WO2012111478A1 - Pâte conductrice et photopile - Google Patents

Pâte conductrice et photopile Download PDF

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Publication number
WO2012111478A1
WO2012111478A1 PCT/JP2012/052706 JP2012052706W WO2012111478A1 WO 2012111478 A1 WO2012111478 A1 WO 2012111478A1 JP 2012052706 W JP2012052706 W JP 2012052706W WO 2012111478 A1 WO2012111478 A1 WO 2012111478A1
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Prior art keywords
glass frit
conductive paste
glass
softening point
semiconductor substrate
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PCT/JP2012/052706
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English (en)
Japanese (ja)
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義博 川口
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株式会社 村田製作所
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Publication of WO2012111478A1 publication Critical patent/WO2012111478A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H01L31/0512—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module made of a particular material or composition of materials
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
    • C03C8/18—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions containing free metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a conductive paste and a solar cell, and more particularly to a conductive paste suitable for forming an electrode of a solar cell, and a solar cell manufactured using this conductive paste.
  • a solar cell usually has a light-receiving surface electrode of a predetermined pattern formed on one main surface of a semiconductor substrate. Further, an antireflection film is formed on the semiconductor substrate excluding the light receiving surface electrode, and the reflection loss of incident sunlight is suppressed by the antireflection film, thereby converting the conversion efficiency of sunlight into electric energy. Has improved.
  • the light receiving surface electrode is usually formed as follows using a conductive paste. That is, the conductive paste contains conductive powder, glass frit, and organic vehicle, and the conductive paste is applied to the surface of the antireflection film formed on the semiconductor substrate to form a conductive film having a predetermined pattern. To do. Then, the glass frit is melted in the firing process, and the antireflection film under the conductive film is decomposed and removed, whereby the conductive film is sintered to form the light receiving surface electrode, and the light receiving surface electrode and the semiconductor substrate are bonded together. They are bonded to make them both conductive.
  • This method of disassembling and removing the antireflection film in the firing process and bonding the semiconductor substrate and the light-receiving surface electrode is called fire-through, and the conversion efficiency of the solar cell is greatly increased in fire-through performance.
  • Dependent That is, it is known that if the fire-through property is insufficient, the conversion efficiency is lowered and the basic performance as a solar cell is inferior.
  • a glass frit having a low softening point in order to increase the adhesive strength between the light receiving surface electrode and the semiconductor substrate.
  • lead-based glass frit has been used as a glass frit with a low softening point.
  • lead (Pb) has a large environmental load, the appearance of a new material to replace lead-based glass frit is required. ing.
  • Patent Document 1 discloses that the glass frit has a softening point of 570 to 760 ° C., and the glass frit has a molar ratio of B 2 O 3 / SiO 2 of 0.3 or less.
  • a conductive paste containing B 2 O 3 and SiO 2 and containing less than 20 mol% Bi 2 O 3 has been proposed.
  • Patent Document 1 although it is a lead-free conductive paste that does not contain lead, the adhesive strength between the light-receiving surface electrode and the semiconductor substrate is large even when baked at a relatively low temperature, and between the light-receiving surface electrode and the semiconductor substrate. It is possible to obtain a solar cell having a low contact resistance.
  • a conductive paste is applied to an antireflection film on a semiconductor substrate, and this is fired as an object to be fired.
  • the present invention has been made in view of such circumstances, and it is a lead-free electrode for forming an electrode for a solar cell that can stably obtain high conversion efficiency even when fired in a wide temperature range. It aims at providing the electrically conductive paste and the solar cell manufactured using this electrically conductive paste.
  • the present inventor conducted intensive studies to achieve the above object, and as a result, the molar ratio of B 2 O 3 to SiO 2 was adjusted to 0.4 or less, and the two types of non-softening points differing by 20 ° C. or more.
  • the blending ratio of both glass frit is in the range of 1/4 to 4/1, good fire-through property can be secured even if the temperature fluctuates during firing. It was possible to obtain a solar cell having a desired high conversion efficiency in a wide range of firing temperatures.
