Efficient two-color luminescence of Er3+/Yb3+/Li+:ZrO2 nanocrystals

We demonstrate the upconversion-photoluminescence spectra of Er3+, Yb3+ and Li+ ions doped ZrO2 nanocrystals. By introducing Li+, emission intensities of single green and single red band increase by a factor of 1.93 and 1.65, respectively. Powder X-ray diffraction data and decreased slopes of the excitation power dependences on upconverted emission intensities give evidences that Li+ ions can tailor the local structure of host lattice and improve energy transfer processes from Yb3+ to Er3+, respectively.

Research highlights
► Single green and red emissions are obtained in Er3+/Yb3+/Li+:ZrO2 nanocrystals.
► Upconversion intensities of green and red emissions increase by doping Li+.
► Effects of Li+ are discussed by rate equation model.