Phosphors For Lighting Research Articles

Synthesis and photoluminescence properties of reddish-orange Li6ALa2Sb2O12:Sm3+ (A = Ca and Sr) garnet phosphors

Single-cubic-phase garnet phosphors of the trivalent samarium (Sm3+)-doped Li6CaLa2Sb2O12 and Li6SrLa2Sb2O12 matrices were investigated with respect to their crystal structure, morphology, and photoluminescence properties. The concentration quenching mechanism dominated by the dipole-dipole interaction determined the 5 mol% Sm3+ as the optimal doping concentration for the Li6ALa2Sb2O12:Sm3+ (A = Ca and Sr) garnet phosphors. As such, the performance comparison was carried out between Li6CaLa2Sb2O12:0.05Sm3+ and Li6SrLa2Sb2O12:0.05Sm3+ garnet phosphors in terms of various aspects (e.g., photoluminescence emission intensity, color purity, thermal stability, photoluminescence quantum yield, and decay curve). Particularly, the emission intensity of the Li6SrLa2Sb2O12:0.05Sm3+ was stronger than the Li6CaLa2Sb2O12:0.05Sm3+ phosphor. Interestingly, both Li6SrLa2Sb2O12:0.05Sm3+ and Li6CaLa2Sb2O12:0.05Sm3+ garnet phosphors exhibited beneficial thermal stability of 67.72 % and 61.67 % at 423 K, respectively. Overall, it is the first report to study and compare the photoluminescence performances of the reddish-orange Li6ALa2Sb2O12:Sm3+ (A = Ca and Sr) garnet phosphors. The findings of this work aim to design a thermal-stable garnet phosphor for potential solid-state lighting.

Ruddlesden-Popper type Sr(La,Gd)2Al2O7:Cr3+ layered perovskite new phosphors for NIR pc-LED application

Near-infrared phosphor converted light-emitting diodes (NIR pc-LEDs), as a state-of-the-art type of NIR sources, are finding multifaceted applications, where phosphor is a crucial component. In hope to provide new choices for NIR lighting, we synthesized in this work the two series of Ruddlesden -Popper type layered perovskite phosphors of SrLa2Al2-xO7:xCr3+ (x = 0–0.02) and SrLa2-yGdyAl1.984O7:0.016Cr3+ (y = 0–2), followed by detailed structure and luminescence investigation. SrLa2Al2-xO7:xCr3+ was found to emit ∼700–800 nm NIR light under UV excitation and be able to maintain ∼54.3 % of its room temperature intensity at 423 K, which is remarkably higher than those (∼25–30 %@423 K) of the Mn4+ activated perovskite NIR phosphors. Luminescence regulation was achieved by substituting La3+ with Gd3+, and it was revealed that Gd3+ may act as a sensitizer to significantly enhance Cr3+ luminescence (∼346 % at 77 K) through Gd3+ → Cr3+ energy transfer, which was confirmed by spectral and fluorescence lifetime analysis. The observed spectral features and the influence of Gd3+ were rationalized by considering crystal structure, local coordination, and crystal field. Finally, an NIR pc-LED device showing strong ∼700–900 nm luminescence was fabricated to show potential application of the phosphor in night vision and plant lighting.

Enhanced luminescence of Eu3+ in LaAl2B4O10 via energy transfer from Dy3+ doping

In this study, an investigation was conducted on the structural and photoluminescence (PL) characteristics of LaAl2B4O10 (LAB) phosphors initially incorporated with Dy3+ and Eu3+ ions. Subsequently, the impact of varying Eu3+ concentration while maintaining a constant Dy3+ concentration was examined. Structural characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis confirmed the effective embedding of both dopants into the hexagonal framework of the LAB. The PL emission spectra revealed characteristic emissions of Dy3+ (blue and yellow) and Eu3+ (red) ions. The optimized dopant concentrations of both Dy3+ and Eu3+ were observed to be 3 wt%. The dominant mechanism for concentration quenching in doped LAB phosphors was determined to be the electric dipole–dipole interaction. Co-doping with Eu3+ led to a substantial decrease in Dy3+ emission intensity (∼0.18-fold) while enhancing Eu3+ emission intensity (∼3.72-fold). The critical energy transfer distance (RC = 11.64 Å) and the analysis based on the Dexter theory confirmed that the energy transfer mechanism corresponds to dipole–dipole interaction. The color purities and correlated color temperatures (CCT) were estimated, suggesting the potential of these phosphors for warm white and red lighting applications, respectively. The observed energy transfer and luminescence properties, along with the structural and compositional characterization, highlight the promising potential of LAB:Dy3+/Eu3+ co-doped phosphors for advanced lighting and display technologies.

