Upconversion luminescence properties in Er3+/Yb3+ codoped TiO2 films prepared by magnetron sputtering

The Er3+ /Yb3+ codoped TiO2 films prepared by magnetron sputtering can emit the green light at 490 nm and the red light at 670 nm by using a 980 nm diode laser irradiation. The emission intensity of upconversion is influenced by Er-x Yb2-x Ti2O7 crystal and concentration of Er3+ /Yb3+. The experiment shows that an appropriate codoping proportion of Er3+ /Yb3+ brings a notable enhancement of upconversion luminescence intensity. Er3+ plays a main role in the upconversion luminescence, and the sensitized ion Yb3+ can greatly improve the efficiency of upconversion. The TiO2 film prepared by magnetron sputtering has a small density of phonon states, thus it inhibits the process of non-radiative transitions, which leads to the formation of green light at 490 nm and the intensity of red light being greater than green light.