  • the electrically conductive paste which concerns on this invention is an electrically conductive paste for forming the electrode of a solar cell, Comprising: Conductive powder and 1st glass Containing a frit, a second glass frit having a softening point higher by 20 ° C. or more than the first glass frit, and an organic vehicle, wherein the first and second glass frits do not contain Pb, At least B and Si are contained, and the molar ratio of B to Si is 0.4 or less in terms of SiO 2 and B 2 O 3 , respectively, and the first glass frit and the second glass frit
  • the content ratio of is characterized by being 1/4 to 4/1 in weight ratio.
  • adhesion is secured by the first glass frit having a relatively low softening point, while the light receiving surface electrode and the semiconductor are secured by the second glass frit having a softening point of 20 ° C. or more higher than that of the first glass frit. Excessive glass flow to and from the substrate can be suppressed, thereby ensuring a good fire-through property even when fired in a wide temperature range, and stably obtaining a solar cell having high conversion efficiency Is possible.
  • the softening point of the first glass frit is 510 to 570 ° C.
  • the softening point of the second glass frit is preferably 530 to 680 ° C.
  • the first glass frit is such that Bi 2 O 3 is 20 to 40 mol%, BaO is 5 to 20 mol%, and Al 2 O 3 is 5 mol% or less. Each is preferably contained.
  • the second glass frit has a Bi 2 O 3 content of 5 to 30 mol%, a BaO content of 5 to 25 mol%, and an Al 2 O 3 content of 5 mol% or less. It is preferably contained.
  • the first and second glass frit contain at least one of Bi and Ba.
  • the conductive paste of the present invention preferably contains ZnO.
  • the fire-through property can be further promoted, and a solar cell having a low contact resistance between the electrode and the semiconductor substrate can be realized.
  • the conductive powder is preferably Ag powder.
  • an antireflection film and a light receiving surface electrode penetrating the antireflection film are formed on one main surface of the semiconductor substrate, and the electrode is the conductive paste according to any one of the above Is characterized by being sintered.
  • the conductive powder such as Ag powder
  • the molar ratio of B to Si is 0.4 or less in terms of SiO 2 and B 2 O 3 , respectively, and the content ratio of the first glass frit and the second glass frit is expressed as a weight ratio.
  • the first glass frit having a relatively low softening point ensures adhesion, while the second glass frit having a softening point higher than the first glass frit by 20 ° C. or more.
  • an antireflection film and an electrode penetrating the antireflection film are formed on one main surface of the semiconductor substrate, and the electrode is formed of the conductive paste according to any one of the above. Since it is sintered, a solar cell having high conversion efficiency can be obtained stably even when fired in a wide temperature range.
  • FIG. 1 is a cross-sectional view of an essential part showing an embodiment of a solar cell manufactured using a conductive paste according to the present invention.
  • an antireflection film 2 and a light receiving surface electrode 3 are formed on one main surface of a semiconductor substrate 1 containing Si as a main component, and a back electrode 4 is formed on the other main surface of the semiconductor substrate 1.
  • the semiconductor substrate 1 has a p-type semiconductor layer 1b and an n-type semiconductor layer 1a, and an n-type semiconductor layer 1a is formed on the upper surface of the p-type semiconductor layer 1b.
  • the semiconductor substrate 1 can be obtained, for example, by diffusing impurities on one main surface of a single-crystal or polycrystalline p-type semiconductor layer 1b to form a thin n-type semiconductor layer 1a.
  • the n-type semiconductor layer 1a is formed on the upper surface of the layer 1b, its structure and manufacturing method are not particularly limited.
  • the semiconductor substrate 1 has a structure in which a thin p-type semiconductor layer 1b is formed on one main surface of the n-type semiconductor layer 1a, or a p-type semiconductor layer 1b on a part of one main surface of the semiconductor substrate 1.
  • a structure in which both the n-type semiconductor layer 1a and the n-type semiconductor layer 1a are formed may be used.
  • the conductive paste according to the present invention can be used effectively as long as it is the main surface of the semiconductor substrate 1 on which the antireflection film 2 is formed.
  • the surface of the semiconductor substrate 1 is shown in a flat shape, but the surface is formed to have a fine concavo-convex structure in order to effectively confine sunlight to the semiconductor substrate 1.
  • the antireflection film 2 is formed of an insulating material such as silicon nitride (SiN x ), suppresses reflection of light to the light receiving surface of sunlight indicated by an arrow A, and allows sunlight to be quickly and efficiently applied to the semiconductor substrate 1. Lead.
