KR20130104614A - A glass frit, paste composition comprising the same and silicon solar cell using the paste composition - Google Patents
A glass frit, paste composition comprising the same and silicon solar cell using the paste composition Download PDFInfo
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- KR20130104614A KR20130104614A KR1020120026245A KR20120026245A KR20130104614A KR 20130104614 A KR20130104614 A KR 20130104614A KR 1020120026245 A KR1020120026245 A KR 1020120026245A KR 20120026245 A KR20120026245 A KR 20120026245A KR 20130104614 A KR20130104614 A KR 20130104614A
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/062—Glass compositions containing silica with less than 40% silica by weight
- C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
- C03C8/16—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions with vehicle or suspending agents, e.g. slip
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/14—Conductive material dispersed in non-conductive inorganic material
- H01B1/16—Conductive material dispersed in non-conductive inorganic material the conductive material comprising metals or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/002—Inhomogeneous material in general
- H01B3/004—Inhomogeneous material in general with conductive additives or conductive layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
- H01B3/10—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances metallic oxides
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/542—Dye sensitized solar cells
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/547—Monocrystalline silicon PV cells
Abstract
Description
The present invention relates to a technique using a glass frit, and more particularly, to a glass frit, a paste composition comprising the same, and a silicon solar cell using the paste composition.
In recent years, interest in renewable energy has increased due to rising oil prices, global environmental problems, depletion of fossil energy, waste disposal of nuclear power generation, and the selection of locations due to construction of new power plants. The research and development of the is actively progressing.
A solar cell is a device that converts light energy into electrical energy using a photovoltaic effect, and has advantages such as pollution-free, indefinite resource, and semi-permanent life.
Solar cells are classified into silicon solar cells, thin film solar cells, dye-sensitized solar cells, and organic polymer solar cells according to their constituent materials. Crystalline silicon solar cells account for most of the total production of solar cells in the world. It is said to be the most popular solar cell because technology that is higher than the battery and continues to lower the manufacturing cost is being developed.
In order to improve the efficiency of crystalline silicon solar cells, which are currently being commercialized, studies are being conducted to increase the short-circuit current Isc, the open voltage Voc, and the fill factor (FF).
In general, an electrode of a solar cell is formed on the surface of a wafer by applying, patterning, and firing an electrode paste. The conductive paste for an electrode of a solar cell is made into a paste shape by uniformly dispersing a conductive powder and a glass frit as an inorganic binder in a vehicle, which is a liquid carrier.
Inorganic materials constituting the conventional electrode are dependent on lead glass. Recently, due to the increasing interest in the environment, the use of heavy metals such as lead is regulated and lead-free. The study of glass frit is urgently needed.
Related prior arts are Korean Unexamined Patent Publication No. 2011-0051836 (published May 18, 2011), wherein the Bi 2 O 3 10-30 mol%, Al 2 O 3 0.1-4 mol%, SiO 2 A glass composition comprising 1 to 25 mol%, B 2 O 3 20 to 40 mol%, ZnO 30 to 45 mol% and Na 2 O 0.1 to 4 mol% and a glass frit made therefrom are disclosed.
An object of the present invention is to provide a lead-free glass frit having excellent durability and electrical properties by varying the composition of the glass frit.
Another object of the present invention is to provide a paste composition using the glass frit.
In addition, another object of the present invention to provide a silicon solar cell excellent in light conversion efficiency using the paste composition.
Glass frit according to the present invention for achieving the above object comprises 30 to 50 mol% Bi 2 O 3, 30 to 50 mol% B 2 O 3 , 0.1 to 10 mol% SiO 2 and 1 to 20 mol% SrCO 3 , La 2 O 3 , Y 2 O 3 , Nd 2 O 3 , Co 2 O 3 And Cr 2 O 3 It is characterized in that it comprises 0.1 to 10 mol% of any additive.
In addition, the paste composition according to the present invention for achieving the above object comprises a conductive powder, a glass frit and an organic vehicle (vehicle), the glass frit is 30 ~ 50mol% Bi 2 O 3, 30 ~ 50mol B 2 O 3 %, SiO 2 0.1-10 mol% and SrCO 3 1-20 mol%, and the additive of any one of La 2 O 3 , Y 2 O 3 , Nd 2 O 3 , Co 2 O 3 and Cr 2 O 3 Characterized in that it comprises at ~ 10mol%.
