KR20160007994A - Electro-conductive carbon-ball, composition for forming solar cell comprising the same and method for preparing the same - Google Patents

Abstract

The present invention relates to a conductive carbon ball, a composition comprising the same for forming an electrode of a solar cell and a manufacturing method thereof. The conductive carbon ball is a composite of a carbon ball derived from carbohydrate and a silver (Ag) atom, wherein the carbon ball includes 10 to 1,000 ppm of a nickel or a zinc atom and 5 to 95 wt% of the silver atom is included. The conductive carbon ball has excellent particle size uniformity. According to the manufacturing method thereof, the particle size of the carbon ball can be controlled and the yield of the composite carbon ball can be maximized. The solar cell prepared with the composition comprising the conductive carbon ball for forming an electrode of a solar cell has excellent conversion efficiency and minimizes production costs, thereby providing excellent economic efficiency.

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive carbon ball, a composition for forming a solar cell electrode comprising the conductive carbon ball, and a method of manufacturing the same. BACKGROUND ART [0002] Electroconductive carbon-

The present invention relates to a conductive carbon ball, a composition for forming a solar cell electrode comprising the conductive carbon ball, and a method of manufacturing the same.

Solar cells generate electrical energy by using the photoelectric effect of pn junction that converts photon of sunlight into electricity. The solar cell is formed with a front electrode and a rear electrode on a semiconductor wafer or a substrate on which a pn junction is formed. The photovoltaic effect of the pn junction is induced in the solar cell by the sunlight incident on the semiconductor wafer, and the electrons generated from the pn junction provide a current flowing to the outside through the electrode. The electrode of such a solar cell can be formed on the surface of the wafer by applying, patterning and firing the composition for electrode formation.

Electrodes used in solar cells have a great influence on the conversion efficiency of solar cells and require a high level of electrical conductivity. Especially silver powder used for the front electrode is relatively expensive, and therefore much efforts have been made to develop a material to replace the silver powder. As an alternative, silver-coated copper has been proposed, but there is a problem in that the copper is oxidized at high-temperature firing or the denseness or adhesion of the formed plating film is poor.

U.S. Patent Publication No. 2013-0140501 discloses a technique of coating silver on an acrylic resin or a styrenic resin, but the manufacturing process is relatively complicated because a tin layer must be formed by plating before plating silver.

The present inventors have accomplished the present invention in order to ensure the electrical conductivity of the silver powder level, to facilitate the manufacturing process, and to minimize the manufacturing cost.

A problem to be solved by the present invention is to provide a conductive carbon ball having excellent particle size uniformity.

Another object of the present invention is to provide a method for manufacturing a conductive carbon ball which can control the particle size of the carbon ball and maximize the synthesis yield of the carbon ball.

Another object of the present invention is to provide a composition for forming a solar cell electrode having excellent conversion efficiency including the conductive carbon ball.

Another object of the present invention is to provide a composition for forming a solar cell electrode which is economical and minimizes the manufacturing cost.

One aspect of the present invention is a composite of a carbon ball and a silver (Ag) element derived from a carbohydrate, wherein the carbon ball contains 10 to 1,000 ppm of nickel or zinc element, 5 to 95 wt% of the silver (Ag) The present invention relates to a conductive carbon ball.

Another aspect of the present invention relates to a method for producing a carbon ball by hydrothermal synthesis of a carbohydrate in the presence of a metal salt catalyst; And preparing a conductive carbon ball by electroless plating the carbon ball, wherein the metal salt catalyst is a nickel salt or a zinc salt.

A further aspect of the present invention relates to a composition for forming a solar cell electrode comprising a conductive filler, a glass frit and an organic vehicle, wherein the conductive filler comprises the conductive carbon ball.

Another aspect of the present invention relates to a solar cell electrode made of the composition for forming a solar cell electrode.

