An efficient blue-violet phosphor: an advanced material designed for high-quality full-spectrum lighting

A highly efficient phosphor with exceptional luminescence properties is crucial for achieving high-quality solid-state white-light illumination. Here, this paper presents a groundbreaking discovery, an innovative blue-violet emitting Ba1.31Sr3.69(BO3)3Cl:Ce3+ (BSBCl:Ce3+) phosphor designed with remarkable thermal stability and quantum efficiency for full spectrum white light-emitting diodes (WLEDs). By employing a high-temperature solid-phase method, we synthesized various BSBCl:xCe3+ phosphors with different Ce3+ doping concentrations. Remarkably, BSBCl:0.03Ce3+ displays a broad excitation band from 250 nm to 400 nm, rendering it compatible with commercial near-ultraviolet (UV) LED chips. Under 330 nm excitation, this phosphor emits blue light with an astonishing 88.2% internal quantum efficiency (IQE) and an impressive 60.9% external quantum efficiency (EQE). Notably, when employed in the temperature range of 298-473 K, the synthesized BSBCl:0.03Ce3+ phosphor exhibits exceptional color stability and thermal stability (I423 K/I298 K = 83%). Utilizing BSBCl:0.03Ce3+ as the blue-violet emitting component in the fabrication of WLED devices has demonstrated significant advancements in the color rendering index. These findings underscore the potential of BSBCl:Ce3+ phosphors for a wide range of applications in health-oriented indoor illumination.

Judd-Ofelt parameters and X-ray irradiation results of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors synthesized via a molten salt method

Trivalent Eu-activated MNb2O6 (M = Sr, Cd, Ni) ceramic phosphors were produced using the molten salt route, which involves a low sintering temperature and provides improved homogeneity. The photoluminescence (PL) and radioluminescence (RL) spectra of phosphors exhibited characteristic Eu3+ emissions with 5F0 → 7F j transitions, and strong peaks occurred at the 5D0 → 7F2 transition. The PL and RL emissions of SrNb2O6:Eu3+ decreased over 3 mol%, while both emissions for CdNb2O6:Eu3+ and NiNb2O6:Eu3+ increased with increasing Eu3+ concentration. The spectral properties of phosphors were evaluated by determining Judd-Ofelt intensity parameters (Ω 2, Ω 4) from the PL emission spectrum. The quantum efficiencies (η QE%) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with the highest emission were found as 61.87%, 41.89%, and 11.87% respectively. Bandwidths (σ e × Δλ eff) and optical gains (σ e × τ) of MNb2O6:Eu3+ (M = Sr, Cd, Ni) phosphors with highest emissions were found as follows; 24.182 × 10-28, 28.674 × 10-28, 38.647 × 10-28 cm3 and 20.441 × 10-25, 13.790 × 10-25, 3.987 × 10-25 cm2 s, respectively, corresponding to the 5D0 → 7F2 transition.

Eu(iii)-Doped tri-calcium Ca3(1−X−Z)MZ(PO4)2AX:X host array: optical investigations of down-conversion red phosphor for boosting display intensity and high color purity

Eu³⁺-Activated double and triple phosphates were synthesized via a high-temperature solid-state reaction.

Study on the fluorescence properties of micron-submicron-nano BaFBr:Eu2+ phosphors

BaFBr:Eu²⁺ with narrow size distribution and good dispersion is fabricated via a precipitation method. After annealing, it shows excellent optical properties.

Upconversion luminescence modulated by alkali metal (Li, Na, and K) induced crystallization in Er3+/Yb3+ co-doped β-PbF2 oxyfluoride glass ceramics

Upconversion luminescence of Er³⁺/Yb³⁺ co-doped β-PbF₂ oxyfluoride glass ceramics modulated by alkali metals (Li, Na, and K).

Enhanced Photoluminescence Properties of Low-Dimensional Eu3+-Activated Y4Al2O9 Phosphor Compared to Bulk for Solid-State Lighting Applications and Latent Fingerprint Detection-Based Forensic Applications

In recent years, nanoscale phosphors have become vital in optoelectronic applications and to understand the improved performance of nanophosphors over bulk material, detailed investigation is essential. Herein, trivalent europium-activated Y4Al2O9 phosphors were developed by solid-state reaction and solvothermal reaction methods and their performance as a function of their dimension was studied for various applications. Under 394 nm optical excitation, the photoluminescence (PL) emission, excited state lifetime of the nanophosphor, exhibits greater performance than its bulk counterpart. The homogeneous spherical structure of the nanophosphors as compared with solid lumps of bulk phosphors is the basis for almost 40% of the enhancement in nanophosphors' intense red emission compared to the bulk. Moreover, the thermal stability of the nanophosphor is much better than the bulk phosphor, which clearly indicates a key advantage of nanophosphor. The superior performance of Eu3+-doped Y4Al2O9 nanophosphors over their bulk counterparts has been demonstrated for industrial phosphor-converted light-emitting diodes and visualization of latent fingerprint.