In addition, a silicon solar cell according to the present invention for achieving the above object is a silicon substrate comprising a P-type semiconductor layer and an N-type semiconductor layer from below; A front electrode formed on the N-type semiconductor layer; And a rear electrode positioned opposite to the front electrode and formed on the P-type semiconductor layer, wherein the front electrode or the rear electrode is formed by baking a paste composition including conductive powder, glass frit, and an organic vehicle. The glass frit includes Bi 2 O 3 30-50 mol%, B 2 O 3 30-50 mol%, SiO 2 0.1-10 mol% and SrCO 3 1-20 mol%, La 2 O 3 , Y 2 O 3 , Nd 2 O 3 , Co 2 O 3 And Cr 2 O 3 An additive characterized in that it comprises 0.1 to 10 mol%.
The glass frit according to the present invention may be lead-free and exhibit durability and electrical properties such as excellent chemical resistance and heat resistance.
Therefore, the silicon solar cell including the electrode formed by coating and firing the paste composition including the glass frit according to the present invention can secure electrical characteristics equivalent to those of Pb-based, and thus have excellent photoelectric conversion efficiency.
In addition, since the glass frit according to the present invention is lead-free and does not contain lead, there is no restriction in using heavy metals, and environmental pollution such as soil and water can be prevented.
1 is a cross-sectional view showing a silicon solar cell according to an embodiment of the present invention.
Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments and drawings described below in detail.
However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and only the present embodiments make the disclosure of the present invention complete and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.
Hereinafter, a glass frit according to the present invention, a paste composition including the same, and a silicon solar cell using the paste composition will be described in detail.
Glass Frit
Glass frit may be used as a core component of the electrode paste composition of a solar cell, and refers to a glass powder obtained through a sieve of about 100 mesh or less.
The glass frit used in the present invention is preferably a lead-free system substantially free of lead in order to prevent environmental pollution caused by heavy metal emissions.
In addition, the glass frit used in the present invention is excellent in chemical resistance, heat resistance, and conductivity so as to maintain electrical characteristics such as short-circuit current (Isc), open voltage (Voc), charge rate (FF), and the like, which is equivalent to that of Pb. It is preferable to use.
The glass frit used in the present invention comprises A) Bi 2 O 3 30-50 mol%, B) B 2 O 3 30-50 mol%, C) SiO 2 0.1-10 mol% and D) SrCO 3 1-20 mol% as main components. Included as, 0.1 to 10 mol% of any one of the following E ~ I additive for improving the glass stabilization, conductivity and the like. E) La 2 O 3 , F) Y 2 O 3 , G) Nd 2 O 3 , H) Co 2 O 3 , I) Cr 2 O 3 .
The glass frit having the composition may have a glass transition temperature (Tg) of 350 to 450 ° C. and a softening temperature (Tdsp) of 400 to 460 ° C., and according to these characteristics, it is possible to secure the firing density even at the firing temperature of 460 to 500 ° C. Do.
In addition, the glass frit having the composition may have an average coefficient of thermal expansion 70 × 10 −7 / ° C. to 135 × 10 −7 / ° C. in the range of 30 to 300 ° C. after firing. According to this characteristic, warpage of the silicon wafer is prevented even when the thickness of the silicon wafer is thin when the electrode of the silicon solar cell is manufactured.
The average particle size (D50) of the glass frit may be 0.5 μm to 5 μm. When the average particle size (D50) is less than 0.5 μm, bumps, which are protrusions, may be generated in the post-printing firing process, while the average particle size is When (D50) exceeds 5㎛, the filling rate of the particles in the post-printing firing process is lowered, the contact with the silicon wafer is not made well, thereby causing a problem that the efficiency of the solar cell is lowered.
As such, the glass frit is lead-free, which does not contain lead, and therefore, there is no restriction in using heavy metals, and environmental pollution such as soil and water can be prevented.
In addition, the glass frit has a low firing temperature and a coefficient of thermal expansion, and has excellent durability and electrical properties such as chemical resistance and heat resistance, and thus is usefully used in the manufacture of silicon solar cells.
Hereinafter, the role and content of each component included in the glass frit used in the present invention will be described.