Red-emitting Mn4+-doped Li2MgSn2O6 phosphors for plant growth LED lighting

In this study, a novel red-emitting Mn4+ doped Li2MgSn2O6 (Li2MgSn2O6:Mn4+) phosphors were successfully synthesized using a simple solid-state reaction method. XRD patterns indicated the replacement of Mn4+ ions with Sn4+ ions in the [SnO6] octahedrons site of the Li2MgSn2O6 lattice, and XPS spectra confirmed the Mn4+ oxidation state. Excited at 323 nm and 480 nm, the phosphors exhibited a strong red emission band peaking at 659 nm, attributed to the 2E → 4A2 transition of Mn4+ ions. Notably, the highest PL intensity was found in the Li2MgSn2O6:0.3%Mn4+ sample annealed at 1000 °C. These phosphors, with a particle size of 1.0 μm, possess a long lifetime of 0.176 ms, high activation energy of 0.335 eV, excellent color purity of 99.9%, and good internal and external quantum efficiency of 44.5% and 24.1%, respectively. Furthermore, an LED coated with Li2MgSn2O6:0.3%Mn4+ phosphor on a 365 nm NUV LED chip showed strong emission matching the absorption spectrum of the red phytochrome. Therefore, these results indicated that the synthesized Li2MgSn2O6:Mn4+ phosphors could be used as red-emitting materials for plant growth LED applications.

Green-Emitting Perovskite BaTiO3:Ho3+ Phosphors for Solid-State Lighting

Green-Emitting Perovskite BaTiO3:Ho3+ Phosphors for Solid-State Lighting

Green Emission in Thermally Stable Er3+ Doped Lead-Free Perovskite Phosphor for Solid-State Lighting and Optical Thermometry Applications

Green Emission in Thermally Stable Er³⁺ Doped Lead-Free Perovskite Phosphor for Solid-State Lighting and Optical Thermometry Applications

Bi3+/Mn4+ co-doped Y2MgTiO6 dual-emitting phosphors for plant growth lighting and temperature sensor

Novel Bi3+/Mn4+ co-doped Y2MgTiO6 dual-emitting phosphors were synthesized using a high-temperature solid-phase method. The crystal structure and luminescence properties of phosphors were systematically investigated by experimental characterization and theoretical calculation. Under excitation at 375 nm, Y2MgTiO6:Bi3+, Mn4+ phosphors exhibit two emission bands located at 410 nm and 696 nm (blue and red), which can well be matched with the absorption bands of chlorophylls a, b and phytochrome. The Y2MgTiO6: Bi3+, Mn4+ luminescence remains at 66.2 % intensity at 423 K and quantum yield is 52.06 %. Optical temperature properties of Y2MgTiO6:Bi3+, Mn4+ were investigated using fluorescence intensity ratio (FIR) analysis and were found to reach a maximum relative sensitivity of 2.93 % K−1 at 498 K. The study suggests that this material could be a potential option for indoor plant culture and optical temperature sensing.

Studies on structural, photo and thermoluminescence properties of Sm3+ activated Ca3MgSi2O8 phosphors for solid-state lighting

Studies on structural, photo and thermoluminescence properties of Sm3+ activated Ca3MgSi2O8 phosphors for solid-state lighting

Tailoring high purity orange-red emission in Sm3+ activated SrTi(PO4)2 phosphor for lighting and display devices

An anhydrous double monophosphate, SrTi(PO4)2, was utilized as a host for RE-incorporated phosphor material for the first time. A series of orange-red emitting, Sm3+ doped SrTi(PO4)2 are synthesized by employing high-temperature solid-state reaction method. The structural, optical, luminescent and spectroscopic characteristics are extensively studied using XRD, FTIR, FE-SEM, DRS, PL spectroscopy and JO theory. The sample crystallizes in a monoclinic system with space group C2/m, having a loosely packed bubbly structure in the sub-micrometre range. PL emission spectra reveal the highly pure orange-red emission which can be effectively excited by n-UV radiation. The optimum Sm3+ ion concentration is 0.05 mol and the Dexter theory explains the luminous intensity quenching at higher concentrations as the energy transfer via dipole-dipole interaction. The longer radiative lifetime in the 2 ms range and the excellent color purity make the prepared Sm3+ doped SrTi(PO4)2 an orange-red emitting phosphor for lighting, sensing and display devices.

