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Conducting polymers such as polyaniline (PANi) have been widely investigated as ammonia gas sensors due to their intrinsic redox states, good environmental stability, and suitability for low-cost and variable changing in electrical conductivity when exposed to acid and basic gases. In this paper we used both a hybrid PANi derivative, poly(o-methoxyaniline) (POMA)-vanadium pentoxide (V2O5) film, and new ac electrical measurement strategies to increase the ammonia gas sensor performance. Complex impedance measurements of POMA/V2O5 hybrid film showed linearity in response and a high sensitivity to ammonia in the 0–20 ppm range in both real (around 800%) and imaginary (around 3000%) components, which indicated that the film is a good candidate to use as an ammonia sensing material. FTIR spectra presented typical V2O5 and POMA bands and also presented a shifting to higher wave numbers in bands referring to the vanadyl group and primary amines, which indicated the presence of hydrogen bonds between oxide and polymer. Finally, the Cole–Cole theoretical model with an interface effect provided a good fit for the experimental results from electrical ac measurements.

Studies of xerogel vanadium pentoxide hybrids in the presence of polyaniline (V2O5/PANI) for ammonia gas detection are presented. The hybrid materials were obtained in an oxidative polymerization/intercalation process, in which gel reacted with the monomers of the polymers. In situ characterization revealed V2O5/PANI hybrids with lamellar structure. Finally, the electric impedance technique was used for determining the optimal frequency band for operation of an Ag/V2O5/PANI/Ag amperometric ammonia gas sensor, to achieve linearity and stability. The results indicate that the sensor can detect gaseous ammonia in the 0–54 ppm range of concentrations. This characteristic is important for successful applications in easy to handle and low-cost ammonia gas sensors for animal confinement husbandry, for which current variation and difficulties related to electrode effects and dielectric absorption of V2O5 and PANI are negligible.

Hyperbilirubinemia is a systemic global problem and an often diagnosed pathology in newborns. In most cases, blue-light phototherapy (410–460 nm) is the only treatment required to prevent the bilirubin neurotoxicity, but its effectiveness is dose-dependent and is highly affected by the skills, knowledge, and attention of nurses and clinicians who implement the treatment. This paper presents a novel light-sensitive colorimetric dosimeter to simulate the effect of blue-light phototherapy on the optical properties of in vitro bilirubin. The dosimeter is based on a multilayered organic structure comprising a light-stable green-light emitter (copper phthalocyanine, C 32 Cl 16 CuN 8 ), and a blue-light-sensitive red emitter (poly{[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene]vinylene}, OC 1O C 6 -PPV). The optical and chemical properties of the dosimeter were investigated by fluorescence and FTIR spectroscopies and by color coordinates of CIE (1931) diagram chromatics, while the photochemical processing of bilirubin was evaluated by UV–vis absorption spectroscopy. The optical response of the dosimeter under conventional (10 μW/cm 2 ) and intensive (40 μW/cm 2 ) phototherapy was found to present the same photochemical kinetics as bilirubin. These findings highlight a cutting-edge solution for monitoring bilirubin elimination in neonates as a function of the dosimeter’s color evolution. This novel colorimetric dosimeter provides a standardized method of reporting and measuring phototherapy dose to promote an efficient use of available phototherapy units in health facilities.

With the aim of improving phototherapy for neonatal jaundice (hyperbilirubinemia), this study investigates the degradation of unconjugated bilirubin under irradiance by conventional light and by white, red, green, and blue LED sources in vitro. The absorption spectra of bilirubin under these different light sources are compared. The results demonstrate that white LED phototherapy promotes more efficient bilirubin degradation than conventional blue-light therapy. This study provides a basis for the design of novel phototherapy devices for the treatment of hyperbilirubinemia.

