KR20190051396A - Electrode Paste For Solar Cell's Electrode And Solar Cell using the same - Google Patents

Abstract

The present invention relates to a conductive paste for a solar cell electrode. The present invention relates to a conductive paste for a solar cell electrode comprising metal powder, glass frit, and organic vehicles, wherein a surface of the glass frit is coated with an aliphatic amine compound. By coating the surface of the glass frit with the aliphatic amine compound to enhance the dispersion properties, electrical characteristics of the solar cell electrode formed using the glass frit can be enhanced to enhance the power generation efficiency of a solar cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste for a solar cell electrode,

The present invention relates to a conductive paste used for forming an electrode of a solar cell and a solar cell manufactured using the conductive paste.

A solar cell is a semiconductor device that converts solar energy into electrical energy. It has a p-n junction type and its basic structure is the same as a diode. FIG. 1 shows a structure of a general solar cell element. The solar cell element is generally constituted by using a p-type silicon semiconductor substrate 10 having a thickness of 180 to 250 .mu.m. On the light receiving surface side of the silicon semiconductor substrate, an n-type impurity layer 20 having a thickness of 0.3 to 0.6 占 퐉, an anti-reflection film 30 and a front electrode 100 are formed thereon. A back electrode 50 is formed on the back side of the p-type silicon semiconductor substrate.

The front electrode 100 is formed by applying a conductive paste containing silver as a main component, silver powder, glass frit, organic vehicle, and additives, on the antireflection film 30 The back electrode 50 is formed by applying an aluminum paste composition composed of aluminum powder, glass frit, organic vehicle and additives to the substrate by screen printing or the like and drying it. Then, the substrate is dried at a temperature of 660 캜 (melting point of aluminum) Followed by firing. Aluminum is diffused into the p-type silicon semiconductor substrate at the time of firing, so that an Al-Si alloy layer is formed between the back electrode and the p-type silicon semiconductor substrate, and the p + layer 40 Is formed. The existence of such a p + layer prevents the recombination of electrons and improves the collection efficiency of the generated carriers, thereby obtaining a BSF (Back Surface Field) effect. A rear silver electrode 60 may be further disposed under the rear aluminum electrode 50.

Glass frit, on the other hand, is essential for Ag / Si contact of silicon solar cells. Because of the high efficiency characteristics of the solar cell, it is inevitable to use a glass frit having excellent contact resistance Rc. In the conventional case, the etching of the antireflective film is controlled by controlling the component system, particle size, or content of the glass frit, but there are many problems in dispersion of the glass frit. In addition, when the image is observed after sintering, the thickness of the glass layer is not uniform and damage occurs in the n layer in the thick region, and the penetration of the silver powder in the thin region is reduced.

United States Patent No. 8,748,327 B1 (June 10, 2014) WO Patent Publication 2013/105812 A1 (Jul. U.S. Published patent application 2011-0094578 A1 (April 28, 2011)

The present invention relates to a method for improving the electric power generation efficiency of a solar cell by improving the electrical characteristics of the solar cell electrode formed by using the surface of the glass frit in the composition of the conductive paste for the solar cell electrode by coating the surface of the glass frit with an aliphatic amine compound, .

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

The present invention provides a conductive paste for a solar cell electrode, comprising a metal powder, a glass frit, and an organic vehicle, wherein the surface of the glass frit is coated with an aliphatic amine compound.

The aliphatic amine compound is characterized by containing an alkylamine-based material having 6 to 24 carbon atoms.

The alkylamine-based material may be at least one selected from the group consisting of triethylamine, heptylamine, octadecylamine, hexadecylamine, decylamine, octylamine, Didecylamine, or trioctylamine.

The coating layer formed by coating with the aliphatic amine compound has a thickness of 0.1 nm to 50 nm.

The glass frit is a first glass frit, and the conductive paste includes a second glass frit, wherein the surface of the second glass frit is not coated or is coated with a fatty acid.

Further, the fatty acid is characterized by containing lauric acid, oleic acid, stearic acid, palmitic acid or acetic acid.

The present invention also provides a solar cell having a front electrode on a substrate and a back electrode on the bottom of the substrate, wherein the front electrode is formed by applying the conductive paste for a solar cell electrode, followed by drying and firing And the like.

