TWI697015B - Paste composition of solar cell front electrode and manufacturing method thereof - Google Patents

Abstract

The paste composition for a front electrode of a solar cell in the present invention comprises conductive metal powder; glass frit comprising PbO, Bi ₂O ₃, TeO ₂, Ag ₂O and Li ₂O; and organic vehicle. The front electrode of a solar cell manufactured from the paste composition in the present invention shows low series resistance to provide advantage in manufacturing a solar cell with a higher efficiency.

Description

Paste composition for solar cell front electrode and preparation method thereof

The present invention relates to a paste composition for a solar cell front electrode comprising conductive metal powder for a solar cell front electrode, glass frit, and an organic vehicle.

Recently, due to concerns about environmental pollution and energy depletion caused by fossil energy, research and development of the next generation of clean energy have been actively carried out. Among them, solar energy is rich in resources and does not emit pollutants during the production of energy. Therefore, in order to use it as an energy source to replace fossil energy, a lot of research has been carried out. In general, the research on the use of solar cells to convert solar energy into electrical energy is more many.

However, such a solar cell has a problem that the conversion efficiency as the ratio of incident solar energy to output electric energy is low, and therefore a large-scale equipment is required to produce a large amount of electricity, and the energy efficiency is low relative to the cost of the solar cell.

The efficiency of such a solar cell depends on various factors, for example, it is closely related to the material of the electrode, the material of the semiconductor substrate, the laminated structure of the electrode or semiconductor substrate, the shape of the electrode or semiconductor substrate, and the resistance of the electrode. In particular, in the case of the front electrode, due to the characteristics of the solar cell, sunlight cannot be directly applied to the semiconductor substrate, but penetrates through the front electrode. Therefore, in order to improve the efficiency of the solar cell, this front electrode needs to ensure The light rate reduces the resistance between the front electrode and the semiconductor substrate.

Korean Patent No. 10-1210112 also discloses a glass frit that can improve the photoelectric conversion efficiency. However, in this case, there is still a problem of exhibiting relatively low photoelectric conversion efficiency.

Existing technical literature

Patent Literature

Patent Document 1: Korean Patent No. 10-1210112

An object of the present invention is to provide a paste composition for preparing a solar cell front electrode with low series resistance and high efficiency.

Another object of the present invention is to provide a paste composition for a front electrode of a solar cell having a relatively low lead oxide content.

The paste composition for a front electrode of a solar cell according to the present invention includes: a conductive metal powder; a glass frit containing PbO, Bi ₂ O ₃ , TeO ₂ , Ag ₂ O, and Li ₂ O; and an organic vehicle.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may include 15% to 30% by weight of PbO, 20% to 40% by weight of Bi ₂ O ₃ , and 30% by weight % To 50% by weight of TeO ₂ , 1% to 5% by weight of Ag ₂ O, and 1% to 5% by weight of Li ₂ O.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may further include SiO ₂ , BaO, ZnO, B ₂ O ₃ , Na ₂ O, CaO, WO ₃ and MgO. One or more glass frit additives.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may further include 0.1% to 20% by weight of the glass frit additive.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may be 15% to 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20 A first glass frit of TeO _{2 by} weight to 45% by weight, and Li ₂ O by 1% to 5% by weight, and Bi ₂ O _{3 by} 1% to 25% by weight, 40% to 80% by weight A second glass frit of TeO ₂ , 1% to 25% by weight of Ag ₂ O, and 1% to 10% by weight of Li ₂ O.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the weight ratio of the first glass frit to the second glass frit may be 1:0.1 to 2.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may be a mixture of a first glass frit and a third glass frit, and the first glass frit may include 15% by weight to 30% by weight % PbO, 20% to 55% by weight Bi ₂ O ₃ , 20% to 45% by weight TeO ₂ , and 1% to 5% by weight Li ₂ O, the third glass frit contains 8% by weight % To 25% by weight PbO, 15% to 45% by weight Bi ₂ O ₃ , 35% to 55% by weight TeO ₂ , 1% to 10% by weight Li ₂ O, 0.5% to 5% by weight % Ag ₂ O, and 0.1% to 3% by weight of SiO ₂ .

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the weight ratio of the first glass frit to the third glass frit may be 1:0.1 to 2.

