WO2007104039A9 - Cellules photovoltaïques - Google Patents

Cellules photovoltaïques

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Publication number
WO2007104039A9
WO2007104039A9 PCT/US2007/063669 US2007063669W WO2007104039A9 WO 2007104039 A9 WO2007104039 A9 WO 2007104039A9 US 2007063669 W US2007063669 W US 2007063669W WO 2007104039 A9 WO2007104039 A9 WO 2007104039A9
Authority
WO
WIPO (PCT)
Prior art keywords
article
layer
electrically conductive
conductive lines
width
Prior art date
Application number
PCT/US2007/063669
Other languages
English (en)
Other versions
WO2007104039A2 (fr
WO2007104039A3 (fr
Inventor
Christoph Brabec
Jens Hauch
Pavel Schilinsky
Original Assignee
Konarka Technologies Inc
Christoph Brabec
Jens Hauch
Pavel Schilinsky
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 Konarka Technologies Inc, Christoph Brabec, Jens Hauch, Pavel Schilinsky filed Critical Konarka Technologies Inc
Priority to EP07758241A priority Critical patent/EP1997219A4/fr
Priority to JP2008558548A priority patent/JP2009529792A/ja
Publication of WO2007104039A2 publication Critical patent/WO2007104039A2/fr
Publication of WO2007104039A9 publication Critical patent/WO2007104039A9/fr
Publication of WO2007104039A3 publication Critical patent/WO2007104039A3/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
    • 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
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/81—Electrodes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
    • C08G2261/31—Monomer units or repeat units incorporating structural elements in the main chain incorporating aromatic structural elements in the main chain
    • C08G2261/312—Non-condensed aromatic systems, e.g. benzene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
    • C08G2261/32—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain
    • C08G2261/324—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain condensed
    • C08G2261/3243—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain condensed containing one or more sulfur atoms as the only heteroatom, e.g. benzothiophene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
    • C08G2261/33—Monomer units or repeat units incorporating structural elements in the main chain incorporating non-aromatic structural elements in the main chain
    • C08G2261/334—Monomer units or repeat units incorporating structural elements in the main chain incorporating non-aromatic structural elements in the main chain containing heteroatoms
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
    • C08G2261/34—Monomer units or repeat units incorporating structural elements in the main chain incorporating partially-aromatic structural elements in the main chain
    • C08G2261/342—Monomer units or repeat units incorporating structural elements in the main chain incorporating partially-aromatic structural elements in the main chain containing only carbon atoms
    • C08G2261/3422—Monomer units or repeat units incorporating structural elements in the main chain incorporating partially-aromatic structural elements in the main chain containing only carbon atoms conjugated, e.g. PPV-type
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G2261/90—Applications
    • C08G2261/91—Photovoltaic applications
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/81—Electrodes
    • H10K30/82—Transparent electrodes, e.g. indium tin oxide [ITO] electrodes
    • H10K30/83—Transparent electrodes, e.g. indium tin oxide [ITO] electrodes comprising arrangements for extracting the current from the cell, e.g. metal finger grid systems to reduce the serial resistance of transparent electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
    • H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/114—Poly-phenylenevinylene; Derivatives thereof
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
    • H10K85/146—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE poly N-vinylcarbazol; Derivatives thereof
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/151—Copolymers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
    • H10K85/211—Fullerenes, e.g. C60
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
    • H10K85/211—Fullerenes, e.g. C60
    • H10K85/215—Fullerenes, e.g. C60 comprising substituents, e.g. PCBM
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
    • H10K85/221—Carbon nanotubes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/649—Aromatic compounds comprising a hetero atom
    • H10K85/656—Aromatic compounds comprising a hetero atom comprising two or more different heteroatoms per ring
    • H10K85/6565—Oxadiazole compounds
    • 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
    • Y02E10/549—Organic PV cells

Definitions

  • the invention relates to photovoltaic cells containing a plurality of electrically conductive lines, as well as related systems, methods, modules, and components.
  • Photovoltaic cells are commonly used to transfer energy in the form of light into energy in the form of electricity.
  • a typical photovoltaic cell includes a photoactive material disposed between two electrodes. Generally, light passes through one or both of the electrodes to interact with the photoactive material. As a result, the ability of one or both of the electrodes to transmit light (e.g., light at one or more wavelengths absorbed by a photoactive material) can limit the overall efficiency of a photovoltaic cell.
  • a film of semiconductive material e.g., indium tin oxide
  • the semiconductive material can have a lower electrical conductivity than electrically conductive materials, the semiconductive material can transmit more light than many electrically conductive materials.
  • This invention relates to photovoltaic cells containing a plurality of electrically conductive lines, as well as related systems, methods, modules, and components.
  • this invention features an article that includes a first electrode containing a plurality of electrically conductive lines, a second electrode, and a photoactive layer between the first and second electrodes.
  • the photoactive layer includes an electron donor material and an electron acceptor material.
  • the article is configured as a photovoltaic cell.
  • this invention features an article that includes a first electrode containing a plurality of electrically conductive lines, a second electrode, and a photoactive layer between the first and second electrodes.
  • the photoactive layer includes an electron donor material and an electron acceptor material.
  • the electrically conductive lines have a first width at a first portion and a second width at a second portion, in which the second width is different from the first width.
  • the article is configured as a photovoltaic cell.
  • this invention features a system that includes a first electrode comprising a plurality of electrically conductive lines, a second electrode, and first and second photoactive layers between the first and second electrodes. At least one of the first and second photoactive layers includes an electron donor material and an electron acceptor material.
  • the system is configured as a photovoltaic system.
  • this invention features a system that includes a first electrode comprising a plurality of electrically conductive lines, a second electrode, and first and second photoactive layers between the first and second electrodes. At least one of the first and second photoactive layers includes an electron donor material and an electron acceptor material.
