阅读说明：本技术 太阳能电池电极用导电性浆料以及使用上述浆料制造的太阳能电池 (Conductive paste for solar cell electrode and solar cell manufactured using same ) 是由 金仁喆 金和重 田*铉 高旼秀 张文硕 卢和泳 金冲镐 朴刚柱 于 2018-10-18 设计创作，主要内容包括：本发明提供一种太阳能电池电极用导电性浆料,其特征在于：包含金属粉末、玻璃熔块、金属氧化物、有机粘接剂以及溶剂,上述金属氧化物包含从由钨(W)、锑(Sb)、镍(Ni)、铜(Cu)、镁(Mg)、钙(Ca)、钌(Ru)、钼(Mo)以及铋(Bi)构成的组中选择的某1种以上的金属的氧化物。(The invention provides a conductive paste for a solar cell electrode, which is characterized in that: the glass frit contains a metal powder, a glass frit, a metal oxide, an organic binder, and a solvent, wherein the metal oxide contains an oxide of at least one metal selected from the group consisting of tungsten (W), antimony (Sb), nickel (Ni), copper (Cu), magnesium (Mg), calcium (Ca), ruthenium (Ru), molybdenum (Mo), and bismuth (Bi).)

1. A conductive paste for a solar cell electrode, characterized in that:

comprises metal powder, glass frit, metal oxide, organic binder and solvent,

the metal oxide includes an oxide of at least one metal selected from the group consisting of tungsten (W), antimony (Sb), nickel (Ni), copper (Cu), magnesium (Mg), calcium (Ca), ruthenium (Ru), molybdenum (Mo), and bismuth (Bi).

2. The electroconductive paste for solar cell electrodes according to claim 1, characterized in that:

the metal oxide contains an oxide of antimony (Sb).

3. The electroconductive paste for solar cell electrodes according to claim 2, characterized in that:

the content of the metal oxide is 0.1 wt% to 0.5 wt% based on the total weight of the conductive paste.

4. The electroconductive paste for solar cell electrodes according to claim 1, characterized in that:

the metal oxide includes at least 2 of the 1 st metal oxide and the 2 nd metal oxide selected from the group consisting of tungsten (W), antimony (Sb), nickel (Ni), copper (Cu), magnesium (Mg), calcium (Ca), ruthenium (Ru), molybdenum (Mo), and bismuth (Bi).

5. The electroconductive paste for solar cell electrodes according to claim 4, characterized in that:

the 1 st metal oxide is an oxide of tungsten (W), and the 2 nd metal oxide is an oxide of antimony (Sb).

6. The electroconductive paste for solar cell electrodes according to claim 5, characterized in that:

the weight ratio of the 1 st metal oxide to the 2 nd metal oxide is 1:1 to 5.

7. The electroconductive paste for solar cell electrodes according to claim 5, characterized in that:

the content of the above-mentioned 1 st metal oxide is 0.1 to 0.3 wt% and the content of the above-mentioned 2 nd metal oxide is 0.1 to 0.5 wt% based on the total weight of the above-mentioned conductive paste.

8. The electroconductive paste for solar cell electrodes according to claim 1, characterized in that:

the content of the glass frit is 2.5 wt% to 3.1 wt% based on the total weight of the conductive paste.

9. A solar cell, characterized by:

in a solar cell in which a front electrode is provided on the upper portion of a substrate and a back electrode is provided on the lower portion of the substrate,

the front surface electrode is produced by applying the conductive paste for a solar cell electrode according to any one of claims 1 to 8, and then drying and firing the applied conductive paste.

