Single-phase white-light emitters in the lighting technology overcome the challenges of re-absorption and color shift. However, achieving the broadband white emission in single-phase phosphor remains a challenge. Here, crystallized KBaScSi 3 O 9 :Eu 2+ (KBSSO:Eu 2+ ) glass-ceramics (GC) with abundant cationic sites have been developed and an ultra-broad emission band ranging from 460 to 800 nm have been found, in which the asymmetric green emission is ascribed to the Eu 2+ ions in [KO 8 ] and [BaO 7 ] polyhedra, while the red emission centered at 620 nm is originated from Eu 2+ ions in [ScO 6 ] sites. The optimized GC-converted white LED (WLED) exhibits a high color rendering index ( R a = 89.8) and low correlated color temperature (CCT = 4241 K). Moreover, the encapsulant-free GCc-WLED can operate continuously under high drive currents. This work paves the way for the design and future development of single-phase high-power white light sources.
The exploration of stable/efficient phosphor for n -UV chip pumped white light-emitting diodes ( w LEDs) remains an arduous task. Herein, a novel series of color tunable Eu 2+ /Tb 3+ /Sm 3+ tridoped Sc-based cyclosilicate phosphors (KBaScSi 3 O 9 : Eu 2+ /Tb 3+ /Sm 3+ ) have successfully designed and obtained via facile solid-state reaction based on comprehensive consideration of rigidly structural network of host, weak electron-phonon coupling strength and spectral adjustability of codopants via energy transfer (ET). The crystallographic occupancies of Eu, Tb and Sm primary in Ba/K, Ba and Ba sites in the monoclinic host, respectively were determined on the basis of the Rietveld refinements and crystal chemistry rules. The photoluminescence (PL) properties were systematically investigated in conjunction with structural analyses, implying that the ‘warm’ white light with excellent thermal stability is stemmed from combination of optimized blue (Eu 2+ ), green (Tb 3+ ) and red (Sm 3+ ) emissions via Eu → Tb → Sm ET strategy. Interestingly, Tb ions play both roles of green light luminescent center and ET bridge to achieve cascade ET for connecting Eu/Sm ion pairs because of the adverse metal-metal charge transfer (MMCT) effect (Eu 2+ + Sm 3+ → Eu 3+ + Sm 2+ ). Furthermore, the phosphor-converted w LEDs (pc- w LEDs), by encapsulating the optimal KBS: 4 %Eu/4 %Tb/6 %Sm with commercial n -UV LED chip, show high thermal stability with satisfactory electroluminescence (EL) performances. These results indicate the KBS: Eu/Tb/Sm phosphors are potential candidates for application in high power n -UV pumped pc- w LEDs.
危险品化学品经营许可证（带存储）