Photoluminescence, radioluminescence and thermoluminescence properties of Eu3+ doped cadmium tantalate phosphor

For investigate spectroscopic properties, Eu3+ doped columbite type CdTa2O6 phosphors were synthesized using the solid state reaction method. The synthesized ceramic phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), photoluminescence (PL), radioluminescence (RL) and thermoluminescence (TL) analyses. CdTa2O6:Eu3+ phosphors exhibited emissions at 591.8 nm and 612.1 nm because of the characteristic band transitions of the Eu3+ ion. Phosphor emission increased with increasing Eu3+ ion dopant up to 1.5 mol%, and then decreased owing to concentration quenching. The decay times decreased with increasing Eu3+ dopant, while they were varied from 711 to 534 μm. The scintillation emissions of Eu3+ doped samples from the UV to near-IR spectral region were monitored by RL measurements. The high RL emission may be attributed to the good scintillation property of phosphor. TL glow curves were monitored for different Eu3+ concentrations in the range of 50 °C to 400 °C at a heating rate of 2 °C s-1, after being irradiated under short-wave UV light (254 nm).

Enhanced Upconversion and Downshifting emissions from Tb3+, Yb3+ co-doped CaZrO3 phosphor in presence of Li+ ions

This paper reports the enhanced green photoluminescence from Tb3+, Yb3+ co-doped CaZrO3 phosphor in the presence of Li+ ion synthesized through solid state reaction technique. The structural studies show an increase in the particle size and a shrink in crystal lattice due to Li+ co-doping in the phosphor. The phosphor sample emits intense green upconversion emission (UC) due to Tb3+ ions on excitation with 980 nm radiation which is further enhanced ~ 28 times on Li+ co-doping. The lifetime of 5D4 level of Tb3+ ion decreases in the presence of Li+ ions due to increase in asymmetry in crystal field. The downshifting (DS) emission intensity monitored on 378 and 487nm excitations is also enhanced in the presence of Li+ ions. Thus, the Tb3+, Yb3+, Li+ co-doped CaZrO3 phosphor can be a suitable candidate for UC solid state lighting.

Neutralizing the Charge Imbalance Problem in Eu3+-Activated BaAl2O4 Nanophosphors: Theoretical Insights and Experimental Validation Considering K+ Codoping

In recent years, rare-earth-doped nanophosphors have attracted great attention in the field of luminescent materials for advanced solid-state lighting and high-resolution display applications. However, the low efficiency of concurrent red phosphors creates a major bottleneck for easy commercialization of these devices. In this work, intense red-light-emitting K⁺-codoped BaAl₂O₄:Eu³⁺ nanophosphors having an average crystallite size of 54 nm were synthesized via a modified sol-gel method. The derived nanophosphors exhibit strong red emission produced by the ⁵D₀ → ⁷F _J (J = 0, 1, 2, 3, 4) transitions of Eu³⁺ upon UV and low-voltage electron beam excitation. Comparative photoluminescence (PL) analysis is executed for Eu³⁺-activated and K⁺-coactivated BaAl₂O₄:Eu³⁺ nanophosphors, demonstrating remarkable enhancement in PL intensity as well as thermal stability due to K⁺ codoping. The origin of this PL enhancement is also analyzed from first-principles calculations using density functional theory. Achievement of charge compensation with the addition of a K⁺ coactivator plays an important role in increasing the radiative lifetime and color purity of the codoped nanophosphors. Obtained results substantially approve the promising prospects of this nanophosphor in the promptly growing field of solid-state lighting and field emission display devices.

White light emitting MgAl2O4:Dy3+,Eu3+ nanophosphor for multifunctional applications

An efficient energy transfer from Dy³⁺ to Eu³⁺ in MgAl₂O₄ offers white light emission and self-referencing thermal behaviour.

