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An innovative method has been used to reduce the bandgap of poly(vinyl alcohol) (PVA) polymer by addition of a nontoxic, inexpensive, and environmentally friendly material. The resulting materials are small-bandgap polymers, hence opening new frontiers in green chemistry. The doped PVA films showed a wide range of light absorption of the solar spectrum from 200 nm to above 800 nm. Nonsharp absorption behavior versus wavelength was observed for the samples. The refractive index exhibited a wide range of dispersion. Shift of the absorption edge from 6.2 eV to 1.5 eV was observed. The energy bandgap of PVA was diminished to 1.85 eV upon addition of black tea extract solution, lying in the range of small-bandgap polymers. Increase of the optical dielectric constant was observed with increasing tea solution addition. The results indicate that small-bandgap PVA with good film-forming ability could be useful in terms of cost–performance tradeoff, solving problems of short lifetime, cost, and flexibility associated with conjugated polymers. The decrease of the Urbach energy upon addition of black tea extract solution indicates modification of PVA from a disordered to ordered material. X-ray diffraction results confirm an increase of the crystalline fraction in the doped samples.

Chitosan : AgI solid polymer composite films have been prepared by the well-known solution cast technique. Electrical impedance spectroscopy was used to investigate the electrical percolation threshold phenomenon in this work. A wide dispersion can be seen in dielectric constant spectra at low frequencies. The dielectric constant at selected frequencies as a function of AgI concentration indicates the occurrence of electrical percolation threshold via the appearance of two distinguishable regions. The behaviour of dielectric constant and DC conductivity vs. AgI concentration are almost the same at low and high filler concentrations. The steep increase of dielectric constant and DC conductivity from 5 to 10 wt% of AgI was observed and a plateau was achieved from 10 to 20 wt% of AgI. The pattern of real part of electric modulus ( M ′) at selected frequencies is similar to dielectric constant. The existence of distinct peaks in M ′′ spectra with no corresponding peaks in ε ′′ spectra indicated that ionic and polymer segmental motions are strongly coupled. Argand plots of M ′′ vs. M ′ was used to detect the relaxation type process. The Argand plots at different temperatures exhibit incomplete semicircular arc with a diameter below the real axis.

This report presents a facile and efficient methodology for the fabrication of plasticized polyvinyl alcohol (PVA):chitosan (CS) polymer electrolytes using a solution cast technique. Regarding characterizations of electrical properties and structural behavior, the electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD) are used, respectively. Crystalline peaks appear in the XRD pattern of the PVA:CS:NH4I while no peaks can be seen in the XRD pattern of plasticized systems. The degree of crystallinity is calculated for all the samples from the deconvoluted area of crystalline and amorphous phases. Considering the EIS measurements, the most conductive plasticized system shows a relatively high conductivity of (1.37 × 10−4) S/cm, which is eligible for applications in energy storage devices. The analysis of the EIS spectra reveals a decrease in bulk resistance which indicates an increase in free ion carriers. The electrical equivalent circuit (EEC) model is used in the analysis of EIS plots. Dielectric properties are modified with the addition of glycerol as a plasticizer. It is proved that the addition of glycerol as a plasticizer lowers ion association. It also shows, at the low-frequency region, a large value of a dielectric constant which is correlated with electrode polarization (EP). The distribution of relaxation times is associated with conducting ions.

In the current study, a breakthrough methodology has been utilized to deliver polymer composites based on polystyrene (PS) with enhanced optoelectronic properties. In this work, bitumen (BT), which is enriched with hydrocarbons and N/O elements extracted from natural rocks, has been employed to alter the optical band gap of the PS polymer. It was found that the optical parameters of PS improved significantly, which is crucial from the technological application viewpoint. The PS: BT films have been prepared utilizing a simple solution casting method. Fourier transforms infrared (FTIR), Raman spectroscopy, UV-absorption spectroscopy, and X-ray diffraction were used to investigate the effect of (BT) loading on the structural and optical properties of PS. The XRD analysis revealed that the addition of BT into PS improved the crystalline phase structure for the composite films. The D and G bands related to order and disorder structures were distinguished in the Raman spectra of the bitumen. The FTIR spectra demonstrated a shift and constriction of the PS-O-H stretching bands upon incorporating BT, indicating a robust interaction between BT and the polymer matrix. Furthermore, the FESEM images revealed rough surfaces in the composite films. Optical characterizations reveal that integrating BT into PS films enhanced their reflectance and diminished their transmittance of incident light at visible and ultraviolet wavelengths. The optical properties, including the absorption edge, refractive index, and dielectric constant, encompassing both the real and imaginary parts, were analyzed. The dielectric constant increased when comparing the composite samples to the pure polystyrene sample. The optical energy gap dropped from 4.34 to 1.14 as the BT doping concentration increased to 2 mL. The band edge width, which characterizes the tail-localized states, increases with higher BT concentration. The results of the present work will revolutionize the field of polymer composites for photonics and optoelectronics, especially non-linear optics and laser attenuation.

