Orange-red Light Research Articles

Luminescence properties, tunable emission and energy transfer of Na3Sc2(PO4)3: Sm3+, Bi3+ phosphors

Na3Sc2(PO4)3:R (R = Bi3+, Sm3+, and Sm3+/Bi3+) are successfully synthesized in air atmosphere. The high-temperature solid-state reaction method is used in this work. The X-ray diffractometer patterns confirm that all samples have the single pure phase Na3Sc2(PO4)3. Na3Sc2(PO4)3:Bi3+ displays blue emission because of the Bi3+ - Sc3+ metal-to-metal charge-transfer and the 3P1 → 1S0 transition of Bi3+. Na3Sc2(PO4)3:Sm3+ shows red-orange emission with four emission bands derived from the 4G5/2 → 6H5/2 (550 - 582 nm), 6H7/2 (582–625 nm), 6H9/2 (625–675 nm), and 6H11/2 (675–750 nm) transitions of Sm3+. The optimal Sm3+ concentration in Na3Sc2(PO4)3:Sm3+ is ∼8mol%. An adjustable color emission from blue to red-orange of Na3Sc2(PO4)3:Sm3+, Bi3+ with excitation at 345 nm can be observed when the ratio between Sm3+ and Bi3+ ions is changed. Na3Sc2(PO4)3:Sm3+, Bi3+ emits red–orange light under excitation 406 nm. The optimal Bi3+ concentration in Na3Sc2(PO4)3:8mol%Sm3+, Bi3+ is ∼ 6mol%. The energy transfer from Bi3+ to Sm3+ in Na3Sc2(PO4)3:Sm3+, Bi3+ is verified by the spectral properties of samples. We discuss the influences of Bi3+ or Sm3+ concentration on luminescence properties of samples and analyze their luminous mechanism by energy level diagram. The experimental results of paper are useful for the research of new Bi3+ and Sm3+ doped phosphors.

Tunable red/ blue emitting of Ca5(PO4)3F: Eu2+, Eu3+ and remote-excited color convertor for NUV-WLED

Eu2+/Eu3+ co-doped Ca5(PO4)3F (FAP) phosphors with tunable color of red/blue (R/B) emission were successfully synthesized by the two-step method for potential applications in light-emitting diodes (LED). Eu2+ (or Eu3+) single-doped and Eu2+/Eu3+ co-doped FAP all showed pure hexagonal FAP crystal with space group P63/m, indicating the occupation of Ca sites by Eu2+ and Eu3+ ions. Typically, Ca5(PO4)3F: Eu2+ phosphors exhibited a broad blue emission band at 451 nm under 293 nm excitation and Ca5(PO4)3F: Eu3+ samples emitted strong orange-red light at 596 nm, 615 nm and 620 nm under 394 nm excitation. Further, Eu2+/Eu3+ co-doped FAP phosphors obtained by the two-step method depicted the blue emission at 451 nm (Eu2+ ions) and the orange-red emission (Eu3+ ions) at 596 nm, 615 nm and 620 nm with an excitation wavelength of 365 nm (NUV). The tunable R/B ratio from 0.079 to 7.035 with various CIE chromaticity coordinate can be achieved by adjusting the recalcined temperature in the second step. Ca5(PO4)3F: Eu2+, Eu3+ sample can be packaged with green Lu3Al5O12 (LuAG) phosphors by 365 nm chip (1 W) and the cold white light with CIE chromaticity coordinate (0.2815, 0.3485) (CRI: 73, CCT: 7973 K) is achieving. Based on Ca5(PO4)3F: Eu2+, Eu3+ and 25B2O3-10SiO2-35ZnO-6Li2O-12La2O3-12WO3 (BS-glass) (in mol%) with strong mechanical strength as a great binder, the remote-excited color convertor (PiG: phosphor in glass) has been fabricated by screen printing technology for NUV-WLED application. Finally, by comparing the working temperature of PiG and pc-WLED at the same operating time, the working temperature of PiG was stable at 32 °C when remote excitation lighting was applied, which greatly avoided the phenomenon of “thermal quenching” for phosphors caused by high temperature under the operating of WLED. Thus, it was demonstrated that Eu2+ and Eu3+ co-doped Ca5(PO4)3F phosphors with tunable red/blue emitting would be a highly potential candidate for NUV-WLED.

