JP5321723B1 - Conductive composition and solar battery cell - Google Patents

Abstract

A conductive composition capable of forming an electrode having excellent adhesion to a transparent conductive layer and the like and having a low contact resistance while maintaining a low volume resistivity, and a solar battery cell using the same as a collecting electrode Offer.
A conductive composition containing conductive particles (A) and an organopolysiloxane (B) having a phenyl group and / or a vinyl group. Furthermore, curable resin (C) other than the said organopolysiloxane (B) is contained. The curable resin (C) is an epoxy resin. The conductive particles (A) are silver particles and / or copper particles.
[Selection figure] None

Description

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

  Conventionally, conductive particles such as silver particles and binders made of thermoplastic resin (for example, acrylic resin, vinyl acetate resin, etc.) or thermosetting resin (for example, epoxy resin, silicone resin, unsaturated polyester resin, etc.), organic A conductive paste (conductive composition) obtained by adding and mixing a solvent, a curing agent, a catalyst, etc. is printed on a substrate (for example, a silicon substrate, an epoxy resin substrate, etc.) so as to have a predetermined pattern. A method of manufacturing a solar battery cell or a printed wiring board by forming electrodes and wirings by heating is known.

As such a conductive composition, for example, Patent Document 1 describes “a conductive paste composition for low-temperature firing characterized by containing silver powder, a polyimide silicone resin, and an organic solvent” ( [Claim 1]).
Patent Document 2 describes “a conductive paste composition comprising a silicone resin, a conductive powder, a thermosetting component, a curing agent, and a solvent.” ([Claim 1]), it is described that a specific amount of a predetermined epoxy resin or the like is blended as a thermosetting component ([Claim 3]).

  Furthermore, in Patent Document 3, the applicant of the present invention said that the conductive composition containing “silver powder (A), fatty acid silver salt (B), resin (C), and solvent (D), The fatty acid silver salt (B) is a compound having one carboxy silver base (—COOAg) and one or two hydroxyl groups (—OH), and the content of silver oxide is the solvent (D). The electrically conductive composition is 10 parts by mass or less with respect to 100 parts by mass "([Claim 1]), and the resin (C) includes" from epoxy resin, polyester resin, silicone resin and urethane resin. " "At least one selected from the group consisting of" is described ([Claim 6]).

JP 2007-184153 A JP 2007-224191 A JP 2012-023095 A

  However, when this inventor examined the conductive composition which mix | blended the silicone resin with reference to patent documents 1-3, the volume resistivity of the electrode and wiring (henceforth an electrode etc.) formed becomes low. However, when an electrode or the like is formed on a transparent conductive layer (for example, a transparent conductive oxide layer (TCO)) on a substrate (for example, a silicon wafer), adhesion may be inferior and contact resistance may increase. Became clear.

  Therefore, the present invention uses a conductive composition capable of forming an electrode having excellent adhesion to a transparent conductive layer or the like and having a low contact resistance while maintaining a low volume resistivity, and the current collector electrode. It is an object to provide a solar battery cell.

As a result of intensive studies to solve the above problems, the present inventors have formulated organopolysiloxane having a phenyl group and / or a vinyl group, thereby maintaining a low volume resistivity and adhesion to a transparent conductive layer or the like. The present invention has been completed by finding that an electrode having excellent properties and low contact resistance can be formed.
That is, the present inventors have found that the above problem can be solved by the following configuration.

(1) It contains conductive particles (A) and an organopolysiloxane (B) having a phenyl group and / or a vinyl group, and the organopolysiloxane (B) has the formula (S-3) or ( S-4), a curable resin (C) other than the organopolysiloxane (B), the curable resin (C) being an epoxy resin, The electroconductive composition whose content of polysiloxane (B) is 0.1-10 mass parts with respect to 100 mass parts of said electroconductive particle (A) .
(2 ) The conductive composition according to (1 ), wherein the conductive particles (A) are silver particles and / or copper particles.
( 3 ) The conductive composition according to (1) or (2) , wherein the organopolysiloxane (B) further has an epoxy group .

( 4 ) A solar battery cell using the conductive composition according to any one of (1) to ( 3 ) as a collecting electrode.
( 5 ) The solar battery cell according to ( 4 ), wherein a transparent conductive layer is provided as a base layer for the collecting electrode.
( 6 ) A solar cell module using the solar cell according to ( 4 ) or ( 5 ) above.

As shown below, according to the present invention, a conductive composition capable of forming an electrode having excellent adhesion to a transparent conductive layer or the like and having a low contact resistance while maintaining a low volume resistivity, and A solar battery cell used for the current collecting electrode can be provided.
Moreover, if the conductive composition of the present invention is used, even when firing at a low temperature (about 150 to 350 ° C. (especially around 200 ° C.)), the adhesiveness to the transparent conductive layer or the like is maintained while maintaining a low volume resistivity. Since an electrode having excellent and low contact resistance can be formed, the solar battery cell (especially, a second preferred embodiment described later) has an effect of reducing damage caused by heat, which is very useful.
Furthermore, when the conductive composition of the present invention is used, not only a material having high heat resistance such as silicon but also a circuit such as an electronic circuit and an antenna can be easily and quickly formed on a material having low heat resistance such as PET film. It is very useful because it can be made with.