The paste composition for a front electrode of a solar cell according to an embodiment of the present invention may include 1% by weight to 10% by weight of the above glass frit.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the conductive metal powder may be selected from gold, silver, copper, nickel, aluminum, palladium, chromium, cobalt, tin, lead, zinc, One or more of iron, tungsten, magnesium and their alloys.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the conductive metal powder may be a silver powder containing internal pores.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the organic carrier may be selected from Trimethyl Pentanyl Diisobutylate (Trimethyl Pentanyl Diisobutylate) and Dibasic ester ), Diethylene glycol monobutyl ether, Diethylene Glycol n-butyl Ether Acetate, Diethylene glycol monobutyl ether, Diethylene glycol monoethyl ether, Diethylene glycol monobutyl ether , Diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether propionate, diethyl ether propylene At least one of acid ester, terpineol, propylene glycol monomethyl ether acetate, dimethylamino formaldehyde, methyl ethyl ketone, γ-butyrolactone, ethyl lactate, and ester alcohol (Texanol) The solvent is prepared by adding one or more resins selected from cellulose resins, acrylic resins, and polyethylene resins.

The present invention also provides a method for preparing a paste composition for a front electrode of a solar cell. The method for preparing a paste composition for a front electrode of a solar cell according to the present invention includes: a step of preparing a first glass frit, which is 15% by weight to 30% Mix PbO by weight, Bi ₂ O ₃ by 20% to 55% by weight, TeO _{2 by} 20% to 45% by weight, and Li ₂ O by 1% to 5% by weight, mix, and cool after melting; The preparation step of the second glass frit is to combine 1 wt% to 25 wt% Bi ₂ O ₃ , 40 wt% to 80 wt% TeO ₂ , 1 wt% to 25 wt% Ag ₂ O, and 1 wt% to 10 after wt% of Li ₂ O were mixed, melted and cooled; and a mixing step of mixing the first materials and a second glass frit.

The preparation method of the paste composition for solar cell front electrode according to the present invention includes: a first glass frit preparation step, in which 15% to 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20% to 45% by weight of TeO ₂ and 1% to 5% by weight of Li ₂ O are mixed and cooled after melting; the third glass frit preparation step, 8% to 25% by weight of PbO, 15% to 45% by weight Bi ₂ O ₃ , 35% to 55% by weight TeO ₂ , 1% to 10% by weight Li ₂ O, 0.5% to 5% by weight Ag ₂ O, and 0.1 SiO ₂ by weight to 3% by weight is mixed, melted, and cooled; and in the mixing step, the first glass frit and the third glass frit are mixed.

The invention also provides a solar cell front electrode. The solar cell front electrode according to the invention can be prepared from the paste composition for solar cell front electrode according to an embodiment of the invention.

The present invention also provides a solar cell. The solar cell according to the present invention may use the solar cell front electrode according to an embodiment of the present invention.

The paste composition for a front electrode of a solar cell according to the present invention has the advantage that a glass frit containing PbO, Bi ₂ O ₃ , TeO ₂ , Ag ₂ O, and Li ₂ O can be used to prepare a solar cell with low series resistance Front electrode.

Hereinafter, the paste composition for solar cell front electrodes of the present invention will be described in detail. Among them, unless otherwise defined, the technical terms and scientific terms used have the meanings generally understood by those of ordinary skill in the technical field to which the present invention belongs, and omission in the following description may obscure the subject matter of the present invention and redundant practices. Know the function and structure description.

The present invention relates to a paste composition for a front electrode of a solar cell containing a conductive metal powder, a glass frit containing PbO, Bi ₂ O ₃ , TeO ₂ , Ag ₂ O, and Li ₂ O, and an organic carrier.

When the solar cell is prepared using the composition according to the present invention, it has the advantages of low series resistance and high conversion efficiency.

Specifically, in the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may include 15% to 30% by weight of PbO and 20% to 40% by weight of Bi ₂ O _3. 30% to 50% by weight TeO ₂ , 1% to 5% by weight Ag ₂ O, and 1% to 5% by weight Li ₂ O.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may contain only PbO as a lead-containing component.

The paste composition for a front electrode of a solar cell according to an embodiment of the present invention has an advantage that the photoelectric efficiency can be further improved.

