ALL-SOLID-STATE DYE-SENSITIZED TIO2 PHOTO ELECTROCHEMICAL-CELL AND ITS LONG-TERM STABILITY

An all solid-state dye-sensitized TiO2 photo electrochemical cell was fabricated with solid polymer electrolyte, Oligoethylene glycol methac rylate (MEG) and lithium iodide were used as a solid polymer electroly te. Ethylene glycol (E.G.) or propylene carbonate (P.C.) was added to the polymer to enhance the performance. In order to make a tight conta ct with the TiO2 porous film, the solid polymer electrolyte was polyme rized after immersing the porous film in the monomer solution. The ele ctrical conductivity of polymer solid electrolytes was found to be ove r 1 mS cm(-1) . The short circuit current of the cell which contained P.C. was two times higher than the one containing E.G. The cell in whi ch MEO was polymerized by thermal radical polymerization exhibited bet ter current-voltage characteristics than that produced by photo induce d radical polymerization. For the cell prepared by thermal radical pol ymerization with P.C., the open circuit voltage, short circuit current , fill factor, and energy conversion efficiency were 0.63 V, 2.54 mA/c m(2), 0.69, and 1.72%, respectively under photo irradiation of 1000 W/ m(2). A continuous photo irradiation test was carried out with a UV- a nd IR-filtered 150 W hologen ramp for over 8000 h. Though in the initi al 2000 h the short circuit current decreased to 70%, no further decre ase was observed by the elongated irradiation, proving the stability o f the sensitizing dye. No leakage of the electrolyte was observed duri ng this test. The long-term durability of the cell was enhanced dramat ically.