KR102680599B1 - Glass frit composition for forming solar cell electrode, solar cell electrode formed by using the same glass composition, and solar cell including the same electrode - Google Patents

Abstract

It relates to a glass frit composition for forming solar cell electrodes, an electrode for solar cells formed using the same, and a solar cell including the electrode, wherein the glass frit composition includes lead (Pb) - tellurium (Te) -- bismuth (Bi) The glass frit is a glass frit.
Specifically, with respect to the total amount of the glass frit (100 mol%), lead oxide (PbO), which is a first metal oxide, is contained in an amount of 19 to 23 mol%, and tellurium oxide (TeO ₂ ), which is a second metal oxide, is contained in an amount of 25 to 35 mol%. It contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), which is a third metal oxide, and 9 to 13 mol% of lithium oxide (Li ₂ O), which is a fourth metal oxide. A glass frit raw material containing 2 to 3 mol% of sodium oxide (Na ₂ O), which is a metal oxide, and the balance includes a sixth metal oxide, and the sixth metal oxide is different from the first to fifth metal oxides. It includes.

Description

Glass frit composition for forming solar cell electrodes, electrodes for solar cells formed using the same, and solar cells comprising the electrodes THE SAME ELECTRODE}

The present invention relates to batteries, and more specifically, to a glass frit composition for forming solar cell electrodes, an electrode for solar cells formed using the same, and a solar cell including the electrode.

In response to concerns about environmental pollution caused by fossil energy and depletion of the fossil energy, research to develop next-generation clean energy is actively underway. Among the next-generation clean energies, solar energy in particular has abundant resources and does not emit pollutants during the energy production process, so much research is being conducted as an energy source to replace fossil energy.

Solar cells using the solar energy are photoelectric conversion elements that convert the solar energy into electrical energy, and are attracting attention as an infinite, pollution-free next-generation energy resource. In order to increase the efficiency of these solar cells, it is important to be able to output as much electrical energy as possible from solar energy, and one way to increase the area is to increase the area.

However, as the area of the solar cell increases, the line resistance and contact resistance between the semiconductor substrate and the electrode increase, which may actually reduce the efficiency of the battery.

The technical problem to be solved by the present invention is to provide a glass frit composition for forming solar cell electrodes that improves contact between a semiconductor substrate and an electrode, minimizes line resistance and contact resistance, and ensures thermal stability.

In addition, another technical problem to be solved by the present invention is to provide an electrode for a solar cell formed using a glass frit composition for forming a solar cell electrode having the above advantages.

In addition, another technical problem to be solved by the present invention is to provide a solar cell including an electrode for a solar cell having the above advantages.

Glass frit composition for forming electrodes of solar cells

In one embodiment of the present invention, a glass frit composition for forming electrodes of solar cells, which is a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit, is provided. Specifically, with respect to the total amount of the glass frit (100 mol%), lead oxide (PbO), which is a first metal oxide, is contained in an amount of 19 to 23 mol%, and tellurium oxide (TeO ₂ ), which is a second metal oxide, is contained in an amount of 25 to 35 mol%. It contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), which is a third metal oxide, and 9 to 13 mol% of lithium oxide (Li ₂ O), which is a fourth metal oxide. A glass frit raw material containing 2 to 3 mol% of sodium oxide (Na ₂ O), which is a metal oxide, and the balance includes a sixth metal oxide, and the sixth metal oxide is different from the first to fifth metal oxides. may include.

In another embodiment, the glass frit may satisfy Equation 1 below.

[Equation 1]

49<A=([PbO]+[TeO ₂ ]+[Bi ₂ O ₃ ])<66

(In Equation 1, [PbO], [TeO ₂ ], and [Bi ₂ O ₃ ] are, respectively, the content (mol%) of the lead oxide (PbO) relative to the total amount of the glass frit (100 mol%), Tellurium oxide (TeO ₂ ) (mol%), and the content (mol%) of bismuth oxide (Bi ₂ O ₃ ).

In another example, the glass frit may satisfy Equation 2 below.

[Equation 2]

11<B=[Li ₂ O]+[Na ₂ O]<16

(In Equation 2, [Li ₂ O] and [Na ₂ O] are the content (mol%) of lithium oxide (Li ₂ O) and the sodium oxide (Na) relative to the total amount of glass frit (100 mol%), respectively. ₂ This refers to the content (mol%) of O).

In another example, the glass frit may satisfy Equation 3 below.

[Equation 3]

3.1<A/B<6.0

(In Equation 3 above, A refers to the value of Equation 1, and B refers to the value of Equation 2.)

In one embodiment, the six metal oxides include silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), copper oxide (CuO), and boron oxide (B ₂ O). ₃ ), and at least one glass frit raw material selected from the group including aluminum oxide (Al ₂ O ₃ ). In another embodiment, the glass frit may satisfy Equation 4 below.

[Equation 4]

3<[ZnO]+[WO ₃ ]+[Al ₂ O ₃ ]<11

(In Equation 4, [ZnO], [WO ₃ ], and [Al ₂ O ₃ ] are each the content (mol%) of the lead oxide (PbO) relative to the total amount of the glass frit (100 mol%), Tellurium oxide (TeO ₂ ) (mol%), and the content (mol%) of bismuth oxide (Bi ₂ O ₃ ).

In this regard, the following descriptions can each be applied independently.

In one embodiment, the sixth metal oxide includes silicon oxide (SiO ₂ ), and contains 16 to 23 mol% of silicon oxide (SiO ₂ ) based on the total amount of the glass frit (100 mol%), The remainder includes zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). It may contain one or more metal oxides selected from the group. In one embodiment, the sixth metal oxide includes copper oxide (CuO), and contains 0.2 to 0.5 mol% of copper oxide (CuO) based on the total amount of the glass frit (100 mol%), with the balance being is a group including silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). It may contain one or more metal oxides selected from.

In one embodiment, the sixth metal oxide includes silver oxide (Ag ₂ O), and contains 0.5 to 2.0 mol% of silver oxide (Ag ₂ O) based on the total amount of the glass frit (100 mol%), The remainder includes silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), aluminum oxide (Al ₂ O ₃ ), copper oxide (CuO), and boron oxide (B ₂ O ₃ ). It may contain one or more metal oxides selected from the group. In one embodiment, the sixth metal oxide includes boron oxide (B ₂ O ₃ ), and the boron oxide (B ₂ O ₃ ) is 0.5 to 1.5 mol based on the total amount of the glass frit (100 mol%). %, and the remainder includes silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), copper oxide (CuO), and aluminum oxide (Al ₂ O ₃ ). It may contain one or more metal oxides selected from the group containing.

In one embodiment, the sixth metal oxide includes aluminum oxide (Al ₂ O ₃ ), and the aluminum oxide (Al ₂ O ₃ ) is 0.4 to 1.0 mol based on the total amount of the glass frit (100 mol%). %, and the balance includes silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), copper oxide (CuO), and boron oxide (B ₂ O ₃ ). It may contain one or more metal oxides selected from the group containing. The glass frit may independently satisfy the physical properties described below.

In one embodiment, the softening point (Tdsp) of the glass frit may satisfy a temperature range of 260°C to 350°C. In one embodiment, the crystallization temperature (Tc) of the glass frit may satisfy a temperature range of 320°C to 420°C.

In one embodiment, the line resistance of the glass frit may be less than 3.0 uΩ·cm (excluding 0 uΩ·cm). In one embodiment, the contact resistance of the glass frit may be less than 2.0 mΩ·cm2 (except 0 mΩ·cm2). In one embodiment, the adhesion of the glass frit may be greater than 1.5 N.

