Optical Properties Of Composite Films Research Articles

Quantum Study of the Optical Conductivity of Composite Films Formed by Bilayer Graphene and Single-Walled Carbon Nanotubes under Axial Stretching

In this article, quantum methods are used to study the optical properties of composite films formed by AB-stacked bilayer graphene and chiral single-walled carbon nanotubes (SWCNT) (12, 6) with a diameter of 1.2 nm. The analysis of optical properties is carried out on the basis of the results of calculating the diagonal elements of complex optical conductivity tensor in the wavelength range of 0.2–2 μm. Two cases of electromagnetic radiation polarization are considered: along the X axis (along the graphene bilayer) and along the Y axis (along the nanotube axis). The calculations are performed for three topological models (V1, V2, V3) of composite films, which differ in the width of the graphene bilayer and in the value of the shift between graphene layers. It is found that in the case of polarization along the X axis, the profile of the real part of optical conductivity in the region of extremal and middle UV radiation is determined by SWCNT (12, 6), and in the region of near UV and visible radiations, it is determined by bilayer graphene. In the case of polarization along the Y axis, the profile of the real part of optical conductivity in the region of extremal, near UV, and visible radiation is determined by SWCNT (12, 6), and in the region of the mid-UV range, it is determined by bilayer graphene. Regularities in the change in the profile of the surface optical conductivity of bilayer graphene-SWCNT (12,6) composite films under the action of stretching deformation along the Y axis are revealed. For models V1 (width of the graphene nanoribbon is 0.5 nm, the shift between layers is 0.48 nm) and V2 (width of the graphene nanoribbon is 0.71 nm, the shift between layers is 0.27 nm), the shift of the conductivity peaks in the region of extreme UV radiation along the wavelength to the right is shown. For the model V3 (width of the graphene nanoribbon is 0.92 nm, the shift between layers is 0.06 nm), the shift of the conductivity peaks to the right along the wavelength is observed not only in the region of extreme UV radiation, but also in the region of visible radiation. It is assumed that graphene-SWCNT (12,6) composite films with island topology are promising materials for photodetectors in the UV-visible and near-IR ranges.

Effect of nitrogen plasma on optical parameters of erbium nitrate doped hydroxyethyl cellulose film

Hydroxyethyl cellulose (HEC) doped with 3 wt% erbium nitrate film was prepared by casting from solution. The effect of plasma treatment on optical properties of composite film was investigated. The optical absorbance was measured in the wavelength region of 200–800 nm. . Electronic transition was proved to be direct allowed for pristine and plasma treated film. Tauc’s plots were used to determine the optical band gap (Eopt) of the samples under study. The energy gap was 5.30 eV for untreated composite film and the treated samples at 10, 20 and 30 min have lower values of optical band gap, 5.22, 5.20 and 4.90 eV respectively. It was also found that the Urbach energy values (Ee) were decreased under different plasma treatment times. It begins with 1.46 eV for untreated sample till it reaches 0.72 eV for 30-minute treated sample. Wemple–DiDomenico model parameters such as, oscillator energy, dispersion energy and zero-frequency refractive index values were calculated and their variations with plasma were studied. The color parameters for composite film are noticeably affected under plasma treatment.

Fabrication and Characterization of Lignin Particles and Their Ultraviolet Protection Ability in PVA Composite Film.

Recently, lignin utilization in advanced applications has gained much interest. Due to the limitation of the current use of standard lignin, lignin particles have recently gained attention in overcoming the challenge. In this work, the spherical lignin particles obtained from organosolv lignin (OL) were prepared using the dialysis method with tetrahydrofuran (THF) or ethanol as the solvent. From the result, it was found that the types of lignin and solvent, initial lignin concentration, and stirring rate strongly affected the size of fabricated particles. Moreover, the preparation of lignin particles using THF as a solvent showed more uniform and symmetric spherical lignin particles. The stability of the particle dispersion was examined under various pH conditions. Moreover, lignin samples were also introduced into the poly(vinyl alcohol) (PVA) for the production of ultraviolet (UV)-blocking composite film. Mechanical and optical properties of composite film were also observed. As a result, the prepared lignin–PVA composite film showed great ultraviolet (UV) protective potential in both UVA and UVB regions.