The conductive carbon ball of the present invention is excellent in particle size uniformity and its manufacturing method can control the particle size of the carbon ball and maximize the synthesis yield of the carbon ball, A solar cell made of a composition for forming a solar cell has excellent conversion efficiency and minimizes a manufacturing cost and is excellent in economy.

1 is a conceptual view schematically showing a structure of a solar cell according to an embodiment of the present invention.
2 is a scanning electron microscope (SEM) photograph of a carbon ball according to Example 1 of the present invention.
3 is a scanning electron microscope (SEM) photograph of a carbon ball according to Comparative Example 1 of the present invention.

Conductive carbon balls and method for manufacturing the same

The electro-conductive carbon-ball according to one embodiment of the present invention includes steps (S10) of producing carbon balls by hydrothermal synthesis of carbohydrates (S10) and electroless plating of the carbon balls to produce conductive carbon balls Step S20. ≪ / RTI > In the present invention, the conductive carbon ball means a composite of a carbon ball and a silver (Ag) component. The silver (Ag) component may be continuously or discontinuously coated on the outside of the carbon balls, or may be contained in the inside of the carbon balls.

The manufacturing step (S10) of the carbon ball comprises dispersing the carbohydrate in a solvent; Hydrothermal synthesis in the presence of a metal salt catalyst; Washing step; And a drying step.

The solvent may be deionized water, ethanol, etc. The carbohydrate powder may be a monosaccharide such as glucose, fructose, or a disaccharide such as sucrose, but is not limited thereto. The carbohydrate may be in powder form having an average particle diameter (D50) of 0.2 to 30 mu m.

The metal salt catalyst may be a nickel salt or a zinc salt. The nickel salt may be nickel sulfate, nickel chloride, or nickel nitrate. The zinc salt may be zinc chloride or zinc nitrate. The metal salt catalyst may be used in the form of an anhydride or a hydrate. When the nickel salt or the zinc salt is used, it is easy to control the size of the carbon ball to be synthesized, the uniformity of the carbon ball particle size distribution is excellent, the tap density is increased, and a high content of carbon balls is mixed into the solar battery paste .

The prepared carbon balls may have an average particle diameter (D50) of 0.2 to 30 mu m, and may be spherical, plate-like, or amorphous. The carbon ball may have a tap density of 0.05 to 0.5 g / cm < ³ >.

The prepared carbon balls may satisfy the following formulas (1) and (2) as the average particle diameters D10, D50 and D90. When the following formulas 1 and 2 are satisfied, an excellent particle size distribution can be exhibited.

[Formula 1]

(D90-D10) / D50? 2

[Formula 2]

D90 / D10? 5

In addition, the carbon balls may include nickel (Ni) or zinc (Zn) components. Specifically, when the carbon balls are measured by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer), 10 to 1,000 ppm of nickel or zinc elements can be detected.

The conductive carbon ball according to one embodiment of the present invention can be produced by electroless plating silver (Ag) on the synthesized carbon balls. Specifically, the step S20 of electroless-plating the carbon balls to form the conductive carbon balls includes: dispersing the synthesized carbon balls in the plating solution; Electroless plating; Washing step; And a heat treatment step.

The plating solution may be a silver salt solution containing a silver (Ag) component as a metal source. The silver salt may be, but not necessarily limited to, silver nitrate (AgNO ₃ ). The plating liquid silver salt may be contained in an amount of 5 to 100 g / L.

The plating solution may contain any one of ammonia water, ethylenediamine and ethylenediaminetetraacetic acid (EDTA) as a complexing agent.

The complexing agent controls the plating rate and prevents the plating from spontaneously decomposing, thereby providing an environment with excellent solution stability. In particular, ammonia water which is stable in alkalinity and exhibits good stability to silver (Ag) It is preferable to use it as a basic complexing agent, and as an additional complexing agent, any one of ethylenediamine and ethylenediaminetetraacetic acid may be further used. In order to maintain the performance as a complexing agent in the plating solution, the concentration of ammonia water is preferably 50 to 400 ml / l, and the concentration of ethylenediamine and ethylenediaminetetraacetic acid is preferably 1.0 to 10 g / l.

