WO2011142804A1 - Cellules photovoltaïques souples et modules présentant une adhésivité améliorée - Google Patents

Cellules photovoltaïques souples et modules présentant une adhésivité améliorée Download PDF

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Publication number
WO2011142804A1
WO2011142804A1 PCT/US2011/000813 US2011000813W WO2011142804A1 WO 2011142804 A1 WO2011142804 A1 WO 2011142804A1 US 2011000813 W US2011000813 W US 2011000813W WO 2011142804 A1 WO2011142804 A1 WO 2011142804A1
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polymer
layer
carrier
station
cell
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PCT/US2011/000813
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English (en)
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Alvin D. Compaan
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The University Of Toledo
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1864—Annealing
    • 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
    • H01L31/03925—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 including AIIBVI compound materials, e.g. CdTe, CdS
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
    • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same 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
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/048—Encapsulation of modules
    • 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
    • H01L31/073—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 comprising only AIIBVI compound semiconductors, e.g. CdS/CdTe 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1828—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
    • H01L31/1836—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe comprising a growth substrate not being an AIIBVI compound
    • 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
    • Y02E10/543—Solar cells from Group II-VI materials
    • 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 generally to photovoltaic cells (PV cells) and methods for the fabrication thereof. More particularly, the invention relates to a method of manufacturing a flexible PV cell having improved adhesion of active semiconductor layers to a transparent polymer substrate or superstate.
  • PV cells can be used to convert solar energy into electric current.
  • PV cells can include a substrate layer and two ohmic contacts or electrode layers for passing current to an external electrical circuit.
  • the PV cell also includes an active semiconductor junction, usually comprised of two or three semiconductor layers arranged in series.
  • the two-layer type of semiconductor cell consists of an n-type layer and a p-type layer, and the three- layer type includes an intrinsic (i-type) layer positioned between the n-type layer and the p-type layer for absorption of light radiation.
  • the PV cells operate by having readily excitable electrons that can be energized by solar energy to higher energy levels, thereby creating positively charged holes and negatively charged electrons at the interface of various semiconductor layers. The creation of these positive and negative charge carriers applies a net voltage across the two electrode layers in the PV cell, establishing a current of electricity.
  • PV cells are examples of diode structures where light passes through a transparent front window and a transparent electrode layer to energize an active semiconductor junction. Certain characteristics of the transparent electrode layers can impact the ability to pass current to the external electrical circuit in diode structures.
  • Electrode layers Some notable characteristics of these electrode layers are a capability to: 1) conduct electricity to and from the diode structure; and, 2) be substantially transparent to certain light wavelengths (typically greater than 400 nm) so that the solar energy can reach the primary semiconductor layers that form the active semiconductor junction.
  • certain light wavelengths typically greater than 400 nm
  • the restriction on the amount of light that can pass through the conductor layer sets a practical limit on the efficiency of the PV cell.
  • the electrical conductivity of the electrode layer impacts the overall efficiency of a PV cell.
  • Cadmium telluride PV cells are built on glass in a superstrate configuration, taking advantage of glass's transparency, mechanical rigidity, and the opportunity to form the back contact last.
  • glass is heavy, rigid and fragile and these are
  • Polymer materials may be used to replace glass in order to produce flexible PV cell panels.
  • Polymer materials can be sufficiently transparent to admit light in the proper wavelength (i.e., 400 ⁇ to 850 ⁇ ) for CdTe-based PV cells. While being initially flexible and transparent, polymer materials can be degraded, both mechanically and optically, by the processes used to form the remaining layers of the PV cell or PV cell array. Additionally, the flexible nature of polymer-based flexible PV cells puts stress on the interface between the polymer superstrate and the transparent conductive oxide electrode as the structure bends. In certain instances, the bond between the polymer superstrate and the subsequently applied layers may be compromised and therefore weak or nonexistent. When this happens, the PV cell film may pull away from the polymer substrate or superstrate and the device fails. An entire device failure may occur even if only part of the area delaminates.
  • a PV cell that includes an interface layer having an improved bond characteristic between two adjacent layers.
  • the PV cell comprises a flexible polymer-based superstrate layer having an ionically bombarded interface layer between two adjacent layers.
  • the PV cell includes a transparent or translucent primer or tie coat as the interface layer. The primer coat may be applied between two adjacent layers, such as the polymer superstrate layer and a transparent conductive oxide (TCO) layer.
  • the PV cell includes an interface layer that includes a surface of a first layer, such as the polymer superstrate layer, that has been exposed to an etchant or a solvent material. The solvent-formed interface layer has a surface texture characteristic that provides an improved bond characteristic with a subsequently applied layer, such as a TCO layer.
  • a method of producing a PV cell having an improved adhesion characteristic between the layers of a thin-film based CdTe PV cell and a polymer superstrate or substrate layer includes an ionic bombardment process to create an interface layer having an improved bond characteristic.
  • the method includes application of a transparent or translucent primer coating or tie coating that forms the interface layer having the improved bond characteristic.
  • the method includes an etchant or solvent applied to a surface, such as a polymer surface, to create the interface layer.
  • an apparatus for producing a PV cell having an interface layer that exhibits an improved bond characteristic with a subsequently applied PV cell layer may include a roll-to-roll process for producing finished or semi-finished PV cells through processing at a plurality of stations where the PV cell is formed with a polymer front window having an improved bond characteristic with a TCO layer.
  • the apparatus includes an ionic bombardment station to form the interface layer having the improved bond characteristic.
  • the apparatus includes a primer application station to apply a transparent or translucent primer coating or tie coating onto a layer, such as the polymer superstrate layer.
