showing 19 related works from this author
Influence of the electrodeposition conditions on the energetics of polypyrrole thin films
2008
The influence of the solvent used for the electrodeposition and that of the dopant anion on the energetics of electrochemically grown polypyrrole were studied by means of a non-destructive optical technique: Photocurrent Spectroscopy. Polypyrrole films doped with the same anion and grown in different solvents, both aqueous and non- aqueous, show the same HOMO-LUMO gap and the same Fermi level location in respect to HOMO. Polypyrrole films doped with different anions in aqueous solutions, present different values of indirect band gap and flat band potential, indicating that dopant anion influences both the defects band and the Fermi level locations.
Amperometric Biosensor and Front-End Electronics for Remote Glucose Monitoring by Crosslinked PEDOT-Glucose Oxidase
2018
Focusing on the interplay between interface chemistry, electrochemistry, and integrated electronics, we show a novel low-cost and flexible biosensing platform for continuous glucose monitoring. The amperometric biosensing system features a planar three-electrode structure on a plastic substrate, and a wireless near-field communication-powered electronic system performing sensor analog front-end, A/D conversion, digital control, and display tasks. The working electrode is made of electropolymerized poly (3,4-ethylenedioxythiophene) film onto a polyethylene terephthalate/gold electrode followed by immobilization of cross-linked glucose oxidase by glutaraldehyde. The advantages offered by such…
Structural Properties and Temperature Behaviour of Optical Absorption Edge in Polycrystalline ZnO:X (Cu,Ag) Films
2013
Silver- and copper-doped ZnO lms were prepared by radio-frequency magnetron sputtering on glass substrates. The in uence of dopants content on the structural, morphological properties as well as on evolution of the optical absorption edge was considered. It has been found that Ag- and Cu-doped ZnO lms are characterized by wurtzite crystalline structure with the preferred direction of crystalline orientation (002). The sizes of grains within the lms were found to be dependent on the type of dopant. The temperature evolution of the optical absorption edge is described by the modi ed Urbach rule that re ects polycrystalline nature of the material. The corresponding parameters concerning electr…
Inhibition of Cor-Ten steel corrosion by “green” extracts of Brassica campestris
2018
Abstract Extract of Brassica campestris was tested as potential corrosion inhibitor for Cor-Ten steel in NaCl and acidic solutions, simulating a marine and an urban-industrial environment, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were performed both in absence and in presence of the extract at room temperature. The surface chemical analysis was investigated by X-ray Photoemission Spectroscopy (XPS), before and after corrosion. Electrochemical results demonstrated that a very small concentration of Brassica campestris extracts can inhibit Cor-Ten corrosion in NaCl solution (inhibition efficiency of 80–84%) better than in acidic solutions. Su…
ELECTRODEPOSITION OF NOVEL POLY(NAPHTHALENEDIIMIDE-QUATERTHIOPHENE) THIN FILMS AND APPLICATIONS IN PLASTIC OPTOELECTRONICS DEVICES
2013
A novel symmetric naphthalenediimide-quaterthiophene derivative (NDIT4d) has been polymerized on different substrates including glassy carbon and ITO/PET electrodes by means of electrochemical methods. XPS and UV-VIS spectroscopy as well as cyclic voltammetry have been employed for characterizing the thin film chemical features, the band gap and the HOMO and LUMO levels. DFT computational studies were in close agreement with the experimental observables also showing intriguing geometrical effects on the band gap energy values. The comparison of the energy levels locations of the electrodeposited poly(naphthalenediimide-quaterthiophene) derivative (e-PNDIT4) and P3HT thin films transferred b…
NLO properties of polythiophenes galvanostatically electrodeposited on ITO glasses
2008
International audience; A study of nonlinear optical properties of ClO4-doped polythiophenes, galvanostatically electrodeposited on ITO glasses, was carried out using second and third harmonic generation measurements. The effect of the oxidation state of the polymeric films was studied by comparing the nonlinear optical response of oxidised and reduced polythiophenes. Reduced polymeric films show higher values of the second and third order susceptibilities and a lower absorbance in respect to the oxidised ones. The morphology of the polythiophene films was studied by scanning electron and atomic force microscopes.
