Energy Transfer Distance Research Articles

Arg92Leu-cTnT Alters the cTnC-cTnI Interface Disrupting PKA-Mediated Relaxation.

Impaired left ventricular relaxation, high filling pressures, and dysregulation of Ca2+ homeostasis are common findings contributing to diastolic dysfunction in hypertrophic cardiomyopathy (HCM). Studies have shown that impaired relaxation is an early observation in the sarcomere-gene-positive preclinical HCM cohort, which suggests the potential involvement of myofilament regulators in relaxation. A molecular-level understanding of mechanism(s) at the level of the myofilament is lacking. We hypothesized that mutation-specific, allosterically mediated, changes to the cTnC (cardiac troponin C)-cTnI (cardiac troponin I) interface can account for the development of early-onset diastolic dysfunction via decreased PKA accessibility to cTnI. HCM mutations R92L-cTnT (cardiac troponin T; Arg92Leu) and Δ160E-cTnT (Glu160 deletion) were studied in vivo, in vitro, and in silico via 2-dimensional echocardiography, Western blotting, ex vivo hemodynamics, stopped-flow kinetics, time-resolved fluorescence resonance energy transfer, and molecular dynamics simulations. The HCM-causative mutations R92L-cTnT and Δ160E-cTnT result in different time-of-onset diastolic dysfunction. R92L-cTnT demonstrated early-onset diastolic dysfunction accompanied by a localized decrease in phosphorylation of cTnI. Constitutive phosphorylation of cTnI (cTnI-D23D24) was sufficient to recover diastolic function to non-Tg levels only for R92L-cTnT. Mutation-specific changes in Ca2+ dissociation rates associated with R92L-cTnT reconstituted with cTnI-D23D24 led us to investigate potential involvement of structural changes in the cTnC-cTnI interface as an explanation for these observations. We probed the interface via time-resolved fluorescence resonance energy transfer revealing a repositioning of the N-terminus of cTnI, closer to cTnC, and concomitant decreases in distance distributions at sites flanking the PKA consensus sequence. Implementing time-resolved fluorescence resonance energy transfer distances as constraints into our atomistic model identified additional electrostatic interactions at the consensus sequence. These data show that the early diastolic dysfunction observed in a subset of HCM is attributable to allosterically mediated structural changes at the cTnC-cTnI interface that impair accessibility of PKA, thereby blunting β-adrenergic responsiveness and identifying a potential molecular target for therapeutic intervention.

Fluorescence and Colorimetric Dual-Readout Detection of Tetracycline Using Leucine-Conjugated Iron Oxide Quantum Dots.

This study developed a dual-readout system utilizing fluorescence and colorimetry based on iron oxide quantum dots (IO-QDs) for detecting tetracycline (TCy). IO-QDs were synthesized within 6 h using L-leucine as a surface modifier, achieving a more efficient route. Upon interaction with TCy, IO-QDs exhibited a significant decrease in fluorescence response and observable color changes, while fluorescence lifetime remained consistent regardless of TCy presence. Moreover, IO-QDs' fluorescence response remained stable across various temperatures. The Förster resonance energy transfer distance of less than 2 nm and a quenching constant of 2.90 × 1012 M-1s-1 indicated static quenching in the presence of TCy. Additionally, significant changes in observed and corrected fluorescence efficiency suggested the involvement of the inner filter effect in the fluorescence quenching of IO-QDs. The synthesized IO-QDs were then utilized for selective and rapid fluorescence-based TCy detection, showing a linear range of 0.5 to 80 μM. Simultaneously, a colorimetric method for TCy detection was established, demonstrating a good linear relationship within the range of 0.5 to 20 μM. The detection limits for TCy were determined as 0.539 and 0.329 μM using fluorescence and colorimetric approaches, respectively. Furthermore, IO-QDs were applied to detect real samples, and the dual-readout probe exhibited satisfactory recoveries, confirming the practical reliability of the developed method for analyzing milk and drinking water samples.

Influence of Host Lattice Ions on the Dynamics of Transient Multiband Upconversion in Yb-Er Codoped NaLnF4 and LiLnF4 Microcrystals (Ln: Y, Lu, Gd).

