JP7039491B2 - Paste composition for solar cells - Google Patents

Description

The present invention relates to a paste composition for a solar cell, and is particularly intended for a solar cell for forming a p ⁺ layer with respect to a crystalline solar cell having a passivation film provided with an opening by using laser irradiation or the like. Regarding the paste composition.

In recent years, various researches and developments have been carried out for the purpose of improving the conversion efficiency (power generation efficiency), reliability, etc. of crystalline solar cells. As one of them, a PERC (Passivated emitter and rear cell) type high conversion efficiency cell is attracting attention.

The PERC type high conversion efficiency cell has a structure including, for example, an electrode layer containing aluminum as a main component. This electrode layer (particularly the back electrode layer) is formed by, for example, applying a paste composition mainly composed of aluminum to a pattern shape, drying the paste composition as necessary, and then firing the paste layer. It is known that the conversion efficiency of the PERC type high conversion efficiency cell can be enhanced by appropriately designing the configuration of the electrode layer. For example, Patent Document 1 describes an aluminum paste containing a glass frit composed of 30 to 70 mol% Pb ²⁺ , 1 to 40 mol% Si ⁴⁺ , 10 to 65 mol% B ³⁺ , and 1 to 25 mol% Al ³⁺ . The composition is disclosed. Further, Patent Document 2 discloses a paste composition containing an aluminum powder, an aluminum-silicon alloy powder, a silicon powder, a glass powder, and an organic vehicle.

Japanese Unexamined Patent Publication No. 2013-145865 Japanese Unexamined Patent Publication No. 2013-143499

However, the electrode layer formed by using the conventional paste composition is a granular substance having an aluminum or aluminum-silicon alloy composition on the surface of the electrode layer after firing and having a diameter of about 20 to 200 μm (hereinafter, this granular substance is referred to as “this granular substance”. There is a problem that "Sandy") occurs and an appearance defect occurs. Further, when modularizing a solar cell, there is a problem that the cell is cracked starting from this Sandy.

An example of Sandy is shown in FIGS. 3 and 4. FIG. 3 is an example in which a Sandy of 220 μm is recognized, and FIG. 4 is an example in which a Sandy of 30 μm is recognized. On the other hand, FIG. 5 is an example in which Sandy is not recognized (an example in which there is no appearance defect).

The present invention has been made in view of the above, and is a paste composition having high adhesion after firing while preventing or suppressing the generation of Sandy on the surface of the electrode layer after firing in a crystalline solar cell. The purpose is to provide.

As a result of diligent research to achieve the above object, the present inventor has found that a paste composition containing a specific conductive material can achieve the above object, and has completed the present invention.

That is, the present invention relates to the following paste composition for solar cells.
1. 1. A paste composition for a solar cell containing glass powder, an organic vehicle and a conductive material.
(1) The conductive material contains 40% by mass or more of Al—X alloy powder having a melting point of more than 660 ° C and less than 800 ° C specified by differential scanning calorimetry.
(2) The element X in the Al—X alloy powder is at least one selected from the group consisting of silicon, barium, bismuth, calcium, germanium, indium, lanthanum, nickel, lead , strontium , tellurium and yttrium.
A paste composition for a solar cell, characterized in that.
2. 2. Item 2. The paste composition for a solar cell according to Item 1, wherein the conductive material further contains Al powder in addition to the Al—X alloy powder.
3. 3. Item 2. The paste composition for a solar cell according to Item 1 or 2, wherein the element X in the Al—X alloy powder is silicon.

According to the paste composition for a solar cell of the present invention, in a crystalline solar cell (particularly a PERC type high conversion efficiency cell), the generation of Sandy on the surface of the electrode layer after firing can be prevented or suppressed, and the electrode layer can be prevented. High adhesion can be obtained. The ability to prevent or suppress the generation of Sandy on the surface of the electrode layer after sintering is useful in preventing poor appearance and cracking during modularization of the solar cell.

It is a schematic diagram which shows an example of the cross-sectional structure of a PERC type solar cell, (a) is an example of the embodiment, (b) is another example of the embodiment. It is a schematic diagram of the cross section of the electrode structure produced in the Example and the comparative example. This is an example in which Sandy (220 μm) was observed on the surface of the electrode layer after firing. This is an example in which Sandy (30 μm) was observed on the surface of the electrode layer after firing. This is an example in which Sandy is not observed on the surface of the electrode layer after firing.