  • the apparatus includes an etchant station or solvent station that forms the interface layer onto the surface of the first layer, such as the polymer superstrate layer.
  • Fig. 1A is a schematic iUustration of a process for making a PV cell that can be used for implementing certain embodiments of the invention.
  • Fig. IB is a schematic illustration of another process for making a PV cell that can be used for implementing certain embodiments of the invention.
  • Fig. 2A is a schematic iUustration of a portion of a process for making a PV cell that can be used for implementing certain embodiments of the invention.
  • FIG. 2B is a schematic illustration of an alternative embodiment of a portion of a process for making a PV cell that can be used for implementing certain embodiments of the invention.
  • FIG. 3 is a schematic illustration of a portion of another process for making a PV cell that can be used for implementing certain embodiments of the invention.
  • Fig. 4A is a schematic illustration of a first step in a process for making a PV cell.
  • Fig. 4B is a schematic illustration of a second step in a process for making a PV cell.
  • Fig. 4C is a schematic iUustration of a third step in a process for making a PV cell.
  • Fig. 4D is a schematic iUustration of a fourth step in a process for making a PV cell.
  • Fig. 4E is a schematic illustration of a fifth step in a process for making a PV cell.
  • FIG. 5 is a schematic illustration of an embodiment of a carrier separation method.
  • FIG. 6 is a schematic illustration of another embodiment of a carrier separation method.
  • FIG. 7 is a schematic illustration of another embodiment of a carrier separation method.
  • Fig. 8 is a perspective view, partially assembled, of an embodiment of a carrier and PV cell subassembly.
  • Fig. 9 is a schematic illustration of a portion of a PV cell showing an embodiment of an electron flow path.
  • Fig. 10 is a schematic illustration of a monolithic integration suitable for a flexible module on a polyimide film layer.
  • Fig. 11 is a perspective schematic illustration showing a detail of a three-scribe monolithic integration with an ink-jet backfill.
  • PV cells rely on a substantially transparent or translucent front window layer to admit solar radiation and to provide protection for the underlying cell layers. Described herein is an improvement over PV cells that rely on glass as the transparent front window material.
  • Polymer materials are used as an alternative medium to glass as a front window layer for a PV cell. While certain polymer materials may be less transparent (e.g., some having poor (-80% or less) light transmissive characteristics in the blue and green wavelengths), certain polymer materials have greater flexibility and reduced weight than glass materials.
  • polymer films such as for example polyimide films, can be made sufficiently thin which improves the optical transmissibility of light to the PV cell active layers and which reduces material cost.
  • a PV cell that is fabricated on a transparent polymer superstrate or substrate.
  • the PV cell can be fabricated using a magnetron sputter deposition to form the semiconductor layers. Improvements to the performance of certain layers, some of which are deposited by magnetron sputtering onto polyimide superstrates or substrates, may be realized over those described in U.S. Patent No. 7,141,863 to Compaan et al. entitled “Method of Making Diode Structures,” the disclosure of which is incorporated herein by reference in its entirety.
  • improvements relate to processing techniques to assemble the stack arrangement, or specific layer composition and orientation that has been developed beyond the disclosure of the '863 patent, as described herein.
  • these improvements relate to processing enhancements that improve the adhesion of subsequently applied PV cell layers, such as CdTe or CdS based active layers, to the transparent polymer substrate or superstrate layer.
  • FIGs. 1A and IB there are illustrated schematic views of two embodiments of apparatuses 10 and 100 useful for carrying out a method for producing PV cells 12. It is to be understood that Figs. 1A and IB are shown for illustrative purposes and that other steps or processes can be practiced with the inventive method described herein.
  • Fig. 1A illustrates a batch run roll-to-roll (RTR) manufacturing process where a carrier 14 is supplied on a pay-out spool 15.
  • the method includes the use of a roll-to-roll manufacturing process wherein coiled materials may be supplied on spools and drawn into the process equipment by handling machinery. The coiled materials need to have sufficient strength and flexibility to resist damage from the handling process.
  • the carrier 14 is a generally thin, flexible material that is capable of supporting various PV cell layers through the various process stations as the PV cell is being constructed, as will be further described herein in detail.
  • the carrier 14 may be the polyimide material.
  • the carrier 14 is fed into the apparatus 10 where a polymer material 20 is applied onto an outer surface 18 of the carrier 14.
  • the polymer material 20 can be applied by various suitable processes, some of which are described herein.
  • the carrier 14 acts as a mechanism to transfer the applied polymer 20 through the manufacturing process.
  • the carrier 14 is configured to withstand the various loads imparted by the manufacturing processes used to form the PV cell.
  • the carrier 14, may be any material having sufficient strength, flexibility, thermal properties (i.e., melting point, thermal expansion), and dimensional stability (i.e., strain, thermal expansion rate) to support the polymer throughout the subsequent PV cell manufacturing processes.
  • the carrier 14 is a stainless steel foil or sheet material.
  • the carrier 14 may be made from metallic or non-metallic sheets such as, for example, copper, aluminum, resin- impregnated carbon fiber or fiberglass sheet material, or high temperature polymers.
  • the polymer material 20 has desired light transmission characteristics, along with desired flexibility and flexural strain characteristics.
  • the polymer material 20 comprises a polyimide material.
  • a polyimide material sold under the trademark Kapton®.
  • the outer surface 18 of the carrier 14 can be prepared for the application of the polymer material 20.
  • the outer surface 18 can be cleaned, such as by ultrasonic cleaning, and coated with a retention coating or a release agent (shown in Fig. 8).
  • the polymer material 20 is then applied to the surface 18 of the carrier 14 to form a polymer-carrier laminate 22.