The present invention includes Bi 2 O 3 , B 2 O 3 , SiO 2 and SrCO 3 as main components constituting the glass frit. Serves as.
First of all, SiO 2 and B 2 O 3 are mentioned as a network former, and these components play the most important role in glass formation.
The mesh modifiers and mesh intermediate modifiers include Bi 2 O 3 and SrCO 3 , which contribute to the thermal properties of the glass and the chemical stability of the glass in terms of the properties of the glass. That is, the thermal property and stability of glass can be ensured by appropriate limitation of the glass composition range.
Considering the thermal properties and stability of such glass, the composition range of Bi 2 O 3 30-50 mol%, B 2 O 3 30-50mol%, SiO 2 0.1-10mol% and SrCO 3 1-20mol% is most preferred.
That is, when the content of Bi 2 O 3 , B 2 O 3, SiO 2 and SrCO 3 is different, it may not be possible to generate glass and may cause an increase in glass transition temperature.
chief ingredient
A) Bi 2 O 3
In the present invention, Bi 2 O 3 forms a glass, secures chemical resistance and heat resistance, serves as a flux or fusing agent for lowering the glass transition temperature (Tg), and 30 mol% to 50 mol of the total mol of the glass frit. It is preferably added in%. When the content of Bi 2 O 3 is less than 30 mol%, the generation of glass may be impossible, the effect of lowering the glass transition temperature (Tg) is reduced, it is difficult to secure sufficient chemical resistance and heat resistance. On the contrary, when the content of Bi 2 O 3 exceeds 50 mol%, chemical resistance may decrease.
B) B 2 O 3
In the present invention, B 2 O 3 forms a glass, secures chemical resistance, lowers the coefficient of thermal expansion, serves as a flux, and is preferably added at 30 mol% to 50 mol% of the total mol of the glass frit.
When the content of the B 2 O 3 is less than 30mol%, it may not be possible to produce the glass, it is difficult to secure sufficient chemical resistance with the effect of lowering the glass transition temperature (Tg) and the coefficient of thermal expansion. On the contrary, when the content of B 2 O 3 exceeds 50 mol%, the heat resistance may be weakened, or the crystallization may be deepened, thereby decreasing transparency.
C) SiO 2
In the present invention, SiO 2 may be added for glass formation and physicochemical improvement.
SiO 2 and B 2 O 3 can form glass alone, but SiO 2 has a higher melting point (1723 ° C) and B 2 O 3 has a lower melting point (450 ° C) than SiO 2 but has a glass property. It is very weak and therefore not suitable for use alone.
That is, SiO 2 is to complement the physicochemical properties of B 2 O 3 , and it is preferable to add 0.1 mol% to 10 mol% of the total mol of the glass frit. When the content of SiO 2 is less than 0.1 mol%, sufficient physicochemical properties cannot be obtained. On the contrary, when the content of SiO 2 exceeds 10 mol%, the glass transition temperature (Tg) increases, so that the process temperature increases.
D) SrCO 3
In the present invention, SrCO 3 may be added to ensure chemical resistance and heat resistance, and is preferably added in an amount of 1 mol% to 20 mol% of the total mol of the glass frit.
When the content of SrCO 3 is less than 1 mol%, it is difficult to secure sufficient chemical resistance and heat resistance. On the contrary, when the content of SrCO 3 exceeds 20 mol%, the glass transition temperature (Tg) increases, so that the process temperature increases.
additive
E) La 2 O 3
In the present invention, La 2 O 3 may be added to improve the electrical properties. The La 2 O 3 may be added at a level ranging from 0.1 mol% to 10 mol% of the total mol of the glass frit.
When the content of La 2 O 3 is less than 0.1 mol%, electrical characteristics such as a short circuit current (Isc), an open voltage (Voc), and a charging rate (FF) may not be sufficiently secured. On the contrary, when the content of La 2 O 3 exceeds 10 mol%, the coefficient of thermal expansion may increase, crystallization may be intensified, and corrosion resistance may be reduced.
F) Y 2 O 3
In the present invention, Y 2 O 3 may be added for glass stabilization. The Y 2 O 3 may be added at a level ranging from 0.1 mol% to 10 mol% of the total mol of the glass frit.