Hereinafter, the paste composition for a solar cell of the present invention will be described in detail. In the present specification, the range indicated by "-" means "greater than or equal to or less than" unless otherwise specified.

The paste composition for a solar cell of the present invention can be used, for example, to form an electrode of a crystalline solar cell. The crystalline solar cell is not particularly limited, and examples thereof include a PERC (Passivated emitter and rear cell) type high conversion efficiency cell (hereinafter referred to as “PERC type solar cell”). The paste composition for a solar cell of the present invention can be used, for example, to form a back electrode of a PERC type solar cell. Hereinafter, the paste composition of the present invention is also simply referred to as "paste composition".

First, an example of the structure of a PERC type solar cell will be described.

1. 1. PERC type solar cell FIGS. 1 (a) and 1 (b) are schematic views of a general cross-sectional structure of a PERC type solar cell. The PERC type solar cell may include a silicon semiconductor substrate 1, an n-type impurity layer 2, an antireflection film (passivation film) 3, a grid electrode 4, an electrode layer 5, an alloy layer 6, and a p ⁺ layer 7 as constituent elements. can.

The silicon semiconductor substrate 1 is not particularly limited, and for example, a p-type silicon substrate having a thickness of 180 to 250 μm is used.

The n-type impurity layer 2 is provided on the light receiving surface side of the silicon semiconductor substrate 1. The thickness of the n-type impurity layer 2 is, for example, 0.3 to 0.6 μm.

The antireflection film 3 and the grid electrode 4 are provided on the surface of the n-type impurity layer 2. The antireflection film 3 is formed of, for example, a silicon nitride film and is also referred to as a passivation film. By acting as a so-called passivation film, the antireflection film 3 can suppress the recombination of electrons on the surface of the silicon semiconductor substrate 1, and as a result, it is possible to reduce the recombination rate of the generated carriers. This enhances the conversion efficiency of the PERC type solar cell.

The antireflection film 3 is also provided on the back surface side of the silicon semiconductor substrate 1, that is, on the surface opposite to the light receiving surface. Further, a contact hole formed so as to penetrate the antireflection film 3 on the back surface side and scrape a part of the back surface of the silicon semiconductor substrate 1 is formed on the back surface side of the silicon semiconductor substrate 1.

The electrode layer 5 is formed so as to come into contact with the silicon semiconductor substrate 1 through the contact holes. The electrode layer 5 is a member formed by the paste composition of the present invention, and is formed in a predetermined pattern shape. The electrode layer 5 may be formed so as to cover the entire back surface of the PERC type solar cell as in the form of FIG. 1 (a), or the contact hole and the contact hole and the form as in the form of FIG. 1 (b). It may be formed so as to cover the vicinity thereof. Since the main component of the electrode layer 5 is aluminum, the electrode layer 5 is an aluminum electrode layer.

The electrode layer 5 can be formed, for example, by applying the paste composition to a predetermined pattern shape. The coating method is not particularly limited, and examples thereof include known methods such as screen printing. The electrode layer 5 is formed by applying the paste composition, drying it if necessary, and then firing it at a temperature exceeding the melting point of aluminum (about 660 ° C.) for a short time, for example.

In the present invention, the firing temperature may be a temperature exceeding the melting point of aluminum (about 660 ° C.), but is preferably about 750 to 950 ° C., more preferably about 780 to 900 ° C. The firing time can be appropriately set according to the firing temperature within the range in which the desired electrode layer 5 is formed.

When fired in this way, the aluminum contained in the paste composition diffuses into the silicon semiconductor substrate 1. As a result, an aluminum-silicon (Al-Si) alloy layer (alloy layer 6) is formed between the electrode layer 5 and the silicon semiconductor substrate 1, and at the same time, p by diffusion of aluminum atoms as an impurity layer. ⁺ Layer 7 is formed.

The p ⁺ layer 7 can bring about an effect of preventing electron recombination and improving the collection efficiency of generated carriers, that is, a so-called BSF (Back Surface Field) effect.

The electrode formed by the electrode layer 5 and the alloy layer 6 is the back surface electrode 8 shown in FIG. Therefore, the back surface electrode 8 is formed by using the paste composition, for example, the back surface electrode 8 is coated on the antireflection film 3 (passivation film 3) on the back surface side, dried as necessary, and then fired. Can be formed. Here, by forming the back surface electrode 8 using the paste composition of the present invention, it is possible to prevent or suppress the generation of Sandy on the surface of the electrode layer 5 after firing, and the electrode layer 5 after firing has high adhesion. Sex is obtained. In particular, being able to prevent or suppress the generation of Sandy on the surface of the electrode layer 5 after sintering is useful in preventing poor appearance and cracking during modularization of the solar cell.

