JP2012238754A - Conductive composition for forming solar cell collector electrode and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive composition for forming a solar cell collector electrode capable of obtaining a solar cell that exhibits a high fill factor over a wide calcination temperature range (700-800°C), and to provide a solar cell using the same.SOLUTION: A conductive composition for forming a collector electrode of a solar cell forms a collector electrode of a solar cell having a surface electrode on the light receiving surface side, an antireflection film, a semiconductor substrate and a back electrode. The conductive composition contains conductive particles (A), a fatty acid silver salt (B), an acetylacetone metal complex (C), glass frit (D) and a solvent (E). A content of the fatty acid silver salt (B) is 1-30 pts.mass based on 100 pts.mass of the conductive particles (A), and a content of the acetylacetone metal complex (C) is 0.1-10 pts.mass based on 100 pts.mass of the conductive particles (A), and the mass ratio (B/C) of the content of the fatty acid silver salt (B) to the content of the acetylacetone metal complex (C) is 1 or more.

Description

  The present invention relates to a conductive composition for forming a solar battery collecting electrode and a solar battery cell.

  Solar cells that convert light energy such as sunlight into electrical energy have been actively developed in various structures and configurations as interest in global environmental issues increases. Among them, solar cells using a semiconductor substrate such as silicon are most commonly used due to advantages such as conversion efficiency and manufacturing cost.

  As a material for forming an electrode of such a solar cell, for example, Patent Document 1 includes “silver powder (A), silver oxide (B), and an organic solvent (D), and the silver powder (A ) Is a silver simple substance contained in the composition and a conductive composition that is 50% by mass or more in the silver compound ([Claim 1]), an embodiment containing a silver carboxylate as an optional component, Embodiments containing other additives such as glass frit are described ([Claim 2] [0030] [0031] [0032] etc.).

  Further, Patent Document 2 discloses that “a conductive material for a solar cell electrode comprising an organic binder, a solvent, conductive particles, a glass frit, and a compound containing Al, Ga, In, or Tl. ”Is described ([Claim 1]), an organometallic compound or the like is described as the compound ([Claim 3]), and an acetylacetone complex or the like is described as the organometallic compound ( [Claim 4]).

JP 2011-35062 A JP 2007-294678 A

  However, when this inventor examined the electrically conductive composition described in patent document 1, and the electrically conductive paste described in patent document 2, depending on the calcination temperature which forms an electrode, the curve of the photovoltaic cell obtained is obtained. It has become clear that the factor (FF) may be low.

  If the characteristics change depending on the firing temperature in this way, depending on the degree, the yield may decrease when the solar cells are manufactured, or the firing temperature may be controlled with high accuracy in order to improve the yield. In some cases, problems such as unavoidable have occurred.

  Therefore, the present invention provides a conductive composition for forming a solar battery collecting electrode and a solar battery cell using the same, which can obtain a solar battery cell exhibiting a high fill factor in a wide firing temperature range (700 to 800 ° C.). The issue is to provide.

  As a result of intensive studies to solve the above problems, the present inventor formed an electrode using a conductive composition containing a fatty acid silver salt and an acetylacetone complex at a specific mass ratio, thereby achieving a wide firing temperature range ( The present inventors have found that a solar cell exhibiting a high fill factor at 700 to 800 ° C. can be obtained, and the present invention has been completed. That is, the present invention provides the following (1) to (8).

  (1) Containing conductive particles (A), fatty acid silver salt (B), acetylacetone metal complex (C), glass frit (D) and solvent (E), the content of fatty acid silver salt (B) and the above The electrically conductive composition for solar cell current collection electrode formation whose mass ratio (B / C) with content of an acetylacetone metal complex (C) is 1 or more.

  (2) The conductive composition for forming a solar cell collecting electrode according to (1), wherein the mass ratio (B / C) is 2 or more.