  • the material constituting the antireflection film 2 is not limited to the above silicon nitride, and other insulating materials such as silicon oxide and titanium oxide may be used, and two or more kinds of insulating materials may be used. May be used in combination. In addition, as long as it is crystalline Si, either single crystal Si or polycrystalline Si may be used.
  • the light receiving surface electrode 3 is formed on the semiconductor substrate 1 through the antireflection film 2.
  • the light-receiving surface electrode 3 is formed by applying a conductive paste of the present invention, which will be described later, onto the semiconductor substrate 1 by using screen printing or the like to produce a conductive film and baking it. That is, in the baking process for forming the light receiving surface electrode 3, the antireflection film 2 under the conductive film is decomposed and removed and fired through, whereby the light receiving surface electrode is formed on the semiconductor substrate 1 so as to penetrate the antireflection film 2. 3 is formed.
  • the light-receiving surface electrode 3 has a large number of finger electrodes 5a, 5b,... 5n arranged in a comb-like shape and intersects with the finger electrodes 5a, 5b,.
  • Bus bar electrode 6 is provided, and finger electrodes 5a, 5b,... 5n and bus bar electrode 6 are electrically connected.
  • the antireflection film 2 is formed in the remaining region excluding the portion where the light receiving surface electrode 3 is provided. In this way, the electric power generated in the semiconductor substrate 1 is collected by the finger electrodes 5n and taken out to the outside by the bus bar electrodes 6.
  • the back electrode 4 is formed on the back surface of the current collecting electrode 7 and the current collecting electrode 7 made of Al or the like formed on the back surface of the p-type semiconductor layer 1b. It is comprised with the extraction electrode 8 which consists of Ag etc. which were electrically connected with the current collection electrode 7. FIG. Then, the electric power generated in the semiconductor substrate 1 is collected by the collecting electrode 7 and is taken out by the extracting electrode 8.
  • the conductive paste of the present invention contains conductive powder, two types of lead-free glass frit (first and second glass frit) having different softening points, and an organic vehicle.
  • the first and second glass frit both contain at least B and Si, and satisfy the following formulas (1) to (3).
  • Ts 1 is the softening point of the first glass frit
  • Ts 2 is the softening point of the second glass frit
  • ⁇ is the molar content of B 2 O 3 in each glass frit
  • ⁇ is in each glass frit.
  • x is the content weight of the first glass frit
  • y is the content weight of the second glass frit.
  • the conductive paste of the present invention contains at least two lead-free glass frit containing B and Si and having different softening points, and the softening point Ts 2 of the second glass frit is the same as that of the first glass frit. 20 ° C. or more higher than the softening point Ts 1, the molar ratio ⁇ / ⁇ of B 2 O 3 to SiO 2 is 0.4 or less, and the weight ratio x / of the first glass frit to the second glass frit y is set to 1/4 to 4/1.
  • Softening points Ts 1 and Ts 2 of the first and second glass frit Si-B-Bi-Ba glass frit containing SiO 2 , B 2 O 3 , Bi 2 O 3 , and BaO is a promising substitute for lead glass frit because it has good fire-through properties. is there.
  • the glass frit having a low softening point easily flows at the interface between the light-receiving surface electrode 3 and the semiconductor substrate 1 (n-type semiconductor layer 1a) during the baking process, and is reflected. Since the decomposition / removal of the prevention film is promoted, it can contribute to the improvement of the fire-through property. It is also possible to improve the adhesive strength between the light receiving surface electrode 3 and the semiconductor substrate 1.
  • the lead-free glass frit having a low softening point flows excessively at the interface between the conductive film to be the light-receiving surface electrode 3 and the semiconductor substrate 1 and diffuses toward the semiconductor substrate 1 to cause the semiconductor substrate 1 to flow. There is a risk of erosion. As a result, the pn junction formed between the n-type semiconductor layer 1a and the p-type semiconductor layer 1b may be destroyed, and a desired high conversion efficiency may not be obtained. In this case, if the conductive powder is excessively diffused to the semiconductor substrate 1 side through the glass frit, the parallel resistance is lowered, and as a result, the voltage when the output terminal is opened, that is, the open circuit voltage Voc is lowered. High conversion efficiency cannot be obtained.
