Efficient oxide phosphors for light upconversion; green emission from Yb3+ and Ho3+ co-doped Ln2BaZnO5 (Ln = Y, Gd)

Abstract

The optical properties of Yb³⁺ and Ho³⁺ co-doped Y₂BaZnO₅, synthesized by solid-state reactions, are investigated in detail. Under 977 nm excitation (∼25 × 10⁻³ W mm⁻²), bright green upconversion emission is observed. Concentration dependence studies at room temperature show that relatively high infrared to visible upconversion efficiencies are obtained with values up to ∼2.6%. The results of power dependence studies and temperature-dependent lifetime measurements allow us to determine the dominant upconversion mechanisms in Yb³⁺:Ho³⁺ co-doped Y₂BaZnO₅oxides. The materials presented in this article constitute new and efficient upconversion phosphors which may find utility in a variety of applications.