JP4714633B2 - Conductive paste for solar cell electrode - Google Patents

Description

  The present invention includes a conductive paste for a solar cell electrode, particularly a crystalline silicon solar cell electrode conductive paste such as a single crystal or a polycrystal, a solar cell electrode formed by firing the conductive paste, and the electrode. The present invention relates to a solar cell and a method for manufacturing a solar cell using the conductive paste.

  Conventional solar cells using single crystal or polycrystalline silicon as the main semiconductor substrate material are electrons / holes generated by light incident / absorbed in the semiconductor due to the electric field generated at the PN junction provided near the substrate surface. The pair is separated and taken out to the outside as an electric current through an electrode formed to have a low contact resistance with each of the P-type semiconductor and the N-type semiconductor.

  For example, in the case of a general polycrystalline silicon solar cell, an element capable of forming an N-type diffusion layer such as P (phosphorus atom) from one side surface of a P-type silicon substrate doped with B (boron atom) or the like as an impurity. Diffusion to form a PN junction. In this case, in order to have a light confinement effect, the N-type diffusion layer is formed after texture (unevenness) processing is performed on the surface of the P-type silicon substrate.

  A light incident side electrode composed of a bus electrode and a finger electrode is formed through an antireflection film (film thickness: 50 nm to 100 nm) such as silicon nitride and titanium oxide with the N-type diffusion layer side as a light incident side. Since light does not need to be incident on the P-type silicon substrate side on the back side, the back side electrode is formed on almost the entire surface. Both electrodes need to be in ohmic contact with each semiconductor with low resistance.

  Both electrodes are generally formed by printing, drying and firing a conductive paste. The conductive paste composition and firing conditions are particularly important for the characteristics of the solar cell.

  The conductive paste generally contains an organic binder, a solvent, conductive particles, and glass frit, and an additive is optionally blended. These components include control of printability and shape after printing, imparting conductivity as an electrode, maintaining adhesion with a semiconductor substrate, fire-through of an antireflection film, contact resistance with a semiconductor substrate and a diffusion layer of a solar cell. Play a role of reduction.

  The conductive paste is printed directly on the semiconductor substrate by a method such as screen printing or on the antireflection film formed on the diffusion layer, and dried at a temperature of about 100 to 150 ° C. for several minutes, and then 600 to High-speed baking is performed at about 850 ° C. for several minutes to form a light incident side electrode or a back side electrode. As the firing conditions, optimum conditions for obtaining good solar cell characteristics differ depending on the conductive paste composition, and therefore conditions suitable for the paste composition are selected.

  The influence of the electrode on the conversion efficiency and the stability of the battery characteristics of the crystalline silicon solar cell is large, and particularly the influence of the light incident side electrode is very large. As a measure of electrode performance, there is a solar cell fill factor (FF). When the series resistance of the solar cell is high, the FF tends to be small, and one of the components of the series resistance is the contact resistance between the P-type semiconductor and the N-type semiconductor and the electrode. In addition, the series resistance in a solar cell can be evaluated using the slope of the tangent at the Voc point (open voltage point) in the IV (current-voltage) characteristics under light irradiation of the solar cell as an index.

For this reason, for the purpose of obtaining high conversion efficiency and stable characteristics of solar cells, the following methods have been proposed so far in which various additives are blended into the conductive paste for solar cell electrodes.
(I) A conductive paste containing glass frit containing Bi ₂ O ₃ , B ₂ O ₃ , and SiO ₂ (Patent Document 1).
(Ii) A conductive paste in which a metal such as Ti, Zn, or Y or a compound thereof is added as fine particles of 0.001 to 0.1 μm (Patent Document 2).
(Iii) A conductive paste containing Ti, Bi, Co, Zr, Fe, and Cr (Patent Document 3).
(Iv) A conductive paste to which a halide is added (Patent Document 4).

  However, in any of the conductive pastes, a sufficiently high FF (curve factor) cannot be obtained in a solar cell including an electrode formed using the conductive paste, and the FF of the FF due to fluctuations in the firing temperature for forming the electrode is not obtained. There was a problem that the change was large.

