Indoor Plant Cultivation Research Articles

Structural and luminescence properties of Y2O3:Ho3+ phosphor: Potential applications in plant cultivation LEDs and thermoluminescent dosimetry

Current research on Y2O3:Ho3+ phosphors highlight their promising luminescence properties, but often lacks an environmentally friendly synthesis method and comprehensive analysis of their applications. In this study, we address these gaps by successfully synthesizing Y2O3:Ho3+ phosphors using a green synthesis route with varying concentrations of Ho3+. Our work provides detailed characterization of their photoluminescence (PL) and thermoluminescent (TL) properties. The PL excitation (PLE) spectra reveal a distinct peak at 439 nm, attributed to the 5I8→(5K5; 5G5) transition of Ho3+ions. Upon excitation at 439 nm, the emission spectra show a sharp emission peak around 660 nm from the 5F5→5I8 transition, with the 0.1 mol% Ho3+ phosphors exhibiting particularly strong red emission, indicating their suitability for indoor plant cultivation under LED lighting. Additionally, TL properties were evaluated after gamma-ray exposure, with the highest emission intensity at 0.1 mol% Ho3+ concentration. TL glow curves were analyzed for various radiation doses using the Computerized Glow Curve Deconvolution (CGCD) method, and TL trapping parameters were determined through Chen's peak shape and the Initial Rise methods. This work demonstrates significant potential for using these phosphors to enhance indoor plant growth and for applications in thermoluminescent dosimetry (TLD).

Removal of Cadmium from Public Smoking area Soil using indoor Plants and Electrical Grounding

Objectives : In this study, the absorption of heavy metals in the soil from smoking areas using indoor plants and electrical grounding was investigated to increase the utility of indoor plants for soil decontamination.Methods : Soil from plant pots in a smoking area was collected for the experimental plant pot preparations. Some of the prepared pots were connected to electrical ground via an electrode. Kidney beans (<i>Phaseolus vulgaris</i>) were seeded, and their growth were observed. After 30 days of the cultivation, TOC (Total Organic Carbon), and metagenomics profiles in the soil was analyzed. To estimate the behavior of the heavy metals in soil and plants, Cadmium concentrations in the samples were analyzed using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry).Results and Discussion : The connection of the electrical ground to the plant pot induced the rapid growth of plant (48.2 ± 2.3% increase in stem growth), compare to the plant in the pot without the electrical ground. TOC analysis showed that the soil from the grounded pots showed the highest value, compared to the control soil (3.08 ± 1.22%), and the soil from the pot without ground connection (2.3 ± 0.1%). The ICP-MS analysis indicated that the plant body in the grounded pot had the highest cadmium concentration at 0.33 ± 0.018 μg/kg. Using the metagenomic analysis, biomineralization related bacterial species (<i>Nocardioides</i> sp., <i>Streptomyces</i> sp., <i>Sphingomonas</i> sp. etc.) were identified from the grounded soil sample. These results suggested that the indoor plant cultivation with the electrical ground connection as an electrical fertilizer enhances the cadmium absorption by plant, exudate secretion from the plant root, and bacterial flora change in the rhizosphere.Conclusion Cadmium in the soil from the smoking area was absorbed by indoor plant with the electrical ground. Therefore, the application of the electrical ground connection (earth) to the electrically insulated outdoor plant pots might enhance the plant growth rate and physiological activity. This application could be a novel soil decontamination method using plants.