Solar cell Paste composition for forming solar cell electrodes

In another embodiment of the present invention, conductive powder; glass frit; and an organic vehicle; wherein the glass frit is a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit. The present invention provides a paste composition for forming electrodes of a solar cell.

In one embodiment, 19 to 23 mol% of lead oxide (PbO), which is a first metal oxide, is included with respect to the total amount of glass frit (100 mol%), and the second metal oxide is contained in 19 to 23 mol%. It contains 25 to 35 mol% of tellurium oxide (TeO ₂ ) as a metal oxide, 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ) as a third metal oxide, and lithium oxide (Li) as a fourth metal oxide. ₂ O) is contained in an amount of 9 to 13 mol%, sodium oxide (Na ₂ O), which is a fifth metal oxide, is contained in an amount of 2 to 3 mol%, and the balance contains a sixth metal oxide, wherein the sixth metal oxide is It may include a glass frit raw material different from the first to fifth metal oxides.

In one embodiment, the glass frit may be the same as the one described above, and redundant description thereof will be omitted. In one embodiment, the conductive powder is silver (Ag) powder, silver (Ag)-containing alloy powder, aluminum (Al) powder, aluminum (Al)-containing alloy powder, copper (Cu) powder, aluminum (Al)-containing alloy. It may include at least one type of conductive powder selected from the group including powder, nickel (Ni) powder, and nickel (Ni)-containing alloy powder. In one embodiment, the organic vehicle may include an organic binder and an organic solvent.

In one embodiment, based on the total amount of the paste composition (100% by weight), the conductive powder is included in an amount of 86 to 90% by weight, the glass frit is included in an amount of 1.5 to 3.0% by weight, and the organic vehicle is included in an amount of 7 to 12.5% by weight. may be included.

In one embodiment, the paste composition may further include an additive. The additive may be included in an amount of 0.1 to 5% by weight based on the total amount (100% by weight) of the paste composition.

solar cell electrodes

In another embodiment of the present invention, an electrode for a solar cell manufactured using the above-described glass frit composition is provided.

Independently, in another embodiment of the present invention, an electrode for a solar cell manufactured using the above-described paste composition is provided.

solar cell

In another embodiment of the present invention, a semiconductor substrate; and an electrode located on at least one surface of the semiconductor substrate and formed using the glass frit composition described above. A solar cell including a solar cell can be provided.

Independently of this, in another embodiment of the present invention, a solar cell can be provided, which is located on at least one side of the semiconductor substrate and includes an electrode formed using the above-described paste composition.

The glass frit composition for forming solar cell electrodes according to an embodiment of the present invention contains 19 to 23 mol% of lead oxide (PbO), which is a first metal oxide, based on the total amount of glass frit (100 mol%), and a second metal oxide. It contains 25 to 35 mol% of tellurium oxide (TeO ₂ ) as a metal oxide, 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ) as a third metal oxide, and lithium oxide (Li) as a fourth metal oxide. ₂ O) is contained in an amount of 9 to 13 mol%, sodium oxide (Na ₂ O), which is a fifth metal oxide, is contained in an amount of 2 to 3 mol%, and the balance contains a sixth metal oxide, wherein the sixth metal oxide is By including a glass frit raw material different from the first to fifth metal oxides, the contact resistance between the electrode and the semiconductor substrate can be lowered and thermal stability can be ensured.

The contact resistance of the solar cell electrode according to another embodiment of the present invention can be reduced by using the glass frit composition for forming solar cell electrodes, which has the above-mentioned advantages.

The solar cell according to another embodiment of the present invention can improve the efficiency and thermal stability of the solar cell by using the solar cell electrode having the above-described advantages.

Figure 1 is a schematic diagram of a solar cell according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

In the drawing, the thickness is enlarged to clearly express various layers and areas. Throughout the specification, similar parts are given the same reference numerals. When a part of a layer, membrane, region, plate, etc. is said to be “on” another part, this includes not only cases where it is “directly above” the other part, but also cases where there is another part in between. Conversely, when a part is said to be “right on top” of another part, it means that there is no other part in between.

Generally, the electrode of a solar cell is prepared by mixing conductive powder, glass frit, and an organic vehicle, adding additional additives as necessary to prepare a paste composition, and applying this paste composition to one side of a semiconductor substrate. Alternatively, it can be formed according to a series of processes in which the applied paste composition is applied to both sides and patterned, and then the applied paste composition is fired and dried. Considering this electrode formation process, it can be seen that lowering line resistance and contact resistance by improving contact between the semiconductor substrate and the electrode formed thereon is an important factor in increasing the efficiency of solar cells.

Specifically, the glass frit etches the anti-reflection film during the firing process and melts the conductive powder to generate metal crystal particles in the emitter region, thereby creating a barrier between the electrode (particularly the metal crystal particles) and the semiconductor substrate. Not only does it play a role in lowering line resistance and contact resistance by improving adhesion, but it also softens and lowers the firing temperature.

In this regard, in one embodiment of the present invention, a glass frit that ensures thermal stability while lowering the contact resistance between the electrode and the semiconductor substrate is commonly applied to improve the efficiency and thermal stability of the solar cell.

Glass frit composition for forming electrodes of solar cells

In one embodiment of the present invention, a glass frit composition for forming electrodes of solar cells, which is a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit, is provided. Specifically, with respect to the total amount of the glass frit (100 mol%), lead oxide (PbO), which is a first metal oxide, is contained in an amount of 19 to 23 mol%, and tellurium oxide (TeO ₂ ), which is a second metal oxide, is contained in an amount of 25 to 35 mol%. It contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), which is a third metal oxide, and 9 to 13 mol% of lithium oxide (Li ₂ O), which is a fourth metal oxide. A glass frit raw material containing 2 to 3 mol% of sodium oxide (Na ₂ O), which is a metal oxide, and the balance includes a sixth metal oxide, and the sixth metal oxide is different from the first to fifth metal oxides. may include. The glass frit composition contains lead oxide (PbO), tellurium oxide (TeO ₂ ), bismuth oxide (Bi ₂ O ₃ ), lithium oxide (Li ₂ O), and sodium oxide (Na ₂ O) as main ingredients. , the remainder is a lead (Pb)-tellurium (Te)-bismuth (Bi)-based glass frit containing glass frit raw materials different from the above main components.

The lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit that satisfies the above content ranges ensures thermal stability while lowering the line resistance and contact resistance between the electrode and the semiconductor substrate. This fact is supported through the examples and evaluation examples described later.

In one embodiment, the glass frit may satisfy Equation 1 below.

[Equation 1]

49<A=([PbO]+[TeO ₂ ]+[Bi ₂ O ₃ ])<66

In Equation 1, [PbO], [TeO ₂ ], and [Bi ₂ O ₃ ] are, respectively, the content (mol%) of lead oxide (PbO) relative to the total amount of the glass frit (100 mol%), and the oxidation It means tellurium (TeO ₂ ) (mol%), and the content (mol%) of bismuth oxide (Bi ₂ O ₃ ). In Equation 1, when the [PbO] + [TeO ₂ ] + [Bi ₂ O ₃ ] value is greater than 66 mol%, the line resistivity and contact resistivity increase, leading to a decrease in efficiency and a decrease in adhesion. , if it is less than 49 mol%, there is a problem that the contact resistivity increases, which reduces cell efficiency when applied to solar cells. Accordingly, by satisfying the range of Equation 1, both line resistance and contact resistance are appropriately controlled, and thus a solar cell with improved efficiency can be obtained.

