Phosphor For Solid-state Lighting Research Articles

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

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.

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

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 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

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.

Preparation and photoluminescence properties of Ba2La8(SiO4)6O2:Eu3+ red phosphor for solid-state lighting and horticulture

In this study, the Ba2La8(SiO4)6O2: xEu3+ red phosphors were prepared by high temperature solid phase method. The phase structure, luminescence characteristics, thermal stability and color coordinates of the samples were analyzed. The results show that the Ba2La8(SiO4)6O2: xEu3+ red phosphors can be excited by ultraviolet or blue light, Under the excitation of 394 nm, the 5D0-7FJ (J = 0,1,2,3,4) transition emission of Eu3+ was observed in the range of 500–750 nm, and the strongest emission peak was located at 703 nm (5D0-7F4), the optimal doping concentration of Eu3+ is 12 %, and the mechanism of concentration quenching is attributed to the electric quadrupole–quadrupole interaction. The internal quantum efficiency (IQE) of phosphor is 23.82 %. The samples have a high activation energy (0.3193 eV) and good thermal stability in the temperature range of 300 K to 575 K, the color coordinates of all samples are located in the red luminous region. The deep red strong emission peak of Ba2La8(SiO4)6O2: xEu3+ is located at 703 nm, which is consistent with the absorption band of plant photochrome (PFR). The above results indicate that Eu3+-doped Ba2La8(SiO4)6O2 phosphor have potential applications in the field of white light LEDs and plant growth lighting.

Synthesis and tunable photoluminescence properties of Er3+/Eu3+ co-doped Na5La(MoO4)4 phosphors

The tunable emission characteristics of Er3+ doped and Er3+/Eu3+ co-doped Na5La(MoO4)4 phosphors prepared via high-temperature solid phase method were investigated. The microstructure of the modified phosphor was studied by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy, and its luminescence properties were analyzed by photoluminescence excitation and photoluminescence spectra. The energy transfer mechanism of Er3+ ions to Eu3+ ions was investigated by changing the concentration of Eu3+ ions to induce the spectral changes, and the photoluminescence decay lifetime was measured to validate the findings. Notably, under excitation at 380 nm, the co-doped phosphors exhibited tunable emission ranging from green to orange-red. Furthermore, Na5La(MoO4)4:0.04Er3+/0.04Eu3+ phosphor, when combined with a 380 nm chip, achieved desired warm white light emission. These promising results underscore the potential application of Na5La(MoO4)4:0.04Er3+/0.04Eu3+ phosphor in solid-state lighting.

GPT-Assisted Learning of Structure-Property Relationships by Graph Neural Networks: Application to Rare-Earth-Doped Phosphors.

Two challenges facing machine learning tasks in materials science are data set construction and descriptor design. Graph neural networks circumvent the need for empirical descriptors by encoding geometric information in graphs. Large language models have shown promise for database construction via text extraction. Here, we apply OpenAI's Generative Pre-trained Transformer 4 (GPT-4) and the Crystal Graph Convolutional Neural Network (CGCNN) to the problem of discovering rare-earth-doped phosphors for solid-state lighting. We used GPT-4 to datamine the chemical formulas and emission wavelengths of 264 Eu2+-doped phosphors from 274 articles. A CGCNN model was trained on the acquired data set, achieving a test R2 of 0.77. Using this model, we predicted the emission wavelengths of over 40 000 inorganic materials. We also used transfer learning to fine-tune a bandgap-predicting CGCNN model for emission wavelength prediction. The workflow requires minimal human supervision and is generalizable to other fields.

