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

Abstract

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 |²F_7/2, ³T₂> state of Yb³⁺–MoO₄ ²⁻ dimer and ⁴F_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.