Specifically, the glass frit according to an embodiment of the present invention contains the oxide having the composition as described above, so that the photoelectric conversion efficiency can be improved. In detail, when a glass frit containing a metal oxide having a composition as described above is used to prepare a front electrode of a solar cell, the photoelectric conversion efficiency can be improved by more than 5% relative to the case where a glass frit excluding a part of the composition is used. advantage. In other words, the paste composition for a front electrode of a solar cell according to an embodiment of the present invention contains the oxide having the composition as described above, and even if a lower lead oxide is used, a solar cell with excellent efficiency can be prepared by virtue of these advantages To minimize the leakage of lead oxide during the subsequent anti-reflection film etching process, so it has the advantage of environmental protection.

Furthermore, the glass frit according to an embodiment of the present invention may further include one or more glass frits selected from SiO ₂ , BaO, ZnO, B ₂ O ₃ , Na ₂ O, CaO, WO ₃ and MgO. The additives, specifically, relative to the total weight of the glass frit, may contain 0.1 to 20% by weight of such additives. When the glass frit additive described above is further included, there is an advantage that a more efficient solar cell can be produced by increasing the open circuit voltage.

The glass frit of the present invention may be composed of an oxygen polyhedron having a network structure containing oxygen, specifically, a random network structure. The softening point of the glass frit is preferably 300°C to 500°C, and the viscosity of the glass melt is appropriate within the above range, so it is preferable in terms of electrode formation, but it is not limited thereto.

The above glass frit can be prepared by a conventional method. For example, after addition at the above composition ratio, it can be melted and quenched under the conditions of 900°C to 1300°C. The mixed composition can be pulverized by a ball mill, a disk mill, a planetary mill, or the like to obtain a glass frit. The average particle diameter (D50) of the pulverized glass frit may be 0.1 micrometer (μm) to 5 micrometers, preferably, 0.5 micrometer to 3 micrometers, but it is not limited thereto.

Furthermore, the above-mentioned glass frit according to an embodiment of the present invention may be a mixture of a first glass frit and a second glass frit, the first glass frit includes 15% to 30% by weight of PbO, 20% to 55% by weight Bi ₂ O ₃ , 20% to 45% by weight of TeO ₂ , and 1% to 5% by weight of Li ₂ O, the second glass frit contains 1% to 25% by weight of Bi ₂ O ₃ , 40% to 80% by weight of TeO ₂ , 1% to 25% by weight of Ag ₂ O, and 1% to 10% by weight of Li ₂ O.

That is, in the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the glass frit may be a mixture of a first glass frit containing lead and a second glass frit not containing lead. As described above, when the first glass frit and the second glass frit are prepared and mixed by a separate method, the series resistance can be more excellent than when a single glass frit is simply mixed to prepare a single glass frit. Although it has not been clearly confirmed, it is judged to be an effect due to a separate heat treatment in the preparation process of the glass frit, specifically, when the paste composition for a front electrode of a solar cell according to an embodiment of the present invention simultaneously contains The first glass frit and the second glass frit of the composition described above may have a series resistance lower than 10% compared to a case where a single glass frit is used to prepare a solar cell, more specifically, may have a lower 10% to 30 The% series resistance has the advantage of showing excellent energy conversion efficiency due to low series resistance.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the first glass frit may include only PbO as a lead-containing component, and the second glass frit may not include a lead-containing component.

In detail, in the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the weight ratio of the first glass frit to the second glass frit may be 1:0.1 to 2, specifically, it may be 1: 0.2 to 1.5, which has the advantage of showing a lower series resistance in the above range.

In the paste composition for a front electrode of a solar cell according to another embodiment of the present invention, the above-mentioned glass frit may be a mixture of a first glass frit and a third glass frit, and the first glass frit includes 15% by weight to 30% PbO by weight, Bi ₂ O ₃ by 20% to 55% by weight, TeO _{2 by} 20% to 45% by weight, and Li ₂ O by 1% to 5% by weight, the third glass frit contains 8 PbO by weight to 25% by weight, Bi ₂ O ₃ by weight to 15% by weight, TeO _{2 by} 35% to 55% by weight, Li ₂ O by 1% to 10% by weight, 0.5% to 5% by weight Ag ₂ O by weight and SiO ₂ from 0.1% to 3% by weight.

As described above, when the first glass frit and the third glass frit are separately prepared and mixed, the series resistance can be lowered by 10% or more compared to the case where a single glass frit is prepared by mixing individual oxides.

In the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the first glass frit and the third glass frit may include only PbO as a lead-containing component.

