Direct Optical Energy Gap Research Articles

Impact of molecular configuration on the photoluminescence and electrical characteristics of poly-pyrrol-thiazol-imine polymers films

The optical, photoluminescence, and electrical properties of Poly(Z)-PTI and Poly(E)-PTI, two Poly-Pyrrol-Thiazol-Imine polymers with comparable chemical structures but distinct configurations, were examined. Using the dip-casting method, polymer films were deposited on ITO substrates. UV-VIS spectroscopy revealed that both polymers diverged between 500 and 800 nm, showing the impact of molecular arrangement, but showed similar absorption behavior for wavelengths shorter than 500 nm. For Poly(Z)-PTI, the direct optical energy gaps were 2.06 eV, while for Poly(E)-PTI, they were 1.78 eV. Poly(Z)-PTI displayed an emission peak at 610 nm (red) according to laser photoluminescence spectra, while Poly(E)-PTI peaked at 563 nm (green-yellow). The capacitance behavior was revealed by electrochemical impedance spectroscopy. Nyquist plots suggested an equivalent circuit model of Rs (CRct)(QR)(CR) for both polymers, and the relaxation times were 15.9 ns for Poly(Z)-PTI and 89.5 ns for Poly(E)-PTI. The Mott-Schottky analysis verified the n-type conductivity, revealing 2.18 × 1016 cm− 3 carrier densities for Poly(Z)-PTI and 1.78 × 1016 cm− 3 for Poly(E)-PTI. At lower frequencies, both polymers exhibited limited conductivity and large dielectric constants. Insights into the possible uses of Poly-Pyrrol-Thiazol-Imine polymers in electrical and optoelectronic devices are provided by this study, which emphasizes the influence of molecular configuration on these polymers’ characteristics.

The Annealing Temperature Effect Enhances the Structural and Optical Parameters of Bi2Te3 Thermally Evaporated Thin Films

The current work investigates the influence of the annealing temperature (373, 473 K) on the structural and optical properties of Bi2Te3 thin films produced by the thermal evaporation technique. The crystal structure of samples is examined using an X-ray diffraction, indicating that Bi2Te3 thin films have a Rhombohedral structure with space group R-3m. The crystallite size (D) increased from 10.85 to 14.46 nm by increasing the annealing temperature. Additionally, increasing the annealing temperature reduces the micro-strain and the dislocation density from (3.33 × 10−3 to 2.5 × 10−3) and (8.49 × 1015 to 4.78 × 1015) Lines / m 2 , respectively. These micro-strain and dislocation density reductions refer to the crystallinity enhancement of sample Bi2Te3 thin films. The transmittance and reflectance spectra were measured using an Fourier transform infrared spectrometer. All samples reveal direct and indirect transition types and both direct and indirect optical energy gap decreased with increased annealing temperature from (0.325 to 0.29 eV) and (0.24 to 0.274 eV), respectively. From transmittance and reflectance data, the refractive index is calculated. These results reveal the refractive index decreasing as temperature annealing increased from (2.45–1.79) at 3250 nm. Other optical parameters such as absorption index, dielectric constant, energy loss function, and optical conductivity were estimated.

Preparation and Characterization of Au Quantum Dots Using Laser in Benzene and Study of the Pulse Energy effect on Quantum Size

Here, findings from a study on pulsed laser ablating of noble Au targets submerged in benzene solvent and a study on the effect of pulse energy on quantum size are presented. Three samples of gold quantum dots (AuQDs) are synthesized at pulse fluence of 4, 8, and 12 J/cm2, which is referred to as F1, F2, and F3, respectively. The prepared AuQDs were characterized by UV-Vis, HR-TEM, XRD, XPS, EDX, FTIR, Raman spectroscopy and Photoluminescence measurement. AuQDs that were synthesized have monocrystalline and cubic (FCC) structure, according to XRD patterns. It was found that the direct optical energy gap of AuQDs is enhanced to 2.6 eV. The emission peak of AuQDs photoluminescence emission spectra is at roughly 481, 445, and 437 nm, for F1, F2, F3 samples, respectively. The quantum size was reduced to 2 nm for sample F3. This strategy has the ability to prepare pure AuQDs in one step, with promising biosensor and bioimaging applications.

