Understanding the Charge Carrier Conduction Mechanisms of Plasma-Polymerized 2-Furaldehyde Thin Films via DC Electrical Studies

Monomer 2-furaldehyde (FDH) was deposited onto the glass substrates in optimum conditions via a glow discharge using a capacitively coupled parallel plate reactor to obtain plasma polymerized 2-furaldehyde (PPFDH) thin films of different thicknesses. In order to realize the carrier conduction mechanisms, the direct current density against applied voltage (J-V) characteristics of these films with different thicknesses were investigated at different temperatures (T) in the voltage region from 0.5 to 49 V in Al/PPFDH/Al sandwich configuration. The J-V characteristics at various temperatures follow a power law of the form J ∞ Vn. In the low voltage region the values of n were recorded to be 0.80 ≤ n ≤ 1.12 and those in the high voltage region found to lie between 1.91 ≤ n ≤ 2.58, demonstrating the Ohmic conduction mechanism in the low voltage region and non-Ohmic conduction in the high voltage region. Theoretically calculated and experimental results of Schottky (βs) and Poole-Frenkel (βPF) coefficients display that the most probable conduction mechanism in PPFDH thin films is the Schottky type. Arrhenius plots of J vs. 1/T for an applied voltage of 5 V, the activation energies were 0.13 ± 0.02 and 0.50 ± 0.05 eV in the low and high temperature regions, respectively. However, for an applied voltage of 35 V, the activation energy values were found to be 0.11 ± 0.01 eV and 0.55 ± 0.02 eV, respectively in low and high temperature regions

Heat treatment effect on the structural, morphological, and optical properties of plasma polymerized furan-2-carbaldehyde thin films

The furan-2-carbaldehyde (PPFCD) amorphous polymer thin films, with several thicknesses, were deposited onto glass substrates using a glow discharge of monomer FCD at ordinary room temperature via plasma polymerization technique. The structural, morphological, and optical characteristics of the as synthesised PPFCD amorphous films were studied as a function of temperature via X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and ultraviolet-visible (UV–Vis) absorption spectroscopy. The amorphous nature of the thin films was ascertained in both as-synthesised and heat treated states using the XRD studies. The SEM micrographs display homogeneous and fracture free surface of PPFCD films and no remarkable variation in the surface morphology of the as synthesised films was detected owing to the heat treatment procedure. However, the EDX, and FTIR analysis represented some structural rearrangement originated from the heat treatment of the PPFCD thin films. The analysis of the UV–Vis absorption spectroscopy revealed that the absorbance of the films depend on the films thickness and the temperature of the heat treatment. The optical band-gaps of PPFCD amorphous films were found to be significantly decreased with the gradual rise in heat treatment temperature

Structural and optical properties of plasma polymerized pyromucic aldehyde thin films

Abstract: Plasma polymerized pyromucic aldehyde (PPPA) thin films have been deposited on to glass substrates by glow discharge technique. Scanning electron microscopy (SEM) graphs reveal that the surface morphology of PPPA thin films is uniform and flawless. FTIR analysis reveals that the chemical composition of PPPA films is different from that of the pyromucic aldehyde (PA). From the UV-vis spectra direct and indirect transition energy gaps were determined for as deposited PPPA thin films of different thicknesses

Structural, morphological, compositional and optical studies of plasma polymerized 2-furaldehyde amorphous thin films

Plasma synthesized 2-furaldehyde (PPFDH) amorphous polymer thin films of varying thicknesses were prepared in optimum conditions by a capacitively coupled parallel plate glow discharge reactor at room temperature. The structure, morphology, composition and optical properties of deposited PPFDH thin films have been investigated using X-Ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-Ray spectroscopy (EDS), as well as Ultraviolet–visible (UV–vis) absorption spectroscopy. XRD results confirmed the amorphous nature of the films. The smooth and uniform nature of the PPFDH thin films were observed by SEM images. FTIR analyses of monomer FDH and PPFDH thin films show that structural rearrangement has occurred due to the synthesis process taking place in the chemical structure. IR stretching bands obtained from DFT calculations of the optimized structures of monomer and polymer of 2-furaldehyde are in good agreement with the experimental results. UV–vis absorption spectra in transmittance as well as reflectance mode was utilized to compute absorption coefficient, allowed direct and indirect transition energy gaps, band edge sharpness, Urbach energy, steepness parameter, extinction coefficient, and dispersion and oscillator energy. The oscillator strength, moments of optical spectra, refractive index at infinite wavelength, high frequency dielectric constant, average oscilator strength, complex refractive index, dissipation factor, optical conductivity and skin depth were also determined by using measured UV–vis transmittance and reflectance spectra

Synthesis and aging effect of plasma-polymerized 2-furancarboxaldehyde amorphous thin films

Monomer 2-Furancarboxaldehyde (FCD) deposited via glow discharge technique onto glass substrates to produce plasma synthesized 2-Furancarboxaldehyde (PPFCD) thin films with different thicknesses. The various characteristics, such as the structural, optical, morphological and elemental properties of unaged (as deposited) as well as aged PPFCD thin films were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) absorption spectroscopy, environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectroscopic (EDAX) methods. The XRD studies indicated the existence of small crystallite domains or amorphous nature of the PPFCD films. The ESEM micrographs exhibited the uniform, pinhole, and fracture free surface of PPFCD films together with no queerish morphological variations due to the aging effect. On the contrary, the EDAX and FTIR spectroscopic studies illustrated some structural rearrangement owing to the aging of PPFCD thin films. The UV-Vis studies revealed that the direct and indirect optical band gaps (Edb and Eib), and steepness parameter (σ) of the aged PPFCD films were significantly reduced from 3.43 to 3.20 eV, 2.18 to 1.53 eV, and 0.0546 to 0.0524 respectively while the Urbach energy (Eu) value was slightly enhanced from 0.48 to 0.50 eV. This indicated that the aging has remarkable effects on the optical properties of the PPFCD films