Study of morphological, elemental, optical and excitation wavelength dependent red photoluminescence in Eu3+ doped Li2SrSiO4 for solid state lighting

A comprehensive investigation of Eu3+ doped Li2SrSiO4 phosphors synthesized via the solid-state reaction method was conducted. XRD confirmed the crystalline phase and SEM along with and its 3D projection's observations confirmed that the phosphor particles were in the micro meter size range, indicating their suitability for applications in primary phosphor-converted LEDs. FTIR spectroscopy elucidated vibrational characteristics, while TGA, EDX and XPS analysed thermal stability, elemental composition and valence states respectively. Doping-induced band gap increase was attributed to the Moss-Burstein effect. Photoluminescence excitation studies revealed enhanced absorption at 394 nm compared to the charge transfer transition band (CTB) at 254 nm, aligning with industry-standard near-ultraviolet chips. XPS suggested two distinct Eu3+ sites in the LSS crystal, corroborated by excitation wavelength-dependent PL emission. As a result of excitation wavelengths, the magnetic-dipole transition (5D0 → 7F1) at 592 nm, the electric-dipole transition (5D0 → 7F2) at 615 nm and the induced electric-dipole transition ((5D0 → 7F3,4) at 650 and 700 nm arose. Additionally, the phosphor gave an improved conversion efficiency at 2% Eu doping. Low synthesis temperature, micro-sized particles, thermal stable, short lifetime, excitation bands at near UV to blue region, colour tunability, lower CCT, LER and similar CIE to available red phosphors are the key factors for the Li2SrSiO4:Eu3+ proving reliable red phosphor for solid state lighting.

A thermally stable lithium yttrium phosphate phosphor for solid-state lighting

In this work, trivalent dysprosium was incorporated with lithium yttrium phosphate LiY5P2O13 (LYP), obtaining a yellow-emitting material. The crystallographic sites of introduced Dy3+ activators are determined through the comprehensive analysis of the XRD investigation, DFT computation, and experimental luminescence spectra. Under 353 nm excitation, the LYP:Dy3+ phosphor shows bright yellow emission owing to dominant 4F9/2 → 6H13/2 transition (577 nm) of Dy3+. The luminescence quenching occurs when the Dy3+ content exceeds 0.07 mol, originating from the dipole–dipole interaction. Furthermore, the excellent thermal stability behavior (84 % at 423 K) and good resistance to color shifting (0.00634 at 473 K) for title phosphor are manifested by temperature-dependent investigation. Eventually, the w-LED fabricated with LYP:0.07Dy3+ and commercial materials exhibits stable white-emitting output (0.3595, 0.3179) with high Ra (85) and low CCT (4203 K). All the study demonstrates that the LYP:Dy3+ material is a perspective candidate in solid-state illustration field.

Photoluminescence properties of CaMgB2O5: RE3+ (RE = Dy, Eu, Sm) environmental friendly phosphor for solid state lighting

Photoluminescence properties of CaMgB2O5: RE3+ (RE = Dy, Eu, Sm) environmental friendly phosphor for solid state lighting

High-quality reddish-orange-emitting Sr6Y2Al4O15:Eu3+ phosphors for solid-state lighting and anti-counterfeiting applications

The reddish-orange emitting Sr6Y2Al4O15:Eu3+ phosphors were synthesized via a high-temperature solid-state reaction technique, and their luminescent properties were systematically studied. The dominant emission peak assigned to the electric dipole transition (5D0 → 7F2) was recorded at 612 nm owing to the non-inversion symmetry of the substituted sites of Eu3+ ions under the excitation of charge transfer band (∼261 nm). The emission of Sr6Y2Al4O15:Eu3+ revealed a Commission Internationale de l'Eclairage (CIE) chromaticity coordinate of (0.571, 0.368) and a color purity of 93.6 %. The thermal stability and photoluminescence quantum yield (PLQY) of Sr6Y2Al4O15: Eu3+ were analyzed, exhibiting a high thermal stability of 88.24 % at 423K and a good external PLQY of 36.24 %. Furthermore, the solid-state lighting (SSL) and flexible anti-counterfeiting applications of Sr6Y2Al4O15:Eu3+ were demonstrated. The red light-emitting diode (LED) was packaged with ∼260 nm ultraviolet LED chip, representing a CIE chromaticity coordinate of (0.5955, 0.3592) and a color purity of 86.53 %. The flexible anti-counterfeiting film was fabricated with polydimethylsiloxane polymer, and it showed tunable emission under different excitations. Moreover, the anti-counterfeiting ink was prepared and printed on various substrates. Consequently, the reddish-orange emitting Sr6Y2Al4O15: Eu3+ phosphors with high color purity, good thermal stability, and high quantum efficiency were introduced and potentially used in SSL and flexible anti-counterfeiting applications.

