Search

The current work focuses on the fabrication of pristine and metals (Co, Cu, Ni, Li, and Sn) doped β -PbO phase nanoparticles by cost-effective precipitation method. The properties of the produced nanoparticles were investigated using a variety of characterization techniques. The produced compound was a highly pure β -PbO phase, according to the XRD data. From the UV–vis DRS the obtained bandgap of pristine β -PbO, Co, Cu, Ni, Li, and Sn doped β -PbO was 2.68 eV, 1.88 eV, 2.01 eV, 2.65 eV, 2.64 eV, and 2.70 eV, respectively. The doped samples with the lowest photoluminescence (PL) intensities show the reduced photogenerated electron–hole pair recombination, which increased the photocatalytic activity of β -PbO nanoparticles. The study of the surface morphology by SEM reveals the irregular distribution of the particles. In both pristine and doped nanoparticles, EDX verifies the existence of the expected elements. In comparison to pristine β -PbO, all doped β -PbO nanoparticles have enhanced photocatalytic activity for the degradation of methylene blue (MB) dye under the irradiation of visible light. Among the doped nanoparticles, Cu and Co-doped β -PbO demonstrated particularly high performance. After 80 min of irradiation, Cu and Co-doped β -PbO showed 99.45% and 99.39% degradation rates of MB dye, compared to only 75.13% for pure β -PbO. Hence, the photocatalytic activity of pure β -PbO is boosted through metals doping due to bandgap narrowing, generation of impurity states, increased specific surface area, higher carrier concentration, reduced carriers recombination, the action of dopant ions, and microstructural changes.

This work presents a systematic first-principles study of the crystal structure, mechanical, electrical, optical, and thermodynamic properties of lithium- and calcium-based catalysts (Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 ) for the production of cubic boron nitride. The mechanical findings indicate that Ca _3 N _2 is identified as a ductile material, with a higher B/G (20.04) and Poisson’s ratio (0.48). The other three materials are recognized as brittle materials, with B/G less than 1.75 and Poisson ratio less than 1/3. The electrical discoveries show that Li _3 BN _2 has the widest band gap among the four catalyst materials, and the band gap of ternary catalyst materials (Li _3 BN _2 and Ca _3 B _2 N _4 ) is larger than that of corresponding binary catalyst materials (Li _3 N and Ca _3 N _2 ). The optical results reveal that Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 have sufficient energy to prevent charge carriers from being scattered or captured by material defects. The absorption peaks of Ca-based materials (Ca _3 N _2 and Ca _3 B _2 N _4 ) are significantly higher than those of Li-based materials (Li _3 N and Li _3 BN _2 ). In this frequency range, the light is the most difficult to pass through in Ca _3 N _2 and the easiest to propagate in Ca _3 B _2 N _4 . The connection between Li _3 N and Ca _3 N _2 bands is greater, while the Li _3 BN _2 and Ca _3 B _2 N _4 bands interact rather weakly. The thermodynamic conclusions demonstrate that the thermal stability of the four structures is as follows: Li _3 N< Ca _3 N _2 < Li _3 BN _2 < Ca _3 B _2 N _4 . The heat capacities of Li _3 N, Ca _3 N _2 , Li _3 BN _2 , and Ca _3 B _2 N _4 tend to approach _2 3.74, 52.05, 70.73, and 311.48 J·mol ^−1 ·K ^−1 , respectively.

Here we present the optoelectronic properties of pure inorganic lead-free halide perovskites in the form of Cs _2 AgBi X _6 ( X = Br, Cl, F, I) using the density functional theory calculations on cubic phase (Fm $\mathop{3}\limits^{̅}$ m) and tetragonal phase (I4/m). First, all the structures of the two phases were optimized at the PBE level. Structural, electronic, optical properties, phonon, and thermal properties of Cs _2 AgBi X _6 in cubic (Fm $\mathop{3}\limits^{̅}$ m) and tetragonal phases (I4/m) were obtained using the VASP code. Tetragonal phases of all compounds of the form Cs _2 AgBi X _6 , except Cs _2 AgBiBr _6, are reported here for the very first time. Among all the Cs _2 AgBi X _6 ( X = F, Cl, Br, I) structures, the cubic phase of Cs _2 AgBiBr _6 was seen to have the highest absorption coefficient along with prominent electronic features that are favorable for optoelectronic applications. Thus, the cubic phase of Cs _2 AgBiBr _6 was selected as the host lattice and bromine atoms were partly replaced with chlorine and iodine atoms. Electronic and optical properties of these mixed halide compounds of Cs _2 AgBiBr _6−x F _x , Cs _2 AgBiBr _6−x Cl _x, and Cs _2 AgBiBr _6−x I _x where x = 1, 2, 3, 4, 5 are investigated with hybrid functional HSE06 level. The electronic structure revealed that these mixed compounds exhibited indirect band gap nature regardless of the halide substitution (different x concentration) and the band gap of Cs _2 AgBiBr _6 could be varied with the substitutions of fluorine, chlorine, and iodine atoms. Our in-depth analysis shows that Cs _2 AgBiBr _6 and their mixed halides have the potential to become active double perovskite materials for photovoltaic applications and as photocatalysts for water splitting.

In this research work Fe and Ni co-doped Tin oxide (SnO _2 ) nanoparticles have been prepared by co-precipitation method. The samples were prepared at various combination of Fe and Ni from 0% up to 10%. The produced nanoparticles were studied by x-ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV–vis Spectrophotometer, Fourier Transformation Infrared Spectroscopy (FTIR) and Vibrating Sample Magnetometer (VSM). The XRD study reveals the formation of rutile structure of the undoped and doped SnO _2 nanoparticles with the average crystallite size of 1.5–10.8 nm. Metal oxide bonding is confirmed through FTIR measurement. Optical band gap redshift (3.9 to 3.64 eV) with doping of Fe and Ni atom is observed. SEM image confirms the formation of spheroidal nanoparticles and size of the nanoparticle varies from 36 to 15 nm. The VSM study shows the ferromagnetic phase transition at 7% Ni, Fe doped SnO _2 nanoparticles. This ferromagnetism arises for the oxygen vacancies and defect states. Further, increase of doping concentration of 10%, nanoparticles show the phase transition from ferromagnetic to paramagnetic. Such transition can be applicable in hyperthermia treatment and memory devices.