The conductive paste according to the present invention may include a glass frit coated with an aliphatic amine compound in order to improve dispersibility, so that it is possible to uniformly apply the glass frit during electrode formation. As a result, the reactivity at the time of firing becomes excellent, the damage of the n layer at the high temperature can be minimized, the adhesion can be improved, and the open voltage can be made excellent. In addition, the contact resistance between the electrode and the n-layer can be reduced by uniformly infiltrating the metal powder (for example, silver powder) during firing. As a result, the electrical characteristics of the solar cell electrode can be improved and the power generation efficiency of the solar cell can be improved.

1 is a schematic cross-sectional view of a general solar cell element.
Fig. 2 is an image for evaluating the dispersibility of the glass frit, in which the glass frit is placed in water and the state is observed immediately after stirring and after standing for 24 hours.
FIGS. 3A and 3B show the results of thermogravimetric analysis of surface-coated glass frit and non-coated glass frit prepared according to Preparation Examples 1 to 6. FIG.
Figures 4A and 4B show the results of DSC analysis of surface coated glass frit and uncoated glass frit prepared according to Preparation Examples 1 to 6.
Fig. 5 shows the results of measurement of adhesion between a solar cell electrode and a ribbon produced using the conductive paste prepared according to Examples 1 and 4 and Comparative Example 1. Fig.
6A to 6C are surface images of electrodes taken after the removal of the conductive ribbon.

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is defined solely by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise stated.

Throughout this specification and claims, the word "comprise", "comprises", "comprising" means including a stated article, step or group of articles, and steps, , Step, or group of objects, or a group of steps.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. Any feature that is specifically or advantageously indicated as being advantageous may be combined with any other feature or feature that is indicated as being preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

The paste according to one embodiment of the present invention is a paste suitable for use in forming a solar cell electrode, and provides a conductive paste including a glass frit coated with an aliphatic amine compound. More specifically, the conductive paste according to the present invention comprises metal powder, glass frit, organic vehicle and other additives.

As the metal powder, silver powder, copper powder, nickel powder, aluminum powder, etc. may be used. In the case of the front electrode, powder is mainly used, and in the case of the rear electrode, aluminum powder is mainly used. The metal powder may be used as a mixed powder in which one of the above-mentioned powders is used alone, an alloy of the above-described metals is used, or at least two of the powders described above are mixed.

The content of the metal powder is preferably 40 to 95% by weight based on the total weight of the conductive paste composition, taking into consideration the electrode thickness formed at the time of printing and the line resistance of the electrode. If it is less than 40% by weight, the resistivity of the formed electrode may be high. If it is more than 95% by weight, the content of other components is not sufficient and the metal powder is not uniformly dispersed. More preferably 70 to 90% by weight.

In the case where the conductive paste includes silver powder for forming the front electrode of the solar cell, the silver powder is preferably a pure silver powder. In addition, silver-coated composite powder having at least a silver layer on its surface, or an alloy containing silver as a main component an alloy or the like may be used. Further, other metal powders may be mixed and used. For example, aluminum, gold, palladium, copper, and nickel.

The average particle diameter (D50) of the metal powder may be 0.1 to 10 占 퐉, and it is preferably 0.5 to 5 占 퐉 in consideration of ease of paste formation and denseness in firing, and the shape of the metal powder may be spherical, acicular, It can be more than a species. The metal powder may be a mixture of powders of two or more kinds having different average particle diameter, particle size distribution and shape.

The glass frit may be coated with an aliphatic amine compound to improve dispersibility. Preferably, the aliphatic amine compound may comprise an alkylamine-based material having 6 to 24 carbon atoms. More preferably, the surface of the glass frit can be coated with an alkylamine-based material having 10 to 20 carbon atoms. For example, the alkylamine-based material may be selected from the group consisting of triethylamine, heptylamine, octadecylamine, hexadecylamine, decylamine, octylamine, Diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diisopropylamine,

The aliphatic amine compound is preferably coated on the surface of the glass frit to a thickness of 0.5 nm to 50 nm. The coating of the aliphatic amine compound can be carried out by adding a glass frit in an organic solvent or an aqueous solution in which the aliphatic amine compound is dissolved, stirring the mixture for a predetermined period of time, and then filtering the mixture. When the thickness of the coating layer formed by the coating process of the aliphatic amine compound is less than 0.5 nm, the effect of improving the dispersibility of the glass frit is reduced. When the thickness of the coating layer is larger than 50 nm, The electrical characteristics may be degraded. The thickness of the coating layer can be controlled through the content of the aliphatic amine compound used in the coating process.

