EP1177584A2 - Solar cell and method for producing a solar cell - Google Patents

Solar cell and method for producing a solar cell

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Publication number
EP1177584A2
EP1177584A2 EP00934884A EP00934884A EP1177584A2 EP 1177584 A2 EP1177584 A2 EP 1177584A2 EP 00934884 A EP00934884 A EP 00934884A EP 00934884 A EP00934884 A EP 00934884A EP 1177584 A2 EP1177584 A2 EP 1177584A2
Authority
EP
European Patent Office
Prior art keywords
absorber layer
carrier
layer
solar cell
copper
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Withdrawn
Application number
EP00934884A
Other languages
German (de)
French (fr)
Inventor
Klaus Kalberlah
Thomas Hoffmann
Klaus Jacobs
Rainer MÖLLER
Andreas Kampmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CIS Solartechnik GmbH and Co KG
Original Assignee
CIS Solartechnik GmbH and Co KG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by CIS Solartechnik GmbH and Co KG filed Critical CIS Solartechnik GmbH and Co KG
Publication of EP1177584A2 publication Critical patent/EP1177584A2/en
Withdrawn legal-status Critical Current

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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
    • H01L31/0248—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
    • H01L31/036—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 their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392—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 their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • H01L31/03926—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 their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate comprising a flexible substrate
    • H01L31/03928—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 their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate comprising a flexible substrate including AIBIIICVI compound, e.g. CIS, CIGS deposited on metal or polymer foils
    • 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
    • H01L31/0248—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
    • H01L31/036—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 their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392—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 their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • 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
    • H01L31/1876—Particular processes or apparatus for batch treatment of the devices
    • 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 solar cell which has an absorber layer which is arranged on a flexible and band-shaped carrier and in which the absorber layer at least partially contains copper, at least one element from the group of indium and gallium and at least one element from the group of selenium and sulfur and in which the absorber layer is at least partially p-type.
  • the invention further relates to a method for producing a solar cell, in which a flexible and ribbon-shaped support is provided with an absorber layer and in which the absorber layer is at least partially made of copper, at least one element from the group indium and gallium and at least one element from the group Selenium and sulfur is produced and in which the absorber layer is provided with p-conducting properties at least in some areas.
  • Thin-film solar cells are generally produced by first applying a transparent, electrically conductive layer to special silicate glass (solar glass) and then vapor-deposition silicon with various doping. In turn, a conductive layer is applied as the cover layer, but this does not need to be translucent. Through the use of masks, a separation of the layers using a laser and the successive sequence of the processing steps described, the entire area is structured in such a way that a large number of individual cells that are electrically connected in series. Through contacting, protective cover on the back and framing of the entire structure, a thin-film solar module is created which is used to convert light energy into electrical power (regenerative power generation). Solar modules are also known in which copper-indium-selenide (CIS) was vapor-deposited on glass instead of silicon.
  • CIS copper-indium-selenide
  • Solar modules are available under the trade name UNISOLAR, in which silicon was vapor-deposited on a long stainless steel strip in a high vacuum ("roll-to-roll” process). The tape is then cut at the non-vaporized points and the individual cells are electrically and mechanically combined to form solar modules.
  • a specialty here is the production of tandem or triple cells, in which two or three spectrally differently sensitive silicon cells are layered on top of one another. Such a tandem cell on a glass substrate, manufactured in a high vacuum, was already produced in CIS technology by the Hahn-Meitner-Institut Berlin and was shown for the first time at the 1998 technical fair in Hanover.
  • DE 196 34 580 proposes to use the shingle technique known per se, the question of undesirable contacts between the copper and the conductive cover layers at the edges and the interfaces of the band being open remains.
  • the object of the present invention is therefore to construct a solar cell of the type mentioned in the introduction in such a way that both low production costs and high electrical efficiency are achieved.
  • the object is achieved in that the absorber layer is at least partially applied galvanically to the carrier, that the components of the absorber layer are relative to each other in a stoichiometric. trical ratio and that the absorber layer is heat-treated after its application to the carrier.
  • Another object of the present invention is to improve a method of the type mentioned in the introduction in such a way that large-scale production of the solar cells is supported at low production prices.
  • the absorber layer is at least partially applied galvanically to the carrier, in that the constituents of the absorber layer are deposited in a stoichiometric ratio relative to one another and in that the absorber layer is subjected to a heat treatment after it has been applied to the carrier.
  • the strip is guided continuously or clocked through several "galvanic" baths, with CIS (copper, indium and selenium) being electromechanical on the cell areas. is mixed homogeneously.
  • a further, homogeneous copper cover layer can preferably be applied galvanically to these galvanically produced layers or, alternatively, copper doping can be carried out.
  • the strip can be passed through a so-called "lamp oven", the mixing and the microcrystalline structure of the CIS layer being optimized by heating the coated areas in a precisely metered manner in terms of time and temperature.
  • the cover layer made of metallic copper and a layer of copper selenium which may be located below it can be selectively removed by etching.
  • a transparent, n-conductive cover layer for example zinc oxide, can be applied to the entire strip.
  • the flexible carrier is cut in the area of the insulating layer, so that individual cells are formed whose top layer (ITO) and base layer are electrically conductive, but are reliably insulated from one another.
  • the method proposed according to the invention can be carried out in such a way that an approximately 35 mm wide and fractional millimeter thick stainless steel strip is used.
  • This has the advantage that a width of 35 mm is an international standard for flexible printed circuit boards, which creates equipment advantages in the manufacture of solar cells.
  • the number of contacts when the cells are connected to modules, which also presents a certain problem in shingle technology, is considerably reduced compared to a band cell that is only 10 mm wide, for example.
  • an insulating layer made of an electrically non-conductive and highly temperature-resistant material can also be applied to the carrier in such a way that delimited, uncoated areas are formed, on which the CIS is later deposited.
  • ternary i.e. at the same time, copper, indium and selenium are deposited electrochemically in one pass through an appropriate bath. Precautions must be taken to ensure that the concentration of the electrolytes remains constant, that no gas bubbles adhere to the layer (risk of "pinholes") and that other inhomogeneities are avoided.
  • ternary deposition it can prove to be expedient to break down the deposition of the elements into sub-steps, for example first applying binary indium + selenium and then copper. Certain advantages arise if first binary copper + selenium, then indium + selenium are deposited at the same time.
  • the "mixing" is then carried out by heating in the lamp furnace, the temperature, the residence time and the heating and cooling gradients having to be optimized differently depending on the layer structure selected.
  • the strip is fed into an annealing furnace, it being advantageous to supply the strip with the required thermal energy not by heat conduction, but rather by heat radiation.
  • the temperature, the time gradient of the heating (which seems to be important for the crystallization process) and the residence time can be set up as desired.
  • the cooling process is controlled in terms of speed and course (bottom to top or vice versa) by cooling the contact surface and / or blowing in cooled protective gas.
  • tempering CIS cells A known problem in tempering CIS cells is the volatility of selenium, which destroys any optimal stoichiometric balance that may be present.
  • selenium steam By adding selenium steam, it is necessary to "re-select" in the tempering furnace ("selenization furnace"); In the lamp furnace, as used for the production of CIS cells according to the invention, this is avoided by, on the one hand, using the lowest possible temperatures, and on the other hand, the heating takes place very quickly by means of correspondingly strong light radiation on the covering copper layer of the strip. If this is not sufficient, an excess pressure of the protective gas atmosphere (eg nitrogen) can be set in the lamp furnace. Annealing under excess pressure the structuring of the band according to the invention in areas and the clocked feed almost inevitably presupposes this, but this can in principle also be carried out with a rapidly continuously running band cell.
  • the protective gas atmosphere eg nitrogen
  • the irradiation of light on the upper side of the band leads to a temperature gradient in the layer, which can be advantageous with regard to the diffusion out of the band or with regard to the load on lower layers when building a tandem cell structure.
  • the strip After leaving the lamp furnace, the strip is largely removed by etching in the fifth process step, i.e.
  • individual conductor tracks made of Cu remain, which take over the low-resistance derivation of the electrons generated by the photon absorption and field separation instead of the grid (usually "printed” with silver paste), usually printed with silver paste.
  • the "etched free" surface of the cell is provided with a transparent, highly electrically conductive cover layer ("ITO window electrode").
  • ITO window electrode a transparent, highly electrically conductive cover layer
  • This is done, for example, by spray pyrolysis of zinc oxide; It is advantageous that the cell area was delimited in step 1 by an insulator, so that an exact delimitation of the areas affected by the spraying is now not necessary: applying the electrically conductive layer beyond the cell edge does not lead to short circuits or reworking.