2. 2. Paste Composition The paste composition of the present invention is a paste composition for a solar cell containing glass powder, an organic vehicle and a conductive material.
(1) The conductive material contains 40% by mass or more of Al—X alloy powder having a melting point of more than 660 ° C and less than 800 ° C specified by differential scanning calorimetry.
(2) The element X in the Al—X alloy powder is at least one selected from the group consisting of silicon, barium, bismuth, calcium, germanium, indium, lanthanum, nickel, lead, antimony, strontium, tellurium and yttrium. ,
It is characterized by that.

As described above, by using the paste composition, it is possible to form a back electrode of a solar cell such as a PERC type solar cell. That is, the paste composition of the present invention can be used to form a back electrode for a solar cell that electrically contacts the silicon substrate through the holes of the passivation film formed on the silicon substrate. According to the paste composition of the present invention, in a crystalline solar cell (particularly a PERC type solar cell), the generation of Sandy on the surface of the electrode layer after firing can be prevented or suppressed, and the electrode after firing can be prevented or suppressed. High adhesion of the layer can be obtained. In particular, being able to prevent or suppress the generation of Sandy on the surface of the electrode layer after sintering is useful in preventing poor appearance and cracking during modularization of the solar cell.

The paste composition contains glass powder, an organic vehicle and a conductive material (metal particles) as constituents. When the paste composition contains a conductive material (metal particles), the sintered body formed by firing the coating film of the paste composition exhibits conductivity that electrically connects to the silicon substrate. ..
(Conductive material)
In the present invention, the conductive material is
(1) Contains 40% by mass or more of Al—X alloy powder having a melting point (hereinafter abbreviated as “melting point”) specified by differential scanning calorimetry and having a melting point of more than 660 ° C and less than 800 ° C.
(2) The element X in the Al—X alloy powder is at least one selected from the group consisting of silicon, barium, bismuth, calcium, germanium, indium, lanthanum, nickel, lead, antimony, strontium, tellurium and yttrium. .. Here, the alloy component X is one or more of the above elements, and the element X may be one kind or two or more kinds.

Examples of Al-X alloys having a melting point of more than 660 ° C and less than 800 ° C include aluminum-silicon alloys, aluminum-valium alloys, aluminum-bismus alloys, aluminum-calcium alloys, aluminum-germanium alloys, aluminum-indium alloys, and aluminum-. Examples thereof include lanthanum alloys, aluminum-nickel alloys, aluminum-lead alloys, aluminum-antimon alloys, aluminum-strontium alloys, aluminum-tellu alloys, aluminum-ittrium alloys and the like. Among these, at least of aluminum-silicon alloy, aluminum-bismuth alloy, aluminum-germanium alloy, aluminum-indium alloy, aluminum-nickel alloy, aluminum-lead alloy and aluminum-antimonal alloy in that alloy powder can be easily formed. One type is preferable. Further, among these alloys, an aluminum-silicon alloy is more preferable from the viewpoint of good conductivity.

Since the melting point of these alloys changes according to the content of the element X, the melting point can be adjusted to exceed 660 ° C and to be less than 800 ° C by adjusting the content of the element X in each alloy. The melting point may be within such a range, but the melting point is preferably 670 ° C. or higher and 790 ° C. or lower, more preferably 680 ° C. or higher and 770 ° C. or lower, and most preferably 690 ° C. or higher and 750 ° C. or lower. The differential scanning calorimetry in the present specification is a value measured by a differential scanning calorimetry device (manufactured by Rigaku Co., Ltd., model number Thermo plus EVO2 TG-DTA / H-IR).

More specifically, the aluminum-silicon alloy has a silicon content of 18 to 28% by mass, the aluminum-valium alloy has a barium content of 3 to 12% by mass, and the aluminum-bismus alloy has a bismuth content of 4 to 10. Mass%, calcium content 12-19 mass% in aluminum-calcium alloys, germanium content 74-89 mass% in aluminum-germanium alloys, indium content 21-39 mass% in aluminum-indium alloys , The lantern content is 13-23% by mass in the aluminum-lantern alloy, the nickel content is 6-18% by mass in the aluminum-nickel alloy, the lead content is 2-4% by mass in the aluminum-lead alloy, and aluminum. -Antimon content is 2-10% by mass in antimonal alloys, strontium content is 1-5% by mass in aluminum-strontium alloys, tellurium content is 6-60% by mass in aluminum-tellu alloys, aluminum-ittrium. In the alloy, when the yttrium content is 11 to 20% by mass (both are the contents in the alloy), the melting point of each alloy can be adjusted to exceed 660 ° C and to be less than 800 ° C. In addition, you may use these alloys in combination of 2 or more types.

