WO2009001471A1 - Fine silicon particle and method of manufacture and solar cell using the fine silicon particle and method of manufacture - Google Patents

Fine silicon particle and method of manufacture and solar cell using the fine silicon particle and method of manufacture Download PDF

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Publication number
WO2009001471A1
WO2009001471A1 PCT/JP2007/063052 JP2007063052W WO2009001471A1 WO 2009001471 A1 WO2009001471 A1 WO 2009001471A1 JP 2007063052 W JP2007063052 W JP 2007063052W WO 2009001471 A1 WO2009001471 A1 WO 2009001471A1
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fine silicon
covalently bound
functional group
silicon particles
organic thin
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PCT/JP2007/063052
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French (fr)
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Kazufumi Ogawa
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Kazufumi Ogawa
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Priority to PCT/JP2007/063052 priority Critical patent/WO2009001471A1/en
Publication of WO2009001471A1 publication Critical patent/WO2009001471A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02524—Group 14 semiconducting materials
    • H01L21/02532—Silicon, silicon germanium, germanium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02587—Structure
    • H01L21/0259—Microstructure
    • H01L21/02601—Nanoparticles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/02623—Liquid deposition
    • H01L21/02628—Liquid deposition using solutions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • 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
    • H10K30/10—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising heterojunctions between organic semiconductors and inorganic semiconductors
    • 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
    • H10K30/50—Photovoltaic [PV] devices

Definitions

  • the present invention is related to a solar cell and method for manufacturing the same.
  • it relates to a solar cell using fine particles and a method of manufacture in which the surface of the semiconductive fine silicon particles are given thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity.
  • the fine silicon particle shall include semi-conductive p-type fine silicon particles and semi-conductive n-type fine silicon particles.
  • Conventional silicon solar cells are known to include silicon amorphous solar cells that are formed into a film on a glass substrate surface using plasma CVD and silicon crystal solar cells in which silicon crystal or polysilicon crystal is cut into plate form and then impurities are diffused.
  • silicon amorphous solar cells that are formed into a film on a glass substrate surface using plasma CVD
  • silicon crystal solar cells in which silicon crystal or polysilicon crystal is cut into plate form and then impurities are diffused.
  • Patent document 1 Japanese Patent Application Laid Open No. 10-247629
  • the present invention aims to provide fine silicon particles, a method for manufacturing the same, a solar cell using the fine silicon particles, and a method for manufacturing the same that allows a significant reduction in costs, while using silicon, compared to the use of conventional amorphous solar cells or silicon crystal solar cells.
  • the second aspect of this invention is the fine silicon particle of the first aspect of this invention in which the organic thin film covalently bound to the surface comprises molecules that include a functional group at one end and covalently bind to the surface of the fine silicon particle via Si at the other end.
  • the third aspect of this invention is the fine silicon particle of the second aspect of this invention in which the functional group is a reactive functional group.
  • the fourth aspect of this invention is the fine silicon particle of the third aspect of this invention in which the reactive functional group is a functional group with either thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity.
  • the fifth aspect of this invention is the fine silicon particle of the third aspect of this invention in which the reactive functional group is either an epoxy group or imino group or otherwise a chalcone group.
  • the sixth aspect of this invention is the fine silicon particles of the first and second aspects of this invention in which the organic thin film covalently bound to the surface comprises a monomolecular film.
  • the seventh aspect of this invention is a method for manufacturing a fine silicon particle comprising a process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid produced from a mixture of at least an alkoxysilane compound, a silanol condensation catalyst, and a nonaqueous organic solvent.
  • the eighth aspect of this invention is a method for manufacturing a fine silicon particle of the seventh aspect of this invention comprising the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid and then cleaning the surface of the fine silicon particle with an organic solvent to form a monomolecular film covalently bound to the surface of the fine silicon particle.
  • the ninth aspect of this invention is a method for manufacturing a fine silicon particle of the seventh aspect of this invention in which a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is used instead of the silanol condensation catalyst.
  • the tenth aspect of this invention is the method for manufacturing a fine silicon particle of the seventh aspect of this invention in which at least one promoter chosen from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is mixed with the silanol condensation catalyst.
  • the eleventh aspect of this invention is a solar cell in which a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer.
  • the twelfth aspect of this invention is a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles, and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
  • the thirteenth aspect of this invention is the solar cells of the eleventh and twelfth aspects of this invention in which the organic thin film covalently bound to the surface comprises molecules that include a reactive functional group at one end and covalently bind to the surface of the semiconductive fine silicon particle via Si at the other end.
  • the fourteenth aspect of this invention is the solar cell of the thirteenth aspect of this invention in which the reactive functional group is a functional group with thermal reactivity or ionic reactivity.
  • the fifteenth aspect of this invention is the solar cell of the thirteenth aspect of this invention in which the reactive functional group is an epoxy group or imino group.
  • the sixteenth aspect of this invention is the solar cell of the eleventh or twelfth aspect of this invention in which the organic thin film covalently bound to the surface comprises a monomolecular film.
  • the seventeenth aspect of this invention is the solar cells of the eleventh to sixteenth aspects of this invention in which the surface of the base material covered by an organic thin film covalently bound to the surface, the layer of n-type fine silicon particles covered by an organic thin film, and the layer of p-type fine silicon particles covered by an organic thin film are covalently bound with each other via the respective organic thin film to form a hardened film.