Morphology control and photoluminescence properties of Eu3+-activated Y4Al2O9 nanophosphors for solid state lighting applications

Spherical Eu³⁺:Y₄Al₂O₉ nanophosphors exhibit brilliant PL behavior with enhanced color purity and excited state lifetime.

Developing near-infrared long-lasting phosphorescence of Yb3+ through a medium: insights into energy transfer in the novel material Zn1.98Li0.02P2O7:Yb3+

We systematically investigated and focused on how to excite Yb³⁺ and obtain long-lasting phosphorescence in the novel phosphor Zn_1.98Li_0.02P₂O₇:Yb³⁺.

Influence of Li+ charge compensator ion on the energy transfer from Pr3+ to Gd3+ ions in Ca9Mg(PO4)6F2:Gd3+, Pr3+, Li+ phosphor

Phototherapy is a renowned treatment for curing skin diseases since ancient times. Phototherapeutic treatment for psoriasis and many other diseases require narrow band ultra violet-B (NB-UVB) light with peak intensity at 313nm to be exposed to the affected part of body. In this paper, we report combustion synthesis of NB-UVB -313nm emitting Ca₉Mg(PO₄)₆F₂ phosphors doped with Gd³⁺, Pr³⁺ and Li⁺ ions. The phase formation was confirmed by obtaining X-ray diffraction (XRD) pattern and morphology was studied with the Scanning electron microscopy (SEM) images. Photoluminescence (PL) emission spectra show intense narrow band emission at 313nm under 274nm excitation wavelengths. Emission intensity was enhanced when Ca₉Mg(PO₄)₆F₂ compound is co-doped with Pr³⁺ ions. Excitation spectra of Ca₉Mg(PO₄)₆F₂:Gd³⁺, Pr³⁺ doped samples shows broad excitation in ultra violet C (UVC) region. Diffuse reflectance spectra (DRS), obtained by UV-visible spectrophotometer, measures the absorption properties of the material. By applying Kubelka Munk function on the diffuse reflectance spectra, band gap of the material is determined. PL decay curves were examined which indicates efficient energy transfer between Pr³⁺ and Gd³⁺ ions. Charge compensation effect was also studied by co-doping Li⁺ ion in host. Emission intensity was found to increase with the addition of charge compensator. The prepared phosphor has potential to convert UVC light into NB-UVB. The luminescence intensity of Gd³⁺ shows remarkable increase when it is sensitized with Pr³⁺, and an addition of charge compensator in the form of Li⁺, show even better results. This phosphor surely has the potential to be used as phototherapy lamp phosphor.

Enhancement of upconversion, temperature sensing and cathodoluminescence in the K+/Na+ compensated CaMoO4:Er3+/Yb3+ nanophosphor

Enhancing upconversion, temperature sensing and cathodoluminescence in the CaMoO₄:Er³⁺/Yb³⁺ nanophosphor via K⁺/Na⁺ simultaneous codoping.

Upconversion luminescence enhancement and temperature sensing behavior of F− co-doped Ba3Lu4O9:Er3+/Yb3+ phosphors

F⁻ doping to enhance upconversion luminescence and temperature sensitivity of Ba₃Lu₄O₉:Er³⁺/Yb³⁺ (EYBLO) phosphors is ascribed to the modification of local crystal field of activator ions and reduction of crystal site symmetry.

Enhanced up-conversion and temperature-sensing behaviour of Er(3+) and Yb(3+) co-doped Y2Ti2O7 by incorporation of Li(+) ions

Y2Ti2O7:Er(3+)/Yb(3+) (EYYTO) phosphors co-doped with Li(+) ions were synthesized by a conventional solid-state ceramic method. X-ray diffraction studies show that all the Li(+) co-doped EYYTO samples are highly crystalline in nature with pyrochlore face centred cubic structure. X-ray photon spectroscopy studies reveal that the incorporation of Li(+) ions creates the defects and/or vacancies associated with the sample surface. The effect of Li(+) ions on the photoluminescence up-conversion intensity of EYYTO was studied in detail. The up-conversion study under ∼976 nm excitation for different concentrations of Li(+) ions showed that the green and red band intensities were significantly enhanced. The 2 at% Li(+) ion co-doped EYYTO samples showed nearly 15- and 8-fold enhancements in green and red band up-converted intensities compared to Li(+) ion free EYYTO. The process involved in the up-conversion emission was evaluated in detail by pump power dependence, the energy level diagram, and decay analysis. The incorporation of Li(+) ions modified the crystal field around the Er(3+) ions, thus improving the up-conversion intensity. To investigate the sensing application of the synthesized phosphor materials, temperature-sensing performance was evaluated using the fluorescence intensity ratio technique. Appreciable temperature sensitivity was obtained using the synthesized phosphor material, indicating its applicability as a high-temperature-sensing probe. The maximum sensitivity was found to be 0.0067 K(-1) at 363 K.