  • the carrier 14 may be supplied to the apparatus 10 with the polymer material 20 (and, optionally, any other coatings or release agents) already formed as a sub-assembly in an offline process.
  • the polymer-carrier laminate 22 is moved through various processing stations 40, 50, 60, 70 of the apparatus 10, the PV cell is formed on the polymer material 20 comprising the polymer-carrier laminate 22.
  • the carrier 14 is separated from the polymer-carrier laminate 22.
  • the polymer 20 of the polymer-carrier laminate 22 remains with the semi-finished PV cell 30.
  • the carrier 14 can be recoiled on a take-up spool for recycling and/or reprocessing.
  • Fig. IB illustrates a continuous belt, RTR process 100 where the carrier 114, similar to the carrier described above, forms a continuous loop.
  • the polymer material 120 may be cast onto the carrier 114, either with or against the force of gravity, or may be applied as a separate sheet material, thus forming a polymer-carrier laminate 122.
  • the carrier 114 is separated from the polymer 120 of the polymer-carrier laminate 122.
  • the carrier 114 may be moved to a cleaning and preparation station to ready portions of the carrier for another application of polyimide material.
  • Fig. IB also includes a polymer surface preparation station, shown generally at 150.
  • the polymer preparation station 150 prepares the surface of the polymer material 20 so that subsequently applied layers, such as the active semiconductor layers of the PV cell, have improved adhesion characteristics.
  • the polymer preparation station 150 may apply an etching agent, a solvent, or other cleaning agent to the smooth surface of the polymer 120 to provide a surface texture for adhering a subsequently applied layer, such as a transparent conductive oxide layer.
  • a solvent such as acetone or methyl ethyl ketone may be applied to the surface to create a softened, thixotropic, or thin liquid layer that can be manipulated to provide the proper surface characteristics for adhering the subsequently applied layers.
  • Etching of the polyimide film may also be done with, for example, aqueous solutions of KOH and alcohol solutions of KOH such as 0.1 normal KOH in a mixture of 80% ethanol/20% water.
  • the RTR process apparatus 100 also includes a plurality of processing stations 160, 170, 180, and 190 that may be similar to the processing stations 40, 50, 60, 70 of the apparatus 10. These processing stations may include, for example, sputtering stations configured to apply the various layers of the PV cell, such as a TCO layer, a CdTe layer, a CdS layer, and a back contact layer.
  • processing stations 160, 170, 180, and 190 may be similar to the processing stations 40, 50, 60, 70 of the apparatus 10.
  • These processing stations may include, for example, sputtering stations configured to apply the various layers of the PV cell, such as a TCO layer, a CdTe layer, a CdS layer, and a back contact layer.
  • the built-up layers of the resulting PV cell 12 are subjected to more interlaminate stress and strain than cells formed on rigid substrates or superstrates.
  • the adhesion of the polymer superstrate layer with the TCO layer needs to accommodate these stresses and strains without debonding or delaminating.
  • the connections between the various active semiconductor layers and electrical contact layers are also affected by this bond integrity.
  • the preparation of the polymer material surface to retain the subsequently applied layers may comprise the steps of surface roughening, material implantation, adherent coating application, or combinations of these steps.
  • FIG. 2A there is shown an embodiment of a surface preparation apparatus, shown generally at 200, that includes an ion bombardment process.
  • the surface preparation apparatus 200 is configured as a discrete process for producing a single unit of material, such as a coated polymer layer 210 or a complete PV cell. It should be understood that the method and apparatus of this surface preparation procedure may be included as part of the RTR or continuous loop apparatuses 10 and 100 of Figs. 1A and IB. Such an apparatus may be positioned, for example, at processing station 40 in Fig. 1A or processing station 160 in Fig. IB, if desired.
  • the surface preparation apparatus 200 in Fig. 2A may be configured as an ion bombardment chamber that includes a polymer sheet mounting structure, illustrated as a rotating drum 220.
  • the drum 220 is spaced apart from an electrode surface 230 to constitute an ion source 240.
  • a supply of gas 250 is provided and may be comprised of any suitable inert or reactive sputtering gas such as, for example, argon, neon, krypton, oxygen, nitrogen, or a combination of gasses.
  • the gas 250 and ion source 240 is used to form a plasma to support the ion bombardment process and to regulate the kinetic energy of particles moving from the target to the polymer layer.
  • the gas may be supplied by a "shower-head" inlet 252, instead of the gas supply 250.
  • the shower head inlet 250 can be at ground potential where the substrate drum is negatively biased as shown.
  • the drum or polyimide substrate is near ground potential and the showerhead is biased positively.
  • a grid may be provided in front of the showerhead to bias that end of the discharge, similar to the grid of Fig. 2B described below. Due to the insulating nature of the polyimide, a screen or grid may be provided in front of the gas showerhead and another in front of the polyimide.
  • the surface preparation apparatus 200 may be encased in an air tight chamber, such as a vacuum chamber (not shown).
  • a voltage generator 260 applies a biasing voltage, shown in Fig. 2A as a negative biasing voltage 262, onto the surface of the polymer layer 210.
  • the polymer biasing voltage 262 causes an attraction of the charged ionic particles that are ejected from the ion source during sputtering.
  • the biasing voltage 262 can be varied in intensity so that the kinetic energy of the particles impacting the polymer sheet 210 can be changed throughout the process.
  • the biasing voltage 262 may be applied at a stronger level during the initial phase of the process to increase the kinetic energy of particles impacting the smooth face of the polymer layer 210.
  • the higher kinetic energy particles impact the polymer surface with higher energy and provide a rougher surface for subsequent particles.
  • the ions may be accelerated toward the polymer with a screen or grid that receives the biasing voltage. In this case most of the positive ions pass through the grid and impact the polyimide.