When the content of Y 2 O 3 is less than 0.1 mol%, sufficient chemical resistance may not be secured. On the contrary, when the content of Y 2 O 3 exceeds 10 mol%, the water resistance may be lowered.
G) Nd 2 O 3
In the present invention, Nd 2 O 3 may be added for glass stabilization similarly to the Y 2 O 3 . The Nd 2 O 3 may be added at a level ranging from 0.1 mol% to 10 mol% of the total mol of the glass frit.
When the content of Nd 2 O 3 is less than 0.1 mol%, sufficient chemical resistance cannot be secured. On the contrary, when the content of Nd 2 O 3 exceeds 10 mol%, mechanical strength and corrosion resistance may decrease.
H) Co 2 O 3
In the present invention, Co 2 O 3 may be added to improve the electrical properties. The Co 2 O 3 may be added at a level ranging from 0.1 mol% to 10 mol% of the total mol of the glass frit.
When the content of Co 2 O 3 is less than 0.1 mol%, the effect of improving the excitation voltage is insufficient, and thus the effect of improving the efficiency of the solar cell cannot be seen. On the contrary, when the content of Co 2 O 3 exceeds 10 mol%, the corrosion resistance may decrease.
I) Cr 2 O 3
In the present invention, Cr 2 O 3 may be added in order to improve electrical characteristics similar to Co 2 O 3 . The Cr 2 O 3 may be added at a level ranging from 0.1 mol% to 10 mol% of the total mol of the glass frit.
When the content of Cr 2 O 3 is less than 0.1 mol%, the effect of improving the excitation voltage is insufficient, and the effect of improving the efficiency of the solar cell is not seen. On the contrary, when the content of Cr 2 O 3 exceeds 10 mol%, corrosion resistance may decrease.
The glass frit having the composition could have a glass transition temperature (Tg) of 350 to 450 ° C. and a softening temperature (Tdsp) of 400 to 460 ° C. as a result of DTA analysis. According to these characteristics, the firing density can be ensured even at the firing temperature of 460 to 500 ° C.
In addition, the glass frit having the composition, as a result of TMA analysis, may have a thermal expansion coefficient of 70 × 10 −7 / ° C. to 135 × 10 −7 / ° C. at 25 ° C. after firing.
The manufacturing process of the glass frit is as follows. First, the main components of Bi 2 O 3 , B 2 O 3 , SiO 2 , SrCO 3 and La 2 O 3 , Y 2 O 3 , An additive of any one of Nd 2 O 3 , Co 2 O 3 , and Cr 2 O 3 is formed at the above composition ratio, and then the raw materials are mixed. Then, the mixed raw material is heated to a temperature of 1000 ~ 1100 ℃ to make a glass melt. Subsequently, after quenching the glass melt, the glassy material is pulverized using a jet mill to prepare a powder having an average particle size of 0.5 to 5 탆.
Paste composition
The paste composition according to the present invention is a composition for forming a front electrode or a back electrode of a silicon solar cell.
The paste composition according to the present invention comprises a conductive powder, a glass frit and an organic vehicle.
The paste composition comprises 65 wt% to 90 wt% of the conductive powder, 0.1 wt% to 5 wt% of the glass frit, and 9.9 wt% to 34.90 wt% of the organic vehicle.
Glass frit
Since the glass frit used in the paste composition of the present invention is the same as the glass frit according to the present invention described above, duplicate description thereof will be omitted.
The glass frit contained in the paste composition allows the silicon substrate and the conductive powder on which the PN junction is formed to form a good ohmic contact during the firing process, and plays an important role in improving adhesion between the conductive powder and the underlying substrate. .
In the present invention, the glass frit is preferably included in an amount of 0.1% by weight to 5% by weight based on the total weight of the composition. In the paste composition, when the glass frit having the above components and composition ratio is included in the above content range, the contact between the silicon wafer and the paste composition is improved, the bending of the silicon wafer or the bubbles, bumps, and It can be expected to prevent yellowing and improve efficiency of solar cells.
If the content of the glass frit is less than 0.1% by weight, sufficient ohmic contact may be poor, and it may be difficult to exhibit durability and electrical properties. On the contrary, when the content of the glass frit exceeds 5% by weight, there is a possibility that the PN junction is destroyed by excessive etching during the firing process, and the amount of the glass frit remaining after firing may be excessively distributed to increase the resistance. .