  • the finished, for example 40 cm long and 35 mm wide, CIS solar cells are produced by cutting the tape outside the cell areas. Instead of the shingle-like connection proposed in DE 196 34 589, they are preferably electrically connected to one another by means of interposed "spacers".
  • the finished arrangement of, for example, 40 cells in series connection is covered in a so-called “laminator 1 in a slight vacuum under pressure and heat on the front with a transparent TEDLAR ° film and on the back with the EVA film customary in solar technology and protected against weather influences.
  • the resulting arrangement of solar cells is called a “laminate”, which is further processed into a “standard solar module” by providing it with a frame and a cable junction box.
  • the carrier consists of at least one metal and the back electrode of the solar cell forms that the absorber layer is at least partially applied galvanically to the carrier is that the constituents of the absorber layer copper, indium / gallium and selenium / sulfur are present in a stoichometric ratio of 1: 1: 2 or with a slight excess of selenium and that the absorber layer is heat-treated in a device after it has been applied to the carrier in such a way that it is converted into pure, single-phase crystalline copper indium / gallium diselenide / sulfide with at least some p-type characteristics.
  • one or more matching, base, contact or adhesive layers are applied before the application of the absorber layer, preferably by electrochemical deposition.
  • the layers which form the absorber by sequential electrochemical deposition of the metals copper, indium / gallium and selenium or by binary deposition of compound semiconductors according to the formula "Cu2Se plus In2Se3 / Ga2Se3 equal to 2 Culn / GaSe2" or by ternary Deposition or by a mixture of metal deposition and deposition of compound semiconductors such as Cu, In2Se3 / Ga2Se3, Se takes place with a precisely determined thickness in such a way that the proportions are correct or a small excess of selenium is present.
  • a sodium-containing compound for example sodium selenide
  • a sodium-containing compound for example sodium selenide
  • the constituents of the absorber layer were "recrystallized" by heating to temperatures above 500 ° Celsius under a protective gas atmosphere to form a uniform, pure and p-conducting CIS2 layer, with a very rapid rise in temperature and a short duration of the Heating, by a very small volume above the absorber layer and / or by an overpressure of the protective gas atmosphere, evaporation of selenium / sulfur and the formation of other crystalline phases is prevented or made more difficult.
  • FIG. 2 a top view of the arrangement according to FIG. 1
  • Fig. 3 an example of the structure of a heat treatment furnace.
  • Fig. 1 shows a flexible carrier (1) which is provided with a surface (2) on which an absorber layer (3) is arranged. Insulating layers (4) extend along edge regions and a copper cover layer (5) is applied to the absorber layer (3) in this embodiment. Alternatively, doping with copper can also be used, for example. be lized. In the area of the side of the absorber layer (3) facing away from the carrier (1), a cover layer (6) is arranged, which can be formed, for example, as an ITO layer.
  • the flexible carrier (1) is unwound from a roll (7) and passed through an interior (8) of the temperature control device (9).
  • the cover layer (5) and intermediate cell areas (10) are located on the carrier (1).
  • a material (11), which can be sulfur or selenium, for example, is applied in the conveying direction next to the absorber layer (3).
  • the temperature control device (9) has a transparent lower cover (12) and a semi-transparent upper cover (13).
  • a protective gas atmosphere is arranged in the area of the interior (8) and the interior (8) is enclosed by a translucent housing (14).
  • Heat radiators (15) of a first control circuit are arranged below the housing (14) and heat radiators (16) of a second control circuit and heat radiators (17) of a third control circuit are positioned above the housing (13).
  • the heat radiators (15) of the first control loop are essentially opposite the heat radiators of the third control loop.
  • the heat radiators of the second control circuit are arranged in the transport direction of the carrier (1) from the roll (7) to a take-up roll (18) in front of or behind the heat radiators (17) of the third control circuit. arranges.
  • the lower cover (12) is provided with cooling (19), which can be formed, for example, from cooling channels through which a cooling medium flows.
  • cooling (19) can be formed, for example, from cooling channels through which a cooling medium flows.
  • locks (20) are arranged in the inlet area and in the outlet area of the housing (14).
  • the carrier (1) can be made of different materials. In particular, the use of copper is thought of. Alternatively, steel strips or carrier materials made of flexible plastics can also be used.
  • the insulating layer (4) is arranged in such a way that the cell areas remain free.
  • the electrodeposition of the absorber layer (4) can be carried out, for example, in such a way that an electrochemical deposition of the metals copper, indium and / or gallium and selenium is carried out sequentially.
  • the heat treatment of the absorber layer (3) within the furnace described in FIG. 3 takes place during the cycle operation of the carrier (1) through the furnace.
  • sulfur or selenium is supplied in vapor form.
  • these elements are deposited on the intermediate cell area (10).
  • a regulation of the heat supply is divided into at least two control loops, so that the cell areas and the intermediate cell areas can be heated differently.
  • the sulfur and selenium in the intercell area is first evaporated and then this area is used to condense the remaining steam.

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  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
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  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Photovoltaic Devices (AREA)

Abstract

The solar cell is provided with an absorbing layer which is arranged on a flexible and band-shaped support. The absorbing layer is at least partially provided with components of copper and is provided with at least one element from the group of indium and gallium and with at least one element from the group of selenium and sulphur and is at least partially embodied as p-type. The absorbing layer is at least partially deposited on the support in a plating manner. The components of the absorbing layer are in a stoichiometric ratio in relation to one another. The absorbing layer is heat-treated after having been deposited on the support.

Description

Solarzelle sowie Verfahren zur Herstellung einer Solarzelle Solar cell and method for producing a solar cell
Die Erfindung betrifft eine Solarzelle, die eine Absorberschicht aufweist, die auf einem flexiblen und bandförmigen Träger angeordnet ist und bei der die Absorberschicht mindestens teilweise Kupfer, mindestens ein Element aus der Gruppe Indium und Gallium sowie mindestens ein Element aus der Gruppe Selen und Schwefel enthält sowie bei der der Absorberschicht mindestens bereichsweise p-leitend ausgebildet ist.The invention relates to a solar cell which has an absorber layer which is arranged on a flexible and band-shaped carrier and in which the absorber layer at least partially contains copper, at least one element from the group of indium and gallium and at least one element from the group of selenium and sulfur and in which the absorber layer is at least partially p-type.
Die Erfindung betrifft darüber hinaus ein Verfahren zur Herstellung einer Solarzelle, bei dem ein flexibler und bandförmiger Träger mit einer Absorberschicht versehen wird und bei der die Absorberschicht mindestens teilweise aus Kupfer, mindestens einem Element aus der Gruppe Indium und Gallium sowie mindestens einem Element aus der Gruppe Selen und Schwefel hergestellt wird sowie bei dem die Absorberschicht mindestens bereichs- weise mit p-leitenden Eigenschaften versehen wird.The invention further relates to a method for producing a solar cell, in which a flexible and ribbon-shaped support is provided with an absorber layer and in which the absorber layer is at least partially made of copper, at least one element from the group indium and gallium and at least one element from the group Selenium and sulfur is produced and in which the absorber layer is provided with p-conducting properties at least in some areas.
Dünnschicht-Solarzellen werden in aller Regel hergestellt, indem zunächst eine transparente, elektrisch leitende Schicht auf spezielles Silikatglas (Solarglas) aufgebracht und nachfolgend im Hochvakuum Silizium mit verschiedener Dotierung aufgedampft wird. Als Deckschicht wird wiederum eine leitfähige Schicht aufgebracht, die jedoch nicht lichtdurchlässig zu sein braucht. Durch die Benutzung von Masken, einer Auftren- nung der Schichten mittels Laser und der sukzessiven Abfolge der beschriebenen Bearbeitungsgänge wird die Geamtfläche so strukturiert, daß eine Vielzahl einzel- ner Zellen entsteht, die elektrisch in Serie verschaltet sind. Durch Kontaktierung, rückseitige Schutzabdek- kung und Rahmung der gesamten Struktur entsteht ein Dünnschicht-Solarmodul, das zur Umwandlung von Lichtenergie in elektrische Leistung (regenerative Stromerzeugung) dient. Es sind auch bereits Solarmodule bekannt, bei welchen statt des Siliziums Kupfer-Indium- Selenid (CIS) auf Glas aufgedampft wurde.Thin-film solar cells are generally produced by first applying a transparent, electrically conductive layer to special silicate glass (solar glass) and then vapor-deposition silicon with various doping. In turn, a conductive layer is applied as the cover layer, but this does not need to be translucent. Through the use of masks, a separation of the layers using a laser and the successive sequence of the processing steps described, the entire area is structured in such a way that a large number of individual cells that are electrically connected in series. Through contacting, protective cover on the back and framing of the entire structure, a thin-film solar module is created which is used to convert light energy into electrical power (regenerative power generation). Solar modules are also known in which copper-indium-selenide (CIS) was vapor-deposited on glass instead of silicon.