  • the first glass frit having a low softening point and the second glass frit having a softening point higher by 20 ° C. or more than the first glass frit are contained in the conductive paste, thereby Excessive flow of glass frit at the interface between the light receiving surface electrode 3 and the semiconductor substrate 1 is suppressed.
  • the glass component is appropriately flowed by the first glass frit, the adhesion at the interface is ensured, the decomposition and removal of the antireflection film is promoted, and the fire-through property is secured, while the second glass frit is secured.
  • the softening point of the second glass frit Ts 2 and the difference between the softening point Ts 1 of the first glass frit be at least 20 ° C. above, when both the softening point difference ⁇ Ts is reduced to below 20 ° C., This is because it is not much different from the case where one type of glass frit is contained in the conductive paste, and high conversion efficiency cannot be obtained stably.
  • the softening points Ts 1 and Ts 2 of the first and second glass frits are not particularly limited as long as the difference between the softening points ⁇ Ts between the commonly used glass frits can be 20 ° C. or more.
  • the first glass frit is preferably 510 to 570 ° C.
  • the second glass frit is preferably 530 to 680 ° C.
  • B 2 O 3 molar ratio to SiO 2 ⁇ / ⁇ Glass is composed of a network oxide that becomes amorphous to form a network network structure, a modified oxide that modifies the network oxide to make it amorphous, and an intermediate oxide between the two. Composed. Of these, SiO 2 and B 2 O 3 both act as network oxides and are important constituents.
  • the conductive powder is dissolved in the glass frit during firing of the conductive film, and the dissolved conductive powder is reduced on the semiconductor substrate 1 and deposited as metal particles. This facilitates the formation of electrical contact between the conductive powder and the semiconductor substrate 1.
  • the molar ratio ⁇ / ⁇ of B 2 O 3 with respect to SiO 2 is set to 0.4 or less.
  • the weight ratio x / y between the first glass frit and the second glass frit is less than 1/4, the second glass frit is excessively contained, while the weight ratio x / y is 4/1. If it exceeds, the first glass frit is excessively contained.
  • the weight ratio x / y between the first glass frit and the second glass frit is set to 1/4 to 4/1.
  • the total content of the glass frit is not particularly limited, but is preferably 1 to 6 parts by weight with respect to 100 parts by weight of the conductive powder.
  • the first glass frit having a relatively low softening point has the adhesiveness.
  • excessive glass flow between the light-receiving surface electrode and the semiconductor substrate can be suppressed by the second glass frit having a softening point 20 ° C. higher than that of the first glass frit. While preventing destruction, it is possible to prevent the open circuit voltage Voc from decreasing by suppressing the decrease in parallel resistance. As a result, while being a lead-free conductive paste, a solar cell having high conversion efficiency stably even when fired in a wide temperature range without impairing fire-through properties, electrical contact properties, adhesive strength, etc. Can be obtained.
  • the components of the first and second glass frit are not particularly limited as long as they contain Si and B. From the viewpoint of obtaining good battery characteristics, the above-described Si—B—Bi is used. -Ba type is preferred.
  • the composition of each glass component is such that the first glass frit contains 20 to 40 mol% Bi 2 O 3 , 5 to 20 mol% BaO, and 5 mol% or less Al 2 O 3.
  • the second glass frit preferably contains 5 to 30 mol% Bi 2 O 3 , 5 to 25 mol% BaO, and 5 mol% or less Al 2 O 3. .
  • Bi 2 O 3 has an effect of adjusting the fluidity of glass as a modified oxide, and further promotes fire-through properties, and therefore plays an important role in a conductive paste for solar cells.
  • the content molar amount of Bi 2 O 3 is 20 to 40 mol%, and in the case of the second glass frit requiring a higher softening point than the first glass frit, The amount is preferably 5 to 30 mol%.
  • BaO like Bi 2 O 3 , also has the effect of adjusting the fluidity of glass as a modified oxide, and contributes to the promotion of fire-through properties. Accordingly, the molar amount of BaO is determined in relation to the molar amount of Bi 2 O 3 having the same action.
  • the content of the second glass frit is 5 to 20 mol%. In this case, 5 to 25 mol% is preferable.