The pH of the plating solution may be in the range of 9 to 12. In the above-mentioned pH range, plating can be performed effectively with high plating speed. For the pH control, the electroless plating solution may further contain sodium citrate, sodium hydroxide, or the like as a pH buffer.

The plating process is preferably performed at a temperature ranging from 20 to 60 캜. In this range, a dense and fine plating layer can be formed.

Further, after the electroless plating step, it may further include a step of heat-treating at 40 to 80 ° C for 20 minutes to 1 hour through a washing step. The resistivity of the plated film can be further reduced by heat treatment during the heat treatment step.

The conductive carbon balls may contain 5 to 95% by weight, preferably 30 to 80% by weight, of the silver (Ag) component based on the total weight of the conductive carbon balls. When the silver (Ag) component is included in the above range, excellent conversion efficiency can be secured.

The average particle diameter (D50) of the conductive carbon balls may be 0.2 to 30 mu m.

The specific gravity of the conductive carbon balls may be 0.5 to 2 g / cm < ³ >. In the specific gravity range, excellent printability and fine line width of the electrode can be realized.

Composition for forming solar cell electrode

A composition for forming a solar cell electrode, which is another aspect of the present invention, may include a conductive filler (A), a glass frit (B), and an organic vehicle (C).

(A) a conductive filler

The composition for forming a solar cell electrode of the present invention includes a conductive filler, and the conductive filler may include the conductive carbon ball described above.

The conductive filler may include at least one selected from the group consisting of Au, Ag, Cu, Al, Pd, Pt, Cr, Co, (Sn), lead (Pb), zinc (Zn), iron (Fe), iridium (Ir), osmium (Os), rhodium (Rh), tungsten (W), molybdenum (Mo) And ITO (indium tin oxide). The conductive metal powder may be at least one selected from the group consisting of indium tin oxide (ITO), and the like. The conductive filler may preferably include silver (Ag) powder as a conductive metal powder.

The conductive metal powder may be a nano-sized or micro-sized powder, for example, a powder having a size of several tens to several hundreds of nanometers, a powder of several to several tens of micrometers, May be mixed with the metal powder.

The conductive metal powder may have a spherical shape, a plate shape, or an amorphous shape.

The average particle diameter (D50) of the conductive metal powder may be 0.1 占 퐉 to 10 占 퐉, and more preferably 0.5 占 퐉 to 5 占 퐉. The average particle diameter was measured using a 1064 LD model manufactured by CILAS after distributing the conductive powder to isopropyl alcohol (IPA) by ultrasonication at 25 캜 for 3 minutes. Within this range, the contact resistance and line resistance can be lowered.

When the conductive carbon ball and the conductive metal powder are used in combination as the conductive filler, the conductive carbon ball and the conductive metal powder may be contained in a weight ratio of 1:50 to 20: 1. When it is included in the above range, excellent conversion efficiency can be ensured and manufacturing cost can be remarkably reduced in comparison with the case where the conductive metal powder is used singly.

The conductive filler may be contained in an amount of 50 to 95% by weight based on the total weight of the composition. In the above range, it is possible to prevent the conversion efficiency from being lowered by increasing the resistance. Preferably 70 to 90% by weight.

(B) glass frit

The glass frit is formed by etching the antireflection film during the firing process of the electrode paste, melting the silver particles to produce silver grains in the emitter region so that the resistance can be lowered, and the adhesion between the conductive powder and the wafer And softening at sintering to lower the firing temperature.

Increasing the area of the solar cell in order to increase the efficiency of the solar cell may increase the contact resistance of the solar cell. Therefore, the damage to the pn junction should be minimized and the series resistance should be minimized. In addition, it is preferable to use a glass frit which can sufficiently secure thermal stability even at a wide firing temperature because the range of variation in firing temperature becomes large as wafers of various sheet resistances increase.