  • the eighteenth aspect of this invention is a method for manufacturing a solar cell comprising a process of forming a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of a base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
  • the nineteenth aspect of this invention is the method for manufacturing a solar cell of the eighteenth aspect of this invention in which prior to the application of the paste to the base material, an organic thin film, including a functional group that reacts with the first or second reactive functional group on the surface of the fine silicon particle covered by an organic film, including the first reactive functional group or of the fine silicon particle covered by an organic film, including the second reactive functional group, is bound to the surface of the base material.
  • the gist of the present invention provides a fine silicon particle covered by an organic thin film covalently bound to the surface through the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid produced from a mixture of at least an alkoxysilane compound, a silanol condensation catalyst, and a nonaqueous organic solvent.
  • a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is used instead of the silanol condensation catalyst, it advantageously reduces the reaction time.
  • the organic thin film covalently bound to the surface comprises molecules that include a functional group at one end and covalently bind to the surface of the fine silicon particle via Si at the other end, it advantageously gives new functionality to the fine silicon particle.
  • the functional group is a reactive functional group, it is advantageous to form the fine silicon particles into a film.
  • the reactive functional group is a functional group with either thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity, it is advantageous to give reactivity.
  • the reactive functional group is an epoxy group, imino group, or chalcone group, it is advantageous to generate a strong bond to increase the reliability.
  • the organic thin film covalently bound to the surface comprises a monomolecular film, it is advantageous to improve the silicon density.
  • the gist of the present invention provides a solar cell in which at least a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer through a process of forming a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of a
  • the gist of the present invention provides a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles; and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
  • the organic thin film covalently bound to the surface comprises molecules that include a reactive functional group at one end and covalently bind to the surface of the semiconductive fine silicon particle via Si at the other end, those fine silicon particles can be advantageously stabilized even more to form a film.
  • the reactive functional group is a functional group with thermal reactivity or ionic reactivity, it advantageously forms a film with higher reliability.
  • the reactive functional group is an epoxy group or imino group, it advantageously forms a film with even higher reliability.
  • the organic thin film covalently bound to the surface comprises a monomolecular film, it advantageously forms a film with higher silicon density.
  • the surface of the base material covered by an organic thin film covalently bound to the surface, the layer of n-type fine silicon particles covered by an organic thin film, and the layer of p-type fine silicon particles covered by an organic thin film are covalently bound with each other via the respective organic thin film to form a hardened film, it advantageously allows the manufacture of a solar cell with high conversion efficiency and reliability.
  • this invention has an effect of providing fine silicon particles with a stabilizing function, a function to improve the dispersibility into various solvents, and various reactive functions while maintaining most of the original functions of the fine silicon particles. Furthermore, if covering with a chemically absorbed monomolecular film, this invention has a special effect of providing fine silicon particles with a stabilizing function, a function to improve dispersibility into various solvents, and various chemical reaction functions while almost completely maintaining the original shape and functions of the fine silicon particles. It also has an effect of manufacturing a high-efficiency silicon solar cell at an extremely low cost.
  • FIG. 1 is a conceptual diagram of the first example of the present invention that enlarges the reaction of the fine silicon particle to the molecular level.
  • FIG. 1A shows the surface of the fine silicon particle before the reaction.
  • FIG. 1 B shows the surface after a monomolecular film containing an epoxy group is formed.
  • FIG. 1C shows the surface after a monomolecular film containing an amino group is formed.
  • FIG. 2 shows a section conceptual diagram of the solar cell that uses the fine silicon particle of the second example of the present invention.
  • the present invention provides a solar cell in which at least a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer through a process of forming a paste by mixing into an organic solvent the fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material, a process of forming a paste by mixing into an organic solvent the fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
  • the present invention provides a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles; and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
  • the present invention provides fine silicon particles with a function to stabilize its own particle surface, a function to improve the dispersibility into various solvents, and various chemical reaction functions while almost completely maintaining the original shape and functions of the fine silicon particles. It also works to manufacture and provide a high-efficiency silicon solar cell at an extremely low cost.
  • the fine silicon particles related to the present invention include semiconductive p-type and n-type fine silicon particles.
  • the p-type fine silicon particle is used to explain the representative example.
  • Example 1 First, p-type fine silicon particles 1 with a particle diameter ranging from 100 to 10 nm were prepared and dried thoroughly.
  • an agent containing a reactive functional group e.g. epoxy group or imino group
  • an alkoxysilane compound at the other end for example the agent shown in the following chemical formula [Formula 1] or [Formula 2]
  • a silanol condensation catalyst for example, dibutyltin diacetylacetonate or acetic acid (a type of organic acid) was measured to be 1 w/t %, respectively.
  • a chemical absorption monomolecular film 3 containing epoxy groups or a chemical absorption monomolecular film 4 containing amino groups, which forms a chemical bond with the surface of the fine silicon particle throughout the surface was formed at a thickness of about 1 nm, because of the bonding formation shown in the following chemical formula [Formula 3] or [Formula 4] by a dealcoholization reaction (in this case, de-CH 3 OH) between Si(OCH 3 ) group of the foregoing chemical absorption agent and the foregoing hydroxyl groups under the presence of the silanol condensation catalyst or the organic acid (shown in FIG.S 1 B and 1C).
  • a dealcoholization reaction in this case, de-CH 3 OH
  • an adsorption agent containing an amino group When using an adsorption agent containing an amino group, it was better to use an organic acid, such as acetic acid, since the tintype catalyst produced a deposition.
  • the amino group contains an imino group, substances such as pyrrole derivative and imidazole derivatives other than the amino group also contain the imino group.
  • a ketimine derivative when a ketimine derivative was used, the amino group was easily introduced by hydrolysis after the coating formation.
