TW201434988A - Conductive compositions and solar cell - Google Patents

Abstract

The purpose of the present invention is to provide: a conductive composition which is capable of providing an electrode or the like that has low contact resistance and exhibits excellent adhesion to a transparent conductive layer and the like, while maintaining low volume resistivity and a solar cell which uses this conductive composition for a collector electrode. A conductive composition of the present invention contains (A) conductive particles and (B) an organopolysiloxane that has a phenyl group and/or a vinyl group.

Description

Conductive composition and solar cell unit

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

Conventionally, there has been known a method of adding a thermoplastic resin (for example, an acrylic resin or a vinyl acetate resin) or a thermosetting resin (for example, an epoxy resin, an anthracene resin, and an unsaturated polyester) to conductive particles such as silver particles. A binder, an organic solvent, a curing agent, a catalyst, or the like, which is composed of a resin or the like, is mixed to obtain a conductive paste (conductive composition), and then printed on a substrate (for example, a substrate, an epoxy substrate, or the like) The solar cell or the printed wiring board is formed by forming a predetermined pattern and heating it to form an electrode or a wiring.

As a conductive composition, for example, Patent Document 1 discloses "a conductive paste composition for low-temperature sintering, which is characterized by containing silver powder, polyamidoxime resin, and organic solvent" (requested item) 1).

Further, Patent Document 2 describes "a conductivity" A paste composition containing an anthracene resin, a conductive powder, a thermosetting component, a curing agent, and a solvent (claim 1), and a thermosetting component is described as a predetermined amount. Epoxy resin, etc. (request item 3).

Further, in Patent Document 3, the applicant proposes "a conductive composition containing silver powder (A), a fatty acid silver salt (B), a resin (C), and a solvent (D), wherein the fatty acid silver salt (B) is a compound having one carboxylic acid silver salt group (-COOAg) and having one or two hydroxyl groups (-OH), and the silver oxide content is 10 parts by mass or less based on 100 parts by mass of the solvent (D). (Required item 1), the resin (C) is described as "at least one selected from the group consisting of epoxy resin, polyester resin, enamel resin, and urethane resin" (Request Item 6).

[Practical Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-184153

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2007-224191

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2012-023095

However, the inventors of the present invention refer to Patent Documents 1 to 3 for blending enthalpy After conducting research on the conductive composition of the resin, it is clear that although the volume resistivity of the formed electrode or wiring (hereinafter also referred to as an electrode or the like) becomes low, a transparent conductive layer (for example, transparent) on a substrate (for example, a germanium wafer) is formed. When an electrode or the like is formed on a conductive oxide layer (TCO) or the like, adhesion may be inferior and contact resistance may increase.

Accordingly, an object of the present invention is to provide a conductive composition and a solar cell using the same for a collector electrode, which can be formed to maintain a low volume resistivity while being densely bonded to a transparent conductive layer or the like. An electrode that is excellent in compatibility and has low contact resistance.

In order to solve the above problems, the present inventors have found that by blending an organic polyoxyalkylene having a phenyl group and/or a vinyl group, it is possible to form a dense conductive layer and the like while maintaining a low volume resistivity. The present invention has been completed by an electrode or the like having excellent properties and low contact resistance.

In other words, the inventors of the present invention have found that the above problems can be solved by the following configuration.

(1) A conductive composition comprising conductive particles (A) and an organic polyoxyalkylene (B) having a phenyl group and/or a vinyl group.

(2) The conductive composition according to the above (1), further comprising a curable resin (C) other than the organic polysiloxane (B).

(3) The conductive composition according to the above (2), wherein the curable resin (C) is an epoxy resin.

(4) Conductivity as described in any one of (1) to (3) above In the composition, the conductive particles (A) are silver particles and/or copper particles.

(5) The conductive composition according to any one of the above-mentioned (1), wherein the organopolyoxane (B) further has an epoxy group.

The conductive composition according to any one of the above (1) to (5), wherein the content of the organopolysiloxane (B) is 100 parts by mass based on 100 parts by mass of the conductive particles (A). 0.1 to 10 parts by mass.

(7) A solar cell according to any one of the above (1) to (6), wherein the conductive composition is used for a collector electrode.

(8) The solar battery cell according to (7) above, which further comprises a transparent conductive layer as a base layer of the current collecting electrode.

(9) A solar battery module using the solar battery unit according to (7) or (8) above.

As shown below, according to the present invention, it is possible to provide a conductive composition and a solar cell unit which is used for a collector electrode, which can be formed while maintaining a low volume resistivity, a transparent conductive layer, etc. An electrode having excellent adhesion and low contact resistance.

Further, the conductive composition of the present invention can form a low-volume (about 150 to 350 ° C (especially before and after 200 ° C)) sintering, and can maintain a low volume resistivity and excellent adhesion to a transparent conductive layer or the like. And contact with low-resistance electrodes, etc., so it also has the ability to reduce solar energy The battery unit (especially the second embodiment described later) is very useful because it is damaged by heat.

Further, the conductive composition of the present invention is useful not only for high heat resistance materials but also for low heat resistance materials such as PET films, and it is also possible to easily and quickly produce circuits such as electronic circuits and antennas.