Unter dem Handelsnamen UNISOLAR sind Solarmodule verfügbar, bei welchen Silizium im Hochvakuum auf ein langes Edelstahlband aufgedampft wurde ( "roll-to-roll"- Verfahren) . Das Band wird anschließend an den unbe- dampften Stellen zerschnitten und die einzelnen Zellen elektrisch und mechanisch zu Solarmodulen zusammengefügt. Eine Besonderheit ist hierbei die Herstellung von Tandem- oder Triple-Zellen, bei welchen zwei oder drei spektral unterschiedlich empfindliche Silizium-Zellen übereinander geschichtet werden. Eine derartige Tandem- Zelle auf Glas-Substrat, im Hochvakuum hergestellt, wurde bereits auch in CIS-Technologie vom Hahn-Meitner- Institut Berlin erzeugt und auf der Technischen Messe in Hannover 1998 erstmals gezeigt.Solar modules are available under the trade name UNISOLAR, in which silicon was vapor-deposited on a long stainless steel strip in a high vacuum ("roll-to-roll" process). The tape is then cut at the non-vaporized points and the individual cells are electrically and mechanically combined to form solar modules. A specialty here is the production of tandem or triple cells, in which two or three spectrally differently sensitive silicon cells are layered on top of one another. Such a tandem cell on a glass substrate, manufactured in a high vacuum, was already produced in CIS technology by the Hahn-Meitner-Institut Berlin and was shown for the first time at the 1998 technical fair in Hanover.
Bekannt ist es ebenfalls, eine schmale, quasi endlos lange CIS- "Bandzelle" unter Verwendung eines Kupferbandes herzustellen. Dies wird in der DE 196 34 580 beschrieben. Hier wird das Kupferband zunächst galvanisch mit Indium beschichtet, dann läßt man in einem "Graphit-Reaktor" eine Schwefelatmosphäre bei hoher Temperatur auf das rasch durchlaufende Band einwirken. Da die sonst übliche p-Leitfähigkeit der Absorberschicht anscheinend nicht erreicht wird, muß nachfolgend eine p-leitende, transparente Schicht aufgebracht werden, bevor die übliche, n-leitende, transparente Deckschicht den Abschluß bildet.It is also known to produce a narrow, quasi-endlessly long CIS "band cell" using a copper band. This is described in DE 196 34 580. Here the copper strip is first galvanically coated with indium, then a sulfur atmosphere is allowed to act on the rapidly passing strip in a "graphite reactor" at high temperature. Since the usual p-conductivity of the absorber layer does not appear to be achieved, a p-conductive, transparent layer must subsequently be applied before the usual, n-type, transparent cover layer forms the end.
Für die Herstellung von Modulen aus derartigen, extrem schmalen CIS-Bandzellen wird in der DE 196 34 580 vorgeschlagen, die ansich bekannte Schindeltechnik zu benutzen, wobei die Frage unerwünschter Kontakte zwischen dem Kupfer und den leitenden Deckschichten an den Rändern und den Schnittstellen des Bandes offen bleibt.For the production of modules from such extremely narrow CIS band cells, DE 196 34 580 proposes to use the shingle technique known per se, the question of undesirable contacts between the copper and the conductive cover layers at the edges and the interfaces of the band being open remains.
Die elektrochemische Deposition von CIS ist in den Veröffentlichungen "Darstellung und Charakterisierung von CuGaS2 Dünnfilmsolarzellen", Dissertation M. Mehlin, TU Berlin 1994, "Elektronische Abscheidung ternärer Ber- bindungshalbleiter" , Dr. M. Reiter, HMI Berlin 1996 und "Injektionsanoden zur kontinuierlichen elektrochemischen Abscheidung", Disseration R. Freitag, TU Berlin ebenfalls beschrieben worden. Es werden verschiedene, elektrochemische Abscheideverfahren vorgeschlagen, auch die ternäre Deposition von Kupfer, Indium und Selen gleichzeitig. Da die so erzeugte Kristallstruktur pho- tovoltaisch ungenügend geeignet ist, müssen die erzeugten Zellen einem Temperprozeß unterworfen werden, wobei sie häufig gleichzeitig einer Atmosphäre aus Selendampf ausqesetzt werden. Anschließend werden Deckschichten zur Ableitung des Photostromes aufgebracht, die jedoch nicht transparent sein müssen.The electrochemical deposition of CIS is described in the publications "Representation and Characterization of CuGaS 2 Thin Film Solar Cells", dissertation M. Mehlin, TU Berlin 1994, "Electronic deposition of ternary compound semiconductors", Dr. M. Reiter, HMI Berlin 1996 and "Injection anodes for continuous electrochemical deposition", dissertation R. Freitag, TU Berlin have also been described. Various electrochemical deposition processes are proposed, including the ternary deposition of copper, indium and selenium at the same time. Since the crystal structure produced in this way is insufficiently suitable for photovoltaics, the cells produced have to be subjected to an annealing process, whereby they are often simultaneously exposed to an atmosphere of selenium vapor. Cover layers are then applied to derive the photocurrent, but they do not have to be transparent.
Hervorzuheben ist, daß derartige, elektrochemisch erzeugte CIS Zellen in allen bekannt gewordenen Beispielen auf Glas aufgebaut, d.h. weder flexibel waren noch im kontinuierlichen Betrieb, wie bei einer Bandzelle hergestellt werden konnten. Man beachte auch, daß bei diesen Zellen die Lichteinfallsrichtung umgekehrt ist, nämlich durch das Glas hindurch, was eine deutlich andere Problemstellung des Schichtenaufbaues ergibt.It should be emphasized that such electrochemically produced CIS cells in all known examples are built on glass, ie they were neither flexible nor in continuous operation, as could be produced with a band cell. It should also be noted that the direction of light incidence is reversed for these cells, namely through the glass, which results in a significantly different problem of the layer structure.
Aufgabe der vorliegenden Erfindung ist es daher, eine Solarzelle der einleitend genannten Art derart zu konstruieren, daß sowohl geringe Fertigungskosten als auch ein hoher elektrischer Wirkungsgrad erreicht wird.The object of the present invention is therefore to construct a solar cell of the type mentioned in the introduction in such a way that both low production costs and high electrical efficiency are achieved.
Die Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Absorberschicht mindestens zum Teil galvanisch auf den Träger aufgebracht ist, daß die Bestandteile der Absorberschicht relativ zueinander in einem stöchiome- . trischen Verhältnis vorliegen und daß die Absorberschicht nach ihrem Aufbringen auf den Träger wärmebehandelt ist .The object is achieved in that the absorber layer is at least partially applied galvanically to the carrier, that the components of the absorber layer are relative to each other in a stoichiometric. trical ratio and that the absorber layer is heat-treated after its application to the carrier.
Weitere Aufgabe der vorliegenden Erfindung ist es, ein Verfahren der einleitend genannten Art derart zu verbessern, daß eine großtechnische Fertigung der Solarzellen bei günstigen Herstellungspreisen unterstützt wird.Another object of the present invention is to improve a method of the type mentioned in the introduction in such a way that large-scale production of the solar cells is supported at low production prices.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Absorberschicht mindestens zum Teil galvanisch auf den Träger aufgebracht wird, daß die Bestandteile der Absorberschicht relativ zueinander in einem stöchiome- trischen Verhältnis abgeschieden werden und daß die Absorberschicht nach ihrem Aufbringen auf den Träger einer Wärmebehandlung unterworfen wird.This object is achieved according to the invention in that the absorber layer is at least partially applied galvanically to the carrier, in that the constituents of the absorber layer are deposited in a stoichiometric ratio relative to one another and in that the absorber layer is subjected to a heat treatment after it has been applied to the carrier.
Insbesondere ist es möglich, daß im zweiten Schritt das Band kontinuierlich oder getaktet durch mehrere "galvanische" Bäder geführt wird, wobei CIS (Kupfer, Indium und Selen) auf den Zellenbereichen elektröche- misch homogen abgeschieden wird.In particular, it is possible that in the second step the strip is guided continuously or clocked through several "galvanic" baths, with CIS (copper, indium and selenium) being electromechanical on the cell areas. is mixed homogeneously.