Japanese Patent Laid-Open No. 11-329072 JP-A-2005-243500 JP 2001-313400 A JP 2001-118425 A

  The present invention solves the above-described problems, and in an electrode that is in ohmic contact with a P-type semiconductor and an N-type semiconductor of a crystalline silicon solar cell, a conductive paste for a solar cell electrode that can stably obtain a high FF, And it aims at providing the manufacturing method of the solar cell using the electrode of the solar cell formed by baking the said electrically conductive paste, the solar cell provided with the said electrode, and the said electrically conductive paste.

  As a result of intensive investigations focusing on the homogenization of the electrode composition in the vicinity of the interface with the semiconductor and the reactivity of the additive, the present inventors have made a conductive paste for solar cell electrodes in a temperature range of 150 to 800 ° C. It has been found that blending a substance that changes into a gas is very effective for stably obtaining a high FF, and the present invention has been completed.

  That is, the present invention provides a solar cell electrode conductive material comprising an organic binder, a solvent, conductive particles, glass frit, a metal oxide, and a substance that changes to a gas in a temperature range of 150 to 800 ° C. It is a paste. As will be described later, generally, the conductive paste goes through a temperature range of 150 to 800 ° C. in the firing step.

  In the conductive paste for solar cell electrode of the present invention, the metal oxide is more preferably one or more selected from the group consisting of zinc oxide, titanium oxide and tin oxide. Moreover, it is preferable that the substance which changes into gas in the temperature range of 150-800 degreeC is an organometallic compound, and an organometallic compound is an acetylacetone metal complex, an acetoacetate metal complex, a diethylmalonate metal complex, a cyclopentadiene complex. More preferably, it is at least one selected from the group consisting of naphthenic acid metal compounds, octylic acid metal compounds, stearic acid metal compounds and palmitic acid metal compounds.

  The present invention is also a conductive paste for a solar cell electrode that includes an organic binder, a solvent, conductive particles, and glass frit, and further includes an organic metal compound and a metal oxide. The organometallic compound and the metal oxide are preferably those described above.

  The present invention relates to an electrode for a solar cell obtained by firing the above conductive paste. Furthermore, this invention relates to the solar cell provided with said electrode. In addition, this invention relates to the manufacturing method of the solar cell using said electrically conductive paste.

  According to the conductive paste for solar cell electrode of the present invention, a high FF solar cell can be obtained, and the performance of the solar cell can be improved.

  In the first embodiment of the present invention, the conductive paste for solar cell electrode is made into an organic binder, a solvent, conductive particles, glass frit, metal oxide, and gas in a temperature range of 150 to 800 ° C. And changing substances.

(1) Organic Binder and Solvent The organic binder and the solvent play a role of adjusting the viscosity of the conductive paste and are not particularly limited. It is also possible to use an organic binder dissolved in a solvent.

  Examples of the organic binder include cellulose resins such as ethyl cellulose and nitrocellulose; (meth) acrylic resins such as polymethyl acrylate and polymethyl methacrylate. Organic solvents include alcohols such as terpineol and α-terpineol. , Β-terpineol, etc .; esters such as hydroxy group-containing esters, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, butyl carbitol acetate and the like can be used.

(2) Conductive particles The conductive particles are not particularly limited, and examples thereof include Ag, Cu, and Ni. Ag is preferable because it can be fired in air. The shape and average particle size of the conductive particles are not particularly limited, and those known in the art can be used. Examples of the shape of the conductive particles include a spherical shape and a flake shape. The average particle size of the conductive particles may be 0.05 to 10 μm, preferably 0.1 to 5 μm, from the viewpoint of workability. The average particle size means the average of the particle diameter in the case of a spherical shape, the long diameter of the particle flake in the case of a flake shape, and the length in the case of a needle shape.