Color tunability and NIR luminescence in Cr3+/Li+ co-doped ZnGa2O4 phosphor for solid state lighting and NIR LEDs

In this work, we report the color tunable photoluminescence in the Cr3+/Li+ doped and co-doped ZnGa2O4 (ZGO) phosphors synthesized by solid state reaction method. The phase and surface morphology of ZGO phosphor were examined by XRD and SEM measurements, respectively. The EDS spectra revealed the presence of Zn, Ga, Cr and O elements in the phosphor. The vibrational structure of the phosphor materials has been analyzed by FTIR measurements. The Cr3+ doped phosphor shows electronic absorption bands at 302, 408 and 544 nm alongwith the host CTB at 260 nm. The optical band gap of the phosphor decreases via doping of Cr3+ and Cr3+/Li+ ions. The ZGO is a self-activated host and emits broad blue emission with maximum at 434 nm upon excitation at 260 nm. The Cr3+ doped phosphors show emission bands due to spin-allowed as well as spin-forbidden transitions due to Cr3+ ion in the blue, green and NIR regions on excitation with 260, 302, 408 and 544 nm wavelengths. The emission intensity is optimum for 0.5 mol% concentration of Cr3+ ion. The emission intensity of Cr3+ doped ZGO phosphor increases via doping of Li+ ion. The color tunability has been observed in the phosphor upon 260 and 302 nm excitations. The lifetimes of 4T2 (4F) and 2E states of Cr3+ ion have been measured and it is found that it decreases with increasing concentrations of Cr3+ and Cr3+/Li+ ions. The Cr3+/Li+ doped and co-doped ZGO phosphors may be suitable candidates for display devices, solid state lighting and NIR LEDs.

Structural and photoluminescence properties of europium (III)-activated lithium meta-silicate phosphors for solid-state lighting

Structural and photoluminescence properties of europium (III)-activated lithium meta-silicate phosphors for solid-state lighting

Lanthanum vacancy induced luminescence enhancement of Mn4+-activated LaMg2/3Nb1/3O3: A thermally stable deep-red phosphor for purple perilla cultivation

Deep-red luminescent materials have kept booming due to the distinct photophysical properties and broad application prospect in plant cultivation. Here, a series of La1-xMg2/3Nb1/3O3-δ:Mn4+ deep-red phosphors with the emission range of 660–730 nm were developed and lanthanum vacancy was introduced into the matrix via decreasing lanthanum content. The defect induced structure variation of the samples were analyzed detailedly and high structural adjustability of this perovskite was confirmed via X ray diffraction and transmission electron microscopy. By creating lanthanum vacancy into the matrix both the emission intensity and thermal stability of the phosphors were greatly improved. The emission intensity of the optimized La0.6Mg2/3Nb1/3O3-δ:Mn4+ at 423 K was improved almost 16 times than the initial sample at 423 K and kept 83.6% of that at 298 K. Furthermore, deep-red LED device was fabricated by coating this deep-red phosphor onto the near ultraviolet chip and applied to the cultivation of purple perilla. The purple perilla with additional deep-red light compensation in the night grew faster than that without light compensation. This modification strategy investigated here opens a new insight to improve the luminescence property of the phosphors for solid state lighting.

