JP5656380B2 - Conductive ink composition, solar cell using the composition, and method for producing solar cell module - Google Patents

Description

The present invention relates to a conductive ink composition used for forming an electrode such as an electronic component or electric wiring. More particularly, relates to a process for the preparation of the electric wire, or a solar cell electrode solar cell and a solar cell module had use a suitable conductive ink composition may be used and the composition for the formation of the solar cell module It is.

  A method of forming an electrode or an electric wiring by applying or printing a conductive ink composition on a substrate such as a film, a substrate, or an electronic component, and then drying and curing by heating is widely used. ing. However, with the recent improvement in performance of electronic devices, electrodes and electrical wiring formed using conductive ink compositions are required to have lower resistance and higher reliability, and the demand is increasing year by year. It's getting on.

  In the field of solar cells, in a photovoltaic device comprising a photoelectric conversion layer made of a crystalline semiconductor substrate or the like having a textured structure formed on the surface, and a collector electrode provided on the photoelectric conversion layer, the collector electrode is Therefore, it is required to make the electrode width as thin as possible and design the resistance as small as possible. In general, solar cells are classified into a crystalline single crystal type or a polycrystalline type, an amorphous type, a compound type, a hybrid type, and the like depending on the type of material used.

  1 and 2 are schematic views showing an example of a solar battery cell in a hybrid solar battery. FIG. 2 is a plan view seen from the light receiving surface side, and FIG. 1 is a cross section taken along line AA in FIG. FIG. As shown in FIG. 1, a solar cell in a hybrid solar cell has an amorphous amorphous silicon layer 12 formed on the light-receiving surface side of an n-type single crystal silicon substrate 11, and ITO is formed on the amorphous silicon layer 12. A collecting electrode 14 is formed on the transparent electrode 13 and the transparent electrode 13. On the other hand, an amorphous silicon layer 16 and a transparent electrode 17 are formed on the back surface of the substrate opposite to the light receiving surface. In general, the surface on which the collecting electrode 14 is formed has a textured structure having an uneven shape in order to obtain a light confinement effect.

  As shown in FIG. 2, the collector electrode 14 is generally composed of a bus bar portion 14a and finger portions 14b. The collector electrode 14 absorbs as much light as possible into the n-type single crystal silicon substrate or the like, which is a photoelectric conversion layer. Since it is required to take out electric power without loss, it is required to reduce the electrode width, particularly the electrode width of the finger portion 14b, to secure a wider area of the light receiving surface, and to further reduce the resistance.

  In order to realize such thinning and low resistance of the electrode width of the collecting electrode, for example, the collecting electrode contains a granular conductive filler and a flaky conductive filler, and among these, the granular conductive filler for the entire conductive filler A photovoltaic element formed using a conductive paste having a content of 40% by weight or more is disclosed (for example, see Patent Document 1). The collector electrode constituting this photovoltaic element is generally formed using a screen printing method, but if the conductive paste contains a lot of flaky conductive filler, the screen plate is likely to be clogged, An object of the present invention is to solve the conventional problem that the printed pattern is faint or disconnected and it is difficult to make the line thin.

JP 2002-76398 A (Claim 1)

  However, in the invention described in Patent Document 1, the flakes of the flaky conductive filler contained in the conductive paste are used so that good conductivity is not impaired by reducing the content of the flaky conductive filler. The diameter (the longest length of the flake plane) is 5 μm or more, preferably 6 to 8 μm, and a conductive filler having a relatively large flake diameter must be used. For this reason, when the conductive paste is printed using a screen printing method or the like, it is difficult to print a fine pattern, and the effect of thinning the electrode width of the formed electrode is not sufficient.

  It is an object of the present invention to further reduce the electrode width and reduce the resistance of an electrode or an electrical wiring, particularly a solar cell collector electrode, and sufficient adhesion even in a narrow and narrow contact area. Another object of the present invention is to provide a conductive ink composition capable of forming a highly reliable electrode having excellent heat resistance and water resistance.

Another object of the present invention is to provide a solar cell having an electrode formed using the conductive ink composition and having high photoelectric conversion efficiency, and a method for producing a solar cell module including the solar cell. It is in.

Still another object of the present invention is to provide a method for producing a solar cell module having an electrical wiring formed using the conductive ink composition and having high photoelectric conversion efficiency.