1,100‧‧‧ solar battery unit

2‧‧‧n layer

3‧‧‧Anti-reflection film

4‧‧‧ surface electrode

5‧‧‧p layer

6‧‧‧Back electrode

7‧‧‧矽 substrate

11‧‧‧n type single crystal germanium substrate

12a, 12b‧‧‧i type amorphous layer

13a‧‧‧p-type amorphous layer

13b‧‧‧n type amorphous layer

14a, 14b‧‧‧Transparent conductive layer

15a, 15b‧‧‧ collector electrode

Fig. 1 is a cross-sectional view showing a first embodiment of a solar battery cell.

Fig. 2 is a cross-sectional view showing a second embodiment of the solar battery unit.

[Electroconductive composition]

The conductive composition of the present invention contains conductive particles (A) and an organic polyoxyalkylene (B) having a phenyl group and/or a vinyl group.

Further, as described later, the conductive composition of the present invention is preferably a curable resin (C) other than the above organopolysiloxane (B).

In the present invention, by mixing the organic polyoxyalkylene (B) having a phenyl group and/or a vinyl group together with the conductive particles (A), the conductive composition obtained can be formed to maintain a low volume resistance. At the same time, the electrode is excellent in adhesion to a transparent conductive layer or the like and has a low contact resistance.

Although the specific reason is not clear, it is considered to be because the functional group which the organopolysiloxane (B) has, that is, a phenyl group or a vinyl group, and a material (for example, a metal oxide or the like) which forms a transparent conductive layer or the like. Interaction, such that a transparent conductive layer or the like and a functional group are bonded at a molecular level.

In this regard, as shown in the comparative example described later, when a ruthenium resin having no phenyl group or a vinyl group is blended, the formed electrode and the like have poor adhesion and high contact resistance, and thus the fact can be estimated.

Hereinafter, the conductive particles (A), the organopolyoxyalkylene (B), and the curable resin (C) and other components which may be contained as needed are described in detail.

<Electrically 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), and nickel (Ni), and the like. One type can be used or two or more types can be used at the same time.

Among them, silver and copper are preferable, and silver is more preferable in view of the reason that an electrode having a lower volume resistivity can be formed.

In the present invention, in consideration of the fact that the printability is good, the conductive particles (A) are made of metal powder having an average particle diameter of 0.5 to 10 μm. The end is better.

Among the above metal powders, it is preferable to use spherical silver particles and/or copper particles for the reason that an electrode having a lower volume resistivity can be formed. Further, from the viewpoint of improving oxidation resistance, it is preferred that the copper particles are copper particles which have been surface-modified or coated with an organic compound, an inorganic compound, an inorganic oxide, or a metal other than copper.

Here, the average particle diameter means the average value of the particle diameter of the metal powder, and is a 50% volume cumulative diameter (D50) measured by a laser diffraction type particle size distribution analyzer. Further, regarding the particle diameter as the basis for calculating the average value, when the metal powder has an elliptical cross section, the total value of the major axis and the minor axis is divided by the average value of 2, and when it is a perfect circle, it means diameter.

Further, the spherical shape refers to a particle shape in which the ratio of the long diameter to the short diameter is 2 or less.

Further, in the present invention, in view of the fact that the printability is better, the average particle diameter of the conductive particles (A) is preferably 0.7 to 5.0 μm, and the reason why the sintering speed is appropriate and the workability is excellent is 1.0. ~3.0μm is better.

Further, in the present invention, a commercially available product can be used as the conductive particles (A).

Specific examples of the commercially available silver particles include AG2-1C (average particle diameter: 1.0 μm, manufactured by DOW Electronics Co., Ltd.), AG4-8F (average particle diameter: 2.2 μm, manufactured by DOWA Electronics Co., Ltd.), and AG3-11F. (Average particle size: 1.4 μm, DOWA Manufactured by Electronics Co., Ltd., AgC-102 (average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.), AgC-103 (average particle size: 1.5 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.), and EHD (average particle) Diameter: 0.5 μm, manufactured by Mitsui Metals Co., Ltd., etc.

<Organic Polyoxane (B)>

The organopolysiloxane (B) to be 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, the organopolyoxyalkylene refers to a polymer composed of one or more repeating units selected from the group consisting of four units shown below.

In the repeating unit represented by the above formulas (S-1) to (S-3), R each represents a substituted or non-substituted one-valent hydrocarbon group, and at least one R represents a phenyl group or a vinyl group.

Further, examples of the R other than the phenyl group and the vinyl group include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms.

Specific examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, and an anthracenyl group.

In the above alkenyl group (excluding vinyl group), specifically, For example, a butenyl group, a pentenyl group, an allyl group, etc. are mentioned.

Specific examples of the aryl group (excluding phenyl group) include a tolyl group, a xylyl group, and a naphthyl group.

In the present invention, the organic polyfluorene oxide (B) contains at least the above formula (S-3) in consideration of the possibility of forming an electrode having better adhesion to a transparent conductive layer or the like and having a lower contact resistance. The T unit represented by the above or the Q unit represented by the above formula (S-4), that is, the resin having a crosslinked structure is preferred.