This study theoretically analyzed the optical properties and electric field enhancement of gold nanospheres. Based on numerical analysis, the gold nanospheres were coated experimentally with diallyldimethylammonium chloride (C _8 H _16 ClN) for targeted drug delivery. Numerically, a resonance peak for 10 nm nanospheres was observed at 510 nm. As the radius increased from 10 nm to 100 nm, the resonance peak shifted from 510 nm to 605 nm. The nanosphere radius also affected the extinction cross-section. The resonance peaks showed a red shift as the radius of the nanosphere increased. For experiment analysis, gold nanospheres were synthesized using a seed-mediated technique and then coated with different concentrations of C _8 H _16 ClN. The UV absorbance by the nanospheres increased with an increase in the concentration of C _8 H _16 ClN from 10 mg ml ^−1 to 20 mg ml ^–1 . UV–vis spectrum confirmed a rise in resonance peaks with increasing coating concentration. The coated gold nanospheres were used to deliver the doxorubicin-HCl (DOX-HCl) drug. Maximum drug release was observed when the temperature was set at 50 °C. It was concluded that the nanospheres, coated with 20 mg ml ^–1 of C _8 H _16 ClN, are excellent candidates for drug delivery applications. The gold nanospheres with a radius of 50 nm were best for target drug delivery, and the particles above 50 nm were best for thermal therapies for cancer treatment.

Here we report on ten water-soluble perylene bisimides that are functionalised with the amino acids L-alanine, L-aspartic acid, L-glutamic acid, L-phenylalanine, L-histidine, L-leucine, L-methionine, L-valine, L-tryptophan, and L-tyrosine. Reduction potentials, absoprtion and emission spectra, molar absorptivity, quantum yield, and rheology are obtained and the data interpreted for each species in aqueous solution or hydrogels in order to provide a comprehensive understanding of the subtle effects of amino acid functionalisation on the optoelectronic and supramolecular properties.

We present a theoretical method for calculating optical absorption spectra based on maximally localized Wannier functions, which is suitable for large periodic systems. For this purpose, we calculate the exciton Hamiltonian, which determines the Bethe–Salpeter equation for the macroscopic polarization function and optical absorption characteristics. The Wannier functions are specific to each material and provide a minimal and therefore computationally convenient basis. Furthermore, their strong localization greatly improves the computational performance in two ways: first, the resulting Hamiltonian becomes very sparse and, second, the electron–hole interaction terms can be evaluated efficiently in real space, where large electron–hole distances are handled by a multipole expansion. For the calculation of optical spectra we employ the sparse exciton Hamiltonian in a time-domain approach, which scales linearly with system size. We demonstrate the method for bulk silicon—one of the most frequently studied benchmark systems—and envision calculating optical properties of systems with much larger and more complex unit cells, which are presently computationally prohibitive.

WO _3 -based semiconductor materials are optimistic competitors for modern electronic devices because of their outstanding electronic and optical properties. Simulations on pure and Gd-doped WO _3 compositions were executed using Tran and Blaha modified Becke–Johnson approximation. Experimentally, thin films of these compositions were prepared using the chemically derived technique. X-ray diffraction spectra of thin films exhibited cubic structure having space group 221-Pm-3m in all compositions. Field emission scanning electron micrographs reveal the uniform growth of thin films with rod-like compact morphology. The density of states spectra for electronic properties demonstrate the main contribution of W- d and O- p for pure WO _3 with p-d hybridization while Gd containing composition provides an additional prominent contribution from f -orbital. Band structure shows an indirect transition for WO _3 and band gap values were observed as 1.73 eV which decreased with increment of Gd content. A significant change in thermoelectric parameters was observed with an increment of temperature and Gd doping. The maximum value of the refractive index was observed as 3.02 in the visible energy regime and tends to decrease in Gd containing compositions. The experimentally obtained maximum dielectric constant was observed as 7.89 for pure WO _3 and decreased to 4.58 for maximum Gd containing composition. Optical parameters like extinction, absorption coefficient, and optical conductivity show a sharp increment in visible energy region which make these compositions favorable for photovoltaic and optoelectronic applications. The experimentally obtained optical parameters are found in good agreement with simulated results obtained through TB-mBJ approximation.

In this study, four ZnO thin films were deposited on FTO substrates using the sol–gel dip coating method to examine their microstructural, morphological, and optical properties through various techniques. Three of them were subjected to ultraviolet (UV) light, magnetic field (MF), and a combination of UV and MF during deposition, referred as ZnO: UV, ZnO: MF, and ZnO: (UV+MF), respectively. The results obtained showed that the simultaneous UV and MF exposure improved the crystallinity and surface homogeneity of the as-deposited film. Moreover, ZnO: (UV+MF) film exhibited an average transparency of 80% in the visible region and a high optical bandgap (3.67 eV). Room-temperature photoluminescence (PL) spectra revealed a weak UV emission and a strong violet emission peaks for all films. However, the violet emission intensity being lower in ZnO: UV and ZnO: MF films due to a reduction in zinc interstitials (Zn _i ) defects, The simultaneous UV and MF exposure did not reduce Zn _i defects, and the violet emission intensity was almost identical to that of the untreated film. These findings suggest that the ZnO: (UV+MF) film can be a promising candidate for the development of ultraviolet and violet lasers and light-emitting diodes.

Computational materials science relies on simple, yet efficient, measures and indicators of the modeled materials’ properties. Ideally, the desired properties should be linked to such scalar quantities that can be obtained in polynomial time and efficiently integrated within automated high-throughput screening loops for screening and sorting out the evaluated materials to the desired categories. Here, we focus on the freestanding gapped 2D materials and scalar indicator of their band gap sensitivity to the presence of additional stacked 2D layer/s. The proposed measure uses only a freestanding model of a given material, and it is based on an automated integration of the electron density of frontier orbitals extending into the vacuum within the model unit cell. The usefulness and limitations of such an approach for materials pre-screening are demonstrated on a handful of 2D materials, like, e.g. MXenes, graphane, fluorographene, or, allotropes of phosphorus.

In this study, we report the fabrication and characterization of ${LaM}{O}_{3}$ $(M={Fe},{Cr},{Mn})$ perovskite thin films deposited on FTO substrates via electrophoretic deposition (EPD). The x-ray diffraction (XRD) patterns showed the formation of the orthorhombic structure for ${LaFe}{O}_{3}$ and ${LaCr}{O}_{3}$ films and the trigonal structure for the ${LaMn}{O}_{3}$ film. The field-emission scanning electron microscopy (FE-SEM) micrographs revealed nano-spherical particles with an average grain size of about 50 nm covering the ${LaMn}{O}_{3}$ surface with fewer porosities compared to the other films. Moreover, the ${LaMn}{O}_{3}$ film exhibited a higher transparency in the visible region (∼84%). The estimated bandgaps of ${LaFe}{O}_{3},$ ${LaCr}{O}_{3},$ and ${LaMn}{O}_{3}$ perovskite films were found to be 2.17, 3.18, and 2.92 eV, respectively. In addition, the refractive indices of all deposited films were calculated using five empirical models that relate the refractive index to the bandgap, which consistently revealed a decrease in refractive index with an increase of bandgap energy This study holds significant implications for the field of perovskite thin films as we contribute new insights into the fabrication of lanthanum-based perovskite thin films using the EPD technique. The comprehensive characterization of microstructural, morphological, and optical properties provides valuable information for understanding the structure-property relationship in these materials. Furthermore, the determination of bandgaps and refractive indices enhances our understanding of the optical properties of perovskite films. The findings from this study pave the way for potential applications in optoelectronic devices, where fine-tuning of material properties is critical for optimal device performance.