Glass frit used in the present invention is preferably a glass transition temperature (Tg) 350 ~ 450 ℃, softening temperature (Tdsp) 400 ~ 460 ℃. If the glass transition temperature (Tg) of the glass frit is less than 380 ° C. and the softening temperature (Tdsp) is less than 400 ° C., the coefficient of thermal expansion of the glass frit is relatively large, resulting in a warpage of the wafer after the firing step in the solar cell manufacturing process. There is a problem of increasing. On the other hand, when the glass transition temperature (Tg) of the glass frit exceeds 460 ° C and the softening temperature (Tdsp) exceeds 460 ° C, the glass frit is not sufficiently melted during the firing process, so that the adhesion between the electrode layer and the silicon wafer layer is This deterioration problem may occur.
The glass frit used in the present invention preferably has a firing temperature of 500 ° C. or lower of 460 ° C. to 500 ° C., in which case it is possible to secure the firing density and contribute to the improvement of the conversion efficiency of the solar cell. When the firing temperature of the glass frit exceeds 500 ° C., the firing density may be lowered.
The glass frit used in the present invention preferably has a thermal expansion coefficient at a temperature of 30 to 300 ° C. after firing of 135 × 10 −7 / ° C. or less of 70 × 10 −7 / ° C. to 135 × 10 −7 / ° C. If the coefficient of thermal expansion of the glass frit exceeds 135 × 10 −7 / ° C., warping of the silicon wafer may occur.
Glass frit used in the present invention may be used that the average particle size of 0.5 ~ 5㎛. When forming the electrode within the above range does not cause a defect in the printing process, the density of the pattern after firing is good, the resistance loss can be reduced.
Conductive powder
As the conductive powder used in the present invention, both conductive organic and inorganic materials may be used. Preferably silver (Ag), gold (Au), palladium (Pd), platinum (Pt), copper (Cu), chromium (Cr), cobalt (Co), aluminum (Al), tin (Sn), zinc ( Zn), iron (Fe), iridium (Ir), osmium (Os), rhodium (Rh), tungsten (W), molybdenum (Mo), nickel (Nickel) or indium tin oxide (ITO) may be used. Can be. Such conductive powder can be used 1 type or in mixture of 2 or more types.
Preferably, the conductive powder includes silver (Ag) or aluminum (Al) particles, and further nickel (Ni), cobalt (Co), iron (Fe), zinc (Zn) or copper (Cu) particles are further added. Can be.
The conductive powder may be used having an average particle diameter (D50) having an average particle diameter of 0.1 ~ 10㎛. When the average particle size of the conductive powder is less than 0.1 μm, bumps occur in the post-printing firing process, and wafer warpage is increased. On the other hand, when the average particle size is more than 10 μm, the filling rate of the particles is lowered, which causes the efficiency of the solar cell. This deterioration problem occurs.
The conductive powder may comprise 65 to 90% by weight of the total weight of the paste composition. When the content of the conductive powder is less than 65% by weight, an increase in the resistance may cause a series resistance (Rser, Series Resistance) and Fill Factor (FF) to be poor, and may cause a problem such as an electrode short circuit. If it exceeds 90% by weight, the amount of the organic binder may be relatively small, which may make it difficult to paste.
Organic vehicle ( vehicle )
The organic vehicle according to the present invention may be an organic binder that provides liquid properties to the paste composition, and may further include a solvent.
In the paste composition, the binder serves to fix the glass frit to the electrode surface and to improve the interparticle binding force of the glass frit.
Such organic binders include cellulose-based polymers such as ethyl cellulose (Ethyl Cellulose), hydroxyethyl cellulose (Hydroxyethyl Cellulose), hydroxypropyl cellulose (Hydroxypropyl Cellulose) or hydroxyethyl hydroxypropyl cellulose (Hydroxyethylhydroxypropyl), respectively. It can be used individually or in mixture of 2 or more types.
The organic binder may comprise 1 to 2% by weight of the total weight of the paste composition. When the content of the organic binder is less than 1% by weight, the printing effect and dispersion stability of the paste composition are lowered. On the contrary, when the content of the organic binder exceeds 2% by weight, pin holes or bubbles may be generated due to residual carbon in the firing process, thereby deteriorating electrical characteristics of the solar cell.