In detail, in the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the weight ratio of the first glass frit to the third glass frit may be 1:0.1 to 2, specifically, it may be 1: 0.2 to 1.5, which has the advantage of showing a lower series resistance in the above range.

Furthermore, in order to increase the open circuit voltage, each glass frit according to an embodiment of the present invention may independently include one selected from SiO ₂ , BaO, ZnO, B ₂ O ₃ , Na ₂ O, CaO, WO ₃ and MgO One or two or more glass frit additives, and each glass frit may independently contain 0.1 to 20% by weight of the above glass frit additive, but the present invention is not limited thereto.

In addition, in order to ensure excellent conversion efficiency and prevent a decrease in solderability, etc., the paste composition for a front electrode of a solar cell according to an embodiment of the present invention may include the above glass frit from 0.1% by weight to 15% by weight. The invention is not limited to this.

The paste composition for a front electrode of a solar cell according to the present invention contains a conductive metal powder, and the above-mentioned conductive metal powder according to the present invention may be a metal powder generally used when preparing an electrode for a solar cell, for example, it may contain a material selected from silver, At least one of gold, copper, nickel, aluminum, palladium, chromium, cobalt, tin, lead, zinc, iron, tungsten, magnesium, and their alloys, preferably, can have excellent conductivity The crystalline inorganic semiconductor forms a strong interface with silver (Ag).

As the conductive metal powder, preferably, the purity of the silver powder can be 80% or more, and more preferably, the purity of the silver powder can be 95% or more, as long as the purity satisfies the conditions normally required for the electrode, no special limited.

The form of the conductive metal powder is not particularly limited as long as it is a form known in the technical field of the present invention. For example, a spherical shape, a flake shape, or a combination thereof may be used, but is not limited thereto.

In addition, the particle size of the conductive metal powder can be adjusted to an appropriate range in consideration of the required firing rate and the influence of the process of forming the electrode. In the present invention, in order to achieve the effect of reducing contact resistance, the average particle diameter of the conductive metal powder may have a size of about 0.1 to 5 microns, but it is not limited thereto.

From the viewpoints of preventing viscosity reduction and phase separation, the above-mentioned glass frit composition according to an embodiment of the present invention may include 60% by weight to 99.5% by weight of conductive metal powder, preferably, may contain 70% by weight to 99.5 The conductive metal powder by weight may more preferably contain 80 to 99.5% by weight of conductive metal powder, but the invention is not limited thereto.

In addition, in the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, the conductive metal powder may be a silver powder containing internal pores. As such, when using silver powder containing internal pores as the conductive metal powder, it has the advantages of excellent sintering characteristics, reduced electrode resistance, and improved battery efficiency. Furthermore, the silver powder containing internal pores may have a spherical shape, in which the diameter may be 0.1 to 5 microns, but it can of course be adjusted to an appropriate range.

The paste composition for solar cell front electrodes according to the present invention contains an organic vehicle. The organic carrier according to the present invention can adjust the viscosity of the paste composition for the front electrode of a solar cell, and can function as a dispersion medium for solid particles. Specifically, the organic carrier is not limited as long as it is generally used for solar cell electrode pastes, but the organic binder may be a binder solution dissolved in a solvent.

Specifically, the organic carrier according to an embodiment of the present invention may be selected from trimethyl pentanyl diisobutylate (Trimethyl Pentanyl Diisobutylate), dibasic ester (Dibasic ester), diethylene glycol monobutyl Diethylene glycol monobutyl ether, Diethylene Glycol n-butyl Ether Acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether Acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether propionate, diethyl ether propionate, terpineol (terpineol ), Propylene glycol monomethyl ether acetate, dimethylamino formaldehyde, methyl ethyl ketone, γ-butyrolactone, ethyl lactate, and ester alcohol (Texanol) in one or more solvents It is made from more than one resin among cellulose resin, acrylic resin, and polyethylene resin.

Wherein, the cellulose-based resin may be selected from ethyl cellulose, methyl cellulose, nitrocellulose, carboxymethyl cellulose, hydroxy cellulose, ethyl hydroxyethyl cellulose, amine ethyl cellulose, oxygen One or more of ethyl cellulose, hydroxyethyl cellulose, benzyl cellulose, trimethyl cellulose, ethyl hydroxymethyl cellulose, etc. The acrylic resin may be selected from methyl acrylate, One or more of ethyl acrylate, butyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl acrylate, acrylate, and the like. In addition, the polyethylene-based resin may include one or more selected from polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, and the like, but the present invention is not limited thereto.

