WO2013058418A1 - Silver paste composition (2) for the back electrode of a solar cell - Google Patents

Silver paste composition (2) for the back electrode of a solar cell Download PDF

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WO2013058418A1
WO2013058418A1 PCT/KR2011/007733 KR2011007733W WO2013058418A1 WO 2013058418 A1 WO2013058418 A1 WO 2013058418A1 KR 2011007733 W KR2011007733 W KR 2011007733W WO 2013058418 A1 WO2013058418 A1 WO 2013058418A1
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silver
solar cell
paste composition
silver paste
weight
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PCT/KR2011/007733
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French (fr)
Korean (ko)
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홍승권
임대성
이창모
최형섭
이창준
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동우 화인켐 주식회사
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Publication of WO2013058418A1 publication Critical patent/WO2013058418A1/en

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor 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
    • H01L31/02Details
    • H01L31/0224Electrodes
    • H01L31/022408Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20Conductive material dispersed in non-conductive organic material
    • H01B1/22Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy

Definitions

  • the present invention relates to a silver paste composition for a solar cell back electrode.
  • a PN junction is formed by diffusing phosphorus (P) on the surface of a P-type silicon wafer, and an antireflection film is coated to reduce reflection loss of sunlight incident on the P-type silicon wafer.
  • the Ag electrode is formed, and Ag and Al electrodes are formed on the back side P layer.
  • the silver paste used as the front electrode is connected to the N-side of silicon to form an electrode, and the aluminum paste is connected to the backside of silicon, that is, the P layer, to form an electrode.
  • Silicon crystalline solar cells generally use P-type silicon substrates with a thickness of 180-220 ⁇ m.
  • Phosphorus diffusion source in the front of the substrate typically phosphorus oxychloride (POCl) 3
  • POCl phosphorus oxychloride
  • N-type emitter layer with a thickness of 0.2-0.6 ⁇ m, and on top of it, a SiNx layer for antireflection is formed through plasma chemical vapor deposition (CVD).
  • CVD plasma chemical vapor deposition
  • the front silver paste is applied by screen printing and dried, and then the front electrode is formed by firing several seconds or several minutes at a high temperature (800-950 ° C) in an infrared belt furnace (Belt Furnace). .
  • An aluminum electrode is formed on the rear side, and the aluminum electrode is formed by applying an aluminum paste by screen printing or the like through drying and baking.
  • the silver or silver / aluminum paste printed on the back side is also fired at the same time to form the silver or silver / aluminum back electrode.
  • aluminum diffuses into the P-type silicon wafer, thereby forming an Al-Si alloy layer.
  • the diffusion layer (P + layer) forms a back surface field (BSF) that prevents recombination of electrons generated in the solar cell and improves the collection efficiency of the generated carriers.
  • Korean Patent No. 10-0798255 includes silver particles, glass particles, and an organic vehicle, and a conductive thick film used as an electrode for connecting with a rear terminal on a silicon substrate of a solar cell.
  • An electroconductive paste is disclosed which has an average particle diameter of the composition, in particular of the silver particles, between 3.0 and 15.0 ⁇ m.
  • the back electrode paste including the silver particles having a large size as described above has a disadvantage that the voids remain after the firing process because the internal porosity between the particles is high, thereby increasing the resistance of the wiring.
  • Korean Patent No. 10-0890866 discloses an electrode paste including silver and aluminum powder and Pb-free glass frit including aluminum particles to improve thermal expansion characteristics with a rear aluminum electrode.
  • the electrode paste has a disadvantage in that the resistance of the wiring is increased by adding aluminum particles having poor electrical conductivity to the silver paste, and the soldering property with the ribbon is degraded in the module manufacturing process of the solar cell.
  • the electrode paste provides an environmental advantage by using a Pb-free glass frit, but by using a glass frit containing Bi 2 O 3 component aluminum powder contained in the aluminum layer in the overlapping portion of silver-aluminum This causes a problem that the oxide film on the surface is thermally etched by the Bi 2 O 3 component. As a result, the reactivity of the aluminum powder and moisture is increased, thereby deteriorating the durability of the cell.
  • the present invention is to solve the above problems of the prior art, improve the efficiency of the solar cell by reducing the wiring resistance of the rear electrode and improve the adhesion with the silicon substrate, does not cause environmental problems,
  • An object of the present invention is to provide a silver paste for a solar cell back electrode which prevents a decrease in water resistance of an aluminum layer at a silver-aluminum overlapping portion, thereby contributing to improved durability.
  • the present invention also provides a solar cell comprising a back electrode formed of the silver paste composition for the solar cell back electrode.
  • the silver paste composition of the present invention uses silver particles having an average particle diameter of D 50 of 0.3 ⁇ m to 1.5 ⁇ m to minimize internal voids of the rear electrode and to improve adhesion to the silicon substrate. Therefore, it provides an effect of minimizing the resistance of the electrode wiring and improving the efficiency of the solar cell.
  • the present invention provides a paste composition has no fear of generating environmental problems due to the PbO component by using the glass frit does not contain the PbO component, and Bi 2 O 3 component, the rear electrode due to the Bi 2 O 3 component - The fall of the water resistance of the aluminum layer at the aluminum overlapping portion is prevented to improve the durability of the finished cell and module.
  • soldering characteristics may also be greatly improved when manufacturing a solar cell module.
  • Figure 1 is an image of the results of the water resistance test of the electrode formed of the silver paste composition of Example 1 of the present invention.
  • FIG. 2 is an image photographing the water resistance test results of the electrodes formed of the silver paste compositions of Comparative Examples 1 to 3.
  • FIG. 2 is an image photographing the water resistance test results of the electrodes formed of the silver paste compositions of Comparative Examples 1 to 3.
  • a silver paste composition for a solar cell back electrode comprising 20 to 34.9% by weight of an organic vehicle solution.
  • the silver paste composition of the present invention does not include PbO-based and Bi 2 O 3 -based glass frits, there is no fear of environmental problems caused by PbO-based glass frits, which is a problem caused by Bi 2 O 3 -based glass frits. And free from the problem of a decrease in the water resistance of the silver-aluminum overlapping portion due to thermal etching of the aluminum oxide film and a decrease in the durability of the finished cell.
  • the silver paste composition of this invention uses silver powder which has a specific average particle diameter as mentioned above, and contains an electrode containing a group 3 element or a group 3 element, or salts or hydrates thereof, and thus electrode wiring. It is characterized by minimizing the resistance.
  • the silver paste composition of the present invention may include some aluminum powder within the composition ratio range of the silver powder, but more preferably does not include aluminum powder in order to improve soldering characteristics in manufacturing a solar cell module.
  • the powder contained in the paste composition of the present invention has preferably a mean particle diameter (D 50) of particles is 0.3 ⁇ m ⁇ 1.5 ⁇ m.
  • D 50 of the silver particles is less than 0.3 ⁇ m, the specific surface area of the particles is widened, so that the viscosity of the paste composition is high and printability is reduced. In addition, this limits the content of silver particles.
  • the D 50 of the silver particles exceeds 1.5 ⁇ m, the density of the silver particles in the paste decreases, and a large amount of voids are generated in the wiring after the firing process, thereby increasing the resistance of the wiring.
  • the silver powder is preferably contained in 65 to 75% by weight relative to the total weight of the composition, when included in less than 65% by weight, the printed silver wiring layer is thinned after firing to increase the rear wiring resistance, soldering characteristics This will be lowered, and if it exceeds 75% by weight, the printing thickness will be too thick, which may result in warping of the silicon wafer.
