KR20230102993A - Electrode Paste For Solar Cell's Electrode And Solar Cell using the same - Google Patents

Abstract

The present invention relates to a conductive paste for solar cell electrodes. The conductive paste for solar cell electrodes includes metal powder, glass frit, and an organic vehicle. The glass frit includes Ag_2O. The content of Ag_2O is 6 wt% or more and 10 wt% or less based on 100 weight of glass frit. Therefore, it is possible to prevent leakage current and reduce contact resistance.

Description

Conductive paste for solar cell electrode and solar cell manufactured using the same {Electrode Paste For Solar Cell's Electrode And Solar Cell using the same}

The present invention relates to a conductive paste used for forming an electrode of a solar cell and a solar cell manufactured using the same.

A solar cell is a semiconductor device that converts solar energy into electrical energy and generally has a p-n junction form, and its basic structure is the same as that of a diode. A solar cell device is generally constructed using a p-type silicon semiconductor substrate having a thickness of 160 to 250 μm. On the light-receiving surface side of the silicon semiconductor substrate, an n-type impurity layer having a thickness of 0.3 to 0.6 μm, an antireflection film and a front electrode are formed thereon. Further, a back electrode is formed on the back side of the p-type silicon semiconductor substrate.

알루미늄의 융점) 이상의 온도에서 소성함으로써 형성되어 있다. 이 소성 시 알루미늄이 p형 실리콘 반도체 기판의 내부로 확산됨으로써, 배면 전극과 p형 실리콘 반도체 기판 사이에 Al-Si 합금층이 형성됨과 동시에, 알루미늄 원자의 확산에 의한 불순물층으로서 p+층이 형성된다. 이러한 p+층의 존재에 의해 전자의 재결합을 방지하고, 생성 캐리어의 수집 효율을 향상시키는 BSF(Back Surface Field) 효과가 얻어진다. 배면 알루미늄 전극 하부에는 배면 실버 전극이 더 위치될 수 있다.The front electrode forms an electrode by applying a conductive paste containing a mixture of silver powder, glass frit, organic binder, solvent, and additives on the anti-reflection film and then firing it. , The rear electrode is coated with an aluminum paste composition composed of aluminum powder, glass frit, organic binder, solvent and additives by screen printing, etc., and dried, 660

It is formed by firing at a temperature higher than the melting point of aluminum. During this firing, aluminum diffuses into the p-type silicon semiconductor substrate, so that an Al—Si alloy layer is formed between the back electrode and the p-type silicon semiconductor substrate, and a p+ layer is formed as an impurity layer by diffusion of aluminum atoms. . The presence of such a p+ layer results in a Back Surface Field (BSF) effect that prevents recombination of electrons and improves the collection efficiency of generated carriers. A rear silver electrode may be further positioned below the rear aluminum electrode.

On the other hand, the front electrode of the solar cell penetrates the antireflection film while evaporating organic matter during firing, and contacts the inside of the n-type semiconductor substrate to prevent recombination of holes and improve the collection efficiency of generated carriers. The junction depth between the conventional front electrode and the n-type semiconductor substrate is 350 to 500 nm, which has little effect on SCR (space charge region) damage due to penetration of the electrode, but there is a limit to achieving high efficiency.

In addition, recently, a technology has been developed to form a shallow junction depth of 200 nm or less between the front electrode and the n-type semiconductor substrate to achieve high efficiency of the solar cell, but in this case, SCR damage due to electrode penetration during firing of the front electrode increases As a result, there is a limit in that efficiency and fill factor are reduced due to leakage current due to recombination of electrons and holes, or efficiency and fill factor are reduced due to increase in contact resistance of electrodes.

An object of the present invention is to provide a conductive paste and a high-efficiency solar cell with improved contact resistance and prevention of leakage current due to recombination of electrons and holes between a front electrode of a solar cell and an n-type semiconductor substrate.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood by those skilled in the art from the description below.

According to the present invention, a conductive paste for a solar cell electrode includes a metal powder, a glass frit, and an organic vehicle, wherein the glass frit includes Ag ₂ O, and the content of Ag ₂ O is 6 weight relative to 100 weight of the glass frit. It provides a conductive paste for a solar cell electrode, characterized in that % or more and 10% by weight or less.

