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Improvement of photovoltaic performance for dye sensitized solar cells (DSC) is discussed in terms of electron-path and ion-path. In order to make electron path, we focused on passivation of TiO2 surface states which are observed by thermally stimulated current (TSC). The TiO2 surface was well-passivated with dye molecules under pressurized CO2 atmosphere. It was found that DSC cells prepared by a CO2 process (Cell-CO2) had higher efficiency than those prepared by a conventional dipping process (Cell-DIP) and the higher efficiency was associated with low TiO2-surface state, high electron diffusion coefficient and long electron life time in TiO2 for the Cell-CO2. In addition, dye-staining under pressurized CO2 atmosphere had advantages over a conventional dipping process on rapid dye-uptake and less dye aggregation. In order to fabricate ion-path in solidified electrolyte, we focused on surface modification of nano-materials. Surface of nano-materials such as TiO2-nanoparticles and porous alumina films were modified with imidazolium iodide moieties consisting of long alkyl chains which render surface-molecules self-organized. Redox-species are concentrated on the self-organized molecules and make ion-path. We propose quasi-solid electrolyte system consisting of two layers having different charge carrier concentration to keep high photoconversion efficiencies even after solidification.

Hydrogenation properties of some amorphous Zr-Ni-Ti-V based alloys were investigated. Pressure-composition(P-C) isotherms and hydrogen storage capacities at room temperatures were measured and effects of elemental substitution of the components with Pd or Mn were studied. The alloy electrodes were prepared by using amorphous (Zr-Ni-Ti-V)-(Pd,Mn) alloys prepared by the melt spinning method. The amorphous alloys in the electrode kept their amorphous structures during cycles of charge and discharge. The electrochemical hydrogen storage capacities were strongly affected by the substitution amounts of Pd or Mn. Even a small amount of substitution, changed the equilibrium dissociation pressures of the alloy. In the present study, the rechargeable capacity was optimized up to H/M=0.5 for the alloy electrode with the composition of (Zr45Ni30Ti25)-3at%Pd. The slope in the P-C isotherm suggested that the maximum H/M of the alloy would exceed 1.0 at higher hydrogen pressure than 1.0 MPa, however, the wide distribution of hydrogen site energy in the amorphous hydride resulted in extremely large slope in P-C isotherms, and consequently restricted the rechargeable capacities of the electrodes.