EP1733436A1 - Mo substrate for a photovoltaic solar cell - Google Patents
Mo substrate for a photovoltaic solar cellInfo
- Publication number
- EP1733436A1 EP1733436A1 EP05716294A EP05716294A EP1733436A1 EP 1733436 A1 EP1733436 A1 EP 1733436A1 EP 05716294 A EP05716294 A EP 05716294A EP 05716294 A EP05716294 A EP 05716294A EP 1733436 A1 EP1733436 A1 EP 1733436A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- molybdenum
- layer
- alloy
- metal strip
- thickness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000758 substrate Substances 0.000 title claims abstract description 65
- 229910052751 metal Inorganic materials 0.000 claims abstract description 102
- 239000002184 metal Substances 0.000 claims abstract description 102
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 52
- 239000011733 molybdenum Substances 0.000 claims abstract description 52
- 238000000034 method Methods 0.000 claims abstract description 38
- 229910001182 Mo alloy Inorganic materials 0.000 claims abstract description 35
- 230000008569 process Effects 0.000 claims abstract description 20
- 239000011148 porous material Substances 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 238000005240 physical vapour deposition Methods 0.000 claims abstract 4
- 238000005097 cold rolling Methods 0.000 claims description 17
- 230000009467 reduction Effects 0.000 claims description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 11
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 239000010949 copper Substances 0.000 claims description 9
- 238000000678 plasma activation Methods 0.000 claims description 8
- 229910001369 Brass Inorganic materials 0.000 claims description 7
- 239000010951 brass Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 5
- 229910000831 Steel Inorganic materials 0.000 claims description 4
- 239000010959 steel Substances 0.000 claims description 4
- 229910000599 Cr alloy Inorganic materials 0.000 claims description 3
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 3
- AFTDTIZUABOECB-UHFFFAOYSA-N [Co].[Mo] Chemical compound [Co].[Mo] AFTDTIZUABOECB-UHFFFAOYSA-N 0.000 claims description 3
- 239000000788 chromium alloy Substances 0.000 claims description 3
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 3
- 230000008021 deposition Effects 0.000 claims description 3
- DDTIGTPWGISMKL-UHFFFAOYSA-N molybdenum nickel Chemical compound [Ni].[Mo] DDTIGTPWGISMKL-UHFFFAOYSA-N 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 229910000531 Co alloy Inorganic materials 0.000 claims 2
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 239000011651 chromium Substances 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000009713 electroplating Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910003271 Ni-Fe Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- KTSFMFGEAAANTF-UHFFFAOYSA-N [Cu].[Se].[Se].[In] Chemical compound [Cu].[Se].[Se].[In] KTSFMFGEAAANTF-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000035987 intoxication Effects 0.000 description 1
- 231100000566 intoxication Toxicity 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000012995 silicone-based technology Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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
- H01L31/0248—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 characterised by their semiconductor bodies
- H01L31/0256—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 characterised by their semiconductor bodies characterised by the material
- H01L31/0264—Inorganic materials
- H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
- H01L31/0322—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—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 characterised by potential barriers
- H01L31/072—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 characterised by potential barriers the potential barriers being only of the PN heterojunction type
- H01L31/0749—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 characterised by potential barriers the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/541—CuInSe2 material PV cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the invention relates to a metal substrate for a photovoltaic solar cell.
- the invention also relates to a metal strip for producing such metal substrates, to a photovoltaic solar cell comprising such a metal substrate, and to a method for producing such a metal strip.
- the photovoltaic solar cell market is at present dominated by silicon based technology. Photovoltaic cells transform solar light directly into electricity; after installation no further costs need to be made.
- a silicon substrate however has several disadvantageous. One of them is the high price, another the fact that silicon is not flexible.
- a photovoltaic solar cell has been developed using glass or copper (or brass) as a substrate.
- a basic layer of Cr, Ni or Ni-Fe and a contact layer of molybdenum, wolfram or palladium, or an alloy thereof with nickel has been provided by electroplating.
- Other electroplating layers are also possible.