The solvent plays a role of dissolving the organic binder and controlling the viscosity of the paste composition.
If it is compatible with such an organic binder, it will not restrict | limit in particular. Preferably, the solvent may be a solvent having a boiling point in the range of about 150 ~ 300 ℃ to prevent drying of the paste composition during the printing process and to control the fluidity.
As the solvent, tripropylene glycol methyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, diethylene glycol ethyl ether, diethylene Glycol n-butyl ether, diethylene glycol hexyl ether, ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether, terpinol, Texanol ethylene glycol Can be mentioned. These may be used alone or in combination of two or more. Alternatively, alpha terpineol (α-Terpineol), butyl carbitol acetate (Butyl Carbitol Acetate) and the like may be used as the solvent.
The content of the solvent may be determined according to the content of the glass frit, the binder and the conductive powder, and may be about 5 to 35% by weight of the total weight of the paste composition.
5 to 30% by weight of the organic binder in the organic vehicle, the solvent may comprise 70 to 95% by weight.
The organic vehicle may be included in an amount of 9.9% to 34.90% by weight of the total weight of the paste composition. When the content of the organic vehicle is less than 9.9% by weight, the viscosity may be too high after the paste is prepared or the adhesion to the substrate may be reduced after printing and drying. On the other hand, when the content of the organic vehicle exceeds 34.90% by weight, the viscosity is lowered to increase the line width of the pattern, thereby reducing the area where the solar energy is incident, the photovoltaic power may be reduced.
On the other hand, the paste composition may further include a conventional additive as needed to improve the flow characteristics and process characteristics. The additives include plasticizers, dispersants, thixotropic agents, viscosity stabilizers, defoamers, pigments, ultraviolet stabilizers, antioxidants, coupling agents, and the like, but are not necessarily limited thereto. These may be used alone or in combination of two or more. These are all known enough to be commercially available to those of ordinary skill in the art, so specific examples and descriptions thereof will be omitted.
1 is a cross-sectional view showing a silicon solar cell according to an embodiment of the present invention.
Referring to FIG. 1, a silicon solar cell includes a
The P-
The
The
Although not shown in the drawings, an anti-reflection film may be further formed on the N-
The silicon solar cell using the paste composition of the Bi-B-Si-Sr glass frit as described above showed excellent conversion efficiency as a conversion efficiency (Eff) of 18.58 to 18.64% as a result of measurement using a solar cell efficiency meter. Fill factor (FF) 79.22 ~ 80.01%, short circuit current (Isc) 8.770 ~ 8.815mA / ㎠, open voltage (Voc) 0.632 ~ 0.636V, series resistance (Rser) 0.0044 ~ 0.0048Ω and parallel resistance (Rsht) 19.4 ~ 43.6Ω showed excellent electrical properties.
In the present invention, the Bi-B-Si-Sr-based glass frit is described as being limited to the use of an electrode for manufacturing a silicon solar cell. However, the Bi-B-Si-Sr-based glass frit is a dye-sensitized solar cell or other semiconductor device. Needless to say, it can be used for forming electrodes, such as a display apparatus.
Example
Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.
Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.
1. Glass Frit prepared
As shown in Table 1, glass frits according to Compositions 1 to 6 were prepared.
[Table 1] (Unit: mol%)
2. Measurement of thermal properties
The glass transition temperature (Tg) and softening temperature of each of the glass frits according to the above compositions 1 to 6 were heated up to 600 ° C. at a temperature rising rate of 10 ° C./min using a DTA (DTG-60H, manufactured by Shitmatz) analyzer. (Tdsp) was measured and the results are shown in Table 2.
[Table 2]
Referring to Table 2, the glass frit according to the compositions 1 to 6 corresponding to the embodiments of the present invention showed a glass transition temperature (Tg) of 381 to 442 ° C, and a softening temperature (Tdsp) of 407 to 460 ° C. appear.
In particular, the glass transition temperature (Tg) and softening temperature (Tdsp) of the glass frit according to the composition 6 is lower than the composition 1 ~ 5, the content of Bi 2 O 3 and SrCO 3 is low, the content of B 2 O 3 is low Could confirm.
