Tracking the changes in the structural, optical and photoluminescent properties of CuCo2O4/MnS nanocomposites with different composition ratios

(1−x)CuCo2O4/xMnS (x = 0, 0.25, 0.5) nanocomposite samples were formed using hydrothermal and thermolysis procedures. X-ray diffraction (XRD) phase analysis showed the formation of only CuCo2O4 phase necessitating the inclusion of Mn and S ions into the CuCo2O4 lattice. Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the presence of Mn and S ions in the nanocomposite samples. Rietveld refinement method was applied to determine the cation distribution of the different ions between different sites. The cell parameter (a) has no fixed trend of change. The average crystallite size is almost the same for all samples with an average of 15 nm. The effect of insertion of Mn and S ions into the CuCo2O4 on the diffused absorbance, extinction coefficient, refractive index, dielectric properties, and nonlinear optical parameters was discussed in detail. The pristine CuCo2O4 nanoparticles have two direct optical band gaps (1.65, 2.74) eV which are decreased to (1.59, 2.56) and (1.58, 2.54) eV for the MnS content x = 0.25 and 0.5, respectively. The two indirect optical band gaps of pristine CuCo2O4 changed irregularly as the MnS amount increased in the nanocomposite. The PL spectrum of CuCo2O4 is shifted to higher wavelength in the visible region upon alloying with MnS. The photoluminescence (PL) intensity of the nanocomposite samples is smaller than that of CuCo2O4 sample. The emitted PL colors depended on the amount of Mn and S ions in the CuCo2O4 matrix.

Highly oriented quasi-2D layered tin halide perovskites with 2-thiopheneethylammonium iodide for efficient and stable tin perovskite solar cells

3D tin-based halide perovskites are promising light absorbers for the perovskite solar cells (PSCs) due to their non-toxicity, suitable optical band gaps, and excellent optoelectronic properties. However, the inherent rapid...

UV-Visible Characterization of Zinc and Potassium Zinc Pyrophosphate

New Zn2P2O7, K2ZnP2O7 and KZn1.5P2O7 compounds were synthesized with conventional solid solid reaction method. The optical properties have been studied by using UV-Visible spectrophotometer. The optical band gaps (Eg) were found to be 3.76 eV, 3.39 eV and 3.59eV respectively. Optical parameters such as refractive index, Cauchy’s parameters and conductivity were deduced. The refractive index fitting in the visible range and the dispersion parameters (E0 and Ed) of these compounds were estimated using the Wemple–DiDomenico model.

Dithienothiazine Copolymers – Synthesis and Electronic Properties of Novel Redox-active Fluorescent Polymers

Dithienothiazine copolymers are efficiently obtained by Suzuki polymerization or in situ lithiation-Negishi polymerization in good to excellent yields. Gel permeation chromatography was applied to characterize the dispersities and degrees of polymerization of these novel materials. Thermogravimetric analysis shows that the copolymers are stable towards sidechain cleavage up to 200 °C. The materials are deep red to black amorphous solids or resins and their absorption and emission spectra in solution reveal broad absorption bands in the visible and orange to deep red luminescence upon UV excitation. According to the optical band gaps these novel copolymers qualify as a new class of low band gap organic semiconductors.

Synthesis of Amorphous Conjugated Copolymers Based on Dithienosilole-Benzothiadiazole Dicarboxylic Imide with Tuned Optical Band Gaps and High Thermal Stability