Polymer blend electrolytes based on poly(vinyl alcohol):chitosan (PVA:CS) incorporated with various quantities of ammonium iodide were prepared and characterized using a range of electrochemical, structural and microscopic techniques. In the structural analysis, X-ray diffraction (XRD) was used to confirm the buildup of the amorphous phase. To reveal the effect of dopant addition on structural changes, field-emission scanning electron microscope (FESEM) was used. The protrusions of salt aggregates with large quantity were seen at the surface of the formed films at 50 wt.% of the added salt. The nature of the relationship between conductivity and dielectric properties was shown using electrochemical impedance spectroscopy (EIS). The EIS spectra were fitted with electrical equivalent circuits (EECs). It was observed that both dielectric constant and dielectric loss were high in the low-frequency region. For all samples, loss tangent and electric modulus plots were analyzed to become familiar with the relaxation behavior. Linear sweep voltammetry (LSV) and transference number measurement (TNM) were recorded. A relatively high cut-off potential for the polymer electrolyte was obtained at 1.33 V and both values of the transference number for ion (tion) and electronic (telec) showed the ion dominant as charge carrier species. The TNM and LSV measurements indicate the suitability of the samples for energy storage application if their conductivity can be more enhanced.

The current study used sustainable and green approaches to convey polymer composites with desired optical properties. The extracted green tea dye (GTD) enriched with ligands was used to synthesize zinc metal complexes. Green chitosan biopolymer incorporated with green synthesized metal complex using casting technique was used to deliver polymer composites with improved optical properties. The FTIR-ATR was used to identify the functional groups of the GTD, pure CS, and functional groups surrounding the synthesized zinc metal complex. Distinguished ATR bands were observed in green tea dye spectra, such as OH, C = O, and NH functional groups ascribed to various polyphenols. The ATR bands of the zinc metal complex compared to GDT established that GDT is crucial to capturing zinc cations and producing the Zn 2+ -metal complex. The broadness of the bands observed in CS-based composites inserted with the Zn 2+ - metal complex confirms strong interaction among the components of polymer composites. The XRD achievements confirm that CS films with different Zn2+- metal complex concentrations transferred to an amorphous composite. The XRD pattern of composite films establishes that the zinc metal complex scarified the crystalline phases of chitosan. Linear optical properties such as absorption, refractive index (n), and optical dielectric parameters were improved. The absorption edge of the composite’s films shifted to lower photon energies. Various models were used to determine the optical band gap. The band gap drops from when chitosan is loaded with a 36% Zn 2+ -metal complex. The Spitzer-Fan method is used to get the dielectric constant, and the Drude Lorentz oscillator model was used to calculate vital optical parameters, including N/m* , τ , and µ opt . The W-D single oscillator model was used to determine the E o and E d parameters. The values of optical moments ( M −1 and M −3 ) were calculated with the help of the W-D model. The oscillator’s strength ( ) and wavelength ( ) were determined via the Sellmeier model using the linear refractive index. The first-order nonlinear ( ), second-order non-linear ( ) and third-order nonlinear optical susceptibility ( ) were determined for all the films.

In this review paper, we present a comprehensive summary of the different organic solar cell (OSC) families. Pure and doped conjugated polymers are described. The band structure, electronic properties, and charge separation process in conjugated polymers are briefly described. Various techniques for the preparation of conjugated polymers are presented in detail. The applications of conductive polymers for organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic photovoltaics (OPVs) are explained thoroughly. The architecture of organic polymer solar cells including single layer, bilayer planar heterojunction, and bulk heterojunction (BHJ) are described. Moreover, designing conjugated polymers for photovoltaic applications and optimizations of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy levels are discussed. Principles of bulk heterojunction polymer solar cells are addressed. Finally, strategies for band gap tuning and characteristics of solar cell are presented. In this article, several processing parameters such as the choice of solvent(s) for spin casting film, thermal and solvent annealing, solvent additive, and blend composition that affect the nano-morphology of the photoactive layer are reviewed.

