Solution processed thin films of non-aggregated TiO2 nanoparticles prepared by mild solvothermal treatment

In this report, non-aggregated anatase TiO2 nanoparticles were synthesized by mild solvothermal process in 1-butanol. By varying solvothermal reaction temperature and time, TiO2 particle size was controlled from 5.3 to 9.0 nm, while maintaining pure anatase phase and optical clearance in the concentrated dispersion (5 wt%). Spin coating of TiO2 dispersions resulted in transparent thin films with thickness controllability, and it was confirmed that the mild solvothermal reaction significantly increased the refractive index of the thin films without post-thermal treatment. In addition to the fabrication of low-temperature processed thin films, the inverse opal TiO2 films were also fabricated by the colloidal templating method followed by thermal calcination to reveal the improved volume shrinkage of the mesoporous TiO2 films.