Enhanced the luminescent performance of CsPbI3 quantum dot-embedded borosilicate glass by controlling crystallization using Dy3+ ions as nucleating agent for remote color-tunable LEDs

Different concentrations of Dy3+ and perovskite quantum dots (PQDs) were simultaneously embedded in the B-Si-Zn glasses by melt-quenching and heat-treatment subsequently. A battery of experimental results including TEM, distribution of different elements, and photoluminescence prove that partial Dy ions are successfully doped into CsPbI3 and played different roles depending on the doping concentration. When the Dy3+ concentration is circa 0.1mol%, Dy3+ as a nucleation agent reduces the energy required for the precipitation and growth of perovskite quantum dots, obtaining outstanding quantum efficiency of 31.82%. The excess Dy3+ supplement will prevent the mobility of PQDs elements. Based on the as-made glass sample, the remote fluorescent films have been successfully prepared. A kind of prototype lighting device was assembled, which demonstrated a high color rendering index of 96.5 under the current of 20 mA. Interestingly, by adjusting the concentration of Dy3+, color regulation can be achieved from orange-red light to yellow-white light.

Photoluminescence properties of novel blue-light excited orange-red phosphors Sr3Al2Si3O12:Eu2+

Developing red phosphors for LEDs is highly demanded yet challenging. Herein, a novel Eu2+-activated orange-red phosphors Sr3-xAl2Si3O12:xEu2+ (SASO:xEu2+) (0 ≤ x ≤ 0.08, ∆x = 0.01) were successfully prepared by high-temperature solid-phase reaction. The phosphors all belong to the cubic crystal system, and the space group is Fm-3 m(225). Phosphors SASO:xEu2+ can be efficiently excited by wavelengths in the range of 420–500 nm and produces strong orange-red light emission at 618 nm. In phosphors SASO:xEu2+, the optimal doping concentration of Eu2+ is 0.06, and the Inokuti–Hirayama (I-H) model shows that the energy transfer between Eu2+ ions is mainly due to the dipole-dipole (d-d) interaction. The phosphors SASO:xEu2+ have excellent thermal stability, the fluorescence intensity of phosphor SASO:0.06Eu2+ at 418 K still maintains 69.57 % of the fluorescence intensity at room temperature. Phosphor SASO:0.06Eu2+ has a high luminescence quality with a color purity of 86.5 %, which exhibits bright orange-red emission under 450 nm illumination.

Designing orange-red emitting luminescent platform for data security and information encryption based Sm3+ doped BLAO phosphor

Due to the features of great difference and invariability, latent fingerprint (LFP) and lip print (LP) detection has grown to be a vital part of criminal investigation. Due to its environmental friendliness, powder dusting is now the method of choice for visualizing LFPs. The uses of this technology are severely constrained by essential flaws like limited resolution, low sensitivity, and high background interference. To address these issues, a novel orange red emitting BaLaAlO4:Sm3+ (1–5 mol %) (BLAO:Sm) phosphor has been fabricated via solution combustion route. The 4G5/2 → 6H7/2 transition of Sm3+ ions caused the phosphor to generate intense orange-red light at 601 nm under stimulation at 402 nm. The optimal Sm3+ concentration in BLAO is 2 mol % (BLAO:2Sm). The International Commission on Illumination evaluated the colour coordinates (CC), correlated colour temperature (CCT), and colour purity (CP) values based on the photoluminescence emission (PLE) profiles. The acquired CC and the typical National Television System Committee (NTSC) coordinates are compared. Additionally, the usefulness of the phosphor is assessed for the powder dusting technique to detect fingerprints (FPs) on various surfaces. The level 1–3 structure of LFPs and the distinct features of lip prints (LPs) are clearly visible utilizing the BLAO:2Sm phosphor under 402 nm, UV illumination. Fluorescent phosphor is fabricated with the necessary thickening agent in order to create AC inks that mark on various surfaces with high resolution without spreading and tracing. When exposed to UV light, the above ink's drawn design instantly developed and is illuminated with vivid orange red fluorescence emission. The results revealed that the optimized phosphor can garner significant interest for use in personal identification, and security encoding.