  • the processed part had an extremely thin coating with a film thickness at the nanometer level, the particle diameter was not impaired.
  • this coating had a voltage of 0.1 V or less, it had almost no electrical insulating characteristics while maintaining the ability to prevent the oxidization process of silicon.
  • Example 1 Although the above Example 1 used the substance shown in [Formula 1] or [Formula 2] as a chemical absorption agent containing a reactive group, the following substances (1) to (16) other than those described above could also be used.
  • the following substances (17) to (22) could also be used as a chemical absorption agent containing the energy beam reactive functional group for a light or electron beam.
  • an energy beam such as light, electron beams, or the like shall be irradiated for hardening.
  • Example 1 for the silanol condensation catalyst, groups of carboxylic acid metal salt, carboxylic acid ester metal salt, carboxylic acid metal salt polymer, carboxylic acid metal salt chelate, titanic acid ester, and titanic acid ester chelate are available.
  • stannous acetic acid dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin dilaurate, dioctyltin dioctate, dioctyltin diacetate, stannous dioctanoic acid, lead naphthenate, cobalt naphthenate, iron 2-ethylhexanoate, dioctyltin bis-octylthioglycolate ester, dioctyltin maleate ester, dibutyltin maleate polymer, dimethyltin mercaptopropionate polymer, dibutyltin bis-acetylacetate, dioctyltin bis-acetyl laurate, tetrabutyltitanate, tetranonyltitanate, and bis(acetylacetonyl) diprop
  • an anhydrous organochlorine solvent, hydrocarbon solvent, fluorocarbon solvent, silicon solvent, or a mixture of these were available as a solvent when using an alkoxysilane type or a chlorosilane type chemical absorption agent. If increasing the particle concentration by evaporating the solvent without cleaning, the boiling point of the solvent is preferably between 50 and 250 degrees Celsius.
  • an organochlorine solvent nonaqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, n-paraffin, decalin, industrial gasoline, nonan, decane, kerosene, dimethyl silicon, phenyl silicon, alkyl modified silicon, polyether silicon, and dimethylformamide
  • the adsorption agent is an alkoxysilane type and the organic coating is formed by evaporating the solvent
  • an alcohol solvent such as methanol, ethanol, propanol, or a mixture of these, was able to be used in addition to the above listed solvents.
  • the fluorocarbon solvent can be a chlorofluorocarbon solvent, Fluorinert (a product manufactured by 3M Company), and Aflude (a product manufactured by Asahi Glass Co., Ltd.). These may be used solely, or two or more kinds may be mixed if the combination blends well.
  • an organochlorine solvent such as chloroform may be added.
  • the processing time was several times faster (to about half an hour), so that the time of film formation was reduced to a fraction.
  • a dibutyltin oxide which is a silanol catalyst
  • H3 from Japan Epoxy Resins Co., Ltd.
  • the activity was further enhanced when the silanol condensation catalyst was mixed with one selected from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and aminoalkylalkoxysilane compound.
  • a ketimine compound organic acid, aldimine compound, enamine compound, oxazolidine compound, and aminoalkylalkoxysilane compound.
  • the available ketimine compounds are not particularly limited, and include the following examples: 2,5,8-triaza-1 ,8-nonadien;
  • organic acids there are also no particular limitations to the organic acids available; however, for example, formic acid, acetic acid, propionic acid, butyric acid, and malonic acid showed almost the same effect.
  • Example 2 The same method as Example 1 was used to form a chemical absorption monomolecular film with an epoxy group or amino group on n-type fine silicon particles 11, and the same amount of the n-type fine silicon particles covered by epoxy group 12 and the n-type fine silicon particles covered by amino group 13 were sampled and mixed well in isopropyl alcohol to form a paste.
  • the paste was applied to an ITO transparent electrode 15, which was preformed on the surface of a glass substrate 14, and heated at 50 to 100 degrees Celsius for hardening to form a coating film 16 of n-type fine silicon particles with a film thickness of about 1 micron.
  • Example 2 the same amount of the p-type fine silicon particles 5 and 6 obtained in Example 1 , which were covered by a chemical absorption monomolecular film containing an epoxy group or amino group, were sampled and mixed well in isopropyl alcohol to form a paste.
  • the paste was applied to the surface of the coating film 16 of the foregoing n-type fine silicon particles and heated at 50 to 100 degrees Celsius to form a coating film 17 of the p-type fine silicon particles with a film thickness of about 1 micron.
  • an Al film 18 was formed as a back surface electrode by evaporation to create a solar cell that receives light 19 irradiated from the side of the glass substrate.
  • the reactive monomolecular films on the surface of the p-type and n-type fine silicon particles serve to form a hardened film of fine silicon particles and to protect against the oxidation of p-type and n-type fine silicon particles in the atmosphere. Since this reactive monomolecular film has a thickness of about 1 nm, it does not interfere with the conductivity of the silicon.
  • the range of the absorption wavelength was controlled from the infrared light region to the visible light region.
  • any semiconductive fine particles that contain active hydrogen, such as hydrogen of the hydroxyl group, on the surface are available as semi-conductive fine particles for the present invention.

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Abstract

A solar cell in which a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer through a process of forming a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface, and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.

Description

DESCRIPTION
FINE SILICON PARTICLE AND METHOD OF MANUFACTURE AND SOLAR CELL
USING THE FINE SILICON PARTICLE AND METHOD OF MANUFACTURE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention is related to a solar cell and method for manufacturing the same. In particular, it relates to a solar cell using fine particles and a method of manufacture in which the surface of the semiconductive fine silicon particles are given thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity.