FIG. 1 is a cross-sectional view showing a first preferred embodiment of a solar battery cell. FIG. 2 is a cross-sectional view showing a second preferred embodiment of the solar battery cell.

[Conductive composition]
The conductive composition of the present invention is a conductive composition containing conductive particles (A) and an organopolysiloxane (B) having a phenyl group and / or a vinyl group.
Moreover, it is preferable that the electrically conductive composition of this invention contains curable resin (C) other than the said organopolysiloxane (B) so that it may mention later.

In the present invention, the adhesiveness to the transparent conductive layer and the like is maintained while maintaining a low volume resistivity by blending the organopolysiloxane (B) having a phenyl group and / or a vinyl group together with the conductive particles (A). It becomes an electrically conductive composition which can form an electrode etc. which are excellent in contact resistance and low.
Although this is not clear in detail, the phenyl group or vinyl group, which is the functional group of the organopolysiloxane (B), interacts with the material forming the transparent conductive layer (for example, metal oxide). By acting, it is considered that the transparent conductive layer and the like and the functional group are bonded at the molecular level.
This is the fact that, as shown in a comparative example to be described later, when a silicone resin having no phenyl group or vinyl group is blended, the adhesion of the formed electrode and the like is poor and the contact resistance is also high. It is guessed from.

  Hereinafter, the conductive particles (A), the organopolysiloxane (B), the curable resin (C) which may be optionally contained, and other components will be 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.
Among these, silver and copper are preferable and silver is more preferable because an electrode having a lower volume resistivity can be formed.

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 spherical silver particles and / or copper particles for the reason that an electrode having a lower volume resistivity can be formed. In addition, from a viewpoint of improving oxidation resistance, it is preferable to use copper particles whose surfaces are modified or coated with an organic compound, an inorganic compound, an inorganic oxide, a metal other than copper, or the like.
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.

  In the present invention, the average particle diameter of the conductive particles (A) is preferably 0.7 to 5.0 μm because the printing property is better, and the sintering speed is appropriate and the work is performed. It is more preferable that it is 1.0-3.0 micrometers from the reason which is excellent in property.

Furthermore, in this invention, a commercial item can be used as said electroconductive particle (A).
Specific examples of commercially available silver particles include AG2-1C (average particle size: 1.0 μm, manufactured by DOWA Electronics), AG4-8F (average particle size: 2.2 μm, manufactured by DOWA Electronics), AG3- 11F (average particle size: 1.4 μm, manufactured by DOWA Electronics), AgC-102 (average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.), AgC-103 (average particle size: 1.5 μm, Fukuda) Metal foil powder industry), EHD (average particle size: 0.5 μm, Mitsui Metals), and the like.

<Organopolysiloxane (B)>
The organopolysiloxane (B) used in the conductive composition of the present invention is not particularly limited as long as it is an organopolysiloxane having a phenyl group and / or a vinyl group.
Here, organopolysiloxane refers to a polymer composed of one or more repeating units selected from the group consisting of the following four units.

In the repeating units represented by the above formulas (S-1) to (S-3), each R independently represents a substituted or unsubstituted monovalent hydrocarbon group, and at least one R is Represents a phenyl group or a vinyl group.
Moreover, as R other than a phenyl group or a vinyl group, a C1-C12 alkyl group, a C2-C12 alkenyl group, and a C6-C12 aryl group are mentioned, for example.
Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, and a dodecyl group.
Specific examples of the alkenyl group (excluding the vinyl group) include a butenyl group, a pentenyl group, and an allyl group.
Specific examples of the aryl group (excluding the phenyl group) include a tolyl group, a xylyl group, and a naphthyl group.

  In the present invention, the organopolysiloxane (B) has at least the above formula (S-3) because it has better adhesion to the transparent conductive layer and the like and can form an electrode having a lower contact resistance. It is preferable that it is a thing containing the T unit represented, ie, a silicone resin.

As said silicone resin, the organopolysiloxane represented by following formula (1) is mentioned, for example. In addition, it is preferable that the weight average molecular weight of the organopolysiloxane represented by following formula (1) is about 500-50000.
(RSiO _3/2 ) _a (R ₂ SiO _2/2 ) _b (R ₃ SiO _1/2 ) _c (SiO _4/2 ) _d (XO _1/2 ) _e (1)
{In the formula, R is the same as described in the above formulas (S-1) to (S-3), and X is a hydrogen atom or an alkyl group. A is a positive number, b, c, d and e are each independently 0 or a positive number, b / a is a number from 0 to 10, and c / a is a number from 0 to 0.5. D / (a + b + c + d) is a number from 0 to 0.3, and e / (a + b + c + d) is a number from 0 to 0.4. }

In the above formula (1), examples of the alkyl group as X include those described as R in the above formulas (S-1) to (S-3).
Further, the content (introduction) ratio of the phenyl group or vinyl group in R of the above formula (1) is preferably 10 mol% or more, more preferably 25 mol% or more, based on the total of R, More preferably, it is 50 mol% or more.