- a flexible solar cell can be provided when a copper or substrate is used, as described in patent application WO 01/57932.
- a CIS layer Copper Indium Selenide/Sulphur
- a disadvantage of this technology is that glass as a substrate is not flexible, and that copper (or brass) as a substrate is expensive.
- PND Physical Napour Deposition
- the metal substrate according to the invention it is possible to provide a pure or almost pure molybdenum layer on the metal substrate. This is not possible with conventional techniques, since molybdenum cannot be electroplated as such, but only in combination with other metals like ⁇ i or Cr as is described in WO 01/57932. However, these codeposited metals will contaminate the semiconductor produced in this way, so for that reason an intermediate layer is necessary, such as the basic layer of Cr, ⁇ i or ⁇ i-Fe as described in WO 01/57932.
- the application of the molybdenum (alloy) layer by using a PND technique thus reduces the number of layers that is necessary, and thus the production price of the metal substrate is reduced.
- WO 01/57932 is has already be mentioned that it is possible to apply the CIS layer on a flexible molybdenum foil which can be bought on the market, but that such foils are too expensive. Since PND applied layers are porous, it is required that the molybdenum (alloy) layer on the metal substrate according to the invention is pore free. If pores are present, elements from the metal substrate could contaminate the semiconductor. According to a first preferred embodiment of the metal substrate the metal substrate has been subjected to a skin pass or cold rolling operation after the layer of molybdenum or molybdenum alloy has been applied.
- the layer of molybdenum or molybdenum alloy has been applied by a PND process including plasma activation. Due to the plasma activation during the PND process, the molybdenum (alloy) will not form crystals on the metal substrate, but the molybdenum (alloy) will form an amorphous layer on the metal substrate without pores.
- a skin pass or cold rolling operation on the amorphous molybdenum (alloy) layer, but this is not required to obtain an essentially pore free layer.
- the layer of molybdenum or molybdenum alloy has a thickness between 0.5 to 10 ⁇ m, preferably a thickness between 1.0 to 5 ⁇ m, more preferably a thickness between 1.5 to 3 ⁇ m. If a layer with a thickness of more than 5 ⁇ m has been applied by a PND process, the layer is essentially pore free without any further treatment. However, molybdenum is an expensive material and for that reason the layer should be thin. Therefore, a thickness between 1.5 to 3 ⁇ m is preferred.
- the molybdenum has a purity of 99.0 wt % or more. With such a purity no intoxication of the semiconductor will occur.
- the molybdenum alloy is a molybdenum-nickel alloy or a molybdenum-chromium alloy or a molybdenum-cobalt layer. This means that also when the molybdenum has a purity of 99.0 wt % or more, the remainder should preferably consist of chromium, nickel or cobalt or a combination thereof.
- the skin pass or cold rolling operation has provided a reduction in thickness of the metal substrate of between 0.2 and 20 %, preferably a reduction in thickness of between 3 to 7 %, more preferably a reduction in thickness of essentially 5 %.
- the slcin pass operation is used to provide a small thickness reduction; for a larger thickness reduction a cold rolling operation is used. Since the skin pass or cold rolling operation is usually needed to close the pores in the molybdenum (alloy) layer, any thickness reduction will do. However, the slcin pass or cold rolling operation is also used to provide a smooth surface to the metal substrate.
- the molybdenum or molybdenum alloy layer has a mirror finish, more preferably a roughness Ra being lower than 0.6 ⁇ m, even more preferably a roughness Ra being below 0.05 ⁇ m.
- a roughness provides the best surface for the CIS layer to be applied to the metal substrate.
- the metal substrate consists of steel, stainless steel, copper or brass. These metals are relatively cheap substrates for photovoltaic solar cells. Steel is most preferred in view of cost aspects.
- the metal substrate has a thickness between 0.08 and 0.5 mm, preferably a thickness of essentially 0.2 mm. Such thicknesses provide the required flexibility and stability, for instance a thickness between 0.15 and 0.3 mm.
- a thickness of essentially 0.2 mm is preferred as optimal thickness for both stability and flexibility.