  • the electrically conductive lines have a first width at a first portion and a second width at a second portion, in which the second width is different from the first width.
  • the system is configured as a photovoltaic system. Embodiments can include one or more of the following features.
  • the second portion is configured to conduct a higher current flow than the first portion and the second width is larger than the first width.
  • the difference between the first and second widths is at least about 0.1 ⁇ m. In some embodiments, at least some of the electrically conductive lines are substantially parallel to each other. In certain embodiments, all of the electrically conductive lines are substantially parallel to each other.
  • the electrically conductive lines include trapezoid or triangle shaped lines.
  • the electrically conductive lines include a metal, an alloy, a polymer, or a combinations thereof.
  • the article further includes a hole carrier layer between the first electrode and the photoactive layer.
  • the hole carrier layer can include a polymer, which can be selected from the group consisting of polythiophenes (e.g., poly(3,4- ethylene dioxythiophene) (PEDOT) or polythienothiophenes), polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, and copolymers thereof.
  • the hole carrier layer includes a metal oxide or a carbon nanotube.
  • the hole carrier layer includes a dopant. Examples of dopants include poly(styrene-sulfonate)s, polymeric sulfonic acids, or fluorinated polymers (e.g., fluorinated ion exchange polymers).
  • the first electrode has a surface resistivity, when measured in combination with the hole carrier layer, of at most about 50 ⁇ /square.
  • the electron donor material includes a polymer.
  • the polymer can be selected from the group consisting of polythiophenes, polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, polycyclopentadithiophenes, polysilacyclopentadithiophenes, polycyclopentadithiazoles, polythiazolothiazoles, polythiazoles, polybenzothiadiazoles, poly(thiophene oxide)s, poly(cyclopentadithiophene oxide)s, polythiadiazoloquinoxaline, polybenzoisothiazole, polybenzothiazole, polythienothiophene, poly(thienothiophene oxide), polydithienothiophene, poly(dithienothiophene oxide)s, polytetra
  • the electron donor material can include a polymer selected from the group consisting of polythiophenes (e.g., poly(3-hexylthiophene) (P3HT)), polycyclopentadithiophenes (e.g., poly(cyclopentadithiophene-co- benzothiadiazole)), and copolymers thereof.
  • polythiophenes e.g., poly(3-hexylthiophene) (P3HT)
  • P3HT poly(3-hexylthiophene)
  • polycyclopentadithiophenes e.g., poly(cyclopentadithiophene-co- benzothiadiazole)
  • the electron acceptor material includes a material selected from the group consisting of fullerenes, inorganic nanoparticles, oxadiazoles, discotic liquid crystals, carbon nanorods, inorganic nanorods, polymers containing CN groups, polymers containing CF3 groups, and combinations thereof.
  • the electron acceptor material can include a substituted fullerene (e.g., C61-phenyl-butyric acid methyl ester (PCBM)).
  • PCBM C61-phenyl-butyric acid methyl ester
  • the first photoactive layer has a first band gap and the second photoactive layer has a second band gap different from the first band gap.
  • the system further includes a recombination layer between the first and second photoactive layers.
  • the recombination layer can include a p-type semiconductor material and an n-type semiconductor material.
  • the p-type and n-type semiconductor materials are blended into one layer.
  • the recombination layer includes two layers, one layer containing the p- type semiconductor material and the other layer containing the n-type semiconductor material.
  • the system includes a tandem photovoltaic cell.
  • Embodiments can provide one or more of the following advantages.
  • the electrically conductive lines have a first width at a first portion and a second width at a second portion, in which the second portion is configured to conduct a higher current flow than the first portion and the second width is larger than the first width.
  • FIG. l(a) is a top view of a module containing a plurality of photovoltaic cells
  • FIG. l(b) is a top view of a plurality of photovoltaic cells with trapezoide-shaped electrodes
  • FIG. 2 is a cross-sectional view of an embodiment of a photovoltaic cell
  • FIG. 3 is a cross-sectional view of an embodiment of a tandem photovoltaic cell.
  • FIG. 4 is a schematic of a system containing multiple photovoltaic cells electrically connected in series;
  • FIG. 5 is a schematic of a system containing multiple photovoltaic cells electrically connected in parallel. Like reference symbols in the various drawings indicate like elements.
  • FIG. l(a) shows a top view of a module 100 containing a plurality of photovoltaic cells.
  • Each cell includes, among others, a bottom electrode 120 and a top electrode 160.
  • electrodes 120 include a plurality of electrically conductive lines (i.e., grid electrodes) to allow light to pass through via the space between the lines.
  • Electrode 160 includes an electrically conductive foil and serve as a common electrode for a plurality of photovoltaic cells. Electrode 120 of one photovoltaic cell contacts electrode 160 of another cell at its right end.
  • electrode 160 can also include a plurality of electrically conductive lines.
  • electrodes 120 and 160 are formed of an electrically conductive material.
  • electrically conductive materials include electrically conductive metals, electrically conductive alloys, electrically conductive polymers, and electrically conductive metal oxides.
  • Exemplary electrically conductive metals include gold, silver, copper, aluminum, nickel, palladium, platinum and titanium.
  • Exemplary electrically conductive alloys include stainless steel (e.g., 332 stainless steel, 316 stainless steel), alloys of gold, alloys of silver, alloys of copper, alloys of aluminum, alloys of nickel, alloys of palladium, alloys of platinum, and alloys of titanium.
  • Exemplary electrically conducting polymers include polythiophenes (e.g., poly(3,4-ethelynedioxythiophene) (PEDOT)), polyanilines (e.g., doped polyanilines), polypyrroles (e.g., doped polypyrroles).