Auf diese galvanisch erzeugten Schichten kann in einem dritten Schritt eine weitere, homogene Kupferabdeckschicht vorzugsweise galvanisch aufgetragen werden oder alternativ ein Kupfer-Doping durchgeführt werden.In a third step, a further, homogeneous copper cover layer can preferably be applied galvanically to these galvanically produced layers or, alternatively, copper doping can be carried out.
Das Band kann in einem nachfolgenden vierten Schritt durch einen sogenannten "Lampenofen" geführt werden, wobei durch eine zeitlich und temperaturmäßig genau dosierte Erwärmung der beschichteten Bereiche in einer inerten Atmosphäre die Durchmischung und der mikrokristalline Aufbau der CIS - Schicht optimiert wird.In a subsequent fourth step, the strip can be passed through a so-called "lamp oven", the mixing and the microcrystalline structure of the CIS layer being optimized by heating the coated areas in a precisely metered manner in terms of time and temperature.
In einem fünften Schritt kann die Deckschicht aus metallischem Kupfer und eine ggf. darunter befindliche Schicht aus Kupferselen selektiv ätztechnisch entfernt werden.In a fifth step, the cover layer made of metallic copper and a layer of copper selenium which may be located below it can be selectively removed by etching.
Im anschließenden sechsten und letzten Schritt kann auf das ganze Band eine transparente, n-leitende Deckschicht, beispielsweise Zinkoxid, aufgebracht werden.In the subsequent sixth and final step, a transparent, n-conductive cover layer, for example zinc oxide, can be applied to the entire strip.
Im Anschluß an die beispielsweise beschriebene Herstellung des Solarzellenbandes wird der flexible Träger im Bereich der Isolierschicht zerschnitten, so daß Einzelzellen entstehen, deren Deckschicht (ITO) und Grundschicht elektrisch leitend, jedoch zuverlässig voneinander isoliert sind.Following the production of the solar cell tape described as an example, the flexible carrier is cut in the area of the insulating layer, so that individual cells are formed whose top layer (ITO) and base layer are electrically conductive, but are reliably insulated from one another.
Das erfindungsgemäß vorgeschlagene Verfahren kann derart durchgeführt werden, daß ein etwa 35 mm breites und Bruchteile eines Millimeters dickes Edelstahlband verwendet wird. Dies hat den Vorteil, daß eine Breite von 35 mm ein internationaler Standard bei flexiblen Leiterplatten ist, wodurch apparative Vorteile bei der Solarzellenherstellung entstehen. Weiterhin wird die Anzahl der Kontakte beim Verschalten der Zellen zu Modulen, die auch bei der Schindeltechnik ein gewisses Problem darstellt, gegenüber einer beispielsweise nur 10 mm breiten Bandzelle erheblich reduziert.The method proposed according to the invention can be carried out in such a way that an approximately 35 mm wide and fractional millimeter thick stainless steel strip is used. This has the advantage that a width of 35 mm is an international standard for flexible printed circuit boards, which creates equipment advantages in the manufacture of solar cells. Furthermore, the number of contacts when the cells are connected to modules, which also presents a certain problem in shingle technology, is considerably reduced compared to a band cell that is only 10 mm wide, for example.
Aufgrund der größeren Breite werden höhere Anforderungen an die elektrische Leitfähigkeit der transparenten Deckschicht gestellt, dies ist nach der vorliegenden Erfindung aber kein Problem. Anstatt die Kupfer- Deckschicht ätztechnisch völlig zu entfernen, bleiben einzelne Leiterbahnen aus Kupfer stehen und dienen als niederohmige Ableitung von Ladungsträgern, ähnlich dem bei kristallinen Solarzellen üblichen "grid" . Ein weiterer, entscheidender Vorteil des Trägermaterials besteht darin, daß ein Eindiffundieren von Fremdatomen in die CIS-Schicht durch einfache Isolierschichten vermieden werden kann.Due to the larger width, higher requirements are placed on the electrical conductivity of the transparent cover layer, but this is not a problem according to the present invention. Instead of completely removing the copper cover layer by etching, individual copper conductor tracks remain and serve as low-resistance derivation of charge carriers, similar to the "grid" common with crystalline solar cells. A further, decisive advantage of the carrier material is that a diffusion of foreign atoms into the CIS layer can be avoided by simple insulating layers.
Erfindungsgemäß kann weiter eine Isolierschicht aus einem elektrisch nicht leitenden und hoch temperaturbeständigen Material auf den Träger so aufgetragen werden, daß abgegrenzte, unbeschichtete Bereiche entstehen, auf welchen später das CIS abgeschieden wird. Es entstehen somit diskrete Bereiche ("Zellen"), während zugleich ein kontinuierliches oder getaktetes Durchwandern der nachfolgenden Verfahrensschritte "am laufenden Band" möglich ist. Der Nachteil einer sehr schmalen und endlos langen Bandzellen, daß nämlich an den seitlichen Kanten und den späteren Schnittstellen Undefinierte Verhältnisse, ggf. sogar Kurzschlüsse entstehen können, wird so von vorn herein vermieden. Anschließend wird das so in diskrete Zellenbereiche eingeteilte Band durch chemische Bäder geleitet, wobei die Oberfläche derartig behandelt wird, daß eine Haftung der nachfolgenden CIS- Absorberschicht auch dann gewährleistet ist, wenn die Zelle flexibel verformt wird.According to the invention, an insulating layer made of an electrically non-conductive and highly temperature-resistant material can also be applied to the carrier in such a way that delimited, uncoated areas are formed, on which the CIS is later deposited. This creates discrete areas ("cells"), while at the same time continuous or clocked walking through the subsequent process steps "on the conveyor belt" is possible. The disadvantage of a very narrow and endlessly long band cells, namely that undefined conditions, possibly even short circuits, can arise at the lateral edges and the later interfaces, is avoided from the outset. Then will the band thus divided into discrete cell areas is passed through chemical baths, the surface being treated in such a way that adhesion of the subsequent CIS absorber layer is ensured even if the cell is flexibly deformed.
Im zweiten Schritt wird in den so vorbereiteten Zellenbereichen nach ansich bekannten Methoden ternär, d.h. gleichzeitig, Kupfer, Indium und Selen elektrochemisch im Durchlauf durch ein entsprechendes Bad abgeschieden. Hierbei sind Vorkehrungen zu treffen, daß die Konzentration der Elektrolyte konstant bleibt, daß keine Gas- blasen an der Schicht haften (Gefahr von "pinholes") und daß andere Inhomogenitäten vermieden werden.In the second step, ternary, i.e. at the same time, copper, indium and selenium are deposited electrochemically in one pass through an appropriate bath. Precautions must be taken to ensure that the concentration of the electrolytes remains constant, that no gas bubbles adhere to the layer (risk of "pinholes") and that other inhomogeneities are avoided.
Es kann sich als zweckmäßig erweisen, statt der ternä- ren Abscheidung die Deposition der Elemente in Teil- schritte zu zerlegen, also beispielsweise zunächst binär Indium+Selen und anschließend Kupfer aufzubringen. Gewisse Vorteile entstehen, wenn zunächst binär Kup- fer+Selen, dann Indium+Selen gleichzeitig abgeschieden werden. Für die "Durchmischung" sorgt nachfolgend die Erhitzung im Lampenofen, wobei die Temperatur, die Verweilzeit sowie die Erwärmungs- und Abkühlungsgradienten je nach gewähltem Schichtaufbau anders zu optimieren sind.Instead of ternary deposition, it can prove to be expedient to break down the deposition of the elements into sub-steps, for example first applying binary indium + selenium and then copper. Certain advantages arise if first binary copper + selenium, then indium + selenium are deposited at the same time. The "mixing" is then carried out by heating in the lamp furnace, the temperature, the residence time and the heating and cooling gradients having to be optimized differently depending on the layer structure selected.