Technical Field

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

Background

Solar cells (solar cells) are semiconductor elements for converting solar energy into electrical energy, and are generally in the form of p-n junctions, and have the same basic structure as a diode. FIG. 1 shows a structure of a general solar cell device, which is generally formed by using a p-type silicon semiconductor substrate 10 having a thickness of 180 to 250 μm. An n-type doped layer 20 having a thickness of 0.3 to 0.6 μm, and an anti-reflection film 30 and a front electrode 100 located above the n-type doped layer are formed on the light-receiving surface side of the silicon semiconductor substrate. Further, a back surface electrode 50 is formed on the back surface side of the p-type silicon semiconductor substrate. The front electrode 100 is formed by applying conductive paste obtained by mixing conductive particles (silver powder) mainly containing silver, glass frit, organic vehicle (organic vehicle), and additives to the antireflection film 30 and then firing the applied conductive paste, and the rear electrode 50 is formed by applying and drying an aluminum paste composition composed of aluminum powder, glass frit, organic vehicle (organic vehicle), and additives by screen printing or the like and then firing the aluminum paste composition at a temperature of 660 ℃ (melting point of aluminum) or higher. During the above firing, aluminum will be diffused into the inside of the p-type silicon semiconductor substrate and thereby an Al — Si alloy layer will be formed between the back electrode and the p-type silicon semiconductor substrate, while the p + layer 40 will also be formed as an impurity layer by diffusion of aluminum atoms. With the p + layer as described above, recombination of electrons can be prevented, and a BSF (Back Surface Field) effect that can improve collection efficiency of generated carriers is achieved. A rear silver electrode 60 may be provided below the rear aluminum electrode 50.

Since the electromotive force of the solar cell including the solar cell electrode is low, a Photovoltaic Module (Photovoltaic Module) having an appropriate electromotive force is required to be constructed by connecting a plurality of solar cells, and the solar cells are connected by lead-plated ribbon wires having a specific length. At this time, a so-called leaching (leaching) phenomenon occurs in which Ag, which is a constituent of the electrode, is dissolved by Sn, which is a constituent contained in the tape lead. In order to solve the above-described problems, the desired electrical characteristics and adhesion can be achieved by adjusting the content and ratio of Ag and glass frit in the conductive paste, but in this case, in order to achieve high efficiency, the number of patterns of the bus bar electrode constituting the front electrode needs to be increased and the width thereof needs to be reduced, which leads to a problem that the adhesion between the ribbon-shaped wire and the front electrode is reduced.

Disclosure of Invention

Technical subject

The purpose of the present invention is to provide a conductive paste composition for a solar cell electrode, which can reduce the leaching (leaching) phenomenon in which the constituent components of the electrode dissolve during the soldering of an electrode ribbon wire in order to enhance the electrical characteristics of the front electrode.

However, the object of the present invention is not limited to the object mentioned in the above, and practitioners in the relevant arts will be able to further clearly understand other objects not mentioned through the following description.

Means for solving the problems

In order to solve the above problems, the present invention provides a conductive paste for a solar cell electrode, comprising: the glass frit comprises metal powder, glass frit, metal oxide, organic binder and solvent, wherein the metal oxide is composed of at least one of 1 st metal oxide containing tungsten and 2 nd metal oxide containing antimony.

Further, the present invention provides a conductive paste for a solar cell electrode, characterized in that: the metal oxide includes the 1 st metal oxide and the 2 nd metal oxide, and the 1 st metal oxide is WO₃And the 2 nd metal oxide is Sb₂O₃。

Further, the present invention provides a conductive paste for a solar cell electrode, characterized in that: the weight ratio of the 1 st metal oxide to the 2 nd metal oxide is 1:1 to 5.

Further, the present invention provides a conductive paste for a solar cell electrode, characterized in that: the content of the above-mentioned 1 st metal oxide is 0.1 to 0.3 wt% and the content of the above-mentioned 2 nd metal oxide is 0.1 to 0.4 wt% based on the total weight of the above-mentioned conductive paste.

Further, the present invention provides a conductive paste for a solar cell electrode, characterized in that: the content of the above-mentioned 1 st metal oxide is 0.1 wt% and the content of the above-mentioned 2 nd metal oxide is 0.4 wt% based on the total weight of the above-mentioned conductive paste.

Further, the present invention provides a conductive paste for a solar cell electrode, characterized in that: the content of the glass frit is 2.5 wt% to 3.1 wt% based on the total weight of the conductive paste.

Further, the present invention provides a solar cell, characterized in that: in a solar cell having a front electrode provided on an upper portion of a substrate and a back electrode provided on a lower portion of the substrate, the front electrode is produced by applying a conductive paste for a solar cell electrode mentioned in the above, followed by drying and firing.