Inorganic host matrices provide a tunable luminescence environment for lanthanide ions, allowing for the modulation of upconversion luminescence (UCL) properties. AREF4 (A = alkali metal, RE = rare earth) have a low phonon energy and a high optical damage threshold, making them widely used as the host matrix for UCL materials. However, the impact mechanism of alkali metal ions and lanthanide lattice ions on transient UCL dynamics in AREF4 remains unclear. This study utilized a high-power nanosecond-pulsed laser at 976 nm to excite Yb-Er codoped NaLnF4 and LiLnF4 (Ln: Y, Lu, and Gd) microcrystals (MCs). All samples exhibit multiband emission, and the transient UC dynamics are discussed in detail. Compared with LiLnF4, NaLnF4 has higher UC efficiency and red to green (R/G) ratio. Lanthanide ions (Y, Lu, and Gd) affect the energy transfer (ET) distance in Yb-Er codoped systems, thereby altering UC efficiency and the R/G ratio. The energy level coupling between Gd3+ and Er3+ prolongs the duration of the UC emission. Specifically, the red emission lifetime of NaGdF4 is five times longer than that of NaYF4. Our research contributes to exploring excellent alternative host matrices for NaYF4 in the fields of rapid-response optoelectronic devices, micro-nano lasers, and stimulated emission depletion (STED) microscopy.

Interfacial B-O bonding modulated S-scheme B-doped N-deficient C3N4/O-doped-C3N5 for efficient photocatalytic overall water splitting

Photocatalytic overall pure water splitting is a promising method for generating green hydrogen energy under mild conditions. However, this process is often hindered by sluggish electron-hole separation and transport. To address this, a step-scheme (S-scheme) B-doped N-deficient C3N4/O-doped C3N5 (BN-C3N4/O-C3N5) heterojunction with interfacial B-O bonds has been constructed. Utilizing Pt and Co(OH)2 as co-catalysts, BN-C3N4/O-C3N5 S-scheme heterojunction demonstrates significantly enhanced photocatalytic activity for overall pure water splitting under visible light, achieving H2 and O2 evolution rates of 40.12 and 19.62 µmol/h, respectively. Systematic characterizations and experiments revealed the performance-enhancing effects of the enhanced built-in electric field and the interfacial B-O bonding. Firstly, the strengthened built-in electric field provides sufficient force for rapid interfacial electron transport. Secondly, by reducing the transport energy barrier and transfer distance, the interfacial B-O bonds facilitate rapid recombination of electrons and holes with relatively low redox potential via the S-scheme charge-transfer route, leaving the high-potential electrons and holes available for H+ reduction and OH− oxidation reactions. Overall, the photocatalytic efficiency of BN-C3N4/O-C3N5 S-scheme heterojunction was significantly improved, making it a promising approach for green hydrogen production through overall pure water splitting.

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.

Tuning and high temperature fluorescence properties of LaPO4:Sm3+ nanophosphors

A series of LaPO4:x%Sm3+ nanophosphors were successfully synthesized through a one-step hydrothermal method, where the acidity of the reaction system was meticulously modulated without the addition of any organic compounds. The influence of pH values and Sm3+ doping concentration on the structure, morphology, and luminescent properties of LaPO4:x%Sm3+ was systematically investigated. The composition, structure, morphology, and luminescent properties of the products were characterized and analyzed using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM, EDS), transmission electron microscopy (TEM), and fluorescence spectrophotometry (FL). The results indicate that the acidity of the reaction system effectively influences the morphology and size of the nanophosphors, facilitating the controlled synthesis of nanorod-shaped, nano-spherical, and ellipsoidal phosphors. When the Sm3+ doping concentration is 2 %, the phosphors exhibit maximum luminescent intensity and fluorescence lifetime. The energy transfer between Sm3+ ions in LaPO4:x%Sm3+ is identified as electric dipole-electric dipole interaction, with a critical distance for energy transfer established at 1.593 nm. LaPO4:2%Sm3+ exhibits good thermal stability, characterized by a thermal quenching activation energy of 0.1660 eV. The main outcome of this research, LaPO4:2%Sm3+ phosphor, exhibits significant potential for use in optical sensors, as well as promising applications in solar cells and biological fields.

