Ding Ren

Study in the porosity of the TiO 2 films prepared by magnetron sputtering deposition

Nano-crystalline TiO2 films with an anatase phase were deposited by reactive medium frequency magnetron sputtering deposition. Such TiO2 films as anode for the dye-sensitized solar cells should be with a suitable porosity, two methods were used. One is change the tilt angle, i.e., the angle between sputtering beam direction and normal of the substrate, during film deposition. Another is regulating the total pressure during film deposition. Cross-section morphologies of SEM observation and measurements in optical property of the TiO2 films were used to check the porosity of the deposited TiO2 films. The result shows that increasing the tilt angle and increasing the total pressure are both effective to increase the porosity of the TiO2 films. And the results from both checking analyses are very coincident.

Behaviors of the different dispersers on the morphology of the porous TiO 2 films

TiO<inf>2</inf> films with nano-particles dispersed by using three different additives such as acetylacetone, Emulsifier OP-10 and polyethylene glycol (PEG) respectively. It is found that the TiO<inf>2</inf> films produced at appropriate amount of Emulsifier OP-10 are no re-aggregation of TiO<inf>2</inf> nano-particles with pores of about 5–15 nm. By adding PEG, the pores of the TiO<inf>2</inf> films could be at about 50 nm to 200 nm. But, by using acetylacetone, aggregations of TiO<inf>2</inf> nano-particles always exist in the TiO<inf>2</inf> films. The related mechanism on the aggregation of nano-particles in the TiO<inf>2</inf> slurries is discussed.