  (3) The fatty acid silver salt (B2), wherein the fatty acid silver salt (B) has at least one fatty acid silver salt (B1), carboxy silver base (—COOAg) and hydroxyl group (—OH) each having 18 or less carbon atoms. And (1) or (1) above, which is a fatty acid silver salt selected from the group consisting of a polycarboxylic acid silver salt (B3) having two or more carboxy silver bases (—COOAg) without having a hydroxyl group (—OH) The electrically conductive composition for solar cell current collection electrode formation as described in (2).

  (4) The acetylacetone metal complex (C) is a complex of a metal species selected from the group consisting of indium, nickel, copper, titanium, zinc, and tin, according to any one of (1) to (3) above A conductive composition for forming a solar cell collecting electrode.

  (5) The sun according to any one of (1) to (4), wherein the content of the fatty acid silver salt (B) is 1 to 30 parts by mass with respect to 100 parts by mass of the conductive particles (A). A conductive composition for forming a battery current collecting electrode.

  (6) The content of the acetylacetone metal complex (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the conductive particles (A), according to any one of the above (1) to (5). A conductive composition for forming a solar cell collector electrode.

  (7) A light-receiving surface side surface electrode, an antireflection film, a semiconductor substrate, and a back surface electrode are provided, and at least the surface electrode is for forming a solar cell collecting electrode according to any one of (1) to (6) above A solar battery cell formed using a conductive composition.

  (8) A solar cell module in which the solar cells according to (7) are wired in series using an interconnector.

  As shown below, according to the present invention, a conductive composition for forming a solar battery collecting electrode capable of obtaining a solar battery cell exhibiting a high fill factor in a wide firing temperature range (700 to 800 ° C.), and The used solar battery cell can be provided.

FIG. 1 is a cross-sectional view showing an example of a preferred embodiment of a solar battery cell.

[Conductive composition for forming solar cell collector electrode]
The conductive composition for forming a solar cell collector electrode of the present invention (hereinafter abbreviated as “the conductive composition of the present invention”) is composed of conductive particles (A), fatty acid silver salt (B), acetylacetone metal complex ( C), glass frit (D) and solvent (E), and the mass ratio (B / C) of the content of the fatty acid silver salt (B) and the content of the acetylacetone metal complex (C) is 1 or more It is an electroconductive composition for solar cell current collection electrode formation which is.
Hereinafter, the conductive particles (A), the fatty acid silver salt (B), the acetylacetone metal complex (C), the glass frit (D), the solvent (E), and other components that may be optionally contained are described in detail. .

<Conductive particles (A)>
The conductive particles (A) used in the conductive composition of the present invention are not particularly limited, and for example, a metal material having an electrical resistivity of 20 × 10 ⁻⁶ Ω · cm or less can be used.
Specific examples of the metal material include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni), and the like. One species may be used alone, or two or more species may be used in combination.
Of these, gold, silver, and copper are preferred, and silver is preferable because an electrode with a small volume resistivity can be formed and a solar cell with higher photoelectric conversion efficiency can be produced. Is more preferable.

In the present invention, it is preferable to use a metal powder having an average particle size of 0.5 to 10 μm for the conductive particles (A) because of good printability.
Among the above metal powders, it is more preferable to use a spherical silver powder because an electrode having a smaller volume resistivity can be formed and a solar cell having higher photoelectric conversion efficiency can be produced.
Here, an average particle diameter means the average value of the particle diameter of a metal powder, and means the 50% volume cumulative diameter (D50) measured using the laser diffraction type particle size distribution measuring apparatus. In addition, when the cross-section of the metal powder is an ellipse, the particle diameter used as the basis for calculating the average value is an average value obtained by dividing the total value of the major axis and the minor axis by 2, and in the case of a perfect circle, Refers to the diameter.
The spherical shape refers to the shape of particles having a major axis / minor axis ratio of 2 or less.

  Further, in the present invention, the average particle diameter of the conductive particles (A) is preferably 0.7 to 5 μm because the printing property is better, and the sintering speed is appropriate and the workability is improved. From the reason of being excellent, it is more preferable that it is 1-3 micrometers.