Wherein, the above-mentioned organic carrier may include 10% by weight to 30% by weight of organic binder and the remaining amount of solvent, but the present invention is not limited thereto. Furthermore, from the viewpoint of preventing the decrease in conductivity and ensuring uniform dispersion of the paste composition, the paste composition for a front electrode of a solar cell according to an embodiment of the present invention may contain 0.1 to 35% by weight of an organic vehicle, Preferably, it may contain 10 to 25% by weight of an organic carrier, but the present invention is not limited thereto.

In addition, if necessary, the paste composition for a front electrode of a solar cell according to an embodiment of the present invention may further contain additives that are usually added. Specifically, such additives may contain one or more kinds selected from thickeners, thixotropic agents, stabilizers, dispersing agents, thixotropic agents, leveling agents, defoamers, and the like. From the viewpoint of ensuring conductivity, dispersibility and low resistance, the content of such additives is 0.1% by weight to 10% by weight relative to the total paste composition, but the present invention is not limited thereto.

The invention also provides a preparation method of the paste composition for the front electrode of the solar cell.

The preparation method of the paste composition for solar cell front electrode according to the present invention includes: a first glass frit preparation step, in which 15% to 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20% to 45% by weight of TeO ₂ and 1% to 5% by weight of Li ₂ O are mixed and melted and cooled; the preparation step of the second glass frit is 1% to 25% by weight of Bi ₂ O ₃ , 40% to 80% by weight of TeO ₂ , 1% by weight to 25% by weight of Ag ₂ O, and 1% by weight to 10% by weight of Li ₂ O are mixed and cooled after melting; and the mixing step, The above-mentioned first glass frit and second glass frit are mixed.

In the method for preparing a paste composition for a front electrode of a solar cell according to an embodiment of the present invention, only PbO may be mixed as a lead-containing component in the preparation step of the first glass frit, and in the preparation of the second glass frit The lead-containing component may not be mixed in the step.

According to another embodiment of the present invention, a method for preparing a paste composition for a front electrode of a solar cell may include: a step of preparing a first glass frit, combining 15% by weight to 30% by weight of PbO, and 20% by weight to 55% by weight % Bi ₂ O ₃ , 20% by weight to 45% by weight TeO ₂ , and 1% by weight to 5% by weight Li ₂ O are mixed and cooled after melting; the third glass frit preparation step, 8% by weight PbO to 25% by weight, Bi ₂ O ₃ to 15% to 45% by weight, TeO ₂ to 35% to 55% by weight, Li ₂ O to 1% to 10% by weight, 0.5% to 5% by weight Ag ₂ O and 0.1% to 3% by weight of SiO ₂ are mixed, melted and cooled; and a mixing step of mixing the first glass frit and the third glass frit.

In the method for preparing a paste composition for a front electrode of a solar cell according to an embodiment of the present invention, only PbO is mixed as a lead-containing component in the preparation steps of the first glass frit and the third glass frit.

As described above, in the preparation method of the paste composition for solar cell front electrode according to an embodiment of the present invention, by separately preparing and mixing the first glass frit and the second glass frit or the first glass frit and the third glass As compared with the case where a single glass frit is prepared and mixed, it has the advantage that the prepared solar cell exhibits a lower series resistance.

Specifically, in the preparation method of the paste composition for a front electrode of a solar cell according to an embodiment of the present invention, melting in the preparation steps of each glass frit may be independently performed at a temperature of 900°C to 1400°C. Furthermore, such melting can be performed for 10 hours to 12 hours, specifically, for 10 hours to 4 hours, but there is no limitation on the temperature and time range in which the above-mentioned composition can be melted.

Furthermore, in the preparation steps of each glass frit, the above cooling means to lower the temperature of the melt to normal temperature, and the cooling method may be a method of quenching with pure water, but the present invention is not limited to this . In addition, each glass frit preparation method may include a step of finally preparing the glass frit by crushing the quenched melt. Among them, a conventional pulverizer can be used for pulverization, and the average particle diameter (D50) of the glass frit prepared by pulverization may be 0.1 μm to 5 μm, but the present invention is not limited thereto.