In the present invention, the organopolysiloxane (B) preferably further has an epoxy group in addition to the phenyl group and / or the vinyl group, for better adhesion to the transparent conductive layer and the like. .
Here, as an aspect which has an epoxy group, for example, R in the above formula (1) is an epoxyalkyl group such as a 2,3-epoxypropyl group, a 3,4-epoxybutyl group, a 4,5-epoxypentyl group, and the like. Glycidoxyalkyl group such as 2-glycidoxyethyl group, 3-glycidoxypropyl group, 4-glycidoxybutyl group; 2- (3,4-epoxycyclohexyl) ethyl group, 3- (3 Examples include an epoxycyclohexylalkyl group such as a 4-epoxycyclohexyl) propyl group.
As another aspect, as shown in the Example mentioned later, the aspect which introduce | transduces an epoxy group by making the organopolysiloxane which has a phenyl group and / or a vinyl group, and epoxysilane react is mentioned.
Moreover, it is preferable that the content (introduction) ratio of the arbitrary epoxy group in R of said Formula (1) is 0.1 mol% or more and less than 20 mol% with respect to the sum total of R.

In the present invention, the following commercially available products can be used as the organopolysiloxane (B).
217 Flake (weight average molecular weight: 2000, hydroxyl group content: 7% by weight, phenyl group content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.57 , manufactured by Toray Dow Corning ]
TMS217 (weight average molecular weight: 2000, hydroxyl group content: 2% by weight, phenyl group content: 100 mol%, a silicone resin in which the above-mentioned 217 Flakes are end-capped with a trimethylsilyl group, manufactured by Toray Dow Corning)
SH6018 [weight average molecular weight: 2000, hydroxyl group content: 6% by weight, phenyl group content: 70 mol%, propyl group: 30 mol%, average molecular formula: (PhSiO _3/2 ) _0.7 (ProSiO _3/2 ) _0.3 (HO _1/2 ) _0.48 , manufactured by Toray Dow Corning)
SR-21 [weight average molecular weight: 3800, hydroxyl group content: 6% by weight, phenyl group content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.48 , Konishi Chemical Industries, Ltd. Made)
SR-20 [weight average molecular weight: 6700, hydroxyl group content: 3% by weight, phenyl group content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.24 , Konishi Chemical Co., Ltd. Made)
R10330 [weight average molecular weight: 3000 to 4000, vinyl group content: 7 mol%, average molecular formula: (Me ₃ SiO _1/2 ) _0.13 (SiO _4/2 ) _0.8 (ViMe ₂ SiO _1/2 ) _0.07 , blue (Star silicone)

  In the present invention, the content of the organopolysiloxane (B) suppresses an increase in volume resistivity, improves adhesion to a transparent conductive layer and the like, and forms an electrode having a lower contact resistance. From the reason which can be performed, it is preferable that it is 0.1-20 mass parts with respect to 100 mass parts of said electroconductive particle (A), and it is more preferable that it is 0.1-10 mass parts.

<Curable resin (C)>
The conductive composition of the present invention has better adhesion to a transparent conductive layer and the like, can form an electrode having a lower contact resistance, and has a higher coating film strength. From the reason that the strength is improved, it is preferable to contain a curable resin (C) other than the organopolysiloxane (B), and specifically, it is more preferable to contain an epoxy resin described in detail below.

The epoxy resin is not particularly limited as long as it is a resin composed of a compound having two or more oxirane rings (epoxy groups) in one molecule, and generally has an epoxy equivalent of 90 to 2,000.
A conventionally well-known epoxy resin can be used as such an epoxy resin.
Specifically, for example, epoxy compounds having a bisphenyl group such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type, and polyalkylene Bifunctional glycidyl ether type epoxy resins such as glycol type, alkylene glycol type epoxy compounds, epoxy compounds having a naphthalene ring, and epoxy compounds having a fluorene group;
Polyfunctional glycidyl ether type epoxy resins such as phenol novolac type, orthocresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type;
Glycidyl ester epoxy resins of synthetic fatty acids such as dimer acid;
N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyldiaminodiphenylsulfone (TGDDS), tetraglycidyl-m-xylylenediamine (TGMXDA), triglycidyl-p-aminophenol, triglycidyl- Glycidylamine epoxy resins such as m-aminophenol, N, N-diglycidylaniline, tetraglycidyl 1,3-bisaminomethylcyclohexane (TG1,3-BAC), triglycidyl isocyanurate (TGIC);
Tricyclo [5,2,1,0 ^2,6] epoxy compound having a decane ring, specifically, for example, after polymerizing the cresols or phenols such as dicyclopentadiene and cresol are reacted with epichlorohydrin Epoxy compounds obtainable by known production methods;
Cycloaliphatic epoxy resin; epoxy resin represented by Toraythiol Co., Ltd. Frep 10 epoxy resin main chain having sulfur atom; urethane modified epoxy resin having urethane bond; polybutadiene, liquid polyacrylonitrile-butadiene rubber or acrylonitrile butadiene rubber Examples thereof include a rubber-modified epoxy resin containing (NBR).

