Electronics and Materials Science Course,
Department of Engineering, Graduate School of
Integrated Science and Technology,
Shizuoka University, Japan

Dr. Masayuki OKUYA
Associate Professor

A glass is a typical insulator, but it is easily turned to be a clear conductor by coating the glass with a transparent conductive oxide (TCO) film. TCO film is an essential material in opt electronic devices, such as a ceramic heater, anti-static shield glass, touch panel, and liquid-crystal monitor, and the industrial film formation technique should be developed to meet these demands.
Our research group developed a spray pyrolysis deposition (SPD) technique to prepare TCO film by a joint research project with MAKE Co. Ltd., and SPD Laboratory Co. Ltd., in Hamamatsu, Japan. SPD is the same film processing technique as so-called pyrosol technique, in which a source solution is sprayed on the heated substrate to be pyrolized and deposited as a film. High-frequency plasma and electromagnetic wave have also been employed as a new energy source for a novel film formation technique. These film formation techniques are applied to fabricate opt electronic devices, such as dye-sensitized solar cell and UV sensor, as well as TCO films.
Research topics
  • TCO film on a large (30cm×30cm) substrate
    The substrate from the size of 2cm×2cm to 30cm×30cm is acceptable to deposit TCO film by SPD technique. FTO film with high transmittance, >80% in the visible region, and low electrical resistivity, 1×10−4 Ω⋅cm, is prepared in air within 10 minutes in a laboratory scale.

  • Novel TCO film
    Novel TCO films, such as TNO, IZO and AZO, along with the conventional ones, ITO and FTO, are prepared and applied to opt electric devices mentioned below.

  • Dye-sensitized solar cell
    The optical and electrical properties of TCO films are optimized and applied to dye-sensitized solar cells to achieve high light-to-electron conversion efficiency. Porous TiO2 layer is deposited on the TCO film by SPD technique to prepare a working electrode for a dye-sensitized solar cell.

  • Magnetic and dielectric material for devices
    TCO is not the only material that is prepared by SPD technique. The technique is also applicable to deposit ferrite and barium titanate films.

  • Optical sensor
    UV sensor with p-i-n junction by stacking metal oxide layers is fabricated by SPD technique. The sensitivity is easily tuned by controlling the surface morphology and/or the carrier density of i-layer.

  • High-frequency plasma and electromagnetic wave
    The interaction between precursors and plasma or electromagnetic wave induces a new chemical reaction to prepare TCO film. Additionally, plasma induced by a surface discharge can supply a high energy to the selective area on the substrate, which is a convenient tool for a direct patterning in a film formation.
Apparatus of spray pyrolysis deposition (SPD) technique. A large substrate up to 30 × 30 cm in size is acceptable in this system. A compact SPD film formation system for a laboratory scale was also developed.
Demonstration of a dye-sensitized solar cell in Techno-Festa in Hamamatsu. An electric motor is working by a single cell under the quasi-sunlight irradiation.
Surface discharge on the selec-tive area for a direct patterning in film formation; (top) Plane, (left) Star, and (right) Symbol of Shizuoka University; Suruga Bay with Mt. Fuji, where was selected as a World Heritage site in UNESCO, 2013.