Tuning the optical and photophysical characteristics of DR1 through mixing with JGB

A dye mixture of Disperse red1 (DR1) and Janus green B (JGB) was prepared with different concentrations of the two dyes. The optical properties were studied for the two dyes and their mixtures in terms of the absorbance spectra. The direct optical energy gap in addition to the refractive index, extinction coefficient, dielectric constant and optical conductivity were estimated to the two dyes and their mixtures. The experimental energy gap was found to be 2.234 and 1.666 eV for DR1 and JGB respectively, while the values of the energy gaps for the mixtures were found to be ranging between these two values. On the other hand, the refractive index was found to be changed in a systematic way by changing the contents of the dye mixture. The same behavior was also observed for the dielectric constant and optical conductivity. The emission of the two dyes and their mixtures was studied in terms of fluorescence spectra using excitation wavelength of 300 nm where a change in the fluorescence intensity was observed by changing the contents of the mixture. Finally, TD-DFT simulations were performed for the two dyes and their mixture to study the electron density, electrostatic potential, energy gap and optical absorption spectrum and found to be compatible with the experimental measurements.

Influence of laser energies on the optical, structural and electrical properties of CdS nanoparticles by laser ablation in distilled water

Various laser energies were used to synthesize cadmium sulfide (CdS) nanoparticle nanostructures in distilled water using pulsed laser ablation. The influence of laser energies on the structural, optical, morphological, and electrical properties of CdS nanoparticles was studied using X-ray diffraction (XRD), UV–Vis spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and Hall measurement. The XRD data indicate that synthesized CdS nanoparticles are nanocrystalline and possess a hexagonal wurtzite structure, the lattice constants of CdS nanostructures were calculated to be (a = 4.105), (c = 6.662), and c/a=1.622. The direct optical energy gap of CdS was determined to be between 2.42 and 1.71 eV, depending on the laser energy. In CdS colloidal solution, EDS results demonstrate the presence of Cd and S components. In FT-IR spectra, the Cd–S stretching frequency is detected in the wave number region below 700 cm-1. Electrical analysis revealed that the synthesized CdS nanoparticles were n-type with mobility increasing with laser energy 530, 590 mJ and decreasing with laser energy 650 mJ. The I-V characteristics of (n-CdS NPs/p-Si) displays that the current increased exponentially with increasing voltage, whereas at reverse bias, the current increased slowly with increasing voltage

PVA/CMC/PEG blended polymer loaded with ZnCo1.9Al0.1O4/carbon nanoparticles/PANi as a promising films for UV radiation shielding

Polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) have been employed as polymeric matrices for the synthesis of polymeric nanocomposite films that incorporate ZnCo1.9Al0.1O4, carbon nanoparticles (CNPs) and polyaniline (PANI) as fillers. X-ray diffraction technique was utilized to examine the structure of ZnCo1.9Al0.1O4 filler and the formed PVA/CMC/PEG/ZnCo1.9Al0.1O4/CNPs/x wt % PANi blends. The morphology of the doped blend was explored using the scanning electron microscopy technique. The increases in absorbance, especially in the UV spectrum, demonstrate the potential of these blends in UV-blocking and UV-filtering applications. The minimum direct and direct optical energy gaps are 5.62 and 4.77 eV obtained as the quantity of PANi became 0.3 wt %. The highest refractive index values (n = 1.66 at 600 nm) were acquired as the blend was doped with 0.4 wt % PANi. The impact of different fillers on the linear and nonlinear optical parameters was explored. The inclusion of ZnCo1.9Al0.1O4/CNPs/x wt % PANi resulted in an improvement in PVA/CMC/PEG blended polymer's optical conductivity. The FL intensities of the loaded blends are comparatively lower than those of the undoped blend. The values of the dielectric constants of doped blends with x = 0 or 0.4 are notably higher than those of other blends. Doped blend with x = 0.2 exhibited the highest energy density value (9 × 10−3 J/m3 at 1 kHz). The doped blend with x = 0.4 has the highest ac conductivity (1.53 × 10−8 Sm−1 at 1 kHz). The influence of doping on the relaxation time and capacitance behavior of the host blend was inspected. These outcomes suggest the opportunity of employing the created nanocomposites in capacitive energy storage and optoelectronic devices.