  • the maximum particle diameter (Dmax) of the silver particles is preferably 4.5 ⁇ m or less, and the silver particles may be spherical or plate-shaped.
  • ZnO-based or V 2 O 3 -based glass frits that do not contain PbO and Bi 2 O 3 , which are included in the silver paste composition of the present invention are 0.01 to 10% by weight, preferably 0.5 to 7% by weight, based on the total weight of the composition. More preferably 1 to 5% by weight. If the glass frit is included in less than 0.01% by weight, the problem that the silver wiring after the firing process has a problem that the adhesion to the wafer, which is the substrate of the solar cell is reduced, if the content exceeds 10% by weight, the resistance is high and the efficiency of the solar cell is lowered Problem occurs.
  • ZnO-based or V 2 O 3- based glass frit that does not contain PbO and Bi 2 O 3 is ZnO 10 ⁇ 55mol%, V 2 O 3 0 ⁇ 70mol%, B 2 O 3 0 ⁇ 50mol%, alkaline earth metal oxide 1 ⁇ 10 mol%, SiO 2 0-35 mol% and alkali metal oxide 1-10 mol%;
  • '0' in the molar ratio means that the component is not included.
  • PbO-based glass frits have easy melting point control and low coefficient of thermal expansion, but are limited in use due to environmental problems. For this reason, Bi 2 O 3 based low melting glass frits having properties similar to PbO based are commonly used. However, in the case of the Bi 2 O 3 -based glass frit, the reactivity of thermal etching the aluminum oxide film is so high that the water resistance of the silver-aluminum overlapping portion is lowered and, as a result, the durability of the finished cell is reduced.
  • the structure of the solar cell shows that the rear silver electrode paste and the aluminum paste have overlapping portions, and the Bi 2 O 3 glass frit contained in the silver electrode paste diffuses into the aluminum layer by capillary action during the liquid phase sintering process.
  • the diffused Bi 2 O 3 glass frit thermally etches the oxide film on the aluminum powder surface forming the aluminum layer. Accordingly, the aluminum powder etched with the oxide film reacts with moisture in the air to generate hydrogen and rapidly oxidize, thereby degrading the water resistance of the silver-aluminum overlapping portion.
  • the softening point of the glass frit used by this invention is 350-600 degreeC. If the softening point is less than 350 ° C, the coefficient of thermal expansion of the glass frit becomes relatively large, causing a problem of increasing the warpage of the wafer after the firing step during the solar cell manufacturing process.
  • the adhesion between the wiring layer and the silicon wafer layer should be imparted, but the glass frit may not be sufficiently melted during the firing process, thereby causing a problem in that the adhesion is reduced.
  • Glass frits that do not contain PbO and Bi 2 O 3 components have a high melting point, so a large amount of wood-based formula is used, which increases the coefficient of thermal expansion and the warpage of silicon wafers during cell fabrication due to the relatively high coefficient of thermal expansion. This may be caused, but since the area of the cell is small, it does not have a great influence on the silicon wafer warpage phenomenon.
  • the organic vehicle solution included in the silver paste composition of the present invention is preferably included in 20 to 34.9% by weight based on the total weight of the composition. If the organic vehicle solution is contained in less than 20% by weight, the viscosity is too high, the printability is lowered, and if contained in excess of 34.9% by weight, the silver powder content is low, it is difficult to secure a sufficient thickness of the silver wiring layer.
  • the organic vehicle solution is prepared by dissolving a polymer resin in an organic solvent, and may further include a thixotropic agent, a humectant, an additive, and the like, as necessary.
  • the organic vehicle solution used in the present invention may be composed of 75% by weight or more of solvent and 1 to 25% by weight of the polymer resin, and, if necessary, about 5% by weight or less of a wetting agent and thixotropic agent, And 1 to 10% by weight may further include an additive.
  • a solvent having a breaking point in the range of about 150-300 ° C. is suitable to prevent drying of the paste during the printing process and to control fluidity.
  • Widely used solvents include glycol ether-based tripropylene glycol methyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, diethylene glycol ethyl ether.
  • Diethylene glycol n-butyl ether diethylene glycol hexyl ether, ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether, terpinol, texanol (Texanol ), Ethylene glycol, and the like.
  • polymer resin examples include polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, ethyl cellulose, rosin, phenol resin, acrylic resin and the like.
  • the content of the polymer resin is 1 to 25% by weight, preferably 5 to 25% by weight based on the total weight of the organic vehicle solution. If the amount of the polymer resin is less than 1% by weight, the printability and dispersion stability of the paste may be lowered. If the amount of the polymer resin exceeds 25% by weight, the paste may not be printed.
  • any one generally used in the art may be used without limitation.
  • the additives include those generally used in this field such as dispersants.
  • Commercially available surfactants can be used as the dispersant, and these can be used alone or in combination of two or more thereof.
  • the surfactant may be, for example, an ether type such as alkyl polyoxyethylene ether, alkylaryl polyoxyethylene ether, polyoxyethylene polyoxypropylene copolymer as a nonionic surfactant; Ester ether types such as polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitan ester, and polyoxyethylene ether of sorbitol ester; Ester type such as polyethylene glycol fatty acid ester, glycerin ester, sorbitan ester, propylene glycol ester, sugar ester, alkyl polyglucoside; Nitrogen-containing types such as fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, amine oxides; Polymeric surfactants include poly
  • Hypermer KD manufactured by Uniqema
  • AKM 0531 manufactured by Nippon Yuji Co., Ltd.
  • KP manufactured by Shin-Etsu Chemical Co., Ltd.
  • POLYFLOW polyflow
  • EFTOP manufactured by Tochem Products
  • Asahi guard above, manufactured by Asahi Glass
  • SOLSPERSE manufactured by Geneva
  • EFKA EFKA Chemicals, Inc.
  • PB 821 manufactured by Ajinomoto Co., Ltd.
  • BYK-111, BYK-184, BYK-185, BYK-2160, Anti-Terra U manufactured by BYK
  • the dispersant is preferably included in 1 to 10% by weight based on the total weight of the organic vehicle solution, more preferably 1 to 5% by weight.
  • a silver paste composition was prepared in the same manner as in Example 1, except that silver powder having a D 50 of 4.5 ⁇ m was used.
  • a surface texturing process was performed on a 156 ⁇ 156 mm, 200 ⁇ m thick single crystal wafer to form a pyramid height of about 4-6 ⁇ m, followed by coating SiNx on the N-side of the wafer. Subsequently, after printing and drying the respective Bus Bars using the paste compositions prepared in Examples 1 and Comparative Examples 1 to 3 on the back side of the wafer, Dongwoo Fine Chem Co., Ltd. aluminum electrode paste (trade name: AMP-BL122C) was applied using a screen printing plate and dried. Thereafter, the Finger Line was printed and dried on the front SiNx side using silver paste.
  • the silicon wafer passed through the above process was fired in an infrared continuous firing furnace such that the temperature of the firing region was 720 to 900 ° C. to manufacture a solar cell.
  • the firing process may be performed by simultaneous firing of the front and rear surfaces while passing the silicon wafer into a belt furnace.
  • the belt furnace includes a burn-out section at about 600 ° C. and a firing section at about 800 ° C. to 950 ° C., after burning off the organic material in the paste composition, the front and rear surfaces are melted with aluminum to form an electrode. To be.
  • the cell was placed in distilled water at 80 ° C. in a thermostatic chamber and left for 10 minutes. It was confirmed whether hydrogen gas was generated by reacting with water at the overlapped portion of the silver paste and the aluminum paste for 10 minutes, and after the test, there was a breakdown of the overlapped portion with an optical microscope and an electron microscope (FIGS. 1 and 2).
  • the silver paste composition of Example 1 of the present invention prevented a reaction from moisture at an overlapping portion with an aluminum paste, and thus did not generate bubbles.
  • the silver paste compositions of Comparative Examples 1 to 3 bubbles were generated due to reaction with moisture in the overlapping area with the aluminum paste, and electrode damage was also observed.

Abstract

The present invention relates to a silver paste composition for the back electrode of a solar cell. The silver paste composition includes a) 65 wt% to 75 wt% of silver powder having a mean particle diameter (D50) of 0.3 μm to 1.5 μm, b) 0.01 wt% to 10 wt% of ZnO-based or V2O3-based glass frit which does not contain PbO or Bi2O3, and c) 20 wt% to 34.8 wt% of an organic vehicle solution with respect to the gross weight of the composition.