Enhancing the luminescence of Mn4+-doped double perovskite oxide Ca2LuNbO6 phosphor by utilizing A-site cationic fluoride as a flux

Supplement illumination is indispensable in the indoor plant cultivation domain. In this research work, double perovskite Ca2LuNbO6:Mn4+ phosphors were produced. A strategy of enhancing luminescence performance by utilizing A-site cationic fluoride as a flux was proposed. The structure and morphology of Ca2LuNbO6:Mn4+ phosphor was characterized. Under the excitation of 360 nm, the emission spectra of Ca2LuNbO6:Mn4+ phosphor cover from 600 nm to 750 nm peaking at 683 nm. It benefits the red section of chlorophyll absorption band and possesses the wavelengths of 680 nm and 700 nm demanded by photosystem I (PS I) and photosystem II (PS II) to realize Emerson enhancement effect. After adding CaF2 as flux, the emission intensity increases by 2.5 times. Due to its compatibility with the A-site cation of host, CaF2 agent not only lower the sintering temperature but also increase the crystallite size, which result in the enhancement of luminescence. The Dq/B and optical band gap of Ca2LuNbO6 host is 2.32 and 3.79 eV, respectively, which show that Mn4+ ions locate in the [NbO6] octahedra of strong crystal field and host has the suitable optical band gap for Mn4+ ions. With the help of CaF2, the thermal stability, activation energy ΔEa, internal quantum efficiency of Ca2LuNbO6:Mn4+ phosphors are promoted at 373 K from 64.8% to 70.7% of that at 273 K, from 0.33 to 0.36 eV, and from 9.1% to 23.5%. The luminescence lifetime of Ca2LuNbO6:Mn4+ is the order of a fraction of a millisecond. Finally, the as-prepared Ca2LuNb0.996O6:0.004Mn4+ phosphor was successfully fabricated through a 365 nm near ultraviolet (NUV) chip, which has the peak wavelengths of 683 nm and possesses 680 nm and 700 nm demanded by PS I and PS II. It is implied that Ca2LuNbO6:Mn4+ phosphor-converted light emitting diode has prospective market in the domain of supplement illumination of plant cultivation.

Double-perovskite LaBaZnTa1-xMnxO6 phosphors for wide-range optical thermometer and high-quality WLED devices

Due to the huge food demand of the population, the luminescent materials with excellent performance applied for indoor plant cultivation have been extensively studied. In this work, a series of Mn4+-doped LaBaZnTaO6 phosphors in were synthesized and its luminescence mechanism has been researched in detail. Due to their broad absorption band, they could be effectively excited by the NUV to blue LED chip. Importantly, suitable emission in the red region overlapped with the absorption of plant pigments making it possible to be used in indoor plant cultivation. On the other hand, high-sensitivity non-contact optical temperature sensor is the focus of current research, so the optical thermometer-based lifetime model also was designed and investigated in this work. Interestingly, the maximum relative sensitivity was 1.38 %K−1@473 K, suggesting a good development potential of the sample in optical thermometry. Finally, the warm WLED device was fabricated and achieved a superior CRI value of 90.95 and a good CCT of 3582 K. All the obtained results suggest that it could become a promising red component to be applied in optical thermometer and lighting sources.

A highly efficient deep red-emitting Mn4+-powered oxyfluoride nanophosphor developed for plant growth and optical thermometric applications.

This research mainly highlighted an intense deep red-emitting and Mn4+-powered oxyfluoride nanophosphor, Mg14Ge4.99O16F8:0.01Mn4+ (MGOF:Mn), which was synthesized via adopting a scalable synthesis route for commercial temperature sensing and artificial plant growth applications. The electron microscopic analysis confirmed the formation of nanosized particles without any defined shape or size distribution. The obtained nanophosphor exhibited sharp emission peaks at 659 nm and 631 nm under UV (317 nm) and blue excitation (417 nm) owing to Mn4+:2Eg → 4A2g and Mn4+:2T1g → 4A2g transitions, respectively. The emission spectrum is situated in the deep red region of the CIE color diagram where the red color purity approached 100% under both the excitations. The absorption efficiency and the internal and external quantum efficiencies of this red-emitting system were calculated to be 53%, ∼77%, and ∼41%, respectively, under blue excitation of 417 nm, which indicated its potential for indoor plant cultivation. A prototype red LED was fabricated by pasting the red-emitting MGOF:Mn4+ nanophosphor powder on a 410 nm blue LED chip. The resulting electroluminescence spectrum overlapped with those of the important organic pigments of normal plants. Importantly, the thermometric properties of the nanophosphor were evaluated in detail for FIR and lifetime-based thermometry applications. The examined nanophosphor showed an extreme absolute sensitivity of 0.00326 K-1 at 373 K with excellent reproducibility and temperature resolution. Because of the small particle size and high luminescence efficiency, the nanophosphor could be implemented in various nano-devices where non-contact optical thermometry is necessary for high performance.

