UV Vis NIR Spectroscopy Research Articles

Foam flows in turbulent liquid exfoliation of layered materials and implications for graphene production and inline characterisation

Surfactants are often used to stabilise two-dimensional (2D) materials in environmentally friendly solvents such as water. Aqueous-surfactant solutions prevent agglomeration of nanosheets through steric and electrostatic repulsion, facilitating the production of high concentration nanomaterial dispersions. Turbulent, shear-assisted liquid exfoliation of layered precursor materials produces defect-free nanosheets by promoting mixing and generating sufficiently high shear rates to overcome out-of-plane van der Waals bonds. In the presence of a liquid–gas interface, a consequence of using surfactants in turbulent flows is the formation of foam. In this experimental study, batch exfoliation of graphite particles into few-layer graphene was performed using a kitchen blender modified to operate across Reynolds numbers, Re∼105–106. Foam formation during turbulent operation was found to influence the hydrodynamics of the liquid exfoliation process. Measurements on the motion of graphite particles indicate that surfactant concentration can alter the rheology of the mixture under dynamic conditions and change the material flow patterns within the device. As a result, the surfactant concentration that maximised graphene concentration was found to be non-unique. This highlights that the design and selection of surfactants should consider both molecular scale repulsion effectiveness and macroscale hydrodynamics of the liquid exfoliation process. Furthermore, the multi-phase turbulent flows and complex fluids that exist during batch exfoliation in aqueous-surfactants create major challenges for realising in situ 2D material characterisation and quality control. Here, we have developed a protocol to enable inline UV–VIS–NIR spectroscopy to determine graphene production and atomic layer number changes in-process. These insights on exfoliation and characterisation of graphene in aqueous-surfactant dispersions can help advance the development of resource-efficient large-scale production of high-quality 2D materials for future technologies.

Low-cost thermo-chemical process of TiO2powder purification: study of iterative gettering effect

The titanium dioxide (TiO2) purity is very important for the TiO2-based applications making essential the impurities density reduction. In this study, we propose an efficient purification process of TiO2powder in order to reduce impurities. The low-cost proposed approach is based on an iterative gettering (IG) process combining three main steps: (1) a porous TiO2sacrificial layer formation (p-TiO2), (2) a rapid thermal annealing (RTA) of p-TiO2powder in an infrared oven at 950 °C under air permitting the residual impurities diffusion to the porous layer surface and (3) etching in acid solution to remove the porous layer. Effect of the proposed gettering process on purification efficiency was evaluated by different characterization techniques such as the transmission electron microscopy (TEM), the energy dispersive X-ray spectroscopy (EDX), the UV–Visible-NIR spectroscopy, the X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS). The obtained results showed the efficient removal of metal impurities, such as Cu, Al, P, and Fe confirming the efficiency of the process improving the purity from 89% to 99.96%.

Synthesis, growth, structural, spectroscopic, optical, thermal, DFT, HOMO–LUMO, MEP, NBO analysis and thermodynamic properties of vanillin isonicotinic hydrazide single crystal

• The vanillin isonicotinic hydrazide (VINH), an organic single crystal • Single-crystal X-ray diffraction to determine the cell dimensions • Powder X-ray diffraction to evaluate the planes and phase purity of the crystal • Spectral, optical, and thermal properties were studied. • Further, DFT, HOMO–LUMO, MEP, HOMA, NBO analysis were studied • The dipole moment, linear polarizability, and first hyperpolarizabilities have been investigated as molecular parameters. The work is aimed to present the synthesis and physical analysis of vanillin isonicotinic hydrazide (VINH), an organic single crystal, produced by the method of slow evaporation at room temperature. The grown VINH crystal was subjected to (SXRD) single-crystal X-ray diffraction to determine the cell dimensions. The powder X-ray diffraction study was performed to evaluate the planes and phase purity of the crystal. The presence of functional groups were analyzed through FTIR spectroscopy. UV–Vis–NIR spectroscopy study was carried out to enumerate the cutoff wavelength. Thermogravimetric and differential thermal analysis (TGA/DTA) was done to identify the thermal properties of the grown crystal. Further, the density functional theory (DFT/B3LYP) methods with the 6-311++G(d,p) basis set were used to compute the optimized molecular structure, HOMO-LUMO, molecular electrostatic potential surfaces, and vibrational studies of VINH crystal. The low HOMO - LUMO energy gap shows that the charge transfer inside the molecule is possible. NBO analysis proved the presence of intermolecular ON...H hydrogen bonds caused by the interaction of the lone pair of oxygen with the anti-bonding orbital. The dipole moment, linear polarizability, and first hyperpolarizabilities have been investigated as molecular parameters.