  • Alkaline earth metal oxides other than BaO such as MgO, SrO, and CaO, can be used because they have the effect of adjusting the fluidity of the glass as a modified oxide, as well as BaO, but are good. From the viewpoint of obtaining fire-through properties, it is preferable to use BaO.
  • Al 2 O 3 acts as an intermediate oxide, and by containing an appropriate amount, Al 2 O 3 can suppress crystallization of glass, obtain a stable amorphous glass, and improve the chemical durability of the glass frit. Can do.
  • the content molar amount of Al 2 O 3 exceeds 5 mol%, it becomes easier to crystallize. Therefore, when Al 2 O 3 is included, it is 5 mol% or less, preferably 0.1%. ⁇ 5 mol%.
  • the conductive powder is not particularly limited as long as it is a metal powder having good conductivity, but it maintains good conductivity without being oxidized even when the baking treatment is performed in the air. Ag powder that can be used is preferred.
  • the shape of the conductive powder is not particularly limited, and may be, for example, a spherical shape, a flat shape, an irregular shape, or a mixed powder thereof.
  • the average particle diameter of the conductive powder is not particularly limited, but from the viewpoint of securing a desired contact point between the conductive powder and the semiconductor substrate 1, in terms of spherical powder, 1. 0 to 5.0 ⁇ m is preferable.
  • ZnO promotes the decomposition and removal of the antireflection film 2 during the firing of the conductive paste to enable smooth fire-through, and lowers the contact resistance between the light receiving surface electrode 3 and the semiconductor substrate 1.
  • the organic vehicle is prepared such that the binder resin and the organic solvent are in a volume ratio of 1 to 3: 7 to 9, for example.
  • the binder resin is not particularly limited, and for example, ethyl cellulose resin, nitrocellulose resin, acrylic resin, alkyd resin, or a combination thereof can be used.
  • the organic solvent is not particularly limited, and ⁇ -terpineol, xylene, toluene, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, etc. alone or in combination thereof Can be used.
  • plasticizers such as di-2-ethylhexyl phthalate and dibutyl phthalate
  • a rheology modifier such as a fatty acid amide or a fatty acid, and a thixotropic agent, a thickener, a dispersant, etc. may be added.
  • the conductive paste is prepared by weighing and mixing the conductive powder, the first and second glass frit, the organic vehicle, and various additives as necessary at a predetermined mixing ratio, and so on. It can be easily manufactured by dispersing and kneading using the above.
  • the conductive powder such as Ag powder, the first and second glass frits, and the organic vehicle are contained, and the glass frit satisfies the above formulas (1) to (3). Therefore, the first glass frit having a relatively low softening point ensures adhesion, while the second glass frit having a softening point 20 ° C. higher than that of the first glass frit allows the light-receiving surface electrode and the semiconductor substrate to adhere to each other. In this way, it is possible to suppress excessive glass flow between them, and even when fired in a wide temperature range, it is possible to obtain a solar cell having stable and high conversion efficiency while ensuring good fireability. Become.
  • the first glass frit contains Bi 2 O 3 in an amount of 20 to 40 mol%, BaO in an amount of 5 to 20 mol%, and Al 2 O 3 in an amount of 5 mol% or less. Glass frit contains 5 to 30 mol% of Bi 2 O 3 , 5 to 25 mol% of BaO, and 5 mol% or less of Al 2 O 3 . Can be obtained.
  • the inclusion of ZnO can promote the fire-through property, and a solar cell with low contact resistance between the electrode and the semiconductor substrate can be realized.
  • the said solar cell will have high conversion efficiency stably even if it burns in a wide temperature range.
  • the present invention is not limited to the above embodiment.
  • the case where both Bi 2 O 3 and BaO are included is exemplified as a preferred form of the glass frit.
  • both are modified oxides and promote fire-through properties, only one of them is included. It is good also as a component composition containing this.
  • the glass frit it is also preferable to contain various oxides in the glass frit as required.
  • TiO 2 and ZrO 2 can be drastically improved in chemical durability of glass only by being contained in a small amount in a glass frit.
  • the content in the glass frit is preferably 5 mol% or less.
  • alkali metal oxide is contained in a large amount in the glass frit, the chemical durability of the glass frit may be lowered. Therefore, the content of the alkali metal oxide in the glass frit is 10 mol% or less. It is preferable to do this.