The Effects of Light Spectrum and Intensity, Seeding Density, and Fertilization on Biomass, Morphology, and Resource Use Efficiency in Three Species of Brassicaceae Microgreens.

Light is a critical component of indoor plant cultivation, as different wavelengths can influence both the physiology and morphology of plants. Furthermore, fertilization and seeding density can also potentially interact with the light recipe to affect production outcomes. However, maximizing production is an ongoing research topic, and it is often divested from resource use efficiencies. In this study, three species of microgreens-kohlrabi; mustard; and radish-were grown under five light recipes; with and without fertilizer; and at two seeding densities. We found that the different light recipes had significant effects on biomass accumulation. More specifically, we found that Far-Red light was significantly positively associated with biomass accumulation, as well as improvements in height, leaf area, and leaf weight. We also found a less strong but positive correlation with increasing amounts of Green light and biomass. Red light was negatively associated with biomass accumulation, and Blue light showed a concave downward response. We found that fertilizer improved biomass by a factor of 1.60 across species and that using a high seeding density was 37% more spatially productive. Overall, we found that it was primarily the main effects that explained microgreen production variation, and there were very few instances of significant interactions between light recipe, fertilization, and seeding density. To contextualize the cost of producing these microgreens, we also measured resource use efficiencies and found that the cheaper 24-volt LEDs at a high seeding density with fertilizer were the most efficient production environment for biomass. Therefore, this study has shown that, even with a short growing period of only four days, there was a significant influence of light recipe, fertilization, and seeding density that can change morphology, biomass accumulation, and resource input costs.

Synthesis, structural and optical properties of a novel double perovskite for LED applications

Amidst growing concerns for environmental sustainability and green ecology, the utilization of Light Emitting Diodes (LEDs) for indoor plant cultivation has emerged as an influential area of research. Nonetheless, the growth of indoor plants is often constrained by inadequate lighting. Consequently, designing novel LEDs to create an appropriate light environment has emerged as a focal point in research. As a new type of photocatalytic material with excellent optical properties and light stability, double perovskite has broad application prospects in LEDs manufacturing. In this context, this article aims to synthesize a new Ca2Lu(Nb,Mn)O6 double perovskite and study its optical properties in LEDs lighting for indoor plant growth. A new Ca2Lu(Nb,Mn)O6 double perovskite were synthesized using the traditional high-temperature solid-phase method. The crystal structure and luminescence properties of the double perovskite were characterized in detail using powder X-ray diffraction (XRD), Rietveld refinement, excitation and emission spectra, decay lifetimes, quantum efficiency (QE), electron paramagnetic resonance (EPR) spectra, temperature-dependent emission spectra, and the Commission International de l’Eclairage (CIE) color coordinates. The photoelectric properties of Ca2Lu(Nb,Mn)O6 and Ca2LuNbO6 double perovskite have been explored through first-principles investigations. The absorption spectra from 270 to 600 nm indicates that it can be effectively excited by ultraviolet (UV) light. The emission spectra show a strong broad red emission peak at 684 nm. The luminescence mechanism has been studied using the Tanabe-Sugano diagram. In addition, the internal UV emission ratio β1, crystal field strength Dq, and Racah parameters B and C were evaluated. The thermal stability of the sample was studied through emission spectra at heating temperatures from 303 to 573 K. The results indicate that Ca2Lu(Nb,Mn)O6 double perovskite provides a new solution for indoor plant growth.