The glass frit may be typically at least one of a flexible glass frit or a lead-free glass frit used in a composition for forming a solar cell electrode.

The glass frit may be one derived from at least one metal oxide selected from lead oxide, silicon oxide, tellurium oxide, bismuth oxide, zinc oxide, boron oxide, aluminum oxide, tungsten oxide and the like.

For example, zinc oxide-silicon oxide (ZnO-SiO2), zinc oxide-boron oxide-silicon oxide (ZnO-B2O3-SiO2), zinc oxide-boron oxide- SiO2-Al2O3), bismuth oxide-silicon oxide system (Bi2O3-SiO2), bismuth oxide-boron oxide-silicon oxide system (Bi2O3-B2O3-SiO2), bismuth oxide-boron oxide- (Bi2O3-ZnO-B2O3-SiO2), or bismuth oxide-zinc oxide-boron oxide-silicon oxide-aluminum oxide system (Bi2O3-ZnO-B2O3 -SiO2-Al2O3) glass frit and the like can be used.

The glass frit can be prepared from the metal oxides described above using conventional methods. For example, in the composition of the metal oxide described above. The blend can be mixed using a ball mill or a planetary mill. The mixed composition is melted at a temperature of 900 ° C to 1300 ° C and quenched at 25 ° C. The resulting product is pulverized by a disk mill, a planetary mill or the like to obtain a glass frit.

The shape of the glass frit may be spherical or irregular.

The glass frit may have an average particle diameter (D50) of 0.1 to 5 mu m.

The glass frit may be made of, for example, silicon dioxide (SiO2), aluminum oxide (Al2O3), boron oxide (B2O3), bismuth oxide (Bi2O3), sodium oxide (Na2O) , Zinc oxide (ZnO), and the like.

The glass frit may be contained in an amount of 1 to 15% by weight, and preferably 2 to 10% by weight based on the total weight of the composition. And may have appropriate dispersibility, fluidity and printability in the above range.

(C) Organic vehicle

The organic vehicle imparts suitable viscosity and rheological properties to the composition through mechanical mixing with inorganic components of the composition for forming solar cell electrodes.

The organic vehicle may be an organic vehicle ordinarily used in a composition for forming a solar cell electrode, and may include a common binder resin, a solvent, and the like.

As the binder resin, an acrylate-based or cellulose-based resin can be used, and ethylcellulose is generally used. However, it is preferable to use a mixture of ethylhydroxyethylcellulose, nitrocellulose, a mixture of ethylcellulose and phenol resin, an alkyd resin, a phenol resin, an acrylic ester resin, a xylene resin, a polybutene resin, a polyester resin, Based resin, a rosin of wood, or a polymethacrylate of alcohol may be used.

Examples of the solvent include hexane, toluene, ethyl cellosolve, cyclohexanone, butyl cellosolve, butyl carbitol (diethylene glycol monobutyl ether), dibutyl carbitol (diethylene glycol dibutyl ether) , Butyl carbitol acetate (diethylene glycol monobutyl ether acetate), propylene glycol monomethyl ether, hexylene glycol, terpineol, methyl ethyl ketone, benzyl alcohol, gamma butyrolactone or ethyl lactate, Two or more of them may be used in combination.

The organic vehicle may be contained in an amount of 3 to 40% by weight based on the total weight of the composition for forming a solar cell electrode. Within this range, sufficient adhesive strength and excellent printability can be ensured.

(D) Other additives

The composition for forming a solar cell electrode of the present invention may further include conventional additives as needed in order to improve flow characteristics, process characteristics, and stability in addition to the above-described components. The additive may be used alone or as a mixture of two or more of a dispersing agent, a plasticizer, a viscosity stabilizer, a defoaming agent, a pigment, an ultraviolet stabilizer, an antioxidant and a coupling agent. These may be contained in an amount of 0.1 to 5% by weight based on the total weight of the composition for forming a solar cell electrode, but the content can be changed as necessary.