  • Examples of electrically conductive metal oxides include indium tin oxides, fluorinated tin oxides, tin oxides, zinc oxides, and titanium oxides. In some embodiments, combinations of electrically conductive materials are used.
  • electrodes 120 are formed entirely of an electrically conductive material (e.g., electrodes 120 are formed of a substantially homogeneous material that is electrically conductive).
  • the open area between grid electrodes 120 can vary as desired. Generally, the open area is at least about 10% (e.g., at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, or at least about 80%) and/or at most about 99% (e.g., at most about 95%, at most about 90%, or at most about 85%) of the total area of an electrode layer in module 100.
  • grid electrodes 120 allow transmittance of at least about 60% (e.g., at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95%) of incident light at a wavelength or a range of wavelengths used during operation of the photovoltaic cell.
  • electrode 120 or 160 itself is made of a transparent material.
  • a transparent material is a material which, at the thickness used in a photovoltaic cell 200, transmits at least about 60% (e.g., at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, or at least about 95%) of incident light at a wavelength or a range of wavelengths used during operation of the photovoltaic cell.
  • electrodes 120 are formed of a first material that is coated with a second material different from the first material (e.g., using metallization or vapor deposition).
  • the first material can be formed of any desired material (e.g., an electrically insulative material or an electrically conductive material), and the second material is an electrically conductive material.
  • electrically insulative material from which the first material can be formed include textiles, optical fiber materials, polymeric materials (e.g., a nylon) and natural materials (e.g., flax, cotton, wool, silk).
  • electrically conductive materials from which the first material can be formed include the electrically conductive materials disclosed above.
  • the first material is in the form of a fiber
  • the second material is an electrically conductive material that is coated on the fiber.
  • the first material is in the form of a grid (see discussion above) that, after being formed into a grid, is coated with the second material (e.g., PEDOT).
  • Grid electrodes 120 can have any desired shape (e.g., rectangle, circle, semicircle, triangle, diamond, ellipse, trapezoid, irregular shape) at any cross-section. For example, FIG. l(a) shows that grid electrode 120 has a rectangular shape from the top view (i.e., the entire electrode 120 having the same width).
  • FIG l(b) shows that grid electrode 120 has a trapezoid shape from the top view, i.e., electrode 120 having a first width at a first portion and a second width at a second portion, in which the second width is different from the first width.
  • the difference between the first and second widths is at least about 0.1 ⁇ m (e.g., at least about 0.5 ⁇ m, at least about 1 ⁇ m, at least about 5 ⁇ m, at least about 10 ⁇ m, at least about 100 ⁇ m, at least about 1,000 ⁇ m, or at least about 0.01 cm, or at least about 0.1 cm) or at most about 1 cm (e.g., at most about 0.5 cm, at most about 0.1 cm, at most about 0.05 cm, at most about 0.1 cm, or at most about 1,000 ⁇ m).
  • different regions of grid electrode 120 can have different shapes.
  • open regions between grid electrodes 120 can generally have any desired shape (e.g., square, circle, semicircle, triangle, diamond, ellipse, trapezoid, or irregular shape). In some embodiments, different open regions between grid electrodes 120 can have different shapes.
  • grid electrode 120 has a surface resistivity, when measured in combination with a hole carrier layer filled in the space between the grid electrode, of at most about 50 ⁇ /square (e.g., at most about 25 ⁇ /square, at most about 20 ⁇ /square, at most about 10 ⁇ /square, at most about 5 ⁇ /square, or at most about 1 ⁇ /square).
  • the maximum thickness of grid electrode 120 i.e., the maximum thickness of grid electrode 120 in a direction substantially perpendicular to the surface of a substrate in contact with grid electrode 120 should be less than the total thickness of the layer above it.
  • the maximum thickness of grid electrode 120 is at least 0.1 micron (e.g., at least about 0.2 micron, at least about 0.3 micron, at least about 0.4 micron, at least about 0.5 micron, at least about 0.6 micron, at least about 0.7 micron, at least about 0.8 micron, at least about 0.9 micron, at least about one micron) and/or at most about 10 microns (e.g., at most about nine microns, at most about eight microns, at most about seven microns, at most about six microns, at most about five microns, at most about four microns, at most about three microns, at most about two microns).
  • electrode 120 or 160 is flexible (e.g., sufficiently flexible to be incorporated in photovoltaic cell 100 using a continuous, roll-to-roll manufacturing process). In certain embodiments, electrode 120 or 160 is semi-rigid or inflexible. In some embodiments, different regions of electrode 120 or 160 can be flexible, semi-rigid or inflexible (e.g., one or more regions flexible and one or more different regions semi- rigid, one or more regions flexible and one or more different regions inflexible). In general, the layout and shape of grid electrodes 120 in photovoltaic module 100 can vary as desired.
  • photovoltaic module 100 having grid electrodes 120 can be designed based on (1) power loss resulted from the transport of electrons between electrodes 120, (2) power loss resulted from the transport of electrons in electrodes 120, and (3) absorption loss due to the presence of electrodes 120.
  • I I 2 R sq d / 6L (1), in which I refers to the maximum current between two grid electrodes, R sq refers to the surface resistivity of the material (e.g., PEDOT) between two grid electrodes, d refers to the distance between two grid electrodes, and L refers to the length of a grid electrode.
  • R sq refers to the surface resistivity of the material (e.g., PEDOT) between two grid electrodes
  • d refers to the distance between two grid electrodes
  • L refers to the length of a grid electrode.
  • I I 2 • P • L / (3 • ⁇ • w) (2), in which I refers to the maximum current in the grid electrode, p refers to the surface resistivity of the material (e.g., silver) that forms the grid electrode, L refers to the length of the grid electrode, ⁇ refers to the thickness of the electrode, and w refers to the width the grid electrode.
