KR101566071B1 - Composition for forming solar cell electrode and electrode prepared using the same - Google Patents
Composition for forming solar cell electrode and electrode prepared using the same Download PDFInfo
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- KR101566071B1 KR101566071B1 KR1020130033029A KR20130033029A KR101566071B1 KR 101566071 B1 KR101566071 B1 KR 101566071B1 KR 1020130033029 A KR1020130033029 A KR 1020130033029A KR 20130033029 A KR20130033029 A KR 20130033029A KR 101566071 B1 KR101566071 B1 KR 101566071B1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The present invention relates to silver powder; Fumed silica; Glass frit; And an organic vehicle. The composition for forming a solar cell electrode has improved contact with an electrode and a wafer by introducing a specific fumed silica. The solar cell electrode made of the composition has a series resistance of Rs ) Is minimized and the fill factor and conversion efficiency are excellent.
Description
The present invention relates to a composition for forming a solar cell electrode and an electrode made therefrom.
Solar cells generate electrical energy by using the photoelectric effect of pn junction that converts photon of sunlight into electricity. The solar cell is formed with a front electrode and a rear electrode on a semiconductor wafer or a substrate on which a pn junction is formed. The photovoltaic effect of the pn junction is induced in the solar cell by the sunlight incident on the semiconductor wafer, and the electrons generated from the pn junction provide a current flowing to the outside through the electrode. Such an electrode of the solar cell can be formed on the surface of the wafer by applying, patterning and firing the electrode paste composition.
Recently, as the thickness of the emitter is continuously thinned to increase the efficiency of the solar cell, it may cause a shunting phenomenon which may degrade the performance of the solar cell. Further, the area of the solar cell is gradually increased to increase the efficiency of the solar cell, which can reduce the efficiency of the solar cell by increasing the contact resistance of the solar cell.
Therefore, it is urgently required to develop a composition capable of improving the contact property with the wafer and minimizing the series resistance (Rs) to produce a solar cell electrode having excellent conversion efficiency.
An object of the present invention is to provide a composition for forming a solar cell electrode which is excellent in ohmic contact between an electrode and a wafer surface.
Another object of the present invention is to provide a composition for forming a solar cell electrode capable of minimizing a series resistance (Rs).
It is still another object of the present invention to provide a solar cell electrode having excellent conversion efficiency and fill factor.
It is another object of the present invention to provide an electrode made from the composition.
The above and other objects of the present invention can be achieved by the present invention described below.
One aspect of the present invention relates to a silver powder; Fumed silica; Glass frit; And an organic vehicle.
Wherein the composition for forming the solar cell electrode comprises 60 to 95% by weight of the silver powder; 0.01 to 0.1 wt% of the fumed silica; 0.5 to 20 wt% of the glass frit; And 1 to 30% by weight of the organic vehicle.
The specific surface area (BET) of the fumed silica may be 20 to 500 m 2 / g.
Wherein the glass frit is at least one selected from the group consisting of zinc oxide-silicon oxide system (ZnO-SiO2), zinc oxide-boron oxide-silicon oxide system (ZnO-B2O3-SiO2), zinc oxide-boron oxide- SiO2-Al2O3), bismuth oxide-silicon oxide system (Bi2O3-SiO2), bismuth oxide-boron oxide-silicon oxide system (Bi2O3-B2O3-SiO2), bismuth oxide-boron oxide- (Bi2O3-ZnO-B2O3-SiO2), bismuth oxide-zinc oxide-boron oxide-silicon oxide-aluminum oxide system (Bi2O3-ZnO-B2O3- (PbO-TeO2-SiO2), lead oxide-tellurium oxide-lithium oxide (PbO-TeO2-SiO2-SiO2-Al2O3), tellurium oxide- (Bi2O3-TeO2-Li2O) glass oxide (Bi2O3-TeO2-SiO2) or bismuth oxide-tellurium oxide-lithium oxide glass (Bi2O3-TeO2-Li2O) glass Frit.
The glass frit may have an average particle diameter (D50) of 0.1 to 5 mu m.
The composition may further include at least one additive selected from the group consisting of a dispersant, a thixotropic agent, a plasticizer, a viscosity stabilizer, a defoamer, a pigment, a UV stabilizer, an antioxidant and a coupling agent.
A solar cell electrode, which is another aspect of the present invention, may be formed from the composition for forming the solar cell electrode.
The composition for forming the solar cell electrode of the present invention improves the contact property between the electrode and the wafer by introducing a specific fumed silica. The solar cell electrode made of the composition has a minimum series resistance (Rs) Is excellent.
FIG. 1 is a conceptual view schematically illustrating a process in which silver powder and glass frit are calcined on a wafer to form silver grains.
2 is a schematic view briefly showing a structure of a solar cell according to an embodiment of the present invention.
