Electrical characterization of in situ polymerized polyaniline thin films (original) (raw)
Effect of annealing on electrical conductivity and morphology of polyaniline films
Journal of Applied Polymer Science, 2001
We report structure–property relationships of polyaniline emeraldine base (EB) films that were produced by combining different processing steps in various sequences. The effect of annealing and doping processes on the surface structure of the films was investigated by atomic force microscopy (AFM), and the corresponding changes to the chemical structure of the EB films were monitored by Fourier transform infrared spectroscopy. AFM results indicate that after doping polyaniline (EB) films with HCl, the root mean square (rms) roughness of the surface of EB film increased ∼ 46%. When the doped films were annealed at 180°C under a nitrogen atmosphere for 3 h, the rms roughness was essentially unchanged from that of the initial, undoped films. The electrical conductivity of the films also showed a significant dependence on the processing sequence. When the doped polyaniline (EB) films were annealed, no electrical conductivity was observed. When these films were redoped, only ∼ 6% of the initial conductivity could be recovered. In another processing sequence in which the polyaniline (EB) films were first annealed and then doped, the electrical conductivity was only ∼ 12% relative to the film that was doped immediately after being cast. From this work, a strategy to reduce the surface roughness of films made from electrically conducting polyaniline (EB) is proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3602–3610, 2001
A Study on The Conductivity of Polyaniline Polymers
IOP Conference Series: Materials Science and Engineering
Polyaniline (PANI) is a promising conducting material to be used in a variety of electronic applications ranging from sensors, through solar cells to touch screens. Enhancing the electrical characteristics of polyaniline by increasing the charge carriers, using doping materials, allows for using it as a good alternative for semiconductors in the fabrication of integrated circuits. Zinc sulfide (Zns) is considered one of the attractive doping materials that improve the electrical characteristics of polyaniline owing to the distinctive optical characteristics in the visible range. In this work, a practical study on the electrical properties of polyaniline doped with zinc sulfide is presented and compared with pure PANI. Different volume rates of doping are tested, experimentally, and the results are collected. Voltage-current characteristics and the activation energy levels are obtained for different temperatures. From the results, it has been observed that the conductivity increases by increasing the doping rate and inversely related to temperature. A low activation energy level and improved I-V characteristics are shown to be approachable by careful choice of doping rate. Polyaniline doped with zinc sulfide provides low cost conductors for integrated circuits industry.
Structure and electrical properties of the oriented polyaniline films
Journal of Applied Polymer Science, 1994
The structure of oriented polyaniline (PANI) films were characterized by elemental analysis, FTIR, XPS, SEM, and X-ray diffraction, and their electrical properties were measured as a function of the protonation state, elongation ratio, temperature, and applied pressure. A maximum conductivity at room temperature for oriented PANI films can be achieved up to 500 s/cm with conductivity anisotropy as high as 20 : 1. The temperature dependence of conductivity for both unoriented and oriented films at 77-300 K and applied pressure of 0-11.4 kbar is consistent with the 3-D variable-range hopping model; however, the hopping barrier of oriented films is one order magnitude lower than that of unoriented films. The mechanism of enhanced conductivity for oriented PANI films is discussed. 0 1994 John Wiley & Sons, Inc.
Impedance and voltammetric studies of electrogenerated polyaniline conducting films
Synthetic Metals, 1994
Polyaniline thin films were electrochemically synthesized from aniline in three acids: sulfuric, hydrochloric and perchloric. Cyclic voltammetry was used in the electrosynthesis, and the relationship of voltammetric parameters and the properties of the conductive form of the films were investigated. The main tool for film characterization was impedance spectroscopy. Semiautomated plotting of three-dimensional Argand diagrams with a potential parameter was used for synoptic view of the system and nonlinear least-square data fitting was used for rigorous treatment. Charge storage capacity, resistance and changes in constant phase element parameters were analyzed in relation to the use of the three acidic media.
Advanced Materials Letters, 2015
Self-standing polyaniline (Pani) films modified with gold nanoparticles (Au NP's), where Au NP's are added in different successive weight percents, have been synthesized by conventional chemical polymerization technique. An in-depth investigation of the structural and electrical characteristics of prepared films has been conducted using various characterizations. The X-ray diffraction (XRD) validates the presence of Au NP's in Pani and the results are supported well by energy dispersive X-ray analyzer (EDX). The field emission scanning electron microscopy (FESEM) clearly shows thorough dispersion of Au NP's in the amorphous host matrix with minor aggregation. The Fourier transform infrared red (FTIR) studies give the information of possible chemical interaction between the nanoparticles and polymer which is in good agreement with charge transfer mechanism proposed in the manuscript. The temperature dependent dc electrical conductivity has been observed to depend strongly on the nanoparticle loading and follows Mott's three-dimensional variable range hopping (3D VRH) conduction mechanism. Parameters obtained from Hall Effect measurements are of same order as is calculated by dc measurements which indicates a very good corroboration of results. Higher ac conductivity, dielectric constant and dielectric loss of nanocomposites have also been observed as compared to that of pure Pani.
Dielectric Spectroscopy of Conducting Polyaniline Polymer
International Journal of Polymeric Materials, 2006
The dielectric spectroscopy of conducting polyaniline polymers (PAN) in the form of emeraldine base and emeraldine salt were carried out in the temperature range 30 to 80 C 0 and in the frequency range 1Hz to 1 MHz. The imaginary part of the impedance Z" versus frequency exhibits a relaxation peak , the position of the peaks are shifted towards lower frequencies for concentrations below 0.1,while the peaks are shifted to higher frequencies for concentrations above 0.1. The PAN samples were protonated (doped) externally with various concentrations of aqueous sulfuric acid in the range of 0.05 to 0.5 molar. The thermal behavior of undoped and doped PAN samples has been analyzed using thermal gravimetric analysis and differential scanning calorimetry techniques reveal that transition in the thermal behavior has been observed for concentrations above 0.1 molar. The a.c conductivity measurements reveal that insulator to metal transition in the conductivity of these samples was observed for acid concentration greater than 0.1 molar. The a.c conductivity for the protonated samples bellow 0.1 molar follows an Arhenius behavior 0 ∂ ∂ T σ with two activation energies, while 0 ∂ ∂ T σ for acid concentration greater than 0.1.
Polyaniline has been chemically synthesised by oxidative polymerization of 0.1 M aniline monomer using 0.3 M dodecyl benzene sulphonic acid (DBSA) as a dopant. The formation of polymer has been confirmed by X-ray diffraction and FTIR measurements where as surface morphology has been observed using scanning electron microscope. The spin coated polyaniline film has been prepared over ITO coated glass substrate and its current voltage response has been analyzed using Schottky emission theory. The band gap of the material has been calculated using UV visible spectroscopy and found to be 2.7 eV. The current-voltage response of deposited film gives the value of barrier height (Ø b) and constant factor (β) as 0.307 eV and 1.89×10-4 , respectively. These films may have potential applications in electronic and optoelectronic sensing devices.