Alternating current electrical properties of Argon plasma treated jute

Low temperature plasma (LTP) treatment, a kind of environment friendly surface modification technique, was applied to biodegradable and environment friendly jute fibre with the use of nonpolymerizing gas, namely argon, at various discharge power levels and exposure times with a definite flow rate. Scanning electron microscopy (SEM) microphotographs reveal that the roughness of the fibre surfaces increases with the increase of discharge power and exposure time. This is caused due to the bombardment of high energetic ions on the fibre surface and the fibres become sputtered. The capacitance and the electrical conductance of raw and LTP treated jute fibre were measured as a function of frequency at room temperature. The dielectric constant, conductivity, dielectric loss-tangent and the surface morphology of raw and LTP treated jute as a function of frequency were studied at room temperature. It was observed that for all the samples the dielectric constant almost constant at lower frequencies and then decreases gradually in the high frequency region. In addition, dielectric constant increases with the increase of plasma treatment time as well as discharge power. It is also observed for all the samples that the conductivity increases as the frequency increases with a lower slope in the low frequency region and with a higher slope in the higher frequency region. In addition, the conductivity decreases with the increase of plasma exposure time as well as discharge power. The conductivity increases with frequency due to the hopping mechanism of electrons. The dependence of the dielectric loss-tangent with frequency at different treatment times and discharge powers for all the jute samples show small relaxation peaks in the very low frequency region. The dielectric loss-tangent decreases with the increase of both plasma treatment time and discharge power. In addition, the relaxation peaks are shifted to the higher frequency region as the plasma treatment time as well as discharge power increases. At the low frequencies relaxation peaks indicate the possibility of interfacial polarization

Effect of salinity on dynamic dielectric properties of Sundori wood of Bangladesh

The dynamic dielectric properties of Sundari wood have been investigated for their dependence on saline content and various thicknesses of wood slice. Measurement of capacitance and loss tangent have been carried out in the range from 1 kHz to 13 MHz (Agelent 4192 A LF) at room temperature. The calculated values of the dielectric constant at oven-dry condition were found to be between 2.69 to .086 and was increased with the wood slice thickness. These results were varied with their saline content. The introduction of salt ions into the Sundari wood matrix increases the dielectric constant by a factor of two

Understanding the enhancement of the optical and electronic attributes of iodine-doped vacuum deposited tetramethylaniline (PPTMA) thin film coatings

This article presents a comprehensive analysis on vacuum deposited Iodine-doped plasma polymerized monomer N, N, 3, 5 tetramethylanilin (PPTMA) thin film coatings to comprehend the structural, morphological, chemical, optical, and electronic properties. The as-deposited PPTMA thin film coatings were characterized by means of X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) spectroscopy, and ultraviolet-visible spectrophotometry, respectively. The amorphous nature of the PPTMA thin film coatings was established via XRD analysis. The surfaces of the PPTMA thin film coatings were observed to be smooth and uniform. The IR studies pointed out that the I-atoms get connected to amine nitrogen sites of the TMA structure. The absorption peaks detected at 1683 and 1577 cm−1 indicated the existence of aromatic ring stretching, and the Csingle bondC stretched vibrations due to the I-doping into the PPTMA thin film coatings. It was further noticed that the iodine doping resulted the Nsingle bondH, Csingle bondN stretching vibrations shifting towards higher wave number sides of 3384 cm−1, and 1384 cm−1 respectively. In a similar fashion, the optical absorption peaks were also shifted towards the longer wavelength sides (from 300 nm to 380 nm). The direct energy band gaps of the PPTMA coatings were decreased 3.20–3.04 eV with increasing I-content. Similar types of behaviors were also observed for the indirect energy band-gaps and Urbach energy values of the PPTMA thin film coatings. However, the refractive index, high frequency dielectric constant, and static dielectric constant were gradually increased with the monotonic increase of coatings thickness due to subsequently enhanced I-content

Structural and optical behaviours of methyl acrylate-vinyl acetate composite thin films synthesized under dynamic low-pressure plasma

Low-pressure (33.33 Pa) plasma polymerized methyl acrylate and vinyl acetate composite thin films with various monomer compositions were deposited onto glass substrates. Under the same plasma conditions, the homopolymer thin films were also prepared. The thickness of the composite films was observed to vary between 117 and 213 nm depending on the monomer ratio. The composite films exhibit a smooth, pinhole-free, and immaculate surface morphology, surpassing that of the homopolymers. The energy dispersive x-ray study shows that the films contain mainly carbon and oxygen with 26.09–37.20 at% and 35.03 − 40.10 at%, respectively. The composite films contain more carbon contents which enhance the film stability. The appearance of some broad absorption bands in the Fourier transform infrared spectroscopy indicates structural changes in the PP films caused by the restructuring or dilapidation of monomer molecules while forming the polymer. The UV–visible spectra analysis reveal that the composite films exhibited a tunable optical band gap by adjusting the monomer ratio. The decrease of methyl acrylate monomer reduces the direct and indirect optical band-gap values of composite films from 3.15 to 3.00 eV and 2.35 to 1.74 eV, respectively. While Urbach energy values increases from 0.33 eV to 0.90 eV. All the films showed good transmittance properties (86 − 96%) in the visible range wavelength (550 − 800 nm). Other optical parameters are also found better in composite films which indicates the aptness of the composite films in various optoelectronic or electronic applications