  • an interface layer configured as a film layer, begins to form on the polymer layer 210.
  • the film layer may be formed from the same constituents as a first active layer of the PV cell, such as a ZnO: Al layer or other transparent conducting layer followed by a CdS layer.
  • the polymer biasing voltage 262 may be deceased to lower the kinetic energy of the particles.
  • the pressure of the sputtering gas 250 may be increased to provide more gas molecules and a greater intensity of collisions between the energized particles ejected from the target 230 and the gas molecules. These collisions remove energy from the particles prior to impact with the polymer layer.
  • the densification of the resulting lattice structure can be controlled. This prevents lateral compression of the polymer and film laminate which prevents curling of the polymer and film laminate due to any residual tensile or compressive stress state of the laminate from the incident particles.
  • the bias voltage 262 may be varied from about 20 V to about 200 V with alternating voltage such as at RF frequency (typically 13.56 MHz).
  • the voltage may be a pulsed DC voltage or a straight DC voltage.
  • the pressure of the sputtering gas 250 may be varied from 5 mTorr at the start of the process to 18 mTorr near the end of the layering cycle.
  • the biasing voltage 262 or the gas pressure 250 may be a constant value or may be cycled for a specific time period during the process.
  • FIG. 2B there is illustrated another embodiment of a surface preparation apparatus shown generally at 300.
  • the surface preparation apparatus 300 is illustrated as a discrete process similar to the surface preparation apparatus 200.
  • the method and apparatus of this surface preparation procedure may be included as part of the RTR or continuous loop apparatuses 10 and 100 of Figs. 1A and IB.
  • Such an apparatus may be positioned, for example, at processing station 40 in Fig. 1A or processing station 160 in Fig. IB, if desired.
  • the surface preparation apparatus 300 includes a polymer layer 310 mounted onto a polymer sheet mounting structure, illustrated as a rotating drum 320.
  • the drum 320 is spaced apart from a target 330 and a sputtering gun, such as a magnetron sputtering gun 340.
  • a supply of gas 350 is provided and may be any suitable inert or reactive sputtering gas such as, for example, argon, neon, krypton, oxygen, nitrogen, or a combination of gasses.
  • the gas 350 is used to both form a plasma to support the sputtering process and to regulate the kinetic energy of particles moving from the target to the polymer layer.
  • the surface preparation apparatus 300 may be encased in an air tight chamber such as a vacuum chamber (not shown).
  • a voltage generator 360 applies a biasing voltage, shown in Fig. 2A as a negative biasing voltage 362, between the ion source and the surface of the polymer layer 310 or grid .
  • the biasing voltage 362 may be positive or negative depending on the particle charge.
  • the biasing voltage 362 causes an attraction of the charged ionic particles that are ejected from the target 330 during sputtering.
  • a triode screen 370 may be disposed between the polymer layer 310 and the target 330.
  • the triode screen 370 may have a negative or a positive biasing voltage 372 applied thereto to increase or decrease the kinetic energy of particles ejected off of the target 330.
  • the triode biasing voltage 372 may be varied or constantly applied during the process.
  • each film or layer may have an ion concentration or gradient that optimizes that layer's adhesion characteristics. This ability to vary the ion dispersion through the material, and the related concentration of ions in the various layers, provides optimized adhesion characteristics that are based on the layer constituents and material properties rather than being limited by the available process parameters.
  • Fig. 3 is a schematic view of a processing station in the RTR manufacturing process for constructing a PV cell.
  • the processing station is a sputtering process, used to build up conductive (i.e., a transparent conductive oxide layer or front contact) and active layers (i.e. p, i, and n layers) of the PV cell.
  • the sputtering process may be, for example, an RF magnetron sputtering; other processing stations may include active layer doping, elevated temperature CdCli annealing, laser scribing, back contact application, and encapsulation, to name a few.
  • FIGs. 4A-4E schematically illustrate a general process for constructing a PV cell using a polymer-carrier laminate, as described herein. Additionally, Figs. 4A-4E disclose another embodiment of a process to improve adhesion between the polymer material 20 and the subsequently applied PV Cell layers.
  • a first step shown in Fig. 4A the polymer 20 is first cast or otherwise applied onto the carrier 14.
  • the polymer casting process is generally characterized by application of the polymer in a fluidic state, such as a liquid or a thixotropic paste, onto the carrier.
  • a knife edge 16 can be used to evenly distribute the polymer material 20 over the surface 18 of the carrier 14.
  • the knife edge 16 may be a physical blade or roller device that is spaced apart from the surface of the carrier.
  • the knife edge 16 may be a fluid stream (such as, for example heated air) that is directed across the surface of the polymer material.
  • the knife edge 16 is subsequently drawn (in a squeegee-like manner), moved, or directed over the polymer material to create a thin film of material.
  • the polymer material 20 may be applied to the surface 18 of the carrier 14 by other suitable processes, such as, but not limited to, spraying, co-extruding, or as co-linear sheets of material that are attached together as the materials are payed out.
  • Fig. 4B illustrates a second step where a primer coating or tie-coating 400 is applied onto the polymer-carrier laminate 22.
  • the primer coating 400 is a generally transparent or translucent layer that is applied to the polymer layer.
  • the primer coating 400 improves adhesion of the subsequently applied TCO layer.
  • the primer coating 400 may be applied by a spraying process, a screening process, or an electrostatic process.
  • the spraying process may include a solvent that is mixed with the primer, such as sodium hydroxide, other hydroxides, or hydrazine.
  • the screening process may apply a patterned or textured surface finish to the polymer.
  • the electrostatic process may include an electrostatic charge generator that generates a charge on the exposed polymer surface such that the primer is attracted to the polymer surface.