  Furthermore, in this invention, a commercial item can be used as such electroconductive particle (A), As the specific example, AgC-102 (shape: spherical shape, average particle diameter: 1.5 micrometers, Fukuda metal foil) Powder Industry Co., Ltd.), AgC-103 (shape: spherical, average particle size: 1.5 μm, Fukuda Metal Foil Powder Industry Co., Ltd.), AG4-8F (shape: spherical, average particle size: 2.2 μm, DOWA Electronics Co., Ltd.) Manufactured), AG2-1C (shape: spherical, average particle size: 1.0 μm, manufactured by DOWA Electronics), AG3-11F (shape: spherical, average particle size: 1.4 μm, manufactured by DOWA Electronics), SPN5J (shape) : Spherical, average particle size: 1.2 μm, manufactured by Mitsui Kinzoku), EHD (shape: spherical, average particle size: 0.5 μm, manufactured by Mitsui Kinzoku), AgC-2011 (shaped: flake, average particle) : 2 to 10 [mu] m, manufactured by Fukuda Metal Foil & Powder Co., Ltd.), AgC-301K (shape: flaky, average particle size: 3 to 10 [mu] m, Fukuda metal foil Powder Co., Ltd.) and the like.

<Fatty acid silver salt (B)>
The fatty acid silver salt (B) used in the conductive composition of the present invention is not particularly limited as long as it is a silver salt of an organic carboxylic acid (fatty acid), and for example, [0063] to [0068] of JP-A-2008-198595. ] Fatty acid metal salts described in paragraph (particularly tertiary fatty acid silver salts), fatty acid silver salts described in paragraph [0030] of Japanese Patent No. 4482930, and [0029] to [0045] of JP 2010-92684 A. ] The fatty acid silver salt having one or more hydroxyl groups described in the paragraph, the secondary fatty acid silver salt described in the paragraphs [0046] to [0056] of the publication, and [0022] to [0022] of JP 2011-35062 A The silver carboxylate described in [0026] can be used.
Among these, since the printability is improved and the temperature dependency of the fill factor can be further reduced, the fatty acid silver salt (B1) having 18 or less carbon atoms, carboxy silver base (—COOAg) and hydroxyl group (—OH) Selected from the group consisting of a fatty acid silver salt (B2) having 1 or more of each and a polycarboxylic acid silver salt (B3) having 2 or more carboxy silver bases (—COOAg) without having a hydroxyl group (—OH) Preferably, at least one fatty acid silver salt is used.
Among them, the polycarboxylic acid silver salt (B3) having 3 or more carboxy silver bases (—COOAg) without having a hydroxyl group (—OH) is used because the temperature dependence of the fill factor can be further reduced. Particularly preferred.

Here, as said fatty-acid silver salt (B2), the compound represented by either of following formula (I)-(III) is mentioned, for example.

(In formula (I), n represents an integer of 0 to 2, R ¹ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ² represents an alkylene group having 1 to 6 carbon atoms. When it is 0 or 1, the plurality of R ² may be the same or different, and when n is 2, the plurality of R ¹ may be the same or different.
In formula (II), R ¹ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and a plurality of R ¹ may be the same or different.
In formula (III), R ¹ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ³ represents an alkylene group having 1 to 6 carbon atoms. The plurality of R ¹ may be the same or different. )

Examples of the polycarboxylic acid silver salt (B3) include compounds represented by the following formula (IV).

(In Formula (IV), m represents an integer of 2 to 6, R ⁴ represents an m-valent saturated aliphatic hydrocarbon group having 1 to 24 carbon atoms, and an m-valent unsaturated fat having 2 to 12 carbon atoms. family hydrocarbon group, m-valent alicyclic hydrocarbon group having 3 to 12 carbon atoms, or, when the carbon number of the .R ⁴ representing the m-valent aromatic hydrocarbon group having 6 to 12 carbon atoms and p, m ≦ 2p + 2.)