The conductive material contains the Al—X alloy powder in an amount of 40% by mass or more. Such a content can be widely set from 40% by mass to 100% by mass (when all the conductive materials are the Al—X alloy powder), but 50 to 80% by mass from the viewpoint of obtaining good conductivity. % Is preferable. Here, when the content of the Al—X alloy powder is less than 100% by mass, it is preferable that the balance is aluminum powder. It is permissible to contain metal particles other than the Al—X alloy powder and the aluminum powder, if necessary, as long as the effects of the present invention are not impaired. All of these conductive materials can be produced by a known atomization method such as a gas atomization method, a water atomization method, or a disk atomization method.

The above-mentioned aluminum powder refers to aluminum in which an alloy is not formed, but the presence of unavoidable impurities and trace amounts of additive elements derived from raw materials is not excluded. Similarly, the Al—X alloy in the present invention represents an alloy of aluminum and element X, but does not exclude the presence of unavoidable impurities in aluminum and element X and trace amounts of additive elements derived from raw materials.

The shape of the conductive material (Al—X alloy powder, aluminum powder) is not particularly limited, and may be, for example, spherical, elliptical, amorphous, scaly, fibrous or the like. When the shape of the conductive material is spherical, the filling property of the conductive material is increased in the electrode layer 5 formed by the paste composition, and the electric resistance can be effectively reduced.

Further, when the shape of the conductive material is spherical, the contact points between the silicon semiconductor substrate 1 and the conductive material increase in the electrode layer 5 formed by the paste composition, so that a good BSF layer can be easily formed. In the case of a spherical shape, the average particle size measured by the laser diffraction method is preferably in the range of 1 to 10 μm.
(Glass powder)
The glass powder is said to have an effect of assisting the reaction between the conductive material and silicon and the sintering of the conductive material itself.

The glass powder is not particularly limited, and can be, for example, a known glass component contained in a paste composition used for forming an electrode layer of a solar cell. Specific examples of the glass powder include a group consisting of lead (Pb), bismuth (Bi), vanadium (V), boron (B), silicon (Si), tin (Sn), phosphorus (P) and zinc (Zn). At least one selected from. Further, lead-containing glass powder or lead-free glass powder such as bismuth-based, vanadium-based, tin-lin-based, zinc borosilicate-based, and alkaline borosilicate-based can be used. In particular, considering the effect on the human body, it is desirable to use lead-free glass powder.

Specifically, the glass powder is B ₂ O ₃ , Bi ₂ O ₃ , ZnO, SiO ₂ , Al ₂ O ₃ , BaO, CaO, SrO, V ₂ O ₅ , Sb ₂ O ₃ , WO ₃ , P ₂ O ₅ . And at least one component selected from the group consisting of TeO ₂ can be contained. For example, in glass powder, a glass frit in which the molar ratio (B ₂ O ₃ / Bi ₂ O ₃ ) between the B ₂ O ₃ component and the Bi ₂ O ₃ component is 0.8 or more and 4.0 or less, and V ₂ O. A glass frit having a molar ratio (V ₂ O ₅ / BaO) of ₅ components to the BaO component of 1.0 or more and 2.5 or less may be combined.

The softening point of the glass powder can be, for example, 750 ° C. or lower. The average particle size of the particles contained in the glass powder can be, for example, 1 μm or more and 3 μm or less.

The content of the glass powder contained in the paste composition is preferably, for example, 0.5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the conductive material. In this case, the adhesion to the silicon semiconductor substrate 1 and the antireflection film 3 (passivation film) is good, and the electrical resistance is unlikely to increase. The content of the glass powder contained in the paste composition is particularly preferably 1 part by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the conductive material.
(Organic vehicle)
As the organic vehicle, a material in which various additives and resins are dissolved in a solvent can be used, if necessary. Alternatively, the resin itself may be used as an organic vehicle without containing a solvent.

As the solvent, known types can be used, and specific examples thereof include diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, and dipropylene glycol monomethyl ether.

