Photoluminescence Investigations Research Articles

Hazardous 2,4,6-Trinitrophenol (TNP) Detection in Water by Amine and Azine Functionalized Metal-Organic Framework.

A Zn(II)-based metal-organic framework (MOF) decorated with amine and azine functionalities, TMU-17-NH2 (formulated as [Zn(H2ata)(L)].2DMF; L = 1,4-bis(4-pyridyl)-2,3-diaza-2,3-butadiene and H2ata = 2-aminoterephthalic acid) has been successfully synthesized via a solvothermal method. According to crystallographic studies, the synthesized TMU-17-NH2 has three dimensional cuboidal structure with the pore surface decorated with free amine (-NH2) and azine (= N-N =) functional groups. The photoluminescence investigations proved that the synthesized MOF can be effectively utilized for selective detection of 2,4,6-trinitrophenol (TNP) in water with an apparent turn-off quenching response. Its limits of detection (LOD) for TNP was 9.4ppb and competitive nitro explosive testing confirmed its higher selectivity towards TNP (over other nitro explosives). Calculations based on density functional theory (DFT) and spectrum overlap were utilized to evaluate the sensing mechanisms. This MOF-based fluorescence sensing technique for TNP had a high sensitivity (Ksv = 3.26 × 104M-1).

Enhancing the Analysis of Eu3+ Photoluminescence in Coordination Compounds in the Solid State by Determining their Refractive Index

AbstractThis study is focused on determining the refractive index as a crucial parameter for evaluating the intrinsic quantum yield and the ligand sensitisation efficiency in solid‐state trivalent lanthanide coordination compounds. For this, eight trivalent europium complexes with phenyl‐terpyridine ([EuX3(ptpy)(L)], X=Cl− or NO3−, ptpy=4′‐phenyl‐2,2′ : 6′,2′′‐terpyridine, L=H2O or other molecules) were examined. Their refractive indices were determined using the Becke lines test by immersing transparent material in a series of media with known refractive indices. Using the set of media presented here, determining crystalline materials′ refractive indices from 1.41 to 1.73 with a step of 0.01 is possible. Assessment of the refractive indices of the complexes mentioned above allowed a comprehensive analysis of their photophysical properties in the solid state. Moreover, this method can be extrapolated for other solid‐state materials, offering valuable insights in the broader field of photophysics. In addition to photoluminescence investigations, the compounds presented were characterised by single‐crystal X‐ray diffraction (SCXRD), powder X‐ray diffraction (PXRD), Hirschfeld surface area analysis, UV‐Vis reflectance spectroscopy, hydrolysis sensitivity analysis, and simultaneous thermogravimetry and differential thermal analysis coupled with mass‐spectrometry (STA‐MS).

Tb-doped strontium aluminate nanophosphor: cytotoxicity, phytotoxicity, and bioimaging in plant cells

This study explores the novel application of terbium-doped strontium aluminate nanoparticles for fluorescence imaging in plant cells. The study encompasses microwave assisted solid state synthesis as well as the structural and optical characterization of terbium-doped strontium aluminate nanophosphors, their toxicity studies in plant and animal cells and their use as a fluorescent dye for plant imaging. The X-ray diffraction pattern analysis, along with Rietveld refinement studies, show the formation of SrAl2O4 as a dominant crystalline phase. Photoluminescence investigations demonstrate green emission from Tb3+ transition levels. In vitro biocompatibility of terbium-doped strontium aluminate nanophosphors was studied using L929 fibroblast cells. The plant Clitoria ternatea was used to examine phytotoxicity. The samples' potential for bioimaging was further investigated. Our findings reveal improved growth of seedlings, positioning these nanoparticles as promising tools in plant-related research. This study advances our understanding of nanoparticle-plant interactions and holds potential for transformative applications in agriculture.

High-Pressure Structural and Optical Studies of Pure Low-Dimensional Cesium Lead Chlorides CsPb2Cl5 and Cs4PbCl6.