In one embodiment, the glass frit may satisfy Equation 2 below.

[Equation 2]

11<B=[Li ₂ O]+[Na ₂ O]<16

In Equation 2, [Li ₂ O] and [Na ₂ O] are the content (mol%) of lithium oxide (Li ₂ O) and the sodium oxide (Na ₂ ) relative to the total amount of glass frit (100 mol%), respectively. It refers to the content (mol%) of O). In Equation 1, when the [Li ₂ O] + [Na ₂ O] value is greater than 16 mol%, there is a problem of increased contact resistivity, and when it is less than 11 mol%, the line resistivity and contact resistivity increase, reducing efficiency. There is a problem of degradation, a problem of reduced adhesion, and a problem of reduced cell efficiency when applied to solar cells. Accordingly, by satisfying the range of Equation 2, both line resistance and contact resistance are appropriately controlled, and thus a solar cell with improved efficiency can be obtained.

In one embodiment, the glass frit may satisfy Equation 3 below.

[Equation 3]

3.1<A/B<6.0

In Equation 3, A refers to the value of Equation 1, and B refers to the value of Equation 2. In Equation 3 above, if the value of A/B is greater than 6.0, the line resistivity and contact resistivity increase, leading to problems of reduced efficiency and decreased adhesion, and if it is less than 3.1, the problem of increased contact resistivity. Therefore, there is a problem that cell efficiency decreases when solar cells are applied. Accordingly, by satisfying the range of Equation 3, both line resistance and contact resistance are appropriately controlled, and thus a solar cell with improved efficiency can be obtained. In one embodiment, the glass frit satisfies at least one of Equations 1 to 3 above, thereby not only lowering line resistance and contact resistance due to high contact properties, but also contributing to lowering the sintering temperature by softening at an appropriate softening point.

In one embodiment, the sixth metal oxide is not particularly limited as long as it is different from the first to fifth metal oxides among metal oxides generally used in glass frit compositions. The sixth metal oxide is a non-limiting example and includes silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide. It may include at least one glass frit raw material selected from the group containing (Al ₂ O ₃ ). Specifically, with regard to the latter case, the following explanations can be applied independently.

In one embodiment, the sixth metal oxide includes silicon oxide (SiO ₂ ), and contains 16 to 23 mol% of silicon oxide (SiO ₂ ) based on the total amount of the glass frit (100 mol%), The remainder is one or more selected from the group consisting of zinc oxide (ZnO), tungsten oxide (WO ₃ ), copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). May contain metal oxides. In one embodiment, the sixth metal oxide includes zinc oxide (ZnO),

Based on the total amount of the glass frit (100 mol%), 1 to 4 mol% of zinc oxide (ZnO) is included, and the balance includes silicon oxide (SiO ₂ ), tungsten oxide (WO ₃ ), copper oxide (CuO), It may include one or more metal oxides selected from the group including boron oxide (B ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ). In one embodiment, the sixth metal oxide includes tungsten oxide (WO ₃ ), and includes 2 to 6 mol% of tungsten oxide (WO ₃ ) based on the total amount of the glass frit (100 mol%), The remainder is one or more selected from the group consisting of silicon oxide (SiO ₂ ), zinc oxide (ZnO), copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). It may contain metal oxides.

In one embodiment, the sixth metal oxide includes the copper oxide (CuO), and relative to the total amount of the glass frit (100 mol%), the sixth metal oxide includes the tungsten oxide (WO ₃ ), Based on the total amount of the glass frit (100 mol%), 2 to 6 mol% of tungsten oxide (WO ₃ ) is included, and the balance includes silicon oxide (SiO ₂ ), zinc oxide (ZnO), copper oxide (CuO), It may contain one or more metal oxides selected from the group including boron oxide (B ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ). In one embodiment, the sixth metal oxide includes boron oxide (B ₂ O ₃ ), and the boron oxide (B ₂ O ₃ ) is 0.5 to 1.5 mol based on the total amount of the glass frit (100 mol%). %, and the balance is 1 selected from the group including silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), copper oxide (CuO), and aluminum oxide (Al ₂ O ₃ ). It may contain more than one type of metal oxide.

In one embodiment, the sixth metal oxide includes aluminum oxide (Al ₂ O ₃ ), and the aluminum oxide (Al ₂ O ₃ ) is 0.4 to 1.0 mol based on the total amount of the glass frit (100 mol%). %, and the balance is 1 selected from the group including silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), copper oxide (CuO), and boron oxide (B ₂ O ₃ ). It may contain more than one type of metal oxide. A mixture of all metal oxides exemplified as the sixth metal oxide may be used as the sixth metal oxide. In this case, based on the total amount of glass frit (100 mol%), 16 to 23 mol% of silicon oxide (SiO ₂ ) is included, 1 to 4 mol% of zinc oxide (ZnO) is included, and the tungsten oxide ( 2 to 6 mol% of WO ₃ ), 0.2 to 0.5 mol% of copper oxide (CuO), 0.5 to 1.5 mol% of boron oxide (B ₂ O ₃ ), and 0.5 to 1.5 mol% of aluminum oxide (Al ₂ O ₃ ). It may contain 0.4 to 1.0 mol%.

In one embodiment, the glass frit may satisfy Equation 4 below.

[Equation 4]

3<[ZnO]+[WO ₃ ]+[Al ₂ O ₃ ]<11

In Equation 4, [ZnO], [WO ₃ ], and [Al ₂ O ₃ ] are, respectively, the content (mol %) of zinc oxide (ZnO) relative to the total amount of the glass frit (100 mol %), and the oxidation It means tungsten (WO ₃ ) (mol%), and the content (mol%) of aluminum oxide (Al ₂ O ₃ ). In Equation 4, when the [ZnO] + [WO ₃ ] + [Al ₂ O ₃ ] value is greater than 11 mol%, there is a problem that the contact resistivity increases, and when it is less than 3 mol%, the contact resistivity increases. There is a problem that cell efficiency decreases when solar cells are applied. Accordingly, by satisfying the range of Equation 2, both line resistance and contact resistance are appropriately controlled, and thus a solar cell with improved efficiency can be obtained.

As described above, the glass frit mainly contains lead oxide (PbO), tellurium oxide (TeO ₂ ), bismuth oxide (Bi ₂ O ₃ ), lithium oxide (Li ₂ O), and sodium oxide (Na ₂ O). It consists of a metal oxide, which is a glass frit composition different from the main ingredient, and the balance includes metal oxide, which is a glass frit composition different from the main ingredient. When each ingredient satisfies a specific content range, excellent physical properties can be exhibited. Specifically, the glass frit can lower line resistance and contact resistance by improving the adhesion between the electrode and the semiconductor substrate, and can satisfy each range of adhesion, line resistance, and contact resistance described below.

In one embodiment, the adhesion of the glass frit may be greater than 1.5 N. In one embodiment, the line resistance of the glass frit may be less than 3.0 uΩ·cm (excluding 0 uΩ·cm). In one embodiment, the contact resistance of the glass frit may be less than 2.0 mΩ·cm2 (except 0 mΩ·cm2).

The glass frit can contribute to lowering the sintering temperature by softening at an appropriate softening point, and can satisfy each range of softening point and crystallization temperature described below. In one embodiment, the softening point (Tdsp) of the glass frit may satisfy a temperature range of 260°C to 350°C. In one embodiment, the crystallization temperature (Tc) of the glass frit may satisfy a temperature range of 320°C to 370°C.

