Growth of Europium-Doped Magnesium Selenide Films by Electric Field-Assisted Spray Pyrolysis: Optical and Structural Analysis

Europium-doped MgSe films were deposited via electric field-assisted spray pyrolysis. The dopant concentration of the bulk solution of europium trioxide was 5wt. %. However, for doping the films at different substrate temperatures, volume percentage (vol. %) was employed at each instance of variation. Variation of spray temperature was around 573K and 673K (±0.3). Deposition occurred at optimized conditions. Spectra of absorption indicate poor absorption characteristics demonstrated by Europium-doped MgSe films in the ultra-violet region and very low absorption characteristics in the visible section. Absorption peaks were evident around 230nm, 240nm, 350nm and 365nm which confirmed defect states are inherent inside the crystal structure of the films. The films displayed high transparency and low reflection in the visible section at varying substrate temperatures. The high transparency revealed by the MgSe:Eu films in the visible section of the electromagnetic spectrum makes the material applicable as a coating layer in the manufacturing of transparent products. Band gap energies within the range of 2.49eV to 2.95eV corresponding to varying substrate temperatures (573K, 598K, 623K, 648K and 673K) and film thicknesses (2900nm, 2750nm, 2500nm, 2100nm and 200nm) were determined for the MgSe:Eu films. However, a clear observation shows that the band gaps of MgSe:Eu films are mainly dependent on thickness such that the obtained band gaps decreased with increasing thickness (band gap increases with thickness reduction). Structural analysis (XRD) studied at 10% and 40% Eu concentrations reveals a hexagonal (or wurzite) structure for the films with a distortion in crystallinity at higher dopant concentration (40 vol. %) and a resultant blue shift in the lattice constant from the bulk value. Multiple planes of reflection from XRD pattern of the deposited MgSe:Eu films indicate clearly that the films are polycrystalline. Surface morphology (SEM) confirms the highly strained nature and the presence of defect states within the crystal lattice of the Europium-doped MgSe films. Composition of MgSe:Eu films obtained by energy dispersive analysis x-ray (EDAX) confirms the growth of MgSe:Eu films

Theoretical investigation of the structural, optoelectronic, and the application of waste graphene oxide/polymer nanocomposite as a photosensitizer

The negligence of used waste polymers often results in the waste of resources and constitutes serious environmental pollutants. Therefore, it becomes necessary to practically provide a means of converting these waste polymers to useful resources. For this purpose, the potential applicability of some selected waste polymers as the active photosensitizer material in dye-sensitized solar cells were exploited using density functional theory. In this research work, density function theory (DFT) is applied to investigate the interaction of graphene oxide (GO) with monomers of Polypyrrole (PPy), Poly (phenylene vinylene) (PPV), Poly(vinyl alcohol) (PVA), and Polyvinyl Pyrrolidone (PVP) polymers. The geometrical structures of the hybridized nanocomposites GO-PPy, GO-PPV, GO-PVA, and GO-PVP are fully optimized at wB97XD/6–311++G(d,p) computational method. All of the nanocomposites’ optoelectronic properties, the excitation type and the wavelengths, oscillator strengths, as well as the dominant transitions were calculated. Atoms-in-molecules (AIM) and natural bond orbital (NBO) analysis were used to analyze the strength and nature of the composites. The results of the ground state energy gap revealed that the hybridized nanocomposites are semiconducting in nature while the 3.7020 eV energy gap of the GO-PVA makes it the most stable among the various nanocomposites. The thermodynamic calculation of the various nanocomposites shows that the GO-PVA nanocomposite is highly endothermic among the various nanocomposites with free energy value of 353.71kcal mol ^−1 . The results of the density of state (DOS) analysis show that the p-orbitals in all of the different nanocomposites had the highest density contribution to the frontier molecular orbitals, and are also found to dominate the anti-bonding states densities