  • Fig. 4C illustrates a third step in the process where layers of the thin-film PV cell are applied onto the polymer surface of the polymer-carrier laminate 22.
  • specific layers of the PV cell may be applied by any suitable process such as, for example, by sputtering to apply the active n- and p- layers, or colltnear extrusion for applying the back contact.
  • the sputtering source applies certain layers of the PV cell, such as the active layers, against the force of gravity.
  • the sputtering process may be conducted in the direction of the force of gravity or at an angle relative thereto if desired.
  • the process of forming the various active PV layers may be any suitable process.
  • the PV cell may be constructed by being deposited onto the primer-coated polymer material of the polymer-carrier laminate.
  • a TCO layer forms the front electrical contact and is formulated to allow light to pass through to the active layers below to release electrons, thus creating a voltage and current flow.
  • the PV cells may be fabricated using sputtered zinc oxide doped with aluminum as the TCO layer. Other materials may be used in the TCO layer such as, for example, indium tin oxide, cadmium tin oxide, and doped tin oxide.
  • a highly resistive transparent (HRT) layer may be applied between the TCO layer and the first active layer to form a bilayer.
  • the HRT layer made, e.g., of undoped ZnO or AI2O3 to provide both an electrical isolation function and a chemical diffusion barrier function.
  • the TCO HRT bilayer may use a ZnO: Al/ZnO bilayer where the ZnO: Al portion functions as the TCO layer and the undoped portion of ZnO functions as the HRT layer.
  • active layers of CdTe and CdS are deposited onto the TCO to fonn the p-type and n-type layers.
  • the CdS and CdTe layers may also be deposited through the sputtering process.
  • An intrinsic, or i-type, layer may be deposited between the n- and p- layers.
  • multiple sputtering stations can be positioned to create multiple layered or tandem PV cells.
  • Other processes and/or fabrication steps may be interposed at appropriate points along the manufacturing line to form the various PV layers.
  • steps include: (i) doping of the CdTe layer with a suitable dopant, such as for example copper, (ii) a CdCb treatment, which may be performed at approximately 390°C for a time that ranges from 5 to 30 minutes, depending on the thickness of the CdTe layer, and (iii) a back contact treatment process involving deposition of 5-50 A Cu layer followed by a 5-30 minutes anneal at 150°C for diffusion of the Cu, the processing parameters of which may also depend on the CdTe thickness.
  • a suitable dopant such as for example copper
  • CdCb treatment which may be performed at approximately 390°C for a time that ranges from 5 to 30 minutes, depending on the thickness of the CdTe layer
  • a back contact treatment process involving deposition of 5-50 A Cu layer followed by a 5-30 minutes anneal at 150°C for diffusion of the Cu, the
  • stations may be positioned at appropriate points along the line for scribing and applying the back contact, if desired.
  • the scribing process may also be interposed between the various sputtering stations to create series or parallel electrical connections for tandem cell construction, similar to the cell of Fig. 9.
  • an encapsulant can be applied to the semi-finished PV cell to protect the PV cell from damage and exposure to weather and the elements.
  • the encapsulant may be any suitable material to seal the PV cell.
  • suitable encapsulant materials include resins, sealants, plastics and/or polymers such as, for example, polyvinyl chloride, vinyl ester resin, urethane, and phenolic resins.
  • step illustrated in Fig. 4D may be conducted before the cell removal step shown in Fig. 4E, it is to be understood that, in certain embodiments, the
  • encapsulation process may be conducted after the cell removal step of Fig. 4E.
  • the encapsulation and/or back contact may also be applied in an offline process in this step of the process.
  • a separation station or separation point is positioned at or near the end of the RTR manufacturing line.
  • the separation station removes the finished, or semi-finished, PV cell from the carrier.
  • a mechanical parting operation includes a blade, wedge, wire cutter, or other parting structure.
  • the blade may peel the carrier layer directly away from the polymer-PV cell structure.
  • a release agent disposed between the carrier and the polymer layer, may be in the form of a somewhat brittle or otherwise frangible material.
  • the blade may cleave the release agent material allowing the polymer layer to pull or fall away from the carrier.
  • a cleaning process may be applied to both the polymer layer and the carrier if residual frangible release agent remains on either or both surfaces.
  • the PV cell may be separated from the carrier by way of mechanical or ultrasonic vibration generated by a vibratory shaker.
  • the vibratory force may excite the structure at a resonant frequency of the polymer to carrier interface, causing the materials to separate.
  • the vibrations may cause the frangible release agent to crack or otherwise cleave allowing the layers to separate.
  • the vibratory shaker may be any structure capable of imparting an oscillatory force onto the carrier and PV cell assembly such as, for example, a roller at the separation point in the process.
  • the blade of Fig. 5 may be a vibrating parting blade or may be used in conjunction with the vibratory shaker of Fig. 6.
  • an alternative embodiment of a separation station or point may include a focused stream acting at the polyimide to carrier interface.
  • the focused stream may be a fluid stream of water or air (or another gas) in the form of a fluid knife. Such a stream may cut or otherwise abrade a portion of the polymer layer or abrade a release agent layer.
  • the focused stream may be a solvent such as, for example, methanol that is reactive with the release agent to permit separation at the polymer to carrier interface.
  • Yet another embodiment of a focused stream may be a laser beam, electron beam, or other energy stream capable of localized excitation of the polymer to carrier interface or oxidation or other removal process applied to the release agent layer.
  • the carrier may include a coating that facilitates selective retention of the release agent or the polyimide material.
  • the coating may be an oxide coating such as, for example, a ZnO coating.
  • the coating, or the carrier itself, may further have a textured finish applied to the surface.