- a much thinner substrate is not stable enough on for instance roofs, and a much thicker substrate is not flexible enough.
- a metal strip for producing metal substrates for photovoltaic solar cells wherein on the metal strip a layer of molybdenum or molybdenum alloy is present that has been applied by Physical Napour Deposition (PND) process and wherein the layer of molybdenum is at least essentially pore free.
- PND Physical Napour Deposition
- Such a metal strip can be the basis for the metal substrates according to the first aspect of the invention, and can be produced easier and cheaper than producing such metal substrates piece by piece.
- the metal strip can have a with of a few times ten to a few times hundred millimeter or more, and a length of several hundred meter or more.
- the molybdenum or molybdenum alloy has been applied by a PND process in a continuous strip coating process.
- Using a continuous process for the coating of the metal strip provides a cheaper strip than the batch-wise coating using the PND process.
- Further preferred embodiments of the metal strip according to the invention have, mutatis mutandis, the same features and advantages as the preferred features of the metal substrate according to the first aspect of the invention.
- a photovoltaic solar cell comprising a metal substrate according to the first aspect of the invention or produced from a metal strip according to the second aspect of the invention. This is the end product that can be produced using the metal substrate or metal strip specified above.
- a method for producing a metal strip suitable for producing metal substrates for photovoltaic solar cells comprising the steps: providing a metal strip; applying a layer of molybdenum or molybdenum alloy by a PND process; providing a method step such that the layer of molybdenum or molybdenum alloy becomes at least essentially pore free. This method provides the metal strip according to the second aspect of the invention.
- the method step consists of subjecting the metal strip with the layer of molybdenum or molybdenum alloy to a skin pass or cold rolling operation. Due to the skin pass or cold rolling operation the pores are closed.
- the method step consists in including plasma activation in the PND process. Due to the plasma activation the pores are not formed. If a skin pass or cold rolling operation is performed, this operation is used to provide a smooth surface to the metal strip.
- the layer of molybdenum or molybdenum alloy is applied in a continuous manner.
- This is a very cost-effective way to produce a metal strip with a molybdenum (alloy) coating applied by the PND process.
- the skin pass or cold rolling operation is performed in a continuous manner, more preferably in the same run as the application of the layer of molybdenum or molybdenum alloy. In this way a long metal strip can be provided that is pore free and has a smooth surface.
- the method according to the fourth aspect of the invention is used for producing the metal strip according to the second aspect of the invention.
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Power Engineering (AREA)
- Sustainable Energy (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Photovoltaic Devices (AREA)
Abstract
The invention relates to a metal substrate for a solar cell. According to the invention on the metal substrate a layer of molybdenum or molybdenum alloy is present that has been applied by a Physical Vapour Deposition (PVD) process, the layer of molybdenum or molybdenum alloy being at least essentially pore free. The invention also relates to a metal strip for producing such metal substrates and to a method for producing such a metal strip, and to a photovoltaic solar cell comprising such a metal substrate.
Description
MO SUBSTRATE FOR A PHOTOVOLTAIC SOLAR CELL
The invention relates to a metal substrate for a photovoltaic solar cell. The invention also relates to a metal strip for producing such metal substrates, to a photovoltaic solar cell comprising such a metal substrate, and to a method for producing such a metal strip. The photovoltaic solar cell market is at present dominated by silicon based technology. Photovoltaic cells transform solar light directly into electricity; after installation no further costs need to be made. A silicon substrate however has several disadvantageous. One of them is the high price, another the fact that silicon is not flexible. As an alternative to the silicon solar cell, a photovoltaic solar cell has been developed using glass or copper (or brass) as a substrate. On this substrate for instance a basic layer of Cr, Ni or Ni-Fe and a contact layer of molybdenum, wolfram or palladium, or an alloy thereof with nickel has been provided by electroplating. Other electroplating layers are also possible. In this way a flexible solar cell can be provided when a copper or substrate is used, as described in patent application WO 01/57932. On these layers a CIS layer (Copper Indium Selenide/Sulphur) is provided to produce a photovoltaic solar cell. A disadvantage of this technology is that glass as a substrate is not flexible, and that copper (or brass) as a substrate is expensive. Important is also that copper atoms from the copper or brass layer could negatively influence the semiconductor or CIS layer due to diffusion of copper atoms in the CIS layer, which would change the ratio of copper in the CIS layer, having a negative effect on the performance of the solar cell during the life time of the solar cell. For this reason a diffusion barrier layer is needed, which makes the copper/brass based solar cells expensive. Moreover the electroplating of a basic layer and a contact layer makes the production expensive. It is an object of the invention to provide a metal substrate for a photovoltaic solar cell that is relatively cheap to manufacture. It is another object of the invention to provide a metal substrate that is relatively easy to manufacture.