  • I refers to the maximum current in the grid electrode
  • p refers to the surface resistivity of the material (e.g., silver) that forms the grid electrode
  • L refers to the length of the grid electrode
  • ⁇ refers to the thickness of the electrode
  • w refers to the width the grid electrode.
  • Absorption loss due to the presence of electrodes 120 can be obtained based on the percentage of the shading area of the electrode within the entire the electrode layer, which is given by the ratio of the sum of the electrode width and the sum of the distances between the electrodes. Based on the above three factors, one can design a photovoltaic module having grid electrodes that result in a minimum power/absorption loss. For example, referring to FIG.
  • the power/absorption loss of the module varies based on the distance between two grid electrodes and the length of the grid electrode.
  • the relationship between these variables can be expressed in a 3 -dimensional graph, from which one can readily determine the optimal distance between two electrodes and the length of the electrode that result in the minimum power/absorption loss.
  • Equation (2) shows that power loss increases with the increase of current in a grid electrode and with the decrease of the electrode width.
  • the current generated by photovoltaic effects in a photovoltaic module increases inside the photovoltaic module and reaches the highest level at the point where the current exits the module.
  • the width of the grid electrode can be increased in the same direction as the current increase. An example of such a configuration is illustrated in FIG. l(b).
  • the width i.e., b in FIG.
  • l(a)) of grid electrode 120 is at least about 1 ⁇ m (e.g., at least about 5 ⁇ m, at least about 10 ⁇ m, or at least about 50 ⁇ m) or at most about 1 cm (e.g., at most about 0.5 cm, at most about 0.1 cm, or at most about 0.05 cm).
  • the length of grid electrode 120 can be designed based on the three factors described above. It can vary depending on, for example, other dimensions (e.g., width and thickness) of electrodes 120, the distances between two electrode 120, the material used to form electrode 120, and the hole carrier material that fills in the space between electrodes 120.
  • the length of grid electrode 120 is at least about 0.1 cm (e.g., at least about 0.5 cm, at least about 1 cm, or at least about 5 cm) or at most about 20 cm (e.g., at most about 15 cm, at most about 10 cm, or at most about 5 cm).
  • the distance between two grid electrodes 120 can generally also be designed based on the three factors described above. It can vary depending on, for example, other dimensions (e.g., width and thickness) of electrodes 120, the material used to form electrode 120, and the hole carrier material that fills in the space between electrodes 120. In some embodiments, the distance between two grid electrodes 120 is at least about 0.01 cm (e.g., at least about 0.05 cm, at least about 0.1 cm, or at least about 0.5 cm) or at most about 10 cm (e.g., at most about 5 cm, at most about 1 cm, or at most about 0.5 cm). FIG.
  • FIG. 2 shows a cross-sectional view of a photovoltaic cell 200 that includes a substrate 210, a cathode 220, a hole carrier layer 230, a photoactive layer 240 (containing an electron acceptor material and an electron donor material), a hole blocking layer 250, an anode 260, and a substrate 270.
  • a photoactive layer 240 containing an electron acceptor material and an electron donor material
  • a hole blocking layer 250 an anode 260
  • substrate 270 a substrate 270.
  • light impinges on the surface of substrate 210, and passes through substrate 210, cathode 220, and hole carrier layer 230. The light then interacts with photoactive layer 240, causing electrons to be transferred from the electron donor material in layer 240 to the electron acceptor material in layer 240.
  • the electron acceptor material then transmits the electrons through hole blocking layer 250 to anode 260, and the electron donor material transfers holes through hole carrier layer 230 to cathode 220.
  • Anode 260 and cathode 220 are in electrical connection via an external load so that electrons pass from anode 260, through the load, and to cathode 220.
  • Substrate 210 is generally formed of a transparent material.
  • Exemplary materials from which substrate 210 can be formed include polyethylene terephthalates, polyimides, polyethylene naphthalates, polymeric hydrocarbons, cellulosic polymers, polycarbonates, polyamides, polyethers and polyether ketones.
  • the polymer can be a fluorinated polymer.
  • combinations of polymeric materials are used.
  • different regions of substrate 210 can be formed of different materials.
  • substrate 210 can be flexible, semi-rigid or rigid (e.g., glass). In some embodiments, substrate 210 has a flexural modulus of less than about 5,000 megaPascals. In certain embodiments, different regions of substrate 210 can be flexible, semi-rigid or inflexible (e.g., one or more regions flexible and one or more different regions semi-rigid, one or more regions flexible and one or more different regions inflexible).
  • substrate 210 is at least about one micron (e.g., at least about five microns, at least about 10 microns) thick and/or at most about 1 ,000 microns (e.g., at most about 500 microns thick, at most about 300 microns thick, at most about 200 microns thick, at most about 100 microns, at most about 50 microns) thick.
  • substrate 210 can be colored or non-colored. In some embodiments, one or more portions of substrate 210 is/are colored while one or more different portions of substrate 210 is/are non-colored.
  • Substrate 210 can have one planar surface (e.g., the surface on which light impinges), two planar surfaces (e.g., the surface on which light impinges and the opposite surface), or no planar surfaces.
  • Anon-planar surface of substrate 210 can, for example, be curved or stepped.
  • a non-planar surface of substrate 210 is patterned (e.g., having patterned steps to form a Fresnel lens, a lenticular lens or a lenticular prism).
  • cathode 220 can have any suitable shape as desired.
  • cathode 220 can be formed of a plurality of electrically conductive lines (i.e., grid electrodes), such as those described above.
  • cathode 220 can include a mesh electrode. Examples of mesh electrodes are described in commonly owned co-pending U.S. Patent Application Publication Nos. 20040187911 and 20060090791, the contents of which are hereby incorporated by reference.
