KR20190113131A - Composition for forming solar cell electrode and electrode prepared using the same - Google Patents

Abstract

The present invention is to provide a composition for forming a solar cell electrode having excellent physical properties of ribbon adhesion while having excellent electrical properties of fill factors and conversion efficiency and an electrode prepared therefrom. The composition comprises conductive powder, a mixture of the glass frit and an organic vehicle. The mixture of the glass frit comprises: one or more types from the second glass frit having the glass transition temperature not less than 260°C and less than 290°C and the third glass frit having the glass transition temperature not less than 290°C and not more than 360°C; and the first glass frit having the glass transition temperature of not less than 220°C and less than 250°C.

Description

A composition for forming a solar cell electrode and an electrode manufactured therefrom {COMPOSITION FOR FORMING SOLAR CELL ELECTRODE AND ELECTRODE PREPARED USING THE SAME}

The present invention relates to a composition for forming a solar cell electrode and an electrode prepared therefrom. More specifically, the present invention comprises a mixture of the glass frit having a specific glass transition temperature of the present invention, the electrical properties of the Fill Factor and the conversion efficiency, and the physical properties of the ribbon adhesion force at the same time can be realized It relates to a composition for forming a battery electrode.

Solar cells generate electrical energy using the photoelectric effect of pn junctions that convert photons of sunlight into electricity. In the solar cell, front and rear electrodes are formed on the upper and lower surfaces of the semiconductor wafer or substrate on which the pn junction is formed. The photovoltaic effect of the pn junction is induced by solar light incident on the semiconductor wafer, and electrons generated therefrom provide a current flowing through the electrode to the outside. The electrode of such a solar cell may be formed on the wafer surface by applying, patterning, and firing an 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 that may degrade the performance of the solar cell. In addition, in order to increase the efficiency of the solar cell, the area of the solar cell is gradually increased, and the sheet resistance of the wafer is gradually increasing, which can reduce the efficiency of the solar cell by increasing the contact resistance of the solar cell.

Background art of the present invention is disclosed in Japanese Patent Laid-Open No. 2015-144162 or the like.

An object of the present invention is to provide a composition for forming a solar cell electrode excellent in the electrical properties of the Fill Factor and the conversion efficiency, and at the same time excellent electrode physical properties of the ribbon adhesion.

Another object of the present invention is to provide a solar cell electrode having excellent electrical properties of Fill Factor and conversion efficiency and excellent physical properties of ribbon adhesion.

Composition for forming a solar cell electrode of the present invention is a conductive powder; Mixtures of glass frits; And an organic vehicle, wherein the mixture of glass frits comprises at least one of a second glass frit having a glass transition temperature of at least 260 ° C. and less than 290 ° C. and a third glass frit having a glass transition temperature of at least 290 ° C. and at most 360 ° C .; And a first glass frit having a glass transition temperature of 220 ° C. or more and less than 250 ° C.

The first glass frit may include bismuth-tellurium-zinc-lithium glass frit or lead-tellurium-zinc-lithium glass frit.

The second glass frit may include bismuth-tellurium-zinc-lithium-tungsten-based glass frit or lead-tellurium-zinc-lithium-tungsten-based glass frit.

The third glass frit is bismuth-tellurium-zinc-lithium-magnesium-based glass frit, bismuth-lithium-sodium-based glass frit, lead-tellurium-zinc-lithium-magnesium-based glass frit or lead-tellurium-zinc- Lithium-sodium based glass frit.

In the mixture of the glass frit the first glass frit is 10% to 80% by weight, the second glass frit is 0% to 70% by weight, the third glass frit is 0% to 70% by weight, the The sum of the second glass frit and the third glass frit is greater than 0 wt%.

In the mixture of the glass frit, the first glass frit: the second glass frit and the third glass frit may be included in a weight ratio of 1: 1 to 1:10.

The first glass frit: the second glass frit: the third glass frit in the mixture of the glass frit may be included in a weight ratio of 1: 0.1 to 3: 0.1 to 5.