  • the textured finish is transferable to the polyimide material to provide greater collection of solar radiation.
  • the textured finish may be in the form of a patterned shape such as, for example, honeycombs, hexagons, and triangles.
  • the textured finish may be a random surface roughness, for example, as may be determined by an Ra, Rz, or other surface roughness measurement characteristics.
  • Selection of the appropriate carrier material or structure as the fixturing embodiment may be driven by the specific chemistry of the polymer layer.
  • selection criteria may involve, for example, balancing the glass transition temperature (T g ), the mechanical properties of the polymer before and after sputtering exposure (e.g., RF, DC, and pulsed DC sputtering), and the surface texture characteristics of the polymer exhibited after casting, or application as a thin film sheet onto the carrier, and prior to sputtering exposure.
  • T g glass transition temperature
  • the mechanical properties of the polymer before and after sputtering exposure e.g., RF, DC, and pulsed DC sputtering
  • the surface texture characteristics of the polymer exhibited after casting or application as a thin film sheet onto the carrier, and prior to sputtering exposure.
  • T g glass transition temperature
  • RF, DC, and pulsed DC sputtering exposure e.g., RF, DC, and pulsed DC sputtering
  • the release agent may be disposed between the carrier layer and the polyimide layer, as shown in Fig. 8.
  • the release agent may be a soluble adhesive; a salt, for example NaCl or other salt; or other compound that is soluble in water or a solvent to permit separation of the polyimide from the carrier.
  • the release agent may function as a fixturing material to retain the polyimide film onto the carrier.
  • the release agent may work in conjunction with one or more separation mechanisms, as will be described below, to permit removal of the carrier without damage to the polyimide layer or the PV cell generally.
  • the polymer material may be retained onto the carrier by an electrostatic charge applied to the carrier.
  • An electrostatic generator may be positioned proximate to the carrier to induce a charge potential on the carrier.
  • a downstream electrostatic absorber (not shown) may nullify or otherwise eliminate the electrostatic charge in order to release the assembled PV cell from the carrier.
  • a polymer layer forms a front window layer.
  • the polyimide film layer is shown oriented as a front window or first layer of the PV cell. It should be understood that the polymer layer may be positioned also as an outermost layer behind the back contact.
  • the polymer layer is an electrically conductive polymer layer that forms a back contact of the cell.
  • the active semiconductor coatings that form the heteroj unction CdS/CdTe show improved performance characteristics when the back contact is formed last and this requires the overall structure have the superstrate configuration. That is, the cells or modules are turned upside down in operation so that sunlight enters through the transparent substrate.
  • Glass is often chosen as a superstrate material for the window layer when the coatings forming the PV cell are deposited at temperatures of about 550°C to about 650°C.
  • the method of the invention provides deposition of coatings at much lower temperatures enabling the use of transparent polymer material rather than glass.
  • the polymer-based window layer described herein provides a light-weight and flexible PV cell.
  • the low weight and flexibility of such PV cells provides a variety of advantages over the rigid and heavy glass-based modules, while still retaining the performance of the polycrystalline
  • a separable polymer-carrier laminate structure (“laminate”) provides a practical solution for implementing high volume PV production.
  • the laminate is comprised of a thin metal foil carrier and a polyinude polymer layer that are detachably adhered, or laminated, together.
  • the laminate has releasability characteristics that allow the metal foil carrier to be removed from the polyimide polymer layer after most of the fabrication of the PV module is completed.
  • the use of the polymer-carrier laminate allows for the deposition of PV film layers on large-area polyimide films.
  • the polymer layer is provided with an improved adhesion characteristic to facilitate bonding of the subsequent PV cell layers.
  • the improved adhesion characteristic of the polymer layer prevents debonding or delamination of the various PV cell layers when the structure is flexed. Processing steps such as ionic bombardment of the polymer layer, application of transparent primer coatings, or conditioning of the polymer layer by etching may be used to create the improved adhesion characteristic.
  • the removal of the metal foil carrier provides a PV cell structure that is at least semitransparent. Combined with the excellent thickness control available through magnetron sputtering, this allows for the production of PV cells that can use much of the available light but still be sufficiently light transmissive for architectural use.
  • a semitransparent PV module can include an electrically conductive and transparent back contact applied to the CdTe PV cell.
  • the polyimide superstate and the front contact are also transparent, thus permitting some light to pass through the PV cell.
  • Such a PV module can function as a window that also produces electric power.
  • PV cells can be fabricated with CdTe layers having a thickness of only about 0.5 ⁇ that still can operate with 10% efficiency and still transmit about 5% of the light through the entire structure. In other embodiments, PV cells thinner than about 0.5 ⁇ can transmit more light at some sacrifice of efficiency.
  • the polymer-carrier laminate is useful in the manufacturing of a monolithically integrated flexible module based on thin-film silicon (tf-Si).
  • tf-Si thin-film silicon
  • individual cell modules were formed from large-area tf-Si multi-layer structures in a separate manufacturing step that involved the post-manufacturing interconnection of many individual PV cells into higher voltage modules typically under 100 volts. While this two- step process provides flexibility for module designs suitable for different applications, the invention provides further and distinct advantages for the production of a module which is monolithically-integrated into a high-voltage output easily above 100V.
  • the RTR manufacturing process uses a polyimide layer releasably attached (i.e., temporarily adhered) to a metal foil to provide an improvement to the fabricating process of a TCO/CdS/ CdTe/(back contact) cell structure.
  • a very long (>lkm) and wide ( ⁇ lm) laminate can be used to facilitate the high volume production in the RTR process.
  • the PV sub-modules while attached to the polymer-carrier laminate, are monolithically integrated by using a laser scribing and ink jet backfill process.
