Papers by Author: Hajime Horikawa

Abstract: Conductive SnO2 powder was synthesized by ultrasonic spray pyrolysis and was blended with TiO2 nano particles in order to improve the conductivity of TiO2 porous films used in dye-sensitized solar cells. However, the conductivity of the films decreased because of the exposure of SnO2 to high temperature during synthesis and calcination.

Abstract: Silica, silica/polymethylmethacrylate (PMMA) hybrid, and silica-particle blend silica films were successfully prepared on polybutylene terephtalate (PBT) substrate by dip coating using perhydropolysilazane (PHPS) as a silica source. The effect of thermal treatment on conversion from PHPS to silica was investigated in detail by scanning electron microscopy and Fourier transform infrared spectroscopy. Mechanical properties of silica and silica/PMMA hybrid thin films also were examined by the pencil scratch hardness tests.

Abstract: TiO2 powder was synthesized hydrothermally from titanium alkoxide ethanol solution in supercritical state and obtained anatase type crystalline powder sized ca. 20 nm. Dye-sensitized solar cells were fabricated with the powders and evaluated the power generation efficiencies.

Abstract: Titania nanocrystals were prepared by hydrolysis of titanium alkoxide in ethanol solution. The preparation of titania / alumina thin film was performed on ITO coated glass substrate by dip coating method using ethanol of titania nanocrystal and boemite sol. The crystal structures, microstructure and thickness of titania / alumina thin film were examined by XRD and SEM. The adsorption of dye was influenced by the surface structure of thin film. The adsorption of dye on the films was improved by the immersion into acid as HNO3. Ruthenium polypyridyl complex and triarylmethylium salt were used as dye. Electrode using titania / alumina thin film for dye-sensitized solar cell was constructed.

Abstract: Homogeneous BaTiO3 nano-sized powders were successfully prepared by spray pyrolysis using multiphase plasma under the air atmosphere. Particle size, morphology, crystal phase and crystallinity of as-prepared powders were characterized by SEM and XRD. The effect of starting precursor solution on the formation of nanoparticles was investigated. The use of Ba/Ti aqueous solution derived from malic acid led to formation of cubic BaTiO3 nanoparticles with 50 nm size.