It is still another object of the invention to provide a metal strip for producing such metal substrates that is relatively cheap respectively relatively easy to manufacture. It is yet another object of the invention to provide a photovoltaic solar cell using the metal substrate or metal strip as foreseen above. Still another object of the invention is to provide a method for producing a metal strip as foreseen above. According to a first aspect of the invention one or more of these objectives is reached with a metal substrate for a photovoltaic solar cell, wherein on the metal substrate a layer of molybdenum or molybdenum alloy is present that has been applied by a Physical Napour Deposition (PND) process and wherein the layer of molybdenum or molybdenum alloy is at least essentially pore free. With the metal substrate according to the invention it is possible to provide a pure or almost pure molybdenum layer on the metal substrate. This is not possible with conventional techniques, since molybdenum cannot be electroplated as such, but only in combination with other metals like Νi or Cr as is described in WO 01/57932. However, these codeposited metals will contaminate the semiconductor produced in this way, so for that reason an intermediate layer is necessary, such as the basic layer of Cr, Νi or Νi-Fe as described in WO 01/57932. The application of the molybdenum (alloy) layer by using a PND technique thus reduces the number of layers that is necessary, and thus the production price of the metal substrate is reduced. It should be noted that in WO 01/57932 is has already be mentioned that it is possible to apply the CIS layer on a flexible molybdenum foil which can be bought on the market, but that such foils are too expensive. Since PND applied layers are porous, it is required that the molybdenum (alloy) layer on the metal substrate according to the invention is pore free. If pores are present, elements from the metal substrate could contaminate the semiconductor. According to a first preferred embodiment of the metal substrate the metal substrate has been subjected to a skin pass or cold rolling operation after the layer of molybdenum or molybdenum alloy has been applied. Due to the skin pass or cold rolling operation the molybdenum (alloy) layer is compressed and the pores that are present in the PND layer are closed.
According to a second preferred embodiment of the metal substrate the layer of molybdenum or molybdenum alloy has been applied by a PND process including plasma activation. Due to the plasma activation during the PND process, the molybdenum (alloy) will not form crystals on the metal substrate, but the molybdenum (alloy) will form an amorphous layer on the metal substrate without pores. Of course it will be possible to perform a skin pass or cold rolling operation on the amorphous molybdenum (alloy) layer, but this is not required to obtain an essentially pore free layer. Using plasma activation means that in the semi-vacuum used for the PND process a voltage is applied, resulting in a gas-discharge. The gas-discharge results in the amorphous layer. Preferably, the layer of molybdenum or molybdenum alloy has a thickness between 0.5 to 10 μm, preferably a thickness between 1.0 to 5 μm, more preferably a thickness between 1.5 to 3 μm. If a layer with a thickness of more than 5 μm has been applied by a PND process, the layer is essentially pore free without any further treatment. However, molybdenum is an expensive material and for that reason the layer should be thin. Therefore, a thickness between 1.5 to 3 μm is preferred. These thicknesses suffice for applying a CIS layer. According to a preferred embodiment, the molybdenum has a purity of 99.0 wt % or more. With such a purity no intoxication of the semiconductor will occur. Preferably, the molybdenum alloy is a molybdenum-nickel alloy or a molybdenum-chromium alloy or a molybdenum-cobalt layer. This means that also when the molybdenum has a purity of 99.0 wt % or more, the remainder should preferably consist of chromium, nickel or cobalt or a combination thereof. According to a preferred embodiment the skin pass or cold rolling operation has provided a reduction in thickness of the metal substrate of between 0.2 and 20 %, preferably a reduction in thickness of between 3 to 7 %, more preferably a reduction in thickness of essentially 5 %. The slcin pass operation is used to provide a small thickness reduction; for a larger thickness reduction a cold rolling operation is used. Since the skin pass or cold rolling operation is usually needed to close the pores in the molybdenum (alloy) layer, any thickness reduction will do. However, the slcin pass or cold rolling operation is also used to provide a smooth surface to the metal substrate.
