TiO2 films obtained by the sol–gel process and doped with Yb3+ and Er3+ ions

The upconversion mechanism based on lanthanide ions has been studied in several systems and has been applied in various fields, such as sensors, biological markers, and photovoltaic cells. This work investigates the properties of the lanthanides Er3+ and Yb3+ doped into titanium oxide at different molar concentrations. The sol–gel methodology and the spin-coating technique were used to prepare the thin films. To promote the upward energy...