The present invention also provides a solar cell front electrode. The solar cell front electrode according to the present invention may be prepared using the paste composition for solar cell front electrode as described above.

Specifically, the front electrode according to an embodiment of the present invention may include printing the paste composition on the substrate by methods such as screen printing, gravure printing, offset printing, roll-to-roll printing, aerosol printing, or inkjet printing. The process of drying and firing is performed afterwards, but the present invention is not limited to this.

Furthermore, the present invention provides a solar cell. The solar cell according to the present invention can be prepared by including the solar cell front electrode as described above. The solar cell according to an embodiment of the present invention has a low series resistance, and thus has a characteristic of exhibiting high energy conversion efficiency.

Hereinafter, the present invention will be specifically described by examples. The embodiments described below are merely to facilitate understanding of the present invention, and the present invention is not limited to the embodiments.

Preparation of glass frit

After mixing the components including the composition of Table 1 below, it was melted at 1100° C. for 30 minutes and quenched with pure water (H ₂ O). The quenched glass melt was crushed with an Attrition-mill to make it have an average particle size of 1 to 3 microns, and a glass frit was prepared.

Table 1 glass PbO Bi ₂ O ₃ TeO ₂ Ag ₂ O Li ₂ O SiO ₂ BaO ZnO total Glass frit (1) 17 28 45 5 3.5 1.5 100 Glass frit (2) 28 32 30 - 3 5 - 2 100 Glass frit (3) - 9 60 10 5 2.5 3.5 10 100 Glass frit (4) 10 55 15 - 7 8 2.5 2.5 100 Glass frit (5) 32 15 45 - 2 3 1.5 1.5 100 Glass frit (6) - 15 65 13 2.5 2 1.5 1 100

Example 1

Preparation of paste composition for solar cell front electrode

Evenly mix 3% by weight of the glass frit (1) of Table 1 above, 89.5% by weight of silver powder having a particle diameter of 0.1 to 3 microns as a conductive metal powder, and 1% by weight of cellulose ester as an organic binder ( CAB, EASTMAN, Ethyl Cellulose Resin (ECN, AQUALON, USA), 2% by weight of trimethylpentyl diisobutyrate (TXIB) as an organic solvent , Trimethyl Pentanyl Diisobutylate), 2.5% by weight of dibasic ester (Dibasic ester, Tokyo Chemical Industry Co., Ltd. (TCI), Japan, dimethyl adipate / dimethyl glutarate / dimethyl succinate (Dimethyl adipate / dimethyl glutarate/dimethyl succinate (mixture) and 1% by weight of butyl carbitol (BC, BUTYL CARBITOL), thereby preparing a paste composition for solar cell front electrodes.

Preparation of solar cells

In the preparation of solar cells, phosphorus (P) is doped by a diffusion process of POCl _{3 in} a tube furnace at a temperature of 810°C using a 156 mm × 156 mm single crystal silicon wafer and formed A semiconductor layer with a sheet resistance of 95Ω/ is deposited on the semiconductor layer by chemical vapor deposition (plasma enhanced chemical vapor deposition (PECVD) method) and using precursors SiH ₄ and NH ₃ to deposit a silicon nitride film, Thus, a thickness of 75 nm was formed and an anti-reflection film was formed.

In the rear electrode, the above electrode paste composition containing aluminum powder instead of silver powder was applied to the rear surface by a screen printing method at a thickness of 30 μm, and then dried in a drying oven at 250° C. for 60 seconds . In the front electrode, the paste composition prepared in Examples and Comparative Examples of the present invention was applied to a thickness of 20 μm by a screen printing method, and then dried in a drying oven at a temperature of 200° C. for 60 seconds. The printed solar cell was subjected to a firing process for 1 minute in a belt firing furnace at a temperature of 820°C, thereby preparing a solar cell.

Example 2

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (1) of Table 1 above, 1.5% by weight of the glass frit (1) and 1.5% by weight of the glass frit (2) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 3

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (1) of Table 1 above, 2.4% by weight of the glass frit (1) and 0.6% by weight of the glass frit (2) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 4

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (1) of Table 1 above, 0.9% by weight of the glass frit (1) and 2.1% by weight of the glass frit (2) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 5

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (1) of Table 1 above, 2.7% by weight of the glass frit (1) and 0.3% by weight of the glass frit (2) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 6

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (2) of Table 1 above, 1.5% by weight of the glass frit (2) and 1.5% by weight of the glass frit (3) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 7

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (2) of Table 1 above, 2.4% by weight of the glass frit (2) and 0.6% by weight of the glass frit (3) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 8

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (2) of Table 1 above, 0.9% by weight of the glass frit (2) and 2.1% by weight of the glass frit (3) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Example 9

Prepared by the same method as Example 1, instead of 3% by weight of the glass frit (2) of Table 1 above, 2.7% by weight of the glass frit (2) and 0.3% by weight of the glass frit (3) were mixed to prepare a paste Agent, and a solar cell was prepared using the paste.