Effect of source-substrate distance on the transparent electrode properties of spray pyrolysed aluminium doped zinc oxide thin films

The wide band gap zinc oxide is a potential metal oxide that has been widely used in optoelectronic applications. The zinc oxide thin films demonstrate excellent conductivity and transparency enabling them for transparent electrode applications. The aluminium doping is an efficient route in further improving the conductivity without compromising the transparency and scalable spray pyrolysis is an effective approach in realizing high quality thin films. Our current study focuses on the effects of distance between the substrate and spray nozzle on the structural, morphological, optical, and electrical properties of aluminium doped zinc oxide. Our results suggests that this spray parameter has appreciable impact on the thin film properties and can be optimized for tuning properties. We explain this in detail backed by the characterization of thin films by X-ray diffraction, Atomic Force Microscopy, UV–Vis-NIR spectroscopy, Photoluminescence and Hall effect measurements.

Deposition and characterization of stannite Cu2FeSn(S0·8Se0.2)4 thin film for potential absorber layer in solar cell application

This work investigates the properties of CFTSSe material synthesized by melt quench technique and subsequent thin film deposition using thermal evaporation method. To study the compositional, structural, morphological and optical properties of the material, various characterization techniques like XRD, SEM, EDS, Raman spectroscopy, FTIR and UV–Vis–NIR spectroscopy have been applied. These studies show that CFTSSe is crystalline in nature and consistent with the stannite structure. Whereas some large density electronic defects have been detected in the lattice. UV visible spectroscopy estimates a high absorption coefficient (>104 cm−1) and optimal band gap of 1.49 eV. Additionally, the properties of CFTSSe are also compared with our previous study of CZTSSe and appeared to have potential to be used in thin film solar cell applications.

Development of smart window using an hydroxypropyl cellulose-acrylamide hydrogel and evaluation of weathering resistance and heat shielding effect

Reducing the amount of electricity used by cooling systems is essential for lowering CO 2 emissions; therefore suppressing increases in room temperature in an environmentally friendly manner requires the development of heat-shielding materials that autonomously control sunlight without the use of electricity. Hydroxypropyl cellulose (HPC) has attracted attention as a lower critical solution temperature (LCST) type of temperature-responsive polymer. HPC is a thermochromic material that changes its optical properties in response to changes in external temperature. In this study, acrylamide (AAm) and HPC with various molecular weights were used to prepare HPC-AAm hydrogels, and their optical, heat-shielding, and weathering-resistant properties were evaluated. UV–vis–NIR spectroscopy revealed that the solar transmittance ( αT sol ) of the HPC-AAm hydrogel decreased while its solar reflectance ( αR sol ) increased with increasing HPC concentration above LCST. The αT sol of low-molecular-weight HPC was found to be lower than that of high-molecular-weight HPC. In addition, the temperature inside a box constructed using an HPC-AAm hydrogel window was approximately 10 °C lower than that constructed using glass alone. Furthermore, the optical properties of the HPC-AAm hydrogel were found to hardly deteriorated even when continuously exposed to heat and UV radiation for 150 h. Therefore, the HPC-AAm hydrogel prepared in this study is expected to be useful as a heat-shielding material. • Hydrogels based on hydroxypropyl cellulose (HPC) acrylamide (AAm) were prepared. • HPC-AAm hydrogels show high αT sol values below the LCST. • αT sol decreases and αR sol increases with increasing HPC loading above the LCST. • The L-HPC-AAm hydrogel led to lower temperatures inside a simulated room. • The HPC-AAm hydrogel is stable when continuously heated and UV irradiated.