  • Example preparation (Production of glass frit) SiO 2 , B 2 O 3 , Bi 2 O 3 , BaO, and Al 2 O 3 were blended so as to have a blending ratio as shown in Table 1 in mol% to prepare glass frits A to L. Then, thermal analysis was performed using TG-DTA (thermogravimetric-differential thermal analyzer), and the softening points of the glass frits A to L were measured. That is, 5 mg of a sample is accommodated in an alumina container, ⁇ alumina is used as a standard sample, and the measuring apparatus is heated at 20 ° C. per minute while supplying air into the measuring apparatus at a flow rate of 100 mL / min. It heated with the profile and the TG curve and the DTA curve were created from the weight change with respect to temperature. And the softening point in each sample was measured from such TG curve and DTA curve.
  • TG-DTA thermogravimetric-differential thermal analyzer
  • the glass frit A to J has a B 2 O 3 / SiO 2 of 0.4 or less, indicating a glass frit composition within the scope of the present invention.
  • Example 1 a conductive paste was prepared using these glass frits A to L, and further, a solar battery cell was prepared using this conductive paste, and the characteristics were evaluated.
  • conductive paste As the conductive powder, spherical Ag powder having an average particle diameter of 1.6 ⁇ m and ZnO having a specific surface area of 10 m 2 / g were prepared.
  • the organic cellulose was prepared by mixing the ethyl cellulose resin and texanol so that the binder resin was 10% by weight of ethyl cellulose resin and the organic solvent was 90% by weight of texanol.
  • the glass frit contained in the conductive paste was blended so that the total amount was 2% by weight, as shown in Table 2, by appropriately selecting and combining glass frits A to J.
  • An antireflection film having a thickness of 0.1 ⁇ m was formed by plasma enhanced chemical vapor deposition (PECVD) over the entire surface of a single crystal Si-based semiconductor substrate having a length of 50 mm, a width of 50 mm, and a thickness of 0.2 mm.
  • PECVD plasma enhanced chemical vapor deposition
  • P is diffused into a part of the p-type Si-based semiconductor layer, whereby an n-type Si-based semiconductor layer is formed on the upper surface of the p-type Si-based semiconductor layer.
  • an Al paste mainly composed of Al and an Ag paste mainly composed of Ag were prepared. Then, an Al paste and an Ag paste were appropriately applied to the back surface of the Si-based semiconductor substrate and dried to form a back electrode conductive film.
  • each sample was placed in an oven set at a temperature of 150 ° C. to dry the conductive film.
  • a belt-type near infrared furnace (CDF7210, manufactured by Despatch) was used, and the conveyance speed was adjusted so that the sample passed between the inlet and the outlet in about 1 minute, and the maximum firing temperature of 760 to 800 in the air atmosphere.
  • the solar cells of Sample Nos. 1 to 16 were prepared by firing at 0 ° C. and sintering the conductive paste to form the light-receiving surface electrode. The reason why the maximum firing temperature is set to 760 to 800 ° C. is that the optimum maximum firing temperature varies depending on the paste composition.
  • Pmax is the maximum output of the sample
  • Voc is the open circuit voltage
  • Isc is the short circuit current
  • the conversion efficiency ⁇ was obtained from the maximum output Pmax, the area A of the light receiving surface electrode, and the irradiance E based on the formula (5).
  • Table 2 shows the paste composition, the glass frit softening point difference ⁇ Ts, the fill factor FF, and the conversion efficiency ⁇ of each sample Nos. 1 to 16.
  • Sample No. 13 was found to contain only glass frit C having a softening point Ts of 542 ° C. in the conductive paste, and the conversion efficiency ⁇ was as low as 16.06%.
  • Sample No. 14 contains glass frits C and D in the conductive paste, but the softening point difference ⁇ Ts is as small as 5 ° C. (glass frit C: 542 ° C., glass frit D: 547 ° C.).
  • the conversion efficiency ⁇ was slightly improved as compared with Sample No. 12 containing only the kind, but the conversion efficiency ⁇ was still low at 16.15%, and a sufficient conversion efficiency ⁇ could not be obtained.