These may be used alone or in combination of two or more.
Of these, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferable from the viewpoints of curability, heat resistance, durability, and cost.

In the present invention, it is preferable to use an epoxy resin with little curing shrinkage as the epoxy resin. Since a silicon wafer as a substrate is easily damaged, using an epoxy resin having a large curing shrinkage causes cracking or chipping of the wafer. In recent years, silicon wafers have been made thinner for cost reduction, and an epoxy resin with little curing shrinkage also has an effect of suppressing warpage of the wafer.
The reason why ethylene oxide and / or propylene oxide is reduced is that the shrinkage on curing is reduced, the volume resistivity is lower, the adhesion to the transparent conductive layer and the like becomes better, and an electrode having a lower contact resistance can be formed. An added epoxy resin is preferred.
Here, the epoxy resin to which ethylene oxide and / or propylene oxide has been added is prepared by adding ethylene and / or propylene when preparing an epoxy resin by reacting bisphenol A, bisphenol F or the like with epichlorohydrin, for example. And then added (modified).
Commercially available products can be used as the epoxy resin to which ethylene oxide and / or propylene oxide is added. Specific examples thereof include ethylene oxide-added bisphenol A type epoxy resin (BEO-60E, manufactured by Shin Nippon Rika Co., Ltd.), propylene oxide addition. Bisphenol A type epoxy resin (BPO-20E, manufactured by Shin Nippon Chemical Co., Ltd.), Propylene oxide added bisphenol A type epoxy resin (EP-4010S, manufactured by ADEKA), Propylene oxide added bisphenol A type epoxy resin (EP-4000S, ADEKA) Manufactured) and the like.

Another method for adjusting the curing shrinkage of the epoxy resin is to use two or more types of epoxy resins having different molecular weights in combination.
Among them, bisphenol A type having an epoxy equivalent of 1500 to 4000 g / eq because the volume resistivity is lower, the adhesion to the transparent conductive layer and the like becomes better, and an electrode having a lower contact resistance can be formed. It is preferable to use an epoxy resin (C1) and a polyhydric alcohol glycidyl type epoxy resin (C2) having an epoxy equivalent of 1000 g / eq or less or a diluted bisphenol A type epoxy resin (C3) of 1000 g / eq or less.

(Bisphenol A type epoxy resin (C1))
The bisphenol A type epoxy resin (C1) is a bisphenol A type epoxy resin having an epoxy equivalent of 1500 to 4000 g / eq.
Since the epoxy equivalent of the bisphenol A type epoxy resin (C1) is in the above range, when the bisphenol A type epoxy resin (C1) is used in combination as described above, curing shrinkage of the conductive composition of the present invention is suppressed, and the substrate And the adhesion to the transparent conductive layer becomes better. Since the volume resistivity becomes lower, the epoxy equivalent is preferably 2000 to 4000 g / eq, and more preferably 2000 to 3500 g / eq.

(Polyhydric alcohol glycidyl type epoxy resin (C2))
The polyhydric alcohol glycidyl epoxy resin (C2) is a polyhydric alcohol glycidyl epoxy resin having an epoxy equivalent of 1000 g / eq or less.
Since the polyhydric alcohol glycidyl type epoxy resin (C2) has an epoxy equivalent in the above range, when the polyhydric alcohol glycidyl type epoxy resin (C2) is used in combination as described above, the viscosity of the conductive composition of the present invention. Becomes good and printability becomes good.
The epoxy equivalent of the polyhydric alcohol-based glycidyl type epoxy resin (C2) is preferably 100 to 400 g / eq, and preferably 100 to 300 g / eq, because the viscosity at the time of screen printing becomes appropriate. More preferably.

(Dilution type bisphenol A epoxy resin (C3))
The dilution type bisphenol A type epoxy resin (C3) is a bisphenol A type epoxy resin having an epoxy equivalent of 1000 g / eq or less. The viscosity is lowered by using a reactive diluent without impairing the properties of the epoxy resin.
Since the epoxy equivalent of the bisphenol A type epoxy resin (C3) is in the above range, when the bisphenol A type epoxy resin (C3) is used in combination as described above, the viscosity of the conductive composition of the present invention is improved and the printability is increased. Becomes better.
The epoxy equivalent of the bisphenol A type epoxy resin (C3) is preferably 100 to 400 g / eq, and preferably 100 to 300 g / eq, because the viscosity at the time of screen printing becomes appropriate. More preferred.