This paper describes a variety of experiments that reveal the potential application of impedance spectroscopy (IS) measurements to enhance performance of ultrathin polyaniline (PANI)-based films on flexible substrate to control ammonia gas exposure in the 0–20 ppm range. Further, the device is mechanically robust for making electrical contact without lithography. We have employed the IS technique to proper adjust the optimal operation frequency of an easy-to-process, inexpensive and user-friendly PANI-based resistometric detectors in which drift current and delay problems related to electrode effects and dielectric absorption of PANI are insignificant. These requirements place emphasis upon the material and device configuration, and the range of frequencies from 10 to 100 Hz corresponds to the ideal working region to operate the device to unify sensibility inside 5%, reproducibility, linearity, stability and low response time (

Research in hybrid electronics has included advances in materials, devices and architectures. However, in practice, controversy still exists on some details which limit hybrid materials to high-performance applications, such as processing–structure–design–property relations. This paper describes a practical approach to enhancing the sensing performance of a prototype ammonia gas sensor based on electrical conductivity changes, percolation theory and current limitation to a semiconducting polymer-metal oxide medium. This device is based on fully-gravure printed polyaniline/indium - tin oxide nanocomposites, Pani100−xITOx [0 ≤ x≤ 100% (wt/wt)], layers on a freestanding high-density polyethylene substrate. We find that the electrical current of the device decreases and tends to saturate as the gas concentration increases, and the value of this electrical current limit (IL) depends on x: the higher the value of x, the smaller the IL, when the current that flows through the electronic device was dominated by the ITO-nanoparticle filled PAni, which increase the concentration of hopping carriers and contribute to the desired electrical response of a heterogeneous gas sensor. In this regime, we find a good linear relationship between x and ammonia concentration. These findings suggest new directions for future research on the development and investigation of organic-inorganic devices in which the electrical current variation is desired for enhanced sensitivity and stability of hybrid sensors.

In the present work, we concentrate on the study of effects of metallic electrodes, multilayer thickness and temperature in ac and dc electrical conductivity of polyaniline/poly(vinyl sulfonic acid) (PANI/PVS) ultrathin films. The polymer system was obtained from layer-by-layer (Lbl) self-assembly technique on a glass substrate with an electrode array of adhesion layer of NiCr (20 nm) covered with Au (180 nm). We observed a significant and abrupt increase in the value of dc conductivity and a change of ac conductivity behavior of NiCr/Au–PANI/PVS–NiCr/Au structure when the thickness of PANI/PVS system reaches the Au layer. These effects were ascribed to the ideal contact of Au–PANI/PVS and the relative high interfacial contact resistance between PANI/PVS and NiCr, thus reducing the parallel resistance of NiCr/Au–PANI/PVS interfacial layer in an ideal parallel plate capacitor structure. Atomic Force Microscopy images confirm this assumption. Furthermore, the ac conductivity of Au–PANI/PVS–Au structure was typical of solid disordered materials. A model based on carrier hopping in a medium with randomly varying energy barriers was presented for the ac conductivity of the polymer system, which also encompasses the high dielectric constant of PANI/PVS blended films, the neutral contact Au–PANI/PVS, and the electrical resistance of NiCr–PANI/PVS interfacial layer. The model allowed separating the interface and the bulk effects in the electrical response of NiCr/Au–PANI/PVS–NiCr/Au structure and in addition the highest activation energy (35 MeV) correlated with an optimization of hopping distance (30 nm) for carriers jumps in PANI/PVS system.

Neste trabalho as propriedades ópticas do poli[2-metóxi,5-(2’etil-hexiloxi)-p-fenilenovinileno] - MEH-PPV foram estudadas sob efeito de luz azul proveniente de super LEDs utilizada no tratamento da hiperbilirrubinemia neonatal (ou icterícia). Os resultados mostraram que o MEH-PPV apresenta uma mudança de cor do vermelho-alaranjado para o incolor, passando por diversas tonalidades de amarelo, bem como uma diminuição da intensidade dos espectros de absorção e de fotoluminescência (PL) em função do tempo de exposição à radiação. Essas mudanças foram usadas para projetar um sensor de acúmulo de dose de radiação azul, tipo indicador de cores, para avaliar a dose de radiação recebida por recém-nascidos durante o tratamento da icterícia neonatal. In this work we investigated the optical behavior of poly[2-methoxy-5(2’-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) under the effect of blue-light LED source applied in neonatal hyperbilirubinemia treatment. There is a visible response that covers the electronic absorption of bilirubin (350-500 nm), and hence this material is applicable for controlling the radiation doses in the treatment of jaundice of neonates, which is one of the most common reasons for hospital readmission of newborn infants. The results show that the material presents a gradation of color from orange-red to yellow and quenching on the absorption and photoluminescent (PL) spectra with the radiation exposure time. The rate of these changes can be altered by manipulations of organic solution concentration, suggesting these color and emission/absorption changes can be used to design an indicator-dosimeter that is readily associated with the radiation exposure time used in treating neonatal jaundice.