(3) Glass frit The glass frit is not particularly limited, and is a Pb glass frit such as PbO—B ₂ O ₃ —SiO ₂ ; Pb free glass frit such as Bi ₂ O ₃ —B ₂ O ₃ —SiO Examples include _2- CeO ₂ —LiO ₂ —NaO ₂ system. The shape and size of the glass frit are not particularly limited, and those known in the art can be used. Examples of the shape of the glass frit include a spherical shape and an indefinite shape. The average dimension is 0.01 to 10 μm, preferably 0.05 to 1 μm, from the viewpoint of workability. The average particle size is as described above, but in the case of an irregular shape, it means the average of the longest diameter.

(4) Metal oxide When the conductive paste of the present invention is used in combination with metal oxide such as zinc oxide, titanium oxide, tin oxide, copper oxide or nickel oxide, particularly zinc oxide, titanium oxide and tin oxide, high FF It is effective in obtaining. Specific examples include ZnO, TiO ₂ and SnO ₂ . In addition, even if it is a metal oxide, the substance which can change into gas in the temperature range of 150-800 degreeC is considered not as a metal oxide but as a substance which changes into gas in the temperature range of 150-800 degreeC. To do.

  The metal oxide is usually solid at room temperature, and the shape and average particle size are not particularly limited. Examples of the shape include a spherical shape and an indefinite shape. The average particle size is preferably 0.05 to 1 μm from the viewpoint of dispersibility.

  The metal oxide prevents excessive sintering of the conductive particles in the firing process, while controlling the spread of the liquefied glass derived from the glass frit and creating a field where the conductive particles come into contact with the semiconductor surface. It is thought to contribute. At this time, when a gas generated by vaporizing or sublimating a substance (for example, an organometallic compound) that changes to a gas in the temperature range of 150 to 800 ° C. described below coexists, the conductive particles form better contact with the semiconductor. I think it can be done.

(5) Substance that changes to gas The conductive paste of the present invention is characterized by containing a substance that changes to gas in a temperature range of 150 to 800 ° C. Such a substance may be a simple substance (consisting of one kind of element) or a compound (consisting of two or more kinds of elements).

  Generally, since the peak of the firing temperature of the conductive paste is set to about 850 ° C. in order to suppress adverse effects on the PN junction, the conductive paste is said to be 150 to 800 ° C. in the firing step. It will go through the temperature range. In the present invention, a high FF solar cell can be obtained by using a conductive paste containing a substance that changes to a gas in this temperature range for the production of a solar cell electrode.

  A substance that can change to a gas in the temperature range of 150 to 800 ° C. is a temperature at which a change to a gas is started by thermogravimetric analysis (a temperature at which weight reduction starts), or a change to a gas is completely completed. The temperature (the temperature at which the weight becomes a substantially constant value) should be in the range of 150 to 800 ° C., and preferably both the temperature at which the change to gas begins and the temperature at which the change to gas completely ends It exists in the range of 150-800 degreeC.

  The upper limit of 800 ° C. is because the peak of the baking temperature of the conductive paste for solar cell electrodes is usually up to about 850 ° C., while the lower limit of 150 ° C. is the swelling of the coating film or the pin This is intended to suppress the generation of holes and the drying process. The temperature range of 150 to 800 ° C at which the gas is changed is more preferably 200 to 600 ° C.

  In the conductive paste for solar cell electrodes of the present invention, a substance that changes into a gas in a temperature range of 150 to 800 ° C., which can be said to be a temperature that passes through the baking process, is blended. It is considered that a high FF solar cell can be obtained as a result of exhibiting the effects of the material blending in a wide range, such as causing a uniform electrode composition near the interface with the semiconductor.

  The substance that changes to a gas in the temperature range of 150 to 800 ° C. can be blended into the conductive paste as a solid, a liquid, or a substance in which the solid is dissolved in a soluble solvent. When blended in a solid form, it is finally changed to a gas, so the influence of the shape and average particle size is small, and is not particularly limited. Examples of the shape include a spherical shape and an indeterminate shape, and examples of the average particle size include 0.01 to 10 μm from the viewpoint of dispersibility, for example, 0.1 to 1 μm.

  In the baking process of the conductive paste, these substances that change to gas become a gas (vaporization) after the solid melts and becomes a liquid as the temperature rises, or directly becomes a gas without passing through the liquid (sublimation). ). When used by being dissolved in a solvent, after the solvent is evaporated, it is changed to a liquid or a solid and then changed to a gas. The generated gas may maintain the molecular structure of the original substance, or may be thermally decomposed and changed into a gas with a molecular weight reduced from the original.