In addition, the glass frit includes PbO, and the content of PbO is 31 wt% or more and 38 wt% or less with respect to 100 wt% of the glass frit.

In addition, the glass frit includes TeO ₂ , and the amount of TeO ₂ is 24 wt% or more and 34 wt% or less with respect to 100 wt% of the glass frit.

In addition, the glass frit includes Bi ₂ O ₃ , and the amount of Bi ₂ O ₃ is 10 wt % or more and 19 wt % or less with respect to 100 wt % of the glass frit.

In addition, the glass frit contains 31 wt% or more and 38 wt% or less of PbO, 24 wt% or more and 34 wt% or less of TeO _{2 ,} 10 wt% or more and 19 wt% or less of Bi ₂ O ₃ , and 5 wt% of SiO2 based on 100 wt% of the glass frit. % or more and 15 wt% or less, Li2O 0 wt% or more and 5 wt% or less, Na2O 0 wt% or more and 5 wt% or less, ZnO 0 wt% or more and 5 wt% or less, Al2O3 0 wt% or more and 5 wt% or less A conductive paste for solar cell electrodes is provided.

In addition, the glass frit provides a conductive paste for a solar cell electrode, characterized in that it is included in 2% by weight or more and 3% by weight or less based on 100% by weight of the total paste.

The present invention also provides a solar cell having solar cell electrodes manufactured by printing and firing the conductive paste for solar cell electrodes.

In addition, the electrode has a recombination current of Jo1 (pA) in the range of 0.155 to 0.170, a recombination current of Jo2 (nA) in the range of 2.40 to 4.00, a pFF in the range of 0.830 to 0.850, and Rs (series resistance, mΩ). ) is in the range of 1.0 to 1.5, and Voc (V) is in the range of 0.6670 to 0.6695.

The conductive paste according to the present invention can improve contact resistance by forming sufficient silver recrystallization at the wafer interface after firing by controlling the composition of the glass frit, and at the same time, the effect of preventing the problem of recombination of holes and electrons due to excessive penetration of the electrode there is This has the effect of improving the efficiency of the solar cell.

1 shows an image related to a solar cell manufactured using the conductive paste composition of Example 1 of the present invention.
2 shows an image related to a solar cell prepared using the conductive paste composition of Comparative Example 1 of the present invention.
3 shows an image related to a solar cell prepared using the conductive paste composition of Comparative Example 2 of the present invention.

Prior to describing the present invention in detail below, it is understood that the terms used herein are intended to describe specific embodiments and are not intended to limit the scope of the present invention, which is limited only by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art unless otherwise specified.

Throughout this specification and claims, the terms "comprise", "comprise" and "comprising", unless stated otherwise, are meant to include a stated object, step or group of objects, and steps, and any other object However, it is not used in the sense of excluding a step or a group of objects or a group of steps.

On the other hand, various embodiments of the present invention can be combined with any other embodiments unless clearly indicated to the contrary. Any feature indicated as being particularly desirable or advantageous may be combined with any other features and characteristics indicated as being particularly desirable or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

A conductive paste composition for a solar cell electrode according to an embodiment of the present invention includes a conductive metal powder, a glass frit, and an organic vehicle. In addition, additives may be further included. In addition, the conductive paste composition for a solar cell electrode according to an embodiment may additionally include silicone oil.

Each component is described in detail below.

<Conductive metal powder>

Silver powder, copper powder, nickel powder, aluminum powder, etc. may be used as the conductive metal powder. Silver powder is mainly used for the front electrode, and aluminum powder is mainly used for the rear electrode. Hereinafter, for convenience, the conductive metal material will be described by taking silver powder as an example. The following description is equally applicable to other metal powders.

The silver powder is preferably a pure silver powder, and in addition, a silver-coated composite powder having at least a surface made of a silver layer, an alloy containing silver as a main component, or the like can be used. Also, other metal powders may be mixed and used. For example, aluminum, gold, palladium, copper, nickel, etc. are mentioned. The average particle diameter of the silver powder may be 0.1 to 10 μm, and considering the ease of pasting and the compactness during firing, 0.5 to 5 μm is preferable, and the shape is spherical, needle, or plate. (板狀) and amorphous (無定) may be at least one kind. The silver powder may be used by mixing two or more types of powders having different average particle diameters, particle size distributions, shapes, and the like. The content of the silver powder is preferably 60 to 98% by weight based on the total weight of the paste composition for an electrode, considering the thickness of the electrode formed during printing and the line resistance of the electrode.