The above-mentioned oxime resin may, for example, be an organopolyoxane represented by the following formula (1). Further, the weight average molecular weight of the organopolysiloxane represented by the following formula (1) is preferably from about 500 to 50,000.

( 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 addition, a is a positive number, b, c, d, and e are each 0 or a positive number, b/a is a number from 0 to 10, c/a is a number from 0 to 0.5, and 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 of X include the same as those described for the above formulas (S-1) to (S-3).

Further, in the R of the above formula (1), the ratio of the content of the phenyl group or the vinyl group (introduction) to the total value of R is preferably 10 mol% or more, more preferably 25 mol% or more, and 50 mol%. More than % are better.

In the present invention, adhesion to a transparent conductive layer or the like is considered. More preferably, the above organopolyoxyalkylene (B) is preferably one having an epoxy group other than a phenyl group and/or a vinyl group.

Here, the aspect of the epoxy group is, for example, R of the above formula (1) is a ring of 2,3-epoxypropyl group, 3,4-epoxybutyl group or 4,5-epoxypentyl group. Oxyalkyl; 2-glycidyloxyethyl, 3-glycidoxypropyl, 4-glycidyloxybutyl, etc.; and 2-(3,4- The form of an epoxycyclohexylalkyl group such as epoxycyclohexyl)ethyl or 3-(3,4-epoxycyclohexyl)propyl.

In another aspect, as shown in the examples below, a form in which an epoxy group is introduced by reacting an organopolysiloxane having a phenyl group and/or a vinyl group with an epoxy decane is exemplified.

Further, the ratio of the content (introduction) of the epoxy group of any component in the above formula (1) to R is preferably 0.1 mol% or more and less than 20 mol%.

In the present invention, the commercially available product shown below can be used as the above-mentioned organopolyoxane (B).

‧217 Flake [weight average molecular weight: 2000, hydroxyl content: 7 wt%, phenyl content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.57 , manufactured by Dow Corning Toray Co., Ltd.]

‧ TMS217 [weight average molecular weight: 2000, hydroxyl content: 2% by weight, phenyl content: 100 mol%, belonging to the resin which was subjected to end-blocking treatment of the above 217Flake with trimethylsulfonyl group, manufactured by Dow Corning Toray Co., Ltd. 〕

‧SH6018 [weight average molecular weight: 2000, hydroxyl content: 6% by weight, phenyl content: 70 mol%, propyl: 30 mol%, average molecular formula: (PhSiO _3/2 ) _0.7 (ProSiO _3/2 ) _0.3 (HO _1/2 ) _0.48 , manufactured by Dow Corning Toray]

‧SR-21 [weight average molecular weight: 3800, hydroxyl content: 6% by weight, phenyl content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.48 , manufactured by Xiaoxi Chemical Industry Co., Ltd. 〕

‧SR-20 [weight average molecular weight: 6700, hydroxyl content: 3% by weight, phenyl content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.24 , manufactured by Xiaoxi Chemical Industry Co., Ltd. 〕

‧R10330 [weight average molecular weight: 3000~4000, vinyl content: 7 mol%, average molecular formula: (Me ₃ SiO _1/2 ) _0.13 (SiO ₄ ) _0.8 (ViMe ₂ SiO _1/2 ) _0.07 , Bluestar Silicones Manufacturing

In the present invention, the content of the above-mentioned organopolyoxane (B) is compared with respect to the reason that an electrode having an increased volume resistivity, a good adhesion to a transparent conductive layer or the like, and a lower contact resistance can be formed. 100 parts by mass of the conductive particles (A) is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass.

<Curable resin (C)>

The conductive composition of the present invention is considered to have an effect of forming an electrode having a better adhesion to a transparent conductive layer or the like and having a lower contact resistance, and improving the strength of the coating film and improving the strength of the formed electrode or the like. The curable resin (C) other than the above organic polysiloxane (B) is Preferably, specifically, the epoxy resin detailed below is preferred.

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%. 2000.

As the epoxy resin, a conventionally known epoxy resin can be used.

Specific examples thereof include a bisphenol A type, a bisphenol F type, a brominated bisphenol A type, a hydrogenated bisphenol A type, a bisphenol S type, a bisphenol AF type, and a biphenyl type. Oxygen compound, polyethylene glycol type, ethylene glycol type epoxy compound, epoxy compound having a naphthalene ring, bifunctional glycidyl ether epoxy resin such as an oxime-based epoxy compound; phenol novolac type, adjacent Polyfunctional glycidyl ether epoxy resin such as cresol type, trihydroxyphenylmethane type or tetraphenol ethane type; glycidyl ester epoxy resin of synthetic fatty acid such as dimer acid; N, N, N ' , N ' -tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyldiaminodiphenylphosphonium (TGDDS), tetraglycidyl metaxylylenediamine (TGMXDA), triglycidyl P-aminophenol, triglycidyl m-amino phenol, N,N-diglycidyl aniline, tetraglycidyl 1,3-cyclohexanedimethylamine (TG 1,3-BAC), isocyanuric acid glycidyl (TGIC) glycidyl amine based epoxy resin and the like; having a tricyclo [5,2,1,0 ^2,6] decane ring of the epoxy compound, specifically, for example, bicyclic An epoxy compound obtained by polymerizing a cresol such as a diene or m-cresol or a phenolic aldehyde, and then reacting the epichlorohydrin to obtain a known epoxy resin; an alicyclic epoxy resin; FLEP10 manufactured by Thiokol is an epoxy resin having a sulfur atom in the epoxy resin main chain; a polyurethane modified epoxy resin having a polyurethane bond; and a polybutadiene, a liquid polyacrylonitrile-butadiene rubber or Rubber modified epoxy resin of acrylonitrile-butadiene rubber (NBR).

