and MgO, thereby preventing the glass frit from passing through the emitter layer during over-firing. Accordingly, it is possible to perform a more stable process at the time of manufacturing the solar cell. In addition, the efficiency of the solar cell can be improved by stably forming the electrode to be formed.

The glass frit preferably has a softening point of 300 to 600 ° C. When the temperature is higher than 600 ° C, the glass frit is melted to provide adhesion between the silver wiring layer and the silicon wafer layer. However, the glass frit may not be melted sufficiently during the firing process, resulting in a problem of poor adhesion. When the softening point is less than 300 ° C, melting starts at a too low temperature, and the silver electrode penetrates the emitter layer of the silicon wafer, resulting in an increase in leakage current, resulting in a reduction in efficiency.

The glass frit is preferably contained in an amount of 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, and most preferably 1 to 5% by weight, based on 100% by weight of the total amount of the silver paste composition. If the content is less than 0.1 wt%, adhesion between the wiring layer and the silicon wafer substrate may be lowered after the firing process, and if the content exceeds 10 wt%, the resistance may increase and the efficiency of the solar cell device may be lowered.

<Organic Vehicle >

The organic vehicle is a component for imparting viscosity and rheological properties suitable for printing on the silver paste composition, and may be a solution in which a polymer resin and various additives are dissolved in an organic solvent.

The organic vehicle may be a mixture of 75 to 99% by weight of an organic solvent and 1 to 25% by weight of a polymer resin, and 1 to 10% by weight of an additive may be further mixed therewith.

As the organic solvent, a known solvent may be used, and a solvent having a boiling point of 150 to 300 DEG C may be used so as to prevent drying of the paste composition in the printing process and to control fluidity. Specific examples thereof include tripropylene glycol methyl ether, tripropylene glycol n-butyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, propylene glycol phenyl ether, diethylene glycol ethyl ether, diethylene glycol n- Ether, diethylene glycol hexyl ether, ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether, ethylene glycol, terpineol, butyl carbitol, Carbitol acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (texanol), etc. These may be used alone or in admixture of two or more.

The organic solvent is preferably contained in an amount of 75 to 99% by weight based on 100% by weight of the total amount of the organic vehicle. In this content range, an optimum fluidity can be imparted to the paste composition.

As the polymer resin, those well known in the art can be used, and examples thereof include ethylcellulose, nitrocellulose, hydroxypropylcellulose, phenol, acrylic, rosin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyvinylbutyral, Butadiene-styrene (ABS), poly (methyl methacrylate), polyvinyl chloride, polyvinyl chloride, polyvinyl chloride, polyvinyl chloride, polyvinyl chloride, polyvinylidene chloride, , Polyvinylidene chloride, polyvinyl acetalte, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene oxide, polysulfone, polyimide, polyether sulfone, polyarylate, polyether ether Ketone, and silicone. These may be used alone or in combination of two or more.

The polymer resin is preferably contained in an amount of 1 to 25% by weight, preferably 5 to 25% by weight, based on 100% by weight of the total amount of the organic vehicle. If the content is less than 1% by weight, the printing property and dispersion stability of the paste composition may be deteriorated, and if more than 25% by weight, the paste composition may not be printed.

The organic vehicle may further comprise a dispersant as an additive with the above components.

As the dispersing agent, known surfactants can be used. Examples thereof include polyoxyethylene alkyl ethers having 6 to 30 carbon atoms in the alkyl group, polyoxyethylene alkylaryl ethers having 6 to 30 carbon atoms in the alkyl group, Ether type such as polyoxyethylene-polyoxypropylene alkyl ether; Ester ethers such as glycerin ester addition type polyoxyethylene ether, sorbitan ester addition type polyoxyethylene ether and sorbitol ester addition type polyoxyethylene ether; Esters such as polyethylene glycol fatty acid esters, glycerin esters, sorbitan esters, propylene glycol esters, sugar esters and alkylpolyglucosides; Nitrogen-containing systems such as fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine having 6 to 30 carbon atoms in the alkyl group, and amine oxide; And polymeric compounds such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylic acid-maleic acid copolymer, and poly 12-hydroxystearic acid. Also, commercially available products such as hypermer KD (Uniqema), AKM 0531 (Nippon Kayaku Co., Ltd.), KP (Shinetsugaku Kagaku Co., Ltd.), POLYFLOW (Kyoeisha Chemical Co., Ltd.) Asahi guard (Asahi Glass Co.), Surflon (Asahi Glass Co., Ltd.), SOLSPERSE (Geneka Co., Ltd.), EFKA (EFKA Chemical Co., Ltd.) ), PB 821 (Ajinomoto Co., Ltd.), BYK-184, BYK-185, BYK-2160 and Anti-Terra U (manufactured by BYK). These may be used alone or in combination of two or more.