Hierarchical cupric oxide nanostructures on copper substrate for cold cathode emission: an experimental venture with theoretical correlation

In this paper we report a facile route for the synthesis of controlled CuO nanoarchitectures directly grown on a copper substrate by a one-step simple chemical route with varying concentration of non-ionic surfactant PEG-6K. The phase purity and degree of crystallinity of the as-developed nanostructures were systemically investigated by X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy (HRTEM). A detailed analysis by field emission scanning electron microscopy confirmed the uniformity of the prepared nanostructures on the substrates. These architectures displayed substantial improvement of field emission properties with respect to other structures of CuO reported so far. A particular nanostructure (needle) among them showed a down shift of the turn-on field to 2.2 V μm(-1) coupled with a good enhancement factor (β) ∼516, which are deemed as sufficient for electron emission based applications such as field emission displays and vacuum nanoelectronic devices. The origin of this efficient field emission from CuO nanoarchitectures, were probed computationally by investigating the local electric field distribution through finite element based simulation method using the ANSYS Maxwell simulation package.

Observation of bright green luminescence in an Eu2+ complexed graphene oxide composite through reduction of Eu3+

We have demonstrated a simplified reduction technique of Eu³⁺ to Eu²⁺ in complexation with an azo-pyridine graphene oxide composite and its effect on photoluminescence.

The effect of Li+ ions on the luminescent properties of a single-phase white light-emitting phosphor α-Sr2P2O7:Dy3+

Two series of phosphors, α-Sr_2(1−x)Dy_2xP₂O₇ and α-Sr_2(1−2x)Dy_2xLi_2xP₂O₇, with different x values were synthesized successfully using a conventional solid-state method at high temperature for the first time, and their luminescence properties were investigated comparatively.

Luminescence properties of a novel reddish orange long-lasting phosphorescence phosphor Zn2P2O7:Sm3+,Li+

A new reddish orange long-lasting phosphor was synthesized via incorporating Li⁺ into Sm³⁺ activated Zn₂P₂O₇ to modify its trap levels.

Studies of terbium bridge: saturation phenomenon, significance of sensitizer and mechanisms of energy transfer, and luminescence quenching

Terbium chain in the form of S → (Tb(3+))n → A (S = Ce(3+) or Eu(2+), A = Eu(3+)), as a promising energy transfer (ET) approach, has been proposed to enhance Eu(3+) emission for solid-state lighting. However, the viewpoint of ET from S to A via the terbium chain (Tb(3+)-Tb(3+)-Tb(3+)-...) is very doubtful. Here, hosts of Ba3Ln(PO4)3, LnPO4, LnBO3, and Na2Ln2B2O7 doped with Ce(3+) → (Tb(3+))n → Eu(3+) or (Tb(3+))n → Eu(3+) are synthesized to prove the universality of S → (Tb(3+))n → A in inorganic hosts and to study the unsolved issues. Saturation distance of Tb(3+)-Eu(3+), estimated with the empirical data of different hosts, is proposed to be a criterion for determining whether a spectral chromaticity coordinate keeps constant. A branch model is put forward to replace the chain model to explain the role of (Tb(3+))n in ET from Ce(3+) to Eu(3+) and the necessity of high content of Tb(3+); the term "terbium bridge" is used to replace "terbium chain", and the value of n is determined to be two or three. The intensity quenching of Eu(3+) emission is attributed to the surface defects ascribed to the smaller particles and larger specific surface area rather than the concentration quenching of Tb(3+). Based on the saturation distance and the mechanism of luminescence quenching, the necessary concentration of Tb(3+) for (Tb(3+))n can be estimated as long as the cell parameters are already known and the luminescent efficiency of Eu(3+) can be further improved by optimizing the synthesis method to decrease the quantity of surface defects.

Synthesis and photoluminescence properties of a novel Sr2CeO4:Dy3+ nanophosphor with enhanced brightness by Li+ co-doping

A series of Dy³⁺ (0.005–0.09 mol%) and Li⁺ (0.005–0.03 mol%) co-doped strontium cerate (Sr₂CeO₄) nanopowders are synthesized by low temperature solution combustion synthesis.