  In the present invention, various inorganic substances and organic substances can be used as the substance that changes to a gas in a temperature range of 150 to 800 ° C. In the case of an organic substance, an organometallic compound is particularly preferably used. In this specification, the organometallic compound refers to an organic compound containing various metals.

  Examples of inorganic substances that vaporize or sublimate in the temperature range of 150 to 800 ° C. include inorganic compounds such as diphosphorus pentoxide, and inorganic simple substances such as red phosphorus and iodine.

  In the case of an organic substance, a material in a wider range than an inorganic substance can be selected. In particular, an organometallic compound is suitable as a substance that can be changed to a gas in a temperature range of 150 to 800 ° C.

For example, an organometallic compound having an acetylacetone group represented by [M (CH ₃ COCHCOCH ₃ ) _n ] (M is a metal) usually starts changing from around 150 ° C. to a gas, and is completely gaseous at about 300 ° C. Suitable for use.

  In general, the vaporization or sublimation temperature in an organometallic compound is determined mainly by an organic group such as an acetylacetone group that binds to the metal rather than the type of the metal, and thus is a relatively low and narrow temperature range. The vaporization or sublimation temperature of the organometallic compound is lower than that of the same metal compound such as oxide, hydroxide, halide, etc., and usually starts to change to gas at 100 to 400 ° C. It is convenient to select the substance to be blended in the conductive paste.

  Examples of organometallic compounds that change into gas in the temperature range of 150 to 800 ° C. include Al, Ga, In, Tl, Zn, Ni, Pd, Pt, Co, Ir, Sn, Pb, Ti, Zr, Hf, Cu, Organometallic compounds of typical metal elements or transition metal elements such as Fe, Ru, Mn, V, Nb, Mo, W, Mn, Mg, Ca, K, Li, Ce, Y, and Sb are commercially available. For example, diketone complexes and carboxylates of these metals can be used. Examples of the diketone complex include acetylacetone metal complex, acetoacetate metal complex, diethylmalonate metal complex, cyclopentadiene complex, and the like. Examples of the carboxylate include a naphthenic acid metal compound, an octylic acid metal compound, a stearic acid metal compound, and a palmitic acid metal compound.

  As the metal element, an organometallic compound containing In, Sn, Y, Ni, Cu, Mg, Pb, Zn, or Ga is more preferable, and an organometallic compound containing In, Sn, Ga, Ni, or Cu is particularly preferable. Among them, acetylacetone metal complexes, octylic acid metal compounds, and naphthenic acid metal compounds containing any of these metal elements are preferable. Specifically, indium acetylacetone compound, yttrium acetylacetone compound, gallium acetylacetone compound, octylic acid Examples thereof include tin, nickel octylate, magnesium octylate, copper naphthenate, lead naphthenate, and zinc naphthenate.

  These organometallic compounds are liquid or solid at room temperature, and can be blended into the conductive paste as they are, but they should be dissolved or dispersed in toluene, ethanol, acetylacetone, methylene chloride, etc. as solvents. You can also.

  FIG. 1 shows the results of thermogravimetric analysis of an indium acetylacetone compound as an example of an organometallic compound. Decomposition and vaporization start from around 150 ° C, vaporization ends at around 300 ° C, and about 5% of indium remains as an oxide. Thus, a substance that starts changing to gas at a temperature above the drying temperature and completes changing to gas before reaching the peak of firing is a substance that changes to gas in the temperature range of 150 to 800 ° C. preferable.

  You may mix | blend arbitrary components, such as a dispersing agent and a plasticizer, with the electrically conductive paste of this invention in the range which does not impair the effect of this invention.

  In the conductive paste of the present invention, the glass frit is 0.5 to 10 parts by weight with respect to 100 parts by weight of the conductive particles from the viewpoint of securing sufficient adhesive strength and suppressing increase in contact resistance. It is preferable that it is 1 to 5 parts by weight. Within this range, good adhesive strength and low contact resistance can be obtained.

