KR101431509B1 - Paste composition used for forming an electrode of solar cell - Google Patents

Abstract

The present invention relates to a paste composition for forming a solar cell electrode, which comprises a) a conductive powder, b) a cellulosic binder, c) an acrylate monomer, d) a radical polymerization initiator, and e) The paste composition for forming can be fired at a low temperature as compared with the conventional paste composition and has excellent curing degree, electrical resistivity characteristic and stability, and can be usefully used for forming electrodes or wiring of a solar cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a paste composition for forming a solar cell electrode,

The present invention relates to a paste composition for forming a solar cell electrode, and more particularly to a paste composition which can be fired at a low temperature and has excellent electrical resistivity characteristics and excellent stability and is usefully used for forming electrodes or wiring of a solar cell, Forming method.

Conventional electrodes or paste-forming paste compositions are prepared by mixing conductive powder, epoxy-based binder, curing agent, solvent, and the like.

When such a conventional paste composition is heated and cured, a urethane compound is produced. The resulting urethane compound has a problem of greatly lowering the adhesion and weldability of Ag particles mainly used as a conductive powder. In addition, such a conventional paste composition has a problem of spreading a line width due to a slow curing rate, making it difficult to realize a high-resolution electrode pattern (Korean Patent Laid-Open Nos. 10-2006-0049996 and 10-2008-0024444 And Japanese Patent Laid-Open Nos. 2005-268239, 2006-48149, and 2007-224191).

Accordingly, efforts have been made to develop paste compositions for electrodes or interconnects having high curability and excellent stability without deteriorating the adhesive force of the conductive powder by sorting organic materials such as a binder and a polymerization initiator used together with the conductive powder .

Accordingly, the present invention relates to a thermosetting paste composition which is capable of being fired at a low temperature as compared with a conventional electrode or a wiring-forming paste composition and has excellent hardness, electrical resistivity and stability and is usefully used for forming electrodes or wiring, Or a wiring forming method.

In order to achieve the above object,

a) conductive powder;

b) a cellulose-based binder;

c) an acrylate-based monomer;

d) a radical polymerization initiator; And

e) Solvent

The present invention provides a paste composition for forming a solar cell electrode.

Also,

A paste composition for forming a solar cell electrode on a substrate, followed by drying and firing.

Also,

And an electrode or wiring formed by the electrode or the wiring forming method.

In the paste composition for forming a solar cell electrode of the present invention,

(1) Since the printing characteristics are excellent, a high-resolution electrode pattern can be realized.

② It is possible to realize high aspect ratio due to excellent rheological characteristics.

③ Excellent electrical resistivity can be obtained even at low temperature (below 400 ℃) due to excellent curing degree.

④ It is excellent in storage stability because viscosity change is small.

⑤ High adhesion regardless of substrate material (polymer, glass, metal, ceramics, etc.) and can be applied to a wide range of applications (solar cell, RFID, PCB, etc.).

The paste composition for forming a solar cell electrode according to the present invention is characterized by comprising a) a conductive powder, b) a cellulosic binder, c) an acrylate monomer, d) a radical polymerization initiator, and e) Since the reaction temperature is 80-150 ° C, it does not spontaneously cure at room temperature, so there is no danger of storage deterioration at 80 ° C or lower and low temperature calcination at 150-400 ° C is possible.

The composition of the present invention preferably comprises a) 30 to 90% by weight of conductive powder, b) 1 to 30% by weight of a cellulose-based binder, c) 1 to 30% by weight of an acrylate monomer, d) 0.01 to 10% by weight of a radical polymerization initiator % And e) balance of solvent.

In the present invention, the a) conductive powder may be a conventional metal powder or metal powder used for forming an electrode or a wiring, and the most typical conductive powder may be silver (Ag) powder. The conductive powder used in the present invention may be a powder having an average particle diameter of 0.05 to 10 mu m, preferably 0.1 to 5 mu m.

