WO2012165167A1 - Solar cell and paste composition for forming aluminum electrode of solar cell - Google Patents
Solar cell and paste composition for forming aluminum electrode of solar cell Download PDFInfo
- Publication number
- WO2012165167A1 WO2012165167A1 PCT/JP2012/062687 JP2012062687W WO2012165167A1 WO 2012165167 A1 WO2012165167 A1 WO 2012165167A1 JP 2012062687 W JP2012062687 W JP 2012062687W WO 2012165167 A1 WO2012165167 A1 WO 2012165167A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- mol
- aluminum
- solar cell
- glass
- electrode
- Prior art date
Links
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 202
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 179
- 239000000203 mixture Substances 0.000 title claims abstract description 94
- 239000011521 glass Substances 0.000 claims abstract description 119
- 229910000272 alkali metal oxide Inorganic materials 0.000 claims abstract description 8
- 239000000758 substrate Substances 0.000 claims description 61
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 37
- 229910052710 silicon Inorganic materials 0.000 claims description 37
- 239000010703 silicon Substances 0.000 claims description 37
- 239000002313 adhesive film Substances 0.000 claims description 34
- 239000004065 semiconductor Substances 0.000 claims description 29
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 18
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 18
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 229910052708 sodium Inorganic materials 0.000 claims description 11
- 229910015902 Bi 2 O 3 Inorganic materials 0.000 claims description 6
- -1 B 2 O 3 Inorganic materials 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract 1
- 229910052681 coesite Inorganic materials 0.000 abstract 1
- 229910052593 corundum Inorganic materials 0.000 abstract 1
- 229910052906 cristobalite Inorganic materials 0.000 abstract 1
- 239000004615 ingredient Substances 0.000 abstract 1
- 239000000377 silicon dioxide Substances 0.000 abstract 1
- 229910052682 stishovite Inorganic materials 0.000 abstract 1
- 229910052905 tridymite Inorganic materials 0.000 abstract 1
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 1
- 239000000853 adhesive Substances 0.000 description 42
- 230000001070 adhesive effect Effects 0.000 description 42
- 239000002245 particle Substances 0.000 description 30
- 238000012360 testing method Methods 0.000 description 29
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 13
- 229910052709 silver Inorganic materials 0.000 description 13
- 239000004332 silver Substances 0.000 description 13
- 238000000576 coating method Methods 0.000 description 11
- 238000000034 method Methods 0.000 description 11
- 239000000843 powder Substances 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 9
- 238000011156 evaluation Methods 0.000 description 9
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 235000012431 wafers Nutrition 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000007650 screen-printing Methods 0.000 description 8
- 239000011734 sodium Substances 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- 229920005989 resin Polymers 0.000 description 7
- 239000011347 resin Substances 0.000 description 7
- 229910000679 solder Inorganic materials 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000010304 firing Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000007718 adhesive strength test Methods 0.000 description 4
- 229910021419 crystalline silicon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910000510 noble metal Inorganic materials 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- OAYXUHPQHDHDDZ-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethanol Chemical compound CCCCOCCOCCO OAYXUHPQHDHDDZ-UHFFFAOYSA-N 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229920001187 thermosetting polymer Polymers 0.000 description 3
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 3
- 229920000178 Acrylic resin Polymers 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 2
- 239000001856 Ethyl cellulose Substances 0.000 description 2
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 2
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical class OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 2
- 238000003618 dip coating Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229920001249 ethyl cellulose Polymers 0.000 description 2
- 235000019325 ethyl cellulose Nutrition 0.000 description 2
- 238000007561 laser diffraction method Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 229940116411 terpineol Drugs 0.000 description 2
- 230000000930 thermomechanical effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- VXQBJTKSVGFQOL-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethyl acetate Chemical compound CCCCOCCOCCOC(C)=O VXQBJTKSVGFQOL-UHFFFAOYSA-N 0.000 description 1
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910021364 Al-Si alloy Inorganic materials 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 206010037660 Pyrexia Diseases 0.000 description 1
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229920000180 alkyd Polymers 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000003667 anti-reflective effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- 239000004210 ether based solvent Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 238000007719 peel strength test Methods 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920006287 phenoxy resin Polymers 0.000 description 1
- 239000013034 phenoxy resin Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 1
- 229920006122 polyamide resin Polymers 0.000 description 1
- 229920005668 polycarbonate resin Polymers 0.000 description 1
- 239000004431 polycarbonate resin Substances 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
Classifications
-
- 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
-
- 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
-
- 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
-
- 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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
-
- 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 solar battery (cell) and a manufacturing method thereof, and to an aluminum electrode forming paste composition used in the manufacturing method. Note that this application claims priority based on Japanese Patent Application No. 2011-125062 filed on June 3, 2011, the entire contents of which are incorporated herein by reference. .
- a single-sided light receiving type solar cell as shown in FIG. 1000 is known (see, for example, Patent Documents 1 to 4).
- This solar cell 1000 includes an n-Si layer 116 formed by pn junction formation on the light-receiving surface side of a p-Si layer (p-type crystalline silicon) 118 of a silicon semiconductor substrate (Si wafer) 111, and on its surface.
- the back surface of the p-Si layer 118 (referred to as the surface opposite to the light receiving surface; hereinafter the same), it is made of Ag formed by screen printing / baking silver paste in the same manner as the surface electrode 112.
- a back surface side external connection electrode 122 and an aluminum electrode 120 having a so-called back surface field (BSF) effect are provided.
- the aluminum electrode 120 is formed on substantially the entire back surface by printing and baking a paste composition (hereinafter also referred to as “aluminum paste”) mainly composed of aluminum (Al) powder. During this firing, an Al—Si alloy layer (not shown) is formed, and aluminum diffuses into the p-Si layer 118 to form a p + layer 124.
- aluminum paste mainly composed of aluminum (Al) powder.
- an Ag surface electrode (light-receiving surface electrode) 112 for taking out current is formed on the light-receiving surface side, and recombination prevention of electrons is performed on the back-surface side.
- a BSF layer 124 is formed.
- the Ag surface electrode 112 and the aluminum electrode 120 for forming the BSF layer 124 are typically formed by a screen printing method, and are formed by simultaneously sintering both surfaces.
- a lead wire (lead frame: not shown) for current extraction is soldered to the solar cell wafer 1000 having the electrodes (112, 120, 122) formed on both surfaces in this way. Then, a plurality of solar cell wafers 1000 are connected in series using the lead wires to be modularized, and predetermined power can be supplied in such a modularized state.
- the Ag electrode 122 is formed on the soldered portion.
- the formation of the Ag electrode 122 hinders the uniformization of the BSF layer 124, and the formation of the Ag electrode 122 uses silver, which is a noble metal more expensive than aluminum, as the conductive component. It becomes a factor of.
- the present inventor uses a conductive adhesive film (that is, a film containing an adhesive and conductive particles) without using solder, and a method of thermocompression bonding of the lead wire was considering. Specifically, the connection is executed without using solder by thermally bonding the lead wire to the position of the external connection electrode 122 made of Al via a conductive adhesive film.
- this technique using a conductive adhesive film cannot provide sufficient adhesive strength on the electrode 122 made of aluminum. That is, as a result of examination by the present inventors, when the adhesive portion of the lead wire (conductive ribbon wire) through the conductive adhesive film is peeled off, peeling occurs in the aluminum film in the electrode 122 made of aluminum, which is sufficient. It was thought that this was the reason why it was not possible to obtain a sufficient adhesive strength. More specifically, it was found that the aluminum film itself in the electrode 122 made of aluminum has no strength, and the adhesive strength after firing between the aluminum particles forming the aluminum film is weak.
- the lead wire can be bonded on the aluminum electrode of the solar cell wafer, the advantage that the BSF layer 124 can be formed on the entire surface is obtained, and the use of silver is not necessary. A significant cost reduction corresponding to the price difference can be achieved.
- the present invention has been created in view of the above points, and one object of the present invention is to provide a paste composition for forming an aluminum electrode (particularly a backside external connection electrode) with improved adhesive strength. To do. Another object of the present invention is to provide a solar cell including an aluminum electrode (particularly a backside external connection electrode) formed using such a paste composition and a method for producing the solar cell.
- the paste composition provided by the present invention is a paste composition for forming an aluminum electrode of a solar cell.
- the paste composition for aluminum electrode formation of the solar cell disclosed here contains aluminum powder, glass frit, and an organic vehicle.
- the glass frit has the following conditions: (1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower; (2) The coefficient of thermal expansion is 60 ⁇ 10 ⁇ 7 / ° C. or more and 80 ⁇ 10 ⁇ 7 / ° C. or less; (3) Including SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one alkali metal oxide as essential components; It is characterized by comprising.
- the paste composition is applied to the silicon semiconductor substrate by having the glass frit (glass powder) having the properties described in (1) to (3) above.
- the adhesive strength of the formed aluminum electrode can be improved. Therefore, for example, it is possible to stably join an aluminum electrode (for example, a backside external connection electrode) formed from the paste composition and another connection member (for example, a conductive adhesive film including an adhesive and conductive particles). Can be maintained.
- the conductive component of the conventional electrode, for example, the external connection electrode from a noble metal such as silver with inexpensive aluminum, and to reduce the cost corresponding to the material price difference between silver and aluminum. Can be realized.
- the Ag electrode for external connection on the back side can be replaced with an aluminum electrode, the BSF layer can be formed uniformly on the entire back side of the silicon semiconductor substrate.
- the glass frit includes 100 mol% of the following components as a whole, and the molar content of each component is SiO 2 20-35 mol%, B 2 O 3 5-30 mol%, ZnO and / or PbO 25-45 mol%, Al 2 O 3 2-10 mol%, At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%, At least one of CaO, SrO and BaO 0-10 mol%, Bi 2 O 3 0-5 mol%, And the total of these components is 95 mol% or more (for example, 100 mol%) of the entire glass frit.
- the adhesive strength (peeling strength) of an aluminum electrode (for example, a backside external connection electrode) formed from the paste composition can be further improved.
- the glass frit has 100 mol% of the following components as a whole, and the molar content of each component is SiO 2 20-30 mol%, B 2 O 3 20-30 mol%, ZnO 25-35 mol%, Al 2 O 3 3-7 mol%, At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%, 2 to 10 mol% of at least one of CaO, SrO and BaO, And the total of these components is 95 mol% or more (for example, 100 mol%) of the entire glass frit.
- the adhesive strength (peeling strength) of an aluminum electrode such as a back-side external connection electrode formed from the paste composition can be further improved. Moreover, such high adhesive strength can be realized without Pb.
- the glass softening point of the glass frit is 500 ° C. or more and 600 ° C. or less.
- the total paste composition is 100% by mass
- the aluminum powder content is 60 to 80% by mass
- the above The glass frit content is 2 to 10% by mass.
- a solar cell comprising: At least a part of the aluminum electrode as a glass composition has the following conditions: (1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower; (2) The coefficient of thermal expansion is 60 ⁇ 10 ⁇ 7 / ° C. or more and 80 ⁇ 10 ⁇ 7 / ° C.
- the solar cell characterized by containing the glass composition which comprises can be provided.
- the solar cell having such a configuration can achieve high adhesive strength (peel strength) in an aluminum electrode containing the glass composition (glass component) having the above properties.
- the conductive component of the portion where the Ag electrode has been used in the past, for example, the external connection electrode can be replaced with inexpensive aluminum from noble metal such as silver. This makes it possible to reduce the manufacturing cost of the electrode (substitution from the Ag electrode to the aluminum electrode).
- the glass composition is composed of 100 mol% of the following components as a whole, and the molar content of each component is SiO 2 20-35 mol%, B 2 O 3 5-30 mol%, ZnO and / or PbO 25-45 mol%, Al 2 O 3 2-10 mol%, At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%, At least one of CaO, SrO and BaO 0-10 mol%, Bi 2 O 3 0-5 mol%, And the total of these components is 95 mol% or more (typically 100 mol%) of the entire glass composition.
- the glass composition has 100% by mole of the following components as a whole, and the molar content of each component is SiO 2 20 ⁇ 30mol%, B 2 O 3 20-30 mol%, ZnO 25-35 mol%, Al 2 O 3 3-7 mol%, At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%, 2 to 10 mol% of at least one of CaO, SrO and BaO, And the total of these components is 95 mol% or more (typically 100 mol%) of the entire glass composition.
- the glass softening point of the glass composition is 500 ° C. or higher and 600 ° C. or lower.
- an aluminum electrode having an adhesive strength (peel strength) equal to or higher than that of a conventional Ag electrode can be formed on the silicon semiconductor substrate as the external connection electrode.
- an external connection electrode is formed on the back surface side of the silicon semiconductor substrate, and the external connection electrode is formed by an aluminum electrode containing the glass composition. It is configured.
- a conductive adhesive film is affixed on an aluminum electrode containing the glass composition that constitutes the external connection electrode.