Quantum dots (QDs) have sparked great interest due to their unique electronic, optical, and structural properties. In this review, we provide a critical analysis of the latest advances in the synthesis, properties, and applications of QDs. We discuss synthesis techniques, including colloidal and hydrothermal synthesis, and highlight how the underlying principles of these techniques affect the resulting properties of QDs. We then delve into the wide range of applications of QDs, from QDs based color conversion, light-emitting diodes and biomedicine to quantum-based cryptography and spintronics. Finally, we identify the current challenges and future prospects for quantum dot research. By reading this review, readers will gain a deeper understanding of the current state-of-the-art in QDs research and the potential for future development.

Two-dimensional (2D)/quasi-2D organic-inorganic halide perovskites are regarded as naturally formed multiple quantum wells with inorganic layers isolated by long organic chains, which exhibit layered structure, large exciton binding energy, strong nonlinear optical effect, tunable bandgap via changing the layer number or chemical composition, improved environmental stability, and excellent optoelectronic properties. The extensive choice of long organic chains endows 2D/quasi-2D perovskites with tunable electron-phonon coupling strength, chirality, or ferroelectricity properties. In particular, the layered nature of 2D/quasi-2D perovskites allows us to exfoliate them to thin plates to integrate with other materials to form heterostructures, the fundamental structural units for optoelectronic devices, which would greatly extend the functionalities in view of the diversity of 2D/quasi-2D perovskites. In this paper, the recent achievements of 2D/quasi-2D perovskite-based heterostructures are reviewed. First, the structure and physical properties of 2D/quasi-2D perovskites are introduced. We then discuss the construction and characterizations of 2D/quasi-2D perovskite-based heterostructures and highlight the prominent optical properties of the constructed heterostructures. Further, the potential applications of 2D/quasi-2D perovskite-based heterostructures in photovoltaic devices, light emitting devices, photodetectors/phototransistors, and valleytronic devices are demonstrated. Finally, we summarize the current challenges and propose further research directions in the field of 2D/quasi-2D perovskite-based heterostructures.

In this study, Titanium dioxide nanostructures were hydrothermally synthesized at different temperatures 130, 170 and 200 °C. The structural properties and crystallite size of TiO _2 nanostructures were confirmed through XRD analyses. Moreover, the morphologies were confirmed using TEM analyses. These analyses confirmed the formation of single phase TiO _2 nanostructures. The average crystallite size for the TiO _2 nanostructures synthesized at different hydrothermal temperatures of 130, 170, and 200 °C was found to be 11.5 nm, 5.3 nm, and 5 nm, respectively. The impact of changes in these morphologies on the physical characteristics and photokilling activity of cancer cells has been studied. The results showed that the photokilling activity of TiO _2 nanostructures is morphology dependent, with TiO _2 nanowires having the highest activity and nanosheets having the lowest under our experimental conditions.

Polymer composites are recently introduced as flexible candidates for modern electronic devices. Transition metals oxides incorporated PVDF polymer composite thin films were successfully synthesized and investigated for an optical response. The effect of ZnO and NiO nanoparticles as PVDF fillers is studied in this work. Experimentally pure and doped PVDF uniform and evenly distributed thin films were synthesized by sol-gel based spin coating method. Structural studies were carried out with x-ray diffraction analysis which reveals the sharp traces of ZnO and NiO and endorses the presence of crystalline fillers in PVDF polymer composite thin films. The Field emission scanning electron microscope was used to examine the surface morphology of prepared thin films containing a smooth, uniform distribution and compact polymer traces. Refractive index, extinction, absorption coefficient, reflectivity, optical conductivity and real epsilon were extracted using spectroscopic ellipsometry. Enhanced response of optical parameters was observed in nanoparticles containing PVDF polymer composites. The absorption coefficient seems to increase with the increment of nano-filler contents, which makes these materials suitable for photovoltaic applications. The maxima of the refractive index were recorded as 1.6 for pure PVDF and 2.1 for maximum nano-filler content with an incredible shift to higher energy values. The optical conductivity was observed to increase with the incorporation of nanoparticles in PVDF. The maximum values of real epsilon were recorded as 2.3 for pure PVDF and 3.9 for the highest nano-filler containing composition. The increasing trend of real epsilon in nano-fillers containing compositions is attributed to the enhanced polarization and storage capability of these composites. The outcomes of this work are considered that ZnO-PVDF-NiO advanced polymer composites are promising candidates for enhanced modern electronic devices.

The pristine WO _3 (tungsten trioxide) and Cu/Ni Co-doped WO _3 nanoparticles were synthesized by the co-precipitation synthesis methods with fixed wt.% of nickel, i.e., 5 wt.%, and different wt.% of copper, i.e., 2, 3, 5 wt.%. The structural, optical and electrical properties, as well as the surface morphology were investigated thoroughly by various characterization techniques. All the doped/co-doped and un-doped samples had an orthorhombic structure, according to the XRD measurements. The XRD results further confirmed that the average crystalline size ranged from 46 to 25 nm after the dopant concentration was introduced. Reflectance spectroscopy was used to investigate the optical properties of the prepared nanomaterials and revealed that the optical band gap varied from 2.80 to 2.63 eV with dopant concentrations. The room temperature photoluminescence study showed that the emission peaks were observed in the visible region with slight peak shift towards short wavelength with dopant concentrations. The FTIR studies described the different mode of band related to a functional groups present in the materials and the stretching mode of O–W–W observed from 550 to 1050 cm ^−1 . The I-V studies confirmed that the prepared samples had a good ohmic contact behavior and the resistivity decreased from 6.3 × 10 ^−3 Ω.cm to 0.63 × 10 ^−3 Ω.cm with doping concentrations.

Mn-activated optical materials have been demonstrated to be promising for various applications such as light-emitting device, tunable lasers and smart sensors. Most of the candidates belong to the single crystals and crystalline powders, and few reports involve about the glass-derived materials. This letter reports the fabrication of active Mn-doped nanostructured glass sample via control of the crystallization of a typical gallogermanate glass. LiGa _5 O _8 and LiGaGeO _4 can precipitate after heat-treatment, and Mn centers selectively incorporate into the crystalline phase. Importantly, the luminescence can be switched from red to green colour and the intensity can be enhanced simultaneously. Furthermore, the luminescence properties can be tuned via control of the phase of the nanostructured glass.