  It is preferable that a metal oxide is 0.5-15 weight part with respect to 100 weight part of electroconductive particles, More preferably, it is 2-10 weight part. If it is within this range, the effect of blending can be easily obtained.

  Moreover, it is preferable that the substance which changes to gas in the temperature range of 150-800 degreeC is 0.1-10 weight part with respect to 100 weight part of electroconductive particle, More preferably, it is 0.5-5 weight part. It is. If it is within this range, the effect of blending can be easily obtained.

  The amount of the organic binder and the solvent can be appropriately selected so as to have an appropriate viscosity according to the method for applying and printing the conductive paste.

  The method for producing the conductive paste of the present invention is not particularly limited, and an organic binder, a solvent, conductive particles, glass frit, a metal oxide, a substance that changes to a gas in a temperature range of 150 to 800 ° C., and other optional components Can be prepared by kneading with a planetary mixer or the like and then dispersing with a three roll or the like.

  The electrically conductive paste of this invention can be used for manufacture of the electrode for solar cells, and can obtain favorable contact especially with respect to an N-type semiconductor.

  The production of the solar cell electrode and the production method of the solar cell are not particularly limited. An example will be described with reference to FIG.

  A texture is optionally formed on the surface of the P-type polycrystalline silicon substrate 4, and then P (phosphorus) or the like is thermally diffused at 900 ° C. to form the N-type diffusion layer 3. Next, an antireflection film 2 such as a silicon nitride thin film or titanium oxide is formed to a thickness of 50 to 100 nm by a plasma CVD method or the like. The conductive paste of the present invention is screen-printed on the antireflection film 2 as a light incident side electrode, and the solvent is evaporated at about 150 ° C. and dried. Next, as the back surface side electrode, an aluminum electrode paste is optionally printed on the back surface of the P-type polycrystalline silicon substrate 4 by screen printing and dried. Next, baking is performed to obtain a solar battery cell including the light incident side electrode 1 and the back surface electrode 5.

  At this time, the firing conditions are such that the firing peak temperature is higher than the temperature at which vaporization or sublimation of a substance that changes to a gas in the temperature range of 150 to 800 ° C. blended in the conductive paste of the present invention starts. It is preferable to set, and it is more preferable to set the peak temperature to be 200 ° C. or higher.

  The conductive paste for solar cell electrode according to the second embodiment of the present invention includes an organic binder, a solvent, conductive particles, and glass frit, and further includes an organic metal compound and a metal oxide. This is a conductive paste for electrodes. The organic binder, solvent, conductive particles, and glass frit are the same as in the case of the conductive paste of the first embodiment. By using the organometallic compound and the metal oxide in combination, a solar cell having a high FF can be obtained.

  The effect obtained by using the organometallic compound and the metal oxide in the conductive paste is considered to be the same mechanism as in the first embodiment. Specific examples of the organometallic compound and the metal compound are the same as those in the first embodiment. The compounding amount of the organometallic compound and the metal compound is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the conductive particles. The metal oxide is preferably 0.5 to 15 parts by weight, more preferably 2 to 10 parts by weight.

  Moreover, the manufacturing method of the conductive paste for solar cell electrodes, the solar cell electrode, and the solar cell is the same as that of the first embodiment.

  The solar cell in the examples was manufactured as follows. A texture was formed by wet etching on the surface of a P-type polycrystalline silicon substrate (substrate thickness 200 μm) doped with B (boron). Thereafter, P (phosphorus) was thermally diffused to form an N-type diffusion layer (thickness 0.3 μm). Next, an antireflection film comprising a silicon nitride thin film (thickness: about 60 nm) was formed from silane gas and ammonia gas by plasma CVD. The obtained substrate with antireflection film was cut into 15 mm × 15 mm for use.

  The paste described in each of the following examples was printed on the antireflection film by screen printing with a pattern comprising bus electrodes and finger electrodes so that the film thickness was about 20 μm, and dried at 150 ° C. for about 1 minute. .