These may be used alone or in combination of two or more.

Further, among them, a bisphenol A type epoxy resin and a bisphenol F type epoxy resin are preferable from the viewpoints of hardenability, heat resistance, durability, and cost.

In the present invention, it is preferable to use an epoxy resin having less curing shrinkage as the above epoxy resin. Since the wafer as the substrate is easily damaged, if the epoxy resin having a large hardening shrinkage is used, the wafer may be broken or damaged. Recently, in order to reduce the cost, the wafer is continuously thinned, and the epoxy resin having less hardening shrinkage also has the effect of suppressing wafer bending.

Considering the reduction of hardening shrinkage, and the formation of a lower volume resistivity, a better adhesion to a transparent conductive layer, etc., and an electrode having a lower contact resistance, etc., an addition of ethylene oxide and/or Epoxy propylene oxide is preferred.

Here, as for the epoxy resin to which ethylene oxide and/or propylene oxide are added, for example, when an epoxy resin is reacted with an epichlorohydrin such as bisphenol A or bisphenol F, ethylene is added and / or propylene is added (modified) to obtain.

Addition of epoxy resin with ethylene oxide and/or propylene oxide Commercially available products can be used, and specific examples thereof include bisphenol A type epoxy resin (BPO-60E, manufactured by Nippon Chemical and Chemical Co., Ltd.) added with ethylene oxide, and bisphenol A type ring added with propylene oxide. Oxygen resin (BPO-20E, manufactured by Nippon Chemical and Chemical Co., Ltd.), bisphenol A epoxy resin (EP-4010S, manufactured by ADEKA), and bisphenol A epoxy resin added to propylene oxide Resin (EP-4000S, manufactured by ADEKA Co., Ltd.), etc.

As another method of adjusting the hardening shrinkage of the epoxy resin, a method of using two or more kinds of epoxy resins having different molecular weights at the same time may be mentioned.

Among them, consideration is given to the reason that an electrode having a lower volume resistivity, a better adhesion to a transparent conductive layer, and a lower contact resistance can be formed, and a bisphenol A having an epoxy equivalent of 1500 to 4000 g/eq can be simultaneously used. A type epoxy resin (C1), a polyvalent 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 is preferred. .

(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 bisphenol A type epoxy resin (C1) has the epoxy equivalent in the above range, as described above, when the bisphenol A type epoxy resin (C1) is used at the same time, the hardening shrinkage of the conductive composition of the present invention can be obtained. It is suppressed to have better adhesion to the substrate and the transparent conductive layer. Considering that the volume resistivity is lower, the epoxy equivalent is preferably 2000 to 4000 g/eq, and more preferably 2000 to 3500 g/eq.

(polyvalent alcohol glycidyl type epoxy resin (C2))

The polyvalent alcohol glycidyl type epoxy resin (C2) is a polyvalent alcohol glycidyl type epoxy resin having an epoxy equivalent of 1000 g/eq or less.

Since the polyvalent alcohol glycidyl type epoxy resin (C2) has the epoxy equivalent in the above range, the conductivity of the present invention is as described above when the polyvalent alcohol glycidyl type epoxy resin (C2) is used at the same time. The composition has good viscosity and good printability.

Further, considering the reason why the viscosity at the time of screen printing is appropriate, the above-mentioned polyvalent alcohol glycidyl type epoxy resin (C2) preferably has an epoxy equivalent of 100 to 400 g/eq, more preferably 100 to 300 g/eq.

(Diluted bisphenol A epoxy resin (C3))

The diluted bisphenol A type epoxy resin (C3) is a bisphenol A type epoxy resin having an epoxy equivalent of 1000 g/eq or less. It is subjected to a low viscosity treatment using a reactive diluent without damaging the properties of the epoxy resin.

Since the diluted bisphenol A type epoxy resin (C3) has the epoxy equivalent in the above range, the conductive composition of the present invention is used as described above when the diluted bisphenol A type epoxy resin (C3) is used at the same time. The viscosity is good and the printability is good.

Further, considering the reason why the viscosity at the time of screen printing is appropriate, the epoxy equivalent of the diluted bisphenol A type epoxy resin (C3) is preferably 100 to 400 g/eq, more preferably 100 to 300 g/eq.

In the present invention, the content of the curable resin (C) is preferably 2 to 20 parts by mass, more preferably 2 to 15 parts by mass, and 2 to 10 parts by mass, based on 100 parts by mass of the conductive particles (A). Better.

Further, the mass ratio (B/C) of the above organopolyoxane (B) to the curable resin (C) is preferably 0.01 to 3.50.