Improving the thermoelectric performances of polymer via synchronously realizing of chemical doping and side-chain cleavage

Side-chain cleavage is an effective strategy to reconstruct the arrangement of polymer main chains, thus improving their electrical properties and corrosion stability. However, simultaneously realizing side-chain cleavage and chemical doping of polymer semiconductors have not been reported. Herein, a series of p-type polymer semiconductors with the incorporation of ester-cleavage groups (PBDTTT-TETx, X is the molar ratio of the cleavage ester groups and nondegradable alkyl groups) were designed and synthesized. The introduced functional ester side-chains on PBDTTT-TET0.5 can be degraded by a commonly used p-type dopant FeCl3 readily, resulting in the maximum 120-fold enhancement in electrical conductivity and 15-fold increase in power factor at the FeCl3 concentration of 30 mM, compared to the reference one (PBDTTT-PET0.5 with the nondegradable ester side-chains). Scanning electron microscopy, atomic force microscopy measurements and X-ray diffraction reveal that the increase of crystalline domains along with the side-chain cleavage contributes to the formation of (bi)polaron network. The improved doping efficiency can be reflected by their ultraviolet photoelectron spectroscopy and UV–vis-NIR spectroscopy results. Moreover, a further optimized power factor can be achieved for PBDTTT-TET0.05, which is 5.8 times higher than that of PBDTTT-TET. Therefore, molecule design strategy by incorporating FeCl3-cleavage ester groups into the π-conjugated backbones provided an effective approach to establish advanced TE materials.

Nanostructured TiO2 photocatalyst modified with Cu for improved imidacloprid degradation

We investigated the role of Cu(II) ions, their local atomic structure and chemical state in the Cu-modified immobilized nanostructured TiO2 photocatalysts used for imidacloprid degradation under UV/VIS-radiation. Catalyst samples were prepared via electrochemical anodization and modified with different Cu concentrations (0.2–1 M). The catalysts’ structure and morphology were characterized by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy, UV–VIS-NIR spectroscopy, Photoluminescence spectroscopy and X-ray absorption spectroscopy: extended X-ray absorption fine structure and X-ray absorption near edge structure. The EXAFS results indicate formation of Ti–O–Cu connections, suggesting that the Cu(II) cations are attached to TiO2 surface which contributes to the photocatalytic activity improvement, i.e. Cu(II) ions are free electron traps that reduce high recombination rate of photo generated charge carriers. The results here demonstrate the role of Cu(II) cations on photocatalytic activity of the Cu@TiO2 photocatalyst.

Fe-doped CuGaS2 (CuGa1-xFexS2) - Detailed analysis of the intermediate band optical response of chalcopyrite thin films based on first principle calculations and experimental studies

We have theoretically and experimentally studied the tailoring of intermediate bands in the CuGa1-xFexS2 chalcopyrite system. An ab initio density functional theory calculations within GGA + U approach have been performed to model pristine and Fe-doped CuGaS2 to understand their structural and electronic properties and thereby understand the origin of intermediate states produced with Fe doping. Thin films of the pristine and Fe-doped CuGaS2 of various compositions are deposited using chemical spray pyrolysis for the experimental studies. The crystal structure, morphology, and topography of the deposited thin films are examined using Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM), respectively. The binding energy and chemical composition of CuGa0.95Fe0.05S2 thin films are determined using X-ray Photoelectron Spectroscopy (XPS). The direct and intermediate band optical responses have been probed through UV–Vis–NIR Spectroscopy. Pristine CuGaS2 exhibits a direct bandgap of 2.43 eV, with formation of intermediate bands in Fe-doped CuGaS2 at 1.82 eV, 1.75 eV, 1.54 eV and 1.49 eV with varying Fe atomic percentage (X = 0.025, 0.05, 0.075, and 0.1 at. %). The optimum Fe concentration is determined to be X = 0.05 (CuGa0.95Fe0.05S2) as it exhibits the highest photocurrent (1.46 mA), electrical conductivity, and intermediate band optical response. The IB formation is further supported by the calculated density of states of the Fe doped CuGaS2 structure.

Experimental studies and new theoretical modeling on the properties of In2S3 thin films

Indium sulfide (In2S3) is a material extensively used as an alternative buffer layer to that of cadmium sulphide (CdS) for thin film photovoltaic applications. In this work, In2S3 thin films were obtained over SiO2 glass with various substrate temperatures (Ts) using the vacuum thermal evaporation method. The effect of Ts which varies from 25 °C to 300 °C on structural, optical and morphological homestead are reported and discussed here. Our deposited In2S3 films are typified via X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV–Vis–NIR spectroscopy. XRD analysis reveals the amorphous nature of all samples. AFM graphics reveals that the deposited layers are smooth along relatively high surface roughness. The UV–Vis–NIR spectra show a high transmittance for all samples ranging from 75% to 90%, over the region extending from the UV–Vis to the near-infrared. The evaluated optical band gap energy showed a decrease from 2.60 eV to 2.12 eV with increasing Ts, which might be attributed to the presence of high concentration of defects, in the compound band structure. These experimental data were confirmed by theoretical predictions obtained by transfer matrix method (TMM) simulations.