The phosphors free of active dopants have been attracted much attention due to their interesting optical properties and potentials for construction of rare-earth free functional materials. In this letter, we report the construction of phosphor free of active dopants via nanocrystallization of glass. In a typical example, a single-phase Zn _2 GeO _4 phosphor is fabricated via controllable crystallization of the germinate glass. Intense green luminescence with the central wavelength at 523 nm can be realized in nanostructured glass and it is estimated to be ∼150 times higher than that of the as-made glass. The physical mechanism is associated with the formation of Zn related interstitial defects during the disorder-order phase transformation in glass. The progress in this work indicates that the avenue of glass crystallization provides an effective strategy for the development of novel active photonic materials free of active dopants.

Cerium oxide nanoparticles (CeO _2 NPs) of different ratios ( x = 5, 10, 15, and 20 in wt %) are successfully incorporated into chitosan (CS) to synthesize CeO _2 NPs/CS nanocomposites by solution cast method. FTIR and XRD analysis confirmed the effective incorporation of CeO _2 NPs into chitosan nanocomposites. TGA and DTG showed that the thermal stability of the as-prepared nanocomposites is improved. The CeO _2 NPs/CS nanocomposites exhibited enhanced light absorption capacity in the UV-visible range as x increases, owing to the CeO _2 NPs’ large bandgap. The transmittance of UV decreased for x = 10 and 15 nanocomposites. Light scattering enhanced for x = 5 and 10 nanocomposites, increasing reflectance. Compared to CS (5.3 eV), the optical energy bandgap lowers to 4.94 eV and 5.1 eV, respectively. Impedance spectroscopy research validates the impedance spectroscopy parameters’ dependency on CeO _2 NPs concentrations. Because of the growth of multiple polarization types, generating interfaces of numerous defects, and space charge polarization, the dielectric constant increases with increasing x (up to x = 15). The dc conductivity ( σ _DC ) and the frequency exponent ( S ) are estimated using the universal Josher’s power law and applied to the ac conductivity data ( σ _AC ). Obviously, ( S ) decreases with increasing temperature, which refers to the electrical conductivity that follows the hopping mechanism. In addition, according to the CBH model, the Coulomb barrier of charge carriers ( U m) is estimated, showing decreasing values as increasing x and recording the lowest value for x = 15 nanocomposites. Nyquist plots (Z″&Z′) indicate one semicircle arc behavior for all samples. As x rises, the radius of semicircular arcs reduces, suggesting that ( σ _DC ) increases. The enhanced characteristics of CeO _2 NPs/CS nanocomposites make them suitable for future bio-applications.

Metal halide perovskites that do not contain lead are non-toxic and offer a wide range of uses in low-cost photovoltaic and optoelectronic systems. In this report, density functional theory is used to explore the influence of pressure (0–150 GPa) on the structural, electronic and optical characteristics of RbSrCl _3 perovskite metal halide. At 0 GPa, RbSrCl _3 was found to be an indirect wide-bandgap semiconductor. Under pressure, the electronic band gap transforms to visible range direct band gap which is suitable for optoelectronic devices. Higher absorption for RbSrCl _3 was found in the ultraviolet region under the influence of different pressures. As the pressure on the halide perovskite increased, absorption peak is shifted to higher energy range. The optical conductivity, reflectivity and extinction coefficient were significantly changed due to induced pressures. The results suggest that under uniform pressure RbSrCl _3 can be used in optoelectronic applications.

The ab-initio framework has taken place by means of the Full-potential Linear Augmented Plane-Wave (FP-LAPW) method, using the modified Becke-Johnson exchange potential approximation. This modified method was carried out to study the effects of doping iron ions on the structural, electronic, magnetic, and optical properties of CoScO _3 perovskite compound. Doping Fe ions have formed a nonstoichiometric perovskite Co _1-x Fe _x ScO _3 where x = 0, 0.25, 0.50, 0.75, and 1. all doped compounds crystallized in a tetragonal lattice due to the Jahn-Teller effect, while the lattice constant was calculated and found to vary between the value of the two pure compounds. Meanwhile, the stabilities of the studied compounds are shown in the negative values of the formation energy. The magnetic moment was calculated and the whole compounds showed a ferromagnetic behavior. Co _1-x Fe _x ScO _3 perovskite is a potential candidate for spintronic application due to the presence of the half metallic behavior. All optical spectrums including dielectric function, absorption coefficient, reflectivity and refractivity index, and energy loss function show remarkable features for the proposed perovskites.

In this research, structural, magnetic, electrical, and optical properties of Al ^3+ substituted Ba _0.6 Sr _0.4 Ti _1-x Al _x O _3 ceramics (where x = 0.00 to 0.20) have been investigated and discussed. The ceramic samples have been successfully synthesized by the conventional solid-state reaction method. The crystallinity of the prepared samples has been confirmed by x-ray peak broadening techniques such as the Williamson Hall (W-H) plot technique and the Scherrer method. The lattice constant ‘ a ’, showing a significant drop as Al concentration increases, varies from 3.942 Å to 3.921 Å. The FTIR spectrum revealed a prominent peak between 435 cm ^−1 to 540 cm ^−1 , without showing any secondary phase. Raman spectroscopic analysis showed that the prepared samples are in cubic phase with no phase transition. The shifting of a dominating peak in Raman at 580 cm ^−1 is due to the development of Al _Ti defects. VSM analysis at room temperature showed the ferromagnetic characteristics of all the samples. The highest value of the anisotropic constant (Ka ∼ 39.933 emu cm ^−3 ) has been seen at x = 0.10. The real component of initial permeability is almost constant for the frequency range of about 75 MHz, and above this frequency range, it quickly reduces. At the high-frequency range, the prepared samples show an excellent relative quality factor due to the low dielectric loss, notably when x = 0.05. The prepared perovskites exhibited minimum eddy current loss characteristics due to the increment of AC resistivity at x = 0.20. UV–visible spectroscopy shows a significant change in the energy bandgap from 3.23 eV to 3.04 eV with the doping concentrations.