  Next, the aluminum electrode paste was printed on the back surface of the P-type polycrystalline silicon substrate 1 by screen printing so that the film thickness was about 20 μm, and dried at 150 ° C. for about 1 minute.

  Then, the board | substrate which printed and dried the paste of both surfaces was baked on the conditions as described in each Example, and the photovoltaic cell provided with the light-incidence side electrode and the back surface electrode was obtained.

The current-voltage characteristics of the solar battery cells were measured under solar simulator light (AM1.5, energy density 100 mW / cm ² ), and FF was calculated from the measurement results.

Example 1
In this example, an indium acetylacetone compound, which is an organometallic compound, is used as a substance that changes to a gas in a temperature range of 150 to 800 ° C. It will be shown in comparison with the case where no additive is added that the addition of a substance that vaporizes to the conductive paste can maintain a high FF in a wide temperature range and that an FF with little variation can be obtained.

  The conductive paste composition (parts by weight) is as shown in Table 1. The conductive paste was prepared by mixing each component with a planetary mixer and three rolls.

  The firing conditions are a peak temperature of 705 ° C., 725 ° C. or 745 ° C., and a firing time of 2 minutes.

  FF about the obtained solar cell is shown in FIG. When the conductive paste of Example 1 was used, high FF was exhibited at any temperature and there was little variation. On the other hand, when the conductive paste of the comparative example was used, the FF decreased as the temperature increased, and the FF variation was large.

Example 2
In this example, an indium acetylacetone compound, which is an organometallic compound, is used as a substance that changes to a gas in a specific temperature range, and the amount of addition is changed.

  The conductive paste composition (parts by weight) is as shown in Table 2. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 2 shows the FF of the obtained solar cell. In Examples 2-1 to 2-3 in which an acetylacetone compound of indium was added, high FF was shown at any addition amount.

Example 3
This is an example in which an indium acetylacetone compound, which is an organometallic compound, is used as a substance that changes into a gas in a specific temperature range, and the amount of ZnO as a metal oxide is changed.

  The conductive paste composition (parts by weight) is as shown in Table 3. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 3 shows the FF of the obtained solar cell. Examples 3-1 to 3-6 to which ZnO was added showed higher FF than the comparative examples to which ZnO was not added. In particular, ZnO blended at 0.5 to 15 parts by weight, particularly 1 to 15 parts by weight, showed high FF.

Example 4
This is an example in which various organometallic compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with conductive paste in which Pb glass frit is blended as glass frit and ZnO is blended as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 4. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes. Table 4 shows the FF of the obtained solar cell. All showed high FF.

Example 5
This is an example in which various organometallic compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with a conductive paste in which Pb-free glass frit is blended as glass frit and ZnO is blended as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 5. The conductive paste was prepared by dispersing each component with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 5 shows the FF of the obtained solar cell. All showed high FF compared with the case where the substance which changes to gas is not added (not shown).

Example 6
This is an example in which various organometallic compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with a conductive paste blended with Pb glass frit as glass frit and TiO ₂ as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 6. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 6 shows the FF of the obtained solar cell. All showed high FF compared with the case where the substance which changes to gas is not added (not shown).

Example 7
This is an example in which various organometallic compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with a conductive paste in which Pb-free glass frit is blended as glass frit and TiO ₂ is blended as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 7. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 7 shows the FF of the obtained solar cell. All showed high FF compared with the case where the substance which changes to gas is not added (not shown).

Example 8
This is an example in which various organometallic compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with a conductive paste in which Pb glass frit is blended as glass frit and SnO ₂ is blended as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 8. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 8 shows the FF of the obtained solar cell. All showed high FF.

Example 9
This is an example in which various organic metal compounds that change into gas upon vaporization or sublimation in a specific temperature range are blended with a conductive paste in which Pb-free glass frit is blended as glass frit and SnO ₂ is blended as metal oxide.

  The conductive paste composition (parts by weight) is as shown in Table 9. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 725 ° C. and a firing time of 2 minutes.

  Table 9 shows the FF of the obtained solar cell. All showed high FF compared with the case where the substance which changes to gas is not added (not shown).

