Energy transfer for Ce3+ → Tb3+ → Sm3+ induced bright white emission in single-phase CaLa4(SiO4)3O:Ce3+, Tb3+, Sm3+ phosphors and their application in white-light-emitting diodes

Abstract

The emergence of phosphor-converted white-light-emitting diodes has crucial significance in the sustainable development of energy; hence, the evolution of phosphors with eminent luminescence and high stability is imperative. In this study, a tri-doped system composed of rare earth ions Ce³⁺, Tb³⁺, and Sm³⁺ incorporated into a CaLa₄(SiO₄)₃O host is reported, and the energy transfer, tunable single-phase white emission, and favorable thermostability of the Ce³⁺-Tb³⁺-Sm³⁺ system were explored. Rietveld refinement results coincided with the original model of the crystal structure, and a band gap energy of 4.612 eV calculated using density functional theory (DFT) demonstrated the system as an appropriate luminescent host with a wide energy gap. Furthermore, ET processes for Ce³⁺ → Tb³⁺, Tb³⁺ → Sm³⁺, and Ce³⁺ → Tb³⁺ → Sm³⁺ were investigated via steady-state photoluminescence and decay measurements. Besides, the activation energies of CLSO:3%Ce³⁺, 9%Tb³⁺, y%Sm³⁺ (y = 7, 9) were 0.205 eV and 0.223 eV, respectively, showing outstanding thermal quenching resistance. Devices made with LED beads containing CLSO:3%Ce³⁺, 9%Tb³⁺, y%Sm³⁺ (y = 7, 9) phosphors exhibited bright white light with CCT ≈ 3586 and 3307 K and Ra ≈ 81.0 and 78.5, respectively. This study demonstrates that energy transfer for Ce³⁺-Tb³⁺-Sm³⁺ in a tri-doped system offers an interesting design prospect for promoting single-phase white emission phosphors.