The glass frit can be manufactured using conventional methods. For example, the glass frit contains lead oxide (PbO), tellurium oxide (TeO ₂ ), bismuth oxide (Bi ₂ O ₃ ), lithium oxide (Li ₂ O), and sodium oxide (Na ₂ O) as main ingredients. The remainder includes glass frit raw materials different from the main components, and each component is mixed so that each component satisfies a specific content range. At this time, mixing may be performed by physical or chemical methods, and as a non-limiting example, may be performed using a ball mill, planetary mill, etc.

Thereafter, the mixed composition is melted in a temperature range of 900°C to 1300°C, quenched at room temperature (25°C), and then milled using a jet mill, disk mill, planetary mill, etc. By grinding using , a glass frit with a final particle size adjusted can be obtained. Specifically, the finally obtained glass frit may have a D50 particle size of 0.1 to 10 ㎛, and its shape may be spherical or amorphous, as non-limiting examples.

Paste composition for forming electrodes of solar cells

In another embodiment of the present invention, a paste composition for forming electrodes of a solar cell includes conductive powder; glass frit; and an organic vehicle, wherein the glass frit may be a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit. Specifically, with respect to the total amount of the glass frit (100 mol%), lead oxide (PbO), which is a first metal oxide, is contained in an amount of 19 to 23 mol%, and tellurium oxide (TeO ₂ ), which is a second metal oxide, is contained in an amount of 25 to 35 mol%. It contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), which is a third metal oxide, and 9 to 13 mol% of lithium oxide (Li ₂ O), which is a fourth metal oxide. A glass frit raw material containing 2 to 3 mol% of sodium oxide (Na ₂ O), which is a metal oxide, and the balance includes a sixth metal oxide, and the sixth metal oxide is different from the first to fifth metal oxides. It includes. More specifically, the paste composition is a paste composition that uses the above-described glass frit and mixes it with conductive powder and an organic vehicle.

The glass frit may be included in an amount of 1 to 5% by weight, specifically 1.5 to 3% by weight, based on the total amount (100% by weight) of the paste composition. When the glass frit is included within the above content range, the adhesion between the electrode and the semiconductor substrate is improved, making it possible to implement a solar cell with excellent efficiency. Hereinafter, redundant description of the glass frit will be omitted and the remaining components of the paste composition will be described in detail.

The conductive powder is not particularly limited as long as it has conductivity and can perform the function of collecting photogenerated charges, and non-limiting examples include silver (Ag) powder and silver (Ag)-containing alloy. selected from the group consisting of powder, aluminum (Al) powder, aluminum (Al) containing alloy powder, copper (Cu) powder, aluminum (Al) containing alloy powder, nickel (Ni) powder, and nickel (Ni) containing alloy powder. It may contain at least one type of conductive powder. However, it is not limited to this and may be a different type of metal powder, and may contain other additives in addition to the metal powder.

In one embodiment, the conductive powder may be a collection of conductive particles having different particle diameters, and the average particle diameter may be 0.1 to 50 ㎛. In one embodiment, when the conductive powder is silver (Ag) powder, it may have an average particle diameter of 0.1 to 10 ㎛. At this time, the shape of the conductive particles is a non-limiting example, and any shape among spherical, plate-shaped, and amorphous is possible.

The conductive powder may be included in an amount of 80 to 95% by weight, specifically, 87 to 91% by weight, based on the total amount (100% by weight) of the paste composition. When the conductive powder is included within the above content range, excellent electrical conductivity can be achieved due to an appropriate packing density of the conductive powder during firing, and dispersibility can be improved when manufacturing a paste composition.

The organic vehicle is mixed with the conductive powder to give an appropriate viscosity to form a paste, and may include an organic binder and an organic solvent that dissolves it. The organic binder is a non-limiting example, and ethyl cellulose, ethyl hydroxyethyl cellulose, nitro cellulose, and acrylic acid ester resin may be used alone or in a mixture of two or more types.

The organic solvent includes, but is not limited to, 2,2,4-trimethyl-monoisobutyrate (Texanol), butyl carbitol acetate (diethylene glycol monobutyl ether acetate), toluene, ethyl cellosolve, butyl Glycol ether solvents such as senrosolve, butyl carbitol (diethylene glycol monobutyl ether), dibutyl carbitol (diethylene glycol dibutyl ether), propylene glycol monomethyl ether, hexylene glycol, terpineol Solvents such as (Terpineol), methyl ethyl ketone, and 3-pentanediol can be used alone or in combination of two or more.

Based on the total amount (100% by weight) of the paste composition, the organic vehicle may be included in an amount of 5 to 40% by weight, specifically 5 to 15% by weight. When the organic vehicle is contained within the above content range, a paste composition with appropriate viscosity can be produced.

Considering the specific content range of each component described above, with respect to the total amount (100% by weight) of the paste composition, the conductive powder is included in 87 to 91% by weight, the glass frit is included in 1.5 to 3.0% by weight, and the organic The vehicle may be included in an amount of 7 to 12.5% by weight.

In one embodiment, the paste composition may further include additives. If necessary, the additives include dispersants, thixotropic agents, plasticizers, viscosity stabilizers, anti-foaming agents, ultraviolet stabilizers, antioxidants, coupling agents, etc., which can be used alone or in a mixture of two or more. In one embodiment, the additive may be included in an amount of 0.1 to 5 wt% based on the total amount (100 wt%) of the paste composition.

solar cell electrodes

In another embodiment of the present invention, an electrode for a solar cell manufactured using the above-described glass frit composition or a paste composition containing the same is provided. The electrode may be a front electrode or a rear electrode, and is manufactured using the above-described glass frit composition or a paste composition containing the same, thereby improving the efficiency of the solar cell and ensuring thermal stability.

Redundant description of the above-described glass frit composition or paste composition containing the same will be omitted, and the electrode and its forming method will be described below.

solar cell

In another embodiment of the present invention, a semiconductor substrate; and an electrode located on at least one surface of the semiconductor substrate and formed using the above-described glass frit composition or a paste composition containing the same.

Figure 1 illustrates a cross-sectional view of the solar cell.

Hereinafter, a solar cell according to an embodiment will be described with reference to FIG. 1. This is a non-limiting example, and the solar cell is not limited to FIG. 1.

Below, for convenience of explanation, the upper and lower positional relationship will be described centering on the semiconductor substrate 10, but the relationship is not limited thereto. Additionally, the side of the semiconductor substrate 10 that receives solar energy is called the front side, and the side opposite to the front side is called the rear side.

Referring to FIG. 1 , a solar cell according to one embodiment includes a semiconductor substrate 10 including a lower semiconductor layer 10a and an upper semiconductor layer 10b.

The semiconductor substrate 10 may be made of a semiconductor material. The semiconductor material may specifically be crystalline silicon or a compound semiconductor, and a silicon wafer may be used as the crystalline silicon.

One of the lower semiconductor layer 10a and the upper semiconductor layer 10b may be a semiconductor layer doped with a p-type impurity, and the other may be a semiconductor layer doped with an n-type impurity. For example, the lower semiconductor layer 10a may be a semiconductor layer doped with the p-type impurity, and the upper semiconductor layer 10b may be a semiconductor layer doped with the n-type impurity. The p-type impurity may be a group III compound such as boron (B), and the n-type impurity may be a group V compound such as phosphorus (P).

In one embodiment, an electrode is formed on at least one surface of the semiconductor substrate 10. The electrode may include a front electrode 20 and a rear electrode 30, but this is a non-limiting example and is not limited to the above structure.

