Plasmon-enhanced upconversion luminescence in pyrochlore phase Yb x Er 2-x Ti 2 O 7 thin film.

Pyrochlore phase YbxEr2-xTi2O7 (YETO) thin films have been prepared by employing a facile sol-gel method combining with spin-coating technique and post-annealing treatment at 700 degrees C. High concentration of Yb3+ ions can promote the transformation from Yb3+/Er3+ co-doped anatase phase TiO2 to pyrochlore phase YETO at 700 degrees C temperature. We find that the YETO thin film with 30 mol% Yb3+ ions exhibits the brightest upconversion (UC) emission. Moreover, the introduction of Au nanorods (Au NRs) in the YETO thin film can further enhance the UC fluorescence. By adjusting the density of Au NRs, the UC emission intensity is increased by about 2.8-fold due to the excitation field enhancement caused by the localized surface plasmon resonance effect.