Enhancing blue light emission in Y2O3:Ce3+, Eu2+ through Ce3+→ Eu2+ energy transfer

The blue emitting phosphors have numerous scopes in solid-state lighting applications. We synthesised a set of blue emitting Y₂O₃ phosphors co-doped with 1 mol% Ce³⁺ and 1, 2, 3, 4 mol% Eu²⁺. An X-ray diffraction study revealed that the samples have a cubic crystal structure. The 1 mol% Ce doped sample produced a strong absorption band at ∼206 nm. This absorption band was found to red-shift after co-doping with Eu ions. Under 300 nm ultraviolet excitation, the Eu²⁺-Ce³⁺ co-doped phosphors exhibited characteristic blue luminescence corresponding to transitions from the lowest Ce³⁺ 5d excited state to ²F₇/₂ and ²F₅/₂ 4f ground state levels. In addition, the blue emission is also ascribed to the inter-configurational 4f⁶5 d¹ – 4f⁷ allowed transition of Eu²⁺ ions. The photoluminescence spectra, luminescence decay curves and energy transfer efficiency all indicated a possible energy transfer from Ce³⁺ → Eu²⁺ ions.