The conductive metal powder is coated with a coating agent. The coating agent is an alkylamine-based compound having an amine group in an alkyl chain having 8 to 20 carbon atoms or an alkylcarboxyl compound having a carboxyl group in an alkyl chain having 8 to 20 carbon atoms. include Preferably, it is good to include a compound having an amine group or a carboxyl group in an alkyl chain having 15 to 20 carbon atoms. When the carbon number of the alkyl chain is less than 8, there is a problem that the desired effect is not expressed, and when the carbon number exceeds 20, there is a problem in that it is difficult to dissolve in a solvent and the surface treatment is not good. In addition, the coating agent may be used in either a saturated or unsaturated alkyl chain.

The compound having an amine group in the alkyl chain is triethylamine, heptylamine, octadecylamine, hexadecylamine, decylamine, octylamine, didecylamine It may include at least one selected from amine (Didecylamine) and trioctylamine (Trioctylamine).

The compound having a carboxyl group in the alkyl chain includes capric acid, lauric acid, myristic acid, palmitic acid, stearic acid as saturated fatty acids ), arachidic acid, and unsaturated fatty acids may include at least one selected from myristoleic acid, palmitoleic acid, oleic acid, and linoleic acid.

Most preferably, silver powder coated with octadecylamine is used, and the coating agent is preferably coated on the surface of the metal powder to a thickness of 0.1 nm to 50 nm. The coating may be performed by adding metal powder such as silver powder to an organic solvent in which the coating agent is dissolved, stirring for a predetermined time, and then filtering.

As a specific coating method, surface treatment may be performed by adding an alcohol solution containing an alkylamine compound or an alkyl carboxyl compound to a solution in which the conductive metal powder is dispersed and stirring it at 2000 to 5000 rpm for 10 to 30 minutes using a stirrer. An alcohol solution containing an alkylamine compound or an alkyl carboxyl compound may use an alcohol solution in which the compound is dissolved in an amount of 5 to 20% by weight based on the total weight of the solution, and the alcohol is methanol, ethanol, n-propanol, or benzyl alcohol , Terpineol, etc. may be used, and ethanol may be preferably used.

0.1 to 1.0 parts by weight of the coating agent may be used based on 100 parts by weight of the conductive metal powder. When mixed at less than 0.1 part by weight, the amount of coating agent adsorbed on the surface of the conductive metal powder is small, and aggregation occurs between the powders, and the effect of improving the compatibility of silicone oil may be insignificant. When mixed at more than 1.0 part by weight, conductive metal powder There is a problem in that an excessive amount of the surface treatment agent is adsorbed on the surface and the electrical conductivity of the manufactured electrode may be reduced.

By using the conductive metal powder coated with the coating agent, the silicon oil included in the conductive paste can be positioned on the surface of the metal powder, so that phase separation in the vehicle can be completely prevented. That is, it is possible to control the degree of movement of silicone oil to the surface of the conductive metal powder as it is coated with the coating agent. By preventing phase separation due to non-compatibility of silicone oil with organic vehicles (organic solvents and organic binders, etc.), it is possible to secure the storage stability of the provided conductive paste and to secure excellent slip properties to provide the effect of realizing ultra-fine line widths. .

<Glass frit>

When the glass frit according to an embodiment of the present invention is fired, the anti-reflection film around it is completely etched and the n-type semiconductor substrate is partially etched to make electrical contact. In this case, the etching depth of the n-type semiconductor substrate may be adjusted to be smaller than the longitudinal length of the n-type semiconductor substrate according to the composition ratio of the glass frit.