Ternary composite films with simultaneously enhanced strength and ductility: Effects of sodium alginate-gelatin weight ratio and graphene oxide content

This study aimed to simultaneously enhance the strength and ductility of films by adding graphene oxide (GO) into the sodium alginate (SA)-gelatin film system to prepare SA-gelatin-GO ternary composite films. The effects of the SA/gelatin weight ratio and the GO content on the morphology, structural, mechanical, hydrophobic, water vapor barrier, hygroscopic, and optical properties of composite films were investigated. Results showed that tensile strength and elongation at break values of the composite film with 0.5% GO content were significantly improved from 37.00 to 48.01 MPa and 20.19% to 25.75%, respectively, compared with the SA-gelatin film without GO, suggesting GO with the content of 0.5% simultaneously enhance the strength and ductility of the SA-gelatin film, which was due to the interaction of hydrogen bonds and the good dispersibility of GO in the film matrix. The surface hydrophobicity of composite films increased first and then decreased with increasing GO content. In addition, the hygroscopicity of composite films reduced due to the GO addition, especially when the GO content was 0.25%. The SA-gelatin-GO ternary composite films provide a good select for food packaging materials, especially the materials that require high strength and fine ductility.

Innovative Synthesis of Nickel Nanoparticles in Polystyrene Matrix with Enhanced Optical and Magnetic Properties

The effect of Ni nanoparticles addition on some optical and magnetic properties of polystyrene has been studied. For this purpose, Ni nanoparticles were synthesized by reduction method and added to polystyrene as a filler with different weight percentages (3, 5, 8 and 10 wt%) to form Ni–PS composite films. The films have been prepared by solution casting method. The structure of the prepared films were investigated by X-ray diffraction (XRD), where the obtained results reveals the existence of cubic phase structure of Ni nanoparticles embedded in semi crystalline PS matrix. The morphology of the synthesized Ni nanoparticles was described by high resolution transmission electron microscope (HRTEM). The individual Ni nanoparticles were needle like shaped particles while the agglomerated nanoparticles form sphere like shaped particles. The surface of the prepared Ni–PS composite films was examined by field emission electron microscope (FESEM).The optical properties of composite films was examined by UV–Vis technique. The transmittance was found to decrease while the absorbance increases with increasing the weight percent of nickel nanoparticles. The absorption coefficient, optical band gap, and extinction coefficient of the composite films were calculated. The results revealed a decrease in range from (4.54 to 3.91 eV), and an increase in both absorption coefficient, and extinction coefficient with increasing Ni nanoparticles. Magnetic hysteresis plots at room temperature of composites Ni–PS were studied. All samples demonstrate ferromagnetic behavior with well pronounced magnetic hysteresis except pure PS showed diamagnetic behavior. The exchange bias effect at room temperature was observed and discussed for Ni–PS composite films.

Surface plasmon spectroscopy of thin composite films of Au nanoparticles and PEDOT:PSS conjugated polymer

Abstract We studied the effect of Au nanoparticles (NPs) on optical properties of composite films of poly(3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) mixed with Au NPs of 20, 40 and 60 nm in diameter by surface plasmon resonance (SPR) spectroscopy. The excitation wavelength of SPR redshifts with increasing the concentration of Au NPs in the Au/PEDOT:PSS composite films. The SPR spectra were simulated by using transfer matrix method (TMM) and effective medium approximation (EMA). The SPR wavelength redshift was ascribed to the film thickness increase of Au/PEDOT:PSS composites rather than effective permittivity variation of the composite films induced with Au NPs inclusion.

The influence of surface plasmons on the optical properties of composite films on the basis of poly(3-hexylthiophene), fullerene derivatives, and nickel nanoparticles

It is shown that a previously discovered effect of the introduction of Ni nanoparticles into films on the basis of poly(3-hexylthiophene) and fullerene derivatives (P3HT: [60]PCBM: Ni), which consists in increasing the light absorption and photoluminescence quenching in the spectral range from 400 to 620 nm, can be theoretically explained as being a result of the influence of surface plasmon resonance of Ni nanoparticles on the optical properties of P3HT: [60]PCBM: Ni composite films.

Investigation of Mechanoluminescent Light-Emitting Devices Based on ZnS:Cu Composite Embedded Elastomer Film

A mechanically driven light-generating composite flims consisted of ZnS:(Cu,Al) and polydimethylsiloxane (PDMS) were fabricated by spin coating method. Effects of mechanical stresses on the structural, optical properties of composite films were investigated. X-ray diffraction(XRD) measurements showed the ZnS:(Cu,Al) microparticle based composite films showed a hexaginal zinc blende type crystal peaks without any other distinguishable phase. Field emission scanning electron microsope (FE-SEM) images showed that the ~ 900 um thick composite films fabricated and the mixed ZnS:(Cu,Al) microparticles were mostly surrounded by PDMS matrix. The mechanoluminescence intensity and color of composite films were strongly related to the external mechanical stress. The mechanoluminescence intensity increased with increasing mechanical stress and a color of the ZnS:(Cu,Al) based composite films shifted from green to blue [Commission internationale de L'Eclairage (CIE) color coordinates of (0.225, 0.444) to (0.171, 0.304)] as the increased mechanically stress. The best brightness of the composite films was 140 cd/m2 when it was exposed to external gas flow of 700 kPa.

