Tunable emission from green to red in the GdSr2AlO5:Tb3+,Eu3+ phosphor via efficient energy transfer

Herein, a series of GdSr₂AlO₅:Tb³⁺,Eu³⁺ phosphors were successfully synthesized through a high temperature solid-state reaction, and their crystal structures as well as photoluminescence properties were investigated in detail. Compared to the intense emission of ⁵D₀ → ⁷F₁ or ⁵D₀ → ⁷F₂ transition of Eu³⁺, another strong emission corresponding to ⁵D₀ → ⁷F₄ was observed. Concentration quenching is not obvious in Tb³⁺ or Eu³⁺-doped GdSr₂AlO₅ because structure isolation and energy transfer (ET) of Gd³⁺ → Eu³⁺ and Gd³⁺ → Tb³⁺ were found. Moreover, the energy transfer process from Tb³⁺ to Eu³⁺ was verified by the overlap of luminescence spectra and the variation of lifetime. Energy transfer mechanism was determined to be a dipole–dipole interaction, and ET efficiency as well as quantum efficiency were also obtained. Moreover, the emission color of GdSr₂AlO₅:Tb³⁺,Eu³⁺ can be tuned from green to red by altering the ratio of Tb³⁺/Eu³⁺. These results indicate that the GdSr₂AlO₅:Tb³⁺,Eu³⁺ phosphor is a promising single-component white light-emitting phosphor.

The emission spectra of GdSr₂AlO₅:2%Tb³⁺,x%Eu³⁺ (x = 0, 0.5, 1, 2, 3, and 5) under 275 nm excitation. (b) Variation tendency of the green emission of Tb³⁺ and the red emission of Eu³⁺.