  • Hole carrier layer 230 is generally formed of a material that, at the thickness used in photovoltaic cell 200, transports holes to cathode 220 and substantially blocks the transport of electrons to cathode 220.
  • materials from which layer 230 can be formed include semiconductive polymers, such as polythiophenes (e.g., PEDOT), polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, and copolymers thereof.
  • hole carrier layer 230 can include a dopant used in combination with a semiconductive polymer.
  • dopants include poly(styrene-sulfonate)s, polymeric sulfonic acids, or fluorinated polymers (e.g., fluorinated ion exchange polymers).
  • the materials that can be used to form hole carrier layer 230 include metal oxides, such as titanium oxides, zinc oxides, tungsten oxides, molybdenum oxides, copper oxides, strontium copper oxides, or strontium titanium oxides.
  • the metal oxides can be either undoped or doped with a dopant.
  • dopants for metal oxides includes salts or acids of fluoride, chloride, bromide, and iodide.
  • the materials that can be used to form hole carrier layer 230 include carbon allotropes (e.g., carbon nanotubes).
  • the carbon allotropes can be embedded in a polymer binder.
  • hole carrier layer 230 can include combinations of hole carrier materials described above.
  • the hole carrier materials can be in the form of nanoparticles.
  • the nanoparticles can have any suitable shape, such as a spherical, cylindrical, or rod-like shape.
  • the thickness of hole carrier layer 230 (i.e., the distance between the surface of hole carrier layer 230 in contact with photoactive layer 240 and the surface of cathode 220 in contact with hole carrier layer 230) can be varied as desired.
  • the thickness of hole carrier layer 230 is at least 0.01 micron (e.g., at least about 0.05 micron, at least about 0.1 micron, at least about 0.2 micron, at least about 0.3 micron, or at least about 0.5 micron) and/or at most about five microns (e.g., at most about three microns, at most about two microns, or at most about one micron).
  • the thickness of hole carrier layer 230 is from about 0.01 micron to about 0.5 micron.
  • Photoactive layer 240 generally contains an electron acceptor material (e.g., an organic electron acceptor material) and an electron donor material (e.g., an organic electron donor material).
  • electron acceptor materials include fullerenes, inorganic nanoparticles, oxadiazoles, discotic liquid crystals, carbon nanorods, inorganic nanorods, polymers containing moieties capable of accepting electrons or forming stable anions (e.g., polymers containing CN groups, polymers containing CF3 groups), or combinations thereof.
  • the electron acceptor material is a substituted fullerene (e.g., PCBM).
  • a combination of electron acceptor materials can be used in photoactive layer 240.
  • electron donor materials include conjugated polymers, such as polythiophenes, polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, polycyclopentadithiophenes, polysilacyclopentadithiophenes, polycyclopentadithiazoles, polythiazolothiazoles, polythiazoles, polybenzothiadiazoles, poly(thiophene oxide)s, poly(cyclopentadithiophene oxide)s, polythiadiazoloquinoxalines, polybenzoisothiazoles, polybenzothiazoles, polythienothiophenes, poly(thienothiophene oxide)s, polydithienothiophenes, poly(dithienothiophene oxide)s, polytetrahydroisoindoles, and
  • the electron donor material can be polythiophenes (e.g., poly(3-hexylthiophene)), polycyclopentadithiophenes, and copolymers thereof.
  • a combination of electron donor materials can be used in photoactive layer 240.
  • the electron donor materials or the electron acceptor materials can include a polymer having a first comonomer repeat unit and a second comonomer repeat unit different from the first comonomer repeat unit.
  • the first comonomer repeat unit can include a cyclopentadithiophene moiety, a silacyclopentadithiophene moiety, a cyclopentadithiazole moiety, a thiazolothiazole moiety, a thiazole moiety, a benzothiadiazole moiety, a thiophene oxide moiety, a cyclopentadithiophene oxide moiety, a polythiadiazoloquinoxaline moiety, a benzoisothiazole moiety, a benzothiazole moiety, a thienothiophene moiety, a thienothiophene oxide moiety, a dithienothiophene moiety, a dithieno
  • the first comonomer repeat unit includes a cyclopentadithiophene moiety.
  • the cyclopentadithiophene moiety is substituted with at least one substituent selected from the group consisting of Ci-C 2O alkyl, C1-C20 alkoxy, C3-C20 cycloalkyl, Ci-C2o heterocycloalkyl, aryl, heteroaryl, halo, CN, OR, C(O)R, C(O)OR, and SO 2 R; R being H, Ci-C 20 alkyl, Ci-C 20 alkoxy, aryl, heteroaryl, Cs-C 20 cycloalkyl, or Ci-C 20 heterocycloalkyl.
  • the cyclopentadithiophene moiety can be substituted with hexyl, 2-ethylhexyl, or 3,7- dimethyloctyl.
  • the cyclopentadithiophene moiety is substituted at 4-position.
  • the first comonomer repeat unit can include a cyclopentadithiophene moiety of formula (1):
  • each of Ri and R 2 independently, can be hexyl, 2- ethylhexyl, or 3,7-dimethyloctyl.
  • An alkyl can be saturated or unsaturated and branch or straight chained.
  • a Ci-C 20 alkyl contains 1 to 20 carbon atoms (e.g., one, two , three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 carbon atoms).
  • An alkoxy can be branch or straight chained and saturated or unsaturated.
  • Ci-C 20 alkoxy contains an oxygen radical and 1 to 20 carbon atoms (e.g., one, two , three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 carbon atoms).
  • a cycloalkyl can be either saturated or unsaturated.
  • a C3-C 2 0 cycloalkyl contains 3 to 20 carbon atoms (e.g., three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 carbon atoms).