3. Physical properties Measure
Coefficient of thermal expansion (CTE) while heating up to 350 ° C. at a heating rate of 5 ° C./min at a load of 0.05 N using TMA (TMA-Q400, manufactured by TA instrument) analysis equipment for each of the glass frits according to Compositions 1 to 6 above. ) Was measured and the results are shown in Table 3. In addition, the average particle size (D50) was measured for each of the glass frits according to Compositions 1 to 6 using PSA (Malvern mastersizer 2000 (RI: 2.5)), and the results are shown in Table 3 below.
[Table 3]
Referring to Table 3, the glass frit according to the compositions 1 to 6 corresponding to the examples of the present invention showed a coefficient of thermal expansion (CTE) of 94 × 10 −7 / ° C. to 120 × 10 −7 / ° C. Particle size (D50) was found to be 1.8 ~ 2.7㎛.
4. Preparation of Paste Composition
0.5% by weight of the glass frit according to the compositions 1 to 6 having the composition shown in Table 1, the average particle size (D50) of 2㎛ aluminum (Al) powder 70% by weight, organic cellulose 29.5 dissolved by dissolving ethyl cellulose in glycol ether After mixing the wt%, the mixture was stirred to prepare paste compositions according to Examples 1 to 6 (compositions 1 to 6), respectively.
5. Fabrication of Silicon Solar Cells
Example 1 to 6
Phosphorus (P) is injected into the surface of the P-type silicon wafer to form a PN junction. Then, silver (Ag) paste is printed on the N-type semiconductor layer on the front surface of the wafer by printing a pattern in a predetermined pattern, and 130 ° C using an infrared drying furnace. Dried for 5 minutes. Thereafter, the paste composition prepared in Examples 1 to 6 was printed on the front surface by screen printing on the P-type semiconductor layer on the back of the wafer and dried in the same manner. Then, the silicon wafer subjected to the above process was subjected to Peak Temp. Baking at a temperature of 800 ℃ for 1 minute to produce a solar cell.
Comparative example
A silicon solar cell was manufactured in the same manner as in Examples 1 to 6, except that the following Pb system was used as the glass frit included in the back electrode paste composition.
The specification of the Pb-based glass frit used in the comparative example is as follows.
Pb-based glass frit:
(a) Main components: 79.3 wt% PbO, 10.53 wt% SiO 2 , 6.47 wt% B 2 O 3 and 0.5 wt% Al 2 O 3
(b) Additives: MgO 1.4% by weight, Fe 2 O 3 0.6% by weight, Cr 2 O 3 0.8% by weight, MnO 2 0.4% by weight
6. Electrical characteristic evaluation
Solar cell for a comparative example comprising a silicon solar cell according to Examples 1 to 6 comprising a back electrode prepared using a paste composition comprising a glass frit of compositions 1 to 6 and a back electrode using a Pb-based glass frit Conversion efficiency (Eff), fill factor (FF), short circuit current (Isc), open circuit voltage (Voc), series resistance (Rser) and parallel resistance (Rsht) were measured using an efficiency meter. It was.
[Table 4]
Referring to Table 4, as a result of comparing lead-free Examples 1 to 6 and Pb-based comparative examples, there was almost no significant difference in conversion efficiency (Eff) between Examples 1 to 6 and Comparative Examples. Except for Example 4, the conversion efficiency (Eff) was about 0.01 ~ 0.06% higher than the comparative example.
In addition, there were almost no significant differences between Examples 1 to 6 and Comparative Examples in the filling factor (FF), the short-circuit current (Isc), the open circuit voltage (Voc), and the series resistance (Rser). However, parallel resistance (Rsht) was slightly higher in Examples 1 to 6 than in Comparative Example.
Through this, when forming an electrode for a silicon solar cell using a lead-free glass frit having a component and a composition ratio according to the present invention, the result can be obtained at the same level as the electrical characteristics of the conventional Pb system, in terms of photoelectric conversion efficiency In the case of using a Pb-based glass frit, it was confirmed that slightly superior.
While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.
110 silicon substrate 112 P-type semiconductor layer
114: N-type semiconductor layer 120: front electrode
130: rear electrode
Claims (14)
The glass frit
Glass frit, characterized in that the glass transition temperature (Tg) is 350 ~ 450 ℃, softening temperature (Tdsp) is 400 ~ 460 ℃, firing temperature is 460 ~ 500 ℃.