The composition, particle diameter and shape of the glass frit are not particularly limited. It is possible to use not only flexible glass frit but also lead-free glass frit. Preferably, the content and content of the glass frit are 5 to 29 mol% of PbO, 20 to 34 mol% of TeO ₂ , 3 to 20 mol% of Bi ₂ O ₃ , 20 mol% or less of SiO ₂ , 10 mol% or less of B ₂ O ₃ , 10 to 20 mol% of an alkali metal (Li, Na, K, etc.) and an alkaline earth metal (Ca, Mg, etc.) It is possible to prevent an increase in the electrode line width due to the combination of the organic components of each of the above components, improve the contact resistance in the high-surface resistance, and improve the short-circuit current characteristics.

The average particle diameter of the glass frit is not limited, but it may have a particle diameter in the range of 0.5 to 10 mu m, and a mixture of various particles having different average particle diameters may be used. Preferably, at least one kind of glass frit has an average particle diameter (D50) of not less than 2 mu m and not more than 10 mu m.

The content of the glass frit is preferably 1 to 10% by weight based on the total weight of the conductive paste composition. If the content is less than 1% by weight, incomplete firing may occur to increase electrical resistivity. If the content is more than 10% by weight, There is a possibility that the electrical resistivity becomes too high due to too much component.

As described above, as the surface of the glass frit is coated with the aliphatic amine compound, the dispersibility is improved, and it is possible to uniformly coat the glass frit at the time of forming the electrode. As a result, the reactivity at the time of firing becomes excellent, the damage of the n layer at the high temperature can be minimized, the adhesion can be improved, and the open-circuit voltage (Voc) can be made excellent. In addition, the contact resistance between the electrode and the n-layer can be reduced by uniformly infiltrating the metal powder (for example, silver powder) during firing. The provision of such an effect can provide additional effects that make it easier to control the composition, particle size or shape of the glass frit.

In another embodiment of the present invention, the glass frit may comprise a first glass frit coated with an alkylamine-based material having from 6 to 24 carbon atoms, and a second glass frit coated with a fatty acid. Each of the first glass frit and the second glass frit may comprise the above-described flexible glass frit or lead-free glass frit. Also, the alkylamine-based material may be selected from the group consisting of triethylamine, heptylamine, octadecylamine, hexadecylamine, decylamine, octylamine, didecylamine ), Or trioctylamine, and the fatty acid may include lauric acid, oleic acid, stearic acid, palmitic acid or acetic acid. The first glass frit and the second glass frit coated with different kinds of materials as the glass frit are mixed and used so that the dispersibility of the glass frit in the conductive paste can be variously controlled.

As another embodiment of the present invention, the first glass frit may be a glass frit coated with the alkylamine-based material, and the second glass frit may be a glass frit that is not coated.

The organic vehicle is not limited, but organic binders, solvents, and the like may be included. Solvents may sometimes be omitted. The organic vehicle is not limited, but is preferably 1 to 30% by weight based on the total weight of the conductive paste composition.

The organic vehicle is required to have a property of keeping the metal powder and the glass frit uniformly mixed. For example, when the conductive paste is applied to the substrate by screen printing, the conductive paste becomes homogeneous, And a property to suppress the flow and to improve the discharging property and the plate separability of the conductive paste from the screen plate.