As various additives, for example, antioxidants, corrosion inhibitors, antifoaming agents, thickeners, tack fires, coupling agents, antistatic agents, polymerization inhibitors, thixotropy agents, antisettling agents and the like are used. be able to. Specifically, for example, polyethylene glycol ester compound, polyethylene glycol ether compound, polyoxyethylene sorbitan ester compound, sorbitan alkyl ester compound, aliphatic polyvalent carboxylic acid compound, phosphoric acid ester compound, amidoamine salt of polyester acid, polyethylene oxide. System compounds, fatty acid amid wax and the like can be used.

Known types of resins can be used, such as ethyl cellulose, nitrocellulose, polyvinyl butyral, phenol resin, melanin resin, urea resin, xylene resin, alkyd resin, unsaturated polyester resin, acrylic resin, polyimide resin, and furan resin. Thermo-curable resins such as urethane resin, isocyanate compound, cyanate compound, polyethylene, polypropylene, polystyrene, ABS resin, polymethylmethacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyacetal, polycarbonate, polyethylene terephthalate, Two or more kinds of polybutylene terephthalate, polyphenylene oxide, polysulphon, polyimide, polyethersulphon, polyarylate, polyether ether ketone, polytetrafluoroethylene, silicon resin and the like can be used in combination.

The ratios of the resin, the solvent, and various additives contained in the organic vehicle can be arbitrarily adjusted, and for example, the component ratio can be the same as that of a known organic vehicle.

The content ratio of the organic vehicle is not particularly limited, but for example, from the viewpoint of having good printability, it is preferably 10 parts by mass or more and 500 parts by mass or less, preferably 20 parts by mass, with respect to 100 parts by mass of the conductive material. It is particularly preferable that the amount is 45 parts by mass or less.

The paste composition of the present invention is suitable for use, for example, for forming an electrode layer of a solar cell (particularly, a back electrode 8 of a PERC type solar cell as shown in FIG. 1). Therefore, the paste composition of the present invention can also be used as a back electrode forming agent for solar cells.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples. In addition, Example 5 is a reference example.

Example 1
40 parts by mass of Al-6.0 mass% Bi powder produced by the atomizing method, 60 parts by mass of Al powder produced by the atomizing method, and B ₂ O ₃ -Bi ₂ O ₃ -SrO-BaO-Sb ₂ O ₃ = A paste of 1.5 parts by mass of 40/40/10/5/5 (mol%) glass powder into 35 parts by mass of a resin solution prepared by dissolving ethyl cellulose in butyl diglycol using a known disperser. did.

A fired substrate, which is a solar cell for evaluation, was manufactured as follows.

First, as shown in FIG. 1A, a silicon semiconductor substrate 1 having a thickness of 180 μm was first prepared. Then, as shown in FIG. 1B, a YAG laser having a wavelength of 532 nm was used as a laser oscillator to form a contact hole 9 having a width D of 50 μm and a depth of 1 μm on the back surface of the silicon semiconductor substrate 1. The silicon semiconductor substrate 1 had a resistance value of 3 Ω · cm and was a backside passivation type single crystal.

Next, as shown in FIG. 2C, the paste composition 10 obtained above is applied to the surface of the silicon semiconductor substrate 1 so as to cover the entire back surface (the surface on the side where the contact holes 9 are formed). On the top, a screen printing machine was used to print at 1.0 to 1.1 g / pc. Next, although not shown, an Ag paste prepared by a known technique was printed on the light receiving surface.

Then, it was fired using an infrared belt furnace set at 800 ° C. By this firing, as shown in FIG. 2D, the electrode layer 5 is formed, and during this firing, aluminum diffuses inside the silicon semiconductor substrate 1, so that the electrode layer 5 and the silicon semiconductor substrate are formed. At the same time that the Al—Si alloy layer 6 was formed between 1 and 1, a p ⁺ layer (BSF layer) 7 was formed as an impurity layer due to the diffusion of aluminum atoms. As described above, a fired substrate for evaluation was manufactured.

In the evaluation of the obtained solar cell, the presence or absence of Sandy was confirmed using a microscope VHX-D500 manufactured by KEYENCE CORPORATION.

Those in which no Sandy was confirmed were marked with ◯, those in which a small Sandy of 50 μm or less was confirmed were marked with Δ, and those in which a large Sandy of 50 μm or more was confirmed were marked with ×. In addition, only ○ evaluation is passed.