1st viewpoint of this invention consists of an organic vehicle containing electroconductive particle, a thermosetting resin composition, a hardening | curing agent, and a solvent, and it electrically joins the collector electrode or photovoltaic cell of photovoltaic cells. In the conductive ink composition used for forming the lead wire, the conductive particles are nano silver particles having an average particle size of 1 nm or more and less than 100 nm and flaky conductive particles having an average flake size of 0.1 μm or more and 1.0 μm or less And the conductive particles contain more flaky conductive particles in a mass ratio than the nano silver particles, and the conductive particles are spherical conductive particles having an average particle size of 0.1 to 0.5 μm. In addition, the conductive particles contain 50 to 95% by mass of flaky conductive particles, the conductive particles contain 1 to 10% by mass of nano silver particles, and the nano silver particles are spherical and anisotropic other than spherical. And heat hardened The content ratio of the conductive resin composition to the conductive particles is 2 to 15:75 to 95 by mass ratio, the flaky conductive particles are Ag particles, the spherical conductive particles are Ag particles, and the thermosetting resin. Lewis acid containing epoxy resin composition, 20-40 parts by mass of epoxy resin composition with respect to 100 parts by mass of solvent, and curing agent containing imidazoles, tertiary amines, or boron fluoride Or a compound thereof.

A second aspect of the present invention is an invention based on the first aspect, and is characterized in that after being applied to a substrate, it is heat-cured within a temperature range of 100 to 280 ° C.

The 3rd viewpoint of this invention is a manufacturing method of the photovoltaic cell which forms a collector electrode using the conductive ink composition based on the 1st or 2nd viewpoint.

A fourth aspect of the present invention is the invention based on the third aspect, and is characterized in that a collecting electrode is further formed on the transparent conductive layer.

The 5th viewpoint of the present invention is a solar cell module provided with the photovoltaic cell of the 3rd or 4th viewpoint.

A sixth aspect of the present invention is a solar cell module in which a lead wire is formed using the conductive ink composition of the first or second aspect .

According to the conductive ink composition of the present invention, the conductive ink composition is composed of an organic vehicle containing conductive particles and a thermosetting resin composition, a curing agent and a solvent. In a conductive ink composition used for formation of a lead wire to be bonded, a conductive silver particle having a mean particle diameter of 1 nm or more and less than 100 nm and a flake shape having an average flake diameter of 0.1 μm or more and 1.0 μm or less Conductive particles, the conductive particles contain more flaky conductive particles in a mass ratio than the nano silver particles, and the conductive particles have a spherical conductivity with an average particle size of 0.1 to 0.5 μm. Further containing conductive particles, the conductive particles contain 50 to 95% by mass of flaky conductive particles, the conductive particles contain 1 to 10% by mass of nanosilver particles, the nanosilver particles are spherical, and other than spherical With anisotropic particles And the content ratio of the thermosetting resin composition and the conductive particles is 2 to 15:75 to 95 by mass ratio, the flaky conductive particles are Ag particles, and the spherical conductive particles are Ag particles, The thermosetting resin composition is an epoxy resin composition, containing 20 to 40 parts by mass of the epoxy resin composition with respect to 100 parts by mass of the solvent, and the curing agent is imidazoles, tertiary amines, or boron fluoride. In the formation of an electrode or electrical wiring, particularly, a collector electrode of a solar cell, the electrode width can be further reduced and the resistance can be reduced. In addition, it is possible to form a highly reliable electrode having sufficient adhesion even in a narrow and narrow adhesion area and having excellent heat resistance.
Since the collector electrode formed using the conductive ink composition of the present invention has a narrower electrode width and a lower resistance, a solar cell provided with this electrode and a solar cell provided with the solar cell The battery module can obtain high photoelectric conversion efficiency.
Moreover, since the lead wire formed using the conductive ink composition of the present invention has a lower resistance than the conventional one, a solar cell module provided with this lead wire can obtain high photoelectric conversion efficiency.

The figure which shows the cross section of the AA line of FIG. The schematic diagram showing an example of the plane of a photovoltaic cell. The top view which shows the outline of an example of a solar cell module.