Specific examples of the fatty acid silver salt (B1) include 2-methylpropanoic acid silver salt (also known as isobutyric acid silver salt), 2-methylbutanoic acid silver salt, and the like.
Specific examples of the fatty acid silver salt (B2) include 2-hydroxyisobutyric acid silver salt and 2,2-bis (hydroxymethyl) -n-butyric acid silver salt.
Specific examples of the polycarboxylic acid silver salt (B3) include 1,3,5-pentanetricarboxylic acid silver salt and 1,2,3,4-butanetetracarboxylic acid silver salt. Is done.

  In the present invention, the content of the fatty acid silver salt (B) is 1 to 30 parts by mass with respect to 100 parts by mass of the conductive particles (A) because the printability is better. Preferably, it is 5-25 mass parts.

<Acetylacetone metal complex (C)>
The acetylacetone metal complex (C) used in the conductive composition of the present invention is not particularly limited as long as it is a complex of acetylacetone and a metal.
By forming the electrode of the solar battery cell using the conductive composition of the present invention containing the acetylacetone metal complex (C) at a specific mass ratio, a high fill factor in a wide firing temperature range (700 to 800 ° C.) Can be obtained.
Although this is not clear in detail, by adding the acetylacetone metal complex (C), dispersibility of the fatty acid silver salt (B) and the solvent (E) described later is improved, and will be described later. It is thought that the temperature range where the glass frit (D) softens (decomposes) widens, the fire-through progresses moderately over a wide firing temperature range (700 to 800 ° C.), and a good contact is formed with the silicon substrate. It is done.

In the present invention, the acetylacetone metal complex (C) is a complex of a metal species selected from the group consisting of indium, nickel, copper, titanium, zinc and tin because the temperature dependence of the fill factor can be further reduced. And more preferably an indium complex.
In the present invention, the acetylacetone metal complex (C) may be a single acetylacetone metal complex or a combination of two or more acetylacetone metal complexes.

  In the present invention, the content of the acetylacetone metal complex (C) is 0.1 to 10 with respect to 100 parts by mass of the conductive particles (A) because the temperature dependence of the fill factor can be further reduced. It is preferable that it is a mass part, and it is more preferable that it is 1-5 mass parts.

In the present invention, the mass ratio (B / C) between the content of the fatty acid silver salt (B) and the content of the acetylacetone metal complex (C) is 1 or more, and the temperature dependence of the fill factor is From the reason that it can be further reduced, it is preferably 2 or more.
Moreover, the mass ratio is preferably 30 or less, and more preferably 25 or less, because the paste formed by blending these components is finished to a viscosity that can be easily printed with an appropriate viscosity.

<Glass frit (D)>
The glass frit (D) used in the conductive composition of the present invention is not particularly limited, and it is preferable to use one having a softening temperature of 300 ° C. or higher and a firing temperature (heat treatment temperature) or lower.
Specific examples of the glass frit (D) include a borosilicate glass frit having a softening temperature of 300 to 800 ° C.
The shape of the glass frit (D) is not particularly limited, and may be spherical or crushed powder. The average particle size of the spherical glass frit is preferably 0.1 to 20 μm, and more preferably 1 to 10 μm. Furthermore, it is preferable to use a glass frit having a sharp particle size distribution from which particles of 15 μm or more are removed. Here, the average particle diameter means an average value of the particle diameters, and means a 50% volume cumulative diameter (D50) measured using a laser diffraction particle size distribution measuring apparatus.
The content of the glass frit (D) is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the conductive particles (A).

<Solvent (E)>
The solvent (E) used in the conductive composition of the present invention is not particularly limited as long as it can apply the conductive composition of the present invention onto a substrate.
Specific examples of the solvent (E) include butyl carbitol, butyl carbitol acetate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, diethylene glycol dibutyl ether, methyl ethyl ketone, isophorone, (alpha)-terpineol etc. are mentioned, These may be used individually by 1 type, or may use 2 or more types together.
Moreover, it is preferable that it is 2-20 mass parts with respect to 100 mass parts of said electroconductive particle (A), and, as for content of the said solvent (E), it is more preferable that it is 5-15 mass parts.