In one embodiment, an anti-reflection film 12 may be formed on the front surface of the semiconductor substrate 10. The anti-reflection film 12 is formed on the front surface of the semiconductor substrate 10 that receives solar energy to reduce light reflectance and increase selectivity in a specific wavelength region. Additionally, the efficiency of the solar cell can be increased by improving the contact characteristics with silicon present on the surface of the semiconductor substrate 10.

The anti-reflection film 12 may be made of a material that absorbs less light and has insulating properties. The anti _- reflection film is a _{non -} limiting example, _and includes silicon _nitride ( _SiN ) and a combination thereof, and may be formed as a single layer or multiple layers. In one embodiment, the anti-reflection film 12 may have a thickness of 200 to 1500 Å, but is not limited thereto.

A plurality of front electrodes 20 may be formed on the anti-reflection film 12. The front electrode 20 may extend parallel to one direction of the semiconductor substrate 10, but is not limited thereto.

The front electrode 20 may be formed using the above-described glass frit composition or a paste composition containing the same, and may be formed using a screen printing method. The conductive powder included in the composition at this time may be a low-resistance conductive powder such as silver (Ag).

A bus bar electrode (not shown) may be formed on the front electrode 21. The bus bar electrode is used to connect neighboring solar cells when assembling a plurality of solar cells.

A back electrode 30 may be formed on the lower part of the semiconductor substrate 10. The rear electrode 30 may be formed by a screen printing method using the above-described glass frit composition or a paste composition containing the same. The conductive powder included in the paste composition may be an opaque metal such as aluminum (Al).

In one embodiment, a solar cell is prepared by preparing a semiconductor substrate 10, doping the semiconductor substrate 10 with an n-type impurity, forming a front electrode 20, and forming a back electrode 30. It may include steps to:

The step of preparing the semiconductor substrate 10 is a step of preparing the semiconductor substrate 10 for solar cell manufacturing. As the semiconductor substrate 10, a silicon wafer may be used, which may be doped with p-type impurities.

The step of doping the semiconductor substrate 10 with an n-type impurity is a step of doping the semiconductor substrate 10 with an n-type impurity. The n-type impurity can be doped by diffusing POCl ₃ , H ₃ PO ₄ , etc. at high temperature. Accordingly, the semiconductor substrate 10 may include a lower semiconductor layer 10a and an upper semiconductor layer 10b doped with different impurities.

The step of forming the front electrode 20 is a step of forming an electrode that comes into contact with the upper semiconductor layer 10. An antireflection film 12 may be formed on the upper semiconductor layer 10b. The front electrode 20 can be formed by applying the above-described glass frit composition or a paste composition containing the same onto the anti-reflection film 12 and drying it. At this time, as the glass frit in the composition melts and penetrates the anti-reflection film 12, the front electrode 20 comes into contact with the upper semiconductor layer 10b.

In the step of forming the back electrode 30, the back electrode 30 can be formed by applying the above-described glass frit composition or a paste composition containing the same on the lower semiconductor layer 10a and then drying it.

In one embodiment, when forming the front electrode 20 and the rear electrode 30, each composition may be applied by a screen printing method and then baked and dried. The firing may be performed in a firing furnace, and the temperature may be raised to a temperature higher than the melting temperature of the conductive powder in each composition. For example, the firing may be performed at a temperature range of about 700 to 900 °C. A solar cell having the above structure can be manufactured according to the above steps, but is not limited thereto.

Hereinafter, preferred embodiments of the present invention, comparative examples, and evaluation examples by comparing them will be described. However, the following examples are only some of the preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Examples 1 to 18

(1) Manufacturing of glass frit

To satisfy Tables 1 and 2 below, lead oxide (PbO), tellurium oxide (TeO ₂ ), bismuth oxide (Bi ₂ O ₃ ), silicon oxide (SiO ₂ ), lithium oxide (Li ₂ O), and sodium oxide ( Mix Na ₂ O), zinc oxide (ZnO), tungsten oxide (WO ₃ ), silver oxide (Ag ₂ O), copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). Thus, the glass frit compositions of Examples 1 to 18 were prepared, respectively.

The mixing at this time was performed using a zero-gravity mixer, allowing sufficient time to ensure that all components in the glass frit composition were completely mixed. The mixed glass composition was placed in a platinum crucible, and then melting was performed at a temperature of 950 to 1,250°C. The melting time was 20 minutes (min). In the melting step, the molten glass composition was quenched through dry and wet quenching. The quenched glass melt was ground into powder using a jet mill and a fine mill to finally obtain a glass frit.

(2) Preparation of paste composition

Conductive powder, organic vehicle, and additives were added to the glass frits of Examples 1 to 18 and mixed to prepare respective paste compositions. Specifically, with respect to the total amount of each paste composition (100% by weight), the glass frit was 2.5% by weight, the conductive powder was 89.5% by weight, the organic vehicle was 5.5% by weight, and the additive was 2.5% by weight.

Silver (Ag) powder (D50 particle size: 2.0 ㎛) was used as the conductive powder, and the organic vehicle used was ethyl cellulose as an organic binder and (2,2,4-trimethyl-monoisobutyrate) as an organic solvent in 3: A mixture was used at a weight ratio of 97 (order of order: organic binder: organic solvent), and a thixotropic agent (CRAYVALLAC) and a dispersant (Duomeen TDO) were used as the additives.

(3) Fabrication of solar cells

Before forming the front electrode, an aluminum paste composition was applied to the back of a silicon wafer (sheet resistance: 85 Ω/sq.), a type of semiconductor substrate, and dried to form a back electrode. The aluminum paste composition was printed and dried using commercial product DSCP-A151 (Dongjin Semichem) paste, and then the front electrode was formed. The drying was performed by maintaining the temperature at 130° C. for 4 minutes (min) in an infrared drying furnace and then cooling.

Thereafter, the front electrode was formed using the paste compositions of Examples 1 to 18 prepared in (2) above, respectively. Each of the paste compositions was applied to the front surface of the silicon wafer on which the rear electrode was formed. The application was performed by screen printing in a certain pattern.

With both the rear electrode and the front electrode formed, firing was performed by raising the temperature to 770°C at a rate of 240 inches/min using a belt-type firing furnace.

Comparative Examples 1 to 21

Except that glass frit compositions were prepared with the compositions of Comparative Examples 1 to 21 instead of Examples 1 to 18 in Tables 1 and 2 below, the paste composition and front electrode were prepared in the same manner, and the solar cell was manufactured. Produced.