Upconversion-based hydrogel kit with Python-assisted analysis platform for sample-to-result detection of organophosphorus pesticide

On-site quantitative analysis of pesticide residues is crucial for monitoring environmental quality and ensuring food safety. Herein, we have developed a reliable hydrogel portable kit using NaYbF4@NaYF4: Yb, Tm upconversion nanoparticles (UCNPs) combined with MnO2 nanoflakes. This portable kit is integrated with a smartphone reader and Python-assisted analysis platform to enable sample-to-result analysis for chlorpyrifos. The novel UCNPs maximizes energy donation to MnO2 acceptor by employing 100 % of activator Yb3+ in the nucleus for NIR excitation energy collection and confining emitter Tm3+ to the surface layer to shorten energy transfer distance. Under NIR excitation, efficient quenching of upconversion blue-violet emission by MnO2 nanoflakes occurs, and the quenched emission is recovered with acetylcholinesterase-mediated reactions. This process allows for the determination of chlorpyrifos by inhibiting enzymatic activity. The UCNPs/MnO2 were embedded to fabricate a hydrogel portable kit, the blue-violet emission images captured by smartphone were converted into corresponding gray values by Python-assisted superiority chart algorithm which achieves a real-time rapid quantitative analysis of chlorpyrifos with a detection limit of 0.17 ng mL−1. At the same time, pseudo-color images were also added by Python in “one run” to distinguish images clearly. This sensor detection with Python-assisted analysis platform provides a new perspective on pesticide monitoring and broadens the application prospects in bioanalysis.

Synthesis and study of optical properties of a Gd3+-doped NaYF4 phosphor for phototherapy lamp application.

In recent trends, radiation falls under the narrowband ultraviolet-B region (305-315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+-doped NaYF4 luminescent material synthesized for the first time using the low-temperature co-precipitation method. It crystallized into a face-centred cubic structure, as confirmed by X-ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as-prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet-B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole-dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low-cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

Exploration of Photoluminescence, Colorimetric, and Decay Performance of Sm-activated CaWO4 Ceramic.

This paper represents structure, photoluminescence, and colorimetric investigations of Sm-activated CaWO4 ceramic made with the help of a solid-state reaction process. Structures of the ceramics are examined through X-ray diffraction spectroscopy. It indicates that these materials have a tetragonal structure and I41/a space group without having any other secondary phase. Energy band gaps are increased with the higher concentrations of Sm dopants. Photoluminescence analyses show that concentration quenching is found at x = 0.02 Sm incorporated CaWO4. The critical distance of energy transfer is obtained as about 20Å. Q-value is observed approximately equal to 6 which denotes that dipole-dipole interactions occur in the materials that create the critical energy transfer distance in them. Chromaticity values are described in that the ceramics emit orange-red color as well as excellent colorimetric parameters. Quantum efficiency of x = 0.02 Sm composition in CaWO4 is measured under 405nm EX wavelength. Photoluminescence decay behaviors are observed and average lifetime values are evaluated.

Optical properties and Judd-Ofelt analysis of a novel Red-Emitting monoclinic Li3Ba2Gd3(WO4)8: Eu3+ phosphor

Red-emitting Li3Ba2Gd3(WO4)8: x at.% Eu3+ (0.5 ≤ x ≤ 10) phosphors were effectively produced using a conventional solid-state reaction method at high temperature in air atmosphere. The phosphors exhibited monoclinic crystalline structure with the C2/c space group and 2/m point group. The unit cell parameters determined from the Rietveld refinement for 3 at.% doped sample are a = 5.2149(4) Å, b = 12.7447(1) Å, c = 19.2058(3) Å, α = γ = 90°, β = a^c = 91.9315(1)° and Vcalc = 1275.748(2) Å3. Photoluminescence spectra, lifetimes, colour coordinates and purity, and temperature-dependent emission spectra have been systematically studied. Upon excitation at 395 nm, the phosphors displayed red emission with a peak centered at 614 nm, which was associated with the 5D0→7F2 electrical dipolar transition of Eu3+. At the same time, the influence of different Eu3+ ion concentration on the photoluminescence intensity is also discussed. The optimal concentration of Eu3+ ions in Li3Ba2Gd3(WO4)8 was found to be 3 at.%. The mechanism behind concentration quenching was ascribed to dipole–dipole interactions, and the critical distance for energy transfer among Eu3+ ions was determined to be 7.409 Å. The Judd–Ofelt theory was utilized to assess the intensity parameters and radiative properties. The fluorescence decay times were also determined for the different concentration levels of Eu3+ cations. The chromatic coordinates of Li3Ba2Gd3(WO4)8: Eu3+ were found to be (0.653, 0.345), closely resembling the standard red light (0.670, 0.330) and demonstrated high colour purity (98.42 %) under excitation at 395 nm. Moreover, the phosphors Li3Ba2Gd3(WO4)8: Eu3+ exhibited favorable thermal stability, characterized by an activation energy of 0.219 eV. The aforementioned findings indicate that the phosphors Li3Ba2Gd3(WO4)8 doped with Eu3+ have the potential to function as a red-emitting phosphor in near-ultraviolet-driven white light-emitting diodes.

