In this work, an in-depth numerical simulation based on drift diffusion and Poisson equation is undertaken to study the efficiency of new ninhydrin-glycine (NG) Schiff base complexes in monolayer ...organic light emitting diodes (OLED) devices. The Technology Computer-Aided Design (TCAD) simulation prove that NG complex with Al 3+ metal exhibit the maximum current and the lowest turn-on voltage compared to the three NG materials with Co 2+ , Zn 2+ and Fe 3+ metals. In the endeavors to achieve better efficiency, we have optimized the OLED device based on Al 3+ by improving the electron and hole injections. Thus, an enhanced luminescence of 6752 cd/m 2 and a power efficiency equal to 29.12 lmW −1 are achieved by introducing a PEDOT: PSS hole transporting layer and by replacing aluminum cathode with magnesium.
•This work studies the structural and photoluminescence properties of europium doped barium carbonate.•Barium carbonate materials have been prepared with high purity.•Our compound has high color ...purity.•Based on the optical results and CIE chromaticity diagram, the Eu3+ doped BaCO3 phosphor material can be considered as good candidate for red luminescence applications.
Nanostructured powders of undoped and europium (Eu3+) doped barium carbonate (BaCO3) were prepared by the autocombustion method. We investigated the influence of Eu3+ doping on the optical properties of barium carbonate. The samples nanostructures were characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and photoluminescence (PL). The results obtained by XRD revealed that the samples consist of the BaCO3 phase with orthorhombic structure having the space group Pmcn, retaining this crystalline phase after doping with Eu3+. These products were found for undoped and BaCO3: Eu3+ nanoparticles with 56–71 nm and 49–60 nm ranges, respectively. SEM reveals that the barium carbonate nanoparticles had a spherical morphology. Symmetric stretches, asymmetric stretches, and in plane bending vibrations, and out of plane of CO32− complexes have detected. The photoluminescence of the obtained BaCO3:Eu3+ were studied. The CIE co-ordinates for the Eu3+ doped BaCO3 were x = 0.580 and y = 0.330. From the CIE chromaticity diagram for the emissions of Eu3+ doped BaCO3. The material has such color purity and reaches 76%. Thus, having color tenability and has been considerate as a candidate of the laser emission.
•Phosphate glasses doped with Sm-Eu were prepared by melt quenching method.•Structural and optical properties of the glasses have been investigated.•Judd–Ofelt analysis is carried out.•Sm-Eu co-doped ...phosphate glasses are promising materials for the development of red LEDs.
Phosphate glasses with chemical compositions of 74.5NaH2PO4–20ZnO–5Li2O–0.5Sm2O3 and 74NaH2PO4–20ZnO–5Li2O–0.5Sm2O3–0.5Eu2O3 were synthetized by melt quenching method. We investigated the influence of Sm3+/Eu3+ doping on the optical properties of phosphate glasses. X-ray Diffraction indicates that the samples have an amorphous structure. DSC measurements show a good thermal stability of phosphate glasses. Using the absorption spectra, Judd–Ofelt analysis was applied to absorption bands of Sm3+ (4f5) to carry out the three phenomenological parameters of Judd–Ofelt (JO). According to the obtained values of Ω2, Ω4 and Ω6, some radiative properties were theoretically determined. We report both the photoluminescence (PL) and the PL lifetime measurements of a prominent emission transition 4G5/2→6H5/2 (604nm) of Sm3+ both in absence and in presence of Eu3+. It is shown that Eu3+ ions act as sensitizers for Sm3+ ions and contribute largely to the improvement of the radiative properties of phosphate glasses. An improvement of the PL lifetime value after adding Eu3+ ions (4.58ms) is reported. The predicted lifetime (τrad) calculated by Judd–Ofelt theory and the experimental lifetime (τmeas) for the prepared phosphate glasses were compared with those of other works. Photoluminescence (PL) intensity of 4G5/2→6H5/2 (604nm), 4G5/2→6H7/2 (567nm), 4G5/2→6H9/2 (650nm) and 4G5/2→6H11/2 (706nm) and the quantum efficiency (η) for the excited 4G5/2 level were enhanced after adding Eu3+. The radiative properties obtained for (Sm, Eu) codoped phosphate glasses suggest that the present material can be a potential candidate for the development of color display devices.