The computational Generalized Gradient Approximations (GGA) are applied on cubic Cesium Lead Bromide (CsPbBr _3 ) with different stress values of 0, 5, 10, and 15 GPa for a supercell with PBE exchange relationship parameters to study the structural, mechanical, and optoelectronic characteristics. This study aims to determine how stress affects structural and electronic properties, how optical behaviour changes in reaction to electronic change, and how mechanical properties change as a result. The structure remains cubic, and there is no phase shift, but a reduction in the lattice parameters is seen. The reduction in band gap (1.900 eV) is found from 0–15 GPa and zero at 17 GPa. The partial densities of states (PDOS) of bulk CsPbBr _3 , Cs, Pb, and Br are also calculated. The partial density states PDOS of bulk CsPbBr _3 show that in the valence band range, the sharpest observed peak is for d -states, while in the conduction region, the sharpest peak is for p -states and then for s -states. The significant variation in values of absorption, conductivity (imaginary and real), dielectric function (imaginary and real), loss function, reflectivity, and refractive index (imaginary and real) are found by applying stresses of 0, 5, 10, 15 GPa. Using the energy deformation relationship, the elastic constants are computed. From these constants, various mechanical characteristics such as the bulk modulus, shear modulus, Young modulus, and Poisson ratio are derived and discussed. Additionally, it is a good component in optoelectronic devices due to its high refractive index, absorption, reflectivity, and conductivity.

The development and application of smart fabrics is a research hotspots in clothing fabrics. Accurately measuring the thermal conductivity of clothing fabric samples is an important basis for developing corresponding products. Here, thermal properties (thermal resistance and diffusivity) of clothing fabrics were measured through using a metamaterial sensor. The measured thermal resistance and diffusivity of the clothing fabrics could be affected by ambient temperature. The measured thermal resistance was also enhanced by increasing the fabric sample thickness. Similar resonance behaviors could be found in the fitted results based on the heat conduction theory. Finally, under the condition of the same thickness and temperature, the thermal properties of four clothing fabric samples were simulated and measured.

A new cross-linked triblock copolymer has been elaborated. The optical properties have demonstrated that the resulting material presents original properties compared to the pristine homopolymers. In fact, the optical absorption of the A-B-C copolymer overlapped all the ultraviolet (UV) and visible domain. Furthermore, combined with experimental analyses, DFT and TD-DFT calculations have been used to predict the most probable appropriate model structure of the triblock copolymer. So, the electronic properties of the selected model structure have been computed. All the obtained results support that this new copolymer is usable as an active layer in the optoelectronic fields due to its original properties.

In this work, diamond-like carbon (DLC) films used as anti-reflective coatings for monocrystalline silicon were deposited by magnetron sputtering for potential application in solar cells. The microstructural and optical properties of the films were investigated as a function of substrate temperature over a wide range during deposition. It showed that, when the substrate temperature increased from RT to 800 °C, the hybridized structures of the DLC films accordingly changed associated with a significant variation of refractive index between2.22 and 1.64 at a wavelength of 550 nm. Three types of coating systems, namely single-, three- and five-layer films on monocrystalline silicon substrates, were designed based on the anti-reflection principle and fabricated in terms of the relationships of refractive index and deposition rate with substrate temperature. In particular, a well-designed three-layer film, of which the refractive index gradually changed along the thickness, that is 1.8, 1.9 and 2.0, respectively, was successfully deposited at one step on monocrystalline silicon substrates by adjusting substrate temperature and deposition time, and featured a broadband anti-reflective characteristic with low average reflectivity of 8.7% at a wide solar spectrum of 400–1100 nm. This work demonstrates that the DLC film has a promising application potential as broadband anti-reflective coatings in silicon-based solar cells.

Spinel glass–ceramic is an important class of composites with promising applications in transparent antiriot shields, tunable lasers and broadband optical amplifiers. Although the crystallization process of spinel has been well studied, the approach for tuning it and the optical response of the resultant glass–ceramic still need urgent attention. Here, we posit that the addition of Ga _2 O _3 can significantly improve the crystallization tendency of the spinel phase and greatly change the optical response of the glass–ceramic. On one hand, the colourization of glass–ceramic can be tuned, and an unusual blue colour can be achieved. On the other hand, the luminescence can be notably enhanced, and the resultant spinel glass–ceramic exhibits intense green–yellow luminescence. The present findings about the Ga _2 O _3 –mediated structure modification and optical response tuning can provide an effective avenue for the functionalization of spinel glass–ceramic and may be general for various types of material candidates.

Incorporation of impurities in CuAlO _2 provides an opportunities to modulate its electronic and optical properties, which can be exploited for the applications of optoelectronic devices. Among the various elements doped of CuAlO _2 , research on the codoping magnesium (Mg) with nitrogen (N) which may be a promising way for fabricating p-type CuAlO _2 is still limited. Here, the first-principles calculation based on density functional theory was used to investigate the electronic and optical properties of Mg-doped, N-doped and Mg–N codoped CuAlO _2 . Compared with the undoped CuAlO _2 , the lattice parameters a and c of the Mg–N codoped CuAlO _2 become larger and smaller, respectively. The acceptor level induced by 2 p state of N in N-doped CuAlO _2 is very deep. The undoped and Mg-doped CuAlO _2 has indirect band gap. Whether the deep acceptor level or the indirect band gap, it is unfavorable to p -type doping or light emission. Due to the hybridization of 3 p state of Mg and 2 p state of N on the top of the valence band, the Mg–N codoped CuAlO _2 not only has a direct band gap, but also has a shallower acceptor level (about 0.24 eV above the top of the valence band). The optical properties of CuAlO _2 changes obviously after Mg–N codoping in the area of low energy. These results suggest that the possibility of enhancing the hole concentration in CuAlO _2 by Mg–N dual-acceptor codoping which will be beneficial to the application of CuAlO _2 in optoelectronic devices.

This experiment addressed the effect of Nickel-doped on the dielectric, ac conductivity, and optical properties of pure and doped Zn _(1−x) Ni _x O (x = 0, 3 and 6%) nanostructures. The un-doped and Ni-doped ZnO nanostructures were synthesized using co-precipitation. In this paper, the frequency-dependent dielectric and the electrical conductivity of un-doped and Ni-doped Zn _(1−x) Ni _x O nanostructures were examined at various temperatures ranging from 320 K to 460 K using an LCR meter. For the morphological and optical investigation, the prepared samples were analyzed using field emission-scanning electron microscopy (FE-SEM), and UV visible Spectroscopy was used at room temperature. The dielectric constant ( $\varepsilon ^{\prime} $ ), dielectric loss ( $\varepsilon ^{\prime\prime} $ ), tangent loss (tan δ ), the real as well as the imaginary part of the impedance against the frequency ranging from 100 Hz to 2 × 10 ^6 Hz that declines with increases in frequency at different temperatures ranging from 320–460 K. However, the electrical conductivity ( ${\sigma }_{ac}$ ) increased with the increase in frequency was examined. The ac conductivity ( ${\sigma }_{ac}$ ) follows Jonscher,s power law that the electrical conductivity is enhanced with increasing doping concentration. The optical transmission area also improved due to an increase in Ni-doping concentration in ZnO. The optical bandgap of pure and Ni-doped ZnO nanostructures is in the range lies 3.30–3.12 eV found that to decrease with the increase in Ni doping concentrations.