The central process of neonatal phototherapy by employing blue light has been attributed to the configurational conversion of (4Z,15Z)-bilirubin to (4Z,15E). Indeed, photoisomerization is the early photochemical event during this procedure. However, in this paper, we show that the bilirubin solutions under continuous blue light exposure undergo a photooxidation process. To ascertain the role of this photodegradation in the phototherapy, we evaluated UV–visible absorption spectra obtained from bilirubin solutions in CHCl3, milli-Q water, and physiological saline, as well as FTIR spectroscopy for bilirubin in CHCl3. These analyses also showed that the first 2 h of phototherapy are the most relevant period. In addition, quantum molecular modeling using B3LYP/6-31G(d,p) and ZINDO/S-CIS was performed to evaluate the electronic and structural properties of four bilirubin isomers, showing that the (4Z,15E)-bilirubin isomer is the most polar configuration. Therefore, it can be more soluble in aqueous environments than the other configurations. This clarifies why this is the faster isomer excreted during the phototherapy.

In this work, a plasma-enhanced chemical vapor deposition (PECVD) system was used to deposit carbon nitride at low deposition temperatures (ca. 100 °C) to improve the lifetime of polymer light-emitting diodes (PLEDs) and to decrease photo-degradation of MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinilene]) in air. The characteristics of the carbon nitride and MEH-PPV films are investigated with FTIR and UV–Visible spectroscopies, with particular emphasis on the degradation process of MEH-PPV under illumination. It was shown by absorbance measurements that the coating protects the polymer film since the damage caused by photo-oxidation diminishes considerably. Current vs. voltage curves for PLEDs also indicated that the protection of a carbon nitride layer enhances the device lifetime.

The properties of a commercial indium-tin-oxide (ITO) layer deposited on glass substrates were evaluated as a function of the treatment time in diluted aqua regia solution. The samples were characterized by atomic force microscopy (AFM), bulk conductivity, ellipsometry, energy-dispersive X-ray analysis (EDX), contact angle/surface energy, and work function measurements. The results show that shorter times of treatment do not affect significantly the ITO properties but decrease the ITO thickness. For longer times (more than 30 min), although the work function and In/Sn ratio are not affected by the treatment, conductivity, roughness, UV–VIS absorption spectra, and refraction index values are greatly affected. Contact angle and surface energy data indicated that the dispersive component of the surface energy was not affected by the treatments. However, a strong decrease in the polar contribution occurred, indicating that ITO surface becomes more hydrophobic as the chemical treatment proceeds. These treated surfaces can interact more strongly with nonpolar materials, such as poly-(p-phenylene-vinylene) derivatives, resulting in a strong polymer ITO adhesion that can improve the efficiency of polymer light-emitting diodes (PLEDs).

Complex conductance,ae ⁄ (f) = ae0(f)+iae"(f), measurements of polyaniline/carnauba wax composites were carried out at room temperature in samples containing different amounts of PAni. While ae"(f) ever grows as a function of the frequency f;ae0(f) was observed to vary as f n (n … 1) in the high frequency domain, and to be frequency-independent for lower frequencies. This is the quasi-universal behavior characteristic of conduction in a disordered medium. Superposed on this, another signal was observed to occur, and the whole impedance response was then analysed in an Argand Diagram, disclosing an electrode process in series with the bulk one. An equivalent conductance expression was used to explain such electrical behavior, in which the bulk properties of the composite were represented through the Random Free Energy Barrier model, while the composite-electrode interface by a simple parallel combination of a capacitor and a resistor. From the theoretical fittings it was concluded that the increase of PAni concentration acts in the sense of increasing not only the sample conductance, but also the bulk capacitance. The separation of the bulk and the interface contributions was then achieved.

In this paper we present the photoconduction effect of the poly( p -phenylenevinylene) (PPV) and its derivative, the poly[(2-methoxy-5-hexyloxy)-p-phenylenevinylene] (MH-PPV). The structures used to study photoconductivity were prepared using solutions of either PPV-precursor in methanol or MH-PPV in chloroform, both spin-coated on an interdigitated chromium-gold line array previously deposited onto glass substrate. Currents vs. voltage curves were carried out as well as of the films optical characteristics have been studied by UV-Vis, and photoluminescence and eletroluminescent spectroscopies.