An analysis comparing the performance of lead and tin halides organic Perovskite Solar Cells and numerical simulation with SCAPS

The scientific community focused on finding environmentally safe alternative metal halides to address the instability and toxicity associated with lead perovskite materials. These alternatives are supposed to replace lead halides without altering the distinctive properties of lead perovskite materials. Additionally, they should contribute to producing longer-lasting and stable perovskite in solar cells. This research presents a practical investigation of using tin- and lead-based composites in perovskite iodide solar cells with Titanium dioxide (TiO2) and Copper oxide (CuO) as electron transport materials (ETM) and hole transport materials (HTM), respectively. The performance parameters of the perovskite solar cells (PSCs) are compared with those of lead-based and lead-free PSCs with the same charge transport layers of ETM and HTM, as well as compare the practical results with the software results of Solar Cell Capacitance Simulation (SCAPS) package. In this study, the performance of PSCs with an absorption layer ((CH3NH3PbI3)t/(CH3NH3SnI3)1-t) was examined. The thickness of the perovskite layer is represented by (t), which can take the values(t = 1, 0.5, or 0) μm. The results of the laboratory study were compared to the performance of PSCs based on numerical analysis of SCAPS modeling. PSCs were prepared with a configuration structure (FTO/compact TiO2/(CH3NH3PbI3)t/(CH3NH3SnI3)1-t/CuO/Cu-electrode). A tetragonal phase was obtained for perovskite materials CH3NH3PbI3 and CH3NH3SnI3 with a direct optical energy gap estimated at (1.55 and 1.35) eV, respectively. The l-V curve of the prepared PSCs was studied, and the performance of the solar cells was examined under a light intensity of 100 mW/cm2. The power conversion efficiency, PCE, of the prepared solar cells, was (PCE = 2.9, 3.11, or 0.5) at (t = 1, 0.5, or 0)μm, respectively. A comparative analysis was also performed between the empirical performance of the manufactured PSCs and the theoretical results acquired by the SCAPS package software.

Conversion of preferred crystalline orientation by annealing and its impacts on the structural, electronic, and optical properties of pulsed laser-deposited CdO thin films

The impact of annealing on the preferred crystalline orientation as well as the structural, electronic, and optical properties of pulsed laser-deposited 150 ± 3 nm thick cadmium oxide (CdO) films was studied. X-ray diffraction analysis revealed that the annealed CdO films have smaller crystallite sizes, as their molecules at the grain boundaries possessed enough kinetic energy to rearrange their preferred crystalline orientation between (111) and (200). The atomic force microscopy and field emission scanning electron microscopy analyses revealed an enhancement in the active surface area with optimized grain boundaries by annealing which facilitates gas adsorption/desorption. DC electrical conductivity depends on the annealing process and reveals two different conduction mechanisms. The direct optical energy gap was decreased from 3.41 eV to 2.76 eV by annealing at 473 K which is greater than the theoretical value, i.e. 2.2 eV, for bulk CdO. The findings agree with the Burstein-Moss effect as a result of the increased carrier concentration following the generation of numerous oxygen vacancy sites and Cd interstitials. However, mutual charge carrier-impurity interaction and charge carrier Columb interaction contributed to narrowing the band gap by increasing the annealing temperature. The enhanced values of Urbach energy, optical packing density, dispersion parameters, optical conductivity, dissipation factor, oscillator strength, and lattice dielectric constant supported the effectiveness of the annealing process on tailoring optoelectronic responses in the infrared region for the CdO thin films for use in optoelectronic devices. Moreover, the calculated linear optical susceptibility, and nonlinear constants (i.e. third-order optical susceptibility and nonlinear refractive index) were the highest for CdO films annealed at 473 K. The improved value of the figure of merit, solar material protection factor, and solar skin protection factor for the CdO films, annealed at 473 K supports its use in several photovoltaic applications, including solar cells.