We report high-pressure single-crystal X-ray diffraction, optical absorption, and photoluminescence investigations of all-inorganic perovskite-related materials CsPb2Cl5 and Cs4PbCl6. The crystal structure of CsPb2Cl5, composed of alternate layers of Cs+ cations and Pb-Cl frameworks, is stable under pressure up to at least 4.2 GPa. Because external stress is mainly absorbed by the Cs+ layers, the optical absorption edge of the crystal only slightly red-shifts with increasing pressure, which correlates well with a moderate shortening of the Pb-Cl bonds. A quite different response to pressure shows Cs4PbCl6, the crystal built of isolated PbCl64- octahedra and Cs+ cations. During the compression at around 3.4 GPa, the trigonal phase I, space group R3̅c, transforms to the orthorhombic phase II, space group Cmce, which at around 4 GPa transforms into phase III. On decompression, phase II is not restored, but phase III converts through a diffuse phase transition into another high-pressure phase IV, which is stable in a wide pressure range and transforms to the initial phase I only around atmospheric pressure. The red shift of the absorption edge and the profound modification of the absorption spectrum in phase II were ascribed to the deformation of the PbCl64- octahedra. The transition to phase III induces a blue shift of the absorption edge, while the transition to phase IV is associated with a large red shift. Photoluminescence was detected in phases I and II with the intensity quenched with increasing pressure.

Photoluminescence investigation of novel red emitting NaLa(1-x)MgTeO6: XSm3+ phosphor with high color purity for n-UV based warm WLEDS and anti-counterfeiting applications

Recently, red phosphors are extensively developed to find applications in phosphor converted white LEDs (pc-WLEDs) and anti-counterfeiting. In this work, samarium doped sodium lanthanum magnesium tellurate (NaLaMgTeO6:Sm3+) red emitting phosphors have been synthesized for the first time via solid state reaction method. Rietveld refinement of XRD pattern reveals monoclinic crystal structure of NaLaMgTeO6. Under 404 nm (6H5/2 → 4F7/2) n-UV excitation, NLMT:Sm3+ phosphor shows red emission at 643 nm (45/2 → 69/2) with color purity 100 % and the obtained CCT value corresponds to warm light source. Temperature-dependent PL analysis of NLMT:Sm3+ exhibits good thermal stability. The anti-counterfeiting security ink was developed using optimized phosphor and the information was encrypted on different surfaces using the prepared security ink. The encrypted data was decoded only by n-UV light. The aforementioned results revealed that NLMT:Sm3+ is a highly effective phosphor as a red component for pc-WLEDs and luminescent dye for anti-counterfeiting applications.

Disorder induced in GaN thin films by 200 MeV silver ions

GaN is a material of strategic importance due to its versatility in high temperature, radiation prone and chemical environments. The present study explores evolution of defects in GaN thin films in swift heavy ion radiation regime. GaN thin films grown by metal organic chemical vapour deposition techniques were irradiated with 200 MeV Ag ions at various fluences starting from 5 × 1010 to 5 × 1012 ions/cm2. Structural analysis revealed accumulation of lattice damage with increasing fluence. XRD analysis reveals that swift heavy ions of silver (Ag) deposit more energy into the target lattice, inducing localized damage at higher fluences, leading to broader peaks in irradiated samples. Recrystallization becomes evident at fluences of 1 × 1011 ions/cm2 of Ag 200 MeV ion irradiation, as indicated by a decrease in Full Width at Half Maximum (FWHM). The compressive stress identified in Raman analysis is associated with the c-axis and elevates the wavenumber of the E2(H) mode following Ag ion irradiation. Meanwhile, the pristine sample exhibits narrow A1 (LO) phonon mode peaks, indicating good crystallinity. Photoluminescence investigations demonstrate that Ag ions induce point defects in GaN, evident through analysis of YL, GL, and BL defect-related emission peaks following irradiation at various fluences.

Green, affordable, and unprecedented photoluminescence investigation on white emission of Y2O3:Clitoria ternatea floral extract complex to replace conventional Dy3+ doping for wLED

Green, affordable, and unprecedented photoluminescence investigation on white emission of Y2O3:Clitoria ternatea floral extract complex to replace conventional Dy3+ doping for wLED

Luminescence properties of CdF2 single crystals co-doped with Er3+ and Y3+ ions.

The luminescence properties of erbium and yttrium co-doped cadmium difluoride with three different concentrations of yttrium were investigated. First, we synthesized single crystal samples with good optical quality using the Bridgman technique. From the optical absorption spectra, recorded at room temperature, both in the ultraviolet-visible and infrared spectral ranges, Judd-Ofelt analysis was performed based on yttrium concentrations to predict the radiative properties of Er3+ luminescent ions. For the 10% optimum concentration of yttrium, a detailed photoluminescence investigation was carried out. We mainly explored green, red, and near-infrared fluorescence under different excitation wavelengths and presented their highlight spectroscopic characteristics. The desired transitions had relatively high emission cross-sections both under visible and near-infrared excitation. Optical gain followed a similar trend. Furthermore, the dynamic fluorescence study showed a significant increase in the measured lifetime under an 800 nm infrared excitation. The upconversion process under an 800 nm excitation produced quantum efficiency greater than 100% due to the contribution of more than one energy transfer mechanism.

