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1999 Fiscal Year Final Research Report Summary

Development of a New Method to Prepare Polycrystalline Silicon Thin Films for High-Efficiency and Low-Cost Solar Cells

Research Project

Project/Area Number 09480102
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field エネルギー学一般・原子力学
Research InstitutionOsaka University

Principal Investigator

NAKATO Yoshihiro  Graduate School of Engineering Science, Osaka University, Professor, 大学院・基礎工学研究科, 教授 (70029502)

Co-Investigator(Kenkyū-buntansha) YAE Shinji  Graduate School of Engineering Science, Osaka University, Research Associate (1997.4〜1998.3), 大学院・基礎工学研究科, 助手 (00239716)
Project Period (FY) 1997 – 1999
KeywordsSolar cell / Polycrysalline silicon / Molten salt / Electroreduction / Junction / Surface state / Termination bond / Nano-fabrication
Research Abstract

The research has been made with the aim at developing a new electrochemical method to prepare polycrystalline silicon (Si) thin films for high-efficiency and low-cost solar cells of a new type. In the new method, cheap silicon tetrachloride (SiClィイD24ィエD2), as the silicon source, was electrochemically reduced at the cathode (conductive substrate), with a molten salt used as the electrolyte. Much effort has been made to solve the problems of a very low solubility of SiClィイD24ィエD2 in the molten salt and of resulting inhomogeneous deposition of polycrystalline Si thin films. A mixed salt of aluminum trichloride and n-butylpyridinium chloride dissolved SiClィイD24ィエD2 in high concentrations, but its use was limited only below 100℃, resulting in the deposition of amorphous Si films. It was finally found that the use of a rotating cathode, only a half of it being immersed in the electrolyte, together with an eutectic melt of lithium chloride and potassium chloride as the electrolyte, gave a fairly homogeneous polycrystalline Si films. In parallel to these studies, basic studies have been made on the fabrication of a new junction appropriate for the use of polycrystalline Si films. It was found that Si-H termination bond could be converted to Si-X (X=halogen) bonds by immersin in concentrated hydrogen halide solutions containing a small amount of an oxidant, which led to shifts in the Si band edges. Interestingly, immersion of atomically flat n-Si (111) surfaces in a hydrogen iodide solution led to formation of ordered iodine nano-rods. Similar nano-rods of nickel were also formed when it was electrochemically deposited. Solid-state solar cells of a new type, "n-Si/p-CuI/ITO", gave a high open-circuit photovoltage (Voc) of 0.617 V, close to a theoretical value.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Y. Nakato: "Efficient Solar-to-Chemical Conversion by One Chip of n-Type Silicon with Surface Asymmetry"Electrochem. Solid-State Lett.. 1. 71-73 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] H. Kobayashi: "Oxide Thickness Dependence of Energy Shifts in the Si 2p Levels for the SiO_2/Si Structure, and its Elimination by a Palladium Overlayer"Appl. Phys. Lett.. 73. 933-935 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K. Morisawa: "Electrochemical Metal Deposition on Atomically Nearly-Flat Silicon Surfaces Accompanied by Nano-Hole Formation"Electrochem. Acta. 44. 3725-3729 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M. Ishida: "Structural Control of Semiconductor Surfaces on Atomic and Nanometer Scales for Efficient Solar Energy Conversion"Z. Phy Chem.. 212. 99-106 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K. Murakoshi: "Anisotropic Agglomeration of Surface-Modified Gold Nanoparticles in Solution and on Solid Surfaces"Jpn. J. Appl. Phys.. (in press).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A. Imanishi: "Formation of Ordered Rod-like Clusters of Iodine on H-Terminated Si(111) Surfaces During Immersion in Concentrated HI Solutions"Jpn. J. Appl. Phys.. (in press).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y. Nakato: "Efficient Solar-to-Chemical Conversion by One Chip of n-Type Silicon with Surface Asymmetry"Electrochemical and Solid-State Letters. Vol.1, No.2. 71-73 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] H. Kobayashi: "Oxide Thickness Dependence of energy Shifts in the Si 2p Levels for the SiOィイD22ィエD2/Si Structure, and its Elimination by a Palladium Overlayer"Appl. Phys. Lett.. Vol.73, No.7. 933-935 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Morisawa: "Electrochemical Metal Deposition on Atomically Nearly-flat Silicon Surfaces Accompanied by Nano-hole Formation"Electrochimica Acta. Vol.44. 3725-3729 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Ishida: "Structural Control of Semiconductor Surfaces on Atomic and Nanometer Scales for Efficient Solar Energy Conversion"Z. Phys. Chem.. Vol.212. 99-106 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Murakoshi: "Anisotropic Agglomeration of surface-Modified Gold Nanoparticles in Solution and on Solid Surfaces"Jpn. J. Appl. Phys.. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Imanishi: "Formation of Ordered Rod-like Clusters of Iodine on H-Terminated Si (111) Surfaces During Immersion in Concentrated HI Solutions"Jpn. J. Appl. Phys.. (in press).

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2001-10-23  

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