In addition, two or more conductive powders may be used in combination. In this case, powders having a particle size of 0.05 to 1 占 퐉 and a powder having an average particle size of 1 to 10 占 퐉 may be mixed.

The shape of the conductive powder may be spherical, non-spherical or plate-like (flaky), and they may be used in combination of two or more kinds.

Specific examples of the cellulose-based binder in the present invention include methylcellulose, ethylcellulose, propylcellulose, nitrocellulose, cellulose acetate, cellulose propionate, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylhydroxypropylcellulose, , And ethyl cellulose may be preferably used.

In the present invention, specific examples of the c) acrylate monomer include methacrylic acid, methacrylate, ethylglycidylether methacrylate, propylglycidylether methacrylate, 2 or 4-bromobenzylmethacrylate, Hexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, ethyl isoamyl acrylate, butyl glycidyl ether methacrylate, Benzyl methacrylate, 2 or 4-methoxyphenyl methacrylate, 2 or 4-methoxybenzyl methacrylate, 2 or 4-methoxyphenyl methacrylate, tricyclodecyl methacrylate, phenyl methacrylate, Methoxyphenyl methacrylate, 2-or 4-ethoxybenzyl methacrylate, 2-or 4-chlorophenyl methacrylate , 2 or 4 chlorobenzyl methacrylate, 2 or 4-bromophenyl methacrylate, trimethylolpropane triacrylate, polyfunctional monomer, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3 -Butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylol trimethacrylate, trimethylol propane triceta acrylate, pentaerythritol trimethacrylate, di Trimethylolpropane tetramethacrylate, dipentaerythritol hexyl methacrylate, or a mixture thereof, preferably trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, Can be used.

As the d) radical polymerization initiator in the present invention, it is preferable to use a peroxide compound used in a radical polymerization reaction. Specific examples of such peroxide initiators include dilauryl peroxide, dibenzoyl peroxide, tert-butyl peroxyneodecanoate, tert-amyl peroxy pivalate, di (2-ethylhexyl) peroxydicarbonate, Di (3, 3, 5-trimethylhexanoyl) peroxide, tert-amyl peroxy Butylperoxy-2-ethylhexanoate, tert-butylperoxy-2-tylhexanoate, tert-butylisopropylmonoperoxycarbonate, tert-butylperoxy-2-ethylhexecarbonate, dibenzoyl peroxide, tert- Amyl (2-ethylhexyl) monoperoxycarbonate, tert-butylperoxide, tetrabutylperoxide, tert-butylperoxyisopropylcarbonate, tert-butylperoxybenzoate, 1,1,3,3-tetramethyl Butyl peroxyneodecanoate, dicumyl peroxide, didecanoyl peroxide Side or And mixtures thereof. Preferably, tert-butyl peroxide, tetrabutyl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyetecanoate can be used.

In addition, the paste composition for forming a solar cell electrode according to the present invention may further include, if necessary, additives other than the above-mentioned essential components, which can be usually contained in an electrode or a wire forming paste. Examples of such additives include plasticizers, thickeners, stabilizers, dispersants, defoamers, and surfactants. Each additive may be used in an amount of 0.01 to 10 wt% in the paste of the present invention.

The paste composition of the present invention can be prepared by uniformly mixing the conductive powder, the cellulose-based binder, the acrylate-based monomer, the radical polymerization initiator, and optional additives with a solvent in a blender or a three-roll kneader or the like within the above- .

The paste composition of the present invention may comprise a solvent in an amount to achieve a specific viscosity and preferably has a shear rate of 3.84 sec < ^-1 > at room temperature (25 [deg.] C) as a # 51 spindle using a Brookfield HBT viscometer The viscosity may be in the range of 1 to 300 Pa · S.

