The ultraviolet–visible (UV–Vis) range (200–800 nm) optical behaviour of nanocomposite films consisted of poly (vinyl pyrrolidone)/poly (vinyl alcohol) (PVP/PVA) blend matrix and alumina (Al2O3) nanofiller (1–5 wt%) was characterized for their eco-friendly green technology-based optoelectronic device applications Absorbance, transmittance, and reflectance spectra of the (PVP/PVA)/Al2O3 films were analyzed to determine absorption coefficient, energy band gaps (direct and indirect), and Urbach energy The non-linear decrease in band gap values of these composites with increasing amount of Al2O3 in the polymer matrix was explained The wavelength-dependent values of refractive index, extinction coefficient, complex dielectric permittivity, and optical conductivity of these hybrid nanocomposites enhanced non-linearly with increasing filler concentration, as well as the dispersive energy, single oscillator strength, and optical susceptibility increased gradually All these optical parameters values of the (PVP/PVA)/Al2O3 nanocomposites are found controllable by Al2O3 contents and reasonably comparable with the results of other similar types of composites

Investigation on the optical properties of (PVP/PVA)/Al2O3 nanocomposite films for green disposable optoelectronics

Polymer nanocomposites (PNCs) are currently in high industrial demand for the development of a variety of technologically advanced flexible-type milli- to micro-sizes electronic components/devices. In the advances of PNC materials, herein, we have prepared the hybrid nanocomposite films taking tin oxide (SnO2) nanoparticles as filler and biodegradable poly(vinyl pyrrolidone)/poly(vinyl alcohol) (PVP/PVA) blend as host matrix. Analysis of X-ray diffraction (XRD) patterns, Fourier transform infra-red (FTIR) spectra, and the scanning electron microscope (SEM) images have shown the successful formation of these (PVP/PVA)/SnO2 nanocomposites. The percent degree of crystallinity of the nanocomposites and the diffraction peak intensities of the SnO2 filler in these hybrids were found to increase linearly when the filler concentration was enhanced from 1 to 5 wt%. Differential scanning calorimetry (DSC) thermograms confirmed that the SnO2 nanoparticles dispersion in the PVP/PVA matrix has led to an appreciable increase in the thermal properties of these composite materials. Ultraviolet–visible (UV–Vis) range spectroscopic measurements revealed that these PNC materials have the ability of UV radiation absorption in a controllable manner. The direct and indirect energy band gaps of these PNCs had systematically reduced up to that of the SnO2 band gap confirming them as band gap tunable optical materials. The results of dielectric relaxation spectroscopy (DRS) performed over the 20 Hz to 1 MHz frequency range revealed that the dielectric permittivity and also the electrical conductivity could be enhanced appreciably by increasing amounts of SnO2 nanoparticles in the PVP/PVA blend host matrix. The SnO2 nanofiller concentration-dependent effectively tailorable structural, thermal, optical, and dielectric parameters credit the multifunctionality of these biodegradable PNCs. Therefore, it is concluded that these flexible hybrid films could be useful in the realization of desirable design and workability of the next-generation variety of advanced optoelectronic, organoelectronic, and microelectronic components/devices.

Nanofiller concentration-dependent appreciably tailorable and multifunctional properties of (PVP/PVA)/SnO2 nanocomposites for advanced flexible device technologies

Tailoring the optical properties of PVA/PVP blend by doping with Cu/MnS nanoparticles