Interconnected spherical metallic silver nanoparticles (Ag NPs) were synthesized in the current study using a green chemistry method. The reduction of silver ions to Ag NPs was carried out with low-cost and eco-friendly quince leaves. For the first time, it was confirmed that the extract solution of quince leaves could be used to perform green production of Ag NPs. Fourier transform infrared spectroscopy (FTIR) was conducted to identify the potential biomolecules that were involved in the Ag NPs. The results depicted that the biosynthesis of Ag NPs through the extract solution of quince leaf was a low-cost, clean, and safe method, which did not make use of any contaminated element and hence, had no undesirable effects. The majority of the peaks in the FTIR spectrum of quince leaf extracts also emerged in the FTIR spectrum of Ag NPs but they were found to be of less severe intensity. The silver ion reduction was elaborated in detail on the basis of the FTIR outcomes. In addition, through X-ray diffraction (XRD) analysis, the Ag NPs were also confirmed to be crystalline in type, owing to the appearance of distinct peaks related to the Ag NPs. The creation of Ag NPs was furthermore confirmed by using absorption spectrum, in which a localized surface plasmon resonance (LSPR) peak at 480 nm was observed. The LSPR peak achieved in the present work was found to be of great interest compared to those reported in literature. Field emission scanning electron microscopy (FESEM) images were used to provide the morphology and grain size of Ag NPs. It was shown from the FESEM images that the Ag NPs had interconnected spherical morphology.

Biodegradable solid polymer electrolytes (BSPEs) have gained significant attention due to their exceptional processability, safety, and flexibility. This work presents the development of sodium ion (Na +) conducting ternary blended (BSPEs) using a standard solution casting technique. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) validated the complete salt dissociation and demonstrated the formation of polymer-salt complexes. The deconvoluted XRD spectra revealed the degree of crystallinity ( ) of electrolytes where the sample incorporated 40 wt% of NaSCN salt content (STC4) was found to be the lowest value. The deconvoluted FTIR spectra were used to estimate ionic transport parameters of diffusion coefficient ( ), ion mobility ( ), and carrier density ( ). Ionic conductivity and electrical properties of electrolyte samples were investigated by electrochemical impedance spectroscopy (EIS). The EIS results were fitted with electrical equivalent circuits to understand the electrical behavior of the films. The highest DC conductivity value ( ) of (2.74 × 10 −6 S/cm) was achieved for the STC4 sample, attributed to its highest amorphous region and carrier density. The dielectric studies proved beneficial in distinguishing the areas attributed to molecular polarizations and electrodes. The reduction of relaxation time is indicated by shifting loss tangent peaks (tan δ) toward high frequency ranges. According to dielectric relaxation studies, the appearance of peaks confirmed non-Debye type behavior. Distinct areas attributed to the effects of electrode polarization and ( ) are seen in AC conductivity ( ) spectra.

In this study, conducting polymers composed of polyaniline hydrochloric acid (PANI/HCl) with varying concentrations of a newly synthesized azo-azomethine dye (4-(((Z)-2-hydroxy-5-((Z)-(4-hydroxyphenyl)diazenyl)-3-methoxybenzylidene)amino)benzoic acid) were synthesized using a chemical oxidative polymerization technique. The synthesized azo-azomethine was characterized by FTIR, 1 H-NMR, 13 C-NMR, and HRMS. The effects of varying the concentration of the dopant azo-azomethine in PANI/HCl on its optical, structural, thermal, and electrical properties were examined using FTIR, UV–Vis, XRD, FESEM, TEM, cyclic voltammetry, and electrical impedance spectra. The results indicate that the optical, direct, and indirect band gaps of the doped polymers decreased from 4.48 and 3.96 eV to 3.91 and 2.49 eV, respectively. The crystalline structure and phase transitions in the doped polymers were examined using X-ray diffraction. Cyclic voltammetry demonstrated that the doped polymers exhibited higher electrochemical conductivity compared to the pure polymer, with the specific capacitance increasing from 161.17 to 816.9 F/g. The electrical impedance spectra revealed the bulk resistance and conductivity of the material. Among all the doped polymers, PANI/HCl with an azo-azomethine concentration of 5 × 10 −5  M exhibited lower bulk resistance (10 Ω) and higher electrical conductivity (σ = 50.09 × 10 −3  S cm −1 ).