Preferably, the molybdenum or molybdenum alloy layer has a mirror finish, more preferably a roughness Ra being lower than 0.6 μm, even more preferably a roughness Ra being below 0.05 μm. Such a roughness provides the best surface for the CIS layer to be applied to the metal substrate. According to a preferred embodiment the metal substrate consists of steel, stainless steel, copper or brass. These metals are relatively cheap substrates for photovoltaic solar cells. Steel is most preferred in view of cost aspects. Preferably the metal substrate has a thickness between 0.08 and 0.5 mm, preferably a thickness of essentially 0.2 mm. Such thicknesses provide the required flexibility and stability, for instance a thickness between 0.15 and 0.3 mm. A thickness of essentially 0.2 mm is preferred as optimal thickness for both stability and flexibility. A much thinner substrate is not stable enough on for instance roofs, and a much thicker substrate is not flexible enough. According to a second aspect of the invention one or more of these objectives is reached with a metal strip for producing metal substrates for photovoltaic solar cells, wherein on the metal strip a layer of molybdenum or molybdenum alloy is present that has been applied by Physical Napour Deposition (PND) process and wherein the layer of molybdenum is at least essentially pore free. Such a metal strip can be the basis for the metal substrates according to the first aspect of the invention, and can be produced easier and cheaper than producing such metal substrates piece by piece. The metal strip can have a with of a few times ten to a few times hundred millimeter or more, and a length of several hundred meter or more. According to a preferred embodiment of the metal strip, the molybdenum or molybdenum alloy has been applied by a PND process in a continuous strip coating process. Using a continuous process for the coating of the metal strip provides a cheaper strip than the batch-wise coating using the PND process. Further preferred embodiments of the metal strip according to the invention have, mutatis mutandis, the same features and advantages as the preferred features of the metal substrate according to the first aspect of the invention. According to a third aspect of the invention there is provided a photovoltaic solar cell comprising a metal substrate according to the first aspect of the invention or produced from a metal strip according to the second aspect of the invention. This is the
end product that can be produced using the metal substrate or metal strip specified above. According to a fourth aspect of the invention a method for producing a metal strip suitable for producing metal substrates for photovoltaic solar cells is provided, the method comprising the steps: providing a metal strip; applying a layer of molybdenum or molybdenum alloy by a PND process; providing a method step such that the layer of molybdenum or molybdenum alloy becomes at least essentially pore free. This method provides the metal strip according to the second aspect of the invention. In this way a relatively cheap way is provided to produce the metal strip according to the invention, using the PND process to apply a layer of molybdenum (alloy) and providing that layer pore free. According to a first preferred embodiment of the method, the method step consists of subjecting the metal strip with the layer of molybdenum or molybdenum alloy to a skin pass or cold rolling operation. Due to the skin pass or cold rolling operation the pores are closed. According to a second preferred embodiment of the method, the method step consists in including plasma activation in the PND process. Due to the plasma activation the pores are not formed. If a skin pass or cold rolling operation is performed, this operation is used to provide a smooth surface to the metal strip. Preferably, the layer of molybdenum or molybdenum alloy is applied in a continuous manner. This is a very cost-effective way to produce a metal strip with a molybdenum (alloy) coating applied by the PND process. Preferably the skin pass or cold rolling operation is performed in a continuous manner, more preferably in the same run as the application of the layer of molybdenum or molybdenum alloy. In this way a long metal strip can be provided that is pore free and has a smooth surface. According to a preferred embodiment the method according to the fourth aspect of the invention is used for producing the metal strip according to the second aspect of the invention.
