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Mn <sup>4+</sup> -activated BaLaMgSbO <sub/>6</sub> double-perovskite phosphor: a novel high-efficiency far-red-emitting luminescent material for indoor plant growth lighting
摘要： In the present work, novel high-efficiency Mn4+-activated BaLaMgSbO6 (BLMS) far-red-emitting phosphors used for plant growth LEDs were successfully synthesized via a solid-state reaction method. X-ray diffraction (XRD), photoluminescence (PL), temperature-dependent PL, CIE color coordinates, and lifetimes as well as internal quantum efficiency (IQE) were used to characterize the phosphor samples. The excitation spectrum of the as-obtained BLMS:Mn4+ phosphors presented two wide bands covering 250–550 nm and the emission spectrum exhibited a far-red emission band in the range of 650–800 nm peaked at 700 nm. Concentration-dependent PL properties of BLMS:Mn4+ phosphors were studied. The optimal doping concentration of Mn4+ ions was 0.6 mol%, and the concentration quenching mechanism was determined to be the nonradiative energy transfer among the nearest-neighbor Mn4+ activators. Impressively, the BLMS:0.6%Mn4+ sample showed an outstanding IQE of 83%. In addition, the luminescence thermal quenching characteristics were also analyzed. Furthermore, the PL spectrum of BLMS:0.6%Mn4+ sample was compared with the absorption spectrum of phytochrome PFR. Finally, after combining BLMS:0.6%Mn4+ phosphors with a 365 nm near-UV LED chip, a far-red light-emitting diode (LED) device was successfully achieved to demonstrate its possible applications in plant growth LEDs.
关键词： far-red-emitting,solid-state reaction,Mn4+-activated,internal quantum efficiency,plant growth LEDs,phosphor,BaLaMgSbO6
更新于2025-09-19 17:15:36
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Improved luminescence properties of a novel red dodec-fluoride phosphor Ba <sub/>3</sub> Sc <sub/>2</sub> F <sub/>12</sub> :Mn <sup>4+</sup> with extraordinary thermal stability for WLED application
摘要： Mn4+-activated red phosphors have recently attracted tremendous attention for their fascinating performance in white light emitting diodes (WLEDs) application to achieve warm white light, while the thermal stability of fluoride is still considered as a drawback. Herein, we report a novel red phosphor composed of Ba3Sc2F12:Mn4+ (BSF:Mn), in which, the emitting centers of Mn4+ ions are locating in the sites of Sc3+ ions. The photoluminescence of BSF:Mn varies with the concentration of K2MnF6, reaction temperature, and the concentrations of NH3·H2O in reaction system. Partly substituting Ba2+ with Ca2+ decreases the luminescent intensity of BSF:Mn. By employing the as-prepared phosphor BSF:Mn as a red component, a high-performance WLED with a correlated color temperature (CCT) at 4796 K and a color rendering index (CRI) of 85.2 was obtained. The phosphor BSF:Mn keeps undecomposed up to 800 oC, therefore, this work exhibits a strategy to explore a novel Mn4+-doped fluoride with particularly thermal stability.
关键词： luminescent properties,thermal stability,Ba3Sc2F12:Mn4+,Mn4+-activated red phosphors,WLEDs
更新于2025-09-19 17:13:59
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Transition metal ion Co-Doped MgO–MgF2-GeO2:Mn4+ red phosphors for white LEDs with wider color reproduction gamut
摘要： Mn4+-activated non-rare-earth based red phosphors are excellent down conversion materials for phosphor-converted light-emitting diode (pc-LEDs) based solid-state lighting applications. However, the low quantum efficiency of Mn4+ activated red phosphors under InGaN based blue LED excitation hinders their use in phosphor-converted LEDs. To enhance the absorption at an excitation wavelength of around 420 nm in Mn4+-doped MgO-MgF2-GeO2 (MGF: Mn4+), which is a conventional red-emitting lamp phosphor, we doped MGF: Mn4+ phosphors with transition metal oxides (Sc2O3, Lu2O3, Y2O3, and La2O3) replacing MgO. When excited using 420 nm light, the absorption ratio of the synthesized phosphors with Sc2O3 (Sc-MGF:Mn4+) was 58% with an internal quantum efficiency (IQE) of 55% as compared to the 35% IQE of the pristine MGF-Mn4+ phosphor. White LEDs were fabricated using Sc-MGF-Mn4+ (red), and β-SiAlON:Eu2+ (green) on InGaN chips (λem = 450 nm) and their performance was compared to the optical performance of LEDs fabricated using K2SiF6:Mn4+ as the red phosphor. According to the National Television System Committee (NTSC) standard, the color reproduction coverage with an Sc-MGF:Mn4+ phosphor-loaded white LED was 121% by the International Commission on Illumination (CIE) 1976, and 80% by the BT.2020 standard. The coverages are 9% and 6% higher than the coverages of LEDs fabricated using K2SiF6:Mn4+ as the red phosphor according to the NTSC and BT.2020 standards, respectively. Our simple approach to enhance the IQE of Mn4+ activated phosphors by co-doping transition metal oxides can be extended to other Mn4+ activated phosphor systems for applications that require enhanced absorption, higher luminescent emission intensity, and a wider gamut of color reproduction.
关键词： MgO-MgF2-GeO2,Mn4+ activated red phosphors,Solid-state lighting,White LEDs,BT.2020
更新于2025-09-12 10:27:22