Luminescence properties of Tb3+/Eu3+ ions activated LiLaSiO4 phosphors for solid-state lighting and flexible display applications

The synthesis and luminescence properties of Tb3+ and Eu3+ single- and co-doped LiLaSiO4 (LLSO) phosphors with energy transfer mechanisms were reported. The rare-earth ions doped LLSO phosphors were synthesized via a solid-state reaction method and their physical characterizations such as phase purity, surface morphology, and elemental analysis were investigated systematically. For the Tb3+ and Eu3+ single- and co-doped LLSO phosphors, their photoluminescence (PL) properties were studied in detail. The LLSO:Tb3+ and LLSO:Eu3+ single-doped phosphors showed superior red and green emissions due to 5D4→7F5 and 5D0→7F2 in the optimized characteristic electronic transitions under ultraviolet (UV) irradiation, respectively. The luminescence performances for both the LLSO:Tb3+ and LLSO:Eu3+ phosphors were optimized at 0.125 mol of doping ion concentration. Under UV excitation, by adjusting the Eu3+ ion concentration in LLSO:0.125Tb3+/Eu3+ phosphors, the tunable emissions from green to red via yellow-orange were obtained. Thus, the tunable emission spectra and luminescence decay lifetimes with increasing the doping content of acceptor ions (Eu3+) confirmed an efficient energy transfer from Tb3+ to Eu3+ ions in the co-doped samples. The critical distance between Tb3+ and Eu3+ was determined to be 13.26 Å and the energy transfer mechanism from Tb3+ to Eu3+ ions was demonstrated to be a dipole-dipole mechanism interaction. In addition, the temperature-dependent PL study was carried out for the LLSO:0.125Tb3+/0.025Eu3+ co-doped phosphor sample and it showed better thermal stability against the temperature quenching. The Tb3+ and Eu3+ single- and co-doped LLSO/polydimethylsiloxane (PDMS) flexible composite films were fabricated by mixing the phosphor powders and PDMS solution. Benefiting from the effective protection of the PDMS matrix, the luminescence stability of the composite films was greatly enhanced. Based on the excellent properties of the synthesized phosphors, Tb3+ and Eu3+ single-doped and Tb3+/Eu3+ co-doped LLSO phosphors could serve as a single-phase multicolor-emitting phosphor under UV excitations.

Effect of charge compensators A+ (A+ = Li, Na and K) on photoluminescence properties of Ba2Ca(PO4)2:Eu3+ phosphor for solid state lighting

Effect of charge compensators A+ (A+ = Li, Na and K) on photoluminescence properties of Ba2Ca(PO4)2:Eu3+ phosphor for solid state lighting

The photoluminescence and Judd-Ofelt investigations of UV, near-UV and blue excited highly pure red emitting BaWO4: Eu3+ phosphor for solid state lighting

The article explores the photoluminescence properties of UV, near-UV and blue excited BaWO4: Eu3+ red phosphors. The optical band gap narrowing is observed after adding Eu3+ ions. The excitation spectra exhibit a broad peak centred at 255 nm and several narrow peaks of Eu3+ ions at 362, 382, 395, 415 and 465 nm. The three peaks located at 255 (UV), 395 (near-UV) and 465 nm (blue) are the most intense and suitable for the excitation of the sample. The spectral profile of the emission spectra irradiated at 255, 395 and 465 nm are identical. The brightest emission is realized at 18 mol% doping of Eu3+ ions at 255 and 465 nm excitations. However, the optimum concentration is 16 mol% at 395 nm excitation. The phosphors emit highly pure red lights with color purity 98.192%, 97.794% and 98.693% for the optimised concentration under UV, near-UV and blue excitations of 255, 395 and 465 nm, respectively. The quantum efficiency of BaWO4: 16 mol% Eu3+ phosphor is calculated as∼48.234% at 395 nm excitation. The emission intensity parameters are calculated in view of the Judd-Ofelt theory. The spectroscopic parameters like radiative transition probability, radiative lifetime, branching ratio and stimulated emission cross-section are further evaluated from the three emission spectra recorded at 255, 395 and 465 nm excitations. The derived results advocate the use of synthesized material as a red phosphor in white-LED, laser and display devices.