In-Depth Optical Analysis of Zn(Al)O Mixed Metal Oxide Film-Based Zn/Al-Layered Double Hydroxide for TCO Application

In this article, an in-depth optical investigation of Zn(Al)O-mixed metal oxide (MMO) film using Zn/Al-layered double hydroxide (LDH) was elucidated through co-precipitation and spin coating techniques. The field emission scanning electron microscopy (FE-SEM) analysis revealed the occurrence of a vertically aligned sheet-like structure with a thickness of 60 nm for pristine LDH, which further reduced to 45 nm after calcination at 300 °C. Additionally, pristine LDH showed multiple optical bandgaps of 5.18, 3.6, and 3.2 eV. Moreover, a good agreement of the obtained optical bandgaps was attained between both utilized methods, ultraviolet-visible light (UV-Vis), and photoluminescence (PL) spectroscopies. The optical bandgap decreased at higher calcination temperatures, which indicates the active role of the applied post-fabrication process on the optical profile of the deposited MMO film/s. The demonstrated transmittance spectra of the deposited MMO films exhibited a transparency between 85% and 95%; this indicates the usefulness and consistency of the proposed film for transparent conductive oxide (TCO) based optoelectronic applications.

Structural and magnetic properties analysis of trivalent Al3+ ions substituted Ni-Zn-Co nano-spinel ferrites

This study explored the structural, morphological, optical, and magnetic properties of Ni0.4Zn0.35Co0.25Fe2−x Al x O4 (0 ≤ x ≤ 0.12) nano-spinel ferrites. Nanocrystalline cubic structure formation and weight loss percentage were determined by thermogravimetric analysis and differential scanning calorimetry (TGA - DSC). Single-phase cubic spinel structures with Fd3m space group of synthesized samples were confirmed by Rietveld refinement X-ray diffraction (XRD) data. The particle sizes were found to be in the range of 6.7 nm–5.25 nm, and agglomeration occurs inside the ferrite samples. The atomic planes and strong crystallinity were detected through SAED images. The characteristic peaks of the Raman spectra identified the bonding between the cations and anions in the sub-lattices. The optical bandgaps (E g ) were found to be in the range of 2.1 eV–2.52 eV. S-shape hysteresis (M-H) loops identified the superparamagnetic nature of the nano-samples. The studies’ outcomes indicated the applicability for biomedical applications of these nano samples.

Observation of high nonlinearity in Bi doped BixIn35-xSe65 thin films with annealing

The present work demonstrates the impact of thermal annealing on the structural, linear, and non-linear optical characteristics of thermally evaporated BixIn35-xSe65 (x = 0, 5, 10, 15 at%) thin films. The prominent crystalline phases have been developed for all annealed films at 450 °C whereas the films remain amorphous at 350 °C annealing. The XRD and Raman analysis showed the phase transformation of Bi-doped films and new Bi2Se3 phases developed upon annealing at 450 °C. The phase transformation induced change increased the linear and nonlinear properties with great extent as seen from the UV–visible optical studies. The direct and indirect optical bandgaps decreased with annealing temperature and also with Bi % content due to the formation of surface dangling bonds near the crystallite sites. The static linear refractive index and high-frequency dielectric constants were increased with annealing. The third-order non-linear susceptibility and non-linear refractive index were found to be greatly influenced by annealing temperature and increased with bismuth content. The FESEM micrographs also showed the phase transformation and EDX analysis showed the composition. The results obtained from the materials showed the potentiality to be useful for photovoltaic and optoelectronic applications.

Enhanced Photocatalytic Degradation of Ternary Dyes by Copper Sulfide Nanoparticles

We report the effect of thermolysis time on the morphological and optical properties of CuS nanoparticles prepared from Cu(II) dithiocarbamate single-source precursor. The as-prepared copper sulfide nanoparticles were used as photocatalysts for the degradation of crystal violet (CV), methylene blue (MB), rhodamine B (RhB), and a ternary mixture of the three dyes (CV/MB/RhB). Powder XRD patterns confirmed the hexagonal covellite phase for the CuS nanoparticles. At the same time, HRTEM images revealed mixed shapes with a particle size of 31.47 nm for CuS1 prepared at 30 min while CuS2 prepared at 1 h consists of mixtures of hexagonal and nanorods shaped particles with an average size of 21.59 nm. Mixed hexagonal and spherically shaped particles with a size of 17.77 nm were obtained for CuS3 prepared at 2 h. The optical bandgaps of the nanoparticles are 3.00 eV for CuS1, 3.26 eV for CuS2 and 3.13 eV for CuS3. The photocatalytic degradation efficiency showed that CuS3 with the smallest particle size is the most efficient photocatalyst and degraded 85% of CV, 100% of MB, and 81% of RhB. The as-prepared CuS showed good stability and recyclability and also degraded ternary dyes mixture (CV/MB/RhB) effectively. The byproducts of the dye degradation were evaluated using ESI-mass spectrometry.

