All Solid-state Dye-sensitized TiO₂ Photo Electrochemical Cell and Its Long-term Stability

Abstract

An all solid-state dye-sensitized TiO₂ photo electrochemical cell was fabricated with solid polymer electrolyte. Oligoethylene glycol methacrylate (MEO) and lithium iodide were used as a solid polymer electrolyte. Ethylene glycol (E. G. ) or propylene carbonate (P. C. ) was added to the polymer to enhance the performance. In order to make a tight contact with the TiO₂ porous film, the solid polymer electrolyte was polymerized after immersing the porous film in the monomer solution. The electrical conductivity of polymer solid electrolytes was found to be over 1 mS cm^-1.
The short circuit current of the cell which contained P. C. w as two times higher than the one containing E. G. The cell in which MEO was polymerized by thermal radical polymerization exhibited better currentvoltage characteristics than that produced by photo induced radical polymerization.
For the cell prepared by thermal radical polymerization with P. C., the op en circuit voltage, short circuit current, fill factor, and energy conversion efficiency were 0.63 V, 2.54 mA/cm², 0.69, and 1.72%, respectively under photo irradiation of 1000 W/m².
A continuous photo irradiation test was carr ied out with a UV- and IR-filterd 150 W hologen lamp for over 8000 h. Though in the initial 2000 h the short circuit current decreased to 70%, no further decrease was observed by the elongated irradiation, proving the stability of the sensitizing dye. No leakage of the electrolyte was observed during this test. The long-term durability of the cell was enhanced dramatically.