Electrical properties of dye-sensitized solar cells prepared by the binder-free TiO2 pastes

Titania (TiO2) powder, which is material for photoelectrode in dye-sensitized solar cells (DSSCs), was fabricated by hydrothermal synthesis process at 230 degrees C for 12 hours. The crystal structures of all the synthesized nano-structured TiO2 films exhibited anatase phase. Binder-free pastes were prepared with the change of the amount of ammonia water from 2 μl to 640 μl in order to obtain the printable viscosity. It has been known that weak inter-particle bonds in slurry of flocculated particles make the slurry more viscous than slurry of dispersed particles. The increase of the amount of ammonia water for binder-free TiO2 pastes is attributed to the improvement of the viscosity of TiO2 paste and the power conversion efficiency of DSSCs using it. The viscosity of TiO2 pastes prepared at the ammonia water of 418 μl exhibited the highest value about 109,000 cP and also, was very transparent over 84%. As a result, the power conversion efficiency of DSSC prepared with the ammonia water of 418 μl was about 3%.