Efficient and tunable white light emitting from Sb3+, Tb3+, and Sm3+ Co-doped Cs2NaInCl6 double perovskite via multiple energy transfer processes

Inorganic lead-free double perovskites have the advantages of low toxicity, broadband emission, and good stability, which make them promising luminescent materials for lighting applications. However, due to the limited regulation of their self-trapped exciton emission, it is still greatly challenging to achieve white light emitting from a single double perovskite host. Herein, efficient and tunable white light is realized in Cs2NaInCl6: Sb3+, Tb3+, Sm3+ double perovskite by controlling the ratios of the doped three ions with blue, green, and red emissions, respectively. The steady-state and transient fluorescence spectra of singly- and doubly-doped double perovskites reveal the existence of multiple energy transfer channels in the triply-doped phosphors, including from Sb3+ to Tb3+, Sb3+ to Sm3+, and Tb3+ to Sm3+. Benefiting from these channels, the color coordinates of the triply-doped phosphors can cross the whole white light area of the CIE chromaticity diagram by adjusting the ratios of the three dopants, and the maximum internal quantum yield of the white light phosphors is 66.61 %. The white emission phosphors show the characteristic of being independent of excitation wavelength within 310–360 nm. Furthermore, the emission intensity at 430 K of the white light phosphor Cs2NaInCl6: 0.01Sb3+, 0.65Tb3+, 0.20Sm3+ remains 50 % of that at room temperature. A WLED device fabricated with the phosphor and a 365 nm LED chip exhibits a high color rendering index of 90.9, correlated color temperature of 5469 K, and CIE coordinates of (0.333 and 0.328). The results indicate that the as-prepared double perovskite materials are promising candidates in the solid-state lighting field.

Designing high-efficiency red-emitting Mg2In1-zSczSbO6:Mn4+,Li+ phosphors for plant growth lighting

In this work, a synergistic strategy of small cation substitution and charge compensation to realize efficient red luminescence has been developed, which greatly improves the luminescence performance of Mg2InSbO6:Mn4+ by modulating the degree of distortion of the Mn4+ lattice site. The doping Mn ion is stabilized in the tetravalent state and occupies the Sb5+ site. After the Sc3+-In3+ substitution, the emission characteristic of the original Mg2InSbO6:Mn4+ is regulated and effectively red-shifted, and the extruded [MnO6] octahedron present distorted due to the aberration of the near-neighboring lattice sites of Mn4+. Through the Sc3+-In3+ substitution and Li+ compensation, the optimal thermal stability at 423 K is enhanced by 19.1% compared with that of Mg2InSbO6:Mn4+. Surprisingly, the designed Mg2In0.3Sc0.7SbO6:0.003Mn4+,Li+ phosphor exhibits excellent quantum yield (82.02%) and high color purity (97.3%), which is higher than most of the reported Mn4+-doped phosphors. Moreover, the growth of sweet potatoes by combining the plant growth illumination device encapsulated by the phosphor is implemented. The relevant growth parameters further confirm that the designed phosphors have a great potential application in the field of plant growth lighting.

Effect of Tb3+ and Ce3+ Co-doping on the Structure and Photoluminescence Properties of Hexagonal Boron Nitride Phosphors.

In the paper, we have successfully prepared hexagonal boron nitride (h-BN:Tb3+, Ce3+) phosphors with melamine as the nitrogen source. The X-ray powder diffraction patterns confirm that the sample possesses a hexagonal crystal structure within the P m2 space group. It is interesting that the co-doping combination of Tb3+ and Ce3+ can markedly enhance the threshold concentration of doped activators within the limited solid solution of h-BN phosphors. Under 302nm excitation, the h-BN:Ce3+ phosphors exhibit broadband blue light emission at 406nm. In h-BN:Tb3+, Ce3+ phosphors, the co-doping of Ce3+ not only ensures high phase purity but also results in strong green light emission. The energy transfer efficiency from Ce3+ to Tb3+ is about 55%. The fluorescence lifetime increases with the increase of Ce3+ and Tb3+ concentration, and the fluorescence lifetime of h-BN:0.025Tb3+, 0.05Ce3+ phosphor reached 2.087ms. Additionally, the h-BN:0.025Tb3+, 0.05Ce3+ phosphor exhibits excellent thermal performance with an activation energy value of 0.2825eV. Moreover, the photoluminescence quantum yield of the sample exceeds 52%. Therefore, the h-BN:Tb3+, Ce3+ samples can be used as green phosphors for solid state lighting and fluorescent labeling.

Synthesis and Spectroscopic Investigations of Sm3+ Activated ZrO2 and Na2ZrO3 as Warm Light Phosphors.