<hardener (D)>

When the conductive composition of the present invention contains an epoxy resin as the curable resin (C) or when the organopolyoxane (B) contains an epoxy group, the electroconductive composition contains the curing agent (D). It is better.

The hardener (D) is preferably a complex of boron trifluoride and an amine compound as described in detail below.

Examples of the complex of boron trifluoride and an amine compound include a complex of boron trifluoride and an aliphatic amine (aliphatic first-grade amine, aliphatic secondary amine, aliphatic tertiary amine), and trifluorochemical. A complex of boron and an alicyclic amine, a complex of boron trifluoride and an aromatic amine, and a complex of boron trifluoride and a heterocyclic amine. The heterocyclic amine may be an alicyclic heterocyclic amine (hereinafter also referred to as "alicyclic heterocyclic amine") or an aromatic heterocyclic amine (hereinafter also referred to as "aromatic heterocyclic amine"). .

Specific examples of the aliphatic primary amine include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, n-hexylamine, n-octylamine, and 2-ethylhexylamine. And laurylamine and the like. Specific examples of the aliphatic secondary amine include dimethylamine, diethylamine, methylethylamine, and methyl group. Propylamine, diisopropylamine, di-n-propylamine, ethylpropylamine, di-n-butylamine, diisobutylamine, dipropenylamine, chlorobutylpropylamine, bis(chlorobutyl)amine, and bis(bromomethyl)amine Wait. Specific examples of the aliphatic tertiary amine include trimethylamine, triethylamine, tributylamine, and triethanolamine. Specific examples of the alicyclic amine include cyclohexylamine and the like. Examples of the aromatic amine include benzylamine and the like. Specific examples of the alicyclic heterocyclic amine include pyrrolidine, piperidine, 2-methylpiperidine, 3-methylpiperidine, 4-methylpiperidine, 2,4-dimethylpyridine, 2,6- Lutidine, 3,5-lutidine, piperazine, homopiperazine, N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-methylhomopiperazine, N-Ethylpiperazine, 1-(chlorophenyl)piperazine, aminoethyl piperidine, aminopropyl piperidine, N-amine ethylpiperazine (aminoethyl) Piperazine), aminopropyl piperazine, morpholine, N-amine ethylmorpholine, N-aminopropylmorpholine, N-aminopropyl-2-methylpiperidine, N-aminopropyl Base-4-methylpiperidine, 1,4-bis(aminopropyl)piperazine, triethylenediamine, and 2-methyltriethylenediamine. Specific examples of the aromatic heterocyclic amine include pyridine, pyrrole, imidazole, pyridazine, pyrimidine, quinoline, triazine, tetrazine, isoquinoline, quinazoline, naphthyridine, pteridine, acridine, and Phenazine and the like.

Considering the reason that an electrode having a lower volume resistivity and a lower contact resistance with a transparent conductive layer or the like can be formed, the above-mentioned curing agent (D) is obtained from boron trifluoride piperidine and boron trifluoride bromide. Further, a complex selected from the group consisting of boron trifluoride triethanolamine is preferred.

The above-mentioned hardener is considered for the reason that an electrode having a lower volume resistivity and a lower contact resistance with a transparent conductive layer or the like can be formed. The content of the component (D) is preferably 0.1 to 1 part by mass based on 100 parts by mass of the conductive particles (A).

<Solvent (E)>

From the viewpoint of workability such as printability, the conductive composition of the present invention is preferably one containing a solvent (E).

The solvent (E) is not particularly limited as long as it can apply the conductive composition of the present invention to a substrate, and specific examples thereof include butyl carbitol, methyl ethyl ketone, and isophorone. And α-terpineol, etc., which may be used alone or in combination of two or more.

<additive>

The conductive composition of the present invention may contain an additive such as a reducing agent as needed.

Specific examples of the reducing agent include ethylene glycol and the like.

In the conductive composition of the present invention, a fatty acid silver salt which is an essential component of the conductive composition described in the patent document 3 (Japanese Patent Laid-Open Publication No. 2012-023095), which is related to the above-mentioned conductive particles (A) 100 parts by mass is preferably less than 5 parts by mass.

The method for producing the conductive composition of the present invention is not particularly limited, and examples thereof include the above-mentioned conductive particles (A) and the above-mentioned organic polysiloxane by means of a roll, a kneader, an extruder, and a universal agitator. Alkane (B), and the above-mentioned hardenable tree which may also be contained as needed The fat (C), the above-mentioned curing agent (D), the above solvent (E), and the like are mixed.

[Solar battery unit]

In the solar battery cell of the present invention, the conductive composition of the present invention described above is used as a collector electrode.

<First Embodiment of Solar Cell Unit>

In the first embodiment of the solar battery cell of the present invention, a solar battery cell including a surface electrode on the light-receiving surface side, a semiconductor substrate, and a back surface electrode, wherein the surface electrode and/or the back surface electrode use the above-described present invention The conductive composition is formed.

Hereinafter, a first embodiment of a solar battery cell of the present invention will be described with reference to Fig. 1 .

As shown in FIG. 1, the solar cell unit 1 includes a surface electrode 4 on the light-receiving surface side, a pn junction germanium substrate 7 formed by bonding the p-layer 5 and the n-layer 2, and a back surface electrode 6.