Deep blue, cyan, orange-red, and white multicolor emissions generated by Bi3+/Eu3+ activated KBaYSi2O7 luminescent materials for white light-emitting diodes

A variety of Bi3+ and/or Eu3+ doped KBaYSi2O7 phosphors with deep blue, cyan, orange-red, and white light multicolor emissions have been fabricated by a Pechini sol-gel (PSG) method. The KBaYSi2O7:Bi3+ phosphors exhibit an intense cyan emission or a unique narrow deep blue emission when excited by different wavelengths, which may bridge the cyan gap or act as a promising deep blue phosphor for white light-emitting diodes (WLEDs). The tunable multicolor emissions can be achieved by changing the Bi3+ doping concentrations. The Bi3+/Eu3+ co-doped KBaYSi2O7 phosphors display intrinsic emissions of Bi3+ and Eu3+ and an energy transfer process between Bi3+ and Eu3+ can be detected. The luminescence colors of KBaYSi2O7:Bi3+,Eu3+ regularly shift from blue, through cold and warm white, finally toward orange-red by adjusting the relative doping concentrations of Bi3+ and Eu3+. The single-phase white light-emitting material can be generated in both cold and warm white regions by simply varying the Eu3+ doping concentrations. Furthermore, three kinds of WLEDs devices are fabricated by KBaYSi2O7:Bi3+ or KBaYSi2O7:Bi3+,Eu3+ phosphors, which can exhibit dazzling white light emissions with eminent CIE coordinates, correlated color temperature, and color rendering index. The result offers direct evidence that the as-synthesized phosphors may be potentially applied in WLEDs and solid-state lighting.

Structure, Judd-Ofelt analysis and spectra studies of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg, Ca, Sr, Ba) glasses for reddish-orange light application

In the present work, a series of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg, Ca, Sr, Ba) glasses were prepared. The glass structure and luminescence properties were investigated by XRD, DSC, IR, absorption spectroscopy, Judd-Ofelt theory and photoluminescence spectra. The J-O parameters of Sm3+-doped glasses follow the trend of Ω4＞Ω6＞Ω2. Under the excitation of 401 nm Xenon lamp, Sm3+-doped glasses exhibited four emissions from the transitions of 4G5/2→6HJ/2 (J = 5, 7, 9, 11) in the visible spectra. The luminous intensity of Sm3+ increases with the asymmetry in local environments and decreases with the increasing radius of the alkaline-earth cation. Among the as-prepared glass, the Sm3+-doped glass containing magnesium oxide exhibits higher values of stimulated emission cross-section (2.18 × 10−21 cm2), gain bandwidth (1.40 × 10−27 cm3), and optical gain (3.83 × 10−24 cm2). All the Sm3+-doped glasses show intense orange light in the CIE 1931 chromaticity diagram with a high color purity exceeding 99%. In addition, the time-resolved emission spectra reveal the decay process of the Sm3+ ions for the transitions 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 in the glass containing magnesium oxide. It suggests that Sm3+-doped alkaline-earth zinc borophosphate glasses could be a potential candidate for reddish-orange light-conversion fluorescent materials based on the ultraviolet light-emitting diode.

A new peroxyoxalate chemiluminescence of bis (2, 4-dinitrophenyl) oxalate (DNPO) using pyronin Y as the fluorophore and its application to the flow-based determination of cysteamine

Peroxyoxalate chemiluminescence (POCL) systems have received great attention due to their high quantum yield and the ability to emit a wide-range colors by the utilizing different fluorophores. In this research, Pyronin Y (PY) was first introduced as the fluorophore for a POCL system. Our results indicated that the reaction of (2, 4-dinitroophenyl) oxalate (DNPO) with hydrogen peroxide (H2O2) catalyzed by sodium salicylate (SS) could transfer energy to Pyronin Y via the formation of the dioxetanedione intermediate and emit orange-red light. The relationships between chemiluminescence (CL) intensity and the concentrations of DNPO, fluorophore, H2O2, and the catalyst were investigated. Moreover, the analytical utilization of the new CL system was evaluated by detecting a drug, cysteamine, in pharmaceuticals. A linear working range for cysteamine concentrations from 3 × 10 −8 to 7.5 × 10 −6 molL−1 (r > 0.9907, n = 5) and a detection limit of 7.8 × 10−9 molL−1 were obtained, respectively. The relative standard deviation for five repetitive determinations was less than 3.8 %, with estimated recoveries of 100.1 % and 103.4 %. This method shows high sensitivity for the assay of cysteamine.