The dispersing agent is preferably contained in an amount of 1 to 10% by weight, preferably 1 to 5% by weight based on 100% by weight of the total amount of the organic vehicle.

The organic vehicle may further contain additives such as a thixotropic agent, a wetting agent, an antioxidant, a corrosion inhibitor, a defoaming agent, a thickener, a dispersant, a tackifier, a coupling agent, an antistatic agent, a polymerization inhibitor and an anti-

The organic vehicle is preferably contained in an amount of 5 to 30% by weight based on 100% by weight of the total amount of the silver paste composition. When the content is less than 5% by weight, the viscosity of the paste composition becomes too high to lower the fluidity and printability. When the content exceeds 30% by weight, the content of the powder is relatively small, .

The silver paste composition containing the above-mentioned components not only prevents the penetration of the emitter layer by the organic frit during over-baking but also has an excellent contact property with the emitter layer, thereby improving the efficiency in manufacturing the solar cell.

The present invention also provides an electrode formed from the silver paste composition.

The electrode is formed through a process of printing and drying and baking the silver paste composition on a substrate, such as a silicon wafer substrate. The printing method is not particularly limited, and for example, screen printing, gravure printing, offset printing, and the like can be used. Drying is performed at 60 to 300 ° C for several seconds to several minutes, and firing can be performed at 600 to 950 ° C for several seconds to several tens of seconds.

The electrode thus formed can be applied as a front electrode and / or a rear electrode of a solar cell element, thereby lowering the resistance and increasing the efficiency of the solar cell and preventing the penetration of the emitter layer of the glass frit in the under- can do.

The present invention provides a solar cell element provided with an electrode formed from the silver paste composition. Hereinafter, an embodiment of a method of manufacturing a solar cell according to the present invention will be described.

According to the method for manufacturing a solar cell of the present invention, the irregularities are formed on one surface of the substrate by the texture etching method of the crystalline silicon wafer substrate.

The substrate may be a monocrystalline or polycrystalline silicon wafer substrate and may be doped with Group 3 element B, Ga, In or the like as a p-type impurity, or may be doped with a Group 5 element P, As, Sb or the like as an n-type impurity .

When the substrate is immersed in the etching liquid composition or when the etching liquid composition is sprayed onto the substrate, etching proceeds to form irregularities on the surface of the substrate.

If the surface of the substrate is roughened by the unevenness formation, the reflectance of the incident light decreases, and the optical trapping amount increases, thereby reducing the optical loss.

The width (width) of the irregularities is not particularly limited, and may be, for example, 1 to 20 탆 in size. The height of the concavities and convexities is not particularly limited, and may be, for example, 1 to 15 占 퐉. When the height of the concave and convex corresponds to the above range, it can be applied to a substrate having a thickness of 180 탆 or less. An emitter layer, which can be formed on the concave and convex portions, is then formed with a uniform doping profile, Uniformity of the pn junction at the interface between the antireflection film and the antireflection film can be improved and then the front electrode forming paste can be filled up to the concave portion formed according to the shape of the concave and convex portion to be coated, The resistance of the front electrode can be reduced.

The shape of the concavities and convexities is not particularly limited, and examples thereof include a pyramidal shape, a square shape, and a triangular shape.

After the formation of the unevenness, a step of forming an emitter layer on the unevenness; Forming an antireflection film on the emitter layer; Forming a front electrode through the antireflection film to connect to the emitter layer; And forming a rear electrode on the rear surface of the substrate.

The emitter layer may be formed on the substrate with the opposite conductivity type to the substrate. For example, if the substrate is doped with a p-type impurity, the emitter layer may be doped with a Group 5 element P, As, Sb or the like as an n-type impurity. If the substrate is doped with an n-type impurity, . When the substrate and the emitter layer are doped with an impurity of the opposite conduction type, a pn junction is formed at the interface between the substrate and the emitter layer. When light is irradiated to the pn junction, photovoltaic power can be generated due to the photoelectric effect .