  • a laser scribing and ink jet backfill process can also produce a semi-transparent PV cell array suitable for window applications.
  • an improved method for handling of the polyimide material during processing includes: 1) heat-up in vacuum to the deposition temperature of about 250°C followed by the sputter deposition of ZnO:Al, CdS, and CdTe layers; then 2) activation treatment at about 390° C in dry air plus saturated vapors of CdCb; followed by 3) vacuum deposition of the metal back contact; and, 4) final heat treatment near 150°C in air to achieve good ohmic contact.
  • the method may further include one or more
  • the interlayer coating is between the metal carrier and polyimide material.
  • the interlayer can act both as a temporary adherent and as a release agent to facilitate removal of the polyimide layer (and the built-up PV cell structure thereon) from the metal carrier without damaging the flexible PV cell structure.
  • the delaminated coated metal foil carrier is sufficiently undamaged by the delamination step and can be recycled and reused in further cycles of the manufacturing process of the PV cells.
  • the metal foil carrier can be configured to be compatible with the pay-out, transport, and take-up systems needed for a RTR manufacturing line.
  • the metal foil material may be a stainless steel laminate foil material.
  • the polymer-carrier laminate (comprised of a polyimide film applied to a metal foil) supports the steps in the fabrication sequence of CdS/CdTe PV modules. These steps can include: 1) deposition at -250°C of a TCO layer on the polyimide (in one embodiment the TCO layer is ZnO: Al); 2) deposition of an HRT layer; 3) deposition at ⁇ 250°C of the active semiconductor layers of CdS and CdTe; 4) an activation step, usually involving temperatures near 390°C in the presence of CdCl 2 ; and finally, 5) application of a back contact through a metallization process.
  • steps can include: 1) deposition at -250°C of a TCO layer on the polyimide (in one embodiment the TCO layer is ZnO: Al); 2) deposition of an HRT layer; 3) deposition at ⁇ 250°C of the active semiconductor layers of CdS and CdTe; 4) an activation step, usually involving temperatures near 390°
  • the metal lamination layer is removed from the polyimide film without damaging the polyimide or the PV-cell layers.
  • the fabrication of the complete submodule includes the deposition of all the PV cell layers (e.g., TCO/HRT/CdS/CdTe/back contact) and the cadmium chloride activation step.
  • one step in the method can include providing for the monolithic integration of individual PV cell strips into high voltage modules while the polymer-carrier laminate is intact and the
  • polyimide/cell structure is still attached to the underlying metal foil carrier.
  • the metal foil carrier provides extra support, or stiffening, of the semi-finished PV cell in order to protect the thin film of polyimide that will eventually be the window layer of the finished PV cell.
  • the presence of the carrier layer in the subsequent process steps acts to assist in accurate focusing of scribing and backfilling processes and in maintaining dimensional stability.
  • the monolithic integration of CdTe-based cells can be done with three sequential scribes: 1) an isolation scribe PI is done after TCO deposition; then 2) a via scribe P2 is opened after CdS/CdTe deposition; finally, 3) another isolation scribe P3 is done after back contact metallization.
  • the monolithic integration can be accurately and conveniently done after most or all PV-cell layers have been deposited. This can be done through the use of laser scribing, followed by an insulating backfill of PI and a conducting backfill of P2, see Fig. 11.
  • the presence of a relatively stiff metal backing to the polyimide provides at least several advantages.
  • the metal carrier is magnetic or magnetized, the carrier can provide a hold-down method to stabilize the coaled polyimide during the scribing process.
  • the metal carrier can also facilitate the handling and the use of thinner polyimide films which, in turn, reduces the module materials costs and improves the superstrate (i.e., window layer) light transmission.
  • the scribing of the ZnO:Al layer can be done with a 355 nm wavelength to achieve sufficient optical absorption using, for example, a galvanometer scanned system with this wavelength.
  • the galvo-scanned laser system can be used in a process of "edge deletion" in which some of the film deposition is removed from the edges of the module to improve the electrical isolation at the module edges. Edge deletion can improve adhesion and moisture barrier performance of encapsulants or sealants at the module edges.
  • the available stiffening of a metal foil laminate can similarly facilitate this edge isolation or edge deletion which can be done after all active PV layers are deposited.
  • a high power, high repetition rate, pulsed laser can be used to remove entirely a narrow (about 5 to 10 mm) strip at the module edges by removing either the back contact metallization only or preferably removing all thin-film material including the conductive TCO layer to achieve good electrical isolation of individual cells from the damaged cut edges of the module.
  • Edge isolation may also be done by masking and chemical etching of a band of TCO around the outside edges of the cells.
  • PV cells produced by the methods described herein can be made for use in architectural windows where it is desired that such windows be at least translucent, if not transparent.
  • these PV cells are especially appropriate for window applications and are well-suited for urban sites with tall buildings having large amounts of glazing and little unobstructed roof areas.
  • these PV cells are especially appropriate for applications in vehicles including, but not limited to skylights, side and rear windows, panels in roofs, trunks, hoods, etc.
  • the PV cell comprises a semitransparent, monolithically integrated PV module.
  • the PV cell can have a reduced thickness of a CdTe layer (e.g., on the order of approximately to 0.5 um) and a transparent back contact structure, such as ZnTe:N, that facilitates, together with the thin CdTe, the fabrication of flexible, semi- transparent PV cells.
  • a reactive magnetron sputtering can be used to form these transparent contact structures.
  • the flexible, thin-film CdTe-based PV modules on polymer can be semi- transparent and may exhibit operational characteristics on the order of -7% conversion efficiency with about 5% transparency and good color balance on polyimide sheet in a RTR deposition process. In other embodiments, a higher transparency may be achieved with somewhat lower PV efficiency.