Influence of Rare Earth Ions (REIs) on the Visible Emission of Magnesium Sodium Borate Glasses

Borate glass systems have been extensively studied for practical applications in optical display devices by virtue of their peculiar luminescence efficiency. However, the attainment of high emission from borate glass materials via apposite control of rare earth ions (REIs) contents remains a topical issue in Material Physics. In this paper, we report the influence of REIs (Dy3+, Eu3+, and Sm3+) on multiple-colour emission of magnesium sodium borate (MSB) glasses fabricated by using the conventional melt-quenching method. These glasses were optically characterized via X-ray Diffraction (XRD), UV-VIS-NIR and Photoluminescence techniques. The XRD pattern confirms the amorphous nature of the as-prepared glasses. The absorption spectra disclosed several absorption bands at 347 nm (6H15/2 → 6P7/2) for Dy3+, 393 nm (7F0 →5L6) for Eu3+ and 403 nm (6H5/2 →6P5/2) assigned for Sm3+ respectively. Also, the emission spectra radiate at 463 nm (4F9/2 → 6F11/2 + 6H9/2), 612 nm (5D0 → 7FJ) and 599 nm (4G5/2 → 6H7/2) for Dy3+, Eu3+, and Sm3+ correspondingly, wherein Dy3+ emits blue, yellow, and red light, Eu3+ emits red light and Sm3+ emits reddish-orange light. Finally, 1.0 mol% content of Dy3+, Eu3+, and Sm3+ in MSB glasses was found to be optimal and hence considered the best optical host for colour display devices.

Intense photoluminescence in CaTiO3:Sm3+ phosphors, effect of co-doping singly, doubly and triply ionized elements and their applications in LEDs.

In this work, Sm3+-doped and Sm3+/Li+/K+/Mg2+/Ba2+/Gd3+/Bi3+ co-doped CaTiO3 phosphors were synthesized by a solid-state reaction method at 1473 K. The phase of phosphors was identified to be orthorhombic with space group Pnma (62) by XRD measurements. The morphological properties of the prepared samples were studied by SEM measurements. The average crystallite and particle sizes were found to increase in the presence of modifiers and they follow the trend Li+ > Mg2+ > Gd3+ > K+ > Bi3+ > Ba2+. EDX measurements were used to verify the presence of Ca, Ti, O, Sm, K, Mg, Ba, Gd and Bi atoms in the prepared phosphor samples. The Sm3+ ion shows emission peaks at 564, 599 and 646 nm due to 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 transitions upon 407 nm excitation, among which the peak situated at 599 nm has maximum emission intensity. Concentration quenching was observed above 2 mol% of Sm3+ ions in this host. However, the emission intensity of Sm3+ peaks can be enhanced using different modifier (Li+/K+/Mg2+/Ba2+/Gd3+/Bi3+) ions. It was found that the size (ionic radii) and charge compensation of the ion together play a dominant role. The enhancement is more after co-doping with smaller radius ions (Li+, Mg2+ and Gd3+), among which Li+ shows the largest enhancement. This is because ions of smaller size will be able to go closer to the activator ion and the charge imbalance causes a larger field. The CIE color coordinates, correlated color temperature (CCT) and color purity of the phosphors were calculated and show orange-red color emissions with a maximum color purity of ∼93% in the case of CaTiO3:2Sm3+/1.0Li+ phosphor. The lifetime value is increased in the presence of these ions. It is again maximum for the Li+ co-doped CaTiO3:2Sm3+ phosphor sample. Thus, the prepared phosphor samples are suitable sources for orange-red light.

Gadolinium-based Sm3+ activated GdSr2AlO5 nanophosphor: synthesis, crystallographic and opto-electronic analysis for warm wLEDs.

A material's luminosity characteristics, which in turn dictate its applicability, are critically influenced by its structure. Therefore, it is essential for design and fabrication of optical nanocrystalline materials to comprehend the relationship between structural and luminescence properties. The gel-combustion approach was used to produce a sequence of orange-red light emanating GdSr2AlO5:Sm3+ (GSA:Sm3+) nanophosphors which are used for warm white-light-emitting diodes (w-LEDs). Comprehensive investigation of the structural and optical characteristics of GdSr2AlO5:Sm3+ nanophosphors has been done in a detailed manner. The synthesized powdered nanophosphors are crystallized in a tetragonal phase with I4/mcm (140) space group, affirmed through Rietveld refining method. The nano size with an aggregated, spherical form of the particles in the powdered nanocrystalline material was revealed by TEM analysis. These orange-red emitting phosphors Gd1-x Sr2AlO5:xSm3+ (x = 1-7 mol%) were shown to possess photoluminosity (PL) properties that demonstrated the presence of most intense emission peaks at 603 nm that were caused by 4G5/2 → 6H7/2 transitions of the Sm3+ ion under 273 nm excitation. Considering its long decay lifespan and PL emission, it can be concluded that the GdSr2AlO5:Sm3+ phosphor is a potential single element for the fabrication of warm white light-emitting devices.