Nonlinear optical characterization of the Ag nanoparticles doped in polyvinyl alcohol films

The effect of silver nanoparticles doped in polyvinyl alcohol (PVA) on the nonlinear optical properties of composite films is studied experimentally. Samples are PVA films of 0.14 mm thickness doped with different concentrations of silver nanoparticles. Nonlinear optical properties of doped polymer films are studied experimentally employing Z-scan techniques. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at 532 nm wavelength and 45 mW power. The effect of nonlinear refractive index of samples is obtained by measuring the profile of propagated beam through the samples and their nonlinear refractive index is found to be negative. The nonlinear absorption coefficient is calculated using open aperture Z-scan data while its nonlinear refractive index is measured using the closed aperture Z-scan data, leads to measuring the third order susceptibility |χ(3)|. Real and imaginary parts of the third-order nonlinear optical susceptibility |χ(3)| are decrease with increasing the concentration of Ag nanoparticles in the films. The values of thermo-optic coefficient are determined at different concentrations of silver nanoparticles for samples.

Optical, Electrical and Viscosity Properties of Poly (Vinyl Alcohol) Films Embedded with Cr2O3 Nanoparticles Synthesised by Biological and Electrochemical Methods

The effect of Cr2O3 nanoparticles embedded in PVA on the structural, electrical and optical properties of composite films is studied experimentally. Sample is PVA films embedded with different sizes and concentrations of Cr2O3 nanoparticles. Structural properties are studied using X-ray diffraction, SEM, and FTIR spectrum. Optical property is studied using UV-Visible spectroscopy. Results show that by embedding Cr2O3 nanoparticles in PVA, number of Bragg’s planes in the structure of polymer and its crystallinity are increased noticeably. The λmax of Cr2O3 undergoes a blue shift towards the lower wavelength after embedding. Scanning electron microscopy shows that the prepared Cr2O3 nanoparticles were dispersed and nearly uniform in diameter within the polymeric matrix. Frequency dependent conductivity, photo-voltaic activity and viscosity measurements of PVA and PVA-Cr2O3 nanoparticles composites films/solutions are also discussed. The induced structural changes, revealed through XRD and FTIR spectroscopy, are responsible for the observed changes in optical behaviour of PVA after embedding Cr2O3 nanoparticles in it.

Synthesis and optical properties of composite films from P3HT and sandwich-like Ag–C–Ag nanoparticles

Sandwich-like Ag–C–Ag nanoparticles (Ag–C–Ag NPs) were synthesized under mild hydrothermal conditions in a one-step method with Ag encapsulated in the centre, uniformly dispersed in a carbon matrix and on a carbon shell.

Structure and properties of composite films formed by cellulose nanocrystals and charged latex nanoparticles.

We report the structural and optical properties of composite films formed from mixed suspensions of cellulose nanocrystals (CNCs) and fluorescent latex nanoparticles (NPs). We explored the effect of NP concentration, size, surface charge, glass transition temperature and film processing conditions on film structure and properties. The chiral nematic order, typical of CNC films, was preserved in films with up to 50 wt% of negatively-charged latex NPs. Composite films were characterized by macroscopically close-to-uniform fluorescence, birefringence, and circular dichroism properties. In contrast, addition of positively charged latex NPs led to gelation of CNC-latex suspensions and disruption of the chiral nematic order in the composite films. Large latex NPs disrupted the chiral nematic order to a larger extend than small NPs. Furthermore, the glass transition of latex NPs had a dramatic effect on the structure of CNC-latex films. Latex particles in the rubbery state were easily incorporated in the ordered CNC matrix and improved the structural integrity of its chiral nematic phase.

Optical Properties of Composite Films Based on Copper Chloride in PMMA Matrix

The composite lms based on PMMA, CuCl2 and photoinitiator were prepared.Transmission spectra of the lms with and without photoinitiator were measured. The holo-graphic gratings were recorded, the sensitivity of the lms and surface structure of gratingswere studied. Microanalysis of the lms was performed in di erent part of structure elementsof grating.

Impact of composition and morphology on the optical properties of Si-NC/P3HT thin films processed from solution

Blends of Si nanocrystals (Si-NCs) and organic semiconductors are promising materials for new optical and electronic devices processed from solutions. Here, we study how the optical properties of composite films containing Si-NCs and the organic semiconductor poly(3-hexylthiophene) (P3HT) are influenced by the composition and morphology resulting from different solution-processing parameters and different solvents used dichlorobenzene vs. chloroform). The optical spectra of the hybrid films are described using a simple phenomenological model, with which we can discern the contribution of each material in the films to the optical properties. From this analysis, we obtain quantitative information about the composition and morphology of the hybrid nanostructured films, which otherwise would be obtained from more demanding microscopy and spectroscopy techniques. For the case of the Si-NC/P3HT blend, we find that in films deposited from dichlorobenzene solutions the Si-NCs contribute sizably to light absorption.