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.

NanoGuard: Antibacterial marvels of strontium titanate – Synthesis, characterization, and multifunctional insights

This study presents a comprehensive exploration into the synthesis and multifaceted characterization of strontium titanate (ST) nanopowder via the solution combustion method. The investigation delves into the photoluminescent properties, electrochemical behaviors assessed through potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), as well as antibacterial characteristics of the synthesized nanoproduct. Through meticulous analysis involving powder X-ray diffraction (PXRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy (UV–vis), ST nanoparticles revealed intriguing features. PXRD unveiled a cubic crystal structure with a crystallite size of ∼ 11 nm, showcasing a crystallinity of 89.23. FESEM, UV–visible spectroscopy, and FT-IR studies uncovered irregularities in size, band gap properties, and the formation of M−O bonds within ST, with an Eg value of ∼ 3.0 eV. Photoluminescence investigations highlighted oxygen deficiencies within the ST material. Furthermore, corrosion inhibition efficiency was evaluated, demonstrating a maximum of 81.9 % at a concentration of 400 ppm, while antibacterial studies exhibited promising results against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, with zone of inhibitions (ZOI) measuring 8.00 ± 0.250 mm and 9.00 ± 0.000 mm, respectively. These findings collectively underscore the diverse potential applications of ST nanoparticles and offer valuable insights into their structural, optical, electrochemical, and antimicrobial properties.

Investigation of photoluminescence and thermoluminescence properties of UV& γ irradiated Li4SrCa(SiO4)2:Dy3+ phosphor

Investigation of photoluminescence and thermoluminescence properties of UV& γ irradiated Li4SrCa(SiO4)2:Dy3+ phosphor

A study of morphological, optical, and photoluminescence properties of ZnS thin films doped Mn and ca

In this study, zinc sulfide (ZnS) thin films were deposited via physical vapor deposition (PVD) under high vacuum conditions, incorporating dual dopants manganese (Mn2+) and calcium (Ca2+). Morphological examination by AFM revealed that Mn2+ promoted a uniform and smooth film structure, whereas Ca2+ induced surface roughness. Optical characterization using ultraviolet–visible spectroscopy showed high transparency in the visible range, with doping leading to significant alterations in the bandgap energy. Photoluminescence investigations displayed prominent emission peaks at 385 nm, 448 nm, and 560 nm, characteristic of ZnS bandgap emissions, as well as an additional peak at 600 nm due to the novel dopant's influence. X-ray fluorescence (XRF) and Fourier transform infrared (FTIR) analyses verified the presence of ZnS and other constituents. Doping improved the optical and luminescent characteristics, offering potential for use in optoelectronics, light-emitting diodes (LEDs), and advanced technology development. This customizable approach to ZnS thin films presents innovative opportunities within material science and device manufacturing.

A g‐C3N4/PANI S‐scheme heterojunction with face‐to‐face structure to improve the anticorrosion property on Q235 steel and enhanced mechanism study

AbstractIn photocatalytic anticorrosion perspective, the migration rate of excited electrons from surface layers to substrate steels restricted the performance of g‐C3N4 due to the high resistance between interface of g‐C3N4 layers and adhesive layers. Herein, an S‐scheme g‐C3N4/polyaniline (PANI) heterojunction with face‐to‐face structure was established by a secondary calcining method. The as‐prepared heterojunctions were applied to protect Q235 carbon steel, and the results showed that the anticorrosion performance of S‐scheme g‐C3N4/PANI heterojunction is much higher than that of g‐C3N4 and PANI coating layers according to salt spray test. Photocurrent intensity indicated that the optimum amounts of g‐C3N4 and PANI were 0.06 and 0.09 mL/cm2, which are benefit for the transport of excited electrons due to the optimum thickness of coating layers. Furthermore, the S‐scheme g‐C3N4/PANI heterojunction can promote the separation rate of charge carriers and suppress the recombination rate at the same time, which are inferred from photocurrent intensity, electrochemical impedance spectra, super‐depth‐of‐field microscope, and photoluminescence investigation. In the last, the enhanced anticorrosion performance of S‐scheme g‐C3N4/PANI heterojunction with face‐to‐face structure was deduced according to mentioned characterization.

