Quenching process effects on the performance of a TiO2 photoelectrode for dye-sensitized solar cells

A rapid cooling (quenching) step has been introduced in fabrication of TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The quenching process, studied at a fixed sintering temperature, decreased particle size but increased surface roughness without any substantial change in the crystal structure or oxidation state of TiO2 films. Therefore, the change in the DSSC performance induced by the quenching was related closely to the microstructural and morphological changes in the TiO2 films. Smaller particle size and the rough surface of TiO2 films facilitated dye adsorption and increased the number of active reaction sites. In particular, the enlarged number of active reaction sites produced by the quenching process promoted the charge transfer reaction at the TiO2-dye-electrolyte interface, resulting in overall performance improvement of DSSCs. The conversion efficiency of the furnace cooled- and quenched-TiO2 films at 500 degrees C were 4.588% and 5.797%, respectively.