Copolymers of 4-Trimethylsilyl Diphenyl Acetylene and 1-Trimethylsilyl-1-Propyne: Polymer Synthesis and Luminescent Property Adjustment

Poly(4-trimethylsilyl diphenyl acetylene) (PTMSDPA) has strong fluorescence emission, but its application is limited by the effect of aggregation-caused quenching (ACQ). Copolymerization is a commonly used method to adjust the properties of polymers. Through the copolymerization of 4-trimethylsilyl diphenyl acetylene and 1-trimethylsilyl-1-propyne (TMSP), we successfully realized the conversion of PTMSDPA from ACQ to aggregation-induced emission (AIE) and aggregation-induced emission enhancement (AEE). By controlling the monomer feeding ratio and with the increase of the content of TMSDPA inserted into the copolymer, the emission peak was red-shifted, and a series of copolymers of poly(TMSDPA-co-TMSP) that emit blue-purple to orange-red light was obtained, and the feasibility of the application in explosive detection was verified. With picric acid (PA) as a model explosive, a super-quenching process has been observed, and the quenching constant (KSV) calculated from the Stern-Volmer equation is 24,000 M-1, which means that the polymer is potentially used for explosive detection.

Structural and luminescent characteristics of orthorhombic GdAlO3:Sm3+ nanocrystalline materials for solid state lighting

In the current article, an eco-friendly, efficient and less energy consuming gel-combustion process has been used to develop a series of perovskite based Gd1-xAlO3:xSm3+ (x = 0.01, 0.03, 0.05, 0.07 and 0.09 mol) nanomaterials which produce reddish orange light. According to crystallographic investigation, the synthesized nanocrystalline materials belong to orthorhombic crystal symmetry having space group Pnma (62). The non-uniform agglomerated particles in nano range (35–45 nm) were examined via TEM analysis, which supports the results obtained from XRD analysis. The PL spectra involve 4f-transitions of trivalent samarium ions, such as 4G5/2→ 6H5/2 (565 nm), 4G5/2→ 6H7/2 (601 nm) and 4G5/2 → 6H9/2 (647 nm). The energy transferal mechanism between neighbouring trivalent samarium ions is dipole–dipole (DD) interaction, which is answerable for the quenching of luminous intensity. Additionally, colorimetric characteristics like color coordinates, color-purity and correlated-color temperature were obtained using PL data. These photometric parameters were strongly recommends these synthesized nanophosphors samples for solid state lighting applications.

Preparation and luminescence properties of Ba3P4O13:Sm3+ orange-red phosphors with high thermal stability

In this work, a series of Ba3P4O13:Sm3+ phosphors are prepared via calcining the precursor synthesized by a chemical co-precipitation method, meanwhile, the phase and fluorescence properties are characterized as required. The results demonstrate that the phosphors emit orange-red light with several emission peaks centering at 564 nm, 600 nm and 648 nm under ultraviolet (UV) excitation, which originate from the transition of 4G5/2 to 6H5/2 (or 6H7/2,6H9/2) energy level in Sm3+. Among them, Ba2.98P4O13:0.02Sm3+ phosphor exhibit the strongest emission intensity, and then concentration quenching occurs due to the d-d interaction once the concentration of Sm3+ ions exceeded 0.02. Even so, the color coordinates of all BaP4O13:Sm3+ samples are calculated to be close to (0.58, 0.41), implying a high color purity. Significantly, the charge compensation of alkali metal ions, especially for K+ ion, enhances the emission intensity, thermal stability and fluorescence lifetime of the phosphors remarkably, even zero thermal quenching is observed in the range of 25–250 °C.