Next, the form for implementing this invention is demonstrated.
The conductive ink composition of the present invention contains conductive particles and an organic vehicle containing a heat curable resin composition, a curing agent and a solvent. The conductive particles contain nano silver particles having an average particle diameter of 1 nm or more and less than 100 nm and flaky conductive particles having an average flake diameter of 0.1 μm or more and 1.0 μm or less .

  In the conductive ink composition of the present invention, since the nanosilver particles are sintered at a relatively low temperature by containing the nanosilver particles as the conductive particles, the gap between the conductive particles is filled. Even if the average flake diameter of the particles is made smaller than before, high conductivity can be maintained. In addition, since flaky conductive particles with a small average flake diameter can be used, problems such as screen clogging that occur when printing using the screen printing method are eliminated without reducing the content of flaky conductive particles. Is done.

The average particle diameter of the nano silver particles is in the above range because if it is less than 1 nm, it becomes an unstable material in which strong aggregation or the like is likely to occur, and if it is 100 nm or more, when it is baked at a low temperature around 100 to 150 ° C., This is because the silver particles are not sufficiently sintered at a low temperature, and it is difficult to obtain the effects of the present invention. Among these, the average particle diameter of the nano silver particles is preferably 5 to 90 nm. The average flake diameter of the flaky conductive particles is within the above range because the specific surface area increases when the average flake diameter of the flaky conductive particles is less than 0.1 μm, and the viscosity of the composition increases. This is because it is difficult to obtain the effect of obtaining high conductivity by passing the flaky conductive particles. On the other hand, Exceeding 1.0 [mu] m, or it is difficult to reduce the resistance of the electrode to be formed, also when printing using a screen printing method or the like, cause screen clogging, causing printing defects such as thin spots . Among these, the flake diameter of the flaky conductive particles is preferably 0.15 to 1.0 μm.

The conductive ink composition of the present invention as the conductive particles, in addition to the nano silver particles and flaky conductive particles, further including a spherical conductive particles having an average particle size of 0.1 to 3 m. By further including the spherical conductive particles, the gaps between the conductive particles gather more closely, and the conductivity is further improved. If the average particle size of the spherical conductive particles exceeds 3 μm, the composition has a low viscosity due to the inclusion of many particles having a large particle size, so that the pattern shape after printing collapses and bleeding occurs, which is not preferable. Among these, the average particle diameter of the spherical conductive particles further contained is particularly preferably 0.1 to 2.0 μm. In addition, since the conductive particles are closely gathered and suitable for ensuring high conductivity, the average particle diameter of the spherical conductive particles further contained is smaller than the average flake diameter of the flaky conductive particles. It is particularly preferred. Here, the average particle diameter of nano silver particles and spherical conductive particles and the average flake diameter of flaky conductive particles are measured with a laser diffraction / scattering type particle size distribution measuring device (LA-950, manufactured by Horiba, Ltd.) The 50% average particle diameter (D ₅₀ ) calculated using the particle diameter standard as the number. The number-based average particle diameter or the average flake diameter measured by this laser diffraction / scattering particle size distribution analyzer is an arbitrary value of 50 in an image observed with a scanning electron microscope (S-4300SE and S-900, manufactured by Hitachi High-Technologies Corporation). The average particle diameter or the average flake diameter when the particle diameter is actually measured for each particle is almost the same. Whether it is flaky or spherical is determined to be flaky if the aspect ratio (diameter / thickness) identified by the image observed with the scanning microscope is 2 or more, and is identified as spherical if it is less than 2 . The average flake diameter of the flaky conductive particles refers to the average value of the diameter (major axis) of the flaky conductive fine particles. The aspect ratio (diameter / thickness) of the flaky conductive particles is preferably in the range of 2-20. The thickness is preferably in the range of 0.005 to 1.5 μm, and particularly preferably in the range of 0.005 to 0.5 μm.

The conductive particles contain more flaky conductive particles in a mass ratio than the nano silver particles. That is, the conductive particles contain 50% by mass or more of the flaky conductive particles. When the flaky conductive particles are less than 50% by mass, the conductivity is lowered. Of these, conductive particles of the flaky conductive particles containing 50 to 95 wt%, is good preferable to contain 65 to 95 wt%. On the other hand, the nano silver particles are preferably contained in an amount of 1 to 10% by mass. Moreover, when further containing spherical electroconductive particle, it is preferable to contain 4-35 mass%.