The mixture of the glass frit may include all of the first glass frit, the second glass frit and the third glass frit.

The composition may include 60 wt% to 95 wt% of the conductive powder, 1 wt% to 20 wt% of the mixture of the glass frit, and the balance of the organic vehicle.

The composition may further include one or more additives of a dispersant, thixotropic agent, plasticizer, viscosity stabilizer, antifoaming agent, pigment, ultraviolet light stabilizer, antioxidant, coupling agent.

The electrode of the present invention can be prepared with the composition for forming a solar cell electrode of the present invention.

The present invention provides a composition for forming a solar cell electrode which is excellent in electrical properties of Fill Factor and conversion efficiency, and at the same time excellent electrode physical properties of the ribbon adhesion.

The present invention provides a solar cell electrode having excellent electrical properties of Fill Factor and conversion efficiency, and excellent physical properties of ribbon adhesion.

1 is a schematic diagram schematically showing the structure of a solar cell according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, it will be described embodiments of the present application in more detail. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms.

The "glass transition temperature" of the glass frit herein can be measured by conventional methods known to those skilled in the art, for example, can be measured by differential scanning calorimetry, but is not limited thereto.

Composition for forming solar cell electrode

Composition for forming a solar cell electrode of the present invention is a conductive powder; Mixtures of glass frits; And an organic vehicle, wherein the mixture of glass frits comprises at least one of a second glass frit having a glass transition temperature of at least 260 ° C. and less than 290 ° C. and a third glass frit having a glass transition temperature of at least 290 ° C. and at most 360 ° C .; And a first glass frit having a glass transition temperature of 220 ° C. or more and less than 250 ° C. The inventors of the present invention find that the composition for forming a solar cell electrode including the mixture of the glass frit has excellent electrical properties of Fill Factor and conversion efficiency, and at the same time realizes an electrode having excellent physical properties of ribbon adhesion. Completed.

Hereinafter, each component in the composition of the present invention will be described in detail.

Conductive powder

The conductive powder may include silver (Ag) powder. The silver powder may be a powder having a particle size of nano size or micro size, for example, may be a silver powder of several tens to hundreds of nanometers in size, silver powder of several to several tens of micrometers. In addition, the silver powder may be used by mixing silver powder having two or more different sizes.

The conductive powder may include a conventionally known conductive powder in addition to silver (Ag) powder. For example, the conductive powder may be silver (Ag), gold (Au), palladium (Pd), platinum (Pt), copper (Cu), chromium (Cr), cobalt (Co), aluminum (Al), tin (Sn). ), Lead (Pb), zinc (Zn), iron (Fe), iridium (Ir), osmium (Os), rhodium (Rh), tungsten (W), molybdenum (Mo) and nickel (Ni) powders can be used. have.

The conductive powder is not particularly limited in particle shape, and particles of various shapes, for example, spherical, plate or amorphous particles, may be used without limitation.

The average particle diameter (D50) of the conductive powder is 0.1 μm to 10 μm, preferably 0.5 μm to 3 μm. Within this range, the Fill Factor and the conversion efficiency may be excellent. The average particle diameter (D50) was measured using a 1064LD model manufactured by CILAS after dispersing the conductive powder in isopropyl alcohol (IPA) at 25 ° C. for 3 minutes with ultrasonic waves.

The conductive powder may be included in 60 wt% to 95 wt% of the composition for forming a solar cell electrode. When the content of the conductive powder satisfies the above range, the change efficiency of the solar cell is excellent and the paste can be made smoothly. Preferably, the conductive powder may be included in 70% by weight to 90% by weight of the composition for forming a solar cell electrode.

Glass frit

The glass frit is for etching the antireflection film during the firing process of the composition for forming a solar cell electrode, melting the conductive powder to generate crystal particles of the conductive powder in the emitter region. In addition, the glass frit improves the adhesion between the conductive powder and the wafer and softens during sintering to induce an effect of lowering the firing temperature.