Combustion synthesis, structural and photoluminescent investigations of Eu3+ activated crystalline Ba2BiV3O11 nanomaterials for multifunctional applications

Nanocrystalline Ba2BiV3O11 phosphor activated with lanthanide ion (Eu3+) has been successfully developed via a solution combustion approach. Various characterization techniques were implemented to explore the crystal structure, morphological behavior, photoluminescence, and chromatic aspects of Eu3+: Ba2BiV3O11 nanophosphors. Rietveld refinement was exercised to attain the phase purity and various crystallographic parameters. Transmission Electron Microscopy (TEM) technique was employed to analyze the crystallite size of the developed nanocrystals which is also in agreement with the size calculated from Scherrer formalization and W-H (Williamson-Hall) plot. Morphological behavior was studied with the help of Scanning Electron Microscopy (SEM) measurements. The most intense peak centered at 622 nm (5D0 → 7F2) in emission spectra was noted for Eu3+: Ba2BiV3O11 nanophosphors under 348 nm excitation. Kubelka-Munk function computed the Egap for the host along with the optimized sample and the outcomes evolved as 3.47 eV and 3.41 eV, respectively. Auzel’s model was executed to attain the radiative lifetime (1.3467 ms) for 5D0 electronic state. The CIE coordinates (x = 0.5990, y = 0.4003), CCT values (1710 K), quantum efficiency (87 %), and emission of bright red light indicate the promising behavior of Ba2Bi0.9Eu0.1V3O11 nanophosphor to use in the imaging applications, wLEDs, temperature sensing, and solid-state lighting (SSLs) appliances.

Chemical tuning of photo- and persistent luminescence of Cr3+-activated β-Ga2O3 by alloying with Al2O3 and In2O3

An effect of alloying of the monoclinic β-Ga2O3 with Al2O3 and In2O3 on the photoluminescent, thermoluminescent and persistent luminescent properties of Cr3+ ions has been comprehensively investigated. For this purpose, various series of Cr3+ and Ca2+ co-doped microcrystalline phosphors were synthesized by the solution combustion method, including pseudobinary compounds like (Ga-Al)2O3 with up to 20 % Al and (Ga-In)2O3 with up to 50 % In as well as pseudoternary compounds (Ga-Al-In)2O3 with balanced proportion of Al, Ga and In. The phase composition and crystal structure of the obtained materials were examined by X-ray powder diffraction technique. Detailed luminescence studies were conducted for the (Ga-Al)2O3 and (Ga-In)2O3 compounds which exhibited a single-phase monoclinic structure. Low-temperature and time-resolved photoluminescence investigations of the Cr-doped pseudobinary compounds unveiled several types of Cr3+ centres, attributed to the Al-, Ga- and In-centred octahedra in the studied alloys. The obtained results underscore the benefit of bandgap engineering through alteration in the host lattice chemical composition for efficient tuning of the thermoluminescent and persistent luminescent properties of the near-infrared-emitting β-Ga2O3:Cr based phosphors. Furthermore, it was demonstrated that modification of the chemical composition of the host lattice also adjusts the thermometric performance of the studied phosphors. Indeed, the specific sensitivity of the β-Ga2O3:Cr3+ decay time luminescence thermometer showed nearly twofold enhancement when the host lattice was alloyed with 30 % of In2O3.

Synthesis, characterization, and photoluminescence investigations of Al/Co-doped ZnO nanopowder

Present research describes the use of solution combustion to create ZnO nanoparticles doped with Co and Al. The studies revealed that the synthesized Al/Co-doped ZnO nanopowder has a narrower size distribution, controllable shape, and high crystallinity. Powder X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), and photoluminescence (PL) spectral techniques were utilized to characterize the as-prepared materials. Interestingly, Al-doped ZnO nanoparticles' UV emission peak location showed greater intensity than Co-doped ZnO, which is explained by an increase in non-radiative recombination. The energy gap plot calculates the Tauc gap, along with the color information defined by the CIE. The doping components were combined through mechanical mixing, and their impact on the effectiveness of the electromagnetic interference (EMI) shielding was examined.

Extending Infrared Emission via Energy Transfer in a CsPbI3-Cyanine Dye Hybrid.

Directing energy flow in light harvesting assemblies of nanocrystal-chromophore hybrid systems requires a better understanding of factors that dictate excited-state processes. In this study, we explore excited-state interactions within the CsPbI3-cyanine dye (IR125) hybrid assembly through a comprehensive set of steady-state and time-resolved absorption and photoluminescence (PL) experiments. Our photoluminescence investigations reveal the quenching of CsPbI3 emission alongside the simultaneous enhancement of IR125 fluorescence, providing evidence for a singlet energy transfer. The evaluation of both photoluminescence (PL) quenching and PL decay measurements yield ∼94% energy transfer efficiency for the CsPbI3-IR125 hybrid assembly. Transient absorption spectroscopy further unveils that this singlet energy transfer process operates on an ultrafast time scale, occurring within 400 ps with a rate constant of energy transfer of 1.4 × 1010 s-1. Our findings highlight the potential of the CsPbI3-IR125 hybrid assembly to extend the emission of halide perovskites into the infrared region, paving the way for light energy harvesting and display applications.