In the present invention, the fine silicon particle shall include semi-conductive p-type fine silicon particles and semi-conductive n-type fine silicon particles. Description of Related Art
Conventional silicon solar cells are known to include silicon amorphous solar cells that are formed into a film on a glass substrate surface using plasma CVD and silicon crystal solar cells in which silicon crystal or polysilicon crystal is cut into plate form and then impurities are diffused. For example, the following patent is acknowledged.
[Patent document 1] Japanese Patent Application Laid Open No. 10-247629
However, conventional silicon amorphous solar cells have the disadvantage of high production cost because of the expensive vacuum equipment. In addition, the silicon crystal solar cells have the disadvantage of a high production cost because of the large amount of high purity silicon crystals or polysilicon crystals that are necessary.
The present invention aims to provide fine silicon particles, a method for manufacturing the same, a solar cell using the fine silicon particles, and a method for manufacturing the same that allows a significant reduction in costs, while using silicon, compared to the use of conventional amorphous solar cells or silicon crystal solar cells. SUMMARY OF THE INVENTION
Accordingly, it would be advantageous to provide a fine silicon particle covered by an organic thin film covalently bound to the surface.
The second aspect of this invention is the fine silicon particle of the first aspect of this invention in which the organic thin film covalently bound to the surface comprises molecules that include a functional group at one end and covalently bind to the surface of the fine silicon particle via Si at the other end.
The third aspect of this invention is the fine silicon particle of the second aspect of this invention in which the functional group is a reactive functional group. The fourth aspect of this invention is the fine silicon particle of the third aspect of this invention in which the reactive functional group is a functional group with either thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity.
The fifth aspect of this invention is the fine silicon particle of the third aspect of this invention in which the reactive functional group is either an epoxy group or imino group or otherwise a chalcone group.
The sixth aspect of this invention is the fine silicon particles of the first and second aspects of this invention in which the organic thin film covalently bound to the surface comprises a monomolecular film. The seventh aspect of this invention is a method for manufacturing a fine silicon particle comprising a process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid produced from a mixture of at least an alkoxysilane compound, a silanol condensation catalyst, and a nonaqueous organic solvent. The eighth aspect of this invention is a method for manufacturing a fine silicon particle of the seventh aspect of this invention comprising the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid and then cleaning the surface of the fine silicon particle with an organic solvent to form a monomolecular film covalently bound to the surface of the fine silicon particle.
The ninth aspect of this invention is a method for manufacturing a fine silicon particle of the seventh aspect of this invention in which a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is used instead of the silanol condensation catalyst.
The tenth aspect of this invention is the method for manufacturing a fine silicon particle of the seventh aspect of this invention in which at least one promoter chosen from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is mixed with the silanol condensation catalyst.
The eleventh aspect of this invention is a solar cell in which a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer.
The twelfth aspect of this invention is a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles, and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
The thirteenth aspect of this invention is the solar cells of the eleventh and twelfth aspects of this invention in which the organic thin film covalently bound to the surface comprises molecules that include a reactive functional group at one end and covalently bind to the surface of the semiconductive fine silicon particle via Si at the other end.
The fourteenth aspect of this invention is the solar cell of the thirteenth aspect of this invention in which the reactive functional group is a functional group with thermal reactivity or ionic reactivity.
The fifteenth aspect of this invention is the solar cell of the thirteenth aspect of this invention in which the reactive functional group is an epoxy group or imino group.
The sixteenth aspect of this invention is the solar cell of the eleventh or twelfth aspect of this invention in which the organic thin film covalently bound to the surface comprises a monomolecular film.
The seventeenth aspect of this invention is the solar cells of the eleventh to sixteenth aspects of this invention in which the surface of the base material covered by an organic thin film covalently bound to the surface, the layer of n-type fine silicon particles covered by an organic thin film, and the layer of p-type fine silicon particles covered by an organic thin film are covalently bound with each other via the respective organic thin film to form a hardened film.
The eighteenth aspect of this invention is a method for manufacturing a solar cell comprising a process of forming a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of a base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
The nineteenth aspect of this invention is the method for manufacturing a solar cell of the eighteenth aspect of this invention in which prior to the application of the paste to the base material, an organic thin film, including a functional group that reacts with the first or second reactive functional group on the surface of the fine silicon particle covered by an organic film, including the first reactive functional group or of the fine silicon particle covered by an organic film, including the second reactive functional group, is bound to the surface of the base material.
The gist of the present invention is further explained hereinafter.
The gist of the present invention provides a fine silicon particle covered by an organic thin film covalently bound to the surface through the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid produced from a mixture of at least an alkoxysilane compound, a silanol condensation catalyst, and a nonaqueous organic solvent.
In so doing, it advantageously provides a fine silicon particle with a relatively higher silicon content through the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid and then cleaning the surface of the fine silicon particle with an organic solvent to form a monomolecular film covalently bound to the surface of the fine silicon particle.
In addition, if a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is used instead of the silanol condensation catalyst, it advantageously reduces the reaction time.
In addition, if at least one promoter chosen from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is mixed with the silanol condensation catalyst, it advantageously allows further reduction of the reaction time. Moreover, if the organic thin film covalently bound to the surface comprises molecules that include a functional group at one end and covalently bind to the surface of the fine silicon particle via Si at the other end, it advantageously gives new functionality to the fine silicon particle. In addition, if the functional group is a reactive functional group, it is advantageous to form the fine silicon particles into a film. Furthermore, if the reactive functional group is a functional group with either thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity, it is advantageous to give reactivity. Furthermore, if the reactive functional group is an epoxy group, imino group, or chalcone group, it is advantageous to generate a strong bond to increase the reliability. In addition, if the organic thin film covalently bound to the surface comprises a monomolecular film, it is advantageous to improve the silicon density.