Solar cell electrode and solar cell comprising same

Another aspect of the present invention relates to an electrode formed from the composition for forming a solar cell electrode and a solar cell including the same. 1 shows a structure of a solar cell according to an embodiment of the present invention.

1, a composition for electrode formation is printed on a wafer 100 or a substrate including a p-layer (or n-layer) 101 and an n-layer (or p-layer) So that the rear electrode 210 and the front electrode 230 can be formed. For example, the electrode forming composition may be applied to the rear surface of the wafer by printing and then dried at a temperature of about 200 캜 to 400 캜 for about 10 to 60 seconds to perform a preliminary preparation step for the rear electrode. In addition, a preparation step for the front electrode can be performed by printing a composition for electrode formation on the entire surface of the wafer and then drying it. Thereafter, the front electrode and the rear electrode can be formed by performing a sintering process in which sintering is performed at 400 ° C to 950 ° C, preferably 750 ° C to 950 ° C, for about 30 seconds to 50 seconds.

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Production Example 1-4: Preparation of carbon balls

Production Example 1

10.8 g of a glucose powder and 14.3 mg of nickel chloride (II) hexahydrate as a metal salt catalyst are added to 120 ml of deionized water (D.I. water) and stirred for 20 minutes. The stirred solution was put into a 200 ml teflon-lined autoclave and hydrothermally synthesized at 200 ° C for 6 hours to prepare a carbon ball. The prepared carbon balls were washed three times with a 0.45 占 퐉 membrane filter, and then dried in an oven at 30 占 폚 for 8 hours to prepare carbon balls having an average particle diameter (D50) of 0.44 占 퐉. The physical properties of the synthesized carbon balls are shown in the following Table 1 after measurement based on the following evaluation method.

Production Example 2

Carbon balls were prepared in the same manner as in Preparation Example 1 except that 2.17 g of ZnCl2 was used instead of nickel chloride (II) hexahydrate as a metal salt catalyst, and the physical properties of the synthesized carbon balls were determined according to the following evaluation methods The results are shown in Table 1 below.

Production Example 3

Carbon balls were prepared in the same manner as in Production Example 1, except that the metal salt catalyst was not used. Physical properties of the synthesized carbon balls were measured according to the following evaluation methods, and are shown in Table 1 below.

Production Example 4

Carbon balls were prepared in the same manner as in Preparation Example 1 except that 1.08 g of SnCl 2 was used instead of nickel chloride (II) hexahydrate as a metal salt catalyst, and the physical properties of the synthesized carbon balls were evaluated according to the following evaluation methods The results are shown in Table 1 below.

Property evaluation method

Shape and Particle Size Analysis:

(1) A powdery carbon ball or a conductive carbon ball is fixed to an aluminum holder using a carbon tape.

(2) Platinum is coated for 200 seconds using a sputtering machine.

(3) Insert a holder equipped with a specimen into a SEM (Scanning Electron Microscopy, Hitach 4300S) and analyze the shape of the specimen.

* Fail: It means that spherical carbon balls and metal particles exist separately.

Metal content measurement:

(1) Weigh about 0.5 g of sample to 0.1 mg and transfer to 150 mL glass beaker.

(2) Place a beaker containing the sample on a hot plate, add 5 mL of concentrated sulfuric acid, and heat the sample at a high temperature of 200 ° C to 250 ° C for at least 15 minutes to carbonize the organic material.

(3) Remove the beaker from the hot plate and allow to cool.

(4) 1 mL of hydrogen peroxide is injected to oxidize the carbonized sample to decompose organic matter. Hydrogen peroxide is injected until the shape of the sample disappears.