Examples of the solvent include terpineol, butyl carbitol acetate, butyl carbitol, ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, butylene glycol monomethyl ether, propylene glycol methyl ether, propylene glycol monomethyl ether Propionate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, dipropylene glycol monomethyl ether, dipropylene glycol methyl ether acetate, propylene glycol monomethyl ether propionate, ethyl ether propionate, propylene glycol monomethyl ether Acetate, dimethylamino formaldehyde, methyl ethyl ketone, gamma butyrolactone, ethyl lactate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Tessanol), toluene, 1- -2-propanol or a mixture thereof There.

The present invention also provides a method of forming a solar cell electrode or wiring by applying the paste composition onto a substrate, followed by drying and firing. The electrode or wiring may be an electrode or a wiring of a solar cell and the solar cell according to the present invention may be manufactured by a common material and method except that electrodes or wirings are formed using the paste composition according to the present invention have.

The electrode or wiring formed from the paste composition of the present invention may have a thickness of 3 to 50 mu m. Further, for example, in the case of a solar cell, the substrate may be a Si substrate coated with a front electrode (for example, Ag electrode) and dried. The application can be carried out by screen printing, and the drying is carried out at 60 to 150 DEG C for 3 to 30 minutes, And firing can be carried out at 150-400 DEG C for 5 to 60 minutes. Also, it can be carried out at a low temperature of 100-400 DEG C for 5 to 60 minutes by simultaneously performing drying and firing.

As described above, the paste composition for forming a solar cell electrode of the present invention has the following advantages;

① High resolution: It is easy to realize pattern with high resolution of 80 ㎛ or less because of excellent paste rheology.

(2) High aspect ratio: It is possible to realize a high aspect ratio pattern because of excellent screen mesh dropping during printing, so that excellent line resistance can be obtained even at high resolution.

③ Excellent electric resistance property even at low temperature hardening below 400 ℃: Even with a small amount of binder + monomer + polymerization initiator, it has excellent hardness and excellent electrical resistivity characteristics.

④ Excellent storage stability: The curing reaction is suppressed at room temperature, and the viscosity change is small at 25 ~ 40 ℃.

⑤ Because of its high hardness, it has excellent adhesion to all substrates used in electronic materials such as film, transparent conductive layer, silicon and glass, and can be applied effectively to a wide range of applications such as solar cell, RFID, and PCB.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

[Example]

Examples 1 to 3 and Comparative Examples 1 and 2

The components shown in the following Table 1 were mixed in a three-roll kneader using the corresponding amounts to prepare a desired paste composition.

Resistivity, viscosity change, resolution, aspect ratio, substrate adherence, and strength after firing were measured for the prepared paste composition, and the results of physical properties are also shown in Table 1 below.

Formulation (parts by weight) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Conductive powder Silver powder 30 70 85 30 85 Binder 1 Ethyl cellulose 10 6 2 - 2 Binder 2 Epoxy resin - - - 10 5 Hardener Amine system - - - One 0.5
Monomer Ethylene glycol dimethacrylate 6 3 4 - - Trimethylolpropane triacrylate 6 2 One - -
Polymerization initiator t-butyl peroxide One - - - - t-butyl peroxyneodecanoate - 0.5 0.5 - - Organic solvent 1 Terpineol 20 8 3 26 3 Organic solvent 2 Butyl carbitol acetate 20 8 3 26 3 Plasticizer Dibutyl phthalate 5 One - 5.5 - additive Defoaming agent One 0.5 0.5 0.5 0.5 Dispersant One One One One One



characteristic Resistivity (* 10 ^-6 Ω cm) Curing at 180 캜 for 30 minutes 26.4 18.3 13.5 325 114 Curing at 200 ° C for 30 minutes 15.7 10.2 7.18 275 25.5 Curing at 220 캜 for 30 minutes 10.2 9.4 6.4 87.9 15.4 Viscosity change rate (%) Viscosity change rate after storage at 25 ° C for 1 month 1.7 3.2 2.8 very
Hardening 32.3 Resolution (탆) Line width change rate after printing
Implemented within 10% 50 65 70 90 100 Aspect ratio (%) Pattern height after baking at 180 占 폚 / pattern line width ratio 16.49 22.23 27.66 5.13 13.1 Substrate adhesion Probe pressure transfer method 25N 25N 25N 10N 7N Strength after firing Pencil hardness measurement 4H 2H 2H H HB