In addition, the gist of the present invention provides a solar cell in which at least a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer through a process of forming a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
Further, the gist of the present invention provides a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles; and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate. In so doing, prior to the application of the paste to the base material, if an organic thin film, including a functional group that reacts with the first or second reactive functional group on the surface of the fine silicon particle covered by an organic film, including the first reactive functional group or of the fine silicon particle covered by an organic film, including the second reactive functional group, is bound to the surface of the base material, those fine silicon particles can be advantageously stabilized to form a film.
Moreover, if the organic thin film covalently bound to the surface comprises molecules that include a reactive functional group at one end and covalently bind to the surface of the semiconductive fine silicon particle via Si at the other end, those fine silicon particles can be advantageously stabilized even more to form a film.
Furthermore, if the reactive functional group is a functional group with thermal reactivity or ionic reactivity, it advantageously forms a film with higher reliability. In addition, if the reactive functional group is an epoxy group or imino group, it advantageously forms a film with even higher reliability. In addition, if the organic thin film covalently bound to the surface comprises a monomolecular film, it advantageously forms a film with higher silicon density. Furthermore, if the surface of the base material covered by an organic thin film covalently bound to the surface, the layer of n-type fine silicon particles covered by an organic thin film, and the layer of p-type fine silicon particles covered by an organic thin film are covalently bound with each other via the respective organic thin film to form a hardened film, it advantageously allows the manufacture of a solar cell with high conversion efficiency and reliability.
As described above, this invention has an effect of providing fine silicon particles with a stabilizing function, a function to improve the dispersibility into various solvents, and various reactive functions while maintaining most of the original functions of the fine silicon particles. Furthermore, if covering with a chemically absorbed monomolecular film, this invention has a special effect of providing fine silicon particles with a stabilizing function, a function to improve dispersibility into various solvents, and various chemical reaction functions while almost completely maintaining the original shape and functions of the fine silicon particles. It also has an effect of manufacturing a high-efficiency silicon solar cell at an extremely low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a conceptual diagram of the first example of the present invention that enlarges the reaction of the fine silicon particle to the molecular level. FIG. 1A shows the surface of the fine silicon particle before the reaction. FIG. 1 B shows the surface after a monomolecular film containing an epoxy group is formed. FIG. 1C shows the surface after a monomolecular film containing an amino group is formed.
FIG. 2 shows a section conceptual diagram of the solar cell that uses the fine silicon particle of the second example of the present invention.
DETAILED DESCRIPTION
The present invention provides a solar cell in which at least a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer through a process of forming a paste by mixing into an organic solvent the fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material, a process of forming a paste by mixing into an organic solvent the fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
In addition, the present invention provides a solar cell in which n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the n-type fine silicon particles; and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via the mentioned organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
Therefore, the present invention provides fine silicon particles with a function to stabilize its own particle surface, a function to improve the dispersibility into various solvents, and various chemical reaction functions while almost completely maintaining the original shape and functions of the fine silicon particles. It also works to manufacture and provide a high-efficiency silicon solar cell at an extremely low cost.
Although examples are hereinafter used to describe the details of the present invention, these examples shall not be construed as limiting the present invention. The fine silicon particles related to the present invention include semiconductive p-type and n-type fine silicon particles. First, the p-type fine silicon particle is used to explain the representative example.
Example 1 First, p-type fine silicon particles 1 with a particle diameter ranging from 100 to 10 nm were prepared and dried thoroughly. Next, as a chemical absorption agent, an agent containing a reactive functional group (e.g. epoxy group or imino group) at the functional site and an alkoxysilane compound at the other end, for example the agent shown in the following chemical formula [Formula 1] or [Formula 2], was measured to be 99 w/t % and as a silanol condensation catalyst, for example, dibutyltin diacetylacetonate or acetic acid (a type of organic acid) was measured to be 1 w/t %, respectively. These were dissolved into a solvent that was a mixture of the same quantity of silicone and dimethylformamide (e.g. a liquid solution with 50% of hexamethyldisiloxane and 50% of dimethylformamide) to prepare a chemical absorption liquid so that it had a concentration of about 1 w/t % (preferably the concentration of the chemical absorption agent is about 0.5 to 3%). [Formula 1]
O OCH3
CH2-CHCH2O(CH2)SSi -OCH3
OCH3
[Formula 2]
OCH3
H2N(CH2J3Si — OCH3 OCH3 The p-type fine silicon particles 1 were mixed and stirred in this absorption liquid and reacted in a normal atmosphere (45% relative humidity) for about two hours. In this case, since the surface of the p-type fine silicon particle bound with a lot of hydroxyl groups 2 at the dangling bonds (shown in FIG. 1A), a chemical absorption monomolecular film 3 containing epoxy groups or a chemical absorption monomolecular film 4 containing amino groups, which forms a chemical bond with the surface of the fine silicon particle throughout the surface was formed at a thickness of about 1 nm, because of the bonding formation shown in the following chemical formula [Formula 3] or [Formula 4] by a dealcoholization reaction (in this case, de-CH3OH) between Si(OCH3) group of the foregoing chemical absorption agent and the foregoing hydroxyl groups under the presence of the silanol condensation catalyst or the organic acid (shown in FIG.S 1 B and 1C).