Oligofuran–Benzothiadiazole Co-oligomers: Synthesis, Optoelectronic Properties and Reactivity

Donor–acceptor–donor (DAD) triad systems are commonly applied as active materials in ambipolar organic field-effect transistors, organic solar cells, and NIR-emitting organic light-emitting diodes. Often, these triads utilize oligothiophenes as donors, whereas their oxygen-containing analogs, oligofurans, are far less studied in this setup. Here we introduce a family of DAD triads in which the donors are oligofurans and the acceptor is benzothiadiazole. In a combined computational and experimental study, we show that these triads display optical bandgaps similar to those of their thiophene analogs, and that a bifuran donor is sufficient to produce emission in the NIR spectral region. The presence of a central acceptor unit increases the photostability of oligofuran-based DAD systems compared with parent oligofurans of the similar length.

Experimental Investigation on the Sputtering Process for Tantalum Oxynitride Thin Films

Metal oxynitrides are compounds between nitrides and oxides with a certain level of photocatalytic functions. The purpose of this study is to investigate an appropriate range of oxygen flow rate during sputtering for depositing tantalum oxynitride films. The sputtering process was carried out under fixed nitrogen but variable oxygen flow rates. Post rapid thermal annealing was conducted at 800 °C for 5 min to transform the as-deposited amorphous films into crystalline phases. The material characterizations of annealed films include X-ray diffraction and Raman spectroscopy for identifying crystal structures; scanning electron microscope for examining surface morphology; energy-dispersive X-ray spectroscopy to determine surface elemental compositions; four-point probe and Hall effect analysis to evaluate electrical resistivity; UV-visible-NIR spectroscopy for quantifying optical properties and optical bandgaps. To assess the photocatalytic function of oxynitride films, the degradation of methyl orange in de-ionized water was examined under continuous irradiation by a simulated solar light source for six hours. Results indicate that crystalline tantalum oxynitride films can be obtained if the O2 flow rate is chosen to be 0.25–1.5 sccm along with 10 sccm of N2 and 20 sccm of Ar. In particular, films deposited between 0.25 and 1.5 sccm O2 flow have higher efficiency in photodegradation on methyl orange due to a more comprehensive formation of oxynitrides.

NEW 3,5-DISUBSTITUTED 2,6-DICYANOANILINES CONTAINING 3,4-ETHYLENEDIOXYTHIOPHENE FRAGMENTS: SYNTHESIS AND FURTHER TRANSFORMATION

Some novel 3,5-disubstituted 2,6-dicyanoanilines incorporating 3,4-ethylenedioxythiophene (EDOT) fragment were prepared and investigated. Two different synthetic procedures have been applied for this purpose. One of them consists in the cyclization of chalcones with the malononitrile excess, another one relies on the one-pot three-component strategy. Condensation of thus prepared 3,5-disubstituted 2,6-dicyanoanilines with 3,4-ethylenedioxythiophene-2-carboxaldehyde (EDOT-CHO) has successfully given rise to the corresponding Schiff bases. UV absorption and fluorescence spectra were recorded for the chloroform solutions of the synthesized compounds. The influence of the changes in the compounds’ molecular structure on the UV absorption and fluorescence maxima as well as on the absorption edge position has been analyzed. It has been revealed that the π-conjugation chain elongation results in the red shift of the UV absorption and fluorescence maxima (λmax). The absorption red edge values (λonset) of the Schiff bases’ solutions were found to be crucially shifted to the longwave region if compared with the ones obtained for the solutions of the initial 2,6-dicyanoanilines (142 and 170 nm). The strong bathochromic shifts were also detected for their fluorescence maxima (72 and 114 nm). The optical bandgaps (Egopt) calculated on the basis of the λonset values were found to be less than 2.5 eV for all prepared compounds. Cyclic voltammetry method was used to study the electrochemical behavior of the Schiff bases, as a result the values of the onset oxidation potentials (Eoxonset) were determined and used for calculation of such important characteristics of molecules as the frontier orbital energies (EHOMO и ELUMO). The structures of the synthesized compounds were confirmed by elemental analysis and by IR and 1H NMR spectral data.