Further, as shown in FIG. 1, in order to reduce the reflectance, the solar battery cell 1 is preferably etched on the surface of the wafer to form a pyramid-shaped texture, and is preferably provided with the anti-reflection film 3.

Hereinafter, the surface electrode, the back surface electrode, the ruthenium substrate, and the above-described anti-reflection film which are arbitrarily provided in the first embodiment of the solar battery cell of the present invention will be described in detail.

<surface electrode / back electrode>

The surface electrode and the back surface electrode may be formed using any one or both of the conductive compositions of the present invention, and the arrangement (pitch), shape, height, width, and the like of the electrodes are not particularly limited.

Here, although the surface electrode and the back surface electrode are generally as shown in FIG. 1, for example, only a part of the plurality of surface electrodes may be formed of the conductive composition of the present invention, or one of the plurality of surface electrodes may be provided with a plurality of back surfaces. One of the electrodes is formed of the conductive composition of the present invention.

<anti-reflection film>

The antireflection film is a film formed by a portion where no surface electrode is formed on the light receiving surface (thickness: 0.05 to 0.1 μm), for example, a tantalum oxide film, a tantalum nitride film, a titanium oxide film, and the like, and the like. Composition.

Further, the ruthenium substrate has a pn junction, and this indicates that the second conductivity type light-receiving surface impurity diffusion region is formed on the surface side of the first conductivity-type semiconductor substrate. Further, when the first conductivity type is an n-type, the second conductivity type is a p-type, and when the first conductivity type is a p-type, the second conductivity type is an n-type.

Here, examples of the impurity forming the p-type include boron and aluminum, and examples of the impurity forming the n-type include phosphorus and arsenic.

(矽 substrate)

The tantalum substrate is not particularly limited, and a well-known tantalum substrate (having a thickness of about 80 to 450 μm) for forming a solar cell can be used, and any one of a single crystal or a polycrystal can be used.

Further, the conductive composition of the present invention is also suitably used for forming a back electrode of a full-back electrode type (so-called full-back electrode) solar cell, and thus can be applied to a full-back electrode type solar cell.

<Method of Manufacturing Solar Cell (First Embodiment)>

The method for producing the solar cell unit (the first embodiment) is not particularly limited, and examples thereof include a method of forming a wiring by applying the conductive composition of the present invention onto a ruthenium substrate, and forming a wiring; The wiring is heat-treated to form a heat treatment step of the electrode (surface electrode and/or back electrode).

Further, when the solar cell unit is provided with an antireflection layer, the antireflection film can be formed by a well-known method such as a plasma DVD method.

Hereinafter, the wiring forming step and the heat treatment step will be described in detail.

(Wiring forming process)

In the wiring forming step, the conductive composition of the present invention is applied onto a tantalum substrate to form a wiring.

Here, specific examples of the coating method include inkjet, screen printing, gravure printing, offset printing, and relief printing.

(heat treatment process)

The heat treatment step is a step of heat-treating the coating film formed in the wiring forming step to form a conductive wiring (electrode).

After heat treatment of the wiring, the conductive particles (A) are connected, and the electrode is formed.

The heat treatment is not particularly limited, and it is preferably a treatment of heating (sintering) at a low temperature of 150 to 350 ° C for several seconds to several tens of minutes. When the temperature and time are within this range, the electrode can be easily formed even if an antireflection film is formed on the crucible substrate.

Further, in the first embodiment of the solar battery cell of the present invention, since the conductive composition of the present invention is used, good heat treatment (sintering) can be performed even at a relatively low temperature of 150 to 350 °C.

In the present invention, the wiring formed in the wiring forming step may be formed by ultraviolet rays or infrared rays, and thus the heat treatment step may be performed by ultraviolet rays or infrared rays.

<Second Embodiment of Solar Cell>

In a second embodiment of the solar battery cell of the present invention, a solar cell (for example, a heterojunction solar cell) unit including an amorphous germanium layer and a transparent conductive layer (for example, an n-type single crystal germanium substrate) is provided. TCO), wherein the transparent conductive layer is used as a base layer, and a current collecting electrode is formed on the transparent conductive layer by using the conductive composition of the present invention. The solar cell unit (second embodiment) is a solar cell in which a single crystal germanium and an amorphous germanium are mixed, and has high conversion efficiency.

Hereinafter, a second embodiment of the solar battery cell of the present invention will be described with reference to Fig. 2 .

As shown in FIG. 2, the solar battery cell 100 has i-type amorphous germanium layers 12a and 12b, a p-type amorphous germanium layer 13a, and an n-type amorphous germanium layer 13b, and is transparent, centering on the n-type single crystal germanium substrate 11. The conductive layers 14a and 14b and the collector electrodes 15a and 15b formed using the above-described conductive composition of the present invention.

The n-type single crystal germanium substrate is a single crystal germanium layer doped with an n-type impurity. The n-type impurity is generated as described above.

The above i-type amorphous germanium layer is an undoped amorphous germanium layer.

The p-type amorphous germanium is an amorphous germanium layer doped with a p-type impurity. The p-type impurity is produced as described above.