<Resin binder>
The conductive composition of the present invention may contain a resin binder as necessary from the viewpoint of printability.
The resin binder is obtained by dissolving a resin having a binder function in a solvent.
Specific examples of the resin include ethyl cellulose resin, nitrocellulose resin, alkyd resin, acrylic resin, styrene resin, phenol resin and the like, and these may be used alone or in combination of two or more. May be. Among these, it is preferable to use ethyl cellulose resin from the viewpoint of thermal decomposability.
Specific examples of the solvent include α-terpineol, butyl carbitol, butyl carbitol acetate, diacetone alcohol, methyl isobutyl ketone, and the like. You may use the above together. In the present invention, the solvent may be a part of the solvent (E) described above.

<Metal oxide>
In order to improve the photoelectric conversion efficiency, the conductive composition of the present invention may contain a metal oxide. Specific examples of the metal oxide include zinc oxide, silicon oxide, cerium oxide, bismuth oxide, tin oxide, and ABO ₃ (wherein A is selected from the group consisting of Ba, Ca and Sr). B represents at least one element selected from the group consisting of Ti, Zr and Hf and represents Ti.) And B is selected from the group consisting of perovskites And at least one oxide.
In the present invention, since the thixotropy of the conductive composition of the present invention is improved and the aspect ratio can be increased, the content of silver oxide that can correspond to the metal oxide is determined by the solvent ( E) It is preferably 5 parts by mass or less with respect to 100 parts by mass, more preferably 1 part by mass or less, and most preferably an embodiment containing substantially no silver oxide.

  The manufacturing method of the electroconductive composition of this invention is not specifically limited, The said electroconductive particle (A), the said fatty acid silver salt (B), the said acetylacetone metal complex (C), the said glass frit (D), and the said solvent ( E) and a resin binder and a metal oxide which may be optionally contained are mixed by a roll, a kneader, an extruder, a universal agitator or the like.

[Solar cells]
The solar cell of the present invention comprises a surface electrode on the light-receiving surface side, an antireflection film, a semiconductor substrate, and a back electrode, and at least the surface electrode is formed by using the above-described conductive composition of the present invention. It is a battery cell.
In addition, since the conductive composition of the present invention described above can also be applied to the formation of the back electrode of an all back electrode type (so-called back contact type) solar battery cell, it is also applicable to an all back electrode type solar cell. can do.
Below, an example of the suitable embodiment of the photovoltaic cell of this invention is demonstrated using FIG.

As shown in FIG. 1, a solar cell 10 of the present invention includes a surface electrode 1 on the light receiving surface side, an antireflection film 2, a pn junction silicon substrate 4 in which a p layer 5 and an n layer 3 are joined (hereinafter referred to as these). Are also referred to as “crystalline silicon substrate 7”) and back electrode 6.
Moreover, as shown in FIG. 1, it is preferable that the photovoltaic cell 10 of this invention forms a pyramid-like texture by, for example, etching the wafer surface in order to reduce reflectivity.

<Front electrode / Back electrode>
The surface electrode and the back electrode provided in the solar battery cell of the present invention are arranged (pitch), shape, height, width, etc. of the electrode as long as at least the surface electrode is formed using the conductive composition of the present invention. Is not particularly limited.
Here, a plurality of surface electrodes are usually provided, but in the present invention, only a part of the plurality of surface electrodes may be formed of the conductive composition of the present invention.

<Antireflection film>
The antireflection film included in the solar battery cell of the present invention is a film (thickness: about 0.05 to 0.1 μm) formed on a portion of the light receiving surface where the surface electrode is not formed. It is composed of an oxide film, a silicon nitride film, a titanium oxide film, a laminated film of these, and the like.

<Crystal silicon substrate>
The crystalline silicon substrate included in the solar battery cell of the present invention is not particularly limited, and a known silicon substrate (plate thickness: about 100 to 450 μm) for forming a solar battery can be used. Any polycrystalline silicon substrate may be used.

