Dazzling Red-Emitting Europium(III) Ion-Doped Ca2LaHf2Al3O12 Garnet-Type Phosphor Materials with Potential Application in Solid-State White Lighting

Bright red-emitting phosphors with high color purity and high photoluminescence quantum yield (PLQY) are highly demanded for the fabrication of high-performance warm-white light-emitting diodes (LEDs). Herein, we demonstrated a novel efficient Eu³⁺-activated Ca₂LaHf₂Al₃O₁₂ garnet phosphor with excellent luminescence properties for near-ultraviolet (near-UV) excited warm-white LEDs. The Ca₂LaHf₂Al₃O₁₂:Eu³⁺ phosphors exhibited an intense excitation spectrum in the near-UV region with a maximum around 394 nm, and they produced dazzling red luminescence peaking at 592, 614, 659, and 711 nm due to the ⁵D₀ → ⁷F_J (J = 1-4) transitions of Eu³⁺ ions when the excitation wavelength was set at 394 nm. Luminescent properties have been studied as a function of Eu³⁺ doping concentration, and the highest emission intensity was achieved at 50 mol % Eu³⁺, while the dipole-dipole interaction brought the concentration quenching effect. The Ca₂LaHf₂Al₃O₁₂:50%Eu³⁺ sample exhibited CIE chromaticity coordinates of (0.6419, 0.3575) with a color purity of 92.7%, and its PLQY was measured to be 64%. The thermal stability and activation energy of Ca₂LaHf₂Al₃O₁₂:50%Eu³⁺ phosphors were also discussed and analyzed. Finally, we made a near-UV chip-based white LED device in which the Ca₂LaHf₂Al₃O₁₂:50%Eu³⁺ phosphor was utilized as a red ingredient. A bright warm-white light emission was realized from this LED device under 80 mA driving current, accompanied by a high color rendering index (CRI) of 88.3, a low correlation color temperature of 3853 K, and good CIE chromaticity coordinates of (0.3909, 0.3934). These results revealed that these red-emitting Ca₂LaHf₂Al₃O₁₂:Eu³⁺ phosphors have promising application prospect in near-UV-excited warm-white LEDs with high a CRI.