  • cycloalkyl moieities include cyclohexyl and cyclohexen-3-yl.
  • a heterocycloalkyl can also be either saturated or unsaturated.
  • a C 3 -C 20 heterocycloalkyl contains at least one ring heteroatom (e.g., O, N, and S) and 3 to 20 carbon atoms (e.g., three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 carbon atoms).
  • heterocycloalkyl moieties include 4-tetrahydropyranyl and 4-pyranyl.
  • An aryl can contain one or more aromatic rings.
  • aryl moieties include phenyl, phenylene, naphthyl, naphthylene, pyrenyl, anthryl, and phenanthryl.
  • a heteroaryl can contain one or more aromatic rings, at least one of which contains at least one ring heteroatom (e.g., O, N, and S).
  • heteroaryl moieties include furyl, furylene, fluorenyl, pyrrolyl, thienyl, oxazolyl, imidazolyl, thiazolyl, pyridyl, pyrimidinyl, quinazolinyl, quinolyl, isoquinolyl, and indolyl.
  • Alkyl, alkoxy, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl mentioned herein include both substituted and unsubstituted moieties, unless specified otherwise.
  • substituents on cycloalkyl, heterocycloalkyl, aryl, and heteroaryl include C 1 - C 2O alkyl, C 3 -C 2O cycloalkyl, C 1 -C 20 alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, amino, C 1 -C 10 alkylamino, C 1 -C 2 0 dialkylamino, arylamino, diarylamino, hydroxyl, halogen, thio, C 1 -C 10 alkylthio, arylthio, C 1 -C 10 alkylsulfonyl, arylsulfonyl, cyano, nitro, acyl, acyloxy, carboxyl, and carboxylic
  • the second comonomer repeat unit can include a benzothiadiazole moiety, a thiadiazoloquinoxaline moiety, a cyclopentadithiophene oxide moiety, a benzoisothiazole moiety, a benzothiazole moiety, a thiophene oxide moiety, a thienothiophene moiety, a thienothiophene oxide moiety, a dithienothiophene moiety, a dithienothiophene oxide moiety, a tetrahydroisoindole moiety, a fluorene moiety, a silole moiety, a cyclopentadithiophene moiety, a fluorenone
  • the second comonomer repeat unit is a 3,4-benzo-l,2,5- thiadiazole moiety.
  • the second comonomer repeat unit can include a benzothiadiazole moiety of formula (2), a thiadiazoloquinoxaline moiety of formula (3), a cyclopentadithiophene dioxide moiety of formula (4), a cyclopentadithiophene monoxide moiety of formula (5), a benzoisothiazole moiety of formula (6), a benzothiazole moiety of formula (7), a thiophene dioxide moiety of formula (8), a cyclopentadithiophene dioxide moiety of formula (9), a cyclopentadithiophene tetraoxide moiety of formula (10), a thienothiophene moiety of formula (11), a thienothiophene tetraoxide moiety of formula (12
  • each of X and Y is CH 2 , O, or S; each of R5 and R 6 , independently, is H, C1-C20 alkyl, C1-C20 alkoxy, C3-C20 cycloalkyl, C1-C20 heterocycloalkyl, aryl, heteroaryl, halo, CN, OR, C(O)R, C(O)OR, or SO 2 R, in which R is H, C1-C20 alkyl, C1-C20 alkoxy, aryl, heteroaryl, C3-C20 cycloalkyl, or C1-C20 heterocycloalkyl; and each Of R 7 and Rs, independently, is H, C1-C20 alkyl, C1-C20 alkoxy, aryl, heteroaryl, C3-C20 cycloalkyl, or C3-C20 heterocycloalkyl.
  • the second comonomer repeat unit includes a be
  • the second comonomer repeat unit can include at least three thiophene moieties.
  • at least one of the thiophene moieties is substituted with at least one substituent selected from the group consisting of C 1 -C 20 alkyl, Ci-C 20 alkoxy, aryl, heteroaryl, C3-C 2 o cycloalkyl, and C3-C 2 o heterocycloalkyl.
  • the second comonomer repeat unit includes five thiophene moieties.
  • the polymer can further include a third comonomer repeat unit that contains a thiophene moiety or a fluorene moiety.
  • the thiophene or fluorene moiety is substituted with at least one substituent selected from the group consisting of C1-C20 alkyl, C1-C20 alkoxy, aryl, heteroaryl, C3-C20 cycloalkyl, and C3-C20 heterocycloalkyl.
  • the polymer can be formed by any combination of the first, second, and third comonomer repeat units. In certain embodiments, the polymer can be a homopolymer containing any of the first, second, and third comonomer repeat units.
  • n can be an integer greater than 1.
  • the monomers for preparing the polymers mentioned herein may contain a non- aromatic double bond and one or more asymmetric centers. Thus, they can occur as racemates and racemic mixtures, single enantiomers, individual diastereomers, diastereomeric mixtures, and cis- or trans- isomeric forms. All such isomeric forms are contemplated.
  • a copolymer can be prepared by methods known in the art, such as those described in commonly owned co-pending U.S. Application No 11/601,374, the contents of which are hereby incorporated by reference.
  • a copolymer can be prepared by a cross-coupling reaction between one or more comonomers containing two alkylstannyl groups and one or more comonomers containing two halo groups in the presence of a transition metal catalyst.
  • a copolymer can be prepared by a cross-coupling reaction between one or more comonomers containing two borate groups and one or more comonomers containing two halo groups in the presence of a transition metal catalyst.
  • the comonomers can be prepared by the methods known in the art, such as those described in U.S. Patent Application Serial No. 11/486,536, Coppo et al, Macromolecules 2003, 36, 2705-2711 and Kurt et al, J. Heterocycl. Chem. 1970, 6, 629, the contents of which are hereby incorporated by reference. Without wishing to be bound by theory, it is believed that an advantage of the polymers described above is that their absorption wavelengths shift toward the red and near IR regions (e.g., 650 - 800 nm) of the electromagnetic spectrum, which is not accessible by most other conventional polymers.