Im dritten Schritt wird, sofern nicht zuvor schon Kupfer als letzte Schicht des Absorbers abgeschieden wurde, eine homogene metallische Schicht aus Kupfer, vorzugsweise durch elektrochemische Deposition, deckend auf die unterliegenden Cu-In-Se-Schichten aufgebracht . Im vierten Schritt wird das Band in einen Temperofen geführt, wobei es vorteilhaft erscheint, dem Band die erforderliche Wärmeenergie nicht durch Wärmeleitung, sondern durch Wärmestrahlung zuzuführen. Bei dem erfindungsgemäß verwendeten "LampenOfen" lassen sich die Temperatur, der zeitliche Gradient der Erwärmung (was für den Kristallisationsprozeß wichtig zu sein scheint) und die Verweilzeit beliebig einrichten. Durch Kühlung der Auflagefläche und/oder Einblasen von gekühltem Schutzgas wird der Abkühlungsprozeß hinsichtlich Geschwindigkeit und Verlauf (unten nach oben oder umgekehrt) gesteuert. Im Gegensatz zu dem bekanntgewordenen "Graphit-Reaktor" nach der DE 196 34 589 werden dadurch, insbesondere bei getaktetem Bandvorschub, die verschiedenen Parameter: Bandgeschwindigkeit, Energieeintrag, Temperatur der umgebenden Atmosphäre usw. weitgehend "entflochten", so daß eine gezielte Steuerung unabhängiger Einzelfaktoren zur Optimierung des Gesamtresultates möglich ist.In the third step, unless copper has already been deposited as the last layer of the absorber, a homogeneous metallic layer made of copper, preferably by electrochemical deposition, is applied to the underlying Cu-In-Se layers. In the fourth step, the strip is fed into an annealing furnace, it being advantageous to supply the strip with the required thermal energy not by heat conduction, but rather by heat radiation. In the "lamp oven" used according to the invention, the temperature, the time gradient of the heating (which seems to be important for the crystallization process) and the residence time can be set up as desired. The cooling process is controlled in terms of speed and course (bottom to top or vice versa) by cooling the contact surface and / or blowing in cooled protective gas. In contrast to the "graphite reactor" according to DE 196 34 589 which has become known, the various parameters: belt speed, energy input, temperature of the surrounding atmosphere, etc. are largely "unbundled" as a result, in particular with clocked belt feed, so that targeted control of independent individual factors is possible to optimize the overall result.
Ein bekanntes Problem beim Tempern von CIS Zellen ist die Flüchtigkeit von Selen, wodurch ein eventuell vorhandenes, optimales stöchometrisches Gleichgewicht zerstört wird. Durch Zufuhr von Selendampf muß hierbei im Temperofen ("Selenisierungsofen") "nachselenisiert" werden; in dem Lampenofen, wie er für die erfindungsgemäße Herstellung von CIS-Zellen verwendet wird, ist dies vermieden, indem einerseits möglichst niedrige Temperaturen verwendet werden, andererseits die Aufhei- zung durch entsprechend starke Lichteinstrahlung auf die abdeckende Kupferschicht des Bandes sehr rasch erfolgt. Soweit dies nicht ausreichend ist, läßt sich ein Überdruck der Schutzgasatmosphäre (z.B Stickstoff) im Lampenofen einstellen. Ein Tempern unter Überdruck setzt die erfindungsgemäße Strukturierung des Bandes in Bereiche und den getakteten Vorschub fast zwangsläufig voraus, dies ist mit einer rasch kontinuierlich durchlaufenden Bandzelle grundsätzlich aber auch durchführbar.A known problem in tempering CIS cells is the volatility of selenium, which destroys any optimal stoichiometric balance that may be present. By adding selenium steam, it is necessary to "re-select" in the tempering furnace ("selenization furnace"); In the lamp furnace, as used for the production of CIS cells according to the invention, this is avoided by, on the one hand, using the lowest possible temperatures, and on the other hand, the heating takes place very quickly by means of correspondingly strong light radiation on the covering copper layer of the strip. If this is not sufficient, an excess pressure of the protective gas atmosphere (eg nitrogen) can be set in the lamp furnace. Annealing under excess pressure the structuring of the band according to the invention in areas and the clocked feed almost inevitably presupposes this, but this can in principle also be carried out with a rapidly continuously running band cell.
Die Einstrahlung von Licht auf die Oberseite des Bandes führt zu einem Temperaturgradienten in der Schicht, der vorteilhaft sein kann, bezüglich der Diffusion aus dem Band heraus oder bezüglich der Belastung unterer Schichten beim Aufbau einer Tandem-Zellstruktur.The irradiation of light on the upper side of the band leads to a temperature gradient in the layer, which can be advantageous with regard to the diffusion out of the band or with regard to the load on lower layers when building a tandem cell structure.
Nach dem Verlassen des Lampenofens wird das Band im fünften Prozeßschritt die Kupfer-Deckschicht ätztechnisch weitgehend wieder entfernt, d.h. vorteilhafterweise bleiben einzelne Leiterbahnen aus Cu stehen, die anstelle des bei kristallinen Solarzellen üblichen, meist mit Silberpaste aufgedruckten Gitters ("grid") die niederohmige Ableitung der durch die Photonen- Absorbtion und Feldtrennung erzeugten Elektronen übernehmen.After leaving the lamp furnace, the strip is largely removed by etching in the fifth process step, i.e. Advantageously, individual conductor tracks made of Cu remain, which take over the low-resistance derivation of the electrons generated by the photon absorption and field separation instead of the grid (usually "printed" with silver paste), usually printed with silver paste.
Zusätzlich wird, in einem sechsten und letzten Schritt, die "freigeätzte" Oberfläche der Zelle mit einer transparenten, elektrisch hoch leitfähigen Deckschicht ("ITO Fenster-Elektrode") versehen. Dies geschieht beispielsweise durch Spraypyrolyse von Zinkoxid; von Vorteil ist, daß der Zellenbereich in Schritt 1 durch einen Isolator abgegrenzt wurde, so daß nun eine genaue Abgrenzung der durch das Besprühen betroffenen Gebiete nicht erforderlich ist: ein Auftrag der elektrisch leitenden Schicht über den Zellenrand hinaus führt nicht zu Kurzschlüssen oder Nacharbeiten. Durch Zerschneiden des Bandes außerhalb der Zellenbereiche entstehen die fertigen, beispielsweise 40 cm langen und 35 mm breiten CIS-Solarzellen. Sie werden vorzugsweise, anstelle der in der DE 196 34 589 vorgeschlagenen, schindelartigen Verschaltung, mittels zwischengelegter "spacers" elektrisch miteinander verschaltet. Die fertige Anordnung von beispielsweise 40 Zellen in Reihenschaltung wird in einem sogenannten "Laminator1 in einem leichten Vakuum unter Druck und Wärmeeinwirkung vorderseitig mit einer transparenten TEDLAR° Folie und auf der Rückseite mit der in der Solartechnik üblichen EVA-Folie abgedeckt und gegen Witterungseinflüsse geschützt. Die so entstandene Anordnung von Solarzellen nennt man ein "Laminat"; dieses wird zu einem "Standard-Solarmodul" dadurch weiterverarbeitet, daß es mit einem Rahmen und einer Kabel- Anschlußdose versehen wird.In addition, in a sixth and final step, the "etched free" surface of the cell is provided with a transparent, highly electrically conductive cover layer ("ITO window electrode"). This is done, for example, by spray pyrolysis of zinc oxide; It is advantageous that the cell area was delimited in step 1 by an insulator, so that an exact delimitation of the areas affected by the spraying is now not necessary: applying the electrically conductive layer beyond the cell edge does not lead to short circuits or reworking. The finished, for example 40 cm long and 35 mm wide, CIS solar cells are produced by cutting the tape outside the cell areas. Instead of the shingle-like connection proposed in DE 196 34 589, they are preferably electrically connected to one another by means of interposed "spacers". The finished arrangement of, for example, 40 cells in series connection is covered in a so-called "laminator 1 in a slight vacuum under pressure and heat on the front with a transparent TEDLAR ° film and on the back with the EVA film customary in solar technology and protected against weather influences. The resulting arrangement of solar cells is called a "laminate", which is further processed into a "standard solar module" by providing it with a frame and a cable junction box.
Neuerdings werden flexible Laminate, durchaus auch mit geringeren Wirkungsgraden (z.B. 6 %) , auf Dach-Elemente bzw. -materialien aus Stahlblech, Kunststoff, Zinkblech o.a. aufgeklebt ("Bonding-Prozeß") und als BIPV "building integrated photo voltaic" bezeichnet. Die überwiegend galvanisch erzeugte, flexible CIS- Dünnschichtzelle gemäß der vorliegenden Erfindung ist hervorragend geeignet für die Herstellung derartiger, solarer Dachelemente zur Stromerzeugung aus Tageslicht, ohne Umweltbelastung und mit bisher unerreicht niedrigen Kosten.Recently, flexible laminates, even with lower efficiencies (e.g. 6%), have been applied to roof elements or materials made of sheet steel, plastic, zinc sheet or similar. glued on ("bonding process") and referred to as BIPV "building integrated photo voltaic". The predominantly electroplated, flexible CIS thin-film cell according to the present invention is excellently suitable for the production of such solar roof elements for generating electricity from daylight, without environmental pollution and with unprecedented low costs.