Microstructure and optical properties of PbSe nanocrystalline films prepared by magnetron sputtering

PbSe nanocrystalline films were prepared using magnetron sputtering with different sputtering powers and deposition times. The obtained samples were characterized by X-ray diffractometry (XRD), field-emission scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), confocal Raman spectroscopy, UV–Vis–NIR spectroscopy, and spectrofluorophotometry. The XRD and XPS results show that the crystallization quality improves and the Pb/Se atomic ratio tends toward 1:1 with increasing sputtering power and deposition time. The morphology of PbSe particles varies from near-spherical to rod-like or cotton-like and then to triangular with increasing deposition time, consistent with the changed main growth orientation. The optical band gap of PbSe films decreases with increasing film thickness and grain size. A visible photoluminescence peak is observed at 655 nm, and its intensity strongly depends on the crystallization quality and morphology of PbSe particles, which is well consistent with the XRD and SEM results. Therefore, PbSe films with good luminescence performance can be obtained by adjusting sputtering power and deposition time.

Optical spectroscopic studies on poly(methyl methacrylate) doped by charge transfer complex

Polymeric sheets of poly(methyl methacrylate) (PMMA) doped by charge-transfer (CT) complex of perylene/iodine (pyr/I 2 ), perylene/picric acid (pyr/PA) and perylene/chloranilic acid (pyr/CLA) were synthesized in methanol solvent at room temperature. The optical spectroscopic studies on PMMA polymer doped by charge transfer complex are determined by UV–Vis–NIR spectroscopy, Photoluminescence spectroscopy (PL), Vis–NIR diffused reflectance spectroscopy (DRS) and FTIR spectroscopy. The diffused reflectance spectroscopy (DRS) of the polymeric sheet samples is analyzed based on the Kubelka–Munk model. The indirect allowed optical band gaps of the polymeric sheet samples are estimated by applying absorption spectrum fitting (ASF) and Tauc's methods. Here we report the optical spectroscopic studies on PMMA polymer doped by charge transfer complex as potential materials to be used in optoelectronic devices. • Charge-transfer complexes have an important role in solar energy storage and organic semiconductors fields. • Polymeric sheets of PMMA doped by charge-transfer complex were synthesized. • Optical spectroscopic studies on PMMA polymer doped by charge transfer were investigated. • The optical band gap of polymeric sheets was calculated by the DRS, ASF and Tauc's equations. • The spectral behaviour of the refractive index and the specific polarizability were obtained.

Low cost copper zinc tin sulphide (CZTS) solar cells fabricated by sulphurizing sol-gel deposited precursor using 1,2-ethanedithiol (EDT)

In this paper, we report the preparation of crystalline CZTS thin films by sol–gel method followed by sulphurization using 1,2- Ethanedithiol (EDT) at 400 °C in a three zone horizontal tubular reactor equipped with computer controlled vacuum system. These films were characterized by XRD, Raman, Hall measurements and UV–Vis-NIR spectroscopy. XRD and Raman studies confirmed highly crystalline and single phase CZTS. Hall study revealed p-type semiconducting CZTS film having charge carriers density of 1.70 × 1018 cm−3 and the resistivity (ρ) of the order of 5.00 × 10−1Ω-cm. It was found that the direct band gap of 1.44 eV for CZTS film was seen from optical study. Further, double metal oxide layers having slightly different band gap were used to form a p-n junction with CZTS film. Cadmium-free solar cells with structure ITO/ZnO/CZTS/Ag (cell-1) and ITO/ZnO/com-TiO2/CZTS/Ag (cell-2) were fabricated. Electrochemical Impedance Spectroscopy (EIS) measurements were performed in the low frequency range with applied bias of 0.1 Volt for the devices. The EIS studies showed that the solar cell with ultrathin compact TiO2 layer provide a favorable path for the efficient charge transport process at the interface. The external quantum efficiency measured at 520 nm was found to be 62.5%. Cell-2 exhibited improved photovoltaic parameters with short circuit current density (Jsc) of 4.721 mA/cm2, fill factor of 0.46 and open circuit voltage (Voc) of 400 mV. The short circuit current density and fill factor of double metal oxide layers (cell-2) were increased by 78% and 46%, respectively, as compared to single metal oxide layer (cell-1).