Specific energy analysis of using fertilizer-based liquid desiccants to dehumidify indoor plant environments

Controlling humidity in indoor plant environments is crucial to plant growth, but traditional dehumidification methods can be energy intensive. In this study, we evaluate the energy efficiency of a novel dehumidification concept that uses cold concentrated fertilizer solution as a liquid desiccant agent. This closes the water cycle by recovering water vapor for plant fertigation, and eliminates the need for energy-intensive desiccant regeneration. A theoretical transport model is used to conduct a parametric analysis of the specific energy performance of the system in response to desiccant temperature and other operating conditions. Specific energy of dehumidification is defined here as the ratio of the cooling load to the water vapor removal. Minimum specific energy results between 0.16 and 0.24 Wh/g are achieved at liquid desiccant temperatures between 7 and 14 °C. These results compare very favorably with other dehumidification technologies on the market, and satisfy new energy efficiency standards for indoor plant cultivation. The vapor flux associated with the minimum specific energy ranged from 1.2 to 1.6 g/m2/h. Controlling liquid desiccant temperature is shown to be critical to achieving high dehumidification rates at optimal specific energies. These encouraging results suggest that future research and development along this track can contribute to energy efficient greenhouse cultivation for sustainable food production.

Rare-earth free far-red emitting perovskite phosphor NaYBa4W2O12:Mn4+ for indoor plant cultivation lighting

A series of rare-earth free far-red emitting phosphor NaYBa4W2O12: xMn4+ ( ≤ x ≤ 0.75%, NYBW: Mn4+) is successfully synthesized for application in near-ultraviolet (n-UV) light pumped plant cultivation light-emitting diodes (LEDs). The phase purity, crystal structure, electronic structure and luminescent properties of NYBW: Mn4+ are investigated in detail. The results indicate that all NYBW: Mn4+ phosphors are well crystallized with a direct band gap of 3.86 eV. Broad excitation band can be found with dominant wavelengths at 365 and 520 nm, indicating NYBW: Mn4+ can be efficiently excited by commercial n-UV or green LED chip. Upon 360 nm excitation, NYBW: Mn4+ shows intense broad-band far-red emission centered at 696 nm, attributed to the 2Eg→4A2g transition of Mn4+. The optimal doping concentration of Mn4+ is determined to be 0.1% and the concentration quenching mechanism is the dipole-quadrupole interaction. The decay time decreases from 0.58 to 0.081 ms with Mn4+ concentration increasing from 0.025 to 0.75%. The temperature quenching behaviour of Mn4+ in NYBW is investigated, with a thermal activation energy estimated to be about 0.375 eV. Finally, a far-red emitting LED device is fabricated by coating NYBW: Mn4+ phosphor on a 365 nm n-UV LED chip. The above results guarantee that the as-prepared far-red emitting phosphor NYBW: Mn4+ has great potential for application in indoor plant cultivation LEDs.

A double-perovskite Mn4+-doped Sr2ScNbO6 phosphor for indoor plant growth lighting

To find suitable far-red-emitting phosphors in the field of plant lighting, a series of double-perovskite Mn4+-doped Sr2ScNbO6 (abbreviated as SSNO: Mn4+) phosphors were prepared and their crystal structure, morphology, and photoluminescence were analyzed. SSNO: Mn4+ phosphor produces far-red light with a peak wavelength of 702 nm. And this phosphor has two unique efficient broad excitation bands located respectively around 313 nm and 357 nm in the near-ultraviolet (UV) regions. The optimal doping concentration of Mn4+ ions, the dependence of luminescence on temperature, and the decay pattern of the samples were investigated. In addition, the light emitting diode (LED) was prepared by the combination of a 365 nm chip and SSNO: Mn4+ phosphor, which can emit bright far-red light. Therefore, SSNO: Mn4+ phosphors are expected to be applied in field of indoor plant cultivation.

High-Efficiency Ce3+ Activated Orthorhombic Lanthanide Silicate Blue Phosphors for Plant Growth Lighting.