The nanosilver particles contained as conductive particles, regardless of spherical, flaky or rodlike such anisotropic nanosilver particles free of the non-spherical. By including anisotropic nano silver particles, the effect of further improving the conductivity can be expected.

The flaky conductive particles contained in the conductive particles, because they hardly oxidized resistivity small, but that use Ag particles, in addition to Ag are used Au, Cu, Ni or Al alone Alternatively, these two or more types including Ag may be used in combination.

Further, the spherical conductive particles contained in the conductive particles, the reason that the resistivity hardly oxidized smaller, but that use Ag particles, in addition to Ag are used Au, Cu, Ni or Al alone Alternatively, these two or more types including Ag may be used in combination.

The organic vehicle constituting the conductive ink composition of the present invention contains a heat curable resin composition, a curing agent and a solvent.
For the thermosetting resin composition constituting the organic vehicle, an epoxy resin composition is used because it is necessary to express high adhesion in a collector electrode that is further thinned and has a narrow adhesion area. We want to use. Suitable epoxy resin compositions include bisphenol A type, bisphenol F type, biphenyl type, biphenyl mixed type, cresol novolac type, naphthalene type, dicyclopentadiene type and the like. Of these, biphenyl type or biphenyl mixed type epoxy resins are particularly preferable. Examples of the biphenyl type epoxy resin include a biphenol glycidyl ether type epoxy resin (Nippon Kayaku Co., Ltd .: NC-3000, NC-3000L, Japan Epoxy Resin Co., Ltd .: YX4000, YL6640, etc.). The biphenyl mixed type includes an epoxy resin (manufactured by Nippon Kayaku Co., Ltd .: CER-1020, etc.) obtained by mixing polyglycidyl ether of o-cresol novolac and biphenol glycidyl ether. Among the epoxy resin compositions, those having a property of being solid at room temperature and having a melt viscosity at 150 ° C. of 0.1 Pa · s or less are particularly preferable. The reason for this is that the reaction with the curing agent can be carried out instantaneously, and it is suitable for developing high adhesion and reducing the specific resistance. On the other hand, if the melt viscosity at 150 ° C. exceeds 0.1 Pa · s, the curing reaction does not proceed instantaneously, and problems such as poor adhesion are likely to occur. The value of the melt viscosity shown here is a value measured using, for example, a cone and plate type ICI viscometer (manufactured by Research Equipment London).

  As the curing agent, commonly used imidazoles, tertiary amines, Lewis acids containing boron fluoride, or compounds thereof are suitable. Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4. -Methyl-5-hydroxymethylimidazole or 2-phenylimidazole isocyanuric acid adduct is exemplified. Tertiary amines include piperidine, benzyldiamine, diethylaminopropylamine, isophoronediamine or diaminodiphenylmethane. The Lewis acid containing boron fluoride includes an amine complex of boron fluoride such as boron fluoride monoethylamine. Further, a curing agent having a high potential such as dicyandiamide (DICY) may be used, and the above curing agent may be combined as an accelerator. Of these, imidazoles such as 2-ethyl-4-methylimidazole, 2-phenylimidazole, or 2-phenyl-4,5-dihydroxymethylimidazole are particularly preferred for the purpose of improving adhesion.

As the solvent, dioxane, hexane, toluene, methyl cellosolve, cyclohexane, diethylene glycol dimethyl ether, dimethylformamide, N-methylpyrrolidone, diacetone alcohol, dimethylacetamide, γ-butyrolactone, butyl carbitol, butyl carbitol acetate, ethyl carbitol, ethyl carbitol acetate, butyl cellosolve, butyl cellosolve acetate, ethyl cellosolve, alpha-terpineol, and the like. Of these, ethyl carbitol acetate, butyl carbitol acetate, and α-terpineol are particularly preferable.