  In this invention, it is preferable that content of the said curable resin (C) is 2-20 mass parts with respect to 100 mass parts of said electroconductive particles (A), and it is 2-15 mass parts. More preferably, it is 2 to 10 parts by mass.

<Curing agent (D)>
When the conductive composition of the present invention contains an epoxy resin as the curable resin (C) or when the organopolysiloxane (B) has an epoxy group, the conductive composition contains those curing agents (D). preferable.
As the curing agent (D), for example, a complex of boron trifluoride and an amine compound, which will be described in detail below, is preferably used.

As a complex of boron trifluoride and an amine compound, a complex of boron trifluoride and an aliphatic amine (aliphatic primary amine, aliphatic secondary amine, aliphatic tertiary amine), trifluoride Examples thereof include a complex of boron and an alicyclic amine, a complex of boron trifluoride and an aromatic amine, a complex of boron trifluoride and a heterocyclic amine, and the like. The heterocyclic amine may be an alicyclic heterocyclic amine (hereinafter also referred to as “alicyclic heterocyclic amine”) or an aromatic heterocyclic amine (hereinafter referred to as “aromatic heterocyclic amine”). It may be.)
Specific examples of the aliphatic primary amine include methylamine, ethylamine, n-propylamine, iso-propylamine, n-butylamine, iso-butylamine, sec-butylamine, n-hexylamine, n-octylamine, 2 -Ethylhexylamine, laurylamine, etc. are mentioned. Specific examples of the aliphatic secondary amine include dimethylamine, diethylamine, methylethylamine, methylpropylamine, di-iso-propylamine, di-n-propylamine, ethylpropylamine, di-n-butylamine, di- iso-butylamine, dipropenylamine, chlorobutylpropylamine, di (chlorobutyl) amine, di (bromoethyl) amine and the like. Specific examples of the aliphatic tertiary amine include trimethylamine, triethylamine, tributylamine, triethanolamine and the like. Specific examples of the alicyclic amine include cyclohexylamine. Examples of aromatic amines include benzylamine. Specific examples of the alicyclic heterocyclic amine include pyrrolidine, piperidine, 2-pipecoline, 3-pipecoline, 4-pipecoline, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, piperazine, and homopiperazine. N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-methylhomopiperazine, N-acetylpiperazine, 1- (chlorophenyl) piperazine, N-aminoethylpiperidine, N-aminopropylpiperidine, N-aminoethyl Piperazine, N-aminopropylpiperazine, morpholine, N-aminoethylmorpholine, N-aminopropylmorpholine, N-aminopropyl-2-pipecholine, N-aminopropyl-4-pipecholine, 1,4-bis (aminopropyl) piperazine , Triethylenediamine , 2-methyl-triethylene Chie diamine and the like. Specific examples of the aromatic heterocyclic amine include pyridine, pyrrole, imidazole, pyridazine, pyrimidine, quinoline, triazine, tetrazine, isoquinoline, quinazoline, naphthyridine, pteridine, acridine, phenazine and the like.

  The curing agent (D) has a lower volume resistivity and can form an electrode having a lower contact resistance with respect to the transparent conductive layer or the like, so that boron trifluoride piperidine, boron trifluoride ethylamine and trifluoride are used. A complex selected from the group consisting of borohydride triethanolamine is preferred.

  The content of the curing agent (D) is lower in volume resistivity and can form an electrode having a lower contact resistance with respect to the transparent conductive layer or the like, so that 100 parts by mass of the conductive particles (A) can be formed. It is preferable that it is 0.1-1 mass part with respect to it.

<Solvent (E)>
The conductive composition of the present invention preferably contains a solvent (E) from the viewpoint of workability such as printability.
The solvent (E) is not particularly limited as long as the conductive composition of the present invention can be applied onto a substrate. Specific examples thereof include butyl carbitol, methyl ethyl ketone, isophorone, α-terpineol, and the like. These may be used alone or in combination of two or more.

<Additives>
The electrically conductive composition of this invention may contain additives, such as a reducing agent, as needed.
Specific examples of the reducing agent include ethylene glycols.

  The method for producing the conductive composition of the present invention is not particularly limited, and the conductive particles (A) and the organopolysiloxane (B) and the curable resin (C) which may be optionally contained, and the curing described above. The method of mixing an agent (D), the said solvent (E), etc. with a roll, a kneader, an extruder, a universal stirrer etc. is mentioned.

[Solar cells]
The solar battery cell of the present invention is a solar battery cell using the above-described conductive composition of the present invention as a collecting electrode.

<First preferred embodiment of solar cell>
As a 1st suitable aspect of the photovoltaic cell of this invention, it comprises the surface electrode by the side of a light-receiving surface, a semiconductor substrate, and a back electrode, The said surface electrode and / or the said back electrode are the electroconductivity of this invention mentioned above. A solar battery cell formed using the composition can be mentioned.
Below, the 1st suitable aspect of the photovoltaic cell of this invention is demonstrated using FIG.