Description

태양전지 후면 전극용 은 페이스트 조성물 (2)Silver Paste Composition for Solar Cell Back Electrode (2)
본 발명은 태양전지 후면 전극용 은 페이스트 조성물에 관한 것이다.The present invention relates to a silver paste composition for a solar cell back electrode.
실리콘 결정형 태양전지는 P형 실리콘 웨이퍼 표면에 인(P)을 확산시킴으로써 PN접합이 형성되고, 여기에 입사되는 태양빛의 반사손실을 줄이기 위하여 반사방지막을 코팅하고, 이렇게 구성된 웨이퍼의 전면 N층에 Ag 전극을 형성하고, 후면 P층에 Ag와 Al전극을 형성함으로써 구성된다. 전면 전극으로 사용되는 은-페이스트는 실리콘의 N-측에 연결되어 전극을 형성하고, 알루미늄 페이스트는 실리콘의 후면, 즉 P층과 연결되어 전극을 형성한다.In the silicon crystalline solar cell, a PN junction is formed by diffusing phosphorus (P) on the surface of a P-type silicon wafer, and an antireflection film is coated to reduce reflection loss of sunlight incident on the P-type silicon wafer. The Ag electrode is formed, and Ag and Al electrodes are formed on the back side P layer. The silver paste used as the front electrode is connected to the N-side of silicon to form an electrode, and the aluminum paste is connected to the backside of silicon, that is, the P layer, to form an electrode.
실리콘 결정형 태양전지는 일반적으로 두께가 180-220μm인 P형 실리콘 기판을 사용한다. 상기 기판의 전면부에 인 확산 공급원 통상 옥시염화인(POCl3)을 확산 시켜 0.2-0.6μm 두께의 N형 에미터 층을 형성하고, 그 위에 플라즈마 화학증착(CVD)을 통해 반사 방지를 위한 SiNx층이 형성한다. 실리콘 웨이퍼 전면부에는 전면 은 페이스트를 스크린 인쇄를 통해 도포 하고 이를 건조한 후, 적외선 벨트 로(Belt Furnace)에서 고온(800-950℃)의 온도로 수초 또는 수분의 소성 과정을 거쳐 전면 전극을 형성한다. 후면 부에는 알루미늄 전극이 형성되는데, 알루미늄 전극은 알루미늄 페이스트를 스크린 인쇄 등에 의해 도포하고 건조와 소성 과정을 거쳐 형성한다. 또한 후면에 인쇄된 은 또는 은/알루미늄 페이스트도 동시에 소성되어 은 또는 은/ 알루미늄 후면 전극을 형성한다. 이러한 소성과정에서 알루미늄이 P형 실리콘 웨이퍼의 내부로 확산되면서 Al-Si 합금층이 형성된다. 이러한 확산층(P+층)에 의해, 태양전지에서 생성되는 전자의 재결합을 방지하고 생성된 캐리어(Carrier)의 수집 효율을 향상시키는 BSF(Back Surface Field)가 형성된다.Silicon crystalline solar cells generally use P-type silicon substrates with a thickness of 180-220 μm. Phosphorus diffusion source in the front of the substrate, typically phosphorus oxychloride (POCl)3) To form an N-type emitter layer with a thickness of 0.2-0.6 μm, and on top of it, a SiNx layer for antireflection is formed through plasma chemical vapor deposition (CVD). On the front surface of the silicon wafer, the front silver paste is applied by screen printing and dried, and then the front electrode is formed by firing several seconds or several minutes at a high temperature (800-950 ° C) in an infrared belt furnace (Belt Furnace). . An aluminum electrode is formed on the rear side, and the aluminum electrode is formed by applying an aluminum paste by screen printing or the like through drying and baking. The silver or silver / aluminum paste printed on the back side is also fired at the same time to form the silver or silver / aluminum back electrode. In this firing process, aluminum diffuses into the P-type silicon wafer, thereby forming an Al-Si alloy layer. The diffusion layer (P + layer) forms a back surface field (BSF) that prevents recombination of electrons generated in the solar cell and improves the collection efficiency of the generated carriers.
상기 은 또는 은/알루미늄 페이스트와 관련하여, 대한민국 등록특허 제10-0798255호는 은 입자, 유리 입자 및 유기 비히클을 포함하며, 태양 전지의 규소 기판상의 후면 단자와 접속하기 위한 전극으로 사용되는 전도성 후막 조성물, 특히 은 입자의 평균 입경이 3.0 내지 15.0 ㎛인 전기전도성 페이스트를 개시하고 있다. 그러나, 상기와 같이 큰 사이즈를 갖는 은 입자를 포함하는 후면 전극 페이스트는, 입자들 사이의 내부 공극율이 높으므로 소성 공정 후에 공극이 잔존하며, 그에 따라 배선의 저항이 커지게 되는 단점을 갖는다.In relation to the silver or silver / aluminum paste, Korean Patent No. 10-0798255 includes silver particles, glass particles, and an organic vehicle, and a conductive thick film used as an electrode for connecting with a rear terminal on a silicon substrate of a solar cell. An electroconductive paste is disclosed which has an average particle diameter of the composition, in particular of the silver particles, between 3.0 and 15.0 μm. However, the back electrode paste including the silver particles having a large size as described above has a disadvantage that the voids remain after the firing process because the internal porosity between the particles is high, thereby increasing the resistance of the wiring.
또한, 대한민국 등록특허 제10-0890866호는, 후면 알루미늄 전극과의 열팽창 특성을 개선하기 위하여 알루미늄 입자를 포함하는, 은과 알루미늄 분말, Pb-무함유 글라스 프릿을 포함하는 전극 페이스트를 개시하고 있다. 그러나 이러한 전극 페이스트는 전기 전도도가 떨어지는 알루미늄 입자를 은 페이스트에 첨가함으로써 배선의 저항이 상승하며, 태양전지의 모듈제조 공정에서 리본과의 납땜특성이 저하되는 단점을 갖는다. In addition, Korean Patent No. 10-0890866 discloses an electrode paste including silver and aluminum powder and Pb-free glass frit including aluminum particles to improve thermal expansion characteristics with a rear aluminum electrode. However, the electrode paste has a disadvantage in that the resistance of the wiring is increased by adding aluminum particles having poor electrical conductivity to the silver paste, and the soldering property with the ribbon is degraded in the module manufacturing process of the solar cell.
또한, 상기 전극 페이스트는, Pb-무함유 글라스 프릿을 사용하여 환경적인 이점을 제공하나, Bi2O3 성분이 함유된 글라스 프릿을 사용함으로써 은-알루미늄의 중첩부위에서 알루미늄층에 포함된 알루미늄분말 표면의 산화막이 Bi2O3 성분에 의하여 열에칭되는 문제를 야기한다. 그 결과, 알루미늄 분말과 수분의 반응성이 증가되므로, 셀의 내구성이 저하된다. In addition, the electrode paste provides an environmental advantage by using a Pb-free glass frit, but by using a glass frit containing Bi 2 O 3 component aluminum powder contained in the aluminum layer in the overlapping portion of silver-aluminum This causes a problem that the oxide film on the surface is thermally etched by the Bi 2 O 3 component. As a result, the reactivity of the aluminum powder and moisture is increased, thereby deteriorating the durability of the cell.
본 발명은, 종래기술의 상기와 같은 문제를 해결하기 위한 것으로서, 후면 전극의 배선 저항을 감소시키고 실리콘 기판과의 밀착성을 향상시킴으로써 태양전지의 효율을 향상시키며, 환경문제를 야기하지 않으며, 후면 전극의 은-알루미늄 중첩부위에서 알루미늄층의 내수성 저하를 방지하여 내구성 향상에 기여하는 태양전지 후면 전극용 은 페이스트를 제공하는 것을 목적으로 한다.The present invention is to solve the above problems of the prior art, improve the efficiency of the solar cell by reducing the wiring resistance of the rear electrode and improve the adhesion with the silicon substrate, does not cause environmental problems, An object of the present invention is to provide a silver paste for a solar cell back electrode which prevents a decrease in water resistance of an aluminum layer at a silver-aluminum overlapping portion, thereby contributing to improved durability.
본 발명은, 조성물 총 중량에 대하여,The present invention, with respect to the total weight of the composition,
a) 입자의 평균입경(D50)이 0.3㎛ ~ 1.5㎛인 은 분말 65~75 중량%, a) 65 to 75% by weight of silver powder having an average particle diameter (D 50 ) of the particles of 0.3 μm to 1.5 μm,