The conductive ink composition of the present invention is prepared, for example, by the following method.
First, preferably at a temperature 20 to 30 ° C., further preferably of 25 ° C. Conditions, to the solvent 100 parts by weight, preferably 10 to 50 parts by weight of the thermosetting resin composition, more preferably 20 to 40 weight Parts are mixed, and then an appropriate amount of the curing agent is mixed to prepare an organic vehicle. Further, as the conductive particles, the nano silver particles and the flaky conductive particles, or the nano silver particles and the flaky conductive particles, and further the spherical conductive particles are mixed and sufficiently mixed. prepare. Next, the conductive ink composition is prepared by kneading the prepared organic vehicle and the conductive particles with a kneader such as a three-roll mill to form a paste. At this time, in order to give a suitable viscosity and necessary fluidity to the prepared conductive ink composition, the organic vehicle is mixed at a ratio of 5 to 30% by mass and the conductive particles at a ratio of 70 to 95% by mass. It is preferable to do this. When the organic vehicle is less than the lower limit of 5% by mass, that is, when the conductive particles exceed 95% by mass, it is difficult to obtain suitable fluidity as an ink composition, while the organic vehicle has an upper limit of 30% by mass. This is because, if the conductive particles are less than 70% by mass, the conductive particles are insufficient and it is difficult to obtain good conductivity. Among these, it is particularly preferable to mix the organic vehicle in an amount of 8 to 20% by mass and the conductive particles in an amount of 80 to 92% by mass.

Further, the content ratio of the heat curable resin composition and the conductive particles in the conductive ink composition is preferably 2 to 15:75 to 95 in terms of mass ratio because it is suitable for forming a highly conductive electrode. der Ru. Of these, good Mashiku is, 2 to 7: A 83-95.

  The conductive ink composition of the present invention thus prepared has an appropriate viscosity of 30 to 200 Pa · s. Thereby, when applying to a board | substrate etc. using a screen printing method, a fine pattern can be printed, without producing a disorder | damage | disturbance of a shape and a fading. Moreover, after apply | coating or printing on the laminated body etc. in a board | substrate or a photovoltaic cell, Preferably it has a property hardened | cured at the temperature of 100-280 degreeC, More preferably, 150-220 degreeC. If it is less than 100 degreeC, hardening will become inadequate. Moreover, in the case of a hybrid solar cell, when it is baked at a temperature exceeding 280 ° C., the performance of the solar cell is hindered.

  The conductive ink composition of the present invention can be suitably used for forming electrodes or electrical wiring, in particular, collecting electrodes of solar cells in a solar cell module, or lead wires. For example, as shown in FIG. 2 schematically showing the plane of the solar battery cell, the collector electrode of the solar battery cell includes two bus bar portions 14a and a plurality of finger portions 14b perpendicular to the bus bar portion 14a. With.

  The electrode width of the collector electrode, particularly the electrode width of the finger portion, is required to be as thin as possible in order to irradiate more light onto the light receiving surface. In the conductive ink composition of the present invention, Since flaky conductive particles having an average flake diameter of 0.1 μm or more and less than 3 μm are used as compared with conventional ones, a fine pattern can be printed, and the solar cell collector electrode to be formed is further improved Thinning is possible. Further, by using flaky conductive particles having a small flake diameter, problems such as screen clogging, which has been a problem in the prior art when printing using the screen printing method, are solved. The conductive ink composition of the present invention uses flaky conductive particles having a smaller average flake diameter than conventional ones, but the nano silver particles are sintered at a relatively low temperature, and the conductive particles are Therefore, high conductivity can be maintained. Furthermore, since an epoxy resin with high adhesiveness is used, high adhesion can be obtained even in a narrower and narrower adhesive area.

  A solar battery cell having a collector electrode formed by using the conductive ink composition of the present invention and a solar battery module having the solar battery cell receive more light on the light receiving surface by thinning the collector electrode. Since it can be irradiated and absorbed in the photoelectric conversion layer, high photoelectric conversion efficiency is obtained.

  As shown in FIG. 3, generally, the solar cell module 30 is formed by electrically connecting the solar cells 32 to each other by lead wires 31. Since this lead wire is required to have a lower resistance in order to enhance the characteristics of the solar cell module, a copper foil is usually used, and this copper foil is covered with solder or the like. Since the conductive ink composition of the present invention can be used as a substitute for the copper foil in the lead wire and can be formed by a printing method, a low resistance lead wire can be formed by a simple method.

  A solar cell in which a collecting electrode is formed using the conductive ink composition of the present invention or a solar cell module provided with this solar cell has high photoelectric conversion efficiency.