When using an adsorption agent containing an amino group, it was better to use an organic acid, such as acetic acid, since the tintype catalyst produced a deposition. Although the amino group contains an imino group, substances such as pyrrole derivative and imidazole derivatives other than the amino group also contain the imino group. Furthermore, when a ketimine derivative was used, the amino group was easily introduced by hydrolysis after the coating formation.
Then, a chlorinated solvent, such as tricren, was added to the mixture and stirred for cleaning and thus p-type fine silicon particles 5 and 6 covered by a chemical absorption monomolecular film containing a reactive functional group (e.g. epoxy group or amino group) over the surface were manufactured. [Formula 3]
O O—
CH2-CHCH2O(CH2)SSi -O-
O— [Formula 4] o—
H2N(CH2J3Si -O- O—
Since the processed part had an extremely thin coating with a film thickness at the nanometer level, the particle diameter was not impaired. In addition, since this coating had a voltage of 0.1 V or less, it had almost no electrical insulating characteristics while maintaining the ability to prevent the oxidization process of silicon.
When it was removed from the atmosphere without cleaning, the reactivity was almost the same; however, the solvent evaporated and the chemical absorption agent left behind on the particle surface reacted at the particle surface with the moisture in the atmosphere, then a fine silicon particle was obtained on which an extremely thin polymer coating was formed from the chemical absorption agent at the particle surface.
Since this method has a feature of not requiring a dry atmosphere, it offers excellent potential for mass production. Then the same amount of p-type fine silicon particles 5 and 6 covered by the chemical absorption monomolecular film with the foregoing epoxy group or amino group were sampled and mixed well in isopropyl alcohol to form a paste. When the paste was applied to a glass substrate and heated at 50 to 100 degrees Celsius, the epoxy group and amino group were added to each other by the reaction shown in the following chemical formula [Formula 5] to bind and solidify the fine silicon particles, forming a coating film of the p-type fine silicon particles without binders. [Formula 5]
O
/ \ -(CH2)CH-CH2 + H2NCH2 —
► - (CH2)CHCH2-NHCH2 -
OH Although the above Example 1 used the substance shown in [Formula 1] or [Formula 2] as a chemical absorption agent containing a reactive group, the following substances (1) to (16) other than those described above could also be used.
(I) (CH2OCH)CH2θ(CH2)7Si(OCH3)3 (2) (CH2OCH)CH2O(CH2)IiSi(OCHs)3
(3) (CH2CHOCH(CH2)2)CH(CH2)2Si(OCH3)3
(4) (CH2CHOCH(CH2)2)CH(CH2)4Si(OCH3)3
(5) (CH2CHOCH(CH2)2)CH(CH2)6Si(OCH3)3
(6) (CH2OCH)CH2O (CH2J7Si(OC2Hs)3 (7) (CH2OCH)CH2O (CH2)IiSi(OC2Hs)3
(8) (CH2CHOCH(CH2)2)CH(CH2)2Si(OC2H5)3
(9) (CH2CHOCH(CH2)2)CH(CH2)4Si(OC2H5)3
(10) (CH2CHOCH(CH2)2)CH(CH2)6Si(OC2H5)3
(II) H2N(CH2)5Si(OCH3)3 (12) H2N(CHs)7Si(OCHs)3
(13) H2N(CHz)9Si(OCH3)S
(14) H2N(CH2)5Si(OC2H5)3
(15) H2N(CHz)7Si(OC2Hg)3
(16) H2N(CHz)9Si(OC2Hs)3 Hereinabove, the (CH2OCH) group represents a functional group shown in the following formula [Formula 6], and the (CH2CHOCH(CH2)2)CH group represents a functional group shown in the following formula [Formula 7]. [Formula 6]
O CH2-CH -
[Formula 7] CH-CH2
CH CH -
\ /
CH2 -CH2
In addition, the following substances (17) to (22) could also be used as a chemical absorption agent containing the energy beam reactive functional group for a light or electron beam. In this case, an energy beam such as light, electron beams, or the like shall be irradiated for hardening.
(17) CH≡C-C≡C-(CH2)i5SiCI3
(18) CH=C-C=C-(CH2)2Si(CH3)2(CH2)i5SiCl3
(19) CHEC-C=C-(CH2)2Si(CH3)2(CH2)9SiCl3
(20) (C6H5)(CH)2CO(C6H4)O(CH2)6OSi(OCH3)3 (21) (C6H5)(CH)2CO(C6H4)O(CH2)6OSi(OC2H5)3
(22) (C6H5)CO(CH)2(C6H4)O(CH2)6OSi(OCH3)3
Where (06H5)CO(CH)2(C6H4)- represents chalcone group.
In Example 1 , for the silanol condensation catalyst, groups of carboxylic acid metal salt, carboxylic acid ester metal salt, carboxylic acid metal salt polymer, carboxylic acid metal salt chelate, titanic acid ester, and titanic acid ester chelate are available. More specifically, stannous acetic acid, dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin dilaurate, dioctyltin dioctate, dioctyltin diacetate, stannous dioctanoic acid, lead naphthenate, cobalt naphthenate, iron 2-ethylhexanoate, dioctyltin bis-octylthioglycolate ester, dioctyltin maleate ester, dibutyltin maleate polymer, dimethyltin mercaptopropionate polymer, dibutyltin bis-acetylacetate, dioctyltin bis-acetyl laurate, tetrabutyltitanate, tetranonyltitanate, and bis(acetylacetonyl) dipropyl titanate could be used.