Analysis of Structural, Photoluminescence, and Colorimetric Performance of Gd-Incorporated BNT Ceramic.

Structural, optical, photoluminescence and colorimetric analyses of Gd (1-5mol %) doped BNT ceramics synthesized by the solid-state reaction technique are reported. Structural analyses of all the samples are done by the X-ray diffraction method. It is shown that the samples have rhombohedral crystal structures with an R3C space group. The energy band gap of all the phosphors is computed from the UV-visible absorbance spectra. Photoluminescence behaviors are analyzed from the excitation along with the emission spectra of the prepared materials. The critical quenching concentration with the critical energy transfer distance is observed owing to the dipole-dipole interactions between the materials. Colorimetric analyses are carried out with the help of CIE chromaticity. Moreover, the color purity, correlated color temperature, color rendering index, and luminous efficiency of radiation values are evaluated by using the chromaticity coordinates.

N-Doped Carbon Nanowire-Modified Macroporous Carbon Foam Microbial Fuel Cell Anode: Enrichment of Exoelectrogens and Enhancement of Extracellular Electron Transfer.

Microbial fuel cell (MFC) performance is affected by the metabolic activity of bacteria and the extracellular electron transfer (EET) process. The deficiency of nanostructures on macroporous anode obstructs the enrichment of exoelectrogens and the EET. Herein, a N-doped carbon nanowire-modified macroporous carbon foam was prepared and served as an anode in MFCs. The anode has a hierarchical porous structure, which can solve the problem of biofilm blockage, ensure mass transport, favor exoelectrogen enrichment, and enhance the metabolic activity of bacteria. The microscopic morphology, spectroscopy, and electrochemical characterization of the anode confirm that carbon nanowires can penetrate biofilm, decrease charge resistance, and enhance long-distance electron transfer efficiency. In addition, pyrrolic N can effectively reduce the binding energy and electron transfer distance of bacterial outer membrane hemin. With this hierarchical anode, a maximum power density of 5.32 W/m3 was obtained, about 2.5-fold that of bare carbon cloth. The one-dimensional nanomaterial-modified macroporous anodes in this study are a promising strategy to improve the exoelectrogen enrichment and EET for MFCs.

Study of structural, luminescence and Judd-Ofelt calculations for Ce3+ doped ZnS phosphors for display applications

This paper discusses the luminescence properties of novel Zn(1-x)S: xCe3+ (x = 0, 0.01, 0.02, 0.03, 0.1, 0.2 and 0.3) prepared via conventional solid-state reaction method at low temperature. The XRD results revealed that all synthesized phosphors have hexagonal structure. The strain was calculated using size-strain plot (SSP) method. The FTIR study identifies the various vibrational modes present in the synthesized phosphors. The structural and luminescence characteristics of the prepared samples were enhanced by Ce3+ substitution. The optical band gap energies were found to be decreasing with Ce3+ substitution. The optimal Ce3+ content for superior blue emission is found to be x = 10 mol %. The blue emission supports the incorporation of Ce3+ ions within the ZnS lattice, which is again confirmed by Ω2, Judd-Ofelt intensity parameter. The high value of Ω2 indicates the symmetry of site occupies of Ce3+ ions are lower. The obtained critical distance of energy transfer between Ce3+ ions is calculated to be 6.3095 Å, which implies that the exchange interaction mechanism is a multipolar exchange. The high efficiency, branching ratio, stimulated cross section and the optical parameters indicate that the prepared phosphor materials have efficient blue light emission for display applications.