Optical, Structural, and Dielectric Characteristics of Flexible PVA/PEG/ZnMn2O4/CuCo2O4/x wt % Melanin Blended Polymer Composites

Our research described in the current paper was aimed to alter the optical and dielectric characteristics of polyvinyl alcohol/polyethylene glycol blended polymers by incorporating different quantities of melanin and ZnMn2O4/CuCo2O4 to create flexible blended polymer composites suitable for applications like photocatalysis, capacitors, and different optoelectronic applications. The PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blended polymer composites were created using a casting technique. The structural properties of the fillers and various blends were investigated using an X-ray diffraction technique. A transmittance electron microscope was used to investigate the features of the ZnMn2O4/CuCo2O4. The optical properties of the PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blend composites, which included their linear and nonlinear optical parameters, were analyzed using a diffused reflectance technique. The direct and indirect optical energy gaps attained their lowest values (5.47, 3.22, and 2.97) and (5, 1.18) eV in PVA/PEG/ZnMn2O4/CuCo2O4 blended polymer. The doped blends exhibited superior absorbance efficiency in the UV spectra in both the UVA and UVB regions. In the UV and visible ranges doped blends with 15 and 10 wt % of melanin had the highest refractive index values, respectively. The highest dielectric constant and electric ac conductivity were achieved as the blend was loaded with 5 wt % melanin. The energy density value of the doped blend containing 10% melanin was the highest when compared to other doped melanin polymers. The maximum height electrical potential barrier of each blend was also calculated. The electric modulus was also studied. The intensities of the emission peaks in terms of fluorescence characteristics were reduced as the PVA/PEG blend was loaded with ZnMn2O4/CuCo2O4-x wt % melanin. In conclusion, the PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blended polymer composites are promising hybrid materials for use in a variety of applications.

A comprehensive study on structural, optical, electrical, and dielectric properties of PVA-PVP/Ag-TiO2 nanocomposites for dielectric capacitor applications

Nanocomposites made from polymers and nanoparticles (NPs) have a wide range of uses. Herein, the polymer nanocomposite electrolyte films were prepared by blending polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) with hybrid NPs of silver (Ag) and titanium dioxide (TiO2). The structural, optical, electrical, and dielectric properties of the resulting PVA-PVP/Ag-TiO2 nanocomposite electrolytes were analyzed. XRD analysis revealed that the PVA-PVP blend had a semicrystalline structure, and the addition of hybrid NPs reduced the crystallinity ratio. FTIR analysis showed that the intensity decreased as the content ratio of hybrid NPs increased. Optical measurements showed that the nanocomposite electrolyte samples' direct and indirect optical energy gap decreased with the increasing content of hybrid NPs. The electrical conductivity also increased with the hybrid NPs' content, likely due to the higher conductivity of the hybrid NPs compared to the polymer blend matrix's electrical conductivity. The dielectric constant (εr) and dielectric loss (εi) increased with the concentration of hybrid NPs at lower frequencies, indicating the polarization effects of space charges. The capacitance–frequency (C–f) and conductance–frequency (G/ω–f) curves of the prepared polymer nanocomposites exhibited a discernible enhancement correlating with the increased content of Ag-TiO2 nanofillers. The impedance spectroscopy data were analyzed using Nyquist plots, which showed a single semicircular arc whose radius of curvature decreased with increasing the hybrid NPs loading, indicating a decrease in the overall impedance of the nanocomposite electrolytes with the mixed NPs loading. The impedance reduction and dielectric feature increase were attributed to the interfacial polarization between the hybrid NPs and the polymeric matrix. These findings suggest that the PVA-PVP/Ag-TiO2 nanocomposite electrolytes could be used for thin-film dielectric capacitor applications.

Doping and precoating by Cu-metal and annealing impacts on some physical properties and applications of MnS thin films

We prepared thin films of manganese sulfide (MnS) using a thermal evaporation technique. These films were pre-coated and doped with Cu ((MnS)1-xCux, x = 0.05 g). A lot of work was done on these films using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV/VIS/NIR spectrophotometry, and a two-probe approach to figure out their structure, shape, optical properties, and electrical properties. We investigated various factors including the optical energy gap (Eg), refractive index (n), extinction coefficient (k), Urbach energy (Eu), dielectric constants (εr), dispersion parameters, activation energy (ΔE), mobility, photocatalytic analysis, and Seebeck coefficient. The XRD analysis showed that the thin films were amorphous. The direct optical energy gaps of the pure, Cu pre-coated layer, and Cu-doped MnS films were measured at 3.17 eV, 1.88 eV, and 2.45 eV, respectively. Annealing the films at different temperatures showed normal refractive index dispersion in the NIR region. The addition of copper, both as a pre-coating layer and as doping, resulted in a decrease in film resistivity, indicating their semiconducting nature. FE-SEM analysis provided valuable insights into the morphology of the thin films, revealing a uniform and smooth surface. The electrical characteristics showed that film resistivity decreased with copper addition, confirming enhanced conductivity. These properties hold significance in the development of absorber layers for second-generation solar cells, thermoelectric characteristics, and photocatalysis applications.