In this work, we investigate how the structural and optical characteristics of ZrO2 and Na2ZrO3 are influenced by Sm3+ ion doping. Urea-assisted combustion approach is employed by varying the molar concentration of Sm3+ ions in both the host lattices. XRD pattern revealed the monoclinic crystal system for both samples. XPS investigation has been examined to acquire the chemical information of the samples. FESEM is used to identify the morphology of the samples. The optimum molar concentrations of Sm3+ doped ZrO2 and Na2ZrO3 phosphors, as per photoluminescence (PL) findings, are 1.5mol% and 2mol%, respectively. CIE coordinates of ZrO2:Sm3+ and Na2ZrO3:Sm3+ are found to be (x = 0.59, y = 0.41) and (x = 0.61, y = 0.39) that corresponds to the amber region of color gamut. The optical bandgap for the synthesized samples is estimated using the UV-Vis diffuse reflectance spectra and the obtained values for the optimal concentration of dopant (Sm3+) in the ZrO2 and Na2ZrO3 samples are 4.61 and 4.94eV, respectively. The findings of the study reveal that the synthesized phosphors may be utilized as warm light phosphors and be a promising candidate for amber light-emitting diodes (LEDs).

Synthesis and photoluminescence study of Sm3+-activated KBaY(BO3)2 phosphor for solid-state lighting

Synthesis and photoluminescence study of Sm3+-activated KBaY(BO3)2 phosphor for solid-state lighting

SrNb2O6: Dy3+: a single phase warm white light emitting phosphor for solid-state lighting

SrNb2O6: Dy3+: a single phase warm white light emitting phosphor for solid-state lighting

High efficiency white emission in Na3Ba2Ca(PO4)3:Eu2+, Mn2+ phosphors for urban ecological lighting

The white-light-emitting devices (WLEDs) for urban ecological lighting remain the challenge. The current urban lighting system destroys the growth habits of plants and leads to inhibition of plant growth, reduced branching, smaller leaf area and reduced total dry weight due to excessive blue light. In this work, a series of blue-green and red dual-emission Na3Ba2Ca(PO4)3:Eu2+, Mn2+ phosphors have been successfully synthesized by the high-temperature solid-state reaction method. The crystal structure, the occupancy of the dopant ions and the luminescence characteristics were carefully investigated. The excitation and emission spectra as well as the decay lifetime confirm the effective energy transfer from Eu2+ to Mn2+, which leads to a tunable luminescence with greatly reduced blue emission. Especially, the optimal Na3Ba2Ca(PO4)3:0.02Eu2+, 0.11Mn2+ phosphor demonstrates a high internal quantum yield of 99.7%. At 150 °C, the luminescence intensity of Na3Ba2Ca(PO4)3:0.02Eu2+, 0.11Mn2+ can maintain 64.5% of room temperature intensity. In addition, the WLED device fabricated with Na3Ba2Ca(PO4)3:Eu2+, Mn2+ phosphor shows white light emission with CIE coordinates of (0.3800, 0.3852), rendering index (Ra) of 65.4 and correlated color temperature (CCT) of 3640 K. These results confirm that the Na3Ba2Ca(PO4)3:Eu2+, Mn2+ phosphor can be applied as a white light source in the urban ecological field.

Ho3+ -doped BaGd2 ZnO5 green-emitting phosphor for solid-state lighting: synthesis, characterization, and photoluminescence properties.

In this work, we present the synthesis of a green-emitting series of BaGd2 ZnO5 :xHo3+ (0.5-3mol%) phosphors using a high-temperature solid-state reaction method. Phase purity and crystal structure information were evaluated through X-ray powder diffraction patterns. Optical properties were examined through diffuse reflectance spectra, revealing that the prepared phosphor exhibited a band gap of 4.65 eV. The effect of Ho3+ doping on the morphology and ion distribution on the surface was assessed using scanning electron microscopy and time-of-flight secondary ion mass spectrometry techniques, respectively. The excitation spectra of the synthesized phosphor exhibited a charge transfer band and strong absorption transitions. The emission spectra displayed typical holmium emission characteristics, featuring a strong green emission band associated with f-f transitions from 5 F4 + 2 S2 → 5 I8 . Decay dynamics of the synthesized phosphor exhibited a single-exponential decay pattern, with lifetimes ranging from 0.103 to 0.053 ms. The intrinsic radiative lifetime, calculated through Auzel's fitting was determined to be 0.14 ms. Using the emission spectra, colorimetric behaviour was analyzed, revealing that the Commission Internationale de l'éclairage (CIE) coordinates exclusively lay within the green region at (0.285, 0.705), with an impressive colour purity of 99.6%. Given these marked properties, the synthesized phosphor exhibits great potential for a wide range of green-emitting applications, including displays, white light-emitting diodes, and security signage.

