Takehito Mitate

Publications (2)3.84 Total impact

• Article: Modeling of an equivalent circuit for dye-sensitized solar cells

  Liyuan Han, Naoki Koide, Yasuo Chiba, Takehito Mitate
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  ABSTRACT: Internal resistance in a dye-sensitized solar cell (DSC) was investigated using electrochemical impedance spectroscopy measurements. Four resistance elements were observed in the impedance spectra, and their dependencies on the applied bias voltage were characterized. It is found that the resistance element related to charge transport at the TiO ₂/ dye/electrolyte interface displays behavior like that of a diode, and the series resistance elements largely correspond to the sum of the other resistance elements. An equivalent circuit for DSCs is proposed based on these results. © 2004 American Institute of Physics.
  Applied Physics Letters 04/2004; · 3.84 Impact Factor
• Article: Highly efficient quasi-solid state dye-sensitized solar cell with ion conducting polymer electrolyte

  Ryoichi Komiya, Liyuan Han, Ryohsuke Yamanaka, Ashraful Islam, Takehito Mitate
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  ABSTRACT: Quasi-solid state dye-sensitized solar cells were fabricated using an oligomer having three polymerizable reactive groups. Only 7% polymer concentration in the polymer electrolyte is found enough to form a stable quasi-solid structure and a three-dimensional polymer network structure is proposed. Conductivity measurement of the polymer electrolyte in different organic solvents shows that the ionic conductivity increases with decreasing the viscosity of the solvent and a high ionic conductivity of 9 mS/cm is observed for the polymer electrolyte composition of 0.2 M DMPII, 0.5 M LiI, 0.05 M I2 in the mixed solvent of ethylene carbonate and γ-butyrolactone (30:70 v/v). A short circuit photocurrent density of 14.8 mA/cm2, an open circuit voltage of 0.78 V, a fill factor of 0.70 and an overall conversion efficiency of 8.1% under AM1.5 irradiation (100 mW/cm2) was observed when fabricated a quasi-solid state dye-sensitized solar cells using these high conducting polymer electrolyte. The quasi-solid cells with the polymer electrolyte show higher open circuit voltage than that of the liquid cells that may be due to the suppression of the back electron transfer between the conduction band of the TiO2 electrode and the triiodide ion in the electrolyte.
  Journal of Photochemistry and Photobiology A: Chemistry.