The emitter layer may be formed by a method such as a diffusion method, a spray method, an injection method, a printing method, or the like. In one example, the emitter layer can be formed by implanting an n-type impurity into the p-type semiconductor substrate.

Thereafter, an antireflection film is formed on the emitter layer.

Antireflection coatings passivate defects present in the surface or bulk of the emitter layer and reduce the reflectivity of sunlight incident on the front side of the substrate. When defects present in the emitter layer are passivated, the recombination sites of the minority carriers are removed to increase the open-circuit voltage (Voc) of the solar cell. When the reflectance of the sunlight decreases, the amount of light reaching the pn junction increases, Isc) is increased, so that the conversion efficiency of the solar cell is improved.

The antireflection film may be formed of any one single film selected from the group consisting of a silicon nitride film, a silicon nitride film including hydrogen, a silicon oxide film, a silicon oxynitride film, MgF ₂ , ZnS, TiO ₂ and CeO ₂ , or a combination of two or more films It may have a multilayer structure.

The antireflection film may be formed by vacuum deposition, chemical vapor deposition, spin coating, screen printing or spray coating, but is not limited thereto.

Thereafter, a front electrode is formed on the antireflection film.

The front electrode is in contact with the emitter layer through the antireflection film, and is used as a carrier pathway of the carrier generated by the photoelectric effect.

The front electrode can be formed by applying a paste composition for forming the front electrode onto the antireflection film in the form of a bar. The above silver paste composition can use the silver paste composition of the present invention.

As the paste composition for forming the front electrode, the above-described silver paste composition of the present invention can be used.

The coating method is not particularly limited and includes, for example, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, an immersion coating method, A flexographic printing method, an offset printing method, an inkjet printing method, a nozzle printing method, and the like.

After the application, a conventional heat treatment process may be performed. The silver powder becomes a liquid phase at a high temperature by the heat treatment, and is again recrystallized into a solid phase, and the front electrode is connected to the emitter layer by a fire through phenomenon penetrating the antireflection film through the glass frit.

Next, a rear electrode is formed on the rear surface of the substrate.

The backside electrode acts as another carrier's path of travel caused by the photoelectric effect. On the other hand, a back surface field layer may be formed on the interface between the rear electrode and the substrate. The backside layer can prevent the carrier from moving to the backside of the substrate and recombining. If the recombination of the carriers is prevented, the open voltage can be increased and the efficiency of the solar cell can be improved.

The rear electrode can be formed by applying a paste composition for forming the rear electrode on the rear surface of the substrate. The back electrode may have a structure in which a silver electrode and an aluminum electrode are formed. In this case, the electrode may be manufactured using the silver paste composition of the present invention.

The coating method is not particularly limited and includes, for example, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, an immersion coating method, A flexographic printing method, an offset printing method, an inkjet printing method, a nozzle printing method, and the like.

After the application, a conventional heat treatment process may be performed. By the heat treatment, aluminum contained in the paste composition applying portion for forming the rear electrode is diffused through the rear surface of the substrate, thereby forming a rear whole layer at the interface between the rear electrode and the substrate. The backside layer minimizes the rear recombination of the electrons generated by the sunlight, thereby contributing to the improvement of the efficiency of the solar cell.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example

Manufacturing example  1 to 6: glass Frit  I- VI Manufacturing

Glass frit was prepared with the components and contents shown in Table 1 below.

division designation Component (% by weight) PbO Al ₂ O ₃ B ₂ O ₃ SiO ₂ ZnO MgO CaO Li ₂ O P ₂ O ₅ Production Example 1 I 74.95 4.72 8.15 1.15 11.03 - - - - Production Example 2 II 72.0 2.56 8.95 5.12 - 9.64 1.73 - - Production Example 3 III 72.0 2.56 8.95 5.12 9.64 - - 1.73 - Production Example 4 IV 80.22 3.68 1.15 8.77 4.78 - - - 1.4 Production Example 5 V 60.43 1.50 9.04 29.03 - - - - - Manufacturing 6 VI 60.43 1.50 9.04 7.02 - 22.01 - - -

Example  One

75 wt% of spherical silver powder having D ₅₀ = 0.5 to 5 um and 10 wt% of silver powder having D ₅₀ = 10 to 500 nm (total amount of silver powder = 85 wt%) were added and the composition of frit I of 4.5 wt% And 10.5% by weight of an organic vehicle solution in which ethyl cellulose was dissolved by dissolving in glycol ether were sequentially added, followed by stirring at 1,000 rpm for 3 minutes using a mixer that performs both rotation and revolutions simultaneously to prepare a silver paste composition.