The crystalline silicon substrate has a pn junction, which means that a second conductivity type light-receiving surface impurity diffusion region is formed on the surface side of the first conductivity type semiconductor substrate. When the first conductivity type is n-type, the second conductivity type is p-type. When the first conductivity type is p-type, the second conductivity type is n-type.
Here, examples of the impurity imparting p-type include boron and aluminum, and examples of the impurity imparting n-type include phosphorus and arsenic.

  The solar battery cell of the present invention exhibits a high fill factor in a wide firing temperature range (700 to 800 ° C.) because at least the surface electrode is formed of the conductive composition of the present invention.

Although the manufacturing method of the photovoltaic cell of the present invention is not particularly limited, an antireflection film forming step of forming an antireflection film on a crystalline silicon substrate, and applying the conductive composition of the present invention on the antireflection film. There is a method including a wiring forming step for forming a wiring and a heat treatment step for forming an electrode by heat-treating the obtained wiring.
Hereinafter, the antireflection film forming step, the wiring forming step, and the heat treatment step will be described in detail.

<Antireflection film formation process>
The antireflection film forming step is a step of forming an antireflection film on the crystalline silicon substrate.
Here, the formation method of the antireflection film is not particularly limited, and can be formed by a known method such as a plasma CVD method.

<Wiring formation process>
The wiring formation step is a step of forming a wiring by applying the conductive composition of the present invention on a silicon substrate.
Here, specific examples of the coating method include inkjet, screen printing, gravure printing, offset printing, letterpress printing, and the like.

<Heat treatment process>
The heat treatment step is a step of obtaining a conductive wiring (electrode) by heat-treating the wiring obtained in the wiring forming step.
Here, although the said heat processing is not specifically limited, It is preferable that it is the process heated (baking) for several seconds-several tens of minutes at the temperature of 700-800 degreeC. When the temperature and time are within this range, the wiring applied on the antireflection film is fire-through (fired through), whereby an electrode in contact with the crystalline silicon substrate can be formed.
In addition, since the wiring obtained by the wiring formation process mentioned above can obtain an electrode even by irradiation of ultraviolet rays or infrared rays, the heat treatment step in the present invention may be performed by irradiation of ultraviolet rays or infrared rays.

[Solar cell module]
The solar cell module of the present invention is a solar cell module in which the solar cells of the present invention are wired in series using an interconnector.
Here, as the interconnector, a connector used in a conventionally known solar cell module can be used. Specifically, for example, a copper ribbon coated with solder or a conductive adhesive is preferably used. it can.

  Hereinafter, the conductive composition of the present invention will be described in detail using examples. However, the present invention is not limited to this.

(Examples 1-8, Comparative Examples 1-4)
<Preparation of conductive composition>
To the ball mill, conductive particles shown in Table 1 below were added so as to have the composition ratio (mass ratio) shown in Table 1 below, and these were mixed to prepare a conductive composition.

<Production of solar cells>
A single crystal silicon wafer subjected to an alkali texture treatment was prepared, and an aluminum paste was applied to the back surface (the surface opposite to the light receiving surface) by screen printing, followed by drying at 150 ° C. for 15 minutes.
Next, a silicon nitride film as an antireflection film was formed on the surface (light-receiving surface) by a plasma CVD method, and each conductive composition thus prepared was applied by screen printing to form a wiring pattern.
Thereafter, a sample of a solar battery cell in which conductive wiring (electrode) was formed by firing for 30 seconds under two conditions of a peak temperature of 720 ° C. and 780 ° C. in an infrared firing furnace was produced.

<Curve factor>
About the sample of each produced photovoltaic cell, the fill factor was evaluated using a cell tester (manufactured by Yamashita Denso Co., Ltd.). The results are shown in Table 1 below.