Effect of Na doping on microstructures, optical and electrical properties of ZnO thin films grown by sol-gel method

Undoped ZnO film and Na doped ZnO films with different Na/Zn molar ratios were deposited on glass substrates by the sol-gel spin coating method. The X-ray diffraction (XRD) pattern showed that all the films exhibited a high c-axis orientation with a hexagonal wurtzite structure. The diffraction angle shifted significantly to the lower angle with sodium doping. X-ray photoelectron spectroscopy (XPS) analysis confirmed that Na was incorporated into the ZnO matrix by occupying Zn sites. Field emission scanning electron microscope (FESEM) and Atomic force microscope (AFM) analysis showed that the surfaces of the films consisted of homogeneously distributed dense grains. FESEM images also exhibited hexagonal-like shape nanoparticles. The UV–Vis–NIR spectroscopy exhibited very sharp near UV absorption edge. Hall effect measurement results indicated that the undoped ZnO film exhibited n-type conductivity, whereas the Na-doped ZnO films generally exhibited p-type conductivity and all of the films had low carrier concentration. Room temperature photoluminescence (PL) spectra showed an ultraviolet emission (380–384 nm) and a broad visible emission (450–700 nm).

Highly efficient natural-sunlight-driven photodegradation of organic dyes with combustion derived Ce-doped CuO nanoparticles

CuO nanoparticles doped with various concentrations of Ce (2, 4, and 6 mol%) were synthesized by using the solution combustion method. The as-synthesized nanoparticles were characterized by X-ray diffractometer (XRD), fourier transforms infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV–Vis–NIR spectroscopy and photoluminescence (PL) spectroscopy. XRD analysis revealed that the physical parameters such as crystallite size, strain, lattice parameters, dislocation density and stacking fault of CuO nanoparticles were affected after the doping of Ce. FTIR analysis showed that Ce dopants affected the average force constant and the average bond length of CuO nanoparticles. UV–Vis–NIR spectrum analysis showed an enhanced absorption spectrum and narrowed down of the bandgap of CuO from 1.39 eV to 1.28 eV with Ce doping and resulted in increasing refractive index and optical conductivity. PL emission spectra showed a decrease in intensities after doping with Ce by trapping photoinduced electron of CuO by Ce dopants. The photocatalytic activities of the as-synthesized sample were investigated by photocatalytic degradation of organic dyes such as Rhodamine-B (RhB) and Methylene blue (MB), with and without the assistance of H 2 O 2 under solar irradiation. The highest photocatalytic efficiency is obtained with Ce (4 mol%) doped CuO at 95.39% and 87.72% for RhB and MB dyes.

Newly developed glass samples containing P2O5–B2O3–Bi2O3–Li2O–CdO and their performance in optical and radiation attenuation applications

In this research, the radiation safety features and the optical properties of novel prepared glass samples with nominal compositions 45P2O5 + 25B2O3 + 20Bi2O3 + (10-x)Li2O+xCdO where x = 0, 2.5, 5, 7.5, and 10 have been studied. The XRD was utilized to exclude the crystal structure nature of the glass samples. The density of the samples increases while the molar volume decreases with the rise of the CdO incrementation ratio. The UV-Vis NIR spectroscopy was utilized to measure the absorbance rate of the fabricated glass sample. Based on the measured absorbance, some important parameters were evaluated, such as the energy gap, Urbach energy, refractive index. The Monte-Carlo simulation code was utilized to evaluate the radiation attenuation properties of the current glass samples in the energy range 0.015 till 15 MeV.

Influence of deposition time and applied voltage on the properties of electrophoretically deposited nickel oxide colloidal nanoparticles thin film

ABSTRACT In the present work, nickel oxide nanoparticles (NPs) have been synthesised, using the laser ablation technique in aqueous suspension. By applying the electrophoretic deposition (EPD) method with direct current (DC), the nickel oxide NPs obtained have been deposited on an aluminium substrate. During the EPD process, different films have been produced by a variety of deposition times and applied voltages. The characterisation of the samples, including nickel oxide NPs suspension and nickel oxide deposited thin films, was carried out through different methods, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy and atomic force microscopy (AFM). The crystalline structure of the samples inspected by XRD showed that nickel oxide existed in NPs suspension and all the thin films. The morphology of the deposited films and dried NPs has been obtained by SEM. By observing the SEM micrographs, it was shown that deposition time and applied voltage change the morphology of the deposited thin films. In addition, AFM results demonstrated that the electrophoretic parameters have an effect on the average particles size, thickness and roughness of the deposited films. The optical properties of the NPs and deposited films have been analysed by UV–Vis–NIR spectroscopy.