The composition for forming a solar cell electrode of the present invention comprises at least one of a second glass frit and a third glass frit; And a mixture of glass frits including a first glass frit. The glass transition temperatures of the first glass frit, the second glass frit, and the third glass frit are different. The mixture of the glass frit includes two or more glass frits having a glass transition temperature in the entire temperature range from the temperature at which the solvent is volatilized to the temperature at which the organic binder is decomposed when the electrode is manufactured. Therefore, the present invention can be made to continuously sinter in the entire temperature range from the temperature at which the solvent volatilization is started to the decomposition start temperature of the organic binder when the electrode is prepared in the composition for forming an electrode. Through this, it is possible to sinter the conductive powder even at a low temperature to improve the electrical properties and to improve the ribbon adhesion when soldering the film completely filled with the conductive powder.

(1) first glass frit

The first glass frit may have a glass transition temperature of 220 ° C. or more and less than 250 ° C. In the above range, the decomposition of the organic vehicle in the composition and the sintering of the composition may be initiated in the process of volatilizing the solvent when preparing the electrode as a composition for forming an electrode, thereby improving electrical and physical properties. Specifically, the first glass frit may have a glass transition temperature of 220 ° C. or more and 245 ° C. or less.

The first glass frit may be bismuth-tellurium-based including bismuth (Bi) or tellurium (Te) or lead-tellurium-based glass frit including lead (Pb) and tellurium (Te). These may be included alone or two kinds. In addition, the first glass frit may be a bismuth-tellurium-zinc-lithium-based or lead-tellurium-zinc-lithium-based glass frit further including zinc (Zn) and lithium (Li). These may be included alone or two kinds. The first glass frit is bismuth (Bi) or lead (Pb); Tellurium (Te); Zinc (Zn); And by including lithium (Li) it can be easily ensured the glass transition temperature range. For example, the first glass frit contains 70 wt% to 99 wt% of bismuth oxide and tellurium oxide or all lead oxide and tellurium oxide, for example, 70 wt% to 90 wt%, The total amount of lithium oxide may be included in an amount of 1 wt% to 30 wt%, for example, 10 wt% to 30 wt%. Within this range, it is possible to easily ensure the glass transition temperature range of the present invention.

In one embodiment, the first glass frit may comprise 5 wt% to 50 wt%, preferably 10 wt% to 40 wt% of bismuth oxide or lead oxide. In one embodiment, the first glass frit may comprise from 40% to 90% by weight, preferably from 50% to 80% or from 60% to 80% by weight of tellurium oxide. In one embodiment, the first glass frit may comprise 1% to 30% by weight of zinc oxide, preferably 1% to 15% by weight. In one embodiment, the first glass frit may comprise 1% to 10% by weight of lithium oxide, preferably 1% to 8% by weight. In the above range, there may be a low temperature entrained copper effect.

The first glass frit is bismuth (Bi), lead (Pb), phosphorus (P), germanium (Ge), gallium (Ga), cerium (Ce), iron (Fe), silicon (Si), tungsten (W), Magnesium (Mg), Cesium (Cs), Strontium (Sr), Molybdenum (Mo), Titanium (Ti), Tin (Sn), Indium (In), Vanadium (V), Barium (Ba), Nickel (Ni), 1 selected from the group consisting of copper (Cu), sodium (Na), potassium (K), arsenic (As), cobalt (Co), zirconium (Zr), manganese (Mn), aluminum (Al) and oxides thereof It may also contain more than one element.

The first glass frit may be included in 10% to 80% by weight, for example 20% to 50%, 20% to 40%, 30% to 80% by weight of the mixture of the glass frit. In the above range, there may be a low temperature entrained copper effect.

(2) second glass frit

The second glass frit may have a glass transition temperature of 260 ° C. or more and less than 290 ° C. In the above range, it is possible to improve the electrical and physical properties at the same time to enable continuous sintering during electrode production with the composition for forming an electrode. Specifically, the second glass frit may have a glass transition temperature of 260 ° C or more and 280 ° C or less.