Research on X-ray-based energy conversion technology and assessment of application prospect

A new type of wireless energy transfer (radiation energy to electricity) power system is proposed for small-scale distributed energy utilization. To utilize radiation energy efficiently, energy conversion technologies based on different conversion modules and dissimilar material combination schemes are used. A variety of schemes such as single photovoltaic cell and single/multilayer fluorescent layer integrated with photovoltaic cell are designed. The maximum power density ranges from 7.93 nW/cm3 (tube voltage: 30 kV, tube current: 1 mA) to 6.7 µW/cm3 (tube voltage: 110 kV, tube current: 1 mA). After the structure layout of the system is matched and optimized, the maximum output power in radio-luminescent mode can be much higher than that in radio-voltaic mode. In particular, the maximum output power of conversion modules with a stacked layer can be increased by more than 36 times in radio-luminescent mode compared to radio-voltaic mode. At the same time, the effect of the distance of wireless energy transfer on the output performance of the energy conversion module is analyzed. To adjust the radiation intensity and field parameters better, X-ray tube is used as the radiation excitation source for performance testing and analysis. The performance attenuation of different energy conversion modules is similar when responding to X-ray over long distances. Compared with the radio-voltaic mode, the findings of this paper show that the output power of the system based on the radio-luminescent mode can be an order of magnitude higher.

Exploring the binding behaviors between nisoldipine and bovine serum albumin as a model protein by the aid of multi-spectroscopic approaches and in silico

Bovine serum albumin (BSA), a model protein was used to evaluate the binding behavior of nisoldipine and human serum albumin by a series of experiments and in silico in this article. The outcomes suggested that nisoldipine and BSA formed the nisoldipine-BSA complex with a molar ratio of 1:1, caused the fluorescence quenching of BSA, which quenching mechanism was attributable to static quenching. The binding constant of the nisoldipine-BSA complex was (1.3–3.0) × 104 M−1 at 298–310 K, indicating that nisoldipine on BSA protein had a moderate affinity. During the complexation of nisoldipine with BSA, nisoldipine can spontaneously insert into the site II (subdomain III A) of BSA and the distance of energy transfer from donor group in protein to acceptor group in nisoldipine was 3.21 nm, which led to the change in the hydrophobicity of the microenvironment surrounding Trp residues and in the secondary structure of BSA. Additionally, the findings also confirmed that the hydrogen bond and van der Waals force were responsible for forming the nisoldipine-BSA complex and the complexation process was a spontaneous exothermic process. Communicated by Ramaswamy H. Sarma

A study on structural and luminescence properties of novel orange-red emitting Sm3+ doped Sr3LiSbO6 nanorod phosphor with high color purity for W-LEDs

Being a simple synthesis technique, solid state reaction (SSR) method seldom generates 1D nanorod structured phosphors. In this article, we present a systematic study on the structural, morphological and spectroscopic properties of double perovskite type Sr3LiSbO6:Sm3+ phosphors prepared by the conventional SSR method. X-ray diffraction (XRD) analysis confirm the successful synthesis of hexagonal structured Sr(3−x)LiSbO6:xSm3+(x = 0,0.06,0.08,0.1,0.2,0.4 mol) phosphors and Fourier-Transform Infrared spectra (FTIR) revealed the molecular vibrations present in the samples. The surface morphology was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis. The TEM images illustrate the one – dimensional nanorod structure of the phosphor with an average diameter of 35 nm and length of 350 nm. In photoluminescence (PL) spectroscopy, under an excitation of 406 nm the characteristic emissions at 564, 601, 649 and 710 nm, which correspond to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 respectively of Sm3+ were obtained with strong orange - red emission at 601 nm. The concentration quenching was observed at x = 0.1 mol and the critical distance for energy transfer between Sm3+ ions was calculated to be 14.32 Å. The energy transfer mechanism was determined to be dipole-dipole interaction. The decay analysis confirms the shorter life time of the activator ions in the microseconds (µs) range. The estimated CIE coordinates are (0.6057, 0.397) in the warm CCT region with 100 % color purity. Hence these results suggests that Sm3+ doped Sr3LiSbO6 to be a potential orange-red nanorod phosphor in the design of various photonic devices such as phosphor converted LEDs (pc- LEDs).

Exploration of crystal structure, and luminescence behaviors of Terbium-activated CaWO4 phosphor