Synthesis, photoluminescent properties, and an insight into the Judd-Ofelt analysis of the NaPbBi(2-x)(PO4)3: xEu3+ orthophosphate phosphors for light applications

A set of novel reddish orange light emitting NaPbBi2(PO4)3: xEu3+ (hereafter referred to as NPbBP) phosphate phosphors were synthesized by the conventional solid state reaction route. The phase formation, particle morphology, elemental composition and the optical properties of the prepared phosphors were studied in detail from the powder XRD data, SEM images, EDS analysis, and the diffuse reflectance spectroscopy measurements respectively. The photoluminescence properties were systematically studied by recording the excitation and emission spectra of the prepared phosphors. The NPbBP: xEu3+ phosphors, excited at the near ultraviolet light, exhibited the reddish orange light emission in the visible region due to the dominance of magnetic dipole transition of the Eu3+ ions in the host. The details of the radiative properties were analyzed through the Judd- Ofelt intensity parameters, which were found to follow the trend of Ω2< Ω4. The thermal stability and the life time of the phosphors were investigated. The calculated photometric parameters of the NPbBP: 0.09Eu3+ phosphor suggested that the emission was found in the reddish-orange region with a high color purity and high quantum yield of 99.53% and 79.7% respectively. These results showed that the NPbBP: Eu3+ phosphor could serve as a good phosphor for use in various optoelectronic devices such as phosphor converted WLEDs, solar cells, and display panels.

Preparation and photoluminescence performance of BaMoO4:Sm3+ orange–red phosphor

In the present paper, orange–red BaMoO4:Sm3+ phosphor was synthesized by high-temperature solid-phase method. The morphology, elemental composition, crystal structure, photoluminescence performance, and charge compensation mechanism of BaMoO4:Sm3+ were investigated. Results indicated that the BaMoO4:Sm3+ phosphor particles were spherical-like in shape with approximate particle size of 2 μm and contained Ba, Mo, O, and Sm elements. The Rietveld-refinement of X-ray diffraction profile of BaMoO4:Sm3+ was consistent with a tetragonal lattice. Under 404 nm excitation of light, BaMoO4:Sm3+ phosphor showed the strongest emission peak at 649 nm and emitted an orange–red light. When the orange–red phosphor was packaged with a 395 nm UV chip and tested, the color coordinates were (0.3109, 0.3626) under a current of 60 mA, the color rendering index Ra = 81.5, and the color temperature was 6385 K. These results indicated that BaMoO4:Sm3+ red phosphor is suitable as a red light component in WLEDs and has potential practical applications.

Synthesis, adjustable-color emission and energy transfer of Ba2MgSi2O7:Sm3+, Bi3+ phosphors

Ba2MgSi2O7:M (M = Bi3+, Sm3+, Sm3+/Bi3+) phosphors are synthesized in air by the high-temperature solid-state reaction method. All samples are confirmed to be a pure phase. With a 316 nm excitation wavelength, Ba2MgSi2O7:Bi3+ shows blue-white emission including a broad emission band in the range of 340 - 750 nm, and Ba2MgSi2O7:Sm3+, Bi3+ emits a adjustable-color light with the change of the ratio of Sm3+ to Bi3+ ions. Under excited at 402 nm, Ba2MgSi2O7:Sm3+ and Ba2MgSi2O7:Sm3+, Bi3+ emit orange-red light with emission spectrum region from 545 nm to 750 nm, which contain four emission bands peaking at ∼560, 598, 646 and 704 nm due to the 4G5/2 → 6H5/2, 6H7/2, 6H9/2, and 6H11/2 transitions of Sm3+ ion, respectively. Ba2MgSi2O7:Sm3+, Bi3+ under excitation at 316 nm can show a white-color emission by changing the ratio between Sm3+ and Bi3+ ions. Lifetimes of samples decrease with increasing doped ion (Sm3+ or Bi3+) concentration. We explain the luminous mechanism of samples by the schematic energy level diagrams of Bi3+ and Sm3+ ions in Ba2MgSi2O7:Sm3+, Bi3+.

