An investigation was made into the relaxation process of photo-excited carriers in anatase thin films, in which the concentration of the O vacancy was controlled by annealing at various temperatures in an O atmosphere. The influence of O vacancies on absorption spectra, photoluminescence spectra, and photoluminescence decay dynamics were considered.

Influence of Oxygen Vacancies on Optical Properties of Anatase TiO2 Thin Films. Iijima, K., Goto, M., Enomoto, S., Kunugita, H., Ema, K., Tsukamoto, M., Ichikawa, N., Sakama, H.: Journal of Luminescence, 2008, 128[5-6], 911-3