As shown in FIG. 1, the solar cell 1 includes a surface electrode 4 on the light receiving surface side, a pn junction silicon substrate 7 in which a p layer 5 and an n layer 2 are joined, and a back electrode 6.
As shown in FIG. 1, the solar battery cell 1 is preferably provided with an antireflection film 3, for example, by etching the wafer surface to form a pyramidal texture in order to reduce reflectivity.
Below, the said surface electrode which the 1st suitable aspect of the photovoltaic cell of this invention comprises, a back surface electrode, a silicon substrate, and the said antireflection film | membrane which may be optionally provided are explained in full detail.

(Front electrode / Back electrode)
As long as any one or both of the front electrode and the back electrode are formed using the conductive composition of the present invention, the arrangement (pitch), shape, height, width and the like of the electrode are not particularly limited.
Here, as shown in FIG. 1, the front surface electrode and the back surface electrode usually have a plurality, but, for example, only a part of the plurality of surface electrodes is formed of the conductive composition of the present invention. Alternatively, part of the plurality of front surface electrodes and part of the plurality of back surface electrodes may be formed of the conductive composition of the present invention.

(Antireflection film)
The antireflection film is a film (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. For example, the silicon oxide film, the silicon nitride film, and the titanium oxide It is comprised from a film | membrane, these laminated films, etc.

The 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.

(Silicon substrate)
The silicon substrate is not particularly limited, and a known silicon substrate (plate thickness: about 80 to 450 μm) for forming a solar cell can be used, and either a monocrystalline or polycrystalline silicon substrate can be used. Good.

  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 cell, it can also be applied to an all-back electrode type solar cell. Can do.

<The manufacturing method of a photovoltaic cell (1st suitable aspect)>
Although the manufacturing method of the said photovoltaic cell (1st suitable aspect) is not specifically limited, The wiring formation process which apply | coats the electrically conductive composition of this invention on a silicon substrate, and forms wiring, and the formed wiring And a heat treatment step of forming an electrode (front electrode and / or back electrode) by heat treatment.
In the case where the solar battery cell includes an antireflection layer, the antireflection film can be formed by a known method such as a plasma CVD method.
Below, a wiring formation process and a heat treatment process are explained in full detail.

(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 forming a conductive wiring (electrode) by heat-treating the coating film formed in the wiring forming step.
By heat-treating the wiring, the conductive particles (A) are connected to form an electrode.

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 comparatively low temperature of 150-350 degreeC. When the temperature and time are within this range, an electrode can be easily formed even when an antireflection film is formed on a silicon substrate.
Moreover, in the 1st suitable aspect of the photovoltaic cell of this invention, since the electrically conductive composition of this invention is used, even if it is a comparatively low temperature of 150-350 degreeC, favorable heat processing (baking) ) Can be applied.
In the present invention, since the wiring formed in the wiring formation step can form electrodes even by irradiation with ultraviolet rays or infrared rays, the heat treatment step may be performed by irradiation with ultraviolet rays or infrared rays.

<The 2nd suitable aspect of a photovoltaic cell>
As a second preferred embodiment of the solar battery cell of the present invention, an amorphous silicon layer and a transparent conductive layer (for example, TCO) are provided above and below an n-type single crystal silicon substrate, and the transparent conductive layer is disposed below. Examples of the base layer include a solar cell (for example, a heterojunction solar cell) cell in which a collecting electrode is formed on the transparent conductive layer using the conductive composition of the present invention described above. The solar battery cell (second preferred embodiment) is a solar battery cell in which single crystal silicon and amorphous silicon are hybridized and exhibits high conversion efficiency.
Below, the 2nd suitable aspect of the photovoltaic cell of this invention is demonstrated using FIG.

  As shown in FIG. 2, the solar battery cell 100 has an n-type single crystal silicon substrate 11 as a center, i-type amorphous silicon layers 12 a and 12 b and p-type amorphous silicon layers 13 a and n-type amorphous silicon layers above and below the substrate. 13b, transparent conductive layers 14a and 14b, and current collecting electrodes 15a and 15b formed using the above-described conductive composition of the present invention.

The n-type single crystal silicon substrate is a single crystal silicon layer doped with an n-type impurity. Impurities that give n-type are as described above.
The i-type amorphous silicon layer is an undoped amorphous silicon layer.
The p-type amorphous silicon is an amorphous silicon layer doped with an impurity imparting p-type. Impurities that give p-type are as described above.
The n-type amorphous silicon is an amorphous silicon layer doped with an n-type impurity. Impurities that give n-type are as described above.
The said collector electrode is a collector electrode formed using the electrically conductive composition of this invention mentioned above. A specific aspect of the current collecting electrode is the same as that of the front surface electrode or the back surface electrode described above.

