All-plastic dye-sensitized solar cells (DSSCs) using TiO2 paste (SP-210), indium tin oxide-coated polyethylene naphthalate (PEN/ITO) film and a Pt-coated PEN/ITO film counter electrode, were fabricated with 1.0wt% κ-carrageenan solid electrolyte containing the redox electrolytes ( I - / I 3 - ) solution. The cell performance of the all-plastic cell using 1.0wt% κ-carrageenan solid electrolyte was investigated in comparison with liquid type one, showing that the values of V oc (open circuit voltage) and ff (fill factor) were the same, but J sc (short circuit current) and η (conversion efficiency) were slightly larger for the liquid type electrolyte cell than the solid type one. A higher conversion efficiency was exhibited by UV-irradiation before heat treatment of the PEN/ITO/TiO2(SP-210) film than that after heat treatment. The effect of heat treatment conditions was investigated according to a modified hydrothermal treatment of the PEN/ITO/TiO2(SP-210) film, showing that the ff values become high (>0.7) by hydrothermal treatment. The electrochemical impedance spectroscopy (EIS) has shown the important comparison of each charge transport processes between the all-plastic and the conventional cells.