Bright white upconversion luminescence from Er-Tm-Yb doped CaSnO3 powders

Bright white upconversion luminescence from Er³⁺-Tm³⁺-Yb³⁺ doped CaSnO₃ powders is obtained under the diode laser excitation of 980 nm. It is composed of three primary colors of red, green and blue emissions, which originate from the transitions of ⁴F_9/2 → ⁴I_15/2, (²H_11/2, ⁴S_3/2) → ⁴I_15/2 of Er³⁺ ions and ¹G₄ → ³H₆ of Tm³⁺ ions, respectively. The efficient upconversion emission is attributed to the energy transfer between Yb³⁺ and Er³⁺ or Tm³⁺ions. Moreover, it is observed that Tm³⁺ acts as the quenching center for the green upconversion luminescence from Er³⁺ ions, and the sensitizer for the red and blue luminescence when the Tm³⁺ doping content is less than 0.3 mol%. This is interpreted in terms of the efficient energy transfer between Tm³⁺ and Er³⁺ ions. The calculated color coordinates fall within the white region in the standard 1931 CIE chromaticity diagram, indicating the potential applications of Er³⁺-Tm³⁺-Yb³⁺ doped CaSnO₃ in the field of displaying and lasers, etc.