Effects of the invention

The present invention can be obtained by adding WO to a conductive paste for a solar cell electrode₃And Sb₂O₃And liftThe adhesion between the ribbon-shaped wire and the front electrode is increased and thereby a leaching (leaching) phenomenon occurring in the process of soldering the ribbon-shaped wire to the front electrode is reduced. NiO, CuO and Bi are added to the conductive paste for solar cell electrodes₂O₃The leaching (leaching) phenomenon can be reduced.

Drawings

Fig. 1 is a schematic cross-sectional view of a general solar cell element.

Detailed Description

Before explaining the present invention in detail, it is to be understood that the terminology used in the description is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same technical meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Unless otherwise indicated, the term comprising, as used throughout this specification and the claims, is intended to include the inclusion of a stated object, step, or series of objects and steps, but is not intended to exclude the presence of any other object, step, or series of objects or steps.

Moreover, each embodiment to which the present invention is applied can also be implemented in combination with other embodiments, unless explicitly stated to the contrary otherwise. In particular, a feature specified as preferred or advantageous can also be combined with other features and features than those specified as preferred or advantageous. Next, embodiments to which the present invention is applied and effects thereof will be described in detail with reference to the accompanying drawings.

The paste according to an embodiment of the present invention is a paste suitable for use in forming a solar cell electrode, and provides a conductive paste for a solar cell electrode for reducing a leaching (leaching) phenomenon occurring when bonding a ribbon wire. Specifically, the conductive paste composition may include a metal powder, a glass frit, a metal oxide, an organic vehicle, and the like. In addition, various additives can be contained.

As the metal powder, silver powder, copper powder, nickel powder, aluminum powder, or the like can be used, and when applied to the front electrode, silver powder is mainly used, and when applied to the back electrode, aluminum powder is mainly used. Next, for convenience of explanation, the metal powder will be explained by taking silver powder as an example. The following description can be applied to other metal powders as well.

In consideration of the thickness of the electrode formed at the time of printing and the linear resistance of the electrode, the content of the metal powder is preferably 70 to 85 wt%, more preferably 85 to 95 wt%, based on the total weight (wt) of the conductive paste composition.

The silver powder is preferably pure silver powder, and silver-plated composite powder having at least the surface thereof made of silver, an alloy containing silver as a main component, or the like can be used. In addition, other metal powders may be mixed and used. For example, aluminum, gold, palladium, copper, nickel, or the like can be used.

The silver powder may have an average particle diameter of 0.05 to 3 μm, preferably 0.5 to 2.5 μm in consideration of ease of slurrying and compactness at the time of firing, and may have at least one of a spherical shape, a needle shape, a plate shape, and a non-specific shape. The silver powder may be used by mixing 2 or more kinds of powders having different average particle diameters, particle size distributions, shapes, and the like.

The composition, particle size, and shape of the glass frit are not particularly limited. Not only lead-containing glass frits but also lead-free glass frits can be used. Preferably, the glass frit contains 5 to 29 mol% of PbO and 20 to 34 mol% of TeO in terms of oxides as components and contents thereof₂3 to 20 mol% of Bi₂O₃20 mol% or less of SiO₂B of 10 mol% or less₂O₃Preferably 10 to 20 mol% of an alkali metal (Li, Na, K, etc.) and an alkaline earth metal (Ca, Mg, etc.). By combining the organic contents of the above components, the line width of the electrode can be prevented from increasing, and the organic film can be optimized in high surface resistanceContact resistance characteristics and optimization of short circuit current characteristics.

The average particle size of the glass frit is not limited, and may be in the range of 0.05 to 4 μm, and a plurality of types of particles having different average particle sizes may be mixed and used. Preferably, at least one of the glass frits used has an average particle size of 0.1 μm or more and 3 μm or less. This makes it possible to optimize the reactivity during firing, particularly minimize the damage of the n-layer in a high-temperature state, improve the adhesion, and optimize the open circuit voltage (Voc). In addition, the increase in the line width of the electrode during firing can be reduced.

The phase transition temperature of the glass frit can be 200 to 500 ℃, preferably 250 to 450 ℃, and the desired physical properties can be more effectively achieved while satisfying the corresponding range.

The content of the glass frit is preferably 0.1 to 15 wt%, more preferably 0.5 to 4 wt%, based on the total weight of the conductive paste composition.

