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Highly efficient and thermally stable of a novel red phosphor Sr3NaSbO6:Mn4+ for indoor plant growth
摘要： Far red-emitting Mn4+-activated oxide phosphor based on the substitution of Mn4+ for Sb5+ in the lattice of Sr3NaSbO6 (SNSO) was prepared via solid state reaction process. The crystal structure of the host was carefully discussed and studied. The resultant phosphors were characterized by X-ray powder diffraction, fluorescence spectra, ultraviolet-visible diffuse reflectance spectra, temperature-dependent emission spectra (298–548 K), luminescence decay curves and electroluminescence spectra. Excitation and emission spectra indicated that the sample had a wide excitation band in UV(250–400 nm) and exhibited the strong emission band centered at 695 nm. The band structure for SNSO was calculated based on the density functional theory, and the bandgap value of SNSO host is ～2.92 eV. In addition, the mechanism of quenching concentration and energy-transfer of SNSO:Mn4+ were explored and analyzed in detail through calculation. The UV–Vis diffusion reflectance spectra demonstrated that samples had strong absorption (200–550 nm) in the ultraviolet(UV) and near-ultraviolet (NUV) region. The thermal stability of SNSO:Mn4+ was excellent (I423K/I273K = 39.84%). The internal quantum efficiency is 56.2%. In brief, the prepared phosphors had potential application in indoor plant growth as a LED lamp.
关键词： Sr3NaSbO6:Mn4+,Far red-emitting LED,Photoluminescence,Optical properties,Plant growth
更新于2025-09-23 15:23:52
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Simultaneously enhanced far-red luminescence and thermal stability in Ca3Al4ZnO10:Mn4+ phosphor via Mg2+ doping for plant growth lighting
摘要： Non-rare-earth-based Ca3Al4ZnO10:Mn4+,Mg2+ (CAZO:Mn4+,Mg2+) phosphors with admirable luminescence performance and great potential as far-red light source for plant growth light-emitting diodes (LEDs) were reported in this paper. The concentration-dependent optical properties of the as-prepared phosphors were investigated in detail. Under ultraviolet-light excitation at 358 nm, the composition-optimized CAZO:0.4%Mn4+,14%Mg2+ phosphor showed an intense broad far-red emission band in the 625-830 nm wavelength range with a maximum at 714 nm, which was due to the 2Eg→4A2g transition of Mn4+ ions. The luminescence intensity of the CAZO:0.4%Mn4+,14%Mg2+ phosphor was about 1.82 times higher than that of CAZO:0.4%Mn4+ phosphor, and the corresponding mechanism for the luminescence enhancement via Mg2+ doping was studied. Amazingly, the internal quantum efficiency of the CAZO:0.4%Mn4+ phosphor was increased from 31 to 60% after co-doping 14 mol% Mg2+. The CAZO:0.4%Mn4+,14%Mg2+ phosphor also showed enhanced thermal stability compared with the CAZO:0.4%Mn4+ counterpart. It was found that, for CAZO:0.4%Mn4+,14%Mg2+ phosphor, the emission intensity at 423 K (150 oC) was about 51% of that at 303 K (30 oC), while the corresponding activation energy was determined to be 0.245 eV.
关键词： thermal stability,plant growth,phytochrome,far-red emissions,LEDs.,Mn4+ ions
更新于2025-09-23 15:22:29
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Coumarin Caged Compounds of 1-Naphthaleneacetic Acid as Light-Responsive Controlled-Release Plant Root Stimulators
摘要： Six coumarin caged compounds of NAA comprising different substituents on the coumarin moiety were synthesized and evaluated for their photo-physical and chemical properties as light-responsive controlled-release plant root stimulators. The 1H-NMR and HPLC techniques were used to verify the release of NAA from the caged compounds. After irradiation at 365 nm, the caged compounds exhibited the fastest release rate at t1/2 of 6.7 days and the slowest release rate at t1/2 of 73.7 days. Caged compounds at high concentration (10-5 M and 10-6 M) significantly stimulate secondary root germination while free NAA at the same level is toxic and leads to inhibition of secondary root germination. Cytotoxicity of the caged compounds against Fibroblasts and Vero cells were evaluated and the results suggested that at 10-5 – 10-6 M, caged compounds exhibit no significant cytotoxic to the cells. Thus, the caged compounds of NAA in this study can be of great benefits as efficient agrochemicals.