- the present invention provides, as another aspect for realizing the above object, a silicon semiconductor substrate, a light-receiving surface electrode formed on the light-receiving surface side that is one surface of the substrate, and the other surface of the substrate
- a method for producing a solar cell comprising an aluminum electrode formed on a back surface side is provided. That is, the solar cell manufacturing method disclosed herein is characterized in that at least a part of the aluminum electrode formed on the back surface side is formed using any paste composition provided by the present invention. .
- FIG. 1 is a cross-sectional view schematically showing an example of the structure of a solar cell 100 according to an embodiment of the present invention.
- 2A and 2B are a top view and a cross-sectional view schematically showing the configuration of the back surface side of the substrate 11 in the solar cell 100, respectively.
- FIG. 3 is a perspective view schematically showing a configuration in which the conductive adhesive film 30 is disposed on the external connection aluminum electrode 22 on the back surface side of the solar cell 100.
- 4A and 4B are cross-sectional views showing a structure in which a lead wire (tab wire) 35 is disposed on the external connection aluminum electrode 22 with a conductive adhesive film 30 interposed therebetween.
- FIG. 5 is a cross-sectional view schematically showing the configuration of the strength measuring apparatus 300 that performs the adhesive strength evaluation.
- FIG. 6 is a graph showing the relationship between the adhesive strength and the softening point of the glass frit.
- FIG. 7 is a cross-sectional view schematically showing an example of the structure of a conventional solar cell 1000.
- the aluminum electrode forming paste composition disclosed herein is an aluminum paste used for forming an aluminum electrode in a solar cell, and includes a paste form (expressed as ink form) containing aluminum powder, glass frit, and an organic vehicle.
- the aluminum powder refers to an aggregate of particles mainly composed of aluminum (Al), and is typically an aggregate of particles composed of Al alone.
- an impurity other than Al or an alloy mainly composed of Al is used.
- Even a trace amount may be included in the “aluminum powder” as long as it is an aggregate of particles mainly composed of aluminum as a whole.
- the aluminum powder itself may be produced by a conventionally known production method and does not require special production means.
- the particles constituting the aluminum powder to be used are typically spherical, but are not limited to the so-called spherical shape. It may contain flake shaped or irregular shaped particles.
- the aluminum powder used is preferably a powder having a relatively narrow particle size distribution (in other words, a uniform particle size).
- a powder having a relatively narrow particle size distribution in other words, a uniform particle size.
- the ratio (D10 / D90) of the particle size (D10) when the cumulative volume is 10% and the particle size (D90) when the cumulative volume is 90% in the particle size distribution based on the laser diffraction method can be adopted.
- the value of D10 / D90 is 1, and conversely, the value of D10 / D90 approaches 0 as the particle size distribution becomes wider.
- It is preferable to use a powder having a relatively narrow particle size distribution such that the value of D10 / D90 is 0.2 or more (for example, 0.2 to 0.5).
- the aluminum powder contained in the aluminum electrode forming paste composition disclosed herein suitably has an average particle size of 20 ⁇ m or less.
- an aluminum powder having an average particle size of about 1 ⁇ m to 10 ⁇ m can be preferably used.
- the average particle diameter refers to a particle diameter at a cumulative volume of 50% in the particle size distribution of the powder, that is, D50 (median diameter).
- D50 can be easily measured by a particle size distribution measuring apparatus based on a laser diffraction method.
- the content of aluminum powder is suitably about 55 to 85% by mass, more preferably 60 to 80% by mass, based on 100% by mass of the entire paste composition.
- an aluminum electrode having a higher density (for example, an aluminum electrode for external connection having a film thickness of 100 ⁇ m or less, for example, a film thickness of 10 ⁇ m to 100 ⁇ m) is suitable on a silicon semiconductor substrate. Can be formed.
- glass frit is an inorganic additive that improves the adhesive strength of the aluminum electrode.
- the glass frit in the paste composition (aluminum paste) provided by the present invention, the glass frit has the above-mentioned conditions (1) to (3), so that the formed aluminum electrode has high adhesive strength (peel strength). Can be granted. That is, the glass frit (glass composition) contained in the aluminum electrode forming paste composition disclosed herein has, for example, a thermal expansion coefficient (linear thermal expansion coefficient) of 60 ⁇ 10 ⁇ 7 / ° C. or more and 80 ⁇ 10 8. Those having ⁇ 7 / ° C.
- thermal expansion coefficient is a temperature measured by a thermomechanical analyzer (TMA) based on a general differential expansion method (TMA) to a temperature below the glass softening point (for example, 400 ° C. or 500 ° C. Calculated as an average value during (° C).
- TMA thermomechanical analyzer
- TMA general differential expansion method
- the glass frit contained in the aluminum electrode forming paste composition disclosed herein is calculated by a glass softening point (measured by a general thermomechanical analyzer (TMA) in the same manner as the thermal expansion coefficient).
- TMA thermomechanical analyzer
- a glass softening point) of 400 ° C. or higher and 600 ° C. or lower is suitable.
- a glass softening point of 500 ° C. or more and 600 ° C. or less is particularly preferable.
- glass frit As a glass frit (glass composition) having the preferred thermal expansion coefficient and glass softening point, SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one kind It is preferable to include an alkali metal oxide (for example, selected from Li 2 O, Na 2 O, and K 2 O) as an essential component.
- an alkali metal oxide for example, selected from Li 2 O, Na 2 O, and K 2 O
- the glass frit (glass composition) contained in the aluminum electrode forming paste composition disclosed herein the following components as a whole are assumed to be 100 mol%, and the molar content of each component is: SiO 2 20-35 mol%, B 2 O 3 5-30 mol%, ZnO and / or PbO 25-45 mol%, Al 2 O 3 2-10 mol%, At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%, At least one of CaO, SrO and BaO 0-10 mol%, Bi 2 O 3 0-5 mol%, The total of these components is 95 mol% or more (typically 100 mol%) of the entire glass frit (glass composition).
- a glass frit having a particularly preferable composition 100 mol of all the following components are contained. %, The molar content of each component is SiO 2 20-30 mol%, B 2 O 3 20-30 mol%, ZnO 25-35 mol%, Al 2 O 3 3-7 mol%, At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%, 2 to 10 mol% of at least one of CaO, SrO and BaO, The total of these components is 95 mol% or more (typically 100 mol%) of the entire glass frit (glass composition).
- the adhesive strength (peel strength) of the aluminum electrode to be formed can be further improved.
- SiO 2 which is an essential component is a main component constituting a glass skeleton. If the SiO 2 content is too high, the glass softening point becomes too high, which is not preferable. On the other hand, if the SiO 2 content is too low, the chemical resistance and water resistance decrease, which is not preferable.
- B 2 O 3 is a component having a high effect of lowering the softening point and the melting temperature of the glass frit. If the B 2 O 3 content is too low, the effect of lowering the softening point and melting temperature of the glass cannot be obtained.
- ZnO or PbO is a component that can lower the softening point of the glass frit (glass composition) or adjust the thermal expansion coefficient, and any one or both of ZnO and PbO can be used. It is preferable to contain in the range of the said content rate. If the content of these components is too high, the glass softening point is too low, which is not preferable. A PbO free material is preferred.
- Al 2 O 3 is a component that controls the fluidity of the glass frit during melting and is involved in the adhesion stability during the formation of the aluminum electrode. If the Al 2 O 3 content is too low, the adhesion stability is lowered, which is not preferred. If the Al 2 O 3 content is too high, the chemical resistance of the glass may be lowered, which is not preferred. Further, alkali metal oxide components such as Li 2 O, Na 2 O, K 2 O is a component to increase the thermal expansion coefficient. If the content of these alkali metal oxide components is too low, the thermal expansion coefficient may be too low. On the other hand, if the content is too high, the thermal expansion coefficient becomes excessively high, which is not preferable.
- alkali metal oxide components such as Li 2 O, Na 2 O, K 2 O is a component to increase the thermal expansion coefficient. If the content of these alkali metal oxide components is too low, the thermal expansion coefficient may be too low. On the other hand, if the content is too high, the thermal expansion coefficient becomes excessively high, which is not
- the glass frit can contain an arbitrary component in addition to the essential components described above.
- an alkaline earth metal oxide component such as CaO, SrO, or BaO at a content of 10 mol% or less.
- the thermal expansion coefficient can be adjusted more easily, and the chemical resistance, etc. can be improved by diversifying the glass composition (multiple types of constituent metal elements). Is preferable because it can improve the stability of the glass.
- an alkaline earth metal oxide component such as CaO, SrO, or BaO at a content of, for example, 1 mol% to 10 mol% (eg, 2 to 10 mol%, particularly 5 to 10 mol%).
- Bi 2 O 3 may be contained in an appropriate amount, for example, in a proportion of 10 mol% or less (preferably 5 mol% or less) for the purpose of improving the stability of the fired glass (and thus the fired aluminum electrode). Good.
- other oxide components such as Zr, Ti, V, Nb, La, Ce, Sn, and P are appropriately included at a ratio of 5 mol% or less (for example, about 0.1 to 5 mol%) of the entire glass composition. Also good.
- the glass frit contained in the paste composition is a ratio based on the BET method. Those having a surface area of about 0.5 m 2 / g or more and 50 m 2 / g or less are preferred, and those having an average particle diameter (D50) of 2 ⁇ m or less (particularly about 1 ⁇ m or less) are preferred. Further, the content of the glass powder in the paste composition is not particularly limited, but it is suitably about 1 to 15% by mass, and about 2 to 10% by mass with respect to 100% by mass of the entire paste composition. preferable. According to the paste composition containing the glass frit having the above elemental composition with such a content, an aluminum electrode having high adhesive strength (for example, an aluminum electrode for external connection on the back surface side) can be suitably formed.
- the paste composition disclosed here includes the above-described aluminum powder and glass frit (glass powder) as a solid content, and a liquid medium (organic vehicle) for dispersing the solid content.
- the organic solvent constituting such a vehicle is not particularly limited as long as it can disperse aluminum powder and glass frit satisfactorily, and those used in conventional pastes of this type can be used without particular limitation.
- high boiling point organic solvents such as ethylene glycol and diethylene glycol derivatives (glycol ether solvents), toluene, xylene, butyl carbitol (BC), butyl diglycol acetate (BDGA), terpineol and the like are used. It can be used in combination of multiple types.
- various resin components can be included as an organic binder constituting the vehicle. Any resin component may be used as long as it can provide the paste composition disclosed herein with good viscosity and coating film forming ability (adhesion to a silicon substrate), and is used in conventional pastes of this type. Things can be used without particular limitation. Examples thereof include those mainly composed of acrylic resin, epoxy resin, phenol resin, alkyd resin, cellulosic polymer, polyvinyl alcohol, rosin resin and the like. Among these, cellulosic polymers such as ethyl cellulose are particularly preferable. Although there is no particular limitation, the organic vehicle content is suitably about 10 to 30% by mass of the total paste, and more preferably about 15 to 25% by mass.
- the paste composition disclosed herein is typically easily prepared by mixing aluminum powder, glass frit (glass powder), and a suitable organic vehicle. Can do.
- a three-roll mill or other kneader may be used to mix and stir a predetermined mixing ratio of aluminum powder and glass frit together with an organic vehicle at a predetermined mixing ratio.
- the paste composition disclosed here can be handled in the same manner as an aluminum paste conventionally used to form an aluminum electrode (and thus a p + layer or BSF layer) as a back electrode on a substrate, A conventionally known method can be employed without any particular limitation.
- the paste composition is applied (applied) to a silicon semiconductor substrate by a screen printing method, a dispenser coating method, a dip coating method, or the like so as to obtain a desired film thickness or coating film pattern.
- the thickness of the substrate can be set in consideration of the desired solar cell size, the thickness of the aluminum electrode formed on the substrate, the strength (for example, the breaking strength) of the substrate, and the like.
- the paste coating product is dried at an appropriate temperature (for example, room temperature or higher, typically about 100 ° C.).
- the dried coating film is baked by heating in an appropriate baking furnace (for example, a high-speed baking furnace) under appropriate heating conditions (for example, 600 ° C. to 900 ° C., preferably 700 ° C. to 800 ° C.) for a predetermined time. I do.
- an appropriate baking furnace for example, a high-speed baking furnace
- appropriate heating conditions for example, 600 ° C. to 900 ° C., preferably 700 ° C. to 800 ° C.
- FIG. 1 is a cross-sectional view showing a configuration of a solar cell 100 according to an embodiment of the present invention.
- the solar cell 100 of this embodiment includes a silicon semiconductor substrate (Si wafer) 11, a light receiving surface electrode 12 formed on one surface side (front surface side) of the substrate 11, and the other surface side (back surface side) of the substrate 11. ) Formed on the aluminum electrode (20, 22).
- the silicon semiconductor substrate 11 of this embodiment is made of silicon such as crystalline silicon or amorphous silicon.
- the n-Si layer 16 formed by pn junction formation is located on the light receiving surface side of the p-Si layer (p-type crystalline silicon) 18 of the substrate 11.
- An antireflection film 14 made of titanium oxide or silicon nitride formed by general chemical vapor deposition (CVD) or the like is located on the surface of the n-Si layer 16.