In addition, the glass frit may affect the shape and size of silver recrystallization generated at the wafer interface during firing. Preferably, the silver recrystallization may have an average aspect ratio of 0.005 to 0.50 or 0.01 to 0.25, and may have a flat plate shape. If the aspect ratio is less than the above range, the contact of the silver crystal may be unstable, and if the aspect ratio exceeds the above range, SCR damage may increase, and efficiency and fill factor may decrease due to leakage current due to recombination of electrons and holes. there is.

Conventional silver recrystallization in an inverted pyramid shape with a large aspect ratio penetrates the electrode deeply, increasing damage due to bonding and destroying the SCR region to generate leakage current, thereby reducing the efficiency of the solar cell. . However, in the case of the present invention, since the shape of the silver crystal to be recrystallized is a plate-like shape having the above aspect ratio, it is possible to prevent this problem and improve the power generation efficiency of the solar cell.

In addition, the longitudinal length of the silver recrystallization may be 5 nm to 100 nm, specifically 30 nm to 90 nm. Here, the longitudinal length of the silver recrystallization may mean an average value of all recrystallized silver crystals; In some cases, it may mean a length value in the vertical direction of an arbitrary silver crystal among recrystallized silver crystals. In the latter case, silver recrystallization satisfying the range of 5 nm to 100 nm in length in the longitudinal direction may account for 80% or more of the total silver recrystallization.

When the longitudinal length of the silver recrystallization is less than 5 nm, the etching of the antireflection film is insufficient and the electrode and the emitter layer cannot be contacted, resulting in increased resistance. Since the emitter layer is overetched, electrons and holes recombine, and the power generation efficiency of the solar cell may be reduced.

Meanwhile, the glass frit may include at least one composition selected from PbO, TeO ₂ , Bi ₂ O ₃ , SiO ₂ , Li ₂ O, Na ₂ O, K ₂ O, ZnO, Al ₂ O ₃ , TiO _{2 ,} and the like. can More preferably, as an essential component, Ag ₂ O may be further included. Since Ag ₂ O is essentially included, sufficient silver recrystallization is formed at the wafer interface after firing to improve contact resistance, and at the same time, it is possible to improve solar cell efficiency by preventing hole/electron recombination problems caused by excessive penetration of electrodes. there is.

The content of the Ag ₂ O is preferably 6% by weight or more and 10% by weight or less with respect to 100% by weight of the glass frit in terms of oxide. If it is less than 6% by weight, Rs (series resistance) increases and the efficiency decreases. If it exceeds 10% by weight, the Jo1 recombination current increases, resulting in a decrease in Voc, and the Jo2 recombination current increases considerably, resulting in a decrease in pFF and reduced efficiency. can

The glass frit contains PbO, and the content of PbO is preferably 31 wt% or more and 38 wt% or less with respect to 100 wt% of the glass frit. If the content of PbO is too high, it is not environmentally friendly, and the viscosity during melting is too low, so there is a problem that the line width of the electrode increases during firing.

In addition, the glass frit includes TeO ₂ , and the content of TeO ₂ is preferably 24 wt % or more and 34 wt % or less with respect to 100 wt % of the glass frit. In addition, the glass frit includes Bi ₂ O ₃ , and the content of Bi ₂ O ₃ is preferably 10 wt % or more and 19 wt % or less with respect to 100 wt % of the glass frit.

As an example of a preferred glass frit, 6 wt% or more and 10 wt% or less of Ag ₂ O, 31 wt% or more and 38 wt% or less of PbO, 24 wt% or more and 34 wt% or less of TeO ₂ , based on 100 wt% of the glass frit, Bi ₂ O ₃ 10 wt% or more and 19 wt% or less, SiO2 5 wt% or more and 15 wt% or less, Li2O 0 wt% or more and 5 wt% or less, Na2O 0 wt% or more and 5 wt% or less, ZnO 0 wt% or more and 5 wt% or less, Al2O3 It is preferable to include 0% by weight or more and 5% by weight or less. With the above components and contents, silver recrystallization having an excellent aspect ratio is sufficiently formed at the wafer interface after firing to improve contact resistance, and at the same time, it is possible to prevent a problem of recombination of holes and electrons due to excessive penetration of the electrode.