Aqueous ruthenium (III) chloride (RuCl
3
.3H
2
O) solution (0.03 M) was sprayed on pre-heated ordinary glass substrates. Amorphous ruthenium oxide thin films were obtained, which were sulfurized ...under vacuum at several lower heat treatment temperatures (400, 450, 500 and 550 °C) in RTP oven. The XRD results indicated the appearance of the RuS
2
phase for all the sulfurization temperatures. The layer compositions were confirmed by EDS analysis. Monocrystalline and polycrystalline RuS
2
thin films were obtained. SEM images showed mix of morphologies (filament, particles, and clusters) with porous surfaces. High absorption coefficients were deduced. The obtained RuS
2
-thin films showed different direct band gaps (1.43, 1.80, 1.79, 1.83 eV), which make it a distinct energy conversion and storage material. The opto-electrical properties of the as obtained RuS
2
-thin films make them among the best candidats for several applications, such as low cost material for low cost solar cells, and for alkaline hydrogen evolution electrocatalysts.
Phosphate glass with different Al2O3 and Na2CO3 compositions 80NaH2PO4-(20-x) Na2CO3-xAl2O3 with a step from 0 to 4 were prepared through melt quenching technique furnace at 900 °C. In order to ...determine the structure and microstructure modification of the samples after heat treatment the IR and Raman spectroscopy were performed. The X-ray diffraction (XRD) result shows an amorphous character of the prepared glass. The result obtained by differential scanning calorimetry (DSC) reveals a good thermal stability in the temperature range of 25 to 400 °C. The impedance Nyquist diagrams were investigated and modeled by resistors and constant phase elements (CPE) equivalent circuits. These measurements show a non-Debye type dielectric relaxation. Both AC and DC conductivity, dielectric constant, and loss factors were determined. Thermal activation energies were also calculated. A changes in the electrical conductivity and activation energy depend upon the chemical composition were observed. Also, a transition in the conduction mechanism from ionic to mixed ionic polaronic was noted. In the same line, electrical modulus and dielectric loss parameters are also deduced. Their frequency and temperature dependency exhibited relaxation behavior. Likewise, activation energies value obtained from the analysis of M’’ and those obtained from the conductivity are closes, which proves the optimal character of the preparation conditions.
Our present study focuses on examining the thermal, structural and luminescent characteristics of sodium barium metaphosphate glasses doped with Sm3+. Glass samples with molar compositions (100 − ...y)(50P2O5)–(50-xNa2O)–(xBaO)–ySm2O3, where x = 20, 25, 30, 35, 40 and y = 0.3 and 1% were first synthesized by conventional melt quenching and later dehydroxylated under a constant N2 flow to ensure final glasses with a very high degree of chemical and optical homogeneity and free of water. Upon the addition of BaO and Sm2O3, refractive index, molar mass, density, glass transition temperature and dilatometric softening temperature exhibited an increase, whereas the coefficient of thermal expansion showed a decrease. The FTIR spectra analysis reveals a network depolymerization that intensifies with rising BaO concentration, ultimately transitioning from a modifier oxide to a glass-forming element, at higher BaO concentrations. All doped samples exhibited prominent absorption bands in the visible (VIS) and near-infrared (NIR) regions, as revealed by the optical absorption spectra. The Na2O modifier demonstrated greater influence on Sm3+ emission compared to BaO, a phenomenon that can explained by the moderation of the local ligand field strength resulting from this substitution. With an increase in Sm2O3 concentration from 0.3 to 1 mol%, the experimental lifetimes of the 4G5/2 level decrease, primarily attributed to the presence of energy transfer mechanisms. A discussion of Judd–Ofelt parameter analysis and glass radiation properties will be presented.
Magnesium oxide (MgO) thin films with different magnesium concentrations (Mg2+ = 0.05, 0.1, 0.15 and 0.2 mol·L−1) in a spray solution have been successfully grown using a spray pyrolysis technique. ...X-ray diffraction (XRD), Maud software, FTIR spectroscopy, a confocal microscope, Wien2k software, spectrophotometry and a Photoluminescence spectrometer were used to investigate the structural, morphological and optical properties. XRD analysis revealed a better crystalline quality of the MgO thin layer synthesized with Mg2+ = 0.15 mol·L−1, which crystallized into a face-centered cubic structure along the preferred orientation (200) lattice plan. The enhancement of the crystalline quality for the MgO thin film (Mg2+ = 0.15 mol·L−1) was obtained, which was accompanied by an increment of 94.3 nm of the crystallite size. No secondary phase was detected and the purity phase of the MgO thin film was confirmed using Maud software. From the transmission spectra results, high transparent and antireflective properties of the MgO thin film were observed, with an average transmission value of about 91.48% in the visible range, which can be used as an optical window or buffer layer in solar cell applications. The films also have a high reflectance value in the IR range, which indicates that the highly reflective surface will prevent an increase in surface temperature under solar irradiation, which could be beneficial in solar cell applications. A direct band gap type was estimated using the Tauc relation which is close to the experimental value of 4.0 eV for optimal growth. The MgO material was tested for the degradation of methylene blue (MB), which reached a high photodegradation rate of about 83% after 180 min under sunlight illumination. These experimental trends open a new door for promising the removal of water contaminants for photocatalysis application.