The above n-type amorphous germanium is an amorphous germanium layer doped with an impurity which generates n-type. The n-type impurity is generated as described above.

The collector electrode is a collector electrode formed using the above-described conductive composition of the present invention. The specific form of the collector electrode is the same as the surface electrode or the back electrode described above.

(transparent conductive layer)

Specific examples of the transparent conductive layer material include single metal oxides such as zinc oxide, tin oxide, indium oxide, and titanium oxide; indium oxide tin oxide adduct (ITO), indium oxide zinc oxide adduct, and indium oxide. Various metal oxides such as titanium oxide adduct, tin oxide cadmium oxide adduct; and cadmium-doped zinc oxide, aluminum-doped zinc oxide (AZO), boron-doped oxidation Zinc, titanium-doped zinc oxide, titanium-doped indium oxide, zirconium-doped indium oxide, fluorine-doped tin oxide and other doped metal oxides.

<Method of Manufacturing Solar Cell Unit (Second Embodiment)>

The production method of the solar cell unit (second embodiment) is not particularly limited, and it can be produced by, for example, the method described in JP-A-2010-34162.

Specifically, the i-type amorphous germanium layer 12a can be formed on one side main surface of the n-type single crystal germanium substrate 11 by a method such as PECVD (plasma enhanced chemical vapor deposition). Further, a p-type amorphous germanium layer 13a is formed on the formed i-type amorphous germanium layer 12a by a method such as PECVD.

Next, an i-type amorphous germanium layer 12b is formed on the other main surface of the n-type single crystal germanium substrate 11 by a method such as PECVD. Further, an n-type amorphous germanium layer 13b is formed on the formed i-type amorphous germanium layer 12b by a method such as PECVD.

Next, transparent conductive layers 14a and 14b such as ITO are formed on the p-type amorphous germanium layer 13a and the n-type amorphous germanium layer 13b by sputtering or the like.

Next, the conductive composition of the present invention is applied onto the formed transparent conductive layers 14a and 14b to form wiring, and the formed wiring is further heat-treated to form collector electrodes 15a and 15b.

The method of forming the wiring is the same as the method described in the wiring forming step of the solar battery cell (first embodiment) described above.

The method of heat-treating the wiring is the same as the method described in the heat treatment step of the solar battery cell (first embodiment), and the heat treatment temperature (sintering temperature) is preferably 150 to 200 °C.

Example

Hereinafter, the conductive composition of the present invention will be described in detail by way of examples. However, the invention is not limited thereto.

<Examples 1 to 7 and Comparative Examples 1 to 3>

The conductive composition is prepared by blending an epoxy resin or the like shown in the following Table 1 according to the composition ratio (parts by mass) shown in the following Table 1.

With respect to each of the prepared conductive compositions, the volume resistivity, the adhesion before and after the moisture resistance test, and the contact resistance before and after the moisture resistance test were evaluated by the following methods.

<Volume resistivity (specific resistance)>

On the surface of the soda lime glass, ITO (indium oxide doped with Sn) and AZO (ZnO doped with Al) were formed into a film to prepare a glass substrate for evaluation as a transparent conductive layer.

Next, each of the prepared conductive compositions was applied onto a glass substrate by a screen printing method to form a 20 mm × 20 mm full-surface coated test pattern.

Dry in an oven at 200 ° C for 30 minutes to make a guide Electrical film.

The volume resistivity of each of the produced conductive films was measured by a 4-terminal 4-probe method using a resistivity meter (Loresta-GP, manufactured by Mitsubishi Chemical Corporation). The results are shown in Table 1. Further, in the glass substrate on which the ITO film is formed and the glass substrate on which the AZO film is formed, the volume resistivity is the same, and therefore the value is shown in the first table below.

<contact resistance>

First, on the surface of the soda lime glass, ITO (indium oxide doped with Sn) and AZO (ZnO doped with Al) were formed into a film to prepare a glass substrate for evaluation as a transparent conductive layer.

Next, each of the prepared conductive compositions was applied onto a glass substrate by a screen printing method to form a thin line test pattern having a width of 300 μm and a length of 2.5 cm.

The film was dried at 200 ° C for 30 minutes in an oven to prepare a fine linear conductive film (fine wire electrode). At this time, the electrode pitch was 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm.

After measuring the resistance value between the thin wire electrodes by a digital multimeter (3541 RESISTANCE HiTESTER, manufactured by HIOKI Co., Ltd.), the contact resistance was calculated by a Transfer Length Method (TLM, Transmission Line Model Method).

Then, it was allowed to stand in a constant temperature and humidity chamber at 85 ° C and 85% for 1 hour to carry out a moisture resistance test, and the same measurement was carried out to calculate the contact resistance.

The results are shown in Table 1 below.

<adhesion>

On a conductive film for measuring volume resistivity, after making 100 (10 × 10) 1 mm checkerboards, the transparent tape is completely attached to the checkerboard, rubbed with the fingertips 10 times, and then at the end of the tape paper. The conductive film is quickly pulled apart while maintaining a right angle, and the remaining checkerboard is not completely peeled off, and the result is expressed by the number of remaining checkerboards/100. In addition, 100/100 means that the number of chessboards stripped is zero.