미만인 것이 바람직하다. 비교적 입경이 큰 입자를 사용하므로 유리전이온도를 낮춤으로써 소성 시 불균일하게 용융되는 등의 문제점을 방지할 수 있다.Meanwhile, the average particle diameter of the glass frit is not limited, but may have a particle diameter in the range of 0.5 to 10 μm, and multiple types of particles having different average particle diameters may be mixed and used. Preferably, at least one glass frit having an average particle diameter (D50) of 2 μm or more and 10 μm or less is preferably used. Through this, reactivity during firing is excellent, damage to the n layer can be minimized, especially at high temperatures, adhesion is improved, and open circuit voltage (Voc) can be improved. In addition, it is possible to reduce an increase in the line width of the electrode during firing. In addition, the glass transition temperature (Tg) of the glass frit having an average particle diameter of 2 μm or more and 10 μm or less is 300

It is preferable to be less than Since particles having a relatively large particle diameter are used, problems such as uneven melting during firing can be prevented by lowering the glass transition temperature.

The content of the glass frit is preferably 1 to 15% by weight based on the total weight of the conductive paste composition. If it is less than 1% by weight, incomplete firing may result in an increase in electrical resistivity, and if it exceeds 15% by weight, the silver powder fired body There is a possibility that the glass component is too large in the inside and the electrical resistivity is also increased.

<Organic vehicle>

The type of organic vehicle used in the present invention is not particularly limited, but may include organic binders and solvents, and in some cases, solvents may be excluded. The organic vehicle is not limited, but is preferably 1 to 10% by weight based on the total weight of the electrode paste composition.

The binder used in the paste composition for an electrode according to an embodiment of the present invention is not limited, but cellulose ester-based compounds include cellulose acetate and cellulose acetate butylate. Examples of cellulose ether-based compounds include ethyl cellulose, methyl cellulose, Hydroxy propyl cellulose, hydroxy ethyl cellulose, hydroxy propyl methyl cellulose, hydroxy ethyl methyl cellulose, etc. are exemplified, and acrylic compounds include poly acrylamide, poly methacrylate, poly methyl methacrylate, poly ethyl Examples include methacrylate and the like, and examples of the vinyl type include polyvinyl butyral, polyvinyl acetate, and polyvinyl alcohol. At least one or more of the binders may be selected and used.

As the solvent used for dilution of the composition, alpha-terpineol, texanol, dioctyl phthalate, dibutyl phthalate, cyclohexane, hexane, toluene, benzyl alcohol, dioxane, diethylene glycol, ethylene glycol monobutyl ether (or butyl cellosolve), ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, and diethylene glycol monobutyl ether acetate, and the like.

<Silicone Oil>

Silicone oil can be included in the conductive paste to maximize slipperiness. The type of silicone oil is not limited, and is selected from the group consisting of phenyl trimethione, dimethicone, cyclomethicone, polydimethylsiloxane and silicone gum One or more may be included, and modified silicone oil may also be used. It may preferably be polysiloxane such as polydimethylsiloxane, and it is preferable to use non-modified polysiloxane oil in consideration of slip properties.

The silicone oil is included in an amount of 0.1 to 2% by weight based on the total weight of the conductive paste composition. When the silicone oil is added in an amount of less than 0.1% by weight, the effect of improving slip properties is insignificant, and when added in an amount exceeding 2% by weight, phase separation may occur even when using coated metal powder and additives. It is preferably included in an amount of 0.5 to 1.5% by weight.

<Additives>

The additives include octyldodecyl neopentanoate, tridecyl neopentanoate, dimethyl adipate, dioctyladipate, isotearyl neopentanoate ( isotearyl neopentanoate) and iodopropynyl butylcarbamate. Preferably, phase separation with organic materials can be prevented very effectively by placing silicone oil, including dimethyl adipate, on the surface of the coated conductive metal powder.

The additive is included in an amount of 0.5 to 3% by weight based on the total weight of the conductive paste composition. When the additive is added in an amount of less than 0.5% by weight, compatibility of the silicone oil is low, resulting in phase separation during manufacture of the conductive paste, and when added in an amount exceeding 3% by weight, there is a problem in composition design. It is preferably included in an amount of 0.5 to 1.5% by weight.