- the surface of the antireflection film 14 is provided with a surface electrode (light receiving surface electrode) 12 made of Ag, typically formed by screen printing and baking a silver paste.
- an aluminum electrode forming paste composition disclosed herein (hereinafter sometimes referred to as “first aluminum paste” for convenience) is formed on the back side of the p-Si layer 18 as a material.
- An aluminum electrode 22 is provided.
- the aluminum electrode 22 corresponds to the external connection electrode 22 on the back surface side that is electrically connected to another external connection member such as a lead wire (conductive ribbon line).
- the external connection aluminum electrode 22 of this embodiment is a first aluminum having a predetermined composition as in the case of forming this type of conventional electrode (for example, forming an external connection Ag electrode using a silver paste as a material). It is formed by screen printing and baking the paste.
- an aluminum electrode 20 made of another aluminum paste (hereinafter sometimes referred to as “second aluminum paste” for convenience) is formed together with the external connection aluminum electrode 22.
- the aluminum electrode 20 is formed on substantially the entire back surface of the p-Si layer 18 and is an aluminum electrode (hereinafter referred to as “back surface wide aluminum electrode”) that exhibits a back surface field (BSF) effect.
- the external connection aluminum electrode 22 is linearly formed on the back surface side of the p-Si layer 18, and the back surface wide aluminum electrode 20 is formed on the back surface side of the p-Si layer 18.
- the external connection aluminum electrode 22 is formed on substantially the entire surface other than the region where the external connection aluminum electrode 22 is formed.
- the back surface wide aluminum electrode 20 covers a part of the external connection aluminum electrode 22 (specifically, both edges of the linear structure) and the external connection aluminum electrode 22 It is formed to have an opening 23 that is exposed.
- the back surface wide aluminum electrode 20 covers both edges of the external connection aluminum electrode 22, and the both sides are formed so that the side surface of the back surface wide aluminum electrode 20 and the side surface of the external connection aluminum electrode 22 are in contact with each other.
- the back surface wide aluminum electrode 20 may be a general aluminum paste used for forming an aluminum electrode of a conventional solar cell, including aluminum powder, glass frit, and an organic vehicle. The content is not particularly limited. Therefore, the detailed description is omitted because it does not characterize the present invention.
- the first aluminum paste is applied to the silicon semiconductor substrate (wafer) 11 by a screen printing method, a dispenser coating method, a dip coating method, or the like so as to obtain a desired thickness or coating film pattern.
- the coated material is dried at an appropriate temperature (room temperature to about 100 ° C.).
- a second aluminum paste is applied to the silicon semiconductor substrate 11 so that the opening 23 exposing the external connection aluminum electrode 22 is formed.
- the coated material is dried at an appropriate temperature (room temperature to about 100 ° C.). Thereafter, the dried coating film is baked by heating in an appropriate baking furnace (for example, a high-speed baking furnace) under appropriate heating conditions (for example, 700 to 800 ° C.) for a predetermined time.
- an appropriate baking furnace for example, a high-speed baking furnace
- the coated material is baked on the substrate, and the external connection aluminum electrode 22 and the back surface wide aluminum electrode 20 as shown in FIG. 1 are formed.
- the external connection aluminum electrode 22 and the back surface wide aluminum electrode 20 are fired, and the p + layer (BSF layer) 24 can be formed.
- 2A and 2B are a top view and a cross-sectional view schematically showing the configuration of the back surface side of the substrate 11 of the silicon-based solar cell 100 of the present embodiment. 2 (a) and 2 (b), the back side of the substrate 11 is shown as being positioned upward for convenience.
- the external connection aluminum electrode 22 is formed at a position where the back side external connection electrode (Ag electrode) 122 is located.
- the external connection aluminum electrode 22 can function as, for example, an electrode having a width of 2 to 6 mm. In general, it is difficult to join aluminum and solder.
- the conductive adhesive film 30 is attached so as to be crimped to the external connection aluminum electrode 22 (see FIG. 3 described later).
- the conductive adhesive film 30 (FIG. 3) is typically an anisotropic conductive adhesive film.
- an adhesive component epoxy resin, phenoxy resin, acrylic resin, polyimide resin, polyamide resin, polycarbonate resin are used. Other thermosetting resins and thermoplastic resins can be used.
- various conductive particles are dispersed in the resin (adhesive) component, and the conductive adhesive film 30 is By heating and pressurizing, the conductive adhesive film 30 can be affixed to a predetermined site, and conduction can be ensured by the conductive particles.
- conductive adhesive film 30 there is no restriction
- the electroconductive adhesive film of this kind of application marketed can be employ
- FIG. 3 is a perspective view schematically showing a configuration in which the conductive adhesive film 30 as described above is disposed on the external connection aluminum electrode 22 on the back surface side of the solar cell 100.
- the conductive adhesive film 30 is disposed on the surface of the external connection aluminum electrode 22, and the lead wire, that is, the tab wire (conductive ribbon wire) 35 is disposed on the surface of the conductive adhesive film 30. It will be.
- FIG. 4A and 4B show a cross-sectional structure in which the tab wire 35 is disposed on the external connection aluminum electrode (bus bar electrode) 22 with the conductive adhesive film 30 interposed therebetween.
- a conductive adhesive film 30 is laminated on the external connection aluminum electrode 22 formed on the substrate 11, and a tab wire 35 is formed on the conductive adhesive film 30. Laminate.
- the conductive adhesive film 30 has a configuration in which conductive particles 31 (for example, nickel particles plated with gold) are uniformly dispersed in an adhesive component 32 made of, for example, an epoxy thermosetting resin.
- the laminate of the external connection aluminum electrode 22, the conductive adhesive film 30, and the tab wire 35 is pressed and heated using the conductive adhesive film 30 as a tab wire bonding material.
- the conductive particles 31 in the conductive adhesive film 30 conduct the external connection aluminum electrode 22 and the tab wire 35 (see arrow 55).
- the adhesive component (here, thermosetting resin) 32 in the conductive adhesive film 30 is thermally cured, whereby reliable conduction equivalent to solder bonding can be realized.
- soldering the tab wire 35 it is necessary to apply a high temperature of 200 ° C. or higher, but in the bonding using the conductive adhesive film 30, low-temperature bonding at about 180 ° C. can be performed. Therefore, the influence (for example, generation
- the external connection aluminum electrode 22 composed of the first aluminum paste and the back surface wide aluminum electrode 20 composed of the second aluminum paste are used as the back surface aluminum electrodes, but the present invention is not limited thereto.
- all the back surface aluminum electrodes including the back surface wide aluminum electrode 20 can be formed by the first aluminum paste.
- test examples relating to the present invention will be described, but the present invention is not intended to be limited to those shown in the test examples.
- the difference in adhesive strength was evaluated when the properties of the glass frit which is a solid component of the aluminum electrode forming paste composition (aluminum paste) were made different from each other.
- a total of 8 types of glass samples (sample 1 to sample 8) having the glass composition (mol%), the glass softening point (° C.) and the thermal expansion coefficient (thermal expansion coefficient) shown in Table 1 below were used. .
- Example 1 a total of 8 types of aluminum pastes (Test Examples 1 to 8) each containing the glass frit (Samples 1 to 8) shown in Table 1 were prepared.
- the aluminum paste according to each test example was different only in the properties of the glass frit described above, and other components (aluminum powder, organic vehicle) and mixing ratio were the same. That is, the contents of the aluminum paste of each test example are as follows. (1) Aluminum powder: Aluminum powder having an average particle size of 6 ⁇ m was used in an amount of 66% by mass of the entire paste. (2) Organic vehicle: As an organic solvent, terpineol was used in an amount of 26% by mass based on the entire paste.
- ethyl cellulose was used in an amount of about 2% by mass of the entire paste.
- Glass frit The glass frit having the property of any of the above samples 1 to 8 was used in an amount of 6% by mass of the entire paste.
- an n-Si layer having a thickness of about 0.5 ⁇ m is formed on the light-receiving surface of the silicon substrate by applying a phosphorus-containing solution to the light-receiving surface of the silicon substrate on which the texture structure is formed by the etching process and performing heat treatment. (N + layer) was formed.
- an antireflection film titanium oxide film having a thickness of about 50 nm to 100 nm was formed on the n-Si layer by plasma CVD (PECVD).
- a coating film (thickness of 20 ⁇ m or more and 50 ⁇ m or less) to be a surface electrode (Ag electrode) was formed on the antireflection film by a screen printing method using a predetermined silver paste for forming a surface electrode (Ag electrode).
- the paste composition of any of the above Test Examples 1 to 8 was printed (applied) by screen printing (using stainless steel screen mesh SUS # 165).
- a coating film having a thickness of about 30 ⁇ m was formed in a line shape with a width of about 5 mm.
- this substrate was baked to form a linear aluminum electrode 28 for test evaluation. Specifically, firing was performed at a firing temperature of about 700 ° C.
- the adhesion strength of the aluminum electrode formed from the paste composition for forming an aluminum electrode according to each test example was measured by performing an adhesion strength evaluation test using the test evaluation cell (solar cell) thus obtained.
- peel strength evaluation Evaluation of the adhesive strength (peel strength) of the formed aluminum electrode (that is, peel strength evaluation) was performed using a strength measuring device 300 as shown in FIG. Specifically, the strength measuring apparatus 300 shown in FIG. 5 fixes a glass substrate 41 on a fixing jig 40 via a fixing screw 43 and a locking plate 44, and an epoxy adhesive on the glass substrate 41. The light-receiving surface side of the test silicon semiconductor substrate 11 obtained above was fixed by 42. A conductive adhesive film 30, which is a commercial product, is attached to the formed aluminum electrode 28 on the exposed surface side of the silicon semiconductor substrate 11 fixed on the glass substrate 41 in this way by thermocompression bonding, and on the conductive adhesive film 30. Further, a tab line 35 was pasted. Then, as shown in FIG.
- the strength measuring device 300 is inclined so that the bottom surface of the fixing jig 40 is 135 °, and the extension portion 35e formed in advance on the tab wire 35 is pulled upward in the vertical direction. (See arrow 45), the adhesive strength of tab wire 35 / conductive adhesive film 30 / electrode 28 was measured.
- the results are shown in the corresponding column of Table 2.
- the adhesive strength evaluation test peel strength test
- the adhesive strength evaluation test is performed on a plurality of (two) aluminum electrodes formed from the aluminum paste according to each test example, and the average of the test results (measured values) for the two aluminum electrodes.
- the graph of FIG. 6 has shown the relationship between the adhesive strength obtained by this test, and the softening point of the glass frit in an aluminum paste.
- the glass softening point in the aluminum paste exhibited high adhesive strength in the range of 400 ° C. to 600 ° C. (particularly 500 ° C. to 600 ° C.).
- the aluminum paste of Test Example 6 having a glass softening point around 550 ° C. was used, extremely high adhesive strength was observed.
- the glass frit has a high thermal expansion coefficient of 60 ⁇ 10 ⁇ 7 / ° C. to 80 ⁇ 10 ⁇ 7 / ° C. (especially 65 ⁇ 10 ⁇ 7 / ° C. to 75 ⁇ 10 ⁇ 7 / ° C.). It was observed to show adhesive strength.
- ⁇ Adhesive strength test (2)> Further, a linear aluminum electrode having a film thickness of about 30 ⁇ m and a width of about 2 mm is formed on the silicon semiconductor substrate 11 by using the aluminum paste according to Test Example 6 according to the same procedure as the above-described adhesive strength test (1). When the same peel strength evaluation test was conducted, an average value (n 2) of an adhesive strength of 3.25 N / 2 mm was observed as shown in the Example column of Table 3. As a comparative control, a linear Ag electrode having a film thickness of about 30 ⁇ m and a width of about 2 mm is formed on the silicon semiconductor substrate 11 using a normal silver paste instead of the aluminum paste according to Test Example 6, and solder is formed on the surface thereof.
- Comparative Example B in Table 3 is a result when the aluminum paste according to Test Example 1 is used instead of the aluminum paste according to Test Example 6.
- an aluminum electrode can be employed as the backside external connection electrode.
- the BSF layer can be uniformly formed on the entire back surface of the silicon semiconductor substrate (wafer) as compared with the conventional configuration in which the Ag electrode is used as the back surface side external connection electrode.
- cost reduction corresponding to the material price difference between silver and aluminum can be achieved.
- the bonding using the conductive adhesive film can be used by the aluminum electrode for external connection with improved adhesion strength (peeling strength) of the aluminum film, a pattern not including the electrode portion for solder bonding can be used. Can be built. As a result, the aluminization of the entire back surface of the substrate (wafer) improves the power generation efficiency of the solar cell due to the uniform formation of the BSF layer, and improves the power generation efficiency of the solar cell due to omitting the bus bar electrode pattern. Can be realized.
- a light-receiving surface electrode (For example, the bus-bar electrode which comprises a light-receiving surface electrode, or a grid line) using the paste composition for aluminum electrode formation disclosed here.