Example 2

A silver paste was prepared in the same manner as in Example 1, except that the glass frit was changed to the frit II in Table 1.

Example 3

A silver paste was prepared in the same manner as in Example 1, except that the glass frit was changed to the frit III in Table 1 above.

Comparative Example 1

A silver paste was prepared in the same manner as in Example 1, except that the glass frit was changed to the frit IV in Table 1 above.

Comparative Example 2

A silver paste was prepared in the same manner as in Example 1, except that the glass frit was replaced with the frit V shown in Table 1. [

Comparative Example 3

A silver paste was prepared in the same manner as in Example 1, except that the glass frit was changed to the frit VI in Table 1.

Test Example

156X156mm, a 200μm thick n-type by performing a surface texturing process, the single crystal wafer to form a vapor-deposited to the front CVD using _{BBr 3 Boron Emitter (p + Emitter} ) after the height of the pyramid is formed to be about 2-6μm rear POCl ₃ was similarly deposited by CVD to form an n + layer. The SiNx layer was formed on the p + layer and the n + layer by PECVD to form an antireflection film. The front surface of the front surface of the wafer, on which the n + layer was formed, was printed with silver paste compositions prepared by the above Examples and Comparative Examples at the electrode positions. At this time, the print mask was printed with a size of 290-20mesh / finger = 90um. In addition, the rear electrode was formed by using AMP-NBS5001, a silver paste for Dongwoo Fine-Chem n + emitter.

The printed wafers were dried using NIR Dryer and then fired in an infrared continuous firing furnace at a temperature of 720 - 900 ° C to produce solar cells.

The firing process is performed while passing the silicon wafer through a belt furnace. The belt furnace includes a burn-out period of about 600 ° C. and a firing period of about 800 to 950 ° C., After organic matter in the paste was burned off, the front and rear electrodes were melted to form an electrode.

The cell efficiency was measured using a DENKEN solar simulator.

division Frit efficiency Fill Factor Isc Voc Rs Example 1 I 19.586 78.986 9.2360 0.6417 0.00278 Example 2 II 19.749 79.286 9.2528 0.6432 0.00271 Example 3 III 19.796 79.568 9.2489 0.6428 0.00276 Comparative Example 1 IV 18.237 77.235 9.0534 0.6241 0.00365 Comparative Example 2 V 19.018 77.856 9.1432 0.6384 0.00323 Comparative Example 3 VI 18.856 77.583 9.0786 0.6397 0.00346

As shown in Table 2, the contact properties between the electrodes formed using the silver paste compositions of Examples 1 to 3 including the glass frit according to the present invention and the emitter layer of the solar cell device were improved, .

10: P-type silicon wafer substrate 20: N-type diffusion layer
30: Silicon nitride film 40:
51: P + layer (rear surface electric field) 52: N + layer
61: rear electrode 62: rear aluminum electrode

Claims (7)

Silver powder;
50 to 80 wt% of PbO, 5 to 15 wt% of B ₂ O ₃ , 0.1 to 10 wt% of SiO ₂ , ₂ to 10 wt% of Al ₂ O ₃ , and 5 to 20 wt% of at least one of ZnO and MgO Glass frit; And
Organic vehicle;
&Lt; / RTI &gt;
The silver paste composition according to claim 1, wherein the glass frit further comprises 0.1 to 10% by weight of at least one member selected from the group consisting of CaO, SrO, and BaO.
The silver paste composition according to claim 1, wherein the glass frit further comprises 0.1 to 20% by weight of at least one selected from the group consisting of Na ₂ O, K ₂ O and Li ₂ O.
The silver paste composition of claim 1, wherein the silver powder comprises a second silver powder having an average particle size that can be filled between the first silver powder and the first silver powder.
The silver paste composition according to claim 1, wherein the organic vehicle is a mixture of 1 to 25% by weight of a polymer resin and 75 to 99% by weight of an organic solvent.
An electrode formed from the paste composition of any one of claims 1 to 5.
A solar cell element comprising the electrode of claim 6.

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