Optical and electrical properties of thin films of MnS/metal/MnS for photocatalysis and gas sensing applications

Thin films of manganese sulfide (MnS) with interlayers of silver and copper were prepared using the thermal evaporation technique for applications in photocatalysis and gas sensing. The structure, morphology, optical, and electrical properties of the deposited films were described by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), UV/VIS/NIR spectrophotometer, and two-probe technique. Various parameters such as crystallite size, micro-deformation, dislocation density, optical energy gap, refractive index, extinction coefficient, Urbach energy, dielectric constants, dispersion parameters, activation energy, mobility and, Seebeck coefficient were determined. According to the experimental results, XRD analysis revealed that the MnS powder has a crystalline structure with a cubic phase. While the pure MnS thin films exhibited an amorphous structure, the addition of metals (Ag and Cu) as interlayers resulted in a distinct crystallinity. The pure MnS films had a direct optical energy gap of 3.17 eV, which changed to an indirect transition with energy gaps of 2.43 eV and 2.50 eV when Ag and Cu interlayers were added, respectively. The refractive index values and dispersion of the films depended on the type of interlayer, with all films exhibiting normal dispersion. The temperature dependence of the sheet resistance indicates a semiconducting behavior of the samples, and the addition of the interlayer metal reduced the sheet resistance. Overall, the results suggest that thin films of MnS and MnS/metal/MnS hold promise for organic photocatalysis and gas sensor applications, respectively.

Optical Properties of PVA Silicon Carbide Nano Composites Films Synthesized Via Laser Ablation

Background: Enhancing the optical characteristics of nano-silicon carbide and polyvinyl alcohol films is thought to be crucial for obtaining the semiconductor with the lowest energy gap for applications in electrical devices, digital displays, and sensors.
 Materials and Methods: Poly vinyl alcohol and silicon carbide's optical properties were examined. A pulsed laser with a 532 nm wavelength is used to create these nanoparticles into widespread nanoparticles in two environments (water and vinyl alcohol). Polyvinyl alcohol nanocomposite was created by spin coating silicon carbide particles with the weight fractions 0.90%, 0.91%, 0.93%, and 0.95%. Fourier spectroscopy was used to locate the functional groups based. Techniques FESEM were used to analyze the surface composition and nanoparticle dispersion on the membrane-surface of the nanocomposite. using spectroscopy UV-Vis used to record the absorbance spectrum in the range of (200-800) nm for ultraviolet radiation.
 Results: The direct energy gap (5.585, 5.310, 5.480, 4.986, 4.800) eV and the indirect (5.006, 4.880, 4.916, 4.683, 4.490) eV and Urbach energy (2.38, 2.45, 2.94, 2.74, 3.67) eV were calculated.for the samples by ratio, as shown in Table No. 1.
 Conclusion: By investigating the optical characteristics of nanoparticles, such as their extinction and absorption coefficients, direct and indirect optical energy gaps, and Urbach energies .increase in extinction and absorption coefficients Urbach energy when adding nano carbide to polyvinyl alcohol, results show narrowing of the direct and indirect energy gaps. This suggests that the nanocomposite's optical characteristics have improved.

Effect of CdS Nanoparticles on Structural, Optical and Dielectric Properties for Gamma-Ray Shielding and Antibacterial Efficiency of PVA/PAAm Polymers Blend

