A general approach for selective enhancement of green upconversion emissions in Er3+ doped oxides by Yb3+-MoO4 2- dimer sensitizing

In this paper, we report a general approach to enhance the upconversion (UC) luminescence of Er3+ doped oxides phosphors by Yb3+-MoO4 (2-) dimer sensitizing, which induced strong green UC emissions under the 976 nm laser diode excitation. By codoping of Yb3+ and Mo6+ in the Er3+ doped TiO2 and ZnO, the green UC emissions intensity can be selectively increased about 10 and 500 times than those of Er3+-Yb3+ codoped TiO2 and ZnO, respectively. The high excited state energy transfer between |F-2(7/2), T-3(2)> state of Yb3+-MoO4 (2-) dimer and F-4(7/2) level of Er3+ significantly avoids the nonradiative decay processes happened at lower energy levels of Er3+, and then increases the green UC emissions efficiently. The proposed Yb3+-MoO4 (2-) dimer sensitizing has been realized as an efficient way to enhance the green UC emissions in other Er3+ doped oxides phosphors. It is expected that the selective enhanced green UC emissions sensitized by Yb3+-MoO4 (2-) dimer in Er3+ doped oxides phosphors can greatly extend their scope of applications.