The following were used for each component in Table 1.
Silver powder: AgC-103 (shape: spherical, average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Industry)

  Silver salt of isobutyrate: First, 50 g of silver oxide (manufactured by Toyo Kagaku Kogyo Co., Ltd.), 38 g of isobutyric acid (manufactured by Kanto Chemical Co., Ltd.) and 300 g of methyl ethyl ketone (MEK) are put into a ball mill and reacted by stirring at room temperature for 24 hours. It was. Subsequently, MEK was removed by suction filtration, and the obtained powder was dried to prepare white silver isobutyrate.

  Silver salt of 1,3,5-pentanetricarboxylic acid: First, 50 g of silver oxide (manufactured by Toyo Chemical Co., Ltd.), 30 g of 1,3,5-pentanetricarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 300 g of methyl ethyl ketone (MEK) are ball milled. And reacted by stirring at room temperature for 24 hours. Next, MEK was removed by suction filtration, and the obtained powder was dried to prepare white 1,3,5-pentanetricarboxylic acid silver salt.

_{· In (C 5 H 7 O} 2) 3: Toner Shem indium (Nihon Kagaku Sangyo Co., Ltd.)
_{· Ni (C 5 H 7 O} 2) 3: Toner Shem Nickel (Nihon Kagaku Sangyo Co., Ltd.)
_{· Cu (C 5 H 7 O} 2) 3: Nasemu copper (Nihon Kagaku Sangyo Co., Ltd.)
_{· Ti (C 5 H 7 O} 2) 3: Nasemuchitan (Nihon Kagaku Sangyo Co., Ltd.)
_{· Zn (C 5 H 7 O} 2) 3: Nasemu Zinc (Nihon Kagaku Sangyo Co., Ltd.)

Glass frit: Pb glass frit Solvent: α-terpineol Organic binder: Ethyl cellulose resin Zinc oxide: ZnO (Taika)

From the results shown in Table 1, when a conductive composition containing a fatty acid silver salt (B) and an acetylacetone metal complex (C) was used (Examples 1 to 8), the sun having an electrode fired at 720 ° C. The curve factor of the battery cell was almost the same as the curve factor of the solar battery cell having an electrode fired at 800 ° C., and it was found that the curve factor was high in a wide firing temperature range (700 to 800 ° C.).
On the other hand, when a conductive composition not containing at least one of fatty acid silver salt (B) and acetylacetone metal complex (C) is used (Comparative Examples 1 to 3), a solar battery cell having an electrode fired at 720 ° C. The curve factor was found to be lower than the curve factor of solar cells having electrodes fired at 800 ° C. When a conductive composition containing a fatty acid silver salt (B) and an acetylacetone metal complex (C) but having a mass ratio (B / C) of less than 1 (Comparative Example 4), Although the temperature dependence was small, the absolute value of the fill factor was at a low level compared to the examples of the present invention.

DESCRIPTION OF SYMBOLS 1 Front electrode 2 Antireflection film 3 N layer 4 pn junction silicon substrate 5 P layer 6 Back electrode 7 Crystalline silicon substrate 10 Solar cell

As a result of intensive studies to solve the above problems, the present inventor has formed a wide range by forming an electrode using a conductive composition containing a predetermined amount of a fatty acid silver salt and an acetylacetone metal complex in a specific mass ratio. The present inventors have found that a solar cell exhibiting a high fill factor in a firing temperature range (700 to 800 ° C.) can be obtained, and the present invention has been completed. That is, the present invention provides the following (1) to ( 6 ).

(1) A conductive composition for forming a solar battery collector electrode, which forms a collector electrode of a solar battery cell comprising a surface electrode on the light-receiving surface side, an antireflection film, a semiconductor substrate and a back electrode, wherein the conductive particles (A), fatty acid silver salt (B), acetylacetone metal complex (C), glass frit (D) and solvent (E), and the content of the fatty acid silver salt (B) is the above-mentioned conductive particles (A ) 1 to 30 parts by mass with respect to 100 parts by mass, and the content of the acetylacetone metal complex (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the conductive particles (A). The electrically conductive composition for solar cell current collection electrode formation whose mass ratio (B / C) of content of the said fatty-acid silver salt (B) and content of the said acetylacetone metal complex (C) is 1 or more.