The second glass frit may be a bismuth-tellurium-based including bismuth (Bi) or tellurium (Te) or a lead-tellurium-based glass frit including lead (Pb) and tellurium (Te). These may be included alone or two kinds. The second glass frit may be bismuth-tellurium-zinc-lithium-tungsten-based or lead-tellurium-zinc-lithium-tungsten-based glass frit further comprising zinc (Zn), lithium (Li) and tungsten (W). have. These may be included alone or two kinds. The second glass frit includes bismuth (Bi) or lead (Pb), tellurium (Te), zinc (Zn), lithium (Li), and tungsten (W) to easily secure the glass transition temperature range. . For example, the second glass frit contains 70% by weight to 99% by weight of total bismuth oxide and tellurium oxide, such as 70% by weight to 90% by weight, and 1% by weight of zinc oxide, lithium oxide, and tungsten oxide in total. % To 30% by weight, for example 10% to 30% by weight. Within this range, it is possible to easily ensure the glass transition temperature range of the present invention.

In one embodiment, the second glass frit may comprise 5 wt% to 50 wt%, preferably 10 wt% to 40 wt% of bismuth oxide or lead oxide. In one embodiment, the second glass frit may comprise from 40% to 90% by weight, preferably from 50% to 80% or from 60% to 80% by weight of tellurium oxide. In one embodiment, the second glass frit may comprise 1% to 30% by weight of zinc oxide, preferably 1% to 15% by weight. In one embodiment, the second glass frit may comprise 1% to 10% by weight of lithium oxide, preferably 1% to 8% by weight. In one embodiment, the second glass frit may comprise 1 wt% to 10 wt%, preferably 1 wt% to 8 wt%, of tungsten oxide. In this range, there may be a thermofluid effect at a higher temperature than the first glass frit.

The second glass frit is bismuth (Bi), lead (Pb), phosphorus (P), germanium (Ge), gallium (Ga), cerium (Ce), iron (Fe), silicon (Si), magnesium (Mg), Cesium (Cs), Strontium (Sr), Molybdenum (Mo), Titanium (Ti), Tin (Sn), Indium (In), Vanadium (V), Barium (Ba), Nickel (Ni), Copper (Cu), At least one element selected from the group consisting of sodium (Na), potassium (K), arsenic (As), cobalt (Co), zirconium (Zr), manganese (Mn), aluminum (Al) and oxides thereof It may include.

The second glass frit may be included in 70% by weight or less, for example 10% by weight to 50% by weight, 20% by weight to 40% by weight, 20% by weight to 70% by weight of the mixture of the glass frit. In this range, there may be a thermofluid effect at a higher temperature than the first glass frit.

(3) third glass frit

The third glass frit may have a glass transition temperature of 290 ° C or more and 360 ° C or less. In the above range, it is possible to improve the electrical and physical properties at the same time to enable continuous sintering during electrode production with the composition for forming an electrode. Specifically, the third glass frit may have a glass transition temperature of 260 ° C. or more and 330 ° C. or less.

The third glass frit includes bismuth (Bi), bismuth-lithium based lithium (Li), lead (Pb), lead-lithium based lithium (Li), bismuth (Bi), tellurium (Te) It may be a bismuth-tellurium-based containing or lead-tellurium-based glass frit containing lead (Pb), tellurium (Te). These may be included alone or two or more kinds. The third glass frit may further include one or more of lithium (Li), tellurium (Te), zinc (Zn), magnesium (Mg), and sodium (Na). The third glass frit includes bismuth (Bi) or lead (Pb), lithium (Li) or tellurium (Te), and lithium (Li), tellurium (Te), zinc (Zn), magnesium (Mg) and By further including at least one of sodium (Na) it can be easily ensured the glass transition temperature range. Preferably, the third glass frit is bismuth-tellurium-zinc-lithium-magnesium, bismuth-lithium-sodium, lead-tellurium-zinc-lithium-magnesium, lead-tellurium-zinc-lithium-sodium It may include one or more of the glass frit.