Hierdurch soll auch umfaßt werden, daß der Träger aus mindestens einem Metall besteht und die Rückelektrode der Solarzelle bildet, daß die Absorberschicht mindestens zum Teil galvanisch auf den Träger aufgebracht ist, daß die Bestandteile der Absorberschicht Kupfer, Indium/Gallium und Selen/Schwefel im stöchometrischen Verhältnis 1:1:2 oder mit einem geringfügigem Selen- Überschuß vorliegen und daß die Absorberschicht nach ihrem Aufbringen auf den Träger in einer Vorrichtung derartig wärmebehandelt wird, daß sie in reines, einphasiges kristallines Kupfer-Indium/Gallium- Diselenid/Sulfid mit mindestens bereichsweise p- leitender Charakteristik umgewandelt wird.This is also intended to include the fact that the carrier consists of at least one metal and the back electrode of the solar cell forms that the absorber layer is at least partially applied galvanically to the carrier is that the constituents of the absorber layer copper, indium / gallium and selenium / sulfur are present in a stoichometric ratio of 1: 1: 2 or with a slight excess of selenium and that the absorber layer is heat-treated in a device after it has been applied to the carrier in such a way that it is converted into pure, single-phase crystalline copper indium / gallium diselenide / sulfide with at least some p-type characteristics.
Ferner ist es vorteilhaft, daß vor dem Aufbringen der Absorberschicht eine oder mehrere Anpaß- , Grund- , Kontakt - oder Haftschichten vorzugsweise durch elektrochemische Deposition aufgebracht werden, beispielsweise eine Grundschicht von Molybdän.Furthermore, it is advantageous that one or more matching, base, contact or adhesive layers, for example a base layer of molybdenum, are applied before the application of the absorber layer, preferably by electrochemical deposition.
Weiterhin ist vorgesehen, daß die Schichten, welche den Absorber bilden, durch sequenzielle elektrochemische Deposition der Metalle Kupfer, Indium/Gallium sowie Selen oder durch binäre Abscheidung von Verbindungshalbleitern nach der Formel "Cu2Se plus In2Se3/Ga2Se3 gleich 2 Culn/GaSe2" oder durch ternäre Abscheidung oder durch ein Gemisch von Metallabscheidung und Abscheidung von Verbindungshalbleitern, wie Cu, In2Se3/Ga2Se3, Se mit einer genau bestimmten Dicke derart erfolgt, daß stöchometrisch richtige Anteilεver- hältnisse oder ein geringer Selenüberschuß vorhanden sind.Furthermore, it is provided that the layers which form the absorber by sequential electrochemical deposition of the metals copper, indium / gallium and selenium or by binary deposition of compound semiconductors according to the formula "Cu2Se plus In2Se3 / Ga2Se3 equal to 2 Culn / GaSe2" or by ternary Deposition or by a mixture of metal deposition and deposition of compound semiconductors such as Cu, In2Se3 / Ga2Se3, Se takes place with a precisely determined thickness in such a way that the proportions are correct or a small excess of selenium is present.
Zusätzlich wird vorgeschlagen, daß nach oder vorzugsweise während der Deposition des Absorbers eine natri- umhaltige Verbindung, beispielsweise Natriumselenid, abgeschieden wird. Ferner wird vorgeschlagen, daß die Bestandteile der Absorberschicht durch Erwärmung auf Temperaturen über 500° Celsius unter ein Schutzgas-Atmosphäre zu einer einheitlichen, reinen und p-leitenden CIS2-Schicht "umkristallisiert" wurden, wobei durch einen sehr raschen Temperaturanstieg sowie durch kurze Dauer der Erwärmung, durch ein sehr kleines Raumvolumen über der Absorberschicht und/oder durch einen Überdruck der Schutzgas-Atmosphäre ein Abdampfen von Selen/Schwefel und eine Bildung anderer, kristalliner Phasen verhindert oder erschwert wird.It is additionally proposed that a sodium-containing compound, for example sodium selenide, be deposited after or preferably during the deposition of the absorber. It is also proposed that the constituents of the absorber layer were "recrystallized" by heating to temperatures above 500 ° Celsius under a protective gas atmosphere to form a uniform, pure and p-conducting CIS2 layer, with a very rapid rise in temperature and a short duration of the Heating, by a very small volume above the absorber layer and / or by an overpressure of the protective gas atmosphere, evaporation of selenium / sulfur and the formation of other crystalline phases is prevented or made more difficult.
In der Zeichnung sind Ausführungsbeispiele der Erfindung schematisch dargestellt. Es zeigen:Exemplary embodiments of the invention are shown schematically in the drawing. Show it:
Fig. 1: eine Prinzipdarstellung einer Absorberschicht, die auf einem flexiblen Träger angeordnet ist,1: a schematic representation of an absorber layer which is arranged on a flexible carrier,
Fig. 2: eine Draufsicht auf die Anordnung gemäß Fig. 12: a top view of the arrangement according to FIG. 1
undand
Fig. 3: ein Beispiel für den Aufbau eines Wärmebehandlungsofens .Fig. 3: an example of the structure of a heat treatment furnace.
Fig. 1 zeigt einen flexiblen Träger (1) , der mit einer Oberfläche (2) versehen ist, auf der eine Absorberschicht (3) angeordnet ist. Entlang von Randbereichen erstrecken sich Isolierschichten (4) und auf die Absorberschicht (3) ist bei dieser Ausführungsform eine Deckschicht (5) aus Kupfer aufgebracht. Alternativ kann aber auch beispielsweise eine Dotierung mit Kupfer rea- lisiert werden. Im Bereich der dem Träger (1) abgewandten Seite der Absorberschicht (3) wird eine Deckschicht (6) angeordnet, die beispielsweise als ITO-Schicht aus-, gebildet sein kann.Fig. 1 shows a flexible carrier (1) which is provided with a surface (2) on which an absorber layer (3) is arranged. Insulating layers (4) extend along edge regions and a copper cover layer (5) is applied to the absorber layer (3) in this embodiment. Alternatively, doping with copper can also be used, for example. be lized. In the area of the side of the absorber layer (3) facing away from the carrier (1), a cover layer (6) is arranged, which can be formed, for example, as an ITO layer.
Aus der Draufsicht in Fig. 2 ist erkennbar, daß ein bandartiger Aufbau vorliegt.From the top view in Fig. 2 it can be seen that there is a band-like structure.
Fig. 3 beschreibt beispielsweise den Aufbau einer Einrichtung zur Temperaturbehandlung. Der flexible Träger (1) wird von einer Rolle (7) abgewickelt und durch einen Innenraum (8) der Temperierungseinrichtung (9) hindurchgeführt. Auf dem Träger (1) befinden sich die Deckschicht (5) sowie Zwischenzellenbereiche (10) . In Förderrichtung neben der Absorberschicht (3) ist ein Material (11) aufgebracht, das beispielsweise Schwefel oder Selen sein kann. Die Temperiereinrichtung (9) weist eine transparente untere Abdeckung (12) und eine semitransparente obere Abdeckung (13) auf. Im Bereich des Innenraumes (8) ist eine Schutzgasatmosphäre angeordnet und der Innenraum (8) wird von einem lichtdurchlässigen Gehäuse (14) umschlossen.3 describes, for example, the construction of a device for temperature treatment. The flexible carrier (1) is unwound from a roll (7) and passed through an interior (8) of the temperature control device (9). The cover layer (5) and intermediate cell areas (10) are located on the carrier (1). A material (11), which can be sulfur or selenium, for example, is applied in the conveying direction next to the absorber layer (3). The temperature control device (9) has a transparent lower cover (12) and a semi-transparent upper cover (13). A protective gas atmosphere is arranged in the area of the interior (8) and the interior (8) is enclosed by a translucent housing (14).