Plant growth can be controlled and freed from natural environmental interference through indoor plant cultivation. Artificial light sources with better quality are required to promote indoor plant growth. In this study, we used a simple high-temperature solid-state reaction to synthesize high-efficiency Ce3+-activated NaGdSiO4 (NGSO) phosphors. X-ray diffraction and Rietveld refinement were performed to determine the detailed crystal structure of the NGSO:Ce3+ phosphors. The morphology of NGSO:Ce3+ and the elemental state of Ce3+ were measured and analyzed. Under near-ultraviolet (n-UV) light excitation, the Ce3+-activated NGSO phosphors exhibit a broad emission band from 375 to 500 nm, and their emission peaks are at approximately 401 nm. This asymmetrical blue emission band is caused by the spin-allowed 5d → 4f transition of Ce3+ and overlaps well with the blue absorption region of carotenoids and chlorophyll. The temperature-dependent luminescence spectra were utilized to assess the thermal stability of NGSO:Ce3+. The external quantum efficiency (EQE) was measured to be 60.91%, and the internal quantum efficiency (IQE) was measured to be 73.39%. A blue LED device assembled from the NGSO:Ce3+ phosphor has demonstrated the application potential in accelerating plant growth.

Luminescence enhancement of Mn4+‐activated double‐perovskite phosphors for LEDs through a co‐replacement strategy

AbstractPhosphors doped with Mn4+ ions have strong emission in the red and far‐red light regions and are therefore used as red phosphors for indoor plant cultivation light‐emitting diodes (LEDs) and white LEDs (w‐LEDs). This paper introduces La2Mg(Mg1/3Ta2/3)O6: Mn4+ (Mg2La3TaO9: Mn4+) red phosphors prepared by conventional high‐temperature solid‐phase method. The broad excitation band of Mg2La3TaO9: Mn4+ phosphor is effectively excited by ultraviolet and blue light in the range of 250–600 nm, with the emission of 707 nm centered on far‐red light. The phosphor has a high color purity of 99.07% and an internal quantum efficiency of 59.87%. To further enhance the performance of the phosphor, a cation substitution method was adopted in this paper to synthesize La2Mg(Al1/2Ta1/2)O6: Mn4+ phosphor by replacing [1/3Mg2+–2/3Ta5+] in La2Mg(Mg1/3Ta2/3)O6: Mn4+ with [1/2Al3+–1/2Ta5+]. The luminescence intensity and thermal stability of the samples were enhanced. The emission spectrum of the Mg2La3TaO9: Mn4+ samples matched well with the phytochrome PFR (phytochrome that absorbs far‐red light) and is suitable for the preparation of LEDs for indoor plant cultivation. The concentration quenching effect of the samples was investigated, the main mechanism of which is the electric dipole–dipole interaction. Red LEDs and w‐LEDs devices were prepared with the synthesized phosphors that produce light stably at different currents. The w‐LEDs have a correlated color temperature of 5310 K and a color rendering index of 80.1. Therefore, these samples are expected to be used as red components for w‐LEDs.

Cu2+ and Cr3+ doped borate glasses and glass-ceramics as light conversion materials for plant photosynthesis

We present a kind of Cu2+/Cr3+ doped borate luminescence glasses and glass-ceramics for potential indoor plant cultivation applications. These materials were prepared using a melt-quenching route and their luminescent and structural properties were investigated. The Cu2+ in the as-obtained materials can generate blue emission under ultraviolet (UV) excitations. The Cr3+ ions doped glasses and glass-ceramics display two intense broadband absorptions located in the UV and green light regions, also exhibit the sharp-line 2E2→4A2 emission and the broadband 4T2→4A2 luminescence. These emissions originating from Cu2+ and Cr3+ have blue (peaking at ∼480 nm) and far-red-emitting components (∼690–780 nm), which play a promising role in regulating the photomorphogenesis of plants. For certain base glass compositions, the crystals ZrO2 were spontaneously precipitated during the melt quenching process and the glass-ceramics were obtained accordingly. The relative emission intensity, position of emission bands, and fluorescence decay kinetics of Cu/Cr doped borate glasses and glass-ceramics can be effectively modulated via a compositional design engineering and the variation of excitation wavelength. The excellent photoluminescence features make these glasses and glass-ceramics very promising for applications in plant growth light-emitting diodes (LEDs).