In this paper we study the photo-oxidation phenomenon in the structure of a PPV derivative, the poly[(2-methoxy-5-hexyloxy)- p -phenylenevinylene] - (MH-PPV), using ellipsometry and infrared spectroscopy techniques. Ellipsometric measurements were carried out in MH-PPV films previously exposed to light irradiation in air. It was observed a variation of both real and imaginary components of the refractive index. These variations are related with the replacement of the vinyl C=C bounds by the carbonyl C=O bounds, as confirmed by the infrared absorption measurements.

The photodegradation of soluble electroluminescent polymers is one of the greatest problems to be overcome in order to improve their technological applications. Here we will report on preliminary evaluation of the effects of commonly used solvents on the photodegradation of poly(3-methoxy-5-dodecyloxy- p -phenylene-vinylene), MD-PPV. We prepared solutions of similar concentration of MD-PPV in different solvents and recorded the ultraviolet-visible spectra before and after the exposure to a 250 mW/cm 2 light intensity. Also, we prepared cast films with the same solutions (with similar thickness) in order to observe if the solvent also affects the properties of the films. The results showed that the solvent polarity seems to be not the unique factor affecting the photodegradation, since no direct correlation could be made. Among the solvents tested, tetrahydrofuran was the best solvent for preparing films in order to minimize the photodegradation process.

A report is made of Langmuir film of a new semi-amphiphilic alternating N-hexylpyrrole-thiophene AB copolymer (PHPT) that is amenable to transfer as Langmuir–Blodgett (LB) films. PHPT was synthesized by condensation copolymerization via Stille coupling between N-hexyl-2,5-bis(trimethylstannyl)pyrrole and 2,5-dibromothiophene in the presence of Pd(PPh3)2Cl2 as a catalyst in dry DMF and characterized with various analytical techniques. In contrast to homopolymers (e.g. poly(N-alkylpyrrole)s and poly(3-alkylthiophene)s), PHPT formed a reasonably stable monolayer, as inferred through surface pressure and surface potential isotherms, and Brewster angle microscopy (BAM). The dependence of monolayer characteristics on the spreading volume, subphase temperature and compression speeds was also investigated. Electrical characterization revealed the possibility of using PHPT LB films as gas sensors.

The ac complex conductivity σ*(f) of polyaniline (PAN) films at different doping levels and different temperatures, in the 1–100 KHz frequency range, are reported. The results are typical of a disordered medium where the real component of ac conductivity is frequency independent at low frequencies, rising for higher values of frequencies. In order to interpret both the real and the imaginary components of σ*(f), we developed a model which considers the doped PAN as a disordered insulating matrix, sprinkled with conductive islands generated by doping, as indicated by energy dispersed x-ray microanalysis. The conduction through the insulating matrix obeys the random free energy barrier model, while in the conductive islands a metallic frequency-independent conductivity is considered. From the fittings we obtained the activation energy value of the maximum energy barrier of the doping mechanism and estimated the concentration of hopping sites.

The control of the photo degradation of a fluorene–vinylene–phenylene based-polymer, poly(9,9-di-hexylfluorenediylvinylene- alt -1,4-phenylenevinylene) (LaPPS16) was achieved by addition of a radical scavenger (RS) (enhancing photo resistance) or a radical initiator (RI) (reducing photo resistance). Photoluminescence, UV–Vis absorption, 1 H NMR spectroscopies and gel permeation chromatography (GPC) revealed that the incorporating small amounts of RS or RI is an efficient way to control the rates of the photo-oxidation reactions, and thus to obtain the conjugated polymer with foreseeable degradation rates for applications in blue-light sensitive detectors for neonatal phototherapy.

We report on the investigations about the modification of optical properties induced by X-rays onto film detectors of cadmium tungstate (CdWO4), poly[2-methoxy-5(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and polystyrene (PS) This device takes advantage of reduction of spectral overlap between the radioluminescence (RL) of CdWO4 and the absorption of MEH-PPV as it is exposed to radiation, forming the basis of a new dosimeter that is capable of converting the orange-red radioluminescence of PS:MEH-PPV:CdWO4 into green. We propose an explanation of the optical processes occurring in MEH-PPV:CdWO4 in terms of the radiation hardness of CdWO4 combined to the RL-induced degradation of MEH-PPV.