Example 10
This is an example in which red phosphorus is blended into a conductive paste blended with Pb-based glass frit as a glass frit and ZnO as a metal oxide to change into a gas upon vaporization or sublimation in a specific temperature range.

  The conductive paste composition (parts by weight) is as shown in Table 10. The conductive paste was prepared by mixing each component with a planetary mixer and dispersing with three rolls.

  The firing conditions are a peak temperature of 780 ° C. and a firing time of 2 minutes.

  Table 10 shows the FF of the obtained solar cell. High FF was shown.

It is a thermal analysis result of the acetylacetone compound of indium. This is the basic structure of a solar cell. It is a figure showing the peak temperature of baking and FF about the solar cell of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light incident side electrode 2 Antireflection film 3 N type diffused layer 4 P type silicon substrate 5 Back surface electrode

Claims (15)

Seen containing an organic binder, a solvent, conductive particles, glass frit, and metal oxide, and a substance which changes into a gas at a temperature range of 150 to 350 ° C.,
The substance that changes to a gas in the temperature range of 150 to 350 ° C. is selected from the group consisting of an acetylacetone compound of indium, yttrium or gallium and a compound of octylic acid or naphthenic acid and tin, nickel, copper, lead, magnesium or zinc. One or more types of the conductive paste for solar cell electrodes.   The conductive paste for solar cell electrodes according to claim 1, wherein the substance that changes to a gas in a temperature range of 150 to 350 ° C is at least one selected from the group consisting of acetylacetone compounds of indium, yttrium, or gallium. Seen containing an organic binder, a solvent, conductive particles, glass frit, and metal oxide, and a substance which changes into a gas at a temperature range of 200 to 600 ° C.,
The solar cell , wherein the substance that changes to a gas in a temperature range of 200 to 600 ° C. is one or more selected from the group consisting of a compound of octylic acid or naphthenic acid and tin, nickel, copper, lead, magnesium, or zinc. Conductive paste for electrodes. The conductive paste for solar cell electrodes according to any one of claims 1 to 3 , wherein the metal oxide is one or more selected from the group consisting of zinc oxide, titanium oxide, and tin oxide. The glass frit is 0.5 to 10 parts by weight, the gas-changing substance is 0.1 to 10 parts by weight, and the metal oxide is 0.5 to 15 parts by weight with respect to 100 parts by weight of the conductive particles. The electrically conductive paste for solar cell electrodes of any one of Claims 1-4 which is. The electrode of the solar cell formed by baking the electrically conductive paste for solar cell electrodes of any one of Claims 1-5 . A solar cell comprising the electrode according to claim 6 . The manufacturing method of a solar cell which bakes the electrically conductive paste for solar cell electrodes of any one of Claims 1-5 , and forms an electrode. An organic binder, a solvent, conductive particles, and a glass frit, further including an organometallic compound and a metal oxide;
The solar cell, wherein the organometallic compound is at least one selected from the group consisting of an acetylacetone compound of indium, yttrium or gallium and a compound of octylic acid or naphthenic acid and tin, nickel, copper, lead, magnesium or zinc Conductive paste for electrodes.   The organometallic compound is at least one selected from the group consisting of acetylacetone compounds of indium, yttrium or gallium, tin octylate, nickel octylate, magnesium octylate, copper naphthenate, lead naphthenate and zinc naphthenate. The electrically conductive paste for solar cell electrodes of Claim 9. The conductive paste for solar cell electrodes according to claim 9 or 10 , wherein the metal oxide is one or more selected from the group consisting of zinc oxide, titanium oxide, and tin oxide. The glass frit is 0.5 to 10 parts by weight, the organometallic compound is 0.1 to 10 parts by weight, and the metal oxide is 0.5 to 15 parts by weight with respect to 100 parts by weight of the conductive particles. The electrically conductive paste for solar cell electrodes of any one of Claims 9-11 . It claims 9-12 set forth in any one solar cell electrode conductive paste was calcined formed by the solar cell electrode of. A solar cell comprising the electrode according to claim 13 . Electrodes formed by firing claims 9-12 set forth in any one solar cell electrode conductive paste of the method for manufacturing a solar cell.