Composition for forming solar cell electrode
The composition for forming a solar cell electrode of the present invention comprises silver powder; Fumed silica; Glass frit; And an organic vehicle. Specific fumed silica is introduced to improve the contact property between the electrode and the wafer. The solar cell electrode made of the composition has a series resistance (Rs) Factor and conversion efficiency are excellent.
Hereinafter, the present invention will be described in detail.
(A) is powder
The composition for forming a solar cell electrode of the present invention uses silver (Ag) powder as the conductive powder. The silver powder may be a nano-sized or micro-sized powder, for example, a silver powder having a size of several tens to several hundreds of nanometers, a silver powder of several to several tens of micrometers, Silver powder may be mixed and used.
The silver powder may have a spherical shape, a plate shape, and an amorphous shape as the particle shape
The average particle diameter (D50) of the silver powder is preferably 0.1 to 10 mu m, more preferably 0.5 to 5 mu m. The average particle diameter was measured using a 1064 LD model manufactured by CILAS after dispersing the conductive powder in isopropyl alcohol (IPA) by ultrasonication at 25 캜 for 3 minutes. Within this range, the contact resistance and line resistance can be lowered.
The silver powder may be included in an amount of 60 to 95% by weight based on the total weight of the composition. In this range, it is possible to prevent the conversion efficiency from being lowered by increasing the resistance. Preferably 70 to 90% by weight.
(B) Fume Silica
1, in the firing step for forming a solar cell electrode, the glass frit 112 includes a p-layer (or n-layer) 101 and an n-layer (or p-layer) An electrode can be formed by etching the antireflection film, melting the silver (Ag)
In the present invention, an optimal ohmic conatact is formed by controlling the degree of etching of the antireflective film of the glass frit in the firing process, and a flow for minimizing diffusion of the glass frit acting as an impurity into the wafer by etching of the glass frit (Fumed Silica) was introduced in order to form a silica gel.
Fumed silica is a synthetic silica prepared by a dry process and has a purity of 99.9% or higher, and can be produced by thermal cracking a chlorosilane compound by gas phase.
In the present invention, the use of fumed silica having a specific surface area of 20 to 500 m 2 / g, preferably 50 to 200 m 2 / g is suitable for ensuring the flow of etching control or preventing the diffusion of impurities during the firing process Thereby reducing the series resistance due to the diffusion of impurities and improving the fill factor and conversion efficiency.
The fumed silica may be contained in an amount of 0.1% by weight or less, preferably 0.01 to 0.1% by weight based on the total weight of the composition. If it exceeds 0.1% by weight, the viscosity may greatly increase and the printability may deteriorate.
(C) Glass Frit
The glass frit is formed by etching the antireflection film during the firing process of the electrode paste, melting the silver particles to produce silver grains in the emitter region so that the resistance can be lowered, and the adhesion between the conductive powder and the wafer And softening at sintering to lower the firing temperature.
Increasing the area of the solar cell in order to increase the efficiency of the solar cell may increase the contact resistance of the solar cell. Therefore, the damage to the pn junction should be minimized and the series resistance should be minimized. In addition, it is preferable to use a glass frit which can sufficiently secure thermal stability even at a wide firing temperature because the range of variation in firing temperature becomes large as wafers of various sheet resistances increase.
The glass frit may be typically at least one of a flexible glass frit or a lead-free glass frit used in a composition for forming a solar cell electrode.
The glass frit may include a metal oxide selected from lead oxide, silicon oxide, tellurium oxide, bismuth oxide, zinc oxide, boron oxide, aluminum oxide, tungsten oxide, etc., alone or in a mixture thereof. For example, zinc oxide-silicon oxide (ZnO-SiO2), zinc oxide-boron oxide-silicon oxide (ZnO-B2O3-SiO2), zinc oxide-boron oxide- SiO2-Al2O3), bismuth oxide-silicon oxide system (Bi2O3-SiO2), bismuth oxide-boron oxide-silicon oxide system (Bi2O3-B2O3-SiO2), bismuth oxide-boron oxide- (Bi2O3-ZnO-B2O3-SiO2), bismuth oxide-zinc oxide-boron oxide-silicon oxide-aluminum oxide system (Bi2O3-ZnO-B2O3- (PbO-TeO2-SiO2), lead oxide-tellurium oxide-lithium oxide (PbO-TeO2-SiO2-SiO2-Al2O3), tellurium oxide- (Bi2O3-TeO2-Li2O) glass oxide (Bi2O3-TeO2-SiO2) or bismuth oxide-tellurium oxide-lithium oxide glass (Bi2O3-TeO2-Li2O) Frit or the like may be used.