  • Sample No. 15 has a softening point difference ⁇ Ts of 22 ° C. and a difference of 20 ° C. or more, but includes glass frit K outside the scope of the present invention in which B 2 O 3 / SiO 2 is 3.83, The conversion efficiency was greatly reduced to 13.56%. This is because glass frit K containing a large amount of B 2 O 3 / SiO 2 is contained, so that a large molten glass stays at the interface between the light-receiving surface electrode and the semiconductor substrate, resulting in a high contact resistance, resulting in conversion. The efficiency ⁇ seems to have decreased.
  • Sample No. 16 has a softening point difference ⁇ Ts of 51 ° C. and a difference of 20 ° C. or more, but includes glass frit L outside the scope of the present invention in which B 2 O 3 / SiO 2 is 2.49. For the same reason as Sample No. 15, the conversion efficiency ⁇ decreased to 13.80%.
  • Sample Nos. 1 to 12 use a combination of two types of glass frit having a softening point difference ⁇ Ts of 20 ° C. or more, and B 2 O 3 / SiO 2 is also 0.10 to 0.39. And the blending ratio of each glass frit is also 1/1, so that the conversion efficiency ⁇ is 16.36 to 16.75% and has a high conversion efficiency ⁇ of 16.35% or more. It was found that a battery was obtained.
  • Sample No. 12 has a softening point of the first glass frit of 597 ° C., which is a high temperature exceeding 570 ° C., but when the maximum firing temperature is optimally adjusted, a desired high conversion efficiency ⁇ is obtained. It was.
  • Example 2 Using the glass frits E, F and H produced in Example 1, the conductive pastes of sample numbers 21 to 24 were prepared by the same method and procedure as in Example 1 so that the paste composition shown in Table 3 was obtained. Produced.
  • solar cells of sample numbers 21 to 24 were produced in the same manner and procedure as in Example 1 except that the maximum firing temperature was set to 4 different temperatures between 780 and 820 ° C., respectively, and firing was performed.
  • Table 3 shows the paste composition, firing temperature (baking maximum temperature), fill factor FF, conversion efficiency ⁇ , and determination result for each sample Nos. 21 to 24.
  • the determination result made the sample whose conversion efficiency (eta) 16.35% or more (circle) (pass) and the sample whose conversion efficiency is less than 16.35% made x (fail).
  • Sample No. 23 contains only glass frit E having a softening point Ts of 567 ° C. in the conductive paste, so the conversion efficiency ⁇ is low at 13.90 to 15.89%, and the conversion efficiency depends on the firing temperature. It was found that ⁇ varies.
  • Sample No. 21 uses glass frits E and H having a softening point difference ⁇ Ts of 73 ° C., B 2 O 3 / SiO 2 are both 0.4 or less, and the blending ratio of the two types of glass frits Therefore, it was found that a solar cell having a high conversion efficiency ⁇ of 16.47 to 16.66% over a wide temperature range of 780 to 810 ° C. was obtained.
  • Sample No. 22 uses glass frits F and H having a softening point difference ⁇ Ts of 43 ° C., B 2 O 3 / SiO 2 are both 0.4 or less, and the mixing ratio of the two types of glass frits is Although the softening point of the first glass frit was 597 ° C. and exceeded 570 ° C., the conversion efficiency ⁇ was reduced to 13.90% when the firing temperature was lowered to 780 ° C. That is, when the softening point of the first glass frit is excessively high, the firing temperature region for obtaining high conversion efficiency is wider than that of sample numbers 23 and 24, but is slightly narrower than that of sample number 21. I understood.
  • Example 1 Using the glass frits A and J produced in Example 1, the conductive paste and solar cells of sample numbers 31 to 39 were prepared by the same method and procedure as in Example 1 so that the paste composition shown in Table 4 was obtained. A cell was produced.
  • Table 4 shows the paste composition, the weight ratio x / y (hereinafter referred to as “A / J”) of the glass frit A and the glass frit J, the fill factor FF, and the conversion efficiency ⁇ in each of the samples 31 to 39. Is shown.
