Yonghui Xu,Liang Zhang,Shuwen Yin,Xiudi Wu,Hongpeng You
Despite significant progress has been made in the luminescent materials for white light emitting diodes (WLEDs), it is still desirable to develop novel highly efficient phosphors with appropriate excitation and high visible emission for high color rendering WLEDs. In this study, we report a novel phosphor BaGa 2 Si 2 O 7 :Ce 3+ ,Tb 3+ (BGSO:Ce 3+ ,Tb 3+ ) with highly effective green luminescence. BGSO:Ce 3+ ,Tb 3+ phosphor represents a broad excitation band in the range of 300–400 nm and intense emission at approximately 542 nm with a high photoluminescence quantum efficiency of 76.4%. The structure, luminescence, and energy transfer from the Ce 3+ and Tb 3+ ions were investigated in detail. Moreover, the incorporation of Na + or K + ions into BGSO:Ce 3+ ,Tb 3+ for charge compensation can improve the emission intensity and thermal stability. Moreover, a near ultraviolet (n-UV) pumped prototype WLED device was fabricated and it exhibited bright warm-white light with CIE chromaticity coordinates of (0.3561, 0.3344), high color-rendering index (Ra=90.4), and low CCT (3330 K) upon 20 mA driving current. This work provides a new strategy to develop high-quality solid-state LED phosphors.
Liu Dong,Jin Yahong,Xiong Guangting,Lv Yang,Wu Haoyi,Ju Guifang,Chen Li,Hu Zhengfa,Hu Yihua
A series of broadband blue-green phosphors Rb 0.5+ y Na 1.5− y (Li 3 SiO 4 ) 2 : x Eu 2+ (0 ≤ y ≤ 0.4, 0.01 ≤ x ≤ 0.08) were synthesized by the high-temperature solid-state reaction. The powder X-ray diffraction was employed to explore the crystal structural evolution from RbNa 3 (Li 3 SiO 4 ) 4 to RbNa(Li 3 SiO 4 ) 2 with the increasing of Rb + . The spectra show the optimized composition was determined as y = 0.4. The luminescence, lifetime decay curves and thermal steadily spectra of Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 : x Eu 2+ phosphors were investigated in detail. The phosphor of Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ shows suitable visible spectra (450–550 nm, cover the blue and green regions), excellent thermal quenching (104%@150 °C of the initial integrated intensity at room temperature under 396 nm excitation) and broad excitation spectrum (320–450 nm). Finally, a commercial near-UV LED devices (395 nm) were fabricated with the Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ phosphor as blue-green and commercial red phosphor CaAlSiN 3 :Eu 2+ with a warm color temperature of 3104 K and a color rendering index of 91.8. This result indicated that Rb 0.9 Na 1.1 (Li 3 SiO 4 ) 2 :Eu 2+ may be a promising blue-green phosphor for indoor lighting.
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