Unterhalb des Gehäuses (14) sind Wärmestrahler (15) eines ersten Regelkreises angeordnet und oberhalb des Gehäuses (13) sind Wärmestrahler (16) eines zweiten Regelkreises sowie Wärmestrahler (17) eines dritten Regelkreises positioniert. Die Wärmestrahler (15) des ersten Regelkreises liegen hierbei im wesentlichen den Wärmestrahlern des dritten Regelkreises gegenüber. Die Wärmestrahler des zweiten Regelkreises sind in Transportrichtung des Trägers (1) von der Rolle (7) bis zu einer Aufwickelrolle (18) vor beziehungsweise hinter den Wärmestrahlern (17) des dritten Regelkreises ange- ordnet .Heat radiators (15) of a first control circuit are arranged below the housing (14) and heat radiators (16) of a second control circuit and heat radiators (17) of a third control circuit are positioned above the housing (13). The heat radiators (15) of the first control loop are essentially opposite the heat radiators of the third control loop. The heat radiators of the second control circuit are arranged in the transport direction of the carrier (1) from the roll (7) to a take-up roll (18) in front of or behind the heat radiators (17) of the third control circuit. arranges.
Die untere Abdeckung (12) ist mit einer Kühlung (19) versehen, die beispielsweise aus Kühlkanälen ausgebildet sein kann, die von einem kühlenden Medium durchströmt sind. Zur Vermeidung eines Entweichens der Schutzgasatmosphäre aus dem Innenraum (8) heraus sind im Einlaßbereich und im Auslaßbereich des Gehäuses (14) Schleusen (20) angeordnet.The lower cover (12) is provided with cooling (19), which can be formed, for example, from cooling channels through which a cooling medium flows. To prevent the protective gas atmosphere from escaping from the interior (8), locks (20) are arranged in the inlet area and in the outlet area of the housing (14).
Der Träger (1) kann aus unterschiedlichen Materialien ausgebildet sein. Insbesondere ist an die Verwendung von Kupfer gedacht. Alternativ sind aber auch Stahlbänder oder Trägermaterialien aus flexiblen Kunststoffen verwendbar .The carrier (1) can be made of different materials. In particular, the use of copper is thought of. Alternatively, steel strips or carrier materials made of flexible plastics can also be used.
Im Hinblick auf die Isolierschicht (4) sind unterschiedliche Realisierungen denkbar. Gemäß der in den Figuren dargestellten Ausführungsform ist die Isolierschicht (4) derart angeordnet, daß die Zellenbereiche frei bleiben. Alternativ ist es aber auch möglich, die Isolierschicht (4) beispielsweise aus Keramik auszubilden und mit dieser den gesamten Träger (1) abzudecken. Dies ist insbesondere bei einer konstruktiven Realisierung des Trägers (1) aus Kupfer von Vorteil, da hierdurch ein Eindiffundieren von Kupferatomen in die Absorbeschicht (3) vermieden wird. Da der Ausdehnungsquotient von Keramik und Glas sehr ähnlich ist, ist die Verwendung von Keramik als Isolierschicht für CIS- Zellen vorteilhaft .Different realizations are conceivable with regard to the insulating layer (4). According to the embodiment shown in the figures, the insulating layer (4) is arranged in such a way that the cell areas remain free. Alternatively, however, it is also possible to form the insulating layer (4) from ceramic, for example, and to cover the entire carrier (1) with it. This is particularly advantageous when the support (1) is made of copper, since it prevents copper atoms from diffusing into the absorber layer (3). Since the expansion quotient of ceramic and glass is very similar, the use of ceramic as an insulating layer for CIS cells is advantageous.
Bei der Verwendung einer den gesamten Träger bedeckenden Isolierschicht (4) wird als zweite Schicht eine Rück-Elektrode verwendet. Alternativ zu der erläuterten Aufrauhung des TrägersWhen an insulating layer (4) covering the entire carrier is used, a back electrode is used as the second layer. As an alternative to the described roughening of the carrier
(1) ist es bei bestimmten Verfahrensvarianten ebenfalls vorteilhaft, eine Glättung der Oberfläche des Trägers(1) it is also advantageous in certain process variants to smooth the surface of the carrier
(1) durchzuführen. Dies kann beispielsweise durch Elek- tropolieren erfolgen.(1) to perform. This can be done, for example, by electropolishing.
Die galvanische Abscheidung der Absorberschicht (4) kann beispielsweise derart erfolgen, daß sequentiell eine elektrochemische Deposition der Metalle Kupfer, Indium und/oder Gallium sowie Selen durchgeführt wird. Alternativ ist es möglich, eine Abscheidung der Verbindungshalbleiter Cu2Se, In2Se3 und/oder Ga2Se3 oder ein Gemisch derselben, z.B. Cu/in2Se3/Se in einem stöchome- trisch richtigen Anteilsverhältnis oder mit einem Selen-Überschuß durchzuführen.The electrodeposition of the absorber layer (4) can be carried out, for example, in such a way that an electrochemical deposition of the metals copper, indium and / or gallium and selenium is carried out sequentially. Alternatively, it is possible to carry out a deposition of the compound semiconductors Cu2Se, In 2 Se 3 and / or Ga 2 Se 3 or a mixture thereof, for example Cu / in2Se 3 / Se in a stoichometrically correct proportion ratio or with an excess of selenium.
Die Wärmebehandlung der Absorberschicht (3) innerhalb des in Fig. 3 beschriebenen Ofens erfolgt bei einem Taktbetrieb des Trägers (1) durch den Ofen hindurch. In dem begrenzten Raumvolumen oberhalb der Absorberschicht (3) wird Schwefel oder Selen dampfförmig zugeführt. Hierdurch werden diese Elemente auf dem Zwischenzellenbereich (10) deponiert. Eine Regelung der Wärmezufuhr ist in mindestens zwei Regelkreise aufgeteilt, so daß die Zellenbereiche und die Zwischenzellenbereiche unterschiedlich erwärmt werden können. Der Schwefel und das Selen im Zwischenzellenbereich wird zunächst verdampft und anschließend dient dieser Bereich zur Kondensation des verbleibenen Dampfes. The heat treatment of the absorber layer (3) within the furnace described in FIG. 3 takes place during the cycle operation of the carrier (1) through the furnace. In the limited volume above the absorber layer (3), sulfur or selenium is supplied in vapor form. As a result, these elements are deposited on the intermediate cell area (10). A regulation of the heat supply is divided into at least two control loops, so that the cell areas and the intermediate cell areas can be heated differently. The sulfur and selenium in the intercell area is first evaporated and then this area is used to condense the remaining steam.

Claims

Patentansprüche claims
1. Solarzelle, die eine Absorberschicht aufweist, die auf einem flexiblen und bandförmigen Träger angeordnet ist und bei der die Absorberschicht mindestens teilweise Kupfer, mindestens ein Element aus der Gruppe Indium und Gallium sowie mindestens ein Element aus der Gruppe Selen und Schwefel enthält sowie bei der die Absorberschicht mindestens bereichsweise p-leitend ausgebildet ist, dadurch gekennzeichnet, daß die Absorberschicht (3) mindestens zum Teil galvanisch auf den Träger (1) aufgebracht ist, daß die Bestandteile der Absorberschicht relativ zueinander in einem stöchiometrischen Verhältnis vorliegen und daß die Absorberschicht (3) nach ihrem Aufbringen auf den Träger (1) wärmebehandelt ist.1.Solar cell which has an absorber layer which is arranged on a flexible and band-shaped carrier and in which the absorber layer contains at least partially copper, at least one element from the group indium and gallium and at least one element from the group selenium and sulfur, and in which the absorber layer is at least partially p-conductive, characterized in that the absorber layer (3) is at least partially galvanically applied to the carrier (1), that the constituents of the absorber layer are present in a stoichiometric ratio relative to one another and that the absorber layer (3 ) is heat-treated after it has been applied to the carrier (1).
2. Solarzelle nach Anspruch 1, dadurch gekennzeichnet, daß der Träger (1) zumindest bereichsweise aus Kupfer ausgebildet ist.2. Solar cell according to claim 1, characterized in that the carrier (1) is formed at least in regions from copper.
3. Solarzelle nach Anspruch 1, dadurch gekennzeichnet, daß der Träger (1) zumindest bereichsweise aus Stahl ausgebildet ist.3. Solar cell according to claim 1, characterized in that the carrier (1) is formed at least in regions from steel.
4. Solarzelle nach Anspruch 1, dadurch gekennzeichnet, daß der Träger (1) zumindest bereichsweise aus Kunststoff ausgebildet ist .4. Solar cell according to claim 1, characterized in that the carrier (1) is at least partially made of plastic.
5. Solarzelle nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Träger (1) teilweise mit einer Isolierschicht (4) bedeckt und hierdurch in Zellenbereiche eingeteilt ist. 5. Solar cell according to one of claims 1 to 4, characterized in that the carrier (1) is partially covered with an insulating layer (4) and is thereby divided into cell areas.