The Sr(La1-xTbx)AlO4 (x= 0–1) type layered perovskite: Full substitution of La site, restrained photoluminescence concentration quenching, and novel long afterglow luminescence

A series of Tb3+ substituted layered perovskite Sr(La1-xTbx)AlO4 (x = 0–1) was synthesized via solid-state reaction. The influence of Tb3+ on the phase, structure, photoluminescence, and long afterglow properties of the SrLaAlO4 product was investigated. The fully substituted product SrTbAlO4 was found to be isostructural with its SrLaAlO4 counterpart, and the crystal structure parameters were first reported in this work. Photoluminescence investigation found that benefiting from the unique layered crystal structure, the activator Tb3+ was well separated and the optimal doping concentration was found to be as high as 20 at%. Except for photoluminescence, the products simultaneously show long afterglow properties due to disorder cations distribution in the local structure and thus induced defect condition. When the UV light source is turned off, the afterglow luminescence of SrLaAlO4: 0.03 Tb3+ can last over 1 h. The trap distribution of SrLaAlO4: Tb3+ was analyzed in detail by thermoluminescence. The trap depth is calculated to be around 0.7–0.81 eV, the value of which highly coincides with the ideal energy level for trapping and releasing electrons at room temperature. On the basis of the experimental results, the mechanism of long afterglow luminescence of SrLaAlO4: Tb3+ is elaborated and discussed.

Dual effect to improve the electrical properties of SZO films grown by nitrogen pneumatic spray pyrolysis.

The principal aim of this study is to reduce considerably, via Sn doping, the resistivity of ZnO thin films prepared by simple, flexible, and cost-effective nitrogen pneumatic spray pyrolysis (NPSP) method on glass substrates at a temperature of 400°C. Different Sn content was tested (Sn/Zn = 0, 1, 3, 5 wt%) in an attempt to reduce the concentration of excessive oxygen atoms and create more free electrons. The microstructural, optical, morphological, and electrical properties of the films have been studied. The x-ray diffraction analysis demonstrated that tin-doped SZO films exhibited polycrystalline nature with a preferential orientation along (002) plane with the appearance of a new orientation (101) with the increase of Sn concentration leading then to bidirectional growth. The deposited SZO films showed an average optical transmittance of about 80% in the UV-visible region (200-800 nm) with optical band gap values at around 3.27 eV. Photoluminescence emissions of SZO samples presented three main peaks: near band edge emission, violet emission, and the blue-green emission. The surface morphology of the films obtained by scanning electron microscope (SEM) exhibited the change in morphology with increasing the Sn content. A minimum electrical resistivity value of about 17·10-3 Ω·cm was obtained for 3% SZO films. SZO films prepared by the NPSP method can be used as transparent window layer and electrodes in solar cells. RESEARCH HIGHLIGHTS: Highly oriented, conducting, and transparent Sn-doped ZnO films are successfully synthesized. The film growth orientation changed from mono-directional (002) axis to bi-directional (002) and (101) axis according to Sn doping. Ultraviolet and green emissions are noted by photoluminescence investigation. A minimum resistivity is observed for 3 wt% SZO film. The dual positive effect of the carrier gas used (N2) and Sn doping is confirmed.

Low‐Temperature Photoluminescence Investigation of Carbon‐Doped AlGaAs Grown by MOVPE on Vicinal Substrates

AlGaAs is promising absorber material for multi‐junction solar cells (MJSC) for its tunable bandgap to match various bandgap combination designs. However, the path to achieving high‐quality AlGaAs for solar cell application remains to be determined. In this study, we grow and characterize carbon‐doped p‐Al0.375Ga0.625As on exact and vicinal GaAs(0 0 1) substrates, using metal‐organic vapor phase epitaxy (MOVPE). Low‐temperature photoluminescence (PL) measurement is performed in the range from 6 K to 300 K. The Arrhenius plot of PL intensities reveals an increasing trend for non‐radiative recombination in conjunction with increasing miscut angle. The presence of atomic ordering that inversely correlates to the miscut angle is proposed to explain the PL linewidth and peak energy dependency on substrate orientation. The conflicting tendency of non‐radiative recombination and ordering with miscut angle are further validated using solar cell devices. A slightly vicinal substrate is recommended for AlGaAs solar cells according to our observation.