- Silicon semiconductor substrate Silicon semiconductor substrate (Si wafer) 12 Light-receiving surface electrode 14 Antireflection film 16 n-Si layer 18 p-Si layer 20 Back surface wide-area aluminum electrode 22 Aluminum electrode 23 for external connection Opening 24 BSF layer 30 Conductive adhesive film 31 Conductive particles 32 Adhesive component 35 Tab Wire (lead wire) 35e Tab extension 40 Fixing jig 41 Glass substrate 100, 200, 1000 Solar cell 300 Strength measuring device
Abstract
Description
なお、本出願は2011年6月3日に出願された日本国特許出願2011-125062号に基づく優先権を主張しており、その出願の全内容は本明細書中に参照として組み入れられている。 The present invention relates to a solar battery (cell) and a manufacturing method thereof, and to an aluminum electrode forming paste composition used in the manufacturing method.
Note that this application claims priority based on Japanese Patent Application No. 2011-125062 filed on June 3, 2011, the entire contents of which are incorporated herein by reference. .
この太陽電池1000は、シリコン半導体基板(Siウエハ)111のp-Si層(p型結晶シリコン)118の受光面側にpn接合形成により形成されたn-Si層116を備え、その表面にはCVD等により形成された酸化チタンや窒化シリコンから成る反射防止膜114と、典型的には銀(Ag)粉末を主体とするペースト組成物(以下「銀ペースト」ともいう。)をスクリーン印刷し焼成することによって形成されるAgから成る表面電極(受光面電極)112とを備える。
一方、p-Si層118の裏面(受光面の反対側の面をいう。以下同じ。)側には、表面電極112と同様に銀ペーストをスクリーン印刷・焼成することによって形成されるAgから成る裏面側外部接続用電極122と、いわゆる裏面電界(BSF;Back Surface Field)効果を奏するアルミニウム電極120とを備える。 Conventionally, as a typical example of a solar cell mainly composed of silicon (semiconductor substrate) such as crystalline silicon and amorphous silicon (hereinafter also referred to as “silicon-based solar cell”), a single-sided light receiving type solar cell as shown in FIG. 1000 is known (see, for example, Patent Documents 1 to 4).
This
On the other hand, on the back surface of the p-Si layer 118 (referred to as the surface opposite to the light receiving surface; hereinafter the same), it is made of Ag formed by screen printing / baking silver paste in the same manner as the
また、このように両面に電極(112、120、122)が形成された太陽電池ウェハ1000には、電流取出し用のリード線(リードフレーム:不図示)が半田付けされる。そして、そのリード線を用いて太陽電池ウェハ1000を複数枚直列接続することによってモジュール化し、そのようにモジュール化した状態で所定の電力が供給可能となる。 As shown in FIG. 7, in the conventional silicon-based
Moreover, a lead wire (lead frame: not shown) for current extraction is soldered to the
しかしながら、この導電性接着フィルムを用いる手法では、アルミニウムからなる電極122上において十分な接着強度を得ることができないことが判明した。すなわち、本発明者が検討したところ、導電性接着フィルムを介したリード線(導電リボン線)の接着部分を引き剥がすと、アルミニウムからなる電極122におけるアルミニウム膜内で剥離が生じており、これが十分な接着強度を得ることができない原因であると考えた。さらに述べると、アルミニウムからなる電極122におけるアルミニウム膜内そのものに強度がなく、アルミニウム膜を形成しているアルミニウム粒子間同士の焼成後の接着強度が弱いことが原因であることを見出した。 In an attempt to cover the entire back surface with an aluminum electrode, the present inventor uses a conductive adhesive film (that is, a film containing an adhesive and conductive particles) without using solder, and a method of thermocompression bonding of the lead wire Was considering. Specifically, the connection is executed without using solder by thermally bonding the lead wire to the position of the
However, it has been found that this technique using a conductive adhesive film cannot provide sufficient adhesive strength on the
そして、ここで開示される太陽電池のアルミニウム電極形成用ペースト組成物は、アルミニウム粉末と、ガラスフリットと、有機ビヒクルとを含む。そして、ガラスフリットは、以下の条件:
(1)ガラス軟化点が400℃以上600℃以下である;
(2)熱膨張係数が60×10-7/℃以上80×10-7/℃以下である;
(3)SiO2と、B2O3と、ZnO及び/又はPbOと、Al2O3と、少なくとも一種のアルカリ金属酸化物とを必須構成成分として含む;
を具備することを特徴とする。 The paste composition provided by the present invention (that is, a composition prepared in a paste form) is a paste composition for forming an aluminum electrode of a solar cell.
And the paste composition for aluminum electrode formation of the solar cell disclosed here contains aluminum powder, glass frit, and an organic vehicle. And the glass frit has the following conditions:
(1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower;
(2) The coefficient of thermal expansion is 60 × 10 −7 / ° C. or more and 80 × 10 −7 / ° C. or less;
(3) Including SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one alkali metal oxide as essential components;
It is characterized by comprising.
SiO2 20~35mol%、
B2O3 5~30mol%、
ZnO及び/又はPbO 25~45mol%、
Al2O3 2~10mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 5~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 0~10mol%、
Bi2O3 0~5mol%、
であり、それら成分の合計が該ガラスフリット全体の95mol%以上(例えば100mol%)であることを特徴とする。
このような組成のガラスフリットを採用することによって、当該ペースト組成物から形成されたアルミニウム電極(例えば裏面側外部接続用電極)の接着強度(剥離強度)をより向上させることができる。 In a preferred embodiment of the paste composition (aluminum paste) disclosed herein, the glass frit includes 100 mol% of the following components as a whole, and the molar content of each component is
SiO 2 20-35 mol%,
B 2 O 3 5-30 mol%,
ZnO and / or PbO 25-45 mol%,
Al 2 O 3 2-10 mol%,
At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%,
At least one of CaO, SrO and BaO 0-10 mol%,
Bi 2 O 3 0-5 mol%,
And the total of these components is 95 mol% or more (for example, 100 mol%) of the entire glass frit.
By employing the glass frit having such a composition, the adhesive strength (peeling strength) of an aluminum electrode (for example, a backside external connection electrode) formed from the paste composition can be further improved.
SiO2 20~30mol%、
B2O3 20~30mol%、
ZnO 25~35mol%、
Al2O3 3~7mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 10~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 2~10mol%、
であり、それら成分の合計が該ガラスフリット全体の95mol%以上(例えば100mol%)であることを特徴とする。
このような組成のガラスフリットを採用することによって、当該ペースト組成物から形成された裏面側外部接続用電極等のアルミニウム電極の接着強度(剥離強度)をよりいっそう向上させることができる。また、そのような高い接着強度をPbフリーにて実現することができる。 In a further preferred embodiment of the paste composition (aluminum paste) disclosed herein, the glass frit has 100 mol% of the following components as a whole, and the molar content of each component is
SiO 2 20-30 mol%,
B 2 O 3 20-30 mol%,
ZnO 25-35 mol%,
Al 2 O 3 3-7 mol%,
At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%,
2 to 10 mol% of at least one of CaO, SrO and BaO,
And the total of these components is 95 mol% or more (for example, 100 mol%) of the entire glass frit.
By employing the glass frit having such a composition, the adhesive strength (peeling strength) of an aluminum electrode such as a back-side external connection electrode formed from the paste composition can be further improved. Moreover, such high adhesive strength can be realized without Pb.
従って、本発明によると、シリコン半導体基板と、該基板の一方の面である受光面側に形成される受光面電極と、該基板の他方の面である裏面側に形成されるアルミニウム電極とを備える太陽電池であって、
上記アルミニウム電極の少なくとも一部は、ガラス組成物として、以下の条件:
(1)ガラス軟化点が400℃以上600℃以下である;
(2)熱膨張係数が60×10-7/℃以上80×10-7/℃以下である;
(3)SiO2と、B2O3と、ZnO及び/又はPbOと、Al2O3と、少なくとも一種のアルカリ金属酸化物とを必須構成成分として含む;
を具備するガラス組成物を含有することを特徴とする太陽電池を提供することができる。
かかる構成の太陽電池は、上記性状のガラス組成物(ガラス成分)を含むアルミニウム電極において高い接着強度(剥離強度)を実現することができる。このため、ここで開示される太陽電池(シリコン系太陽電池)では、従来はAg電極を使用していた部位、例えば外部接続用電極の導電成分を銀等の貴金属から安価なアルミニウムに置き換えることが可能となり、電極の製造コストの低減(Ag電極からアルミニウム電極への置換)を実現することができる。
また、本発明によると、裏面側外部接続用のAg電極がアルミニウム電極に置換されたシリコン半導体基板の裏面側の全面にBSF層が形成された太陽電池を提供することができる。 As described above, by using any of the paste compositions (aluminum paste) disclosed herein, an aluminum electrode having high adhesive strength can be formed on the silicon semiconductor substrate.
Therefore, according to the present invention, a silicon semiconductor substrate, a light receiving surface electrode formed on the light receiving surface side which is one surface of the substrate, and an aluminum electrode formed on the back surface side which is the other surface of the substrate are provided. A solar cell comprising:
At least a part of the aluminum electrode as a glass composition has the following conditions:
(1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower;
(2) The coefficient of thermal expansion is 60 × 10 −7 / ° C. or more and 80 × 10 −7 / ° C. or less;
(3) Including SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one alkali metal oxide as essential components;
The solar cell characterized by containing the glass composition which comprises can be provided.
The solar cell having such a configuration can achieve high adhesive strength (peel strength) in an aluminum electrode containing the glass composition (glass component) having the above properties. For this reason, in the solar cell (silicon-based solar cell) disclosed here, the conductive component of the portion where the Ag electrode has been used in the past, for example, the external connection electrode, can be replaced with inexpensive aluminum from noble metal such as silver. This makes it possible to reduce the manufacturing cost of the electrode (substitution from the Ag electrode to the aluminum electrode).
In addition, according to the present invention, it is possible to provide a solar cell in which a BSF layer is formed on the entire back surface side of a silicon semiconductor substrate in which an Ag electrode for back side external connection is replaced with an aluminum electrode.
SiO2 20~35mol%、
B2O3 5~30mol%、
ZnO及び/又はPbO 25~45mol%、
Al2O3 2~10mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 5~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 0~10mol%、
Bi2O3 0~5mol%、
であり、それら成分の合計が該ガラス組成物全体の95mol%以上(典型的には100mol%)であることを特徴とする。 In a preferred embodiment of the solar cell disclosed herein, the glass composition is composed of 100 mol% of the following components as a whole, and the molar content of each component is
SiO 2 20-35 mol%,
B 2 O 3 5-30 mol%,
ZnO and / or PbO 25-45 mol%,
Al 2 O 3 2-10 mol%,
At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%,
At least one of CaO, SrO and BaO 0-10 mol%,
Bi 2 O 3 0-5 mol%,
And the total of these components is 95 mol% or more (typically 100 mol%) of the entire glass composition.
SiO2 20~30mol%、
B2O3 20~30mol%、
ZnO 25~35mol%、
Al2O3 3~7mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 10~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 2~10mol%、
であり、それら成分の合計が該ガラス組成物全体の95mol%以上(典型的には100mol%)であることを特徴とする。
また、好ましくは、上記ガラス組成物のガラス軟化点は500℃以上600℃以下である。 Further, preferably, the glass composition has 100% by mole of the following components as a whole, and the molar content of each component is
SiO 2 20 ~ 30mol%,
B 2 O 3 20-30 mol%,
ZnO 25-35 mol%,
Al 2 O 3 3-7 mol%,
At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%,
2 to 10 mol% of at least one of CaO, SrO and BaO,
And the total of these components is 95 mol% or more (typically 100 mol%) of the entire glass composition.
Preferably, the glass softening point of the glass composition is 500 ° C. or higher and 600 ° C. or lower.
従って、ここで開示される太陽電池として特に好ましい一態様は、シリコン半導体基板の裏面側に外部接続用電極が形成されており、ここで該外部接続用電極が上記ガラス組成物を含むアルミニウム電極によって構成されていることを特徴とする。
また、好ましい一態様では、外部接続用電極を構成している上記ガラス組成物を含むアルミニウム電極上に導電性接着フィルムが貼り付けられていることを特徴とする。 According to the present invention, an aluminum electrode having an adhesive strength (peel strength) equal to or higher than that of a conventional Ag electrode can be formed on the silicon semiconductor substrate as the external connection electrode.
Accordingly, one particularly preferable aspect of the solar cell disclosed herein is that an external connection electrode is formed on the back surface side of the silicon semiconductor substrate, and the external connection electrode is formed by an aluminum electrode containing the glass composition. It is configured.
In a preferred embodiment, a conductive adhesive film is affixed on an aluminum electrode containing the glass composition that constitutes the external connection electrode.
即ち、ここで開示される太陽電池製造方法は、裏面側に形成されるアルミニウム電極の少なくとも一部を、本発明によって提供されるいずれかのペースト組成物を使用して形成することを特徴とする。 Further, the present invention provides, as another aspect for realizing the above object, a silicon semiconductor substrate, a light-receiving surface electrode formed on the light-receiving surface side that is one surface of the substrate, and the other surface of the substrate A method for producing a solar cell comprising an aluminum electrode formed on a back surface side is provided.