6. Solarzelle nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Träger (1) im wesentlichen vollständig von einer Isolierschicht (4) bedeckt ist .6. Solar cell according to one of claims 1 to 4, characterized in that the carrier (1) is substantially completely covered by an insulating layer (4).
7. Solarzelle nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Absorberschicht (3) mindestens bereichsweise von einer Kupferschicht abgedeckt ist .7. Solar cell according to one of claims 1 to 6, characterized in that the absorber layer (3) is covered at least in regions by a copper layer.
8. Solarzelle nach einem der Ansprüche 1 bis 6 , dadurch gekennzeichnet, daß in die Absorberschicht (3) im Bereich ihrer dem Träger (1) abgewandten Oberfläche Kupferatome eingelagert sind.8. Solar cell according to one of claims 1 to 6, characterized in that copper atoms are embedded in the absorber layer (3) in the region of its surface facing away from the carrier (1).
9. Solarzelle nach einem der Ansprüche 1 bis 8 , dadurch gekennzeichnet, daß die Bestandteile der Absorberschicht (3) durch Temperaturbehandlung rekristallisiert sind.9. Solar cell according to one of claims 1 to 8, characterized in that the components of the absorber layer (3) are recrystallized by temperature treatment.
10. Solarzelle nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, daß die Absorberschicht (3) von einer lichtdurchlässigen Schicht (6) überzogen ist.10. Solar cell according to one of claims 1 to 9, characterized in that the absorber layer (3) is coated by a translucent layer (6).
11. Solarzelle nach Anspruch 10, dadurch gekennzeichnet, daß die Deckschicht (5) elektrisch leitfähig ausgebildet ist .11. Solar cell according to claim 10, characterized in that the cover layer (5) is electrically conductive.
12. Solarzelle nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, daß der Träger (1) als ein Band mit einer Breite von etwa 35 mm ausgebildet ist. 12. Solar cell according to one of claims 1 to 11, characterized in that the carrier (1) is designed as a band with a width of about 35 mm.
13. Verfahren zur Herstellung einer Solarzelle, bei dem eine Absorberschicht auf einem flexiblen und bandförmigen Träger angeordnet wird und bei dem die Absorberschicht mindestens teilweise aus Kupfer, mindestens einem Element aus der Gruppe Idium und Gallium sowie mindestens einem Element aus der Gruppe Selen und Schwefel ausgebildet wird sowie bei der die Absorberschicht mindestens bereichsweise mit p- leitenden Eigenschaften versehen wird, dadurch gekennzeichnet, daß die Absorberschicht (3) mindestens zum teil galvanisch auf den Träger (1) aufgebracht wird, daß die Bestandteile der Absorberschicht (3) in einem stöchiometrischen Verhältnis aufgebracht werden und daß die Absorberschicht (3) nach ihrem Aufbringen auf den Träger (1) wärmebehandelt wird.13. A method for producing a solar cell, in which an absorber layer is arranged on a flexible and ribbon-shaped carrier and in which the absorber layer is at least partially formed from copper, at least one element from the group idium and gallium and at least one element from the group selenium and sulfur and in which the absorber layer is at least partially provided with p-conducting properties, characterized in that the absorber layer (3) is at least partially applied galvanically to the carrier (1), that the constituents of the absorber layer (3) are in a stoichiometric ratio are applied and that the absorber layer (3) is heat-treated after it has been applied to the carrier (1).
14. Verfahren nach Anspruch 13, dadurch gekennzeichnet, daß eine Oberfläche des Trägers (1) vor einem Aufbringen der Absorberschicht (3) geglättet wird.14. The method according to claim 13, characterized in that a surface of the carrier (1) is smoothed before application of the absorber layer (3).
15. Verfahren nach Anspruch 13 oder 14 , dadurch gekennzeichnet, daß die Absorberschicht (3) rekristallisiert wird.15. The method according to claim 13 or 14, characterized in that the absorber layer (3) is recrystallized.
16. Verfahren nach einem der Ansprüche 13 bis 15, dadurch gekennzeichnet, daß eine die Absorberschicht (3) abdeckende Kupferschicht selektiv ätztechnisch entfernt wird.16. The method according to any one of claims 13 to 15, characterized in that a copper layer covering the absorber layer (3) is selectively removed by etching.
17. Verfahren nach einem der Ansprüche 13 bis 16, dadurch gekennzeichnet, daß bei der galvanischen Deposition der Absorberschicht (3) zuerst Selen und Indium und zuletzt Kupfer abgeschieden wird. 17. The method according to any one of claims 13 to 16, characterized in that during the galvanic deposition of the absorber layer (3) first selenium and indium and lastly copper is deposited.
18. Verfahren nach einem der Ansprüche 13 bis 17, dadurch gekennzeichnet, daß die Kupferdeckschicht nur teilweise durch Ätzung abgetragen wird und in definierten Bereichen Leiterbahnen aus Cu stehenbleiben, die eine niederohmige Ableitung der durch die Lichteinstrahlung erzeugten Ladungsträger gewährleisten.18. The method according to any one of claims 13 to 17, characterized in that the copper cover layer is only partially removed by etching and in defined areas conductor tracks made of Cu remain, which ensure a low-resistance derivation of the charge carriers generated by the light radiation.
19. Vorrichtung zur Wärmebehandlung einer Absorberschicht, die auf einem bandförmigen und flexiblen Träger angeordnet ist, der in Zellenbereiche und Zellenzwischenbereiche eingeteilt ist und der takt- weise durch einen Temperierbereich hindurchgeführt wird, dadurch gekennzeichnet, daß in einem begrenzten Raumvolumen oberhalb der Absorberschicht Schwefel oder Selen dampfförmig zugeführt wird, wobei diese Elemente vor einer Einschleusung des Trägers in Zwischenbereichen zwischen der Absorberschicht deponiert sind.19. Device for heat treatment of an absorber layer, which is arranged on a band-shaped and flexible carrier, which is divided into cell areas and intermediate cell areas and which is cyclically passed through a temperature control area, characterized in that sulfur or selenium is present in a limited volume above the absorber layer is supplied in vapor form, these elements being deposited in intermediate areas between the absorber layer before the carrier is introduced.
20. Vorrichtung nach Anspruch 19, dadurch gekennzeichnet, daß die Wärmezufuhr in mindestens zwei Regelkreise aufgeteilt ist.20. The apparatus according to claim 19, characterized in that the heat supply is divided into at least two control loops.
21. Vorrichtung nach Anspruch 19 oder 20, dadurch gekennzeichnet, daß die Wärmezufuhr in drei Regelkreise aufgeteilt ist.21. The apparatus according to claim 19 or 20, characterized in that the heat supply is divided into three control loops.
22. Vorrichtung nach einem der Ansprüche 19 bis 21, dadurch gekennzeichnet, daß die Wärmeeinstrahlung durch ein mindestens bereichsweise transparentes Gehäuse hindurch erfolgt. 22. Device according to one of claims 19 to 21, characterized in that the heat radiation takes place through an at least partially transparent housing.
23. Vorrichtung nach einem der Ansprüche 19 bis 22, dadurch gekennzeichnet, daß das Schwefel und/oder das Selen im Zwischenbereich verdampft und anschließend kondensiert wird.23. Device according to one of claims 19 to 22, characterized in that the sulfur and / or the selenium evaporates in the intermediate region and is then condensed.
24. Vorrichtung nach einem der Ansprüche 19 bis 23, dadurch gekennzeichnet, daß der Innenraum des Ofens abgedichtet ist, um eine Schutzgas-Atmosphäre zu enthalten, wobei diese, um dem Abdampfen von Selen entgegenzuwirken, unter Überdruck stehen kann.24. Device according to one of claims 19 to 23, characterized in that the interior of the furnace is sealed to contain a protective gas atmosphere, which can counteract the evaporation of selenium, can be under pressure.
25. Vorrichtung nach einem der Ansprüche 19 bis 24, dadurch gekennzeichnet, daß die Auflagefläche des Metallbandes im Temperofen regulierbar von einer Kühlflüssigkeit durchströmt oder daß gekühltes Schutzgas über das Zellenband geblasen wird, so daß die Abkühlung der CIS-Schicht mit einem einstellbaren räumlichen und zeitlichen Gradienten erfolgt. 25. Device according to one of claims 19 to 24, characterized in that the contact surface of the metal strip in the tempering furnace controllably flows through a cooling liquid or that cooled protective gas is blown over the cell belt, so that the cooling of the CIS layer with an adjustable spatial and temporal Gradient is done.
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