Content of each component in glass frit (unit: mol%, based on total amount of glass frit (100 mol%) PbO TeO ₂ Bi ₂ O ₃ SiO ₂ Li ₂ O Na ₂ O ZnO WO ₃ Ag ₂ O CuO B ₂ O ₃ Al ₂ O ₃ MgO CeO ₂ Ti ₂ o ₃ Poem 20.4 29.2 5.2 22.8 9.9 2.3 1.1 5.9 1.9 0.4 0.5 0.4 - - - Psalm 22.8 33.2 8.0 17.2 9.0 3.0 1.5 2.8 0.5 0.5 0.5 1.0 - - - Psalm 21.9 33.0 5.0 23.0 9.1 2.0 1.0 3.2 0.5 0.4 0.5 0.4 - - - Psalm 21.5 30.7 5.6 18.9 12.0 2.9 1.8 3.1 1.6 0.4 1.1 0.4 - - - Psalm 21.2 30.2 5.5 20.6 11.9 2.9 1.8 3.1 0.6 0.4 1.5 0.4 - - - Poem 23.0 25.0 5.0 23.0 13.0 3.0 1.0 2.0 2.0 0.5 1.5 1.0 - - - Poem 21.1 35.0 6.5 16.5 9.9 2.8 1.8 3.1 1.5 0.4 1.0 0.4 - - - Psalm 22.5 33.1 8.0 18.5 9.2 2.3 2.2 2.0 0.5 0.4 0.9 0.4 - - - Poem 23.0 25.0 5.0 22.5 12.5 3.0 3.2 2.0 2.0 0.4 1.0 0.4 - - - 21.7 27.5 7.3 19.1 12.6 2.3 3.1 2.5 1.5 0.4 1.0 1.0 - - - 23.0 26.0 7.3 21.0 10.5 2.3 2.5 2.5 1.9 0.4 1.5 1.0 - - - 21.6 25.4 7.3 23.0 10.5 2.3 2.7 2.5 1.9 0.3 1.5 1.0 - - - 21.3 25.1 7.3 20.8 13.0 2.7 3.1 2.9 1.9 0.4 1.0 0.4 - - - 20.3 30.8 8.0 17.8 11.3 3.0 1.1 3.9 2.0 0.4 1.0 0.4 - - - 19.9 32.2 7.1 17.4 11.1 2.2 3.1 3.8 1.4 0.3 1.0 0.4 - - - 19.6 25.0 5.3 22.2 12.8 2.4 3.3 5.9 1.0 0.5 1.5 0.4 - - - 19.1 32.9 5.1 16.5 10.0 2.2 4.0 5.8 2.0 0.4 1.1 1.0 - - - 23.0 26.1 8.0 16.5 10.0 2.2 4.0 5.8 2.0 0.4 1.1 1.0 - - - School 27.4 40.0 7.0 - 5.5 - 1.1 9.1 0.6 - - - 9.1 - - Teaching 27.1 39.6 6.9 - 6.6 - 1.1 9.0 0.6 - - - 9.0 - - School 25.4 37.0 6.5 - 12.7 - 1.1 8.5 0.5 - - - 8.5 - - Lesson 23.1 46.0 6.9 1.6 12.2 1.3 - 3.8 - - - - 5.1 - - School 22.5 27.0 3.8 23.0 9.4 2.5 5.5 4.3 - 0.4 1.1 0.5 - - - School 21.9 23.6 5.4 21.7 12.7 - 4.6 7.0 - - 0.8 1.2 - 1.0 - School 21.8 26.2 3.7 22.3 9.1 2.4 5.4 7.2 - 0.4 1.1 0.4 　 - - School 19.4 20.3 5.3 26.0 10.4 2.0 4.5 6.8 - - 0.8 1.2 - 0.9 2.3 School 20.4 21.3 5.3 24.0 12.4 - 2.5 8.8 - - 0.8 1.2 - 0.9 2.3 12.3 40.9 8.6 8.5 20.7 - 4.1 4.5 - - 0.4 - - - - 12.2 40.5 8.5 8.4 19.5 - 4.1 6.5 - - 0.4 - - - - 12.2 40.5 8.5 8.4 17.0 - 4.1 6.5 2.5 - 0.4 - - - - 12.1 40.1 8.4 8.3 19.3 - 4.0 6.4 1.0 - 0.4 - - - - 12.1 40.1 8.4 8.3 20.3 - 4.0 6.4 - - 0.4 - - - - 11.7 41.8 8.2 8.1 19.7 - 3.9 6.2 - - 0.4 - - - - 11.7 38.9 8.2 12.1 19.7 - 3.9 5.2 - - 0.4 - - - - 11.7 38.9 8.2 8.1 19.7 - 5.9 6.2 - - 0.4 - - 1.0 - 11.6 38.5 8.1 10.0 19.5 - 5.8 6.1 - - 0.4 - - - - 11.6 38.5 2.0 8.0 19.5 - 5.8 6.1 - - 0.4 - 8.1 - - 11.5 38.1 8.0 7.9 19.3 - 7.8 6.1 - - 0.4 1.0 - - - 11.4 37.8 7.9 9.8 19.1 - 7.7 6.0 - - 0.4 - - - -

division Equation 1:
A=[PbO]+[TeO ₂ ]+[Bi ₂ O ₃ ] Equation 2:
B=[Li ₂ O]+[Na ₂ O] Equation 3:
C=A/B Equation 4:
D=[ZnO]+[WO ₃ ]+[Al ₂ O ₃ ] Example One 54.8 12.2 4.5 7.4 2 64.0 12.0 5.3 5.3 3 59.9 11.1 5.4 4.7 4 57.8 14.9 3.9 5.4 5 56.9 14.7 3.9 5.3 6 53.0 16.0 3.3 4.0 7 62.5 12.8 4.9 5.2 8 63.6 11.5 5.5 4.7 9 53.0 15.5 3.4 5.6 10 56.5 14.9 3.8 6.6 11 56.3 12.8 4.4 6.0 12 54.3 12.8 4.2 6.2 13 53.7 15.7 3.4 6.5 14 59.1 14.3 4.1 5.4 15 59.1 13.4 4.4 7.3 16 49.9 15.2 3.3 9.7 17 57.1 12.2 4.7 10.8 18 57.1 12.2 4.7 10.8 Comparative example One 74.5 5.5 13.4 10.3 2 73.7 6.6 11.2 10.2 3 68.8 12.7 5.4 9.5 4 76.1 13.5 5.6 3.8 5 53.3 11.9 4.5 10.3 6 51.0 12.7 4.0 12.8 7 51.7 11.5 4.5 13.0 8 49.8 12.4 4.0 12.5 9 49.8 12.4 4.0 12.5 10 53.2 20.7 2.6 8.6 11 52.7 19.5 2.7 10.5 12 52.7 18.5 2.9 10.5 13 52.2 19.3 2.7 10.4 14 52.2 20.3 2.6 10.4 15 53.6 19.7 2.7 10.1 16 50.6 19.7 2.6 9.1 17 50.6 19.7 2.6 12.1 18 50.1 19.5 2.6 12.0 19 52.1 19.5 2.7 12.0 20 49.6 19.3 2.6 14.8 21 49.1 19.1 2.6 13.7

Evaluation Example 1: Evaluation of adhesion, line resistivity, and contact resistivity

The glass frit, the paste composition, or the solar cell were evaluated for adhesion, line resistivity, and contact resistivity, and the evaluation results are shown in Table 3 below. At this time, the specific evaluation conditions are as follows.

Adhesion : Align the ribbon (width 1.1 mm, thickness 0.2 mm) with the island type bus bar of the front electrode of each solar cell, then heat at 380°C using a tabbing machine. Bonding was performed while applying hot air. For each bonded wafer, a peel test (180 degree conditions) was performed using a universal testing machine (NTS technology). In this regard, the adhesion forces reported in Table 3 below are the highest values measured in the peel test.

Line resistivity : After printing, drying, and firing the electrode paste composition containing each silver powder on a printing plate having a length of 20,000 ㎛ and a width of 60 ㎛, the line resistance was measured using a multimeter (Tektronix DMM 4020 device). . Separately, the area was measured using a laser microscope (KEYENCE VK-X100). Afterwards, the line resistivity was calculated by entering each measured value into Calculation Formula 1 below and recorded in Table 3.