The effects of transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) doping on the stability, electronic structure and optical properties of β -Ga _2 O _3 have been studied using GGA and GGA + U. The results show that the U value can correct the strong interaction of the d-layer, causing orbital hybridization and affecting the position and number of impurity energy levels. It can move the conduction band to higher energy levels and weaken the role of Ga-3p in the valence band. The Ti-doped β -Ga _2 O _3 is easily formed, followed by V, Cr, Sc, Fe, Mn, Co, Ni, Cu, and Zn doping. Some bands change regularly with the increase of atomic number. All systems become degraded semiconductors after doping. All doping will make the β -Ga _2 O _3 red shift. Among them, the absorption intensity of Cu doping in the visible light range is significantly improved.

WS _2 is two-dimensional layered material which the electronic band gap is dependent on the number of layers. From application point of view, the WS _2 few layers are good candidate for nano scale flexible electronics . In this study, the WS _2 number of layers is modified using liquid phase exfoliation method. The blue shift of WS _2 supernatant absorption peaks suggested the change of layer thickness compare to the non-exfoliated one. This supernatant is further deposited on Polyethylene terephthalate (PET) to create a flexible multilayer WS _2 thin films. The morphology and the content of the thin film are confirmed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), respectively. The Raman and photoluminescence spectroscopy show typical characteristics of WS _2 multilayers which are dominated by W-S vibrations, exciton contributions, as well as the local defect and strain effects. Furthermore, the electrical characterization reveals the robustness of the WS _2 electronic properties again the mechanical stretching. This study highlights the abundant optical and electrical characterization of WS _2 multilayer which are applicable for flexible electronic devices.

Using PP-APW method the electronic, optical and mechanical anisotropy of ZnRE _2 S _4 (RE = Er, Tm) olivine compounds was investigated. The calculated unit cell parameters are in good agreement compared to the experimental ones. In addition, the study of electronic properties reveals that ZnEr _2 S _4 and ZnTm _2 S _4 are semiconductors with a direct bandgap of about 2.37 eV and 2.35 eV, respectively. The optical constants such as refractive index, reflectivity, and absorption coefficient have been calculated and analyzed. These constants show a clear anisotropy in the UV region for both compounds caused by the different electron polarizability in x −, y − and z −direction. Moreover, the elastic constants are estimated for the first time for ZnEr _2 S _4 and ZnTm _2 S _4 indicating that the compounds are mechanically stable and reveal ductility behavior. The direct bandgap, optical absorption, and mechanical stability make ZnEr _2 S _4 and ZnTm _2 S _4 promising candidates for optoelectronic application.

Zn _1−x Cr _x Al _2 O _4 (x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by hydrothermal method and heat treatment technology, and the effects of Chromium doping ratios on the microstructure, morphology, element distribution, binding energy and optical property of the samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray energy dispersive spectroscopy (XEDS), x-ray photoemission spectroscopy (XPS), ultraviolet-visible (UV–vis) spectroscopy, photoluminescence spectra (PL) and fourier transform infrared spectroscopy (FT-IR). The experimental results show that Zn _1−x Cr _x Al _2 O _4 nanoparticles possess cubic spinel structure without other impurity phases. The average crystallite size decrease and the lattice parameter increase with the increase of Cr doping concentration. The morphology of the samples exhibits irregular spherical or ellipsoid particles with uniform particle size. XEDS spectra display Cr ^3+ successfully used as doping agent replaced Zn ^2+ and entered ZnAl _2 O _4 matrix. XPS spectra demonstrate that the doped Cr ions mainly occupy the tetrahedral sites in Zn _0.95 Cr _0.05 Al _2 O _4 sample. UV–vis spectra indicate the band gap of the doped sample decrease and exhibit red shift with the increase of Cr ion concentration. The intensity of FT-IR spectra for Zn _1−x Cr _x Al _2 O _4 samples decreases slowly and occurs red shift. PL spectra show the intensity decrease and occur luminescence quenching phenomenon for Cr doped sample.

The organic stilbazolium derivative crystal4-dimethylamino-N′-methyl-4′- stilbazolium p- bromobenzenesulfonate (DASB) was successfully grown by spontaneous nucleation method coupled slow evaporation (SNM-SE) for the first time. The corresponding powder XRD revealed the crystalline nature of the DASB material, and various functional groups were determined by FT-IR. The thermal stability and melting point were analyzed by TG/DTG and DSC measurement. The absorption coefficient, band gap energy, cut-off wavelength and extinction coefficient were obtained through UV–vis-NIR spectral study. Photoluminescence result indicates DASB crystal exists purple emission at 405 nm and 467 nm because of the π – π * and defect transitions, respectively. The SHG efficiency of DASB crystal is about 3 times higher than KDP crystal. All the encouraging results indicate the DASB crystal is a promising candidate for the Thz generation applications.

In this work, structural, optical and electrical properties of ZnO thin films grown by laser ablation of a Zn metallic target on oxygen atmosphere using the 532 nm emission of the second harmonic of a Nd:YAG laser, are studied. Different mean kinetic energies of the plasma (E _k ) at fixed ion density (N _p ) were used as control parameters. X-ray diffraction profiles show the presence of a width (002) peak together with a peak associated with the (101) reflection. Changes in E _k affect the crystallinity of the samples. An intense PL emission in the visible range of the spectra associated with a majority intrinsic donor defects can be observed. The films showed an unusual low electrical resistivity as compared to the commonly reported values for undoped ZnO thin films.

Titanium oxide is used in a myriad of applications such as in capacitors, insulation paints among others. It is a prime candidate for water splitting due to its photocatalytic properties. In this work, undoped TiO _2 thin films were prepared by anodizing titanium foils cut into pieces measuring 60 mm by 20 mm. The specimens were anodized in an electrolyte consisting of 0.5 M H _2 SO _4 and 0.075% wt HF at room temperature. The anodizing voltages ranged from 50 V to 100 V. Anion doping of copper in as anodized TiO _2 was done electrochemically. The as anodized Ti foils were dipped in a 1 M Cu _2 SO _4 solution. All samples were annealed at 450 °C for 3 h. Near-normal total reflectance was measured on as anodized and copper pigmented samples in the solar (300–2500 nm) wavelength range. Spectrophotometric reflectance data was analyzed to obtain the absorption coefficient and using the same to determine the band gap of the films. It was noted that the films exhibited reduced solar integrated reflectance for TiO _2 samples prepared at lower anodic voltages of 50, 60 and 70 V. The copper pigmented, and annealed, TiO _2 samples exhibited both direct and indirect energy band gaps in the ranges, 3.38–3.86 and 2.50–2.74, respectively. Further, annealing and copper doping of the films lead to increased absorption. The photocatalytic activity of the films was assessed by measuring the rate of degradation of 10ppm methylene blue in UV light source. Copper doped TiO _2 exhibited enhanced photocatalytic performance in compared to pure TiO _2 . An increase in the anodization voltage caused subsequent increase in photocatalytic activity of films with 70 V as the optimum voltage above which photo degradation of methylene blue decreased.