Effects of Light Conversion Film on the Growth of Leafy Vegetables in Facilities under Haze Weather

The light intensity is low in haze weather, and the facility is in a weak light environment for a long time. As a functional film, light conversion film (LCF) can improve the light conversion performance and is conducive to regulating the environment in the facility to promote crop growth. It can be seen from the test that the light transmittance of LCF under visible light conditions (400–780 nm) is 8.67% higher than that of ordinary film (OF), with stronger light transmittance. In the red–orange light band (600–700 nm), the LCF is 1.3% higher than that of the OF. Through the detection of irradiance, it was found that the irradiance was outdoor environment &gt; LCF &gt; OF in any weather. A two-year greenhouse experiment was conducted to study the effect of LCF on the whole growth process of facility agriculture (environment-soil-crop) under weak light. It is found that LCF reduces the air humidity by 0.47~2.83%; it has an obvious warming effect on the surface soil of greenhouse, and it is linearly correlated with temperature. In terms of crop growth, LCF significantly (p &lt; 0.05) increased the photosynthetic rate at heading stage, and finally increased the yield, total soluble sugar and reduction-type Vitamin C by 8.97–39.53%, 9.22–30.14%, and 1.41–21.09%, respectively. In addition, considering the frequent haze weather in North China, the use of LCF can improve air temperature, CO2 concentration, photosynthetically active radiation (PAR), and soil temperature, and it can effectively deal with the challenge of weak light. In conclusion, LCF can improve the facility environment and improve crop yield and quality, indicating that the implementation of LCF has potential benefits in solving crop yield reduction and quality decline in haze weather. In addition, as the main component of LCF, rare earth materials are a new type of clean energy, which can effectively promote the sustainable development of the agricultural ecosystem.

Structural and luminescence characterization of thermally stable orange-red emitting LiSrP3O9:Sm3+ phosphor to fill the amber gap in WLEDs

Orange-red light emitting LiSr(1-x)P3O9:xSm3+ phosphors were successfully prepared by the Solution combustion method. The Powder X-ray Diffraction analysis confirmed a single phase for the samples with a crystallite size ranging from 66 ± 0.9 nm to 72 ± 0.5 nm. The photoluminescence (PL) spectra revealed that at 398 nm excitation, the LiSrP3O9:Sm3+ phosphors could be easily excited and displayed a bright orange-red emission which attributes to 4G5/2 → 6H7/2 transition of dopant (Sm3+) ion. At 398 nm excitation, the optimum PL intensity was obtained for the 2 mol% Sm3+ ion-doped sample. The lifetime decay measurements showed that the lifespan decreased steadily from 3.48311 to 2.98869 ms with an increase in the Sm3+ ion concentration. Commission International de l'Eclairage coordinates (0.58, 0.42), which correspond to a strong orange red emission situated in the amber gap, colour purity (97.73%), and colour correlated temperature (1666 K) demonstrated excellent luminescent performance. To assess the thermal stability of the phosphor, the thermal quenching behavior of its PL emission was investigated. These results indicate that the LiSrP3O9:Sm3+ phosphor might be a viable option for filling the amber gap in light-emitting diodes.

Abnormal thermal quenching and optical performance of new niobate perovskite Sr3LaNb3O12:Sm3+ phosphors for w-LEDs

Novel orange-red Sr3LaNb3O12 (SLNO):xSm3+ (0.01 ≤ x ≤ 0.03) phosphors are successfully prepared using the traditional solid-state method. The feasibility that the SLNO compounds can act as an appropriate host has been effectively demonstrated by unit cell structure and bandgap structure. The phase purity, particle size distribution, and elemental composition of SLNO:Sm3+ phosphors are studied. The luminescence properties, concentration-quenching mechanism, color purity, thermostability, CIE chromaticity coordinates, and correlated color temperature (CCT) of the obtained SLNO:Sm3+ products are also discussed. Under 408 nm excitation, SLNO:0.10Sm3+ sample emits a bright orange-red light at 598 nm owing to the 4G5/2 to 6H7/2 transition of Sm3+. The concentration-quenching mechanism is found to be dipole-dipole interaction by the calculated Rc value (17.12 Å) and Dexter's theory. Impressively, the color purity of the phosphors is high and stable (all reach 99.9%), which is rarely affected by the Sm3+ doping concentration. It is worth noting that the obtained phosphors exhibit an abnormal thermal quenching (ATQ) behavior, increasing by 16.12% from 300 to 380 K (SLNO:0.10Sm3+). The CIE x and y chromaticity coordinates vary slightly with the change of temperature, indicating a good thermostability. The mechanism of ATQ has been studied as the lattice defects, and the thermal activation energy is calculated to be 0.51 eV. Ultimately, a white-light-emitting diode (w-LED) with a high color rendering index (Ra) of 88 and a CIE chromaticity coordinate of (0.333, 0.333) has been prepared. The results above reveal the potential of SLNO:Sm3+ to be widely used in w-LEDs.