We present the production and extensive characterization of a polyacrylamide (PAAm)/polyvinyl alcohol (PVA) polymeric blend doped with varying percentages of cadmium sulfide (CdS) nanoparticles (NPs). Using the solution casting method, CdS-filled PVA/PAAm polymeric nanocomposite (PNCs) films in various weight ratios and percentages were created. The SEM pictures confirmed the identical spreading of CdS NPs in the mix. The filler CdS material might be used to modify the optical characteristics. The film’s direct optical energy gap ([Formula: see text] (dir.)) has been adjusted from 2.30[Formula: see text]eV to 3.30[Formula: see text]eV. The intermolecular interactions of the PVA/PAAm mix were investigated using FT-IR analysis. The electrical properties of alternating current were studied throughout a frequency range of 100[Formula: see text]Hz–5[Formula: see text]MHz. The impact of CdS NPs on the dielectric coefficient ([Formula: see text], dielectric loss ([Formula: see text] and ac conductivity ([Formula: see text] of PVA/PAAm PNCs over a range of frequencies at room temperature has been investigated. With increased CdS NPs, the attenuation coefficient values rose. We demonstrated that doping CdS composites with PVA/PAAm increases the antibacterial (ANB) activity of the composites. As a result of these findings, the PNCs films are appropriate for gamma-ray shielding (GRS) and ANB applications.

Synthesis, optical characteristics, and gamma-ray protection competence evaluation of polyvinyl chloride reinforced basalt nanocomposites

In this study, new PVC (polyvinyl chloride) polymers doped with different contents of basalt nanoparticles have been prepared. The PVC was mixed with concentrations (0, 5, 10, 15, 20, and 50 wt%) of basalt nanoparticles utilizing the casting method. The samples coded as PB0.0, PB5.0, PB10.0, PB15.0, PB20.0, and PB50.0. The density of the casted samples increased from 1.38 to 2.18 g/cm3 with increasing basalt nanoparticle concentrations. Scanning electron microscope (SEM) of the prepared samples showed a good dispersion with small basalt concentrations in the while some agglomerations were found with the highest basalt concentrations in the mixture. The values of the direct optical energy gap varied from 3.0 to 3.5 eV, while the refractive index values changed from 2.39 to 2.27. The gamma-ray shielding parameters were evaluated using the Phy-X/PSD software program as well as the MCNP – code. The most critical results showed that the linear-attenuation coefficient (μ) increased from 14.421 to 23.862 cm−1 (at 0.015 MeV), and from 0.030 to 0.048 cm−1 (at 15 MeV) for PB0.0 and PB50.0 samples, respectively. Moreover, the evaluation of other gamma - ray shielding characteristics showed an enhancement with the addition of the basalt nanoparticles. Besides, neutron cross section was also calculated, and results revealed that PB0.0 is 0.086 cm−1 and PB50.0 is 0.104 cm−1. Finally, the obtained results concluded that the γ -ray, and neutron shielding capacities were enhanced with the increase in basalt nanocomposites amount in the fabricated composites.

Pb-Bi-S thin films by chemical deposition - optical and electrical properties

In this work, we report the procedure for the synthesis by chemical bath deposition of Heyrovskyite - Pb6Bi2S9 (H- LBS) thin films as a new emerging material. Homogeneous thin films are obtained, with a thickness from 95 to 130 nm. X-ray diffraction shows that deposited films are amorphous, and crystallize to the orthorhombic Pb6Bi2S9 phase when annealed in air at 150 °C. The deposited material has direct optical energy gap (Eg)from 1.31 to 1.62 eV. A heterojunction formed by H- LBS/PbS shows diode behavior with the generation of open circuit voltage (VOC) of 285 mV, short circuit current density (JSC) of 13.3 mA/cm2 and power conversion efficiency (PCE) of 0.98%, evidencing the feasible application of H- LBS thin films as absorbers in solar cells.

The Structural and Optical Investigation of Grown GaN Film on Porous Silicon Substrate Prepared by PLD

The optical properties of a grown gallium nitride (GaN) thin film on a porous silicon (P-Si) substrate was investigated. A Photo-electrochemical etching method was used to synthesize the Psi substrate, and a physical deposition method (pulsed laser deposition) of 1064 nm Q-switch Nd: YAG laser with a vacuum of 10−2 mbar was used to grow a thin layer of GaN on a prepared P-Si substrate. X-Ray diffraction displayed that GaN film has a high crystalline nature at the (002) plane. The photoluminescence of GaN film exhibited ultraviolet PL with a peak wavelength of 374 nm corresponding to GaN material and red PL with a peak wavelength of 730 nm corresponding to Psi substrate. The absorption coefficient of the P-Si substrate and grown GaN thin film was obtained from the absorption calculation of UV-Vis diffused spectroscopy at ambient temperature in the 230–1100 nm wavelength range. Extinction coefficients, optical energy gap, and refractive index of both the P-Si substrate and the grown GaN thin film have been determined, respectively. The direct optical energy gaps of both the P-Si substrate and grown GaN have also been determined using three methods: Plank’s relation with photoluminescence (PL) spectroscopy, Tauc'relation, and Kubulka-Munk argument with Uv-Vis diffused spectroscopy. It was observed that the optical energy gap of the P-Si substrate was 2.1 eV, while the grown GaN thin film had a multi-optical energy gap of 3.3 eV and 1.6 eV. A good agreement has been obtained between these mentioned methods.