( 5 ) A surface electrode on the light-receiving surface side, an antireflection film, a semiconductor substrate, and a back electrode are provided, and at least the surface electrode is for forming a solar cell collecting electrode according to any one of (1) to ( 4 ) above A solar battery cell formed using a conductive composition.

( 6 ) The solar cell module which wired the solar cell as described in said ( 5 ) in series using the interconnector.

[Conductive composition for forming solar cell collector electrode]
The conductive composition for forming a solar cell collector electrode of the present invention (hereinafter abbreviated as “the conductive composition of the present invention”) includes a surface electrode on the light-receiving surface side, an antireflection film, a semiconductor substrate, and a back electrode. A conductive composition for forming a collector electrode of a solar cell for forming a collector electrode of a solar cell, comprising conductive particles (A), fatty acid silver salt (B), acetylacetone metal complex (C), glass frit ( D) and a solvent (E), the content of the fatty acid silver salt (B) is 1 to 30 parts by mass with respect to 100 parts by mass of the conductive particles (A), and the acetylacetone metal complex (C ) Is 0.1 to 10 parts by mass with respect to 100 parts by mass of the conductive particles (A ), the content of the fatty acid silver salt (B) and the content of the acetylacetone metal complex (C). Solar cell collection whose mass ratio (B / C) is 1 or more An electrode formation conductive composition.
Hereinafter, the conductive particles (A), the fatty acid silver salt (B), the acetylacetone metal complex (C), the glass frit (D), the solvent (E), and other components that may be optionally contained are described in detail. .

In the present invention, the content of the fatty acid silver salt (B) is, for reasons that printability becomes better, with respect to the conductive particles (A) 100 parts by mass of, Ri 1 to 30 parts by mass der, it is good preferable 5 to 25 parts by weight.

In the present invention, the content of the acetylacetone metal complex (C) is 0.1 to 10 with respect to 100 parts by mass of the conductive particles (A) because the temperature dependence of the fill factor can be further reduced. parts by der is, it is favorable preferable 1 to 5 parts by weight.

Claims (8)

  Containing conductive particles (A), fatty acid silver salt (B), acetylacetone metal complex (C), glass frit (D) and solvent (E), content of fatty acid silver salt (B) and acetylacetone metal complex The electrically conductive composition for solar cell current collection electrode formation whose mass ratio (B / C) with content of (C) is 1 or more.   The conductive composition for forming a solar cell collecting electrode according to claim 1, wherein the mass ratio (B / C) is 2 or more.   The fatty acid silver salt (B) is a fatty acid silver salt (B2) having 18 or less carbon atoms, a fatty acid silver salt (B2) having at least one carboxy silver base (—COOAg) and one hydroxyl group (—OH), and The fatty acid silver salt selected from the group consisting of a polycarboxylic acid silver salt (B3) having two or more carboxy silver bases (-COOAg) without having a hydroxyl group (-OH). A conductive composition for forming a solar cell collecting electrode.   The solar cell current collecting electrode formation according to any one of claims 1 to 3, wherein the acetylacetone metal complex (C) is a complex of a metal species selected from the group consisting of indium, nickel, copper, titanium, zinc and tin. Conductive composition.   Content of the said fatty-acid silver salt (B) is 1-30 mass parts with respect to 100 mass parts of said electroconductive particle (A), For solar cell current collection electrode formation in any one of Claims 1-4 Conductive composition.   Content of the said acetylacetone metal complex (C) is 0.1-10 mass parts with respect to 100 mass parts of said electroconductive particle (A), The solar cell current collection electrode in any one of Claims 1-5 A conductive composition for formation.   A surface electrode on the light-receiving surface side, an antireflection film, a semiconductor substrate, and a back electrode are provided, and at least the surface electrode uses the conductive composition for forming a solar cell collector electrode according to any one of claims 1 to 6. A solar battery cell formed.   The solar cell module which wired the solar cell of Claim 7 in series using the interconnector.