That is, the solar cell manufacturing method disclosed herein is characterized in that at least a part of the aluminum electrode formed on the back surface side is formed using any paste composition provided by the present invention. .
ここで開示されるアルミニウム電極形成用ペースト組成物は、太陽電池におけるアルミニウム電極を形成する用途に用いられるアルミニウムペーストであり、アルミニウム粉末、ガラスフリット、および、有機ビヒクルを含むペースト状(インク状と表現される場合を包含する。)に調製された電極形成用材料であり、本発明の目的を実現し得る限りにおいて、その他の構成成分に関しては特に制限はない。
本明細書においてアルミニウム粉末とは、アルミニウム(Al)を主体とする粒子の集合体をいい、典型的にはAl単体から成る粒子の集合体であるが、Al以外の不純物やAl主体の合金を微量含むものであっても、全体としてアルミニウム主体の粒子の集合体である限り、ここでいう「アルミニウム粉末」に包含され得る。なお、アルミニウム粉末自体は、従来公知の製造方法によって製造されたものでよく、特別な製造手段を要求するものではない。使用するアルミニウム粉末を構成する粒子は、典型的には球状であるが、いわゆる真球状のものに限られない。フレーク形状や不規則形状の粒子を含むものであってもよい。 First, the aluminum electrode forming paste composition provided by the present invention will be described in detail.
The aluminum electrode forming paste composition disclosed herein is an aluminum paste used for forming an aluminum electrode in a solar cell, and includes a paste form (expressed as ink form) containing aluminum powder, glass frit, and an organic vehicle. In other words, other constituent components are not particularly limited as long as they can realize the object of the present invention.
In this specification, the aluminum powder refers to an aggregate of particles mainly composed of aluminum (Al), and is typically an aggregate of particles composed of Al alone. However, an impurity other than Al or an alloy mainly composed of Al is used. Even a trace amount may be included in the “aluminum powder” as long as it is an aggregate of particles mainly composed of aluminum as a whole. The aluminum powder itself may be produced by a conventionally known production method and does not require special production means. The particles constituting the aluminum powder to be used are typically spherical, but are not limited to the so-called spherical shape. It may contain flake shaped or irregular shaped particles.
ここで開示されるアルミニウム電極形成用ペースト組成物に含まれるアルミニウム粉末は、平均粒径が20μm以下が適当であり、例えば平均粒径が1μm~10μm程度であるものを好ましく用いることができる。
本明細書において平均粒径は、粉末の粒度分布における累積体積50%時の粒径、すなわちD50(メジアン径)をいう。かかるD50は、レーザー回折法に基づく粒度分布測定装置によって容易に測定することができる。
特に限定しないが、アルミニウム粉末の含有量はペースト組成物全体を100質量%として、そのほぼ55~85質量%となる量が適当であり、60~80質量%である量がさらに好ましい。アルミニウム粉末含有量が上記のような場合には、緻密性がより向上したアルミニウム電極(例えば膜厚が100μm以下、例えば膜厚が10μm~100μmの外部接続用アルミニウム電極)をシリコン半導体基板上に好適に形成することができる。 The aluminum powder used is preferably a powder having a relatively narrow particle size distribution (in other words, a uniform particle size). As this index, the ratio (D10 / D90) of the particle size (D10) when the cumulative volume is 10% and the particle size (D90) when the cumulative volume is 90% in the particle size distribution based on the laser diffraction method can be adopted. When all the particle sizes constituting the powder are equal, the value of D10 / D90 is 1, and conversely, the value of D10 / D90 approaches 0 as the particle size distribution becomes wider. It is preferable to use a powder having a relatively narrow particle size distribution such that the value of D10 / D90 is 0.2 or more (for example, 0.2 to 0.5).
The aluminum powder contained in the aluminum electrode forming paste composition disclosed herein suitably has an average particle size of 20 μm or less. For example, an aluminum powder having an average particle size of about 1 μm to 10 μm can be preferably used.
In this specification, the average particle diameter refers to a particle diameter at a cumulative volume of 50% in the particle size distribution of the powder, that is, D50 (median diameter). Such D50 can be easily measured by a particle size distribution measuring apparatus based on a laser diffraction method.
Although there is no particular limitation, the content of aluminum powder is suitably about 55 to 85% by mass, more preferably 60 to 80% by mass, based on 100% by mass of the entire paste composition. When the aluminum powder content is as described above, an aluminum electrode having a higher density (for example, an aluminum electrode for external connection having a film thickness of 100 μm or less, for example, a film thickness of 10 μm to 100 μm) is suitable on a silicon semiconductor substrate. Can be formed.
即ち、ここで開示されるアルミニウム電極形成用ペースト組成物に含まれるガラスフリット(ガラス組成物)としては、例えば、熱膨張係数(線熱膨張係数)が60×10-7/℃以上80×10-7/℃以下であるものが適当であり、かかる熱膨張係数(線熱膨張係数)が65×10-7/℃以上75×10-7/℃以下であるものがより好ましい。
なお、本明細書において「熱膨張係数」は、一般的な示差膨張方式に基づく熱機械分析装置(TMA)によって測定される室温(25℃)~ガラス軟化点以下の温度(例えば400℃或いは500℃)の間の平均値として算出される。 Of the solid content in the aluminum electrode forming paste composition disclosed herein, glass frit (glass powder) is an inorganic additive that improves the adhesive strength of the aluminum electrode. In particular, in the paste composition (aluminum paste) provided by the present invention, the glass frit has the above-mentioned conditions (1) to (3), so that the formed aluminum electrode has high adhesive strength (peel strength). Can be granted.
That is, the glass frit (glass composition) contained in the aluminum electrode forming paste composition disclosed herein has, for example, a thermal expansion coefficient (linear thermal expansion coefficient) of 60 × 10 −7 / ° C. or more and 80 × 10 8. Those having −7 / ° C. or lower are suitable, and those having a thermal expansion coefficient (linear thermal expansion coefficient) of 65 × 10 −7 / ° C. or higher and 75 × 10 −7 / ° C. or lower are more preferable.
In the present specification, the “thermal expansion coefficient” is a temperature measured by a thermomechanical analyzer (TMA) based on a general differential expansion method (TMA) to a temperature below the glass softening point (for example, 400 ° C. or 500 ° C. Calculated as an average value during (° C).
ここで開示されるアルミニウム電極形成用ペースト組成物に含まれるガラスフリット(ガラス組成物)の好適例として、以下の各成分全体を100mol%として、各成分のモル含有率が、
SiO2 20~35mol%、
B2O3 5~30mol%、
ZnO及び/又はPbO 25~45mol%、
Al2O3 2~10mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 5~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 0~10mol%、
Bi2O3 0~5mol%、
であり、それら成分の合計がガラスフリット(ガラス組成物)全体の95mol%以上(典型的には100mol%)であるものが挙げられる。
さらに、特に好ましい組成のガラスフリットとして、以下の各成分全体を100mol
%として、各成分のモル含有率が、
SiO2 20~30mol%、
B2O3 20~30mol%、
ZnO 25~35mol%、
Al2O3 3~7mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 10~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 2~10mol%、
であり、それら成分の合計がガラスフリット(ガラス組成物)全体の95mol%以上(典型的には100mol%)であるものが挙げられる。 As a glass frit (glass composition) having the preferred thermal expansion coefficient and glass softening point, SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one kind It is preferable to include an alkali metal oxide (for example, selected from Li 2 O, Na 2 O, and K 2 O) as an essential component.
As a suitable example of the glass frit (glass composition) contained in the aluminum electrode forming paste composition disclosed herein, the following components as a whole are assumed to be 100 mol%, and the molar content of each component is:
SiO 2 20-35 mol%,
B 2 O 3 5-30 mol%,
ZnO and / or PbO 25-45 mol%,
Al 2 O 3 2-10 mol%,
At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%,
At least one of CaO, SrO and BaO 0-10 mol%,
Bi 2 O 3 0-5 mol%,
The total of these components is 95 mol% or more (typically 100 mol%) of the entire glass frit (glass composition).
Furthermore, as a glass frit having a particularly preferable composition, 100 mol of all the following components are contained.
%, The molar content of each component is
SiO 2 20-30 mol%,
B 2 O 3 20-30 mol%,
ZnO 25-35 mol%,
Al 2 O 3 3-7 mol%,
At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%,
2 to 10 mol% of at least one of CaO, SrO and BaO,
The total of these components is 95 mol% or more (typically 100 mol%) of the entire glass frit (glass composition).
例えば、必須構成成分であるSiO2は、ガラスの骨格を構成する主成分である。SiO2含有率が高すぎるとガラス軟化点が高くなりすぎてしまい好ましくない。一方、SiO2含有率が低すぎると耐化学性や耐水性が低下するため好ましくない。
また、B2O3は、軟化点ならびにガラスフリットの溶融温度を低下させる効果が高い成分である。B2O3含有率が低すぎるとガラスの軟化点及び溶融温度を低下させる効果が得られない。一方、B2O3含有率が高すぎると耐水性低下を招く虞があるため好ましくない。
また、ZnO或いはPbOは、ガラスフリット(ガラス組成物)の軟化点を下げることができる或いは熱膨張係数の調製を行うことができる成分であり、ZnO及びPbOのうちの何れか1種あるいは両方を上記含有率の範囲で含むことが好ましい。これら成分の含有率が高すぎるとガラス軟化点が低下しすぎるため好ましくない。なお、PbOフリーのものが好適である。 By containing the glass frit having the above composition, the adhesive strength (peel strength) of the aluminum electrode to be formed can be further improved.
For example, SiO 2 which is an essential component is a main component constituting a glass skeleton. If the SiO 2 content is too high, the glass softening point becomes too high, which is not preferable. On the other hand, if the SiO 2 content is too low, the chemical resistance and water resistance decrease, which is not preferable.
B 2 O 3 is a component having a high effect of lowering the softening point and the melting temperature of the glass frit. If the B 2 O 3 content is too low, the effect of lowering the softening point and melting temperature of the glass cannot be obtained. On the other hand, if the B 2 O 3 content is too high, the water resistance may be lowered, which is not preferable.
ZnO or PbO is a component that can lower the softening point of the glass frit (glass composition) or adjust the thermal expansion coefficient, and any one or both of ZnO and PbO can be used. It is preferable to contain in the range of the said content rate. If the content of these components is too high, the glass softening point is too low, which is not preferable. A PbO free material is preferred.
また、Li2O、Na2O、K2O等のアルカリ金属酸化物成分は、熱膨張係数を高める成分である。これらアルカリ金属酸化物成分の含有率が低すぎると熱膨張係数が低くなりすぎる虞がある。一方、これらの含有率が高すぎると熱膨張係数が過剰に高くなるため好ましくない。 Al 2 O 3 is a component that controls the fluidity of the glass frit during melting and is involved in the adhesion stability during the formation of the aluminum electrode. If the Al 2 O 3 content is too low, the adhesion stability is lowered, which is not preferred. If the Al 2 O 3 content is too high, the chemical resistance of the glass may be lowered, which is not preferred.
Further, alkali metal oxide components such as Li 2 O, Na 2 O, K 2 O is a component to increase the thermal expansion coefficient. If the content of these alkali metal oxide components is too low, the thermal expansion coefficient may be too low. On the other hand, if the content is too high, the thermal expansion coefficient becomes excessively high, which is not preferable.
例えば、CaO、SrO、BaO等のアルカリ土類金属の酸化物成分を10mol%以下の含有率で含有させることが好ましい。少なくとも1種のアルカリ土類金属酸化物を含有させることにより、熱膨張係数の調整をより容易に行うことができるとともに、ガラス組成の多様化(構成金属元素の多種類化)により耐化学性等を向上させ、ガラスの安定性を高め得るため好ましい。CaO、SrO、BaO等のアルカリ土類金属の酸化物成分を例えば1mol%以上10mol%以下(例えば2~10mol%、特には5~10mol%)の含有率で含有させることが好ましい。
また、焼成後のガラス(ひいては焼成後のアルミニウム電極)の安定性向上の目的のためにBi2O3を適当量、例えば10mol%以下(好適には5mol%以下)の割合で含有させてもよい。
また、その他、Zr、Ti、V、Nb、La、Ce、Sn、P等の酸化物成分をガラス組成物全体の5mol%以下(例えば0.1~5mol%程度)の割合で適宜含ませてもよい。 The glass frit can contain an arbitrary component in addition to the essential components described above.
For example, it is preferable to contain an alkaline earth metal oxide component such as CaO, SrO, or BaO at a content of 10 mol% or less. By containing at least one alkaline earth metal oxide, the thermal expansion coefficient can be adjusted more easily, and the chemical resistance, etc. can be improved by diversifying the glass composition (multiple types of constituent metal elements). Is preferable because it can improve the stability of the glass. It is preferable to contain an alkaline earth metal oxide component such as CaO, SrO, or BaO at a content of, for example, 1 mol% to 10 mol% (eg, 2 to 10 mol%, particularly 5 to 10 mol%).