Effect of Ag-Nanoparticles Doped in Polyvinyl Alcohol on the Structural and Optical Properties of PVA Films

The effect of silver nanoparticles doped in PVA on the structural and optical properties of composite films is studied experimentally. Samples are PVA films of 0.14 mm thickness doped with different sizes and concentrations of silver nanoparticles. Structural properties are studied using X-ray diffraction and FTIR spectrum. Using the reflectance and transmittance of samples, the effect of doped nanoparticles and their concentration on optical parameters of PVA films include absorption coefficient, optical bandgap energy, complex refractive index, complex dielectric function, complex optical conductivity, and relaxation time is extracted and discussed. The dispersion of the refractive index of films in terms of the single oscillator Wemple-DiDomenico (WD) model is investigated and the dispersion parameters are calculated. Results show that by doping silver nanoparticles in PVA, number of Bragg’s planes in the structure of polymer and its crystallinity are increased noticeably. Ag–O bonds are formed in the films and the bandgap energy of samples is decreased. Calculations based on WD model confirm that by doping nanoparticles, the anion strength of PVA as a dielectric medium is decreased.

Preparation and Properties of Biocomposite Film with Gelatin and Poly(<i>Vinyl Alcohol</i>)

The mechanical properties, swelling, solubility, and optical properties of composite films with poly(vinyl alcohol) (PVA) and gelatin were studied. With increasing the PVA content in the composite films, the tensile strength (TS) and elongation at break (EB) of the films increase. The swelling and solubility are different with different gelatin/PVA ratios, with the lowest at 1:5.

Nonlinear optical properties of composite films consisting of multi-armed CdS nanorods and ZnO

The multilayer composite films consisting of multi-armed CdS nanorods and ZnO were fabricated by spin coating and pulsed laser deposition on fused quartz substrates. The nonlinear optical properties such as nonlinear refraction and absorption were determined using closed- and open-aperture Z-scan method with 532 nm picosecond and 800 nm femtosecond laser pulses, respectively. The nonlinear optical response time was studied by a time resolved Kerr-gate technique at 800 nm, showing an instantaneous process. The large optical nonlinearity with ultrafast response of the composite films indicated their potential applications for future nonlinear optical devices.

Structural and Optical Properties of Sol–Gel‐Derived Au/BaTiO3 Nanocomposite Thin Films

Au/BaTiO3 nanocomposite thin films with different Au concentrations were prepared by a sol–gel process. The films were characterized using X‐ray diffraction, thermal analyses, X‐ray absorption spectroscopy, UV‐vis spectroscopy, and transmission electron microscopy. The effects of Au concentration and annealing temperature on the structural and optical properties of composite films were investigated. Gold doping lowered the crystallization temperature of as‐synthesized amorphous BaTiO3 and enhanced its crystallinity in post‐deposition annealing. The Au–BaTiO3 interface was also investigated and no alloying occurred between Au and BaTiO3. The evolution of Au surface plasmon resonance spectra with increasing annealing temperature was observed in the 10 mol% Au/BaTiO3 thin films. The variations of band‐gap energy for Au/BaTiO3 films were also discussed.

Formation of nanocomposite Langmuir–Blodgett alternate multilayers

Non-centrosymmetric alternate-layer Langmuir Blodgett (LB) films of stearic acid and eicosylamine molecules were treated with a twelve-hour-long exposure of hydrogen sulphide (H2S) gas. Surface plasmon resonance (SPR) experiments are carried out to monitor the change in optical properties of composite films. Structural analysis using atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy give a positive identification of the presence of cadmium sulphide (CdS) nanoparticles after the treatment. Quasistatic measurements give smaller pyroelectric activity in H2S-gas-treated LB films than untreated ones.

Poly( p phenylene vinylene)/porous silicon light emitting diodes

Optical properties of composite films formed by mixing poly ( p phenylene vinylene) and porous silicon (PPV/PS) with various concentrations were investigated by Raman, infrared (IR) and photoluminescence (PL) spectroscopy. Analysis of the Raman and IR spectra showed that PS was incorporated to the polymer matrix without effecting its properties. Modifications of the PL spectra were explained by the presence of oxygen from the PS grains. Light emitting diodes (LEDs) using the composite as an emitter exhibited low turn-on voltage as compared to PPV based devices.