Two alternating copolymers of dithienosilole (DTS) were designed and synthesized with small optical band gaps, flanked by thienyl units as electron-donor moieties and benzothiadiazole dicarboxylic imide (BTDI) as electron-acceptor moieties. The BTDI moieties were anchored to two different solubilizing side chains, namely 3,7-dimethyloctyl and n-octyl chains. An analysis of the effect of the electrochemical, optical, thermal, and structural characteristics of the resulting polymers along with their solubility and molecular weight is the subject of this paper. The Stille polymerization was used to synthesize PDTSDTBTDI-DMO and PDTSDTBTDI-8. The average molecular weight of PDTSDTBTDI-DMO and PDTSDTBTDI-8 is 14,600 and 5700 g mol−1, respectively. Both polymers have shown equivalent optical band gaps around 1.4 eV. The highest occupied molecular orbital (HOMO) levels of the polymers were comparable, around −5.2 eV. The lowest unoccupied molecular orbital (LUMO) values were −3.56 and −3.45 eV for PDTSDTBTDI-DMO and PDTSDTBTDI-8, respectively. At decomposition temperatures above 350 °C, both copolymers showed strong thermal stability. The studies of powder X-ray diffraction (XRD) have shown that they are amorphous in a solid-state.

Introducing the magnetic properties in Fe doped ZnO nanoparticles for spintronics application

Proper correlation among the microstructural, optical and magnetic responses of Fe doped ZnO nanoparticles have been established in this work. All the Fe doped ZnO nanoparticles (Zn1-xFexO: x = 0.00, 0.05, 0.10 and 0.15) were prepared using chemical co-precipitation route. Average crystallites size of 18 nm to 28 nm was estimated using Scherrer’s formula. Compressive microstrain was detected in pristine ZnO samples, which moved toward tensile regime upon introducing Fe ions of different weight percentages. Mean crystallites size obtained from Scherrer’s formula was found in almost exact match with the particle size estimated from HRTEM images. Nearly spherical ZnO nanoparticles were seen in HRTEM images and negligible agglomeration among particles was also observed. Direct optical band gaps were found in the range of 2.89 eV to 3.24 eV as estimated from Tauc plots. A decent ferromagnetic signature in non-magnetic ZnO nanoparticles was also introduced at room temperature with the doping of Fe ions.

Band Gap Narrowing and Electrical Properties of (1-x)BaTiO3-xSrFe0.5Nb0.5O3 Lead-Free Ceramics

The composite materials in the form of (1-x)BaTiO3-xSrFe0.5Nb0.5O3((1-x)BT-xSFN) are synthesized via the solid-state reaction route. Structure, optical behaviors and electrical properties of (1-x)BT-xSFN are studied. It can be noted that the structure of the synthesized solid solution changes from the tetragonal phase to the cubic phase with increase of x-value. Due to the increase in content of double perovskite SFN, the optical band gaps of doped BT decrease to a minimum of 2.66 eV, which is smaller than that of pure BT (3.21 eV). However, the ferroelectric property deteriorates with the addition of dopants, which result from the lattice distortion caused by the substitution of Sr2+ and Fe3+/Nb5+ for Ba2+ and Ti4+, respectively. These results provide new insights into the control of the structure, optical behaviors and ferroelectric properties in BT-based oxides.

Green Synthesis of Reduced Graphene Oxide by Using Reducing Sugars

Graphene is a promising candidate for a broad range application in many fields and it has attracted a lot of attention from the researchers due to its unique properties. The involvement of toxic chemicals in synthesisation process is quite worrying as they release toxic gases and cause an explosion. Hence, this research reports a facile and safer method where the improved Hummer’s method was used to synthesize graphene oxide. Chemical reagent reduction method was implemented to synthesize reduced graphene oxide where glucose, fructose and sucrose were used as the reducing agents. The structural and optical properties of GO and rGO was determined by using Fourier Transform Infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrometer. The FTIR analysis of the films showed the existence of a large amount of oxygen-containing functional groups in GO compared to G-rGO, F-rGO and S-rGO. Furthermore, the UV-Vis analysis of GO showed the presence of an absorption peak at 230 nm and also a shoulder at 301 nm. The reduction of GO by sucrose caused a red shift from 230 nm to 260 nm while the reduction of GO by glucose and fructose caused a redshift to 268 nm. By referring to Tauc’s plot method, it was observed that the optical band gaps of GO, G-rGO, F-rGO and S-rGO were 4.26 eV, 3.32 eV, 3.38 eV and 3.66 eV, respectively.