Further, Bi 2 O 3 may be contained in an appropriate amount, for example, in a proportion of 10 mol% or less (preferably 5 mol% or less) for the purpose of improving the stability of the fired glass (and thus the fired aluminum electrode). Good.
In addition, other oxide components such as Zr, Ti, V, Nb, La, Ce, Sn, and P are appropriately included at a ratio of 5 mol% or less (for example, about 0.1 to 5 mol%) of the entire glass composition. Also good.
また、かかるガラス粉末の上記ペースト組成物中の含有量としては、特に限定されないが、該ペースト組成物全体を100質量%として1~15質量%程度が適当であり、2~10質量%程度が好ましい。この程度の含有率で上記のような元素組成のガラスフリットを含むペースト組成物によると、接着強度の高いアルミニウム電極(例えば裏面側の外部接続用アルミニウム電極)を好適に形成することができる。 In order to stably bake and fix (bake) the paste composition (coating film) applied on the silicon semiconductor substrate, the glass frit contained in the paste composition is a ratio based on the BET method. Those having a surface area of about 0.5 m 2 / g or more and 50 m 2 / g or less are preferred, and those having an average particle diameter (D50) of 2 μm or less (particularly about 1 μm or less) are preferred.
Further, the content of the glass powder in the paste composition is not particularly limited, but it is suitably about 1 to 15% by mass, and about 2 to 10% by mass with respect to 100% by mass of the entire paste composition. preferable. According to the paste composition containing the glass frit having the above elemental composition with such a content, an aluminum electrode having high adhesive strength (for example, an aluminum electrode for external connection on the back surface side) can be suitably formed.
かかるビヒクルを構成する有機溶媒は、アルミニウム粉末やガラスフリットを良好に分散させ得るものであればよく、従来のこの種のペーストに用いられているものを特に制限なく使用することができる。例えば、ビヒクルを構成する有機溶媒として、エチレングリコール及びジエチレングリコール誘導体(グリコールエーテル系溶剤)、トルエン、キシレン、ブチルカルビトール(BC)、ブチルジグリコールアセテート(BDGA)、ターピネオール等の高沸点有機溶媒を一種類又は複数種組み合わせて使用することができる。 また、ビヒクルを構成する有機バインダーとして種々の樹脂成分を含ませることができる。かかる樹脂成分は、ここで開示されるペースト組成物に良好な粘性及び塗膜形成能(シリコン基板に対する付着性)を付与し得るものであればよく、従来のこの種のペーストに用いられているものを特に制限なく使用することができる。例えば、アクリル樹脂、エポキシ樹脂、フェノール樹脂、アルキド樹脂、セルロース系高分子、ポリビニルアルコール、ロジン樹脂等を主体とするものが挙げられる。このうち、特にエチルセルロース等のセルロース系高分子が好ましい。
特に限定しないが、有機ビヒクル含有量はペースト全体のほぼ10~30質量%となる量が適当であり、ほぼ15~25質量%である量がさらに好ましい。 The paste composition disclosed here includes the above-described aluminum powder and glass frit (glass powder) as a solid content, and a liquid medium (organic vehicle) for dispersing the solid content.
The organic solvent constituting such a vehicle is not particularly limited as long as it can disperse aluminum powder and glass frit satisfactorily, and those used in conventional pastes of this type can be used without particular limitation. For example, as the organic solvent constituting the vehicle, high boiling point organic solvents such as ethylene glycol and diethylene glycol derivatives (glycol ether solvents), toluene, xylene, butyl carbitol (BC), butyl diglycol acetate (BDGA), terpineol and the like are used. It can be used in combination of multiple types. In addition, various resin components can be included as an organic binder constituting the vehicle. Any resin component may be used as long as it can provide the paste composition disclosed herein with good viscosity and coating film forming ability (adhesion to a silicon substrate), and is used in conventional pastes of this type. Things can be used without particular limitation. Examples thereof include those mainly composed of acrylic resin, epoxy resin, phenol resin, alkyd resin, cellulosic polymer, polyvinyl alcohol, rosin resin and the like. Among these, cellulosic polymers such as ethyl cellulose are particularly preferable.
Although there is no particular limitation, the organic vehicle content is suitably about 10 to 30% by mass of the total paste, and more preferably about 15 to 25% by mass.
次いで、ペースト塗布物を適当な温度(例えば室温以上であり典型的には100℃程度)で乾燥させる。乾燥後、適当な焼成炉(例えば高速焼成炉)中で適当な加熱条件(例えば600℃以上900℃以下、好ましくは700℃以上800℃以下)で所定時間加熱することによって、乾燥塗膜の焼成を行う。これにより、上記ペースト塗布物が基板上に焼き付けられ、後述する図1に示すような外部接続用アルミニウム電極22を形成することができる。 The paste composition disclosed here can be handled in the same manner as an aluminum paste conventionally used to form an aluminum electrode (and thus a p + layer or BSF layer) as a back electrode on a substrate, A conventionally known method can be employed without any particular limitation. Typically, the paste composition is applied (applied) to a silicon semiconductor substrate by a screen printing method, a dispenser coating method, a dip coating method, or the like so as to obtain a desired film thickness or coating film pattern. The thickness of the substrate can be set in consideration of the desired solar cell size, the thickness of the aluminum electrode formed on the substrate, the strength (for example, the breaking strength) of the substrate, and the like. Although not particularly limited, about 5 μm to 300 μm is appropriate, and about 5 μm to 200 μm (particularly about 10 μm to 100 μm) is preferable.
Next, the paste coating product is dried at an appropriate temperature (for example, room temperature or higher, typically about 100 ° C.). After drying, the dried coating film is baked by heating in an appropriate baking furnace (for example, a high-speed baking furnace) under appropriate heating conditions (for example, 600 ° C. to 900 ° C., preferably 700 ° C. to 800 ° C.) for a predetermined time. I do. Thereby, the paste application product is baked on the substrate, and an external
本実施形態の外部接続用アルミニウム電極22は、従来のこの種の電極を形成する場合(例えば、銀ペーストを材料として外部接続用Ag電極を形成する場合)と同様、所定の組成の第1アルミニウムペーストをスクリーン印刷し、焼成することによって形成される。 In the configuration of the present embodiment, an aluminum electrode forming paste composition disclosed herein (hereinafter sometimes referred to as “first aluminum paste” for convenience) is formed on the back side of the p-
The external
なお、本実施形態において、かかる裏面広域アルミニウム電極20は、アルミニウム粉末と、ガラスフリットと、有機ビヒクルとを含む、従来の太陽電池のアルミニウム電極を形成する用途に用いられる一般的なアルミニウムペーストであればよく、その内容に特に制限はない。従って、本発明を特徴付けるものではないため、詳細な説明は省略する。 Further, in the configuration of the present embodiment, the back surface
In this embodiment, the back surface
外部接続用アルミニウム電極22は、図7に示した構成においては裏面側外部接続用電極(Ag電極)122が位置する箇所に形成されている。図2(a)及び(b)に示した例では、外部接続用アルミニウム電極22は、例えば2~6mm幅の電極として機能させることができる。一般に、アルミニウムと半田との接合は困難である。従って、本実施形態の構成においては、外部接続用アルミニウム電極22に圧着するように導電性接着フィルム30が貼り付けられる(後述する図3参照)。導電性接着フィルム30(図3)は、典型的には異方性の導電性接着フィルムであり、例えば、接着材成分としてはエポキシ樹脂、フェノキシ樹脂、アクリル樹脂、ポリイミド樹脂、ポリアミド樹脂、ポリカーボネート樹脂その他の熱硬化型樹脂や熱可塑性樹脂を採用することができる。而して、該樹脂(接着材)成分中に種々の導電性粒子(典型的には、ニッケル、銅、貴金属等の金属粒子)が分散された構成をしており、導電性接着フィルム30を加熱・加圧することで、所定の部位に導電性接着フィルム30を貼り付けることができるとともに、当該導電性粒子によって導通を確保することができる。なお、使用する導電性接着フィルムに特に制限はなく、市販されているこの種の用途の導電性接着フィルムを特に制限なく採用することができる。 2A and 2B are a top view and a cross-sectional view schematically showing the configuration of the back surface side of the
In the configuration shown in FIG. 7, the external
まず、図4(a)に示すように、基板11上に形成された外部接続用アルミニウム電極22の上に導電性接着フィルム30を積層し、その導電性接着フィルム30の上にタブ線35を積層する。導電性接着フィルム30は、例えばエポキシ系の熱硬化型樹脂からなる接着材成分32中に均一に導電性粒子31(例えば、金メッキされたニッケル粒子)が分散された構成を有している。
次に、図4(b)に示すように、導電性接着フィルム30をタブ線接合材料として、外部接続用アルミニウム電極22、導電性接着フィルム30およびタブ線35の積層体を加圧・加熱することにより(矢印50参照)、導電性接着フィルム30中の導電性粒子31が外部接続用アルミニウム電極22とタブ線35とを導通する(矢印55参照)。それとともに、導電性接着フィルム30中の接着材成分(ここでは熱硬化型樹脂)32が熱硬化することによって、半田接合と同等レベルの確実な導通を実現することができる。なお、タブ線35を半田接合する場合には、200℃以上の高温を加える必要があるが、導電性接着フィルム30による接合では180℃程度での低温接合を実行することができる。従って、加熱による太陽電池(セル)100への影響(例えば熱による歪みの発生)を低減若しくは未然に防止することができる。 4A and 4B show a cross-sectional structure in which the
First, as shown in FIG. 4A, a conductive
Next, as shown in FIG. 4B, the laminate of the external
例えば、裏面広域アルミニウム電極20のところを含めて、全ての裏面アルミニウム電極を第1アルミニウムペーストによって形成することもできる。 In the embodiment described above, the external
For example, all the back surface aluminum electrodes including the back surface
本試験においては以下の表1にガラス組成(mol%)、ガラス軟化点(℃)及び熱膨張率(熱膨張係数)を示した計8種類のガラスサンプル(サンプル1~サンプル8)を使用した。 In the following tests, the difference in adhesive strength was evaluated when the properties of the glass frit which is a solid component of the aluminum electrode forming paste composition (aluminum paste) were made different from each other.
In this test, a total of 8 types of glass samples (sample 1 to sample 8) having the glass composition (mol%), the glass softening point (° C.) and the thermal expansion coefficient (thermal expansion coefficient) shown in Table 1 below were used. .
各試験例に係るアルミニウムペーストは、上記のガラスフリットの性状が異なるだけであり、その他の成分(アルミニウム粉末、有機ビヒクル)や配合比は同一とした。
即ち、各試験例のアルミニウムペーストの内容は以下のとおりである。
(1)アルミニウム粉末:
平均粒径6μmのアルミニウム粉末をペースト全体の66質量%となる量だけ配合して使用した。
(2)有機ビヒクル:
有機溶媒としてターピネオールをペースト全体の26質量%となる量だけ配合して使用した。
また、有機バインダーとして、エチルセルロースをペースト全体の約2質量%となる量だけ配合して使用した。
(3)ガラスフリット:
上記サンプル1~8の何れかの性状のガラスフリットをペースト全体の6質量%となる量だけ配合して使用した。 Thus, a total of 8 types of aluminum pastes (Test Examples 1 to 8) each containing the glass frit (Samples 1 to 8) shown in Table 1 were prepared.
The aluminum paste according to each test example was different only in the properties of the glass frit described above, and other components (aluminum powder, organic vehicle) and mixing ratio were the same.
That is, the contents of the aluminum paste of each test example are as follows.
(1) Aluminum powder:
Aluminum powder having an average particle size of 6 μm was used in an amount of 66% by mass of the entire paste.
(2) Organic vehicle:
As an organic solvent, terpineol was used in an amount of 26% by mass based on the entire paste.
Further, as an organic binder, ethyl cellulose was used in an amount of about 2% by mass of the entire paste.
(3) Glass frit:
The glass frit having the property of any of the above samples 1 to 8 was used in an amount of 6% by mass of the entire paste.