b) PbO 및 Bi2O3를 포함하지 않는 ZnO계 또는 V2O3계 글라스 프릿 0.01~10 중량%, 및b) 0.01 to 10% by weight of a ZnO-based or V 2 O 3 -based glass frit containing no PbO and Bi 2 O 3 , and
c) 유기 비히클 용액 20~34.9 중량%를 포함하는 태양전지 후면 전극용 은 페이스트 조성물을 제공한다.c) providing a silver paste composition for a solar cell back electrode comprising 20 to 34.9% by weight of an organic vehicle solution.
본 발명은 또한, 상기 태양전지 후면 전극용 은 페이스트 조성물로 형성된 후면 전극을 포함하는 것을 특징으로 하는 태양전지를 제공한다.The present invention also provides a solar cell comprising a back electrode formed of the silver paste composition for the solar cell back electrode.
본 발명의 은 페이스트 조성물은 평균입경인 D50이 0.3㎛ ~ 1.5㎛인 은 입자를 사용함으로써 후면 전극의 내부 공극을 최소화하며 실리콘 기판과의 밀착성도 향상시킨다. 따라서, 전극 배선의 저항을 최소화하고 태양전지의 효율을 향상시키는 효과를 제공한다. The silver paste composition of the present invention uses silver particles having an average particle diameter of D 50 of 0.3 μm to 1.5 μm to minimize internal voids of the rear electrode and to improve adhesion to the silicon substrate. Therefore, it provides an effect of minimizing the resistance of the electrode wiring and improving the efficiency of the solar cell.
또한, 본 발명의 은 페이스트 조성물은 PbO 성분 및 Bi2O3 성분이 함유되지 않은 글라스 프릿을 사용함으로써 PbO 성분으로 인한 환경문제 발생의 염려가 없으며, Bi2O3 성분에 의한 후면 전극의 은-알루미늄 중첩부위에서의 알루미늄층의 내수성 저하가 방지되어 완성된 셀 및 모듈의 내구성을 향상시킨다.Further, the present invention provides a paste composition has no fear of generating environmental problems due to the PbO component by using the glass frit does not contain the PbO component, and Bi 2 O 3 component, the rear electrode due to the Bi 2 O 3 component - The fall of the water resistance of the aluminum layer at the aluminum overlapping portion is prevented to improve the durability of the finished cell and module.
또한, 본 발명의 은 페이스트 조성물이 알루미늄을 포함하지 않는 경우에는 태양전지 모듈 제조 시 납땜특성도 크게 향상시킬 수 있다.In addition, in the case where the silver paste composition of the present invention does not include aluminum, soldering characteristics may also be greatly improved when manufacturing a solar cell module.
도1은 본 발명의 실시예1의 은 페이스트 조성물로 형성된 전극의 내수성 테스트 결과를 촬영한 이미지이다. Figure 1 is an image of the results of the water resistance test of the electrode formed of the silver paste composition of Example 1 of the present invention.
도2는 비교예 1~3의 은 페이스트 조성물로 형성된 전극의 내수성 테스트 결과를 촬영한 이미지이다.FIG. 2 is an image photographing the water resistance test results of the electrodes formed of the silver paste compositions of Comparative Examples 1 to 3. FIG.
본 발명은, 조성물 총 중량에 대하여,The present invention, with respect to the total weight of the composition,
a) 입자의 평균입경(D50)이 0.3㎛ ~ 1.5㎛인 은 분말 65~75 중량%, a) 65 to 75% by weight of silver powder having an average particle diameter (D 50 ) of the particles of 0.3 μm to 1.5 μm,
b) PbO 및 Bi2O3를 포함하지 않는 ZnO계 또는 V2O3계 글라스 프릿 0.01~10 중량%, 및b) 0.01 to 10% by weight of a ZnO-based or V 2 O 3 -based glass frit containing no PbO and Bi 2 O 3 , and
c) 유기 비히클 용액 20~34.9 중량%를 포함하는 태양전지 후면 전극용 은 페이스트 조성물에 관한 것이다.c) a silver paste composition for a solar cell back electrode comprising 20 to 34.9% by weight of an organic vehicle solution.
본 발명의 은 페이스트 조성물은 PbO계 및 Bi2O3계 글라스 프릿을 포함하지 않기 때문에, PbO계의 글라스 프릿으로 인한 환경문제 발생의 염려가 없으며, Bi2O3계 글라스 프릿이 야기 하는 문제 즉, 알루미늄 산화막의 열에칭에 의한 은-알루미늄 중첩부위의 내수성 저하 및 그로 인한 완성된 셀의 내구성 저하의 문제로부터 자유로운 특징을 갖는다.Since the silver paste composition of the present invention does not include PbO-based and Bi 2 O 3 -based glass frits, there is no fear of environmental problems caused by PbO-based glass frits, which is a problem caused by Bi 2 O 3 -based glass frits. And free from the problem of a decrease in the water resistance of the silver-aluminum overlapping portion due to thermal etching of the aluminum oxide film and a decrease in the durability of the finished cell.
또한, 본 발명의 은 페이스트 조성물은 상기와 같은 특정의 평균입경을 갖는 은 분말을 사용하며, 3족 원소 또는 3족 원소를 포함하는 화합물, 또는 이들의 염 또는 이들의 수화물을 포함함으로써, 전극 배선의 저항을 최소화하는 특징을 갖는다. In addition, the silver paste composition of this invention uses silver powder which has a specific average particle diameter as mentioned above, and contains an electrode containing a group 3 element or a group 3 element, or salts or hydrates thereof, and thus electrode wiring. It is characterized by minimizing the resistance.
본 발명의 은 페이스트 조성물은 상기 은 분말의 조성비 범위 내에서 알루미늄 분말을 일부 포함하는 것도 가능하나, 태양전지 모듈 제조 시 납땜특성을 향상시키기 위해서는 알루미늄 분말을 포함하지 않는 것이 더욱 바람직하다.The silver paste composition of the present invention may include some aluminum powder within the composition ratio range of the silver powder, but more preferably does not include aluminum powder in order to improve soldering characteristics in manufacturing a solar cell module.
본 발명의 은 페이스트 조성물에 포함되는 은 분말은 입자의 평균입경(D50)이 0.3㎛ ~ 1.5㎛인 것이 바람직하다. 은 입자의 D50이 0.3㎛ 미만이 되면 입자의 비표면적이 넓어지므로 페이스트 조성물의 점도가 높아지며, 인쇄성이 저하된다. 또한, 이로 인하여 은 입자의 함량을 높이는데 제한을 받게 된다. 은 입자의 D50이 1.5㎛를 초과하게 되면 페이스트 내의 은 입자의 치밀도가 떨어져 소성공정 후 배선 내부에 공극이 다량 발생하여 배선의 저항이 상승하게 된다.The powder contained in the paste composition of the present invention has preferably a mean particle diameter (D 50) of particles is 0.3㎛ ~ 1.5㎛. When the D 50 of the silver particles is less than 0.3 µm, the specific surface area of the particles is widened, so that the viscosity of the paste composition is high and printability is reduced. In addition, this limits the content of silver particles. When the D 50 of the silver particles exceeds 1.5 µm, the density of the silver particles in the paste decreases, and a large amount of voids are generated in the wiring after the firing process, thereby increasing the resistance of the wiring.
본 발명에서 은 분말은, 조성물 총 중량에 대하여 65~75 중량%로 포함되는 것이 바람직하며, 65 중량% 미만으로 포함되면 소성 후 인쇄된 은 배선 층이 얇아져서 후면 배선 저항이 증가하고, 납땜특성이 저하되게 되며, 75 중량%를 초과하면 인쇄두께가 너무 두꺼워지고 이로 인하여 실리콘 웨이퍼의 휨이 초래될 수 있다.In the present invention, the silver powder is preferably contained in 65 to 75% by weight relative to the total weight of the composition, when included in less than 65% by weight, the printed silver wiring layer is thinned after firing to increase the rear wiring resistance, soldering characteristics This will be lowered, and if it exceeds 75% by weight, the printing thickness will be too thick, which may result in warping of the silicon wafer.
본 발명에서 상기 은 입자의 최대 입경(Dmax)은 4.5㎛ 이하인 것이 바람직하며, 은 입자의 형태는 구형 또는 판상형인 것이 사용될 수 있다. In the present invention, the maximum particle diameter (Dmax) of the silver particles is preferably 4.5 μm or less, and the silver particles may be spherical or plate-shaped.