Growth of the vanadium pentoxide xerogel in the presence of the polyaniline thin film (V2O5/PANI) in different chemical treatment on substrate are presented. The in situ characterization studies revealed the presence of a lamellar structure for the V2O5/PANI hybrid material. The intercalation reaction was evidenced on the basis of the increase in the d-spacing as well as the displacement of the absorption bands toward lower energy levels. The growth of V2O5/PANI thin film, from direct reaction, on glasses substrate using pre-treated with cationic surfactant cetyl pyridinium chloride (CPC) and cetyl trimethylammonium bromide (CTAB) presented layers with a surface homogeneous. The UV/ozone and RCA treatment showed that the film had low adhesion on substrate compared with CPC and CTAB treatment. Furthermore, these results suggests that the CTAB and CPC treatment can be used, further, for V2O5/PANI LbL films using V2O5 gel as first layer as well as a promising candidate for applications as sensor for ammonia detection in poultry shed.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:46Z No. of bitstreams: 1 S0104-14282007000400014.pdf: 147329 bytes, checksum: 3f893157c74ab6ca6c55c1e6b6861912 (MD5) Made available in DSpace on 2013-08-22T19:01:46Z (GMT). No. of bitstreams: 1 S0104-14282007000400014.pdf: 147329 bytes, checksum: 3f893157c74ab6ca6c55c1e6b6861912 (MD5) Previous issue date: 2007-12-01 Made available in DSpace on 2013-09-30T20:02:07Z (GMT). No. of bitstreams: 2 S0104-14282007000400014.pdf: 147329 bytes, checksum: 3f893157c74ab6ca6c55c1e6b6861912 (MD5) S0104-14282007000400014.pdf.txt: 21104 bytes, checksum: 2e00cd9e8faf5bb60bad2ebe8648ff72 (MD5) Previous issue date: 2007-12-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:22:59Z No. of bitstreams: 2 S0104-14282007000400014.pdf: 147329 bytes, checksum: 3f893157c74ab6ca6c55c1e6b6861912 (MD5) S0104-14282007000400014.pdf.txt: 21104 bytes, checksum: 2e00cd9e8faf5bb60bad2ebe8648ff72 (MD5) Made available in DSpace on 2014-05-20T13:22:59Z (GMT). No. of bitstreams: 2 S0104-14282007000400014.pdf: 147329 bytes, checksum: 3f893157c74ab6ca6c55c1e6b6861912 (MD5) S0104-14282007000400014.pdf.txt: 21104 bytes, checksum: 2e00cd9e8faf5bb60bad2ebe8648ff72 (MD5) Previous issue date: 2007-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Nesse trabalho descrevemos a arquitetura e a operação de filmes finos de polianilina (PAni) usados como elemento ativo de sensores flexíveis de pH e de deformação mecânica. Tais dispositivos apresentam grande interesse tecnológico devido aos seus baixos custos de produção e à possibilidade de integração com outros sistemas orgânicos e inorgânicos, incluindo transistores, diodos e baterias. Filmes finos de PAni foram preparados pelo método de polimerização in-situ sobre microeletrodos de Cr/Au previamente depositados sobre substratos de polietilenoteraftalato (PET). As características elétricas do sistema foram investigadas como função do nível de dopagem da PAni. Os dispositivos apresentaram boa resposta elétrica para diferentes soluções ácidas e básicas, bem como para pequenas variações de deformações mecânicas. In this work we describe the design and operation of thin polyaniline (PAni) films as active material for strain gauge and pH-monitoring flexible electronic devices. These devices are interesting due to their low cost and possible integration with other organic or inorganic systems, including diodes, transistors and batteries. Thin PAni films were prepared using the in-situ polymerization method on interdigitated chromium-gold microelectrodes previously deposited on poly(ethylene terephthalate) - PET substrates. The electrical characteristics of the polymer devices were obtained as a function of the PAni doping level. The devices showed high sensitivity for small strains and acid/base solutions. UFOP Departamento de Física EPUSP Departamento de Engenharia de Sistemas Eletrônicos UNESP Faculdade de Ciências e Tecnologia UNESP Faculdade de Ciências e Tecnologia