In addition, the conductive paste composition according to the present invention, if necessary, commonly known general additives, for example, dispersants, plasticizers, viscosity modifiers, surfactants, oxidizing agents, rheology modifiers, thixotropic agents, metal oxides, metal organic compounds, etc. may further include.

The above-described conductive paste composition for a solar cell electrode may be prepared by mixing and dispersing metal powder, glass frit, an organic binder, a solvent, and an additive, followed by filtering and defoaming.

The present invention also provides a method of forming an electrode of a solar cell and a solar cell electrode manufactured by the method, characterized in that the conductive paste is applied on a substrate, dried and fired. In the solar cell electrode formation method of the present invention, except for using the conductive paste containing the coated metal powder as described above, substrate, printing, drying, and firing methods commonly used in the manufacture of solar cells may be used. Of course there is.

In addition, the present invention provides a solar cell having solar cell electrodes manufactured by printing and then firing a conductive paste for solar cell electrodes.

As an example, the substrate may be a silicon wafer, the electrode made of the paste of the present invention may be a front finger electrode or a bus bar electrode, and the printing may be screen printing or offset printing, and the drying may be It may be made at 90 ~ 350 ℃, the firing may be made at 600 ~ 950 ℃. Preferably, the firing is preferably performed at a high temperature/high speed firing at 800 to 950° C., more preferably at 850 to 900° C. for 5 seconds to 1 minute, and the printing is preferably performed at a thickness of 20 to 60 μm. . As a specific example, the structure and manufacture of solar cells described in Korean Patent Publication Nos. 10-2006-0108550, 10-2006-0127813, and Japanese Patent Laid-Open Nos. 2001-202822 and 2003-133567 way can be

In addition, the conductive paste according to the present invention has a structure such as a crystalline solar cell (P-type, N-type), PESC (Passivated Emitter Solar cell), PERC (Passivated Emitter and Rear cell), PERL (Passivated Emitter Real Locally Diffused), etc. And it can be applied to both modified printing processes such as double printing and dual printing.

Example and comparative example

After dispersing 100 g of silver powder in 400 mL of pure water, 2.7 g of an octadecylamine ethanol solution (octadecylamine content: 11.25% by weight) was added to the solution in which the silver powder was dispersed, and stirred at 4000 rpm for 20 minutes to remove the silver powder from the surface. After treatment, stirring was stopped and the mixed solution was filtered using a centrifuge. The filter medium was washed with pure water and dried at 70° C. for 12 hours to obtain a first surface-treated silver powder. This silver powder was pulverized in a food blender and pulverized in a Jet-mill.

The surface-treated silver powder was mixed with the composition and content shown in Table 2 below, and then dispersed using a three-bond mill. Thereafter, a conductive paste was prepared by degassing under reduced pressure. Components and contents of the glass frit used in Examples and Comparative Examples are shown in Table 1, and components and contents of the prepared conductive paste are shown in Table 2 below.

Components (% by weight) Example 1 Comparative Example 1 Comparative Example 2 PbO 32 33 30 TeO ₂ 28 29 27 Bi ₂ O ₃ 18 19 17 SiO ₂ 9 9 9 Li ₂ O One One One Na ₂ O One One One ZnO 2 2 2 Al ₂ O ₃ One One One Ag ₂ O 8 5 12 Sum 100 100 100

division Content (parts by weight) silver powder 89.5 glass frit 2.5 Ethyl Cellulose (EC) 0.7 EFKA-4330 0.5 BYK180 0.4 Texanol 2.5 Butyl cellosolve 2.5 Thixatrol Max 0.3 Dimethyl adipate 1.1 Sum 100,0

Experimental example

The conductive paste prepared according to the above Examples and Comparative Examples was pattern-printed on the entire surface of the wafer by a 50 μm mesh screen printing technique, and dried at 200 to 350° C. for 20 to 30 seconds using a belt-type drying furnace. Thereafter, Al paste was printed on the back side of the wafer and dried in the same manner. The cell formed in the above process was fired at a temperature of 500 to 900 ° C for 20 to 30 seconds using a belt-type firing furnace to manufacture a solar cell. A scanning electron microscope (SEM) analysis was performed on the plane of the solar cell manufactured by the above method, and the results are shown in FIGS. 1 to 3 . As shown, the embodiment can improve contact resistance by forming sufficient silver recrystallization at the wafer interface after firing compared to the comparative examples, and at the same time, prevent the problem of recombination of holes and electrons due to excessive penetration of the electrode.