  • red and near IR regions e.g., 650 - 800 nm
  • photoactive layer 240 is sufficiently thick to be relatively efficient at absorbing photons impinging thereon to form corresponding electrons and holes, and sufficiently thin to be relatively efficient at transporting the holes and electrons.
  • photoactive layer 240 is at least 0.05 micron (e.g., at least about 0.1 micron, at least about 0.2 micron, or at least about 0.3 micron) thick and/or at most about one micron (e.g., at most about 0.5 micron or at most about 0.4 micron) thick. In some embodiments, photoactive layer 240 is from about 0.1 micron to about 0.2 micron thick.
  • Hole blocking layer 250 is generally formed of a material that, at the thickness used in photovoltaic cell 200, transports electrons to anode 260 and substantially blocks the transport of holes to anode 260.
  • materials from which layer 250 can be formed include LiF, amines (e.g., primary, secondary, or tertiary amines), and metal oxides (e.g., zinc oxide or titanium oxide).
  • hole blocking layer 250 is at least 0.02 micron (e.g., at least about 0.03 micron, at least about 0.04 micron, or at least about 0.05 micron) thick and/or at most about 0.5 micron (e.g., at most about 0.4 micron, at most about 0.3 micron, at most about 0.2 micron, or at most about 0.1 micron) thick.
  • Anode 260 is generally formed of an electrically conductive material, such as one or more of the electrically conductive materials described above. In some embodiments, anode 260 is formed of a combination of electrically conductive materials. In certain embodiments, anode 260 can be formed of a mesh electrode.
  • Substrate 270 can be identical to or different from substrate 210.
  • substrate 270 can be formed of one or more suitable polymers, such as those described above.
  • FIG. 3 shows a tandem photovoltaic cell 300 having two semi-cells 302 and 304.
  • Semi-cell 302 includes a cathode 320, a hole carrier layer 330, a first photoactive layer 340, and a recombination layer 342.
  • Semi-cell 304 includes recombination layer 342, a second photoactive layer 344, a hole blocking layer 350, and an anode 360.
  • An external load is connected to photovoltaic cell 300 via cathode 320 and anode 360.
  • the current flow in a semi-cell can be reversed by changing the electron/hole conductivity of a certain layer (e.g., changing hole blocking layer 350 to a hole carrier layer).
  • a tandem cell can be designed such that the semi-cells in the tandem cells can be electrically interconnected either in series or in parallel.
  • a recombination layer refers to a layer in a tandem cell where the electrons generated from a first semi-cell recombine with the holes generated from a second semi- cell.
  • Recombination layer 342 typically includes a p-type semiconductor material and an n-type semiconductor material.
  • n-type semiconductor materials selectively transport electrons and p-type semiconductor materials selectively transport holes.
  • the p-type semiconductor material includes a polymer and/or a metal oxide.
  • Examples p-type semiconductor polymers include polythiophenes (e.g., poly(3,4-ethylene dioxythiophene) (PEDOT)), polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, polycyclopentadithiophenes, polysilacyclopentadithiophenes, polycyclopentadithiazoles, polythiazolothiazoles, polythiazoles, polybenzothiadiazoles, poly(thiophene oxide)s, poly(cyclopentadithiophene oxide)s, polythiadiazoloquinoxaline, polybenzoisothiazole, polybenzothiazole, polythienothiophene, poly(thienothiophene oxide), polydithienothiophene, poly(dithienothiophene oxide)
  • the metal oxide can be an intrinsic p-type semiconductor (e.g., copper oxides, strontium copper oxides, or strontium titanium oxides) or a metal oxide that forms a p-type semiconductor after doping with a dopant (e.g., p-doped zinc oxides or p-doped titanium oxides).
  • a dopant e.g., p-doped zinc oxides or p-doped titanium oxides.
  • dopants includes salts or acids of fluoride, chloride, bromide, and iodide.
  • the metal oxide can be used in the form of nanoparticles.
  • the n-type semiconductor material includes a metal oxide, such as titanium oxides, zinc oxides, tungsten oxides, molybdenum oxides, and combinations thereof.
  • the metal oxide can be used in the form of nanoparticles.
  • the n-type semiconductor material includes a material selected from the group consisting of fullerenes, inorganic nanoparticles, oxadiazoles, discotic liquid crystals, carbon nanorods, inorganic nanorods, polymers containing CN groups, polymers containing CF 3 groups, and combinations thereof.
  • the p-type and n-type semiconductor materials are blended into one layer.
  • the recombination layer includes two layers, one layer including the p-type semiconductor material and the other layer including the n-type semiconductor material.
  • recombination layer 342 includes at least about 30 wt%
  • recombination layer 342 includes at least about 30 wt% (e.g., at least about 40 wt% or at least about 50 wt%) and/or at most about 70 wt% (e.g., at most about 60 wt% or at most about 50 wt%) of the n-type semiconductor material.
  • Recombination layer 342 generally has a sufficient thickness so that the layers underneath are protected from any solvent applied onto recombination layer 342.
  • recombination layer 342 can have a thickness at least about 10 nm (e.g., at least about 20 nm, at least about 50 nm, or at least about 100 nm) and/or at most about 500 nm (e.g., at most about 200 nm, at most about 150 nm, or at most about 100 nm).
  • recombination layer 342 is substantially transparent.
  • recombination layer 342 can transmit at least about 70% (e.g., at least about 75%, at least about 80%, at least about 85%, or at least about 90%) of incident light at a wavelength or a range of wavelengths (e.g., from about 350 nm to about 1,000 nm) used during operation of the photovoltaic cell.