The alternating conductivity, σ *( f ) = σ ′( f ) + iσ ″( f ), of in situ polymerized polyaniline thin films doped with hydrochloric acid, deposited on top of an interdigitated gold line array previously deposited on glass substrates, were measured in the frequency ( f ) range between 0.1 Hz to 10 MHz and in the temperature range from 100 to 430 K. The results for σ ′( f ) are typical of a disordered solid material: for frequencies lower than a certain hopping frequency γ hop , log[ σ ′( f )] is frequency-independent rising almost linearly for in log f > γ hop . A master curve was thus obtained by plotting the real component of the conductivity using normalized scales σ ′( f )/ σ dc and f / γ hop , which is indicative of a single process operating in the whole frequency range. An expression encompassing the conduction through a disordered structure taken from previous random free energy barrier model for hopping carriers, as well a dielectric function to represent the capacitive behavior of the PAni was employed to fit the experimental results. The dielectric constant and activation energy for hopping carriers were obtained as function of the polymer doping level.

Complex impedance measurements were used to analyze the influence of ultraviolet and ozone gas on the electronic behaviour of ZnO films grown by rf magnetron sputtering. The data show that UV exposure strongly increases the ac conductivity of the film at very low frequencies, and that after ozone exposure it recovers the original value. At high frequencies, however, UV-light exposure it does not change the conductivity but the ozone acts in the sense to decrease it. Two distinct mechanisms, related to two relaxation time distributions are clearly observed: they are superimposed in the virgin sample, but they split forming two semicircles in the z ″( f ) − z ′( f ) diagrams when the samples are treated with UV and/or ozone gas. A combination of the bruggeman effective medium approximation (BEMA) with the random free energy barrier model is used to fit the data and to explain the ac conductivity variation phenomena observed.

Hybrid organic−inorganic ionic conductors, also called ormolytes (organically modified electrolytes), were obtained by dissolution of LiClO4 in siloxane−poly(propylene glycol) matrixes. The dynamic features of these nanocomposites were studied and correlated to their electrical properties. Solid-state nuclear magnetic resonance (NMR) spectroscopy was used to probe the effects of the temperature and nanocomposite composition on the dynamic behaviors of both the ionic species (7Li) and the polymer chains (13C). NMR, dc ionic conductivity, and DSC results demonstrate that the Li+ mobility is strongly assisted by the segmental motion of the polymer chain above its glass transition temperature. The ac ionic conductivity in such composites is explained by use of the random free energy barrier (RFEB) model, which is in agreement with their disordered and heterogeneous structures. These solid ormolytes are transparent and flexible, and they exhibit good ionic conductivity at room temperature (up to 10-4 S/cm). Co...

This paper describes a new approach to improve the analysis of surface modification of free-standing semiconducting polymer films emerged from the interfacial interaction between aluminium electrode and HCl-doped polyaniline (PANI) films. The Al–PANI–Al structure was prepared by casting PANI/N-methyl-2-pirrolidone onto a glass substrate and then being sandwiched between Al electrodes after immersion in HCl aqueous solutions and then dried. The Al–polymer interface was investigated by means of complex impedance spectroscopy in the frequency domain on HCl-doped PANI films. The dc conductivity of the interfacial layer between the Al and PANI surface exposed to air during the film processing is higher than those obtained with Al and PANI surface exposed to glass. Raman spectroscopy data confirm this evidence. Here, it is speculated that some dissociated chlorine and aluminium-salt-containing species have contributed as ionic carriers increasing the electrical conductivity of the polymer bulk, and by the formation of an Al2O3 thin layer between the Al and PANI films. An equivalent circuit model considering the influence of Al–PANI reactions on the electrical behaviour of the Al–PANI–Al structure was proposed. Additionally, it was demonstrated that the impedance spectroscopy facilitates the identification of interface modification in the Al–PANI–Al films.

Alternating conductivity measurements of polyaniline, in the 1–10 5 Hz range, were carried out in samples under different temperatures. It was observed that for low frequencies the real component, σ'(ƒ), of ac conductivity is frequency-independent, however obeying the relation σ'(ƒ) ∝ ƒ s , beyond a critical value; the imaginary component increases with frequency in the whole measurements frequency range. The Random Free Energy Barrier Model approach was used to explain the experimental results, and from the theoretical-experimental fittings, it was concluded that the temperature acts in the sense of increasing the carrier mobility.