In one embodiment, the third glass frit comprises from 70% to 99% by weight, for example from 70% to 90% by weight, of total bismuth oxide and tellurium oxide, and total zinc oxide, lithium oxide, and magnesium oxide in one embodiment. It may comprise from 30% by weight to 30% by weight, for example. Within this range, it is possible to easily ensure the glass transition temperature range of the present invention.

In another embodiment, the third glass frit comprises 70% to 99% by weight of total bismuth oxide and lithium oxide, such as 70% to 90% by weight, and 1% to 30% by weight of sodium oxide. For example, it may include 10% by weight to 30% by weight. Within this range, it is possible to easily ensure the glass transition temperature range of the present invention.

In one embodiment, the third glass frit may comprise 5 wt% to 80 wt%, preferably 10 wt% to 75 wt%, 40 wt% to 80 wt% bismuth oxide. In one embodiment, the third glass frit may comprise from 10 wt% to 90 wt%, preferably from 40 wt% to 90 wt%, from 60 wt% to 80 wt% of tellurium oxide. In one embodiment, the third glass frit may comprise 1% to 30% by weight of zinc oxide, preferably 1% to 15% by weight. In one embodiment, the third glass frit may comprise 1 wt% to 50 wt%, preferably 1 wt% to 20 wt%, 1 wt% to 15 wt% of lithium oxide. In one embodiment, the third glass frit may comprise 1 wt% to 30 wt%, preferably 1 wt% to 10 wt% of sodium oxide. In one embodiment, the third glass frit may comprise 1% to 20% by weight of magnesium oxide, preferably 5% to 20% by weight. In the above range, there may be a thermal fluidity effect at a higher temperature than the second glass frit.

The third glass frit is bismuth (Bi), lead (Pb), phosphorus (P), germanium (Ge), gallium (Ga), cerium (Ce), iron (Fe), silicon (Si), magnesium (Mg), Cesium (Cs), Strontium (Sr), Molybdenum (Mo), Titanium (Ti), Tin (Sn), Indium (In), Vanadium (V), Barium (Ba), Nickel (Ni), Copper (Cu), At least one element selected from the group consisting of sodium (Na), potassium (K), arsenic (As), cobalt (Co), zirconium (Zr), manganese (Mn), aluminum (Al) and oxides thereof It may also include.

The third glass frit may be included in 70% by weight or less, for example 10% by weight to 60% by weight, 30% by weight to 60% by weight, 20% by weight to 70% by weight of the mixture of the glass frit. In the above range, there may be a thermal fluidity effect at a higher temperature than the second glass frit.

The first glass frit, the second glass frit, and the third glass frit may be prepared from the metal and / or metal oxide using conventional methods known to those skilled in the art. For example, after mixing the metal and / or metal oxide using a ball mill (plane mill) or planetary mill (planetary mill) and the like, the mixed composition is melted under the conditions of 800 ℃ to 1300 ℃, After quenching at 25 ° C., the resultant can be ground by a disk mill, planetary mill or the like to obtain a glass frit.

The shape and size of each of the first glass frit, the second glass frit, and the third glass frit is not particularly limited. For example, the first glass frit, the second glass frit, and the third glass frit may have the same or different average particle diameter (D50), and an average particle diameter (D50) of 0.1 μm to 10 μm may be used. The shapes of the first glass frit, the second glass frit, and the third glass frit may be the same or different, for example spherical or indefinite. The average particle diameter (D50) is measured using a 1064LD model manufactured by CILAS after dispersing the glass frit powder in isopropyl alcohol (IPA) at 25 ℃ by ultrasonic for 3 minutes.

The first glass frit: the entire second glass frit and the third glass frit in the mixture of glass frits may be included in a weight ratio of 1: 1 to 1:10, for example 1: 1 to 1: 5. In the above range, there can be a high sintering property effect having excellent filling degree in the conductive powder, in particular, silver powder.

The first glass frit: second glass frit: third glass frit in the mixture of glass frits may be included in a weight ratio of 1: 0.1 to 3: 0.1 to 5, such as 1: 0.5 to 2: 1 to 3. In the above range, there can be a high sintering property effect having excellent filling degree in the conductive powder, in particular, silver powder.