Growth and computational studies on vanillin isoniazid single crystals

In this paper, we performed the synthesis, characterization, and computational studies on Vanillin isoniazid (VIN) single crystals grown by the slow evaporation solution growth technique. The crystalline perfection and monoclinic crystal structure with space group Cc have been confirmed using single-crystal X-ray diffraction and powder X-ray diffraction method. The presence of various functional groups has been identified by FTIR and Raman spectroscopy. These data are in good agreement with theoretical and experimental values of FT-IR, FT-Raman.The optical absorption studies were carried out for the grown crystal VIN which has been analyzed by UV–Vis–NIR spectroscopy. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out to characterize the thermal stability of the VIN crystals. The quantum chemical calculations for VIN crystal are performed at the B3LYP, B3PW91, levels of theory with the 6–311++G(d,p) basis set. Finally, inter-and intramolecular charge transfer, hyper conjugative interaction of the compound is investigated from natural bond orbital (NBO) analysis. The Mulliken atomic charge of VIN single crystal has been investigated using theoretical calculations.

Structural, thermal, dielectric, nonlinear optical properties and DFT investigations of a novel material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide for optoelectronic applications

A new organic nonlinear optical (NLO) material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide (CDA) has been synthesized by reflux method. Single crystals were grown by slow evaporation technique and the crystal structure was elucidated by single crystal X-ray diffraction method. Density functional theory (DFT) calculations at B3LYP/6–31+ + G(d, p) basis set was used to predict the molecular geometry and were carried out further to comprehend the electronic structure, vibrational spectra, natural bonding orbitals (NBO), frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP). An optical transparency at the cut-off wavelength of 355 nm was determined by UV–Vis–NIR spectroscopy. Thermal behavior of CDA was studied by TGA/DTA analysis. The dielectric constant (e), dielectric loss (tan δ) and AC conductivity as a function of frequency and temperature was studied. Second Harmonic Generation (SHG) efficiency of the CDA was determined using Kurtz and Perry powder technique and was 0.5 times greater than that of the KDP crystal. The third-order nonlinear optical properties were investigated in solution by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title compound exhibited significant two-photon absorption (β = 2.228 × 10–4 cm W−1), nonlinear refraction (n2 = 1.095 × 10–8 cm2 W−1) and optical limiting (OL threshold = 2.511 × 103 W cm−2) under the CW regime. The nonlinear optical parameters were calculated using time-dependent Hartree–Fock (TDHF) method. The overall obtained results suggested that the studied CDA molecule could be a potential NLO material for frequency generator, optical limiters and optical switching applications.

Nanostructured FeS2 films: Influence of effective parameters on electrochemical deposition and characterization of physical properties

In this study, films of iron disulfide (FeS2) nanostructures are prepared by electrochemical deposition on the Fluorine-doped tin oxide (FTO) glass substrate. The effect of deposition parameters such as voltage, time, molarity, and also sulfurization temperature are studied as parameters affecting the physical properties of the deposited films. The prepared films are studied and characterized by analysis of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, photoluminescence (PL), and UV–Vis–NIR spectroscopy. Following sulfurization, the XRD analysis shows the cubic phase of pyrite. The phase purity of the prepared samples are confirmed by Raman spectroscopy and the presence of Fe and S elements is verified by EDX analysis. The micrograph of FESEM shows that different morphologies in porous, spherical, and flower-like forms in nanometer dimensions are obtained by changing the effective parameters. The PL spectrum shows the presence of emission bands in the visible region. With the increase in the sulfurization temperature, the light absorption intensity of the films increases and the energy band gap increases from 1.53 to 1.73 eV, confirmed by UV–Vis–NIR spectroscopic analysis. The Mott-Schottky's analysis shows the p-type conductivity. Based on the results, the amount of photosensitivity, photoresponsivity, and specific detectivity increases with the rise in temperature. The sample sulfurized at 250 °C, compared to the sample sulfurized at 200 °C, shows a remarkable photoresponsivity in the range of visible spectrum. The values of photoresponsivity, photosensitivity, and specific detectivity at 100 mW/cm2 intensity are 22.7 mA/W, 18.80%, and 0.37×109 (Jones), respectively. According to the obtained results, this material has the potential for use in the fabrication of high-efficiency optoelectronic devices.