  • Recombination layer 342 generally has a sufficiently low resistivity. In some embodiments, recombination layer 342 has a resistivity of at most about 1 x 10 6 ohm/square, (e.g., at most about 5 x 10 5 ohm/square, at most about 2 x 10 5 ohm/square, or at most about 1 x 10 5 ohm/square).
  • recombination layer 342 can be considered as a common electrode between two semi-cells (e.g., one including cathode 320, hole carrier layer 330, photoactive layer 340, and recombination layer 342, and the other include recombination layer 342, photoactive layer 344, hole blocking layer 350, and anode 360) in photovoltaic cells 300.
  • recombination layer 342 can include an electrically conductive mesh material, such as those described above.
  • An electrically conductive mesh material can provide a selective contact of the same polarity (either p-type or n-type) to the semi-cells and provide a highly conductive but transparent layer to transport electrons to a load.
  • recombination layer 342 can be prepared by applying a blend of an n-type semiconductor material and a p-type semiconductor material on photoactive layer. For example, an n-type semiconductor and a p-type semiconductor can be first dispersed and/or dissolved in a solvent together to form a dispersion or solution and then coated the dispersion or solution on a photoactive layer to form a recombination layer.
  • recombination layer 342 can include two or more layers with required electronic and optical properties for tandem cell functionality.
  • recombination layer 342 includes a layer that contains an n-type semiconductor material and a layer that contains a p-type semiconductor material.
  • recombination layer 342 can include a layer of mixed n-type and p-type semiconductor material at the interface of the two layers.
  • a two-layer recombination layer can be prepared by applying a layer of an n-type semiconductor material and a layer of a p-type semiconductor material separately.
  • a layer of titanium oxide nanoparticles can be formed by (1) dispersing a precursor (e.g., a titanium salt) in a solvent (e.g., an anhydrous alcohol) to form a dispersion, (2) coating the dispersion on a photoactive layer, (3) hydrolyzing the dispersion to form a titanium oxide layer, and (4) drying the titanium oxide layer.
  • a precursor e.g., a titanium salt
  • a solvent e.g., an anhydrous alcohol
  • a polymer layer can be formed by first dissolving the polymer in a solvent (e.g., an anhydrous alcohol) to form a solution and then coating the solution on a photoactive layer.
  • a solvent e.g., an anhydrous alcohol
  • tandem cell 300 can be identical to those in photovoltaic cell 200 described above.
  • the semi-cells in a tandem cell are electrically interconnected in series. When connected in series, in general, the layers can be in the order shown in FIG. 3.
  • the semi-cells in a tandem cell are electrically interconnected in parallel.
  • a tandem cell having two semi-cells can include the following layers: a first cathode, a first hole carrier layer, a first photoactive layer, a first hole blocking layer (which can serve as an anode), a second hole blocking layer (which can serve as an anode), a second photoactive layer, a second hole carrier layer, and a second cathode.
  • the first and second hole blocking layers can be either two separate layers or can be one single layer.
  • an additional layer e.g., an electrically conductive mesh layer
  • an electrically conductive mesh layer providing the required conductivity may be inserted.
  • a tandem cell can include more than two semi-cells (e.g., three, four, five, six, seven, eight, nine, ten, or more semi-cells).
  • some semi-cells can be electrically interconnected in series and some semi-cells can be electrically interconnected in parallel.
  • a layer can be prepared by a liquid-based coating process.
  • liquid-based coating process refers to a process that uses a liquid-based coating composition.
  • the liquid- based coating composition can be a solution, a dispersion, or a suspension.
  • the liquid- based coating process can be carried out by using at least one of the following processes: solution coating, ink jet printing, spin coating, dip coating, knife coating, bar coating, spray coating, roller coating, slot coating, gravure coating, flexographic printing, or screen printing. Examples of liquid-based coating processes have been described in, for example, commonly-owned co-pending U.S. Application 60/888,704, the contents of which are hereby incorporated by reference.
  • a layer can be prepared via a gas phase-based coating process, such as chemical or physical vapor deposition processes.
  • the photovoltaic cells described in FIGs. 2 and 3 can be prepared in a continuous manufacturing process, such as a roll-to-roll process, thereby significantly reducing the preparation cost.
  • a continuous manufacturing process such as a roll-to-roll process
  • roll-to-roll processes have been described in, for example, commonly-owned co-pending U.S. Application Publication No. 2005-0263179, the contents of which are hereby incorporated by reference.
  • FIG. 4 is a schematic of a photovoltaic system 400 having a module 410 containing photovoltaic cells 420. Cells 420 are electrically connected in series, and system 400 is electrically connected to a load 430.
  • FIG. 5 is a schematic of a photovoltaic system 500 having a module 510 that contains photovoltaic cells 520. Cells 520 are electrically connected in parallel, and system 500 is electrically connected to a load 530.
  • some (e.g., all) of the photovoltaic cells in a photovoltaic system can have one or more common substrates.
  • some photovoltaic cells in a photovoltaic system are electrically connected in series, and some of the photovoltaic cells in the photovoltaic system are electrically connected in parallel.
  • Other embodiments are in the claims.

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Abstract

L'invention concerne des cellules photovoltaïques contenant une pluralité de lignes conduisant l'électricité et des systèmes, procédés, modules et composants associés.
PCT/US2007/063669 2006-03-09 2007-03-09 Cellules photovoltaïques WO2007104039A2 (fr)

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JP5298308B2 (ja) * 2005-09-06 2013-09-25 国立大学法人京都大学 有機薄膜光電変換素子及びその製造方法
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KR20080104181A (ko) 2008-12-01
EP1997219A4 (fr) 2009-07-22

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