For the film forming liquid, an anhydrous organochlorine solvent, hydrocarbon solvent, fluorocarbon solvent, silicon solvent, or a mixture of these were available as a solvent when using an alkoxysilane type or a chlorosilane type chemical absorption agent. If increasing the particle concentration by evaporating the solvent without cleaning, the boiling point of the solvent is preferably between 50 and 250 degrees Celsius.
More precisely, an organochlorine solvent, nonaqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, n-paraffin, decalin, industrial gasoline, nonan, decane, kerosene, dimethyl silicon, phenyl silicon, alkyl modified silicon, polyether silicon, and dimethylformamide can be used. In addition, if the adsorption agent is an alkoxysilane type and the organic coating is formed by evaporating the solvent, an alcohol solvent, such as methanol, ethanol, propanol, or a mixture of these, was able to be used in addition to the above listed solvents.
In addition, the fluorocarbon solvent can be a chlorofluorocarbon solvent, Fluorinert (a product manufactured by 3M Company), and Aflude (a product manufactured by Asahi Glass Co., Ltd.). These may be used solely, or two or more kinds may be mixed if the combination blends well. In addition, an organochlorine solvent such as chloroform may be added.
On the other hand, when a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound was used instead of the silanol condensation catalyst, the processing time was reduced to about 1/2 to 2/3 at the same concentration.
Moreover, when the silanol condensation catalyst was mixed with a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound (although the ratio can vary from 1:9 to 9:1, it is normally preferable to be around 1:1), the processing time was several times faster (to about half an hour), so that the time of film formation was reduced to a fraction. For example, when a dibutyltin oxide, which is a silanol catalyst, was replaced with H3 (from Japan Epoxy Resins Co., Ltd.), a ketimine compound, and the other conditions remained the same, we obtained almost the same results except that the reaction time was reduced to about one hour.
Moreover, when the silanol catalyst was replaced with a mixture of H3 (from Japan Epoxy Resins Co., Ltd.), a ketimine compound, and dibutyltin bis-acetylacetonate, a silanol catalyst (mixing ratio of 1 :1), and the other conditions remained the same, we obtained almost the same results except that the reaction time was reduced to about half an hour.
Therefore, the above results clearly indicated that the ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and aminoalkylalkoxysilane compound are more active than the silanol condensation catalyst.
Moreover, the activity was further enhanced when the silanol condensation catalyst was mixed with one selected from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and aminoalkylalkoxysilane compound. The available ketimine compounds are not particularly limited, and include the following examples: 2,5,8-triaza-1 ,8-nonadien;
3,11 -dimethyl-4,7, 10-triaza-3, 10-tridecadien; 2, 10-dimethyl-3,6,9-triaza-2,9-undecadien; 2,4,12,14-tetramethyl-5,8,11-triaza-4,11-pentadecadien; 2,4, 15, 17-tetramethy 1-5,8, 11,14-tetraaza-4, 14-octadecadien; 2,4,20,22-tetramethyl-5, 12,19-triaza-4,19-trieicosadien; etc.
There are also no particular limitations to the organic acids available; however, for example, formic acid, acetic acid, propionic acid, butyric acid, and malonic acid showed almost the same effect.
Example 2
The same method as Example 1 was used to form a chemical absorption monomolecular film with an epoxy group or amino group on n-type fine silicon particles 11, and the same amount of the n-type fine silicon particles covered by epoxy group 12 and the n-type fine silicon particles covered by amino group 13 were sampled and mixed well in isopropyl alcohol to form a paste.
Then, the paste was applied to an ITO transparent electrode 15, which was preformed on the surface of a glass substrate 14, and heated at 50 to 100 degrees Celsius for hardening to form a coating film 16 of n-type fine silicon particles with a film thickness of about 1 micron.
Later, the same amount of the p-type fine silicon particles 5 and 6 obtained in Example 1 , which were covered by a chemical absorption monomolecular film containing an epoxy group or amino group, were sampled and mixed well in isopropyl alcohol to form a paste. The paste was applied to the surface of the coating film 16 of the foregoing n-type fine silicon particles and heated at 50 to 100 degrees Celsius to form a coating film 17 of the p-type fine silicon particles with a film thickness of about 1 micron. Finally, an Al film 18 was formed as a back surface electrode by evaporation to create a solar cell that receives light 19 irradiated from the side of the glass substrate.
In so doing, if a monomolecular film 20 containing an epoxy group or amino group is also preformed on the surface of the ITO transparent electrode 15 in a similar way, the monomolecular film on the surface of the fine silicon particles also reacts with the monomolecular film on the surface of the ITO transparent electrode
15 to produce a silicon solar cell with a high resistance to exfoliation. (FIG. 2)
Here, the reactive monomolecular films on the surface of the p-type and n-type fine silicon particles serve to form a hardened film of fine silicon particles and to protect against the oxidation of p-type and n-type fine silicon particles in the atmosphere. Since this reactive monomolecular film has a thickness of about 1 nm, it does not interfere with the conductivity of the silicon.
In addition, by controlling the particle diameter of the fine silicon particle between 100 nm to 1 nm, the range of the absorption wavelength was controlled from the infrared light region to the visible light region.
In the above two examples, fine silicon particles were used for the explanation. However, any semiconductive fine particles that contain active hydrogen, such as hydrogen of the hydroxyl group, on the surface are available as semi-conductive fine particles for the present invention.

Claims

1. A fine silicon particle covered by an organic thin film that is covalently bound to the surface.
2. The fine silicon particle as claimed in Claim 1 , wherein the organic thin film covalently bound to the surface comprises molecules that include a functional group at one end and covalently binds to the surface of the fine silicon particle via Si at the other end.