The mixture of glass frits may be 1% to 20% by weight, for example 2% to 15% by weight of the composition for forming a solar cell electrode. When contained in the above range, it is possible to improve the electrical and physical properties under various sheet resistance.

Organic vehicle

The organic vehicle imparts suitable viscosity and rheological properties to the composition through mechanical mixing with the inorganic component of the composition for forming a solar cell electrode.

As the organic vehicle, an organic vehicle that is typically used in a composition for forming a solar cell electrode may be used, and may include a binder resin, a solvent, and the like.

As the binder resin, an acrylate-based or cellulose-based resin may be used, and ethyl cellulose is generally used. However, ethyl hydroxyethyl cellulose, nitro cellulose, a mixture of ethyl cellulose and phenol resin, alkyd resin, phenol resin, acrylic ester resin, xylene resin, polybutene resin, polyester resin, urea resin, melamine Resins, vinyl acetate-based resins, wood rosins, or polymethacrylates of alcohols;

Examples of the solvent include hexane, toluene, ethyl cellosolve, cyclohexanone, butyl cellosolve, butyl carbitol (diethylene glycol monobutyl ether), 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 alone or 2 It can mix and use species.

The organic vehicle may be included as the remainder in the composition for forming a solar cell electrode, and may preferably be included in an amount of 1% to 30% by weight based on the total weight. It is possible to secure sufficient adhesive strength and excellent printability in the above range.

additive

The composition for forming a solar cell electrode of the present invention may further include a conventional additive as needed to improve the flow characteristics, process characteristics and stability in addition to the components described above. The additive may be used alone or in combination of two or more of a dispersant, thixotropic agent, plasticizer, viscosity stabilizer, antifoaming agent, pigment, ultraviolet stabilizer, antioxidant, coupling agent and the like. These may be included in 0.1 wt% to 5 wt% of the total weight of the composition for forming a solar cell electrode, but may be changed in content as necessary.

Solar cell electrode and solar cell comprising same

Another aspect of the invention relates to an electrode formed from the composition for forming a solar cell electrode and a solar cell comprising the same. 1 illustrates a structure of a solar cell according to an embodiment of the present invention.

Referring to FIG. 1, a solar cell 100 forms electrodes on a wafer 10 or substrate including a p layer (or n layer) 11 and an n layer (or p layer) 12 as an emitter. The backing composition 21 and the front electrode 23 may be formed by printing and baking the composition. For example, the electrode forming composition may be printed on the back side of the wafer and then dried at a temperature of about 200 ° C. to 400 ° C. for about 10 to 60 seconds to perform a preliminary preparation step for the back electrode. In addition, the composition for forming an electrode on the front surface of the wafer may be printed and dried to perform a preliminary preparation step for the front electrode. Thereafter, a firing process may be performed at 400 ° C. to 950 ° C., preferably 700 ° C. to 950 ° C., for about 30 seconds to 210 seconds to form a front electrode and a rear electrode.

Hereinafter, the configuration and operation of the present invention through the embodiments of the present invention will be described in more detail. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Specific specifications of the components used in the following Examples and Comparative Examples are as follows.

(A) Conductive powder: Spherical silver powder having an average particle diameter (D50) of 1.5 µm (Dowa Hightech CO. LTD, AG-4-8)

(B) glass frit:

(B1) A first glass frit composed of bismuth oxide (15% by weight)-tellurium oxide (70% by weight)-zinc oxide (10% by weight)-lithium oxide (5% by weight) and having a glass transition temperature of 235 ° C.

(B2) bismuth oxide (15% by weight)-tellurium oxide (65% by weight)-zinc oxide (10% by weight)-lithium oxide (5% by weight)-tungsten oxide (5% by weight), glass transition temperature Second glass frit having a temperature of 270 ° C.

(B3) bismuth oxide (15% by weight)-tellurium oxide (65% by weight)-zinc oxide (10% by weight)-lithium oxide (5% by weight)-magnesium oxide (5% by weight), glass transition temperature Glass frit having a temperature of 300 ° C

(B4) Third glass frit composed of bismuth oxide (75% by weight)-lithium oxide (15% by weight)-sodium oxide (10% by weight) and having a glass transition temperature of 310 ° C.