ZnGeP _2 single crystals weakly doped by manganese (Mn) were grown by vertical gradient freezing method from polycrystalline batch which was synthesized by the modified two temperature vapor phase transport method. Energy Disperse Spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectrometry (FTIR) were employed to characterize the doping single crystals. The un-doped and Mn doped single crystals show the same color. XRD results manifest that the obtained Mn doped ZnGeP _2 has tetragonal structure with slight lattice distortion and has no segregation. The EDS results indicate a good stoichiometry of ZnGeP _2 weakly doped with Mn. From the XPS results, the doped single crystal with no impurity phases were successfully obtained by the vertical gradient freezing method. FTIR spectra show a slight decrease in infrared transmittance of Mn doped single crystals.

First-principles computation was used to study the effect of pressure on the elastic properties, magnetic properties, optical properties, and electronic structure of the normal spinel magnesium ferrite (MgFe _2 O _4 ) at different pressures (0, 10, 20, 50, 70, and 100 GPa). The normal spinel MgFe _2 O _4 has a direct bandgap of 1.62 eV which significantly decreased to 0.42 eV with increasing the pressure to 100 GPa. The values of the elastic constants were coherent with the mechanical stability norms for cubic crystals, which revealed that MgFe _2 O _4 was mechanically stable. The values of Pugh’s ratio indicate that MgFe _2 O _4 is ductile at all pressure values except at 100 Gpa MgFe _2 O _4 shows brittle behavior. The computed values of the Zener anisotropy factor at different pressures were not equal to 1.0, which indicates that MgFe _2 O _4 is elastically anisotropic. The optical properties (refractive index, reflectivity, dielectric function, optical conductivity, and loss function) for the normal spinel MgFe _2 O _4 , as well as its magnetic moment, were calculated and discussed at different pressures.

A mechanism pertaining to an anomalous optical anisotropy under a strong field in semiconductors having cubic structure is proposed. The valence-conduction band transitions of valence electrons located around atomic bonds re-distribute electrons between bands and, consequently, produce symmetry defects in local electronic density. The optical anisotropy is due to these symmetry defects, which are the sources for localized and non-compensated dipole moments randomly distributed within the crystal. The quantum time-dependent probability amplitude method, combined with classical electrodynamics, demonstrate that the non-compensated dipole moments destroy the optical isotropy of a crystal. To compare the scheme with an experiment, the theory is applied to $GaAs$ single crystal. Within a strong-field IR regime, the predicted four-fold symmetry of optical anisotropy, along with its amplitude, correlate well with an experiment.

Ge–Se–Te chalcogenide films with Ge content from 10% to 27% were prepared using thermal evaporation. The films were annealed with different times, and the changes of the linear refractive index and optical band gap of the films with different chemical compositions were investigated. It was found that, after 30 h of annealing, the Ge _20 Se _8.5 Te _71.5 film exhibits the smallest change ratio in terms of linear refractive index (

The electronic structure and optical properties of intrinsic and doped Ca _2 Ge have been calculated by using the first-principles calculation method based on density functional theory. The doping content of As were 2.08% and 1.04%, respectively, and the doping concentrations of Ga were same with As. The band gap of intrinsic Ca _2 Ge is 0.556 eV, and that decreased to 0.526 eV and 0.548 eV with respect of As doping amount of 2.08% and 1.04%. Meanwhile, the band gap is 0.25 eV when the doping amount of Ga was 1.04%, and the band gap is 0.23 eV for Ga was 2.08%. The band structures results shown that the Fermi levels of As-doped (2.08% and 1.04%) are moved into the bottom of conduction band. The electronic density of sates shown that the electronic configurations at the top valence band and bottom conduction band were changed as As and Ga doped. The dielectric function results shown that the maximum value of 52.7 and 97.53 were respectively obtained at 0 eV for the 2.08% Ga-doped and the 1.04% As-doped. Moreover, the phenomenon of strong metallic reflection has been found in the energy range of 6.0 ∼ 8.5 eV, and the metal reflection characteristics of intrinsic Ca _2 Ge was greater than the doped Ca _2 Ge. Analyzing the energy-loss function, it indicating that the energy region of appearing energy loss can be altered by doping As and Ga or changing their doped concentration.

This research addresses the effect of process parameters on the optical properties of solar selective coating. The proposed study discusses the deposition of a selective coating of CoCuMnO _x onto stainless-steel substrate. The coating was prepared via a sol-gel route and dip coating process. Mechanical adhesion between the coating and the substrate was increased through increasing the surface roughness of the substrate. Four parameters were discussed; precursor concentration, withdrawal rate, number of coating layers and the heat treatment temperature. The best achieved absorptivity was 0.906 in the wavelength range of (200–900 nm) and emissivity was 0.116 in the wavelength range of (2.5–25 μ m) for a sample with precursor molar ratio divided by 60, 1.5 cm min ^−1 withdrawal rate, double coating layer and 450 °C heat treatment temperature. Detailed coating characterization was discussed through XRD, EDX and SEM analysis.

A donor-acceptor small organic molecule, p-N,N-dimethyl-amino-benzylidene-malononitrile (DABMN), has been synthesized and successfully prepared in thin films using spin coating technique. The thin film of DABMN exhibited semiconductor behavior with an optical band gap of about 2.27 eV. The photoluminescence spectrum was exhibited a strong red emission. The energy levels of lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) were determined by experimental calculation from cyclic voltammetry. The electrical performance of the ITO/DABMN/Al structure device was evaluated through current-voltage characteristics and showed a typical Schottky diode behavior with good charge mobility. The charge density associated with the DABMN film was calculated from the capacitance-voltage measurements.

In this paper, we replace the sulfur atom with other atoms based on rhenium disulfide. The monolayer is combined and adjusted on the original basis. Based on the first principle, we studied the structural, electronic and optical properties of the transition metal monolayers of ReX _2 and ReXS (X = S, Se, Te). The structure resembles a ‘sandwich’. It is worth noting that ReSeS and ReSe _2 not only retain the direct band gap properties, but also have a large band gap, when the strain changes, not only the band gap changes, but also the nature of the band gap changes with each other. so they show good optical properties, and ReSe _2 and ReSeS have stronger absorption in the ultraviolet band. The band gap opened in ReSeS can be effectively adjusted by biaxial strain, and the band gap varies between direct and indirect.