(Transparent conductive layer)
Specific examples of the material for the transparent conductive layer include single metal oxides such as zinc oxide, tin oxide, indium oxide, and titanium oxide, indium tin oxide (ITO), indium zinc oxide, indium titanium oxide, tin cadmium oxide, Various metal oxides such as gallium-doped zinc oxide, aluminum-doped zinc oxide (AZO), boron-doped zinc oxide, titanium-doped zinc oxide, titanium-doped indium oxide, zirconium-doped indium oxide, and fluorine-doped tin oxide Such as things.

<The manufacturing method of a photovoltaic cell (2nd suitable aspect)>
Although the manufacturing method of the said photovoltaic cell (2nd suitable aspect) is not specifically limited, For example, it can manufacture by the method etc. of Unexamined-Japanese-Patent No. 2010-34162.
Specifically, the i-type amorphous silicon layer 12a is formed on one main surface of the n-type single crystal silicon substrate 11 by a PECVD (plasma enhanced chemical vapor deposition) method or the like. Further, a p-type amorphous silicon layer 13a is formed on the formed i-type amorphous silicon layer 12a by PECVD or the like.
Next, an i-type amorphous silicon layer 12b is formed on the other main surface of the n-type single crystal silicon substrate 11 by PECVD or the like. Further, an n-type amorphous silicon layer 13b is formed on the formed i-type amorphous silicon layer 12b by PECVD or the like.
Next, transparent conductive layers 14a and 14b such as ITO are formed on the p-type amorphous silicon layer 13a and the n-type amorphous silicon layer 13b by sputtering or the like.
Next, the conductive composition of the present invention is applied on the formed transparent conductive layers 14a and 14b to form wirings, and the formed wirings are heat-treated to form current collecting electrodes 15a and 15b.
The method for forming the wiring is the same as the method described in the wiring formation step of the above-described solar battery cell (first preferred embodiment).
The method of heat-treating the wiring is the same as the method described in the heat treatment step of the above-described solar battery cell (first preferred embodiment), but the heat treatment temperature (firing temperature) is preferably 150 to 200 ° C.

  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 1-2, Reference Example 3, Examples 4-5, Reference Examples 6-7 , Comparative Examples 1-3)
The epoxy resin shown in the following Table 1 was blended so as to have the composition ratio (parts by mass) shown in the following Table 1, and these were mixed to prepare a conductive composition.

  About each adjusted electrically conductive composition, the volume resistivity, the adhesiveness before and behind a moisture resistance test, and the contact resistance before and behind a moisture resistance test were evaluated by the method shown below.

<Volume resistivity (specific resistance)>
On the surface of soda lime glass, ITO (indium oxide doped with Sn) and AZO (Al doped ZnO) were formed as a transparent conductive layer to prepare a glass substrate for evaluation.
Subsequently, each prepared electrically conductive composition was apply | coated by screen printing on the glass substrate, and the test pattern which is a solid coating of 20 mm x 20 mm was formed.
It dried for 30 minutes at 200 degreeC in oven, and produced the electroconductive film.
About each produced electroconductive film, the volume resistivity was evaluated by the 4-terminal 4 probe method using the resistivity meter (Lorestar GP, Mitsubishi Chemical Corporation make). The results are shown in Table 1. In addition, since the volume resistivity was the same value with the glass substrate which formed ITO into a film, and the glass substrate which formed AZO, the value is shown in the following Table 1.

<Contact resistance>
First, ITO (indium oxide doped with Sn) and AZO (Al-doped ZnO) were formed as transparent conductive layers on the surface of soda lime glass to produce a glass substrate for evaluation.
Subsequently, each prepared electrically conductive composition was apply | coated by screen printing on the glass substrate, and the test pattern of the thin line shape of width 300um and length 2.5cm was formed.
The film was dried in an oven at 200 ° C. for 30 minutes to produce a thin wire-shaped conductive film (thin wire electrode). At this time, the distance between the electrodes was 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm.
The resistance value between each thin wire electrode was measured using a digital multimeter (HIOKI: 3541 REISTANCE HiTESTER), and the contact resistance was calculated by Transfer Length Method (TLM method).
The same measurement was performed after a moisture resistance test that was left in a constant temperature and humidity chamber at 85 ° C. and 85% for 1 hour, and contact resistance was determined.
These results are shown in Table 1 below.

<Adhesion>
After making 100 (10 × 10) 1 mm bases on the conductive film used for measuring volume resistivity, completely attaching cellophane adhesive tape on the bases and rubbing 10 times with the belly of the finger, One end of the tape was instantaneously separated while being kept at a right angle to the conductive coating, and the number of base meshes remaining without being completely peeled was examined, and the result was shown by the number of remaining grids / 100. Note that 100/100 means that the number of grids peeled off is zero.
The same measurement was performed after a moisture resistance test that was left in a constant temperature and humidity chamber at 85 ° C. and 85% for 1 hour to evaluate adhesion.
These results are shown in Table 1 below.