(5) Add 10 mL of nitric acid (volume fraction 50% nitric acid solution), place on a hot plate, and heat for 30 minutes.

(6) After cooling, fill with 100 mL volumetric flask.

(7) The contents of nickel (Ni) and zinc (Zn) were measured through ICP-OES (OPTIMA 7300DV, Perkin-Elmer).

Tap density measurement:

(1) Weigh 20 g of the powder sample and put it in a measuring flask.

(2) Tighten a measuring flask containing a sample in a tap density measuring device (copley, JV2000) and perform tapping 1000 times.

(3) The tap density was calculated based on the following formula.

Tap density = [sample weight (20 g)] / [sample volume (cm ³ ) after tapping]

Uniformity of particle size distribution:

The SEM photograph of the synthesized carbon ball powder was visually observed to determine the uniformity of particle size. (Good: Good, Bad: Good)

Production Example 1 Production Example 2 Production Example 3 Production Example 4 sugars Glucose
(10.8 g) Glucose
(10.8 g) Glucose
(10.8 g) Glucose
(10.8 g) catalyst NiCl ₂ 5H ₂ O
(14.3 mg) ZnCl ₂
(2.17 g) - SnCl ₂
(1.08 g) Temperature (℃) 200 200 200 200 Hour (hour) 6 6 6 6 Powder particle size (D50, 占 퐉) 0.44 0.2 0.4 0.4 yield(%) 26 29 4 4 Metal content (ppm) 48 210 - - Tap density (g / cm ³ ) 0.22 0.24 0.16 0.16 shape rectangle rectangle rectangle Fail Particle size uniformity ○ ○ × ×

As shown in the results of Table 1, the carbon balls of Preparation Examples 1 and 2 hydrothermally synthesized in the presence of a nickel salt or a zinc salt had a higher tap density and a specific content of nickel and zinc, respectively, than the carbon balls of Production Examples 3 and 4 As shown in FIG. 2 and 3 are scanning electron microscope (SEM) photographs of carbon balls synthesized in Production Example 1 and Production Example 3, respectively, showing that the particle size uniformity of the carbon balls synthesized in Production Example 1 is higher than that of Production Example 3 Can be confirmed.

Examples 1-2 and Comparative Example 1: Production of conductive carbon balls

Example 1

(1) 9.35 g of silver nitrate (AgNO ₃ ) (Samseon Chemical) was added to 500 ml of distilled water, and 5 g of the carbon ball prepared in Preparation Example 1 was dispersed to prepare a dispersion.

(2) 17.646 g of sodium citrate (purified gold) was dissolved in 600 ml of distilled water, and ammonia water (NH ₃ .H ₂ O) (Samcheon Chemical) was added to prepare a solution at about pH 10.

(3) The dispersion prepared in (1) was stirred at 300-400 rpm at 70 ° C while the solution prepared in (3) was dropped for 2 hours to prepare a conductive carbon ball.

(4) The conductive carbon balls prepared in the above (3) were washed with distilled water in a 0.45 占 퐉 membrane filter, and then dried in an oven at 60 占 폚 for 12 hours to finally produce a conductive carbon ball.

Example 2

A conductive carbon ball was produced in the same manner as in Example 1 except that the carbon balls prepared in Preparation Example 2 were used.

Comparative Example 1

A conductive carbon ball was produced in the same manner as in Example 1 except that the carbon ball prepared in Preparation Example 3 was used.

The silver (Ag) content in the conductive carbon balls prepared in Examples 1-2 and Comparative Example 1 was measured using a TGA: Q5000 (TA Instrument) at a heating rate of 20 ° C / min from 30 ° C to 500 ° C in an air atmosphere The powder particle size and particle size uniformity were measured in the same manner as in the evaluation of the physical properties described above, and are shown in Table 2 below.

