Photoluminescence Properties and Concentration Quenching Mechanism of Eu3+-Doped CaLa2Mo4O16 Phosphor for Red-Emitting LED

Abstract

The red-emitting Eu³⁺-activated CaLa₂Mo₄O₁₆ phosphors have been successfully prepared at 750°C by combustion method, which was reported first time for current work. The structural, morphological, and the photoluminescence characteristics of CaLa₂Mo₄O₁₆ phosphors were throughout examined. All the phosphor compositions display broad absorption bands due to O → Mo and O → Eu charge transfer (CT) transitions, along with excellent photoluminescence characteristics, including intense electric dipole transitions (⁷F₀ → ⁵D₂). The CaLa₂Mo₄O₁₆:Eu³⁺ when excited under near UV and blue light, phosphors display intense emission of red color at 617 nm, which ascribes due to the induced electric dipole transition (⁵D₀ → ⁷F₂). At 0.5 mol%, the maximum intensity was achieved. Dipole–dipole interaction in Eu³⁺–Eu³⁺ ions causes concentration quenching mechanism. According to calculations, the sample color coordinates under 394-nm excitation were (0.586, 0.412) at 592 nm and (0.684, 0.314) at 617 nm, which are quite similar to the normal red values of (0.68, 0.34). Therefore, the synthesized phosphors show potential as red emitters for applications in phosphor-converted red light-emitting diodes.