Flux induced highly efficient and stable phosphor Sr2ScSbO6:Mn4+ for plant growth lighting

Sr2ScSbO5.6F0.4:Mn4+ presents excellent thermal stability and higher internal/external quantum efficiency with application prospects in indoor plant cultivation.

Defect-induced deep red luminescence of CaGdAlO4-type layered perovskites: multi-cationic sites partial/full substitution and application in pc-LED and plant lighting.

A series of CaGdAlO4-type layered perovskite phosphors showing deep red luminescence (λem = 711 nm, λex = 338 nm) were synthesized via a solid-state reaction. A comprehensive analysis performed via photoluminescence, X-ray photoelectron spectroscopy, thermoluminescence, and fluorescence decay revealed that the deep red luminescence is related to oxygen defects and particularly oxygen interstitials. The defect-related luminescence was effectively regulated through partial substitution of multi-cationic sites (the Ca2+ site with Mg2+, Sr2+, and Ba2+; the Gd3+ site with La3+, Y3+, and Lu3+) and full substitution of Gd3+ with Y3+. Remarkably, a 383.3% stronger luminescence was obtained through partial substitution with Lu3+, and the quantum yield of luminescence reached 28.74%, which is higher than those values of most previously reported self-luminescent systems. A pc-LED device was fabricated using this phosphor, and the device was shown to have potential application in indoor plant cultivation.

A novel far-red phosphors Li2ZnTi3O8:Cr3+ for indoor plant cultivation:Synthesis and luminescence properties

A novel far-red phosphors Li2ZnTi3O8:Cr3+ were successfully synthesized via the conventional solid-state method. The structural characteristics, luminescence properties and concentration quenching of the Li2ZnTi3O8:Cr3+ phosphors were investigated systematically. Under the excitation at 360 nm and 468 nm, the Li2ZnTi3O8:Cr3+ phosphors displays the emission spectra in the range from 600 nm to 850 nm. The far-red emission centered at 735 nm was attributed to the spin-forbidden 2E→4A2 transition of Cr3+ ions. The research results of this paper indicate that the phosphors Li2ZnTi3O8:Cr3+ has prospective applications in indoor plant cultivation.

Novel far-red emitting phosphor Mn4+-activated BaLaLiWO6 with excellent performance for indoor plant cultivation of light-emitting diodes

The far-red oxide phosphors doped with Mn4+ ions are constantly investigated for plant cultivation of light-emitting diodes (LEDs) due to their emission bands matching well the absorption region of phytochromes in plants. Herein, a novel far-red emitting phosphor of BaLaLiWO6 (BLLW) doped with Mn4+ ions was successfully prepared for plant cultivation. The Rietveld-refined lattice parameters and surface micromorphology of the samples were investigated. The theoretical values of the energy gap for the perfect BLLW matrix were calculated by density functional theory and the experimental values obtained based on the absorption spectra were compared. In addition, the samples can be efficiently excited by ultraviolet and blue light, and emit intense far-red light with a central wavelength of 708 nm. Furthermore, the crystalline field effect and concentration quenching mechanism of Mn4+ ions in the BLLW matrix were explored. Satisfactorily, the internal quantum efficiency, color purity, and activation energy of the phosphor were as high as 48.38%, 99.6%, and 0.53 eV, respectively. Meanwhile, the effects of synthesis temperature and Ca2+ ions co-doping on the luminescence intensity of the samples were studied. Finally, the far-red LEDs devices were prepared for plant cultivation by combining the phosphor with 460 nm LEDs chips.