Comparative example 1

It was prepared by the same method as Example 1, instead of the glass frit (1) to (3), 3% by weight of the glass frit (4) was mixed to prepare a paste, and a solar cell was prepared using the paste.

Comparative example 2

It was prepared by the same method as Example 1, instead of the glass frits (1) to (3), 3% by weight of the glass frit (5) was mixed to prepare a paste, and a solar cell was prepared using the paste.

Comparative Example 3

It was prepared by the same method as Example 1, instead of the glass frits (1) to (3), 3% by weight of the glass frit (6) was mixed to prepare a paste, and a solar cell was prepared using the paste.

Evaluation of the characteristics of the prepared solar cell

A solar cell printed/fired with a pattern of 4 bus bars, a finger line width of 50 microns, and a number of fine lines of 105 was prepared and its characteristics were evaluated.

For the solar cells of the examples and comparative examples, the open circuit voltage (Voc), the short-circuit maximum current (Isc), the charging factor (FF), the series resistance (Rs), and the energy conversion efficiency were measured using a solar simulator (Solar simulator) Effi.) and shown in Table 2 below.

Table 2 Glass frit (1) Glass frit (2) Glass frit (3) Glass frit (4) Glass frit (5) Glass frit (6) Voc Isc FF Rs Effi. weight(%) (V) (A) (%) (Milliohm (mΩ)) (%) Example 1 3 0.628 8.631 76.05 7.12 16.94 Example 2 1.5 1.5 0.632 8.637 78.59 5.68 17.63 Example 3 2.4 0.6 0.633 8.629 76.87 6.67 17.26 Example 4 0.9 2.1 0.632 8.616 78.22 5.84 17.49 Example 5 2.7 0.3 0.633 8.600 77.61 6.66 17.37 Example 6 1.5 1.5 0.630 8.741 78.69 5.45 17.81 Example 7 2.4 0.6 0.630 8.740 78.16 5.64 17.70 Example 8 0.9 2.1 0.630 8.69 78.27 6.66 17.60 Example 9 2.7 0.3 0.630 8.673 77.83 5.81 17.49 Comparative example 1 3 0.630 8.659 27.69 52.73 6.21 Comparative example 2 3 0.623 8.783 43.26 28.58 9.72 Comparative Example 3 3 0.625 8.692 71.60 8.372 15.99

As summarized in Table 2, the solar cell prepared by the paste composition for the front electrode of the solar cell of the present invention shows that the series resistance between the electrode and the solar cell substrate in the examples of the present invention is reduced compared to the comparative example. It can be seen that the open circuit voltage and charging factor characteristics are improved, and it has excellent solar cell energy conversion efficiency.

As described above, specific matters and limited embodiments are described in the present invention, but this is provided only for a more comprehensive understanding of the present invention, and the present invention is not limited by the above-mentioned embodiments, and the technology to which the present invention belongs Those skilled in the art can make various modifications and changes from these descriptions.

Therefore, the spirit of the present invention should not be limited to the illustrated embodiments for interpretation, and the patent application scope of the invention set forth below and all equivalent or equivalent variants of the patent application scope of the invention belong to the scope of the spirit of the invention .

:no.

:no.