Claims
1. Metal substrate for a photovoltaic solar cell, characterized in that on the metal substrate a layer of molybdenum or molybdenum alloy is present that has been applied by a Physical Vapour Deposition (PVD) process and in that the layer of molybdenum or molybdenum alloy is at least essentially pore free.
2. Metal substrate according to claim 1, wherein the metal substrate has been subjected to a skin pass or cold rolling operation after the layer of molybdenum or molybdenum alloy has been applied.
3. Metal substrate according to claim 1 or 2, wherein the layer of molybdenum or molybdenum alloy has been applied by a PND process including plasma activation.
4. Metal substrate according to claim 1, 2 or 3, wherein the layer of molybdenum or molybdenum alloy has a thickness between 0.5 to 10 μm, preferably a thickness between 1.0 to 5 μm, more preferably a thickness between 1.5 to 3 μm.
5. Metal substrate according to claim 1 - 4, wherein the molybdenum has a purity of 99.0 wt % or more.
6. Metal substrate according to claim 1 - 5, wherein the molybdenum alloy is a molybdenum-nickel alloy or a molybdenum-chromium alloy or a molybdenum- cobalt alloy or a combination thereof.
7. Metal substrate according to any one of the preceding claims, wherein the skin pass or cold rolling operation has provided a reduction in thickness of the metal substrate of between 0.2 and 20 %, preferably a reduction in thickness of between 3 to 7 %, more preferably a reduction in thickness of essentially 5 %.
8. Metal substrate according to any one of the preceding claims, wherein the molybdenum or molybdenum alloy layer has a mirror finish, preferably a roughness Ra being lower than 0.6 μm, more preferably a roughness Ra being below 0.05 μm.
9. Metal substrate according to any one of the preceding claims, wherein the metal substrate has a thickness between 0.08 and 0.5 mm, preferably a thickness of essentially 0.2 mm.
10. Metal substrate according to any one of the preceding claims, wherein the metal substrate consists of steel, stainless steel, copper or brass.
11. Metal strip for producing metal substrates for photovoltaic solar cells, characterized in that on the metal strip a layer of molybdenum or molybdenum alloy is present that has been applied by Physical Napour Deposition (PND) process and in that the layer of molybdenum is at least essentially pore free.
12. Metal strip according to claim 11, wherein the metal strip has been subjected to a skin pass or cold rolling operation after the layer of molybdenum or molybdenum alloy has been applied.
13. Metal strip according to claim 11 or 12, wherein the layer of molybdenum or molybdenum alloy has been applied by a PND process including plasma activation.
14. Metal strip according to claim 11, 12 or 13, wherein the molybdenum or molybdenum alloy has been applied by a PND process in a continuous strip coating process.
15. Metal strip according to claim 11 - 14, wherein the layer of molybdenum or molybdenum alloy has a thickness between 0.5 to 10 μm, preferably a thickness between 1.0 to 5 μm, more preferably a thickness between 1.5 to 3 μm.
16. Metal strip according to any one of claims 11 - 15, wherein the molybdenum has a purity of 99.0 wt % or more.
17. Metal strip according to any one of claims 11 - 16, wherein the molybdenum alloy is a molybdenum-nickel alloy or a molybdenum-chromium alloy or a molybdenum-cobalt alloy or a combination thereof.
18. Metal strip according to any one of claims 11 - 17, wherein the skin pass or cold rolling operation has provided a reduction in thickness of the metal strip of between 0.2 and 20 %, preferably a reduction in thickness of between 3 to 7 %, more preferably a reduction in thickness of essentially 5 %.
19. Metal strip according to any one of claims 11 - 18, wherein the metal substrate consists of steel, stainless steel, copper or brass.
20. Metal strip according to any one of claims 11 - 19, wherein the metal strip has a thickness between 0.08 and 0.5 mm, preferably a thickness of essentially 0.2 mm.