본 발명의 은 페이스트 조성물에 포함되는, PbO 및 Bi2O3를 포함하지 않는 ZnO계 또는 V2O3계 글라스 프릿은 조성물 총 중량에 대하여 0.01~10 중량%, 바람직하게는 0.5~7중량%, 더욱 바람직하게는 1~5중량%로 포함된다. 상기 글라스프릿이 0.01 중량% 미만으로 포함되면 소성 공정 후 은 배선이 태양전지의 기재인 웨이퍼와의 부착력이 떨어지는 문제가 발생되고, 10 중량%를 초과하여 포함되면 저항이 높아져 태양전지의 효율이 저하되는 문제가 발생된다. ZnO-based or V 2 O 3 -based glass frits that do not contain PbO and Bi 2 O 3 , which are included in the silver paste composition of the present invention, are 0.01 to 10% by weight, preferably 0.5 to 7% by weight, based on the total weight of the composition. More preferably 1 to 5% by weight. If the glass frit is included in less than 0.01% by weight, the problem that the silver wiring after the firing process has a problem that the adhesion to the wafer, which is the substrate of the solar cell is reduced, if the content exceeds 10% by weight, the resistance is high and the efficiency of the solar cell is lowered Problem occurs.
상기 PbO 및 Bi2O3를 포함하지 않는 ZnO계 또는 V2O3계 글라스 프릿은 ZnO 10~55mol%, V2O3 0~70mol%, B2O3 0~50mol%, 알칼리 토금속 산화물 1~10mol%, SiO2 0~35mol% 및 알칼리금속 산화물 1~10mol%를 포함하는 것이 바람직하며;ZnO-based or V 2 O 3- based glass frit that does not contain PbO and Bi 2 O 3 is ZnO 10 ~ 55mol%, V 2 O 3 0 ~ 70mol%, B 2 O 3 0 ~ 50mol%, alkaline earth metal oxide 1 ˜10 mol%, SiO 2 0-35 mol% and alkali metal oxide 1-10 mol%;
ZnO 20~50mol%, B2O3 30~50mol%, BaO 5~10mol%, SiO2 0~10mol% 및 Na2O 2~10mol%를 포함하거나, ZnO 20-50 mol%, B 2 O 3 30-50mol%, BaO 5-10mol%, SiO 2 0-10mol% and Na 2 O 2-10mol%,
ZnO 10~25mol%, V2O3 60~70mol%, B2O3 1~10mol%, BaO 5~10mol%, SiO2 0~10mol% 및 Na2O 2~10mol%를 포함하는 경우에 더욱 바람직하다. ZnO 10-25 mol%, V 2 O 3 60-70 mol%, B 2 O 3 1-10mol%, BaO 5-10mol%, SiO 2 0-10mol% and Na 2 O 2-10mol% desirable.
상기 몰비에서 '0'은 해당 성분을 포함하지 않는 것을 의미한다.'0' in the molar ratio means that the component is not included.
일반적으로 PbO계의 글라스 프릿은 융점 제어가 용이하고 열팽창계수가 낮은 특성이 있으나 환경문제로 인해 사용이 제한되고 있다. 그런 이유로 PbO계와 유사한 특성을 갖는 Bi2O3계 저융점 글라스 프릿이 통상적으로 이용되고 있다. 그러나, Bi2O3계 글라스 프릿의 경우 알루미늄 산화막을 열에칭하는 반응성이 너무 커서 은-알루미늄 중첩부위의 내수성을 저하시키고 결과적으로 완성된 셀의 내구성을 저하시킨다.In general, PbO-based glass frits have easy melting point control and low coefficient of thermal expansion, but are limited in use due to environmental problems. For this reason, Bi 2 O 3 based low melting glass frits having properties similar to PbO based are commonly used. However, in the case of the Bi 2 O 3 -based glass frit, the reactivity of thermal etching the aluminum oxide film is so high that the water resistance of the silver-aluminum overlapping portion is lowered and, as a result, the durability of the finished cell is reduced.
즉, 태양전지 셀의 구조를 보면 후면 은 전극 페이스트와 알루미늄 페이스트는 중첩부위가 존재하는데, 은 전극 페이스트에 포함된 Bi2O3계 글라스 프릿은 액상 소결 과정에서 모세관현상에 의해 알루미늄 층으로 확산되며, 확산된 Bi2O3계 글라스 프릿은 알루미늄층을 형성하는 알루미늄 분말표면의 산화막을 열에칭한다. 따라서, 산화막이 에칭된 알루미늄 분말은 공기중의 수분과 반응하여 수소를 발생시킴과 동시에 급격하게 산화되므로, 은-알루미늄 중첩부위의 내수성이 저하되게 된다. In other words, the structure of the solar cell shows that the rear silver electrode paste and the aluminum paste have overlapping portions, and the Bi 2 O 3 glass frit contained in the silver electrode paste diffuses into the aluminum layer by capillary action during the liquid phase sintering process. The diffused Bi 2 O 3 glass frit thermally etches the oxide film on the aluminum powder surface forming the aluminum layer. Accordingly, the aluminum powder etched with the oxide film reacts with moisture in the air to generate hydrogen and rapidly oxidize, thereby degrading the water resistance of the silver-aluminum overlapping portion.
본 발명에서는 사용되는 글라스 프릿은 연화점이 350~600℃인 것이 바람직하다. 연화점이 350℃ 미만인 경우에는 글라스 프릿의 열팽창계수가 상대적으로 커져서 태양전지 제조 공정 중, 소성공정을 거친 후에 웨이퍼의 휨을 증가시키는 문제가 발생되며, 600℃를 초과하는 경우에는 글라스 프릿이 용융되어 은 배선 층과 실리콘 웨이퍼 층 사이에서 밀착성을 부여해야 되는데 소성과정에서 글라스 프릿이 충분히 용융되지 않아 밀착성이 저하되는 문제가 발생될 수 있다. It is preferable that the softening point of the glass frit used by this invention is 350-600 degreeC. If the softening point is less than 350 ° C, the coefficient of thermal expansion of the glass frit becomes relatively large, causing a problem of increasing the warpage of the wafer after the firing step during the solar cell manufacturing process. The adhesion between the wiring layer and the silicon wafer layer should be imparted, but the glass frit may not be sufficiently melted during the firing process, thereby causing a problem in that the adhesion is reduced.
PbO 성분과 Bi2O3 성분이 함유되지 않은 글라스 프릿의 경우 일반적으로 융점이 높기 때문에 망목수식제가 상당량 사용되는데 이로 인해 열팽창계수가 증가하고 상대적으로 높은 열팽창계수로 인해 셀 제조 시 실리콘 웨이퍼의 휨 현상이 야기될 수 있으나, 셀 전체면적 대비 은 전극의 면적이 작기 때문에 실리콘 웨이퍼 휨 현상에 지대한 영향을 끼치지는 않는다.Glass frits that do not contain PbO and Bi 2 O 3 components have a high melting point, so a large amount of wood-based formula is used, which increases the coefficient of thermal expansion and the warpage of silicon wafers during cell fabrication due to the relatively high coefficient of thermal expansion. This may be caused, but since the area of the cell is small, it does not have a great influence on the silicon wafer warpage phenomenon.
본 발명의 은 페이스트 조성물에 포함되는 유기 비히클 용액은 조성물 총 중량에 대하여 20~34.9 중량%로 포함되는 것이 바람직하다. 유기 비히클 용액이 20 중량% 미만으로 포함되면 점도가 너무 높아져 인쇄성이 저하되는 문제가 발생되고, 34.9 중량%를 초과하여 포함되면 은 분말 함유량이 낮아져서 충분한 은 배선 층의 두께를 확보하기 어렵다. The organic vehicle solution included in the silver paste composition of the present invention is preferably included in 20 to 34.9% by weight based on the total weight of the composition. If the organic vehicle solution is contained in less than 20% by weight, the viscosity is too high, the printability is lowered, and if contained in excess of 34.9% by weight, the silver powder content is low, it is difficult to secure a sufficient thickness of the silver wiring layer.
상기 유기 비히클 용액은 유기용매에 고분자 수지를 녹여서 제조하며, 필요에 따라, 요변성제, 습윤제, 첨가제 등을 더 포함할 수 있다.The organic vehicle solution is prepared by dissolving a polymer resin in an organic solvent, and may further include a thixotropic agent, a humectant, an additive, and the like, as necessary.
본 발명에 사용되는 유기 비히클 용액은 용액 총 중량에 대하여, 75 중량% 이상의 용매 및 1~25중량%의 고분자 수지로 구성될 수 있으며, 필요에 따라, 약 5 중량% 이하의 습윤제와 요변성제, 및 1~10 중량% 첨가제를 더 포함할 수 있다. The organic vehicle solution used in the present invention may be composed of 75% by weight or more of solvent and 1 to 25% by weight of the polymer resin, and, if necessary, about 5% by weight or less of a wetting agent and thixotropic agent, And 1 to 10% by weight may further include an additive.