The glass frit can be prepared from the metal oxides described above using conventional methods. For example, in the composition of the metal oxide described above. The blend can be mixed using a ball mill or a planetary mill. The mixed composition is melted at a temperature of 900 ° C to 1300 ° C and quenched at 25 ° C. The resulting product is pulverized by a disk mill, a planetary mill or the like to obtain a glass frit.
The glass frit may have an average particle diameter (D50) of 0.1 to 10 mu m, and may be contained in an amount of 0.5 to 20 wt% based on the total weight of the composition. The shape of the glass frit may be spherical or irregular. In a specific example, two kinds of glass frit having different transition points may be used. For example, a first glass frit having a transition temperature of 200 to 320 ° C and a second glass frit having a transition temperature of 300 to 550 ° C may be mixed at a weight ratio of 1: 0.2 to 1.
The glass frit may be made of, for example, silicon dioxide (SiO2), aluminum oxide (Al2O3), boron oxide (B2O3), bismuth oxide (Bi2O3), sodium oxide (Na2O) , Zinc oxide (ZnO), and the like.
(D) Organic Vehicle
The organic vehicle imparts suitable viscosity and rheological properties to the paste composition through mechanical mixing with inorganic components of the composition for forming the solar cell electrode.
The organic vehicle may be an organic vehicle usually used in a composition for forming a solar cell electrode, and may generally include a binder resin, a solvent, and the like.
As the binder resin, an acrylate-based or cellulose-based resin can be used, and ethylcellulose is generally used. However, it is preferable to use a mixture of ethylhydroxyethylcellulose, nitrocellulose, a mixture of ethylcellulose and phenol resin, an alkyd resin, a phenol resin, an acrylic ester resin, a xylene resin, a polybutene resin, a polyester resin, Based resin, a rosin of wood, or a polymethacrylate of alcohol may be used.
Examples of the solvent include hexane, toluene, ethyl cellosolve, cyclohexanone, butyl cellosolve, butyl carbitol (diethylene glycol monobutyl ether), monoisobutyrate, dibutyl carbitol (diethylene glycol Dibutyl ether), butyl carbitol acetate (diethylene glycol monobutyl ether acetate), propylene glycol monomethyl ether, hexylene glycol, terpineol, methyl ethyl ketone, benzyl alcohol, gamma butyrolactone or ethyl lactate May be used singly or in combination of two or more.
The blending amount of the organic vehicle may be 1 to 30% by weight based on the total weight of the composition. Within this range, sufficient adhesive strength and excellent printability can be ensured.
(E) Additive
The composition for forming a solar cell electrode of the present invention may further include conventional additives as necessary in order to improve flow characteristics, process characteristics, and stability in addition to the above-described components. The additive may be used alone or as a mixture of two or more of a dispersing agent, a thixotropic agent, a plasticizer, a viscosity stabilizer, a defoaming agent, a pigment, an ultraviolet stabilizer, an antioxidant and a coupling agent. These are added in an amount of 0.1 to 5% by weight based on the total weight of the composition, but they can be changed as needed.
Solar cell electrode and solar cell comprising same
Another aspect of the present invention relates to an electrode formed from the composition for forming a solar cell electrode and a solar cell including the same. 2 shows a structure of a solar cell according to one embodiment of the present invention.
2, the composition for forming a solar cell electrode is printed and fired on a
Hereinafter, the present invention will be described in more detail by way of examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.
Example
Example One
1% by weight of ethyl cellulose (STD4) as an organic binder was sufficiently dissolved in 6.69% by weight of Eastmann (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate) as a solvent at 60 DEG C, 89% by weight of a spherical silver powder (Dowa Hightech CO. LTD., AG-4-8) having a particle diameter of 2.0 탆, a low melting point flexible glass powder having an average particle diameter of 1.0 탆 and a transition point of 415 캜 0.01% by weight of fumed silica (Evonic, Aerosil R972) having a BET specific surface area of 90 to 130 m 2 / g, 0.4% by weight of dispersant BYK-2 (BYK-chemie), Thixatrol ST (Elementis co.) 0.4% by weight. The mixture was uniformly mixed and then mixed and dispersed with a three roll kneader to prepare a composition for forming a solar cell electrode.
The composition for forming the solar cell electrode was screen-printed on the entire surface of a wafer having a sheet resistance of 100 OMEGA / sq. By a predetermined pattern, and dried using an infrared ray drying furnace. Thereafter, aluminum paste was printed on the rear surface of the wafer and dried in the same manner. The cells thus formed were fired at 400 to 900 ° C. for 30 seconds to 50 seconds using a belt-type firing furnace. The cells thus manufactured were measured for solar cell efficiency (Pasan Co., CT-801) Fill Factor (FF,%) and conversion efficiency (%) were measured and shown in Table 1 below.