The organic binder contained in the organic vehicle is not limited, but examples of the cellulose ester compound include cellulose acetate and cellulose acetate butyrate. Examples of the cellulose ether compound include ethylcellulose, methylcellulose, hydroxypropylcellulose, hydroxyethylcellulose Examples of the acrylic compound include polyacrylamide, polymethacrylate, polymethylmethacrylate, and polyethylmethacrylate, and the like. Examples of the acrylic compound include polyacrylamide, polymethacrylate, polymethylmethacrylate, and polyethylmethacrylate And examples of vinyl based ones include polyvinyl butyral, polyvinyl acetate, polyvinyl alcohol, and the like. At least one or more organic binders may be selected and used.

Examples of the solvent used for diluting the composition include alpha-terpineol, texanol, dioctyl phthalate, dibutyl phthalate, cyclohexane, hexane, toluene, benzyl alcohol, dioxane, diethylene glycol, ethylene glycol monobutyl ether, ethylene Glycol monobutyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, and the like.

The conductive paste composition according to the present invention may further contain additives commonly known in the art, for example, dispersants, plasticizers, viscosity regulators, surfactants, oxidizing agents, metal oxides, metal organic compounds and the like.

The conductive paste composition for a solar cell electrode may be prepared by mixing and dispersing a metal powder, a coated glass frit, an organic vehicle, an additive, etc., followed by filtration and defoaming.

The present invention also provides a method of forming an electrode of a solar cell and a solar cell electrode produced by the method, wherein the conductive paste is applied on a substrate, followed by drying and firing. Printing, drying, and firing methods commonly used in the manufacture of solar cells can be used, except that the conductive paste containing glass-coated frit is used in the method of forming a solar cell electrode of the present invention Of course it is. As an example, the substrate may be a silicon wafer.

Since a unit solar cell including the above-described solar cell electrode has a small electromotive force, a plurality of unit solar cells are connected to constitute a photovoltaic module having an appropriate electromotive force. Each unit solar cell is connected by lead wires of constant length.

In addition, the conductive paste according to the present invention may be applied to a structure such as a crystalline solar cell (P-type, N-type), a passivated emitter solar cell (PESC), a passivated emitter and rear cell (PERC), a passivated emitter real locally diffused It can be applied to all printing processes such as double printing and dual printing.

Production Example 1

A glass frit of Pb-Te-Bi type was added to an organic solution of 0.3% concentration prepared by dissolving octadecylamine (ODA) in ethanol, followed by 24 hours of ball mill at 80 rpm at room temperature , And then dried in an oven at 50 DEG C for 1 hour to obtain a glass frit coated with octadecylamine.

Production Example 2

The procedure of Preparation Example 1 was repeated except that Duomeen TDO (Tallow alkyl) -1,3-propanediamine oleates was dissolved in ethanol to prepare an organic solution having a concentration of 0.3% To obtain a glass frit coated with TDO.

Production Example 3

In Preparation Example 1, a glass frit coated with stearic acid was obtained in the same manner as in Preparation Example 1, except that stearic acid was dissolved in ethanol to prepare an organic solution having a concentration of 0.3%.

Production Example 4

In Production Example 1, a glass frit coated with oleic acid was obtained in the same manner as in Preparation Example 1, except that oleic acid was dissolved in ethanol to prepare an organic solution having a concentration of 0.3%.

Production Example 5

A glass frit coated with octadecylamine was obtained in the same manner as in Preparation Example 1, except that octadecylamine was dissolved in ethanol to prepare an organic solution having a concentration of 0.1%.

Production Example 6

A glass frit coated with octadecylamine was obtained in the same manner as in Preparation Example 1, except that octadecylamine was dissolved in ethanol to prepare an organic solution having a concentration of 0.5%.

Examples and Comparative Examples

The coated glass frit, organic binder, solvent and dispersant were put into a composition (for example,% by weight) as shown in the following Table 1 and dispersed using a mixing mixer. Silver powder (spherical, average particle diameter 1 μm) And dispersed using a triple mill. Thereafter, vacuum degassing was conducted to prepare a conductive paste. In Examples 1 to 6, the glass frit obtained according to Production Examples 1 to 6 was used, and in Comparative Example 1, a glass frit of Pb-Te-Bi type without coating was used.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Silver Powder 88 88 88 88 88 88 88 bookbinder 0.4 0.4 0.4 0.4 0.4 0.4 0.4 menstruum
(texanol) 6 6 6 6 6 6 6 Dispersant 3.6 3.6 3.6 3.6 3.6 3.6 3.6 Glass frit