Ultra-High Molecular Weight Polyethylene Modifications Produced by Carbon Nanotubes and Fe2O3 Nanoparticles.

Thin sheets of ultra-high molecular weight polyethylene (UHMWPE), both in pristine form and containing carbon nanotubes (CNTs) or Fe2O3 nanoparticles (NPs) at different concentrations, were prepared. The CNT and Fe2O3 NP weight percentages used ranged from 0.01% to 1%. The presence of CNTs and Fe2O3 NPs in UHMWPE was confirmed by transmission and scanning electron microscopy and by energy dispersive X-ray spectroscopy analysis (EDS). The effects of the embedded nanostructures on the UHMWPE samples were studied using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and UV-Vis absorption spectroscopy. The ATR-FTIR spectra show the characteristic features of the UHMWPE, CNTs, and Fe2O3. Concerning the optical properties, regardless of the type of embedded nanostructures, an increase in the optical absorption was observed. The allowed direct optical energy gap value was determined from the optical absorption spectra: in both cases, it decreases with increasing CNT or Fe2O3 NP concentrations. The obtained results will be presented and discussed.

Irradiation-induced effects on structure and optical properties of PbO-B2O3-Na2O glasses: γ-dosimetry application

The objective of this research is to study the impact of gamma irradiation on various PbO-B2O3-Na2O glasses that have been doped with CdO, BaO, MoO3, and WO3. The prepared glass has been experimentally examined before and after 65 kGy gamma irradiation at a dose rate of 0.799 kGy/h at 30 °C. X-ray diffraction has been used to confirm the amorphous nature of glass samples. Structural and optical properties were studied using Infrared (IR) and UV–vis spectroscopic techniques. IR experiments of all glass samples indicate absorption bands specific to different types of borate structures. The optical characterizations such as the direct and indirect optical energy gap, index of refraction, and Fermi energy were analyzed using UV–vis spectra in the wavelength range of 190–1100 nm. We found that the values of the direct and indirect optical energy gap of these glasses are in the range of 3.57–2.81 eV and 3.27–2.45 eV, respectively. The main resonance paramagnetic centers for all prepared samples have been confirmed by the ESR spectrum.

Structural, Optical, Electrical and Discharge Characteristics of PVA-ZnS Nanocomposite Polymer Electrolyte−Zn2+ Ion Conduction for Solid State Battery Applications

Polyvinyl alcohol (PVA) based Zn2+ ion conducting solid polymer electrolyte was prepared using a solution-cast method. Measurements were taken utilizing X-ray diffraction (XRD) and Fourier transform infrared analysis (FT-IR) to investigate the structure. The optical absorption spectra were investigated in the 200-800 nm range in order to acquire information about the optical properties of the material. This data comprised the direct energy gap, indirect energy gap and optical absorption edge of the material. The direct optical energy gap for pure PVA lies at 6.08 eV, while PVA doped with zinc sulphide ranges from 5.28 to 5.68 eV for the different compositions. It was evident that the energy gaps and band edge values transferred to lower energies on doping with ZnS up to a dopant concentration of 92 wt.% of PVA and 8 wt.% of ZnS. For this study, the ionic conductivity and transference number of PVA polymer electrolytes were measured in order to know more about the conductivity order and charge transport in these materials. The charge transport in PVA polymer electrolyte was measured to be largely due to ions (tion = 0.97), as indicated by the transference number. Increasing the ZnS concentration and the temperature were both found to raise the ionic conductivity. The discharge properties of solid-state battery cells made with this PVA polymer electrolyte were studied while operating under a constant load of 100 kW.