In addition, short-circuit current (Isc), open-circuit voltage (Voc), efficiency (Eff), charge factor (FF), series resistance (Rs) of each solar cell manufactured using the paste prepared according to Examples and Comparative Examples The measurements are shown in Table 3, and the open-circuit voltage (Voc), surface recombination current density (Jo1), junction recombination current density (Jo2), and pFF of the solar cell are measured and shown in Table 4.

division Isc [A] Voc [V] Eff [%] FF [%] Rs [mΩ] Example 1 9.577 0.6682 21.37 81.56 1.3 Comparative Example 1 9.572 0.6687 21.27 81.18 1.8 Comparative Example 2 9.566 0.6652 21.21 81.40 1.1

division Voc Jo1 [pA] Jo2 [nA] pFF Example 1 0.668 0.16 2.5 0.840 Comparative Example 1 0.669 0.15 2.3 0.842 Comparative Example 2 0.665 0.21 6.5 0.828

According to Tables 3 and 4, it can be seen that Example 1 has a high short-circuit current (Isc), a high filling factor (FF), and excellent recombination characteristics, resulting in high efficiency compared to Comparative Examples 1 and 2.

Comparative Example 1 has excellent recombination characteristics, but has a problem in that efficiency decreases due to a decrease in charging factor (FF) due to high Rs (series resistance), and Comparative Example 2 has excellent Rs (series resistance), but surface recombination current It can be seen that the open-circuit voltage (Voc) decreases due to the high density Jo1, and the reduction in pFF is large because the junction recombination current density (Jo2) is too high, resulting in a significant drop in efficiency.

The features, structures, effects, etc. illustrated in each of the above-described embodiments can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

Claims (8)

In the conductive paste for solar cell electrodes,
metal powder, glass frit, organic vehicle;
The conductive paste for solar cell electrodes, wherein the glass frit contains Ag ₂ O, and the content of Ag ₂ O is 6 wt% or more and 10 wt% or less with respect to 100 wt% of the glass frit.
According to claim 1,
The conductive paste for solar cell electrodes, characterized in that the glass frit contains PbO, and the PbO content is 31 wt% or more and 38 wt% or less with respect to 100 wt% of the glass frit.
According to claim 1,
The conductive paste for solar cell electrodes, wherein the glass frit contains TeO ₂ , and the content of TeO ₂ is 24 wt% or more and 34 wt% or less with respect to 100 wt% of the glass frit.
According to claim 1,
The conductive paste for solar cell electrodes, wherein the glass frit contains Bi ₂ O ₃ , and the amount of Bi ₂ O ₃ is 10 wt % or more and 19 wt % or less with respect to 100 wt % of the glass frit.
According to claim 1,
The glass frit contains 31 wt% or more and 38 wt% or less of PbO, 24 wt% or more and 34 wt% or less of TeO _{2 ,} 10 wt% or more and 19 wt% or less of Bi ₂ O ₃ , and 5 wt% or more of SiO2 based on 100 wt% of the glass frit. 15 wt% or less, Li2O 0 wt% or more and 5 wt% or less, Na2O 0 wt% or more and 5 wt% or less, ZnO 0 wt% or more and 5 wt% or less, Al2O3 0 wt% or more and 5 wt% or less Conductive paste for solar cell electrodes.
According to claim 1,
The conductive paste for solar cell electrodes, characterized in that the glass frit is included in 2% by weight or more and 3% by weight or less relative to 100% by weight of the total paste.
A solar cell having a solar cell electrode manufactured by printing and firing the conductive paste for a solar cell electrode according to any one of claims 1 to 6.
According to claim 1,
The electrode has a recombination current of Jo1 (pA) in the range of 0.155 to 0.170, a recombination current of Jo2 (nA) in the range of 2.40 to 4.00, a pFF in the range of 0.830 to 0.850, and Rs (series resistance, mΩ) A solar cell having a range of 1.0 to 1.5 and a Voc(V) of 0.6670 to 0.6695.

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