A combined theoretical and experimental study has been performed on four synthesized Schiff base complexes derived from ninhydrin–glycine ligand (NG) with Co(II), Zn(II), Al(III) and Fe(III) metal ...cations. The FT-IR spectra clearly showed that the complexes behave as tridentate monobasic ONO donor ligand. Furthermore, the energy levels of HOMO, LUMO levels and band gap were determined using the Density Functional Theory (DFT). The experimental and theoretical optical investigation showed that the complexes have good absorption in visible region and blue emission with a maximum emission wavelength located at 436 nm, 471 nm and 478 nm for Co–NG, Zn–NG and Al–NG, respectively. Moreover, based on Marcus theories, we estimated the rate of electron and hole charge transfer. As a result, Al–NG complex has the better electron and hole transport than the other complexes with K
et
= 4.10 × 10
14
and K
ht
= 4.86 × 10
14
, respectively. Finally, to predict the possibility of introducing the studied complexes in light emitting diode (LED) devices, the electron and hole injection barriers were estimated. The found results are interesting which make the studied complexes potential candidates for LED application.
Europium and Terbium co-doped phosphate glasses with a chemical composition of 80NaH2PO4–18Na2CO3–2Al2O3, which have been named PNA, were well produced with melt-quenching technique. We studied the ...structural and optical properties of the material. According to the XRD pattern, all the samples have an amorphous structure. After adding Tb3+, it was revealed that the photoluminescence (PL) intensity of the 5D0 →7F2 transition increased. It was observed that the Tb3+ ion functions as a sensitizer for the Eu3+ ion, and significantly enhances the spectroscopic features of Eu-doped PNA. We demonstrated the possibility of excitation transfer from Tb3+ to Eu3+. The radiative lifetime (τR) calculated from Judd-Ofelt (J-O) theory, and the, empirically discovered, measured lifetimes (τmes) were compared for Eu-doped PNA and (Eu; Tb) co-doped PNA. The results reveal that the quantum efficiency (η) was found to increase after adding Tb3+ from 87 to 94% for the 5D0 →7F2 transition. The energy transfer was identified and explained both experimentally using the excitation and emission spectra and theoretically using the J-O theory. The results of the CIE chromaticity coordinates of (Eu, Tb) co-doped PNA were found in the white region, which suggests a significant promise in field emission displays.
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•Eu-doped PNA (0.5 mol%), Tb-doped PNA (0.5 mol%), and (Eu; Tb) co-doped PNA (0.5 mol%; 0.5 mol%), where PNA has a chemical composition of 80NaH2PO4–18Na2CO3–2Al2O3, synthesized using a melt quenching technique.•The energy transfer from Tb3+ to Eu3+ ions was discussed experimentally by PL and PLE measurements and theoretically by J-O theory.•The possibility to obtain white light from the combination of blue, green, red light of Tb3+ and red light of Eu3+.•The prepared sample is promising material for the development of color display devices.
In this work, the main objective is to enhance the gas sensing capability through investigating the effect of Al and Mg doping on ZnO based sensors. ZnO, Mg1% doped ZnO, Al5% doped ZnO and (Al5%, ...Mg1%) co-doped ZnO nanoparticles (NPs) were synthesized by a modified sol-gel method. The structural characterization showed the hexagonal crystalline structure of the prepared samples. Morphological characterizations confirmed the nanometric sizes of the NPs (27–57 nm) and elemental composition investigation proved the existence of Al and Mg with low concentrations. The optical characterization showed the high absorbance of the synthesized samples in the UV range. The gas sensing performances of the synthesized samples, prepared in the form of thick films, were investigated. Sensing tests demonstrated the high influence of the Al and Mg on the sensing performances towards H2 and CO gas, respectively. The 5A1MZO-based sensor exhibits high sensitivity and low detection limits to H2 (<2 ppm) and CO (<1 ppm). It showed a response around 70 (at 250 °C) towards 2000 ppm H2 and 2 (at 250 °C) towards CO.
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