From the above Table 1, it can be seen that the paste compositions of the present invention prepared in Examples 1 to 3 exhibit far superior electrical resistivity characteristics, stability, strength and substrate adhesion as compared to the compositions prepared in Comparative Examples 1 and 2, It can be seen that a high aspect ratio electrode pattern can be realized.

Claims (14)

A paste composition for forming a solar cell electrode which does not contain glass powder and can be fired at 100 to 400 占 폚,
a) 30 to 90 wt% of a conductive powder having an average particle diameter of 0.05 to 10 mu m;
b) a polymer selected from the group consisting of methylcellulose, ethylcellulose, propylcellulose, nitrocellulose, cellulose acetate, cellulose propionate, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylhydroxypropylcellulose and mixtures of two or more thereof 1 to 30% by weight of a cellulose-based binder;
c) 1 to 30% by weight of an acrylate monomer;
d) from 0.01 to 10% by weight of a peroxide radical polymerization initiator, and
e) a residual amount of a solvent. delete The method according to claim 1,
Wherein the conductive powder is a silver (Ag) powder. delete delete The method according to claim 1,
Wherein the acrylate monomer is selected from the group consisting of trimethylolpropane triacrylate, methacrylic acid, methacrylate, ethylglycidylether methacrylate, propylglycidylether methacrylate, 2- or 4- bromobenzylmethacrylate, hexyl Methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, ethyl isoamyl acrylate, butyl glycidyl ether methacrylate, Benzyl methacrylate, 2 or 4-methoxyphenyl methacrylate, 2 or 4-methoxybenzyl methacrylate, 2 or 4-ethoxy-2-methoxybenzyl methacrylate, tricyclodecyl methacrylate, phenyl methacrylate, Phenyl methacrylate, 2 or 4-ethoxy benzyl methacrylate, 2 or 4-chlorophenyl methacrylate 2 or 4 chlorobenzyl methacrylate, 2 or 4-bromophenyl methacrylate, trimethylol propane triacrylate, polyfunctional monomer, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylol trimethacrylate, trimethylol propane triceta acrylate, pentaerythritol trimethacrylate, Ditrimethylolpropane tetramethacrylate, dipentaerythritol hexyl methacrylate, and mixtures thereof. The paste composition for forming a solar cell electrode according to claim 1, The method according to claim 1,
Wherein the peroxide radical polymerization initiator is selected from the group consisting of tert-butyl peroxide, tetrabutyl peroxide, dilauryl peroxide, dibenzoyl peroxide, tert-butyl peroxyneodecanoate, tert-amyl peroxy pivalate, (3-methoxybutyl) peroxydicarbonate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, di (3,5,5-trimethylhexa Amyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl isopropyl monoperoxycarbonate, Butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate Dicumyl peroxide, dimethanoyl peroxide, and mixtures thereof. Wherein the composition is selected from the group consisting of: The method according to claim 1,
Wherein the composition further comprises a plasticizer, a thickener, a stabilizer, a dispersant, a defoamer, a surfactant, or a mixture thereof in an amount of 0.01 to 10% by weight. The method according to claim 1,
Wherein the paste has a viscosity of 1 to 300 PaS when measured at room temperature (25 캜). A method for forming a solar cell electrode comprising applying a paste composition for forming a solar cell electrode according to any one of claims 1, 3, and 6 to a substrate, followed by drying and firing. 11. The method of claim 10,
Wherein the firing is performed at a temperature in the range of 150 to 400 占 폚. 11. The method of claim 10,
Wherein the electrode has a thickness of 3 to 50 mu m Wherein the photovoltaic cell is a photovoltaic cell. delete delete