Samarium and manganese incorporation to improve color rendering of LuAG:Ce3+ phosphor ceramics for laser-driven lighting: a Color-tunable and energy transfer study

Abstract

Deficient red and cyan components are critical limitations that hamper the real applications of single-structured phosphor ceramics in laser-driven white lighting sources (white LDs). In this study, Ce³⁺ and Sm³⁺ were incorporated into Lu₃Al₅O₁₂ (LuAG:Ce³⁺,Sm³⁺) ceramics for the fabrication of white LDs. Multiple narrow-intensified emissions around 569 nm, 618 nm, and 667 nm originating from the ⁴G_5/2 → ⁶H_J (J = 5/2, 7/2, 9/2) transitions of Sm³⁺ were identified as an efficient energy transfer (ET) from Ce³⁺ to Sm³⁺ ions. Impressively, the ET efficiency of 47.4% from Ce³⁺ to Sm³⁺ was achieved by spectral regulation; this was the highest value among those of Ce³⁺–Sm³⁺-co-doped garnet phosphor materials, and its mechanism was deduced to be dipole–dipole interactions based on the Inokuti–Hirayama (I–H) model. The integral and red emission intensities of the as-prepared LuAG:0.02Ce³⁺,0.04Sm³⁺ ceramics at 425 K were 85.8% and 75.3% of that at 300 K, respectively, implying satisfactory thermal stability of fluorescence. A white LD with a high color rendering index (CRI) of up to 78.5 was obtained with the introduction of Mn²⁺ into the LuAG:Ce³⁺,Sm³⁺ system by employing single-structured Ce_0.02Sm_0.04Lu_2.94Mn_0.04Al_4.92Si_0.04O₁₂ phosphor ceramics under 450 nm laser excitation. This result provides a promising pathway for high color quality and practical solid-state lighting based on garnet phosphor ceramics.