CuO (S1) Single pure component nanoparticles (SPCNPs), Ag/CuO (S2) binary component hybrid nanoparticles (BCHNPS), Co1/Ag/CuO (S3), and Co2/Ag/CuO (S4) ternary component hybrid nanoparticles (TCHNPS) were synthesized via co-precipitation method. Several spectroscopic methods investigated the characterization of the prepared catalysts. Based on Crystal properties, CuO exhibit a monoclinic phase (tenorite); the grain size of the prepared samples was 28.15 nm, 29.42 nm, 27.86 nm, and 26.67 nm for S1, S2, S3, and S4 respectively. The addition of different content from Co as a dopant to silver decorated CuO gives a clear change to a flake shape. The presence of the IR absorption peaks in the region 400–600 cm ^−1 matched to the distinctive stretching vibrations of Cu–O bonds in the monoclinic phase structure of CuO. Disappearance of the Raman peaks of CuO and appearing of the new characteristic peaks of cobalt oxide confirms the doping process. Using DRS analysis, arrange of the bandgap values were S1 > S2 > S3 > S4. For the synthetic methyl orange and raw industrial dye, the photodegradation parameters were measured. The results show the excellent activity of Co2/Ag/CuO NPS compared with other samples. Electrical studies of the catalysts show a higher value for the dielectric constant in the higher and lower frequency regions for the sample S4. The hopping process of the charge carrier’s improving as a result of the increase of applied field frequency which leads to an increase in the material conductivity.

C -axis oriented Magnesium doped Zinc Oxide (MgZnO) thin films are promising candidates for variety of applications especially optoelectronic devices. In this work, the effects of seeding solvents on structural and optical properties of MgZnO films were analyzed. The comparison was performed by varying the seed layer solvent i.e. 2-Methoxyethanol, 2-Propanol, Ethanol and Methanol. MgZnO thin films were synthesized on different seed layered glass substrates using Chemical Bath Deposition (CBD) method. The XRD results revealed the hexagonal wurtzite structure for all samples. However, the film with seed layer 2-Methoxyethanol solvent had preferred c -axis orientation and better crystallanity. For 2-Methoxyethanol solvent based seed layer: the morphological study showed wrinkled free, unfractured and highly aligned MgZnO nanorods grown perpendicular to the substrate. Energy dispersive x-ray (EDS) spectroscopy confirmed the presence of magnesium in ZnO film. Highest average transmittance of $80 \% $ and band gap value of $3.3\,{\rm{eV}}$ was recorded through UV–vis spectroscopy. The optical constants (refractive index and extinction coefficient) were determined by reflectance and absorbance data. Furthermore complex dielectric constant and energy loss functions were estimated.

We study electronic and optical properties of zincblende GaN doped with various Cr concentrations (3.12%, 6.25%, 9.37%). We conduct the calculations by employing DFT + U in Wien2K code while supercell size (1 × 2 × 2) is kept fixed for all cases. Electronic properties are changed with effect of dopant where 3 d levels of dopant and 2 p level of N pro d uce p - d hybridization and this hybridization is highly affected by increasing impurity contents. Absorption spectra are blue shifted upon increase in dopant contents and absorption peaks are more pronounced in UV region. Refractive index and dielectric constant shows decrease as Cr concentration increases. Results reported in study indicate that Cr:GaN material may be considered a potential candidate for fabrication of optoelectronic, photonic and spintronic devices.

This research focus on the Influence of Dopant Concentration on Polycrystalline Ytterbium-doped ZrSe (Yb-ZrSe) material for possible photovoltaic application using the electrochemical deposition method. The cationic precursor was an aqueous solution of 0.01 mol ZrOCl _2 .8H _2 O while the anionic precursor was 0.15 mol selenium was prepared by dissolving with 5 ml of Hydrochloric acid (HCl), and then 0.05 mol Yb (NO _3 ) _3 .5H _2 O was used as the dopant. The films were characterized using UV-1800 Visible Spectrophotometer, Bruker D8 Advance x-ray diffractometer with Cu K α line ( λ = 1.54056 Å) in 2 θ range from 10°–90°and Scanning Electron Microscopy. X-ray diffraction (XRD) of the deposited films on FTO substrate studies reveals that films are polycrystalline by exhibiting diffraction peaks at (111), (200), (200) and (210) corresponds to the following angle (27.00°), (38.01°), (46.02°), (66.02°). (SEM) revealed that the grain size was uniformly distributed on the surface of the substrate. The optical band gap energy $2.29-1.57\,{\rm{eV}}$ was obtained.

In this study, silica-graphene oxide nano–composites were prepared by sol-gel technique and deposited by spray pyrolysis method on glass substrate. The effect of changing the graphene/silica ratio on the optical properties and wetting of these nano–structures has been investigated. The structural and morphological properties of the thin films have been studied by x-ray diffraction spectroscopy (XRD), field emission scanning electron microscope (FESEM), energy dispersive x-ray spectroscopy (EDS) and atomic force microscope (AFM). XRD results show that silica structures present in the synthesized films exhibit amorphous character and there is a poor arrangement in graphene plates along their accumulation directions. The relationship between the contact angle of the water drop and the surface of thin films was analyzed by surface roughness. The results show that the contact angle is also decreased by decreasing the surface roughness. Absorption and transmittance spectra obtained from (UV–vis) of the studied films were used to compute and determine some optical parameters such as absorption coefficient, transmittance rate, optical gap, refractive index and extinction coefficient of the films. The calculated optical band gaps of films decrease by increase the silica contents in these structures.

Chalcogenide glasses Ge _x Sb _40−x Se _60 with composition 12, 25 and 30 at.%, synthesized from elements with 5N purity (Ge, Sb, Se) by the conventional melt-quenching method were studied. The spectrophotometer’s measurements were recorded to determine the optical properties. Models based on the absorbance and absorption coefficient are used to determine the optical band-gap energy. The Urbach energy is deduced in the ${{\rm{Ge}}}_{x}{{\rm{Sb}}}_{40-x}{{\rm{Se}}}_{60}$ thin film alloys with composition x = 12, 25 and 30 at.%. The electronic and structural properties are studied, and the influence of the Urbach energy in estimating of the nonlinearity in the optical properties of these glasses is discussed. The analysis is performed with respect to the Urbach parameter that quantifies the degree of crystallinity of the structure which can be used to understand the behavior of different diffractive, wave-transmission and fiber structures.