상기 용매로는 인쇄공정 중 페이스트의 건조를 막고 유동성을 조절할 수 있도록 약 150-300℃ 범위의 끊는점을 갖는 용매가 적합하다. 널리 사용되는 용매로는 글리콜 에테르 계열로 트리프로필렌글리콜 메틸에테르, 디프로필렌글리콜 n-프로필에테르, 디프로필렌글리콜 n-부틸에테르, 트리프로필렌글리콜 n-부틸에테르, 프로필렌글리콜 페닐에테르, 디에틸렌글리콜 에틸에테르, 디에틸렌글리콜 n-부틸에테르, 디에틸렌글리콜 헥실에테르, 에틸렌글리콜 헥실에테르, 트리에틸렌글리콜 메틸에테르, 트리에틸렌글리콜 에틸에테르, 트리에틸렌글리콜 n-부틸에테르, 에틸렌글리콜 페닐에테르, 터피놀, 텍사놀
Figure PCTKR2011007733-appb-I000001
(Texanol
Figure PCTKR2011007733-appb-I000002
), 에틸렌글리콜 등을 들 수 있다.
As the solvent, a solvent having a breaking point in the range of about 150-300 ° C. is suitable to prevent drying of the paste during the printing process and to control fluidity. Widely used solvents include glycol ether-based tripropylene glycol methyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, diethylene glycol ethyl ether. , Diethylene glycol n-butyl ether, diethylene glycol hexyl ether, ethylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol n-butyl ether, ethylene glycol phenyl ether, terpinol, texanol
Figure PCTKR2011007733-appb-I000001
(Texanol
Figure PCTKR2011007733-appb-I000002
), Ethylene glycol, and the like.
상기 고분자 수지로는 폴리비닐피롤리돈, 폴리비닐알코올, 폴리에틸렌글리콜, 에틸셀룰로오스, 로진, 페놀 수지, 아크릴 수지 등을 들 수 있다. 고분자 수지의 함량은 유기 비히클 용액 총 중량에 대하여 1~25 중량%, 바람직하게는 5~25 중량%가 좋다. 고분자수지의 첨가량이 1 중량% 미만일 경우 페이스트의 인쇄성 및 분산 안정성이 저하되고, 25 중량%를 초과할 경우에는 페이스트가 인쇄되지 않는 문제를 초래 할 수 있다.Examples of the polymer resin include polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, ethyl cellulose, rosin, phenol resin, acrylic resin and the like. The content of the polymer resin is 1 to 25% by weight, preferably 5 to 25% by weight based on the total weight of the organic vehicle solution. If the amount of the polymer resin is less than 1% by weight, the printability and dispersion stability of the paste may be lowered. If the amount of the polymer resin exceeds 25% by weight, the paste may not be printed.
상기 요변성제 및 습윤제로는 이 분야에서 일반적으로 사용되는 것을 제한 없이 사용할 수 있다.As the thixotropic agent and the humectant, any one generally used in the art may be used without limitation.
상기 첨가제로는 분산제 등 이 분야에서 일반적으로 사용되는 것을 들 수 있다. 상기 분산제로는 시판되는 계면 활성제를 이용할 수 있고, 이들은 각각 단독으로 또는 2종 이상을 조합하여 사용할 수 있다. 상기의 계면 활성제는, 예를 들면, 비이온성 계면활성제로서 알킬 폴리옥시에틸렌에테르, 알킬아릴 폴리옥시에틸렌에테르, 폴리옥시에틸렌 폴리옥시프로필렌 공중합체와 같은 에테르형; 글리세린에스테르의 폴리옥시에틸렌에테르, 솔비탄 에스테르의 폴리옥시에틸렌에테르, 솔비톨 에스테르의 폴리옥시에틸렌에테르 같은 에스테르에테르형; 폴리에틸렌글리콜지방산에스테르, 글리세린에스테르, 솔비탄에스테르, 프로필렌글리콜에스테르, 슈가에스테르, 알킬폴리글루코시드 같은 에스테르형; 지방산알카놀아미드, 폴리옥시에틸렌지방산아미드, 폴리옥시에틸렌알킬아민, 아민 옥사이드 같은 함질소형이 있으며; 고분자계 계면활성제로서 폴리비닐알콜, 폴리비닐피롤리돈, 폴리아크릴산, 폴리아크릴산-말레인산 공중합체, 폴리 12-히드록시스테아린산 등이 있다.The additives include those generally used in this field such as dispersants. Commercially available surfactants can be used as the dispersant, and these can be used alone or in combination of two or more thereof. The surfactant may be, for example, an ether type such as alkyl polyoxyethylene ether, alkylaryl polyoxyethylene ether, polyoxyethylene polyoxypropylene copolymer as a nonionic surfactant; Ester ether types such as polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitan ester, and polyoxyethylene ether of sorbitol ester; Ester type such as polyethylene glycol fatty acid ester, glycerin ester, sorbitan ester, propylene glycol ester, sugar ester, alkyl polyglucoside; Nitrogen-containing types such as fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, amine oxides; Polymeric surfactants include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylic acid-maleic acid copolymers, poly 12-hydroxystearic acid, and the like.
시판되는 상품으로는 하이퍼머(hypermer) KD(Uniqema 제조), AKM 0531(일본유지㈜ 제조), KP(신에쯔 가가꾸 고교㈜ 제조), 폴리플로우 (POLYFLOW)(교에이샤 가가꾸㈜ 제조), 에프톱(EFTOP)(토켐 프로덕츠사 제조), 아사히가드(Asahi guard), 서플론(Surflon)(이상, 아사히 글라스㈜ 제조), 솔스퍼스(SOLSPERSE)(제네까㈜ 제조), EFKA(EFKA 케미칼스사 제조), PB 821(아지노모또㈜ 제조), BYK-111, BYK-184, BYK-185, BYK-2160, Anti-Terra U(BYK사 제조) 등을 들 수 있다. Commercially available products include Hypermer KD (manufactured by Uniqema), AKM 0531 (manufactured by Nippon Yuji Co., Ltd.), KP (manufactured by Shin-Etsu Chemical Co., Ltd.), and polyflow (POLYFLOW) (manufactured by Kyoeisha Kagaku Co., Ltd.). ), EFTOP (manufactured by Tochem Products), Asahi guard, Suflon (above, manufactured by Asahi Glass), SOLSPERSE (manufactured by Geneva), EFKA (EFKA) Chemicals, Inc.), PB 821 (manufactured by Ajinomoto Co., Ltd.), BYK-111, BYK-184, BYK-185, BYK-2160, Anti-Terra U (manufactured by BYK), and the like.
상기 분산제는 유기 비히클 용액 총 중량에 대하여 1~10 중량%로 포함되는 것이 바람직하며, 더욱 바람직하게는 1~5 중량%가 좋다.The dispersant is preferably included in 1 to 10% by weight based on the total weight of the organic vehicle solution, more preferably 1 to 5% by weight.
이하에서, 실시예를 통하여 본 발명을 보다 상세히 설명한다. 그러나, 하기의 실시예는 본 발명을 더욱 구체적으로 설명하기 위한 것으로서, 본 발명의 범위가 하기의 실시예에 의하여 한정되는 것은 아니다. 하기의 실시예는 본 발명의 범위 내에서 당업자에 의해 적절히 변경될 수 있다. Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by the following examples. The following examples may be appropriately modified by those skilled in the art within the scope of the present invention.
실시예1 및 비교예1 내지 3: 은 페이스트 조성물의 제조Example 1 and Comparative Examples 1 to 3: Preparation of Silver Paste Composition
조성물 총 중량에 대하여, D50=1.0㎛인 은 분말 70 중량%, 하기 표1의 조성의 글라스 프릿 4.5 중량% 및 에틸셀룰로오스를 글리콜 에테르에 용해시킨 유기 비히클 용액 25.5 중량%를 순차적으로 첨가하고, 자전 및 공전을 동시에 수행하는 믹서를 이용하여 1,000rpm에서 3분간 교반을 실시하여 은 페이스트 조성물을 제조하였다. To the total weight of the composition, 70% by weight of silver powder having a D 50 = 1.0 μm, 4.5% by weight of glass frit having the composition shown in Table 1 below, and 25.5% by weight of an organic vehicle solution in which ethylcellulose was dissolved in glycol ether, were added sequentially. A silver paste composition was prepared by stirring at 1,000 rpm for 3 minutes using a mixer that rotates and rotates simultaneously.
비교예4: 은 페이스트 조성물 제조Comparative Example 4: Preparation of Silver Paste Composition
D50=4.5㎛인 은 분말을 사용한 것을 제외하고는 상기 실시예1과 동일한 방법으로 은 페이스트 조성물을 제조하였다.A silver paste composition was prepared in the same manner as in Example 1, except that silver powder having a D 50 of 4.5 μm was used.
표 1
글라스프릿조성 Al2O3 B2O3 PbO Bi2O3 P2O5 ZnO SiO2 BaO Na2O
프릿1 33 7 48 6 6
프릿1 15 24 15 46
프릿2 9 39 17 9 26
프릿3 4 13 30 53
Table 1
Glass frit composition Al2O3 B2O3 PbO Bi2O3 P2O5 ZnO SiO2 BaO Na2O
Frit1 33 7 48 6 6
Frit1 15 24 15 46
Frit2 9 39 17 9 26
Frit3 4 13 30 53
            