The metal oxide includes an oxide of at least one metal selected from the group consisting of tungsten (W), antimony (Sb), nickel (Ni), copper (Cu), magnesium (Mg), calcium (Ca), ruthenium (Ru), molybdenum (Mo), and bismuth (Bi). The average particle diameter can be 0.01 to 5 μm, preferably 0.02 to 2 μm in view of its effect.

When the metal oxide contains 1 or more of the oxides of the metals, it is preferable that an oxide of antimony (Sb) is necessarily contained. When the antimony oxide is contained, the content of the metal oxide is preferably 0.1 to 0.5 wt%, more preferably 0.2 to 0.4 wt%, based on the total weight of the conductive paste.

The metal oxide preferably includes at least 2 of the 1 st metal oxide and the 2 nd metal oxide selected from the group consisting of tungsten (W), antimony (Sb), nickel (Ni), copper (Cu), magnesium (Mg), calcium (Ca), ruthenium (Ru), molybdenum (Mo), and bismuth (Bi).

When 2 or more kinds of the oxides of the above metals are contained in the above metal oxides, it is preferable that an oxide of tungsten (W) is necessarily contained as the 1 st metal oxide and an oxide of antimony (Sb) is necessarily contained as the 2 nd metal oxide. In this case, the weight ratio of the 1 st metal oxide to the 2 nd metal oxide is preferably 1:1 to 5. Further, when the oxide of tungsten and the oxide of antimony are contained, the content of the 1 st metal oxide is preferably 0.1 to 0.3 wt% and the content of the 2 nd metal oxide is preferably 0.1 to 0.5 wt%, more preferably 0.1 to 0.3 wt% of the 1 st metal oxide and 0.2 to 0.4 wt% of the 2 nd metal oxide are contained, based on the total weight of the conductive paste.

The organic vehicle is not limited, and may include an organic binder, a solvent, and the like. Sometimes the solvent can be omitted. The content of the organic vehicle is not limited, but preferably, it is contained in an amount of 3 to 25 wt%, more preferably 5 to 15 wt%, based on the total weight of the conductive paste composition.

The organic vehicle is required to have a characteristic of maintaining a uniformly mixed state of the metal powder and the glass frit, and for example, when the conductive paste is applied to a substrate by screen printing, homogenization of the conductive paste should be achieved to suppress blurring and flowing of a printed pattern, and the flowing-out property of the conductive paste from the screen printing plate and the separability of the printing plate should be improved.

The organic binder contained in the organic vehicle is not limited, and examples of the cellulose ester-based compound include cellulose acetate, cellulose acetate butyrate, and the like, examples of the cellulose ether-based compound include ethyl cellulose, methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and the like, examples of the acrylic-based compound include polyacrylamide, polymethacrylate, polymethyl methacrylate, polyethyl methacrylate, and the like, and examples of the vinyl group include polyvinyl butyral, polyvinyl acetate, polyvinyl alcohol, and the like. At least 1 or more kinds of the organic binder can be selected and used.

As the solvent for diluting the composition, at least one or more selected from compounds including α -terpineol, lauryl alcohol ester, dioctyl phthalate, dibutyl phthalate, cyclohexane, hexane, toluene, benzyl alcohol, dioxane, diethylene glycol, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate is preferably used.

Examples of the additive include a dispersant, a thickener, a thixotropic agent, and a leveling agent, the dispersant includes BYK-110, 111, 108, and 180, the thickener includes BYK-410, 411, and 420, the thickener includes BYK203, 204, and 205, and the leveling agent includes BYK-308, 307, and 3440, but not limited thereto.

The present invention can reduce a leaching (leaching) phenomenon occurring when welding an electrode to a ribbon wire by adjusting the content of the glass frit as described above.

Further, the present invention can reduce a leaching (leaching) phenomenon occurring when welding an electrode to a ribbon wire by adjusting the content of the metal oxide as described above.

In particular, the present invention can be achieved by selecting WO₃、Sb₂O₃、NiO、CuO、MgO、CaO、RuO、MoO、Bi₂O₃And the content ratio of the selected metal oxides is adjusted to reduce a leaching (leaching) phenomenon occurring when welding the electrode to the ribbon wire.

However, as described later, when the content ratio of the metal oxide is excessively increased, there is a possibility that the open circuit voltage is lowered or the contact resistance is increased.

Next, a detailed description will be given with reference to examples.