This manuscript includes structural, optical, photoluminescence, and thermoluminescence behaviors of Terbium incorporated CaWO4 samples with nominal compositions of Ca1-xTb2x/3WO4 (x = 0.01, 0.02, 0.03, 0.04, 0.05) prepared by the traditional solid-state reaction route. Results found from the Rietveld refinements of X-ray diffraction patterns confirmed that all the samples have tetragonal crystal structures with I41/a space group. The variation of unit cell volume with the compositions shows an anomaly at x = 0.03. Band gap energy values of these synthesized samples are found from the UV–Visible absorbance spectra with increasing order. Photoluminescence behaviors, as well as the FWHM values, are analyzed from the excitation along with the emission spectra. Critical quenching concentration at x = 0.03 with a critical energy transfer distance of ∼ 20 Å caused by the dipole-dipole interactions is found in these spectra. CIE Chromaticity coordinates are indicated the green emission color of all the prepared samples with high color purity, correlated color temperature, color rendering index, and luminous efficiency of radiation values. Quantum efficiency of the material with x = 0.03 Tb concentration is observed under 255 nm excitation wavelength. PL decay analyses of the phosphors are carried out and the average lifetime values are calculated. Thermoluminescence spectroscopy of x = 0.03 irradiating by 15 min of UV dose is described as the lower UV dosimetry and second-order kinetics of the material.

Orange-red emitting Sr3LaTa3O12:Sm3+ phosphors with perovskite structure and high thermal stability for w-LEDs

A novel layered perovskite tantalate phosphor Sr3LaTa3O12:Sm3+ (SLTO:Sm3+) with orange-red emission was obtained for the first time via the solid-phase synthetic method. The phase purity, surface morphology, element distribution and luminescent properties of the SLTO:xSm3+ (x = 0.01 mol%–0.30 mol%) phosphors were investigated. Under 408 nm excitation, the optimum doped SLTO:0.10Sm3+ phosphor emits orange-red light at 598 nm with the highest emission peak (4G5/2 → 6H7/2). The critical energy transfer distance is 1.687 nm. The prepared SLTO:0.10Sm3+ phosphor has excellent thermal stability with temperature quenching temperature (T0.5 > 500 K) and high activation energy (Ea = 0.25 eV). Through calculation, the chromaticity coordinates of all samples are concentrated in the orange-red area, and the color purity reaches 99%. The fabricated white light-emitting diode (w-LED) has a good correlated color temperature (5132 K), a high Ra (89), and the CIE chromaticity coordinates (0.340, 0.327). Consequently, the superiority of orange-red-emitting tantalate SLTO:Sm3+ phosphors for w-LEDs is demonstrated.

Highly efficient and low operation voltage hybrid solution-processed WOLEDs based on wide FWHM blue TADF and red phosphorescent emitters

Recent developments in the field of thermally activated delayed fluorescence (TADF) emitter have led to significantly improved performances of hybrid solution processing prepared white organic light-emitting diodes (s-WOLEDs). Importantly, wide coverage of electroluminescent spectra and balanced transfer of carriers are conclusive factors to obtain high quality lighting sources. This paper demonstrated high quality s-WOLEDs grounded on blue TADF and red phosphorescent emitters. In optimal WOLED, Förster energy transfer (ET) distance and ET rate were calculated to be 1.81 nm and 1.29 × 106 s−1, respectively. Also, exciplex host were employed to decrease operation voltage and modulate carriers' distribution. The fabricated optimal solution-processed warm white electroluminescence device exhibited high color rendering index of 80 and maximum luminescent efficiencies up to 29.22 cd A−1, 28.68 lm W−1 and 13.5%. Furthermore, the Commission Internationale de I'Eclairage coordinates of this device are (0.39, 0.41) at the current density of 10 mA cm−2, while the turn-on voltage of this device is 3.0 V.

Photoluminescence Studies of Europium Doped Di-Strontium Magnesium Silicate Phosphors

This article reports the study of photoluminescence spectra of Di Strontium Magnesium Silicate (Sr2MgSi2O7) doped with various concentration of Europium (Eu3+) prepared using solid-state reaction technique. The doping concentration (s) of Eu3+ were 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 mol% respectively. Excitation spectrum monitored at 620 nm wavelength that exhibited two prominent peaks centered at 256 nm and 277 nm. Peak observed at 277 nm was more intense therefore the emission spectra were monitored at 277. Emission Spectra of all the samples revealed intense peaks centred at 607, 618 and 637 are attributed to 5D0 7F2 of Europium (III) ions accommodated at various lattice sites having different energies. Overall emission was found in the red colour region which was confirmed using a CIE chromaticity diagram with coordinate (0.4805, 0.3763). Critical distance for energy transfer in the concentration, beyond which concentration quenching occurred in PL spectra, was calculated. In this case, the critical distance was found to be 19.87 Å, therefore the mechanism involved in concentration quenching of Sr2MgSi2O7 doped with 2.0 mol % of Europium (III) must be only multipole-multipole exchange whereas the exchange interaction is ineffective.