  • PV modules described herein can be monolithically integrated to yield high voltage output (60-240VDC) for ease of installation and for simple inversion to AC power for grid-connected operation.
  • the PV modules described herein can be used for powering instruments and appliances that operate on DC power, off-grid.
  • the PV module can be designed in various sizes to yield voltage and power outputs optimized for a variety of applications.
  • one of the advantages of RTR manufacturing with on-line monolithic module integration is that there is great flexibility in changing the module size and voltage to suit different applications. This differs from glass-based modules in which the entire manufacturing line must be designed to handle a given size of glass.
  • the flexibility and light weight of the PV modules are especially suited for rooftop PV system.
  • Lightweight and flexible modules have many important performance characteristics that are highly desired by customers. For example, many roof structures cannot support the weight of glass based PV modules. Also, in order to support the installation of glass modules, mechanical racking systems are required. For many of these racking systems, roof penetrations are required to anchor the system to the roof and prevent uplift from wind. Once the roof is penetrated, the manufacturer's warranty is generally void.
  • the PV modules described herein can be developed for such diverse applications as large roof area businesses, low roof slope businesses, industrial and institutional buildings, and for easily mounted incorporation with standing-seam metal roofing systems for homes and businesses.
  • the flexible PV modules can be integrated as part of the final laminate on low slope industrial, institutional, and business roofing.
  • standing seam metal roofing is attractive for a product made to adhere to the channels between the seams which would minimize installation costs and require no roof penetrations.
  • canopies and awnings offer another attractive opportunity for flexible and light weight PV.
  • An example would be coverings for parking lots that could offer shade while generating electricity for electric vehicle and plug-in hybrid vehicles.
  • DC power conditioning and regulation can be used to allow DC power to flow directly into the automobile batteries to avoid the losses conventionally incurred with inversion to AC followed by rectification back to DC for battery charging.
  • the PV module is transformational as a flexible product with a DC power conversion efficiency of -6% in a format that is readily applied to windows either from the inside or outside.
  • the PV module is intrinsically semitransparent and can be deployed in large office buildings, and can simultaneously reduce solar heating and produce power for interior lighting, electronics, and conditioning of the office space.
  • Rooftop PV panels deployed horizontally on buildings are particularly well suited for one- and two-story institutional, manufacturing, and warehousing structures.
  • the window PV modules are also suited for plug-and-play connections to
  • the PV modules are also especially suited for use in products needed in
  • the light-weight and flexible PV can be used in high altitude airships and in space applications due to its compact stowage, resilience to vibrations and, for CdTe cells, known resistance to radiation damage.
  • the PV modules can be useful for lightweight, flexible, high
  • the PV cell structure (and methods used to produce such PV cells) also has applicability when used in conjunction with a standard metal back contact by allowing for the reduction in the thickness of the CdTe layer, while still maintaining the desired high efficiencies of the PV cell.
  • Additional benefits include: a reduction of the manufacturing line length, a reduction of CdC activation time, and a reduction in the amounts of cadmium and tellurium needed.
  • the PV cell structures can be coupled with integrated micro- inverters to produce AC power that can be "plugged in” to the existing electrical networks in most buildings with very few modifications.
  • a reactively sputtered, nitrogen-doped ZnTe can serve as a transparent back contact to CdTe.
  • suitable diffusion barriers may be included to control impurity migration, including electro-migration, by controlling the grain morphology through the sputter deposition process conditions.
  • the process of encapsulation can include steps such as "edge deletion,” forming buss lines, bypass diodes, and junction boxes, together with a robust module encapsulation process. These steps are compatible with the polymer-carrier lamination process described herein.
  • the manufacturing process yields complete PV modules that exhibit long-term solar exposure endurance, as well as high voltage isolation and the standard thermal and humidity cycling.
  • the TCO In other embodiments, such as for other CdTe PV modules, the TCO
  • buss lines may be utilized at the ends of the RTR processed modules to collect the current for the junction box, which brings the current through the encapsulation and out of the panel.
  • the RTR manufacturing line can include stations such as a RTR coaling line with on-line chloride activation, followed by the monolithic (sub)module integration and cutting into module sizes. Also, the RTR manufacturing line can include the process of encapsulating the PV submodule to form a completed PV module.

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Abstract

Cette invention concerne une cellule photovoltaïque comprenant une couche d'interface qui présente une caractéristique d'adhésion améliorée entre deux couches adjacentes. Ladite cellule photovoltaïque comprend la couche d'interface disposée entre une fenêtre en polymère et une couche d'oxyde conductrice transparente. La couche d'interface est formée par un procédé qui comprend un processus de bombardement ionique ou un processus d'application de couche d'apprêt ou un processus d'application de solvant/agent de gravure. L'invention concerne en outre un appareil destiné à former la couche d'interface, comprenant un poste de bombardement ionique ou un poste d'application de couche d'apprêt ou un poste d'application d'agent de gravure.
PCT/US2011/000813 2010-05-10 2011-05-10 Cellules photovoltaïques souples et modules présentant une adhésivité améliorée WO2011142804A1 (fr)

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US9159851B2 (en) 2010-05-26 2015-10-13 The University Of Toledo Photovoltaic structures having a light scattering interface layer and methods of making the same
CN108321233A (zh) * 2018-04-12 2018-07-24 江苏东鋆光伏科技有限公司 双玻璃碲化镉太阳能电池组件及其制备方法
CN108321233B (zh) * 2018-04-12 2023-11-10 江苏东鋆光伏科技有限公司 双玻璃碲化镉太阳能电池组件及其制备方法

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