[Calculation Formula 1] Line resistivity = (resistance × area) / length

Contact resistivity : Contact resistance was measured using TLM (Transfer Length Method), one of the widely known methods. Specifically, first, the electrode paste composition containing each of the silver powders is printed on a wafer in a bar pattern (L*Z, 500㎛*3000㎛), and then drying and firing processes are performed. At this time, in order to suppress the interference phenomenon when measuring contact resistance, a laser etching machine (Laser Etching Machine, Hardram) was used twice with a frequency of 200 kHz and a pulse width of 50%. By irradiation, the border of the bar pattern was isolated. Afterwards, the resistance was measured with a multimeter (Tektronix DMM 4020 device), the slope and intercept of the resistance according to the gap were measured, and the contact resistance (Ri, R _total ) was obtained. The measured contact resistance and area were entered into Equation 2 below to calculate the contact resistivity and recorded in Table 3 below.

[Calculation Formula 2] Contact resistivity = contact resistance × area

division line resistivity
(Unit: uΩ·cm) contact resistivity
(Unit: mΩㆍ㎠) adhesion
(Unit: N) Example One 2.6 1.6 1.8 2 2.6 1.3 1.5 3 2.7 1.4 2.5 4 2.8 1.8 2.2 5 2.0 1.5 2.0 6 2.9 1.8 2.1 7 2.8 1.8 1.7 8 2.8 1.6 1.7 9 2.7 1.8 1.8 10 2.8 1.9 1.5 11 2.8 1.9 1.6 12 2.9 1.9 1.6 13 2.6 1.6 1.8 14 2.6 1.9 1.5 15 2.6 1.9 1.6 16 2.7 1.9 1.7 17 2.6 1.9 2.2 18 2.7 1.6 2.4 Comparative example One 3.1 2.4 1.4 2 3.2 2.6 1.4 3 3.5 2.5 2.1 4 3.5 2.8 1.3 5 2.6 2.4 2.4 6 2.7 2.5 2.6 7 2.6 3.2 2.3 8 3.3 1.2 2.9 9 3.4 1.4 2.1 10 2.7 2.4 2.3 11 2.6 2.1 2.3 12 2.8 2.5 2.4 13 2.8 2.1 2.3 14 2.6 2.4 2.6 15 2.4 2.3 2.4 16 2.6 2.6 1.7 17 2.7 2.4 2.3 18 2.7 2.8 2.3 19 2.8 2.9 2.3 20 2.8 2.5 2.5 21 2.5 2.3 2.4

According to Table 3, in the case of Examples 1 to 18, excellent adhesion exceeding 1.5 N was shown, while line resistance was lower than 3.0 uΩ·cm and contact resistance was lower than 2.0 mΩ·cm2. On the other hand, Comparative Examples 1, 2, and 4 have low adhesion, Comparative Examples 1 to 4, 8, and 9 have high line resistance, and Comparative Examples 1 to 7 and 10 to 21 have high contact resistivity. There is. This is due to the difference in glass frit composition. Unlike Comparative Examples 1 to 21, Examples 1 to 18 satisfy all of Tables 1 and 2, showing excellent adhesion between the electrode and the semiconductor substrate, and thus This means that line resistance and contact resistance are lowered.

Evaluation Example 2: Evaluation of transition point and crystallization temperature

For each glass frit, the softening point and crystallization temperature were evaluated, and the evaluation results are shown in Table 4 below. At this time, the specific evaluation conditions are as follows.

Transition point : The glass transition temperature, also called the transition temperature, is the thermal characteristic of the section where the temperature changes from an elastic body to a viscous body or from a viscous body to an elastic body when the temperature increases or decreases. Each glass frit is placed in an aluminum pan. was applied and measured using a Differential Scanning Calorimeter (DSC, TA) while increasing the temperature to 580°C at a temperature increase rate of 10°C/min. During measurement, the peak point at which the endothermic reaction ends was analyzed to confirm the Tg temperature and recorded in Table 4 below.

Crystallization temperature : The same device used to measure the softening point was used, and the same heating rate and temperature conditions were applied, but the peak point at which the exothermic reaction ends during measurement was analyzed to determine the Tc temperature, and recorded in Table 4 below. .

division transition point
(Tg, ℃) crystallization temperature
(Tc, ℃) Example One 274.4 327.2 2 341.4 358.6 3 280.3 335.7 4 338.1 360.0 5 340.8 360.3 6 329.3 356.9 7 340.7 362.7 8 340.5 359.3 9 281.8 332.8 10 338.9 358.5 11 276.6 360.9 12 277.8 355.4 13 284.1 367.8 14 335.6 353.6 15 334.4 350.4 16 336.3 353.5 17 340.5 364.4 18 267.6 325.0

According to Table 4, in the case of Examples 1 to 18, the softening point was measured in an appropriate range of 260 ℃ to 350 ℃, and the crystallization temperature was measured to be 320 ℃ to 420 ℃.

The present invention is not limited to the above-mentioned embodiments, but can be manufactured in various different forms, and those skilled in the art will be able to form other specific forms without changing the technical idea or essential features of the present invention. You will be able to understand that this can be implemented. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

10: semiconductor substrate 10a: lower semiconductor layer
10b: upper semiconductor layer 12: anti-reflection layer
20: front electrode 30: rear electrode

Claims (26)