  Moreover, since the solar cell module in which the lead wire is formed using the conductive ink composition of the present invention has a lower resistance than the lead wire formed from a conventional copper foil or the like, high photoelectric conversion efficiency is obtained.

Next, examples of the present invention will be described in detail together with reference examples and comparative examples. In addition, Example 6 shown below is a reference example.

  First, 30 mass parts of epoxy resin is mixed with 100 mass parts of butyl carbitol acetate under the condition of a temperature of 25 ° C., and an organic vehicle is prepared by adding an appropriate amount of 2-ethyl-4-methylimidazole to the mixture. did. Next, 20% by mass of the obtained organic vehicle and 80% by mass of the silver particles were kneaded with a three-roll mill and formed into a paste to prepare a conductive ink composition.

  Next, the obtained conductive ink composition was applied by printing on a 100 × 100 mm square glass substrate using a screen printing method, and then the glass substrate was put into a hot air circulating furnace, at a temperature of 200 ° C. for 30 minutes. Firing was performed to form a 10 × 10 mm square electrode.

< Reference Example 2>
An organic vehicle was prepared as 25 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as a conductive particle, a flaky conductive material having an average flake diameter of 0.5 μm The use of silver particles consisting of 95% by mass of particles and 5% by mass of nano silver particles having an average particle diameter of 20 nm, the content of conductive particles being 90% by mass, and the content of organic vehicle being 10% by mass Except for the above, a conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1.

<Example 1 >
Preparation of organic vehicle as epoxy resin 35 parts by mass with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, flaky conductive having an average flake diameter of 0.5 μm 80% by mass of particles, 5% by mass of nano silver particles having an average particle diameter of 50 nm, silver particles composed of 15% by mass of spherical conductive particles having an average particle diameter of 0.2 μm, and 88% by mass of the conductive particles. %, A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1 except that the content of the organic vehicle was 12% by mass.

<Example 2 >
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.5 μm 90% by mass of particles, 5% by mass of nano silver particles having an average particle size of 20 nm, 5% by mass of spherical conductive particles having an average particle size of 0.3 μm, and 90% by mass of conductive particles. %, A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1, except that the organic vehicle content was 10% by mass.

<Example 3 >
Preparation of organic vehicle as epoxy resin 35 parts by mass with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, flaky conductive having an average flake diameter of 0.5 μm Except for using 70% by mass of particles, 10% by mass of nano silver particles having an average particle size of 80 nm, and 20% by mass of spherical conductive particles having an average particle size of 0.1 μm, and the content ratio of conductive particles. A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1 except that 88% by mass and the content of the organic vehicle were 12% by mass.

<Example 4 >
An organic vehicle was prepared as 20 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 1.0 μm. 80% by mass of particles, 5% by mass of nano silver particles having an average particle size of 20 nm, 15% by mass of spherical conductive particles having an average particle size of 0.5 μm, and 85% by mass of conductive particles. %, A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1 except that the organic vehicle content was 15% by mass.

<Example 5 >
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.2 μm Similar to Reference Example 1, except that silver particles comprising 70% by mass of particles, 10% by mass of nano silver particles having an average particle size of 40 nm, and 20% by mass of spherical conductive particles having an average particle size of 0.1 μm were used. An ink composition was prepared to form an electrode.

<Example 6 >
An organic vehicle was prepared as 40 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 2.0 μm 80% by mass of particles, 10% by mass of nano silver particles having an average particle size of 70 nm, 10% by mass of spherical conductive particles having an average particle size of 0.5 μm, and 90% by mass of the conductive particles. %, A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1, except that the organic vehicle content was 10% by mass.

<Comparative Example 1>
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 10.0 μm A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1 except that silver particles composed of 93% by mass of particles and 7% by mass of nanosilver particles having an average particle diameter of 50 nm were used.

<Comparative example 2>
An organic vehicle was prepared as 25 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.05 μm The use of silver particles composed of 95% by mass of particles and 5% by mass of nano silver particles having an average particle size of 20 nm, the content of conductive particles being 88% by mass, and the content of organic vehicles being 12% by mass Except for the above, a conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1.