As an attempt to pave the way for developing the lithium polymer batteries, (PVA/PVP) blend filled with different weight percentages of lithium perchlorate (LiClO4) was prepared using solution casting technique. Morphological and microstructural properties of the SPE were studied via SEM, XRD and FT-IR spectroscopy, where its semicrystalline nature was confirmed. Thermal stability, dielectric properties, the relaxation dynamics inside the current system and electrical conduction behavior of the synthesized films were prudently studied. The electrical conduction mechanism inside the samples was interpreted using the Jonscher's double power law. Activation energy was calculated using Coats-Redfern and Broido models. The oblate semicircular arc observed in Nyquist curves indicated the non-Debye behavior of ions relaxation in the present SPE samples. This behavior was assured by the evident decrease in intensity of the M'' relaxation peak. The complex impedance analysis not only verified the dominance of the resistive nature over the capacitance but also demonstrated that the conduction in the SPE was only produced by the induced ions. Mixing LiClO4 filler at 8 wt.% with the PVA/PVP host matrix had a fruitful effect on amelioration in the structural, thermal and dielectric properties of the prepared composite sample. This beneficial enhancement recommends the (PVA/PVP)/LiClO4 composite to be used in fabricating lithium polymer batteries and energy storage devices with high performance.

Impedance, structural and thermal analyses of polyvinyl alcohol/polyvinyl pyrrolidone blend incorporated with Li+ ions for lithium-ion batteries

Hybrid polymer films of polyvinyl pyrrolidone (PVP)/polyvinyl alcohol (PVA) embedded with gradient levels of Bi-powder were prepared using a conventional solution casting process. XRD, FTIR, and SEM techniques have been used to examine the micro/molecular structure and morphology of the synthesized flexible films. The intensities of the diffraction peaks and transmission spectrum of the PVP/PVA gradually declined with the introduction of Bi-metal. In addition, filler changes the microstructure surface of the pure film. The modification in the microstructure leads to an enhancement in the optical absorption characteristic of the blend films. The indirect allowed transition energy was calculated via Tauc’s and ASF (Absorption Spectra Fitting) models. The decrease in the hybrid film’s bandgap returns to the localized states in the forbidden region, which led the present films to be suitable for photo-electric, solar cell, etc., applications. The relation between the transition energy and the refractive index was studied. The enhancement in the refractive index with Bi-metal concentrations led to use the as-prepared films in optical sensors. The rise of Bi-metal concentrations leads also to the improvement of the nonlinear susceptibility and refractive parameters. The optical limiting characteristics revealed that the higher concentration dopant films reduce the light transmission intensity which is appropriate for laser attenuation and optical limiting in photonic devices. The results suggest that hybrid films are promising materials in a wide range of opto-electronic applications.

/pdf/microstructure-study-and-linear-nonlinear-optical-3uggt8vz.pdf

Microstructure Study and Linear/Nonlinear Optical Performance of Bi-Embedded PVP/PVA Films for Optoelectronic and Optical Cut-Off Applications

Polymer rare-earth composite films PVA/PVP–xLa3+ (xwt%; x = 0, 3, 5, 10, and 15) were fabricated by the solution casting method. The structural parameters of these films were determined from X-ray diffraction (XRD) pattern analysis, and the complexation of La3+ ions with the polymer composite films was studied by Fourier transform infrared (FT-IR) spectroscopy. The optical energy gap (Eopt.) and the high-frequency refractive index (n) were determined from UV–Vis transmission spectra analysis. AC electrical conductivity and dielectric characterization of the polymer composite films have been investigated. The structural parameters of the inter-planar (d) spacing, crystallite length (D), and the average crystallite separation (R) and the FT-IR spectra indicate strong bonding of La3+ ions with the carbonyl groups of the polymer composite chains. The optical gaps of the films determined by Tauc’s relation and optical absorption fitting (ASF) exhibit a slight decrease by increasing La3+ ions content, whereas the refractive indices show a slight increase. High values of the dielectric parameter e′ and dielectric loss e″ were produced in pure PVA/PVP composite polymer films, and they tend to decrease by increasing La3+ ions content in the PVA/PVP composite films due to decreasing directional polarization and ionic polarization in the films with increasing La3+ ions content. The minimum energy loss occurred at 70 kHz and these materials may be selected to be used in energy applications. I–V characteristics show a linear-like ohmic behavior because La ions are bonded well in the structure of polymers and became part of it.

R. M. Kershi

Papers

Synthesis and characterization of La3+ ions incorporated (PVA/PVP) polymer composite films for optoelectronics devices