An evaluation of fluorinated titanium oxide nanocrystals with UV exposure treatment for oxygen vacancy control

The oxygen vacancy properties of densified titanium oxide (TiO₂) nanocrystals (NCs) with different surface ligand states were evaluated. Fluorous ligand modification resulting in the high densification of NCs and the effect of residual ligands on the surface of the NCs using ultraviolet (UV)-exposure treatment were investigated. After synthesizing the TiO₂ NCs at 80 °C, their modification proceeded using 2,2,2-trifluoroacetic acid as the fluorous ligand. NC thin films were formed using spin-casting, after which the UV-exposure treatment was performed. According to the analytical results of crystalline size, surface, optical properties, and surface ligand states of the TiO₂ NCs, the ligands on the NCs were decomposed by the UV-exposure treatment under various atmospheres and the flatness of the NC thin films was found to be controlled by the fluorous ligand modification. Thus, the recombination effect of the oxygen vacancies could be controlled by the fluorous ligand modification and UV-exposure treatment.