It is a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit,
Regarding the total amount of glass frit (100 mol%),
Contains 19 to 23 mol% of lead oxide (PbO), which is the first metal oxide,
It contains 25 to 35 mol% of tellurium oxide (TeO ₂ ), which is a second metal oxide,
Contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), a third metal oxide,
Contains 9 to 13 mol% of lithium oxide (Li ₂ O), a fourth metal oxide,
Contains 2 to 3 mol% of sodium oxide (Na ₂ O), a fifth metal oxide,
The remainder includes a sixth metal oxide, wherein the sixth metal oxide includes a glass frit raw material different from the first to fifth metal oxides,
The sixth metal oxide includes zinc oxide (ZnO), tungsten oxide (WO ₃ ), and aluminum oxide (Al ₂ O ₃ ),
With respect to the total amount of the glass frit (100 mol%), the zinc oxide (ZnO) is 1 to 4 mol%, the tungsten oxide (WO ₃ ) is 2 to 6 mol%, and the aluminum oxide (Al ₂ O ₃ ) is 0.4 mol%. to 1.0 mol%,
The glass frit is a glass frit composition for forming electrodes of solar cells that satisfies the following equation 4.
[Equation 4]
3<[ZnO]+[WO ₃ ]+[Al ₂ O ₃ ]<11
(In Equation 4, [ZnO], [WO ₃ ], and [Al ₂ O ₃ ] are the content (mol%) of zinc oxide (ZnO) relative to the total amount of glass frit (100 mol%), respectively. Tungsten oxide (WO ₃ ) (mol%), and the content (mol%) of aluminum oxide (Al ₂ O ₃ )
According to claim 1,
The glass frit is a glass frit composition for forming electrodes of solar cells that satisfies the following formula 1.
[Equation 1]
49<A=([PbO]+[TeO ₂ ]+[Bi ₂ O ₃ ])<66
(In Equation 1, [PbO], [TeO ₂ ], and [Bi ₂ O ₃ ] are, respectively, the content (mol%) of the lead oxide (PbO) relative to the total amount of the glass frit (100 mol%), Tellurium oxide (TeO ₂ ) (mol%), and the content (mol%) of bismuth oxide (Bi ₂ O ₃ )
According to claim 1,
The glass frit is a glass frit composition for forming electrodes of solar cells that satisfies the following equation 2.
[Equation 2]
11<B=([Li ₂ O]+[Na ₂ O])<16
(In Equation 2, [Li ₂ O] and [Na ₂ O] are the content (mol%) of the lithium oxide (Li ₂ O) and the sodium oxide (mol%) relative to the total amount of the glass frit (100 mol%), respectively. refers to the content (mol%) of Na ₂ O)
According to clause 3,
The glass frit is a glass frit composition for forming electrodes of solar cells that satisfies the following equation 3.
[Equation 3]
3.1<A/B<6.0
(In Equation 3 above, A refers to the value of [PbO]+[TeO ₂ ]+[Bi ₂ O ₃ ], B refers to the value of [Li ₂ O]+[Na ₂ O], and [PbO ], [TeO ₂ ], [Bi ₂ O ₃ ], [Li ₂ O] and [Na ₂ O] are the content (mol%) of lead oxide (PbO) relative to the total amount of glass frit (100 mol%), respectively. ), the tellurium oxide (TeO ₂ ) (mol%), the content of bismuth oxide (Bi ₂ O ₃ ) (mol%), the content of lithium oxide (Li ₂ O) (mol%), and the sodium oxide. (Means the content (mol%) of Na ₂ O)
According to claim 1,
The sixth metal oxide is,
A solar cell comprising at least one glass frit raw material selected from the group consisting of silicon oxide (SiO ₂ ), silver oxide (Ag ₂ O), copper oxide (CuO), and boron oxide (B ₂ O ₃ ). Glass frit composition for forming electrodes.
delete According to clause 5,
The sixth metal oxide includes the silicon oxide (SiO ₂ ),
Based on the total amount of the glass frit (100 mol%), 16 to 23 mol% of silicon oxide (SiO ₂ ) is included, and the balance is zinc oxide (ZnO), tungsten oxide (WO ₃ ), and silver oxide (Ag ₂ O). , copper oxide (CuO), boron oxide (B ₂ O ₃ ), and aluminum oxide (Al ₂ O ₃ ). A glass frit composition for forming an electrode of a solar cell containing one or more metal oxides selected from the group consisting of.
delete delete According to clause 5,
The sixth metal oxide includes the silver oxide (Ag ₂ O),
Based on the total amount of the glass frit (100 mol%), 0.5 to 2.0 mol% of silver oxide (Ag ₂ O) is included, and the balance is silicon oxide (SiO ₂ ), zinc oxide (ZnO), and tungsten oxide (WO ₃ ). , aluminum oxide (Al ₂ O ₃ ), copper oxide (CuO), and boron oxide (B ₂ O ₃ ). A glass frit composition for forming electrodes of solar cells containing at least one metal oxide selected from the group consisting of.
According to clause 5,
The sixth metal oxide includes the copper oxide (CuO),
With respect to the total amount of the glass frit (100 mol%), the copper oxide (CuO) is included from 0.2 to 0.5 mol%, and the balance includes silicon oxide (SiO2), zinc oxide (ZnO), silver oxide (Ag2O), and tungsten oxide ( A glass frit composition for forming an electrode of a solar cell containing at least one metal oxide selected from the group consisting of WO3), boron oxide (B2O3), and aluminum oxide (Al2O3).
According to clause 5,
The sixth metal oxide includes the boron oxide (B ₂ O ₃ ),
Based on the total amount of the glass frit (100 mol%), 0.5 to 1.5 mol% of boron oxide (B ₂ O ₃ ) is included, and the balance is silicon oxide (SiO ₂ ), zinc oxide (ZnO), and tungsten oxide (WO). ₃ ), a glass frit composition for forming an electrode of a solar cell containing at least one metal oxide selected from the group consisting of silver oxide (Ag ₂ O), copper oxide (CuO), and aluminum oxide (Al ₂ O ₃ ).
delete According to claim 1,
The transition point of the glass frit is,
A glass frit composition for forming electrodes of solar cells that satisfies a temperature range of 260°C to 350°C.
According to claim 1,
The crystallization temperature (Tc) of the glass frit is,
A glass frit composition for forming electrodes of solar cells in a temperature range of 320° C. to 420° C.
According to claim 1,
The line resistance of the glass frit is,
A glass frit composition for forming electrodes of solar cells less than 3.0 uΩ·cm (excluding 0 uΩ·cm).
According to paragraph 1,
The contact resistance of the glass frit is,
A glass frit composition for forming electrodes of solar cells with a thickness of less than 2.0 mΩ·cm2 (excluding 0 mΩ·cm2).
According to paragraph 1,
Adhesion of the glass frit is greater than 1.5 N. A glass frit composition for forming electrodes of solar cells.
conductive powder;
glass frit; and
Contains an organic vehicle;
The glass frit is a lead (Pb)-tellurium (Te)-bismuth (Bi) based glass frit,
Based on the total amount of glass frit (100 mol%), lead oxide (PbO), which is a first metal oxide, is included in an amount of 19 to 23 mol%,
It contains 25 to 35 mol% of tellurium oxide (TeO ₂ ), which is a second metal oxide,
Contains 5 to 8 mol% of bismuth oxide (Bi ₂ O ₃ ), a third metal oxide,
Contains 9 to 13 mol% of lithium oxide (Li ₂ O), a fourth metal oxide,
Contains 2 to 3 mol% of sodium oxide (Na ₂ O), a fifth metal oxide,
The remainder includes a sixth metal oxide, wherein the sixth metal oxide includes a glass frit raw material different from the first to fifth metal oxides,
The sixth metal oxide includes zinc oxide (ZnO), tungsten oxide (WO ₃ ), and aluminum oxide (Al ₂ O ₃ ),
With respect to the total amount of the glass frit (100 mol%), the zinc oxide (ZnO) is 1 to 4 mol%, the tungsten oxide (WO ₃ ) is 2 to 6 mol%, and the aluminum oxide (Al ₂ O ₃ ) is 0.4 mol%. to 1.0 mol%,
The glass frit is a paste composition for forming electrodes of solar cells that satisfies Equation 4 below.
[Equation 4]
3<[ZnO]+[WO ₃ ]+[Al ₂ O ₃ ]<11
(In Equation 4, [ZnO], [WO ₃ ], and [Al ₂ O ₃ ] are the content (mol%) of zinc oxide (ZnO) relative to the total amount of glass frit (100 mol%), respectively. Tungsten oxide (WO ₃ ) (mol%), and the content (mol%) of aluminum oxide (Al ₂ O ₃ )
According to clause 19,
The conductive powder is,
Silver (Ag) powder, silver (Ag)-containing alloy powder, aluminum (Al) powder, aluminum (Al)-containing alloy powder, copper (Cu) powder, copper (Cu)-containing alloy powder, nickel (Ni) powder, and nickel A paste composition for forming electrodes of a solar cell comprising at least one type of conductive powder selected from the group containing (Ni)-containing alloy powder.
According to clause 19,
The organic vehicle is,
A paste composition for forming electrodes of a solar cell comprising an organic binder and an organic solvent.
According to clause 19,
A paste composition for forming electrodes of a solar cell further comprising an additive.
An electrode for a solar cell formed using the composition of any one of claims 1 to 5, 7, 10 to 12, and 14 to 18.
An electrode for a solar cell formed using the composition of any one of claims 19 to 22.
semiconductor substrate; and
A solar cell comprising: an electrode according to claim 23, located on at least one surface of the semiconductor substrate.
semiconductor substrate; and
A solar cell comprising: an electrode according to claim 24, located on at least one surface of the semiconductor substrate.