<Comparative Example 3>
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.5 μm The use of silver particles composed of 30% by mass of particles and 70% by mass of nano silver particles having an average particle size of 50 nm, the content of conductive particles being 75% by mass, and the content of organic vehicles being 25% by mass Except for the above, a conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1.

<Comparative Example 4>
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.5 μm Similar to Reference Example 1, except that silver particles composed of 100% by mass of the particles were used, the content of the conductive particles was 88% by mass, and the content of the organic vehicle was 12% by mass. An ink composition was prepared to form an electrode.

<Comparative Example 5>
An organic vehicle was prepared as 30 parts by mass of an epoxy resin with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, a flaky conductive material having an average flake diameter of 0.5 μm 70% by mass of particles, 10% by mass of nano silver particles having an average particle diameter of 50 nm, 20% by mass of spherical conductive particles having an average particle diameter of 5.0 μm, and 88% by mass of the conductive particles. %, A conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1 except that the content of the organic vehicle was 12% by mass.

<Comparative Example 6>
Preparation of organic vehicle as epoxy resin 35 parts by mass with respect to 100 parts by mass of butyl carbitol acetate, and as shown in Table 1 below, as conductive particles, flaky conductive having an average flake diameter of 2.0 μm 80% by mass of particles, 20% by mass of silver conductive particles having an average particle size of 0.5 μm were used, 90% by mass of the conductive particles, and 10% by mass of the organic vehicle. Except for the above, a conductive ink composition was prepared and an electrode was formed in the same manner as in Reference Example 1.

＜比較試験及び評価＞
実施例１〜６、参考例１，２及び比較例１〜６で得られた導電性インク組成物について粘度、スクリーン印刷性、スクリーン目詰まり及び最小線幅を評価した。また実施例１〜６、参考例１，２及び比較例１〜６の導電性インク組成物を用いて形成された電極について比抵抗を評価した。その結果を以下の表２に示す。
（１）粘度：レオメータ（ティー・エー・インスツルメント社製 ＡＲ１０００）を用いて、４００ｍｍコーンを使用し、ずり速度１０Ｓ^-1とした時の値を測定した。
（２）スクリーン印刷性：スクリーン印刷法により１００×１００ｍｍ角のガラス基板上に印刷されたパターンについて、パターン形状が確認できた場合を「良好」とし、印刷時のかすれ等でパターン形状が僅かに乱れた場合を「可」とし、また印刷時にレオロジー特性の関係からパターンが全く印刷できなかったり、著しいかすれによりライン欠損が全体にわたってみられた場合を「不可」とした。
（３）スクリーン目詰まり：スクリーン版が目詰まりして連続印刷が困難な場合、又はライン形状に目詰まりによる未塗布箇所がみられた場合を「有」とし、未塗布箇所がみられなかった場合を「無」とした。
（４）最小線幅：４０、５０、７０、１００、１５０及び２００μｍの線幅で開口部が設計されたスクリーン版を用いて１００×１００ｍｍ角のガラス基板上にパターンを印刷し、ラインが重ならずに乱れることなく印刷できた最小の線幅を最小線幅とした。
（５）比抵抗：１００×１００ｍｍ角のガラス基板上に形成された１０×１０ｍｍ角の電極について、表面固有抵抗表面抵抗計（三菱化学社製：ローレスタ）にて四端子四探針方式を用いて測定した表面抵抗値と、レーザー顕微鏡（キーエンス社製：ＶＫ−９６００）を用いて測定した膜厚の値から、電極の比抵抗値（Ω・ｃｍ）を算出した。