(C) organic vehicle

(C1) organic binder: ethyl cellulose (STD10, Dow Chemical)

(C2) Solvent: Terpineol (Texanol, BCA)

(D) Dispersant: BYK102 (BYK-chemie)

(E) thixotropic agent: Thixatrol ST (Elementis co.)

Example 1

2.5 wt% of the organic binder (C1) was added to 5 wt% of the solvent (C2) to sufficiently dissolve at 60 ° C to prepare a mixture. To the mixture, (B1) first glass frit, (B2) second glass frit, (B3) third glass frit, (B4) third glass frit are further added according to the content (unit: wt%) of Table 1 below. Then, (A) 87 wt% conductive powder was added, and (D) 0.2 wt% dispersant and 0.3 wt% (E) thixotropic agent were added to prepare a composition for forming a solar cell electrode.

Examples 2-4

In Example 1, except that the content of (B1) the first glass frit, (B2) the second glass frit, (B3) the third glass frit, (B4) the third glass frit was changed according to Table 1 below In the same manner to prepare a composition for forming a solar cell electrode.

Examples 5-7

3 wt% of the organic binder (C1) was added to 6.5 wt% of the solvent (C2), and the mixture was sufficiently dissolved at 60 ° C to prepare a mixture. To the mixture, (B1) first glass frit, (B2) second glass frit, (B4) third glass frit are further added according to the contents of Table 1 below, and then (A) 87 wt% conductive powder is added. Then, 0.2 wt% of (D) dispersant and 0.3 wt% of (E) thixotropic agent were added to prepare a composition for forming a solar cell electrode.

Comparative Examples 1 to 4

In Example 1, except that the content of (B1) the first glass frit, (B2) the second glass frit, (B3) the third glass frit, (B4) the third glass frit was changed according to Table 1 below In the same manner to prepare a composition for forming a solar cell electrode.

Comparative Example 5

3 wt% of the organic binder (C1) was added to 6.5 wt% of the solvent (C2), and the mixture was sufficiently dissolved at 60 ° C to prepare a mixture. To the mixture, (B1) first glass frit, (B2) second glass frit, (B3) third glass frit, (B4) third glass frit are further added according to the contents of Table 1 below, and then ( 87 wt% of A) conductive powder was added, and 0.2 wt% of (D) dispersant and 0.3 wt% of (E) thixotropic agent were added to prepare a composition for forming a solar cell electrode.

Example Comparative example One 2 3 4 5 6 7 One 2 3 4 5 (B1) 2 One One One One One One 5 - - - 3 (B2) One 2 One One One 2 - - 5 - - - (B3) One One 2 One - - - - - 5 - - (B4) One One One 2 One - 2 - - - 5 -

After manufacturing the solar cell using the composition for forming a solar cell electrode prepared in Examples and Comparative Examples, the electrical properties and ribbon adhesion was measured for each, and the results are shown in Table 2 below.

Solar cell manufacturing

After texturing the front surface of the wafer (a p-type wafer doped with boron) of the solar cell electrode forming composition prepared in Examples and Comparative Examples, an n + layer was formed of POCl ₃ , and Screen printing was performed on a front surface of a multi crystalline wafer (polysilicon-type silicon wafer having a sheet resistance of 90Ω) on which silicon nitride (SiNx: H) was formed as an antireflection film. The screen mask SUS360 type was used for printing, and the thickness was 15 μm, the line width was 30 μm, and the number of fingers was 100.

 Then, it was dried for 1 minute at 300 ~ 400 ℃ using an infrared drying furnace. After printing the aluminum paste on the back of the wafer and dried in the same manner. The cell formed by the above process was fired for 50 seconds at 400 ~ 900 ℃ using a belt-type kiln to manufacture a solar cell.

(1) Electrical characteristics: Fill factor (FF, unit:%) and conversion efficiency (Eff, unit:%) were measured for the solar cell manufactured as described above using a solar cell efficiency measuring instrument (Halm). .