次に、上記のようにして製造した試験例1~8の各アルミニウムペーストを用いてシリコン半導体基板上に作製したアルミニウム電極について接着強度試験を行った。ここでシリコン半導体基板11の一面(裏面)に試験例1~8の各アルミニウムペーストを用いてアルミニウム電極を形成する手順は、次のとおりである。
即ち、市販の125mm四方の大きさの太陽電池用p型単結晶シリコン基板(板厚200μm)を用意し、その表面を水酸化ナトリウム水溶液を用いてアルカリエッチング処理した。次いで、上記エッチング処理でテクスチャ構造が形成されたシリコン基板の受光面にリン含有溶液を塗布し、熱処理を行なうことによって当該シリコン基板の受光面に厚さが約0.5μmであるn-Si層(n+層)を形成した。
次いで、n-Si層上にプラズマCVD(PECVD)法によって厚みが50nm以上100nm以下程度の反射防止膜(酸化チタン膜)を形成した。さらに、所定の表面電極(Ag電極)形成用銀ペーストを用いて反射防止膜上にスクリーン印刷法によって表面電極(Ag電極)となる塗膜(厚さ20μm以上50μm以下)を形成した。
一方、シリコン半導体基板の裏面側には、スクリーン印刷(ステンレス製スクリーンメッシュSUS#165を使用した。)により、上記試験例1~8のいずれかのペースト組成物を印刷(塗布)し、膜厚が約30μmの塗布膜を約5mm幅に線状に形成した。次いで、この基板を焼成して、試験評価用の線状のアルミニウム電極28を形成した。具体的には、大気雰囲気中で近赤外線高速焼成炉を用いて、焼成温度凡そ700℃以上800℃以下で焼成した。
こうして得られた試験評価用セル(太陽電池)を使用して接着強度の評価試験を実行することより、各試験例に係るアルミニウム電極形成用ペースト組成物から形成したアルミニウム電極の接着強度を測定した。 <Adhesive strength test (1)>
Next, an adhesive strength test was performed on the aluminum electrodes manufactured on the silicon semiconductor substrate using the aluminum pastes of Test Examples 1 to 8 manufactured as described above. Here, the procedure for forming an aluminum electrode on one surface (back surface) of the
That is, a commercially available 125 mm square p-type single crystal silicon substrate (plate thickness 200 μm) for solar cells was prepared, and the surface thereof was subjected to alkali etching treatment using an aqueous sodium hydroxide solution. Next, an n-Si layer having a thickness of about 0.5 μm is formed on the light-receiving surface of the silicon substrate by applying a phosphorus-containing solution to the light-receiving surface of the silicon substrate on which the texture structure is formed by the etching process and performing heat treatment. (N + layer) was formed.
Next, an antireflection film (titanium oxide film) having a thickness of about 50 nm to 100 nm was formed on the n-Si layer by plasma CVD (PECVD). Further, a coating film (thickness of 20 μm or more and 50 μm or less) to be a surface electrode (Ag electrode) was formed on the antireflection film by a screen printing method using a predetermined silver paste for forming a surface electrode (Ag electrode).
On the other hand, on the back side of the silicon semiconductor substrate, the paste composition of any of the above Test Examples 1 to 8 was printed (applied) by screen printing (using stainless steel screen mesh SUS # 165). A coating film having a thickness of about 30 μm was formed in a line shape with a width of about 5 mm. Next, this substrate was baked to form a
The adhesion strength of the aluminum electrode formed from the paste composition for forming an aluminum electrode according to each test example was measured by performing an adhesion strength evaluation test using the test evaluation cell (solar cell) thus obtained. .
具体的には、図5に示した強度測定装置300は、固定治具40の上に固定ねじ43及び係止板44を介してガラス基板41を固定し、そのガラス基板41上にエポキシ接着材42によって上記得られた試験用のシリコン半導体基板11の受光面側を固着した。
こうしてガラス基板41上に固着させたシリコン半導体基板11の露出表面側にある上記形成したアルミニウム電極28上に市販品である導電性接着フィルム30を加熱圧着により貼り付け、当該導電性接着フィルム30上にさらにタブ線35を貼り付けた。
そして、図5に示すように、強度測定装置300を固定治具40の底面が135°になるように傾斜させ、タブ線35に予め形成されている延長部35eを鉛直方向上方に引っ張ることにより(矢印45参照)、タブ線35/導電性接着フィルム30/電極28の接着強度を測定した。 Evaluation of the adhesive strength (peel strength) of the formed aluminum electrode (that is, peel strength evaluation) was performed using a
Specifically, the
A
Then, as shown in FIG. 5, the
なお、図6のグラフは、本試験により得られた接着強度とアルミニウムペースト中のガラスフリットの軟化点とを関係を示している。 The results are shown in the corresponding column of Table 2. The adhesive strength evaluation test (peel strength test) is performed on a plurality of (two) aluminum electrodes formed from the aluminum paste according to each test example, and the average of the test results (measured values) for the two aluminum electrodes. The value (that is, the number of measurements n = 2) was evaluated as the adhesive strength.
In addition, the graph of FIG. 6 has shown the relationship between the adhesive strength obtained by this test, and the softening point of the glass frit in an aluminum paste.
また、ガラスフリットの熱膨張係数が60×10-7/℃以上80×10-7/℃以下(特には65×10-7/℃以上75×10-7/℃以下)であるものが高い接着強度を示すことが認められた。 As shown in Table 2 and FIG. 6, it was confirmed that the glass softening point in the aluminum paste exhibited high adhesive strength in the range of 400 ° C. to 600 ° C. (particularly 500 ° C. to 600 ° C.). In particular, when the aluminum paste of Test Example 6 having a glass softening point around 550 ° C. was used, extremely high adhesive strength was observed.
Further, the glass frit has a high thermal expansion coefficient of 60 × 10 −7 / ° C. to 80 × 10 −7 / ° C. (especially 65 × 10 −7 / ° C. to 75 × 10 −7 / ° C.). It was observed to show adhesive strength.
さらに、上述の接着強度試験(1)と同様の手順に従い、試験例6に係るアルミニウムペーストを用いて上記シリコン半導体基板11上に膜厚が約30μmで約2mm幅の線状アルミニウム電極を形成して同様のピール強度評価試験を行ったところ、表3の実施例の欄に示すように、平均値(n=2)で3.25N/2mmの接着強度が認められた。
比較対照として、試験例6に係るアルミニウムペーストに代えて通常の銀ペーストを用いて上記シリコン半導体基板11上に膜厚が約30μmで約2mm幅の線状Ag電極を形成し、その表面にハンダを介して上記タブ線35を貼り付け、同様のピール強度評価試験を行ったところ、表3の比較例Aの欄に示すように、平均値(n=2)で3.5N/2mmの接着強度が認められた。
なお、表3中の比較例Bは、試験例6に係るアルミニウムペーストに代えて試験例1に係るアルミニウムペーストを用いたときの結果である。 <Adhesive strength test (2)>
Further, a linear aluminum electrode having a film thickness of about 30 μm and a width of about 2 mm is formed on the
As a comparative control, a linear Ag electrode having a film thickness of about 30 μm and a width of about 2 mm is formed on the
In addition, Comparative Example B in Table 3 is a result when the aluminum paste according to Test Example 1 is used instead of the aluminum paste according to Test Example 6.
また、アルミニウム膜の接着強度(剥離強度)を向上させた外部接続用アルミニウム電極によって、導電性接着フィルムを用いた接合を利用することできるため、半田接合のための電極の部分を含めないパターンを構築することができる。その結果、基板(ウェハ)の裏面全面のアルミニウム化により、BSF層の均一形成に起因する太陽電池の発電効率の向上とともに、バスバー電極のパターンを省略することに起因する太陽電池の発電効率の向上を実現することが可能となる。 As is clear from the description of the embodiment and test examples described above, in the solar cell provided by the present invention, an aluminum electrode can be employed as the backside external connection electrode. As a result, it is possible to perform bonding using a conductive adhesive film, which cannot be used with ordinary aluminum electrodes because of low adhesive strength. Therefore, the BSF layer can be uniformly formed on the entire back surface of the silicon semiconductor substrate (wafer) as compared with the conventional configuration in which the Ag electrode is used as the back surface side external connection electrode. In addition, cost reduction corresponding to the material price difference between silver and aluminum can be achieved.
Moreover, since the bonding using the conductive adhesive film can be used by the aluminum electrode for external connection with improved adhesion strength (peeling strength) of the aluminum film, a pattern not including the electrode portion for solder bonding can be used. Can be built. As a result, the aluminization of the entire back surface of the substrate (wafer) improves the power generation efficiency of the solar cell due to the uniform formation of the BSF layer, and improves the power generation efficiency of the solar cell due to omitting the bus bar electrode pattern. Can be realized.
12 受光面電極
14 反射防止膜
16 n-Si層
18 p-Si層
20 裏面広域アルミニウム電極
22 外部接続用アルミニウム電極
23 開口部
24 BSF層
30 導電性接着フィルム
31 導電性粒子
32 接着材成分
35 タブ線(リード線)
35e タブ延長部
40 固定治具
41 ガラス基板
100、200、1000 太陽電池
300 強度測定装置 11 Silicon semiconductor substrate (Si wafer)
12 Light-receiving
Claims (12)
- 太陽電池のアルミニウム電極を形成するためのペースト組成物であって、
アルミニウム粉末と、
ガラスフリットであって、以下の条件:
(1)ガラス軟化点が400℃以上600℃以下である;
(2)熱膨張係数が60×10-7/℃以上80×10-7/℃以下である;
(3)SiO2と、B2O3と、ZnO及び/又はPbOと、Al2O3と、少なくとも一種のアルカリ金属酸化物とを必須構成成分として含む;
を具備するガラスフリットと、
有機ビヒクルと、
を含む、アルミニウム電極形成用ペースト組成物。 A paste composition for forming an aluminum electrode of a solar cell,
Aluminum powder,
Glass frit with the following conditions:
(1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower;
(2) The coefficient of thermal expansion is 60 × 10 −7 / ° C. or more and 80 × 10 −7 / ° C. or less;
(3) Including SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one alkali metal oxide as essential components;
A glass frit comprising:
An organic vehicle,
A paste composition for forming an aluminum electrode, comprising: - 前記ガラスフリットは、以下の各成分全体を100mol%として、各成分のモル含有率が、
SiO2 20~35mol%、
B2O3 5~30mol%、
ZnO及び/又はPbO 25~45mol%、
Al2O3 2~10mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 5~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 0~10mol%、
Bi2O3 0~5mol%、
であり、それら成分の合計が該ガラスフリット全体の95mol%以上である、請求項1に記載のペースト組成物。 The glass frit is 100 mol% of the following components as a whole, and the molar content of each component is
SiO 2 20 ~ 35mol%,
B 2 O 3 5-30 mol%,
ZnO and / or PbO 25-45 mol%,
Al 2 O 3 2-10 mol%,
At least one of Li 2 O, Na 2 O and K 2 O, 5 to 15 mol%,
At least one of CaO, SrO and BaO 0-10 mol%,
Bi 2 O 3 0-5 mol%,
The paste composition according to claim 1, wherein the total of these components is 95 mol% or more of the entire glass frit. - 前記ガラスフリットは、以下の各成分全体を100mol%として、各成分のモル含有率が、
SiO2 20~30mol%、
B2O3 20~30mol%、
ZnO 25~35mol%、
Al2O3 3~7mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 10~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 2~10mol%、
であり、それら成分の合計が該ガラスフリット全体の95mol%以上である、請求項2に記載のペースト組成物。 The glass frit is 100 mol% of the following components as a whole, and the molar content of each component is
SiO 2 20-30 mol%,
B 2 O 3 20-30 mol%,
ZnO 25-35 mol%,
Al 2 O 3 3-7 mol%,
At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%,
2 to 10 mol% of at least one of CaO, SrO and BaO,
The paste composition according to claim 2, wherein the total of these components is 95 mol% or more of the entire glass frit. - 前記ガラスフリットのガラス軟化点が500℃以上600℃以下である、請求項1~3のいずれか一項に記載のペースト組成物。 The paste composition according to any one of claims 1 to 3, wherein a glass softening point of the glass frit is 500 ° C or higher and 600 ° C or lower.
- ペースト組成物全体を100質量%として、前記アルミニウム粉末の含有率が60~80質量%であり、且つ、前記ガラスフリットの含有率が2~10質量%である、請求項1~4のいずれか一項に記載のペースト組成物。 The content of the aluminum powder is 60 to 80% by mass, and the content of the glass frit is 2 to 10% by mass based on 100% by mass of the entire paste composition. The paste composition according to one item.