21. Metal strip according to any one of claims 11 - 20, wherein the molybdenum or molybdenum alloy layer has a mirror finish, preferably a roughness Ra being lower than 0.6 μm, more preferably a roughness Ra being below 0.05 μm.
22. Photovoltaic solar cell comprising a metal substrate according to any one of the claims 1 - 10 or produced from a metal strip according to any one of the claims 11 - 21.
23. Method for producing a metal strip suitable for producing metal substrates for photovoltaic solar cells, the method comprising the steps: providing a metal strip; applying a layer of molybdenum or molybdenum alloy by a PND process; providing a method step such that the layer of molybdenum or molybdenum alloy becomes at least essentially pore free.
24. Method according to claim 23, wherein the method step consists of subjecting the metal strip with the layer of molybdenum or molybdenum alloy to a skin pass or cold rolling operation.
25. Method according to claim 23 or 24, wherein the method step consists in including plasma activation in the PND process.
26. Method according to any one of claims 23 - 25, wherein the layer of molybdenum or molybdenum alloy is applied in a continuous manner.
27. Method according to any one of claims 23 - 26, wherein the skin pass or cold rolling operation is performed in a continuous manner, preferably in the same run as the application of the layer of molybdenum or molybdenum alloy.
28. Method according to any one of the claims 23 - 27 for producing the metal strip according to any one of the claims 11 - 21.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP05716294A EP1733436A1 (en) | 2004-03-30 | 2005-03-18 | Mo substrate for a photovoltaic solar cell |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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EP04075974 | 2004-03-30 | ||
PCT/EP2005/003042 WO2005096395A1 (en) | 2004-03-30 | 2005-03-18 | Mo substrate for a photovoltaic solar cell |
EP05716294A EP1733436A1 (en) | 2004-03-30 | 2005-03-18 | Mo substrate for a photovoltaic solar cell |
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EP1733436A1 true EP1733436A1 (en) | 2006-12-20 |
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EP05716294A Withdrawn EP1733436A1 (en) | 2004-03-30 | 2005-03-18 | Mo substrate for a photovoltaic solar cell |
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WO (1) | WO2005096395A1 (en) |
Families Citing this family (6)
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US8101858B2 (en) | 2006-03-14 | 2012-01-24 | Corus Technology B.V. | Chalcopyrite semiconductor based photovoltaic solar cell comprising a metal substrate, coated metal substrate for a photovoltaic solar cell and manufacturing method thereof |
JP2011503847A (en) | 2007-11-02 | 2011-01-27 | ワコンダ テクノロジーズ, インコーポレイテッド | Crystalline thin film photovoltaic structure and method for forming the same |
WO2010088366A1 (en) | 2009-01-28 | 2010-08-05 | Wakonda Technologies, Inc. | Large-grain crystalline thin-film structures and devices and methods for forming the same |
CN101931011A (en) * | 2009-06-26 | 2010-12-29 | 安泰科技股份有限公司 | Thin film solar cell as well as base band and preparation method thereof |
FR2969389A1 (en) * | 2010-12-21 | 2012-06-22 | Saint Gobain | CONDUCTIVE SUBSTRATE BASED ON MOLYBDENUM |
KR20140103257A (en) | 2011-10-24 | 2014-08-26 | 릴라이언스 인더스트리즈 리미티드 | Thin films and preparation process thereof |
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US4392451A (en) * | 1980-12-31 | 1983-07-12 | The Boeing Company | Apparatus for forming thin-film heterojunction solar cells employing materials selected from the class of I-III-VI2 chalcopyrite compounds |
EP1261990A1 (en) * | 2000-02-07 | 2002-12-04 | CIS Solartechnik Gmbh | Flexible metal substrate for cis solar cells, and method for producing the same |
-
2005
- 2005-03-18 WO PCT/EP2005/003042 patent/WO2005096395A1/en not_active Application Discontinuation
- 2005-03-18 EP EP05716294A patent/EP1733436A1/en not_active Withdrawn
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