Claims (15)

A paste composition for a front electrode of a solar cell, comprising: a conductive metal powder; a glass frit; and an organic vehicle, wherein the glass frit contains 15 to 30% by weight of PbO, and 20 to 40% by weight of Bi ₂ O ₃ , 30% to 50% by weight TeO ₂ , 1% to 5% by weight Ag ₂ O, and 1% to 5% by weight Li ₂ O. The paste composition for a front electrode of a solar cell according to claim 1, wherein the glass frit further contains one selected from the group consisting of SiO ₂ , BaO, ZnO, B ₂ O ₃ , Na ₂ O, CaO, WO ₃ and MgO One or more glass frit additives. The paste composition for a front electrode of a solar cell according to claim 2, wherein the glass frit further contains 0.1 to 20% by weight of the glass frit additive. A paste composition for a front electrode of a solar cell, comprising: conductive metal powder; glass frit; and an organic vehicle, wherein the glass frit is a mixture of a first glass frit and a second glass frit, the first glass frit contains 15 weight % To 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20% to 45% by weight of TeO ₂ , and 1% to 5% by weight of Li ₂ O, the second glass frit Contains 1 to 25% by weight of Bi ₂ O ₃ , 40 to 80% by weight of TeO ₂ , 1 to 25% by weight of Ag ₂ O, and 1 to 10% by weight of Li ₂ O. The paste composition for a front electrode of a solar cell according to claim 4, wherein the weight ratio of the first glass frit: the second glass frit is 1: 0.1 to 2. A paste composition for a front electrode of a solar cell, comprising: conductive metal powder; glass frit; and an organic vehicle, wherein the glass frit is a mixture of a first glass frit and a third glass frit, the first glass frit contains 15 weight % To 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20% to 45% by weight of TeO ₂ , and 1% to 5% by weight of Li ₂ O, the third glass frit Contains 8 wt% to 25 wt% of PbO, 15 wt% to 45% by weight of Bi ₂ O3, 35 wt% to 55% by weight of TeO ₂ , 1 wt% to 10 wt% of Li ₂ O, 0.5 wt% to 5% by weight of Ag ₂ O, and 0.1% to 3% by weight of SiO ₂ . The paste composition for a front electrode of a solar cell according to claim 6, wherein the weight ratio of the first glass frit: the third glass frit is 1: 0.1 to 2. The paste composition for a front electrode of a solar cell according to claim 1, wherein the paste composition for a front electrode of a solar cell contains 0.1 to 15% by weight of the glass frit. The paste composition for a front electrode of a solar cell according to claim 1, wherein the conductive metal powder is selected from gold, silver, copper, nickel, aluminum, palladium, chromium, cobalt, tin, lead, zinc, iron, One or more of tungsten, magnesium and their alloys. The paste composition for a front electrode of a solar cell according to claim 1, wherein the conductive metal powder is a silver powder containing internal pores. The paste composition for a front electrode of a solar cell according to claim 1, wherein the organic carrier is selected from trimethylpentyl diisobutyrate, dibasic ester, diethylene glycol monobutyl ether, Ethylene glycol n-butyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether B Ester, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether propionate, diethyl ether propionate, terpineol, propylene glycol monomethyl ether acetate, dimethylamino formaldehyde, methyl ethyl ketone , Γ-butyrolactone, ethyl lactate, and ester alcohols are prepared by adding one or more resins selected from cellulose-based resins, acrylic resins, and polyethylene-based resins. A method for preparing a paste composition for a front electrode of a solar cell, comprising: a preparation step of a first glass frit, combining 15% to 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20 TeO ₂ to 45% by weight and Li ₂ O to 1% to 5% by weight are mixed, melted, and cooled; the preparation step of the second glass frit is 1% to 25% by weight of Bi ₂ O _3. 40% to 80% by weight of TeO ₂ , 1% to 25% by weight of Ag ₂ O, and 1% to 10% by weight of Li ₂ O are mixed and cooled after melting; and the mixing step, mixing The first glass frit and the second glass frit. A method for preparing a paste composition for a front electrode of a solar cell, comprising: a preparation step of a first glass frit, combining 15% to 30% by weight of PbO, 20% to 55% by weight of Bi ₂ O ₃ , 20 TeO _{2 by} weight to 45% by weight, and Li ₂ O by 1% to 5% by weight are mixed and cooled after melting; the third glass frit preparation step is to mix 8% to 25% by weight of PbO, 15 Bi ₂ O ₃ to 45% by weight, TeO ₂ to 35 to 55% by weight, Li ₂ O to 1 to 10% by weight, Ag ₂ O to 0.5% to 5% by weight, and 0.1% by weight % To 3% by weight of SiO ₂ is mixed, melted and cooled; and a mixing step of mixing the first glass frit and the third glass frit. A solar cell front electrode prepared from the paste composition for a solar cell front electrode according to any one of claims 1 to 11. A solar cell using the solar cell front electrode according to claim 14.