- シリコン半導体基板と、該基板の一方の面である受光面側に形成される受光面電極と、該基板の他方の面である裏面側に形成されるアルミニウム電極とを備える太陽電池であって、
前記アルミニウム電極の少なくとも一部は、ガラス組成物として、以下の条件:
(1)ガラス軟化点が400℃以上600℃以下である;
(2)熱膨張係数が60×10-7/℃以上80×10-7/℃以下である;
(3)SiO2と、B2O3と、ZnO及び/又はPbOと、Al2O3と、少なくとも一種のアルカリ金属酸化物とを必須構成成分として含む;
を具備するガラス組成物を含有することを特徴とする、太陽電池。 A solar cell comprising a silicon semiconductor substrate, a light-receiving surface electrode formed on the light-receiving surface side which is one surface of the substrate, and an aluminum electrode formed on the back surface side which is the other surface of the substrate,
At least a part of the aluminum electrode, as a glass composition, has the following conditions:
(1) The glass softening point is 400 ° C. or higher and 600 ° C. or lower;
(2) The coefficient of thermal expansion is 60 × 10 −7 / ° C. or more and 80 × 10 −7 / ° C. or less;
(3) Including SiO 2 , B 2 O 3 , ZnO and / or PbO, Al 2 O 3 , and at least one alkali metal oxide as essential components;
A solar cell comprising a glass composition comprising: - 前記ガラス組成物は、以下の各成分全体を100mol%として、各成分のモル含有率が、
SiO2 20~35mol%、
B2O3 5~30mol%、
ZnO及び/又はPbO 25~45mol%、
Al2O3 2~10mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 5~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 0~10mol%、
Bi2O3 0~5mol%、
であり、それら成分の合計が該ガラス組成物全体の95mol%以上である、請求項6に記載の太陽電池。 The glass composition has the following components as a whole at 100 mol%, and the molar content of each component is
SiO 2 20-35 mol%,
B 2 O 3 5-30 mol%,
ZnO and / or PbO 25-45 mol%,
Al 2 O 3 2-10 mol%,
Li 2 O, at least one of Na 2 O and K 2 O 5 ~ 15mol%,
At least one of CaO, SrO and BaO 0-10 mol%,
Bi 2 O 3 0-5 mol%,
The solar cell according to claim 6, wherein the total of these components is 95 mol% or more of the entire glass composition. - 前記ガラス組成物は、以下の各成分全体を100mol%として、各成分のモル含有率が、
SiO2 20~30mol%、
B2O3 20~30mol%、
ZnO 25~35mol%、
Al2O3 3~7mol%、
Li2O、Na2O及びK2Oうちの少なくとも1種 10~15mol%、
CaO、SrO及びBaOのうちの少なくとも1種 2~10mol%、
であり、それら成分の合計が該ガラス組成物全体の95mol%以上である、請求項7に記載の太陽電池。 The glass composition has the following components as a whole at 100 mol%, and the molar content of each component is
SiO 2 20-30 mol%,
B 2 O 3 20-30 mol%,
ZnO 25-35 mol%,
Al 2 O 3 3-7 mol%,
At least one of Li 2 O, Na 2 O and K 2 O 10-15 mol%,
2 to 10 mol% of at least one of CaO, SrO and BaO,
The solar cell according to claim 7, wherein the total of these components is 95 mol% or more of the entire glass composition. - 前記ガラス組成物のガラス軟化点が500℃以上600℃以下である、請求項6~8のいずれか一項に記載の太陽電池。 The solar cell according to any one of claims 6 to 8, wherein the glass softening point of the glass composition is 500 ° C or higher and 600 ° C or lower.
- 前記裏面側には、外部接続用電極が形成されており、
ここで該外部接続用電極は、前記ガラス組成物を含むアルミニウム電極によって構成されている、請求項6~9のいずれか一項に記載の太陽電池。 On the back side, an external connection electrode is formed,
10. The solar cell according to claim 6, wherein the external connection electrode is composed of an aluminum electrode containing the glass composition. - 前記外部接続用電極を構成している前記ガラス組成物を含むアルミニウム電極上に導電性接着フィルムが貼り付けられている、請求項10に記載の太陽電池。 The solar cell according to claim 10, wherein a conductive adhesive film is affixed on an aluminum electrode containing the glass composition constituting the external connection electrode.
- シリコン半導体基板と、該基板の一方の面である受光面側に形成される受光面電極と、該基板の他方の面である裏面側に形成されるアルミニウム電極とを備える太陽電池を製造する方法であって、
前記裏面側に形成されるアルミニウム電極の少なくとも一部を、請求項1~5のいずれか一項に記載のペースト組成物を使用して形成することを特徴とする、太陽電池の製造方法。 A method of manufacturing a solar cell comprising a silicon semiconductor substrate, a light receiving surface electrode formed on the light receiving surface which is one surface of the substrate, and an aluminum electrode formed on the back surface which is the other surface of the substrate Because
A method for producing a solar cell, wherein at least a part of an aluminum electrode formed on the back surface side is formed using the paste composition according to any one of claims 1 to 5.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201280027104.0A CN103597548B (en) | 2011-06-03 | 2012-05-17 | The aluminium electrode formation paste composition of solar cell and solar cell |
DE112012002354.4T DE112012002354T5 (en) | 2011-06-03 | 2012-05-17 | Solar cell and paste composition for forming an aluminum electrode of a solar cell |
KR1020137031831A KR20140027372A (en) | 2011-06-03 | 2012-05-17 | Solar cell and paste composition for forming aluminum electrode of solar cell |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2011125062 | 2011-06-03 | ||
JP2011-125062 | 2011-06-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012165167A1 true WO2012165167A1 (en) | 2012-12-06 |
Family
ID=47259030
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2012/062687 WO2012165167A1 (en) | 2011-06-03 | 2012-05-17 | Solar cell and paste composition for forming aluminum electrode of solar cell |
Country Status (6)
Country | Link |
---|---|
JP (1) | JPWO2012165167A1 (en) |
KR (1) | KR20140027372A (en) |
CN (1) | CN103597548B (en) |
DE (1) | DE112012002354T5 (en) |
TW (1) | TW201250716A (en) |
WO (1) | WO2012165167A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014178419A1 (en) * | 2013-05-02 | 2014-11-06 | 株式会社ノリタケカンパニーリミテド | Solar cell and paste composition for forming aluminum electrode for solar cell |
JP2014220127A (en) * | 2013-05-08 | 2014-11-20 | 株式会社村田製作所 | Conductive paste, method of producing the same and ceramic electronic part using the same |
JP2014241335A (en) * | 2013-06-11 | 2014-12-25 | 日立化成株式会社 | Solar battery cell and solar battery module |
JP2015115400A (en) * | 2013-12-10 | 2015-06-22 | 東洋アルミニウム株式会社 | Conductive aluminum paste |
JP6074483B1 (en) * | 2015-11-10 | 2017-02-01 | 株式会社ノリタケカンパニーリミテド | Conductive composition |
KR20180004166A (en) | 2015-05-01 | 2018-01-10 | 도요 알루미늄 가부시키가이샤 | PERC-type aluminum paste composition for solar cell |
CN114409249A (en) * | 2022-01-06 | 2022-04-29 | 江苏日御光伏新材料科技有限公司 | Silicon-lithium-lead system and conductive slurry and preparation method thereof |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114725224A (en) * | 2022-04-12 | 2022-07-08 | 安徽华晟新能源科技有限公司 | Grid line prefabricated structure and preparation method thereof, and preparation method of heterojunction battery |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005243935A (en) * | 2004-02-26 | 2005-09-08 | Shin Etsu Handotai Co Ltd | Solar cell module and manufacturing method thereof |
JP2008159917A (en) * | 2006-12-25 | 2008-07-10 | Kyocera Corp | Conductive paste for photoelectric conversion device, photoelectric conversion device, and method of constructing photoelectric conversion device |
WO2009063841A1 (en) * | 2007-11-15 | 2009-05-22 | Hitachi Chemical Company, Ltd. | Solar battery cell |
JP2010192480A (en) * | 2009-02-16 | 2010-09-02 | Nippon Electric Glass Co Ltd | Glass composition for electrode formation, and electrode forming material |
JP2010248034A (en) * | 2009-04-16 | 2010-11-04 | Nippon Electric Glass Co Ltd | Glass composition for forming electrode and electrode forming material |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4970026B2 (en) * | 2006-12-26 | 2012-07-04 | 京セラ株式会社 | Conductive paste for photoelectric conversion element, photoelectric conversion element, and method for producing photoelectric conversion element |
US7485245B1 (en) * | 2007-10-18 | 2009-02-03 | E.I. Du Pont De Nemours And Company | Electrode paste for solar cell and solar cell electrode using the paste |
JP5113710B2 (en) * | 2008-10-08 | 2013-01-09 | 京都エレックス株式会社 | Conductive paste for forming electrode of solar cell element, solar cell element, and method for manufacturing the solar cell element |
-
2012
- 2012-05-14 TW TW101117083A patent/TW201250716A/en unknown
- 2012-05-17 KR KR1020137031831A patent/KR20140027372A/en not_active Application Discontinuation
- 2012-05-17 CN CN201280027104.0A patent/CN103597548B/en not_active Expired - Fee Related
- 2012-05-17 WO PCT/JP2012/062687 patent/WO2012165167A1/en active Application Filing
- 2012-05-17 JP JP2013517960A patent/JPWO2012165167A1/en active Pending
- 2012-05-17 DE DE112012002354.4T patent/DE112012002354T5/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005243935A (en) * | 2004-02-26 | 2005-09-08 | Shin Etsu Handotai Co Ltd | Solar cell module and manufacturing method thereof |
JP2008159917A (en) * | 2006-12-25 | 2008-07-10 | Kyocera Corp | Conductive paste for photoelectric conversion device, photoelectric conversion device, and method of constructing photoelectric conversion device |
WO2009063841A1 (en) * | 2007-11-15 | 2009-05-22 | Hitachi Chemical Company, Ltd. | Solar battery cell |
JP2010192480A (en) * | 2009-02-16 | 2010-09-02 | Nippon Electric Glass Co Ltd | Glass composition for electrode formation, and electrode forming material |
JP2010248034A (en) * | 2009-04-16 | 2010-11-04 | Nippon Electric Glass Co Ltd | Glass composition for forming electrode and electrode forming material |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014178419A1 (en) * | 2013-05-02 | 2014-11-06 | 株式会社ノリタケカンパニーリミテド | Solar cell and paste composition for forming aluminum electrode for solar cell |
JP2014220127A (en) * | 2013-05-08 | 2014-11-20 | 株式会社村田製作所 | Conductive paste, method of producing the same and ceramic electronic part using the same |
JP2014241335A (en) * | 2013-06-11 | 2014-12-25 | 日立化成株式会社 | Solar battery cell and solar battery module |
JP2015115400A (en) * | 2013-12-10 | 2015-06-22 | 東洋アルミニウム株式会社 | Conductive aluminum paste |
KR20180004166A (en) | 2015-05-01 | 2018-01-10 | 도요 알루미늄 가부시키가이샤 | PERC-type aluminum paste composition for solar cell |
JP6074483B1 (en) * | 2015-11-10 | 2017-02-01 | 株式会社ノリタケカンパニーリミテド | Conductive composition |
JP2017092254A (en) * | 2015-11-10 | 2017-05-25 | 株式会社ノリタケカンパニーリミテド | Conductive composition |
CN114409249A (en) * | 2022-01-06 | 2022-04-29 | 江苏日御光伏新材料科技有限公司 | Silicon-lithium-lead system and conductive slurry and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
CN103597548A (en) | 2014-02-19 |
KR20140027372A (en) | 2014-03-06 |
DE112012002354T5 (en) | 2014-02-20 |
CN103597548B (en) | 2016-05-11 |
JPWO2012165167A1 (en) | 2015-02-23 |
TW201250716A (en) | 2012-12-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2012165167A1 (en) | Solar cell and paste composition for forming aluminum electrode of solar cell | |
JP6110311B2 (en) | Conductive paste composition and solar cell electrodes and contacts formed therefrom | |
US8123985B2 (en) | Electroconductive thick film composition(s), electrode(s), and semiconductor device(s) formed therefrom | |
JP5438113B2 (en) | Use of aluminum paste and aluminum paste in the production of silicon solar cells | |
CN103283039A (en) | Nanoparticle inks for solar cells | |
US8884277B2 (en) | Thick film conductive composition and use thereof | |
JP2012502503A (en) | Solar cell electrode | |
JP2011521401A (en) | Aluminum paste and its use in the manufacture of silicon solar cells | |
CN102428567A (en) | Process Of Forming A Grid Electrode On The Front-Side Of A Silicon Wafer | |
TWI725035B (en) | Electric conductive paste, solar cell and method for manufacturing solar cell | |
JP5590191B2 (en) | Method for producing conductive composition | |
CN109478573A (en) | Rear electrode paste composite used for solar batteries | |
TW201626404A (en) | Conductive composition, semiconductor element, and solar battery element | |
US20130160844A1 (en) | Thick-Film Composition Containing Antimony Oxides And Their Use In The Manufacture Of Semiconductor Devices | |
CN102365688A (en) | Metal pastes and use thereof in the production of silicon solar cells | |
CN102428566A (en) | Process Of Forming A Grid Electrode On The Front-Side Of A Silicon Wafer | |
JP6371099B2 (en) | Conductive paste and crystalline silicon solar cell | |
WO2014178419A1 (en) | Solar cell and paste composition for forming aluminum electrode for solar cell | |
WO2013031751A1 (en) | Conductive paste, electrode for semiconductor devices, semiconductor device, and method for manufacturing semiconductor device | |
JP2017092253A (en) | Conductive composition | |
US9445519B2 (en) | Method of manufacturing thick-film electrode | |
CN103298759B (en) | Conductive paste and use the solar cell device of this conductive paste | |
TW201830714A (en) | Front electrode for solar cell and solar cell comprising the same | |
JP2014078594A (en) | Paste composition and solar battery | |
KR20140048465A (en) | Ag paste composition for forming electrode and silicon solar cell using the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201280027104.0 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 12793722 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2013517960 Country of ref document: JP Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 20137031831 Country of ref document: KR Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 112012002354 Country of ref document: DE Ref document number: 1120120023544 Country of ref document: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 12793722 Country of ref document: EP Kind code of ref document: A1 |