The following were used for each component in Table 1.
Conductive particles: Silver particles (AG4-8F, average particle size: 2.2 μm, manufactured by DOWA Electronics)
Epoxy resin C1: Bisphenol A type epoxy resin (YD-019, epoxy equivalent: 2400-3300 g / eq, manufactured by Nippon Steel Chemical Co., Ltd.)
Epoxy resin C2: Polyethylene glycol diglycidyl ether (polyhydric alcohol glycidyl type epoxy resin) (EX-821, epoxy equivalent: 185 g / eq, manufactured by Nagase ChemteX Corporation)
Epoxy resin C3: bisphenol A type epoxy resin (JER806, epoxy equivalent: 160 to 170 g / eq, manufactured by Mitsubishi Chemical Corporation)
・ Curing agent: Boron trifluoride piperidine (manufactured by Stella Chemifa)
・ Solvent: α-terpineol (manufactured by Yasuhara Chemical)

Silicone resin B1: 217 Flake [weight average molecular weight: 2000, hydroxyl group content: 7% by weight, phenyl group content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.57 , Toray (Dow Corning)
-Silicone resin B2: 217 Flakes (manufactured by Dow Corning Toray) 100g, 20g of epoxy silane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) is added and reacted in toluene in the presence of an acetic acid catalyst for 4 hours. Synthetic product obtained (weight average molecular weight: 2000 to 3000, phenyl group content: 90 mol%, epoxy group content: 10 mol%)
Silicone resin B3: R10330 [weight average molecular weight: 3000 to 4000, vinyl group content: 7 mol%, average molecular formula: (Me ₃ SiO _1/2 ) _0.13 (SiO _4/2 ) _0.8 (ViMe ₂ SiO _1/2 ) _0.07 , Blue Star Silicone]
Organopolysiloxane X: KR-220L [weight average molecular weight: 5000, functional group: none, average molecular formula: CH ₃ SiO _3/2 , manufactured by Shin-Etsu Chemical Co., Ltd.]
Polyimide silicone resin Y: X-22-8904 [manufactured by Shin-Etsu Chemical Co., Ltd.]

From the results shown in Table 1, Comparative Examples 2 and 3 prepared using an organopolysiloxane having no phenyl group or vinyl group are more resistant to contact and adhesion than Comparative Example 1 prepared without using an organopolysiloxane. Improved, but found to be inadequate.
In contrast, Examples 1-2, Reference Example 3, Examples 4-5, and Reference Examples 6-7 prepared using organopolysiloxanes having a phenyl group or vinyl group all maintain a low volume resistivity. However, it was found that the contact resistance and adhesion were also good.
Moreover, from the comparison with Examples 1-2, Reference Example 3, Examples 4-5, and Reference Example 6, the case where the epoxy resin which is curable resin is used, or organopolysiloxane has an epoxy group. In this case, it was found that the contact resistance and adhesion were also good after the moisture resistance test. Although not shown in Table 1, it was also found that the conductive coatings produced in Examples 1-2, Reference Example 3, and Examples 4-5 had higher strength.
Furthermore, from the comparison between Examples 1-2, Reference Example 3, Examples 4-5 and Reference Example 7, the content of organopolysiloxane is 0.1 to 10.0 mass with respect to 100 mass parts of conductive particles. In the case of a part, the volume resistivity is low and the contact resistance is low.

DESCRIPTION OF SYMBOLS 1,100 Solar cell 2 N layer 3 Anti-reflective film 4 Front surface electrode 5 P layer 6 Back surface electrode 7 Silicon substrate 11 N-type single crystal silicon substrate 12a, 12b i-type amorphous silicon layer 13a p-type amorphous silicon layer 13b n-type amorphous Silicon layer 14a, 14b Transparent conductive layer 15a, 15b Current collecting electrode

Claims (6)

Containing conductive particles (A) and an organopolysiloxane (B) having a phenyl group and / or a vinyl group ,
The organopolysiloxane (B) includes a repeating unit represented by the following formula (S-3) or (S-4),
Further, containing a curable resin (C) other than the organopolysiloxane (B),
The curable resin (C) is an epoxy resin,
The electroconductive composition whose content of the said organopolysiloxane (B) is 0.1-10 mass parts with respect to 100 mass parts of said electroconductive particle (A) .
{In the repeating unit represented by the above formula (S-3), each R independently represents a substituted or unsubstituted monovalent hydrocarbon group, and at least one R is a phenyl group or a vinyl group. Represents. } The conductive composition according to claim 1, wherein the conductive particles (A) are silver particles and / or copper particles. The organopolysiloxane (B), a conductive composition according to claim 1 or 2 further comprising an epoxy group. The photovoltaic cell which used the electrically conductive composition in any one of Claims 1-3 for the current collection electrode. The solar cell according to claim 4 , further comprising a transparent conductive layer as a base layer of the current collecting electrode. A solar battery module using the solar battery cell according to claim 4 or 5 .