Search results for "conduct"

Polythiophene S,S dioxides: an investigation on electrochemical doping

2000

Abstract A new strategy for functionalizing oligothiophenes is the transformation of the thienyl sulphurs into the corresponding S,S dioxides, with the effect of lowering the LUMO energy without significantly affecting the HOMO one. From a quinquethiophene S,S dioxide derivative, a polymer (pQTDO) which can be reversibly n-doped at not very negative potentials still maintaining the property of being p-doped at moderate potential values was electrosynthesized. There is, however, a great difference in the ability to store charge of the polymer’s p- and n-doped forms: a great amount of injected negative charge irreversibly modifies the structure of pQTDO.

Controlling the electronic properties of polythiophene through the insertion of nonaromatic thienyl S,S-dioxide units

1999

A new class of thiophene-based polymers characterized by the presence of one nonaromatic thienyl S,S-dioxide moiety (O) to every two, four, and six aromatic thienyl units (T) was prepared from the newly synthesized precursors TOT, TTOTT, and TTTOTTT, and electrochemically characterized. The polymers displayed remarkably greater electron affinities than that of polythiophene and could be reversibly n-doped at moderate potentials, while still maintaining the property of also being p-doped at moderate potential values. All polymers were characterized by good p-doping/undoping cyclability, while at least four aromatic units to every nonaromatic one were needed to ensure good n-doping/undoping c…

Synthesis of new electroactive polymers by ion-exchange replacement of Mg(II) by 2H+ or Zn(II) cations inside Mg(II) polyporphine film, with their su…

2014

Abstract It has been demonstrated that the treatment of the magnesium polyporphine of type I, pMgP-I, by trifluoroacetic acid in acetonitrile may be used to replace initial central Mg(II) cations inside the monomeric macrocycle units by protons, to get a new electroactive polymer, “free-base polyporphine of type I”, pH2P-I. In its turn, these inserted protons may be replaced by Zn(II) cations via the film treatment with zinc acetate in organic solvent, to get another new electroactive polymer, “zinc polyporphine of type I”, pZnP-I. These changes of central ions inside monomer units manifest themselves by characteristic modifications of their electroactive properties as well as of UV–visible…

A spectroelectrochemical study of poly(dithienothiophenes)

1997

Abstract The use of n- and p-dopable conjugated polymers as both the working and counter electrodes in an electrochemical device has always attracted chemists and has stimulated the design of new molecules with a low energy gap that can be p- and n-doped efficiently. The present paper reports the spectroelectrochemical study of polymers obtained from several dithienothiophene isomers, molecules with three thiophene rings fused in different positions. Of the six isomers, poly(dithieno[3,4-b:3′,2′-d]thiophene) and poly(dithieno[3,4-b:2′,3′-d] thiophene) were tested against poly(dithieno[3,2-b:2′,3′-d]thiophene) and poly(dithieno[3,4-b:3′,4′-d]thiophene). The differences in their performance, …

Functional Hybrid Materials Containing Polypyrrole and Polyoxometalate Clusters: Searching for High Conductivities and Specific Charges

2002

Atomic force microscopy study of conducting polymer films near electrode's edge or grown on microband electrode

2013

Abstract Polypyrrole (PPy) films of different thicknesses (within the range from 200 nm to 2.5 μm) were electrodeposited on two types of inhomogeneous substrates, single band and double-band Pt electrodes. Topographic images of the polymer layers were obtained by means of ex situ large-scale AFM technique to demonstrate how the propagation rates of the film growth above the electrode (in the normal direction to the electrode surface) and along the insulating surface surrounding the single- or double-band electrodes (in the horizontal direction) change with the deposition charge. It is proved that variations in the film thickness over the double band electrodes and progressive changes of the…

Charge dissipation in e-beam lithography with Novolak-based conducting polymer films

2008

Charging of common resist materials during electron beam (e-beam) writing leads to deflection of the electron beam path, which can result in significant pattern displacement. Here we report a new conducting polymer to eliminate charging. A common approach is to place the conducting layer underneath the e-beam resist layer. Conductivity equal or greater than 10(-4) S cm(-1) has been reported to prevent pattern displacement. Some other properties such as a flat surface layer, chemical inertness and insolubility in both the top resist solvent and the developer are also necessary. The way to achieve all these properties consisted in synthesizing a conducting polymer inside an insulating polymer…

Electropolymerization of N-methylanthranilic acid and spectroelectrochemical characterization of the formed film

2009

Abstract The electropolymerization of N-methylanthranilic acid (NMAA) is reported in this paper. The monomer is substituted both at ortho- and N-position and, to the best of our knowledge, it has not been previously electropolymerized. Electropolymerization of NMAA was done on glassy carbon and optically transparent (indium) tin oxide electrodes. The obtained films, which are probably of an oligomeric nature (oligoNMMA), were characterized with cyclic voltammetry (CV), in situ UV–vis and Raman spectroscopy, ex situ FTIR spectroscopy and scanning electron microscopy (SEM). Our results show that NMAA can be electropolymerized as thin films in 1.0 M HClO4, but the oxidation and reduction peak …

Hybrid LEDs based on ZnO nanowire structures

2017

Abstract This paper summarized the research, development, and state of the art of hybrid ZnO nanowire LEDs, in which electroluminescence is generated at the junction between n-type doped ZnO nanowire structures and specific p-type doped polymers (in particular PEDOT, PEDOT:PSS, or PFO). Different device architectures will be reviewed and discussed with a particular emphasis on the electronic transport through the hybrid structures and the microscopic processes of light emission. Finally, a gas-phase deposition technique for conductive polymers will be presented which might help improve the performance of hybrid ZnO nanowire LEDs in the future.

Light-induced demixing of hole or electron transporting moieties

2004

This paper describes the synthesis of two tri-phenylamine monomers (hole conducting) and one triazine monomer (electron conducting) which differ in their copolymerization parameters because of their styrene and vinyl ester nature. A blend of triphenylamine monomer and poly-(ethylene glycol) and mixtures of both types of monomers (triphepylamine and triazine) were illuminated through a line mask, creating laterally modulated radicals, thus leading to lateral demixing. The experiments with mixtures of triphenylamine and triazine monomers show that the concentration of p- or n-type polymers can be modulated laterally in a controlled way.