(단위: mol%)(Unit: mol%)
시험예: 태양전지의 제조 및 특성 테스트Test Example: Manufacturing and Characteristic Test of Solar Cell
156X156mm, 200μm 두께의 단결정 웨이퍼에 표면 텍스쳐링 공정을 수행하여 피라미드 높이를 약 4-6μm로 형성시킨 후, 웨이퍼의 N-측 상에 SiNx를 코팅하였다. 이어서, 웨이퍼의 후면에 상기 실시예1 및 비교예1~3에서 제조된 페이스트 조성물을 사용하여 각각의 Bus Bar를 인쇄하고 건조시킨 후, 동우화인켐㈜사 알루미늄 전극 페이스트(상품명 : AMP-BL122C)를 스크린 인쇄판을 이용하여 도포하고 건조시켰다. 그 후, 전면 SiNx측 상에 은 페이스트를 이용하여 Finger Line을 인쇄하고 건조하였다.A surface texturing process was performed on a 156 × 156 mm, 200 μm thick single crystal wafer to form a pyramid height of about 4-6 μm, followed by coating SiNx on the N-side of the wafer. Subsequently, after printing and drying the respective Bus Bars using the paste compositions prepared in Examples 1 and Comparative Examples 1 to 3 on the back side of the wafer, Dongwoo Fine Chem Co., Ltd. aluminum electrode paste (trade name: AMP-BL122C) Was applied using a screen printing plate and dried. Thereafter, the Finger Line was printed and dried on the front SiNx side using silver paste.
상기 과정을 거친 실리콘 웨이퍼를 적외선 연속 소성로에서 소성영역의 온도가 720~900℃가 되도록 소성하여 태양전지를 제조하였다.The silicon wafer passed through the above process was fired in an infrared continuous firing furnace such that the temperature of the firing region was 720 to 900 ° C. to manufacture a solar cell.
상기 소성공정은 상기 실리콘 웨이퍼를 벨트 로(Belt Furnace) 내로 통과 시키면서 전후면 동시 소성에 의해 수행될 수도 있다. 이때, 벨트 로(Belt Furnace)는 약 600℃의 Burn-out 구간과 800~950℃ 부근의 Firing 구간을 포함하며, 페이스트 조성물 내 유기물을 태워 없앤 후, 전후면 은과 알루미늄을 용융시켜서 전극이 형성되게 한다.The firing process may be performed by simultaneous firing of the front and rear surfaces while passing the silicon wafer into a belt furnace. At this time, the belt furnace includes a burn-out section at about 600 ° C. and a firing section at about 800 ° C. to 950 ° C., after burning off the organic material in the paste composition, the front and rear surfaces are melted with aluminum to form an electrode. To be.
소성 후 완성된 셀의 내수성을 평가하기 위하여 항온조에서 80℃의 증류수에 셀을 넣고 10분간 방치하였다. 10분 동안 은 페이스트와 알루미늄 페이스트의 중첩부위에서 수분과 반응하여 수소기체가 발생되는가를 확인하였고, 테스트 후 광학현미경 및 전자현미경으로 중첩부위의 파손이 있는가를 확인하였다(도1 및 2). In order to evaluate the water resistance of the finished cell after firing, the cell was placed in distilled water at 80 ° C. in a thermostatic chamber and left for 10 minutes. It was confirmed whether hydrogen gas was generated by reacting with water at the overlapped portion of the silver paste and the aluminum paste for 10 minutes, and after the test, there was a breakdown of the overlapped portion with an optical microscope and an electron microscope (FIGS. 1 and 2).
<수분 반응성에 대한 평가 기준> Evaluation Criteria for Water Reactivity
기포발생Bubble
양호: 기포 미발생Good: No bubbles
NG: 기포 발생 NG: bubble generation
전극손상Electrode damage
양호: 중첩부위의 박리 또는 부스러짐 현상 없음Good: No peeling or chipping of overlapping part
NG: 중첩부위의 박리 또는 부스러짐 현상 있음NG: peeling or chipping of overlapping part
태양전지의 효율은 FitTech사의 태양전지 성능 평가 장치인 SCM-1000을 이용하여 평가하고, 그 결과를 하기 표2에 나타내었다.The efficiency of the solar cell was evaluated using SCM-1000, a solar cell performance evaluation device of FitTech, and the results are shown in Table 2 below.
표 2
조성 주성분 Tg(oC) CTE (10-7/oC) 기포발생 전극손상 효율 (%)
실시예1 Zn-, B- 480 74 양호 양호 17.5 0.3
비교예1 Si- (Bi함유) 520 68 불량 불량 17.5 0.3
비교예2 B-, Si- (Bi 함유) 505 70 불량 불량 17.5 0.3
비교예3 Pb-, Bi-, Zn- 454 48 불량 불량 17.5 0.3
비교예4 Zn-, B- 480 74 양호 양호 17.1 0.3
TABLE 2
Furtherance chief ingredient Tg ( o C) CTE (10 -7 / o C) Bubble Electrode damage efficiency (%)
Example 1 Zn-, B- 480 74 Good Good 17.5 0.3
Comparative Example 1 Si- (containing Bi) 520 68 Bad Bad 17.5 0.3
Comparative Example 2 B-, Si- (with Bi) 505 70 Bad Bad 17.5 0.3
Comparative Example 3 Pb-, Bi-, Zn- 454 48 Bad Bad 17.5 0.3
Comparative Example 4 Zn-, B- 480 74 Good Good 17.1 0.3
상기 표2 및, 도1 및 2에서 확인되는 바와 같이, 본 발명의 실시예1의 은 페이스트 조성물은 알루미늄 페이스트와의 중첩부위에서 수분과의 반응이 방지되어 기포가 발생되지 않았으며, 전극손상도 발견되지 않은 반면, 비교예1 내지 3의 은 페이스트 조성물은 알루미늄 페이스트와의 중첩부위에서 수분과의 반응이 일어나 기포가 발생되었으며, 전극손상도 관찰되었다. As shown in Table 2 and FIGS. 1 and 2, the silver paste composition of Example 1 of the present invention prevented a reaction from moisture at an overlapping portion with an aluminum paste, and thus did not generate bubbles. On the other hand, in the silver paste compositions of Comparative Examples 1 to 3, bubbles were generated due to reaction with moisture in the overlapping area with the aluminum paste, and electrode damage was also observed.
비교예 4의 은 페이스트 조성물의 경우, 알루미늄 페이스트와의 중첩부위에서 수분과의 반응이 방지되어 기포가 발생되지 않았으며, 전극손상도 발견되지 않았으나, 평균입경이 큰 은 입자를 사용함으로써 태양전지 효율의 저하가 관찰되었다.In the silver paste composition of Comparative Example 4, the reaction with water was prevented from overlapping with the aluminum paste to prevent bubbles, and electrode damage was not found, but the solar cell efficiency was obtained by using silver particles having a large average particle diameter. A decrease of was observed.

