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 4G5/2 → 6HJ (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 Ce0.02Sm0.04Lu2.94Mn0.04Al4.92Si0.04O12 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.