3. The fine silicon particle as claimed in Claim 2, wherein the functional group is a reactive functional group.
4. The fine silicon particle as claimed in Claim 3, wherein the reactive functional group is a functional group with either thermal reactivity or light reactivity, or otherwise radical reactivity or ionic reactivity.
5. The fine silicon particle as claimed in Claim 3, wherein the reactive functional group is either an epoxy group or imino group, or otherwise a chalcone group.
6. The fine silicon particle as claimed in Claims 1 or 2, wherein the organic thin film covalently bound to the surface comprises a monomolecular film.
7. A method for manufacturing a fine silicon particle comprising a process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid produced from a mixture of at least an alkoxysilane compound, a silanol condensation catalyst, and a nonaqueous organic solvent.
8. The method for manufacturing a fine silicon particle as claimed in Claim 7 comprising the process of having the surface of the fine silicon particle react with an alkoxysilane compound by dispersing the fine silicon particles among a chemical absorption liquid and then cleaning the surface of the fine silicon particle with an organic solvent to form a monomolecular film covalently bound to the surface of the fine silicon particle.
9. The method for manufacturing a fine silicon particle as claimed in Claim 7, wherein a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is used instead of the silanol condensation catalyst.
10. The method for manufacturing a fine silicon particle as claimed in Claim 7, wherein at least one promoter chosen from a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or an aminoalkylalkoxysilane compound is mixed with the silanol condensation catalyst.
11. A solar cell wherein a layer of n-type fine silicon particles covered by an organic thin film covalently bound to the surface and a layer of p-type fine silicon particles covered by an organic thin film covalently bound to the surface form a lamination layer.
12. A solar cell wherein n-type fine silicon particles covered by a first organic thin film covalently bound to the surface and n-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via said organic thin films to form a hardened film layer of the n-type fine silicon particles, and p-type fine silicon particles covered by a first organic thin film covalently bound to the surface and p-type fine silicon particles covered by a second organic thin film covalently bound to the surface are mixed together and covalently bound to each other via said organic thin films to form a hardened film layer of the p-type fine silicon particles; and then both fine particle layers form a lamination layer on a glass substrate.
13. The solar cells as claimed in Claims 11 or 12, wherein the organic thin film covalently bound to the surface comprises molecules that include a reactive functional group at one end and covalently bind to the surface of the semiconductive fine silicon particle via Si at the other end.
14. The solar cell as claimed in Claim 13, wherein the reactive functional group is a functional group with thermal reactivity or ionic reactivity.
15. The solar cell as claimed in Claim 13, wherein the reactive functional group is an epoxy group or imino group.
16. The solar cells as claimed in Claims 11 or 12, wherein the organic thin film covalently bound to the surface comprises a monomolecular film.
17. The solar cells as claimed in at least one of Claims 11 to 16, wherein the surface of the base material covered by an organic thin film covalently bound to the surface, the layer of n-type fine silicon particles covered by an organic thin film, and the layer of p-type fine silicon particles covered by an organic thin film are covalently bound with each other via said respective organic thin film to form a hardened film.
18. A method for manufacturing a solar cell comprising a process to form a paste by mixing into an organic solvent the n-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface and the n-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of a base material, a process of forming a paste by mixing into an organic solvent the p-type fine silicon particles covered by an organic film, including a first reactive functional group covalently bound to the surface, and the p-type fine silicon particles covered by an organic film, including a second reactive functional group covalently bound to the surface; a process of applying it to the surface of the base material; and a process of hardening.
19. The method for manufacturing a solar cell as claimed in Claim 18, wherein prior to the application of the paste to the base material, an organic thin film, which includes a functional group that reacts with the first or second reactive functional group on the surface of the fine silicon particle covered by an organic film, including the first reactive functional group or of the fine silicon particle covered by an organic film, including the second reactive functional group, is bound to the surface of the base material.
PCT/JP2007/063052 2007-06-22 2007-06-22 Fine silicon particle and method of manufacture and solar cell using the fine silicon particle and method of manufacture WO2009001471A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07126005A (en) * 1993-10-28 1995-05-16 Nippon Oil Co Ltd Production of silicon colloid
JP2006071330A (en) * 2004-08-31 2006-03-16 Tokyo Denki Univ Nanosilicon fluorescence element for detecting/visual sensing cancerous cells and its manufacturing method
JP2007117828A (en) * 2005-10-26 2007-05-17 Kagawa Univ Fine particle and its manufacturing method
JP2007118276A (en) * 2005-10-26 2007-05-17 Kagawa Univ Single-layer fine particle film, cumulated fine particle film and manufacturing method of them
JP2007173516A (en) * 2005-12-22 2007-07-05 Kagawa Univ Silicon fine particles, manufacturing method thereof, solar battery using the same and manufacturing method thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07126005A (en) * 1993-10-28 1995-05-16 Nippon Oil Co Ltd Production of silicon colloid
JP2006071330A (en) * 2004-08-31 2006-03-16 Tokyo Denki Univ Nanosilicon fluorescence element for detecting/visual sensing cancerous cells and its manufacturing method
JP2007117828A (en) * 2005-10-26 2007-05-17 Kagawa Univ Fine particle and its manufacturing method
JP2007118276A (en) * 2005-10-26 2007-05-17 Kagawa Univ Single-layer fine particle film, cumulated fine particle film and manufacturing method of them
JP2007173516A (en) * 2005-12-22 2007-07-05 Kagawa Univ Silicon fine particles, manufacturing method thereof, solar battery using the same and manufacturing method thereof

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