The glass frit
An average thermal expansion coefficient in the range of 30-300 degreeC after baking is 70x10 <-7> / degreeC-135x10 <-7> / degreeC, The glass frit characterized by the above-mentioned.
The glass frit
An average particle size is 0.5-5 micrometers, The glass frit characterized by the above-mentioned.
The glass frit contains Bi 2 O 3 30-50 mol%, B 2 O 3 30-50 mol%, SiO 2 0.1-10 mol% and SrCO 3 1-20 mol%, La 2 O 3 , Y 2 O 3 , Nd A paste composition comprising 0.1 to 10 mol% of an additive of 2 O 3 , Co 2 O 3, and Cr 2 O 3 .
The conductive powder is
Paste composition, characterized in that the material containing silver (Ag) or aluminum (Al).
The glass frit
Paste composition, characterized in that the glass transition temperature (Tg) is 350 ~ 450 ℃, softening temperature (Tdsp) is 400 ~ 460 ℃, firing temperature is 460 ~ 500 ℃.
The glass frit
An average thermal expansion coefficient in the range of 30-300 degreeC after baking is 70x10 <-7> / degreeC-135x10 <-7> / degreeC, The paste composition characterized by the above-mentioned.
The glass frit
Paste composition, characterized in that the average particle size is 0.5 ~ 5㎛.
The paste composition is
A paste composition comprising 65 wt% to 90 wt% of conductive powder, 0.1 wt% to 5 wt% of glass frit, and 9.9 wt% to 34.90 wt% of organic vehicle, based on the total weight of the composition.
The organic vehicle
An paste composition comprising an organic binder and a solvent.
A front electrode formed on the N-type semiconductor layer; And
A rear electrode positioned on the opposite side of the front electrode and formed on the P-type semiconductor layer;
The front electrode or the back electrode,
A paste composition comprising a conductive powder, a glass frit and an organic vehicle is formed by firing,
The glass frit contains Bi 2 O 3 30-50 mol%, B 2 O 3 30-50mol%, SiO 2 0.1-10mol% and SrCO 3 1-20mol%, La 2 O 3 , Y 2 O 3 , Nd Silicon solar cell comprising an additive of any one of 2 O 3 , Co 2 O 3 and Cr 2 O 3 in 0.1 ~ 10mol%.
The glass frit
Glass transition temperature (Tg) is 350 ~ 450 ℃, softening temperature (Tdsp) is 400 ~ 460 ℃, firing temperature is 460 ~ 500 ℃ silicon solar cell, characterized in that.
The glass frit
An average thermal expansion coefficient in the range of 30-300 degreeC after baking is 70x10 <-7> / degreeC-135x10 <-7> / degreeC, The silicon solar cell characterized by the above-mentioned.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20160012960A (en) | 2014-07-24 | 2016-02-03 | 대주전자재료 주식회사 | Silver Paste for Electrode of Solar Cell With Controlled Silver Crystalline Size |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109074895B (en) * | 2016-08-16 | 2022-05-27 | 浙江凯盈新材料有限公司 | Thick film paste for front side metallization in silicon solar cells |
| SG11201809794SA (en) | 2016-12-20 | 2018-12-28 | Zhejiang Kaiying New Materials Co Ltd | Interdigitated back contact metal-insulator-semiconductor solar cell with printed oxide tunnel junctions |
| MY189222A (en) | 2016-12-20 | 2022-01-31 | Zhejiang Kaiying New Mat Co Ltd | Siloxane-containing solar cell metallization pastes |
| US10749045B1 (en) | 2019-05-23 | 2020-08-18 | Zhejiang Kaiying New Materials Co., Ltd. | Solar cell side surface interconnects |
| US10622502B1 (en) | 2019-05-23 | 2020-04-14 | Zhejiang Kaiying New Materials Co., Ltd. | Solar cell edge interconnects |
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| JP5685813B2 (en) * | 2009-12-29 | 2015-03-18 | セントラル硝子株式会社 | Lead-free low melting point glass paste for insulation coating |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20160012960A (en) | 2014-07-24 | 2016-02-03 | 대주전자재료 주식회사 | Silver Paste for Electrode of Solar Cell With Controlled Silver Crystalline Size |
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