(2) Ribbon adhesion: Flux (BONKOTE, BON-102) was applied to the cell's busbar, and Sn / Pb ribbon (Huaguangda, TM-A) was about 360 ° C using a soldering iron (HAKKO, FX-838). To the busbar. The attached ribbon was evaluated for adhesion (unit: N / mm) at a 180 ° angle using a tensile strength tester (Instron, H5KT).

Example Comparative example One 2 3 4 5 6 7 One 2 3 4 5 FF 77.4 77.2 77.0 77.1 77.3 77.2 77.0 75.4 76.8 74.2 68.5 74.2 Eff 17.8 17.8 17.7 17.6 17.8 17.6 17.6 16.5 17.0 16.2 13.8 16.0 Ribbon adhesion 4 4.2 4.2 3.8 4.2 4.1 4.0 2.1 1.5 1.0 0.5 1.8

As shown in Table 2, the composition for forming a solar cell electrode of the present invention was excellent in the electrical properties of the Fill Factor and the conversion efficiency, it was possible to implement the electrode with excellent physical properties of the ribbon adhesion.

On the other hand, Comparative Example, which is a composition that does not contain a mixture of the glass frit of the present invention was excellent in the electrical properties of the Fill Factor and the conversion efficiency, and the physical properties of the ribbon adhesion force could not be achieved at the same time.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (11)

Conductive powder; Mixtures of glass frits; And organic vehicles,
The mixture of the glass frit includes at least one of a second glass frit having a glass transition temperature of 260 ° C. or more and less than 290 ° C. and a third glass frit having a glass transition temperature of 290 ° C. or more and 360 ° C. or less; And a first glass frit having a glass transition temperature of 220 ° C. or more and less than 250 ° C., the composition for forming a solar cell electrode.
The method of claim 1,
The first glass frit is bismuth-tellurium-zinc-lithium-based or lead-tellurium-zinc-lithium-based glass frit, composition for forming a solar cell electrode.
The method of claim 1,
The second glass frit is bismuth-tellurium-zinc-lithium-tungsten-based or lead-tellurium-zinc-lithium-tungsten-based glass frit, composition for forming a solar cell electrode.
The method of claim 1,
The third glass frit is bismuth-tellurium-zinc-lithium-magnesium-based glass frit, bismuth-lithium-sodium-based glass frit, lead-tellurium-zinc-lithium-magnesium, lead-tellurium-zinc-lithium- A composition for forming a solar cell electrode, comprising one or more of sodium-based glass frits.
The method of claim 1,
In the mixture of the glass frit the first glass frit is 10% to 80% by weight, the second glass frit is 0% to 70% by weight, the third glass frit is 0% to 70% by weight and the agent The total composition of 2 glass frits and the third glass frit is more than 0% by weight, the composition for forming a solar cell electrode.
The method of claim 1,
The first glass frit: the second glass frit and the third glass frit in the mixture of the glass frit is a composition for forming a solar cell electrode, comprising a weight ratio of 1: 1 to 1:10.
The method of claim 1,
The first glass frit: the second glass frit: the third glass frit in the mixture of the glass frit is a composition for forming a solar cell electrode, which is included in a weight ratio of 1: 0.1 to 3: 0.1 to 5.
The method of claim 1,
The mixture of the glass frit comprises the first glass frit, the second glass frit and the third glass frit, composition for forming a solar cell electrode.
The method of claim 1,
The composition is
60 wt% to 95 wt% of the conductive powder,
1% to 20% by weight of the mixture of glass frit,
A composition for forming a solar cell electrode, comprising the remaining amount of the organic vehicle.
The method of claim 1,
The composition further comprises at least one additive of a dispersant, thixotropic agent, plasticizer, viscosity stabilizer, antifoaming agent, pigment, UV stabilizer, antioxidant, coupling agent, the composition for forming a solar cell electrode.
An electrode formed of the composition for forming a solar cell electrode according to any one of claims 1 to 10.

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