Example 2 - 3 and Comparative Example 1 - 8
A composition for forming a solar cell electrode was prepared in the same manner as in Example 1 except that each component was used in the composition shown in the following Table 1. The composition was printed to form an electrode, and the fill factor (FF,%) and The conversion efficiency (%) was measured and shown together in Table 1 below.
[Table 1]
As shown in Table 1, Example 1-3 using the ultrafine fumed silica having a specific specific surface area showed a higher Fill Factor value than Comparative Example 1-6 using an inorganic material other than fumed silica and Comparative Example 7 using no inorganic material And the conversion efficiency is also excellent as a result. This is because the fumed silica used in the examples minimizes the formation of optimal ohmic contacts during firing and the penetration or diffusion of glass frit impurities into the wafer. In addition, in Comparative Example 8, the viscosity of the composition was remarkably increased by using fumed silica in an excessive amount, so that the printability was lowered and the fill factor and conversion efficiency were lowered.
It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (7)
Fumed silica;
Glass frit; And
A composition comprising an organic vehicle,
Wherein the fumed silica is contained in an amount of 0.01 to 0.1% by weight based on the total weight of the composition.
60 to 95 wt% of the silver powder;
0.01 to 0.1% by weight of the fumed saccharide;
0.5 to 20% by weight of the glass frit; And
And 1 to 30% by weight of the organic vehicle.
Wherein the fumed silica has a specific surface area (BET) of 20 to 300 m 2 / g.
Wherein the glass frit is at least one selected from the group consisting of zinc oxide-silicon oxide system (ZnO-SiO2), zinc oxide-boron oxide-silicon oxide system (ZnO-B2O3-SiO2), zinc oxide-boron oxide- SiO2-Al2O3), bismuth oxide-silicon oxide system (Bi2O3-SiO2), bismuth oxide-boron oxide-silicon oxide system (Bi2O3-B2O3-SiO2), bismuth oxide-boron oxide- (Bi2O3-ZnO-B2O3-SiO2), bismuth oxide-zinc oxide-boron oxide-silicon oxide-aluminum oxide system (Bi2O3-ZnO-B2O3- (PbO-TeO2-SiO2), lead oxide-tellurium oxide-lithium oxide (PbO-TeO2-SiO2-SiO2-Al2O3), tellurium oxide- (Bi2O3-TeO2-Li2O) glass oxide (Bi2O3-TeO2-SiO2) or bismuth oxide-tellurium oxide-lithium oxide glass (Bi2O3-TeO2-Li2O) glass Frit < / RTI > A composition for forming a battery electrode.
Wherein the glass frit has an average particle diameter (D50) of 0.1 占 퐉 to 5 占 퐉.
Wherein the composition further comprises at least one additive selected from the group consisting of a dispersing agent, a thixotropic agent, a plasticizer, a viscosity stabilizer, a defoamer, a pigment, a UV stabilizer, an antioxidant and a coupling agent .
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020130033029A KR101566071B1 (en) | 2013-03-27 | 2013-03-27 | Composition for forming solar cell electrode and electrode prepared using the same |
| PCT/KR2014/002608 WO2014157958A1 (en) | 2013-03-27 | 2014-03-27 | Composition for forming solar cell electrode and electrode produced from same |
| JP2016505399A JP6343661B2 (en) | 2013-03-27 | 2014-03-27 | Composition for forming solar cell electrode and electrode produced thereby |
| US14/763,260 US9899545B2 (en) | 2013-03-27 | 2014-03-27 | Composition for forming solar cell electrode and electrode produced from same |
| CN201480018000.2A CN105051830B (en) | 2013-03-27 | 2014-03-27 | Form constituent and the electrode with the preparation of described constituent of solar cel electrode |
| TW103111504A TWI562171B (en) | 2013-03-27 | 2014-03-27 | The composition for forming solar cell electrode and electrode prepared using the same |
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| KR1020130033029A KR101566071B1 (en) | 2013-03-27 | 2013-03-27 | Composition for forming solar cell electrode and electrode prepared using the same |
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| KR20140119246A KR20140119246A (en) | 2014-10-10 |
| KR101566071B1 true KR101566071B1 (en) | 2015-11-04 |
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| KR101693840B1 (en) * | 2015-10-05 | 2017-01-09 | 대주전자재료 주식회사 | Paste composition for solar cell front electrode and solar cell using thereof |
| KR102406747B1 (en) * | 2018-12-21 | 2022-06-08 | 창저우 퓨전 뉴 머티리얼 씨오. 엘티디. | Method for forming solar cell electrode and solar cell |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101178180B1 (en) | 2010-05-07 | 2012-08-30 | 한국다이요잉크 주식회사 | Composition For fabricating rear electrode of crystalline solar cell |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101178180B1 (en) | 2010-05-07 | 2012-08-30 | 한국다이요잉크 주식회사 | Composition For fabricating rear electrode of crystalline solar cell |
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