Example 1 Example 2 Comparative Example 1 Ag content (% by weight) 60 60 60 Powder particle size (D50, 占 퐉) 0.8 0.8 5 Uniformity of particle size Good Good Bad

As can be seen from the results shown in Table 2, the conductive carbon balls of Example 1-2 had better particle size uniformity than the carbon balls of Comparative Example 1.

Example 3: Preparation of a composition for forming a solar cell electrode

3.0 wt% of ethyl cellulose (STD4) as an organic binder was sufficiently dissolved in 6.5 wt% of butyl carbitol as a solvent at 60 캜, and spherical silver powder (Dowa High Tech CO. , 3.1 wt% of glass frit (CI-5008), 0.1 wt% of conductive carbon ball prepared from Example 1, 0.1 wt% of dispersant BYK-2 (BYK-chemie ) And 0.3% by weight of a thixotropic agent Thixatrol ST (Elementis co.) Were mixed and dispersed by a three roll kneader to prepare a composition for forming a solar cell electrode.

Manufacture of solar cell and evaluation of cell property (conversion efficiency, fill factor)

The composition for forming a solar cell electrode prepared in Example 3 was screen-printed on the entire surface of a crystal mono wafer in a predetermined pattern, and dried using an infrared ray drying furnace. The cell formed in the above process was fired at 700 to 950 ° C for 30 seconds to 210 seconds using a belt-type firing furnace. The solar cell efficiency measuring equipment (Pasan, CT-801) As a result, the Fill factor was 62.4% and the conversion efficiency was 14.5.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (13)

A composite of carbon balls and silver (Ag) elements derived from carbohydrates,
Wherein the carbon balls contain 10 to 1,000 ppm of nickel or zinc elements,
And a conductive carbon ball comprising 5 to 95% by weight of the silver (Ag) element.
The method according to claim 1,
And the average particle diameter (D50) is 0.2 to 30 占 퐉.
The method according to claim 1,
A conductive carbon ball having a specific gravity of 0.5 to 2 g / cm ³ .
Hydrolyzing the carbohydrate in the presence of a metal salt catalyst to produce a carbon ball; And
And preparing the conductive carbon balls by electroless plating the prepared carbon balls,
Wherein the metal salt catalyst is a nickel salt or a zinc salt.
5. The method of claim 4,
Wherein the step of preparing the carbon balls comprises: dispersing the carbohydrate in a solvent; Hydrothermal synthesis in the presence of a metal salt catalyst; Washing step; And a step of drying the conductive carbon balls.
5. The method of claim 4,
Wherein the carbohydrate is a monosaccharide or a disaccharide.
5. The method of claim 4,
The step of electroless plating the carbon balls to prepare the conductive carbon balls includes the steps of: dispersing the synthesized carbon balls in a plating solution; Electroless plating; Washing step; And a heat treatment step.
8. The method of claim 7,
Wherein the plating solution is a silver salt solution containing a silver (Ag) component as a metal source.
8. The method of claim 7,
Wherein the electroless plating is performed at a temperature of 20 to 60 DEG C and a pH of 9.0 to 12.
8. The method of claim 7,
Wherein the heat treatment step is performed at 40 to 80 DEG C for 20 minutes to 1 hour.
A composition for forming a solar cell electrode comprising a conductive filler, a glass frit, and an organic vehicle,
The composition for forming a solar cell electrode according to any one of claims 1 to 3, wherein the conductive filler comprises the conductive carbon ball.
12. The method of claim 11,
The conductive filler may be at least one selected from the group consisting of Au, Ag, Cu, Al, Pd, Pt, Cr, Co, (Pb), zinc (Zn), iron (Fe), iridium (Ir), osmium (Os), rhodium (Rh), tungsten (W), molybdenum (Mo), nickel (Ni) and indium tin oxide Wherein the composition further comprises at least one conductive metal powder selected from the group consisting of copper oxide, copper oxide, and copper oxide.
A solar cell electrode made of the composition for forming a solar cell electrode according to claim 11.

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