Deep-red emission in Mn4+ activated CaMgAl10O17 phosphor and enhanced optical photoluminescence by charge compensator of Mg2+

In this work, we synthesized a series of CaMgAl10O17:Mn4+, CaMgAl10O17:Mn4+, Mg2+ phosphor by sol-gel method and investigated their phase constituents, microstructure and photoluminescence properties in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), excitation and emission spectra (PLE & PL) and fluorescent lifetime measurements. Under 397 nm excitation, these doped Mn4+ phosphors exhibit intense deep-red emission at 655 nm, belonging to the 2Eg→4A2g transition of Mn4+. The optimal doping concentration of Mn4+ ions reached about 0.02, and co-doping Mg2+ could obviously improve the luminous performance and thermal stability. When the co-doping concentration of Mg2+ ions was about 0.04, the maximum emission intensity could be enhanced by 60%, and color purity is 94%. Lifetime of CaMgAl10O17:0.02Mn4+, 0.04Mg2+ phosphor is 1.052 ms. These results suggest that CaMgAl10O17:Mn4+, Mg2+ has promising application for indoor plant cultivation.

Greatly enhanced deep-red luminescence performance of Ca2InSbO6:Mn4+ phosphor via multiple optimization strategies

Phosphors with high luminescence intensity, thermal stability, and spectral matching are important for indoor plant cultivation (IPC) light-emitting diodes (LEDs). Mn4+ ion-doped phosphors are considered potential deep-red emitters for plant growth LEDs. Herein, Ca2InSbO6:Mn4+ (CISO:Mn4+) phosphors were first synthesized via high-temperature solid-phase method. Their luminescence performance was greatly enhanced by using three kinds of strategies (charge compensator, solid solution, and rare earth ion co-doping). Furthermore, the optimization mechanisms were studied in depth on the basis of the principle of charge compensation and reduced quenching centers. Surprisingly, the internal quantum efficiency of the Ca1·9Y0·1InSb0·6Ta0·4O6:0.006Mn4+ phosphor was greatly enhanced to 71.4%, which was 42.75 times that of the CISO:0.006Mn4+ phosphor. Under 373 nm excitation, the Ca1·9Y0·1InSb0·6Ta0·4O6:0.006Mn4+ phosphor showed intense deep-red emission at 695 nm attributed to the 2Eg→4A2g transition of Mn4+ ions, which indicated a good match with far red phytochrome (Pfr, 84%). Finally, the fabricated IPC-LED displayed superior spectral matching, color purity (99.9%), and CIE chromaticity coordinates (0.692, 0.308). Thus, it has great potential as deep-red substitutes in the field of IPC. This work adopted a series of comprehensive strategies to optimize the luminescence performance of Mn4+-doped oxide phosphors and discussed the optimization mechanisms in depth, aiming to provide new ideas for the future optimization of phosphors.

A thermal-stable Mn4+-doped far-red-emitting phosphor-converted LED for indoor plant cultivation

Artificial light-emitting diode (LED) light source, regarded as a front-runner technology for the promoting of plant growth, has attracted much attention toward the burgeoning fertilizer-free indoor plant cultivation. It still remains a challenge that explore a far-red-emitting phosphor of high-thermal stability. Overall, we report a Mn4+ ion-doped ordered double perovskite tungstates prepared by high-temperature solid-state reaction method in air. The crystal structure, morphology, and fluorescence properties were investigated and discussed in detail. The far-red emission of the optimized CaSrMgWO6:1%Mn4+, covering the wavelength region of 630–780 nm, matches the absorption ranges of the chlorophyll a and phytochrome (Pfr). The value of Dq/B is estimated to be 2.81. Most notable is the excellent thermal quenching resistance of the Mn4+ emission, remaining 86.7% at 150 °C, thereby suitably fabricating a far-red LED device. The LED light-driven regulation of the physiological and biochemical changes enables a proof-of-concept garlic cultivation. The growth of weight, stem length, and root length of the garlic was significantly promoted with the extra supply of the far-red light. This work demonstrates that the as-obtained far-red-emitting phosphor holds a promising perspective for the phosphor-converted far-red LED light sources toward the flourishing fertilizer-free indoor plant cultivation.