<Comparison test and evaluation>
The conductive ink compositions obtained in Examples 1 to 6, Reference Examples 1 and 2, and Comparative Examples 1 to 6 were evaluated for viscosity, screen printability, screen clogging, and minimum line width. Moreover, specific resistance was evaluated about the electrode formed using the conductive ink composition of Examples 1-6 , Reference Examples 1 and 2, and Comparative Examples 1-6. The results are shown in Table 2 below.
(1) Viscosity: Using a rheometer (AR1000 manufactured by TA Instruments), a 400 mm cone was used, and the value at a shear rate of 10S ^-1 was measured.
(2) Screen printability: The pattern printed on a 100 × 100 mm square glass substrate by the screen printing method is defined as “good” when the pattern shape can be confirmed, and the pattern shape is slightly due to blurring during printing. The case where it was disturbed was determined as “Yes”, and the case where the pattern could not be printed at all due to the rheological characteristics at the time of printing, or the case where the line defect was observed over the entire area due to significant blur was determined as “Not possible”.
(3) Screen clogging: When the screen plate is clogged and continuous printing is difficult, or when there is an uncoated part due to clogging in the line shape, “Yes” is indicated, and no uncoated part is seen The case was set to “None”.
(4) Minimum line width: A pattern is printed on a 100 × 100 mm square glass substrate using a screen plate with openings designed with line widths of 40, 50, 70, 100, 150 and 200 μm. The minimum line width that could be printed without being disturbed was defined as the minimum line width.
(5) Specific resistance: For a 10 × 10 mm square electrode formed on a 100 × 100 mm square glass substrate, a four-terminal four-probe method is used with a surface resistivity meter (Mitsubishi Chemical Corporation: Loresta). The specific resistance value (Ω · cm) of the electrode was calculated from the measured surface resistance value and the film thickness value measured using a laser microscope (manufactured by Keyence Corporation: VK-9600).

表２から明らかなように、実施例１〜６、参考例１，２及び比較例１〜６を比較すると、実施例１〜６、参考例１，２では適切な粘度が得られ、スクリーン目詰まりも無く、スクリーン印刷性においても高い評価が得られた。また最小線幅についても、実施例５、７及び８では比較例４〜６と同等の結果に留まったものの、実施例１，２及び４、参考例１，２では、すべての比較例よりも優れた結果を示した。

As is clear from Table 2, when Examples 1 to 6, Reference Examples 1 and 2 and Comparative Examples 1 to 6 are compared, suitable viscosity is obtained in Examples 1 to 6 and Reference Examples 1 and 2 , and There was no clogging, and high evaluation was obtained in screen printability. Also, the minimum line widths were the same as those of Comparative Examples 4 to 6 in Examples 5, 7 and 8, but in Examples 1 , 2 and 4, and Reference Examples 1 and 2 , compared to all the comparative examples. Excellent results were shown.

Moreover, the specific resistance of the electrodes formed in Examples 1 to 6 and Reference Examples 1 and 2 was much lower than the electrodes formed in Comparative Examples 1 to 6, and it was confirmed that high conductivity was obtained. .

Claims (6)

Conductive particles are made of an organic vehicle containing conductive particles, a thermosetting resin composition, a curing agent, and a solvent, and are used for forming a collector electrode of solar cells or a lead wire that electrically joins the solar cells. In the ink composition,
The conductive particles contain nano silver particles having an average particle diameter of 1 nm or more and less than 100 nm and flaky conductive particles having an average flake diameter of 0.1 μm or more and 1.0 μm or less,
The conductive particles contain more flaky conductive particles in a mass ratio than the nano silver particles,
The conductive particles further include spherical conductive particles having an average particle size of 0.1 to 0.5 μm,
The conductive particles contain 50 to 95% by mass of flaky conductive particles,
The conductive particles contain 1 to 10% by mass of nano silver particles,
The nano silver particles include spherical and anisotropic particles other than spherical,
The content ratio of the thermosetting resin composition and the conductive particles is 2 to 15:75 to 95 by mass ratio,
The flaky conductive particles are Ag particles,
The spherical conductive particles are Ag particles,
The thermosetting resin composition is an epoxy resin composition, containing 20 to 40 parts by mass of the epoxy resin composition with respect to 100 parts by mass of the solvent,
The conductive ink composition, wherein the curing agent is an imidazole, a tertiary amine, a Lewis acid containing boron fluoride, or a compound thereof.   The conductive ink composition according to claim 1, wherein the conductive ink composition is heat-cured within a temperature range of 100 to 280 ° C. after being applied to the substrate.   The manufacturing method of the photovoltaic cell which forms a collector electrode using the electroconductive ink composition of Claim 1 or 2.   The manufacturing method of the photovoltaic cell of Claim 3 which forms the said collector electrode on a transparent conductive layer.   The manufacturing method of the solar cell module using the photovoltaic cell obtained by the method of Claim 3 or 4.   A method for producing a solar cell module, wherein solar cells are electrically joined together by a lead wire formed using the conductive ink composition according to claim 1.

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