Fast one-step method to synthesize TiO ₂ nanoparticle clusters for dye sensitized solar cells

We have successfully designed a rapid method for producing dye sensitized solar cells (DSSC) using TiO ₂ films prepared by a modified dielectric barrier discharge jet (m-DBD jet) method which uses a DBD jet with elevated substrate temperatures from room temperature (RT) to 500°C for ∼10 min. This facile process has several advantages over other methods such as (1) eliminating additional coating and annealing steps, (2) creating films with high speed electron mobility via hierarchical pore clusters, and (3) allowing controlled TiO ₂ bandgap by N doping using atmospheric nitrogen instead of supplying N2 gas. Depending on reaction conditions, the resulting nanostructured materials have various sizes and shapes, with those deposited at the highest substrate temperatures displaying hierarchical walnut-shaped morphology as revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A possible growth mechanism of TiO ₂ nanoparticle clusters (TNC) is presented and discussed. Finally, this m-DBD jet method produces TNC films that exhibit ∼4 times higher photo-conversion efficiency than the nanoparticle films by the unmodified DBD jet method.