Production Example 1 2 Production Example 2 2 Production Example 3 2 Production Example 4 2 Production Example 5 2 Production Example 6 2 No coating 2

Experimental Example

(1) Evaluation of coating property of glass frit

The surface-coated glass frit and the non-coated glass frit prepared according to Preparation Examples 1 to 6 were put into water and stirred and left to compare the coating properties. The comparative evaluation of the coatability was carried out by observing the coatability visually by allowing the solution containing the glass frit to stand for 24 hours after the stirring. Fig. 2 is an image for evaluating the coating property of the glass frit, wherein the glass frit is placed in water and the state is observed immediately after stirring and after standing for 24 hours. Referring to FIG. 2, glass frites (Preparation Examples 1, 2, 5 and 6) coated with an aliphatic amine compound and glass frit coated with fatty acid (Preparation Examples 3 and 4) were confirmed to be well coated. At this time, glass frites coated with an aliphatic amine compound (Preparation Examples 1, 5 and 6) had improved dispersibility and became bulkier than those of the uncoated glass frit, while glass frites coated with fatty acid (Production Example 3 And 4) show a large amount of aggregation.

(2) Thermogravimetric analysis (TGA)

The thermogravimetric analyzes were carried out on the surface coated glass frit and uncoated glass frit prepared according to Preparation Examples 1 to 6 above. FIGS. 3A and 3B show the results of thermogravimetric analysis of surface-coated glass frit and non-coated glass frit prepared according to Preparation Examples 1 to 6. FIG. Referring to FIG. 3A, it can be seen that, in the case of coating with fatty acid, the evaporation time of the coating material is longer than that of coating with an aliphatic amine compound. Referring to FIG. 3B, it can be seen that the weight decrease of the aliphatic amine compound (i.e., octadecylamine) is increased according to the content, and it is found that the coating is uniformly coated.

(3) DSC analysis

DSC analysis was performed on surface coated glass frit and uncoated glass frit prepared according to Preparation Examples 1 to 6 above. Figures 4A and 4B show the results of DSC analysis of surface coated glass frit and uncoated glass frit prepared according to Preparation Examples 1 to 6. 4A and 4B, surface-coated glass frit prepared according to Preparation Examples 1 to 6 exhibited an exothermic reaction similar to that of the uncoated glass frit, but in the case of Production Example 6, .

(4) Conversion efficiency and resistance measurement

The conductive paste prepared according to Examples 1 to 6 and Comparative Example 1 was pattern printed on the entire surface of the wafer by a screen printing technique with a mesh size of 40 탆 and dried at 200 to 350 ° C for 20 seconds to 30 seconds Lt; / RTI > Then, Al paste was printed on the back side of the wafer and dried by the same method. The cells thus formed were fired at 500 to 900 ° C for 20 seconds to 30 seconds using a belt-type firing furnace to produce a solar cell.

The prepared cell was measured for short circuit current (Isc), open circuit voltage (Voc), conversion efficiency (Eff), curve factor (FF), serial resistance (CtisVV) using a solar cell efficiency measuring device Rs) and line resistance (Rline) were measured and are shown in Table 2 below.

division Isc
(A) Voc
(V) Eff
(%) FF
(%) Rs
(mΩ) Rline-1
(Ω) Rline-2
(Ω) Comparative Example 1 9.1223 0.6315 18.86 79.31 0.001229 24.30 24.57 Example 1 9.1215 0.6323 18.89 79.231 0.001160 24.53 24.53 Example 2 9.1161 0.6320 18.87 79.30 0.001162 24.73 24.85 Example 3 9.1310 0.6306 18.82 79.18 0.001210 24.80 24.20 Example 4 9.1148 0.6307 18.83 79.32 0.001241 23.84 24.69 Example 5 9.1464 0.6318 18.92 79.32 0.001176 24.00 23.82 Example 6 9.1184 0.6313 18.85 79.32 0.001213 24.52 24.56

As shown in Table 2 above, in the case of a solar cell comprising an electrode made of a conductive paste (for example, Examples 1, 2, and 5) comprising glass frit coated with a fatty acid amine compound, It can be seen that the open-circuit voltage is increased and the series resistance is reduced compared with the solar cell including the electrode made of the conductive paste containing the glass frit coated with fatty acid (Comparative Example 1 or Examples 3 and 4) It can be seen that the efficiency of the solar cell is improved due to the high efficiency.