Regarding the evaluation of adhesion, after attaching a mending tape (12 mm width, manufactured by 3M) to the surface of the aluminum electrode formed on the silicon substrate with a length of about 3 cm, the momentum is applied at an angle of 45 degrees to the silicon substrate. The tape was often peeled off, and the ratio of the total area of the part to which aluminum was attached and the area of the original mending tape to which the tape was attached was calculated using analysis software capable of binarization. Adhesion assessments were all performed by the same person at the same posture, angle, force, and constant speed. Those with no aluminum adhered to the mending tape were evaluated as ◯, and those with even a small amount of aluminum adhered were evaluated as x.

Example 2
A paste was prepared and evaluated in the same manner as in Example 1 except that 65 parts by mass of Al-20.0Si powder produced by the atomizing method and 35 parts by mass of Al powder produced by the atomizing method were used.

Example 3
A paste was prepared and evaluated in the same manner as in Example 1 except that 100 parts by mass of Al-20.0Si powder produced by the atomizing method was used.

Example 4
A paste was prepared and evaluated in the same manner as in Example 1 except that 45 parts by mass of Al-3.0Pb powder produced by the atomizing method and 55 parts by mass of Al powder produced by the atomizing method were used.

Example 5
A paste was prepared and evaluated in the same manner as in Example 1 except that 45 parts by mass of Al-6.0Sb powder produced by the atomizing method and 55 parts by mass of Al powder produced by the atomizing method were used.

Example 6
A paste was prepared and evaluated in the same manner as in Example 1 except that 45 parts by mass of Al-25.0In powder produced by the atomizing method and 55 parts by mass of Al powder produced by the atomizing method were used.

Example 7
A paste was prepared and evaluated in the same manner as in Example 1 except that 45 parts by mass of Al-10.0Ni powder produced by the atomizing method and 55 parts by mass of Al powder produced by the atomizing method were used.

Comparative Example 1
A paste was prepared and evaluated in the same manner as in Example 1 except that 40 parts by mass of Al-28.0Si powder produced by the atomizing method and 60 parts by mass of Al powder produced by the atomizing method were used.

Comparative Example 2
A paste was prepared and evaluated in the same manner as in Example 1 except that 40 parts by mass of Al-10.0 Mg powder produced by the atomizing method and 60 parts by mass of Al powder produced by the atomizing method were used.

Comparative Example 3
A paste was prepared and evaluated in the same manner as in Example 1 except that 40 parts by mass of Al-15.0Ge powder produced by the atomizing method and 60 parts by mass of Al powder produced by the atomizing method were used.

Comparative Example 4
A paste was prepared and evaluated in the same manner as in Example 1 except that 100 parts by mass of Al powder produced by the atomizing method was used.

Comparative Example 5
A paste was prepared and evaluated in the same manner as in Example 1 except that 20 parts by mass of Al-20.0Si powder produced by the atomizing method and 80 parts by mass of Al powder produced by the atomizing method were used.

Comparative Example 6
A paste was prepared and evaluated in the same manner as in Example 1 except that 30 parts by mass of Al-20.0Si powder produced by the atomizing method and 70 parts by mass of Al powder produced by the atomizing method were used.

表１の結果から明らかな通り、本発明の太陽電池用ペースト組成物を結晶系太陽電池セルに用いることによって、焼成後の電極層の表面でのＳａｎｄｙの発生を防止又は抑制できるとともに、電極層の高い密着性が得られる。

As is clear from the results in Table 1, by using the paste composition for solar cells of the present invention in a crystalline solar cell, it is possible to prevent or suppress the generation of Sandy on the surface of the electrode layer after firing, and the electrode layer. High adhesion can be obtained.

1: Silicon semiconductor substrate 2: n-type impurity layer 3: Antireflection film (passivation film)
4: Grid electrode 5: Electrode layer 6: Alloy layer 7: p + layer 8: Backside electrode 9: Contact hole 10: Paste composition

Claims (3)

A paste composition for a solar cell containing glass powder, an organic vehicle and a conductive material.
(1) The conductive material contains 40% by mass or more of Al—X alloy powder having a melting point of more than 660 ° C and less than 800 ° C specified by differential scanning calorimetry.
(2) The element X in the Al—X alloy powder is at least one selected from the group consisting of silicon, barium, bismuth, calcium, germanium, indium, lanthanum, nickel, lead , strontium , tellurium and yttrium.
A paste composition for a solar cell, characterized in that. The paste composition for a solar cell according to claim 1, wherein the conductive material further contains Al powder in addition to the Al—X alloy powder. The paste composition for a solar cell according to claim 1 or 2, wherein the element X in the Al—X alloy powder is silicon.

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