Electrochemical Growth and Physico-Chemical Characterization in Organic Medium of Nb2O5 Thin Films
2008
Investigations about the energetics and the electrical properties of niobium thin film, electrochemically grown, were performed in an organic solution of acetonitrile and lithium perchlorate. The study of the energetics of the Nb2O5/organic solution interface was performed by means of a non-destructive optical technique, photocurrent spectroscopy. By means of this technique, it was possible estimating the value of the flat band potential and locating conduction and valence band. A more cathodic value of flat band potential in respect with acidic solution was found in organic medium. From impedance spectra, the electrical circuit that gives best fitting values is constituted by two resistanc…
Investigation of recovery mechanisms in dye sensitized solar cells
2016
Abstract We study the spontaneous recovery phenomenon displayed by solar cells sensitized with a ruthenium complex-based dye N719, which manifests with the increase over the time (from several minutes up to some days) of the short circuit current density J sc and the open circuit voltage V oc , during cell illumination. Under dark conditions the current decreases over time after the application of forward bias voltages. We investigate the effects of temperature and electrolyte composition by means of current–voltage measurements and electrochemical impedance spectroscopy, both under dark and illumination conditions. The main result is that the recovery of the performances depends on the cha…
Behaviour of Nb2O5/PPy contacts: From Schottky barriers to p-n junctions
2009
In this work, a study of the photoelectrochemical responses of Nb O /PPy contacts fabricated in both organic 2 5 and aqueous solutions is performed. From the comparison between the experimental data of PPy photodeposited on Nb O in organic and in aqueous solutions, it is evident that the medium used for the photodeposition 2 5 influences the absorption coefficient, the band gap and flat band potential values.
Influence of Ag, Cu dopants on the second and third harmonic response of ZnO films
2009
International audience; Silver- and copper-doped ZnO films were prepared by radio-frequency (RF)-magnetron sputtering on glass and quartz substrates. The influence of dopants content on the microstructural evolution and optical as well as nonlinear optical (NLO) properties were investigated. It has been found that the grain sizes were enlarged with increasing of Ag, Cu dopants amount in ZnO films. The Ag or Cu doping leads to the optical band gap narrowing. Besides, the second-order NLO response of Ag- and Cu-doped ZnO films is lower than that of undoped ZnO film. The second harmonic generation (SHG) efficiency of the ZnO:Ag film was found to be higher than that of the ZnO:Cu film at the si…
ZnO Thin films doped with Erbium: Elaboration, Characterization and nonlinear optical properties measurements
2011
In this paper, we investigate NLO properties of ZnO nanostructures for optoelectronics applications. It is shown that carefully designed and fabricated nanostructured ZnO films posses some advantageous for practical use and to generate more and short wavelengths and, when combined with TiO , produce a core–shell structure that 2 reduces the combination rate. The limitations of ZnO-based DSCs are also discussed and several possible methods are suggested in order to expand the basic knowledge of ZnO to TiO , motivating further improvement 2 in the power-conversion efficiency of third harmonic generation THG.