Ba3Lu(BO3)3:Ce3+,Tb3+/Mn2+: Dual-Functional Material for WLEDs and Optical Pressure Sensing.

Ba3Lu(BO3)3(BLB):Ce3+,Tb3+/Mn2+ phosphors were designed to explore effective and multifunctional applications. Under the excitation of near-ultraviolet (n-UV) light, the BLB:Ce3+ phosphor showed broad-band blue emission. After codoping with Mn2+ ions, the single-phase white light phosphor is achieved through the energy transfer (ET) between Ce3+ and Mn2+. In addition, thermal stability is significantly enhanced by the addition of Tb3+ (BLB:0.02Ce3+,0.20Tb3+) compared to that codoped with Mn2+ (BLB:0.02Ce3+,0.10Mn2+). The light-emitting diode (LED) device with warm white light emission is fabricated with UV-chip-coated BLB:0.02Ce3+,0.05Tb3+ and Sr2Si5N8:Eu2+ phosphors, showing a good potential application value for LEDs. Additionally, the spectral properties of borate-based phosphors (BLB:0.02Ce3+) under high pressure were studied for the first time. Surprisingly, the change of pressure enabled the emission peak of BLB:0.02Ce3+ to be tuned from 485 to 552 nm, and dλ/dP is 3.51 nm GPa-1. The color changes from blue to yellow with an increase of pressure. Compared with the reported data, the pressure-sensing sensitivity based on the central peak shift in this work is the highest in all Ce3+ single-doped samples. In addition, the emitting color and intensity were gradually regained after decompression. The intensity can reach 80% of the initial intensity. All data demonstrate that the BLB:0.02Ce3+ phosphor has the potential to be utilized as an optical pressure sensor due to the high-pressure sensitivity and visible color tuning.

Advancements of Lanthanide-doped Phosphors in Solid-state Lighting Applications

Abstract: The challenge of energy conversion and enhancement has been a problem in the world of lighting technologies as the population and global industrialization grow rapidly. Solid-state lighting (SSL) has proven to be a better alternative in the illumination industry because of its environmentally friendly and high energy efficiency. Lanthanide-doped phosphors have gained global attention in SSL because they have versatile applications with enhanced overall performance and luminescence. This review delves into the advancement in lanthanide-doped phosphors for Solid-state lighting (SSL) applications. It discusses the in-depth analysis of how to tailor the crystal lattice design, optimize the host material for emission efficiency, and minimize the non-radiative pathways. This paper further discusses the lanthanide-doped phosphor composition, strategies to obtain desired emission spectra, and enhanced color rendering index with the Energy transfer mechanism and the synthesis techniques. This review also addresses 3 processes for expanding the light spectrum, current challenges, future directions, and emerging trends present in the lanthanide-doped phosphor in Solid-state lighting (SSL) applications.

Garnet Structure-Activated Warm White Light Phosphors Ca3Al2Ge3O12: Dy3+, Eu3+ with Ultrahigh Thermal Stability and Tunable Luminescence.

A series of Ca3Al2Ge3O12: xDy3+, yEu3+ phosphors were successfully prepared by the high-temperature solid-phase method. The phase and morphology of the phosphors were studied by means of Rietveld refinement and scanning electron microscopy. The results show that the phase is pure, and the crystal structure is the Ia3̅d space group. In the Ca3Al2Ge3O12: xDy3+ phosphors, using 380 nm excitation, phosphors showed blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emission peaks at 481 and 581 nm, respectively. In Ca3Al2Ge3O12: xDy3+, yEu3+ phosphors, the energy transfer was inferred by the spectrum overlap of Dy3+ and Eu3+, and the lifetime attenuation was analyzed from the perspective of dynamics; finally, the band gap structure of the phosphors was analyzed by combining diffuse reflection spectra with the first principle, and the energy transfer mechanism and luminescence mechanism were elaborated by combining theory and practice. The transition from blue white light to red light can be achieved by tuning the range of y in Ca3Al2Ge3O12: 0.015Dy3+, yEu3+. Wherein, when y = 0.07, phosphors, the chromaticity coordinate of warm white CIE is (0.3932, 0.3203), the color temperature is 3093 K, and the warm white light is synthesized. The thermal stability of the synthesized warm white phosphors is 90.1% (423 K), the thermal sensing factors are Samax = 5.51 × 10-4 K-1 (303 K) and Srmax = 0.0359% K-1 (303 K), and the actual quantum efficiency is IQE = 52.48%. These results prove that Ca3Al2Ge3O12: Dy3+, Eu3+ have good application prospects as single-component warm w-LED devices.