Then, it was allowed to stand in a constant temperature and humidity chamber at 85 ° C and 85% for 1 hour to carry out a moisture resistance test, and the same measurement was carried out to evaluate the adhesion.

The results are shown in Table 1 below.

The following materials were used for each component in Table 1.

‧ Conductive particles: silver particles (AG4-8F, average particle size: 2.2 μm, manufactured by DOW Electronics)

‧Epoxy resin C1: bisphenol A epoxy resin (YD-019, epoxy equivalent: 2400~3300g/eq, manufactured by Nippon Steel Chemical Co., Ltd.)

‧Epoxy resin C2: Diethanol diglycidyl ether (polyvalent alcohol glycidyl epoxy resin) (EX-821, epoxy equivalent: 185g/eq, manufactured by Nagasechemtex)

‧Epoxy resin C3: bisphenol A epoxy resin (JER806, epoxy equivalent: 160~170g/eq, manufactured by Mitsubishi Chemical Corporation)

‧ hardener: boron trifluoride piperidine (manufactured by Stella-Chemifa)

‧Solvent: α-terpineol (manufactured by Yasuhara Chemical Co., Ltd.)

‧ resin Resin B1: 217Flake [weight average molecular weight: 2000, hydroxyl content: 7 wt%, phenyl content: 100 mol%, average molecular formula: (PhSiO _3/2 ) _1.0 (HO _1/2 ) _0.57 , Dow Corning Toray Company manufacturing]

‧ 20 g of epoxy decane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of 矽 resin B2: 217Flake (manufactured by Dow Corning Toray Co., Ltd.), and subjected to co-existing acetic acid catalyst for 4 hours at 80 ° C in toluene. A synthetic product obtained after the reaction (weight average molecular weight: 2000 to 3000, phenyl content: 90 mol%, epoxy group content: 10 mol%)

‧Anthracene resin B3: R10330 [weight average molecular weight: 3000~4000, vinyl content: 7 mol%, average molecular formula: (Me ₃ SiO _1/2 ) _0.13 (SiO ₄ ) _0.8 (ViMe ₂ SiO _1/2 ) _0.07 , manufactured by Bluestar Silicones

‧Organic polyoxyalkylene 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.)

‧ Polyimine oxime resin Y: X-22-8904 [manufactured by Shin-Etsu Chemical Co., Ltd.]

As is apparent from the results shown in the first table, in Comparative Examples 2 and 3 prepared by using an organopolysiloxane having no phenyl group or vinyl group, Comparative Example 1 prepared by using no organic polyoxane was used. Although the contact resistance and adhesion are improved, they are not sufficient.

On the other hand, in Examples 1 to 7 prepared by using an organic polysiloxane having a phenyl group or a vinyl group, both the contact resistance and the adhesion were good while maintaining a low volume resistivity.

Further, from the comparison between Examples 1 to 5 and Example 6, it is understood that when an epoxy resin is used as the curable resin, or when the organopolysiloxane has an epoxy group, the contact resistance and adhesion after the moisture resistance test are also good. Further, although not shown in the first table, it is also known that the conductive films produced in Examples 1 to 5 have high strength.

In addition, when the content of the organopolysiloxane is 0.1 to 10.0 parts by mass based on 100 parts by mass of the conductive particles, the volume resistivity is low and the contact resistance is also low.

100‧‧‧Solar battery unit

11‧‧‧n type single crystal germanium substrate

12a, 12b‧‧‧i type amorphous layer

13a‧‧‧p-type amorphous layer

13b‧‧‧n type amorphous layer

14a, 14b‧‧‧Transparent conductive layer

15a, 15b‧‧‧ collector electrode

Claims (13)

A conductive composition containing conductive particles (A) and an organic polyoxyalkylene (B) having a phenyl group and/or a vinyl group. The conductive composition of claim 1, further comprising a curable resin (C) other than the organopolysiloxane (B). The conductive composition of claim 2, wherein the curable resin (C) is an epoxy resin. The conductive composition according to any one of claims 1 to 3, wherein the conductive particles (A) are silver particles and/or copper particles. The electroconductive composition according to any one of claims 1 to 3, wherein the organopolyoxane (B) further has an epoxy group. The conductive composition of claim 4, wherein the organopolyoxane (B) further has an epoxy group. The conductive composition according to any one of claims 1 to 3, wherein the content of the organopolysiloxane (B) is 0.1 to 10 parts by mass based on 100 parts by mass of the conductive particles (A). The conductive composition of claim 4, wherein the organopolysiloxane (B) content is 0.1 to 10 parts by mass based on 100 parts by mass of the conductive particles (A). The conductive composition of claim 5, wherein the organopolysiloxane (B) content is 0.1 to 10 parts by mass based on 100 parts by mass of the conductive particles (A). The conductive composition of claim 6, wherein the organopolysiloxane (B) content is 100 parts by mass relative to the conductive particles (A) 0.1 to 10 parts by mass. A solar cell unit using the electroconductive composition according to any one of claims 1 to 10 for a collector electrode. The solar cell unit of claim 11, which is provided with a transparent conductive layer as a base layer of the collector electrode. A solar cell module using a solar cell unit as claimed in claim 11 or 12.