关键词： Photoremovable protecting groups,Agrochemicals,Coumarin caged compounds,Photocontrolled-release plant growth regulators,Plant root simulators,1-Naphthaleneacetic acid
更新于2025-09-23 15:21:01
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Plant Growth and Photosynthetic Characteristics of Soybean Seedlings Under Different LED Lighting Quality Conditions
摘要： Light-emitting diodes (LEDs) have recently been widely used as light sources for the cultivation of plants in controlled environments. However, before LEDs can be used as the sole light source, it is imperative that soybean (Glycine max) response to light quality be well characterized. The objective of the present work was to investigate how soybean seedlings respond to different blue (B) and red (R) photon flux ratios (PFR) using LEDs. Light treatments were comprised of 170 ± 5 μmol m?2 s?1 photosynthetic photon flux density with B:R ratios of 0B:100R%, 10B:90R%, 25B:75R%, 50B:50R%, 80B:20R%, 90B:10R%, and 100B:0R%. Our results suggest that with the increase in B PFR from 0 to 90%, both plant height and specific leaf area inclined to decline while stem diameter gradually increased. The plants exposed to 80B:20R% showed unexpectedly greater total root length, root surface area, root volume, number of root tip, plant dry mass, leaf dry mass, root dry mass, leaf mass fraction and root mass fraction than plants exposed to all other treatments. Plants grown with 0B:100R% had the highest content of chlorophyll b (Chl b) and content of total chlorophyll [Chl (a + b)] but possessed the lowest ratio of the content of chlorophyll a to the content of chlorophyll b (Chl a/b). Plants grown with R alone also showed the lowest chlorophyll fluorescent parameters. The light-saturated CO2 assimilation rate (Asat) and the light-saturated stomatal conductance (gssat) for 0B:100R% were, respectively, 64.85% and 203.23% lower than those for 80B:20R%. However, plants grown with sole R accumulated higher soluble sugar and starch content during the daytime. Collectively, our results suggest that compared to R- or B-LED alone, an appropriate combination of R and B promotes plant growth and photosynthetic performance for soybean.
关键词： Soybean,Plant growth,Light quality,Photosynthetic characteristics,LED
更新于2025-09-23 15:21:01
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High performance red/deep-red emitting phosphors for white LEDs
摘要： Highly efficient oxide based red line emitters are still bottleneck for the smart white LEDs. In the present investigation, sequences of narrow band red emitting phosphors were synthesized through the conventional solid-state technique. The X-ray diffraction studies reveals that the synthesized phosphors were crystallized in the trigonal phase with space group I41/a (88). Under 395 nm excitation, NaSrGd(MoO4)3:Eu3+ phosphors shown sharp red emission around at 616 nm because of the 5D0→7F2 transition (ED transition). Moreover, the internal quantum efficiency (IQE) was found to be 82 %, and the thermal stability study showed that the NaSrGd0.5Eu0.5(MoO4)3 phosphor retains the emission intensity around 71.5% at 423K of its initial room temperature. The red LEDs were designed for the NaSrGd0.5Eu0.5(MoO4)3 red phosphors with the NUV LED chip. White LED also been fabricated by conjugating the blue LED with yellow dye + red phosphor and the LED shown CCT (6823 K), CRI (74%), CIE (0.306, 0.331). The Sm3+ and Eu3+ co-doped deep red phosphor were synthesized and studied for the plant growth. The LED emission of Sm3+ and Eu3+ co-doped phosphor is completely covers the absorption spectrum of Phytochrome Pr. All of these consequences revealed that the synthesized phosphor could be the efficient red emitting phosphor for warm white LEDs and plant growth filed research.
关键词： Eu3+ red phosphor,Quantum Yield,White LED,Plant growth,Molybdate
更新于2025-09-23 15:19:57
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Structure identification and strongly enhanced luminescence of Sr9Y2(WO6)4: Mn4+ phosphors by co-doping Mg2+ ions for plant growth LEDs
摘要： In this paper, we reported a novel far-red emitting phosphor Sr9Y2(WO6)4: Mn4+ and alkaline earth metal Mg2+ ion co-doped phosphor Sr9Y2(WO6)4: Mn4+, Mg2+. Systematical studies on its crystal structure and luminescence properties are carried out. X-ray powder diffraction confirmed that the pure phase Sr9Y2(WO6)4: Mn4+ and Sr9Y2(WO6)4: Mn4+, Mg2+ phosphors show a single phase. Upon 350 nm excitation, the phosphors could emit far-red emission in the range of 600–800 nm, peaking at 680 nm (14,706 cm?1) due to the 2Eg→4A2g transition, with broad spectra overlap with the absorption band of phytochrome PFR. The optimal doping concentration, concentration quenching mechanism, as well as the content and temperature dependent decay times of Sr9Y2(WO6)4: Mn4+ and the related mechanisms are deeply studied. Ultimately, a far-red light emitting diode lamp is fabricated by exciting a far red phosphor Sr9Y2(WO6)4: 0.0025Mn4+, 0.01Mg2+ using a 365 nm n-UV illuminating LED chip. Our studies have shown that Sr9Y2(WO6)4: Mn4+, Mg2+ phosphors have potential application in controlling or adjusting plant growth in plant-lighting.