An insight into the functionalisation of carbon nanotubes by diazonium chemistry: Towards a controlled decoration
2014
The derivatisation of materials including iron, gold, and carbon by addition of diazonium salts is a reliable process to tune their interfacial interaction with the surrounding media. In this regard, the functionalisation of carbon nanostructures by diazonium chemistry is a versatile strategy to obtain soluble nanomaterials with degrees of functionalisation among the highest ever reported. Starting from these premises we have studied the functionalisation of multi-walled carbon nanotubes by addition of the aryl diazonium salts generated in situ by treatment of 4-methoxyaniline with isopentylnitrite. Following a thorough purification and characterisation protocol (UV-vis, TGA, ATR-IR, cyclic…
Quadratic nonlinear optical parameters of 7% MgO-doped LiNbO3 crystal
2016
International audience; Pure and 7% MgO-doped lithium niobate (LiNbO3) single crystals were grown by the Czochralski technique. The shift of optical absorption edge in 7% MgO-doped crystal in direction of shorter wavelength compared to undoped crystal was observed. The second harmonic generation measurements of 7% MgO-doped LiNbO3 crystal were performed at room temperature by means of the rotational Maker fringe technique using Nd:YAG laser generating at 1064 nm in picoseconds regime. Experimentally obtained value of nonlinear optical coefficient d33 for 7% MgO-doped LiNbO3 was found to be less than for undoped crystal but higher than for 5% MgO-doped. I-type phase-matched second harmonic g…
Thiophene pyrenyl derivatives for the supramolecular processability of single-walled carbon nanotubes in thin film heterojunction
2017
Abstract A major problem for the use of single-wall carbon nanotubes (SWCNTs) in electronic devices relates to their poor processability. Chemical modification inevitably introduces defects in the nanotube lattice, resulting in a loss of electronic properties. In this contest, we report on a supramolecular approach with the aim of increasing the dispersion of SWCNTs in solution and in organic semiconductor matrices by ensuring the optoelectronic properties. In particular, new pyrenyl derivatives of thiophene have been synthesized and used to improve the solubility of SWCNTs for electron transfer in thin film heterojunction with poly(3-hexylthiophene) (P3HT) as donor system. Photoinduced ele…
Symmetric naphthalenediimidequaterthiophenes for electropolymerized electrochromic thin films
2015
A new symmetric naphthalenediimidequaterthiophene (s-NDI2ODT4) was synthesized and exhibited the capability to electropolymerize alone or with EDOT affording polymers with controlled donor/acceptor monomer ratios. s-NDI2ODT4-EDOT-based copolymers showed low band gaps, wide optical absorption ranges extending to the near IR region, tuned electrical properties, thin-film surface morphology and hydrophilicity as well as high coloration efficiency in electrochromic devices.
Photoelectrochemical Synthesis of Polypyrrole on Anodic Ta[sub 2]O[sub 5] Films
2007
Polypyrrole film was photoelectrochemically grown on insulating Ta 2 O 5 anodic film in acetonitrile solution. A characterization by photocurrent spectroscopy (PCS) of metal/oxide/polypyrrole interface was carried out. The PCS results suggest that a metallic-like PPy is formed under illumination at constant anodic potential. By polarizing the polypyrrole at cathodic potentials a photocurrent spectrum typical of p-type semiconducting film was recorded. A scanning electron microscopy study of PPy surfaces solution side and oxide side allowed us to obtain information on the morphology of the polymer as well as a rough estimate of the film thickness and of the diameter of PPy globules at the tw…
Electrochemical polymerization of ambipolar carbonyl-functionalized indenofluorene with memristive properties
2019
Abstract Carbonyl-functionalized indenofluorene was electropolymerized with a high faradaic efficiency of 85% and the solid state properties of the resulting polymeric thin films were investigated. They displayed modular optical properties depending on their oxidation state. The approach used for inorganic semiconductors was applied to polyindeonofluorene derivative. Mott-Schottky analysis evidenced a switching from p-type to n-type electrical conduction, suggesting an ambipolar behaviour of the polymer. As an application, flexible organic memristors were fabricated and resistive switching properties were observed.
Novel benzofulvenes-based polymers: Characterization and employment in flexible electrochromic devices
2014
Benzofulvenes-based monomers have been synthesized for the first time and have been polymerized by means of electrochemical methods onto different electrodic materials. Morphological investigation has been performed by using SEM; electrical and optical properties have been studied by means of both cyclic voltammetry, optical absorption and spectroelectrochemical techniques. Finally, solid state electrochromic devices have been fabricated. They have displayed high optical contrast.