Claims (6)

  1. 조성물 총 중량에 대하여,Regarding the total weight of the composition,
    a) 입자의 평균입경(D50)이 0.3㎛ ~ 1.5㎛인 은 분말 65~75 중량%, a) 65 to 75% by weight of silver powder having an average particle diameter (D 50 ) of the particles of 0.3 μm to 1.5 μm,
    b) PbO 및 Bi2O3를 포함하지 않는 ZnO계 또는 V2O3계 글라스 프릿 0.01~10 중량%, 및b) 0.01 to 10% by weight of a ZnO-based or V 2 O 3 -based glass frit containing no PbO and Bi 2 O 3 , and
    c) 유기 비히클 용액 20~34.9 중량%를 포함하는 태양전지 후면 전극용 은 페이스트 조성물.c) A silver paste composition for solar cell back electrode comprising 20 to 34.9% by weight of an organic vehicle solution.
  2. 청구항 1에 있어서, 상기 은 입자의 최대 입경(Dmax)은 4.5㎛ 이하인 것을 특징으로 하는 태양전지 후면 전극용 은 페이스트 조성물.The silver paste composition of claim 1, wherein the maximum particle diameter (Dmax) of the silver particles is 4.5 µm or less.
  3. 청구항 1에 있어서, 상기 은 입자의 형태는 구형 또는 판상형인 것을 특징으로 하는 태양전지 후면 전극용 은 페이스트 조성물.The silver paste composition of claim 1, wherein the silver particles have a spherical shape or a plate shape.
  4. 청구항 1에 있어서, 상기 글라스 프릿은 ZnO 10~55mol%, V2O3 0~70mol%, B2O3 0~50mol%, 알칼리 토금속 산화물 1~10mol%, SiO2 0~35mol% 및 알칼리금속 산화물 1~10mol%를 포함하는 것을 특징으로 하는 태양전지 후면 전극용 은 페이스트 조성물.The method according to claim 1, wherein the glass frit is ZnO 10-55mol%, V 2 O 3 0-70mol%, B 2 O 3 0-50mol%, alkaline earth metal oxide 1-10mol%, SiO 2 0-35mol% and alkali metal Silver paste composition for a solar cell back electrode comprising 1 to 10 mol% oxide.
  5. 청구항 4에 있어서, 상기 글라스 프릿의 연화점은 350~600℃인 것을 특징으로 하는 태양전지 후면 전극용 은 페이스트 조성물.The silver paste composition of claim 4, wherein the softening point of the glass frit is 350 to 600 ° C.
  6. 청구항 1의 태양전지 후면 전극용 은 페이스트 조성물로 형성된 후면 전극을 포함하는 것을 특징으로 하는 태양전지.A solar cell comprising a back electrode formed of a silver paste composition for a solar cell back electrode of claim 1.
PCT/KR2011/007733 2011-10-18 2011-10-18 Silver paste composition (2) for the back electrode of a solar cell WO2013058418A1 (en)

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WO2016137059A1 (en) * 2015-02-27 2016-09-01 Dae Joo Electronic Materials Co., Ltd. Silver paste composition, front electrode for solar cell formed using it, and solar cell employing it

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Publication number Priority date Publication date Assignee Title
JP2006093433A (en) * 2004-09-24 2006-04-06 Sharp Corp Method of manufacturing solar cell
KR100837994B1 (en) * 2005-04-14 2008-06-13 이 아이 듀폰 디 네모아 앤드 캄파니 Conductive compositions and processes for use in the manufacture of semiconductor devices
KR20080099406A (en) * 2007-05-09 2008-11-13 주식회사 동진쎄미켐 A paste for producing electrode of solar cell
KR20110069724A (en) * 2009-12-17 2011-06-23 동우 화인켐 주식회사 Silver paste composition for back electrode of solar cell
KR20110121428A (en) * 2010-04-30 2011-11-07 동우 화인켐 주식회사 Silver paste composition for a back electrode of solar cell

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Publication number Priority date Publication date Assignee Title
JP2006093433A (en) * 2004-09-24 2006-04-06 Sharp Corp Method of manufacturing solar cell
KR100837994B1 (en) * 2005-04-14 2008-06-13 이 아이 듀폰 디 네모아 앤드 캄파니 Conductive compositions and processes for use in the manufacture of semiconductor devices
KR20080099406A (en) * 2007-05-09 2008-11-13 주식회사 동진쎄미켐 A paste for producing electrode of solar cell
KR20110069724A (en) * 2009-12-17 2011-06-23 동우 화인켐 주식회사 Silver paste composition for back electrode of solar cell
KR20110121428A (en) * 2010-04-30 2011-11-07 동우 화인켐 주식회사 Silver paste composition for a back electrode of solar cell

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016137059A1 (en) * 2015-02-27 2016-09-01 Dae Joo Electronic Materials Co., Ltd. Silver paste composition, front electrode for solar cell formed using it, and solar cell employing it

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