关键词： Sr9Y2(WO6)4: Mn4+,Plant growth,Phosphors,Far-red emitting,Mg2+
更新于2025-09-23 15:19:57
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(Ba,Sr)LaZnTaO6:Mn4+ far red emission phosphors for plant growth LEDs: structure and photoluminescence properties
摘要： It is necessary to develop novel high-efficient red or far-red-emitting in order to facilitate the phosphor-converted light-emitting diodes (pc-LEDs) for plant growth. This work reports a series of novel far-red emitting (Ba,Sr)LaZnTaO6:xMn4+ phosphors with double perovskite structure synthesized by traditional high-temperature solid-state reaction (SSR) process. The crystal structure and morphology of (Ba,Sr)LaZnTaO6 are investigated by high-resolution TEM, SEM, and XRD Rietveld refinement. The photoluminescece properties are systematically explored and analyzed by diffuse reflection (DR) spectra, photoluminescence emission (PL) and excitation (PLE) spectra, decay curves and temperature-dependent spectra. Mn4+ ions occupy Ta5+ sites located at [TaO6] octahedral emitting red light with peak at 698 nm in BaLaZnTaO6:Mn4+ and 695 nm in SrLaZnTaO6:Mn4+ under n-UV and blue light excitation. The critical quenching concentration of Mn4+ was determined to be 0.008. The concentration quenching mechanism could be a dipole-dipole interaction between Mn4+ ions. In addtion, the PL intensity of (Ba,Sr)LaZnTaO6:xMn4+ phosphors decrease with increasing temperature. The SrLaZnTaO6:xMn4+ sample has better thermal stability than BaLaZnTaO6:xMn4+. Interestingly, (Ba,Sr)LaZnTaO6:0.008Mn4+ exhibits outstanding internal quantum efficiency (IQE ≥ 80 %). Fianally, the fabricated of LEDs are combined with SrLaZnTaO6:0.008Mn4+ phosphors combined with 460 nm InGaN chips, which emit blue and red light. Based on above properties, the rare-earth-free (Ba,Sr)LaZnTaO6:xMn4+ phosphors have great potentials to be serviced as far-red emitting phosphors in high-power plant growth LEDS.
关键词： double perovskite structure,phosphor-converted light-emitting diodes,internal quantum efficiency,far-red emitting,plant growth,Mn4+,thermal stability,photoluminescence,solid-state reaction
更新于2025-09-23 15:19:57
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Red shift properties, crystal field theory and nephelauxetic effect on Mn4+-doped SrMgAl10-yGayO17 red phosphor for plant growth LED light
摘要： The discovery of novel Mn4+-doped oxide red phosphor with suitable spectrum for plant growth is a hot issue in the recent years due to the characteristic red photoluminescence of 2Eg → 4A2 transition in Mn4+ ions. Generally, the emission position of Mn4+ is hard to tune because of specific crystal field in most phosphors. In this work, tunable luminescence property with obvious red shift in the spectra is observed in the Mn4+-doped SrMgAl10-yGayO17 red phosphor via simple substitution of Ga3+ for Al3+, and crystal field theory and nephelauxetic effect are employed to explain this phenomenon. Meanwhile, the Ga3+ dopant changes the shape of the spectra because Ga3+ dopant guides the replacement site of Mn4+ and changes the luminescence center. Improved emission intensity is obtained because appropriate Ga3+ doping leads to larger band gap and reduces non-radiative transitions. Phosphor-converted LED (pc-LED) devices fabricated with blue chip (470 nm) and the as-obtained SrMgAl10-yGayO17:1.0%Mn4+ phosphors emit bright blue and red light, which fit the absorption regions of plant pigments well, thus SrMgAl10-yGayO17:Mn4+ phosphor can be a candidate for plant growth LED light.
关键词： crystal field theory,SrMgAl10-yGayO17:Mn4+,plant growth LED light,red shift,nephelauxetic effect
更新于2025-09-23 15:19:57
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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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Novel efficient deep-red-emitting Ca2LuTaO6:Mn4+ double-perovskite phosphors for plant growth LEDs
摘要： Deep-red-emitting phosphors are important for fabricating light-emitting diodes (LEDs) toward applications in plant growth lighting. Herein, we reported on novel efficient deep-red-emitting Mn4+-activated Ca2LuTaO6 (CLT) double-perovskite phosphors. A series of CLT:xMn4+ (x = 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%) samples were prepared by the conventional high-temperature solid-state reaction technique, and they were characterized by using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), elemental mapping, photoluminescence excitation and emission, decay curves, CIE chromaticity coordinates, internal quantum efficiency (IQE), and temperature-dependent emission spectra. The CLT host crystallized in a monoclinic structure with space group of P21/n, and it contained an octahedral site of TaO6 for Mn4+ doping. Impressively, under 351 ultraviolet light excitation these CLT:xMn4+ phosphors exhibited bright deep-red emissions around 682 nm with CIE chromaticity coordinates of (0.7272, 0.2728) and full width at half maximum (FWHM) of 25 nm. Notably, the optimal CLT:0.2%Mn4+ sample possessed an IQE of 37% and good resistance to thermal quenching (I423 K/I303K = 47%). Considering the emission spectrum of CLT:0.2%Mn4+ deep-red-emitting phosphors matched well with the absorption spectrum of phytochrome PFR, the as-prepared CLT:0.2%Mn4+ phosphors showed great potential in plant growth LEDs.
关键词： Deep-red emissions,Phosphors,Luminescence,Double-perovskite,Mn4+,Plant growth lighting
更新于2025-09-19 17:13:59