  • Sample No. 38 had a large A / J of 9.00 and an excessive content of glass frit A having a low softening point, so the conversion efficiency ⁇ was reduced to 15.85%. This is because glass frit A having a low softening point is excessively contained, so that an excessive flow of the glass component occurs at the interface between the conductive film to be the light-receiving surface electrode and the semiconductor substrate during firing, and the glass component becomes a semiconductor substrate. In addition, Ag is excessively diffused into the semiconductor substrate through the molten glass, leading to a reduction in parallel resistance and a reduction in the open-circuit voltage Voc. As a result, a high conversion efficiency ⁇ cannot be obtained. This is probably because of this.
  • Sample Nos. 31 to 37 have an A / J of 0.25 to 4.0 (1/4 to 4/1), which is within the range of the present invention. % High solar cell was obtained.

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Abstract

L'invention concerne une pâte conductrice qui contient une poudre d'Ag, une première fritte de verre, une seconde frite de verre qui a un point de ramollissement plus élevé que celui de la première fritte de verre de 20 °C ou plus, et un véhicule organique. Les première et seconde frittes de verre sont dépourvues de plomb et contiennent au moins du B et du Si, le rapport molaire entre B2O3 et SiO2 étant de 0,4 ou moins. La première fritte de verre et la seconde fritte de verre sont contenues dans la pâte conductrice dans un rapport pondéral allant de 1/4 à 4/1. Une électrode de surface réceptrice de lumière (3) est formée à l'aide de la pâte conductrice. En conséquence, on peut obtenir : une pâte conductrice permettant de former une électrode pour des photopiles, qui est dépourvue de plomb mais qui permet d'atteindre de façon stable un haut rendement de conversion même si elle est mise à feu sur une large plage de températures ; et une photopile qui est fabriquée à l'aide de la pâte conductrice.
PCT/JP2012/052706 2011-02-18 2012-02-07 Pâte conductrice et photopile WO2012111478A1 (fr)

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
JP2013175547A (ja) * 2012-02-24 2013-09-05 Namics Corp 太陽電池の電極形成用導電性ペースト
CN103854718A (zh) * 2012-12-03 2014-06-11 西北稀有金属材料研究院 一种太阳能电池正面电极浆料及其制备方法
EP2754185A4 (fr) * 2011-09-09 2015-06-03 Heraeus Precious Metals North America Conshohocken Llc Contacts de cellule solaire à pastille d'argent
JP2015122177A (ja) * 2013-12-21 2015-07-02 株式会社ノリタケカンパニーリミテド 太陽電池用導電性ペースト組成物およびその製造方法

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CN109903886A (zh) * 2019-01-17 2019-06-18 浙江光达电子科技有限公司 一种应用于无网结网版的正面细栅浆料

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JPH0428110A (ja) * 1990-05-23 1992-01-30 Kyocera Corp 積層型コンデンサの端子電極形成用導電性ペースト及び積層型コンデンサ
JPH04206401A (ja) * 1990-11-30 1992-07-28 Matsushita Electric Ind Co Ltd 低温焼成多層基板用の内層銀ペースト組成物
JPH05174614A (ja) * 1991-12-26 1993-07-13 Matsushita Electric Ind Co Ltd 配線電極ペースト及び電子部品の製造方法
JPH0660715A (ja) * 1992-08-06 1994-03-04 Murata Mfg Co Ltd 導電ペースト及びそれを用いたセラミック電子部品の電極形成方法
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JP2000090733A (ja) * 1998-09-14 2000-03-31 Murata Mfg Co Ltd 導電性ペースト及びそれを用いた太陽電池
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Publication number Priority date Publication date Assignee Title
EP2754185A4 (fr) * 2011-09-09 2015-06-03 Heraeus Precious Metals North America Conshohocken Llc Contacts de cellule solaire à pastille d'argent
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JP2013175547A (ja) * 2012-02-24 2013-09-05 Namics Corp 太陽電池の電極形成用導電性ペースト
CN103854718A (zh) * 2012-12-03 2014-06-11 西北稀有金属材料研究院 一种太阳能电池正面电极浆料及其制备方法
CN103854718B (zh) * 2012-12-03 2016-03-30 西北稀有金属材料研究院 一种太阳能电池正面电极浆料及其制备方法
JP2015122177A (ja) * 2013-12-21 2015-07-02 株式会社ノリタケカンパニーリミテド 太陽電池用導電性ペースト組成物およびその製造方法

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