Comparing the cases of Examples 1, 5 and 6, it can be seen that the conversion efficiency was greatly increased when the surface of the glass frit was coated with a small amount (Example 5). As a result, it can be confirmed that the dispersibility of the glass frit and the electrical characteristics of the solar cell electrode are changed depending on the content of the aliphatic amine compound (in other words, the thickness of the coating layer) used in the coating process.

(5) Evaluation of adhesion 1

The conductive paste prepared according to Examples 1 and 4 and Comparative Example 1 was used to manufacture solar cells in the same manner as described above, and conductive ribbons were formed on the electrodes of each of the cells through a tabbing process. . The ribbon used was 60Sn40Pb (manufactured by kosbon), and attachment was carried out at 350 ° C using an iron. Thereafter, the adhesion between the solar cell electrode and the ribbon was measured. The adhesive force measuring device was LS1 (Lloyd), and the adhesion was measured at a rate of 250 mm / min in the direction of 180 degrees. Fig. 5 shows the results of measurement of adhesion between a solar cell electrode and a ribbon produced using the conductive paste prepared according to Examples 1 and 4 and Comparative Example 1. Fig. 5, glass frit (Preparation Example 1) coated with a fatty acid amine compound (e.g., octadecylamine) has a glass frit (Preparation Example 4) coated with a fatty acid (e.g., oleic acid) It can be seen that the adhesive force is uneven. As a result, the glass frit coated with the aliphatic amine compound improves the dispersibility, whereas the glass frit coated with the fatty acid can deduce that the dispersibility is degraded.

(6) Evaluation of adhesion 2

The conductive paste prepared according to Examples 1 and 4 and Comparative Example 1 was used to manufacture solar cells in the same manner as described above, and conductive ribbons were formed on the electrodes of each of the cells through the tabbing process described above Respectively. The conductor ribbon was then removed and interfacial images were measured. 6A to 6C are surface images of electrodes taken after the removal of the conductive ribbon. 6A to 6C, it can be seen that the electrode made of the conductive paste of Example 1 has a uniform interface after the ribbon is detached, as compared with the electrode made of the conductive paste of Comparative Examples 1 and 4. As a result, the glass frit coated with an aliphatic amine compound improves the dispersibility, while the glass frit coated with the fatty acid can infer that the dispersibility deteriorates.

The features, structures, effects, and the like illustrated in the above-described embodiments can be combined and modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

10: P-type silicon semiconductor substrate
20: N-type impurity layer
30: antireflection film
40: P + layer (BSF: back surface field)
50: rear aluminum electrode
60: rear silver electrode
100: front electrode

Claims (7)

Metal powders, glass frit, and organic vehicles,
Wherein the surface of the glass frit is coated with an aliphatic amine compound.
The method according to claim 1,
Wherein the aliphatic amine compound comprises an alkylamine-based material having 6 to 24 carbon atoms.
The method according to claim 1,
The alkylamine-based material may be selected from the group consisting of triethylamine, heptylamine, octadecylamine, hexadecylamine, decylamine, octylamine, didecylamine ), Or trioctylamine. ≪ Desc / Clms Page number 13 >
The method according to claim 1,
Wherein the coating layer formed by coating with the aliphatic amine compound has a thickness of 0.1 nm to 50 nm.
The method according to claim 1,
Wherein the glass frit is a first glass frit,
Wherein the conductive paste comprises a second glass fritter,
Wherein the surface of the second glass frit is not coated or is coated with a fatty acid.
6. The method of claim 5,
Wherein the fatty acid comprises lauric acid, oleic acid, stearic acid, palmitic acid or acetic acid.
1. A solar cell having a front electrode on a substrate and a back electrode on a bottom of the substrate,
Wherein the front electrode is manufactured by applying the conductive paste for a solar cell electrode of any one of claims 1 to 6, followed by drying and firing.

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